Semiconductor device and method for producing same

Abstract

A semiconductor device () includes a TFT () supported on a substrate (), wherein the TFT () includes a gate electrode (), a gate insulating layer () that covers the gate electrode (), and an oxide semiconductor layer () that is formed on the gate insulating layer (). The oxide semiconductor layerhas a layered structure including a first oxide semiconductor layer () in contact with the gate insulating layer () and a second oxide semiconductor layer () layered on the first oxide semiconductor layer (). The first oxide semiconductor layer () and the second oxide semiconductor layer () both include In, Ga and Zn; an In atomic ratio of the first oxide semiconductor layer () is greater than a Zn atomic ratio thereof, and an In atomic ratio of the second oxide semiconductor layer () is smaller than a Zn atomic ratio thereof; and the oxide semiconductor layer () has a side surface of a forward tapered shape.