Patent ID: 7859078

Claim:
A thin film transistor device comprising: a substrate; a first n-type thin film transistor and a first p-type thin film transistor each of which is formed on the substrate and applying a first insulating film as a gate insulating film; and a second n-type thin film transistor and a second p-type thin film transistor each of which is formed on the substrate and applying a laminated film of the first insulating film and a second insulating film as a gate insulating film; wherein a gate electrode of each of the second n-type thin film transistor and the second p-type thin film transistor is made of a conductive material having lower resistance and a lower melting point than a gate electrode of each of the first n-type thin film transistor and the first p-type thin film transistor, wherein the gate electrode of each of the first n-type thin film transistor and the first p-type thin film transistor is made of metal including any one element of titanium, chromium, tungsten and tantalum as a main component, and the gate electrode of each of the second n-type thin film transistor and the second p-type thin film transistor is made of metal including any one element of silver and copper as a main component, and wherein each of the first n-type thin film transistor and the first p-type thin film transistor does not include a lightly doped drain region, the second n-type thin film transistor includes the lightly doped drain region, and the second p-type thin film transistor includes an offset region made of semiconductor not doped with an impurity which is located between a high density impurity region constituting a source and a drain, and a channel region.