JPH04362645A - Positive type resist composition - Google Patents

Abstract

PURPOSE:To provide a positive type resist compsn. having high gamma, fine profile and excellent appliability. CONSTITUTION:The positive type resist compsn. contains a quinonediazido compd., an alkali-soluble resin, an org. solvent (A) having 1-24 rate of evaporation calculated by a weight method on the basis of 100 rate of evaporation of n-butyl acetate and an org. solvent (B) having 25-150 rate of evaporation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist composition having a high γ value and an excellent profile.

0002

[Prior Art] A composition consisting of a compound having a quinonediazide group and an alkali-soluble resin 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. 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. As a result, even positive resists are required to have better resolution (higher γ value). However, in resist materials made of quinonediazide compounds and alkali-soluble resins, there has been a limit to the improvement of the γ value with conventional combinations of materials.

For example, increasing the amount of the quinonediazide compound may be considered to improve the γ value. However, increasing the amount of the quinonediazide compound has serious drawbacks such as a decrease in sensitivity and an increase in development residue. Therefore, there was a limit to the improvement of the γ value.

[0005]

[Problems to be Solved by the Invention] The object of the present invention is to maintain various performances such as heat resistance, resolution, sensitivity, and coatability.
The present invention aims to provide a positive resist composition with a high γ value and an excellent profile.

[0006]

[Means for Solving the Problems] The present inventors have developed heat resistance,
With the aim of providing a resist with a high gamma value and a rectangular profile while maintaining performance such as resolution, sensitivity, and coatability, as a result of extensive research, we developed a method using a gravimetric method using n-butyl acetate as 100. We have discovered that the objective can be achieved by using a mixed organic solvent containing an organic solvent (A) whose evaporation rate is 1 to 24 and an organic solvent (B) whose evaporation rate is 25 to 150. This led to the invention.

The positive resist composition of the present invention comprises a quinonediazide compound, an alkali-soluble resin and an acetic acid n-
The evaporation rate determined by gravimetric method with butyl as 100 is 1~
The same evaporation rate as the organic solvent (A) which is 24 is 25 to 150
It contains a mixed organic solvent containing an organic solvent (B). The quinonediazide-based compound is not particularly limited, but for example, 1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4
-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester, and the like. These esters can be obtained by a known method, for example, by condensing 1,2-naphthoquinonediazide sulfonic acid or benzoquinonediazide sulfonic acid with a compound having a hydroxyl group in the presence of a weak alkali.

[0008] 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, 3,3',4-trihydroxybenzophenone, 3, Trihydroxybenzophenones such as 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
Tetrahydroxybenzophenones such as ',5,5'-tetrahydroxybenzophenone, 2,2',3,4
, 4'-pentahydroxybenzophenone, 2,2',
3,4,5'-pentahydroxybenzophenone, 2,
Pentahydroxybenzophenones such as 2',3,3',4-pentahydroxybenzophenone, 2,3,3',4,5'-pentahydroxybenzophenone, 2,
Hexahydroxybenzophenones such as 3,3',4,4',5'-hexahydroxybenzophenone, 2,2',3,3',4,5'-hexahydroxybenzophenone, gallic acid alkyl ester,

[0009]

[Chemical formula 1]

(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. R1 to R5 each independently represent a hydrogen atom, an alkyl group, oxyflavans such as alkenyl group, cyclohexyl group, or aryl group (provided that either R4 or R5 represents an alkyl group, alkenyl group, cyclohexyl group, or aryl group), JP-A-2-2
Examples include the phenol compound represented by the general formula (I) described in No. 69351.

The alkali-soluble resin used in the composition of the present invention is not particularly limited, but examples thereof include polyvinylphenol and novolak resin. Novolac resins include, for example, phenol, o-cresol,
m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, 2
, 3,5-trimethylphenol, 4-t-butylphenol, 2-t-butylphenol, 3-t-butylphenol, 3-ethylphenol, 2-ethylphenol, 4-ethylphenol, 3-methyl-6-t-butylphenol , 4-methyl-2-t-butylphenol, 2-naphthol, 1,3-dihydroxynaphthalene,
Examples include resins in which phenols such as 1,7-dihydroxynaphthalene and 1,5-dihydroxynaphthalene are condensed alone or in combination with aldehydes in a conventional manner.

Examples of aldehydes include formaldehyde aqueous solution (formalin) and paraformaldehyde. In particular, 37% formalin is industrially mass-produced and is convenient.

The weight ratio of these quinonediazide compounds to the alkali-soluble resin is preferably in the range of 1:1 to 1:7.

[0014] The organic solvent (A
) has an evaporation rate of 1 to 24 determined by the gravimetric method with n-butyl acetate as 100. The evaporation rate of the solvent here refers to the evaporation rate of acetic acid n
-Butyl is set as 100, and is determined by the following formula. Moreover, the organic solvent (B) used in the present invention has an evaporation rate of 25 to 150 as described above.

Examples of the organic solvent (A) include γ-butyrolactone, cyclohexanol, diacetone alcohol, butyl cellosolve, ethyl lactate, butyl lactate, and the like. One type or a mixture of two or more types of these may be used.

Further, as the organic solvent (B), cyclohexanone, methyl lactate, methyl diacetone alcohol,
Examples include 2-heptanone, n-amyl acetate, diisopropyl ketone, and n-butyl acetate. One type or a mixture of two or more types of these may be used.

The amount of the solvent used in the present invention is not particularly limited as long as it is possible to form a uniform coating film on the wafer without pinholes or uneven coating, but usually the solid content, that is, the quinonediazide compound A resist composition is prepared so that the concentration of the alkali-soluble resin is in the range of 3 to 50% by weight.

[0018] The weight ratio of the organic solvent (A) to the total amount of solvent is preferably in the range of 2% to 80%, particularly 5%.
to 75% is preferable in terms of γ value, profile, and coatability. If the ratio of the organic solvent (A) in all solvents becomes too small, the effect of improving the γ value and profile becomes small. Further, if the proportion of the organic solvent (A) in the total solvent becomes too large, problems will arise in coating properties, which is not preferable.

The composition of the present invention may also contain sensitizers, other additive resins, surfactants, etc. as long as they do not impair the effects of the present invention.
Stabilizers, dyes to make the formed image more visible, and various other additives commonly used in the art can be added.

[0020]

[Examples] The present invention will be specifically explained below using Examples, but the present invention is not limited thereto.

Examples and Comparative Examples A novolac resin and a quinonediazide compound having the compositions shown in Table 1 were dissolved in 45 parts of a solvent. This prepared solution is 0
．． A resist solution was prepared by filtering through a 2 μm Teflon filter. This was coated onto a silicon wafer that had been cleaned using a conventional method using a spin coating machine to form a coating film of 1.3 μm.
It was applied thickly. Next, this silicon wafer was heated to 100℃.
Bake for 60 seconds on a hot plate. Next, this wafer was exposed to a reduction projection exposure machine (Hitachi LD-5010i NA=0.
40), and the exposure amount was changed stepwise. This wafer was subjected to a post-exposure bake (PEB) for 60 seconds on a hot plate at 110° C., and then developed for 1 minute using SOPD, a developer manufactured by Sumitomo Chemical, to obtain a positive pattern.

The resolution was evaluated using an SEM (scanning electron microscope) to determine the dimensions of the line and space pattern that can be separated without film loss at an exposure dose that makes the 0.8 μm line and space pattern 1:1. The profile was obtained by observing the cross-sectional shape of a 0.8 μm line-and-space pattern using an SEM at this exposure amount. γ value and sensitivity (Eth)
For each, plot the normalized film thickness (=residual film thickness/initial film thickness) against the logarithm of the exposure dose, find the slope θ, and calculate t
An θ was defined as the γ value, and the exposure amount at which the normalized film thickness became 0 was defined as the sensitivity (Eth). Heat resistance was defined as the highest hot plate temperature at which the 3 μm line and space pattern did not deform when the patterned wafer was heated on a hot plate for 3 minutes. Deformation of the pattern was observed using SEM. The coating properties were evaluated based on the non-uniformity of the film when the film thickness was 2 μm. 〇 indicates good quality, and × indicates poor quality.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028]

[Table 6]

1) Novolak resin Weight average molecular weight 6000 (polystyrene equivalent) obtained by reacting using an oxalic acid catalyst at a charging molar ratio of meta-cresol/para-cresol = 4/6 and formalin/cresol = 0.8/1. ) novolak resin. 2) Quinonediazide compound A condensation reaction product of naphthoquinone-(1,2)-diazide-(2)-5-sulfonic acid chloride and a compound represented by the following formula. (Reaction molar ratio 2.7:1)

[0030]

[Case 2]

3) Evaporation rate Evaporation rate determined by gravimetric method with n-butyl acetate as 100. 4) Weight ratio to total solvent content (%)

[0032]

Effects of the Invention The positive resist composition of the present invention has no deterioration in sensitivity, heat resistance, resolution, or coatability, and is particularly excellent in γ value and profile.

Claims (2)

[Claims] Claim 1: The quinonediazide compound, the alkali-soluble resin, and n-butyl acetate have an evaporation rate of 25 to 150 as determined by the gravimetric method of 1 to 24. A positive resist composition containing a mixed organic solvent including an organic solvent (B). 2. The positive resist composition according to claim 1, wherein the weight ratio of the organic solvent (A) to the total amount of solvent is between 2% and 80%.