LCD device including a TFT for reducing leakage current
First Claim
1. A liquid crystal display (LCD) device comprising a TFT (thin-film-transistor) substrate mounting thereon a plurality of TFTS, a counter substrate mounting thereon a black matrix, a liquid crystal layer sandwiched between said TFT substrate and said counter substrate, and a backlight unit disposed at a rear side of said TFT substrate for irradiating said TFT substrate with backlight, each of said TFTs having a channel in a semiconductor layer, said channel having a channel length larger at an edge portion of said channel than at a central portion thereof.
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Accused Products
Abstract
An amorphous-silicon TFT (thin-film-transistor) in an LCD device has a larger channel length at both the edge portions of the channel of the TFT compared to the central portion of the channel by forming chamfers at the corners of the source and drain electrodes. The larger channel length at both the edge portions reduces the leakage current caused by the turned-around light incident onto the channel.
36 Citations
16 Claims
- 1. A liquid crystal display (LCD) device comprising a TFT (thin-film-transistor) substrate mounting thereon a plurality of TFTS, a counter substrate mounting thereon a black matrix, a liquid crystal layer sandwiched between said TFT substrate and said counter substrate, and a backlight unit disposed at a rear side of said TFT substrate for irradiating said TFT substrate with backlight, each of said TFTs having a channel in a semiconductor layer, said channel having a channel length larger at an edge portion of said channel than at a central portion thereof.
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8. A method for fabricating a TFT in an LCD device, comprising the steps of:
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consecutively forming a gate electrode, a gate insulation film, a semiconductor layer and an ohmic contact layer of the TFT;
patterning said ohmic contact layer and said semiconductor layer;
forming a source electrode and a drain electrode of the TFT on said patterned ohmic contact layer; and
etching a portion of said patterned ohmic contact layer between said source electrode and said drain electrode by using said source electrode and said drain electrode as a mask to thereby expose a portion of said semiconductor layer as a channel, said channel having a channel length larger at an edge portion of said channel than at a central portion thereof.
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9. A method for fabricating a TFT in an LCD device, comprising the steps of:
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consecutively forming a gate electrode, a gate insulation film, a semiconductor layer and an ohmic contact layer of the TFT and a metallic film;
forming a photoresist film on said metallic film and exposing said photoresist film to exposure light having a specific wavelength through a photomask having a source electrode pattern, a drain electrode pattern and an intermediate pattern sandwiched between said source electrode pattern and said drain electrode pattern, said intermediate pattern having a width smaller than a limit of a resolution by said exposure light, to thereby form a photoresist mask pattern having a thickness larger at a region corresponding to said source and drain electrode patterns than at a region corresponding to a gap between said source electrode pattern and said drain electrode pattern;
patterning said metallic film, said ohmic contact layer and said semiconductor layer by using said photoresist mask pattern as a mask;
removing said photoresist mask pattern to leave a portion of said photoresist mask pattern having a specific thickness;
patterning said metallic film by using said portion of said photoresist mask pattern to form a source electrode and a drain electrode of the TFT; and
etching a portion of said patterned ohmic contact layer between said source electrode and said drain electrode by using said source electrode and said drain electrode as a mask to thereby expose a portion of said semiconductor layer as a channel, said channel having a channel length larger at an edge portion of said channel than at a central portion thereof. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification