Gate cut dielectric feature and method of forming the same

A semiconductor device, comprising:

• a first fin structure and a second fin structure;
• a first gate structure over the first fin structure;
• a second gate structure over the second fin structure;
• and
• a gate cut feature disposed between the first gate structure and the second gate structure, the gate cut feature comprising:
• an oxygen blocking layer in contact with the first gate structure and the second gate structure,
• an oxygen trap layer over the oxygen blocking layer and disposed between the first gate structure and the second gate structure, and
• a silicon oxide layer over the oxygen trap layer and disposed between the first gate structure and the second gate structure,
• wherein a dielectric constant of the oxygen blocking layer is greater than a dielectric constant of the silicon oxide layer,
• wherein the first gate structure and the second gate structure comprise a plurality of metal layers,
• wherein a top surface of the silicon oxide layer is coplanar with top surfaces of the first gate structure and the second gate structure.

A semiconductor structure, comprising:

• a first fin structure extending lengthwise along a first direction;
• a second fin structure extending lengthwise along the first direction;
• an isolation feature separating the first fin structure and the second fin structure along a second direction perpendicular to the first direction;
• a first gate structure over the first fin structure and the isolation feature;
• a second gate structure over the second fin structure and the isolation feature;
• and
• a gate cut feature disposed between the first gate structure and the second gate structure,
• wherein the gate cut feature extends into the isolation feature,
• wherein the first gate structure and the second gate structure comprise a plurality of metal layers,
• wherein a top surface of the gate cut feature is coplanar with top surfaces of the first gate structure and the second gate structure,
• wherein the gate cut feature comprises:
• a silicon nitride layer in contact with the first gate structure and the second gate structure,
• a silicon oxide layer over the silicon nitride layer and disposed between the first gate structure and the second gate structure, and
• an oxygen trap layer separating the silicon nitride layer and the silicon oxide layer.