Etching resistance of protein-based photoresist layers

Abstract

Etch resistance of protein-based resist compositions can be improved by treatment of the resist coatings with oxidizing salts prior to exposure of the resist coating to etchant solutions. For example, protein-based, film forming compositions comprising casein, fish glue or albumin can be hardened by the treatment of oxidizing salts (such as chlorates, chlorites, perchlorates, bromates, iodates, periodates, perbromates, and hypochlorite). These salts can be used to harden the protein-based film-forming compositions without environmental damage by appropriate selection of the cation (e.g., sodium, lithium, potassium, calcium, ammonium, organic cations, and the like). Etch resistance is improved such that ferric chloride or other acidic etchant solutions can be used in etching the metal surface or substrate containing the casein-based photoresist. In addition to this benefit, reduced burn-in temperatures may be used to harden the pattern, and the resist displays improved durability in rinse-dry cycles during the etching process.

Dependencies are inferred from the claim text.