JPH02217855A - Negative type electron beam resist composition - Google Patents

Abstract

PURPOSE:To form resist patterns having an excellent image contrast and sectional shape by using a compsn. contg. a specific triazine compd., specific cresol novolak resin, alkoxymethylated melamine resin, and specific ester compd. CONSTITUTION:This compsn. contains the triazine compd. expressed by the formula I, the cresol novolak resin obtd. from cresol contg. >=30wt.% m-cresol, the alkoxymethylated melamine resin, and the ester compd. of polyhydroxybenzophenone and 1, 2-naphthoquinonediazide-4-sulfonic acid or 1, 2-naphthoquinonediazide-5-sulfonic acid. In the formula I, Z is the formula II; R<1> and R<2> denote an alkyl group; R<3> and R<4> respectively denote a hydrogen atom, hydroxyl group or carboxyl group. The solubility of the parts irradiated with electron beams in an alkaline developing soln. is suppressed in this way. The practicable resist patterns having the excellent sectional shape are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel negative electron beam resist composition. More specifically, the present invention can form a resist pattern particularly excellent in image contrast and cross-sectional shape, and can be developed with an organic alkaline aqueous solution, and is suitable for use in transistors such as transistor ICs, LSIs, and ultra-LSIs.
This invention relates to a negative-type electron beam resist #I composition that is suitably used in the manufacture of semiconductor devices such as.

Conventional Technology Semiconductor devices such as transistors, ICs, LSIs, and VLSIs are usually manufactured using lithography methods, i.e.,
[1] A photosensitive resin film laminated on a substrate such as a wafer is irradiated with light through a required patterning mask, and a resist pattern is formed by developing and rinsing. It is manufactured by a method in which a circuit is formed on a substrate by repeating etching or impurity diffusion treatment on the substrate several to several dozen times.

By the way, in recent years in the semiconductor industry, processing dimensions have become significantly smaller, and the integration degree of semiconductor memory has increased to 16M DRAM,
64MDRAM, 256MDRAM%IGDRAM
It is expected that this will lead to further development, and in line with this, many improvements have been proposed in resist materials, reduction projection exposure equipment, etc. in order to further miniaturize processing dimensions.

For example, by combining an improved positive photoresist made of a novolac resin and a naphthoquinone diazide compound with a reduction projection exposure device,
＋＊! It has become possible to obtain resist patterns of However, even with such a combination, it has been difficult to achieve smaller processing dimensions.

On the other hand, in recent years, special specification ASIC (
Application 5specific 1. C)
The demand for ASICs is increasing, and it takes time and effort to prepare masks to create ASICs with special specifications that only require small quantities, making it impossible to shorten product delivery times.
Since this is not economical, research is being conducted on a method in which an electron beam resist film is directly formed on a silicon wafer and a resist pattern is directly drawn without using a mask. However, in this method, 0
．． Although it is possible to form a resist pattern with a thickness of 5 μm or less on a silicon wafer, it is necessary to narrow down the electron beam irradiation spot and draw it directly, and the resist material used in this method has a tendency for adjacent resist patterns to overlap each other. In order to avoid bonding, strict characteristics are required, such as good image contrast, a large solubility difference between the electron beam irradiated area and non-irradiated area in the developer I, and an excellent cross-sectional shape. be done.

On the other hand, as a photoresist material, for example, a sensitive resin composition for printing consisting of an amino resin, a melamine resin, and an organic halide (U.S. Pat. No. 3,697,274), a novolac resin, a diazonaphthoquinone-based photosensitive resin composition, etc. A photosensitive coating composition comprising a type acid generator and a methylated melamine formaldehyde aminoblast (JP-A-60-2
63143) and the like are known. Generally, there is no commonality between photoresist materials and electron beam resist materials, and it is not always possible to apply photoresists to electron beam resists. Therefore, as a conventional electron beam resist, for example, polymethyl methacrylate
5-30225), polyglycidyl methacrylate [Journal of Electrochemical Society 4 (J, Electrochem, Soc,)
J, Vol. 118, No. 669 Hage (1971)],
Chloromethylated polystyrene (JP-A-57-17603
Publication No. 4) etc. are used.

