JP2001291288A - Method for manufacturing master disk for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing the master disk for an optical disk by which a pattern of minute recesses and projections of high resolution can be formed with high throughput. SOLUTION: The substrate is subjected to the surface treatment by using at least one agent selected from organic silicon compounds having at least one kind of hydrolyzable group and generating no base and vinyl polymers having at least one kind of hydrolyzable groups to obtain a surface treated medium 101 to improve the adhesion between the substrate and a resist film. A resist composition containing a medium having such reactivity that the solubility in an alkali aqueous solution changes by the reaction with an acid as a catalyst, and further containing a compound which generates as acid by irradiation of radiation is applied on the surface-treated substrate to form a resist film 103. The film is irradiated with radiation, developed and etched to form minute recesses in the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a master for an optical disk used for recording information and the like.

[0002]

2. Description of the Related Art In recent years, with the rapid development of information communication and image processing techniques, there has been an increasing need for a technique for recording large-capacity digital information such as higher-definition image information. As a current information recording technique, an optical disc such as a compact disc (CD) or a digital video disc (DVD) is used as a medium having the largest storage capacity. In order to further increase the capacity, technological developments such as miniaturization of processing of minute irregularities such as pits of an optical disk master and improvement of an optical head are being promoted.

In conventional pit processing, 350-460n
A desired pit pattern is formed by exposing the resist on the rotating master to a laser beam having a wavelength of m. Shorter laser wavelength (180-300nm) to make pits finer
Pit pattern processing technology is being studied. However, it is difficult to achieve a pit line width of 100 nm or less when the wavelength of the laser is shortened. Therefore, a pit forming method using an electron beam having excellent fine workability is expected.

[0004] The minimum processing size by electron beam exposure depends on the beam diameter, and a high resolution of nanometer level can be obtained. However, electron beam exposure has the disadvantage that the energy absorption rate of the resist is significantly lower than that of laser exposure, so that the resist sensitivity is low, and the throughput is low because the exposure is performed in a vacuum. As a method of improving the throughput, it is important to improve the performance of the resist used, as well as the improvement of the apparatus. Therefore, a resist exhibiting high sensitivity and high resolution is demanded for an electron beam exposure apparatus.

As a resist material for solving these problems, attention has been paid to a chemically amplified resist that causes a reaction that changes the solubility in a developing solution by the catalytic action of an acid generated by exposure, and a number of chemically amplified resist compositions have been proposed. Have been. Changes in solubility may increase or decrease solubility. For example, as a medium that increases the solubility in an aqueous alkali solution, a compound or polymer having a protective group (acetal group, t-butoxycarbonyl group, etc.) that is deprotected (separated) by an acid catalyst is disclosed. In the resist containing such a medium, the exposed portion is melted by the development, and the unexposed portion remains, so that a positive pattern can appear. On the other hand, compounds having a compound having an epoxy group, a methoxymethyl group, a methylol group or the like are disclosed as a medium for reducing the solubility in an aqueous alkali solution. In a resist containing such a medium, an exposed portion becomes alkali-insoluble by a cross-linking reaction or formation of an alkali-insoluble compound, and an unexposed portion dissolves, so that a negative pattern can appear.

Examples of the acid generator used for the chemically amplified resist include onium salts such as diaryliodonium salts and triarylsulfonium salts, various halogen compounds, compounds having a plurality of phenolic hydroxyl groups, alkylsulfonic acid esters, and N-hydroxy compounds. For example, sulfonic acid esters of imide are used.

However, it has been pointed out that the conventional chemically amplified resist causes abnormalities in the resist shape and peeling of the pattern depending on the material and composition of the substrate used.
Soda lime glass usually used as a master of an optical disc contains an alkali metal or an alkaline earth metal.
The acid generated by exposure reacts with these alkali metals before reacting with the medium that changes the solubility, and the necessary acid catalyst reaction that should occur does not occur. In the case of the pull type and the negative type pattern, there is a problem that the shape becomes a biting shape. Therefore, a method of forming a resist pattern using synthetic quartz glass that does not contain a composition that causes neutralization of an acid such as an alkali metal or an alkaline earth metal is generally performed. However, the synthetic quartz glass substrate has a drawback in that the adhesion between the resist and the glass interface is weak due to the presence of a high concentration of hydroxyl groups and water molecules adsorbed on the hydroxyl groups on the surface, resulting in peeling of the pattern. As a method for avoiding this, as described in JP-A-11-288528, a hydroxyl group on a glass substrate surface and hexamethyldisilazane (HMDS) are used.
Are known to develop a siloxane structure. By this treatment, the adhesion between the resist and the glass substrate is improved, and peeling of the pattern can be suppressed to some extent.

