JPH02118663A - Process for forming resist pattern - Google Patents

Abstract

PURPOSE:To obtain a pattern having high precision by forming a hardly soluble layer in an exposed part of a photoresist layer prior to whole surface exposure of the photoresist layer by subjecting the photoresist layer to previous exposure and alkali treatment. CONSTITUTION:A resist layer 12 on an Si substrate 11 is exposed to far ultraviolet rays so as to form a predetermined line/space, then developed with an aq. soln. of tetramethyl ammonium hydroxide(TMAH). The development is interrupted by washing with water, then a hardly soluble layer 13 is formed by drying the developed resist layer 12. The resist layer 12 contg. the formed hardly soluble layer 13 is exposed wholly to ultraviolet rays, then developed with an aq. soln. of TMAH. Thus, a fine resist pattern having sufficiently good shape is formed with high precision.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming a resist pattern, and more specifically, it is useful for microfabrication of semiconductors. [Summary of the Invention] The method for forming a resist pattern of the present invention is , by performing preliminary exposure and alkali treatment to form a hardly soluble layer in the exposed portion of the photoresist layer, before exposing the entire surface of the photoresist layer consisting of an alkali-soluble resin and a photosensitizer.
This allows highly accurate pattern formation.

[Conventional technology]

In recent years, image reverse (ImageReve) has been used as a resist pattern forming method in the semiconductor manufacturing field.
rse) method is attracting attention.

This image reversal method provides a good resist pattern in microfabrication of semiconductors using g-line and i-line.
Moreover, the method can also be applied to excimer laser lithography.

This image reversal method involves first applying a photoresist layer material to a silicon substrate and drying it, then heating the obtained photoresist layer to reverse the so-called positive and negative, and then reversing the obtained photoresist layer. A negative image is formed by the process of exposing the entire surface of the resist layer to light and developing it to form a pattern on the photoresist layer.

[Problem to be solved by the invention]

However, the formation of a resist pattern using this image reverse method had the problem that as the fa of the pattern became thinner, the shape of the pattern due to exposure and development became defective, making it impossible to obtain a pattern with a good shape. .

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages, and to provide a method for forming a resist pattern that is useful for microfabrication of semiconductors.

[Means to solve the problem]

The method for forming a resist pattern of the present invention includes a step of forming a photoresist layer made of an alkali-soluble resin and a photosensitive agent on a substrate, and pre-exposure and alkali treatment of the photoresist layer so that the exposed portions of the photoresist layer are not easily exposed. The method includes a step of forming a solubilized layer, and a step of exposing and developing the entire surface of the photoresist layer including the hardly soluble layer to form a pattern on the photoresist layer.

The photoresist 1 material used in the present invention consists of an alkali-soluble resin and a photosensitizer.

Here, examples of the alkali-soluble resin include phenol, 0-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3
,4-xylenol 3,5-xylenol, or α
- Novolac resins obtained by condensing compounds with phenolic hydroxyl groups such as naphthol and β-naphthol with aldehydes such as formaldehyde, acetaldehyde, and henzaldehyde, or those containing silicon atoms in the resins. Can be mentioned.

As a resin containing silicon atoms, there is a resist material previously proposed by the present applicant (Japanese Patent Application No. 61-1
No. 89821). This resist material has the following formulas: and - pattern hole (2) (in both formulas, R1 and R□) are lower alkylene groups,
3, R4, R10% R11 and R+2 are I+, Kano, C
113 or CI+2011, R5-R8 is a lower alkyl group, R13 is C112 or C1 (20CH, A is phenol, a phenol derivative having 1 to 3 substituents or (R34 is a lower alkylene group, R13, RI6 and R1
7 represents a lower alkyl group), X is a number greater than O and less than or equal to 1, and Y is not O or l-X). . Examples of the phenol derivatives constituting this resist material include 0-lm- and p-cresol, xylenol, and redulucinol.

In addition, in each of the above formulas, the ratio of X and Y is arbitrary, but considering the developability in an organic alkali aqueous solution, Y is 0.
．． 7 or less is preferable.

An example of manufacturing this resist material is shown below.

First, equation (3) The monomer shown was synthesized by the following method.

500m with a reflux condenser installed! In a three-bottle flask with a volume of 50 ml of 3-hydroxy alcohol
g (0,4mo#), benzyl chloride 51g (0,
4mop), anhydrous potassium carbonate 1 ] Og (0,8
m.

I! ), and 200 mj of anhydrous acetone! The mixture was refluxed for 6 hours to complete the reaction. The produced Hennle ether compound was extracted with ether and dried over magnesium sulfate (yield 90%). Next, 30 g (0
, 14 moρ) was dissolved in carbon tetrachloride, and 16.7 g (0,062 moj) of phosphorus tribromide was added dropwise over 2 hours under water cooling to react, and then this solution was poured into ice water to remove any unreacted The bromide produced was purified by silica gel chromatography using n-hexano as the developing solvent (yield 60%).Next, a nitrogen blowing tube, reflux condenser, and dropping funnel were each attached. 500
m7! Magnesium 1.93g in a three-necked flask
(0,079 gram atom) and anhydrous ether 4 Qmj
! and cooled with water, add 20 g (0.07 m
offi) anhydrous ether 100rn7! melted into 2
It dripped over time. After this, the reaction was continued for another 2 hours, and then 6.6 g of dimethylchlorosilane (0.07 moff
) was added dropwise, left overnight at room temperature, and purified by distillation under reduced pressure (
0.6 order (11 g, boiling point 140°C) (yield 60%)
.

Next, if 5 g (0,019 moff) of this distilled product is used as a compound in which 5% of the compound is diluted, a simple substance corresponding to this compound can be obtained.

Next, 5.4 g (0,0156 moff) of a small amount of the above formula (3) which is a siloxane phenol, 1.14 g of Polmarin (37% aqueous solution), 1.6 g of ethyl cellosolve acetate and oxalic acid dihydrate. Japanese product 27 nt
g into a 100 mβ capacity eggplant-shaped flask, and
The reaction product was heated and stirred at 0°C for B hours, and the reaction product was washed with water and purified under reduced pressure to obtain a polymer mainly represented by formula (4).

In addition, as a tying agent, for example, quinonesia such as naphtho-1-nondiazide sulfonyl chloride (in the formula:
R1 and R2 may be the same or different, and each represents an alkyl group having 1 to 3 carbon atoms; ) are listed.

Furthermore, examples of the solvent in which the photoresist 4A material is prepared include cellosolve solvents and mixed solvents of these and other solvents.

Exposure in the present invention includes preliminary exposure and normal full-surface exposure, but the preliminary exposure is weak enough to form a hardly soluble layer and cause scratches. As a light source for exposure, the photosensitizer is 300 to 450
Arc lamps, mercury lamps, and metal halide lamps are used because they have spectral absorption on the order of mm.

For the alkali treatment and development in the present invention, a commonly used development method may be applied. Examples of the alkali used in the alkali treatment include thorium hydroxide,
Potassium hydroxide, sthorium carbonate, sthorium chloride,
Inorganic alkalis such as sodium metasilicate and aqueous ammonia, secondary amines such as ethylamine, n-propylamine, and di-n-propylamine, tertiary amines such as triethylamine and methyldiethylamine, and tetramethylammonium J1 hydrooxide. , aqueous solutions of quaternary amines such as trimedylhydride-methylammonium hydroxide, or solutions to which alcohol, surfactants, etc. are added.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

〔Example〕

Embodiment 2 - This embodiment will be described based on the drawings. First, a positive type silicon-containing resist material is placed on a silicon substrate with a thickness of 0.4 μm.
It was applied to a thick layer, and then the whole was dried at 90° C. for 90 seconds. (Fig. 1A) The obtained resist layer was exposed to deep ultraviolet rays (center wavelength: 248 nm) at 30 mJ/a (Fig. 1B) to form lines/spaces of 0.5 μm, and then tetramethylammonium After developing at 20° C. for 5 seconds using a 3.2% aqueous solution of hydroxide (TMAH), wash with water to interrupt the development and dry to form a poorly soluble layer (Figure 1C). UV light (wavelength: 4
36 nm) by full-surface exposure (intensity: 200 rn J
/cJ) L (Fig. 1D), then 3.2 of TMAH
% aqueous solution at 20°C for 5 seconds (Figure 1E)
.

It was confirmed that the obtained resist pattern was a negative/positive reversal pattern with a good shape.

1111 AZ1350 (trade name, manufactured by Schifley Co., Ltd., positive resist) was applied onto a silicon substrate to a thickness of 0.5 μm, and then the whole was dried at 90° C. for 90 seconds.

The obtained resist layer was exposed to deep ultraviolet Il! (Center wavelength: 243
0.5 μm line/space exposure (
Intensity = 30 mJ/cII, then 20°C using AZ Developonper (trade name, manufactured by Schiffley, developer)
I developed it for 3 seconds. Thereafter, the development was interrupted by washing with water, and the film was dried to form a hardly soluble layer.

The resist layer including the obtained hardly soluble layer was exposed to ultraviolet light (wavelength: 4
36 nm) by full-surface exposure (intensity: 200 m J /
c+a) Then, using AZ Daybelo Soba, 20
Developed at ℃ for 8 seconds.

It was confirmed that the obtained resist pattern was a negative/positive reversal pattern with a good shape.

〔Effect of the invention〕

As detailed above, the resist pattern forming method of the present invention can form fine resist patterns with a high sensitivity and good shape (more than 3 times as high as that of conventional forming methods), and is suitable for microfabrication. It is also possible to apply it to excimer laser lithography, which is considered to be a promising method, and is extremely useful in the field of semiconductor manufacturing, for example, and has great industrial value.

[Brief explanation of drawings]

FIG. 1 is a side view sequentially showing an embodiment of the present invention. In addition, in the symbols used in the drawings, 11 -----------...-- Substrate 12 -----
−−−−−−−−−−−・Photoresist layer 13・
−1111−−−−−−−−=−・− It is a hardly soluble layer.

Claims (1)

[Claims] A step of forming a photoresist layer made of an alkali-soluble resin and a photosensitizer on a substrate, and pre-exposure and alkali treatment of the photoresist layer to form a hardly soluble layer in the exposed portion of the photoresist layer. A method for forming a resist pattern, comprising the steps of: exposing and developing the entire surface of the photoresist layer including the hardly soluble layer to form a pattern on the photoresist layer.