US 2010/0136754 A1 · THIN FILM TRANSISTOR AND METHOD OF FABRICATING THIN FILM TRANSISTOR SUBSTRATE

Abstract

Provided are a thin film transistor (TFT) capable of increasing ON current and decreasing OFF current values, a TFT substrate having the polysilicon TFT, a method of fabricating the polysilicon TFT, and a method of fabricating a TFT substrate having the polysilicon TFT. The polysilicon TFT substrate includes a gate line and a data line defining a pixel region, a pixel electrode formed in the pixel region, and a TFT including a gate electrode connected to the gate line, a source electrode connected to the data line, a drain electrode connected to the pixel electrode, and a polysilicon active layer forming a channel between the source and drain electrodes. The polysilicon active layer includes a channel region on which the gate electrode is superposed, source and drain regions connected to the source and drain electrode, respectively, and at least two lightly doped drain (LDD) regions y formed between the source region and the channel region and between the drain region and the channel region. The LDD regions have an impurity concentration different from each other.

Claims11

Dependent claims

A method of fabricating a thin film transistor (TFT) comprising:

forming a polysilicon active layer on a substrate;
forming a gate insulating layer to cover the polysilicon active layer;
forming a first gate electrode on the gate insulating layer;
doping a first impurity into the polysilicon active layer to form a channel region on which the first gate electrode is superposed and a pair of first lightly doped drain (LDD) regions disposed at the both sides of the channel region;
forming a second gate electrode on the first gate electrode to completely cover the first gate electrode;
doping a second impurity into the polysilicon active layer to form a pair of second LDD regions having an impurity concentration higher than an impurity concentration of the first LDD regions, and source and drain regions opposite to each other interposing the channel region, the first LDD regions and the second LDD regions between them;
and
forming source and drain electrodes connected to the source and drain regions, respectively.

5 more elements

A method of fabricating a thin film transistor (TFT) substrate comprising:

forming a TFT, which has a gate electrode, a polysilicon active layer including a channel region, source and drain regions opposite to each other having the channel region between them, and at least two LDD regions formed between the source region and the channel region and between the drain region and the channel region, on a substrate, the LDD regions having an impurity concentration different from each other;
and
forming a pixel electrode connected to the TFT,
wherein the gate electrode comprises a first gate electrode superposed on the channel region, and a second gate electrode completely covering the first gate electrode.

1 more element

Dependencies are inferred from the claim text.

Thin film transistor and method of fabricating thin film transistor substrate

Life of this patent

Thin film transistor and method of fabricating thin film transistor substrate

Life of this patent

Abstract

Claims11