JPH04230754A - Positive type resist composition - Google Patents

Abstract

PURPOSE:To obtain a positive type resist compsn. having superior sensitivity, heat resistance and a high residual film rate by incorporating an alkali-soluble resin, a quinonediazido compd. and a specified compd. CONSTITUTION:An alkali-soluble resin, a quinonediazido compd. and a compd. represented by formula I are incorporated. In the formula I, each of R1-R9 is alkyl, H, halogen or -OH but at least one of R1-R8 is -OH. The alkali-soluble resin is novolak resin and the area of the pattern of a component having <=900mol.wt. (expressed in terms of polystyrene) measured by GPC (UV-254nm) is <=25% of the total area of the pattern of the resin. A resist compsn. having superior sensitivity, heat resistance and a high residual film rate is obtd. This compsn. has low absorbance to the wavelength of KrF excimer laser light and is useful as a resist compsn. for KrF excimer laser.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-sensitive positive resist composition having excellent sensitivity, heat resistance and film retention rate.

0002

[Prior Art] A radiation-sensitive resist composition containing a compound having a quinonediazide group changes from an alkali-insoluble state to an alkali-soluble state by decomposing the quinonediazide group and producing a carboxyl group when irradiated with light having a wavelength of 500 nm or less. It is used as a positive resist by taking advantage of this fact. This positive resist has a feature of significantly superior resolution compared to negative resists, and is
It is used in the production of integrated circuits such as and LSI.

In recent years, integrated circuits have become increasingly finer due to higher integration, and submicron pattern formation is now required. Therefore, instead of the mask contact method (which is said to have a limit of 2 μm) that has been conventionally used for forming integrated circuits, a reduction projection exposure method is attracting attention. This method is a method in which the pattern of a master mask (reticle) is reduced and projected using a lens system for exposure, and the resolution can be down to submicrons. However, in the reduction projection exposure method, the wafer 1
There is a problem that the total exposure time per sheet becomes long.

[0004] As a method to solve this problem, in addition to improving the apparatus, the most important method is to increase the sensitivity of the resist used. For example, there is a method of lowering the molecular weight of alkali-soluble resins such as quinonediazide compounds and novolac resins. When the molecular weight of the alkali-soluble resin is low, its dissolution rate in an alkaline developer increases, and the apparent sensitivity of the resist increases. However, with this method, film loss in non-exposed areas increases (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. This causes a very serious problem of a decrease in the so-called γ value, that is, a decrease in resolution. Furthermore, in general, if the molecular weight of the alkali-soluble resin is low, the heat resistance will be 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. As described above, sensitivity, heat resistance, and residual film rate generally tend to contradict each other, and an attempt to improve one causes the disadvantage that the other deteriorates.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a positive resist composition with excellent sensitivity without impairing heat resistance or film retention rate.

[0006]

[Means for Solving the Problems] As a result of intensive studies, the present inventors made a compound represented by the following general formula coexist in a positive resist composition. The present invention was completed based on the discovery that sensitivity can be improved.

That is, the present invention is a positive resist composition containing an alkali-soluble resin, a quinonediazide compound, and a compound represented by the following general formula (I).

[0008]

[Case 2]

(In the formula, R1 to R9 each independently represent an alkyl group, a hydrogen atom, a halogen atom, or an -OH group, and at least one of R1 to R9 is an -OH group.)

The positive resist composition of the present invention will be described in more detail below. Compound (I) can be synthesized using m- and p-isopropenylbenzene or a linear dimer thereof by the method described in US Pat. No. 3,288,864.

The alkyl group represented by R1 to R9 in compound (I) is preferably a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group. Examples of the halogen atom include F atom, Cl atom, Br atom, and I atom. As compound (I),

00
12]

[Chemical formula 3]

[0013] etc. are exemplified. These may be used alone or in combination.

