JP2010152299A - Patterning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform high-accuracy positive/negative reversal through simple steps by depositing a reversal film on a positive pattern and filling the gap in the positive pattern with a reversal film material without damaging the pattern. <P>SOLUTION: The resist patterning method uses positive/negative reversal including the steps of: forming a resist film on a substrate to be processed with a composition for forming a chemically amplified positive resist film containing a resin having an acid-labile group-containing repeating unit and becoming soluble in an alkaline developer when the acid-labile group is eliminated, a photoacid generator or a thermal acid generator, and an organic solvent; obtaining a positive pattern by exposing the resist film to high energy rays with a repeating high density pattern thereby exposing and heating an unexposed part, causing a generated acid to react with the acid-labile group of the resin and subjecting the acid-labile group of the resin of the exposed part to an elimination reaction, and subsequently developing the resin; applying resistance against an organic solvent to the positive pattern by exposing or heating the positive pattern thereby eliminating the acid-labile group of the resin and cross-linking the resin; forming the reversal film; and dissolving and removing the cross-linked positive pattern formed thereon. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In particular, the present invention forms a positive pattern by exposure and development, renders the pattern alkali-soluble by acid and heat, and coats a reversal film slightly soluble in alkali on the pattern. The present invention relates to a pattern forming method capable of simultaneously forming a dense pattern and an isolated pattern in pattern formation using positive / negative reversal in which a negative pattern is formed by dissolving the positive pattern and the positive pattern.

In recent years, with the higher integration and higher speed of LSIs, there has been a demand for finer pattern rules. In the light exposure currently used as a general-purpose technology, the intrinsic resolution limit derived from the wavelength of the light source. Is approaching. As exposure light used in forming a resist pattern, light exposure using g-ray (436 nm) or i-line (365 nm) of a mercury lamp as a light source was widely used in the 1980s. As a means for further miniaturization, a method of shortening the exposure wavelength is effective, and mass production after 64 Mbit (process size is 0.25 μm or less) DRAM (Dynamic Random Access Memory) in the 1990s. In the process, a KrF excimer laser (248 nm) having a short wavelength was used as an exposure light source instead of i-line (365 nm). However, in order to manufacture DRAMs with a density of 256M and 1G or more that require finer processing technology (processing dimension is 0.2 μm or less), a light source with a shorter wavelength is required, and an ArF excimer has been used for about 10 years. Photography using a laser (193 nm) has been studied in earnest. At first, ArF lithography was supposed to be applied from the device fabrication of the 180 nm node, but KrF excimer lithography was extended to 130 nm node device mass production, and full-scale application of ArF lithography is from the 90 nm node. Further, a 65 nm node device is being studied in combination with a lens whose NA is increased to 0.9. The following 45nm node devices which required an advancement to reduce the wavelength of exposure light, F ₂ lithography wavelength 157nm became a candidate. However, the cost of the scanner is increased by using a large amount of expensive CaF ₂ single crystal for the projection lens, the optical system is changed due to the introduction of the hard pellicle because the durability of the soft pellicle is extremely low, and the etching resistance of the resist film is reduced. Due to various problems, it has been proposed to advance F ₂ lithography and early introduction of ArF immersion lithography (Non-patent Document 1: Proc. SPIE Vol. 4690 xxix (2002)).

  In ArF immersion lithography, it has been proposed to impregnate water between the projection lens and the wafer. The refractive index of water at 193 nm is 1.44, and pattern formation is possible even with a lens having an NA (numerical aperture) of 1.0 or more. Theoretically, the NA can be increased to near 1.44. Initially, it was pointed out that the resolution was deteriorated and the focus shifted due to the change in refractive index accompanying the change in water temperature. It was confirmed that the water temperature was controlled within 1/100 ° C. and the influence of the heat generated by the resist film due to the exposure was almost no worry, and the problem of refractive index change was solved. Although it was feared that the microbubbles in the water were transferred to the pattern, it was confirmed that the water was sufficiently degassed and that there was no risk of bubble formation from the resist film due to exposure. In the early stage of immersion lithography in the 1980s, a method was proposed in which all stages were immersed in water, but water was inserted only between the projection lens and the wafer to accommodate the operation of the high-speed scanner, and water was supplied and drained. A partial fill system with a nozzle was adopted. In principle, the lens design with NA of 1 or more became possible by immersion using water, but the conventional optical system with a refractive index system becomes a huge lens, and the lens is deformed by its own weight. There was a problem. A catadioptric optical system has been proposed for a more compact lens design, and a lens design with NA of 1.0 or more has been accelerated. The possibility of a 45 nm node is shown by the combination of a lens with NA 1.2 or higher and strong super-resolution technology (Non-patent Document 2: Proc. SPIE Vol. 5040 p724 (2003)), and further development of a lens with NA 1.35. Has also been done.

  As a lithography technique for the 32 nm node, vacuum ultraviolet light (EUV) lithography having a wavelength of 13.5 nm is cited as a candidate. Problems of EUV lithography include higher laser output, higher resist film sensitivity, higher resolution, lower line edge roughness (LER), defect-free MoSi laminated mask, lower reflection mirror aberration, etc. There are many problems to overcome.

The resolution of a line pattern that can be reached with the highest NA of water immersion lithography using an NA 1.35 lens is a half pitch of 40 to 38 nm, and cannot reach 32 nm. Therefore, development of a high refractive index material for further increasing NA is being carried out. It is the minimum refractive index among the projection lens, liquid, and resist film that determines the limit of the NA of the lens. In the case of water immersion, the refractive index of water is the lowest compared to the projection lens (refractive index of 1.5 for synthetic quartz) and resist film (refractive index of 1.7 for conventional methacrylate), and projection is based on the refractive index of water. The lens NA was fixed. Recently, highly transparent liquids having a refractive index of 1.65 have been developed. In this case, it is necessary to develop a projection lens material having the lowest refractive index and a high refractive index of the projection lens made of synthetic quartz. LUAG (Lu ₃ Al ₅ O ₁₂ ) has a refractive index of 2 or more and is the most promising material, but has a problem of large birefringence and absorption. Even if a projection lens material having a refractive index of 1.8 or more is developed, the NA of the liquid having a refractive index of 1.65 is 1.55, and 35 nm can be resolved, but 32 nm cannot be resolved. In order to resolve 32 nm, a liquid having a refractive index of 1.8 or more and a resist film and a protective film having a refractive index of 1.8 or more are required. The most problematic material with a refractive index of 1.8 or higher is a high-refractive-index liquid. At present, there is a trade-off between absorption and refractive index, and no such material has yet been found. In the case of an alkane compound, a bridged cyclic compound is preferable to a linear compound in order to increase the refractive index. I'm staring. Since the hafnium oxide particles are highly transparent at 193 nm and have a refractive index of more than 2, high refractive index liquids in which this is dispersed in water or an alkane-based solution have been studied. However, in order to disperse hafnium oxide in water and increase the refractive index to 1.8, it is necessary to mix 30% by mass or more. However, since the viscosity of the mixture becomes very high, high-speed scanning is impossible. . Further, when a liquid having a refractive index of 1.8 is developed, since the minimum refractive index becomes a resist film, the resist film needs to have a high refractive index of 1.8 or more.

  Recently, a double patterning process in which a pattern is formed by the first exposure and development and a pattern is formed just between the first pattern by the second exposure (Non-Patent Document 3: Proc.SPIE Vol.5754 p1508 (2005)). Many processes have been proposed as a double patterning method. For example, the first exposure and development form a photoresist pattern with 1: 3 line and space spacing, the lower hard mask is processed by dry etching, and another hard mask is laid on the first hard mask. In this exposure method, a line pattern is formed by exposure and development of a photoresist film in a space portion of the exposure, and a hard mask is processed by dry etching to form a line and space pattern that is half the pitch of the initial pattern. Further, a photoresist pattern having a space and line spacing of 1: 3 is formed by the first exposure and development, the underlying hard mask is processed by dry etching, and a photoresist film is applied thereon to form a hard mask. The remaining space pattern is exposed to the remaining portion and the hard mask is processed by dry etching. In either case, the hard mask is processed by two dry etchings.

  In the above-described method, it is necessary to lay a hard mask twice. In the latter method, only one hard mask is required, but it is necessary to form a trench pattern that is difficult to resolve compared to the line pattern. In the latter method, there is a method of using a negative resist material for forming a trench pattern. This can use the same high contrast light as forming a line with a positive pattern, but the negative resist material has a lower dissolution contrast than the positive resist material. Compared with the case of forming a line, when the trench pattern having the same dimensions is formed with a negative resist material, the resolution is lower when the negative resist material is used. In the latter method, a wide trench pattern is formed using a positive resist material, and then the substrate is heated to shrink the trench pattern, or a water-soluble film is coated on the developed trench pattern. It is possible to apply the RELACS method in which the trench is shrunk by heating and then crosslinking the resist film surface. .

  Even in the former method and the latter method, etching for substrate processing is required twice, so that there is a problem in that throughput is reduced and pattern deformation and positional deviation are caused by the etching twice.

  In order to complete the etching once, there is a method in which a negative resist material is used in the first exposure and a positive resist material is used in the second exposure. There is also a method in which a positive resist material is used in the first exposure and a negative resist material dissolved in a higher alcohol having 4 or more carbon atoms that does not dissolve in the second exposure. In these cases, if a negative resist material with low resolution is used, the resolution deteriorates.

  A method in which PEB (post-exposure bake) and development are not performed between the first exposure and the second exposure is the simplest and high throughput method. In this case, the first exposure is performed, the mask is drawn with a shifted pattern, the second exposure is performed, and PEB, development, and dry etching are performed. However, since the light energy of the first exposure and the light energy of the second exposure are offset, the contrast becomes 0 and the pattern is not formed. In this case, if the acid generation is made non-linear by using a two-photon absorption acid generator or a contrast enhancement film (CEL), the energy offset is relatively small even with exposure shifted by half pitch, and the amount of shift is low but low contrast. It has been reported that a pattern having a half pitch can be formed (Non-patent Document 4: Jpn. J. App. Phys. Vol. 33 (1994) p6874-6877, Part 1, No. 12B, December 1994).

  The most critical problem in double patterning is the alignment accuracy between the first pattern and the second pattern. Since the size of the positional deviation is a variation in the line dimensions, for example, if an attempt is made to form a 32 nm line with an accuracy of 10%, an alignment accuracy within 3.2 nm is simply required. The alignment accuracy of the latest ArF immersion scanner is about 8 to 6 nm for each wafer with the same exposure machine. For each wafer, the resist alignment pattern that has been exposed and developed is aligned by an exposure machine, and this requires a significant improvement. When the first exposure and the second exposure are performed without removing the wafer from the chuck even once, the positional deviation due to the chuck remounting can be canceled, so that the alignment accuracy is improved and becomes about 5 to 4 nm. In the case of double patterning, performing a plurality of exposures without removing the wafer from the chuck can be an exposure method that can be realized to the extent that the alignment accuracy is improved. The exposure that forms a nonlinear energy distribution such as the two-photon absorption resist and halves the pitch is performed by shifting the exposure position by ¼ of the pitch without removing the wafer from the chuck. There has not yet been reported a nonlinear resist or CEL that is sensitive to exposure at a wavelength of 193 nm, but if this is completed, double exposure that can be performed with a minimum alignment error becomes realistic.

  As a technique for forming not only double patterning but also a thin space pattern or hole pattern, the above-described method using a negative resist, the thermal flow method, and the RELACS method can be cited, but the negative resist has low resolution of the resist itself. There is a problem that a bridge is generated in a minute hole pattern due to the use of a problem and a cross-linking system, and the thermal flow method and the RELACS method have a problem that variations tend to occur at the time of thermal shrinkage.

  Here, FIG. 1 shows a method of forming a hole pattern by exposure using a positive photoresist material. FIG. 1A shows a method in which a photoresist film 102 is applied and formed on a substrate 101 to be processed on the substrate 100. The state (B) shows a state in which the photoresist film 102 is exposed through a photomask on which a desired pattern is formed and then developed to form a photoresist pattern 102a. The substrate 101 to be processed is formed using the photoresist pattern 102a as a mask. The etched state is shown.

  On the other hand, a method of forming a negative pattern by inverting a positive pattern has been well known for a long time. For example, JP-A-2-154266 (Patent Document 1) and JP-A-6-27654 (Patent Document 2). ), A pattern-reversible naphthoquinone resist, a method in which a portion cured by FIB exposure is left by subsequent irradiation (Patent Document 3: JP-A-64-7525), and a naphthoquinone diazide photosensitizer was produced by exposure. A method in which indene carboxylic acid is insolubilized by making it indene by heat treatment in the presence of a base, and positive / negative reversal is caused by overall exposure (Patent Document 4: JP-A-1-191423, Patent Document 5: JP-A-1). -92741) has been proposed. 2A and 2B show this positive / negative reversal method. FIG. 2A shows a state in which a photoresist film 102 is applied and formed on a substrate 101 to be processed on the substrate 100, and FIG. 2B shows a photomask on which a desired pattern is formed. (C) is a state in which the photoresist film 102 is flood-exposed, (D) is a state in which the pattern reversal film 103 is formed by performing pattern reversal by development, and (E). Shows a state in which the substrate to be processed 101 is etched using the pattern reversal film 103 as a mask.

  In addition, in the positive / negative reversal method by changing the developer, a method of obtaining a negative pattern by organic solvent development of hydroxystyrene partially protected with t-BOC (tert-butoxycarbonyl group) or development with supercritical carbon dioxide has been proposed. ing.

  As a positive / negative reversal technique using a silicon-containing material, a positive resist pattern is obtained by covering a space portion of a positive resist pattern with a silicon-containing film and etching it with oxygen gas etching to remove the positive pattern portion to obtain a silicon-containing film pattern. A method of forming a fine hole pattern by performing inversion has been proposed (Patent Document 6: JP 2001-92154 A, Patent Document 7: JP 2005-43420 A). FIG. 3 shows this, in a state where the photoresist film 102 is formed on the substrate 101 to be processed on the substrate 100 via the lower layer film 104, and FIG. 3B shows exposure through a photomask on which a predetermined pattern is formed. The developed photoresist pattern 102a is formed, (C) is the crosslinked photoresist pattern 102a, and (D) is the SOG film 105 formed on the lower layer film 104 so as to cover the crosslinked photoresist pattern 102a. (E) is a state in which light-etching with CMP or CF-based gas is performed to expose the crosslinked photoresist pattern 102a, (F) is a state in which the pattern is inverted by etching with oxygen gas and hydrogen gas, and (G) is a pattern. A state in which the substrate 101 to be processed is etched using the formed SOG film 105a as a mask is shown.

It is difficult to make a hole pattern finer than a line pattern. If a hole pattern mask is combined with a positive resist film in order to form a fine hole by a conventional method, an exposure margin will be extremely narrow. Therefore, a method has been proposed in which a hole having a large size is formed and the hole after development is shrunk by a thermal flow, a RELACS method or the like. However, there is a problem that the control accuracy decreases as the pattern size after development and the size after shrink are large and the shrink amount is large. A positive resist film is used to form a line pattern in the X direction using dipole illumination, the resist pattern is cured, a resist material is again applied thereon, and the line pattern in the Y direction is exposed to light by dipole illumination. A method of forming a hole pattern from a gap of a line pattern (Non-Patent Document 5: Proc. SPIE Vol. 5377 p255 (2004)) has been proposed. A hole pattern can be formed with a wide margin by combining X and Y lines by high-contrast dipole illumination, but it is difficult to etch the line pattern combined vertically with high dimensional accuracy. There has been proposed a method of forming a hole pattern by exposing a negative resist film by combining a Levenson type phase shift mask in the X direction line and a Levenson type phase shift mask in the Y direction line (Non-Patent Document 6: IEEE IEDM Tech. Digest 61 (1996)). However, the bridging negative resist film has a drawback that the critical dimension is larger than that of the positive resist film because the limit resolution of the ultrafine holes is determined by the bridge margin.
When the super-resolution technique is used for a dense repetitive pattern, a coarse / dense (proximity) bias with an isolated pattern becomes a problem. The stronger the super-resolution technology is used, the higher the resolution of dense patterns, but the larger the density bias. In particular, an increase in the density bias in the hole pattern is a serious problem. In order to suppress the density bias, generally, a bias is applied to the dimension of the mask pattern. Since the density bias varies depending on the characteristics of the photoresist material, that is, dissolution contrast and acid diffusion, the density bias of the mask varies depending on the type of the photoresist material. For this reason, masks with different density biases are used for each type of photoresist material, increasing the burden of mask production. Therefore, only the dense hole pattern is resolved with strong super-resolution illumination, a negative resist film of an alcohol solvent that does not dissolve the first positive resist pattern is applied on the pattern, and unnecessary hole portions are exposed and developed. A method (Pack and unpack; PAU method) for producing both a dense pattern and an isolated pattern by blocking is proposed (Non-patent Document 7: Proc. SPIE Vol. 5753 p171 (2005)). Problems with this method include positional misalignment between the first exposure and the second exposure, and the author of the literature points out this point. Further, a hole pattern that is not blocked by the second development is developed twice, and a dimensional change due to this is also a problem.

JP-A-2-154266 JP-A-6-27654 JP-A 64-7525 JP-A-1-191423 JP-A-1-92741 JP 2001-92154 A JP-A-2005-43420 JP 2007-171895 A JP 2006-293298 A

Proc. SPIE Vol. 4690 xxix (2002) Proc. SPIE Vol. 5040 p724 (2003) Proc. SPIE Vol. 5754 p1508 (2005) Jpn. J. et al. App. Phys. Vol. 33 (1994) p 6874-6877, Part 1, no. 12B, December 1994 Proc. SPIE Vol. 5377 p255 (2004) IEEE IEDM Tech. Digest 61 (1996) Proc. SPIE Vol. 5753 p171 (2005)

In the case of forming a very fine space pattern, if a negative resist film is used, there are problems that a fine pattern cannot be formed due to low resolution and that spaces are bridged. The thermal flow method and the RELACS method have a problem that variations tend to occur when shrinking due to heat.
On the other hand, if a negative pattern can be inverted after obtaining a positive pattern with high resolution, the problem caused by using a negative resist film is solved.

As described above, various methods have been reported for inverting a positive image obtained from a positive resist film that provides high resolution into a negative pattern. In particular, Patent Document 7 mentioned above also refers to the case where the silicon-based embedding material for positive / negative reversal is an organic solvent-based composition. In the previous method of using a water-soluble silicon resin for the reversal film forming material, if the organic solvent-based reversal film forming material composition is applied to the substrate on which the positive pattern is formed, the positive pattern is applied. Although there was a possibility that the organic solvent used may collapse, if the resin that forms the resist pattern is cross-linked by curing with EB to give resistance to the organic solvent and insolubilization with the solvent is performed, the inversion of the organic solvent system It is disclosed that a film forming material composition can be used, and the selection range of materials can be greatly expanded. However, when this treatment is performed, the removal of the resist pattern at the final stage for inversion cannot be performed by dissolution because the positive pattern is insolubilized. The method by dry etching must be taken. Therefore, a material that can be selectively dry-etched containing silicon, titanium, or the like must be selected as the inversion film forming material.
The silicon resin applied on the resist pattern is etched back by etching with a fluorocarbon gas or the like to expose the resist pattern on the surface, and the image is inverted by dry etching with oxygen gas and hydrogen gas. Since it is necessary to perform two etchings of etching back and etching and gas exchange in order to invert the image, this method reduces the throughput.

On the other hand, Patent Document 6 discloses that it is advantageous to remove the positive pattern by wet etching. As a method for this, after obtaining the positive pattern, the organic silicon is made of organic silicon without any special treatment. A method of applying a solvent solution to form an inversion film made of organic silicon is disclosed. Further, this document does not mention damage to the positive pattern due to intermixing, and the solvent used for preparing the organic silicon composition is a highly polar solvent (such as propylene glycol monomethyl ether, lactate ester, etc.). It is described that those having a hydroxy group, esters such as propylene glycol monomethyl ether acetate, ketones such as acetone, etc. can be used in the same manner as those having low polarity (for example, toluene, cumene, etc.) In the examples, only examples of toluene and cumene are given. However, as a follow-up to this, for example, a positive type that does not perform any special treatment using a solvent containing a high polarity solvent such as propylene glycol monomethyl ether acetate, ethyl lactate, propylene glycol monomethyl ether, or cyclohexanone as the solvent for the inversion film. When applied on the pattern, the pattern was dissolved by the coating solvent, and positive / negative reversal satisfying the required accuracy could not be performed. Therefore, in this method, only reversal film materials that exhibit high solubility in low-polar solvents can be used, and novolaks, polyhydroxystyrene polymers, and alicyclic polymers containing a large amount of hydroxy groups and lactones. It has been found that a reversal film material having a high concentration of polar groups with high substrate adhesion cannot be employed.
In a logic device pattern in which hole patterns of various pitches exist, a phenomenon (proximity bias) in which the hole size differs for each pitch of the hole pattern occurs due to the proximity effect. In order to reduce the proximity bias, the OPC technique in which correction is performed by changing the mask size for each pitch makes the mask production difficult and increases the time required for mask production. Proximity bias does not occur in dense hole patterns with a constant pitch. Therefore, if a method of exposing dense hole patterns and filling in unnecessary hole patterns later can be used, a hole pattern without a proximity bias can be formed without using OPC. Based on this idea, a positive hole resist film is used to form a dense hole pattern, and an alcohol solvent negative resist is applied on the positive hole film, exposing the unnecessary hole pattern and closing the hole. was suggested. The disadvantage of the PAU method is that the positional deviation becomes large because the wafer is once removed from the exposure chuck for PEB and development after the first exposure. If a positional shift occurs in the second exposure, there is a problem that the hole at the target location cannot be closed. In order to minimize the positional deviation, it is necessary to continuously expose the pattern without removing the wafer from the stage.
Further, in the PAU method, it is necessary to apply a thermal flow method or a RELACS method in order to shrink the hole size in order to shrink the hole size in the first exposure in order to open a hole using a positive resist film. Further, since the negative resist film used for exposure for closing the second hole generally has a lower resolving power than the positive resist film, there is a drawback that the margin is narrower than the hole pattern of the positive resist film.

  The present invention has been made in view of the above circumstances, and provides a method for forming a resist pattern using positive / negative reversal, which can efficiently form both a close hole pattern and an isolated hole pattern with a wide margin. Objective.

  In order to solve the above-mentioned problems, the present inventors have conducted various studies. As a result, by performing a partial cross-linking treatment of the resin for chemically amplified positive resist material in the positive resist pattern, the required resistance to organic solvents is obtained. Can be dissolved in an alkaline wet etching solution, and if the above operation is incorporated into a negative pattern forming method by positive / negative reversal, a conventional silicon film can be used as the reversal film material. It is possible to apply not only materials based on organic materials but also film forming materials for reversal of organic non-silicone resins such as aromatic resins and polycyclic compound resins. Using such a material, a dense dot pattern is exposed with a positive resist film, then an unnecessary dot pattern is exposed and developed to form a dense dot pattern and an isolated dot pattern, and this is positive / negative inverted. As a result, it was found that both a dense hole and an isolated hole can be formed simultaneously, and the present invention has been made.

Accordingly, the present invention provides the following pattern forming method.
Claim 1:
A resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid on the substrate to be processed, which becomes soluble in an alkaline developer by the elimination of the acid labile group, exposure of high energy rays Applying a photoacid generator that generates acid by heating, or a composition for forming a chemically amplified positive resist film containing a thermal acid generator that generates acid by heating, and an organic solvent, and unnecessary by pre-baking A step of forming a resist film by removing an unnecessary solvent, exposing the resist film to a repeated dense pattern of high energy rays, further exposing an unexposed portion of an unnecessary dense pattern, heating after exposure, A process in which an acid generated from an acid generator is allowed to act on an acid labile group of a resin to cause the acid labile group of an exposed portion of the resin to undergo elimination reaction, and then developed with an alkaline developer to obtain a positive pattern , The process The obtained positive pattern is exposed or heated to remove the acid labile group of the resin in the positive pattern by acid or heat to improve alkali solubility, and an alkaline wet etching solution is added to the resin. A step of forming a crosslink within a range not losing solubility in the above, and imparting resistance to the organic solvent used in the film forming composition for reversal to the positive pattern, for reversal using the film forming composition for reversal A method for forming a resist pattern using positive / negative reversal, including a step of forming a film and a step of dissolving and removing the positive pattern on which the cross-linking has been formed with an alkaline wet etching solution.
Claim 2:
The pattern forming method according to claim 1, wherein the exposure of the dense pattern is a single exposure.
Claim 3:
2. The pattern forming method according to claim 1, wherein the exposure of the dense pattern is a double exposure in which a line pattern and a line pattern in a different direction are overlapped.
Claim 4:
4. The pattern forming method according to claim 1, wherein the exposure of the dense pattern is a double exposure of dipole illumination of a horizontal line pattern and a vertical line pattern.
Claim 5:
5. The pattern forming method according to claim 1, wherein the exposure of the dense pattern and the exposure for removing the unnecessary dense pattern are performed on the same exposure stage. 6.
Claim 6:
6. The exposure of dense patterns and the exposure for removing unnecessary dense patterns are continuously performed on the same exposure stage without separating the substrate to be processed from the stage. 2. The pattern forming method according to claim 1.
Claim 7:
The dissolution rate of the cross-linked positive pattern obtained in the step of imparting resistance to the organic solvent used in the reversal film-forming composition to the resist pattern in an alkaline wet etching solution is 2.38 mass% tetramethylammonium hydroxy. When the organic solvent used in the reversal film forming composition is etched with an aqueous solution of TMAH, propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, It is a single or mixed solvent containing at least one selected from propylene glycol monomethyl ether and heptanone, and the resistance to the solvent used in the reversal film forming composition is such that the crosslink formation positive pattern is formed by the reversal film formation. To the solvent used in the composition The method of forming a resist pattern using the positive-negative inversion of any one of claims 1 to 6 thickness loss and has a solvent resistance is 10nm or less when allowed to touch 0 seconds.
Claim 8:
8. The resist pattern formation using positive / negative reversal according to any one of claims 1 to 7, wherein the reversal film-forming composition contains a resin containing a monomer unit having an aromatic skeleton or an alicyclic skeleton. Method.
Claim 9:
Between the step of forming a film for reversal using the composition for forming a film for reversal and the step of dissolving and removing the positive pattern for crosslinking formation with an alkaline wet etchant, the film was laminated on the positive pattern for crosslinking formation. The method for forming a resist pattern using positive / negative reversal according to claim 1, comprising a step of removing the reversal film.
Claim 10:
The method for forming a resist pattern using positive / negative reversal according to claim 9, wherein the step of removing the reversal film laminated on the positive pattern is wet etching.
Claim 11:
The reversal film is a material that has a lower dissolution rate and exhibits solubility than the cross-linked positive pattern after the step of imparting resistance to the organic solvent when treated with an alkaline wet etching solution. 11. The step of removing the reversal film laminated on the crosslink-forming positive pattern and the step of dissolving and removing the positive pattern with the alkaline wet etchant are performed simultaneously using an alkaline wet etchant. A resist pattern forming method using positive / negative reversal as described.
Claim 12:
The positive / negative reversal method according to claim 11, wherein the reversal film has a dissolution rate of 0.02 nm / second or more and 2 nm / second or less when etched with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution. A resist pattern forming method.
Claim 13:
13. The chemical amplification positive resist film forming composition according to claim 1, comprising a component that generates an acid upon heating in a step of imparting resistance to an organic solvent to the resist pattern. Of forming a resist pattern using positive / negative reversal.
Claim 14:
The method for forming a resist pattern using positive / negative reversal according to claim 13, wherein the component generating an acid by heating is a thermal acid generator added separately from the photoacid generator.
Claim 15:
The pattern forming method according to claim 14, wherein the thermal acid generator is represented by the following general formula (P1a-2).
(In the formula, K ⁻ is a sulfonic acid in which at least one α-position is fluorinated, or perfluoroalkylimide acid or perfluoroalkylmethide acid. R ^101d , R ^101e , R ^101f , and R ^101g are each hydrogen. An atom, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group, an oxoalkyl group or an oxoalkenyl group, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, or R ^101d and R ^101e or R ^101d and R ^101e and R ^101f may be bonded to each other by an alkoxy group, part or all of which may be substituted with an alkoxy group. may form a ring together with the nitrogen atom to which they are attached, when they form a ring, R ^101d, R ^101e, or R ^101d, R ^101e and R ^101f are der alkylene group having 3 to 10 carbon atoms Or form a heterocyclic aromatic ring having a nitrogen atom in the formula in the ring.)
Claim 16:
The composition for forming a chemically amplified positive resist film is a positive resist material containing a resin having a repeating unit having a lactone ring as the resin and a repeating unit having an acid labile group that is eliminated by an acid. Item 16. A resist pattern forming method using positive / negative reversal according to any one of Items 1 to 15.
Claim 17:
The method for forming a resist pattern using positive / negative reversal according to any one of claims 1 to 16, wherein the cross-linking is performed by an electrophilic partial structure in the resin.
Claim 18:
The positive resist material is a positive resist material containing a resin having a repeating unit having a 7-oxanorbornane ring and a repeating unit having an acid labile group that is eliminated by an acid. When the acid labile group of the resin in the positive pattern is eliminated by generating and applying heat, the resin crosslinking in the positive pattern and the acid labile group are eliminated simultaneously. Item 18. A resist pattern forming method using positive / negative reversal according to Item 17.
Claim 19:
The method for forming a resist pattern using positive / negative inversion according to claim 18, wherein the repeating unit having a 7-oxanorbornane ring is a repeating unit (a) represented by the following general formula (1).
(In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² is a single bond or a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, and has an ether group or an ester group. may be, the number of 1 to 6 linear carbon atoms, for branched or cyclic alkylene group, the carbon atom linked to the ester group in the formula is a primary or secondary .R ^3, R ⁴ R ⁵ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and a is in the range of 0 <a <1.0.
Claim 20:
The pattern forming method according to any one of claims 16 to 19, wherein the repeating unit having an acid labile group that is eliminated by an acid is a repeating unit (b) represented by the following general formula (2).
(In the formula, R ¹² represents a hydrogen atom or a methyl group, and R ¹³ represents an acid labile group. B is 0 <b ≦ 0.8.)
Claim 21:
The pattern forming method according to claim 20 acid labile group R ¹³ is an acid labile group of alicyclic structure which is eliminated by an acid.
Claim 22:
The method of forming a resist pattern using positive / negative reversal according to any one of claims 1 to 21, wherein the positive pattern includes a dot pattern, and the pattern obtained by the reversal includes a hole pattern.
Claim 23:
23. The positive pattern according to any one of claims 1 to 22, wherein the positive pattern includes both a dense dot pattern and an isolated dot pattern, and the pattern obtained by the inversion includes a dense hole pattern and an isolated hole pattern. A resist pattern forming method using positive / negative reversal.
Claim 24:
The positive pattern exposes a dense dot pattern, exposes an unnecessary dot pattern portion to form a dense dot pattern and an isolated dot pattern, and forms a dense hole pattern and an isolated hole pattern by the positive / negative reversal. The method for forming a resist pattern according to claim 23.
Claim 25:
A chemical amplification positive resist film forming composition containing a resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid is applied onto a substrate to be processed, and unnecessary solvent is removed by heating. Forming a resist film, applying a protective film-forming composition on the resist film, removing unnecessary solvent by heating to form a protective film, water or refractive index between the resist film and the projection lens However, the resist film is subjected to immersion exposure of high-density repetitive dense patterns on the resist film, and the unexposed portions of unnecessary dense patterns are exposed to immersion, and post-exposure heating is caused by exposure. The obtained acid is allowed to act on the acid labile group to cause the acid labile group of the resin in the exposed portion to undergo a elimination reaction, and then developed with an alkaline developer to obtain a positive pattern, thereby obtaining the positive pattern Obtained in the process The composition for forming a film for reversal in the resist pattern is formed by removing the acid labile group of the resin in the resist pattern and forming a cross-link in the resin without losing the solubility in the alkaline wet etching solution. Positive negative reversal including a step of imparting resistance to the organic solvent used in the step, a step of forming a reversal film using the reversal film forming composition, and a step of dissolving and removing the positive pattern with an alkaline wet etching solution. A resist pattern forming method.
Claim 26:
26. The pattern forming method according to claim 25, wherein the composition for forming a protective film is based on a polymer compound obtained by copolymerizing a repeating unit having an amino group.
Claim 27:
27. The pattern forming method according to claim 25 or 26, wherein the protective film material composition contains an amine compound.
Claim 28:
A carbon film with a carbon content of 75% by mass or more is formed on a substrate to be processed, an intermediate film containing silicon is formed thereon, and a photoresist film for positive / negative reversal is coated thereon, for reversal. The pattern forming method according to any one of claims 1 to 27, wherein the film is formed of a hydrocarbon-based material.
Claim 29:
A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, a photoresist film for positive / negative reversal is coated thereon, and the reversal film is formed of a material containing silicon. The pattern forming method according to claim 1, wherein the pattern forming method is a pattern forming method.
Claim 30:
A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, an organic antireflection film is formed thereon, and a positive / negative reversal photoresist film is coated thereon to form a reversal film. 30. The pattern forming method according to claim 29, comprising a material containing silicon.

