JPS63161449A - High contrast photoresist composition - Google Patents

Abstract

PURPOSE:To obtain a high contrast photoresist compsn. giving a fine pattern with high dimensional controllability by blending an alkalisoluble resin with a compd. having two or more naphtoquinone-1,2-diazido-5-sulfonyl groups and a specified compd. CONSTITUTION:An alkali-soluble resin as a film forming substance is blended with a compd. having two or more naphthoquinone-1,2-diazido-5-sulfonyl groups as a first photosensitive component and a specified monoester as a second photosensitive component to obtain a photoresist compsn. The monoester is prepd. by condensing an arom. compd. having a hydroxyl group in the molecule with naphthoquinone-1,2-diazido-5-sulfonyl chloride in the presence of weak alkali. The pref. ratio between the first and second photosensitive components is (1:0.5)-(1:3) and that of the photosensitive components and the alkali-soluble resin is (1:1)-(1:6). The resulting photoresist compsn. has high contrast and an accurately reproduce the dimensions of a fine pattern on a highly reflective substrate independently of a change in prebaking conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to high contrast photoresist compositions.

<Prior Art> Semiconductor elements are conventionally manufactured by microfabrication technology using photoetching. In recent years, patterns have become finer due to the increased integration of integrated circuits, and it is therefore desirable to form fine patterns on resists with high precision.

The higher the contrast, the less the effect on the geometric dimensions in photoresists patterned by various exposure methods. In other words, the higher the contrast, the more accurately a fine pattern can be formed (Japanese Patent Application Laid-Open No. 61-97652).

In general, it is difficult to form fine patterns with high accuracy on highly reflective substrates such as aluminum or polysilicon with steps, but a high contrast resist provides good dimensional control of fine patterns even on highly reflective substrates.

As an improved method for controlling the dimensions of fine patterns on highly reflective substrates, a method has been proposed in which a light absorbing agent such as oil yellow is added to a photoresist (Japanese Patent Publication No. 37562/1982).

However, photoresists containing light absorbing agents form a coating film, and the light absorbing agents precipitate during storage after prebaking, or sublimate during blubbling, resulting in a decrease in concentration, resulting in unsatisfactory effects and variations. There were drawbacks.

<Problems to be Solved by the Invention> As a result of intensive studies to overcome the drawbacks of the above-mentioned prior art, the present inventors have completed the present invention.

An object of the present invention is to provide a photoresist composition with high contrast and good dimensional controllability of fine patterns on a highly reflective substrate even under changes in prebaking conditions.

Means for Solving the Problems> The present invention provides naphthoquinone-
Compounds having two or more 1,2-diazide-5-sulfonyl groups or naphthoquinone-1,2-diazide-4-sulfonyl groups and general formula (D1 naphthoquinone-1,2
-diazido-5-sulfonyl group or naphthoquinone-1,
It is a 2-diazide-4-sulfonyl group. Also, R1%
R,,R, is an alkyl group, an allyl group, an aralkyl group, -
It is a Q-C rhoQ group or a hydrogen atom. ) A high-contrast photoresist composition comprising the following compounds.

The compound used as the first photosensitive component of the composition of the present invention is a compound having two or more naphthoquinone-1,2-diazido-5-sulfonyl groups or naphthoquinone-1,2-diazide-4-sulfonyl groups. , these are compounds having two or more hydroxyl groups and naphthoquinone-1,2-diazide-5-sulfonyl chloride or naphthoquinone-1,
It is obtained by condensing 2-diazide-4-sulfonyl chloride in the presence of a weak alkali. Examples of compounds having two or more hydroxyl groups include hydroquinone, resorcinol, phloroglucin, 2゜4-dihydroxybenzophenone, 2.3.4-trihydroxybenzophenone, 2,3,4゜4゜-tetrahydroxybenzophenone, Examples include 2°2°, 4.4°-tetrahydroxybenzophenone, and gallic acid alkyl ester.

