Mitigation of gate to contact capacitance in cmos flow

Abstract

Sidewall spacers that are primarily oxide, instead of nitride, are formed adjacent to a gate stack of a CMOS transistor. Individual sidewall spacers are situated between a conductive gate electrode of the gate stack and a conductive contact of the transistor. As such, a capacitance can develop between the gate electrode and the contact, depending on the dielectric constant of the interposed sidewall spacer. Accordingly, forming sidewall spacers out of oxide, which has a lower dielectric constant than nitride, mitigates capacitance that can otherwise develop between these features. Such capacitance is undesirable, at least, because it can inhibit transistor switching speeds. Accordingly, fashioning sidewall spacers as described herein can mitigate yield loss by reducing the number of devices that have unsatisfactory switching speeds and/or other undesirable performance characteristics.