JPS647651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a resist image, and more particularly, to a method for producing a resist image using electron beams, X-rays, ultraviolet rays, or
The present invention relates to a method for producing a fine resist image using radiation such as the following deep violet radiation or a particle beam such as an ion beam or a neutron beam.

Conventionally, photolithography technology, which forms a resist pattern by irradiating light, has been used to manufacture devices that require minute processing, such as integrated circuits and bubble memory devices, but the wavelength of the light depends on the processing accuracy. It is well known that due to the order limit, techniques for forming even finer patterns by irradiation with deep ultraviolet rays, X-rays, electron beams, ion beams, etc. have been developed and are already being put into practical use.

In the early stages of research, photoresists were used as resists for forming patterns by irradiating electron beams, X-rays, deep ultraviolet rays, ultraviolet rays, or ion beams, but in recent years, electron beam , Research and development of materials suitable for irradiation with X-rays, deep ultraviolet rays, ultraviolet rays, or ion beams is being carried out at home and abroad, and there are already many publications.

As is well known, there are two types of resist: positive type and negative type. Positive type resists become easily soluble in solvents when irradiated, and are dissolved and removed during development, leaving a pattern with unexposed areas remaining. It is something that can be obtained. In the negative type, the resist in the irradiated area becomes poorly soluble or insoluble, and a pattern in which the irradiated area remains is obtained by development. In other words, when the same pattern is irradiated, an image of the irradiation pattern or its inverse image can be obtained depending on whether the resist is negative or positive, and both types of resist can be used depending on the purpose. That is advantageous.

Many materials have been proposed for positive electron beam resists, including polymethyl methacrylate, polybutene-1-sulfone, and polymethyl isopropenyl ketone.
Many negative-type materials have been proposed, including polyglycidyl methacrylate, copolymers containing glycidyl methacrylate, epoxidized polybutadiene, and polydiallyl phthalate.

In general, positive resists have excellent resolution but are difficult to obtain with high sensitivity, and negative resists, on the other hand, are easy to obtain with high sensitivity but have difficulty in resolution. However, some of the materials mentioned above are already in practical use, and masks have already been manufactured by electron beam lithography. However, in recent years, dry processes have become more
Namely, ion milling, sputter etching,
As techniques such as plasma etching are used to etch resist images onto substrates, resist materials are required to have high resistance to these etching methods, that is, dry etching resistance. I'm getting used to it. Conventionally, resists mainly used for mask manufacturing have been required to have sensitivity, resolution, and etching resistance. For example, for chrome mask manufacturing, resistance to ceric ammonium nitrate aqueous solution is required for wet etching of chromium, and dry resists have been required. Resistance in the process was not considered.

As a result of research on the dry etching resistance of resist materials, it has been found that the resistance is significantly improved when a conjugated ring such as a phenyl group is included in the molecule. AZ resist, a photoresist (Shitsupray Co., Ltd.,
(trade name) has good dry etch resistance, but it also contains many phenyl groups. In addition, polystyrene has been taken up as a typical polymer containing many phenyl groups, and it has been confirmed that polystyrene has good dry etch resistance.
Polystyrene derivatives (eg, chloromethylated polystyrene, polychlorostyrene) and copolymers containing styrene or styrene derivatives have been investigated as resist materials. The inventors also discovered that polyvinylnaphthalene has even stronger dry etch resistance than polystyrene, and copolymerization of polyvinylnaphthalene, polyvinylnaphthalene derivatives, or vinylnaphthalene or vinylnaphthalene derivatives with monomers that do not contain a naphthalene ring We have already proposed using objects as resists. In addition, in order to obtain a good resist image using these materials as a resist, the development process, that is, the selection of the developer, is very important.
The inventors have already discovered that benzene, xylene, chlorobenzene, dichloroethane, etc. are not preferable for styrene-based resists, and that tetrahydrofuran is suitable as a solvent, and they have proposed that a resist image can be manufactured using tetrahydrofuran or a solution containing tetrahydrofuran. Proposed.

Tetrahydrofuran is generally used by mixing it with an alcohol-based poor solvent, but since the results vary depending on the mixing ratio, it is necessary to find the best ratio, and also to keep the ingredients uniform from a storage perspective. It goes without saying that a solvent is easier to handle.

The inventors conducted further research and discovered benzyl acetate as a developing solvent that is suitable for vinylnaphthalene-based polymers and also shows excellent results even with a single composition.The present invention has practical significance. reached.

That is, the present invention provides a method for producing a resist image in which a polymer resist is developed with benzyl acetate or a developer containing benzyl acetate, and is particularly preferred when the polymer resist is a material containing an aromatic ring. According to the present invention, a complete development process can be performed without causing the polymer resist to swell significantly, and a resist image with substantially improved resolution and excellent shape can be produced.

The invention will be explained in detail below using examples.

Example 1 5 g of monodisperse polystyrene with a molecular weight of 600,000 and a polydispersity of 1.1 or less was dissolved in 95 g of xylene, and then 0.2 μm was dissolved.
The resist solution was obtained by passing it through a filter. Apply by spin coating (2000 rpm, 20 seconds),
A uniform coating film with a thickness of 0.65 microns was obtained by baking at 110°C for 30 minutes. Using an electron beam exposure device with an accelerating voltage of 20 KV, latent images were created by drawing patterns of various sizes with an exposure dose of 2.2 x 10 ^-5 coulombs/cm ² , and then developed by immersing them in benzene acetate for 60 seconds. did. When I observed the resulting image, I found that the 0.5 micron wide resist pattern was completely formed.
It showed excellent resolution. When tetrahydrofuran is used as a developer, slight meandering is observed,
Benzene, xylene, chlorobenzene, and dichloroethane caused severe swelling, and a pattern of 1 micron could not be formed at all.

Example 2 Monodisperse polystyrene with a molecular weight of 390,000 and a polydispersity of 1.1 or less was chloromethylated by a Friedel-Crafts reaction. Elemental analysis showed that the chloromethylation rate was 12
It was %. This sample was dissolved in xylene at 6% by weight and filtered through a 0.2 μm filter to obtain a resist solution. A latent image was formed in the same manner as described in Example 1. However, the appropriate exposure amount was 1.7×10 ^-6 coulombs/cm ² . Benzyl acetate was used as a developer and immersion was performed for 60 seconds. This was followed by rinsing by soaking in isopropanol for 30 seconds. A resist image with excellent shape and resolution was obtained. n in the developer
- When butyl acetate was used, the swelling was somewhat good, and when isoamyl acetate was used, it was slightly better, but it was not as good as benzyl acetate. When a mixed solution of tetrahydrofuran and isopropanol was also tried, almost good results were obtained with 1.5 parts of tetrahydrofuran and 1 part of isopropanol, but good results were not always obtained when the mixing ratio was changed.

Example 3 Styrene 70: Chlorostyrene 25: Butadiene 5
(component ratio), 5.5 g of a random copolymer with a weight average molecular weight of approximately 850,000 was dissolved in 100 ml of xylene, and Example 1
It was evaluated using the same method. However, the exposure amount is 8x
10 ^-7 coulombs/cm ² was appropriate. Almost good results were obtained using benzyl acetate as the developer, but development was carried out by immersion in a mixed solvent of 4 volumes of benzyl acetate and 1 volume of ethanol for 90 seconds, followed by immersion in a mixed solvent of 1 volume of methyl ethyl ketone and 2 volumes of ethanol.
The resist was rinsed by immersing it in a mixed solvent for 30 seconds, and was spray-dried with dry nitrogen to obtain a very good resist image.

Example 4 Poly-2 with a weight average molecular weight of 120,000 and a polydispersity of 1.6
-Vinylnaphthalene was dissolved in dioxane at a concentration of 10% by weight, and evaluated in the same manner as in Example 1. However, the appropriate exposure amount was 5×10 ⁻⁵ coulombs/cm ² . It was developed by immersing it in benzyl acetate for 60 seconds, and then rinsed for 30 seconds with a mixed solvent of 1 volume of methyl ethyl ketone and 1 volume of ethanol to obtain a resist image. 0.6
Excellent resist images were obtained that resolved even micron lines and spaces.

Example 5 The polymer obtained by chloromethylating the poly-2-vinylnaphthalene described in Example 4 (chloromethylation rate: 36%) was evaluated as a resist in the same manner as described in Example 4. However, the exposure amount
2.2×10 ^-6 coulombs/cm ² was appropriate. The film was developed by immersion in benzyl acetate for 90 seconds, and then rinsed by immersion in isopropanol for 30 seconds. The resist image obtained was extremely clear as described in Example 4.

As described in detail above, for many resist materials, especially polymeric resist materials that have aromatic rings such as phenyl nuclei and naphthalene nuclei in their molecules,
Benzyl acetate is excellent as a single component developer solvent in most cases. When the polymer resist tends to swell, as shown in the example, a solvent mixed with a non-solvent can be prepared and used as a developer.

Claims (1)

[Claims] 1 A polymer film formed on a substrate and made of a polymer material containing aromatic rings is irradiated with radiation such as electron beams, X-rays, ultraviolet rays or deep ultraviolet rays, or particle beams such as ion beams or neutron beams to form a latent image. 1. A method for producing a resist image by forming and then developing a resist image, wherein the developing solution is benzyl acetate or a solution containing benzyl acetate.