Method for fabricating a self-aligned thin-film transistor utilizing planarization and back-side photoresist exposure

摘要

A method for fabricating self-aligned thin-film transistors (TFTs) includes the steps of: exposing a backside substrate surface, opposite to a principal substrate surface, to ultra-violet (UV) light to cause exposure of at least a photoresist layer portion which corresponds substantially to an area outside the shadow of a gate electrode formed on the principal substrate surface; developing the exposed photoresist portion to form a mask; etching a second insulation layer segment, using the mask, to form a remaining insulation layer segment, which is aligned with the gate electrode, and narrower than the gate electrode by a selected overlap distance, on each side thereof; and forming source and drain electrodes on a doped semiconductor layer which each overlap the gate electrode by the selected overlap distance. The overlap distance is a function of the UV exposure time, the photoresist development time and the etch time of the second insulation layer.