abstract |
A semiconductor device includes a semiconductor substrate, at least one gate stack, a gate spacer and a dielectric cap. The gate stack is located on the semiconductor substrate. The gate spacer is located on a sidewall of the gate stack. The gate spacer includes a first dielectric layer and a second dielectric layer with different etch properties. The dielectric cap at least caps the gate spacer. The dielectric cap and the second dielectric layer define a gap therebetween. |