The compounds used as the second photosensitive component are aromatic compounds having one hydroxyl group in the molecule and naphthoquinone-1,2
It is a special monoester obtained by condensing -diazide-5-sulfonyl chloride or naphthoquinone-1,2-diazide-4-sulfonyl chloride in the presence of a weak alkali. Aromatic compounds having one hydroxyl group in the molecule include m-cresol, p-cresol, and p-cresol.
-nonylphenol, 4-hydroxybenzophenone,
Examples include p-tert-butylphenol, 2,4.6-tritart-butylphenol, 3.5.6-tortotrimethylphenol, Ritoshimaruphenol, and the like.

Various alkali-soluble resins are used as the film-forming substance used in the present invention. Examples of the alkali-soluble resin include novolac resins produced from phenols and formaldehyde, styrene-maleic anhydride copolymers, acrylic resins having carboxyl groups, and hydroxystyrene polymers. Preferably cresol novolak resins synthesized from m-cresol and/or p-cresol and formalin, m- and p-
Cresol-based novolac resins synthesized from cresol, 3,5-xylenol, and formalin, etc.
Specifically, it is shown in Japanese Patent Application Laid-open No. 159846/1984.
Here are some methods.

The blending ratio of the first photosensitive component and the second photosensitive component is 1:0°5
It is preferable to use the ratio in the range of 1:3 to 1:3.

The blending ratio of photosensitive component and alkali-soluble resin is 1:1 to 1:
It is preferable to use the range of 6.

When the ratio of the second photosensitive component is small, the contrast is low;
If it is too high, the residual film rate will be low, which is not preferable. Furthermore, if the amount of the alkali-soluble resin is too large, the fidelity of the resist image will be poor and the transferability will be poor, and if it is too small, the uniformity of the resist film will be poor and the resolution will be reduced.

The composition of the present invention is used in the form of a solution by dissolving the photosensitive component and the alkali-soluble resin in a suitable solvent.

The solvent used here is preferably one that provides a uniform and smooth coating film after the solvent evaporates at an appropriate drying rate.

Examples of such substances include ethyl cellosolve acetate, methyl cellosolve acetate, propylene glycol monomethyl ether acetate, ethyl cellosolve, methyl cellosolve, cyclohexanone, inamyl ketone, methyl isobutyl ketone, butyl acetate, xylene, and the like. These may be used alone or in combination of two or more.

The compositions of the present invention may also contain small amounts of additional resins, plasticizers, dyes, etc. as additional additives.

An example of a preferred method of using the composition of the present invention is shown below.

The composition of the present invention is applied to a substrate such as a silicon wafer, aluminum or a wafer with a polysilicon film using a spin coater or the like, and then prebaked using a direct contact hot plate to obtain a solvent-friendly coating film.

Next, exposure is performed using a reduction projection exposure device (stripper) through a reticle on which a desired mask pattern has been drawn. After-bake in a function oven, etc. if necessary. Next, the exposed substrate is developed using an automatic developing machine using, for example, a 1 to 3% tetramethyammonium hydroxide aqueous solution. As a result, the portions solubilized by exposure are selectively dissolved and removed, making it possible to obtain an image faithful to the mask pattern.

FIG. 1 shows the relationship between the normalized film thickness of the resist coating film and the exposure amount, and in the figure, the curve E is an example of the relationship between the remaining thick film and the exposure amount.

The number of films was determined by measuring sensitivity and contrast from this curve. Generally, the higher the gamma (y) value, the higher the contrast;
The performance of the resist/developer system is good.

A preferable gamma value is 3 or more. The gamma (γ) value is calculated using the following formula.

The photoresist composition of the present invention has high contrast and can stably and accurately reproduce the dimensions of a fine pattern on a highly reflective substrate even when prebaking conditions change.

<Examples> The present invention will be specifically explained below using Examples and Comparative Examples, but the present invention is not limited thereto.

Synthesis Example 1 2.3.4-) lyhydroxybenzophenone 38g (0
, 17 mol) and naphthoquinone-1,2-diazide-5-
Dissolve 55 g (0.20 mol) of sulfonyl chloride in 506 g of dioxane and add 32 g of 6% aqueous sodium carbonate solution.
0 g was added dropwise over 3 hours at 25° C. or below while stirring. Next, a dilute hydrochloric acid solution prepared by diluting 4 g of 35% hydrochloric acid with 1,500 g of ion-exchanged water was added to precipitate the reactant, and the resulting precipitate was thoroughly washed with ion-exchanged water, water was removed, and then dried.

