JPH063823A - Radiation sensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain a new radiation-sensitive resin compsn. having higher sensitivity than a conventional one to various radiation such as deep UV rays and electron beams. CONSTITUTION:The resist liquid is prepared by dissolving 0.5g of partial allylether of poly(hydroxystyrene) (with 50% ether rate) as the resin and 35mg of triphenylsulfonium trifluoromethane sulfonate as an acid producing agent to 3ml of methoxyethyl acetate, and then filtering the liquid through a membrane filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel resin composition which can be used as a resist material used in the production of semiconductor devices and is sensitive to radiation such as light, electron beams, X-rays or ion beams. is there.

[0002]

2. Description of the Related Art In recent years, processing technology on the order of submicrons has become necessary as LSIs are highly integrated. Therefore, for example, in the etching process in the manufacture of LSI, a dry etching technique capable of highly precise and fine processing is adopted.

Here, the dry etching technique is to cover a substrate to be processed with a resist, pattern the resist with light or an electron beam, and use the obtained pattern as a mask to form a substrate by reactive gas plasma. This is a technique for etching the portion exposed from the mask. Therefore, the resist used in the dry etching technique is composed of a material having a resolution of submicron order and sufficient resistance to reactive gas plasma.

Therefore, at present, as a resist material,
A positive photoresist composed of a diazonaphthoquinone compound and a phenol novolac resin is used, and as an exposure device, a reduction projection exposure device using g-line or i-line of a mercury lamp is used. However, at the stage where it is required to process a dimension of 0.5 μm or less with high accuracy, high resolution and a large focus margin, which exceed those of the current lithography technology, are required. Therefore, reduction projection using a short wavelength light source is required. The exposure method and electron beam exposure are indispensable. Therefore, various resists suitable for such a lithography technique have been studied and various proposals have been made.

For example, Japanese Patent Application Laid-Open No. 61-240237 discloses a technique relating to a resist composition for lithographic printing which can be used with deep UV light having a wavelength of less than 300 nm. According to this, it is described that the resolution characteristics can be improved by using a positive resist composed of trans-2-diazodecalin-1,3-dionlix.

A technique using a radiation-sensitive polymer is disclosed in Japanese Patent Laid-Open No. 1-1201654.
That is, it is described that the acetoin ester of poly (p-styrenesulfonic acid) can be used as a positive resist as in the technique disclosed above and a high resist contrast can be achieved.

Also, a negative resist has been proposed. The one disclosed in Japanese Patent Laid-Open No. 62-10644 has d
A type of resist that develops with an organic solvent using dichlorobenzene as a photosensitive material in order to enhance the sensitivity of a photosensitive resin composition for eepUV / EB while maintaining a narrow distribution of substituted poly (styrene) and maintaining high resolution. Is.

In Japanese Patent Laid-Open No. 1-293338, Kr is disclosed.
A technique relating to a photosensitive resin composition suitable for F excimer laser exposure is disclosed. According to it, a small amount of glycidin group was introduced into poly (vinylphenol), and
It is described that the cross-sectional shape of the resist can be improved more than before by using bis azide as a photosensitive material together.

[0009]

By the way, when the light in the deep UV region of a mercury lamp is used as a short wavelength light source, its illuminance is higher than that of the quinone azide g-line currently used in the production of LSIs. Since it is extremely low, a resist with extremely high sensitivity is required. Further, even when a KrF excimer laser is used as the light source, a highly sensitive resist is required because the light intensity is attenuated by absorption in the reduction optical system.

In electron beam lithography, unlike photolithography, a resist pattern is obtained by sequentially drawing the wafer surface with an electron beam, so that it cannot be put to practical use unless the sensitivity of the resist is high. Since the number of beam shots will increase remarkably as the degree of integration of semiconductor devices increases in the future, the requirement for sensitivity to the resist becomes the most important factor together with the resolution.

However, in the above-mentioned conventional radiation-sensitive resin composition, at least 1 is required for forming the resist pattern.
It requires an exposure dose of 00 to 400 mJ / cm @ 2 and cannot meet the above requirements.

Therefore, an object of the present invention is deepUV.
It is an object of the present invention to provide a novel radiation-sensitive resin composition having higher sensitivity to radiation such as light and electron beam than before.

[0013]

In order to achieve this object, according to the radiation-sensitive resin composition of the present invention (hereinafter sometimes abbreviated as "composition"), it is used as a first component. Partial 2-alkenyl ether of poly (hydroxystyrene) (hereinafter sometimes abbreviated as "resin").
And an acid generator as a second component that decomposes by the action of radiation such as light, electron beam, X-ray, or ion beam to generate an acid.

In order for the resin as the first component to undergo Claisen rearrangement and exhibit alkali solubility, the etherification rate must be 60% or less. Further, in order to have higher sensitivity than conventional resists, the etherification rate is preferably 5% or more, and more preferably 10% or more. If this value is too low, the sensitivity will be lower than that of conventional resists, for example, quinonediazide-based g-line resists currently used in LSI production.
With a lithography light source such as V light or KrF excimer laser, the productivity is extremely reduced.

