Method of fabricating a fully self-aligned TFT-LCD
First Claim
1. A method of forming a thin film transistor (TFT) on a glass substrate, said method comprising:
- forming an indium tin oxide (ITO) on said glass substrate;
forming a first metal layer on said ITO layer;
patterning said first metal layer, said ITO layer to form a gate electrode of said TFT;
forming a first silicon nitride layer on said gate electrode and on said glass substrate;
forming a silicon layer on said first silicon nitride layer;
forming a second silicon nitride layer on said silicon layer;
forming a first positive photoresist on said second silicon nitride layer;
exposing said first positive photoresist from a back side of said glass substrate using said gate electrode as a mask and removing exposed portion of said first positive photoresist;
etching said second silicon nitride layer using said first positive photoresist as a mask, thereby leaving residual portion of said second silicon nitride layer over said gate electrode;
removing said first positive photoresist;
forming a doped silicon layer along a surface of said silicon layer and said residual portion of said second silicon nitride layer;
forming a negative photoresist on said doped silicon layer;
exposing said negative photoresist from said back side of said glass substrate using said gate electrode as a mask and then removing unexposed portion of said negative photoresist;
etching said doped silicon layer using said negative photoresist as a mask, thereby exposing said residual portion of said second silicon nitride layer;
removing said negative photoresist;
patterning a second positive photoresist on said doped silicon layer to define a contact region;
etching said residual portion of said second silicon nitride layer, said silicon layer and said first silicon nitride layer to from a contact hole;
forming a second metal layer on said doped silicon layer, said residual portion of said second silicon nitride layer and in said contact hole;
forming a third metal layer on said second metal layer;
performing a thermal process to form silicide at the interface between said doped silicon layer and said second metal layer;
patterning a third positive photoresist on said third metal layer;
etching said third metal layer using said third positive photoresist as a mask;
removing said third positive photoresist;
etching said second metal layer using said etched third metal layer as a mask, thereby forming source and drain regions;
etching said silicon layer and doped silicon layer to define an island pattern; and
forming a passivation layer over said glass substrate.
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Accused Products
Abstract
An ITO layer and a first metal layer is patterned on a glass substrate. A first silicon nitride layer, a silicon layer and a second silicon nitride layer are formed on the substrate. A back-side exposure is introduced using the gate electrodes as a mask. The second silicon nitride layer that is not covered by a positive photoresist is etched. A heavily doped silicon layer is formed over the substrate. A negative photoresist is formed over the heavily doped silicon layer. Then, a further back-side exposure is employed. The heavily doped silicon layer over the etched second silicon nitride layer is removed. Via holes are created to expose a portion of the first metal layer. A second metal layer and a third metal layer are respectively formed. Next, a thermal annealing is performed for forming silicide. Subsequently, a third metal layer and the second metal layer are patterned. Then, the island pattern is defined. Subsequently, a passivation layer formed of silicon nitride layer is deposited on the island pattern.
96 Citations
16 Claims
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1. A method of forming a thin film transistor (TFT) on a glass substrate, said method comprising:
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forming an indium tin oxide (ITO) on said glass substrate; forming a first metal layer on said ITO layer; patterning said first metal layer, said ITO layer to form a gate electrode of said TFT; forming a first silicon nitride layer on said gate electrode and on said glass substrate; forming a silicon layer on said first silicon nitride layer; forming a second silicon nitride layer on said silicon layer; forming a first positive photoresist on said second silicon nitride layer; exposing said first positive photoresist from a back side of said glass substrate using said gate electrode as a mask and removing exposed portion of said first positive photoresist; etching said second silicon nitride layer using said first positive photoresist as a mask, thereby leaving residual portion of said second silicon nitride layer over said gate electrode; removing said first positive photoresist; forming a doped silicon layer along a surface of said silicon layer and said residual portion of said second silicon nitride layer; forming a negative photoresist on said doped silicon layer; exposing said negative photoresist from said back side of said glass substrate using said gate electrode as a mask and then removing unexposed portion of said negative photoresist; etching said doped silicon layer using said negative photoresist as a mask, thereby exposing said residual portion of said second silicon nitride layer; removing said negative photoresist; patterning a second positive photoresist on said doped silicon layer to define a contact region; etching said residual portion of said second silicon nitride layer, said silicon layer and said first silicon nitride layer to from a contact hole; forming a second metal layer on said doped silicon layer, said residual portion of said second silicon nitride layer and in said contact hole; forming a third metal layer on said second metal layer; performing a thermal process to form silicide at the interface between said doped silicon layer and said second metal layer; patterning a third positive photoresist on said third metal layer; etching said third metal layer using said third positive photoresist as a mask; removing said third positive photoresist; etching said second metal layer using said etched third metal layer as a mask, thereby forming source and drain regions; etching said silicon layer and doped silicon layer to define an island pattern; and forming a passivation layer over said glass substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification