Abstract: An etching composition for removing silicon is provided, which comprises: 1 to 5.5 wt % of a quaternary ammonium salt; 20 to 95.5 wt % of an alcohol amine compound; 1 to 40 wt % of an amide compound; and rest of water. In addition, a method for removing silicon using the aforesaid etching composition is also provided.

Abstract: The composition of an etchant is provided. The composition of the etchant includes about 0.1 to 13 wt % quaternary ammonium salt and about 45 to 90 wt % aprotic organic solvent. A method for forming a semiconductor device is provided. The method for forming the semiconductor device includes a step of removing a dummy gate by using an etchant with a composition that includes about 0.1 to 13 wt % quaternary ammonium salt and about 45 to 90 wt % aprotic organic solvent. A semiconductor device is provided. The semiconductor device includes a polycrystalline silicon component having an etched surface that was etched by an etchant with a composition that includes about 0.1 to 13 wt % quaternary ammonium salt and about 45 to 90 wt % aprotic organic solvent. The surface arithmetic mean height of the etched surface is 20 nm or less.