Semiconductor device and manufacturing method thereof
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorShunpei YAMAZAKI
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Abstract
In a semiconductor device, a region where a channel is formed is protected. In a semiconductor device, a region protecting a region where a channel is formed is provided in a semiconductor layer. In a semiconductor device, a layer protecting a region where a channel is formed is provided. In a semiconductor device, a region and/or a layer protecting a region where a channel is formed have/has a low density of defect states. In a semiconductor device, a region where a channel is formed has a low density of defect states.
Claims16
A semiconductor device comprising:
- an oxide semiconductor layer;
- a gate insulating film in contact with the oxide semiconductor layer;
- and
- a gate electrode overlapping with the oxide semiconductor layer with the gate insulating film provided between the gate electrode and the oxide semiconductor layer,
- wherein a first region is included in a range from a top surface to a 5 nm depth of the oxide semiconductor layer and has a larger energy gap than a second region in a depth of greater than or equal to 5 nm from the top surface of the oxide semiconductor layer.
A semiconductor device comprising:
- an oxide semiconductor layer containing indium and an element M, wherein M represents aluminum, gallium, yttrium, zirconium, or tin;
- a gate insulating film in contact with the oxide semiconductor layer;
- and
- a gate electrode overlapping with the oxide semiconductor layer with the gate insulating film provided between the gate electrode and the oxide semiconductor layer,
- wherein the oxide semiconductor layer comprises a region where a proportion of the indium is lower than a proportion of the element M in a range from a top surface to a 5 nm depth of the oxide semiconductor layer.
A method for manufacturing a semiconductor device comprising the steps of:
- forming a gate electrode;
- forming a gate insulating film over the gate electrode;
- forming a first oxide semiconductor layer over the gate insulating film and forming a second oxide semiconductor layer over the first oxide semiconductor layer,
- forming a conductive film over the second oxide semiconductor layer;
- and
- partly etching the conductive film to expose a part of the second oxide semiconductor layer,
- wherein the part of the second oxide semiconductor layer is etched so that a thickness of the part of the second oxide semiconductor layer is greater than or equal to 0 nm and less than 5 nm.
Dependencies are inferred from the claim text.