Isolation features and methods of fabricating the same

A semiconductor device, comprising:

• a first fin structure and a second fin structure each extending from a substrate;
• a first gate segment over the first fin structure;
• a second gate segment over the second fin structure;
• a first isolation feature between and in contact with the first gate segment and the second gate segment, the first isolation feature comprising a silicon oxide layer lined by a silicon nitride layer;
• a first source/drain (S/D) feature over the first fin structure and adjacent to the first gate segment;
• a second S/D feature over the second fin structure and adjacent to the second gate segment;
• and
• a source/drain (S/D) contact disposed over the first S/D feature and the second S/D feature,
• wherein a portion of the S/D contact extends between the first S/D feature and the second S/D feature,
• wherein the first and second gate segments each comprises a dielectric layer and a conductive layer,
• wherein the dielectric layer is not in contact with silicon nitride layer of the first isolation feature, and
• wherein the conductive layer is in contact with silicon nitride of the first isolation feature.

A semiconductor device, comprising:

• a first fin structure, a second fin structure, a third fin structure, and a fourth fin structure each extending from a substrate;
• a first gate segment over the first fin structure and second fin structure;
• a second gate segment over the third fin structure and the fourth fin structure;
• a first isolation feature between the first gate segment and the second gate segment, the first isolation feature comprising an oxygen-containing dielectric layer and an oxygen-free dielectric layer;
• a first source/drain (S/D) feature over the first fin structure and the second fin structure;
• a second S/D feature over the third fin structure and the fourth fin structure;
• and
• a source/drain (S/D) contact disposed over the first S/D feature and the second S/D feature,
• wherein a portion of the S/D contact extends between the first S/D feature and the second S/D feature,
• wherein the first and second gate segments each comprises a dielectric layer and a conductive layer,
• wherein the dielectric layer of the first and second gate segments is in direct contact with the oxygen-containing dielectric layer and the conductive layer of the first and second gate segments is in direct contact with the oxygen-free dielectric layer.