However, these electron beam resists are developed using organic solvents, which poses problems in the working environment, and scum is likely to occur in resist patterns after development, resulting in deterioration of resist pattern accuracy such as adjoining fine patterns joining together. This has the disadvantage that it is difficult to obtain a resist pattern with a good cross-sectional shape and image texture.

On the other hand, 210~ as a thermosetting resin and a photoacid generator
An aqueous developable resist composition (Japanese Unexamined Patent Publication No. 16405/1983) is known which uses excimer laser-1 far ultraviolet rays, X-rays, etc. as an irradiation source, and is composed of a halogenated organic compound that absorbs actinic radiation in the range of 299 na+. It is being

However, although this resist composition has been shown to be sensitive to electron beams, the resist pattern obtained by electron beam irradiation has poor image contrast and has a high resolution cross-sectional shape that tends to have streaks. However, it is difficult to obtain a high-resolution pattern, which requires a long development time and is not practical.

Problems to be Solved by the Invention The present invention overcomes the drawbacks of conventional electron beam resist compositions, can form a resist pattern with particularly excellent image contrast and cross-sectional shape, and can be developed with an organic alkaline aqueous solution. This was made with the aim of providing a negative-tone electron beam resist composition having excellent properties such as the following.

Means for Solving the Problems As a result of intensive research to develop a negative electron beam resist composition having the above-mentioned excellent properties, the present inventors found that a specific triazine compound, a specific cresol novolak resin, and an alkali It was discovered that the object could be achieved by a composition containing a fukidimethylated melamine resin and a specific ester compound, and based on this knowledge, the present invention was completed.

That is, the present invention is based on the general formula (A), R1 and R2 are alkyl groups having 1 to 5 carbon atoms, R
(B) 30% by weight or more of n+-cresol (C) an alkoxymethylated melamine resin, and (D) a polyhydroxybenzophenone and 1,2-naphthoquinone cyasito-4-sulfonic acid or 1,2-naphthoquinone diazidol. The present invention provides a negative electron beam resist composition containing an ester compound with 5-sulfonic acid.

The present invention will be explained in detail below.

In the composition of the present invention, the triazine compound used as component (A) has a structure represented by the general formula CI), and representative examples of such compounds include:
2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(p-
ethoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(p-propoquinphenyl)-4,6-his(trichloromethyl)-1,
3,5-1-Ryazine, 2-(p-butoxyphenyl)
-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl) -1,,3,5-triazine, 2-( 4-ethoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4
-Propoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-)riazine, 2-(4-butoxynaphthyl)-4,6-bis(trichloromethyl')-
Examples include 1,3,5-) riazine. One type of these triazine compounds may be used, or two or more types may be used in combination.

Incidentally, a photopolymerizable composition using a triazine compound having a chloromethyl group as a photopolymerization initiator and a monomer having an ethylenically unsaturated group is known (JP-A No. 62-212401). ), no examples of its use in electron beam resist compositions have been known so far.

In the composition of the present invention, the Talesol novolak resin used as the fR component (B) contains cresol containing 30% by weight or more of m-cresol, preferably 30% by weight or more of m-cresol, and as the remaining component. p-
A mixed cresol containing at least one selected from cresol, 2,5-xylenol and 3,5-xylenol, more preferably m-cresol 3
0 to 70% by weight and at least one selected from p-cresol and 3,5-xylenol 70 to 30% by weight
It must be obtained from a mixed cresol consisting of.

By using such a resol novolac resin, it is possible to form a resist pattern that has excellent heat resistance and a cross-sectional shape that rises perpendicularly from the substrate.

Examples of the cresol novolac resin include 1-cresol, p-cresol, 2.5-xylenol, and 3.
It can be easily produced by subjecting mixed cresol and formaldehyde, each containing at least one selected from 5-xylenol in a predetermined ratio, to a condensation reaction in the presence of an acid catalyst. In addition, in order to increase the solubility difference between the developing solution on the electron beam irradiated area and the non-irradiated area and improve the image contrast, the weight average molecular weight of the Talesol novolak resin described above is set to 2,000 to 2,000.
A range of 20.000, preferably 3.000-15.000 is practical.

In the composition of the present invention, the alkoxymethylated melamine resin used as component (C) is obtained by converting the methylol group of methylated melamine obtained by a conventional method to an alkoxymethyl group, By using a melamine resin in which methylol groups are converted to an average of 2.5 or more, preferably 3.5 or more alkoxymethyl groups,
A resist solution with extremely excellent storage stability can be obtained. There are no particular restrictions on the type of alkoxymethylated melamine resin, and for example, methoxymethylated melamine resin, ethoxymethylated melamine resin, propoxymethylated melamine resin, butoxymethylated melamine resin, etc. can be used; Nikaratsuku Mx-750, Nikaratsuku Mx-032, Nikaratsuku Mx-706, Nikaratsuku Mx-708, Nikaratsuku Mx-40, Nikaratsuku Mx-31, Nikaratsuku M
s-11, Nikaratsuk Mv-22, Nikaratsuk Mw-3
0 (trade name, manufactured by Sanso Chemical Co., Ltd.), etc. can be preferably used. These alkoxymethylated melamine resins may be used alone or in combination of two or more.

In the composition of the present invention, polyhydroxybenzophenone and 1,2-naphthoquinonediazide are used as component (D).
4-sulfonic acid or 1,2-naphthoquinonediazide-5
- Ester compounds with sulfonic acids are used. As the polyhydroxybenzophenone, for example, 2.3.4
- Trihydroxybenzophenone, 2.3.4.4'
-Tetrahydroxybenzophenone, 2.2', 4.4
Preferred examples include '-tetrahydroxybenzophenone. These polyhydroxybenzophenones are
Each may be used alone, or two or more types may be used in combination.

In the composition of the present invention, any ester compound as described above can be used, but a particularly preferred ester compound is one in which the hydroxyl groups of the polyhydroxybenzophenone used are esterified by an average of 40% or more (hereinafter referred to as average esterification). 40% or more).

By using a resist having an average degree of esterification of 40% or more, the resulting resist pattern has significantly improved image contrast and cross-sectional shape.

The average degree of esterification in the present invention is defined as the number of naphthoquinonediazide groups/the number of naphthoquinonediazide groups by analyzing the ester compound by liquid chromatography (GPC) and measuring the number of hydroxyl groups and the number of 7-toquinonediazide groups in the ester compound. (
This is a value calculated using 100 (number of hydroxyl groups + number of naphthoquinonediazide groups).

Regarding the blending ratio of each component in the composition of the present invention, the weight ratio of the Talesol novolac resin as the component (B) and the alkoxymethylated melamine resin as the component (C) is 60.
: 40 to 95:5, preferably 75:25
It is preferable to use them in a ratio of 90:10 to 90:10. If the ratio of component (B) and component (C) deviates from the above range, scum will occur during the development process, the cross-sectional shape of the resulting resist pattern will deteriorate, and an image with good image contrast may not be obtained. This is not preferable because it is difficult to use, and the storage stability of the resist solution may also be reduced.

The triazine compound as component (A) is usually 2 to 10% by weight, preferably 3% by weight, based on the total amount of the Talesol novolac resin and the alkoxymethylated melamine resin.
It is blended in a range of 7% by weight. This amount is 2% by weight
If it is less than 10% by weight, the object of the present invention cannot be fully achieved, and if it exceeds 10% by weight, the image contrast of the resulting resist pattern tends to deteriorate, which is not preferable.

On the other hand, the ester compound as component (D) is usually 1 to 15% by weight, preferably 3 to 15% by weight, based on the total amount of the Talesol novolac resin and the alkoxymethylated melamine resin.
It is blended within the range of 10% by weight. This amount is 1% by weight
If it is less than 15% by weight, the object of the present invention cannot be achieved and a practical resist pattern cannot be obtained, and if it exceeds 15% by weight, the solubility of the unexposed area in the developer decreases, resulting in a decrease in contrast. This is not desirable as it may lead to

The negative electron beam resist composition of the present invention is usually used in the form of a solution by dissolving each of the above components in an organic solvent. Examples of organic solvents used in this case include ketones such as acetone, methyl ethyl ketone, cyclohexanone, and inamyl ketone; monomethyl ether, monopropyl ether, and Examples include polyhydric alcohols and derivatives thereof such as butyl ether or 7-722 ether; cyclic ethers such as dioxane; and esters such as methyl acetate, ethyl acetate, butyl acetate, and ethyl lactate. These may be used alone or in combination of two or more.

The compositions of the present invention may optionally contain compatible additives, such as additional resins, to the extent that the objects of the present invention are not impaired.
Conventional additives can be added, such as plasticizers, stabilizers, or colorants and antihalation dyes to make the developed image more visible.

Next, to explain a method of forming a fine pattern using the solution of the electron beam resist composition prepared in this way, first, a solution of the electron beam resist composition is placed on a substrate such as a silicon wafer. After coating with a spinner and drying to form an electron beam sensitive layer, this is selectively irradiated with electron beams and further heated at a temperature in the range of 90 to 140°C to increase development sensitivity. and then, for example, 2 to 5% by weight of Tetra 4. By developing with an organic alkaline aqueous solution such as methylammonium hydroxide or furin aqueous solution, the portions not irradiated with the electron beam are selectively dissolved and removed, resulting in a resist pattern with excellent image contrast and cross-sectional shape. Can be done.

The heat treatment after electron beam irradiation is a treatment for increasing development sensitivity, and is essential for achieving the object of the present invention. If this processing temperature is less than 90°C, practical sensitivity cannot be obtained, and if it exceeds 140°C, adjacent resist patterns in fine patterns tend to bond with each other.
Good image contrast becomes difficult to obtain.

Furthermore, although the composition of the present invention is an electron beam resist composition, in addition to electron beams, X-rays or the like can also be used as the irradiation source.

Effects of the Invention The negative electron beam resist composition of the present invention contains polyhydroxybenzophenone and 1,2-naphthoquinonediazide-4.
-sulfonic acid or 1,2-naphthoquinonediazide-5-
It is believed that by blending an ester compound with sulfonic acid, the solubility of the electron beam irradiated area in an alkaline developer can be suppressed, and a practical resist pattern with an excellent cross-sectional shape can be obtained.

The composition of the present invention can form a resist pattern with excellent image contrast and cross-sectional shape, and can be developed with an organic alkaline aqueous solution, so it is extremely useful as a resist for forming fine patterns essential for the production of semiconductor devices such as VLSI. Useful.

“Example I The present invention will now be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 ■-Cresol and p-cresol in a weight ratio of 60:40
4.5 g of cresol novolak resin (weight average molecular weight 4000) obtained by adding formalin to this and condensing it in a conventional manner using a sholic acid catalyst and an average degree of alkoxymethylation of 3.5. Nikaratsuku Mx-750, a methoxymethylated melamine resin (Sansho Chemical Company I)
I) 0.59 and dissolved in 15 g of ethyl lactate,
In this solution, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-1 was added to the total amount of Talesol novolak resin and methoxymethylated melamine resin.
, 4 wt. %) at a ratio of 3% by weight, and the resulting solution was filtered under pressure using a membrane filter with a pore size of 0.2 μm to obtain a resist solution.

Next, the resist solution thus obtained was spin-coded on a 4-inch silicon wafer whose surface had been treated with hexamethyldisilazane at 400 rpm for 20 seconds, and dried on a hot plate at 80° C. for 90 seconds.
A resist layer with a thickness of 5 μm was obtained.

Next, apply Hitachi 1! to this resist layer. HHS-2
After selectively irradiating an electron beam at an accelerating voltage of 20 kW using R, heat treatment was performed at 110°C for 90 seconds, and then immersion in a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 4 minutes. The non-irradiated portions of the lines were dissolved and removed to obtain a resist pattern. It was confirmed using an electron microscope that this resist pattern had a residual film rate of 90% or more in the irradiated area, and had a good cross-sectional shape perpendicular to the silicon wafer surface, weighing 0.3 g. The image contrast was also extremely good, and there was no bonding between adjacent patterns.

This cross-sectional shape is shown in the drawing.

Examples 2 to 11, Comparative Examples 1 to 5 Composition of cresol component in Talesol Novola 7 resin, type of alkoxymethylated melamine resin, mixing ratio of Talesol novolac resin and alkoxymethylated melamine resin, type and formulation of triazine compound The same operations as in Example 1 were performed, except that the amount and the type and amount of the ester compound were changed as shown in the table, and the cross-sectional shape of the pattern of each resist composition was evaluated. The results are shown in the table. In all Examples 2 to 11, the residual film rate was 90.
% or more of resist patterns were obtained, and no bonding between adjacent patterns could be confirmed.

On the other hand, in Comparative Examples 1 to 5, many connections between adjacent patterns were observed in the fine pattern portion.

In addition, a of the cross-sectional shape of the pattern is shown in Fig. 1, b is shown in Fig. 2,
, c means what is shown in FIG.

Note 1) The blending amount is based on the total amount of component (B) and component (C). Nikaratsu Mx-750: Methoxymethylated melamine resin with an average degree of alkoxymethylation of 3.5 Nikaratsu My-30: Average alkoxy Methoxymethylated melamine resin (A)-1 with a methylation degree of 5.5: 2-(p-methoxyphenyl)-4,6
-bis(trichloromethyl)-1,3,5-triazine(A)-272-(4-methoxynaphthyl)-4,6-
Bis(trichloromethyl)-1,3,5-triazine (D)-142,3,4-trihydroxybenzophenone 1,2-naphthoquinone cyasito-5-sulfonic acid ester (D)-272,3,4, 1,2-7toquinonediazide 5-sulfonic acid ester of 4'-tetrahydroxybenzophenone 8) (D)-3: 1,2-naphthoquinonediazide of 2.2',4.4'-tetrahydroxybenzophenone 5-sulfonic acid ester 9) (D)-4: 1,2-naphthoquinonediazide-4-sulfonic acid ester of 2.2',4.4'-tetrahydroxybenzophenone

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are diagrams showing different cross-sectional shapes of resist patterns. Patent applicant Tokyo Ohka Kogyo Co., Ltd.

Claims (1)

[Claims] 1 (A) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Z in the formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼ where R^1 and R^2 are alkyl groups with 1 to 5 carbon atoms, R^3 and R^4 are hydrogen atoms, hydroxyl groups, or carboxyl groups, respectively. may be the same or different), (B) a cresol novolak resin obtained from cresol containing 30% by weight or more of m-cresol, (C) alkoxymethyl melamine resin, and (D) polyhydroxybenzophenone and 1,2-naphthoquinonediazide-4-sulfonic acid or 1
, a negative electron beam resist composition comprising an ester compound of 2-naphthoquinonediazide-5-sulfonic acid. 2. The cresol novolac resin contains 30% by weight or more of m-cresol, and the remaining components include p-cresol,
2. The negative electron beam resist composition according to claim 1, which is obtained from a mixed cresol containing at least one selected from 2,5-xylenol and 3,5-xylenol. 3. The negative-type electronic device according to claim 2, wherein the 3-cresol mixture consists of 30 to 70% by weight of m-cresol and 70 to 30% by weight of at least one selected from p-cresol and 3,5-xylenol. Line resist composition. 4. The negative electron beam resist composition according to claim 1, wherein the 4-alkoxymethylated melamine resin has an average degree of alkoxymethylation of 2.5 or more. 5-polyhydroxybenzophenone is at least one selected from 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone The negative electron beam resist composition according to any one of claims 1 to 4. 6. The negative electron beam resist composition according to claim 1, wherein the ester compound has an average degree of esterification of 40% or more. 7 Add 1 to 1 ester compound to the total amount of cresol novolak resin and alkoxymethylated melamine resin.
7. The negative electron beam resist composition according to claim 1, wherein the negative electron beam resist composition contains 5% by weight.