JPH01222254A - Photoresist composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which has a high accuracy and reproducibility and a high oxygen plasma durability by incorporating a photosensitive siloxane polymer obtd. by condensing a quinone diazide compd. with a hydroxyl group contd. in a specified alkali soluble siloxane polymer, in the composition. CONSTITUTION:The photosensitive siloxane polymer obtd. by condensing the quinone diazide compd. with the hydroxyl group contd. in the alkali soluble siloxane polymer contg. at least one of repeating units shows by formulas I and II, is incorporated in the photoresist composition. In formulas I and II, X is a group shown by formula III or IV, etc., R1-R5 are each hydrogen atom. or optionally substd. alkyl group, etc., (l), (m), (n) and (p) are each 0 or a positive integer. And, in formulas III and IV, R is a hydrocarbon group or a substd. hydrocarbon group. And, as the siloxane polymer contg. formulas I and/or II, has a polysiloxane structure as the main chain of a polymer, a fine pattern which has a very high durability against an oxygen plasma radiation reactive etching (RIE) and a high aspect ratio is formed advantageously. Thus, the composition can be formed as a positive type photoresist which has a high sensitivity against UV rays.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to photoresist compositions with high oxygen plasma resistance that can be reproduced with high precision.

[Prior art and its problems]

Conventionally, resist materials for high-energy radiation have been used for pattern formation in LSI processing processes. Among these, fluorine-containing methacrylate polymers are known to have high sensitivity (1×10 −5 C/cn) as positive resists (Japanese Patent No. 1034536). However, this highly sensitive positive resist has a drawback in that it has low resistance to plasma processing in LSI processing. On the other hand, chloromethylated polystyrene (CMS), which is a negative resist, is known as a resist with high sensitivity and high plasma processing resistance (Patent No. 1107695).
. However, with this negative resist, the resolution decreases as the film thickness increases, making it impossible to form fine patterns. Therefore, in order to solve this drawback, by using multiple layers of resist instead of one layer, the film thickness can be increased.
Moreover, methods have been proposed for forming fine patterns with high shape ratios. That is, after forming a thin film of resist material as the first layer, high energy is irradiated to this second layer resist material, and the organic polymer of the first layer is subjected to oxygen plasma etching (02) using the pattern obtained after development as a mask.
This method attempts to obtain a pattern with a high shape ratio by anisotropic etching using RIE (B.

J, Lin, 5olid 5tate Technol
, 24.73 (1981)).

Since this method requires high 0□RIB resistance, it has been proposed to use S1 polymer as the resist material. For example, Hatzakis et al. used polyvinylmethylsiloxane polymer as a negative resist to form patterns [! J.Hatz
akis et al., Proc. Int. I. Con.
foMicrol-ithography (1981)
).

However, this negative resist material has a glass transition temperature (
There is a problem that Tg) is low. This is because when the Tg is low, problems occur such as dust tends to adhere to the resist, difficulty in controlling film thickness, and deterioration of developability due to pattern deformation during development.

In this way, the resist material has a high Tg and 0. A material with high RIε resistance is required.

Furthermore, in order to form a high-resolution pattern, an alkaline development type non-swelling resist is required.

[Means for solving problems]

Therefore, in this invention, the above-mentioned problems are solved by adopting a polysiloxane structure to increase the resistance to 02RIε, and by using a silicone polymer which has a high Tg by introducing a large number of phenyl groups into the side chain. did.

The present invention represents the following general formula [■] and Cl1l or a substituted hydrocarbon. ), is a type selected from the group of carboxyl groups, and may be the same or different <, R,, R2, R
3, R4 and R3 are the same or different and represent a type of group selected from the group consisting of hydrogen, substituted or unsubstituted alkyl substituted or unsubstituted phenyl group, hydroxyl group and trialkylsiloxy group, p, m, n and p represents O or a positive integer, but is never 0 at the same time, and when β=m20, the groups represented by L, R3, R4, and R6 are hydroxyl groups, and R2+R3
, R4 and R1 are phenyl groups, and includes a photosensitive siloxane polymer in which a quinonediazide compound is condensed with the hydroxyl group of an alkali-soluble siloxane polymer containing in the molecule at least one of the units represented by R4 and R1. This is a photoresist composition characterized by the following.

Hereinafter, the photoresist composition of the present invention will be explained in detail.

Since the photosensitive polysiloxane in the present invention described above acts as a binder itself, the photoresist composition of the present invention may contain the above photosensitive polysiloxane alone, or may contain other photosensitive components as necessary. and/or may contain a binder.

In addition, in the above [■] and (Il) formulas, examples of substituted alkyl groups represented by R3-R6 include phenylalkyl groups, and examples of substituted phenyl groups include alkylphenyl groups, alkoxyphenyl groups, etc. do.

Furthermore, examples of the hydrocarbon group represented by R in X include alkyl groups (methyl, ethyl, propyl, isopropyl, etc.) and aralkyl groups (benzinopephenethyl, etc.)
can be given.

The photosensitive polysiloxane of the present invention has general formulas CI] and [
■) A siloxane polymer having at least one unit represented by
can be easily synthesized by condensation).

Siloxane polymers containing units of the above general formulas [I] and/or [II] have a polysiloxane structure as the main chain of the polymer, and therefore have very high O It's advantageous. Furthermore, despite having a polysiloxane structure, there are many phenyl groups in the side chains, so the Tg is higher than room temperature and it can be used as a resist.

The photosensitive siloxane polymer of the present invention into which a quinonediazide group has been introduced is insoluble in an aqueous alkali solution, but when irradiated with ultraviolet light, the corresponding quinonediazide group is converted to indenecarboxylic acid, so that it becomes soluble in an aqueous alkali solution. That is, since the irradiated area is removed by alkaline development, it exhibits positive resist characteristics.

As a method for producing a siloxane polymer containing units represented by the general formula I used in the present invention, cyclic phenylsiloxanes such as hexaphenylcyclotrisiloxane and octaphenylcyclotetrasiloxane are combined with alkali metal hydroxides such as potassium hydroxide or butyl hydroxides. There is a method of carrying out ring-opening polymerization with an alkylated product of an alkali metal such as lithium, and modifying the obtained polydiphenylsiloxane.

Alternatively, instead of using cyclic phenylsiloxane alone, it may be copolymerized with tetramethyltetraphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, or the like. In addition, especially when it is desired to form a pattern with high resolution, a monodisperse polymer with a uniform molecular weight is preferable, but cyclosiloxane can be subjected to anionic living polymerization with a catalyst such as butyllithium, and the resulting polymer can be modified. A desired monodisperse polymer can be obtained by this method.

Units represented by general formula ■ or general formula [■] used in the present invention
A method for producing a quioxane polymer containing both units represented by and (In) includes a method of modifying a phenylsilsesquioxane polymer easily obtained by hydrolyzing a ran compound.

The quinonediazide compound to be condensed with the siloxane polymer used in the present invention includes 1,2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-5-sulfonyl chloride, or 1,2-benzoquinonediazide-4-sulfonyl chloride. Can be mentioned.

Examples of organic solvents used in the production and condensation reaction of the siloxane polymer include cellosolve acetate, diethylene, glycol monoether, diethylene glycol diether, methylpropylene glycol, methylpropylene glycol acetate, methyl isobutyl ketone, and ethyl acetate lactate. Examples include butyl, isoamyl acetate, propylene carbonate, T-butyrolactone, N-methylpyrrolidone, etc., and they can be used alone or in combination of two or more.

Furthermore, a sensitizer, a storage stabilizer, a dye, a surfactant, etc. can be added to the photoresist composition of the present invention, if necessary.

Next, a method of forming a pattern using the photoresist composition of the present invention will be described.

