Patent ID: 8809992
Filing Date: 2014-08-19
Classification: H01L

Abstract:
1. A semiconductor device comprising: a first insulating film having a projection portion and a depression portion over a substrate; an oxide semiconductor film over the projection portion only of the first insulating film; a second insulating film in the depression portion of the first insulating film; a third insulating film over and in direct contact with the second insulating film; a gate insulating film over and in direct contact with a top surface of the oxide semiconductor film; a gate electrode over the gate insulating film; a source electrode and a drain electrode over and in direct contact with the oxide semiconductor film, the second insulating film and the third insulating film; and wherein the region of the first insulating film is surrounded by the depression portion, wherein entire region of the third insulating film is located at a lower position than a top surface of the gate electrode, wherein the top surface of the oxide semiconductor film is not covered by the second insulating film, wherein the third insulating film is not in contact with the oxide semiconductor film, wherein a side surface of the oxide semiconductor film is covered by and in direct contact with the second insulating film, and wherein the oxide semiconductor film comprises a channel formation region and first regions containing a dopant between which the channel formation region is sandwiched.