A method for fabricating a thin film transistor for an LCD device, comprising:
- forming a semiconductor layer on an entire surface of a substrate, the substrate containing a pixel portion in which a first device is to be formed and a driving circuit portion in which a second and a third device are to be formed;
- forming using at most six mask processes a first photoresist pattern on the semiconductor layer of the first device, the entire second device, and a gate forming region of the third device;
- doping the semiconductor layer of the third device with a first impurity using the first photoresist pattern as a mask;
- removing the first photoresist pattern and forming a second photoresist pattern on a gate forming region of the first device, a gate forming region of the second device, and a part of the third device;
- doping the semiconductor layer of the first and second devices with a second impurity using the second photoresist pattern as a mask;
- forming a conductive layer and a photoresist on an entire surface of the substrate and then partially etching the photoresist by a diffraction exposure to form a third photoresist pattern;
- patterning the conductive layer and the semiconductor layer using the third photoresist pattern as a mask to define source and drain regions and an active region;
- etching the diffraction-exposed third photoresist pattern positioned at channel regions of the first, second and third devices to expose the conductive layer;
- etching the conductive layer using the third photoresist pattern as a mask to form a source and drain of the first, second, and third devices;
- removing the third photoresist pattern and then forming a gate insulating layer on an entire surface of the substrate;
- forming a gate conductive layer on the gate insulating layer and then forming a fourth photoresist pattern on the gate conductive layer;
- etching the gate conductive layer using the fourth photoresist pattern as a mask to form gates of the first, second, and third devices;
- removing the fourth photoresist pattern and then forming a passivation film on an entire surface of the substrate;
- forming a fifth photoresist pattern on the passivation film and then etching the passivation film using the fifth photoresist pattern as a mask to expose the source or drain of the first device;
- removing the fifth photoresist pattern and then forming a transparent electrode layer on the passivation film, the transparent electrode connected to the source or drain of the first device;
- and
- forming a sixth photoresist pattern on the transparent electrode and then etching the transparent electrode layer using the sixth photoresist pattern as a mask to form a pixel electrode.