Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-03-08
2004-05-18
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S325000, C430S326000, C430S905000, C430S909000, C430S910000, C430S914000, C525S219000, C525S222000, C525S223000, C525S227000, C525S241000
Reexamination Certificate
active
06737214
ABSTRACT:
This invention relates to a chemical amplification resist composition, especially of the positive acting type, having a high sensitivity and resolution, and suitable as a micropatterning material for VLSI fabrication.
BACKGROUND OF THE INVENTION
While a number of recent efforts are being made to achieve a finer pattern rule in the drive for higher integration and operating speeds in LSI devices, deep-ultraviolet, EB, EUV and x-ray lithographic techniques are thought to hold particular promise as the next generation in microfabrication technology. Deep-UV lithography is capable of achieving a minimum feature size of 0.24 &mgr;m or less, and can form patterns with sidewalls that are nearly perpendicular to the substrate, when a resist having low light absorption is used.
Recently developed acid-catalyzed chemically amplified positive resists, such as those described in JP-B 2-27660, JP-A 63-27829, U.S. Pat. No. 4,491,628 and U.S. Pat. No. 5,310,619, utilize a high-intensity KrF excimer laser as the deep-UV light source. These resists, with their excellent properties such as high sensitivity, high resolution, and good dry etching resistance, are especially promising for deep-UV lithography.
Such chemically amplified positive resists include two-component systems comprising a base polymer and a photoacid generator, and three-component systems comprising a base polymer, a photoacid generator, and a dissolution regulator having acid labile groups.
For example, JP-A 62-115440 describes a resist comprising poly-4-tert-butoxystyrene and a photoacid generator. JP-A 3-223858 describes a similar two-component resist comprising a resin bearing tert-butoxy groups within the molecule, in combination with a photoacid generator. JP-A 4-211258 describes a two-component resist which is comprised of polyhydroxystyrene bearing methyl, isopropyl, tert-butyl, tetrahydropyranyl, and trimethylsilyl groups, together with a photoacid generator. JP-A 6-100488 discloses a resist comprised of a polydihydroxystyrene derivative, such as poly[3,4-bis(2-tetrahydropyranyloxy)styrene], poly[3,4-bis(tert-butoxycarbonyloxy)styrene] or poly[3,5-bis(2-tetrahydropyranyloxy)styrene], and a photoacid generator. These resists, however, have the drawbacks of slimming of a pattern film after development with an aqueous base solution and poor resistance to dry etching.
Also known in the art are resist compositions using copolymers of hydroxystyrene with (meth)acrylate for achieving a higher transparency and improving the adhesion to the substrate as disclosed in JP-A 8-101509 and 8-146610. The resist compositions of this type suffer from low heat resistance, partial pattern collapse, and pattern shape footing.
SUMMARY OF THE INVENTION
An object of the invention is to provide a chemical amplification type resist composition which has a higher sensitivity, resolution, dry etching resistance and process adaptability than conventional resist compositions, and is improved in the slimming of a pattern film after development with an aqueous base solution.
The invention provides a chemical amplification type resist composition comprising a polymeric mixture of a polymer comprising recurring units of the general formula (1) and having a weight average molecular weight of 1,000 to 500,000 and a polymer comprising recurring units of the general formula (2) and having a weight average molecular weight of 1,000 to 500,000. The combined use of the polymers of formulas (1) and (2) gives an effective base resin for a chemical amplification positive resist composition. The chemical amplification positive resist composition comprising the polymeric mixture, a photoacid generator and an organic solvent has a high sensitivity, high resolution, dry etching resistance and process adaptability, and is improved in the slimming of a pattern film after development with an aqueous base solution. The composition is thus well suited for practical use and advantageously used in precise microfabrication, especially in VLSI manufacture.
Herein R is a hydroxyl group or a OR
3
group, R
1
is hydrogen or methyl, R
2
is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms, R
3
and R
4
each are an acid labile group, R
5
is methyl or ethyl, Z is a straight, branched or cyclic alkylene group of 1 to 10 carbon atoms, x is 0 or a positive integer, y is a positive integer, satisfying x+y≦5, m is 0 or a positive integer, n is a positive integer, satisfying m+n≦5, p, q, r and s each are 0 or a positive number, satisfying p+q+r+s=1.
Herein R
6
, R
7
and R
8
each are hydrogen or methyl, R
9
is methyl or ethyl, E is a straight, branched or cyclic alkylene group of 1 to 10 carbon atoms, R
10
is a straight, branched or cyclic alkyl group of 1 to 20 carbon atoms, which may contain an oxygen or sulfur atom, R
11
is a tertiary alkyl group of 1 to 20 carbon atoms, k is 0 or a positive integer of up to 5, t and w each are a positive number, u and v each are 0 or a positive number, either one of u and v is not equal to 0, satisfying t+u+v+w=1.
When the polymers of formulas (1) and (2) are formulated together in a resist composition, they cooperate to give greater advantages than compensating for their shortcomings. More particularly, when only the polymer of formula (1) is used, the resulting resist composition has the advantages of high sensitivity and resolution, but the disadvantages of poor dry etching resistance and considerable slimming of a pattern film after development with an aqueous base solution. On the other hand, when the polymer of formula (2) is used alone, the resulting resist composition has the advantages of good dry etching resistance and relatively suppressed slimming of a pattern film after development with an aqueous base solution, but the disadvantages of low sensitivity and pattern shape footing.
In contrast, formulating both the polymers of formulas (1) and (2) with other resist components results in a chemical amplification positive resist composition which has a higher sensitivity, resolution, dry etching resistance and process adaptability than the single use of each polymer, and forms a pattern film which undergoes a relatively small reduction of its thickness after development with an aqueous base solution.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Polymer
The chemical amplification type resist composition of the invention is characterized by comprising a polymeric mixture of a polymer comprising recurring units of the general formula (1) and having a weight average molecular weight of 1,000 to 500,000 and a polymer comprising recurring units of the general formula (2) and having a weight average molecular weight of 1,000 to 500,000.
In formula (1), R is a hydroxyl group or a OR
3
group, R
1
is hydrogen or methyl, R
2
is a straight, branched or cyclic alkyl group of 1 to 8 carbon atoms, R
3
and R
4
each are an acid labile group, R
5
is methyl or ethyl, Z is a straight, branched or cyclic alkylene group of 1 to 10 carbon atoms, x is 0 or a positive integer, y is a positive integer, satisfying x+y≦5, m is 0 or a positive integer, n is a positive integer, satisfying m+n≦5, p, q, r and s each are 0 or a positive number, satisfying p+q+r+s=1.
Examples of the straight, branched or cyclic alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl and cyclohexyl.
The acid labile groups represented by R
3
and R
4
are selected from a variety of such groups, preferably from among the groups of the following formulas (3) and (4), branched or cyclic, tertiary alkyl groups with 4 to 20 carbon atoms, trialkylsilyl groups whose alkyl groups each have 1 to 6 carbon atoms, and oxoalkyl groups of 4 to 20 carbon atoms. It is noted that the acid labile groups represented by R
3
and R
4
are different.
In formula (3), R
12
and R
13
are independently hydrogen or straight, branched or cyclic alkyl groups of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, for examp
Hirahara Kazuhiro
Kusaki Wataru
Seki Akihiro
Takeda Takanobu
Takemura Katsuya
Huff Mark F.
Lee Sin J.
Millen, Whtie, Zelano & Branigan, P.C.
Shin-Etsu Chemical Co. , Ltd.
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