Non-uniform channel junction-less transistor

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.