Fabrication of thin film transistor-liquid crystal display with self-aligned transparent conducting layers

A method of forming a thin film transistor-liquid crystal display (TFT-LCD) with self-aligned transparent conducting layers over a substrate, said method comprises the following steps of:

• forming a first metal layer on said substrate to define a gate structure and a storage capacitor electrode;
• forming an insulating layer on said first metal layer and said substrate;
• forming an active layer on said insulating layer to cover said gate structure;
• forming a contact layer on said active layer;
• forming a second metal layer on said contact layer, said active layer, and said insulating layer for defining source/drain(S/D) structures;
• forming a passivation layer on said second metal layer, said active layer and said insulating layer, wherein said passivation layer with a contact hole to expose a surface of said S/D structures;
• forming a transparent conducting layer on said passivation layer and said surface of said S/D structures;
• forming a negative photoresist on said transparent conducting layer;
• performing a front-side exposure and a back-side exposure to define said negative photoresist;
• removing unexposed negative photoresist;
• and
• etching said transparent conducting layer by using said residual negative photoresist as a mask.

A method of forming a thin film transistor-liquid crystal display (TFT-LCD) with self-aligned transparent conducting layers over a substrate, said method comprises the following steps of:

• forming a first metal layer on said substrate to define a gate structure and a storage capacitor electrode;
• forming an insulating layer on said first metal layer and said substrate;
• forming an a-silicon layer on said insulating layer to cover said gate structure;
• forming a doped silicon layer on said a-silicon layer;
• forming a second metal layer on said doped silicon layer, said a-silicon layer, and said insulating layer for defining source/drain(S/D) structures and data lines;
• forming a passivation layer on said second metal layer, said a-silicon layer, and said insulating layer, wherein said passivation layer with a contact hole to expose a surface of said S/D structures;
• forming a transparent conducting layer on said passivation layer and said surface of said S/D structures;
• forming a negative photoresist on said transparent conducting layer;
• performing a front-side exposure to define said negative photoresist by using a first photomask, and performing a back-side exposure by using said first metal layer and said second metal layer as a second photomask to define said negative photoresist, wherein said first photomask having openings corresponding to said contact hole and said storage capacitor electrode;
• removing a portion of said negative photoresist;
• and
• etching said transparent conducting layer by using said residual negative photoresist as a mask, wherein an edge of said transparent conducting layer being aligned to an edge of said data lines.