Display device and method of fabricating the same
A display device and method of fabricating the same are provided. The display device includes a substrate and a thin-film transistor formed on the substrate. The thin-film transistor includes a lower gate conductive layer disposed on the substrate, and a lower gate insulating film disposed on the lower gate conductive layer The lower gate insulating film includes an upper surface and sidewalls. The thin-film transistor includes an active layer disposed on the upper surface of the lower gate insulating film, the active layer including sidewalls. At least one of the sidewalls of the lower gate insulating film and at least one of the sidewalls of the active layer are aligned with each other.
1. A method of fabricating a display device, the method comprising:
forming a buffer layer on a surface of a substrate:
forming an amorphous silicon pattern on the buffer layer;
implanting oxygen into a lower portion of the amorphous silicon pattern; and
dividing the amorphous silicon pattern into which the oxygen is implanted into a lower gate insulating film and an active layer disposed above the lower gate insulating film, the active layer including crystalline silicon, wherein
an oxygen content of the lower gate insulating film is higher than an oxygen content of the buffer layer.
2. The method of claim 1 , wherein the forming of the amorphous silicon pattern on the substrate includes:
forming an amorphous silicon layer on the substrate, and
patterning the amorphous silicon layer to form the amorphous silicon pattern.
3. The method of claim 1 , wherein the dividing of the amorphous silicon pattern into which the oxygen is implanted includes:
forming the active layer by crystallizing an upper portion of the amorphous silicon pattern into which the oxygen is implanted; and
forming the lower gate insulating film by heat-treating the lower portion of the amorphous silicon pattern into which the oxygen is implanted.
4. The method of claim 3 , wherein the amorphous silicon pattern is formed directly on the buffer layer.
5. The method of claim 4 , wherein the buffer layer includes silicon oxide, (SiOx).
6. The method of claim 5 , wherein the lower gate insulating film is denser than in the buffer layer such that bonds of silicon atoms and oxygen atoms are higher in the lower gate insulating film.
7. The method of claim 1 , wherein the dividing of the amorphous silicon pattern includes forming the active layer above the lower gate insulating film to completely cover an upper surface of the lower gate insulating film.
8. The method of claim 7 , wherein the forming of the active layer includes aligning at least one of side walls of the active layer with at least one of sidewalls of the lower gate insulating film.
9. The method of claim 1 , further comprising heat-treating the lower gate insulating film after the dividing of the amorphous silicon pattern into which the oxygen may be implanted.
10. The method of claim 1 , wherein the lower gate insulating film is denser than in the buffer layer such that bonds of silicon atoms and oxygen atoms are higher in the lower gate insulating film.
11. The method of claim 1 , wherein
the buffer layer is formed as a triple film of silicon oxide (SiOx)/silicon nitride (SiNx)/SiOx,
the lower gate insulating film is made of SiOx, and
the SiOx film of the lower gate insulating film is denser than the SiOx film of the uppermost layer of the buffer layer such that the number of bonds of silicon atoms and oxygen atoms is higher.