Method for the insulation of polysilicon film in semiconductor device

摘要

A method for insulating a polysilicon film in a semiconductor device is disclosed. The method comprises the steps of: forming a trench in a semiconductor covered with a first oxide film, a buffing polysilicon film and a nitride film in due order, with a mask pattern for forming the trench; coating the trench with an insulating film and filling the resulting trench with a polysilicon film for forming charge storage electrode; oxidizing the surface of the polysilicon to form a second oxide film on the polysilicon film; and implanting silicon atoms in the polysilicon film through the second oxide film to make a predetermined, upper portion of the polysilicon film be amorphous. The thickness difference of the oxide film formed on the polysilicon film of the trench is minimized by use of the buffing polysilicon film according to the present invention. In addition, ion implantation of silicon atom make a predetermined, upper portion of the polysilicon film of the trench be amorphous, resulting in the improvement of insulating characteristics of charge storage electrode formed in the trench. Consequently, the reliability for trench capacitor of semiconductor device is much enhanced, in accordance with the present invention.