Source/Drain Structure of Semiconductor Device and Method of Forming Same

A device comprising:

• a semiconductor fin extending from a substrate;
• a gate stack extending along sidewalls and a top surface of the semiconductor fin;
• and
• a source/drain region extending into the semiconductor fin adjacent to the gate stack, the source/drain region comprising:
• a first region in an interior of the source/drain region, the first region having a first dopant concentration;
• a second region surrounding the first region, the second region having a second dopant concentration less than the first dopant concentration;
• and
• a third region surrounding the second region, the third region having a third dopant concentration less than the second dopant concentration.

A device comprising:

• a semiconductor fin protruding from a substrate;
• a gate stack over the semiconductor fin;
• a source/drain region in the semiconductor fin, wherein the source/drain region comprises:
• an epitaxial semiconductor material in the semiconductor fin;
• and
• a doped region in the semiconductor fin along an interface between the epitaxial semiconductor material and the semiconductor fin, wherein the epitaxial semiconductor material and the doped region extend into the semiconductor fin to a same depth.

A device comprising:

• a semiconductor fin extending from a substrate;
• a gate stack extending along sidewalls and a top surface of the semiconductor fin;
• gate spacers along sidewalls of the gate stack;
• and
• a source/drain region extending into the semiconductor fin adjacent to the gate stack, the source/drain region comprising:
• an epitaxial semiconductor material;
• a first region in an interior of the source/drain region, the first region having a first dopant concentration;
• a second region surrounding the first region, the second region having a second dopant concentration less than the first dopant concentration;
• a third region surrounding the second region, the third region having a third dopant concentration less than the second dopant concentration;
• and
• a doped region in the semiconductor fin along an interface between the epitaxial semiconductor material and the semiconductor fin.