JPH0769609B2 - Photosensitive resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photosensitive resin composition having high oxygen plasma resistance and capable of reproducing a positive pattern with high accuracy with respect to ultraviolet rays.

[Prior art and its problems]

Conventionally, resist materials for high energy rays have been used for pattern formation in LSI processing processes. Among them, a fluorine-containing methacrylate polymer as a positive resist is known to have high sensitivity (1 × 10 ⁻⁶ C / cm ² ) (Patent No. 1034536). However, this high-sensitivity positive resist has a drawback that plasma processing resistance in LSI processing is low. On the other hand, chloromethylated polystyrene (CMS), which is a negative resist, is known as a resist having high sensitivity and high plasma processing resistance (Patent No. 1107695). However, with this negative resist, the resolution decreases as the film thickness increases, and a fine pattern cannot be formed. Therefore, in order to solve this drawback, there has been proposed a method of forming a fine pattern having a high shape ratio with a large film thickness by forming a resist into a multilayer instead of a single layer. That is, the first
After forming a thin resist material on the second layer, the second resist material is irradiated with high energy, and the organic polymer of the first layer is subjected to oxygen plasma etching (O ₂ RIE) using the pattern obtained after development as a mask. It aims to obtain a pattern with a high shape ratio by anisotropic etching [BJ Lin Solid State Technol. 24, 73 (198
1)]. Since O ₂ RIE resistance must be high in this method, it has been proposed to use Si polymer as the resist material. For example, Hatzakis et al. Performed patterning using a polyvinylmethylsiloxane polymer as a negative resist [M. Hatzakis et al Pro.
c. Int'1.Conf. Microlithography (1981)].

However, this negative resist material has a problem that the glass transition temperature (Tg) is low. This is because when Tg is low, dust easily adheres to the resist, film thickness control is difficult, and developability decreases due to pattern deformation during development.

Thus, as a resist material, Tg is high, and
It is needed having a high O ₂ RIE resistance.

Further, an alkali developing type non-swelling resist is required for forming a high resolution pattern.

[Means for solving problems]

Therefore, in the present invention, the above problems are solved by using a polysiloxane structure to improve the O ₂ RIE resistance, and to use a silicone polymer in which a large number of phenyl groups are introduced into the side chain to increase Tg. I did it.

The present invention relates generally to a photosensitive resin composition and has the following general formula (I): [However, in the general formulas I and II, X is (R represents a hydrocarbon or a substituted hydrocarbon), and is one selected from the group of carboxyl groups, and may be the same or different.

R ', R "and R are phenyl groups.

l, m and n represent 0 or a positive integer, and l and m are never 0 at the same time. ] The resist material represented by the following general formula (III) (Where Z is A group selected from the group consisting of ) Orthonaphthoquinone compound represented by the following general formula (IV) Or a diazomeldrum acid represented by the following general formula (V) An O-nitrobenzyl ester compound represented by the following general formula (VI) (Wherein R represents an alkyl group) and at least one positive photosensitive agent selected from nitrophenyldihydropyridine compounds.

The resist materials represented by the general formulas (I) and (II) have O ₂ RI because the main chain of the polymer is a polysiloxane structure.
It has very high E resistance and is advantageous for forming fine and high aspect ratio patterns. In addition, even though it has a polysiloxane structure, it has many phenyl groups in its side chain, so that it has a Tg of room temperature or higher and can be used as a resist. In addition to the phenyl group Since a hydrophilic group such as a carboxyl group is introduced, the polymer is soluble in an alkaline aqueous solution. Therefore, it has a feature that it can be used as a non-swelling resist capable of being developed with an alkali.

By adding an orthonaphthoquinone compound to this resist, it can be used as a positive photosensitive resin composition.
That is, the Si-containing polymer represented by the general formula (I) or the general formula (II) is added to the general formula (III), (IV),
The photosensitive resin composition to which the positive type photosensitizer represented by (V) and (VI) is added, the positive type photosensitizer in the irradiated portion becomes a corresponding carboxylic acid or alkali-soluble compound by irradiation with ultraviolet rays (UV), and the irradiated portion is Since it is removed by alkali development, it exhibits positive resist characteristics.

In this photosensitive resin composition, the positive-type photosensitizer plays a role of a resist dissolution inhibitor in an alkaline solution. The addition amount of the positive type photosensitizer is usually in the range of 5 to 30% by weight. If it is less than 5% by weight, dissolution of the polymer compound in an alkali developing solution cannot be suppressed and alkali development cannot be carried out. If it exceeds 30% by weight, the Si content as a resist material is lowered and oxygen plasma resistance is reduced. And cause inconvenience. Generally, about 10% by weight is a preferable addition amount.

Examples of the method for producing the siloxane polymer represented by the general formula I of the present invention include cyclic phenyl siloxanes such as hexaphenylcyclotrisiloxane and octaphenylcyclotetrasiloxane, and alkali metal hydroxides such as potassium hydroxide and butyl lithium. There is a method of modifying the obtained polydiphenylsiloxane by ring-opening polymerization with an alkyl compound of an alkali metal such as.

Further, the cyclic phenyl siloxane may be copolymerized with tetramethyltetraphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, or the like, instead of being used alone. Further, particularly when it is desired to form a high-resolution pattern, a monodisperse polymer having a uniform molecular weight is preferable, but cyclosiloxane is obtained by anionic living polymerization with a catalyst such as butyllithium and modifying the obtained polymer. The desired monodisperse polymer can be obtained.

As a method for producing the phenylsilsesquioxane polymer represented by the general formula II of the present invention, There is a method of modifying a phenylsilsesquioxane polymer which is easily obtained by hydrolyzing a silanized product represented by (Z is Cl or OCH ₃ ).

Next, a method for forming a pattern using the photosensitive resin 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 photosensitive resin composition of the present invention is applied thereon to form a two-layer structure. Then, after heat treatment, light irradiation is performed to make only the irradiated portion soluble in the developing solvent, and then the photosensitive resin composition in the irradiated portion is removed by development. Subsequently, using the photosensitive resin composition in the non-irradiated portion as a mask, the organic polymer material in the lower layer is removed by etching by dry etching using oxygen gas to form a pattern. As the organic polymer material, any material may be used as long as it can be etched by oxygen plasma, but an aromatic-containing polymer is preferable in order to enhance resistance when the substrate is dry-etched using this as a mask after pattern formation. .

Production examples are shown below, but the present invention is not limited thereto.

(Production Example 1) 15 g of anhydrous aluminum chloride and 50 ml of acetyl chloride are placed in a 300 ml flask equipped with a stirrer, a thermometer, and a dropping door, and stirred. Next, a solution prepared by dissolving 5 g of polyphenylsilsesquioxane having a molecular weight of 7800 in 50 ml of acetyl chloride was gradually added dropwise. Keep the temperature at 25 ℃ and proceed the reaction. Hydrogen chloride is generated as the reaction progresses. After reacting for 3 hours, the mixture is cooled and the contents are poured into ice water containing hydrochloric acid. Stir well to decompose aluminum chloride, make sure ice water is acidic, and separate precipitated polymer. Rinse well with diluted hydrochloric acid-water. Finally, it is dried in a vacuum dryer. The molecular weight of the obtained polymer was 7,900. 1670 cm in infrared absorption spectrum
Absorption of a carbonyl group was observed at ^-1 , and absorption of a methyl group was observed at δ = 2.4 by NMR, and it was confirmed that acetylation was performed. The acetylation rate at this time was 60% from NMR.

(Production Example 2) 25 ml of stannic chloride and 50 ml of acetic anhydride were placed in a 300 ml flask equipped with a stirrer, a thermometer, and a dropping door, and stirred.
Next, a solution of 6 g of diphenylsilanediol dissolved in 50 ml of acetic anhydride is gradually added dropwise. An acetylated polysiloxane was obtained in the same manner as in Production Example 1 below. The polymer obtained had a molecular weight of 1500 and an acetylation ratio of 42%.

(Production Example 3) 6 g of the acetylated polyphenylsilsesquioxane obtained in Production Example 1 was added to 100 ml of a 10% aqueous solution of sodium hypochlorite, and the mixture was refluxed for 12 hours. Precipitation occurs when the resulting clear liquid is acidified by adding hydrochloric acid. Separated to obtain a yellowish white solid. 1670 cm ^{-1 in} infrared absorption spectrum
It was confirmed that the absorption of the carbonyl group disappeared, and the absorption of the carboxyl group was observed at 1700 cm ^-1, and the carboxylation was carried out. Yield 70% (Production Example 4) 6 g of the acetylated polydiphenylsiloxane obtained in Production Example 2 was added to 100 ml of a 10% aqueous solution of sodium hypochlorite, and the mixture was refluxed for 12 hours. Thereafter, carboxylation was performed in the same manner as in Production Example 3. Yield 65% The carboxylated products obtained in Production Example 3 and Production Example 4 were soluble in an alkaline aqueous solution, methanol and ethanol, but insoluble in other organic solvents.

(Production Example 5) 5 g of the acetylated polyphenylsilsesquioxane obtained in Production Example 1 was dissolved in 100 ml of tetrahydrofuran, and 3 g was added thereto.
LiAlH ₄ was added and the mixture was refluxed for 3 hours. 5% after completion of reaction
It was poured into ice-water containing hydrochloric acid to obtain a yellowish white solid.
Yield 55% 1670 found in the raw material in the infrared absorption spectrum of the product
absorption of the carbonyl group of the cm ^-1 disappears, absorption was observed due to the OH group near 3100~3400cm ^-1, was confirmed to have been reduced.

(Production Example 6) 5 g of acetylated polydiphenylsiloxane obtained in Production Example 2
Was dissolved in 100 ml of tetrahydrofuran, and 3 g of LiAlH was added to it.
₄ was added and refluxed.

After completion of the reaction, it was poured into ice water containing 5% hydrochloric acid to obtain a yellowish white solid. Yield 66% The polymers obtained in Production Examples 5 and 6 were soluble in alkaline aqueous solutions and alcohols such as methanol.

