Semiconductor device with oxygen rich gate insulating layer
First Claim
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1. A semiconductor device comprising:
- a gate electrode over an insulating surface;
a gate insulating layer over the gate electrode;
an oxide semiconductor layer over the gate insulating layer; and
a source region and a drain region over the oxide semiconductor layer,wherein the source region and the drain region each comprise oxide semiconductor,wherein the source region and the drain region each have a lower oxygen concentration than the oxide semiconductor layer,wherein the gate insulating layer comprises a first region and a second region,wherein the first region is located closer to the oxide semiconductor layer side than the second region, andwherein the first region has a higher oxygen concentration than the second region.
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Abstract
A thin film transistor structure in which a source electrode and a drain electrode formed from a metal material are in direct contact with an oxide semiconductor film may lead to high contact resistance. One cause of high contact resistance is that a Schottky junction is formed at a contact plane between the source and drain electrodes and the oxide semiconductor film. An oxygen-deficient oxide semiconductor layer which includes crystal grains with a size of 1 nm to 10 nm and has a higher carrier concentration than the oxide semiconductor film serving as a channel formation region is provided between the oxide semiconductor film and the source and drain electrodes.
196 Citations
25 Claims
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1. A semiconductor device comprising:
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a gate electrode over an insulating surface; a gate insulating layer over the gate electrode; an oxide semiconductor layer over the gate insulating layer; and a source region and a drain region over the oxide semiconductor layer, wherein the source region and the drain region each comprise oxide semiconductor, wherein the source region and the drain region each have a lower oxygen concentration than the oxide semiconductor layer, wherein the gate insulating layer comprises a first region and a second region, wherein the first region is located closer to the oxide semiconductor layer side than the second region, and wherein the first region has a higher oxygen concentration than the second region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A semiconductor device comprising:
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a gate electrode over an insulating surface; a gate insulating layer over the gate electrode; an oxide semiconductor layer over the gate insulating layer; a first source region and a first drain region over the oxide semiconductor layer; a second source region over the first source region; and a second drain region over the first drain region, wherein the first source region and the first drain region each comprise oxide semiconductor, wherein the first source region and the first drain region each have a lower oxygen concentration than the oxide semiconductor layer, wherein the gate insulating layer comprises a first region and a second region, wherein the first region is located closer to the oxide semiconductor layer side than the second region, wherein the first region has a higher oxygen concentration than the second region, and wherein the second source region and the second drain region each comprise the oxide semiconductor comprising W, Mo, Ti, Ni, or Al. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A semiconductor device comprising:
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a gate electrode over an insulating surface; a gate insulating layer over the gate electrode; an oxide semiconductor layer over the gate insulating layer; a channel protective layer over a channel formation region of the oxide semiconductor layer; and a source region and a drain region over the oxide semiconductor layer, wherein the source region and the drain region each comprise oxide semiconductor, wherein the source region and the drain region each have a lower oxygen concentration than the oxide semiconductor layer, wherein the gate insulating layer comprises a first region and a second region, wherein the first region is located closer to the oxide semiconductor layer side than the second region, and wherein the first region has a higher oxygen concentration than the second region. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification