JPH0346659A - Resist composition - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to enable a half-micron pattern to be resolved by using a resist composition made of a silicone-modified phenol resin obtained by substituting a specified silicone resin for at least one part of the hydroxyl groups of the phenol resin. CONSTITUTION:This resist composition is made of the silicone-modified phenol resin obtained by replacing at least one part of the hydroxyl groups of the phenol resin by the silicone resin represented mainly by formula I in which X is halogen, such as Cl or Br; R1 is methylene or higher alkylene; each of R2 - R4 is 1 - 5 C alkyl, 1 - 5 C alkenyl, or phenyl, each optionally same or different, and at least one of them has at least one vinyl or chloromethyl group added to it; and n is 0 or an integer >=1, thus permitting sensitivity to be enhanced and a half-micron pattern to be resolved.

Description

[Detailed Description of the Invention] [Summary] The purpose of the present invention is to provide a resist composition that has high sensitivity and is capable of resolving half-micron patterns, and the present invention aims to provide a resist composition that is highly sensitive and capable of resolving half-micron patterns. A silicon compound represented by the following formula: 2 ■ 4 (2) 4 (In the above formula, X represents a halogen atom, R3 represents a methylene group or an alkylene group, R2,
R3 and R4 may be the same or different from each other and represent an alkyl group, an alkenyl group or a phenyl group, and at least one of R2, R3 and R4 has at least one vinyl group or chloro group attached thereto. The silicone-modified phenolic resin is substituted with a methyl group, n is an integer of 0 or 1 or more, and m is a positive integer.

[Industrial application field]

The present invention relates to a resist composition, and more specifically, to a resist composition comprising a silicone-modified phenolic resin that can be advantageously used for pattern formation of a semiconductor ship LSI. The resist composition of the present invention (3) can be applied to ionizing radiation phosphorography such as X-ray phosphorography, electron beam phosphorography, etc., as well as deep ultraviolet lithography.

[Conventional technology]

As is well known, in order to achieve high integration of LSIs, it is necessary to miniaturize wiring line width and wiring spacing. The minimum line width of IMbit-DRAMs currently on the market is 1.2 marks, and 4Mbit-DRAMs that have begun to be shipped as samples.
The minimum line width of M is 0.81M. Next generation 16Mbi
The minimum line width of t-DRAM is 0.5 nl, and phosphorography techniques and resist materials that can form half-micron patterns are being researched.

Since the exposure wavelength used in X-ray lithography is significantly shorter than the wavelength of light currently used, diffraction phenomena and interference effects can be ignored, making it advantageous for forming fine patterns of 0.5 marks or less. Development is being carried out at various research institutions.

In addition, electron beam lithography is an indispensable pattern forming method for manufacturing semi-custom LSIs, as typified by gate array LSIs (4), and is a method for forming resist materials that can form finer patterns with higher sensitivity. Development continues.

As typical conventional electron beam resist materials, polymethyl methacrylate (PMMA) resist is known as a positive type, and polychloromethylstyrene (CMS) resist is known as a negative type. PMMA resist has good resolution but poor sensitivity, and CMS resist has good sensitivity but poor resolution. In addition, as a high-sensitivity, high-resolution resist, a resist based on a novolac type cresol resin and a crosslinking agent and a photosensitizer is also available, such as 5AL-5AL-1, which is commercially available from Silapray Co., Ltd.
There is 6018R-7. However, this resist material
It has the problem of poor stability when stored in the form of a resist solution, and sensitivity changes each time it is used.

Furthermore, the wiring structure of recent LSIs has become a highly integrated multilayer wiring structure, and the unevenness of the upper layer wiring caused by the formation of the lower layer wiring is becoming more and more severe5〉. Patterns are becoming increasingly difficult to form. Furthermore, as mentioned above, the minimum line width in LM-bit DRAM (1.
2-, and in 4M-bit DRAM, the pattern line width is 0.8 Ja, and the line width of the pattern is also becoming increasingly finer. A two-layer resist process has been proposed as a method that can be expected to form a half-micron pattern even on such a high-step substrate.

In addition, current phosphorography uses the g-line of a mercury lamp as an exposure light source, but because light interference and diffraction phenomena occur, the practical resolution (minimum line width) is 0.6H, and it is necessary to increase the resolution. Based on the general opinion that it is necessary to shorten the wavelength of light used to achieve this, a deep ultraviolet exposure method using a wavelength of 300 nm or less has been proposed. That is, about 20
Excimer laser phosphorography uses wavelengths from 0 to 300 nm.

