Multi-stage preheat high-temperature anneal processes after the deposition of the gate dielectric layer(s) reduce the number of interfacial sites and improve the negative bias temperature instability (NTBI) performance of a p-type metal-oxide-semiconductor transistor (PMOS). The gate dielectric layers may include an interfacial oxide layer and a high-k dielectric layer. The multi-stage preheat is designed to reduce dopant deactivation and to improve inter-mixing between the interfacial oxide layer and the high-k dielectric layer. The high-temperature anneal is used to reduce the number of interfacial sites at the interface between the silicon substrate and the interfacial oxide layer.