Semiconductor device and method of manufacture

A device comprising:

• a gate stack over and along sidewalls of a first semiconductor fin;
• and
• a source/drain region adjacent the gate stack, the source/drain region comprising:
• a first source/drain layer having a germanium concentration in a range from 20 atomic percent to 40 atomic percent;
• a second source/drain layer over the first source/drain layer, the second source/drain layer having a germanium concentration in a range from 40 atomic percent to 50 atomic percent;
• a third source/drain layer over the second source/drain layer, the third source/drain layer having a germanium concentration in a range from 60 atomic percent to 80 atomic percent;
• and
• a fourth source/drain layer over the third source/drain layer, the fourth source/drain layer having a germanium concentration that is less than 40 atomic percent, wherein each of the first source/drain layer, the second source/drain layer, the third source/drain layer and the fourth source/drain layer comprise facets, and wherein a bottommost point of the third source/drain layer and a bottommost point of the fourth source/drain layer are higher than a topmost point of the first source/drain layer.

A device comprising:

• a fin protruding from a substrate;
• a gate stack over a top surface and sidewalls of the fin;
• and
• a source/drain region in the fin, wherein the source/drain region comprises:
• a first semiconductor material having a dopant concentration of less than 5×1020 atoms/cm3;
• a second semiconductor material over the first semiconductor material, the second semiconductor material having a dopant concentration greater than 6×1020 atoms/cm3;
• and
• a third semiconductor material over the second semiconductor material, the third semiconductor material having a dopant concentration greater than 8×1020 atoms/cm3, wherein a first angle between intersecting facets at a top surface of the third semiconductor material is smaller than 90 degrees and larger than a second angle between intersecting facets at a top surface of the second semiconductor material, wherein the first angle is higher than and overlaps the second angle.