JPH04353852A - Method for forming resist pattern - Google Patents

Abstract

PURPOSE:To form a resist pattern of a semiconductor element and the like with good resolution. CONSTITUTION:A resist material comprising the following components (A)-(C) is applied on a substrate, exposed to high energy ray, and treated by heating. Then the substrate is exposed to vapor of a reactive org. germanium compd. to selectively introduce germanium into the area exposed to light and then subjected to dry etching. The components are (A) polyvinylphenol or polyhydroxy alpha-methyl styrene, (B) 5-50wt.% of a compd. having two or more naphthquinone diazide groups, and (C) 0-10wt.% of a radical inhibitor.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist pattern forming method in the field of semiconductor manufacturing.

0002

BACKGROUND OF THE INVENTION In recent years, with the remarkable increase in the degree of integration of semiconductor devices, it has become desirable to form fine patterns at the submicron level with high precision, but the structure of semiconductor devices has become multilayered. Unnegligible irregularities have appeared on the surface of the substrate during the lithography process. Such unevenness causes thickening of the resist film for planarization, occurrence of diffuse reflection of exposure light, etc., and as a result, reduces the resolution of the resist. Therefore, with the conventional method using a single-layer resist, it has become difficult to perform highly accurate microfabrication on actual devices.

[0003] In order to solve the above problems, a gas phase silylation method has been proposed. In this method, after exposure of the resist, the resist is exposed to the vapor of a silylating agent capable of reacting with active hydrogen, such as hexamethyldisilazane (HMDS), thereby selectively exposing exposed or unexposed regions of the resist. A typical example is DES, which silylates only the surface layer and then forms a pattern by dry development.
This is an IRE process. This process is based on Solid State Technology.
Novolac/naphthoquinone diazide photoresist was used, and after exposure and heat treatment, it was exposed to light by reacting it with HMDS in the gas phase at normal pressure. After selectively silylating only the surface layer of a portion, a resist pattern is formed by anisotropic O2 dry etching. Because it utilizes changes in the state of the resist surface layer, it is possible to eliminate the effects of scattered light from the substrate. Since the pattern is formed by dry etching, a resist pattern with a high aspect ratio can be formed. The function of the resist used in the DESIRE process is that in the exposed area, indene carboxylic acid is generated through photolysis of naphthoquinone diazide, making it hydrophilic, and in the unexposed area, naphthoquinone diazide and novolak resin are formed through heat treatment before exposure. The phenol groups of the ester are crosslinked by the esterification reaction, making it difficult for the silylating agent to penetrate.

0004

[Problems to be Solved by the Invention] In the conventional DESIRE process, a novolak resin with a low glass transition temperature is used as a base resin for the resist, so it easily swells due to reaction with a silylating agent. Because it is easily photo-crosslinked, the silylating agent becomes difficult to diffuse in high exposure areas, making it impossible to form a pattern. Due to the low reactivity of the silylating agent, treatment at high temperatures is required, the silylating agent diffuses quickly, and it is difficult to control the thickness of the silylated layer formed. Because of this, the allowable width in which a highly accurate resist pattern can be formed is small. Furthermore, since pattern formation is performed by oxygen dry etching after silylation, the resist surface turns into SiO2 and becomes insoluble and infusible, making it difficult to peel off the resist after pattern formation.

The present invention has been made to solve the above-mentioned problems, and aims to provide a pattern forming method that can form highly accurate fine patterns by dry development and also allows easy resist removal. The purpose is

[0006]

[Means for Solving the Problems] That is, the present invention provides the following components (A) to (C): (A) polyvinylphenol or polyhydroxy α-
Methylstyrene; (B) Compound having two or more naphthoquinone diazide groups in one molecule: 5 to 50% by weight based on the total amount of (A), (B) and (C); (C) Radical inhibitor: (A), (B) and (C)
A resist material consisting of 0 to 10% by weight based on the total amount of The present invention provides a resist pattern forming method characterized by introducing germanium and dry etching it.

[0007]

[Function] In the present invention, a base resin with a high glass transition temperature is used as a resist, and a radical inhibitor is used to prevent photo-crosslinking. Stable pattern formation can be performed up to the exposed area. Further, since organic germanium is used, the resist surface after dry etching becomes germanium oxide, and the resist can be easily removed using an oxidizing acid such as fuming nitric acid.

The resist material used in the present invention uses polyvinylphenol or polyhydroxy-α-methylstyrene as a base resin whose glass transition temperature is higher than that of novolak resin, and has two or more naphthoquinonediazide groups in one molecule as a photosensitizer. It consists of 5-50% by weight of the compound and 0-5% by weight of a radical inhibitor to suppress photocrosslinking. Here, the molecular weight of the base resin, polyvinylphenol or polyhydroxy-α-methylstyrene, is 1,000 to 50,000.
Those within the range of can be used. If it is less than 1,000, thermal crosslinking due to reaction with the photosensitizer will not occur sufficiently during heat treatment after exposure, and if it is more than 50,000, the uniformity of coating will be poor. Further, the naphthoquinone diazide compound which is a photosensitizer may be any compound having two or more naphthoquinone diazide groups in one molecule, for example, compounds shown by the following chemical formulas 1 to 5 may be used. Can be done.

