Method for manufacturing semiconductor device
First Claim
1. A method for manufacturing a semiconductor device comprising the steps of:
- forming a first oxide semiconductor layer over a substrate;
forming a second oxide semiconductor layer over the first oxide semiconductor layer;
performing dehydration or dehydrogenation on the first oxide semiconductor layer and the second oxide semiconductor layer;
forming a first conductive layer and a second conductive layer over the second oxide semiconductor layer; and
forming an oxide insulating layer over the first oxide semiconductor layer so that a carrier concentration in a part of the first oxide semiconductor layer is reduced,wherein the steps of forming the first oxide semiconductor layer and forming the second oxide semiconductor layer are successively performed without exposure to air, andwherein the part of the first oxide semiconductor layer does not overlap with the first conductive layer and the second conductive layer.
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Abstract
It is an object to provide a highly reliable semiconductor device which includes a thin film transistor having stable electric characteristics. It is another object to manufacture a highly reliable semiconductor device at lower cost with high productivity. In a method for manufacturing a semiconductor device which includes a thin film transistor where a semiconductor layer including a channel formation region using an oxide semiconductor layer, a source region, and a drain region are formed using an oxide semiconductor layer, heat treatment for reducing impurities such as moisture (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer.
192 Citations
22 Claims
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1. A method for manufacturing a semiconductor device comprising the steps of:
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forming a first oxide semiconductor layer over a substrate; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing dehydration or dehydrogenation on the first oxide semiconductor layer and the second oxide semiconductor layer; forming a first conductive layer and a second conductive layer over the second oxide semiconductor layer; and forming an oxide insulating layer over the first oxide semiconductor layer so that a carrier concentration in a part of the first oxide semiconductor layer is reduced, wherein the steps of forming the first oxide semiconductor layer and forming the second oxide semiconductor layer are successively performed without exposure to air, and wherein the part of the first oxide semiconductor layer does not overlap with the first conductive layer and the second conductive layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for manufacturing a semiconductor device comprising the steps of:
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forming a gate electrode layer over a substrate; forming a gate insulating layer over the gate electrode layer; forming a first oxide semiconductor layer over the gate insulating layer; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing dehydration or dehydrogenation on the first oxide semiconductor layer and the second oxide semiconductor layer; forming a source electrode layer and a drain electrode layer over the second oxide semiconductor layer; and forming an oxide insulating layer over the first oxide semiconductor layer so that a carrier concentration in a part of the first oxide semiconductor layer is reduced, wherein the steps of forming the first oxide semiconductor layer and forming the second oxide semiconductor layer are successively performed without exposure to air, and wherein the part of the first oxide semiconductor layer does not overlap with the source electrode layer and the drain electrode layer. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for manufacturing a semiconductor device comprising the steps of:
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forming a first oxide semiconductor layer over a substrate; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing a first treatment on the first oxide semiconductor layer and the second oxide semiconductor layer so that each of the first oxide semiconductor layer and the second oxide semiconductor layer are oxygen-deficiency type or n-type oxide semiconductor layers; forming a first conductive layer and a second conductive layer over and in direct contact the second oxide semiconductor layer; and performing a second treatment after forming the first conductive layer and the second conductive layer so that a part of the first oxide semiconductor layer is an oxygen-excess type or i-type oxide semiconductor layer, wherein the steps of forming the first oxide semiconductor layer and forming the second oxide semiconductor layer are successively performed without exposure to air, and wherein the part of the first oxide semiconductor layer is between the first conductive layer and the second conductive layer. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification