Patent ID: 8487378

Claim:
A semiconductor device, comprising: a semiconductor layer disposed over a substrate, the semiconductor layer having a fin structure; a gate structure disposed over the fin structure, the gate structure having a gate dielectric layer and a gate electrode layer, the gate structure wrapping around a portion of the fin structure; and source/drain regions disposed in the fin structure; wherein a doping profile across the fin structure is non-uniform, and wherein a first region of the portion of the fin structure being wrapped around by the gate structure has a lower doping concentration level than the rest of the fin structure, wherein the fin structure includes the first region, a second region, and a third region, and wherein: the first region has a first doping concentration level; the second region is located adjacent to the first region and partially wrapped around by the gate structure and has a second doping concentration level that is greater than the first doping concentration level; and the third region is located adjacent to the second region but not wrapped around by the gate structure and has a third doping concentration level that is greater than the second doping concentration level, and wherein the first, second, and third regions all have the same doping polarity, wherein the first region physically contacts the second region and the second region physically contacts the third region, and wherein the second region has a substantially uniform second doping concentration that extends laterally within the fin structure from under the gate structure to under a spacer on a sidewall of the gate structure and the third region has a substantially uniform third doping concentration that extends laterally within the fin structure from under the spacer to beyond an outer edge of the spacer away from the gate structure.