Semiconductor device and method for manufacturing the same

摘要

A region containing a high proportion of crystal components and a region containing a high proportion of amorphous components are formed separately in one oxide semiconductor film. The region containing a high proportion of crystal components is formed so as to serve as a channel formation region and the other region is formed so as to contain a high proportion of amorphous components. It is preferable that an oxide semiconductor film in which a region containing a high proportion of crystal components and a region containing a high proportion of amorphous components are mixed in a self-aligned manner be formed. To separately form the regions which differ in crystallinity in the oxide semiconductor film, first, an oxide semiconductor film containing a high proportion of crystal components is formed and then process for performing amorphization on part of the oxide semiconductor film is conducted.

主权项

1. A semiconductor device comprising:
a gate electrode layer over a substrate; a gate insulating film over the gate electrode layer; an oxide semiconductor layer over the gate insulating film; an insulating layer over the oxide semiconductor layer; and a source electrode layer and a drain electrode layer over the insulating layer, wherein the oxide semiconductor layer comprises:
a first region which overlaps with the insulating layer;a second region which is in contact and overlaps with the source electrode layer; anda third region which is in contact and overlaps with the drain electrode layer, wherein the first region is positioned between the second region and the third region, wherein a crystallinity of the first region is higher than a crystallinity of each of the second region and the third region, wherein a defect density of the first region is lower than a defect density of the second region, wherein the first region comprises a first crystal part and a second crystal part, wherein a c-axis of each of the first crystal part and the second crystal part is aligned in a direction substantially perpendicular to a top surface of the oxide semiconductor layer, wherein directions of an a-axis and a b-axis of the first crystal part are different from directions of an a-axis and a b-axis of the second crystal part, wherein the oxide semiconductor layer comprises indium, gallium, and zinc, and wherein the insulating layer is in direct contact with top and side surfaces of the oxide semiconductor layer.