SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME
0 Assignments
0 Petitions
Accused Products
Abstract
An object is to provide a structure of a transistor which has a channel formation region formed using an oxide semiconductor and a positive threshold voltage value, which enables a so-called normally-on switching element. The transistor includes an oxide semiconductor stack in which at least a first oxide semiconductor layer and a second oxide semiconductor layer with different energy gaps are stacked and a region containing oxygen in excess of its stoichiometric composition ratio is provided.
16 Citations
13 Claims
-
1. (canceled)
-
2. A semiconductor device comprising:
-
an oxide semiconductor stack including a first oxide semiconductor layer, a second oxide semiconductor layer in contact with a top surface of the first oxide semiconductor layer, and a third oxide semiconductor layer in contact with a top surface of the second oxide semiconductor layer; a source electrode layer and a drain electrode layer adjacent to the oxide semiconductor stack; a gate insulating film adjacent to the oxide semiconductor stack; and a gate electrode layer adjacent to the oxide semiconductor stack with the gate insulating film interposed therebetween, wherein, in the oxide semiconductor stack, a region which does not overlap the source electrode layer or the drain electrode layer has a higher oxygen concentration than a region which overlaps the source electrode layer or the drain electrode layer, and wherein the third oxide semiconductor layer covers side surfaces of the second oxide semiconductor layer and the first oxide semiconductor layer in a channel width direction. - View Dependent Claims (3, 4, 5, 6, 7)
-
-
8. A semiconductor device comprising:
-
an oxide semiconductor stack including a first oxide semiconductor layer, a second oxide semiconductor layer in contact with a top surface of the first oxide semiconductor layer, and a third oxide semiconductor layer in contact with a top surface of the second oxide semiconductor layer; a source electrode layer and a drain electrode layer adjacent to the oxide semiconductor stack; a gate insulating film over the oxide semiconductor stack; and a gate electrode layer over the oxide semiconductor stack with the gate insulating film interposed therebetween, wherein, in the oxide semiconductor stack, a region which does not overlap the source electrode layer or the drain electrode layer has a higher oxygen concentration than a region which overlaps the source electrode layer or the drain electrode layer, and wherein the third oxide semiconductor layer covers side surfaces of the second oxide semiconductor layer and the first oxide semiconductor layer in a channel width direction. - View Dependent Claims (9, 10, 11, 12, 13)
-
Specification