  According to the present invention, a dense dot pattern is exposed using a positive resist film, and then unnecessary dot patterns are continuously exposed and developed to obtain a dot pattern in which a dense pattern and an isolated pattern are mixed. . Since continuous exposure is performed without removing the wafer chuck from the wafer, a dense dot pattern can be formed with a minimum alignment error. By baking the substrate on which the positive dot pattern is formed at a high temperature, it gives the necessary resistance to the organic solvent used in the composition for forming a film for reversal, and ensures solubility in an alkaline etching solution. A pattern forming method for forming a hole pattern by positive / negative reversal in which a step of finally obtaining a negative image is performed by wet etching with an alkaline etching solution can be provided, whereby not only a silicon-based material but also an aromatic resin can be provided. In addition, it is possible to provide a technique that enables application of an inversion film forming material of an organic non-silicone resin such as a polycyclic compound resin. In addition, it is possible to use a solvent having a hydroxy group or a highly polar solvent such as esters and ketones for preparing the reversal film-forming material composition. It is possible to provide a method of forming a resist pattern using positive / negative reversal, which can form both hole patterns and isolated hole patterns with a wide margin.

  Here, FIG. 4 shows the optical contrast of holes, dots, and lines with a pitch of 90 nm and a pattern size of 45 nm in an NA1.3 lens. Each of the masks is a binary mask using a Cr light shielding band. Line is σ0.98, radius σ0.2 dipole illumination + s-polarized illumination, dot is σ0.98 / 0.735 3/4 zone illumination + azimuthally polarized illumination, hole is σ0.98 / 0.735 3/4 Annular illumination + azimuthally polarized illumination.

  The inclination of the mask edge represents the image contrast, and a larger inclination is advantageous for pattern formation. According to this, the order of high contrast is the order of line pattern, dot pattern, and hole pattern. Since the contrast of the hole pattern is extremely low, pattern formation is difficult even with a very high contrast resist film. The dot pattern has a slightly higher contrast than the hole pattern. The contrast of a line pattern obtained by adding strong s-polarized illumination to dipole illumination, which is stronger oblique incidence illumination, is higher, and the limit resolution is higher than a two-dimensional dot pattern or hole pattern in which strong deformation illumination cannot be used. It has been shown that the formation of fine hole patterns is one of the challenges facing lithography techniques. It is also shown that if the dot pattern is reversed to form a hole pattern, further refinement can be achieved. A dot pattern can be produced by a double dipole method in which an X-direction line pattern is exposed, a Y-direction line pattern is exposed and developed. The dot pattern produced by this method can form a finer pattern than the normal method using a mask provided with a dot pattern.

FIG. 5 shows an optical image of a Y-direction line of NA1.2 lens, dipole illumination, s-polarized pitch 90 nm, and pattern size 45 nm. FIG. 6 shows an optical image of an X direction line having a NA1.2 lens, dipole illumination, a pitch of 90 nm with s-polarized light, and a pattern size of 45 nm. The darker one is the light-shielding part and the white one is the strong light area. FIG. 7 is a contrast image in which the optical image of the X direction line is superimposed on the Y direction line. The combination of X and Y lines seems to produce a grid-like image, but this is not the case, and the pattern of the weak light part is circular. When the size of the circle is large, it is easy to connect to the adjacent pattern with a rhombus shape, but it is shown that the degree of circle improves as the size of the circle decreases.
Based on the optical image image of FIG. 7, the resist film pattern shape simulation was performed in FIGS. Here, in the Z direction, the logarithm of the dissolution rate of the resist film is reciprocal, which reflects the pattern shape of the resist film. 8 to 10 show different amounts of exposure. In FIG. 8, the amount of exposure is small, the dot pattern is rhombus, and the patterns are connected. In FIG. 9, the dots are finished in a substantially circular shape, and the size of the dots at this time is about 40 nm. FIG. 10 shows a case where finer dots are formed by increasing the exposure amount, and the dot size at this time is about 20 nm. When a hole is formed by a normal method using a positive resist film, if a hole having a pitch less than half is formed, a hole having a size smaller than 1: 1 is formed by underexposure in a 1: 1 hole. Therefore, the light contrast is lowered, and the exposure amount margin and the roundness are lowered. When forming a 1: 1 dot using a positive resist film, a dot having a size of 1: 1 or less improves light contrast due to overexposure rather than a half (1: 1) or more of the pitch. In addition, the roundness is improved and the exposure amount margin is widened. This method shows that it is possible to form a considerably small dot with a wide margin. If a hole pattern can be formed by image inversion using such a dot pattern, a fine hole can be formed without using a thermal technique such as thermal flow or RELACS.
When trying to form a hole pattern in which a dense pattern and an isolated pattern coexist, a dimensional difference (proximity bias) between the dense hole and the isolated hole occurs. When the proximity bias is increased, one of the patterns is not formed. When oblique incidence illumination such as annular illumination, cross pole illumination, dipole illumination or the like is used, the resolution of the dense pattern is improved, but there is a problem that proximity bias increases.
11 and 12 show X and Y line double dipole masks. FIG. 13 shows a mask pattern for erasing unnecessary dot patterns. In FIG. 14, dots formed by X and Y double dipoles are superimposed on a dot erasure mask pattern. FIG. 15 shows a dot pattern formed by this, and FIG. 16 shows a hole pattern formed by positive / negative reversal.

  As a method for forming a dot pattern, in the case of forming a circular dot, a method of exposing a dense line in the X direction and a dense line in the Y direction perpendicular to the dense line in the X direction is most preferable. In the case of forming an elliptical dot that is long in the X direction, the exposure is performed with a wider space in the Y direction. When producing oblique dots, the lines in the X and Y directions are overlapped obliquely. It is possible to form a repeated dot pattern of various shapes and directions using two lines.

  The pattern forming method of the present invention forms dots of the same size by repeated dot pattern exposure, so that no proximity bias is generated even if a dot pattern having a random pitch is formed by subsequent dot erasure exposure.

In the PAU method described above, a positive resist film is used to form a dense hole by the first exposure, and a negative resist material dissolved in alcohol or water that does not dissolve the positive resist film is coated on the dense hole. Erase the required hole pattern. This also forms a dense pattern with uniform dimensions first, so that no proximity bias is generated. In the PAU method, since the first exposure exposes the hole pattern, the resolution is not improved as compared with the normal exposure method, and only the proximity bias is eliminated.
However, in the pattern forming method of the present invention, since the dot pattern is formed by the double dipole of the high contrast line pattern, the resolution is greatly improved.

  According to the present invention, on a positive pattern, a composition for forming a film for reversal is applied by applying a solvent containing a hydroxy group-containing solvent, an ester or a solvent containing a highly polar solvent such as ketones. Even if a film is formed, the reversal film forming material can be embedded in the gap of the positive pattern without damaging the positive pattern, and the positive pattern obtained from the positive resist material is wet etched. Therefore, high-precision positive / negative reversal can be performed with a simple process. Furthermore, it is possible to use an organic material for the reversal film, which has not been able to achieve selectivity with the resist pattern by dry etching using oxygen, which is a conventional resist pattern removal method. Furthermore, such as resin materials whose adhesion is improved by having hydroxy groups, especially polar groups such as phenolic hydroxy groups and lactone skeletons, such as solvents having high hydroxyl groups, ketones, and esters. A material that is difficult to dissolve unless a polar solvent is contained can be used for the inversion film. In this case, for example, in order to process the silicon oxide film by the conventional method, the inverted pattern had to be further transferred to the organic film and then the silicon oxide film had to be processed. It becomes possible to process directly.

In addition, when a reversal film having an appropriate alkali dissolution rate is used as the reversal film, a step of removing the reversal film laminated on the positive pattern and a step of wet etching the positive pattern are performed. It can also be performed simultaneously, and the process can be greatly simplified.
By reversing the image of the positive pattern to the negative pattern using this method, it is possible to invert and form a fine space pattern of the same size using the first fine line pattern. An ultrafine trench pattern can be formed by forming a line pattern capable of forming a finer pattern from the trench pattern by exposure, and using this as a trench pattern by the image inversion technique. A hole pattern can also be formed by inverting the dot pattern. Further, after forming a line pattern as the first pattern, a second line pattern orthogonal to the line pattern is exposed and developed to form a dot pattern, and a film having an appropriate alkali dissolution rate is applied thereon and developed. By forming a hole pattern by image reversal, it is possible to form a finer hole pattern than conventional holes.
For applications such as logic devices in which dense patterns and isolated patterns are mixed, a positive resist in which dense and isolated dot patterns are mixed by exposing dense patterns and then exposing unexposed portions of unnecessary dense patterns Get a pattern. A pattern in which dense holes and isolated holes are mixed can be formed by reversing the positive and negative of this by the above method.

It is sectional drawing explaining the method of forming a hole pattern by exposure using a positive photoresist material as a conventional method, (A) is formation of a photoresist film, (B) is exposure and development of a photoresist film. , (C) shows a state where the substrate to be processed is etched. Sectional drawing explaining the image reversal method using the positive i line | wire and g line | wire resist material of a quinonediazide- novolak resin as a conventional method, (A) is formation of a photoresist film, (B) is a photoresist film | membrane. Exposure and heating, (C) shows flood exposure, (D) shows pattern reversal by development, and (E) shows a state where the substrate to be processed is etched. Sectional drawing explaining the image reversal method by the hardening of the resist film after image development, and embedding of an SOG film as a conventional method, (A) is formation of a photoresist film, (B) is exposure and development of a photoresist film (C) is cross-linking of the photoresist film, (D) is SOG film coating, (E) is light etching with CMP or CF gas, (F) is pattern inversion with oxygen gas or hydrogen gas etching, and (G) is covered. In this state, the processed substrate is etched. The optical contrast of holes, dots, and lines with a pitch of 90 nm and a pattern size of 45 nm in an NA1.3 lens is shown. The light intensity when using a Y direction line, dipole illumination, s-polarized illumination, and 6% halftone phase shift mask with an NA 1.2 lens is shown. The darker the color, the weaker the light intensity. The light intensity when an X direction line, dipole illumination, s-polarized illumination, and 6% halftone phase shift mask with a NA1.2 lens are used is shown. The darker the color, the weaker the light intensity. FIG. 7 shows the light intensity of double dipole exposure in which the Y direction line of FIG. 5 and the X line of FIG. The darker the color, the weaker the light intensity. A resist shape simulation in the case of performing double dipole illumination exposure with an NA 1.2 lens is shown. The Z-axis is a reciprocal of the logarithm of the resist dissolution rate, and shows the dot pattern resist shape. The exposure amount at this time is 10 mJ / cm ² . It is a resist shape simulation result when the exposure amount is 15 mJ / cm ² . It is a resist shape simulation result when the exposure amount is 40 mJ / cm ² . It is a top view of a Y line mask showing a double dipole mask. It is a top view of an X line mask which shows a double dipole mask. This is a mask pattern for erasing unnecessary dot patterns. The shading part is shown in black. It is the figure which overlapped the dot (black is left pattern) formed with a double dipole, and the dot erasure mask. A double dipole and a dot erasing mask are exposed and developed to create a dot pattern. It is a hole pattern formed by positive / negative reversal. It is sectional drawing explaining the pattern formation method of this invention, (A) is the state which formed the to-be-processed substrate and the resist film on the board | substrate, (B) is the state which exposed and developed the resist film, (C) Is a state where the resist pattern is deprotected and cross-linked with acid and heat, (D) is a state where a pattern reversal film is applied, (E) is a state where a pattern reversal film is developed and positive / negative is reversed, F) shows a state in which the substrate to be processed is etched using a positive / negative pattern. 2A and 2B show dot forming and dot erasing masks used in one embodiment of the present invention, in which FIG. 1A is a dense 1: 1 dot forming mask and FIG. 2B is an unnecessary dot erasing mask. The dot forming mask and the dot erasing mask used in the same example are shown, and (C) is a diagram in which (A) and (B) are overlapped. The dot forming and dot erasing masks used in this example are shown, wherein (D) is a 1: 1 dot pattern formed after development, and (E) is a 1: 3 dot pattern. 2A and 2B show a double dipole mask for dot formation and an X direction line and a mask for dot erasing used in another embodiment of the present invention, and FIG. Is a 1: 1X direction line forming mask. The dot forming Y direction line and X direction line double dipole masks and dot erasing masks used in this example are shown, and FIG. 8C shows an unnecessary dot erasing mask. A double dipole mask for dot formation Y and X direction lines and a mask for dot erasing used in the same example are shown, and (D) is a diagram in which (A), (B), and (C) are superimposed. is there. The color of the light-shielding part in (C) is made darker, and the difference between (A) and (B) is clarified. The dot forming Y direction line and X direction line double dipole masks and dot erasing masks used in this example are shown, wherein (E) is a 1: 1 dot pattern formed after development, and (F) is 1 : 3-dot pattern.

In order to form a dense hole pattern and an isolated hole pattern at the same time, generally circular illumination (normal illumination) is used. In the circular illumination, the resolution of the dense pattern is reduced as compared with the modified illumination that allows light to pass through the outer periphery of the condenser lens, but the dimensional difference between the dense pattern and the isolated pattern is reduced. However, even if circular illumination is used, although not as much as modified illumination, a dimensional difference (dense / dense bias) occurs between a dense hole and an isolated hole. For this purpose, a method of preliminarily applying a density bias (OPC) to the mask is selected. The density bias depends on the type of resist (difference in acid diffusion distance and dissolution contrast), baking temperature and time (especially the temperature and time of PEB). Therefore, in addition to the bias of the optical image, a bias due to resist characteristics and process temperature conditions must be taken into account. For this reason, the amount of calculation of OPC becomes enormous, the time required for the calculation is prolonged, and the mask cost is increased. In addition, when performing small σ exposure with the condenser lens aperture stopped to reduce OPC due to the optical image, the resolution of the dense pattern is lowered compared to normal illumination.
The PAU method in which a dense hole pattern is formed with a positive resist film, a negative resist film that is soluble in alcohol or water that does not dissolve the positive resist film is coated thereon, and only unnecessary holes are exposed. There is an advantage that no bias occurs. However, since the wafer is removed from the chuck and exposed twice, the alignment accuracy is lowered and the target hole cannot be exposed, and a negative resist film having a low resolving power such as a bridge margin is used, so the margin of the second exposure is narrow. There is a problem.
The method of exposing a dense hole pattern using a negative resist film and then exposing unnecessary hole portions can be continuously exposed without removing from the wafer chuck, so alignment accuracy is improved, but resolution is improved. Since a negative resist having a low thickness is used, a defect that a minute hole is blocked by a bridge occurs.
As described above, several attempts have been made to form a pattern which is optically disadvantageous by using positive resist material with high resolution and using positive resist material as it is. I came. The challenge overcome in this development process is how to form a new film without collapsing the obtained pattern when forming a reversal film on the positive pattern once formed. One of them is good. In order to solve this problem, an aqueous composition in which a positive pattern is not dissolved is used as a reversal film forming composition at first, but the reversal film material is extremely water-soluble. For this reason, Patent Document 7 proposes to form a reversal film after the positive pattern is crosslinked by EB cure and insolubilized in a solvent or a developer. Another problem is how to selectively remove the positive pattern with respect to the inversion film. However, as disclosed in Patent Document 7, this can be achieved by dry etching with oxygen on the inversion film. Selective removal has been carried out by using resistant SOG and organic silicone materials.

