JPH01289946A - Positive type resist composition - Google Patents

Abstract

PURPOSE:To improve the sensitivity, the thermo-resisting property and the residual film ratio of the title composition by incorporating a novolak resin, a quinone diazide compd. and a specified compd. in the composition. CONSTITUTION:The composition is composed of the novolak resin, the quinone diazide compd. as a radiation sensitive component and the compd. shown by formula I. In the formula, X is a lower alkylene group, (l), (m) and (n) are each an integer of 1-8. The benzene ring contd. in the compd. may be further substd. with an another substituting group such as alkyl group. The compounding amount of the compd. is preferably 5-20wt.% based on the total solid matter contd. in the positive type resist composition. Thus, the composition with the excellent sensitivity, thermo-resisting property and residual film ratio, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a radiation-sensitive positive resist composition that is excellent in sensitivity, heat resistance, and film retention rate.

<Prior Art> A radiation-sensitive resist composition containing a compound having a quinonediazide group such as a naphthoquinonediazide group or a benzoquinonediazide group is alkali-based by decomposing the quinonediazide group and producing a carboxyl group when irradiated with light of 800 to 500 nm. It is used as a positive resist by taking advantage of the fact that it changes from an insoluble state to an alkali-soluble state. In this case, novolak resins are usually used in combination. Novolac resins are important for obtaining uniform and durable resist coatings. This positive resist has a feature of significantly superior resolution compared to a negative resist. Taking advantage of this high resolution, copper laminates for printed wiring, IC and LS
Photo-etching method used when manufacturing integrated circuits such as I≠
It is used as a protective film for coatings.

Among these, integrated circuits are becoming increasingly finer as they become more highly integrated, and submicron pattern formation is now required. Conventionally, a mask contact method has been used to form integrated circuits, but this method is said to have a limit of 2 μm, and a reduction projection exposure method is attracting attention as an alternative. This method is a method in which the pattern of a master mask (reticle) is reduced and projected using a lens system for exposure.
Resolution is possible down to submicron. However, one of the problems with this reduction projection exposure method is that the throughput is low. That is, unlike the conventional batch exposure method such as the mask contact method, the reduction projection exposure method uses divided and repeated exposure, which results in a longer total exposure time per wafer.

The most important way to solve this problem is to improve the sensitivity of the resist used, as well as improving the equipment. If exposure time can be shortened by increasing sensitivity, throughput can be improved.

The easiest way to achieve high sensitivity in a positive resist material made of a naphthoquinone diazide compound and a novolak resin is to lower the molecular weight of the novolak resin. When the molecular weight of the novolak resin is low, its dissolution rate in an alkaline developer increases, and the apparent sensitivity of the resist increases. However, with this method, film burrs in non-exposed areas become large (so-called reduction in residual film rate), pattern shape deteriorates, and the difference in dissolution rate in developer between exposed and non-exposed areas becomes small. , the so-called T
A very serious problem arises in that the (gamma) value decreases, that is, the resolution decreases. Furthermore, in general, when the molecular weight of the novolac resin is low, the heat resistance becomes poor.

Other methods for improving the sensitivity of resists include increasing the development time or increasing the alkali concentration of the developer. However, even in these methods, although the solubility of the resist in the developing solution increases and thus the apparent sensitivity is certainly improved, the remaining film rate decreases, which leads to a decrease in resolution, which is not preferable. That is, as described above, film-forming sensitivity, heat resistance, and film retention rate tend to contradict each other, and an attempt to improve one causes the disadvantage that the other deteriorates.

<Problems to be Solved by the Invention> An object of the present invention is to provide a positive resist composition with excellent sensitivity without impairing heat resistance and residual film rate.

Specific Means to Solve the Problems〉As a result of intensive study-1, the present inventors found that when 1,8,5 tris(hydroxybenzyl)benzenes were made to coexist in a positive resist composition, the heat resistance The present inventors have also discovered that the sensitivity can be significantly improved without impairing the residual film rate, and have completed the present invention.

