Semiconductor device having display device

摘要

A semiconductor integrated circuit having a high withstand voltage TFT and a TFT which is capable of operating at high speed in a circuit of thin film transistors (TFT) and methods for fabricating such circuit will be provided. A gate insulating film of the TFT required to operate at high speed (e.g., TFT used for a logic circuit) is relatively thinned less than a gate insulating film of the TFT which is required to have high withstand voltage (e.g., TFT used for switching high voltage signals).

主权项

1. A display device comprising:
a substrate having an insulating surface; a first insulating film comprising silicon oxide formed over the substrate; a semiconductor layer formed on the first insulating film, the semiconductor layer including at least a channel region; a second insulating film comprising silicon oxide formed over the semiconductor layer; a third insulating film comprising silicon nitride formed over the second insulating film; a gate electrode formed over the channel region of the semiconductor layer with the second insulating film and the third insulating film interposed therebetween; and a fourth insulating film comprising silicon nitride formed over the semiconductor layer, the first and second and third insulating films and the gate electrode, wherein the semiconductor layer includes at least one lightly doped impurity region between the channel region and one of the pair of impurity regions, and wherein the lightly doped impurity region overlaps the third insulating film.