  On the other hand, the resist film as shown in Patent Document 7 is cross-linked and insolubilized by irradiation with high energy light when the chemically amplified resist film is irradiated with too high irradiation energy in the early stage of development of the chemically amplified resist material. It was known as a phenomenon. That is, when the polyhydroxystyrene unit, which is a component constituting the chemically amplified resist polymer, is irradiated with intense light, the hydrogen radical of methine bonded with a phenyl group is eliminated, and the resulting radical causes crosslinking between the resins. This is a phenomenon in which the resin is insolubilized. It is considered that the generation of radicals that cause this cross-linking formation is not limited to the styrene skeleton but also occurs in the polyacrylic acid skeleton, and the same cross-linking is considered to occur in methylene bonded to a hetero atom. However, the present inventors observed that the insolubilization of the resist film by this cross-linking formation is not insolubilized at a stretch when light irradiation is performed stepwise, but is insolubilized through a point where the dissolution rate is slightly reduced, I thought about its use. In other words, the decrease in dissolution rate initially observed is considered to be the effect of forming intramolecular or intermolecular crosslinks within a limited range, and when the crosslinks are limited within a limited range, Tolerance to organic solvents such as coating solvents can be obtained without losing speed completely. Then, without completely losing the dissolution rate with respect to such an alkali developer, the production of a pattern resistant to an organic solvent that is generally used as a solvent for a film-forming composition was examined. Have found that a simple pattern is feasible.

  If the method of imparting resistance to an organic solvent without completely losing the solubility in an alkaline developer in a positive pattern as described above is incorporated into a method of forming a resist pattern using positive / negative reversal, the following A pattern forming method for inverting a positive pattern to a negative pattern is possible. That is, according to a normal method for obtaining a positive pattern, first, a chemically amplified positive resist composition is applied and then pre-baked to obtain a resist film. Next, after performing pattern exposure, heating is performed after the exposure to remove the acid labile group of the resin in the exposed portion, thereby rendering the exposed portion soluble in alkali development. Further, development with an alkali developer is performed to obtain a positive pattern. Next, the positive pattern obtained here is subjected to a step of imparting resistance to the organic solvent used in the reversal film-forming composition without completely losing the dissolution rate in the above-mentioned alkaline developer. Next, the reversal film-forming composition, which is the organic solvent solution, is applied to a substrate on which a positive pattern having resistance to the organic solvent used in the reversal film-forming composition is formed. Form. At this time, the inversion film is applied so as to completely fill the gaps in the positive pattern, but the film may be formed in a form laminated to some extent on the positive pattern. In such a case, as described in Patent Literature 6 and Patent Literature 7, after the step of forming the inversion film, the step of removing the inversion film stacked on the pattern is performed, and then the positive pattern Is removed with an alkaline wet etching solution, only the reversal film where there was no positive pattern remains, and a reversal film pattern in which positive / negative is reversed is obtained. The alkaline wet etching solution is for dissolving the positive pattern, and the concentration may be adjusted as necessary, but a developer for obtaining the positive pattern can be used.

  In the method of forming a resist pattern using positive / negative reversal according to the process of the present invention, it is not necessary to use conventional dry etching with oxygen to remove the positive pattern, and the operation can be greatly simplified. Further, according to this method, the inversion film is an ordinary organic film such as an antireflection film made of an aromatic organic polymer material or an organic underlayer film used in a multilayer resist method, particularly well known to those skilled in the art. A resin containing a large amount of units having an aromatic skeleton, such as a novolak resin (for example, Patent Document 8: JP-A-2007-171895), a polystyrene resin, a vinyl ether system containing an anthracene ring or a naphthalene ring Alternatively, an organic film (for example, Patent Document 9: Japanese Patent Laid-Open No. 2006-293298) containing an acrylic resin or a resin having a multi-branch (so-called aliphatic polycyclic skeleton) as used in an ArF resist is inverted. It can be used as a coating film. Of course, if these reversal films have a difference in dissolution rate from the positive pattern to an etching selectivity with respect to an alkaline wet etchant, they form a bridge during film formation like an antireflection film. Even those that are insolubilized in an organic solvent may be those that are not so insolubilized. If these organic material films are used, the reversal film pattern obtained by reversal is directly used as an etching mask for processing metal silicon or silicon oxide substrates in the same way as conventional organic resist patterns. it can. As is well known, if an organic inversion film as described above is used, the metal silicon is not only silicon oxide but also silicon nitride, silicon nitride oxide, titanium oxide, titanium nitride, germanium oxide. It is also possible to process a film or a substrate with an object, hafnium oxide.

  In addition, if a reversal film having an alkali solubility as described below is used, the conventional dry etching is used in the reversal film removal step laminated on the positive resist pattern. It is possible to remove with an alkaline wet etching solution without using the method according to 1 and the peeling method with an organic solvent. Therefore, when this method is adopted, the reversal film and the resist pattern laminated on the resist pattern can be simultaneously removed by a single operation, so that the process can be greatly shortened as a whole. The

  As described above, the reversal film is coated by imparting resistance to the organic solvent used in the reversal film forming composition to the positive pattern without completely losing the solubility in the alkaline wet etching solution. The positive pattern is prevented from being deformed or collapsed by dissolution, but as described above, it can be performed by irradiation with a high energy ray having an appropriate energy amount. However, the present inventors have found that cross-linking formation by light or irradiation is difficult to control due to problems with the allowable range of irradiation dose and uniformity of irradiation. By using a resist material having a unit capable of forming a crosslink under a strong reaction condition such as a lactone skeleton by heating in the presence of an acid, in particular, it is possible to perform cross-linking limited to give the above-mentioned organic solvent resistance. It has been found that when the obtained positive pattern is used, control as intended can be performed relatively easily.

  The process of imparting resistance to the organic solvent used in the composition for forming a film for reversal without losing the solubility in the alkaline wet etching solution due to the heat described above is the amount of acid to be generated depending on the material to be used, or heating. Although the optimum power temperature value is different, the resist pattern forming method of the present invention can be easily implemented by setting the conditions according to the following guidelines. That is, an acid is generated in the film by applying heat after irradiation with high energy rays such as light and EB (electron beam) in an appropriate range for the resist film to be used, or only by heating, and using it. The acid labile group of the resin is eliminated to provide solubility in an alkaline solution. At this time, partial crosslinking is simultaneously formed by light or heat, and resistance to the organic solvent used in the composition for forming a film for reversal is given. The standard of solubility to be given above is that the etching rate exceeds 2 nm / second when etching is performed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution usually used for alkali development of a resist film. It is preferable. Further, the resistance to the solvent used in the reversal film-forming composition is preferably 30 seconds, more preferably, the resist pattern after the resistance (crosslinking) treatment is applied to the solvent used in the reversal film-forming composition. If the film loss when touched for 60 seconds is 10 nm or less and gives a certain degree of solvent resistance, the pattern obtained from the positive resist film will cause fatal damage when the above reversal film is applied. Therefore, it is possible to prevent the occurrence of a problem that a pattern reversed to a negative shape having a desired shape cannot be obtained. In determining the processing conditions, the alkaline wet is applied to the bulk film subjected to resist coating, pre-baking, and post-exposure heating while omitting only the pattern exposure for forming the positive pattern in the above-described series of steps. Without using the solubility in the etching solution, the above two dissolution rates can be easily achieved by using the conditions that are candidate processes for imparting resistance to the organic solvent used in the composition for forming a film for reversal. can get.

  In addition, the organic solvent used in the composition for forming a film for reversal that the present invention can be used particularly effectively dissolves the organic polymer material having the adhesive group described above, and has excellent coating properties. The above-mentioned solvent having a hydroxy group, esters, ketones, etc., specifically, it contains at least one selected from propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, propylene glycol monomethyl ether and heptanone. It is a single solvent or a mixed solvent. Furthermore, you may add C3-C10 alcohol, toluene, xylene, anisole, etc. to these solvents. Therefore, as a standard for giving resistance to the organic solvent used in the composition for forming a film for reversal described above, it is 30 seconds, more preferably 60%, with respect to a single solvent or a mixed solvent selected from among them. Any film having a film thickness of 10 nm or less when touched for a second and having a certain degree of solvent resistance can be used universally and is particularly preferable.

  In the above heat treatment, when partial crosslinking is performed by irradiation with high energy rays, the reaction performed by heating is only the decomposition of the acid labile group, so the post-exposure heating used to obtain the positive pattern Heating at a temperature of or slightly lower than that is sufficient. However, when high energy rays are not used, or when high energy rays are used for the main purpose of generating acid, that is, using the same amount of energy as pattern exposure in the previous process, crosslinking is a reaction caused mainly by heat. In the case of forming by resist, it is preferable to set a temperature higher than the pre-bake temperature and the post-exposure heating temperature used when forming the resist film. In the case of a material in which this temperature is set lower than the heating in the previous process, there is a risk that the resolution itself of the positive resist film is lowered.

This positive / negative reversing method can be advantageously used in the following cases. That is, the positive pattern can form a finer pattern depending on the overexposure amount. Therefore, for example, although it is extremely difficult to form an isolated space (trench pattern) below the exposure limit, a pattern thinner than the normal exposure limit is formed using overexposure, and this is reversed by the method of the present invention. As a result, a very thin trench pattern can be formed.
Furthermore, although a fine hole pattern is more technically difficult than a trench pattern, a fine dot pattern is formed by overexposure, and this is reversed by the method of the present invention, so that a very small hole is formed. It becomes possible to form.

  As a typical example of the present invention, a material having a slight solubility in an inversion film in an alkaline wet etching solution (substantially synonymous with an alkaline developer used for developing a resist pattern, hereinafter also referred to as an alkaline developer). The present invention will be described in more detail using the case of using.

The pattern forming method of the most preferred embodiment of the present invention comprises a repeating unit having an acid labile group that is eliminated by an acid, preferably having an alicyclic structure, and the acid labile group is eliminated and further crosslinked. A positive resist material containing a high molecular compound (base resin) having a dissolution rate with respect to an alkaline developer of the cross-linked product obtained above of 2 nm / second is applied onto a substrate to form a resist film, and high energy after heat treatment A desired portion of the resist film is exposed with a line, and after the heat treatment, the resist film is developed with the alkali developer to form a resist pattern. Thereafter, an acid is generated in the resist pattern and heat is applied to remove the acid labile group of the polymer compound in the resist pattern and to crosslink the polymer compound. Next, a reversal film having a dissolution rate in the range of 0.02 nm / second or more and 2 nm / second or less in the alkali developer is formed on the substrate, and the surface of the film is covered with the alkali developer. While dissolving, the resist pattern is dissolved and lost, and a pattern in which the resist pattern is inverted is formed on the inversion film.
In this case, a dot pattern can be formed as a resist pattern, and this can be reversed to form a hole pattern.

  The crosslinking is formed by an electrophilic partial structure such as an ester group or a cyclic ether in the resin. By the acid and heating, the cross-linking reaction proceeds by reactions such as transesterification, lactone ring opening and esterification and etherification, and cyclic ether ring opening and etherification and esterification.

  The polymer compound used for the base resin of the positive resist material used in the pattern forming method according to the present invention is a repeating unit having a lactone ring, particularly a repeating unit having a 7-oxanorbornane ring, preferably What has the repeating unit (a) shown by Formula (1) can be used advantageously. Since this has both an ester group and a cyclic ether in a single repeating unit, the reactivity of the crosslinking reaction is high. Further, this unit is used as an adhesive unit, and the method of the present invention can be preferably applied without adding an additional component to the base resin.

(In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² is a single bond or a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, and an ether group (—O—) or Although it may have an ester group (—COO—), in the case of a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, the carbon atom linked to the ester group in the formula is primary or R ³ , R ⁴ and R ⁵ are each a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and a is in the range of 0 <a <1.0. is there.)

Here, as a C1-C6 alkylene group, a methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, isobutylene group, sec-butylene group, n-pentylene group, isopentylene group, Examples include a cyclopentylene group, an n-hexylene group, and a cyclohexylene group.
Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, isopentyl group, and cyclopentyl group. , N-hexyl group and cyclohexyl group.

The monomer Ma for obtaining the repeating unit (a) represented by the general formula (1) is represented by the following formula. Here, R ^{1 to} R ⁵ are the same as described above.

The monomer Ma is specifically exemplified below.

In the process of the present invention, after the first pattern is formed by exposure and development, an acid labile group is deprotected and cross-linked by acid and heating, and a film (reversal film) having moderate alkali solubility thereon is formed. Apply and develop with alkali.
In the first pattern, a repeating unit having an acid labile group is dissolved in an alkali by deprotection of the acid labile group, and a solvent (a solvent of a material for forming an inversion film) is formed by crosslinking of a 7-oxanorbornane ring. ) Becomes an insoluble film. Therefore, even if a pattern reversal film solution in which the reversal film material is dissolved in an organic solvent is applied on the first pattern, the first pattern does not mix with the pattern reversal film material.
Next, when the surface of the reversal film is dissolved up to the first pattern portion by the treatment with the alkaline developer, the dissolution of the first pattern starts and image reversal occurs.

  When a polymer compound having a repeating unit having oxirane or oxetane is used as the base polymer for resist, the oxirane ring or oxetane ring has a very high rate of cleavage reaction with acid, and therefore, a post-exposure of about 90-130 ° C. Since crosslinking proceeds at the temperature of a resist process such as Jure baking (PEB), it becomes insoluble in alkali and does not function as a positive resist material in the present invention. On the other hand, the 1,4-epoxy bond of the 7-oxanorbornane ring is less reactive in the cleavage reaction with acid than the oxirane ring or oxetane ring, so that the crosslinking does not proceed in the heating temperature region with PEB. The repeating unit having a 7-oxanorbornane ring is stable to an acid in the process until development, and exhibits a function for improving adhesion and alkali solubility as a hydrophilic group. However, the acid generated by flood exposure or heating of the pattern after development and heating at 170 ° C. or higher cause the 1,4-epoxy bond of the 7-oxanorbornane ring to open and the crosslinking reaction proceeds, making it insoluble in the solvent. At the same time, deprotection of the acid labile group of the repeating unit having the acid labile group occurs by acid and heat, and alkali solubility increases. In order to generate an acid, a thermal acid generator may be added to the resist material, or the entire pattern after development may be irradiated with ultraviolet rays having a wavelength of 400 nm or less.

  The base resin used for the positive resist material used in the pattern forming method of the present invention includes a crosslinkable repeating unit (a) represented by the general formula (1) and an acid instability represented by the following general formula (2). It is preferable to use a polymer compound containing the repeating unit (b) having a group.

(In the formula, R ¹² represents a hydrogen atom or a methyl group, and R ¹³ represents an acid labile group. B is in the range of 0 <b ≦ 0.8.)

Here, the monomer Mb for obtaining the repeating unit (b) represented by the general formula (2) is represented by the following formula.
(In the formula, R ¹² and R ¹³ are as described above.)

In the general formula (2), various acid labile groups represented by R ¹³ are selected. In particular, groups represented by the following formulas (AL-10) and (AL-11), The tertiary alkyl group shown, the C4-C20 oxoalkyl group, etc. are mentioned.

In formulas (AL-10) and (AL-11), R ⁵¹ and R ⁵⁴ are monovalent hydrocarbon groups such as linear, branched or cyclic alkyl groups having 1 to 40 carbon atoms, particularly 1 to 20 carbon atoms. Yes, it may contain heteroatoms such as oxygen, sulfur, nitrogen and fluorine. R ⁵² and R ⁵³ are each a hydrogen atom or a monovalent hydrocarbon group such as a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and includes heteroatoms such as oxygen, sulfur, nitrogen and fluorine. However, a5 is an integer of 0 to 10, particularly 1 to 5. R ⁵² and R ⁵³ , R ⁵² and R ⁵⁴ , or R ⁵³ and R ⁵⁴ are bonded to each other to form a ring having 3 to 20 carbon atoms, particularly 4 to 16 carbon atoms together with the carbon atom or carbon atom and oxygen atom to which they are bonded, An alicyclic ring may be formed.
R ⁵⁵ , R ⁵⁶ , and R ⁵⁷ are each a monovalent hydrocarbon group such as a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, and include heteroatoms such as oxygen, sulfur, nitrogen, and fluorine. But you can. Alternatively, R ⁵⁵ and R ⁵⁶ , R ⁵⁵ and R ⁵⁷ , or R ⁵⁶ and R ⁵⁷ are combined to form a ring having 3 to 20 carbon atoms, particularly 4 to 16 carbon atoms, particularly an alicyclic ring, together with the carbon atom to which they are bonded. May be.