That is, the present invention provides a novolac resin, a quinonediazide compound as a radiation-sensitive component, and a compound of the following general formula (1
) is a positive resist composition.

Describing the positive resist composition of the present invention in more detail below, a quinonediazide compound is used as the radiation-sensitive component. This quinonediazide compound is
It can be obtained by a known method, for example, by condensing naphthoquinonediazide sulfonic acid chloride or benzoquinonediazide sulfonic acid chloride with a compound having a hydroxyl group in the presence of an alkali. Examples of compounds having a hydroxyl group include hydroquinone, resorcinol, phloroglycin, 2,4-dihydroxybenzophenone, 2,8,4-trihydroxybenzophenone, 2,
8. Tetrahydroxybenzophenones such as 8', 4-tetrahydroxybenzophenone, 2,8,4,4'-tetrahydroxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone, 2,8,8' , 4,4'-pentahydroxybenzophenone, 2,8,8',4,5'
Examples include pentahydroxybenzophenones such as -pentahydroxybenzophenone, gallic acid alkyl esters, and the like.

The novolak resin used in the present invention is obtained by reacting phenols with aldehydes such as formalin.

Specific examples of phenols used as raw materials for the novolak resin used in the present invention include phenol, cresol 1, xylenol, ethylphenol, trimethylphenol, propylphenol, butylphenol, dihydroxybenzene, naphthols, and the like.

These phenols can be used alone or in combination.

It is particularly preferable to use cresols as the phenols. In this case, Metaphresy (X) alone may be used, or a mixed meta/para cresol may be used. In other words, the cresol preferably has a metacresol/paracresol ratio of 10010 to 80/70.

In the present invention, an aqueous formaldehyde solution (formalin) or paraformaldehyde, which is an oligomer of formaldehyde, is used as the formaldehyde to be subjected to an addition condensation reaction with phenols. In particular, 87% formalin is industrially mass-produced and is convenient.

In the present invention, the addition condensation reaction between phenols and formaldehyde is carried out according to a conventional method.

The reaction is usually carried out at 60-120°C for 2-80 hours.

As the catalyst, organic or inorganic acids, divalent metal salts, etc. are used. Specific examples include oxalic acid, hydrochloric acid, sulfuric acid, perchloric acid,
Examples include P-4 luenesulfonic acid, trichloroacetic acid, phosphoric acid, formic acid, zinc acetate, and magnesium acetate.

Further, the reaction may be carried out in bulk or an appropriate solvent may be used.

Next, regarding the molecular weight of novolak resin, the optimum range varies depending on the mixing ratio of phenols used, the type of catalyst, and the reaction conditions, but it is generally determined by gel permutation chromatography (hereinafter referred to as GPC). The weight average molecular weight (Mw) is 2000 to 50000
, more preferably 8000 to aooooo.

Among these, as a novolac resin, the area ratio of the GPC pattern (using a UV (254 nm) detector) is 150 to 500 less than 1iI on a polystyrene equivalent molecular dish (not including unreacted monomers of phenols), which is a large area below C. ) is 8 to 85%, and the range of 500 to less than 5000 in polystyrene equivalent molecular weight (hereinafter referred to as B region) is 0 to 80%, and the molecular weight in polystyrene equivalent molecular weight is 5 to 80%.
The range exceeding 000 (hereinafter referred to as TC area) is 85
~92% and B area/A area = 2.50 or less, a novolac resin exhibits a preferable effect.

Note that the molecular weight of the novolac resin as used in the present invention is a value determined by GPC using monodisperse polystyrene as a standard.

GPC measurements were performed using Toyo Soda's G-4000Ha, G
-2000H columns were connected in series, and tetrahydrofuran was flowed at a flow rate of 1 ml/min as a carrier solvent. Chromatograph is 2541m U
A V detector was used. The molecular weight was determined from a calibration curve obtained using monodisperse polystyrene. That is, the weight average molecular weight is 800,000.100.000.8, respectively.
A calibration curve was prepared by the 8th order regression method using five monodispersed polystyrenes of 5,000, 4,000, and 800 and a styrene monomer (molecular weight 104).

Compound (I) is represented by the above general formula, but the benzene ring may be further substituted with other substituents, such as an alkyl group. Specific examples are given. These may be used alone or in combination.

Regarding the amount of compound (I) added, it is preferable that the proportion thereof in the total solid content in the positive resist composition is in the range of 5 to 20% by weight.

A positive resist solution is prepared by mixing and dissolving the quinonediazide compound, novolak resin, and compound (I) in a solvent. The ratio of resin to quinonediazide compound is preferably in the range of 1:1 to 6:1. The solvent used is preferably one that evaporates at an appropriate drying rate and provides a uniform and smooth coating film. Examples of such solvents include ethyl cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether acetate, butyl acetate, methyl isobutyl ketone, xylene, and the like. The positive resist composition obtained by the above method may further contain a small amount of a resin, dye, etc. as an additive, if necessary.

<Effects of the Invention> The positive resist composition of the present invention is a resist composition that is excellent in sensitivity, heat resistance, and film retention rate.

<Examples> Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by these Examples.

Using the Examples and Comparative Examples, Ethyl Celsolve Acetate 48 was prepared with the composition shown in Table 1 together with the novolac resin and the quinonediazide compound.
A resist solution was prepared. Each of these compositions was passed through a 0.2 tan Teflon filter to prepare a resist solution.

This was coated to a thickness of 1.8 μm on a silicon wafer cleaned by a conventional method using a spin coater.

This silicon wafer was then baked on a hot plate at 100° C. for 60 seconds. Then add 486 to this wafer.
Exposure was carried out using a reduction projection exposure machine having an exposure wavelength of nm (g-line) and changing the exposure amount stepwise.

A positive pattern was obtained by developing this for 1 minute with Sumitomo Chemical developer 5OPD. Resist sensitivity was determined by plotting the residual film thickness of the resist against the exposure amount. Further, the remaining film rate was determined from the remaining film thickness of the unexposed area.

The heat resistance of the resist was determined by heating the wafer after the resist pattern was formed on a direct hot plate at a predetermined temperature for 8 minutes, and then observing the presence or absence of thermal deformation of the 8 Itm line and space pattern using an SEM.

(Margin below) Table-1 Various compositions and resist performance 1) Parts represent parts by weight.

2) Novolak resin A; metacresol/paracresol = T/8, formalin/cresol = 0, 8/1
Weight average molecular weight 9800 (polystyrene equivalent) obtained by reacting with an oxalic acid catalyst at a charging molar ratio of
novolak resin.

Novolac resin B; formalin/cresol = 0.8
/ □metacresol novolak resin obtained by reacting with an oxalic acid catalyst in 1, and the area ratio of its GPC pattern is 15.9% in the range of molecular weight 150 to less than 500 (not including metacresol monomer), The molecular weight range of 500 to less than 5000 was 24.0%, and the molecular weight was 500 to less than 5000.
(Novolac resin with a weight average molecular weight of ff1lo020 in which the range exceeding +00 is 60.1% (all molecular weights are in terms of polystyrene).

Quinonediazide compound C: naphthoquinone-(1゜2)-
Diazide = (2)-5-sulfonic acid lorido 2.8.
Condensation reaction product of 4-trihydroxybenzophenone.

Quinonediazide compound D: naphthoquinone-(1°2)-
Diazide-(2)-5-sulfonic acid lorido 2.8.
4. Condensation reaction product of 4'-tetrahydroxybenzophenone 8) Minimum exposure amount (msec) D at which the resist film thickness becomes 0
4) Temperature (C) at which an 8 μm line and space pattern begins to undergo thermal deformation.

(Margin below) (17 completed)

Claims (1)

[Scope of Claims] A positive resist composition comprising a novolak resin, a quinonediazide compound, and a compound represented by the following formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, X represents a lower alkylene group, and l, m, and n represent integers from 1 to 3. ]