JPH04214563A - Photoresist composition - Google Patents

Abstract

PURPOSE:To decrease halation in i-ray lithgraphy and to improve resist characteristics by incorporating an alkali-soluble resin, a compd. containing 1, 2-naphthoquinone diazide group, and light-absorbing material into a resist compsn. CONSTITUTION:This photoresist compsn. contains an alkali-soluble resin, a compd. containing 1,2-naphthoquinone diazide group, and a light-absorbing material expressed by formula I. In formula I, R<1> and R<2> are hydrogen atom or lower alkyl groups which may have a substd. hydroxyl group, and m and n are integers from 1 to 5 satisfying that the sum of m and n is >5. When m or n is >2, plural R<1> or R<2> may be same or different. By applying this resist compsn. on a substrate, exposing to light to obtain a specified pattern, and developing, a good resist image can be obtd. even for the area of high reflectance.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to photoresist compositions that are sensitive to broad radiation. Specifically, the present invention relates to the improvement of a photoresist composition comprising an alkali-soluble resin and a compound containing a 1,2-naphthoquinonediazide group.

0002

2. Description of the Related Art As semiconductors become more highly integrated and operate at higher speeds, requirements for microfabrication techniques used in their manufacture are becoming increasingly strict. Among these microfabrication technologies, resist process technology in particular is a fundamental technology for advancing the manufacture of semiconductors, and the level of requirements for photoresists is increasing year by year.

For example, in recent years, taking DRAM as an example, 4
Production of M-bit DRAMs has begun, and progress is being made toward higher integration of 16 Mbits and even 64 Mbits. Under these circumstances, photolithography technology has changed from the conventionally used g-line (wavelength: 436 nm) light source to the i-line (wavelength: 436 nm), which is more advantageous in terms of resolution and depth of focus. 365 nm).

On the other hand, as integration progresses, the level differences in semiconductor substrates caused by the formation of semiconductor elements are also becoming more complex. Furthermore, the step base is of high reflectance (for example, metallic material such as aluminum or tungsten polycide).
In this case, there is a problem that poor resolution (halation) of the resist pattern occurs due to reflection of the exposure light from the side surface of the step, making it difficult to perform highly accurate patterning.

[0005] In order to solve these problems, it is known to add a light-absorbing material to a photoresist (
For example, Japanese Patent Publication No. 51-37562). However, most of the light-absorbing materials that have been shown to be compounded are for g-line use, and there are not many known ones that are effective in photolithography using i-line. On the other hand, if a light-absorbing material is added to the resist to give it light-absorbing properties, the anti-halation ability will improve, but due to the light-absorbing property, the light usage efficiency of the photosensitizer will decrease, resulting in a decrease in sensitivity. , other problems may occur such as reduced adhesion between the substrate and the resist, or striation during resist application, and other properties of the resist may be affected at all or only to the extent that it is practically acceptable. Selecting light-absorbing materials is very difficult.

[0006]

[Problem to be Solved by the Invention] The present inventors have particularly
As a result of intensive research to provide a photoresist that does not have the above-mentioned drawbacks in photolithography using wires, we found that when a compound with a specific structure is selected as a light-absorbing material added to a photoresist, We have discovered that it is possible to prevent the effects of reflection and to keep the decrease in sensitivity within a practical range, and that it also has good adhesion between the substrate and resist, and there are no problems with resist coating properties, leading to the present invention. did.

[0007]

[Means for Solving the Problems] That is, the gist of the present invention is as follows:
A photoresist composition comprising an alkali-soluble resin, a compound containing a 1,2-naphthoquinonediazide group, and a light-absorbing material represented by the general formula [I]. The present invention will be explained in detail below.

The alkali-soluble resins used in the present invention include phenol, cresol, ethylphenol, t-butylphenol, xylenol, naphthol, 1,4-
So-called novolac resins, which are obtained by condensing hydroxy aromatic compounds such as dihydroxybenzene and 1,3-dihydroxybenzene with aldehydes such as formaldehyde, acetaldehyde, benzaldehyde, and furfural, as well as polyhydroxystyrene and derivatives thereof, are preferably used. . If necessary, these alkali-soluble resins may be blended with alkali-insoluble resins, such as polymethyl methacrylate, styrene, etc., to make the entire composition alkali-soluble.

The compound containing a 1,2-naphthoquinonediazide group, which is a photosensitive substance, is not particularly limited, but for example, J. “Lightse” by Kosar
nsitive Systems” (John Wi
ley & Sons, Inc) 343-351
Examples include the compounds disclosed on p. Preferably, 1
, 2-naphthoquinonediazide-5-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, and the like. More preferably, esters of 1,2-naphthoquinonediazide-5-sulfonic acid or 1,2-naphthoquinonediazide-4-sulfonic acid and polyhydroxy aromatic compounds are used. Examples of polyhydroxy aromatic compounds include polyhydroxybenzophenone such as 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, and 2,3,4,2',4'-pentahydroxybenzophenone. Hydroxybenzophenones, quercetin or alkylphenols,
Polymers obtained by dehydration condensation polymerization of phenol derivatives such as resorcinols and pyrogallols and carbonyl compounds such as formalin, acetaldehyde, benzaldehyde, and acetone are preferably used.

The ratio of the alkali-soluble resin and the compound containing a 1,2-naphthoquinonediazide group is 5 to 100 parts by weight of the compound per 100 parts by weight of the alkali-soluble resin,
Preferably it is 10 to 60 parts by weight. The photoresist composition of the present invention further comprises an alkali-soluble resin and a compound containing a 1,2-naphthoquinone diazide group;
It is characterized by containing a light-absorbing material represented by [I].

In the general formula [I] shown above, R1 and R2
Examples of the lower alkyl group represented by C1 to C such as methyl group, ethyl group, n-propyl group, and i-propyl group
4 lower alkyl groups, which may be substituted with a hydroxy group. Specific examples of such include hydroxymethyl, hydroxyethyl, and the like. R1
and R2 is particularly preferably a hydrogen atom or an unsubstituted lower alkyl group, and particularly preferably a hydrogen atom, a methyl group, or an ethyl group. Note that R1 and R2 may be the same or different, and if m or n is 2 or more, multiple R1
or R2 may be the same or different, but usually R
1 and R2 are preferably the same.

The total number of m and n in the above general formula [I] must be 5 to 10, preferably 5 or 6. If it is less than 5, the light absorption becomes small in the i-line exposure band, making it impossible to sufficiently prevent the influence of reflection from the substrate. Therefore, it is necessary to add an extremely large amount of light-absorbing material to the photoresist composition compared to the case where the sum of m and n is 5 or more, which results in, for example, a decrease in the resist remaining film rate and This results in significant deterioration of resist properties such as deterioration of the pattern profile and further deterioration of thermal stability of the resist, making it unsuitable as a resist especially when i-line is used as the exposure wavelength. It is preferable that m and n are both 2 or more, and it is particularly preferable that the positions at which -OR1 and -OR2 are introduced into the benzene ring are at least the 2-position and the 4-position, respectively.

[0013] Specific compounds include, for example, 2,3
, 4,3',4',5'-hexahydroxybenzophenone, 2,4,5,2',4',5'-hexahydroxybenzophenone, 2,3,4,2',4'-pentahydroxybenzophenone , 2, 3, 4, 5, 6, 2',
3',4',5',6'-decahydroxybenzophenone, 2,3,4,5,2',3',4',5'-octahydroxybenzophenone, 2,3,4,2',3
',4'-hexahydroxybenzophenone, 2,5,
2',5'-tetrahydroxy-4,4'-dimethoxybenzophenone, 3,3'-dihydroxy-2,4,2
',4'-tetraethoxybenzophenone, 2,3,4
, 2',3',4'-hexahydroxymethoxybenzophenone and the like.

The amount of the light-absorbing material added is 0.1 to 10% by weight based on the total solid content to be dissolved in the below-mentioned solvent in the composition.
, preferably 0.5 to 5.0% by weight. If the amount added is less than this, the antihalation effect will not be sufficient, and if it is more than this, it will cause deterioration of resist properties such as a decrease in the residual film ratio of the resist, deterioration of the resist pattern profile, and deterioration of the thermal stability of the resist, which is not preferable.

The photoresist composition according to the present invention is usually used by dissolving each component in an appropriate solvent. The solvent is not particularly limited as long as it has sufficient solubility for compounds containing 1,2-naphthoquinone diazide groups and alkali-soluble resins and provides good coating properties, but examples include methyl cellosolve, ethyl cellosolve, Cellosolve solvents such as methyl cellosolve acetate and ethyl cellosolve acetate, ester solvents such as butyl acetate, amyl acetate, and ethyl lactate, highly polar solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone, or mixed solvents thereof. , or those to which an aromatic hydrocarbon is further added.

[0016] The above resist composition can be applied to a substrate by a known method, exposed to light in a predetermined pattern, and developed to obtain a good resist image even in areas with high reflectance. The developing solution for the photoresist composition of the present invention includes inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-
Primary amines such as propylamine, diethylamine,
Secondary amines such as di-n-propylamine, tertiary amines such as trimethylamine and triethylamine, quaternary ammonium salts such as tetramethylammonium hydroxide and trimethylhydroxyethylammonium hydroxide, or alcohols, It is possible to use one to which a surfactant or the like is added.

The photoresist composition of the present invention is mainly used as a positive photoresist, and is useful not only for the production of VLSIs but also for general IC production, as well as mask production and offset printing. .

[0018]

[Examples] Next, the present invention will be explained in more detail with reference to specific examples, but the present invention is not limited to the examples in any way unless the gist of the invention is exceeded. Example 1 100 parts by weight of phenolic novolac resin and 2,3,4
A photoresist base was prepared by dissolving 22 parts by weight of 1,2-naphthoquinonediazide-5-sulfonic acid ester of , 4'-tetrahydroxybenzophenone (average degree of esterification about 100%) in 315 parts by weight of ethyl cellosolve acetate. 2,3,4,2',4'-pentahydroxybenzophenone as a light-absorbing material was dissolved in this photoresist base in an amount to give the concentration shown in Table 1 (representing the weight percent of the total solids dissolved in the solvent). did. The photoresist composition thus obtained was applied to a thickness of 1.50 μm onto an aluminum wafer with a diameter of 6 inches with a step of 1 μm using a spin coating device, and NA=0.50) and exposed using 2.38
It was developed with a wt % tetramethylammonium hydroxide aqueous solution at 23° C. for 60 seconds. Table 1 shows the results of observing the resist pattern thus obtained using a scanning electron microscope. There was no thinning of the resist at the stepped portion, and the anti-halation ability was sufficient, and no constrictions such as undercuts were observed at the ends of the resist in contact with the substrate.

In Table 1, the sensitivity represents a relative value based on the sensitivity of a photoresist base containing no light-absorbing material (Comparative Example 1), and if it is 0.7 or more, there is no problem in practical use. Can be used. Further, the anti-halation ability was determined by observing the thinning of the resist at the stepped portion and expressed according to the following criteria. ◎: No change in line width ○: Almost no change △: Significantly thinner ×: Disconnected or almost disconnected

Example 2 The same procedure as in Example 1 was carried out except that 2,3,4,2',3',4'-hexahydroxybenzophenone was added as a light-absorbing material in an amount having a concentration shown in Table 1. The results are shown in Table 1.

Example 3 2,2',3-trihydroxy-4,
The same procedure as in Example 1 was carried out except that 4'-dimethoxybenzophenone was added in an amount to give the concentration shown in Table 1. The results are shown in Table 1.

Comparative Example 1 Example 1 except that the light-absorbing material was removed from Example 1.
I did the same thing. The results are shown in Table 1.

Comparative Example 2 The same procedure as in Example 1 was carried out except that 2,3,4-trihydroxybenzophenone was added as a light-absorbing material in an amount having a concentration shown in Table 1. The results are shown in Table 1.

Comparative Example 3 The same procedure as in Example 1 was carried out except that 2,3,4,4'-tetrahydroxybenzophenone was added as a light-absorbing material in an amount to give the concentration shown in Table 1. The results are shown in Table 1.

Comparative Example 4 The same procedure as in Example 1 was carried out except that 4-hydroxyazobenzene was added as a light-absorbing material in an amount having the concentration shown in Table 1. However, striation occurred during resist application, and the evaluation was virtually impossible. I could not do it.

[0026]

[Table 1]

[0027]

Claims (1)

[Claims] 1. A photoresist composition comprising an alkali-soluble resin, a compound containing a 1,2-naphthoquinonediazide group, and a light-absorbing material represented by the following general formula [I]. [Formula 1] (In the formula, R1 and R2 each independently represent a hydrogen atom or a lower alkyl group optionally substituted with a hydroxyl group, m and n each independently represent an integer of 1 to 5, and m and n If the total of is 5 or more and m or n is 2 or more, multiple R1 or R2 may be the same or different.)
2. The photoresist composition according to claim 1, wherein the photoresist composition contains 0.1 to 10% by weight of the light-absorbing material based on the solid content of the photoresist composition.