Method of fabricating thin-film transistor

A method of fabricating a thin-film transistor, comprising:

• providing an insulation substrate;
• forming a first conductive layer on the insulation substrate;
• patterning the first conductive layer to form a gate and a gate line on the conductive layer by performing a first step of photolithography and etching;
• forming a gate dielectric layer, a silicon layer, a doped silicon layer and a second conductive layer over the insulation substrate in sequence;
• performing a second step of photolithography and etching on the a silicon layer, a doped silicon layer and a second conductive layer, so that a source/drain line is formed, and remaining portions of the second conductive layer, the doped silicon layer and the silicon layer are aligned over the gate;
• forming a transparent conductive layer on the insulation substrate;
• performing a third step of photolithography and etching on the transparent conductive layer, the remaining portions of the second conductive layer, the remaining portions of the doped silicon layer and the remaining portions of the doped silicon layer to form a pixel electrode, a source/drain conductive layer and a source/drain region;
• forming a protection layer over the substrate;
• and
• performing a fourth step of photolithography and etching to expose a portion of the pixel electrode.