Dielectric structures for semiconductor device structures

Abstract

An interconnect fabrication method is disclosed herein that utilizes a disposable etch stop hard mask over a gate structure during source/drain contact formation and replaces the disposable etch stop hard mask with a dielectric feature (in some embodiments, dielectric layers having a lower dielectric constant than a dielectric constant of dielectric layers of the disposable etch stop hard mask) before gate contact formation. An exemplary device includes a contact etch stop layer (CESL) having a first sidewall CESL portion and a second sidewall CESL portion separated by a spacing and a dielectric feature disposed over a gate structure, where the dielectric feature and the gate structure fill the spacing between the first sidewall CESL portion and the second sidewall CESL portion. The dielectric feature includes a bulk dielectric over a dielectric liner. The dielectric liner separates the bulk dielectric from the gate structure and the CESL.