(Production Example 7) 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, acetylated polydiphenylsiloxane Got

(Production Example 8) 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 9) A propionylated polyphenylsiloxane was obtained by the same method as in Production Example 7, except that propionyl chloride was used instead of acetyl chloride.

Examples of the present invention will be shown below.

"Example 1" For the resist materials obtained in Production Examples 1 to 9 A photosensitive resin composition containing 20% by weight of a naphthoquinone compound represented by the formula was applied to a silicon wafer to a thickness of about 0.2 μm, and prepaked at 80 ° C. for 20 minutes. After prepaking, it was irradiated with ultraviolet rays using a jet light manufactured by Oak Co. After irradiation, the ratio of Microposit 2401 (made by Shipley) and water is
It was developed with 1/1 developer respectively, and the irradiation amount at which the residual film in the irradiated portion became 0 was defined as the sensitivity.

For the resolution, the minimum pattern size that can be resolved with a line & space pattern was measured.

Table 1 shows the sensitivity and resolution.

Example 2 A silicon wafer was coated with AZ-1350 resist (manufactured by Shipley) to a thickness of 2 μm, and heated at 200 ° C. for 30 minutes to insolubilize it. The resist material used in Example 1 was applied on the AZ resist in the same manner as in Example 1 to a thickness of about 0.2 μm, and prebaked at 80 ° C. for 20 minutes. 0.5 after prebaking
Ultraviolet irradiation was performed through a chromium mask having a line & space pattern of μm, and development was performed with a developing solution having the same composition as in Example 1. As a result, the mask pattern was transferred to the AZ resist material. After that, the AZ resist was etched with 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 conditions of RF power 0.2 W / cm ² and O ₂ gas pressure of 20 mtorr, the AZ resist in the part not covered by the resist pattern disappeared completely.

With any of the resist materials used in Example 1, a 0.5 μm line & space pattern could be formed with a thickness of about 2 μm.

"Example 3" For the resist materials obtained in Production Examples 1 to 9 The sensitivity and resolution were evaluated in the same manner as in Example 1 for the photosensitive resin containing 20% by weight of the positive photosensitive agent represented by The results are shown in Table 2.

“Example 4” The exposure characteristics of the photosensitive resin compositions used in Examples 1 and 3 to deep ultraviolet rays were evaluated. The evaluation method was the same as in Example 1. However, a mask aligner PLA-521 (manufactured by Canon) was used as an exposure device, and a Xe-Hg lamp and a cold mirror (CM250) were used as a light source.

The evaluation results are shown in Table 3.

Since the exposure wavelength was short, the sensitivity and the resolution were higher than those of Examples 1 and 3.

[Effects of the Invention] As described above, the resist material used in the present invention is an alkali-soluble siloxane polymer, and the photosensitive resin composition of the present invention obtained by adding a positive-type photosensitizer to the resist material is alkali developable. It becomes a non-swelling positive resist. Further, the photosensitive resin composition of the present invention has high oxygen plasma resistance because it contains silicon, and therefore can be used as an upper layer resist of a two-layer resist. Therefore, there is an advantage that a fine pattern of 0.5 μm or less, which cannot be achieved by the conventional resist material, can be formed with a high aspect ratio.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhide Onose, Tokai-mura, Naka-gun, Ibaraki 162, Shirahane, Shirahoji, Nippon Telegraph and Telephone Corporation, Ibaraki Electro-Communications Research Laboratory (56) Reference JP 61-144639 (JP, A) JP 62-159141 (JP, A) JP 62-247350 (JP, A) JP 62-229136 (JP, A)

Claims (2)

[Claims] 1. The following general formula [However, X represents R-C-, R-CH- (R represents a hydrocarbon or a substituted hydrocarbon. ), A kind selected from the group of carboxyl groups, and they may be the same or different. R ′, R ″ and R are phenyl groups. L, m and n are 0 or a positive integer, and l and m cannot be 0 at the same time.] formula (Where Z is A group selected from the group consisting of ) Orthonaphthoquinone compound represented by the following general formula Diazomeldrum acid represented by the following general formula An O-nitrobenzyl ester compound represented by the following general formula A photosensitive resin composition comprising one or more positive-working photosensitizers selected from nitrophenyldihydropyridine compounds represented by the formula (wherein R represents an alkyl group). 2. The following general formula [However, X represents R-C-, R-CH- (R represents a hydrocarbon or a substituted hydrocarbon. ), A kind selected from the group of carboxyl groups, and they may be the same or different. R ′, R ″ and R are phenyl groups. L, m and n are 0 or a positive integer, and l and m cannot be 0 at the same time.] formula (Where Z is One group selected from the group consisting of ) Orthonaphthoquinone compound represented by the following general formula Diazomeldrum acid represented by the following general formula An O-nitrobenzyl ester compound represented by the following general formula A photosensitive resin composition comprising one or more positive-working photosensitizers selected from nitrophenyldihydropyridine compounds represented by the formula (wherein R represents an alkyl group).