Method for tuning the work function of a metal gate of the pmos device

A method for tuning the work function of a metal gate of the PMOS device, comprising, after formation of a device isolation, the steps of

• 1) cleaning a silicon substrate with the device isolation formed therein;
• 2) performing rapid thermal oxidation at about 600-900° C. for about 20-120 seconds, so as to form an interface layer of SiOx or SiON at the surface of the silicon substrate;
• 3) forming a high-k gate dielectric layer on the interface layer by physical vapor deposition, wherein a Hf—La target and a Hf target are sputtered alternatively in a magnetron reactive sputtering process for deposition of HfLaON, or a Hf target and a Si target are sputtered alternatively in a magnetron reactive sputtering process for deposition of HfSiON, and the high-k gate dielectric layer having different compositions and thicknesses is obtained by adjusting sputtering power or duration for alternative sputtering;
• 4) performing rapid thermal annealing at about 600-1050° C. for about 10-120 seconds;
• 5) forming a metal gate on the gate dielectric layer by physical vapor deposition, wherein a metal nitride gate is deposited in a magnetron reactive sputtering process;
• 6) doping the metal nitride gate by ion implantation of p-type ions;
• 7) etching to form the metal gate gate stack;
• 8) performing thermal annealing at about 350-1050° C.;
• 9) forming back-side ohmic contacts by physical vapor deposition, wherein an Al—Si layer is deposited on the back side by a direct current sputtering process;
• 10) alloying the resulting structure by annealing in an alloying oven in N2 gas or forming gas at about 380-450 ° C. for about 30-60 minutes.