First, a film of an organic polymer material is formed on a substrate such as silicon, and the photoresist composition of the present invention is applied thereon to form a two-layer structure. Then, after heat treatment, the photoresist composition is irradiated with light to make only the irradiated area soluble in a developing solvent, and then the photoresist composition in the irradiated area is removed by development. Next, using the non-irradiated portions of the photoresist composition as a mask, the underlying organic polymer material is removed by dry etching using oxygen gas to form a pattern. The above-mentioned organic polymer material may be any material as long as it can be etched by oxygen plasma, but aromatic-containing polymers are preferred in order to increase resistance when dry etching the substrate using this as a mask after pattern formation. .

〔Example〕

Examples of the present invention will be shown below along with production examples of the siloxane polymer and photosensitive siloxane polymer used in the present invention, but the present invention is not limited thereto.

(Production Example 1) In a 30011 flask equipped with a stirrer, a thermometer, and a dropping funnel, 15 g of anhydrous aluminum chloride 1 5 g of acetyl chloride
Take 011 and stir. Next, a solution of 5 g of polyphenylsilsesquioxane having a molecular weight of 7800 dissolved in 5011 acetyl chloride is gradually added dropwise. The reaction is allowed to proceed while maintaining the temperature at 25°C. Hydrogen chloride is generated as the reaction progresses.

After reacting for 3 hours, the mixture was cooled and the contents were poured into ice water containing hydrochloric acid. Stir well to decompose the aluminum chloride, make sure the ice water is acidic, and filter out the precipitated polymer. Wash thoroughly with dilute hydrochloric acid and water, and finally dry in a vacuum dryer. The molecular weight of the obtained polymer was 7,900. The infrared absorption spectrum showed a carbonyl group absorption at 1670 cm-', and the NMR showed a methyl group absorption at δ=2.4, confirming that it was an acetyl compound.

The acetylation rate at this time was 60% based on NMR.

(Production Example 2) In a 300+1 flask equipped with a stirrer, thermometer, and dropping funnel, add 2511 stannic chloride and 5Qm ji of acetic anhydride.
! Take and stir. Next, diphenylsilanediol 6
A solution of g dissolved in acetic anhydride 5011 is gradually added dropwise. Acetylated polysiloxane was obtained in the same manner as in Production Example 1. The molecular weight of the obtained polymer was 1500,
The acetylation rate was 42%.

(Production Example 3) 5 g of acetylated polyphenylsilsesquioxane obtained in Production Example 1 was dissolved in tetrahydrofuran 100+1, and 3 g of LIAI84 was added thereto, followed by refluxing for 3 hours.

After the reaction was completed, the mixture was poured into ice water containing 5% hydrochloric acid to obtain a yellowish white solid. In the infrared absorption spectrum of the product with a yield of 55%, the carbonyl absorption at 1670 cm that was observed in the raw material disappeared, and absorption due to OH groups was observed around 3100 to 3400 cm, confirming that it had been reduced. .

(Production Example 4) Acetylated polydiphenylsiloxane 5 obtained in Production Example 2
Dissolve g in tetrahydrofuran 10011, add 3
g of LiAIHl was added and refluxed. 5% after reaction completion
The mixture was poured into ice water containing hydrochloric acid to obtain a yellowish white solid.

Yield: 66% The polymers obtained in Production Examples 3 and 4 were soluble in alkaline aqueous solutions and alcohols such as methanol.

(Production Example 5) Acetylated polydiphenylsiloxane was obtained in the same manner as in Production Example 1, using polydiphenylsiloxane (molecular weight 10,000) obtained by ring-opening polymerization of cyclic siloxane instead of polyphenylsilsesquioxane. Ta.

(Production Example 6) A propionylated polyphenylsilsesquioxane was obtained by the same method as in Production Example 1 except that propionyl chloride was used instead of acetyl chloride.

(Production Example 7) A propionylated polyphenylsiloxane was obtained by the same method as in Production Example 5, using propionyl chloride instead of acetyl chloride.

(Production Example 8) Acetylated siloxane polymer obtained in Production Example 1 4.
4 g and 10.8 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride were dissolved in 90 g of dioxane,
While stirring, 40 g of a 10% aqueous solution of sodium carbonate is gradually added at 40°C.