[0008]

In the above prior art, when HMDS used as an adhesion improver reacts with a hydroxyl group on a glass surface, ammonia, which is a basic compound, is generated as a decomposed product. It has not been considered that a neutralization reaction occurs with the resulting acid, resulting in a decrease in sensitivity and a deterioration in resolution at the top or bottom of the resist pattern.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a master for an optical disk capable of forming a high-resolution pattern with fine irregularities at a high throughput.

[0010]

In order to achieve the above object, a method for manufacturing an optical disk master according to the present invention comprises irradiating a resist film applied on a substrate with radiation, developing the resist film, etching the resist film, and etching the resist film. It forms minute recesses on the substrate,
(A) using at least one selected from the group consisting of a non-base generating organosilicon compound and a vinyl polymer having at least one type of hydrolyzable group, having at least one type of hydrolyzable group, A step of subjecting the substrate to a surface treatment, (b) applying the resist composition containing a reactive medium whose solubility in an aqueous alkali solution changes by a reaction using an acid as a catalyst, and a resist composition containing a compound capable of generating an acid by irradiation with radiation; And (c) forming a latent image on the resist film using radiation, and (d) forming a resist pattern by development. is there.

By the surface treatment of the substrate, the adhesion between the substrate and the resist film can be improved. The formation of the resist film is preferably performed by heating. After the latent image is formed on the resist film, it is preferable to heat the resist film in order to promote the acid-catalyzed reaction in the latent image portion. It is preferable to use an aqueous alkali solution for development. As the radiation, electromagnetic waves such as ultraviolet rays, far ultraviolet rays, X-rays, and particle beams such as electron beams and ion beams are used.

As the non-base generating type organosilicon compound having a hydrolyzable group used in the present invention, a silane coupling agent is preferable. Here, the non-basic-occurring, generally, in the molecule (-NH-) group, - refers to having no (NH ₂₎ substituents such as those generated ammonia such groups. The silane coupling agent refers to an organic silicon compound having a hydrolyzable group and an organic functional group in a molecule. The hydrolyzable group is a substituent capable of being hydrolyzed by moisture in the air or moisture adsorbed on an inorganic surface to generate a highly reactive silanol group. This silanol group can react with the surface of glass, a metal material or the like to form a chemical bond. Further, even when the amount of water on the material surface is extremely small or small, a polymer thin film of the silane coupling agent is formed, so that the adhesiveness of the resist can be improved. Specific examples of the hydrolyzable group include a halogen group, an alkoxy group and an acetoxy group. On the other hand, the organic functional group indicates a substituent that reacts with the organic resin matrix. Specific examples of the organic functional group include a vinyl group, a methacryloyl group, an epoxy group, an amino group, and an isocyanate group.

Specific examples of the silane coupling agent include:
Vinyltriacetoxysilane, 3-aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, γ-isocyanatopropyltriethoxysilane, etc. Is mentioned.

Further, as the organosilicon compound having a hydrolyzable group and generating a non-base, isopropenoxytrimethylsilane and the like can be used in addition to the silane coupling agent.

The vinyl polymer having a hydrolyzable group used in the present invention is preferably a vinyl polymer having an epoxy group as a hydrolyzable group. Specifically, a polymer obtained by subjecting a rubber material having an unsaturated double bond, such as polybutadiene or polyisoprene, to an epoxy resin is preferable. In such a polymer, a structure containing a large number of epoxy groups in the molecule is formed by reacting a rubber material with peracetic acid.
The epoxy group is hydrolyzed by water adsorbed on the substrate surface to generate a hydroxyl group. It is considered that the generated hydroxyl group forms a hydrogen bond with the resin component of the resist and the substrate to give good adhesion. These surface treatment media (a silane coupling agent and an epoxy group-containing vinyl polymer) can be used alone or in combination of two or more.

The surface treatment medium for improving the adhesion used in the present invention has a concentration of 0.001% by weight.
10 to 10% by weight, preferably 0.01 to 5% by weight
Diluting with water, organic solvent, etc., immersing glass, metal material, etc. in this liquid, spraying this solution on the substrate surface, dropping this solution on the substrate surface and spin coating It is convenient and preferable. If the concentration of the medium is less than 0.001% by weight, the effect of improving the adhesion is small, and if it exceeds 10% by weight, the reaction between the medium on the substrate surface and the acid in the resist becomes remarkable, and the sensitivity and resolution are reduced. Connection is not good.

