Patent ID: 8853796

Claim:
A method of forming a semiconductor device comprising: providing a substrate having a substrate surface, the substrate is prepared with a device region surrounded by an isolation region, the device region serves as a device region of a transistor having a width direction and a length direction, wherein the width direction is a channel width direction of the transistor and the length direction is a channel length direction of the transistor, wherein a length of the channel is between source/drain regions of the transistor, the width and length directions are perpendicular, and the device region includes edge portions along the width direction of the device region and a central portion between the edge portions; and forming a metal gate electrode layer over the surface of the substrate in the device region, the metal gate electrode having a top surface, wherein the metal gate electrode layer comprises a graded thickness along the width direction of the device region, the graded thickness resulting in the top surface of the metal gate electrode having an uneven height with respect to the substrate surface, wherein a thickness T E at edge portions of the device region along the width direction with respect to the substrate surface is thinner than a thickness T C at the central portion of the device region.