Semiconductor device and method for manufacturing the same
First Claim
1. A method for manufacturing a semiconductor device, comprising the steps of:
- forming a first insulating layer over an oxide semiconductor layer;
forming a sacrificial layer overlapping with a part of the oxide semiconductor layer with the first insulating layer interposed therebetween;
forming a second insulating layer over the sacrificial layer;
removing a part of the second insulating layer and a part of the sacrificial layer so that a top surface of the sacrificial layer is exposed and the top surface of the sacrificial layer is substantially flush with a top surface of the rest of the second insulating layer;
removing the sacrificial layer, thereby forming a third insulating layer which does not cover a part of the first insulating layer;
supplying oxygen into a region of the oxide semiconductor layer after removing the sacrificial layer;
forming a conductive layer over the first insulating layer and the third insulating layer after the supplying oxygen; and
forming a gate electrode by processing the conductive layer so that a top surface of the third insulating layer is exposed and a top surface of the processed conductive layer is substantially flush with the top surface of the third insulating layer, andwherein the region does not overlap with the third insulating layer.
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Abstract
A transistor including an oxide semiconductor film, which has stable electric characteristics is provided. A transistor including an oxide semiconductor film, which has excellent on-state characteristics is also provided. A semiconductor device in which an oxide semiconductor film having low resistance is formed and the resistance of a channel region of the oxide semiconductor film is increased. Note that an oxide semiconductor film is subjected to a process for reducing the resistance to have low resistance. The process for reducing the resistance of the oxide semiconductor film may be a laser process or heat treatment at a temperature higher than or equal to 450° C. and lower than or equal to 740° C., for example. A process for increasing the resistance of the channel region of the oxide semiconductor film having low resistance may be performed by plasma oxidation or implantation of oxygen ions, for example.
127 Citations
19 Claims
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1. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a first insulating layer over an oxide semiconductor layer; forming a sacrificial layer overlapping with a part of the oxide semiconductor layer with the first insulating layer interposed therebetween; forming a second insulating layer over the sacrificial layer; removing a part of the second insulating layer and a part of the sacrificial layer so that a top surface of the sacrificial layer is exposed and the top surface of the sacrificial layer is substantially flush with a top surface of the rest of the second insulating layer; removing the sacrificial layer, thereby forming a third insulating layer which does not cover a part of the first insulating layer; supplying oxygen into a region of the oxide semiconductor layer after removing the sacrificial layer; forming a conductive layer over the first insulating layer and the third insulating layer after the supplying oxygen; and forming a gate electrode by processing the conductive layer so that a top surface of the third insulating layer is exposed and a top surface of the processed conductive layer is substantially flush with the top surface of the third insulating layer, and wherein the region does not overlap with the third insulating layer. - View Dependent Claims (2, 3, 4, 5, 6, 19)
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7. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a first insulating layer over an oxide semiconductor layer; forming a sacrificial layer overlapping with a part of the oxide semiconductor layer with the first insulating layer interposed therebetween; forming a second insulating layer over the sacrificial layer; removing a part of the second insulating layer and a part of the sacrificial layer so that a top surface of the sacrificial layer is exposed and the top surface of the sacrificial layer is substantially flush with a top surface of the rest of the second insulating layer; removing the sacrificial layer, thereby forming a third insulating layer which does not cover a part of the first insulating layer; supplying oxygen into a region of the oxide semiconductor layer after removing the sacrificial layer; forming a conductive layer over the first insulating layer and the third insulating layer after the supplying oxygen; and forming a gate electrode by processing the conductive layer so that a top surface of the third insulating layer is exposed and a top surface of the processed conductive layer is substantially flush with the top surface of the third insulating layer, wherein the region does not overlap with the third insulating layer, and wherein plasma oxidation is performed in the step of supplying oxygen. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a first insulating layer over an oxide semiconductor layer; forming a sacrificial layer overlapping with a part of the oxide semiconductor layer with the first insulating layer interposed therebetween; forming a second insulating layer over the sacrificial layer; removing a part of the second insulating layer and a part of the sacrificial layer so that a top surface of the sacrificial layer is exposed and the top surface of the sacrificial layer is substantially flush with a top surface of the rest of the second insulating layer; removing the sacrificial layer, thereby forming a third insulating layer which does not cover a part of the first insulating layer; supplying oxygen into a region of the oxide semiconductor layer after removing the sacrificial layer; forming a conductive layer over the first insulating layer and the third insulating layer after the supplying oxygen; and forming a gate electrode by processing the conductive layer so that a top surface of the third insulating layer is exposed and a top surface of the processed conductive layer is substantially flush with the top surface of the third insulating layer, wherein the region does not overlap with the third insulating layer, and wherein implantation of oxygen ions is performed in the step of supplying oxygen. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification