JPS6425475A - Mos type semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the breakdown strength of a polysilicon from decreasing by forming a 3-layer structure with a silicon nitride film between high melting point metal or its silicide and a polysilicon in contact with a gate oxide film, and forming a polysilicon on the sidewall of a gate for connecting therebetween. CONSTITUTION:A main gate 31 made of polysilicon 3, Si3N4 film 4 and a TiSi2 film 5 is formed through a first gate oxide film 21 on a P-type Si substrate 1, and the end of the polysilicon 3 is brought into contact with a sub gate 32 of polysilicon except that the lower part is partly covered with an oxide film 23. The gate 32 is disposed through a second gate oxide film 22 on low concentration source, drain 61, 72 to electrically connect the film 5 to the polysilicon Si3. That is, the gate 32 is of a conductive path for propagating an electric signal applied externally to the film 5 of the main gate to the polysilicon Si3 of the lower layer, and of a gate electrode for controlling the surface state of an N<-> type region.