Effects of positive resist developer processing on plasma etching characteristics are described. The etch rate of polycrystalline silicon was measured with and without positive resist developer processing using a barrel‐type plasma etching system and as an etching gas. A considerably accelerated etch rate was observed for polycrystalline silicon with residues of positive resist developer. The acceleration is attributed to residues adhered on the surface, which act as catalytic agents. The residual also accelerates the etch rate of polycrystalline silicon.