Patent ID: 8048697

Claim:
A method for manufacturing a semiconductor device, comprising: forming a first conductive layer in which a transparent conductive layer and a metal layer are stacked over an insulating substrate; forming a first resist using a first multi-tone mask; etching the transparent conductive layer and the metal layer using the first resist to form a source electrode, a drain electrode, and a pixel region to be a pixel electrode; ashing the first resist so that a part of the first resist is left over the source electrode and the drain electrode; etching the metal layer over the pixel region using the first resist which is left to form the pixel electrode formed of the transparent conductive layer; forming a semiconductor layer having an impurity element which imparts one conductivity type over the insulating substrate; forming a second resist over the source electrode and the drain electrode by backside light exposure and changing a shape of the second resist to cover edge portions of the source electrode and the drain electrode by performing a reflow treatment on the second resist; etching the semiconductor layer having an impurity element which imparts one conductivity type using the second resist; forming a semiconductor layer over the insulating substrate; forming a third resist using a second mask; etching the semiconductor layer having an impurity element which imparts one conductivity type and the semiconductor layer using the third resist to exist between the source electrode and the drain electrode and over the source electrode and the drain electrode; forming a gate insulating film and a conductive film over the insulating substrate; forming a fourth resist using a third multi-tone mask; etching the gate insulating film and the conductive film using the fourth resist to form an island-shaped conductive film; ashing the fourth resist so that a part of the fourth resist is left over the semiconductor layer; etching the island-shaped conductive film using the fourth resist which is left to form a gate electrode; forming a protective film over the insulating substrate; forming a fifth resist over the gate electrode, the source electrode, and the drain electrode by backside light exposure; changing a shape of the fifth resist to cover the gate insulating film by performing a reflow treatment on the fifth resist; and etching the protective film over the pixel electrode using the fifth resist.