  Specific examples of the compound represented by the formula (AL-10) include tert-butoxycarbonyl group, tert-butoxycarbonylmethyl group, tert-amyloxycarbonyl group, tert-amyloxycarbonylmethyl group, 1-ethoxyethoxycarbonyl. Examples include a methyl group, 2-tetrahydropyranyloxycarbonylmethyl group, 2-tetrahydrofuranyloxycarbonylmethyl group and the like, and substituents represented by the following general formulas (AL-10) -1 to (AL-10) -10. .

In the formulas (AL-10) -1 to (AL-10) -10, R ⁵⁸ is the same or different linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, aryl having 6 to 20 carbon atoms. Group or a C7-20 aralkyl group is shown. R ⁵⁹ represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. R ⁶⁰ represents an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms. a5 is as described above.

  Examples of the acetal compound represented by the formula (AL-11) are (AL-11) -1 to (AL-11) -34.

  In addition, examples of the acid labile group include a group represented by the general formula (AL-11a) or (AL-11b), and the base resin may be intermolecularly or intramolecularly crosslinked by the acid labile group. .

In the above formula, R ⁶¹ and R ⁶² represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms. Alternatively, R ⁶¹ and R ⁶² may be bonded to form a ring together with the carbon atom to which they are bonded, and when forming a ring, R ⁶¹ and R ⁶² are linear or branched having 1 to 8 carbon atoms. -Like alkylene group. R ⁶³ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, b5 and d5 are 0 or 1 to 10, preferably 0 or an integer of 1 to 5, and c5 is an integer of 1 to 7. . A represents a (c5 + 1) -valent aliphatic or alicyclic saturated hydrocarbon group, aromatic hydrocarbon group or heterocyclic group having 1 to 50 carbon atoms, and these groups are heteroatoms such as O, S, and N. Or a part of hydrogen atoms bonded to the carbon atom may be substituted with a hydroxyl group, a carboxyl group, a carbonyl group or a fluorine atom. B represents —CO—O—, —NHCO—O— or —NHCONH—.

  In this case, A is preferably a divalent to tetravalent C1-C20 linear, branched or cyclic alkylene group, alkanetriyl group, alkanetetrayl group, or C6-C30 arylene group. These groups may have intervening heteroatoms such as O, S, N, etc., and a part of the hydrogen atoms bonded to the carbon atoms are substituted by a hydroxyl group, a carboxyl group, an acyl group or a halogen atom. Also good. C5 is preferably an integer of 1 to 3.

  Specific examples of the crosslinked acetal groups represented by the general formulas (AL-11a) and (AL-11b) include those represented by the following formulas (AL-11) -35 to (AL-11) -42.

  Next, examples of the tertiary alkyl group represented by the formula (AL-12) include tert-butyl group, triethylcarbyl group, 1-ethylnorbornyl group, 1-methylcyclohexyl group, 1-ethylcyclopentyl group, tert Examples thereof include an amyl group and the like, or groups represented by the following general formulas (AL-12) -1 to (AL-12) -16.

In the above formula, R ⁶⁴ represents the same or different linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. R ⁶⁵ and R ^{67 each} represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. R ⁶⁶ represents an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms.

Further, examples of the acid labile group include groups represented by the following formulas (AL-12) -17 and (AL-12) -18, and the acid containing R ⁶⁸ which is a divalent or higher valent alkylene group or an arylene group. The base resin may be intramolecularly or intermolecularly cross-linked by an unstable group. In the formulas (AL-12) -17 and (AL-12) -18, R ⁶⁴ represents the same as described above, and R ⁶⁸ represents a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, or an arylene group. Further, it may contain a hetero atom such as an oxygen atom, a sulfur atom or a nitrogen atom. b6 is an integer of 1 to 3.

R ⁶⁴ , R ⁶⁵ , R ⁶⁶ , and R ⁶⁷ described above may have a heteroatom such as oxygen, nitrogen, sulfur, etc., specifically, the following formulas (AL-13) -1 to (AL— 13) -7.

  In particular, as the acid labile group of the above formula (AL-12), those having an exo structure represented by the following formula (AL-12) -19 are preferable.

(In the formula, R ⁶⁹ represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. R ^{70 to} R ⁷⁵ and R ^78. And R ⁷⁹ each independently represents a hydrogen atom or a monovalent hydrocarbon group such as an alkyl group which may contain a C 1-15 hetero atom, and R ⁷⁶ and R ^{77 each} represents a hydrogen atom, or R ^70. And R ⁷¹ , R ⁷² and R ⁷⁴ , R ⁷² and R ⁷⁵ , R ⁷³ and R ⁷⁵ , R ⁷³ and R ⁷⁹ , R ⁷⁴ and R ⁷⁸ , R ⁷⁶ and R ⁷⁷ , or R ⁷⁷ and R ⁷⁸ are bonded to each other. May form a ring (particularly an alicyclic ring) together with the carbon atom to which they are bonded, and in this case, those involved in the formation of the ring are alkylene groups that may contain a heteroatom having 1 to 15 carbon atoms, etc. represents a divalent hydrocarbon group. the R ⁷⁰ and R ^79, R ⁷⁶ and R ^79, or R ⁷² and R ⁷⁴ are as bonded to the adjacent carbon to each other Nothing attached without intervention, may form a double bond. The formula also represents enantiomer.)

Here, the following repeating unit having an exo-body structure represented by the general formula (AL-12) -19
JP-A-2000-327633 discloses an ester monomer for obtaining the above. Specific examples include the following, but are not limited thereto. R ¹¹¹ and R ¹¹² each independently represent a hydrogen atom, a methyl group, —COOCH ₃ , —CH ₂ COOCH ₃ or the like.

  Furthermore, examples of the acid labile group of the above formula (AL-12) include an acid labile group having frangiyl, tetrahydrofurandiyl or oxanorbornanediyl represented by the following formula (AL-12) -20.

(In the formula, R ⁸⁰ and R ⁸¹ each independently represent a monovalent hydrocarbon group such as a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. Or, R ⁸⁰ and R ⁸¹ are bonded to each other. Then, an aliphatic hydrocarbon ring having 3 to 20 carbon atoms may be formed together with the carbon atom to which they are bonded, and R ⁸² represents a divalent group selected from flangedyl, tetrahydrofurandiyl or oxanorbornanediyl. ⁸³ represents a monovalent hydrocarbon group such as a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a hetero atom.)

Repeating units substituted with acid labile groups having frangyl, tetrahydrofurandiyl or oxanorbornanediyl
Examples of the monomer for obtaining the are as follows. R ¹¹² is as described above. In the following formulae, Me represents a methyl group, and Ac represents an acetyl group.

The polymer compound serving as the base of the resist material used in the pattern forming method of the present invention preferably has a repeating unit (a) represented by the general formula (1) and a repeating unit (b) represented by the general formula (2). However, the repeating unit (c) derived from a monomer having an adhesive group such as a hydroxy group, a cyano group, a carbonyl group, an ester group, an ether group, a lactone ring, a carboxyl group, or a carboxylic acid anhydride group is copolymerized. May be.
Specific examples of the monomer for obtaining the repeating unit (c) include the following.

  Among the repeating units (c), those having an α-trifluoromethyl alcohol group or a carboxyl group improve the alkali dissolution rate after heating of the pattern after development, and it is preferable to copolymerize them. Examples of the repeating unit having a carboxyl group include the following.

  In the repeating units (a), (b) and (c), the ratio of the repeating units is 0 <a <1.0, 0 <b ≦ 0.8, 0.1 ≦ a + b ≦ 1.0, 0 ≦ c <0.9, preferably 0.1 ≦ a ≦ 0.9, 0.1 ≦ b ≦ 0.7, 0.2 ≦ a + b ≦ 1.0, 0 ≦ c ≦ 0.8. . Note that a + b + c = 1.

  Here, for example, a + b = 1 means that in the polymer compound containing the repeating units (a) and (b), the total amount of the repeating units (a) and (b) is 100 mol with respect to the total amount of all the repeating units. A + b <1 means that the total amount of the repeating units (a) and (b) is less than 100 mol% with respect to the total amount of all the repeating units, and other than the repeating units (a) and (b) It has other repeating units (c).

  The polymer compound serving as the resist base resin used in the pattern forming method of the present invention has a weight average molecular weight in terms of polystyrene by gel permeation chromatography (GPC) of 1,000 to 500,000, particularly 2,000 to 30, 000 is preferred. If the weight average molecular weight is too small, the crosslinking efficiency in the thermal crosslinking after development of the resist material is lowered. If it is too large, the alkali solubility is lowered, and the trailing phenomenon may easily occur after pattern formation.

  Furthermore, in the high molecular compound used as the base resin of the resist material used in the pattern forming method of the present invention, when the molecular weight distribution (Mw / Mn) is wide, a low molecular weight or high molecular weight polymer exists, so that after exposure, There is a possibility that foreign matter is seen on the pattern or the shape of the pattern is deteriorated. Therefore, since the influence of such molecular weight and molecular weight distribution tends to increase as the pattern rule becomes finer, in order to obtain a resist material suitably used for fine pattern dimensions, the multi-component copolymer to be used is obtained. The molecular weight distribution is preferably from 1.0 to 2.0, particularly preferably from 1.0 to 1.5 and narrow dispersion.

  It is also possible to blend two or more polymers having different composition ratios, molecular weight distributions, and molecular weights.

  In order to synthesize these polymer compounds, one method is to heat-polymerize a monomer having an unsaturated bond for obtaining repeating units (a), (b), and (c) by adding a radical initiator in an organic solvent. In this way, a polymer compound can be obtained. Examples of the organic solvent used at the time of polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane and the like. As polymerization initiators, 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2-azobis (2-methylpropionate) ), Benzoyl peroxide, lauroyl peroxide and the like, and preferably polymerized by heating to 50 to 80 ° C. The reaction time is 2 to 100 hours, preferably 5 to 20 hours. As the acid labile group, those introduced into the monomer may be used as they are, or the acid labile group may be once removed by an acid catalyst and then protected or partially protected.

As described above, the positive resist material is applied on a substrate to form a resist film, and after heat treatment, a high energy ray is irradiated and exposed to a desired portion of the resist film. After the heat treatment, an alkali developer is applied. The exposed portion of the resist film is dissolved and developed to form a resist pattern such as a dot pattern, and then an acid is generated in the resist pattern (the unexposed portion due to the high energy rays). The acid labile group of the polymer compound is eliminated (deprotected) and the polymer compound is crosslinked. In the polymer compound, the acid labile group is eliminated and crosslinked, The dissolution rate in the alkali developer is more than 2 nm / second, preferably 3 to 5,000 nm / second, more preferably 4 to 4,000 nm / second. In this case, it is preferable that the reversal film described later has a dissolution rate of 2 to 250,000 times, particularly 5 to 10,000 times the dissolution rate of the alkaline developer.
In order to make the polymer compound have such a dissolution rate, the repeating unit (b) having an acid labile group represented by the general formula (2) is 10 mol% or more and 90 mol% or less in all repeating units. In particular, it is preferably 12 mol% or more and 80 mol% or less.

  The resist material used in the pattern forming method of the present invention includes an organic solvent, a compound that generates an acid in response to high energy rays (acid generator), a dissolution controller, a basic compound, a surfactant, if necessary. Other components can be contained.

The resist material used for pattern formation of the present invention may contain an acid generator, particularly for functioning as a chemically amplified positive resist material. For example, a compound that generates an acid in response to active light or radiation (photoacid generation) Agent). The component of the photoacid generator may be any compound that generates an acid upon irradiation with high energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like. These can be used alone or in admixture of two or more.
Specific examples of the acid generator are described in paragraphs [0122] to [0142] of JP-A-2008-111103.

The resist material of the present invention can further contain any one or more of an organic solvent, a basic compound, a dissolution controller, a surfactant, and acetylene alcohols.
Specific examples of the organic solvent include paragraphs [0144] to [0145] of JP-A-2008-111103, the basic compounds include paragraphs [0146] to [0164], and the surfactants include paragraphs [0165] to [0165]. [0166] Paragraphs [0155] to [0178] of JP-A-2008-122932 are disclosed as dissolution control agents, and paragraphs [0179] to [0182] of acetylene alcohols are described.

  Further, a thermal acid generator of ammonium salt as a photoresist material is added in an amount of 0.001 to 20 parts by mass, preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the base resin of the photoresist material. It is also possible to generate an acid. In this case, the generation of acid, the crosslinking reaction, and the deprotection reaction of the acid labile group proceed simultaneously. The heating conditions are preferably 100 to 300 ° C., particularly 130 to 250 ° C. and preferably 10 to 300 seconds. As a result, a resist film which is dissolved in an alkali and has characteristics necessary for positive / negative reversal unnecessary for a solvent and improved in mechanical strength to prevent the pattern from being deformed by heating is formed.

In addition, as a thermal acid generator of the said ammonium salt, what is shown by the following general formula (P1a-2) is mentioned.
(In the formula, K ⁻ is a sulfonic acid in which at least one α-position is fluorinated, or perfluoroalkylimide acid or perfluoroalkylmethide acid. R ^101d , R ^101e , R ^101f , and R ^101g are each hydrogen. An atom, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group, an oxoalkyl group or an oxoalkenyl group, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, or R ^101d and R ^101e or R ^101d and R ^101e and R ^101f may be bonded to each other by an alkoxy group, part or all of which may be substituted with an alkoxy group. may form a ring together with the nitrogen atom to which they are attached, when they form a ring, R ^101d, R ^101e, or R ^101d, R ^101e and R ^101f are der alkylene group having 3 to 10 carbon atoms Or form a heterocyclic aromatic ring having a nitrogen atom in the formula in the ring.)

Specific examples of K ⁻ include perfluoroalkanesulfonic acids such as triflate and nonaflate, imide acids such as bis (trifluoromethylsulfonyl) imide, bis (perfluoroethylsulfonyl) imide, and bis (perfluorobutylsulfonyl) imide. , Methido acids such as tris (trifluoromethylsulfonyl) methide, tris (perfluoroethylsulfonyl) methide, and sulfonate having a fluoro substituted at the α-position represented by the following general formula (K-1), And sulfonates in which the α-position shown in -2) is fluoro-substituted.

In General Formula (K-1), ^R102 represents a hydrogen atom, a linear, branched or cyclic alkyl group or acyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or 6 to 6 carbon atoms. 20 aryl groups or aryloxy groups, which may have an ether group, an ester group, a carbonyl group or a lactone ring, or a part or all of the hydrogen atoms of these groups may be substituted with fluorine atoms Good. In General Formula (K-2), R ¹⁰³ represents a hydrogen atom, a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an aryl having 6 to 20 carbon atoms. It is a group.

  Furthermore, a polymer compound having an amino group and a fluoroalkyl group as repeating units can be added. By aligning the polymer compound on the resist surface after coating, it is possible to prevent film loss of the resist pattern after development and to improve the rectangularity. If film loss occurs in the dot pattern after development, image reversal may not be successful. Addition of the following polymer compound is effective for preventing pattern loss. In this case, the addition amount of the following polymer compound is 0.01 to 20 parts by mass, preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of the resist base polymer.

