Gate structures having sidewall spacers formed using selective deposition

Abstract

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 stackhaving a sidewall is formed over the gate dielectric layer. The gate stackcomprises a conductive layerand a hard maskoverlying the conductive layer. A lineris selectively deposited over the gate stacksuch that the lineris deposited on the hard maskat a rate lower than the rate of deposition on the conductive layer. Thus, the lineris substantially thinner on the hard maskthan on the conductive layer. A nitride spacer is formed overthe liner. A PMD layer is formed over the resultant structure, filling the gaps between adjacent gate stacks.