Source/drain epitaxial layer profile

A method, comprising:

• forming an isolation region on side surfaces of a fin structure;
• forming a gate structure on a first portion of the fin structure;
• forming a first masking structure to cover the gate structure and a second portion of the fin structure, wherein the second portion is wider than the first portion;
• forming a germanium-doped (Ge-doped) region in a third portion of the fin structure, wherein the third portion of the fin structure extends between the first masking structure and the isolation region;
• forming a second masking structure to cover the isolation region and an area of the Ge-doped region in the third portion of the fin structure adjacent to the isolation region;
• removing the Ge-doped region in the third portion of the fin structure between the gate structure and the second masking structure to form an opening in the fin structure;
• and
• growing an epitaxial stack in the opening, wherein the epitaxial stack is in contact with the area of the Ge-doped region in the third portion of the fin structure.

A method, comprising:

• forming an isolation region adjacent to a semiconductor layer;
• forming a gate structure on the semiconductor layer;
• forming a germanium-doped (Ge-doped) region in the semiconductor layer between the gate structure and the isolation region;
• etching a first portion of the Ge-doped region in the semiconductor layer to form an opening, wherein a second portion of the Ge-doped region remains between the opening and the isolation region;
• and
• forming an epitaxial stack in the opening abutting the second portion of the Ge-doped region in the semiconductor layer.