Self-aligned metal gate for multigate device

A device comprising:

• a fin portion disposed between a first isolation feature and a second isolation feature, wherein the first isolation feature is different than the second isolation feature;
• a first dielectric fin disposed over the first isolation feature and a second dielectric fin disposed over the second isolation feature, wherein the first dielectric fin is different than the second dielectric fin;
• and
• a multigate device having a channel layer, a metal gate that wraps the channel layer, and source/drain features, wherein:
• the channel layer extends along a first direction between the source/drain features and along a second direction between the first dielectric fin and the second dielectric fin, the second direction being different than the first direction, and
• the metal gate and the channel layer each physically contact the first dielectric fin and the metal gate is disposed between and separates the channel layer from the second dielectric fin.

A method comprising:

• forming a multigate device having a channel layer, a metal gate that wraps the channel layer, and source/drain features over a substrate, wherein the channel layer extends along a first direction between the source/drain features;
• and
• forming a first dielectric fin and a second dielectric fin over the substrate, wherein:
• the channel layer extends along a second direction between the first dielectric fin and the second dielectric fin, wherein the second direction is different than the first direction,
• the metal gate and the channel layer each physically contact the first dielectric fin and the metal gate is disposed between the channel layer and the second dielectric fin, and
• the first dielectric fin is different than the second dielectric fin.