JPH01300248A - Photoresist composition - Google Patents

Abstract

PURPOSE:To improve the sensitivity of the title composition at the time of use the composition for lithography, and the allowability of the composition against an alkaline development condition at the time of developing it by incorporating an alkali soluble resin having silyl ether group, a specified photosensitive agent and a compd. capable of generating an acid by irradiating active rays in the composition. CONSTITUTION:The composition is composed of the alkali-soluble resin having the silyl ether group, the photosensitive agent shown by formula I and the compd. capable of generating the acid by irradiating the active rays. In formula I, R1 is alkyl group, etc., R2 is alkyl, alkenyl or hydroxyalkyl group, etc. And, the alkali-soluble resin is released a SiO bond in the presence of the acid, and formed a hydroxyl group. As the result, the solubility of the resin for an alkaline aqueous solution increases. Thus, the composition has the high sensitivity for the lithography using a deep UV ray and an excimer laser as a light source, and the excellent allowability against the alkali development.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoresist composition suitable for forming a fine resist pattern, and more specifically, a photoresist composition that has high sensitivity and high resolution for lithography using deep ultraviolet rays and excimer laser as a light source. It also relates to a positive photoresist composition that has excellent alkaline development tolerance. The photoresist composition of the present invention is suitable for LSI and ultra-LSI
In addition to being used to create high-density integrated circuits such as I, it can also be used to manufacture photomasks used in their manufacture, and is widely used in the field of electronic industry.

[Prior Art] In recent years, semiconductors have become increasingly highly integrated, and the demands for miniaturization are becoming more and more severe.

Therefore, in terms of manufacturing, it is becoming difficult to cope with conventional processes, and the introduction of new technologies is being considered. Efforts are being made to establish ultra-fine pattern processing technology by using deep ultraviolet rays with shorter wavelengths and excimer lasers instead of conventional ultraviolet rays as light sources used in lithography. Resist compositions used as excimer laser lithography resists include, for example, compositions whose main component is a resin that can be decomposed by irradiation with actinic rays, such as polymethyl methacrylate and polymethyl glutarimide, and cresol formaldehyde. A composition has been proposed in which a naphthoquinonediazide sulfonic acid ester derivative is mixed as a photosensitizer with an alkali-soluble resin such as a novolac resin.

However, although resist compositions containing the above-mentioned photodegradable resin as a main component have excellent resolution, they have poor sensitivity in the deep ultraviolet and excimer laser wavelength regions, and also have insufficient RIE resistance. There were some problems. Furthermore, although resist compositions using the naphthoquinonediazide sulfonic acid ester derivatives described above as photosensitizers have excellent sensitivity and RIE resistance, the naphthoquinonediazide sulfonic acid ester derivatives have poor absorption in the deep ultraviolet and excimer laser wavelength regions. Since it does not decrease after exposure, no matter what type of alkali-soluble resin is used as the main component, the surface layer of the resist will absorb light strongly, and the bottom of the resist will not be exposed sufficiently, resulting in the desired rectangular shape. There was a drawback that it was difficult to obtain a resist pattern having a profile of .

[Problems to be Solved by the Invention] As described above, conventional photoresist compositions have poor sensitivity, resolution, and
There is no solution that satisfies all the requirements such as RIE resistance, and it is still difficult to say that it is practical.

Therefore, the present invention has been made to solve the above-mentioned problems. That is, an object of the present invention is to provide a positive photoresist composition that has high sensitivity and resolution for lithography using deep ultraviolet rays and excimer laser as a light source, and also has excellent alkaline development tolerance. It's about doing.

[Means for Solving the Problems] In view of the above circumstances, the present inventors have made extensive studies and have developed an alkali-soluble resin having a silyl ether group as a resin component, and a deep ultraviolet and excimer laser as a photosensitive component. an alkali dissolution inhibitor having a specific structure that is highly sensitive to light and can significantly reduce absorption in the wavelength range of the light after exposure, and an alkali dissolution inhibitor that efficiently generates acid by irradiation with the light. By having a photoacid generator that is capable of The bonds are cleaved and hydroxyl groups are generated, increasing the alkaline solubility of the resin, and as a result, it becomes possible to increase the solubility difference between exposed and unexposed areas, resulting in improved sensitivity and resolution of the resist. The present inventors have discovered that the properties and development tolerance can be improved, and have completed the present invention.

That is, the present invention comprises a) an alkali-soluble resin having a silyl ether group, b) a photosensitizer represented by the following general formula (1), and c) a compound capable of generating an acid upon irradiation with actinic light The present invention provides a photoresist composition.

The photoresist composition of the present invention will be explained in detail below.

