JPH0345953A - Resist composition - Google Patents

Abstract

PURPOSE:To form patterns which obviate halation and notching on a high- reflectivity substrate and have a stable high resolution even to prebaking by using a specific compd. as a light absorbent. CONSTITUTION:The compd. expressed by formula I is used as the resist compsn. In the formula I, R1 to R5 respectively independently denote hydrogen, 1 to 6C alkoxy group or hydroxy group. The effect of preventing the halation is low if the amt. of using such compd is too small. Profiles and sensitivity are poor if the amt. is too large. Combination use of one or >=2 kinds of other compds. in addition to this compd. is possible as well. The patterns which are free from the halation and notching even with the high-reflectivity substrate and have the high resolution are formed stable without lowering productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a resist composition. More specifically, the present invention relates to a resist composition particularly suitable for forming fine patterns on high reflectance substrates such as aluminum in the production of semiconductor devices such as ICs and LSIs.

<Prior Art> Conventionally, in the manufacture of integrated circuits such as LSIs, resists made of quinone diazide photosensitizers and novolac resins, resists made of bisazide photosensitizers and cyclized rubber resins, and the like have been used.

When manufacturing integrated circuits, resists are used to form fine patterns on various substrates, but on high-reflectivity substrates such as aluminum, aluminum-silicon, and polysilicon, conventional resists cannot be used on substrate surfaces or side surfaces of steps. Due to the reflection of the light, a photosensitive phenomenon occurs in unnecessary areas, resulting in problems such as so-called notching and halation.

In order to improve the above problem and prevent the resolution from deteriorating, Japanese Patent Publication No. 51-37562 discloses a dye (oil yellow (C, I, -11020)) shown in the formula below that has light-absorbing properties in the ultraviolet region.
') has been proposed as a light absorbing agent. Thereby, it is possible to rapidly reduce the amount of light that passes through the resist layer, and to reduce the amount of light that goes around to the light-blocking area.

Hereinafter, in the present invention, a composition consisting of a resin such as a novolak resin and a photosensitizer will be referred to as a "resist", and a composition containing a light absorbing agent will be referred to as a "resist composition".

However, the addition of a light absorbing agent generally causes an undesirable problem in that the sensitivity of the resist is greatly reduced, resulting in a reduction in productivity during semiconductor manufacturing.

In addition, a resist film is usually created by applying a resist composition containing a solvent to a wafer and prebaking to remove the solvent, but some light absorbers may precipitate during storage or sublimate during prebaking. There is a problem in that the density decreases and the resist performance varies.

<Problems to be Solved by the Invention> The present inventors have conducted intensive studies to overcome the drawbacks of the above-mentioned prior art, and as a result, have completed the present invention.

That is, an object of the present invention is to eliminate the drawbacks of the prior art, and to form a high-resolution pattern on a high reflectance substrate that is free from nozzles and notching and is stable against pre-baking. The object of the present invention is to provide a highly sensitive resist composition in which sensitivity decreases little due to the addition of a light absorbing agent.

Another object of the present invention is to have good compatibility with the resist;
Another object of the present invention is to provide a resist composition for microfabrication in which a light absorbing agent does not precipitate during storage (in the resist composition, in the resist composition film after coating and prebeta).

Means for Solving the Problems〉 As a result of intensive studies, the present inventors have determined that the general formula (
The inventors have discovered that by using the compound I), the drawbacks of the prior art can be solved all at once, and have completed the present invention.

That is, the present invention is based on the general formula (I) in which R9 2 3 R1 s each independently represents hydrogen, an alkoxy group having 1 to 6 carbon atoms, or a hydroxy group. This is a resist composition characterized by containing a compound represented by the following. Among R3-R3, 1
It is more preferable that one or two of them are hydroxy groups.

Compounds of general formula (I,) are J, Chefll, Soc,
, Perk in↑rans, 1. (7), 1
555-1560 (I980) and the like. That is, a platform can be formed by a condensation reaction between a compound of formula (n) and a compound of formula (III).

(In the formula, R1, R2, and R3 represent the same meanings as above.) Examples of the compound of primary formula (I) include the following compounds, but the present invention is not limited to these, and Two or more of these compounds can also be used in combination.

As the resist serving as the base material of the resist composition used in the present invention, a resist made of, for example, a novolak resin obtained by addition-condensation reaction of phenols and formaldehyde and a naphthoquinone diazide compound is suitably used.