(In the above formula, R ⁰¹ , R ⁰⁴ and R ⁰⁷ each independently represents a hydrogen atom or a methyl group. X ′, Y ′ and Y ″ each independently represents a single bond, —O—R ⁰⁹ —, —C ( ═O) —O—R ⁰⁹ — or —C (═O) —NH—R ⁰⁹ —, a linear or branched alkylene group having 1 to 4 carbon atoms, or a phenylene group, where R ⁰⁹ is carbon number. 1 to 10 linear, branched or cyclic alkylene groups, which may have an ester group (—COO—) or an ether group (—O—), n ′ is 1 or 2, When n ′ = 1, Y ′ is a single bond, —O—R ⁰⁹ —, —C (═O) —O—R ⁰⁹ — or —C (═O) —NH—R ⁰⁹ —, 4 is a linear or branched alkylene group or a phenylene group, and R ⁰⁹ is as described above, and when n ′ = 2, Y ′ is —O—R ^{010 ═} , —C (═O). -O-R ⁰¹⁰ = ^or- C (═O) —NH—R ⁰¹⁰ =, a group in which one hydrogen atom is further removed from a linear or branched alkylene group having 1 to 4 carbon atoms, or one more hydrogen atom is removed from a phenylene group R ⁰¹⁰ is a group in which one hydrogen atom is further removed from a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, and has an ester group or an ether group. R ⁰² and R ⁰³ are the same or different hydrogen atoms, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms, a hydroxy group, an ether A group, an ester group, a cyano group, an amino group, a double bond, or a halogen atom, or an aryl group having 6 to 10 carbon atoms, and R ⁰² and R ⁰³ are bonded to form a bond. A ring having 3 to 20 carbon atoms may be formed together with the nitrogen atom to perform R ⁰⁵ A linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, R ⁰⁶ is bonded to a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group or a difluoromethyl group, or R ⁰⁵ to form R ⁰⁵ , R ⁰⁶ and the carbon atom to which they are bonded may form an alicyclic ring having 2 to 12 carbon atoms, and the ring has an ether group, an alkylene group substituted with fluorine, or a trifluoromethyl group. R ⁰⁸ is a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, substituted with at least one fluorine atom, and an ether group, an ester group, or a sulfonamide group. 0 <(a-1) <1.0, 0 ≦ (b-1) <1.0, 0 ≦ (b-2) <1.0, 0 <(b-1) + (B-2) <1.0, 0.5 ≦ (a−1) + (b−1) + (b−2) ≦ 1.0 is there. )

  On the other hand, as the reversal film, a film having a dissolution rate in the alkaline developer used in the reversal process according to the present invention of 0.02 nm / second to 2 nm / second, preferably 0.05 nm / second to 1 nm / second is used. To do. If the dissolution rate is slower than 0.02 nm / second, the inversion film does not dissolve up to the top of the first resist pattern, so that the pattern inversion is not performed or the surface layer of the inverted pattern becomes a head. If it is faster than 2 nm / second, there is a disadvantage that the remaining film of the inversion film is reduced or the hole size of the inversion pattern is increased.

  In this case, in particular, in order to dissolve the film surface appropriately during development to form a trench pattern, the alkali dissolution rate is adjusted to a dissolution rate in the range of 0.05 nm / second to 1 nm / second. If the dissolution rate is faster than this, the film loss during development increases, and if the dissolution rate is slow, the film surface does not dissolve and the trench pattern becomes empty. In order to adjust the dissolution rate appropriately, a unit having an alkali dissolution rate of 1 nm / second or more and a unit of 0.05 nm / second or less are copolymerized and the copolymerization ratio is optimized to obtain a material having an optimal dissolution rate. can do.

  A film (inversion film) having a dissolution rate in the range of 0.02 nm / second or more and 2 nm / second or less in the alkaline developer used in the pattern forming method of the present invention may be a material made of hydrocarbon or silicon. It may be a material. A material based on a polymer having a phenolic hydroxy group, α-trifluoromethylhydroxy group, or carboxyl group is preferably used. As the silicon-containing material, a material having silanol in addition to the alkali-soluble group is preferably used. Examples of the polymer having a phenolic hydroxy group include a cresol novolak resin, a phenol low nucleus, a bisphenol low nucleus, a bisphenol novolak resin, a bisnaphthol low nucleus, a bisnaphthol novolak resin, calixarenes, calixresorcinol, polyhydroxy Styrene, polyhydroxyvinylnaphthalene, polyhydroxyindene and its copolymer, carboxystyrene polymer, carboxyvinylnaphthalene and its copolymer, α-trifluoromethylhydroxy group-containing styrene polymer and its copolymer, methacrylic acid and Examples thereof include a carboxyl group-containing (meth) acrylate polymer and a copolymer thereof, an α-trifluoromethylhydroxy group-containing (meth) acrylate polymer and a copolymer thereof.

  In this case, the alkali dissolution rate of the polymer consisting only of the repeating unit having a phenolic hydroxy group, α-trifluoromethylhydroxy group, and carboxyl group is almost 1 nm / second or more. Copolymerizes with units having a speed of 0.05 nm / sec or less. Examples of the unit having an alkali dissolution rate of 0.05 nm / second or less include a phenolic hydroxy group, an α-trifluoromethylhydroxy group, a hydrogen atom of a hydroxyl group of a carboxyl group, an alkyl group having 1 to 20 carbon atoms, and a carbon number of 3 -20 alkenyl group, C6-C20 aryl group, C1-C20 acyl group, or the substituent substituted by an acid labile group is mentioned. Or, styrenes, indene, indole, chromone, coumarone, acenaphthylene, norbornadiene, norbornenes, vinylnaphthalene, vinylanthracene, vinylcarbazole, vinyl ethers, lactone-containing (meth) acrylates, hydroxy group-containing (meth) acrylates Can be mentioned.

  More specifically, the material for obtaining the polymer for the inversion film specifically has an alkali-soluble group such as a phenolic hydroxy group, a carboxyl group, or an α-trifluoromethylhydroxy group. In order to adjust the alkali dissolution rate, partial protection of the alkali-soluble group, combination with a hardly alkali-soluble group, or the like may be necessary.

  Specific examples of the material having a phenolic hydroxy group include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol 4-t-butylphenol, resorcinol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, catechol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3- Propylphenol, 4-propyl Pyrphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, pyrogallol, thymol, isothymol, etc. in the presence of aldehydes And novolak resin. Examples of the polymer of the compound having a polymerizable olefin having a phenolic hydroxy group include hydroxystyrene, hydroxyvinylnaphthalene, hydroxyvinylanthracene, hydroxyindene, hydroxyacenaphthylene, and polymers of monomers shown below. .

  A polymer of a monomer for obtaining a repeating unit having a carboxyl group can also be used as a material for forming the inversion film. Specific examples of the monomer include the following.

For partial protection of the phenolic hydroxyl group or carboxyl group for adjusting the alkali dissolution rate, the hydrogen atom of the hydroxyl group of the hydroxyl group or carboxyl group is replaced by an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Substitution with an aryl group having 6 to 20 carbon atoms, an acetyl group, a pivaloyl group, or an acid labile group is preferable.
Examples of the acid labile group include those described above.

  In order to adjust the alkali dissolution rate, it is possible to copolymerize alkali-insoluble repeating units. As the alkali-insoluble repeating unit, (meth) acrylate of alkyl group or aryl group ester, (meth) acrylate having hydroxy group or lactone, styrene, vinyl naphthalene, vinyl anthracene, vinyl pyrene, vinyl carbazole, indene, acenaphthylene, norbornene , Repeating units derived from norbornadienes, tricyclodecenes, tetracyclododecenes.

As the base polymer for forming the inversion film, a resin containing a monomer unit having an aromatic skeleton or an alicyclic skeleton, particularly a material comprising a hydrocarbon, particularly those containing a hydrocarbon having an aromatic group. preferable.
As the material having silicon as the inversion film material, a silicon polymer based on silsesquioxane is preferably used from the viewpoint of etching resistance. In silsesquioxane, silanols in which a part of the bonds are dissociated exist, and the alkali solubility necessary as an inversion film can be obtained by silanol.

In addition, it is preferable that the polystyrene conversion weight average molecular weight by GPC of the said base polymer is 1,000-200,000, especially 1,500-100,000.
The dispersity (Mw / Mn) is preferably 1.0 to 7.0, particularly preferably 1.02 to 5.0.

  As the film forming material for reversal, in addition to the above base polymer, an alkali slightly soluble material for pattern reversal, an alkali-soluble surfactant for improving surface alkali dissolution rate, an alkali-soluble etching resistance improver, basic A quencher, a solvent, etc. can be used.

  Further, examples of the alkali-soluble material for pattern reversal include phenol groups, malonic acid-substituted fullerenes, and phenolic compound low nuclei. These materials have a high carbon content and also have a function of improving etching resistance. The pattern reversal material may be used alone or in a blend of two or more.

  Specific examples of such materials include phenol compounds disclosed in JP-A-2006-259249, JP-A-2006-259482, JP-A-2006-285095, and JP-A-2006-293298, and JP-A-2007-199653. Bisnaphthol compounds described in the above publication, fluorene compounds having the following phenol groups, 4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′dimethyl-4,4 ′-(9H-fluorene-9- Ylidene) bisphenol, 2,2′diallyl-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′difluoro-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2, 2'diphenyl-4,4 '-(9H-fluorene-9-ylidene) bisphenol 2,2′dimethoxy-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, tetrahydrospirobiindene compound, 2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene -6,6'-diol, 3,3,3 ', 3'-tetramethyl-2,3,2', 3'-tetrahydro- (1,1 ')-spirobiindene-6,6'-diol 3,3,3 ′, 3 ′, 4,4′-hexamethyl-2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-6,6′-diol, 2, 3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-5,5′-diol, 5,5′-dimethyl-3,3,3 ′, 3′-tetramethyl-2, 3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-6,6 - diols, trityl phenol, and the like. These materials can be used as alkali-soluble etching resistance improvers.

  In addition, it is preferable that the addition amount of the said material shall be 0-200 mass parts with respect to 100 mass parts of said base polymers, especially 0-100 mass parts. When mix | blending, it can be 1 mass part or more, Especially 5 mass part or more.

  Improving the alkali solubility of only the surface of the pattern reversal film of the present invention is a trench in which the pattern reversal film covering the top of the positive resist pattern modified to be alkali-soluble is smoothly dissolved and the positive pattern is converted. This is effective for improving the dimensional controllability of patterns and hole patterns. In order to improve the alkali solubility on the surface, an alkali-soluble surfactant, particularly a fluorosurfactant can be added. As the fluorosurfactant, those having at least one of the repeating units (s-1) and (s-2) in the following general formula (3) are preferable.

(In the above formula, R ⁶ and R ⁹ each independently represent a hydrogen atom or a methyl group. N is 1 or 2, and when n = 1, X ₁ is a phenylene group, —O—, —C (= O) —O—R ¹⁴ — or —C (═O) —NH—R ¹⁴ —, wherein R ¹⁴ is a single bond or a linear or branched alkylene group having 1 to 4 carbon atoms, and an ester. In the case where n = 2, X ₁ is a group represented by —C ₆ H ₃ — in which one hydrogen atom is eliminated from the phenylene group, —C (═O) —O—R ¹⁵ ═ or —C (═O) —NH—R ¹⁵ ═, wherein R ¹⁵ is one hydrogen atom removed from a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms. a the group, which may have an ester group or an ether group .R ⁷ is a single bond or a straight, branched or cyclic alkylene group having 1 to 12 carbon atoms, R ⁸ Hydrogen atom, a fluorine atom, to form a methyl group, a trifluoromethyl group or difluoromethyl group, or combine with R ⁷ together with the carbon atoms to which they are attached a 3 to 10 carbon atoms ring (excluding an aromatic ring) The ring may have an ether group, an alkylene group substituted with fluorine, or a trifluoromethyl group, and X ₂ represents a phenylene group, —O—, —C (═O) —O—R. ¹⁶ — or —C (═O) —NH—R ¹⁶ —, wherein R ¹⁶ is a single bond or a linear or branched alkylene group having 1 to 4 carbon atoms, and has an ester group or an ether group. R ¹⁰ is a fluorine atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, substituted with at least one fluorine atom, an ether group, an ester group or good .X ₂ may have a sulfonamide group For Eniren group m is an integer of 1 to 5, when X ₂ is otherwise m is 1.)

The monomer for obtaining (s-1) can be specifically exemplified below.

(Wherein R ⁶ is the same as described above.)

  Furthermore, examples of the monomer for obtaining the repeating unit (s-2) having an alkyl group substituted with fluorine represented by (s-2) in the general formula (3) include the following specific examples. it can.

(Wherein R ⁹ is the same as described above.)

The repeating unit of (s-1) and (s-2) is copolymerized with the above-described alkali-soluble repeating unit having a phenol group or a carboxyl group, or the above-mentioned alkali-soluble repeating unit (s-3). can do.
In this case, the ratio of the repeating units (s-1) and (s-2) is 0 ≦ (s−1) ≦ 1, 0 ≦ (s−2) ≦ 1, 0 <(s−1) + ( s-2) ≦ 1, but preferably 0.1 <(s−1) + (s−2) ≦ 1, more preferably 0.2 <(s−1) + (s−2) ≦ 1. It is. In the case of (s-1) + (s-2) <1, the remaining repeating units are the repeating units of s-3.
In addition, it is preferable that the weight average molecular weight of this alkali-soluble surfactant is 1,000-100,000, especially 2,000-50,000.
The alkali-soluble surfactant acts to increase the speed of positive / negative reversal by covering the surface of the reverse film after coating and increasing the alkali dissolution rate of the surface of the reverse film.

  The addition amount of the alkali-soluble surfactant is preferably 0 to 50 parts by mass, particularly preferably 0 to 20 parts by mass with respect to 100 parts by mass of the base polymer. If the amount is too large, the amount of film loss may be excessive or the etching resistance may be reduced. In addition, when mix | blending, it is preferable to set it as 1 mass part or more.

  As the basic quencher, a basic compound similar to the basic compound described in the positive resist material can be used. That is, a basic compound can be added to the pattern reversal film used in the pattern forming method of the present invention in order to prevent acid diffusion from the resist pattern after development. When phenolic compounds and carboxyl group-containing compounds substituted with labile groups are used, the alkali dissolution rate increases due to acid diffusion from the resist pattern and the deprotection reaction, and the size of the inverted pattern increases. As a result, there is a problem that the film is reduced. In order to prevent this, it is effective to add a basic compound. The basic compound added to the resist material and the pattern reversal film may be the same or different.

The compounding quantity of the said basic compound (basic quencher) is 0-10 mass parts with respect to 100 mass parts of said base polymers, Especially 0-5 mass parts is preferable. In addition, when mix | blending, it is preferable that it is 0.1 mass part or more.
An onium salt acid generator may be added to the material for the inversion film. When a phenol-based material is used as the base polymer of the reversal film material, the addition of the onium salt reduces the alkali dissolution rate due to the dissolution inhibiting effect of the onium salt. Addition of an onium salt is effective for adjusting the alkali dissolution rate.

  As an organic solvent used for the film forming material for pattern reversal used in the pattern forming method of the present invention, in addition to the organic solvent used for the positive resist material, mixing with a positive resist film (resist pattern) is prevented. For this purpose, alcohols having 3 to 10 carbon atoms and ethers having 8 to 12 carbon atoms can also be used. Specifically, n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-amyl alcohol, Neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl 2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-diethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol 2-methyl-3-pentanol, 3-methyl-1-pentanol 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, 1 -Octanol is mentioned.

Examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, di-isobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-t. -One or more types of solvent chosen from amyl ether and di-n-hexyl ether are mentioned.
In addition to the above-mentioned solvents, aromatic solvents such as toluene, xylene and anisole can be mixed.

  The amount of the organic solvent used is preferably 200 to 3,000 parts by mass, particularly 400 to 2,000 parts by mass with respect to 100 parts by mass of the base polymer.

In the patterning method according to the present invention, the positive resist material is applied onto a substrate to form a resist film. In this case, as shown in FIG. 17A, in the present invention, a resist film 30 made of a positive resist material is formed directly or via an intermediate intervening layer on the substrate 20 to be processed formed on the substrate 10. The thickness of the resist film is preferably 10 to 1,000 nm, particularly 20 to 500 nm. This resist film is heated (pre-baked) before exposure, and as this condition, it is preferably performed at 60 to 180 ° C., particularly 70 to 150 ° C. for 10 to 300 seconds, particularly 15 to 200 seconds.
As the substrate 10, a silicon substrate is generally used. Examples of the substrate to be processed 20 include SiO ₂ , SiN, SiON, SiOC, p-Si, α-Si, TiN, WSi, BPSG, SOG, Cr, CrO, CrON, MoSi, a low dielectric film, and an etching stopper film thereof. It is done. Examples of the intermediate intervening layer include hard masks such as SiO ₂ , SiN, SiON, and p-Si, a lower layer film made of a carbon film, a silicon-containing intermediate film, and an organic antireflection film.