In the alkali-soluble resin having a silyl ether bond used as component (a) in the photoresist composition of the present invention, the 81-0 bond is cleaved in the presence of an acid to generate a hydroxyl group, resulting in increased solubility in an aqueous alkali solution. Examples of such resins include alkali-soluble resins containing structural units represented by the following general formula (II) and the following general formula (m). Here, R6, R7, and R8 in the formula (n) are each an alkyl group or an aryl group, R9 is a hydrogen atom, a methyl group, or an ethyl group, and R in the formula (m)
, o, R, , R12 are each an alkyl group or aryl W, and R+i is a hydrogen atom, an alkyl group, or a hydroxyl group.

The proportion of structural units having silyl ether bonds in the resin is not particularly limited, but the lower limit is preferably 5% or more of the total structural units of the resin. If this ratio is less than 5%, it will adversely affect the developability of the resist. Further, the upper limit of the ratio of the structural units cannot be generally limited because it differs depending on each resin, but it can be determined within a range that does not affect the alkali solubility of the resin and the development characteristics of the resist. Specific examples of such alkali-soluble resins having silyl ether bonds include those shown below, but are not limited thereto.

CHs \CH3 ゝC)+3 Furthermore, the resin has a weight average molecular m (Mw) of 1.000 to 100,000, preferably 2.000, as determined by gel permeation chromatography (GPC method) using polystyrene as a standard. ~50,000 is used.

If it deviates from the above range, it will have an adverse effect on sensitivity, resolution, heat resistance, film performance, adhesion to substrates, etc.

Next, the diazohomotetramic acid derivative used as the component in the photoresist composition of the present invention is represented by the general formula (1), in which R-, an alkyl group, (D-, or R'4, R'5, R"
3, R”4, R”S, R”3, R”4
, R11+ are each a hydrogen atom, an alkyl group, an alkoxy group, a nitro group, a nitroso group, an amino group, a hydroxyl group, or a phenyl group. Specific examples include, but are not limited to, the following. Note that these may be used alone or in combination.

The compounds used as component (c) in the photoresist composition of the present invention generate acids when irradiated with actinic light, particularly deep ultraviolet rays and excimer laser, and many of these compounds are generally widely known.

Examples of such compounds include halogenated diphenylethane derivatives represented by the following general formula (IV), sulfonic acid ester derivatives represented by the following general formula (V), and iodonium salts represented by the following general formula (Vl). , or a sulfonium salt represented by the following general formula (■).

The halogenated diphenylethane derivative represented by the above general formula (IV) produces a halogen acid upon irradiation with actinic rays, and R14 in the formula is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or a nitro group, R1 is a hydrogen atom, a hydroxyl group, or R21fCO-NH- (R2 & is an alkyl group), R+a is a halogen atom, R, , R, are each a hydrogen atom, a halogen atom, an alkyl group It is.

The sulfonic acid ester derivative represented by the above general formula (V) produces a sulfonic acid upon irradiation with actinic rays, and R1 in the formula is 5OIH of the sulfonic acid to be produced.
It is a group that blocks a site.

Such groups include (R7, is an alkylene group, an alkenylene group, or an arylene group SR1, SR2,, R3, SR3, and R
36 is each alkyl group or aryl group, R31
, R33 is an aryl group, and R34 and Rms are each a hydrogen atom, an alkyl group, or an aryl group.

) can be mentioned. Moreover, R2゜ is an alkyl group,
or an aryl group.

The iodonium salt represented by the above general formula (Vl) and the sulfonium salt shown by the above general formula (■) produce a Lewis acid upon irradiation with actinic rays, and R2+, R2! , R23, and R24 are aryl groups, R2s is an alkyl group or an aryl group, and X is BF
6-1PF@-”I AsF5-1SbF,-,Cto
, -.

Specific examples of such photoacid generators include (TV-
1) (rV-2) (IV-3)(
V-1) (V-2) (V-3) (V-4) (V-5) (V-6) (Vl-1)
(Vl-2) (■-1)
(■-2) etc., but are not limited to these. Further, these photoacid generator agents can be used alone or in combination of two or more.

There is no particular restriction on the content ratio of the diazotetramic acid derivative in component (a) in the present invention, but it is preferably a).
Component tree Ab + o o 0, 1 to 40 parts by weight
It is desirable to contain it in an amount of 1 to 20 parts by weight, more preferably 1 to 20 parts by weight. If it deviates from the above range, pattern shape and resolution will be adversely affected.

In addition, the content ratio of the photoacid generator as component (iii) in the present invention is 0.01 to 20 parts by weight, preferably 0.05 to 20 parts by weight, based on 100 parts by weight of the resin used as component (a).
It is desirable to contain it in an amount of 10 parts by weight. If the content is too large, pattern accuracy will be adversely affected.

