Patent ID: 7109075

Claim:
A method for fabrication of a low temperature polycrystalline silicon thin film transistor comprising the steps of: a) selecting a substrate; b) forming a buffer oxide on the substrate; c) depositing a first amorphous silicon film on the buffer oxide, the first amorphous silicon film being an active layer; d) depositing a low-temperature oxide on the first amorphous silicon film; e) forming a hard mask being a photoresist on the low temperature oxide; f) etching the buffer oxide utilizing a wet isotropic etching process: g) depositing a second amorphous silicon film on the active layer; h) forming a polysilicon spacer on either side of the active layer by dry etching; and i) forming large silicon grain structures in the active layer by annealing and recrystallization of an dog-bone shaped portion of the active layer utilizing one of a high-energy continuous wavelength laser and an excimer laser and recrystallizing the active layer as a polycrystalline silicon, wherein the low temperature oxide being a stop layer for the first amorphous silicon film during the dry etching process, a thermal insulating layer and a hard mask for the first amorphous silicon film during laser annealing thereby protecting the polysilicon spacer from removal.