JPS5685840A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To readily obtain a fine multilayer wire having no shortcircuit by filling the overhang of an interlayer insulating film with a material insulated by oxidation, oxidizing the material thereby eliminating defects and forming a second wire thereon. CONSTITUTION:When a field oxide film 102, a gate oxide film 106P and an addition polysilicon gate electrode 107 are selectively formed on a P type Si substrate 101, are thereafter wet oxidized and oxide films 108 and 109 are thus formed thereon, an overhang 108 is formed. Then, polysilicon 110 is accumulated thereon by a CVD process, the lower portion of the overhang 108 is thus buried, and P is added thereto. Subsequently, the entire surface plasma etched, and P-added polysilicon 110' is selectively retained under the overhang 108. When it is again wet oxidized, the film 110' is converted into a thick oxide film 111, and the overhang can be thus eliminated. Thereafter, phosphor-added polysilicon electrode 112 of second layer is formed. With this configuration the conventional excessively etching step due to the overhang can be eliminated, a shortcircuit between the wires can be prevented, and a semiconductor device having a high density and fine wire can be formed. Further, a thick oxide film 111 is interposed, thereby remarkably improving the the insulation withstand voltage.