Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2001-04-17
2003-10-21
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S190000, C430S191000, C430S192000, C430S193000, C430S270100, C430S326000, C430S330000
Reexamination Certificate
active
06635400
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resist composition which provides high sensitivity and high resolution when exposed to ultraviolet light having a wavelength of at least 300 nm. The invention also relates to a patterning process using the resist composition.
2. Prior Art
The thick-film type (3 to 50 &mgr;m) resist films employed to form circuit patterns on a substrate by techniques that involve plating are required to have a good pattern profile with vertical walls and a high plating resistance. A resist patterning process which patterns novolac-type resist compositions with an aligner that employs g- or i-line as the light source is commonly used to achieve this end. However, increased light absorption by the resist film on account of its large thickness lowers sensitivity, which in turn reduces throughput during high-volume production.
The drive in recent years toward smaller geometries in circuit patterns has created a need for higher resolutions, yet light absorption by prior-art resist films such as the above has imposed practical limits on the resolution and pattern shape that are achievable.
Also, when novolac-type resist compositions are used for patterning as a plating base, footing often arises at the bottom of the patterned resist and can have an undesirable effect on formation of a metal layer following patterning of the resist. A need has thus been felt for a thick-film type (3 to 50 &mgr;m) resist composition which can be patterned in the aligners commonly used today that employ as the light source ultraviolet light such as g- or i-line, which has a high resolution and high sensitivity, and which moreover has a high plating resistance.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a resist composition having a high resolution and a high sensitivity that is suitable for achieving metal film circuit patterns of small geometries. Another object of the invention is to provide a patterning process which uses the resist composition.
We have found that resist compositions comprising (A) an alkali-insoluble or substantially insoluble polymer having acidic functional groups protected with acid labile groups, which polymer becomes alkali-soluble upon elimination of the acid labile groups, (B) a photoacid generator and (C) a 1,2-naphthoquinonediazidosulfonyl group-bearing compound, and comprising also, if necessary, (D) a basic compound and (E) a dissolution promoter, have a high resolution and high sensitivity under UV exposure. On NiFe film substrates, in particular, such resist compositions reduce the problem of footing and make it possible to achieve both a good pattern profile with perpendicular sidewalls and a high resolution.
Especially, the above resist composition is effective as a thick-film type, and imparts a resist film having a high resolution and sensitivity, and a high plating resistance with a good adhesion. In recent years, a highly dense pattern is required for a circuit pattern formed by using a resist composition and a plating technique. Such a highly dense pattern can be formed by narrowing the width of lines in a resist pattern. For ensuring the circuit capacity to the narrow circuit lines, it is necessary to increase the thickness of the circuit lines obtained by plating. For increasing the thickness of the circuit lines, it is required to form a resist film having a high thickness. The inventive resist composition can fully satisfy the above requirements.
Accordingly, the invention provides a resist composition for exposure to ultraviolet light at a wavelength of at least 300 nm, comprising:
(A) an alkali-insoluble or substantially insoluble polymer having acidic functional groups protected with acid labile groups, which polymer becomes alkali-soluble upon elimination of the acid labile groups;
(B) a photoacid generator; and
(C) a 1,2-naphthoquinonediazidosulfonyl group-bearing compound.
Preferably, the polymer (A) contains recurring units of general formula (1) below and has a weight-average molecular weight of 3,000 to 300,000.
Herein R
1
is hydrogen or methyl, R
2
is a straight, branched or cyclic alkyl of 1 to 8 carbons, x is 0 or a positive integer, and y is a positive integer, such that x+y≦5. In the recurring units, the hydrogen atoms on some of the phenolic hydroxyl groups have been substituted with at least one type of acid labile group, and the amount of acid labile groups averages more than 0 mol %, but not more than 80 mol %, of all the phenolic hydroxyl group hydrogens in formula (1).
The photoacid generator (B) is preferably an oxime sulfonate compound.
The resist composition of the invention may further comprise (D) a basic compound and/or (E) a dissolution promoter.
The dissolution promoter (E) includes a low polynuclear compound of general formula (2) below having phenolic hydroxyl groups and from 2 to 20 benzene rings, such that the ratio in the number of phenolic hydroxyl groups to the number of benzene rings is from 0.5 to 2.5.
In formula (2), R
3
to R
8
are each independently hydrogen, methyl, or a group of formula (3) or (4) below. The letter m is an integer from 0 to 2 and the letter n is an integer from 0 to 2, with the proviso that m is 1 or 2 if n is 0. When m is 1 and n is 0, A is hydrogen, methyl or a group of formula (3). When m is 2 and n is 0, one A moiety is methylene or a group of formula (5) below and the other A moiety is hydrogen, methyl or a group of formula (3). When n is 1, A is methylene or a group of formula (5). When m is 1 and n is 2, A is methine or a group of formula (6) below. When m is 2 and n is 2, one A moiety is methylene or a group of formula (5) and the other A moiety is methine or a group of formula (6).
In formulas (3) to (6), p, q, r, s, t, u and v are each an integer from 0 to 3, such that p+q≦5, r+s≦4 and u+v≦3.
In a second aspect, the invention provides a patterning process comprising the steps of (i) applying the above-described resist composition onto a substrate; (ii) heat treating the applied resist composition, then exposing it through a photomask to ultraviolet light having a wavelength of at least 300 nm; and (iii) heat treating the exposed resist composition if necessary, then developing it with a developer. In this case, the thickness of the resist film formed on the substrate is preferably 3 to 50 &mgr;m.
DETAILED DESCRIPTION OF THE INVENTION
The resist composition of the invention is based on (A) a polymer or high molecular weight compound which is insoluble or substantially insoluble in alkali, has acidic functional groups protected by acid labile groups, and becomes alkali-soluble when the acid labile groups are eliminated. The polymer typically has a weight-average molecular weight of 3,000 to 300,000, and preferably 3,000 to 30,000, and contains recurring units of general formula (1) below.
In formula (1), R
1
is hydrogen or methyl, and R
2
is a straight, branched or cyclic alkyl of 1 to 8 carbons. The letter x is 0 or a positive integer and y is a positive integer, such that x+y≦5. The hydrogen atoms on some of the phenolic hydroxyl groups in the recurring units of formula (1) have been replaced with one or more type of acid labile group. The amount of acid labile groups averages more than 0 mol %, but not more than 80 mol %, and preferably from 10 to 50 mol %, of all the phenolic hydroxyl group hydrogens in formula (1).
Any of various acid labile groups may be selected for use in the polymer. Exemplary acid labile groups include groups of the following general formulas (7) and (8), tertiary alkyl groups, trialkylsilyl groups, and ketoalkyl groups.
In formula (7), R
9
and R
10
are each independently a hydrogen or a straight or branched alkyl of 1 to 6 carbons, and R
11
is a straight, branched or cyclic alkyl of 1 to 10 carbons. Alternatively, a pair of R
9
and R
10
, a pair of R
9
and R
11
, or a pair of R
10
and R
11
may together form a ring, in which case R
9
, R
10
and R
11
are each independently a straight or branched alkylen
Hirano Yoshinori
Kato Hideto
Nishikawa Kazuhiro
Takemura Katsuya
Chu John S.
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
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