The dried product thus obtained was dissolved in tetrahydrofuran, and its composition was determined by liquid chromatography. The contents were 38.5% triester, 22.1% diester, 28.2% monoester, and 11.2% unreacted materials.

Synthesis Example 2 A reaction product was obtained in the same manner as Synthesis Example 1 except that 22 g (0.20 mol) of m-cresol was used. Analysis of the reaction product revealed that it contained 99% ester and 1% unreacted material.

Synthesis Example 3 A reaction product was obtained in the same manner as in Synthesis Example 1 except that 22 g (0.20 mol) of p-cresol was used. Analysis of the reaction product revealed that it contained 99% ester and 1% unreacted material.

Synthesis Example 4 A reaction product was obtained in the same manner as Synthesis Example 1 except that 40 g (0.20 mol) of 4-hydroxybenzophenone was used. Analysis of the reaction product revealed that it contained 99% ester and 1% unreacted material.

Synthesis Example 5 A reaction product was obtained in the same manner as in Synthesis Example 1 except that 44 g (0.20 mol) of p-nonylphenol was used.

Analysis of the reactants revealed 98% ester and 2 unreacted substances.
%Met.

Examples 1 to 4, Comparative Examples 1 to 3 The reaction products of Synthesis Examples 1 to 5 were added in the amounts shown in Table 1 to 10 g of cresol novolac resin (molecular weight 15,000, polystyrene equivalent), and ethylene A photoresist composition was prepared by dissolving in 36 g of glycol monoethyl ether acetate. These resist compositions were spin-coded onto a wafer with an aluminum film (M thickness: 10,000 mm), and prebater was performed on a hot plate at 100° C. for 1 minute to obtain a resist film with a thickness of 1.28 μm. It was exposed using a stepper (model 4800-DSW manufactured by GCA) and after-baked in a convection oven at 90° C. for 30 minutes. Stationary paddle development for 60 seconds at 23°C with a 2.38% tetramethylammonium hydroxide aqueous solution, washing with water,
Dry. The obtained pattern was subjected to scanning electron microscopy (SE
M) was observed with an optical microscope (OM) and the remaining film thickness was measured, and the results shown in Table 1 were obtained. The results shown in Table 1 show that the resist composition of the present invention has high contrast and well prevents halation from the aluminum substrate.

Examples 5 to 7, Comparative Examples 4 to 6 Using the resist compositions of Example 1 and Comparative Example 1, the results shown in Table 2 were obtained by changing the prebake temperature.

It can be seen that the resist composition of the present invention shows little change in performance due to variations in prebaking conditions.

FIG. 1 is a diagram showing the relationship between the normalized film thickness of a resist coating film and the exposure amount.

Claims (2)

[Claims] (1) Naphthoquinone-1 for alkali-soluble resin
, 2-diazide-5-sulfonyl group or naphthoquinone-
Compounds having two or more 1,2-diazido-4-sulfonyl groups and general formulas ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, D is naphthoquinone-1,2-diazide-5-sulfonyl group or naphthoquinone- 1,2-diazide-4-
It is a sulfonyl group. In addition, R_1, R_2, and R_3 are an alkyl group, an allyl group, an aralkyl group, a ▲ mathematical formula, a chemical formula, a table, etc. ▼ group, or a hydrogen atom. ) A photoresist composition comprising a compound represented by: (2) Compounds having two or more naphthoquinone-1,2-diazide-5-sulfonyl groups or naphthoquinone-1,2-diazide-4-sulfonyl groups and general formulas ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula , D is naphthoquinone-1,2-diazide-5-sulfonyl group or naphthoquinone-1,2-diazide-4-
It is a sulfonyl group. In addition, R_1, R_2, and R_3 are an alkyl group, an allyl group, an aralkyl group, a ▲ mathematical formula, a chemical formula, a table, etc. ▼ group, or a hydrogen atom. 2. The photoresist composition according to claim 1, wherein the compounding ratio of the compound represented by the following formula is in the range of 1:0.5 to 1:3.