The photoresist composition according to the present invention is soluble in organic solvents, and when used in the fabrication of integrated circuits, it is usually used in solutions (
It is used in the form of a resist solution). In this case, the composition generally contains 1 to 50% by weight in an organic solvent, preferably 5 to 50% by weight.
It is dissolved and adjusted at a ratio of 30% by weight. In this case, the solvent to be used is one that uniformly dissolves each component of the negative photoresist composition of the present invention, and after coating the surface of a substrate such as silicon or aluminum, evaporates the organic solvent to create a uniform and smooth surface. It is preferable to use a coating film that can be obtained. Specifically, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, and ether solvents such as tetrahydrofuran and diethylene glycol dimethyl ether. , ethylene glycol monoethyl ester, ethylene glycol monomethyl acetate, and other ester solvents, but are not limited thereto. The above organic solvents may be used alone or in combination of two or more.

In addition to the above-mentioned components, the photoresist composition of the present invention may optionally contain sensitizing columns, dyes, plasticizers, other resins, various inhibitors such as thermal reaction inhibitors, adhesion improvers, etc. I can do it. The photoresist composition of the present invention can be used to form a relief pattern using conventional photoresist techniques by adjusting the resist solution as described above. The method for forming this relief pattern will be explained below.

First, a resist solution prepared as described above is applied to a substrate. This application to the substrate can be performed using, for example, a spinner. This is then heated to a temperature of 260-120°C, preferably 80°C.
Dry at ~100°C for 20-60 minutes. After drying, the coated film is irradiated with deep ultraviolet rays and excimer laser through a positive photomask chart.

Next, a relief pattern is obtained by washing out the exposed area with a developer. As the developer, a weak alkaline aqueous solution of sodium hydroxide, potassium hydroxide, sodium metasilicate, tetramethylammonium hydroxide, etc., having a concentration of 5% by weight or less, can be used. The relief pattern thus formed has good resolution and contrast.

Furthermore, a substrate can be etched using the photoresist composition of the present invention and the pattern formed as described above as a mask.

[Example] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 Trimethylchlorosilane was reacted with 0.4 molar equivalent of poly-(p-hydroxystyrene) (number average molecular weight: 6000) to obtain a copolymer (SP-1) represented by the following formula.

To 16.0 g of this 5P-1, 1.2 g of a photosensitizer represented by the following formula and 0.3 g of a photoacid generator represented by the following formula were added, and these were dissolved in 18 ml of cyclohexanone. was filtered under pressure using a 0.1 μm pore filter to prepare a resist solution. This resist solution was coated onto a silicon wafer using a spin coater at 2300 rpm, and prebaked at 80°C for 40 minutes to obtain a coating of about 1.0 μm.

Next, this resist film was irradiated with light using a KrF excimer laser stepper. After irradiating with varying exposure doses, immersing in a 2.3% tetramethylammonium hydroxide aqueous solution for 60 seconds to develop, and rinsing by immersing in water for 30 seconds, the remaining film is plotted against the exposure dose. The sensitivity curve was defined as a sensitivity curve, and the exposure amount at which the residual film after development was 0 was defined as the sensitivity. The sensitivity of this resist is 121m
j/cm'. Furthermore, using this resist, a film with a thickness of 1 μm was formed on a silicon wafer in the same manner as above.
A 115-mm resist film was formed, and a 115-degree reduction projection exposure was performed using a KrF excimer laser stepper through a chromium mask having a pattern on the resist film. Furthermore, this resist film was coated with tetramethylammonium hydroxide 2.
．． It was developed by processing with a 3% aqueous solution (20° C.) for 60 seconds, and washed with water for 30 seconds to form a resist pattern.

As a result of observing the pattern thus formed using an electron microscope, it was found that a fine pattern of 0.5 μm with a good profile was resolved.

Example 2 0.2 molar equivalent of trimethylchlorosilane was reacted with poly-(α-methyl-p-hydroxystyrene) (number average molecular weight: 6300) to obtain a copolymer (SP-2) represented by the following formula. Ta.

To 6.0 g of this 5P-2, 1.2 g of a photosensitizer represented by the following formula and 0.3 g of a photoacid generator represented by the following formula were added, and these were dissolved in 18 ml of cyclohexanone. A resist solution was prepared by pressure filtration using a 1 μm pore filter. This resist solution was coated onto a silicon wafer using a spin coater at 2000 revolutions, and prebaked at 80° C. for 40 minutes to obtain a coating thickness of about 1.0 μm.

Next, the sensitivity of this resist film was measured in the same manner as in Example 1, and it was found that it had a sensitivity of 135 mj/cm2. Furthermore, using this resist, a resist pattern was formed on a silicon wafer in the same manner as in Example 1. As a result of observing the pattern thus formed using an electron microscope, it was found that a fine pattern of 0.5 μm with a good profile was resolved.

