Field effect transistor manufacturing method

Abstract

Provided is a novel method for manufacturing a field effect transistor. Prior to forming an amorphous oxide layer on a substrate, ultraviolet rays are irradiated onto the substrate surface in an ozone atmosphere, plasma is irradiated onto the substrate surface, or the substrate surface is cleaned by a chemical solution containing hydrogen peroxide.

1 - 6 . (canceled) 
     
     
         7 . A method of manufacturing a field-effect transistor comprising:
 a first step of preparing a substrate;   a second step of depositing on the substrate an insulating layer or an active layer comprising an amorphous oxide semiconductor comprising one element selected from at least In, Zn and Sn; and   third step of thermal processing, at a higher temperature than a deposition temperature of the active layer or the insulating layer in the second step, in an atmosphere of at least one of ozone and nitrogen oxide to reduce defect levels in the amorphous oxide semiconductor, wherein the temperature of the thermal processing is higher than the deposition temperature of the active layer or the insulating layer, and is not more than 200° C.