Patent ID: 7141177

Claim:
A method of etching a substrate, which comprises the steps of: forming a resist pattern on a substrate by use of a photoresist, applying a composition for forming an etching protection layer on the resist pattern formed, forming an etching protection layer insoluble in a developer containing water in the interface between the composition for forming an etching protection layer and the resist, removing unnecessary parts other than the etching protection layer of the composition for forming an etching protection layer by the water-containing developer, and etching the substrate by using, as a mask, the resist pattern having the etching protecticn layer thereon, wherein the above-described composition for forming an etching protection layer comprises at least one water-soluble or water-dispersible resin comprising a copolymer of at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, vinyl acetal, vinyl alcohol, ethylene imine, vinyl amine, allyl amine, methacyl amine and vinyl methyl ether and at least one monomer selected from the group consisting of a styrene derivative selected from the group consisting of hydroxystyrene, 4-methylstyrene, 4-ethylstyrene, p-isopropylstyrene, 4-butylstyrene, 4-hexylstyrene, 4-methoxystyrene, 4-ethoxystyrene, 4-propoxystyrene, 4-butoxystyrene, 4-butoxymethylstyrene, 4-butoxycarbonylstyrene, 2,5-dimethylstyrene, 2,4,5-trimethyistyrene, 4-phenylstyrene, 4-fluorostyrene, 2,5-difluorostyrene, 2,4-difluorostyrene, o-chlorostyrene, 4-acetylstyrene, 4-bezoylstyrene, 4-bromostyrene, aminostyrene, vinyl benzoic acid, vinyl benzoic esters and α-methylstyrene, a polycyclic aromatic vinyl compound, a heterocyclic vinyl compound; a crosslinking agent and water and/or a water-soluble organic solvent as a solvent.