Patent ID: 8956907
Filing Date: 2015-02-17
Classification: H01L

Abstract:
1. A method of fabricating a field effect transistor, the method comprising: a first step of forming a first oxide semiconductor film on a gate insulation layer disposed on a gate electrode; after the first step, a second step of forming a second oxide semiconductor film on the first oxide semiconductor film, the second oxide semiconductor film differing in cation composition from the first oxide semiconductor film and being lower in electrical conductivity than the first oxide semiconductor film; after the second step, a third step of applying a heat treatment at over 300° C. in an oxidizing atmosphere; after the third step, a fourth step of forming a third oxide semiconductor film on the second oxide semiconductor film, the third oxide semiconductor film differing in cation composition from the first oxide semiconductor film and being lower in electrical conductivity than the first oxide semiconductor film; after the fourth step, a fifth step of applying a heat treatment in an oxidizing atmosphere; and, between the fourth step and the fifth step or after the fifth step, an electrode formation step of forming a source electrode and a drain electrode on the third oxide semiconductor film.