The present inventors have developed a negative material prepared by adding benzophene(6)non or 2,2-dimethoxy-2-phenylacetophenone to a ladder-type silicone resin as an upper resist material for a two-layer resist process applicable to deep ultraviolet lithography. He discovered a molded resist assembly and filed a patent application (see Japanese Patent Laid-Open No. 63-279245). However, although this resist composition is also suitable for forming submicron patterns, further improvements are desired in order to keep up with recent technological advances.

[Problem to be solved by the invention]

Therefore, an object of the present invention is to provide a resist composition that is highly sensitive and capable of resolving half-micron patterns.

More specifically, the first object of the present invention is to provide a resist composition as described above, which is particularly applicable to lithography using X-rays, electron beams, etc.

A second object of the present invention is to provide a resist composition as described above, which is particularly applicable to deep ultraviolet phosphorography and is preferably capable of forming a micron pattern even on a high-level substrate. (7) An object of the present invention is to provide a material useful as an upper layer resist material in a two-layer resist process.

[Means to solve the problem]

The above-mentioned object, according to the present invention, is a silicon compound in which at least some of the hydroxyl groups of the phenolic resin are represented by the following formula. ,.

4 (In the above formula, X represents a halogen atom such as chlorine or bromine, RI represents a methylene group or an alkylene group having 2 or more carbon atoms, and R2, R3 and R4 may be the same or different from each other, and are preferably represents a (LA) alkyl group having 1 to 5 carbon atoms, preferably an alkenyl group or phenyl group having 1 to 5 carbon atoms, and R2, R.

and at least one of R1 has at least one vinyl group or chloromethyl group attached thereto, n is an integer of 0 or 1 or more, and m is a positive integer) This can be achieved by a resist composition further comprising a silicone-modified phenolic resin substituted with .

Here, "phenolic resin", which is the main ingredient of the resist composition, refers to phenol group-containing polymers conventionally used as resist materials, such as polyvinyl phenol resin, novolac type phenol resin, novolac type cresol resin, xylenol resin. , and others.

The resist composition of the present invention is a negative type resist composition for use with ionizing radiation, and therefore can be advantageously applied to X-ray or electron beam phosphorography. This resist composition can be used, for example, with an excimer laser (wavelength: 200 to 300 nm).
) etc. (9) For application to lithography, it is preferable to add a photosensitizer to make the material sensitive to such short wavelength light. The photosensitizer is 22-dimethoxy-2-
The resist composition is selected from the group consisting of phenylacetophenone and peroxides (such as dicumyl peroxide) and is added to the resist composition in an amount sufficient to provide sensitivity in the deep ultraviolet range.

Furthermore, the resist compositions of the present invention are generally advantageously used in single layer resist processes. Such a resist composition includes, for example, silicone-modified phenolic Wider fat in an amount of 2.4% by weight of tetramethylammonium hydroxide.
It can be advantageously prepared by dissolving it in an aqueous solution.

The resist composition of the present invention can be advantageously used as an upper layer resist material not only in a single-layer resist process but also in a two-layer resist process. When used as an upper resist material, an alkenyl group-containing silicone resin may be added to the resist composition to increase the silicon content in the material.

(10) [Function] The resist of the present invention is a resist composition that can realize high sensitivity and high resolution when used in X-ray phosphorography or electron beam phosphorography. The basic material of the resist used in the present invention is a phenolic resin, and since these resins are dissolved in an alkaline aqueous solution, alkaline development is possible and high resolution can be expected. However, since these resins do not have functional groups for X-rays or electron beams, their sensitivity to these ionizing radiations is extremely low. It is known that chloromethyl groups or vinyl groups are highly sensitive to ionizing radiation. On the other hand, it is known that a hydroxyl group contained in a phenolic resin causes a substitution reaction with a halogenated alkyl group or a halogenated silyl group. Furthermore, silicon atoms have a larger atomic number than carbon atoms, so
It is known that it easily absorbs radiation. The present invention was completed based on such knowledge. That is, by reacting the phenolic resin with the silicon compounds represented by formulas (I) and (I[), a highly sensitive X-ray (11) or electron beam negative resist can be obtained.

Here, n lOJ<O in the previous formulas (I) and (II)
The denaturation method is different between 1 and 1 or more.

<1) When modifying the hydroxyl group of a phenolic resin with a silicon compound (a compound in which a halogen atom and a silicon atom are directly bonded) when n is O: Dissolve the silicon compound and phenol resin in an organic solvent, and then Dissolve triethylamine or pyridine and stir at room temperature or with heating.
Stir for ~10 hours. After the reaction is completed, the reaction solution is washed with water several times, then evaporated, and then freeze-dried to obtain a modified product.

(2) When modifying the hydroxyl group of a phenolic resin with a silicon compound (a silicon compound in which an alkylene group etc. is present between a silicon atom and a halogen atom) where n is 1 or more: When a silicon compound is added to water or an organic solvent and A phenolic resin is mixed and stirred for 1 to 50 hours while heating using an alkali catalyst such as sodium hydroxide, potassium hydroxide, potassium t-butoxy.After the reaction is completed, (19) the reaction solution is mixed several times. After washing with water, the reaction solution is evaporated and then freeze-dried to obtain a modified product.

If the modification rate of the phenolic resin modified with silicon by the method (1) or (2) above is too high, the number of phenolic hydroxyl groups will decrease and it will not dissolve in an alkaline aqueous solution.
Alkaline development becomes impossible.

Therefore, it is important to modify the deformed resin to such an extent that it dissolves in the alkaline aqueous solution. The range in which the modified resin dissolves in the alkaline aqueous solution is a hydroxyl group modification rate of 0 to 40%.

From the point of view of sensitivity, the higher the denaturation rate, the better; however, taking into account the solubility in alkaline aqueous solutions, it is
0-40% is suitable. Control of the modification rate is mainly determined by the ratio of the amount of phenolic resin charged, the amount of silicone compound charged, and the amount of catalyst charged during the modification reaction.

Usually, a silicone-modified resin having a modification rate of about 25% can be obtained by adding 50 g equivalent of a silicon compound and 50 g equivalent of a catalyst to 100 g equivalent of hydroxyl group of a phenolic resin and reacting the same. Further, the denaturation rate can be determined by quantifying Si(13) silicon atoms by atomic absorption spectrometry.

For example, the silicon-modified phenolic resin can be used as a resist in the following manner. First, the modified resin is dissolved in an organic solvent such as methyl ethyl ketone, methyl isobutyl ketone, or ethyl cellosolve acetate. next,·
A modified resin is spin-coated onto a silicon substrate to a film thickness of 1 to 2 JJm.

After prebaking at about 80° C. for 20 minutes, X-ray irradiation or electron beam exposure is performed to form a latent image of the pattern.

Next, the film is developed with an alkaline developer such as Ml-312 (manufactured by Silapray), and rinsed with pure water.

Bost baking is performed, and the formation of the resist pattern is completed.

Figure 1 shows the two-layer resist process (A>,
This is an abbreviated version in the order of (B) and (C). As shown in the figure, the substrate 1 having the wiring 2 has a lower resist 3 and an upper resist 4 functioning as a planarization layer in this order.

In the case of the two-layer structure resist process, in addition to the high sensitivity and high resolution characteristics of the normal (14) single-layer resist process, the flattening layer is etched with oxygen plasma to form a resist pattern. , oxygen plasma resistance is required. It is known that the presence of a compound having silicon atoms in the resist material improves oxygen plasma resistance. Furthermore, since phenolic resins have phenolic hydrogen groups, they tend to undergo chemical reactions with halogenated alkyl or halogenated silyl compounds.

Therefore, in the present invention, first, a phenolic resin is modified with an alkyl halide or a halogenated silyl compound (hereinafter collectively referred to as a silicon compound) having a silicon atom. Modification method of phenolic resin (2 methods)
was mentioned above.

Now, it is generally said that the oxygen plasma resistance of a resist for a two-layer structure is required to be at least 20 times that of the planarization layer. That is, the etching rate during oxygen plasma bombardment needs to be 1/20 or less of the etching rate of the planarization layer. Oxygen plasma resistance varies depending on the etching conditions (15) (oxygen gas flow rate, gas pressure, applied power density, etc.) (although silicon-modified phenolic resins are often used as a planarization layer). The oxygen plasma resistance is often about 10 times higher than that of hard-baked novolac-type positive photoresists.In such cases, silicone resin is added to the silicone-modified phenolic resin to improve the oxygen plasma resistance. It is preferable to use a resist material with the addition of This is because when mixed with the silicone-modified phenolic resin and irradiated with deep ultraviolet rays, they crosslink with each other and become insoluble in the developer.

