JPH01293339A - Photoresist composition - Google Patents

Abstract

PURPOSE:To improve sensitivity, definition and heat resistance by adding a photo-acid initiation contg. a sulfonate group to a specific polymer and a crosslinking agent contg. a specific group. thereby forming the compsn. CONSTITUTION:This compsn. is prepd. by adding the photo-acid initiator contg. the sulfonate group into the polymer contg. the formula I and the crosslinking agent contg. the group expressed by the formula II. In the formula I, R1 denotes hydrogen or alkyl group of 1-5C. In the formula, R2 denotes hydrogen, methyl group or alkyl group of 1-5C. The photo-acid initiator contg. the sulfonate group is thus combined with the polymer contg. hydroxystyrene and the crosslinking agent. The definition, sensitivity and heat resistance are thereby improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a resist material suitable for forming fine patterns applied to the manufacture of semiconductor integrated circuits, etc. The present invention relates to a photoresist composition having high sensitivity, high resolution, and high dry etch resistance and suitable for deep ultraviolet and excimer laser lithography.

[Prior art and problems to be solved by the invention] Conventionally,
Negative photoresist compositions based on cyclized rubber and containing a bisazide compound are well known and are still widely used in the manufacture of semiconductor integrated circuits and the like. As the cyclized rubber, cyclized polyisoprene or cyclized polybutadiene, which is obtained by partially cyclizing polyisoprene or polybutadiene under an acidic catalyst, is used, and as a bisazide compound, 2
6-bis(4'-azidobenzal)-4-methylcyclohexanone and the like are used. In these compositions,
The azide group is decomposed by light irradiation and active nitrene is generated. This nitrene reacts with the double bonds remaining in the cyclized rubber, crosslinks the cyclized rubber, and turns it into a polymer. After exposure, unexposed areas are removed by developing with an organic solvent to form a negative pattern.

In addition, halogenated polystyrene-based negative photoresist compositions are also well known, and many compositions have been published. For example, iodinated polystyrene, chloromethylated polystyrene, chlorinated polyvinyltoluene, etc. are known. These polystyrene resists are polymerized by the generation of halogen radicals by light irradiation and the resulting crosslinking of the polymer by the carbon radicals in the polymer chains. After exposure, unexposed areas are removed by developing with an organic solvent to form a negative pattern.

However, these resists have several problems when attempting to form a pattern of 1 micron or less, and their use is limited. These problems include insufficient pattern resolution, low heat resistance, and low sensitivity. In particular, the lack of resolution is significant, and there is a large difference from the resolution required for current resists. The reason for this is that the exposed area swells in the organic solvent developer.

Additionally, organic solvent developers are environmentally and health-hazardous;
It is also unfavorable in terms of flammability. Further, the heat resistance is also not satisfactory, and deformation of the pattern is observed at about 130°C.

Therefore, an object of the present invention is to provide a photoresist composition that has high resolution, high sensitivity, and high heat resistance and can be developed in an aqueous solution.

[Means for Solving the Problems] In view of the above circumstances, the present inventors have made extensive studies and have developed a polymer containing hydroxystyrene and an a priori generator containing a sulfonic acid ester group as a crosslinking agent. The present inventors have discovered that a photoresist composition that achieves the above object can be obtained by combining the above, and have completed the present invention.

That is, the present invention relates to a polymer containing the following general formula (1) (wherein R1 represents hydrogen or an alkyl group of 01 to C5) and a crosslinking agent containing a group represented by the following general formula (2). CH
20R2(2) (in the formula, R2 represents hydrogen, a methyl group, or an alkyl group of 01 to C5) is a photoresist composition prepared by adding a prior generator containing a sulfonic acid ester group, and the above-mentioned general Examples of the crosslinking agent containing the group represented by formula (2) include the following general formulas (3) to (5).
), where R3 is hydrogen, -C
Represents H, OCH3 or -CH,OH. ) (In the formula, R4 represents hydrogen or an alkyl group of 01 to C5.) (In the formula, R5 represents hydrogen or a methyl group, and X represents oxygen, a methylene group, or N-R6. Here, R6 represents C1 to (C5 alkyl group.) Examples of the a priori generator containing the sulfonic acid ester group include compounds represented by the following general formulas (6) to (9).

R8 (wherein R7 and RIO are aryl groups, R8 and R9 are hydrogen, aryl groups, C1 to C8 alkyl groups, or 01 to C8
8 represents an alkoxyl group. ) (In the formula, R11 and R16 represent an aryl group, and R12
, R13, R14 and R15 are hydrogen, aryl group, C1
~Represents a C8 alkyl group or a C1-C8 alkoxyl group. ) (In the formula, R17 and R19 represent an aryl group, and R18
represents a C1-C8 alkyl group. ) (wherein, R20
and R21 represents an aryl group or an 01-C8 alkyl group, and R22 represents an aryl group. ), a crosslinking agent, and an acid generator.

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

The a priori generator used in the photoresist composition of the present invention is
Must meet the following criteria:

That is, (1) the prior generator must be dissolved in the resist solution in an amount sufficient to promote crosslinking of the resin composition consisting of a polymer and a crosslinking agent during exposure or heating.

(2) The prior generator must not precipitate when this resist solution is applied onto the substrate.

(3) The prior generator must not react with the resin composition consisting of the polymer and crosslinking agent when not irradiated with light.

(4) The a priori generator must be storage stable in the resist solution.

(5) The prior generator must not evaporate from the resist film during pre-baking.

(6) The prior generator must be thermally stable to the extent that it does not generate acid during brebake.

(7) The prior generator must generate an acid that is difficult to diffuse in the resist film during exposure and subsequent intermediate baking.

Any compound that can generate acid upon exposure to light may potentially be used as an a priori generator. As a result of examining various compounds, the present inventors added a crosslinking agent to a compound containing a sulfonic acid ester group that can generate sulfonic acid by photolysis and a polymer containing hydroxystyrene as compounds that meet the above conditions. It has been found that a useful resist can be obtained in combination with a composition of the same type.

A compound containing a sulfonic acid ester group generates sulfonic acid when irradiated with light, and the polymer is converted into a polymer by a crosslinking agent by this acid.

Specific examples of the above-mentioned compound containing a sulfonic acid ester group include the following compound (14) (Is).

The compound containing a sulfonic acid ester group used in the present invention is
The present invention is not limited to the compounds (lO) to (16) given as specific examples above, and analogs and derivatives can also be used.

On the other hand, a system that generates a halogen acid such as hydrochloric acid as a priori generator has been proposed. As a result of performing lithography using these systems, it was not possible to obtain a pattern with the desired shape. This is thought to be due to the fact that the generated acid is a easily diffusible halogen acid such as hydrochloric acid, and therefore the acid diffused into the unexposed areas.

The compound containing a sulfonic acid ester group used in the present invention generates a relatively bulky and difficult-to-diffuse acid such as a benzenesulfonic acid derivative through photolysis, so it is possible to prevent the acid from diffusing into the unexposed area. As a result, a pattern with a desired shape can be obtained without causing any adverse effects.

Examples of the crosslinking agent used in the photoresist composition of the present invention include the following compounds (+7) (18)H3.

As for the above-mentioned crosslinking agents, those commercially available as Cymel 303 (17), Cymel 325 (18), and Cymel 1170 (19) from Mitsui Suiana Mitsuru Co., Ltd. can be used.

The crosslinking agent used in the present invention is the compound (1
It is not limited to 7) to (22), and analogs and derivatives can also be used.

The proportion of hydroxystyrene in the polymer containing hydroxystyrene is preferably 50% or more, and if it is less than 50%, the solubility in a basic aqueous solution is adversely affected. The polymer used in the present invention has a molecular weight of about 300 to about 100,000, preferably about 10
It has a weight average molecular weight ranging from 0.00 to about 20,000.

The photoresist composition of the present invention contains 3-50% by weight crosslinker, 40-90% by weight polymer, and 0.1-10% by weight prior generator.

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 put into practical use in the form of a resist solution). In this case, the composition is generally prepared by dissolving it in an organic solvent in a proportion of 1 to 50% by weight, preferably 5 to 30% by weight. In this case, the solvent to be used is one that uniformly dissolves each component of the photoresist composition of the present invention, and after applying it to the surface of a substrate such as silicon/aluminum, evaporates the organic solvent to form a uniform and smooth coating film. It is preferable to obtain the following.

Specifically, ketone solvents such as methyl ethyl ketone, cyclopentanone, and cyclohexanone, methyl cellosolve,
Examples include cellosolve solvents such as ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ether solvents such as tetrahydrofuran and diethylene glycol dimethyl ether, and ester solvents such as ethylene glycol monoethyl ester and ethylene glycol monomethyl acetate. but not limited to. The above organic solvents may be used alone or in combination of two or more.

In addition to the above-mentioned components, a sensitizer, a dye, an adhesion improver, etc. can be added to the photoresist composition of the present invention, if necessary. The photoresist composition of the present invention can be used to form a leaf pattern using conventional photoresist techniques by adjusting the resist solution as described above. The method for forming this relief pattern will be explained below.

(1) The resist solution prepared as described above is applied to a substrate to form a resist film with a thickness of 1 to 1.5 μm. This application to the substrate can be performed using, for example, a spinner.

(2) The temperature of the substrate is 60 to 120°C, preferably 80 to 9°C.
Dry at 0°C for 20 to 60 minutes. (Pre-bake) (3) This coating film is irradiated with deep ultraviolet rays and excimer laser through a photomask chart.

(4) Heat the exposed substrate at 80-90℃ for 20 minutes to 60℃.
Heat for a minute. (Intermediate bake) (5) A relief pattern is obtained by washing out the unexposed areas with a developer. As a developer, sodium hydroxide,
For example, a weak alkaline aqueous solution of potassium hydroxide, sodium metasilicate, tetramethylammonium hydroxide, etc. having a concentration of 5% by weight or less can be used.

(6) The developed substrate is heated to a temperature of 80 to 130°C, preferably 9°C.
Dry at 0-120°C for 20-60 minutes. (Bost baking) The relief pattern thus formed has a resolution of 1 μm or less and has good heat resistance.

(Examples) 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) Poly(p-hydroxystyrene) (weight average molecular weight = 5
000), 2.0 g of crosslinker, i.e. Cymel 3
A negative photoresist composition of the present invention consisting of 03 and [1.48 g of α-tosyloxydeoxybenzoin] was dissolved in 50ff11 of ethyl cellosolve acetate to prepare a resist solution.

This resist solution was mixed with hexamethylene disilazane (HMD).
S)1. Using a spin coater, 300
Spin coded at 0+pm/60 seconds. This wafer was prebaked in an oven at 80°C for 30 minutes to give 1,0
A coating film of μm was obtained. Next, the above coating film is passed through a chrome mask having a pattern and applied to a contact aligner-PLA.
-521F (manufactured by Canon) and deep ultraviolet light exposure using a CM-250 mirror. After exposure, the exposed areas were crosslinked by heating the wafer in an oven at 100° C. for 30 minutes. After cooling the wafer, it was developed for 1 minute with a 1.5% aqueous solution of tetramethylammonium hydroxide.
The unexposed areas were dissolved to obtain a pattern. 100 more
Bost bake at ℃ for 30 minutes and measure the film thickness to determine the characteristic curve of irradiation dose and residual film rate.
/caf (254 nm) sensitivity (irradiation dose at 50% residual film rate) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C./30 minutes.

(Comparative Example 1) 1.1-bis(p-chlorophenyl) as a priori generator
The same procedure as in Example 1 was carried out except that -2,2,2-)lichloroethane was used.

Although a sensitivity of 9 m j /al (254 nm) was obtained, a fine pattern of 0.75 μm could not be resolved.

(Example 2) The same procedure as in Example 1 was carried out except that β-tosyloxypropiophenone was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A sensitivity of 211 m j /aj (2S4+m) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C. for 730 minutes.

(Example 3) The same procedure as in Example 1 was carried out except that tosyloxybenzoinamide was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A sensitivity of 25 m j /al (254 nm) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C./30 minutes.

(Example 4) The same procedure as in Example 1 was carried out except that acetophenone (θ-tosyloxime) was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A sensitivity of 22 m j /ad (254 nm) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C./30 minutes.

(Example 5) Same as Example 1 except that polyhydroxystyrene (p:m:o=5:2+2) was used instead of poly(p-hydroxystyrene) and Cymel 1170 was used instead of the crosslinking agent Cymel 303. I did the same thing.

A sensitivity of 28 mj/al was obtained. Furthermore, observation of the formed pattern with an electron microscope revealed that it had a good rectangular shape of 0.7
It was found that fine patterns of 5 μm could be resolved. In addition, the heat resistance of this pattern was measured at 220°C/30°C.
No pattern deformation was observed within minutes.

(Example 6) The same procedure as in Example 5 was carried out except that β-tosyloxypropiophenone was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A sensitivity of 23 m j /al (254++ m) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C./30 minutes.

(Example 7) The same procedure as in Example 5 was carried out except that tosyloxybenzoinamide was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A letter that provides a sensitivity of 25 m j /ad (254 nm). As a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C./30 minutes.

(Example 8) The same procedure as in Example 5 was carried out except that acetophenone (0-tosyloxime) was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A sensitivity of 25 m j /ad (254 n+a) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C./30 minutes.

(Example 9) A p-hydroxystyrene-styrene copolymer (p-hydroxystyrene content = 1011io1%) was used instead of poly(p-hydroxystyrene), and N, N''- instead of the crosslinking agent Cymel 1170. The same procedure as in Example 1 was carried out except that methoxymethyluron was used.

A sensitivity of 30 mj/at was obtained. Furthermore, observation of the formed pattern with an electron microscope revealed that it had a good rectangular shape of 0.7
It was found that fine patterns of 5 μm could be resolved. In addition, the heat resistance of this pattern was measured at 220°C/30°C.
No pattern deformation was observed within minutes.

(Example 10) The same procedure as in Example 9 was carried out except that β-tosyloxypropiophenone was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A sensitivity of 20 m j / cd (254 nml) was obtained. Furthermore, when the formed pattern was observed with an electron microscope, it was found that a fine rectangular pattern of 0.75 μm could be resolved with good accuracy. As a result of measuring the heat resistance, no deformation of the pattern was observed at 220° C. for 30 minutes.

(Example 11) The same procedure as in Example 9 was carried out except that tosyloxybenzoinamide was used instead of α-tosyloxydeoxybenzoin as the a priori generator.

A sensitivity of 25 m j /crl (254 am) was obtained. As a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C. for 730 minutes.

(Example 12) The same procedure as in Example 9 was carried out except that acetophenone (θ-tosyloxime) was used instead of α-tosyloxydeoxybenzoin as a priori generating agent.

A sensitivity of 19 m j /al (254 nm) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved. Further, as a result of measuring the heat resistance of this pattern, no deformation of the pattern was observed at 220° C./30 minutes.

(Effects of the Invention) As explained above, the photoresist composition of the present invention has high sensitivity in the exposure range of deep ultraviolet light and wavelengths associated with excimer laser sources. As a result, in lithography using the above-mentioned light beam as a light source, which is necessary for increasing the resolution of resists, it is possible to significantly improve the resolution and contrast.Furthermore, since it can be developed with an alkaline aqueous solution, it does not get used to swelling, and it is possible to produce high-precision microscopic images. It is possible to form a photoresist pattern.

In addition, photoresist patterns have high heat resistance and can be applied to processes that have not been applicable up to now. Therefore, the requirements for sensitivity and resolution of these compositions will become increasingly strict in the future (IC, LS
It can be used as a resist for manufacturing integrated circuits such as I.

Claims (1)

[Claims] 1. A polymer containing the following general formula (1) and ▲ mathematical formulas, chemical formulas, tables, etc. ▼ (1) (In the formula, R1 represents hydrogen or a C1 to C5 alkyl group.) Crosslinking agent containing a group represented by the following general formula (2) ■N-CH
A photoresist composition characterized by adding a photoacid generator containing a sulfonic acid ester group to _2OR2(2) (wherein R2 represents hydrogen, a methyl group, or a C1 to C5 alkyl group) . 2. The photoresist composition according to claim 1, wherein the crosslinking agent containing the group represented by the general formula (2) is a compound represented by the following general formula (3). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(3) (In the formula, R3 is hydrogen, -CH_2OCH_3 or -CH
Represents _2OH. 3. The photoresist composition according to claim 1, wherein the crosslinking agent containing the group represented by the general formula (2) is a compound represented by the following general formula (4). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(4) (In the formula, R4 represents hydrogen or a C1-C5 alkyl group.) 4. The following general crosslinking agents containing the group represented by the above general formula (2) are used. The photoresist composition according to claim 1, which is a compound represented by formula (5). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(5) (In the formula, R5 represents hydrogen or a methyl group, and X represents oxygen, a methylene group, or N-R6. Here, R6 is a C1 to C5 alkyl group. 5. The photoacid generator according to claims 1, 2, 3, and 4, wherein the photoacid generator containing the sulfonic acid ester group is a compound represented by the following general formula (6). Resist composition. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(6) (In the formula, R7 and R10 are aryl groups, R8 and R9
is hydrogen, an aryl group, a C1-C8 alkyl group, or a C1
~ Represents a C8 alkoxyl group. ) 6. The photoresist according to claims 1, 2, 3, and 4, wherein the photoacid generator containing the sulfonic acid ester group is a compound represented by the following general formula (1). Composition. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(7) (In the formula, R11 and R16 represent an aryl group, and R12
, R13, R14 and R15 are hydrogen, aryl group, C1
~Represents a C8 alkyl group or a C1-C8 alkoxyl group. ) 7. The photoresist according to claims 1, 2, 3, and 4, wherein the photoacid generator containing the sulfonic acid ester group is a compound represented by the following general formula (8). Composition. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(8) (In the formula, R17 and R19 represent an aryl group, and R18
represents a C1-C8 alkyl group. 8. The photoresist according to claims 1, 2, 3, and 4, wherein the photoacid generator containing the sulfonic acid ester group is a compound represented by the following general formula (9). Composition. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(9) (In the formula, R20 and R21 are aryl groups or C1 to C8
represents an alkyl group, and R22 represents an aryl group. ) 9. Claims 1, 2, 3, 4, 5, and 6 state that the photoacid generator is present in the composition in an amount of 1 to 30 parts by weight.
, 7, and 8. The photoresist composition according to items 7 and 8.