JPH0812421B2 - Positive photoresist composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention generally relates to a broad-ray sensitive positive photoresist composition, and more particularly comprises an alkali-soluble resin and a 1,2-naphthoquinonediazide group. The present invention relates to an improvement in a positive photoresist composition containing a compound.

(Prior Art) High integration of integrated circuits has been accelerating year by year, and now it is the era of so-called VLSI with an integration of 100,000 or more.
We are in the era of m-rule and submicron rule design. As a result, the demand for photolithographic technology has become stricter year by year. Most of the resists conventionally used in the photolithography technique are negative resists obtained by adding a bisazide compound as a photocrosslinking agent to cyclized polyisoprene rubber. However, this type of resist has a limited resolution due to swelling during development, and it is difficult to obtain a resolution of 3 μm or more.

A positive photoresist can meet the above demands. The positive photoresist composition contains both an alkali-soluble resin and a photosensitive material, generally a compound containing a substituted naphthoquinonediazide group. When irradiated, naphthoquinonediazide absorbs ultraviolet rays as shown in the following formula, forms ketene through carbene, reacts with water present in the system to form indenecarboxylic acid, and this is dissolved in alkaline water of a developing solution. are doing.

As described above, since the positive type photoresist uses the alkaline aqueous solution as the developing solution, the resist does not swell unlike the case of the negative type, and accordingly, the resolution can be enhanced.

As described above, the positive type photoresist has generally appeared as a resist characterized by non-swelling and high resolution as compared with the negative type resist, and has been widely used in the production of VLSI.

(Problems to be Solved by the Invention) However, in the case of the positive photoresist having such a high resolution, however, when patterning is performed on a substrate having a high reflectance, the image is blurred due to the influence of reflected light from the substrate ( ), And it became clear that control of the line width would be extremely difficult. This phenomenon becomes more remarkable when there is a step on the substrate, and the emergence of a resist that overcomes this problem has been desired.

In order to solve such a problem, it is known to add a light absorbing material, and it is disclosed in, for example, Japanese Patent Publication No. 51-37562. However, it is very difficult to select an absorptive material that affects the other performances of the resist only to the extent that it does not interfere with the performance of the resist. For example, when a light-absorbing material with strong lipophilicity is added, it dissolves easily in the resist solution, but when it is actually used, the lipophilicity of the entire resist film increases, and the developer for a positive resist is usually an alkaline aqueous solution. Solubility in water decreases, and as a result, sensitivity decreases, which causes scum. Moreover, because of the light absorption property, the light use efficiency of the photosensitizer is lowered, and the sensitivity is also lowered from that point, and the sensitivity is markedly lowered as a whole. However, the solubility of the hydrophilic light-absorbing material in the resist solution is low, and it is difficult to obtain sufficient light absorption. The inventors of the present invention have paid particular attention to this point, and as a result, they have been able to dissolve a sufficient amount to prevent the influence of reflection from the substrate by selecting an absorptive material having a specific structure, and to further improve the sensitivity. The present invention has been accomplished by finding that it is possible to keep the decrease in the range within a practically acceptable range.

(Means for Solving Problems) That is, the gist of the present invention is to provide an alkali-soluble resin and
A positive photoresist composition comprising a compound containing a 1,2-naphthoquinonediazide group, wherein the positive photoresist composition comprises 0.1 to 10 wt% of the total solid content of the light-absorbing material represented by the following structural formula. It exists in things.

(In the formula, R ¹ represents a C _{1 to} C ₆ alkyl group, R ² represents an optionally substituted alkyl group, an optionally substituted aryl group, and a — (CH ₂ ) CO ₂ R ³ group (R ³ represents a C ₁ -C ₆ alkyl group), Ar represents an optionally substituted aryl group.) Examples of these substituents include an alkyl group, an aryl group, a halogen atom, an alkyloxycarbonyl group and an aryl group. Examples thereof include an oxycarbonyl group, an alkylaminocarbonyl group, an arylaminocarbonyl group, an arylsulfoxy group and a nitro group.

