JPS6240725A - Electron beam resist composition and forming method of resist pattern - Google Patents

Abstract

PURPOSE:To be used as an upper layer resist in a 2-layer resist method with high sensitivity and high dry etching resistance by introducing a photosensitive group which contains silicon to a polyvinyl phenol. CONSTITUTION:A resist composition having a photosensitive group which contains silicon in a polyvinyl phenol represented by a formula I. In the formula I, at least one of R<1>-R<3> is a vinyl group, aryl group or chloromethyl group, and the remaining two are one type selected from methyl group, vinyl group, acryl group and chloromethyl group. n is 0 or 1, and m is positive integer number. This electron beam resist composition is higher in the sensitivity for the electron beam than the conventional one, and when this is used as an upper layer resist of 2-layer resist method, a high throughput can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an electron beam resist composition for microfabrication used in the manufacture of semiconductor devices, etc., and a resist pattern forming method for forming a microresist pattern using this resist. Regarding.

(Prior Art) In recent years, with the increasing integration of semiconductor devices, technical requirements regarding the formation of fine patterns have become stricter.
Resist pattern rules are also moving toward submicron dimensions. For this reason, the performance required of resists is becoming increasingly high.

In particular, when manufacturing large-scale integrated circuits (LSI) and the like, it often happens that a resist pattern must be formed on a substrate having unevenness (steps) during an intermediate process. In this case, especially in stepped areas, if a single layer resist is used, it will be affected by changes in the irradiated electron dose due to the uneven resist surface and back scattering and forward scattering from the substrate, making it difficult to obtain patterning with the designed dimensions. is difficult to control.

In order to solve this problem, a multilayer resist method has been proposed. Among these, the two-layer resist method is considered promising because it can simplify the process (for example, see 1 document ``6th Electronics Materials Research Group Lecture Abstracts J (June 1985), p. 14).

The upper resist used in this two-layer resist method is required to have high sensitivity, high resolution, and high oxygen plasma etching resistance.

This document describes oxygen gas reactive ion etching (hereinafter referred to as O,R
Silicon-containing electron beam dispersion (SNR: 5 silicone-based
negative resist). According to this document, the SNR is as follows:
For the KV electron beam, D, , = 5, O
It is reported to have a sensitivity of p-C/cm2 and a line-and-space resolution of 0.2 pm.

(Problem to be solved by the invention) However, with this SNR, as already explained,
Electron beam sensitivity is 5, Ofii, c/'cm
2, the sensitivity cannot be said to be sufficiently high, and therefore, there was a problem that the exposure process during pattern formation was time consuming and the throughput was poor.

Moreover, when this SNR is used as an upper layer resist, it is necessary to once bake the lower polymer layer at a temperature of about 100° C. and then form an upper layer resist on this polymer layer, which makes the process complicated. There was a problem.

Therefore, an object of the present invention is to provide a highly sensitive electron beam resist that solves the above-mentioned conventional sensitivity and process problems, and also to provide a method for forming a two-layer resist pattern using this resist through a simple process. It is about providing.

(Means for Solving the Problems) The electron beam resist composition of the first invention of this application is a resist having a silicon-containing photosensitive group in polyvinylphenol as represented by the following general formula (1). A composition.

5iRIR2R3 (CHHz)n (-CHCH2-)m (In general formula (I), n is 0 or 1.

1 (At least one of 1, R2, and R3 is a vinyl group, an allyl group, or a chloromethyl group, and the remaining two are each a type selected from a methyl group, a vinyl group, an allyl group, and a chloromethyl group.

m is a positive integer. ) The second invention of this application is an invention of a method for forming a resist pattern using this electron beam resist composition,
It has the following steps.

First, a lower resist layer such as AZ-24 is applied on the substrate.
00 (trade name manufactured by Silaplay), LMR (naphthoquinonediazide sulfonic acid ester of borac resin), P
Apply a layer of MMA (polymethyl methacrylate) or other suitable polymer.

Thereafter, this lower resist layer was baked at a lower temperature of 60°C than conventional methods, and then an upper resist layer containing an electron compound represented by the general formula (I) in which a photosensitive group containing a silicon atom was introduced into polyvinylphenol was placed on the lower resist layer as an upper resist layer. A resist skin of the line resist composition is formed.

SiR’R2R3 (CH2)n ivy (In general formula (1), n is 0 or 1.

At least one of R', R2, and R3 is a vinyl group, an allyl group, or a chloromethyl group, and the remaining two are each a type selected from a methyl group, a vinyl group, an allyl group, and a chloromethyl group.

m is a positive integer. ) Thereafter, this resist film is selectively irradiated with an electron beam to expose a mask pattern.

Thereafter, the exposed resist film is developed with an organic solvent, and the polymer layer is dry-etched with reactive oxygen plasma using the upper resist pattern obtained by the development as a mask.

(Function) The electron beam resist composition of the present invention has higher sensitivity to electron beams than conventional ones. That is, FIG. 1 shows the sensitivity curve of allyldimethylsilyl ether of polyvinylphenol, which is a type of electron beam resist of the present invention. , the horizontal axis represents the dose and the vertical axis represents the normalized residual film thickness. As can be understood from the experimental results, the dose increase at which the residual film rate is 50% is 4.0 g07 cm2, and the electron beam resist of the present invention has higher sensitivity than the conventional one. Therefore, the electron beam resist composition of the present invention provides high throughput when used as an upper layer resist in a two-layer resist method.

In addition, when buttering was performed using this electron beam resist composition, as described later, the two-layer resist pattern had a resolution of 0.25 gm and a 7 spectral ratio of 6, so this resist has a high resolution. It has high resolution.

Furthermore, since it contains Si, it has a property of high oxidation plasma etching properties.

Therefore, using this upper resist as a mask, the lower resist can be patterned by plasma etching.

Furthermore, in the method of the present invention, since the electron beam resist composition of the present invention as described above is used as the upper resist layer, the baking temperature of the polymer layer of the lower resist layer may be lower than that of the conventional method, at about 60'C. The process of forming a resist pattern can be simplified.

(Examples) Examples of the present invention will be described below. In addition, in the examples described below, description will be made under specific numerical conditions, materials, and other conditions that are preferable for this invention, but these are merely examples, and this invention does not apply to these implementations. It should be understood that this is not limited to examples only.

Ward 21” - Yaai reduction example■ First f, polyvinylphenol (molecular weight 10,000 to
000) was dissolved in 500mM dichloromethane, and 40.9m! Triethylamine (Q) was added, then 40 g of allyldimethylchlorosilane was added, and the mixture was reacted at a temperature of 20 to 25°C for 24 hours.

The reaction mixture is then filtered off. The filtrate is then concentrated and the resulting residue is dissolved in 500 m of benzene. This solution was filtered under reduced pressure again, and the filtrate was concentrated to reduce the total volume to 1
00m sentence.

This concentrated solution was poured into 500 ml of methanol, the resulting precipitate was collected by filtration, and vacuum-dried at room temperature for 24 hours to obtain 43 g of allyldimethylsilyl ether of polyvinylphenol. The substance thus obtained is the electron beam resist composition of the present invention, and in this case, R in the general formula (I) described above is
1 is an allyl group, R2 and R3 are each a methyl group, and n=o.

Example ■ In the same manner as in Example I, 30 g of polyvinylphenol was added to 5
00 mJ1 of dichloromethane, 41 mM triethylamine was added to the resulting solution, followed by 36 g of vinyldimethylglorosilane and reacted at a temperature of 20-25°C for 24 hours. The product was isolated and purified in the same manner as in Example I to obtain 41 g of vinyl dimethylsilyl ether of polyvinylphenol.

In this case, R' in the aforementioned general formula (I) is a vinyl group, R2 and R3 are each a methyl group, and n=o.

Example ■ In this example, as in Example ■, 30 g of polyvinylphenol, 45 g of sodium iodide, and 16.8
g of powdered potassium hydroxide were dissolved in 500 ml of dimethylformamide and 40 g of the resulting solution chloromethyldimethylvinylsilane were added over a period of 30 minutes. 20~
The reaction was carried out at a temperature of 25°C for 2 hours, followed by a reaction at 60°C for 3.5 hours. The resulting mixture was poured into 200 mM ice water, and the resulting precipitate was washed three times with 200 mfL of water.

Thereafter, it was vacuum dried at a temperature of 40°C for 24 hours.

Through this treatment, the yield of vinyl dimethylsilyl methyl ether was 32 g.

In this case, R1 in the aforementioned general formula (I) is a vinyl group, R2 and R3 are each a methyl group, and n=1.

The electron beam resist composition of this invention contains methoxyethyl acetate, ethoxyethyl acetate and other acetate esters, low polar solvents such as benzene, toluene, xylene and other aromatic hydrocarbons, and dimethylformamide. and other amides, dioxane and other ethers, and can form a good film by spin coating. In this case, the lower resist of the two-layer resist method includes an optional polymer layer, such as PM.
MA, AZ resist (product name manufactured by Silapray), LM
R or phenol novolak resin can be used.

Nimuni 11 First, in this example, a polymer layer as a lower resist is formed on the St substrate using, for example, LMR (manufactured by Fuji Pharmaceutical Co., Ltd.).
is applied to a thickness of 1.5 gm by spin coating.

Next, this lower resist layer is baked at a temperature of 60° C. for 30 minutes. Thereafter, a solution in which 20% by weight of the electron beam resist composition of the present invention is dissolved in xylene is filtered through a filter with a pore size of 0.2 JLm, and the filtrate is applied by spin coating to form a thickness of 0°2 ILm.

Next, the substrate having the two-layer resist film was baked at a temperature of 60°C for 30 minutes, and then the upper resist film was applied with an accelerating voltage of 20 KV and a C/C of 9.6 l.
Drawing was performed using an electron beam with a dose (irradiation dose) of m2. Thereafter, baking was performed at 100° C. for 30 minutes.

Next, this substrate was developed for 5 to 10 seconds with a mixed solution of cyclohexane and isoamyl acetate in a volume ratio of 98=2, and then rinsed with cyclohexane.

When the obtained pattern was observed with a scanning electron microscope, it was confirmed that lines and spaces of 0.25 Bm were resolved.

Next, using the upper resist pattern thus obtained as an etching mask, the lower resist film was dry etched using a parallel plate dry etching apparatus.

At this time, the gas type was set to 02, the pressure was set to 5.0 Pa, and the
2 Gas flow rate is 20SCCM, power density is 0.08
Etching was performed for 25 minutes under conditions of W/am2.

When observed with a scanning electron IIrJ microscope, it was found that the two-layer resist pattern thus obtained resolved lines and spaces of 0.25 pm and had an aspect ratio of 6.

It was also found that under these etching conditions, the upper resist layer of the present invention was etched to a thickness of 400 nm.

(Effects of the Invention) As is clear from the above description, the electron beam resist composition of the present invention has high sensitivity and high dry etching resistance because a silicon-containing photosensitive group is introduced into polyvinylphenol. Therefore, it can be used as an upper layer resist in a two-layer coating method.

Therefore, since the resist is applied to the present invention as an upper layer resist, there is no need to bake the lower layer at a high temperature as in the conventional method when forming a resist pattern, and therefore, the process of forming a resist pattern is significantly simplified compared to the conventional method. do.

Furthermore, since the resist composition of the present invention is soluble in an aromatic hydrocarbon solvent, various types of lower layer resists can be selected.

Furthermore, since the resist of the present invention has high sensitivity, patterns with high aspect ratios can be formed with high throughput.

[Brief explanation of drawings]

The figure is a sensitivity curve diagram for explaining the present invention.

Claims (2)

[Claims] (1) An electron beam resist composition represented by the general formula (I) in which a photosensitive group containing a silicon atom is introduced into polyvinylphenol. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the general formula (I), n is 0 or 1. At least one of R^1, R^2 and R^3 is a vinyl group or an allyl group. or a chloromethyl group, and the remaining two are each one selected from a methyl group, a vinyl group, an allyl group, and a chloromethyl group. m is a positive integer.) (2) A step of applying a polymer layer as a lower resist on the substrate, and an electron beam resist represented by the general formula (I) in which a photosensitive group containing a silicon atom is introduced into polyvinylphenol as an upper resist on the lower resist. The process of forming a resist film of the composition, ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the general formula (I), n is 0 or 1. R^1, R^2, and R^ At least one of 3 shall be a vinyl group, an allyl group, or a chloromethyl group, and the remaining two shall each be one selected from a methyl group, a vinyl group, an allyl group, and a chloromethyl group. m shall be a positive integer. ) A step of selectively irradiating the resist film with an electron beam, a step of developing the irradiated resist film with an organic solvent, and a step of dry etching the polymer layer with reactive oxygen plasma using the upper resist pattern obtained by the development as a mask. A method for forming a resist pattern, comprising the steps of: