Method of using polysilane positive photoresist materials

Claim 1

A method of photopatterning a positive image onto a substrate coated with a polysilane, comprising irradiating the coated substrate with actinic radiation forming a pattern of said positive image on the substrate, whereby the portions of the polysilane coating on which said radiation impinges are photodepolymerized to form products which volatilize and whereby said substrate becomes uncoated in the pattern of said positive image, wherein said polysilane is a homopolymer which is substantially free of low molecular weight oligomers or cyclic materials and which comprises recurring units of --Si(X)(Y)--, wherein X and Y together have 4 to 13 carbon atoms, and X and Y each independently is hydrogen, alkyl, cycloalkyl, substituted phenyl, 1- or 2-naphthyl, or phenylalkyl, or togehter X and Y are an alkylene group forming a ring with the adjoining Si atom, wherein X and Y groups which are not H can be substituted by one of C 1-6 -alkoxy, mono- or di(C 1-3 -alkyl)amino, C 2-6 -alkanoyl or the corresponding C 2-3 -ketal thereof, C 1-6 -alkyl, --NH 2 or --OH; with the proviso that only one of X and Y can be a substituted phenyl, and wherein, as a result of the selection of X and Y, said polysilane has sufficient photosensitivity to depolymerize upon exposure to actinic radiation, forming products which volatilize; or wherein said polysilane is a copolymer comprising recurring units of --Si(X)(Y)--, and Si(A)(B)--, Si(X)(Y)-- being different from Si(A)(B)--, wherein X and Y together have 1 to 13 carbon atoms, and X and Y each independently is hydrogen, alkyl, cycloalkyl, phenyl, alkylphenyl, or phenylalkyl, with the proviso that only one of X and Y contains a phenyl moiety, or together X and Y are an alkylene group forming a ring with the adjoining Si atom, and wherein A and B together have 3 to 13 carbon atoms, and A and B each independently is alkyl, 1- or 2-naphthyl, or cycloalkyl, wherein X, Y, A, or B groups which are not H can be substituted by one of C 1-6 -alkoxy, mono- or di-(C 1-3 -alkyl)amino, C 2-6 -alkanoyl or the corresponding C 2-3 -ketal thereof, C 1-6 -alkyl, --NH 2 , or --OH; with the proviso (a) that when one of A and B is ethyl, the other is not methyl or ethyl, and (b) that when one of A and B is n-propyl and the other is methyl, X and Y are not both methyl, wherein A and B are substituents imparting sufficient steric hindrance to the copolymer that it photodepolymerizes upon exposure to actinic radiation, and wherein X and Y are substituents of sufficiently low weight that the products of said photodepolymerization volatilize at the instantaneous temperature of the depolymerizing polymer during irradiation; and wherein said substituents in homo- or copolymers are such that the polymer undergoes substantially no self-crosslinking upon exposure to actinic radiation.

Claim 2

A method of photopatterning a positive image onto a substrate coated with a polysilane, comprising irradiating the coated substrate with actinic radiation forming a pattern of said positive image on the substrate, whereby the portions of the polysilane coating on which said radiation impinges are photodepolymerized to form products which volatilize and whereby said substrate becomes uncoated in the pattern of said positive image, wherein said polysilane is a homopolymer which is substantially free of low molecular weight oligomers or cyclic materials and which comprises recurring units of --Si(X)(Y)--, wherein X and Y together have 4 to 13 carbon atoms, and X and Y each independently is hydrogen, alkyl, cycloalkyl, substituted phenyl, 1- or 2-naphthyl, or phenylalkyl, or togehter X and Y are an alkylene group forming a ring with the adjoining Si atom, wherein X and Y groups which are not H can be substituted by one of C 1-6 -alkoxy, mono- or di(C 1-3 -alkyl)amino, C 2-6 -alkanoyl or the corresponding C 2-3 -ketal thereof, C 1-6 -alkyl, --NH 2 or --OH; with the proviso that only one of X and Y can be a substituted phenyl, and wherein, as a result of the selection of X and Y, said polysilane has sufficient photosensitivity to depolymerize upon exposure to actinic radiation, forming products which volatilize; or wherein said polysilane is a copolymer comprising recurring units of --Si(X)(Y)--, and Si(A)(B)--, Si(X)(Y)-- being different from Si(A)(B)--, wherein X and Y together have 1 to 13 carbon atoms, and X and Y each independently is hydrogen, alkyl, cycloalkyl, phenyl, alkylphenyl, or phenylalkyl, with the proviso that only one of X and Y contains a phenyl moiety, or together X and Y are an alkylene group forming a ring with the adjoining Si atom, and wherein A and B together have 3 to 13 carbon atoms, and A and B each independently is alkyl, 1- or 2-naphthyl, or cycloalkyl, wherein X, Y, A, or B groups which are not H can be substituted by one of C 1-6 -alkoxy, mono- or di-(C 1-3 -alkyl)amino, C 2-6 -alkanoyl or the corresponding C 2-3 -ketal thereof, C 1-6 -alkyl, --NH 2 , or --OH; with the proviso (a) that when one of A and B is ethyl, the other is not methyl or ethyl, and (b) that when one of A and B is n-propyl and the other is methyl, X and Y are not both methyl, wherein A and B are substituents imparting sufficient steric hindrance to the copolymer that it photodepolymerizes upon exposure to actinic radiation, and wherein X and Y are substituents of sufficiently low weight that the products of said photodepolymerization volatilize at the instantaneous temperature of the depolymerizing polymer during irradiation; and wherein said substituents in homo- or copolymers are such that the polymer undergoes substantially no self-crosslinking upon exposure to actinic radiation.