The medium having a reactivity that changes the solubility in an aqueous alkali solution by a reaction using an acid as a catalyst used in the present invention includes a medium having an increased solubility and a medium having a decreased solubility.

Examples of a medium having increased solubility in an aqueous alkali solution include alkali-soluble phenol resins such as polyvinyl phenol, bisphenols, and the like.
Trisphenol alkanes, trinuclear phenols,
Compounds in which hydroxyl groups such as tetrakisphenols are protected with acid-decomposable groups such as acetal groups, ketal groups, t-butyl groups, and t-butoxycarbonyl groups. A polymer in which all or a part of a carboxyl group such as a copolymer of polyacrylic acid or styrene and acrylic acid is protected by the above-mentioned acid-decomposable group, hydroxystyrene and / or hydroxy-α-methylstyrene and methacrylic acid And / or a polymer in which part or all of the hydroxyl group and / or carboxyl group in the copolymer with acrylic acid is protected by an acid-decomposable group, and part of the hydroxyl group in a copolymer of hydroxystyrene and maleic anhydride Or a part or all of the carboxyl group in a polymer including at least a polymer protected by an acid-decomposable group, at least a methacrylate and / or acrylate having an alicyclic group in a side chain, and methacrylic acid and / or acrylic acid. A polymer protected by an acid-decomposable group can be used.

As a medium having reduced solubility in an aqueous alkali solution, for example, a compound having an epoxy group, a methoxymethyl group, a methylol group, a polyhydric alcohol, or the like can be used.

Further, in order to control the alkali solubility of a medium whose solubility in an aqueous alkali solution increases or decreases, an alkali-soluble resin may be mixed and used as necessary. Examples of the alkali-soluble resin include alkali-soluble phenol resins such as cresol novolak resin, polyvinyl alcohol, polyvinyl alkyl ether, a copolymer of styrene and acrylic acid or methacrylic acid, and a copolymer of styrene and maleic anhydride. No.

As the compound capable of generating an acid upon irradiation, the compounds described in the section of the prior art and those described in the above-mentioned JP-A-11-288528 and the like are used.

The resist composition comprises an acid-generating compound 1
The amount of the reactive medium whose solubility in an aqueous alkali solution changes is preferably 3 to 100 parts by weight, more preferably 5 to 25 parts by weight, relative to parts by weight.

Furthermore, the resist composition of the present invention may contain, for example, a surfactant for preventing striation (uneven coating) or improving developability, a storage stabilizer for the resist solution, and an acid catalyst. A basic compound for suppressing diffusion to the exposed portion, an ion dissociating compound such as onium halide, and a humectant such as tetraethylene glycol can be added as necessary.

Further, the substrate used in the present invention includes:
High silicate glass and synthetic quartz glass containing no alkali metal, alkaline earth metal, or the like are preferable. Further, on these substrates, Cr, Ni, Al, Zr, Si, Ta, W,
Metal films such as Ti and Mo, and oxide films and nitride films thereof, and conductive inorganic thin films such as indium tin oxide can be formed and used.

[0025]

Next, specific examples and comparative examples of the present invention will be described. These embodiments are merely examples, and the present invention is not limited only to these embodiments.

Example 1 200 mm in diameter and 6 mm in thickness
1,4-polybutadiene (weight average molecular weight: 3 × 10 ⁵ ) as a surface treatment medium 102 for improving the adhesion is 60% on the surface of the quartz glass substrate 101 (FIG. 1A).
2 ml to 4 ml of a 0.025% by weight xylene solution of the epoxidized polymer was dropped, spin-coated, heat-treated at 180 ° C. for 5 minutes, and dried (FIG. 1B).

On this substrate, m, p-
Cresol novolak resin (weight average molecular weight: 500
0, polydispersity: 1.4): 85 parts by weight and 4,4 ′,
A mixture of 15 parts by weight of 4 ″ -methylidine trisphenol, a polynuclear phenol compound TPPA1000 having a tetrahydropyranyl group as an acid-decomposable group as a dissolution inhibitor
P (manufactured by Honshu Chemical Industry Co., Ltd.) (substitution ratio of tetrahydropyranyl group: 0.66): 12 parts by weight, as an acid-generating compound upon exposure, an ester of N-hydroxynaphthylimide and nonafluorobutanesulfonic acid : 4 parts by weight,
0.1 parts by weight of trimethylsulfonium iodide as an ion dissociating compound is dissolved in 2-heptanone, a resist solution having a solid concentration of 10% by weight is dropped, spin-coated, and heat-treated at 100 ° C. for 5 minutes. Then, a resist film 103 having a thickness of 0.25 μm was obtained (FIG. 1C).

An electron beam lithography apparatus (acceleration voltage of the electron beam is 30 kV) is used to apply an electron beam 104 to the substrate at 5.0 μC.
After drawing a pattern with a pit line width of 0.1 μm and a track pitch of 0.2 μm at an irradiation dose of / cm ² , heat treatment was performed at 100 ° C. for 2 minutes to promote the acid-catalyzed reaction of the latent image forming portion 105 (FIG. d)). After this heat treatment, the film was immersed in an aqueous solution containing 2.38% by weight of tetramethylammonium hydroxide for 60 seconds to obtain a positive resist pattern 106 (FIG. 1).
(E)).

As a result, in the drawing and developing processes including the substrate surface treatment step of the present invention, it was found that resist peeling and pattern collapse were not observed, and the resist cross-section was rectangular and a line width as designed was obtained. Was.

Using this resist film as a mask, the quartz substrate is dry-etched to a depth of 30 nm to 70 nm by reactive ion etching with a mixed gas of C ₂ F ₆ and H ₂ to form a predetermined concave pit pattern. An optical disc master was obtained.

Example 2 A 0.5% by weight aqueous solution of 3-glycidoxypropyltrimethoxysilane was used instead of the xylene solution of the polymer obtained by epoxidizing 1,4-polybutadiene by 60% in Example 1. A resist pattern was formed in accordance with the method of Example 1 except for using. As a result, it was found that in the process including the substrate surface treatment step, a positive pattern having a good cross-sectional shape and a line width according to design dimensions was obtained without resist peeling, pattern collapse, and the like. Further, by performing dry etching in the same manner as in Example 1, a master for an optical disk having a concave pit pattern similar to that in Example 1 was obtained.

Example 3 A 0.5% by weight aqueous solution of 3-aminopropyltriethoxysilane was used in place of the xylene solution of the polymer obtained by epoxidizing 1,4-polybutadiene by 60% in Example 1. A resist pattern was formed in the same manner as in Example 1 except for the above. as a result,
In the process including the substrate surface treatment step, it was found that a positive pattern having a good cross-sectional shape and a line width as designed was obtained without any resist peeling or pattern collapse. Further, by performing dry etching in the same manner as in Example 1, a master for an optical disk having a concave pit pattern similar to that in Example 1 was obtained.

Example 4 A 0.5% by weight aqueous solution of 3-methacryloxypropyltrimethoxysilane was used instead of the xylene solution of the polymer in which 1,4-polybutadiene was epoxidized at 60% used in Example 1. A resist pattern was formed according to the method of Example 1 except that the resist pattern was used. As a result, the process including the substrate surface treatment step of the present invention,
No resist peeling or pattern collapse was observed, and it was found that a positive pattern having a good cross-sectional shape and a line width as designed was obtained. Further, by performing dry etching in the same manner as in Example 1, a master for an optical disk having a concave pit pattern similar to that in Example 1 was obtained.

(Comparative Example 1)
Instead of a substrate surface treatment step using a xylene solution of a polymer in which 4-polybutadiene was epoxidized at 60%, hexamethyldisilazane was dropped on the substrate in an amount of 2 ml to 4 ml, and spin-coated, followed by heat treatment at 100 ° C. for 5 minutes. A resist pattern was formed according to the method of Example 1. As a result, it was found that the process including the above-described surface treatment caused resist peeling.

Example 5 The procedure of Example 1 was followed, except that the quartz glass substrate used in Example 1 was replaced with a substrate in which nickel was deposited to a thickness of 50 to 100 nm on a soda-lime glass surface by nickel sputtering. A resist pattern was formed. As a result, it was found that in the process including the substrate surface treatment step of the present invention, a positive pattern having a good cross-sectional shape and a line width according to design dimensions was obtained without any resist peeling, pattern fall, etc. . Also,
By performing dry etching in the same manner as in Example 1, an optical disk master having the same concave pit pattern as in Example 1 was obtained.