Examples of the spin-on carbon film include a nortricyclene copolymer described in JP-A No. 2004-205658, a hydrogenated naphthol novolak resin described in JP-A No. 2004-205676, and a naphthol dicyclopentadiene copolymer described in JP-A No. 2004-205665. Coalescence, phenol dicyclopentadiene copolymer described in JP 2004-354554 A, JP 2005-10431 A, fluoreneville phenol novolak described in JP 2005-128509 A, and JP 2005-250434 A Acenaphthylene copolymer, indene copolymer described in JP-A-2006-53543, fullerene having a phenol group described in JP-A-2006-227391, JP-A-2006-259249, JP-A-2006-293 Of the bisphenol compound and the novolac resin described in JP-A-9898, JP-A-2007-316282, the dibisphenol compound described in JP-A-2006-259482, the novolac resin, and the adamantanephenol compound described in JP-A-2006-285095 Novolac resin, hydroxyvinylnaphthalene copolymer described in JP-A-2007-171895, bisnaphthol compound described in JP-A-2007-199653, and this novolac resin, ROMP described in JP-A-2008-26600, JP-A-2008 The resin compound shown by the tricyclopentadiene copolymer of -96684 gazette is mentioned.
Examples of the spin-on silicon-containing intermediate layer include JP-A No. 2004-310019, JP-A No. 2005-15779, JP-A No. 2005-18054, JP-A No. 2005-352104, JP-A No. 2007-65161, and JP-A No. 2007-65161. It preferably contains an anti-reflection function, including a silsesquioxane-based silicon compound disclosed in Japanese Patent Application Publication Nos. 2007-163846, 2007-226170, and 2007-226204.

When the reversal film is made of a hydrocarbon-based material, a carbon film having a carbon ratio of 75% by mass or more in order from the top of the work substrate is included between the work substrate and the positive / negative reversal photoresist, and then contains silicon. A film structure for a three-layer resist process for forming an intermediate film is preferable. The carbon film may be formed by spin coating, but may be an amorphous carbon film formed by CVD. The intermediate film containing silicon may be an SOG film formed by spin coating, or a film selected from SiO ₂ , SiN, SiON, and TiN films formed by CVD or ALD. It has both functions as a membrane. In addition, an organic antireflection film may be formed between the silicon-containing film and the resist film for the purpose of preventing tailing and pattern collapse on the substrate and further reducing substrate reflection.
When the reversal film is made of a material containing silicon, a carbon film having a carbon ratio of 75% by mass or more is formed between the substrate to be processed and the resist film for positive / negative reversal, and the resist film is formed thereon. . An organic antireflection film may be formed between the carbon film and the resist film. In this case, the silicon-containing reversal film functions as a hard mask when processing the carbon film.

  Next, exposure is performed. Here, the exposure is most preferably 193 nm exposure using a high energy ray having a wavelength of 140 to 250 nm, and of these, ArF excimer laser. The exposure may be a dry atmosphere in the air or a nitrogen stream, or immersion exposure in water. In the ArF immersion lithography, pure water or a liquid such as alkane having a refractive index of 1 or more and a highly transparent liquid at the exposure wavelength is used as an immersion solvent. In immersion lithography, pure water or other liquid is inserted between a pre-baked resist film and a projection lens. As a result, a lens with an NA of 1.0 or more can be designed, and a finer pattern can be formed. Immersion lithography is an important technique for extending the life of ArF lithography to the 45 nm node. In the case of immersion exposure, pure water rinsing (post-soak) after exposure to remove the water droplet residue remaining on the resist film may be performed, and elution from the resist film is prevented, and the surface lubricity of the film is prevented. In order to increase the thickness, a protective film may be formed on the resist film after pre-baking. As a resist protective film used in immersion lithography, for example, a polymer compound having a 1,1,1,3,3,3-hexafluoro-2-propanol residue that is insoluble in water and dissolved in an alkaline developer is used. A base and a material dissolved in an alcohol solvent having 4 or more carbon atoms, an ether solvent having 8 to 12 carbon atoms, or a mixed solvent thereof is preferable. In this case, the protective film-forming composition is a base composed of a repeating unit (P-1) serving as a base such as a repeating unit having a 1,1,1,3,3,3-hexafluoro-2-propanol residue. In addition to the resin, a resin obtained by copolymerizing a repeating unit (P-2) having a fluoroalkyl group with the base repeating unit (P-1) can be used as the base resin. Specific examples of the repeating unit (P-1) include those obtained from the monomer exemplified in the above (s-1), and specific examples of the repeating unit (P-2) include the above (s-2). Those obtained from the exemplified monomers are mentioned. The ratio of these repeating units (P-1) and (P-2) is 0 <(P-1) ≦ 1.0, 0 ≦ (P-2) <1.0, 0.3 ≦ (P -1) + (P-2) ≦ 1.0, and the weight average molecular weight of the base resin is 1,000 to 100,000, preferably 2,000 to 50,000.

  In addition, when what does not contain a repeating unit (P-2) is used as a base resin, it is preferable to mix | blend an amine compound with the composition for protective film formation. The amine compound can be selected from those detailed as the basic compound. The compounding amount of the amine compound is preferably 0.01 to 10 parts by mass, particularly 0.02 to 8 parts by mass with respect to 100 parts by mass of the base resin. After the photoresist film is formed, pure water rinsing (post-soak) may be performed to extract acid generators or the like from the film surface, or to wash away particles, or to remove water remaining on the film after exposure. Rinse (post-soak) may be performed.

It is preferable to expose so that the exposure amount in exposure is about 1 to 200 mJ / cm ² , preferably about 10 to 100 mJ / cm ² . Next, post-exposure baking (PEB) is performed on a hot plate at 60 to 150 ° C. for 1 to 5 minutes, preferably 80 to 120 ° C. for 1 to 3 minutes.

  Further, 0.1 to 5% by weight, preferably 2 to 3% by weight, using an aqueous developer such as tetramethylammonium hydroxide (TMAH) for 0.1 to 3 minutes, preferably 0.5 to 2 minutes. The target resist pattern 30a is formed on the substrate by development by a conventional method such as a dip method, a paddle method, or a spray method (see FIG. 17B).

  In this case, a dot pattern having a half pitch size of 38 × 38 nm to 100 × 100 nm, particularly 40 × 40 nm to 80 × 80 nm can be formed as the pattern. The size of the dot pattern depends on the NA of the lens of the exposure machine. If an exposure machine with a NA of 1.35 is used, a dot with a half pitch of 38 nm can be formed as the minimum dimension. The dot pattern may have the same length in the vertical and horizontal directions, or one of them may be a long-axis dot pattern with a long length. A method for forming the dot pattern is not particularly limited, but exposure is performed so as to form a first line pattern on the resist film with a high energy beam, and then a second line pattern orthogonal to the first line pattern is formed. The method of adopting a method of forming a dot pattern by exposing and developing this can form the finest half pitch holes.

  When forming a dense pattern and an isolated pattern of random patterns, the dense pattern is exposed, and then exposure for erasing unnecessary dense patterns is performed. The exposure of the erase pattern may be performed after the dense pattern exposure, or may be performed before the dense pattern exposure. The exposure of the erasure pattern may be performed once, but the erasure exposure by the same double dipole exposure is necessary to erase the super-dense pattern formed by the double dipole exposure of the X and Y lines for each repeating unit. For this reason, the erasure exposure may be performed a plurality of times. In addition, since the erase pattern exposure does not require high resolution, immersion exposure is not necessarily required. The mask may be a phase shift mask or a binary mask. The end of the dense pattern generally has a low resolving power and may not be resolved or the pattern size may be small. The exposure of the erase pattern of the present invention is also effective for erasing a pattern in which the size of the end portion is reduced. In some cases, an auxiliary pattern is introduced into the mask in order to prevent a decrease in resolution at the end of the dense pattern. When a pattern smaller than the limit resolution is introduced as an auxiliary pattern, it is not transferred as a resist pattern, but the effect of preventing a decrease in resolution is low. By using a large auxiliary pattern that is transferred as a resist pattern, the auxiliary pattern can be erased by exposure of the erase pattern.

It is desirable that the dense exposure and the erasure exposure be performed with sufficiently high alignment accuracy. Therefore, it is preferable that the exposure is continuously performed without being removed from the wafer chuck. Therefore, a mechanism for performing exposure while replacing a plurality of masks is required on the exposure machine side. A plurality of mask stages are provided, and the plurality of mask stages are previously aligned with respect to the stage, and continuous exposure while exchanging the mask stage is necessary for improving the throughput. When dense exposure is immersion and erasure exposure is dry exposure, the alignment shift increases because of different exposure machines. However, if the exposure is within the range of alignment shift where there is no practical problem, such exposure. The method can also be applied.
Next, baking (PEB) is performed, and a dot pattern is formed by development. A random pitch dot pattern is formed by one development (see FIG. 17B).

Next, the acid labile group of the polymer compound (base resin) in the pattern is eliminated and the polymer compound is crosslinked to form a crosslinked pattern 30b (see FIG. 17C). In this case, acid and heating are required for elimination and crosslinking of the acid labile group of the polymer compound in the resist pattern. In this case, after the acid is generated, deprotection and crosslinking of the acid labile group are simultaneously performed by heating. In order to generate the acid, there is a method in which the photoacid generator is decomposed by flood exposure of the wafer (pattern) after development. The exposure wavelength of the flood exposure is a wavelength of 180 to 400 nm and an exposure amount of 10 mJ / cm ^{2 to 1} J / cm ² . Irradiation with excimer lasers or excimer lamps with wavelengths of less than 180 nm, particularly 172 nm, 146 nm, and 122 nm, not only generates acid from the photoacid generator, but also promotes the crosslinking reaction by light irradiation, and alkali dissolution by excessive crosslinking It is not preferable because the speed is reduced. As the flood exposure wavelength, an ArF excimer laser having a wavelength longer than 193 nm, a 222 nm KrCl excimer lamp, a 248 nm KrF excimer laser, a 254 nm low-pressure mercury lamp, a 308 nm XeCl excimer lamp, and a 365 nm i-line are preferably used. It is also possible to add an ammonium salt thermal acid generator to the positive resist material and generate an acid by heating. In this case, the generation of acid and the crosslinking reaction proceed simultaneously. The heating conditions are 150 to 400 ° C., particularly 160 to 300 ° C., preferably 10 to 300 seconds. As a result, a crosslinked resist pattern insoluble in the solvent of the inversion film forming material is formed. In order to generate an acid by exposure, a new exposure apparatus is required. Therefore, it is preferable to add a thermal acid generator as a resist composition and advance deprotection and crosslinking reaction only by heating.

Next, as shown in FIG. 17D, a reversal film 40 is formed by applying a reversal film forming material so as to cover the cross-linked resist pattern 30b. In this case, the thickness of the inversion film 40 is preferably equal to the height of the resist pattern or in a range of ± 30 nm.
Next, the surface portion of the reversal film 40 is dissolved using the alkaline developer to expose the head of the crosslinked resist pattern 30b, thereby reversing the dissolution rate of the crosslinked resist pattern 30b in the alkaline developer. Since the dissolution rate of the coating film 40 is faster, the crosslinked resist pattern 30b is selectively dissolved and dissolved and disappears, so that the crosslinked resist pattern 30b is reversed on the reversal film 40 as shown in FIG. The inverted pattern 40a is formed. In this case, if the resist pattern is a dot pattern, a hole pattern is formed as an inverted pattern.

  Further, as shown in FIG. 17F, if there is an intermediate intervening layer such as a hard mask using the reverse pattern 40a as a mask, the intermediate intervening layer is etched, and the substrate 20 to be processed is further etched. In this case, the intermediate intervening layer such as a hard mask can be etched by dry etching using a fluorocarbon or halogen gas, and the etching of the substrate to be processed has an etching selectivity with respect to the hard mask. The etching gas and conditions for the etching can be selected as appropriate, and can be performed by dry etching using a gas such as chlorofluorocarbon, halogen, oxygen, and hydrogen. Next, the cross-linked resist film and the second resist film are removed. These removals may be performed after etching of the intermediate intervening layer such as a hard mask. The cross-linked resist film can be removed by dry etching using oxygen, radicals, etc., and the second resist film can be removed in the same manner as above, or an amine solvent, or an organic solvent such as sulfuric acid / hydrogen peroxide solution. It can carry out with stripping solutions, such as.

  EXAMPLES Hereinafter, although a synthesis example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example etc. In addition, a weight average molecular weight (Mw) shows the polystyrene conversion weight average molecular weight by GPC.

[Synthesis example]
As a polymer compound used for the reversal film, each monomer is combined and subjected to a copolymerization reaction in a tetrahydrofuran solvent, crystallized in methanol, further washed with hexane, isolated and dried, and the composition shown below The high molecular compound (Polymer 1) was obtained. The phenol group of the monomer was substituted with an acetoxy group and converted to a phenol group by alkali hydrolysis after polymerization. The composition of the obtained polymer compound was confirmed by ¹ H-NMR, and the molecular weight and dispersity were confirmed by gel permeation chromatography.

Polymer 1
Molecular weight (Mw) = 9,300
Dispersity (Mw / Mn) = 1.88

A film material for pattern reversal was prepared with the composition shown in Table 1 by adding the polymer 1, basic quencher and solvent. To the solvent, 100 ppm of a fluorosurfactant FC-4430 (manufactured by Sumitomo 3M Limited) was added.
A pattern reversal film material was applied to an 8-inch silicon substrate treated with hexamethyldisilazane (HMDS) and baked at 110 ° C. for 60 seconds to form a pattern reversal film having a thickness of 60 nm. This was developed for 30 seconds with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH), the amount of film loss due to development was determined, and the dissolution rate per second was calculated.
The results are shown in Table 1.

PGMEA: Propylene glycol monomethyl ether acetate

Preparation of Positive Resist Material and Composition for Forming an Alkali-Soluble Protective Film Using a polymer compound (resist polymers 1 to 5 and protective film polymer) shown below, a solution dissolved in the composition shown in Tables 2 and 4 below A resist solution and a composition solution for forming a protective film were prepared by filtering through a 2 μm size filter.
Each composition in Tables 2 and 4 is as follows.

Acid generator: PAG1 (see structural formula below)

Resist polymer 1
Molecular weight (Mw) = 8,310
Dispersity (Mw / Mn) = 1.73

Resist polymer 2
Molecular weight (Mw) = 8,500
Dispersity (Mw / Mn) = 1.95

Resist polymer 3
Molecular weight (Mw) = 8,800
Dispersity (Mw / Mn) = 1.94

Resist polymer 4
Molecular weight (Mw) = 7,300
Dispersity (Mw / Mn) = 1.84

Resist polymer 5
Molecular weight (Mw) = 7,200
Dispersity (Mw / Mn) = 1.80

Protective film polymer
Molecular weight (Mw) = 8,800
Dispersity (Mw / Mn) = 1.69

Basic compound: Quencher 1 (see the structural formula below)

Thermal acid generator: TAG 1 to 7 (see the following structural formula)
Organic solvent: PGMEA (propylene glycol monomethyl ether acetate)

Measurement of change in film thickness and alkali dissolution rate by solvent after high-temperature baking A resist material prepared with the composition shown in Table 2 below is spin-coated on a silicon wafer, and baked at 190 ° C. for 60 seconds using a hot plate. The thickness of the film was 150 nm. Dissolve the solvent on the resist film for 30 seconds, then rotate at 2,000 rpm for 30 seconds, shake off the solvent, bake at 100 ° C for 60 seconds to dry the solvent, and change in film thickness after baking at 190 ° C Was determined using a film thickness meter.
Next, the alkali dissolution rate of the resist film after baking at 190 ° C. was determined for the alkali dissolution rate in a 2.38 mass% TMAH aqueous solution using a resist development analyzer RDA-790 manufactured by RISOTEC JAPAN. .
The results are shown in Table 3.

