A semiconductor structure is disclosed. The semiconductor structure includes first and second metal gates on a substrate with a gap therebetween. The first metal gate has a first sidewall, and the second metal gate has a second sidewall directly facing the first sidewall. A contact etch stop layer (CESL) is disposed within the gap and extends along the first and second sidewalls. The CESL has a first top portion adjacent to a top surface of the first metal gate and a second top portion adjacent to a top surface of the second metal gate. The first top portion and the second top portion have a trapezoid cross-sectional profile. A first sidewall spacer is disposed on the first sidewall and between the CESL and the first metal gate. A second sidewall spacer is disposed on the second sidewall and between the CESL and the second metal gate.