Patent ID: 7173283
Filing Date: 2007-02-06
Classification: H01L

Abstract:
1. A portable information terminal having a display device, the display device comprising: a pixel portion formed over a substrate, the pixel portion comprising a first n-channel thin film transistor; and a driver circuit portion formed over the substrate, the driver circuit portion comprising a second n-channel thin film transistor and a p-channel thin film transistor, wherein the second n-channel thin film transistor comprises a first semiconductor layer and a first gate electrode with a first gate insulating film interposed therebetween, wherein the p-channel thin film transistor comprises a second semiconductor layer and a second gate electrode with a second gate insulating film interposed therebetween, wherein a gradient of a side surface with respect to a bottom surface of the first gate electrode is different from that of a side surface with respect to a bottom surface of the second gate electrode, wherein the first n-channel thin film transistor comprises a third semiconductor layer and a third gate electrode with a third gate insulating film interposed therebetween, and wherein a gradient of a side surface with respect to a bottom surface of the third gate electrode is different from that of the side surface with respect to the bottom surface of the first gate electrode.