[Example 1, Comparative Example 1]
ArF exposure patterning evaluation (1)
A resist material prepared with the composition shown in Table 2 below is obtained by applying a spin-on carbon film ODL-50 (carbon ratio: 80% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. to 200 nm on a silicon wafer, and a silicon-containing spin-on hard mask SHB. -Spin coating on a substrate for a tri-layer process formed with a film thickness of 35 nm of A940 (silicon ratio 43 mass%), and baking at 100 ° C. for 60 seconds using a hot plate, to reduce the thickness of the resist film 100 nm. A protective film material (TC-1) shown in Table 4 was spin-coated thereon, and baked at 90 ° C. for 60 seconds to make the thickness of the protective film 50 nm.
This is an ArF excimer laser immersion scanner (manufactured by Nikon Corporation, NSR-S610C, NA 1.30, σ 0.98 / 0.65, oblique 45 ° quadrupole illumination aperture 35 °, 6% halftone phase shift mask ) Was used to expose a 60 nm 1: 1 dense dot pattern shown in FIG. In FIG. 18, the light shielding portion is indicated by a black square. Next, a part of the 60 nm 1: 1 dot pattern exposed portion was exposed with a 120 nm 1: 1 dot pattern shown in FIG. 18 (B), and immediately baked (PEB) at 100 ° C. for 60 seconds to obtain 2.38 mass% TMAH. In a portion where development was performed with an aqueous solution for 30 seconds and only the mask of FIG. 18A was exposed, a 1: 1 dot pattern (FIG. 20D) having a size of 60 nm and a pitch of 120 nm was formed. When exposure was performed twice using the masks of A) and FIG. 18B, a 1: 3 dot pattern (FIG. 20E) with a 240 nm pitch was obtained. FIG. 19C is shown as an overlapping view of FIG. 18A and FIG. The dot pattern formed by development was baked at 190 ° C. for 60 seconds to deprotect and crosslink acid labile groups. The pattern reversal film material (RF1) obtained in the synthesis example was applied on the dot pattern so as to have a film thickness of 60 nm, developed with a 2.38 mass% TMAH aqueous solution for 30 seconds, and the dot pattern was imaged into a hole pattern. Inverted. The dimensions of the developed dot pattern, the heated dot pattern, and the image-inverted hole pattern were observed with TDSEM (S-9380) manufactured by Hitachi High-Technologies Corporation.
As Comparative Example 1, the same resist material was applied to the lower layer film and the intermediate film, and ArF excimer laser immersion scanner (Nikon Corporation, NSR-S610C, NA 1.30, σ 0.98 / 0.65, oblique A hole pattern of 60 nm 1: 1 and 1: 3 using a 45 degree quadrupole illumination opening 35 degree, 6% halftone phase shift mask), and immediately baking (PEB) at 100 ° C. for 60 seconds, Development was carried out with a 2.38 mass% TMAH aqueous solution for 30 seconds.
The results are shown in Table 5.

[Examples 2 to 12, Comparative Example 2]
ArF exposure patterning evaluation (2)
A resist material prepared with the composition shown in Table 2 below was formed on a silicon wafer with a spin-on carbon film ODL-50 manufactured by Shin-Etsu Chemical Co., Ltd. having a thickness of 200 nm and a silicon-containing spin-on hard mask SHB-A940 having a thickness of 35 nm. It spin-coated on the board | substrate for film | membrane for a trilayer process, and baked at 100 degreeC for 60 second using the hotplate, and the thickness of the resist film was 100 nm. A protective film material (TC-1) shown in Table 4 was spin-coated thereon, and baked at 90 ° C. for 60 seconds to make the thickness of the protective film 50 nm.
Using an ArF excimer laser immersion scanner (manufactured by Nikon Corporation, NSR-S610C, NA 1.30, σ 0.98 / 0.65, 20-degree dipole s-polarized illumination, 6% halftone phase shift mask) A 1: 1 line and space pattern of 45 nm in the X direction of the first immersion exposure is exposed using the mask shown in FIG. 21A, and the same place is exposed using the mask shown in FIG. , Exposure with the above scanner (NA 1.30, σ 0.98 / 0.65, aperture 20 degree dipole s-polarized illumination, 6% halftone phase shift mask), and the first time using the mask shown in FIG. The conditions shown below (NA 1.30, σ 0.98 / 0.65, 45 ° oblique quadrupole illumination aperture 35 °, 6% halftone phase shift) at the location overlapping the second exposure position. 22), using the mask shown in FIG. 22C, a portion of the first and second exposures were exposed to 90 nm dot, 180 nm pitch patterns, and immediately after the exposure, baked at 100 ° C. for 60 seconds. When developing with a 38 mass% TMAH aqueous solution for 30 seconds and using the masks of FIGS. 21 (A) and 21 (B) twice, the development finish is 1: 1 with a 40 nm and 90 nm pitch. When a dot pattern (FIG. 24E) is obtained and exposure is performed three times using the masks of FIGS. 21A, 21B, and 22C, 1 at a pitch of 40 nm and 180 nm is obtained. : A three-dot pattern (FIG. 24F) was formed. As a diagram in which FIGS. 21 (A), 21 (B), and 22 (C) are overlapped, FIG. 23 (D) in which only the light-shielding portion of FIG. 22 (C) is dark is shown. The acid labile group was deprotected and crosslinked by baking at 190 ° C. for 60 seconds. The pattern reversal film material (RF1) obtained in the synthesis example was applied on the dot pattern so as to have a film thickness of 60 nm, developed with a 2.38 mass% TMAH aqueous solution for 30 seconds, and the dot pattern was imaged into a hole pattern. Inverted. The dimensions of the image-inverted hole pattern were observed with TDSEM (S-9380) manufactured by Hitachi High-Technologies Corporation.
As Comparative Example 2, the same resist was applied to the lower layer film and the intermediate film, and an ArF excimer laser immersion scanner (manufactured by Nikon Corporation, NSR-S610C, NA 1.30, σ 0.98 / 0.65, oblique 45 45 nm 1: 1 and 1: 3 hole patterns were exposed using a quadrupole illumination aperture of 35 degrees, 6% halftone phase shift mask), and immediately baked (PEB) at 100 ° C. for 60 seconds. Developed with a 38 mass% TMAH aqueous solution for 30 seconds.
The results are shown in Table 6.

PGMEA: Propylene glycol monomethyl ether acetate

From the results of Table 5, in the pattern forming method of Example 1, the 1: 1 and 1: 3 hole patterns were opened with the same size, whereas in the conventional method (Comparative Example 1), the 1: 1 hole was formed. Was opened, but the 1: 3 hole was not opened.
From the results of Table 6, in the pattern forming methods of Examples 2 to 12, both 1: 1 of 45 nm / 90 nm pitch and 1: 3 hole of 45 nm / 180 nm pitch were opened with the same dimension, In the conventional method (Comparative Example 2), holes with a pitch of 90 nm were not opened.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 10 Substrate 20 Substrate 30 Resist film 30a Resist pattern 30b Cross-linked resist pattern 40 Reverse film 40a Reverse pattern

Claims (30)

  A resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid on the substrate to be processed, which becomes soluble in an alkaline developer by the elimination of the acid labile group, exposure of high energy rays Applying a photoacid generator that generates acid by heating, or a composition for forming a chemically amplified positive resist film containing a thermal acid generator that generates acid by heating, and an organic solvent, and unnecessary by pre-baking A step of forming a resist film by removing an unnecessary solvent, exposing the resist film to a repeated dense pattern of high energy rays, further exposing an unexposed portion of an unnecessary dense pattern, heating after exposure, A process in which an acid generated from an acid generator is allowed to act on an acid labile group of a resin to cause the acid labile group of an exposed portion of the resin to undergo elimination reaction, and then developed with an alkaline developer to obtain a positive pattern , The process The obtained positive pattern is exposed or heated to remove the acid labile group of the resin in the positive pattern by acid or heat to improve alkali solubility, and an alkaline wet etching solution is added to the resin. A step of forming a crosslink within a range not losing solubility in the above, and imparting resistance to the organic solvent used in the film forming composition for reversal to the positive pattern, for reversal using the film forming composition for reversal A method for forming a resist pattern using positive / negative reversal, including a step of forming a film and a step of dissolving and removing the positive pattern on which the cross-linking has been formed with an alkaline wet etching solution.   The pattern forming method according to claim 1, wherein the exposure of the dense pattern is a single exposure.   2. The pattern forming method according to claim 1, wherein the exposure of the dense pattern is a double exposure in which a line pattern and a line pattern in a different direction are overlapped.   4. The pattern forming method according to claim 1, wherein the exposure of the dense pattern is a double exposure of dipole illumination of a horizontal line pattern and a vertical line pattern.   5. The pattern forming method according to claim 1, wherein the exposure of the dense pattern and the exposure for removing the unnecessary dense pattern are performed on the same exposure stage. 6.   6. The exposure of dense patterns and the exposure for removing unnecessary dense patterns are continuously performed on the same exposure stage without separating the substrate to be processed from the stage. 2. The pattern forming method according to claim 1.   The dissolution rate of the cross-linked positive pattern obtained in the step of imparting resistance to the organic solvent used in the reversal film-forming composition to the resist pattern in an alkaline wet etching solution is 2.38 mass% tetramethylammonium hydroxy. When the organic solvent used in the reversal film forming composition is etched with an aqueous solution of TMAH, propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, It is a single or mixed solvent containing at least one selected from propylene glycol monomethyl ether and heptanone, and the resistance to the solvent used in the reversal film forming composition is such that the crosslink formation positive pattern is formed by the reversal film formation. To the solvent used in the composition The method of forming a resist pattern using the positive-negative inversion of any one of claims 1 to 6 thickness loss and has a solvent resistance is 10nm or less when allowed to touch 0 seconds.   8. The resist pattern formation using positive / negative reversal according to any one of claims 1 to 7, wherein the reversal film-forming composition contains a resin containing a monomer unit having an aromatic skeleton or an alicyclic skeleton. Method.   Between the step of forming a film for reversal using the composition for forming a film for reversal and the step of dissolving and removing the positive pattern for crosslinking formation with an alkaline wet etchant, the film was laminated on the positive pattern for crosslinking formation. The method for forming a resist pattern using positive / negative reversal according to claim 1, comprising a step of removing the reversal film.   The method for forming a resist pattern using positive / negative reversal according to claim 9, wherein the step of removing the reversal film laminated on the positive pattern is wet etching.   The reversal film is a material that has a lower dissolution rate and exhibits solubility than the cross-linked positive pattern after the step of imparting resistance to the organic solvent when treated with an alkaline wet etching solution. 11. The step of removing the reversal film laminated on the crosslink-forming positive pattern and the step of dissolving and removing the positive pattern with the alkaline wet etchant are performed simultaneously using an alkaline wet etchant. A resist pattern forming method using positive / negative reversal as described.   The positive / negative reversal method according to claim 11, wherein the reversal film has a dissolution rate of 0.02 nm / second or more and 2 nm / second or less when etched with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution. A resist pattern forming method.   13. The chemical amplification positive resist film forming composition according to claim 1, comprising a component that generates an acid upon heating in a step of imparting resistance to an organic solvent to the resist pattern. Of forming a resist pattern using positive / negative reversal.   The method for forming a resist pattern using positive / negative reversal according to claim 13, wherein the component generating an acid by heating is a thermal acid generator added separately from the photoacid generator. The pattern forming method according to claim 14, wherein the thermal acid generator is represented by the following general formula (P1a-2).
(In the formula, K ⁻ is a sulfonic acid in which at least one α-position is fluorinated, or perfluoroalkylimide acid or perfluoroalkylmethide acid. R ^101d , R ^101e , R ^101f , and R ^101g are each hydrogen. An atom, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group, an oxoalkyl group or an oxoalkenyl group, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, or R ^101d and R ^101e or R ^101d and R ^101e and R ^101f may be bonded to each other by an alkoxy group, part or all of which may be substituted with an alkoxy group. may form a ring together with the nitrogen atom to which they are attached, when they form a ring, R ^101d, R ^101e, or R ^101d, R ^101e and R ^101f are der alkylene group having 3 to 10 carbon atoms Or form a heterocyclic aromatic ring having a nitrogen atom in the formula in the ring.)   The composition for forming a chemically amplified positive resist film is a positive resist material containing a resin having a repeating unit having a lactone ring as the resin and a repeating unit having an acid labile group that is eliminated by an acid. Item 16. A resist pattern forming method using positive / negative reversal according to any one of Items 1 to 15.   The method for forming a resist pattern using positive / negative reversal according to any one of claims 1 to 16, wherein the cross-linking is performed by an electrophilic partial structure in the resin.   The positive resist material is a positive resist material containing a resin having a repeating unit having a 7-oxanorbornane ring and a repeating unit having an acid labile group that is eliminated by an acid. When the acid labile group of the resin in the positive pattern is eliminated by generating and applying heat, the resin crosslinking in the positive pattern and the acid labile group are eliminated simultaneously. Item 18. A resist pattern forming method using positive / negative reversal according to Item 17. The method for forming a resist pattern using positive / negative inversion according to claim 18, wherein the repeating unit having a 7-oxanorbornane ring is a repeating unit (a) represented by the following general formula (1).
(In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² is a single bond or a linear, branched or cyclic alkylene group having 1 to 6 carbon atoms, and has an ether group or an ester group. may be, the number of 1 to 6 linear carbon atoms, for branched or cyclic alkylene group, the carbon atom linked to the ester group in the formula is a primary or secondary .R ^3, R ⁴ R ⁵ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and a is in the range of 0 <a <1.0. The pattern forming method according to any one of claims 16 to 19, wherein the repeating unit having an acid labile group that is eliminated by an acid is a repeating unit (b) represented by the following general formula (2).
(In the formula, R ¹² represents a hydrogen atom or a methyl group, and R ¹³ represents an acid labile group. B is 0 <b ≦ 0.8.) The pattern forming method according to claim 20 acid labile group R ¹³ is an acid labile group of alicyclic structure which is eliminated by an acid.   The method of forming a resist pattern using positive / negative reversal according to any one of claims 1 to 21, wherein the positive pattern includes a dot pattern, and the pattern obtained by the reversal includes a hole pattern.   23. The positive pattern according to any one of claims 1 to 22, wherein the positive pattern includes both a dense dot pattern and an isolated dot pattern, and the pattern obtained by the inversion includes a dense hole pattern and an isolated hole pattern. A resist pattern forming method using positive / negative reversal.   The positive pattern exposes a dense dot pattern, exposes an unnecessary dot pattern portion to form a dense dot pattern and an isolated dot pattern, and forms a dense hole pattern and an isolated hole pattern by the positive / negative reversal. The method for forming a resist pattern according to claim 23.   A chemical amplification positive resist film forming composition containing a resin having a repeating unit having a structure having an acid labile group that is eliminated by an acid is applied onto a substrate to be processed, and unnecessary solvent is removed by heating. Forming a resist film, applying a protective film-forming composition on the resist film, removing unnecessary solvent by heating to form a protective film, water or refractive index between the resist film and the projection lens However, the resist film is subjected to immersion exposure of high-density repetitive dense patterns on the resist film, and the unexposed portions of unnecessary dense patterns are exposed to immersion, and post-exposure heating is caused by exposure. The obtained acid is allowed to act on the acid labile group to cause the acid labile group of the resin in the exposed area to undergo elimination reaction, and then developed with an alkaline developer to obtain a positive pattern, thereby obtaining the positive pattern Obtained in the process The composition for forming a film for reversal in the resist pattern is formed by eliminating the acid labile group of the resin in the resist pattern and forming a crosslink in the resin so long as it does not lose the solubility in the alkaline wet etching solution. Positive negative reversal including a step of imparting resistance to the organic solvent used in the step, a step of forming a reversal film using the reversal film forming composition, and a step of dissolving and removing the positive pattern with an alkaline wet etching solution A resist pattern forming method.   26. The pattern forming method according to claim 25, wherein the composition for forming a protective film is based on a polymer compound obtained by copolymerizing a repeating unit having an amino group.   27. The pattern forming method according to claim 25 or 26, wherein the protective film material composition contains an amine compound.   A carbon film with a carbon content of 75% by mass or more is formed on a substrate to be processed, an intermediate film containing silicon is formed thereon, and a photoresist film for positive / negative reversal is coated thereon, for reversal. The pattern forming method according to any one of claims 1 to 27, wherein the film is formed of a hydrocarbon-based material.   A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, a photoresist film for positive / negative reversal is coated thereon, and the reversal film is formed of a material containing silicon. The pattern forming method according to claim 1, wherein the pattern forming method is a pattern forming method.   A carbon film having a carbon content of 75% by mass or more is formed on a substrate to be processed, an organic antireflection film is formed thereon, and a positive / negative reversal photoresist film is coated thereon to form a reversal film. 30. The pattern forming method according to claim 29, comprising a material containing silicon.