RF switch device with a sidewall spacer having a low dielectric constant

An integrated circuit (IC) comprising:

• a semiconductor-on-insulator (SOI) substrate comprising a device layer overlying an insulator layer and a high resistivity layer underlying the insulator layer;
• a pair of source/drain regions in the device layer;
• a gate dielectric layer on the device layer and laterally between the source/drain regions;
• a gate electrode overlying the gate dielectric layer;
• a sidewall liner disposed along sidewalls of the gate electrode and along an upper surface of the device layer;
• and
• a sidewall spacer overlying the device layer on sidewalls and an upper surface of the sidewall liner, wherein the sidewall spacer has a pair of segments respectively on opposite sides of the gate electrode, wherein the sidewall spacer has a dielectric constant less than 6, and wherein the dielectric constant of the sidewall spacer is greater than that of the sidewall liner and greater than that of the insulator layer.

An integrated circuit (IC) comprising:

• a semiconductor-on-insulator (SOI) substrate comprising a device layer overlying an insulator layer and a high resistivity layer underlying the insulator layer;
• a pair of source/drain regions in the device layer;
• a gate dielectric layer on the device layer and laterally between the source/drain regions;
• a gate electrode overlying the gate dielectric layer;
• an interconnect structure overlying the gate electrode, wherein the interconnect structure comprises a conductive wire overlying a dielectric protection layer, wherein the conductive wire is electrically coupled to the gate electrode;
• and
• a sidewall spacer overlying the device layer and disposed on sidewalls of the gate electrode, wherein the sidewall spacer has a dielectric constant greater than that of the insulator layer and less than that of the dielectric protection layer.