Multi-gate devices and method of fabricating the same

A semiconductor device, comprising:

• a semiconductor substrate comprising a first fin and a second fin, wherein the first fin has a first width less than a second width of the second fin;
• an isolation feature around the first fin and the second fin, wherein a surface of the isolation feature around the first fin is lower than a second surface of the isolation feature around the second fin;
• a plurality of gate stack over the first fin and the second fin;
• and
• a plurality of first source/drain (S/D) features on the first fin and a plurality of second source/drain (S/D) features on the second fin.

A method of manufacturing a multi-gate device, comprising:

• providing a semiconductor substrate, wherein the semiconductor substrate has a first fin and a second fin, the first fin has a first width less than a second width of the second fin;
• forming a plurality of semiconductor nanosheets on the first fin and the second fin;
• performing a selectively etching process to remove a portion of the first fin so that a top surface of the first fin is lower than a top surface of the second fin;
• forming an epitaxial source/drain (S/D) feature on the first fin and the second fin and abutting the plurality of semiconductor nanosheets;
• and
• forming a gate structure wrapping each of the plurality of semiconductor nanosheets.