In the following description of the present invention, the presence of a 3-cyano-6-hydroxy-2-pyridone ring and an azo group is particularly important in the present invention, and the portion of the pyridone ring has an appropriate hydrophilicity, The solubility of the resist is kept in good balance with the lipophilic properties of other parts, and the significant decrease in sensitivity is prevented. The azo group is important as a chromophore. Examples of the light-absorbing material of the present invention include, but are not limited to, the following.

Compound I Compound II Such an absorptive material can be easily synthesized by a known method, for example, according to the following reaction formula, but the method is not necessarily limited to this method.

In the formula, R ¹ , R ² and Ar represent the same groups as those described in the claims, and X and Y represent C _{1 to} C ₄ alkyl groups, which may be the same or different.

The amount of this light-absorbing material added is 0.1 to 1 based on the total solid content.
It is 0 wt%, preferably 0.5 to 8 wt%. If the amount added is less than this, the antihalation effect is not sufficient, and if it exceeds this amount, precipitation or the like is caused and the sensitivity is markedly lowered, which is not preferable.

Alkali-soluble resins include phenol, cresol, ethylphenol, t-butylphenol, xylenol,
So-called novolak resins obtained by condensation polymerization of hydroxy aromatic compounds such as naphthol, 1,4-dihydroxybenzene and 1,3-dihydroxybenzene with aldehydes such as formaldehyde, acetaldehyde, benzaldehyde and furfural, and polyhydroxystyrene and its derivatives. Is preferably used. If necessary, an alkali-insoluble resin such as polymethylmethacrylate or styrene may be blended with the resin to make it alkali-soluble as a whole.

Although the compound containing a 1,2-naphthoquinonediazide group is not particularly limited, for example, J. Kosar, “Lig
ht-sensitive Systems "(John Wiley & Sons, Inc) 343
To the compounds disclosed on page 351. Preferable examples thereof include 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, and 1,2-naphthoquinonediazide-5-sulfonic acid ester. More preferably, 1,2-naphthoquinonediazide-5-sulfonic acid or an ester of 1,2-naphthoquinonediazide-4-sulfonic acid and a polyhydroxyaromatic compound is used. As the polyhydroxy aromatic compound, 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, quercetin and the like are preferably used.

The ratio of the alkali-soluble resin to the compound containing a 1,2-naphthoquinonediazide group is 5 to 100 parts by weight, preferably 10 to 60 parts by weight, relative to 100 parts by weight of the resin.

Usually, these are dissolved in a suitable solvent before use. The solvent is not particularly limited as long as it is a solvent that has sufficient solubility in the photosensitizer and the resin and gives good film-forming properties, but is not limited to methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, etc. Cellosolve-based solvent, ester solvent such as butylacetate or amylacetate, or highly polar solvent such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, or a mixed solvent thereof, or aromatic hydrocarbon is further added. Things can be mentioned.

A well-known resist image can be obtained even in a high reflectance portion by applying the resist composition to a substrate by a known method, exposing it to a predetermined pattern, and developing the resist composition.

The developer of the positive photoresist composition of the present invention contains
Sodium hydroxide, potassium hydroxide, sodium carbonate,
Inorganic alkalis such as sodium silicate, sodium metasilicate and aqueous ammonia, primary amines such as ethylamine and n-propylamine, diethylamine, di-n-
Secondary amines such as propylamine, tertiary amines such as triethylamine and methyldimethylamine, quaternary ammonium salts such as tetramethylammonium hydroxide and trimethylhydroxyethylammonium hydroxide, or alcohols and surface active agents. The thing which added the agent etc. can be used.

The positive photoresist composition of the present invention is useful not only for VLSI production but also for general IC production, mask production, or offset printing.

(Examples) Next, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples unless the gist thereof is exceeded.