The molecular weight of this resin can be determined according to the purpose. In order to obtain a suitable resist film, from the viewpoints that a solid film can be formed and that it is soluble in a solvent for preparing a resist coating solution, the weight average molecular weight (Mw) is from 1,000 to It should be in the range of 100,000. In terms of resolution, Mw is 100
More preferably, it is in the range of 0 to 20,000.

As the resin as the first component, for example, a partially allyl ether of poly (hydroxystyrene) containing a monomer represented by the following formula (1a) and a monomer represented by the following formula (1b) can be used. .

[0017]

[Chemical 1]

Partial allyl ethers of poly (hydroxystyrene) can be obtained in high yield by treating poly (hydroxystyrene) with allyl bromide in the presence of a base such as triethylamine.

The acid generator used in the radiation-sensitive resin composition of the present invention must generate a strong acid. As such, for example, various sulfonium salts represented by the following formulas (I) and (II), various iodonium salts represented by the following formulas (III) and (IV), and the following formula (V): Various p-toluene sulfonic acid esters, and various aromatic compounds represented by the following formulas (VI) and (VII) having at least one trichloroethyl group can be used.

[0020]

[Chemical 2]

[0021]

[Chemical 3]

However, X in the formulas (I) to (IV) is, for example, BF ₄ , AsF ₆ , SbF ₆ , ClO ₄ , CF ₃ S.
R ₃ in formula (V) represents O ₃ and represents a group represented by the following formulas (A) and (B).
Is, for example, CCl ₃ or the following formula (C),
It represents a group represented by (D), (E), (F) or (G), and R ₁ in the formula (VII) is, for example, C ₁ or H, and R ₂ is, for example, Cl. Or CCl ₃
Is represented.

[0023]

[Chemical 4]

The above-mentioned acid generators are commercially available, or by the method of JVCrivello etc., for example, [Journal of Polymer Science, Polymer Chemistry Edition (J. Polymer Sci., P.
Olymer Chem. Ed.), 22 , 69, (1984)]. The amount of the acid generator used here is 0.1 to 50%, preferably 1 based on the weight of the resin.
It is preferable to add it in an amount of -30%. If it is out of this range, the sensitivity becomes low and the coating film becomes brittle, which makes it difficult to use.

[0025]

In this radiation sensitive resin composition, the partial 2-alkenyl ether of poly (hydroxystyrene) as the first component functions as a binder polymer and as a cationically polymerizable polymer. Further, since the resin as the first component exhibits transparency derived from poly (hydroxystyrene), it also exhibits practical transparency against deep UV light. The acid generator as the second component generates an acid that acts as a catalyst for the cationic polymerization reaction of the resin as the first component by the action of radiation.

Therefore, for example, when a film of the composition of the present invention is formed on a silicon wafer and the film is selectively irradiated with radiation, an acid is generated in the exposed portion, and the acid causes the cationic polymerization of the resin to be catalytic. Proceed to. When a partially allyl ether of poly (hydroxystyrene) is used as the resin, the following formula (2) shows how the allyl group undergoes cationic polymerization with a strong acid catalyst.

[0027]

[Chemical 5]

On the other hand, when no acid is generated in the unexposed area and the composition is appropriately heated (a temperature at which Claisen rearrangement described below can occur, preferably about 100 to 180 ° C.), the Claisen rearrangement of the resin is added. Occurs and a phenolic hydroxyl group is generated. Therefore, the alkali solubility of the resin is higher than that before the irradiation with radiation. The state of Claisen rearrangement when a partially allyl ether of poly (hydroxystyrene) is used as this resin is shown in the following formula (3).

[0029]

[Chemical 6]

Therefore, when this coating film that has been selectively irradiated with radiation is developed using an alkali developing solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH), only the unexposed portion is dissolved and a negative resist pattern is obtained. .

As described above, the first component undergoes cationic polymerization using a trace amount of acid generated from the acid generator as a catalyst. Therefore, the exposure dose for irradiating the composition of the present invention with radiation may be an exposure dose capable of generating a trace amount of acid from the acid generator. As a result, the radiation-sensitive resin composition of the present invention has higher sensitivity to radiation than before.

[0032]

EXAMPLES As a resin of the first component, a partial allyl ether of poly (hydroxystyrene) (etherification ratio 5
0%) and triphenylsulfonium trifluoromethanesulfonate (wherein X is CF ₃ SO _{3 in the} formula (I)) is used as the acid generator of the second component. Examples of the resin composition will be described. Numerical conditions such as materials used and their amounts, processing time, processing temperature, and film thickness mentioned in the following description are as follows.
It is only a preferred example within the scope of the present invention. Therefore, the present invention is not limited to these conditions.

1. Synthesis of partial allyl ether of poly (hydroxystyrene) (etherification rate: 50%): poly (hydroxystyrene) (Mw = 11,200, Mw / Mn)
= 2.07, made by Maruzen Sekiyu) 6 g and potassium carbonate 3.5
g, potassium iodide 0.415 g, and allyl bromide 3.
1 g and 33 g of dimethyl sulfoxide were added to 70
Heat to ~ 80 ° C and stir for 4 hours. After cooling, pour into 200 ml of cold methanol. The resulting precipitate is MIBK1
Dissolve in 0 ml and pour into 100 ml cold methanol. The precipitate obtained is dried under vacuum overnight.

