Claims
- 1. A method for making a thin film transistor comprising the steps of:
- providing a substrate having a surface;
- depositing a p-doped Si layer on said surface;
- patterning said p-doped Si layer to remove portions of said Si layer and to define a source region, a drain region and a channel region;
- depositing a SiGe layer containing about 80 atomic % Ge by CVD using a mixed gas of SiH.sub.4 and GeH.sub.4 at a flow rate of GeH.sub.4 /(GeH.sub.4 +SiH.sub.4) of from about 0.3 to about 0.4;
- patterning said SiGe layer and etching back so that only a portion of said SiGe layer remains in said channel region;
- annealing said source, drain and channel regions by irradiation with an XeCl laser to crystallize the source, drain and channel regions;
- depositing an insulation layer over said source, drain and channel regions;
- patterning and etching the insulator layer to form a hole for said source and drain regions, respectively;
- forming source and drain electrodes in the respective holes for said source and drain regions;
- forming a gate electrode above said channel region by depositing a SiGe layer by CVD and patterning and etching the SiGe layer to provide said gate electrode, whereby a thin film transistor having a carrier mobility at 300.degree. K of 1400 cm.sup.2 /Volt second or higher and a ratio of on-current to off-current from about 10.sup.6 to about 10.sup.7 is provided.
- 2. A method as defined in claim 1, wherein the substrate is selected from the group consisting of glass and SiO.sub.2 substrates.
- 3. A method as defined in claim 1, wherein in said annealing step, irradiation is performed using a wavelength of about 308 nm and a pulse width of 30 ns.
- 4. A method as defined in claim 1, wherein said source and drain electrodes are made from the group consisting of Al, Mo and Cr.
- 5. A method as defined in claim 1, wherein the source and drain regions have a band gap of about 1.2 eV.
Priority Claims (1)
Number |
Date |
Country |
Kind |
4-074577 |
Mar 1992 |
JPX |
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Division of U.S. Ser. No. 08/331,273, filed Oct. 28, 1994, which is in turn a continuation of U.S. Ser. No. 08/036,285, filed Mar. 24, 1993, abandoned.
US Referenced Citations (12)
Divisions (1)
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Number |
Date |
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331273 |
Oct 1994 |
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Continuations (1)
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Number |
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36285 |
Mar 1993 |
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