Source/drain epitaxial structures for semicondcutor devices

A method, comprising:

• forming first and second fin structures on a substrate, wherein the first and second fin structures are separated by an isolation layer;
• forming a gate structure on the first and second fin structures;
• forming a spacer layer on the first and second fin structures, the isolation layer, and the gate structure;
• forming a first pair of spacer structures on opposite sidewalls of the first fin structure, wherein the first pair of spacer structures have a first height above the isolation layer;
• forming a first epitaxial structure on the first fin structure and between the first pair of spacer structures, wherein the first epitaxial structure comprises a first type of dopant;
• forming a second pair of spacer structures on opposite sidewalls of the second fin structure, wherein the second pair of spacer structures have a second height above the isolation layer greater than the first height;
• and
• forming a second epitaxial structure on the second fin structure and between the second pair of spacer structures, wherein the second epitaxial structure comprises a second type of dopant different from the first type of dopant.

A semiconductor device, comprising:

• first and second fin structures on a substrate;
• an isolation layer between the first and second fin structures;
• a first epitaxial structure on the first fin structure and a second epitaxial structure on the second fin structure, wherein the first epitaxial structure comprises a first type of dopant and the second epitaxial structure comprises a second type of dopant different from the first type of dopant;
• and
• a first spacer structure adjacent to the first epitaxial structure having a first height above the isolation layer and a second spacer structure adjacent to the second epitaxial structure having a second height above the isolation layer, the first height being less than the second height.