Method for fomring a self-aligned LTPS TFT
AssigneeAu Optronics Corporation
InventorChih-Chin Chang
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Abstract
A method for forming a self-aligned low temperature polysilicon thin film transistor (LTPS TFT). First, active layers of a N type LTPS TFT (NLTPS TFT) and a P type LTPS TFT (PLTPS TFT) are formed on a substrate, and a gate insulating (GI) layer is formed on the substrate. Then, a source electrode, a drain electrode, and lightly doped drains (LDD) of the NLTPS TFT are formed. Further, gate electrodes of the NLTPS TFT and the PLTPS TFT are formed on the gate insulating layer. Finally, the gate electrode of the PLTPS TFT is utilized to form a source electrode and a drain electrode in the active layer of the PLTPS TFT.
Claims15
A method for forming a self-aligned low temperature polysilicon thin film transistor (LTPS TFT), the method comprising the steps of:
- providing a substrate comprising an N type LTPS TFT region and a P type LTPS TFT region;
- sequentially forming a patterned undoped polysilicon layer, a dielectric layer, a conductive layer, and a first patterned photo resist layer, the first patterned photo resist layer comprising two first gaps;
- performing an isotropic etching process to remove parts of the conductive layer via the two first gaps to form two second gaps, and to form a gate of an N type LTPS TFT;
- implanting N type dopants into the patterned undoped polysilicon layer of the N type LTPS TFT region to form a source and a drain of the N type LTPS TFT;
- removing the first patterned photo resist layer;
- implanting N type dopants into the patterned undoped polysilicon layer of the N type LTPS TFT region to form two lightly doped drains (LDD) of the N type LTPS TFT;
- forming a gate of a P type LTPS TFT in the P type LTPS TFT region;
- and
- forming a source and a drain of the P type LTPS TFT in the P type LTPS TFT region.
Dependencies are inferred from the claim text.