The quinonediazide compound can be obtained by a known method, for example, by condensing a naphthoquinonediazide sulfonic acid halide or benzoquinonediazide sulfonic acid halide with a compound having a hydroxyl group in the presence of a weak alkali. Examples of compounds having a hydroxyl group include hydroquinone, resorcinol, phloroglucin, 2,4-dihydroxybenzophenone,
, 3,4-trihydroxybenzophenone, 2,2',
3-trihydroxybenzophenone, 2,2',4-trihydroxybenzophenone, 2,2',5-trihydroxybenzophenone, 2,3,3'-trihydroxybenzophenone, 2,3,4'-trihydroxybenzophenone, 2,3',4-trihydroxybenzophenone, 2,3',5-trihydroxybenzophenone, 2
, 4,4'-trihydroxybenzophenone, 2,4'
, 5-trihydroxybenzophenone, 2',3,4-
Trihydroxybenzophenones such as trihydroxybenzophenone, 3,3',4-trihydroxybenzophenone, 3,4,4'-trihydroxybenzophenone, 2,3,3',4-tetrahydroxybenzophenone, 2,3,4 , 4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2',3,4-tetrahydroxybenzophenone, 2,2',3,4'-tetrahydroxybenzophenone, 2 , 2',5,5'-tetrahydroxybenzophenone, 2,3',4',5-tetrahydroxybenzophenone, 2,3',5,5'-tetrahydroxybenzophenones such as 2,3',5,5'-tetrahydroxybenzophenone, 2,2 ',3,4,4'-pentahydroxybenzophenone, 2,2',3,4,5'-pentahydroxybenzophenone, 2,2',3,3',4-pentahydroxybenzophenone, 2,3,3 ',4,5'-pentahydroxybenzophenones such as pentahydroxybenzophenone, 2,3,3',4,4',5'-hexahydroxybenzophenone, 2,2',3,3',4,
Hexahydroxybenzophenones such as 5'-hexahydroxybenzophenone

[0015]

[C4]

(However, in the formula, q represents a number from 0 to 4, r represents a number from 1 to 5, and q+r is 2 or more. R10, R11, and R12 each independently represent a hydrogen atom, an alkyl , alkenyl group, cyclohexyl group, or aryl group), gallic acid alkyl esters, and the like.

Examples of alkali-soluble resins used in the present invention include novolac resins obtained by reacting phenols with aldehydes such as formalin. Specific examples of phenols used as raw materials for novolac resins include phenol, cresol, xylenol, ethylphenol, trimethylphenol, propylphenol, methylbutylphenol, butylphenol, dihydroxybenzene, naphthols, and the like. These phenols can be used alone or in combination.

[0018] It is particularly preferable to use cresols as the phenols. In this case, only meta-cresol may be used, or a mixed meta- and para-cresol may be used. That is, the cresol preferably has a meta-cresol/para-cresol (weight ratio) of 100/0 to 30/70.

In the present invention, an aqueous formaldehyde solution (formalin) or paraformaldehyde is used as the aldehyde to be subjected to an addition condensation reaction with the phenol. In particular, 37% formalin is conveniently produced because it is industrially mass-produced.

The addition condensation reaction between phenols and aldehydes is carried out according to conventional methods. The reaction is usually 60-120
℃ for 2 to 30 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, p-toluenesulfonic acid, trichloroacetic acid, phosphoric acid, formic acid, zinc acetate, and magnesium acetate. Further, the reaction may be carried out in bulk or a suitable solvent may be used.

Next, regarding the molecular weight of the alkali-soluble resin, the optimum range varies depending on the mixing ratio of the phenols used, the type of catalyst, and the reaction conditions, but it is generally determined by the gel permutation chromatography method (hereinafter referred to as GP).
It is appropriate that the weight average molecular weight (MW) in terms of polystyrene (referred to as C) is 2,000 to 50,000. Among these, an alkali-soluble resin in which the pattern area of a component having a polystyrene equivalent molecular weight of 900 or less measured by GPC (UV-254 nm) is 25% or less of the total area of the GPC pattern is more preferable. A positive resist composition using an alkali-soluble resin of 25% or less has good heat resistance and does not produce development residue (scum).

[0022] In order to obtain a resin containing 25% or less of components having a polystyrene equivalent molecular weight of 900 or less, it can be easily obtained by carrying out a conventional condensation reaction and then performing fractionation or the like. The method of separation is to use a good solvent such as alcohols (methanol, ethanol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ethylene glycol and its ethers, ether esters (ethyl cellosolve,
Ethyl cellosolve acetate, etc.), tetrahydrofuran, etc., and then precipitated, or heptane, hexane, pentane, cyclohexane, etc. to separate the liquids.

The amount of compound (I) added is preferably in the range of 5 to 20% by weight in the total solid content of the resist composition. The positive resist solution is prepared by mixing and dissolving the quinonediazide sulfonic acid ester, the alkali-soluble resin, and the compound (I) in a solvent. Ratio of alkali-soluble resin and quinonediazide compound (
The weight ratio) is preferably in the range of 1:1 to 6:1.

The solvent used should preferably have an appropriate drying rate and evaporate to form a uniform and smooth coating film. Such solvents include ethyl cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve,
Examples include methyl cellosolve, propylene glycol monomethyl ether acetate, butyl acetate, methyl isobutyl ketone, and xylene. The amount of solvent is 30 to 80% (% by weight of solvent) when ethyl cellosolve acetate is used as the solvent. The resist composition obtained by the above method may further contain a small amount of a resin, a dye, etc. as an additive, if necessary.

[0025]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Examples and comparative examples

0026
]

[C5]

Compound (1) (p-OST cyclic dimer, manufactured by Mitsui Toatsu) was dissolved in 48 parts of ethyl cellosolve acetate together with a novolac resin and a quinonediazide compound in the composition shown in Table 1. A resist solution was prepared by filtering the prepared solution through a 0.2 μm Teflon filter. This was coated to a thickness of 1.3 μm using a spin coater on a silicon wafer that had been cleaned by a conventional method. This silicon wafer was then baked on a hot plate at 100° C. for 60 seconds. Next, this wafer was exposed to a reduction projection exposure machine (GCA DSW4800NA=0) having an exposure wavelength of 436 nm (g-line).
．． 28), the exposure amount was changed stepwise. A positive pattern was obtained by developing this for 1 minute with a developing solution SOPD manufactured by Sumitomo Chemical.

The sensitivity of the resist was determined by plotting the remaining film thickness of the resist against the exposure amount. The heat resistance of the resist is determined by heating the wafer after forming the resist pattern on a direct hot plate at a specified temperature for 3 minutes.
SE of the presence or absence of thermal deformation of the Ryan-and-space pattern of m
It was obtained by observing with M. The results are shown in Table 1.

[0029]

1) Novolac resin A: metacresol/
para-cresol = 6/4, cresol/formalin = 1
/0.8 molar ratio, weight average molecular weight 13000 obtained by reacting under reflux using an oxalic acid catalyst
(polystyrene equivalent) novolak resin. Novolac resin B: metacresol/paracresol=
This is a novolac resin obtained by reacting under reflux using an oxalic acid catalyst at a molar ratio of 5/5, cresol/formalin = 1/0.8, and the area ratio of its GPC pattern shows that the molecular weight is less than 900. A novolak resin with an area % of 23.5% and a weight average molecular weight of 8000 (all molecular weights are based on polystyrene). 2) Quinonediazide compound C: naphthoquinone-(1,2
)-diazide-(2)-5-sulfonic acid chloride and 2,
Condensation reaction product with 3,4,4'-tetrahydroxybenzophenone. (Reaction molar ratio 2.7) Quinonediazide compound D: Naphthoquinone-(1,2)-
A condensate of diazide-(2)-5-sulfonic acid chloride and the following compound. (Reaction molar ratio 2.5)

[0031]

[C6]

3) Minimum exposure amount (msec) at which the resist film thickness becomes 0. 4) Temperature (°C) at which a 3 μm line and space pattern begins to undergo thermal deformation.

[0033]

Effects of the Invention The positive resist composition of the present invention is a resist composition excellent in sensitivity, heat resistance, and film retention rate. In addition, this compound has the wavelength of KrF excimer laser (2
48 nm), and is useful as a resist composition for KrF excimer laser.

Claims (1)

[Claims] 1. A positive resist composition containing an alkali-soluble resin, a quinonediazide compound, and a compound represented by the following general formula (I). [Formula 1] (wherein R1 to R9 are each independently an alkyl group,
Represents a hydrogen atom, a halogen atom or an -OH group, and R1 to
At least one of R9 is -OH group. ) [Claim 2] The alkali-soluble resin is a novolak resin,
The pattern area of the component with a polystyrene equivalent molecular weight of 900 or less measured by GPC (UV-254 nm) is
2. The positive resist composition according to claim 1, which accounts for 25% or less of the total area of the GPC pattern.