Source/drain structure having multi-facet surfaces

A device comprising:

• a substrate having a source/drain region and a gate region;
• a first fin structure and a second fin structure disposed over the substrate, the first fin structure and the second fin structure having a first height in the source/drain region and a second height in the gate region, the second height being different than the first height;
• a gate structure disposed over the first fin structure and the second fin structure in the gate region of the substrate, the gate structure including a gate dielectric physically contacting the first fin structure and the second fin structure having the second height;
• a dielectric isolation structure disposed on the substrate, wherein the first and second fin structures are at least partially embedded within the dielectric isolation structure;
• and
• a source/drain feature disposed over the first fin structure and the second fin structure having the first height in the source/drain region, the source/drain feature including:
• multiple lower semiconductor portions that are separated from each other by the dielectric isolation structure, wherein the multiple lower semiconductor portions physically contact the first fin structure and the second fin structure having the first height in the source/drain region;
• and
• a single upper semiconductor portion disposed over the multiple lower semiconductor portions, wherein the single upper semiconductor portion is merged from the multiple lower semiconductor portions, wherein the single upper portion has a top surface facing away from a top surface of the substrate, wherein the top surface of the single upper portion includes a first multi-facet surface that is disposed directly over the first fin structure having the first height in the source/drain region, wherein the top surface of the single upper portion further includes a flat surface interfacing with the first multi-facet surface, the first multi-facet surface being positioned at a higher level above the substrate than the flat surface and the flat surface being parallel to the top surface of the substrate.

A device comprising:

• a substrate having a source/drain region and a gate region;
• a fin structure disposed over the substrate, the fin structure having a first height in the source/drain region and a second height in the gate region, the second height being different than the first height;
• a gate structure disposed over the fin structure in the gate region of the substrate, the gate structure including a gate dielectric physically contacting the fin structure having the second height in the gate region of the substrate;
• an isolation structure disposed on the substrate;
• and
• a source/drain feature disposed over the fin structure having the first height in the source/drain region, the source/drain feature including:
• multiple lower semiconductor portions that are separated from each other by the isolation structure, wherein one portion of the multiple lower semiconductor portions physically contacts the fin structure having the first height in the source/drain region;
• a single upper semiconductor portion disposed over the multiple lower semiconductor portions, wherein the single upper semiconductor portion is merged from the multiple lower semiconductor portions;
• and
• a semiconductor layer disposed directly on the single upper semiconductor portion, wherein the semiconductor layer has a top surface facing away from a top surface of the substrate, wherein the top surface of the semiconductor layer includes a first multi-facet surface, wherein the semiconductor layer is formed of a different material than the single upper semiconductor portion.