A semiconductor device with an isolation feature is disclosed. The semiconductor device includes a plurality of gate structures disposed on a semiconductor substrate, a plurality of gate sidewall spacers of a dielectric material formed on respective sidewalls of the plurality of gate structures, an interlayer dielectric (ILD) disposed on the semiconductor substrate and the gate structures, an isolation feature embedded in the semiconductor substrate and extended to the ILD and a sidewall spacer of the dielectric material disposed on sidewalls of extended portion of the isolation feature.