Source/Drain Epitaxial Layers For Transistors

A method, comprising:

• forming a fin structure comprising two end portions and a middle portion between the two end portions;
• forming a gate structure on the middle portion of the fin structure;
• etching the end portions of the fin structure;
• and
• growing source/drain (S/D) epitaxial structures on the etched end portions of the fin structure, wherein growing the S/D epitaxial structures comprises:
• partially growing the S/D epitaxial structures on the etched end portions of the fin structure;
• exposing the partially-grown S/D epitaxial structures to an etching chemistry, wherein the etching chemistry terminates surfaces of the partially-grown S/D epitaxial structures with chlorine atoms to form chlorine-terminated surfaces;
• and
• treating the partially-grown S/D epitaxial structures with hydrogen to replace the chlorine-terminated surfaces with hydrogen-terminated surfaces.

A semiconductor device, comprising:

• a fin structure on a substrate, wherein the fin structure comprises a middle portion and a recessed end portion below the middle portion;
• a pair of spacer structures on sidewalls of the recessed end portion of the fin structure;
• and
• a source/drain (S/D) structure on the recessed end portion of the fin structure, wherein the S/D structure comprises:
• a first facet parallel to (111) crystal planes, wherein a distance between the first facet and a top corner of the middle portion is greater than about 2 nm;
• and
• a second facet adjacent to the first facet and parallel to (100) crystal planes, wherein the second facet is above a top surface of the middle portion.