JPS6413770A - Mos type transistor - Google Patents

Abstract

PURPOSE:To obtain a MOS type transistor having excellent switching characteris tics by giving high mobility by forming a second semiconductor layer having a band gap equal to or wider than that of a first semiconductor layer on the interface between the first semiconductor layer and a thermal oxide film. CONSTITUTION:A second semiconductor layer 12 different from a semiconductor substrate is shaped between the semiconductor substrate and a gate oxide film in a MOS type transistor, and a gate oxide film 13 and a gate electrode 14 are formed onto the semiconductor layer 12 in succession. A material having a band gap equal to or larger than that of a first semiconductor layer 11 is used by reason of the increase of the lifetime of inversion layer carrier as the semiconductor layer 12. SiC (a P type), SiN (an N type, where it means a semiconductor such as SiN:H, not an insulator such as Si3N4), etc., can be employed as a concrete material. It is preferable that the film thickness of the semiconductor layer 12 is kept within the range of 100-5000Angstrom in order to ensure an effective electric field for shaping an inversion layer.