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
2000-02-25
2001-11-20
Ashton, Rosemary (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
C430S914000, C430S920000, C430S927000
Reexamination Certificate
active
06319650
ABSTRACT:
FIELD OF INVENTION
The present invention relates to strong aqueous base developable photoresist composition and processes for forming lithographic patterns therewith.
BACKGROUND OF INVENTION
There is continuing effort in electronic industry to achieve higher circuit density in electronic devices. To archive higher degree of integration, new and improved lithographic tools and techniques have been developed which in turn demand new photoresists that could enhance the resolution of lithographic patterns. Aqueous base developable photoresist compositions which are formed through crosslinking have been disclosed in Reck et al., SPIE regional Technical Conference on Photopolymers, Ellenville, N.Y., 63 (1988) and in U.S. Pat. No. 5,034,304 and 5,204,225 to Feely. Such formulations were characterized by polymers having an aromatic moeity, like poly(hydroxystyrene) or novolak, which are susceptible to electrophilic aromatic substitution, and a crosslinking agent which can form a carbonium ion upon treatment with acid and a photoacid generator.
U.S. Pat. No. 4,810,601 to Allen et al. is concerned with formation of negative tone resist patterns by crosslinking an aromatic compound with monomeric or polymeric source of carbonium ions. Thus, diacetoxymethyl benzene and trisacetoxymesitylene were used with triphenylsulfonium hexafluoroantimonate to crosslink a poly(hydroxystyrene) matrix.
U.S. Pat. No. 5,296,332 to Sachdev and Japanese patents 2-15270 and 1-293339 to Kokai describe aqueous base deviopable resist composition comprising of a phenolic resin like poly(hydroxystyrene) or Novolak, a crossinkable agent which can form carbonium ion upon treatment with acid, and a photoacid generator.
SUMMARY OF THE INVENTION
A broad aspect of this invention is an aqueous base developable photoresist composition for generating subquarter of micrometer negative tone resist images on a substrate. Another aspect of this invention is a photoresist composition which is capable of being developed in higher concentrations of base developer than polyhydroxystyrene resist compositions to be compatable with those used in positive tone resist manufacturing and does not result in the formation of microbridges between the resist image on the substrate. The composition of this photoresist consists of (a) a film forming polymer methacrylate resin having pendant phenolic groups, (b) an acid catalyzable crosslinking agents selected from aminoplast family and more particularly from glycoluril derivatives (c) a radiation degradable acid generator to assist in crosslinking of the film former and crosslinker and (d) optionally an organic base to improve shelf life stability of the formulation. The phenolic polymer resins of the present invention are selected from the unmodified homopolymers of Poly 4-Hydroxyphenylethyl methacrylate of molecular weights between 68-8K number average molecular weight as shown in the formula
The crosslinking agents of this composition are selected from Glycouril derivatives shown in the formula:
in which R is an alkoxadical, preferably CH
20
CH
3
, and R1 and R2 can individually be selected from hydrogen, alkyl or aryl groups. The composition of the present invention also includes a radiation degradable acid generator.
The present invention also provides a method of using new resist composition for generating negative tone resist images on a substrate which comprises:
a) coating the substrate with a film comprising of a film forming polymer resin having phenolic functionality, an acid catalyzable crosslinking agent selected from glycoluril derivatives and a radiation degradable acid generator;
b) imagewise exposing the film with UV radiation to cause crosslinking in the exposed portion of the film;
c) baking the said substrate at elevated temperatures, and
d) developing film in an aqueous base developer.
The present compositions are sensitive to deep UV radiation. The resist speed can be adjusted by the ratio of the crosslinker to polymer resin, addition of an organic base.
REFERENCES:
patent: 4175972 (1979-11-01), Crivello
patent: 5853953 (1998-12-01), Georger, Jr.
patent: 6074801 (2000-06-01), Iwasa et al.
patent: 6087064 (2000-07-01), Lin et al.
patent: 6150068 (2000-11-01), Sato et al.
patent: 1030615 (1998-11-01), None
patent: 10306159 (1998-11-01), None
Derwent abstract of JP 10306159, Nov. 1998.*
CAPLUS online abstract of JP 10306159, Nov. 1998.
Afzali-Ardakani Ali
Gelorme Jeffrey Donald
Graham Teresita Ordonez
Kosbar Laura Louise
Ashton Rosemary
Beck Thomas A.
International Business Machines - Corporation
Morris Daniel P.
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