A silicone-modified phenolic resin alone or a silicone-modified phenolic resin to which a silicone resin is added is sensitive to far ultraviolet rays even without the use of a photosensitizer. Concomitant use of drugs is recommended. (16) As mentioned above, suitable photosensitizers include 2,2-dimethoxy-2-phenylacetophenone and peroxides (a typical example of which is dicumyl peroxide).

Using the described paulownia wood, a resist solution is prepared as follows. A resist material prepared by adding a silicone-modified phenol resin or a silicone resin and, if necessary, a photosensitizer thereto, is dissolved in an organic solvent such as ethylene glycol monomethyl acetate or dimethyl ketone to prepare a resist solution.

Next, this resist solution is spin-coated onto a silicon substrate or the like on which a planarization layer is formed. After prebaking, deep ultraviolet rays that have passed through a photomask are irradiated. Next, development is performed with an alkaline aqueous solution or an organic solvent, and post-baking is performed to form a resist pattern. Next, a planarization layer pattern is formed by oxygen plasma etching using this resist pattern as a mask. To pattern the wiring part, dry etching or wet etching is performed using a chlorine-based or fluorine thread gas (17) using the pattern of the peel resist + planarization layer as a mask, and the wiring pattern can be formed (see Figure 1). .

〔Example〕

Preparation Example 1 A silicone-modified novolak phenol resin was prepared with the following composition.

Sodium hydroxide 1.9g
Ethylene glycol monomethyl ether 100 - The above composition was placed in a three-necked flask and stirred at 100°C for 6 hours. This was poured into a large amount of water to form a precipitate, and the precipitate was washed three times with tetrahydrofuran (TIIF) water. Next, it was precipitated with THF-nhexano, and 1.4-
Freeze-drying was performed with dioxane to obtain a silicone-modified novolac type phenolic resin.

This modified resin is an alkaline developer MP-312 (↑
8) (manufactured by Silapray). Further, according to atomic absorption spectrometry, the amount of silicon atoms was 5.2% by weight, and from this result, the modification rate was calculated to be 26%.

Preparation Example 2 A silicone-modified polyvinylphenol resin was prepared with the following composition.

Polyvinylphenol I fat 20.0g (Linker-M, manufactured by Maruzen Petrochemical) Pyridine 6.6g Methyl isobutyl ketone 200-Polyvinylphenol was dissolved in methylisobutylketone, and a silicon compound and pyridine were sequentially added dropwise.
The reaction was carried out at 60°C for 3 hours. After pyridine hydrochloride was filtered off, the reaction solution was washed five times with water, and the reaction solution was evaporated using an evaporator and freeze-dried with 1.4 dioxane to obtain a silicon-modified polyvinylphenol resin.

This modified resin is also soluble in an alkaline developer as in Preparation Example 1, and the atomic weight of silicon (19) determined by atomic absorption spectrometry is 5.4% by weight, and from this result the modification rate can be calculated to be 29%. Ta.

Preparation Example 3 A silicone-modified novolac type phenol resin was prepared with the following composition.

Sodium hydroxide 3.8g
Ethylene glycol monomethyl ether 10h+4
! The above composition was placed in a three-necked flask and stirred at 100°C for 6 hours. This was poured into a large amount of water to form a precipitate, and the precipitate was washed three times with THF-water.

Next, it was precipitated with THF-n hexane and freeze-dried with 1,4-dioxane to obtain a silicone-modified novolac type phenol resin.

Preparation Example 4 A silicone-modified polyvinylphenol resin was prepared with the following composition.

(20) Pyridine 7.9 g Methyl isobutyl ketone 200-Polyvinylphenol was dissolved in methyl isobutyl ketone, and the silicon compound and pyridine were sequentially added dropwise. after that,
The reaction was carried out at 60°C for 3 hours. After pyridine hydrochloride was filtered off, the reaction solution was washed five times with water, and the reaction solution was evaporated using an evaporator and freeze-dried with 1,4 dioxane to obtain a silicon-modified polyvinylphenol resin.

Preparation Example 5 A ladder type silicone resin having a vinyl group in the side chain was synthesized using the following composition.

Pyridine water Methyl isobutyl ketone 0 g 0 g 5O- (21) A solution containing methyl isobutyl ketone and pyridine was cooled to -30°C, and predetermined amounts of vinyltrichlorosilane and water were sequentially added dropwise. Thereafter, the mixture was refluxed at 120°C for 9 hours. After washing with water five times, 75 g of a silylating agent (trimethylchlorosilane) and 100 g of pyridine were added, and the mixture was reacted at 60° C. for 2 hours. After washing with water, the resin was precipitated and recovered with methanol.