Example 6 Instead of the quartz glass substrate used in Example 1, a transparent conductive film of indium tin oxide (film thickness: 100 nm to 200 nm) was formed on the surface of soda lime glass.
A resist pattern was formed according to the method of Example 1 except that a substrate on which a film having a thickness of (nm) was formed was used. As a result, the process including the substrate processing step of the present invention, the resist peeling,
No pattern collapse was observed, and it was found that a positive pattern having a good cross-sectional shape and a line width as designed was obtained.
Further, by performing dry etching in the same manner as in Example 1, a master for an optical disk having a concave pit pattern similar to that in Example 1 was obtained.

Example 7 Instead of the resist composition of Example 1, m, p-cresol novolak resin (weight average molecular weight: 5500, polydispersity: 3.8): 100 parts by weight, methylol melamine: 15 A resist was prepared according to the method of Example 1, except that a resist composition consisting of 5 parts by weight of triphenylsulfonium trifluoromethanesulfonate as an acid precursor and 0.1 part by weight of trimethylsulfonium iodide as an ion dissociating compound was used. A pattern was formed. As a result, in the pit pattern forming process including the substrate surface treatment step of the present invention, a negative pattern having a good cross-sectional shape and a line width as designed can be obtained without resist peeling, pattern fall, etc. Do you get it. Further, by performing dry etching in the same manner as in Example 1, a master for an optical disk having a concave pit pattern similar to that in Example 1 was obtained.

(Example 8) Instead of the xylene solution of a polymer obtained by epoxidizing 1,4-polybutadiene by 60% in Example 1, the same 1,4-polybutadiene was used in 60%.
A resist pattern was formed according to the method of Example 1, except that a 0.5% by weight acetone / water mixed solution (10: 1) of epoxidized polymer 20% by weight and vinyltrichlorosilane 80% by weight was used. . As a result, it was found that in the process including the substrate surface treatment step, a positive pattern having a good cross-sectional shape and a line width according to design dimensions was obtained without resist peeling, pattern collapse, and the like. Further, by performing dry etching in the same manner as in Example 1, a master for an optical disk having a concave pit pattern similar to that in Example 1 was obtained.

(Embodiment 9) Using electron beam drawing technology, R
An embodiment in which the present invention is applied to a process of manufacturing an OM (Read Only Memory) type optical disc master will be described. First, after the surface of the quartz substrate was surface-treated with the adhesion improver used in Example 2, the resist composition used in Example 1 was spin-coated on the substrate, and heat-treated at 100 ° C. for 5 minutes to obtain 0%. A resist film having a thickness of .15 μm was obtained.
Next, an antistatic film spacer 30 is formed on the resist film.
0 (manufactured by Showa Denko KK) by spin-coating and 1 without heat treatment
Dry for 0 minutes. The substrate is placed on an electron beam lithography system (acceleration voltage 30
kV) while rotating, and irradiating the resist film with an electron beam while sending the electron beam from the inner peripheral side to the outer peripheral side at a track pitch of 100 nm to form a spiral or concentric track. A latent image of a pit is formed in the pit. Next, this substrate was heat-treated at 100 ° C. for 2 minutes, and then immersed in an aqueous solution containing 2.38% by weight of tetramethylammonium hydroxide for 60 seconds to obtain a positive resist pattern.

Example 1 using this resist film as a mask
By performing dry etching in the same manner as in the above, an optical disk master having a predetermined concave pit pattern was obtained.

[0041]

According to the present invention, it is possible to form a pattern with fine irregularities having high sensitivity and excellent resolution to electron beams, X-rays and other radiations by using a chemically amplified resist, and using the same as a mask. By etching, a pattern of fine irregularities with good dimensional accuracy can be obtained. As a result, a high-density, large-capacity optical disc master can be manufactured stably with a high yield.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a manufacturing process of an optical disc master according to a first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Quartz substrate 102 ... Surface treatment medium 103 ... Resist film 104 ... Electron beam 105 ... Latent image forming part 106 ... Resist pattern

Claims (1)

[Claims] 1. A method for manufacturing a master for an optical disk, comprising: irradiating a resist film applied on a substrate with radiation, developing and etching the resist film to form minute recesses in the substrate. Surface treatment of the substrate using at least one selected from the group consisting of a non-base-generating organosilicon compound and a vinyl polymer having at least one hydrolyzable group Step (b) On a substrate having been subjected to the above-mentioned surface treatment, a resist medium containing a reactive medium whose solubility in an aqueous alkali solution is changed by a reaction using an acid as a catalyst and a compound generating an acid by irradiation with radiation. Applying and forming a resist film, (c) forming a latent image on the resist film using radiation, and (d) forming a resist pattern by development. Method for manufacturing a master optical disc characterized by having a step.