Semiconductor device and manufacturing method thereof

摘要

A transistor having a multi-layer structure of oxide semiconductor layers is provided in which a second oxide semiconductor layer having a crystalline structure including indium zinc oxide is formed over a first oxide semiconductor layer having an amorphous structure, and at least a third oxide semiconductor layer is formed stacked over the second oxide semiconductor layer. The second oxide semiconductor layer mainly serves as a carrier path for the transistor. The first oxide semiconductor layer and the third oxide semiconductor layer each serve as a barrier layer for suppressing entrance of impurity states of an insulating layer in contact with the multi-layer structure to the carrier path.

主权项

1. A semiconductor device comprising:
an oxide semiconductor stack; a first gate electrode layer comprising a region overlapping with the oxide semiconductor stack; a first gate insulating layer between the oxide semiconductor stack and the first gate electrode layer; a first electrode layer and a second electrode layer electrically connected to the oxide semiconductor stack; a second gate electrode layer comprising a region overlapping with the oxide semiconductor stack; and a second gate insulating layer between the oxide semiconductor stack and the second gate electrode layer; the oxide semiconductor stack being between the first gate insulating layer and the second gate insulating layer, wherein the oxide semiconductor stack includes at least a first oxide semiconductor layer, a second oxide semiconductor layer comprising a crystalline structure over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer, wherein the first oxide semiconductor layer and the third oxide semiconductor layer each include a layer expressed as InMXZnYOZ (X≧1, Y>1, Z>0, and M is one or more metal elements selected from Ga, Mg, Hf, Al, Sn, Zr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), and wherein the second oxide semiconductor layer includes an indium zinc oxide layer.