Patent ID: 8492212

Claim:
A manufacture method of a thin film transistor formed on an insulating substrate, comprising: a gate electrode forming step of forming a gate electrode on a first main surface of the insulating substrate; a gate insulating film forming step of forming a gate insulating film so as to cover the insulating substrate that includes the gate electrode; a semiconductor film forming step of forming a semiconductor film on the gate insulating film, wherein the semiconductor film forming step includes an oxide film forming step of forming an oxide film on the semiconductor film; a first resist pattern forming step of forming a first resist pattern on the oxide film; an impurity region forming step of forming an impurity region in the semiconductor film by implanting impurity ions of one of first and second conductive types with a first dose amount to the semiconductor film using the first resist pattern as a mask; an etching stopper layer forming step of forming an etching stopper layer on the semiconductor film that faces the gate electrode, wherein the etching stopper layer forming step includes: an oxide film removing step of removing the oxide film on the semiconductor film using the first resist pattern as a mask, leaving the oxide film beneath the first resist pattern intact, a nitride film forming step of, after removing the first resist pattern, forming a nitride film on the remaining oxide film, a second resist pattern forming step of forming a second resist pattern on the nitride film, and an etching step of etching the nitride film using the second resist pattern as a mask; and a source/drain region forming step of implanting impurity ions of the one of the conductive types to the semiconductor film with a second dose amount that is larger than the first dose amount using the etching stopper layer as a mask to form a source region and a drain region in the semiconductor film with higher impurity concentration than the impurity region and to form electric field reduced regions in the impurity region that is sandwiched between the source region and the drain region.