METHOD FOR MANUFACTURING TRANSISTOR, TRANSISTOR, AND SPUTTERING TARGET

摘要

Disclosed is a method for manufacturing a transistor, which is capable of achieving desired electrical conduction characteristics of an active layer without introducing oxygen during the film formation. In a method for manufacturing a transistor according to one embodiment of the present invention, an oxide semiconductor layer (an active layer (15)) having the above-mentioned composition range is formed by sputtering a target, which is formed from an oxide semiconductor, in a non-oxidizing atmosphere.  The oxide semiconductor has a composition range represented by the following general formula: ZnxGayInzO(x+3y/2+3z/2), with the ratio z/y being 0 or greater but less than 0.9 and the ratio x/y being 0 or greater but less than 6.5.  The oxide semiconductor layer is subjected to a heat treatment at a temperature of not less than 200°C but not more than 400°C.  Consequently, a transistor having an on/off current ratio characteristic of not less than 5 digits can be manufactured.