Method of fabricating a bottom-gate-type thin film transistor using a heat relaxation layer during laser crystallization

摘要

Provided is a constitution for forming a polysilicon film having uniform crystallinity. To construct a structure of a bottom-gate-type TFT, a heat relaxation layer is formed to cover a gate electrode. The heat conductivity of the heat relaxation layer is lower than that of the gate electrode, and it acts to inhibit heat propagation to the gate electrode. In the step of laser crystallization of an amorphous silicon film into a polysilicon film, the heat relaxation layer prevents local temperature gradation in the film owing to the heat-absorbing effect of the underlying gate electrode. The polysilicon film formed has extremely excellent uniformity and crystallinity.