JPH0232350A - Photoresist composition and pattern forming method - Google Patents

Abstract

PURPOSE:To obtain patterns having high contrast by using a specific azide compd. as a photosensitive agent, exposing the photosensitive film formed thereof with far UV light and developing the same with an alkaline developing soln. CONSTITUTION:This compsn. is formed of the photosensitive agent expressed by the formula I and an alkali soluble resin and the photosensitive film formed thereof is exposed by using <=313nm far UV light and is developed by the alkaline developing soln. In the formula, A- denotes the formula II or the formula II; R1, R2 denote an alkyl group, alkenyl group, aryl group or aralkyl group; R3, R4 denote an alkyl group, aryl group, aralkyl group, alkoxy group or aryloxyl group; X denotes O or NH. Since this photoresist compsn. has a large difference between the transmittance before exposing and the transmittance after exposing and, therefore, the resist pattern having high resolution is obtd. by exposing the compsn. with the far UV light.

Description

Detailed Description of the Invention <Industrial Utilization Public Funds> The present invention relates to a novel photoresist composition and a pattern forming method using the same.
This is suitable for using far ultraviolet light of wavelengths below m, particularly when using a KrF excimer laser as a light source.

<Prior Art> In recent years, manufacturing technology for semiconductor elements and integrated circuits has made remarkable progress, and as a result, requirements for photolithography technology have become stricter year by year. The resolution R of the resist in the reduction projection exposure method is expressed by Rayleigh's equation R= as λ/NA, and methods for improving the resolution include increasing the numerical aperture of the lens expressed by NA, and changing the exposure light. Wavelength (λ)
There are three methods: shortening the wavelength of k, and decreasing k determined by the resist process. In the past, improvement in resolution was mainly due to increasing the NA of the stepper and improving the resist process. However, increasing the NA of the stepper causes a problem in that the depth of focus (DOF) expressed by the following equation, λ DOF=±−−m−T 2 (NA), becomes shallower.

On the other hand, shortening the wavelength λ has less influence on the depth of focus than NA, and in recent years, the light source has been changed from the G-line (436 nm) of the conventional high-pressure mercury lamp to the excimer laser, which has a shorter wavelength. In particular, development of a stepper device using KrF excimer laser light (248 nm) is progressing.

By the way, the conventional gill (436nm), i@
A photoresist made of an alkali-soluble novolak resin and naphthoquinonediazide sulfonic acid ester is used in the stepper that uses (365 nm) as a light source. These photoresists have the property that a high-resolution pattern can be obtained because they become transparent in the exposure light when exposed to glL is. Therefore, as mentioned above, these photoresists are also used in the recently developed excimer laser stepper device.

<Problems to be Solved by the Invention> However, the photoresist made of the above-mentioned alkali-soluble novolac resin and naphthoquinonediazide sulfonic acid ester has too high an absorption rate for far ultraviolet rays under 313 nm AL. The problem arises that the light does not reach the target and gives an overcut profile. Furthermore, when these photoresists are exposed to deep ultraviolet light, the photoresist has a problem in that the photodecomposition products of the photosensitizer absorb the exposure light, resulting in no improvement in transmittance.

Diazomeldrum acid derivatives have been reported as photosensitizers that solve these problems (IEEE Tra
ns, Electron Devices,
ED-28, 1300, 1981).

However, although these photosensitizers become transparent upon exposure, they have the disadvantage that they sublimate during prebaking of the resist. Diazobiperidine thione derivatives (Proe) are also used as photosensitizers for deep ultraviolet light.

of 5PIE Vol, 771.2.1987)
2-diazo-cyclohexane-1,3-dione derivatives (JP-A-61-240237) or α-phosphoryl-substituted diazocarbonyl compounds (JP-A-61-240237)
23837) and the like have been reported, but all of them have the drawback that the difference in transmittance before and after exposure at 248 nm is small.

The present invention overcomes the above-mentioned problems, can be developed with alkali, has a large difference in transmittance before and after exposure to deep ultraviolet light, especially KrF excimer laser light, and can obtain a pattern with high contrast. The purpose of this invention is to provide a photoresist composition having excellent properties such as, and a pattern forming method using the same.

Means for Solving the Problems The present inventors have conducted extensive research to develop a photoresist composition and pattern forming method having the above-mentioned excellent properties, and as a result, have developed a photoresist comprising a photosensitizer and an alkali-soluble resin. In the composition, a specific azide compound is used as the photosensitizer, and the photosensitive film of the photoresist composition is exposed to deep ultraviolet light of 313 nm or less and developed with an alkaline developer. I discovered that.

The photoresist composition according to the present invention based on this knowledge represents the following general formula (1), where R1 and R2 represent an alkyl group, an alkenyl group, an aryl group, or an aralkyl group, and R, and R4 represent an alkyl group or an aryl group. group, aralkyl group, alkoxyl group or aryloxyl group, and X represents O or NH.

It is characterized by consisting of a photosensitizer represented by: and an alkali-soluble resin.

In addition, a pattern forming method using such a photoresist involves exposing a photosensitive film made of a photosensitive agent represented by the above general formula (1) and an alkali-soluble resin to deep ultraviolet light of 313 nm or less, and then exposing the photosensitive film to deep ultraviolet light of 313 nm or less, and then exposing it to an alkaline developer using an alkaline developer. It is characterized by being developed.

The present invention will now be described in detail.

The compound represented by the above general formula (1) is used as the photosensitizer in the photoresist composition of the present invention, and more specific examples of the substituents in this general formula (1) include R,...
R2 is an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, hexyl group, or cyclohexyl group, a substituted or unsubstituted aryl group such as a phenyl group, tolyl group, or naphthyl group, or an aralkyl group such as a benzyl group. , an allyl group, a propenyl group, an alkenyl group such as a butenyl group, and R3 and R4 are a methyl group and an ethyl group.

Alkyl groups such as butyl group and cyclohexyl group; methoxyl group and ethoxyl group; alkoxyl groups such as butoxyl group; phenyl group t Substituted or unsubstituted aryl groups such as tolyl group and naphthyl group; and aryloxyl groups such as phenoxyl group. I can do it.

The compound represented by the general formula (1) is island et Her, 1
02.2216 (1989) and Che+a, Ber
, 103.1477 (1970).

The photosensitizer represented by the general formula (1) is a diazopiperidinedione derivative disclosed in the above-mentioned patent or literature;
Far compared to -diazo-cyclohexane-1,3-dione derivatives or a-phosphoryl-substituted diazocarbonyl compounds! Ratio ε of absorbance before and after exposure at external light, particularly at 248 nm, which is the wavelength of light from a KrF excimer laser. /ε is very large.

Therefore, when the present photoresist containing these brightening agents is used and exposed using KrF excimer laser light,
When exposed to light, the resist layer becomes transparent, allowing light to reach the bottom of the resist film, resulting in a resist layer (turn) with a good profile.

Examples of the alkali-soluble resin in the resist composition of the present invention include novolak resin, poly(hydroxystyrene)
, an alkali-soluble copolymer with an imide structure, etc. Examples of novolac resins include phenol, O-cresol, m-cresol, p-cresol, and 2,3-xylenol.

2,5-xylenol, 3p4-xylenol, 3,5
Examples include condensates of phenols such as -xylenol, α-naphthol, or β-naphthol and aldehydes such as formaldehyde, acetaldehyde, and benzaldehyde. Examples of poly(hydroxystyrene) include poly(O-hydroxystyrene) and poly(m-hydroxystyrene).

Poly(p-hydroxystyrene), poly(α-methyl-〇-hydroxystyrene), poly(α-methyl-m-
hydroxystyrene).

Examples include poly(a-methyl-m-7-droxystyrene), partially acetylated products and silylated products thereof. The alkali-soluble copolymer having an imide structure is a copolymer having a repeating unit having a structure represented by the following general formula (2).

However, in the formula, R6 represents hydrogen, an alkyl group or an aryl group, R6 and R7 represent hydrogen, 0H2COOH, 30, H or 0COR, (R, is an alkyl group), and n represents an integer of 0 to 6.

These basic combinations are disclosed in JP-A-61-162039, JP-A-62-151408, and JP-A-62-15.
It can be manufactured by a known method as disclosed in Japanese Patent No. 1409 and the like.

The photoresist composition of the present invention is preferably used in the form of a solution by dissolving the photosensitizer represented by the general formula (1) and the alkali-soluble resin in a suitable solvent. Examples of such solvents include ethers such as dioxane, jetoxyethane, diethylene glycol dimethyl ether, methyl cellosolve, ethyl cellosolve, ethylene glycol monoisopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetone, methyl ethyl ketone.

Methyl isobutyl ketone, cyclopentanone.

Ketones such as cyclohexanone, ethyl acetate, butyl acetate, methyl cellosolve acetate (ethyl cellosolve acetate), acids 11! Propylene glycol monomethyl ether, propylene glycol monoethyl ether acetate.

Examples include esters such as dimethyl oxalate, amides such as pNpN-dimethylformamide and N,N-dimethylacetamide, pyrrolidones such as N-methylpyrrolidone, lactones such as γ-butyrolactone, and sulfoxides such as dimethylsulfoxide. be able to. These solvents may be used alone, or
Al or more may be used in combination.

There is no particular restriction on the blending ratio of the photosensitizer and the alkali-soluble resin in the photoresist composition of the present invention, but usually, per 100 parts by weight of the alkali-soluble resin,
The photosensitive component is blended in an amount of 1 to 100 parts by weight, preferably 5 to 50 parts by weight.

The photoresist composition of the present invention may contain additive components used in ordinary photoresists, such as surfactants, dyes, stabilizers, and sensitizers, as required.

The photoresist composition of the present invention can be applied to a substrate to form a film, and then used in a method of forming a pattern using deep ultraviolet light, particularly 248 nm light oscillated by a KrF excimer laser. It is valid.

Next, an example of the pattern forming method of the present invention will be described. First, a solution of the photoresist composition of the present invention dissolved in a solvent is applied onto a substrate such as a semiconductor wafer using, for example, a spinner.
Dry to form a photosensitive film. The drying conditions at this time are determined in consideration of the thermal stability of the photosensitizer used, the boiling point of the solvent, etc. The thickness of the photoresist film to be formed is not particularly limited;
If the number of people is less than 0.00, pinholes are likely to occur, and the diameter of 5 μm
If it becomes thicker, the image becomes out of focus in a reduction projection exposure apparatus, so it is usually 50 to 5 μm, more preferably 1000 to 3 μm.

In the method of the present invention, after forming the above photoresist film, pattern exposure is carried out by irradiating it with deep ultraviolet light of 313 nm or less, particularly preferably KrF excimer laser light, through a predetermined pattern.

After that, the resist layer is dissolved in an inorganic alkali such as sodium hydroxide or potassium hydroxide! A desired fine pattern can be obtained by developing with an alkaline developer such as an aqueous solution of an organic alkali such as tetramethylammonium water or choline.

Kusou example Next, the present invention will be explained in more detail by giving specific examples.

Synthesis Example (Diphenylphosphinyldiethylcarbamoyldiazomethane) In a nitrogen atmosphere, 15.0 g of ethyl diphenylphosphine oxide was added dropwise to 24.3 g of refluxed N,N-diethylacetamide over about 1 hour. 30 more after dropping
The mixture was refluxed.

After cooling, n-hexane was added to the reaction mixture to precipitate crystals. The precipitated crystals were filtered and dried to obtain diphenylphosphinyldiethylcarbamoylmethane. 15.82 g of the obtained diphenylphosphinyldiethylcarbamoylmethane and potassium t-butoxide were mixed in 125 g of a 4:1 mixed solvent of benzene and tetrahydrofuran.
ml and heated under reflux for 10 minutes in a nitrogen atmosphere. After cooling the mixture to 0° C., a solution of 9.86 g of I)-) luenesulfonyl azide in 125 mj of benzene was added. 1 hour at the same temperature and 15 hours at room temperature.
After stirring for an hour, 150 mj of water was added. After extraction with benzene, the benzene layer was washed with alkali. When the benzene was distilled off and the mixture was concentrated, crystals were precipitated. The precipitated crystals were filtered and further recrystallized from isopropyl ether to obtain the following diphenylphosphyl diethylcarbamoyldiazomethane (sensitizer 1).

Photosensitizer 1 Photosensitizer 3 mp, 110℃ H’-NMR.

0.92 ppm (Mie fi, 6H) 3,27 ppm (VEWa, 4H) 7,2
5 to 7.97 ppm (multiple line, 10H) In the same manner, the following photosensitizers 2 and 3.4 were produced.

Photosensitizer 2 mp, 106°C mp, 64°C Photosensitizer 4 mp, 90°C Examples 1 to 4 1 part by weight each of the above-mentioned photosensitizers 1 to 4 and 10 parts by weight of the alkali-soluble resin shown in Table 1 were mixed into methyl cellosolve acetate. A photoresist composition was prepared. These photoresist compositions were applied onto a quartz plate using a spinner and heated at 85°C.
was dried for 30 minutes to form a film. This film was exposed to light using a low-pressure mercury lamp, and the transmittance at 248 nm before and after exposure was measured. The results are also shown in Table 1.

For comparison, 2,3,4-)lihydotetraxybenzophenone, which is a photosensitizer for photoresists currently used, and 1
, 2-naphthoquinone diazide-5-sulfonic acid, and a photosensitive film using the ester as reference example 1, JP-A-61-2
Reference Example 2 A photoresist film was prepared using diphenylphosphinylbenzoyldiazomethane disclosed in No. 23837 as a photosensitizer.
The transmittance before and after exposure at 248 nm was similarly measured.

These results are also shown in Table-1.

From the results shown in Table 1, it can be seen that the photoresist compositions of Examples 1 to 4 have a larger difference in transmittance ('r, x, -'ro) before and after exposure compared to Reference Examples 1 and 2. .

Example 5 The photoresist of Example 1 was applied onto a silicone unibar and dried at 85° C. for 30 minutes to form a photoresist film with a thickness of 1.0 μm. After pattern exposure using a KrF excimer laser stepper with a numerical aperture of 0.37 and irradiation with 160 mj of light, the pattern was developed with 0.18 ON tetramethylammonium water i volume W, resulting in a 0.3 μ line and space pattern. I was able to resolve it clearly.

<Effects of the Invention> The photoresist composition of the present invention is suitable for use in the far ultraviolet region, especially KrF.
Since there is a large difference in the transmittance of excimer laser light before and after exposure at 248 nm, it is possible to obtain a high-resolution resist pattern by making a photosensitive film using such a photoresist composition and exposing it to deep ultraviolet light. Be able to do that. Therefore, the present invention is particularly suitable for manufacturing highly integrated semiconductor devices.

Claims (5)

[Claims] (1) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ However, in the formula, A- is ▲ 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, alkenyl groups,
It represents an aryl group or an aralkyl group, R_3 and R_4 represent an alkyl group, an aryl group, an aralkyl group, an alkoxyl group, or an aryloxyl group, and X represents O or NH. A photoresist composition comprising a photosensitizer represented by: and an alkali-soluble resin. (2) The photoresist composition according to claim 1, wherein the alkali-soluble resin is a novolac resin. (3) The photoresist composition according to claim 1, wherein the alkali-soluble resin is poly(hydroxystyrene). (4) Alkali-soluble resin has the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ However, in the formula, R_5 represents hydrogen, an alkyl group, or an aryl group, and R_6 and R_7 are hydrogen, OH, COOH, SO_
3H or OCOR_9 (R_9 is an alkyl group),
n represents an integer of 0 to 6. The photoresist composition according to claim 1, which is a copolymer having a repeating unit having a structure represented by: (5) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ However, in the formula, A- is ▲ 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, alkenyl groups,
It represents an aryl group or an aralkyl group, R_3 and R_4 represent an alkyl group, an aryl group, an aralkyl group, an alkoxyl group, or an aryloxyl group, and X represents O or NH. A pattern forming method comprising exposing a photosensitive film made of a photosensitizer represented by the above formula and an alkali-soluble resin to deep ultraviolet light of 313 nm or less, and developing the film with an alkaline developer.