Thus, 4.5 g of partially allyl ether of poly (hydroxystyrene) was obtained. The weight average molecular weight (Mw) and the specific dispersion (Mw / Mn), and the absorption coefficient (abs. (At 248) at a wavelength of 248 nm.
nm)) was measured and the following values were obtained.

Mw = 14,000, Mw / Mn = 2.2
0, abs. (At 248 nm) = 0.35. 2. Preparation of composition: Partial allyl ether of poly (hydroxystyrene) synthesized as described above (etherification rate: 5
0%) 0.5 g, and 35 mg of triphenylsulfonium trifluoromethanesulfonate as an acid generator are dissolved in 3 ml of methoxyethyl acetate and filtered through a membrane filter to prepare a resist solution.

3. Pattern formation: 3-1. In the case of exposure with a KrF excimer laser: A coating solution (hereinafter referred to as a resist solution) of the composition of Example is spin-coated on a silicon wafer pretreated with hexamethyldisilazane. This is pre-baked on a hot plate at 80 ° C. for 1 minute to form a film having a thickness of 0.8 μm.

Next, a KrF excimer laser (EMG201 (trade name) manufactured by Lambda Physik Co., Ltd.) is applied to this coating.
Irradiation is performed by changing the exposure amount through a mask having an evaluation pattern that gives lines and spaces. The exposure level is set by changing the irradiation time.

The exposed sample is baked at 140 ° C. for 2 minutes. This was developed with a TMAH aqueous solution for 1 minute and rinsed with water for 1 minute. The residual film thickness of the obtained pattern is measured by a surface roughness meter (Rank Taylor Hobson Co., Taristep (trade name)), and this value is plotted against the logarithm of the exposure amount to create a characteristic curve.

The sensitivity obtained from this characteristic curve is 40 mJ /
cm ² , and the contrast was ^2.5 . Further, when the cross section of the pattern having an exposure dose of 60 mJ / cm ² was observed with a scanning electron microscope (SEM), it was found that a line and space of 0.5 μm was resolved in a vertical shape. 3-2. In the case of exposure by electron beam: The method of forming the coating film in this example is the same as that in the case of exposure by the KrF excimer laser described above. Acceleration voltage 2 is applied to the formed film.
0 kV electron beam (ELS3300, manufactured by Elionix Co., Ltd.)
(Trade name)) and change the exposure amount, and draw an appropriate number of evaluation drawings. The exposed sample is processed in the same manner as described above to form a pattern and is evaluated.

As a result, the sensitivity was 6.4 μC / cm ² and the contrast was 2.0. Also, the exposure amount is 8.0 μC
SEM observation of the cross section of the / cm ² pattern revealed that a line and space of 0.5 μm was resolved with a good shape.

[0041]

As is clear from the above description, according to the radiation-sensitive resin composition of the present invention, deepU
When radiation such as V light, electron beam, X-ray, and ion beam is selectively irradiated, an acid is generated from the acid generator in the radiation irradiation part, and the acid causes the poly (hydroxystyrene) partial 2-alkenyl ether. The cationic polymerization of the alkenyl group of 1 proceeds catalytically. In this case, since the amount of acid generated may be small, the amount of exposure for irradiating the composition with radiation may be an amount of exposure capable of generating a small amount of acid from the acid generator.

On the other hand, in the non-radiation-irradiated portion, Claisen transition occurs by applying appropriate heat to this composition,
This produces phenol soluble in aqueous alkaline solutions.

Therefore, the radiation-sensitive resin composition of the present invention becomes a negative resist having high sensitivity to radiation.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/027

Claims (6)

[Claims] 1. Radiation comprising a partial 2-alkenyl ether of poly (hydroxystyrene) having an etherification rate in the range of 5 to 60% and an acid generator which generates an acid by the action of radiation. Sensitive resin composition. 2. A poly (hydroxystyrene) moiety 2-
The weight average molecular weight of the alkenyl ether is 1,000 to 1.
The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive resin composition is in the range of 0.00000. 3. The acid generator is a sulfonium salt, and the addition amount thereof is a poly (hydroxystyrene) moiety 2.
The radiation-sensitive resin composition according to claim 1, which is in the range of 0.1 to 50% based on the weight of the alkenyl ether. 4. The acid generator is an iodonium salt, and the addition amount thereof is the poly (hydroxystyrene) moiety 2.
The radiation-sensitive resin composition according to claim 1, which is in the range of 0.1 to 50% based on the weight of the alkenyl ether. 5. The acid generator is p-toluenesulfonic acid ester, and the addition amount thereof is in the range of 0.1 to 50% with respect to the weight of the partial 2-alkenyl ether of poly (hydroxystyrene). Claim 1 characterized by the above.
The radiation-sensitive resin composition described. 6. The acid generator is an aromatic compound having at least one trichloromethyl group, and the addition amount thereof is 0.1-based on the weight of the partial 2-alkenyl ether of poly (hydroxystyrene). The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive resin composition is in the range of 50%.