Gate structures having sidewall spacers formed using selective deposition

摘要

Sidewall spacers are disclosed that extend on opposing sidewalls of gate stacks. The sidewall spacers have improved profiles to suppress or eliminate void formation between the gate stacks during gap-filling A gate dielectric layer is formed on a semiconductor substrate. Then, a gate stack 24 having a sidewall is formed over the gate dielectric layer. The gate stack 24 comprises a conductive layer 28 and a hard mask 30 overlying the conductive layer 28 . A liner 32 is selectively deposited over the gate stack 24 such that the liner 32 is deposited on the hard mask 30 at a rate lower than the rate of deposition on the conductive layer 28 . Thus, the liner 32 is substantially thinner on the hard mask 30 than on the conductive layer 28 . A nitride spacer is formed over 34 the liner 32 . A PMD layer is formed over the resultant structure, filling the gaps between adjacent gate stacks.