Among them, cresol/borac resin synthesized from m-cresol and/or p-cresol and formalin, or cresol-based novolac resin synthesized from m-p-cresol, 3,5-xylenol, and formalin, etc. 2.3.4 -) lyhydroxybenzophenone, 2.3.
4.4'-tetrahydroxybenzophenone, 2.2'
, 4.4'-tetrahydroxybenzophenone, 2.
3.3',4-tetrahydroxybenzophenone, 2.
2',3,4゜5-pentahydroxybenzophenone,
2.3゜3', 4.5-pentahydroxybenzophenone 2.3.3', 4.4'-pentahydroxybenzophenone, 2.2', 3.4.4' -pentahydroxybenzophenone, 2.2' A resist containing a naphthoquinone-12-diazide sulfonic acid ester of a polyhydroquine benzophenone such as , 3,3'4-pentahydroquine benzophenone is preferably used.

The amount of the compound represented by general formula (,1) used in the resist composition of the present invention is usually based on the solid content of the resist.
0. 1 to 20%, more preferably 02 to 10%. If this amount is too small, the antihalation effect will be low, and if it is too large, the profile and sensitivity will tend to deteriorate. In addition to the compound of the present invention, one or more other compounds can also be used in the composition of the present invention.

Among these compounds of the present invention, compounds having maximum absorption for light in the region of 550 nm or less, more preferably 300 to 450 nm are preferably used.

<Effects of the Invention> According to the present invention, the drawbacks of the prior art are eliminated at once, and high-resolution patterns without halation or notching can be stably produced even on high-reflectance substrates without reducing productivity. Its industrial utility value is immeasurable, such as being able to form

<Examples> The present invention will be specifically explained below using reference examples and examples, but the present invention is not limited thereto.

Examples 1 to 4 and Comparative Example 1 Positive resist PF-6200 (trade name, manufactured by Sumitomo Chemical Co., Ltd., solid content percentage a1.owt%) containing novolac resin and at least one O-quinonediazide Table 2
Each compound shown in was added to prepare a resist composition.

The compounds of Examples 1 and 2 were synthesized by the method described on page 5 of the specification. The amount of the compound added was such that the absorbance at 365 nn+ was the same as in Comparative Example 1 (addition amount 1°Qwt%). These resists are coated with aluminum film.
The film was coated onto an inch silicon wafer using a spinner to a thickness of 1.8 μm, and prebaked on a hot plate at 100° C. for 1 minute. This was exposed using a reduction projection exposure device (exposure wavelength i-ray (365nω)) by changing the exposure amount stepwise through a test reticle. The film was developed using an automatic developing machine using a static paddle method at 23° C. for 60 seconds.

The effect was evaluated by the method shown below.

[Evaluation method of anti-halation effect]

1. Preparation of step substrate for evaluation A step pattern having the shape shown in FIG. 1 was prepared on a silicon substrate having a 1 μm thick 5iOa film by photolithography, etching, and aluminum sputtering. Typical pattern size is a=4pm% b=Lum, c
=l μm, d=1 μm.

2. Evaluation of anti-halation effect A resist film with a thickness of 1.8 μm was formed by a spin code method on the step substrate with high reflectance produced by the above method.

11th! Exposure and development are performed so that a resist line with a line width (X) of 1.2 μm in a portion without a step is formed across the central concave portion of the step pattern shown in I. (Second
(See figure) i! Resist line width at the center of the step recess after first photodevelopment (
7) Reduction rate for (X) If the amount of decrease in line width is within 10%, it is judged as halation prevention effect (excellent), and 11
~20% (good), 21% or more (bad)
Comparative Example 2 The resist composition was prepared, exposed, and developed in the same manner as in Comparative Example 1 except that no light absorbing agent was added. When the halation prevention effect was evaluated using the same method as Comparative Example 2, Table-
The results shown in 2 were obtained.

As shown in Table 2, in the examples, patterns could be formed with high sensitivity. The formed pattern was sharply resolved, and there was no notching due to reflected light from the side surfaces of the pattern, indicating that the pattern was excellent in preventing halation from the aluminum surface.

On the other hand, the resist of the comparative example was insufficient in terms of sensitivity or antihalation effect.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the shape of a step pattern for evaluation. FIG. 2 is a diagram showing the resist applied, exposed, and developed. (Below the margin J Fig. t → (Diagram)

Claims (1)

[Claims] General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) or hydroxyl group).