Example 1 Silicon-modified 6.0 g novolak type phenolic resin methyl isobutyl ketone obtained in Preparation Example 1 A resist solution having the above composition was filmed on an 81 substrate on which an AA wiring pattern was formed with a thickness of 20-1 mark. It was spin coded so that the thickness was 1.5-. After prebaking at 80°C for 20 minutes, further
Rotating target type X-ray generator 5X-NR as a ray exposure machine
Contact exposure was performed using Model 4 (manufactured by Rigaku Denki). Next, the film was developed for 3 minutes using an alkaline developer MP-312 (manufactured by Silapray), and rinsed with water. The resulting resist pattern (22) was well resolved in shape up to 0.51-, which is the minimum line width of the mask. The exposure amount at this time was 30 mJ/cnf.

Example 2 6.0 g of silicone-modified polyvinylphenol resin methyl isobutyl ketone obtained in Preparation Example 2 was spin-coded and prebaked in the same manner as in Example 1. Next, electron beam exposure was performed using an electron beam drawing device εLS-3300 (manufactured by Elionix Co., Ltd.). Next, the film was developed for 3 minutes using an alkaline developer Ml-312 (manufactured by Silapray), and rinsed with water. The resulting resist pattern was resolved to 0.4 ha. The exposure amount at this time was 12μC/Cl11
Met.

Example 3 A resist solution was prepared with the following composition.

5.0 g of silicon resin obtained in Preparation Example 3 Ladder-type silicone resin obtained in Preparation Example 5 1.0 g Methyl isobutyl ketone 40 m An Af wiring pattern was formed with a thickness of 121 mm (23) MP of photoresist is applied as a planarization layer on the S1 substrate.
Using a substrate coated with -1300 (manufactured by Silaplay Co., Ltd.) to a thickness of 20 μm and baked at 200°C, a resist solution having the above composition was applied to the substrate using a spin cord to a film thickness of 0.3 μm. did. After baking at 80℃ for 20 minutes, an ultra-high pressure Xe-Hg lamp (Ushio Inc.
MX-500MA model) and a photomask, deep ultraviolet exposure was performed to form a latent image of a resist pattern. Next, it was developed with methyl isobutyl ketone and rinsed with isopropyl alcohol. This substrate was placed in a dry etching device (model DBM-451, manufactured by Nikkei Anelva Co., Ltd.), and the planarization layer was etched using oxygen plasma to form a pattern. According to SEM observation, it was found that resolution was achieved up to 0.5J=-, which is the minimum line width of the photomask, without any residue in the space portion. The exposure amount at this time is 5
It was 0 mJ/cnf and had high sensitivity.

Example 4 A resist solution was prepared with the following composition.

(24) Methyl isobutyl ketone 4 - The following steps were carried out in exactly the same manner as in Example 3. The results in this case were also similar to those in Example 3, and it was found that resolution was achieved with no residue in the space portion up to 0.5 Ja, which is the minimum line width of the photomask. The exposure amount at this time was 30 mJ/cut.

〔Effect of the invention〕

According to the present invention, a half-micron resist pattern can be formed on a substrate having a high level difference, so the present invention can be applied to the manufacture of VLSIs of 16 Mbit-DRAM and later.

[Brief explanation of drawings]

FIGS. 1A, 1B, and 1C are cross-sectional views sequentially showing an example of a two-layer resist process to which the resist composition of the present invention can be applied. In the figure, 1 is the substrate, 2 is the wiring, 3 is the lower resist, (25
) 4 is the upper layer resist.

Claims (1)

[Claims] 1. A silicon compound in which at least some of the hydroxyl groups of a phenolic resin are represented by the following formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼(II) (In the above formula, X represents a halogen atom, R_1 represents a methylene group or an alkylene group, and R_
2, R_3 and R_4 may be the same or different from each other and represent an alkyl group, an alkenyl group or a phenyl group, and at least one of R_2, R_3 and R_4 has at least one vinyl group added thereto. or a chloromethyl group, n is an integer of 0 or 1 or more, and m is a positive integer). 2. Sufficient amount of 2,2- to have sensitivity in the deep ultraviolet region
The resist composition according to claim 1, further comprising a photosensitizer selected from the group consisting of dimethoxy-2-phenylacetophenone and/or peroxide.