A method includes depositing a contact etch stop layer (CESL) over a gate, a source/drain (S/D) region and an isolation feature. The method includes performing a first chemical mechanical planarization (CMP) to expose the gate. The method further includes performing a second CMP using a slurry different from the first CMP to expose the CESL over the S/D region, wherein, following the second CMP, an entire top surface of the CESL over the S/D region and over the isolation feature is substantially level with a top surface of the gate.