Capping layers for metal oxynitride TFTs
First Claim
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1. A thin film transistor fabrication method, the 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;
a compound comprising nitrogen, oxygen, zinc, indium and gallium;
ora compound comprising nitrogen, oxygen, zinc and tin;
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.
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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.
138 Citations
17 Claims
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1. A thin film transistor fabrication method, the 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; a compound comprising nitrogen, oxygen, zinc, indium and gallium;
ora compound comprising nitrogen, oxygen, zinc and tin; 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)
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9. A thin film transistor fabrication method, the 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; a compound comprising nitrogen, oxygen, zinc, indium and gallium;
ora compound comprising nitrogen, oxygen, zinc and tin; 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 and flowing PH3 gas along with the N2O and SiH4 gases. - View Dependent Claims (10)
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11. A thin film transistor fabrication method, the 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; a compound comprising nitrogen, oxygen, zinc, indium and gallium;
ora compound comprising nitrogen, oxygen, zinc and tin; 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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Specification