METHOD OF FORMING CONTACT PLUG IN SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method of forming a contact plug is to prevent an etching residue and impurities form being generated, thereby subsequent cleaning process being dispensed with, and to have no curved portion or step at a boundary of a contact plug and an insulation film. CONSTITUTION: A method of forming a contact plug comprises the steps of: forming an oxide film(8) on a first conductive layer and etching the oxide film to form the contact hole; forming a polysilicon film(9) on the resultant product thus obtained; and wet-etching the polysilicon film in aqueous ammonia solution until the surface of the oxide film being exposed. The aqueous ammonia solution is an aqueous solution in which ammonia solution having a composition of from 20 to 30 wt% and ultra-pure water are mixed at a ratio of from 1:5 to 1:10 by volume.