After stirring it for about 2 hours, a sticky oil precipitates out. The supernatant of this solution is removed by decanting, about 10 times the amount of water is added, and the mixture is vigorously stirred to turn the oil into a powder. It was separated into three parts, and the resulting precipitate was thoroughly washed with methanol and vacuum dried to obtain the desired resist material.

(Production Examples 9 to 14) In Production Example 8, instead of the polymer obtained in Production Example 1, the polymers obtained in Production Examples 2 to 9 were used to produce a condensate of a quinonediazide compound of a siloxane polymer in the same manner. Obtained.

[Example] (Example 1) The photosensitive siloxane polymer obtained in Production Examples 8 to 14 was applied to a silicon wafer 1 to a thickness of about 0.2 μm, and heated at 80°C.
Prebaked for 20 minutes. After pre-beta, it was exposed to ultraviolet light using a mask aligner (PLA-501F) manufactured by Canon. After exposure, development was performed with a developer (a 1.5% by weight aqueous solution of tetramethylammonium and droxide), and the irradiation amount at which no residual film remained in the irradiated area was defined as the sensitivity.

Table 1 shows the sensitivity and resolution. Resolution was evaluated by forming line and space patterns, and each material was 0.5 μm.
A wide pattern was formed.

(Example 2) HPR-206 resist (manufactured by Hunt) was coated on a silicon wafer to a thickness of 2 μm, and heated at 200° C. for 30 minutes to make it insolubilized. The resist material used in Example 1 was applied on top of this HPR resist by approximately 0.2 μm in the same manner as in Example 1.
It was coated to a thickness of m and prebaked at 80° C. for 20 minutes.

After prebaking, ultraviolet irradiation and development were performed in the same manner as in Example 1, and the mask pattern was transferred onto the IPR resist. Thereafter, the HPR resist was etched using a parallel plate type sputter etching apparatus using oxygen gas as an etchant gas and the resist pattern as a mask.

By etching for 15 minutes under the conditions of RF power of 0.2 W/cd, O, and gas pressure of 20 mTorr, the HPR resist in the portions not covered by the resist pattern completely disappeared.

0.5 μm for any resist material used in Example 1
A line and space pattern with a thickness of about 2 μm could be formed.

〔Effect of the invention〕

As explained above, the photoresist composition of the present invention, which is made of a photosensitive siloxane polymer obtained by condensing a quinonediazide compound with an alkali-soluble siloxane polymer, becomes a positive photoresist that is highly sensitive to ultraviolet light. Also, because it contains silicon, it has high oxygen plasma resistance.
It can be used as an upper layer resist of a two-layer resist.

Therefore, since it can be developed with alkali and can be used in a two-layer resist, it has the advantage of being able to form fine patterns of 0.5 μm or less with a high aspect ratio, which could not be achieved with conventional resist materials.

Claims (1)

[Claims] (1) The following general formulas [I] and [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [ I ] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] (However, X is ▲ Mathematical formulas, chemical formulas, tables, etc. There are ▼, ▲Mathematical formulas, chemical formulas, tables, etc.▼ (R represents a hydrocarbon or substituted hydrocarbon), is a type selected from the group of carboxyl groups, and may be the same or different, R_1, R_
2, R_3, R_4 and R_5 are the same or different and represent a type of group selected from the group consisting of hydrogen, substituted or unsubstituted alkyl group, substituted or unsubstituted phenyl group, hydroxyl group and trialkylsiloxy group, , m, n
and p indicate 0 or a positive integer, but they are never 0 at the same time, and when l=m=0, R_2, R_3,
An alkali-soluble siloxane containing in its molecule at least one of the following units: at least one of R_4 and R_5 is a hydroxyl group, and at least one of R_2, R_3, R_4, and R_5 is a phenyl group A photoresist composition comprising a photosensitive siloxane polymer in which a quinonediazide compound is condensed to the hydroxyl groups of the polymer.