Method of polycrystallization, method of manufacturing polysilicon thin film transistor, and laser irradiation device therefor
View Patent ↗A device for irradiating a laser beam onto an amorphous silicon thin film formed on a substrate. The device includes: a stage mounting the substrate; a laser oscillator for generating a laser beam; a projection lens for focusing and guiding the laser beam onto the thin film; a reflector for reflecting the laser beam guided onto the thin film; a controller for controlling a position of the reflector, and an absorber for absorbing the laser beam reflected by the reflector.
1. A method of manufacturing a thin film transistor using a laser irradiation device including a projection lens, the method comprising:
depositing an amorphous silicon thin film on a substrate;
irradiating a laser beam from the laser irradiation device onto the thin film
through an exposure mask having a slit pattern to form a polysilicon layer after preheating the projection lens wherein the preheating is performed without irradiating a laser beam from the irradiation device onto the thin film;
patterning the polysilicon layer to form a semiconductor layer;
depositing a first insulating layer on the semiconductor layer, forming a gate electrode on the first insulating layer;
implanting impurities into the semiconductor layer to form source and drain regions;
depositing a second insulating layer on the gate electrode;
forming contact holes exposing the source and the drain regions in the first or the second insulating layers; and
forming source and drain electrodes respectively connected to the source and the drain regions through the contact holes.
2. The method of claim 1 wherein the polysilicon layer is formed by lateral sequential solidification.
3. The method of claim 1 further comprising:
forming a pixel electrode connected to the drain electrode.
4. The method of claim 3 wherein the pixel electrode comprises a transparent conductive material or a reflective conductive material.
5. A method of polycrystallizing an amorphous silicon thin film using a laser irradiation device including a projection lens, the method comprising:
depositing an amorphous silicon thin film on a substrate;
preheating the projection lens without irradiating a laser beam from the laser irradiation device onto the thin film; and
irradiating the laser beam from the laser irradiation device onto the thin film to be polycrystallized after the preheating.
6. The method of claim 5 wherein the laser beam from the laser irradiation device is reflected away from the thin film during the preheating.