Example 3 Trimethylchlorosilane was replaced with p-hydroxystyrene-methyl methacrylate copolymer (number average molecular weight: 4200
, copolymerization ratio: p-hydroxystyrene:methyl methacrylate) = 9010) was reacted in an amount of 0.3 molar equivalent to obtain a copolymer (SM-1) represented by the following formula.

To this 5M-16.0 g, 1.2 g of a photosensitizer represented by the following formula and 0.3 g of a photoacid generator represented by the following formula PFs were added, and these were dissolved in 18 ml of cyclohexanone. was filtered under pressure using a 0.1 μm pore filter to prepare a resist solution. This resist solution was applied to a silicon wafer using a spin coater at 2500 rpm.
Prebaking was performed at 80° C. for 40 minutes to obtain a coating of approximately 1.0 μm.

Next, the sensitivity of this resist film was measured in the same manner as in Example 1, and it was found that it had a sensitivity of 117 mj/cm2. Furthermore, using this resist, a resist pattern was formed on a silicon wafer in the same manner as in Example 1. As a result of observing the pattern thus formed using an electron microscope, it was found that a fine pattern of 0.5 μm with a good profile was resolved.

Example 4 Trimethylchlorosilane was reacted with 0.3 molar equivalent of cresol formaldehyde novolac resin (number average molecular weight: 4800, meta-para ratio 2:1) to obtain a copolymer (SN-1) represented by the following formula. Ta.

To this 5N-16.0 g, add 1.2 g of a photosensitizer represented by the following formula and 0.3 g of a photoacid generator represented by the following formula, dissolve these in 18 ml of cyclohexanone, and further add this solution. 0.1μm
A resist solution was prepared by pressure filtration using a pore filter. This resist solution was applied to a silicon wafer using a spin coater at 2500 rpm, and then
Prebaking was performed for 1 minute to obtain a coating of approximately 1.0 μm.

Next, the sensitivity of this resist film was measured in the same manner as in Example 1, and it was found that it had a sensitivity of 142 mj/cm''.Furthermore, using this resist and in the same manner as in Example 1, silicon A resist pattern was formed on the wafer.The pattern thus formed was observed under an electron microscope, and it was found that a fine pattern of 0.5 μm with a good profile was resolved.

[Effects of the Invention] As explained above, the photoresist composition of the present invention not only has excellent sensitivity and resolution when used in lithography using deep ultraviolet rays and excimer laser as a light source, but also has excellent sensitivity and resolution during development. As a result of its excellent tolerance to alkaline development conditions, it is possible to obtain a fine resist pattern with a good profile. Therefore, these compositions can be used as resists for manufacturing high-density integrated circuits such as LSIs and VLSIs, where requirements for resolution will become increasingly strict in the future, as well as for manufacturing photomasks used in their manufacturing. It can be widely used in the field of electronic industry.

Claims (1)

[Scope of Claims] (1) A) An alkali-soluble resin having a silyl ether group, and B) The following general formula (I) ▲There are numerical formulas, chemical formulas, tables, etc.▼(I) [R_1 is an alkyl group, ▲Mathematical formula , chemical formulas, tables, etc.▼, or ▲mathematical formulas, chemical formulas, tables, etc.▼. R_2 is an alkyl group, an alkenyl group, a hydroxyalkyl group, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas, chemical formulas,
There are tables, etc. ▼, alkoxy groups, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, alkylamino groups, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ mathematical formulas, chemical formulas , tables, etc.▼(R_3, R_4,
R_5, R_3', R_4', R_5', R_3'', R
_4″, R_5″, R_3′″, R_4′″, R_5′
'' is a hydrogen atom, an alkyl group, an alkoxy group, a nitro group, a nitroso group, an amino group, a hydroxyl group, or a phenyl group), and c) a photosensitive agent that can generate an acid when irradiated with actinic rays. A photoresist composition containing a compound.(2) The alkali-soluble resin having a silyl ether group has the following general formula (II) ▲There are numerical formulas, chemical formulas, tables, etc.▼(II) [R_6, R_7, R_8 are each alkyl group or aryl group, R_9 is methyl group or ethyl group.] The photoresist composition according to claim 1, characterized in that it contains a structural unit represented by: (3) Silyl ether group An alkali-soluble resin having the following general formula (III) ▲Mathematical formulas, chemical formulas, tables, etc.▼(III) [R_1_0, R_1_1, R_1_2 are each an alkyl group or an aryl group, and R_1_3 is a hydrogen atom, an alkyl group, or a hydroxyl group. The photoresist composition according to claim 1, characterized in that it contains a structural unit represented by the following formula.