[0009]

[Chemical formula 1]

0010

[Case 2]

[0011]

[Chemical formula 3]

0012

[C4]

[0013]

[C5]

[0014] The blending amount of these compounds is (A)
, 5 to 50% by weight, preferably 20 to 35% by weight, based on 100% by weight of the total amount of components (B) and (C). If it is less than 5% by weight, unexposed areas will be difficult to crosslink during heat treatment, and if it exceeds 50% by weight, the light absorption of the resist will be too large and the film forming properties will be poor, which is not preferable.

Furthermore, as the radical inhibitor, those shown by the following chemical formulas 6 to 10 are used, for example.

[0016]

[C6]

[0017]

[C7]

[0018]

[Chemical formula 8]

[0019]

[Chemical formula 9]

[0020]

[Chemical formula 10]

[0021] Regarding the blending amounts of these, when using polyhydroxy-α-methylstyrene as the base resin, it is not necessary to add them, but when using polyvinylphenol, (A), (B) and (C) The amount is from 0.1 to 10% by weight, preferably from 1 to 3% by weight, based on the total amount of components. If it is less than 0.1% by weight, the effect will be small, and if it exceeds 10% by weight, crystallization will occur in the resist film. When this resist is applied onto a substrate, dried, and then exposed to light, hydrophilic groups are generated in the exposed areas due to decomposition of naphthoquinone diazide. When this is then heat-treated for 1 to 5 minutes at a temperature range of 180 DEG C. to 230 DEG C., thermal crosslinking occurs in the unexposed areas between the OH groups of polyvinylphenol or polyhydroxy α-methylstyrene and naphthoquinone diazide. after that,
When the surface of this resist is exposed to the vapor of a reactive organic germanium compound, the organic germanium compound invades and diffuses into the resist at the exposed area, and the OH group of phenol and indenecarboxylic acid, which is a photodecomposition product of naphthoquinone diazide, reacts. Organic germanium can be introduced only into the exposed areas of the resist by carrying out the reaction for 0.5 to 5 minutes at a reaction temperature of 100 to 200°C and under normal pressure or reduced pressure. The reactive organic germanium compounds used here include [(C2H5)3Ge]2NH, [(CH3)3
Ge]3N, (C2H5)3GeN(C2H5)2, (
CH3)3GeOC2H5, (C2H5O)4Ge, (
CH3)3GeNCO or the like is used. After this, by performing, for example, anisotropic oxygen dry etching,
A resist pattern with excellent resolution can be manufactured.

The principle of the pattern forming method according to the present invention is basically the same as the DESIRE process. DESI
The major differences from the RE process are that a polymer with a high glass transition temperature and difficult to photo-crosslink is used as the base resin of the resist material, and that reactive organic germanium is used instead of reactive organic silicon during the gas phase reaction. This is the point where it is used. Since a polymer with a high glass transition temperature is used as the base resin of the resist material, the diffusion of the germanium compound into the resist during reaction with reactive organic germanium is slow, and the thickness of the germanium-introduced layer can be easily controlled. , the swelling of the resist can be reduced. In addition, reactive organic germanium has higher reactivity than silicon compounds,
A germanium-introduced layer can be formed at a lower temperature. This also leads to less swelling of the resist. Furthermore, the germanium-introduced layer has about 25% higher dry etching resistance than the silicon-introduced layer, and the etching rate ratio between the unexposed portion and the exposed portion can be increased, so that a resist pattern with high contrast can be formed. After pattern formation by oxygen dry etching, the surface of the resist becomes a metal oxide, but when organic silicon is used, the surface layer becomes SiOx, making it difficult to remove the resist. On the other hand, when organic germanium is used, the resist surface similarly becomes GeOx, but unlike SiOx, it dissolves in oxidizing acids such as fuming nitric acid, so the resist can be easily removed. This will be explained below using specific examples.

[0023]

[Example] Example 1 Polyvinylphenol (Maruzen Sekiyu Co., Ltd., molecular weight: 5,50
0) 24.5 g, 10.5 g of the naphthoquinone diazide compound represented by Chemical Formula 5, and 0.35 g of hydroquinone were dissolved in 100 ml of methyl cellosolve acetate to prepare a resist solution, which was spin-coated onto a silicon wafer. The film thickness at that time was 1.8 μm. After that, exposure was carried out using a Nikon excimer stepper (NA 0.45) at various exposure doses, and after heat treatment on a hot plate at 200°C for 3 minutes, a reactive organogermanium compound [(C
2H5)3Ge]2NH was reacted at 140° C. for 90 seconds under a reduced pressure of 150 mmHg. This sample was processed using a reactive ion etching device manufactured by Nichiden Anelva (DE).
M-451T), oxygen flow rate 5 sccm, pressure 3
Etching was performed for 40 minutes at a power of 60 W. As a result, resist residual film characteristics were exhibited with little swelling in a wide exposure area, and the sensitivity was approximately 20 mJ/cm2, and 40 mJ/cm2.
0.30μm line/at an exposure dose of mJ/cm2
Resolved space pattern.

Example 2 In Example 1, 2,5-ter was used as a radical inhibitor.
A similar experiment was conducted using a product to which 0.3 g of t-butylhydroquinone was added. In this case, the sensitivity is approximately 35 mJ/cm2
A line/space resolution of 0.3 μm was obtained with an exposure dose of 70 m/Jcm 2 .

Example 3 In Example 1, tris(trimethylgermyl)amine was used as the reactive organogermanium compound, and 15
A similar experiment was conducted under the conditions that the reaction was carried out at 160° C. for 90 seconds under a reduced pressure of 0 mmHg. In this case, the sensitivity is about 20mJ/c
m2, and 0.35 μm at an exposure dose of 50 mJ/cm2
line/space resolution was obtained.

Example 4 In Example 1, triethylgermyl diethylamine was used as the reactive organogermanium compound, and 150
A similar experiment was conducted under conditions of reaction at 160° C. for 120 seconds under a reduced pressure of mmHg. In this case, the sensitivity is about 50 mJ/c
m2, and 0.4 μm at an exposure dose of 100 mJ/cm2
line/space resolution was obtained.

Example 5 Polyhydroxy-α-methylstyrene (poly 4-ter
Synthesized by thermal decomposition of t-butoxycarbonyloxy-α-methylstyrene, molecular weight: 10,000) 26.15
g, naphthoquinone diazide compound shown in chemical formula 3 8.8
A resist solution was prepared by dissolving 5 g in 100 ml of methylcellosolve acetate and spin-coating it onto a silicon wafer. The film thickness at that time was 2.0 μm. Thereafter, pattern formation was performed in the same manner as in Example 1. In this case, only the reaction temperature with [(C2H2)3Ge]2NH was 170°C. As a result, the sensitivity was 40 mJ/cm2, and at an exposure dose of 60 mJ/cm2, the sensitivity was 0.
A 3 μm line/space pattern was resolved.

Example 6 The same experiment as in Example 5 was conducted using 8.85 g of the naphthoquinone diazide compound shown in Chemical Formula 1. In this case, the sensitivity is 30 mJ/cm2, which is 8
0.3μm line/at an exposure dose of 0mJ/cm2
The pattern of space was resolved.

Example 7 In Example 6, tris(triethylgermyl)amine was used as the reactive organogermanium compound, and 15
A similar experiment was conducted under the conditions that the reaction was carried out at 170° C. for 90 seconds under a reduced pressure of 0 mmHg. As a result, the sensitivity was 30mJ/c
m2, 0.35μ at an exposure dose of 60mJ/cm2
A pattern of m lines/spaces was resolved.

Example 8 A pattern was formed using PLASMASK200G-C (manufactured by Japan Synthetic Rubber Co., Ltd.) as a novolak resin/naphthoquinone diazide resist under the same conditions as in Example 1, but due to photocrosslinking, the germanium compound was not introduced,
No resist pattern was formed. A resist pattern could be formed for the first time by carrying out the reaction temperature at 170° C. for 90 seconds when introducing germanium. The sensitivity at that time was 100 mJ/cm2, and the resolution was 0.4 μm line and space. In a similar silylation process, in this case, the resist film thickness decreases by about 15%, making it impossible to obtain a good pattern. This shows that the reaction can be easily controlled by using germanium compounds.

[0031]

As described above, according to the present invention, a polymer having a high glass transition temperature and difficult to photo-crosslink is used as the base resin of the resist, and organic germanium, which has excellent O2 dry etching resistance, can be selectively etched in a gas phase. Since it is introduced into the resist surface layer, there is an effect that a fine resist pattern with high precision can be formed with little swelling.

Claims (1)

[Claims] [Claim 1] The following components (A) to (C): (A)
Polyvinylphenol or polyhydroxy α-methylstyrene; (B) Compound having two or more naphthoquinonediazide groups in one molecule: 5 to 50% by weight based on the total amount of (A), (B) and (C); (C) Radical inhibitors: (A), (B) and (C)
A resist material consisting of 0 to 10% by weight based on the total amount of A resist pattern forming method characterized by introducing germanium and dry etching it.