MOS field effect transistor structure and method of manufacture

A method of manufacturing a metal-oxide-semiconductor field effect (MOSFET) device. A substrate having an isolating structure thereon is provided. A gate dielectric layer and a conductive layer are sequentially formed over the substrate. The conductive layer and the gate dielectric layer are patterned to form a gate structure. A low dielectric constant material spacer is formed on the sidewall of the gate structure. A source drain region is formed in the substrate on each side of the gate structure.