Semiconductor devices and methods of manufacturing thereof

A semiconductor device, comprising:

• a semiconductor fin extending along a first lateral direction;
• a gate structure extending along a second lateral direction and straddling the semiconductor fin, the first lateral direction perpendicular to the first lateral direction;
• an epitaxial structure disposed in the semiconductor fin and next to the gate structure;
• a first interconnect structure extending along the second lateral direction and disposed above the epitaxial structure;
• and
• a dielectric layer comprising a first portion and a second portion that form a stair.

A method for fabricating a semiconductor device, comprising:

• forming a first metal structure overlaid by a dielectric capping layer that contains nitrogen;
• forming a second metal structure next to the first metal structure;
• growing a dielectric layer comprising a thicker portion that overlays the nitrogen-containing dielectric capping layer and a thinner portion that overlays a surface that contains no nitrogen;
• and
• forming an interconnect structure electrically coupled to second metal structure.