JPH04226458A - Positive resist composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

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

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, since the reduction projection exposure method uses divided and repeated exposure, there is a problem that the total exposure time per wafer becomes long.

[0003] 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 an alkali-soluble resin. However, in general, when the molecular weight of the alkali-soluble resin is low, the heat resistance becomes poor. In addition, as a means of increasing sensitivity, it is possible to increase the rate of dissolution in an alkaline developer by appropriately selecting the monomer of the alkali-soluble resin. For example, in a novolak resin, by increasing the ratio of monomers with high solubility in an alkaline developer, such as metacresol and phenol, the rate of dissolution of the resin in the alkaline developer can be increased. However, even if this method achieves high sensitivity without lowering the heat resistance (without lowering the molecular weight of the alkali-soluble resin), the residual film rate generally decreases and the resolution deteriorates significantly. 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.

0004

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

[0005]

[Means for Solving the Problems] As a result of extensive studies, the present inventors have developed a novolak resin obtained by condensing a compound represented by the following general formula with an aldehyde as an alkali-soluble resin for a positive resist composition. The present inventors have found that heat resistance can be significantly improved without impairing sensitivity and film retention rate when used as a method, leading to the completion of the present invention.

That is, the present invention is a positive resist composition containing, as a radiation-sensitive compound and an alkali-soluble resin, a novolak resin obtained by condensing a compound of the following general formula (I) with an aldehyde.

[0007]

[Case 2]

(In the formula, R1 to R9 are each independently an alkyl group, a hydrogen atom, a halogen atom, or an -OH group. However, at least one of R1 to R9 is -OH
group, and at least two of the o-position and p-position with respect to the -OH group are hydrogen atoms. )

[0009] The positive resist composition of the present invention will be described in more detail below.As for the radiation-sensitive compound, a quinone diazide compound or the like is used. This quinonediazide compound can be obtained by a known method, for example, by condensing 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, 2,3,4-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-trihydroxybenzophenone, Trihydroxybenzophenones such as 3,3',4-trihydroxybenzophenone and 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 tetrahydroxybenzophenone, 2,2',3,4,
4'-pentahydroxybenzophenone, 2,2',3
, 4,5'-pentahydroxybenzophenone, 2,2
',3,3',4-pentahydroxybenzophenone,
Pentahydroxybenzophenones such as 2,3,3',4,5'-pentahydroxybenzophenone, 2,3
, 3',4,4',5'-hexahydroxybenzophenone, 2,2',3,3',4,5'-hexahydroxybenzophenones such as hexahydroxybenzophenone,

0010

[Chemical formula 3]

(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 are hydrogen atoms, alkyl groups,
Represents an alkenyl group, a cyclohexyl group or an aryl group. ), gallic acid alkyl esters, etc. are exemplified.

The resin used in the present invention is compound (I)
is obtained by condensing with aldehydes in the presence of an acid catalyst.

[0013] The aldehydes used here are:
For example, formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, glutaraldehyde, glyoxal, o- Examples include methylbenzaldehyde and p-methylbenzaldehyde, and among these compounds, formaldehyde is particularly preferred because it is easily available industrially. These aldehydes can be used alone or in combination of two or more.

The addition condensation reaction of compound (I) with aldehydes is carried out according to a conventional method. The reaction is usually 60
It is carried out at ~120°C 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.

Regarding the molecular weight of the resin used in the present invention, gel permeation chromatography (
The polystyrene equivalent weight average molecular weight (MW) determined by GPC (hereinafter referred to as GPC) is suitably 2,000 to 50,000, more preferably 3,000 to 30,000.

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 7 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),

[0019]

[C4]

[0020] etc. are exemplified. These may be used alone or in combination.

A positive resist solution is prepared by mixing and dissolving a radiation-sensitive compound and an alkali-soluble resin in a solvent. The ratio of the alkali-soluble resin to the quinonediazide compound is preferably in the range of 1:1 to 6:1 by weight.

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, xylene, ethyl lactate, propylene glycol monoethyl ether acetate, and the like. The amount of solvent is
When using ethyl cellosolve acetate as a solvent, 30~
80% (solvent amount weight %). 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.

[0023]

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.

Synthesis Example 1 In a four-neck flask with an internal volume of 300 ml, 53.6 g of the compound represented by the following formula (1) (p-OST cyclic dimer, manufactured by Mitsui Toatsu) and 50 g of ethyl cellosolve acetate were placed. 4g of 5% oxalic acid and 6.08g of 5% oxalic acid were charged, the temperature was raised to 80°C, and 13.0g of 37% formalin was added dropwise from the dropping funnel over 60 minutes while stirring. Thereafter, the mixture was stirred at 110°C for 10 hours. Thereafter, the mixture was neutralized, washed, and dehydrated to obtain a solution of novolak resin in ethyl cellosolve acetate. This was designated as resin A. GPC of resin A
The weight average molecular weight (polystyrene equivalent) measured with
It was 00.

[0025]

[C5]

Examples and Comparative Examples The resin and the quinonediazide compound were dissolved in 48 parts by weight of ethyl cellosolve acetate in the composition shown in Table 1. This prepared solution was filtered through a 0.2 μm Teflon filter to prepare a resist solution. 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 (Nikon NSR 1) having an exposure wavelength of 436 nm (g-line).
505G3C NA=0.42), and 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 determined by observing with M. The results are shown in Table 1.

[0028] Table 1

1) Novolac resin B: Weight average obtained by reacting under reflux using an oxalic acid catalyst at a molar ratio of metacresol/paracresol=70/30 and cresol/formalin=1/0.8. Novolak resin with a molecular weight of 12,000 (polystyrene equivalent). Novolak resin C: Weight average molecular weight 7000 (polystyrene equivalent) obtained by reacting under reflux using an oxalic acid catalyst at a molar ratio of meta-cresol/para-cresol = 60/40 and cresol/formalin = 1/0.8. ) novolak resin. 2) Quinonediazide Compound D: A condensate of naphthoquinone-(1,2)-diazide-(2)-5-sulfonic acid chloride and the following compound. (Reaction molar ratio 2.4)

[0030]

[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.

[0032]

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. Further, the composition of the present invention is useful as a resist composition for KrF excimer laser.

Claims (1)

[Claims] 1. A positive resist composition containing an alkali-soluble resin obtained by condensing a compound represented by the following general formula (I) with an aldehyde and a radiation-sensitive compound. [Formula 1] (wherein R1 to R9 are each independently an alkyl group,
It is a hydrogen atom, a halogen atom, or an -OH group. However, R
At least one of 1 to R9 is an -OH group,
At least two of the o-position and p-position with respect to the -OH group
is the hydrogen atom. )