Patent ID: 8872175
Filing Date: 2014-10-28
Classification: H01L

Abstract:
1. A semiconductor device comprising a transistor, the transistor comprising: a first oxide semiconductor layer; a second oxide semiconductor layer over the first oxide semiconductor layer; a source electrode over the second oxide semiconductor layer; and a drain electrode over the second oxide semiconductor layer, wherein the first oxide semiconductor layer includes a channel formation region, wherein the second oxide semiconductor layer includes a first region overlapping with the channel formation region, wherein the second oxide semiconductor layer includes a second region in contact with the source electrode, wherein the second oxide semiconductor layer includes a third region in contact with the drain electrode, wherein the first region is located between the source electrode and the drain electrode, wherein a thickness of each of the second region and the third region is thicker than a thickness of the first region, wherein the first region has a first electrical conductivity, wherein the second region has a second electrical conductivity, wherein the third region has a third electrical conductivity, and wherein each of the second electrical conductivity and the third electrical conductivity is higher than the first electrical conductivity.