Capping Layers for Metal Oxynitride TFTS
First Claim
1. A thin film transistor fabrication method, comprising:
- depositing a semiconductor layer over a thin film transistor stack comprising a substrate, a gate electrode, and a gate dielectric layer, the semiconductor layer comprising nitrogen, oxygen, and one or more elements selected from zinc, indium, tin, gallium, cadmium, and combinations thereof;
depositing a conductive layer over the semiconductor layer;
etching the conductive layer to define source and drain electrodes and to expose a portion of the semiconductor layer between the source and drain electrodes defined as the active channel; and
depositing a capping layer over the exposed semiconductor layer by flowing N2O and SiH4 gas into a processing chamber at a ratio of N2O and SiH4 of between about 20;
1 to about 40;
1.
1 Assignment
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Accused Products
Abstract
A capping layer may be deposited over the active channel of a thin film transistor (TFT) in order to protect the active channel from contamination. The capping layer may affect the performance of the TFT. If the capping layer contains too much hydrogen, nitrogen, or oxygen, the threshold voltage, sub threshold slope, and mobility of the TFT may be negatively impacted. By controlling the ratio of the flow rates of the nitrogen, oxygen, and hydrogen containing gases, the performance of the TFT may be optimized. Additionally, the power density, capping layer deposition pressure, and the temperature may also be controlled to optimize the TFT performance.
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Citations
22 Claims
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1. A thin film transistor fabrication method, comprising:
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depositing a semiconductor layer over a thin film transistor stack comprising a substrate, a gate electrode, and a gate dielectric layer, the semiconductor layer comprising nitrogen, oxygen, and one or more elements selected from zinc, indium, tin, gallium, cadmium, and combinations thereof; depositing a conductive layer over the semiconductor layer; etching the conductive layer to define source and drain electrodes and to expose a portion of the semiconductor layer between the source and drain electrodes defined as the active channel; and depositing a capping layer over the exposed semiconductor layer by flowing N2O and SiH4 gas into a processing chamber at a ratio of N2O and SiH4 of between about 20;
1 to about 40;
1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A thin film transistor fabrication method, comprising:
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depositing a semiconductor layer over a thin film transistor stack comprising a substrate, a gate electrode, and a gate dielectric layer, the semiconductor layer comprising nitrogen, oxygen, and one or more elements selected from zinc, indium, tin, gallium, cadmium, and combinations thereof; depositing a conductive layer over the semiconductor layer; etching the conductive layer to define source and drain electrodes and to expose a portion of the semiconductor layer between the source and drain electrodes defined as the active channel; and depositing a silicon oxide layer over the exposed semiconductor layer in the active channel to partially fill the active channel, the depositing comprising flowing N2O, SiH4, and PH3 gas into a processing chamber to obtain a chamber pressure of about 500 mTorr to about 2.5 Torr and applying an RF bias and to a gas distribution showerhead in the processing chamber is between about 1.16×
10−
6 W/cm2 to about 4.63×
10−
3 W/cm2. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A thin film transistor, comprising:
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one or more gate dielectric layers disposed over a gate electrode and a substrate; a semiconductor layer disposed over the one or more gate dielectric layers, the semiconductor layer comprising nitrogen, oxygen, and one or more elements selected from zinc, indium, gallium, cadmium, tin, and combinations thereof; source and drain electrodes disposed over a portion of the semiconductor layer, the source and drain electrodes spaced apart a first distance and exposing a portion of the semiconductor layer defined as an active channel; and a first capping layer disposed over the semiconductor layer in the active channel and partially filling the active channel, the first capping layer comprising silicon oxide. - View Dependent Claims (19, 20, 21, 22)
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Specification