DIFFERENT LIGHTLY DOPED DRAIN LENGTH CONTROL FOR SELF-ALIGN LIGHT DRAIN DOPING PROCESS

摘要

A method is provided for fabricating thin-film transistors (TFTs) for an LCD having an array of pixels. The method includes depositing a first photoresist layer over a portion of a TFT stack. The TFT stack includes a conductive gate layer, and a semiconductor layer. The method also includes doping the exposed semiconductor layer with a first doping dose. The method further includes etching a portion of the conductive gate layer to expose a portion of the semiconductor layer, and doping the exposed portion of the semiconductor layer with a second doping dose. The method also includes removing the first photoresist layer, and depositing a second photoresist layer over a first portion of the doped semiconductor layer in an active area of the pixels to expose a second portion of the doped semiconductor layer in an area surrounding the active area. The method further includes doping the second portion of the doped semiconductor layer with a third doping dose, the first dose being higher than the second dose and the third dose.

主权项

1. A method of fabricating thin-film transistors (TFTs) for a liquid crystal display (LCD) having an array of pixels, the method comprising:
placing a first photoresist mask over a TFT stack including a conductive gate layer, and a semiconductor layer, the mask having a thicker portion of photoresist covering a pixel area, and the mask having a half tone mask with a thicker portion of photoresist and a thinner portion of photoresist near edge covering an area surrounding the pixel area; ashing a top portion of the first photoresist such that the thinner portion of the photoresist is removed; etching a portion of the conductive gate layer to expose a portion of the semiconductor layer; anddoping the semiconductor layer with a first doping dose such that a length of light drain doping (LDD) region in the pixel area is shorter than a length of the LDD in the area surrounding the pixel area.