Patent ID: 9583638
Date: 2017-02-28
CPC Classifications: H01L

Claim:
1. A transistor, comprising: a channel layer having a multi-layer structure; a source electrode and a drain electrode separately contacting opposing ends of the channel layer; a gate corresponding to the channel layer; and a gate insulating layer between the channel layer and the gate, wherein the channel layer includes a first layer, a second layer and a third layer that are sequentially disposed on a same side of the gate, each of the first layer, the second layer and the third layer includes a ZnO-based oxide semiconductor, the first layer is between the gate and the second layer, the second layer is between the gate and the third layer, and the third layer is a continuous layer from the source electrode to the drain electrode, an oxygen concentration of the second layer is higher than an oxygen concentration of the first and third layers, a ratio of a concentration of all metal elements of the second layer with respect to the oxygen concentration thereof is lower than a ratio of a concentration of all metal elements of the first or third layer with respect to the oxygen concentration thereof, a carrier density of the first and third layers is greater than a carrier density of the second layer, a first portion of the third layer is between the source electrode and the second layer, a top surface of the first portion directly contacts the source electrode, a second portion of the third layer is between the drain electrode and the second layer, a top surface of the second portion directly contacts the drain electrode, a third portion of the third layer is between the first portion and the second portion, and each of the first portion, the second portion and the third portion has an oxygen concentration lower than the oxygen concentration of the second layer, the channel layer has the multi-layer structure including the first layer, the second layer and the third layer in a region including a first region between the source electrode and the drain electrode, the first region is not overlapped with the source electrode and the drain electrode.