METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE
First Claim
1. A method for manufacturing a semiconductor device, comprising:
- forming a gate electrode layer over a substrate having an insulating surface;
stacking a gate insulating layer, an oxide semiconductor film, and a conductive film over the gate electrode layer;
forming a first mask layer over the gate insulating layer, the oxide semiconductor film, and the conductive film;
performing a first etching with the first mask layer to etch the oxide semiconductor film and the conductive film so that an oxide semiconductor layer and a conductive layer are formed;
forming a second mask layer by ashing the first mask layer; and
performing a second etching with the second mask layer to etch the oxide semiconductor layer and the conductive layer so that an oxide semiconductor layer having a depression, a source electrode layer, and a drain electrode layer are formed,wherein the first mask layer is formed using a light-exposure mask,wherein the first etching is dry etching with use of an etching gas,wherein the second etching is wet etching with use of an etchant, andwherein the oxide semiconductor layer having the depression includes a region with a smaller thickness than a region overlapping with the source electrode layer or the drain electrode layer.
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Abstract
An object is to manufacture a semiconductor device including an oxide semiconductor at low cost with high productivity in such a manner that a photolithography process is simplified by reducing the number of light-exposure masks. In a method for manufacturing a semiconductor device including a channel-etched inverted-staggered thin film transistor, an oxide semiconductor film and a conductive film are etched using a mask layer formed with the use of a multi-tone mask which is a light-exposure mask through which light is transmitted so as to have a plurality of intensities. In etching steps, a first etching step is performed by dry etching in which an etching gas is used, and a second etching step is performed by wet etching in which an etchant is used.
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Citations
14 Claims
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1. A method for manufacturing a semiconductor device, comprising:
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forming a gate electrode layer over a substrate having an insulating surface; stacking a gate insulating layer, an oxide semiconductor film, and a conductive film over the gate electrode layer; forming a first mask layer over the gate insulating layer, the oxide semiconductor film, and the conductive film; performing a first etching with the first mask layer to etch the oxide semiconductor film and the conductive film so that an oxide semiconductor layer and a conductive layer are formed; forming a second mask layer by ashing the first mask layer; and performing a second etching with the second mask layer to etch the oxide semiconductor layer and the conductive layer so that an oxide semiconductor layer having a depression, a source electrode layer, and a drain electrode layer are formed, wherein the first mask layer is formed using a light-exposure mask, wherein the first etching is dry etching with use of an etching gas, wherein the second etching is wet etching with use of an etchant, and wherein the oxide semiconductor layer having the depression includes a region with a smaller thickness than a region overlapping with the source electrode layer or the drain electrode layer. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for manufacturing a semiconductor device, comprising:
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forming a gate electrode layer over a substrate having an insulating surface; stacking a gate insulating layer, a first oxide semiconductor film, a second oxide semiconductor film, and a conductive film over the gate electrode layer; forming a first mask layer over the gate insulating layer, the first oxide semiconductor film, the second oxide semiconductor film, and the conductive film; performing a first etching with the first mask layer to etch the first oxide semiconductor film, the second oxide semiconductor film, and the conductive film so that a first oxide semiconductor layer, a second oxide semiconductor layer, and a conductive layer are formed; forming a second mask layer by ashing the first mask layer; and performing a second etching with the second mask layer to etch the first oxide semiconductor layer, the second oxide semiconductor layer, and the conductive layer so that an oxide semiconductor layer having a depression, a source region, a drain region, a source electrode layer, and a drain electrode layer are formed, wherein the first mask layer is formed using a light-exposure mask, wherein the first etching is dry etching with use of an etching gas, wherein the second etching is wet etching with use of an etchant, and wherein the oxide semiconductor layer having the depression includes a region with a smaller thickness than a region overlapping with the source region or the drain region. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification