Claims
- 1. A method of making a thin film transistor comprising the steps of:
- a) depositing a gate electrode on a substrate;
- b) depositing a semiconductor layer over said gate electrode;
- c) depositing a first source-drain metal layer over said semiconductor layer;
- d) patterning said first source-drain metal layer to form source and drain electrode layers having a channel length L.sub.1 defined therebetween;
- e) depositing a second metal layer over said first patterned source-drain metal layer; and
- f) patterning said second metal layer to form at least one of a source electrode and a drain electrode, said second metal patterned so that it is offset with respect to the first patterned source-drain metal layer and the channel length of the transistor is less than length L.sub.1.
- 2. The method of claim 1, wherein said second source-drain metal layer in step f) is patterned so as to include both source and drain electrode sections defining length L.sub.1 therebetween.
- 3. The method of claim 1, wherein said first metal is deposited before said second metal, and wherein the first and second metal layers are patterned in steps d) and f) so that the channel length L.sub.2 of the resulting thin film transistor is equal to:
- L.sub.2 =L.sub.1 -.DELTA.L
- where L.sub.1 is the length defined between the source and drain electrodes of at least one of the first and second source-drain metals, and .DELTA.L is the offset length between said first and second metal layers on at least one of the source and drain.
- 4. The method of claim 1, wherein the patterning in step d) is carried out using a first etchant and the patterning in step f) is carried out using a second etchant different than the first etchant, said second etchant not etching the first deposited source-drain metal.
- 5. A method of making a thin film transistor (TFT) comprising the steps of:
- providing a gate electrode;
- providing a semiconductor layer;
- providing a semiconductor contact layer in a location such that the semiconductor layer is located between the contact layer and the gate electrode;
- depositing a first source-drain conductive layer on the substrate and patterning the first conductive layer so as to for a TFT channel length L.sub.1 between patterned portions thereof; and
- depositing a second conductive layer on the substrate and patterning the second conductive layer so that the resulting TFT has a channel length less than L.sub.1.
- 6. The method of claim 5, wherein the first and second conductive layers are of different metals, and the first conductive layer is deposited before the second conductive layer whereby the second conductive layer is deposited over top of the first conductive layer.
- 7. A method of making a liquid crystal display including plurality of TFTs comprising the steps of:
- providing first and second substrates;
- depositing and patterning a gate electrode on one of the first and second substrates;
- depositing a semiconductor layer on the one substrate over the gate electrode;
- depositing a semiconductor contact layer on the one substrate over the semiconductor layer;
- patterning the semiconductor and semiconductor contact layers to form a TFT island on the one substrate;
- depositing a first source-drain conductive layer on the one substrate on the TFT island;
- patterning the first source-drain conductive layer to form TFT source and drain electrode portions with a channel length L.sub.1 therebetween;
- depositing and patterning a second conductive layer on the TFT island so that the resulting TFT has a channel length less than L.sub.1 ; and
- sandwiching a liquid crystal layer between the first and second substrates.
- 8. The method of claim 7, wherein the first and second conductive layers are of different metals.
- 9. The method of claim 8, wherein the recited steps are performed in the order they are recited so that the second conductive layer is deposited over the first conductive layer on the TFT island.
Parent Case Info
This is a continuation, division of application Ser. No. 08/444,673, filed May 19, 1995 now U.S. Pat. No. 5,539,219.
US Referenced Citations (20)
Foreign Referenced Citations (2)
Number |
Date |
Country |
63-77159 |
Apr 1988 |
JPX |
283941 |
Mar 1990 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
444673 |
May 1995 |
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