Adhesive sheets for sticking wafers thereto

Claim 2

A structure as claimed in claim 1 wherein said base sheet is polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polybutene, polybutadiene, polyurethane, polymethylpentene, ethylene-vinyl acetate copolymer, cross-linked polyolefin or ethylene-methacrylic acid copolymer.

Claim 3

A structure as claimed in either of claims 1 and 2 wherein said adhesive comprises (A) one or two or more nonionic surface active agents having ethylene oxide groups as their hydrophilic components, and (B) one or two or more copolymers composed of 40-99mol% of one or two or more recurring structural units represented by the following formula (I) and 60-1mol% of one or two or more recurring structural units represented by the following formula (II), said copolymer or copolymers being cross-linked, if necessary, with a crosslinker such as zinc acetate or magnesium chloride which reacts with the carboxyl group of the component (B); wherein R₁ is hydrogen, chlorine or lower alkyl and R₂ is hydrogen, chlorine, lower alkyl or a group -OCOR₃, -OR₃, -COOR₃, -CN, -CONH₂, -CONHCH₂OH, -CH₂OH, -C₂H₄OH, -OH, or in which R₃ is alkyl of 1-8 carbon atoms; wherein X, Y and Z, which may be the same or different are each hydrogen, chlorine, lower alkyl or the group of -COOR₄, -COOH, -CH₂COOH or -CH₂COOR₄, in which R₄ is an alkyl of 1-4 carbon atoms.

Claim 4

A structure as claimed in claim 3 wherein the nonionic surface active agents are (i)   HO(C₂H₄O) a (C₃H₆O) b (C₂H₄O) c H wherein a, b and c are each an integer of 20-80 (ii)   RA(C₂H₄O) e H wherein R is alkyl of 6-18 carbon atoms, alkylphenyl having an alkyl moiety of 4-20 carbon atoms or the group A is oxygen, sulfur or the group -COO, -CONH, CON(C₂H₄O) e H, PO₄H or PO₄(C₂H₄O) e H, the symbols e, which may be the same or different, each representing an integer of 2-80, or wherein R is an alkyl of 6-18 carbon atoms, and x, y and z are each an integer of 2-40.

Claim 5

A structure as claimed in either of claims 1 and 2 wherein said adhesive comprises (A) a water-soluble polymer derived from (meth)acrylic acid, (meth)acrylic ester, vinylpyrrolidone, acrylamide, dimethylaminoethyl (meth)acrylate, diethylamino(meth)acrylate, vinyl methyl ether or a (meth)acrylic ester monomer represented by the formula wherein R¹ is hydrogen or methyl, R² is an alkylene of 2-4 carbon atoms, R³ is an alkyl of 1 or more carbon atoms, and n is an integer of 1 or more and (B) a (meth)acrylic ester monomer which gives a water-swelling polymer.

Claim 6

A structure as claimed in claim 5 wherein the (meth)acrylic ester monomer (B) is a (meth)acrylic ester monomer, dimethylaminoethyl(meth)acrylate or diethylaminoethyl(meth)acrylate.

Claim 7

A structure as claimed in either of claims 1 and 2 wherein said adhesive comprises (A) a salt of a copolymer obtained by neutralizing the carboxyl group in a copolymer comprising 10-40 mol% of a carboxyl-containing monomer, 60-90 mol% of (meth)acrylic alkyl ester having an alkyl moiety of 4 or more carbon atoms and 0-20 mo.% of vinyl monomer other than the above-mentioned monomers and (B) a hydrophilic compound represented by the formula R₁O(R₂O) n R₃ wherein R₁ is an alkyl of 1-4 carbon atoms, R₂ is an alkylene of 2-4 carbon atoms, R₃ is hydrogen, an alkyl of 1-4 carbon atoms or acetyl, and n is an integer of 1-6.

Claim 8

Process for grinding the reverse side of a wafer said process comprising: i) forming a structure as claimed in any one of claims 1 to 7; ii) grinding the reverse side of said wafer with water spraying; iii) stripping off said adhesive sheet after completion of grinding; and, where necessary iv) removing any residual adhesive by water washing.