Semiconductor Device and Method for Manufacturing the Same

Provided is a semiconductor device including: a gate electrode; a channel layer arranged in a region directly below or directly above the gate electrode; a source and a drain electrodes arranged to be in contact with the channel layer; and a first insulating layer arranged between the gate electrode and the channel layer, the channel layer including a first oxide semiconductor, the source electrode and/or the drain electrode including a second oxide semiconductor, the first and second oxide semiconductors containing In, W and Zn, a content rate of W/(In+W+Zn) being higher than 0.001 atomic % and not higher than 8.0 atomic %, a content rate of Zn/(In+W+Zn) being from 1.2 atomic % to 40 atomic %, an atomic ratio of Zn to W being higher than 1.0 and lower than 20000. Also provided is a method for manufacturing the device.