Example 1 A novolak resin obtained by condensing m-cresol, p-cresol, and 2,5-xylenol with formaldehyde using oxalic acid as a catalyst (m-cresol / p-cresol / 2,5-xylenol = 3 / 4/3, Mw = 6,500) 100 parts by weight of 2,3,4,4′-tetrahydroxybenzophenone
33 parts by weight of 1,2-naphthoquinonediazide-5-sulfonic acid ester (average esterification rate: 75%) was added to ethyl cellosolve.
Dissolve in 315 parts by weight to prepare a photoresist base.

3 parts by weight (2.2 wt% of total solids in the resist) of 3-cyano-6-hydroxy-5 was added to the photoresist base material.
-(P-isobutyloxycarbonylphenylazo)-
4-Methyl-1-propyl-2-pyridone (Compound I)
Dissolve.

The photoresist composition thus obtained was applied on a silicon wafer to a film thickness of 1.0 μ, and pre-baked in a clean oven at 90 ° C. for 30 minutes, followed by a reduction projection exposure apparatus (“Canon FP
A141 ") and exposed to an aqueous solution of 2.38 wt% tetramethylammonium hydroxide at 25 ° C for 1 minute.
Find the exposure amount (Eth) that makes the exposed film thickness just 0,
The reciprocal is defined as the sensitivity. Table 1 shows the relative values with respect to the sensitivity of the photoresist base material containing no light absorbing material. In addition, this resist is applied to an A1 vapor deposition substrate with a step of 1 μm, pattern exposure and development are performed, and the resist image is SE
As a result of observation with M, the thinning of the resist was not seen even in the step portion, and the antihalation function was sufficient.

As another measure of anti-halation function, this resist composition was applied on a quartz wafer to a thickness of 1.0 μm and irradiated with a high pressure mercury lamp to completely bleach the photosensitizer, after which a wavelength of 436 nm (exposure by a reduction projection exposure device was used. The transmittance at the wavelength) was measured. T _{λ = 436} = 36%.

Example 2 5- (m-chlorophenylazo) instead of compound I
-3-Cyano-6-hydroxy-4-methyl-1- (2
Evaluation was conducted in the same manner as in Example 1 except that 3 parts by weight (2.2% of total solids) of -ethylhexyl) -2-pyridone (Compound II) was used. The results are shown in Table 1.

Comparative Example 1 N-Methyl-4-cyclohexylamino-1,8-naphthalene dicarboxylic acid imide (Compound III), which is a light absorber having insufficient hydrophilicity instead of Compound I 1,3 parts by weight was added and the same evaluation as in the example was carried out. The results are shown in Table 1.
However, the decrease in sensitivity was remarkable.

Comparative Example 2 Instead of Compound I, 3-methyl-5-hydroxy-1- (2,5-dichloro-4-sulfophenyl) -4- (4sulfophenylazo) -pyrazole disodium salt having extremely strong hydrophilicity ( Compound IV) Was attempted to dissolve in the photoresist base material, but practically none.

Comparative Example 3 In Example 1, 0.07 part by weight of compound I (total solid content) was used.
(0.05%), but the same evaluation was performed. The anti-halation function was not enough.

(Effects of the Invention) The composition of the present invention can provide a photoresist excellent in line width controllability even on a high reflectance substrate and excellent in various characteristics such as sensitivity, resolution and heat resistance. Can be used very suitably for the development of.

Claims (1)

[Claims] 1. A positive photoresist composition comprising an alkali-soluble resin and a compound containing a 1,2-naphthoquinonediazide group, and a light-absorbing material represented by the following structural formula in an amount of 0.1 to 10 wt% of the total solid content. A positive photoresist composition comprising: (In the formula, R ¹ represents a C _{1 to} C ₆ alkyl group, R ² represents an optionally substituted alkyl group, an optionally substituted aryl group, and a-(CH ₂ ) CO ₂ R ³ group (R ³ represents a C ₁ -C ₆ alkyl group), and Ar represents an optionally substituted aryl group.)