Method for manufacturing stack structure of PMOS device and adjusting gate work function

A method for manufacturing a gate stack structure and adjusting a gate work function for a PMOS device, comprising:

• 1) growing an interface oxide or oxynitride layer on a semiconductor substrate after conventional LOCOS or STI dielectric isolation is completed;
• 2) forming a high-K gate dielectric film on the interface oxide or oxynitride layer and performing thermal annealing at about 500-1020° C. for about 4-120 seconds;
• 3) depositing a metal gate comprising a first TiN layer, an Al film, and a second TiN layer in sequence;
• 4) depositing a barrier metal layer on the metal gate;
• 5) depositing a polysilicon film and a hard mask on the barrier metal layer by low-pressure chemical vapor deposition and then performing photolithography and etching the hard mask;
• 6) removing photoresist and etching the polysilicon film, the barrier metal layer, the metal gate, the high-K gate dielectric, and the interface SiO2 in sequence using the hard mask to form a gate stack structure;
• 7) forming first spacers and performing source/drain extension region low-energy ion implantation and large-angle implantation;
• 8) forming second spacers and performing source/drain region ion implantation;
• 9) performing rapid thermal annealing in N2 at about 600-1050° C. for about 2-30 seconds, whereby while source/drain dopants are activated, metal Al ions from the Al film are driven to an interface between the high-K gate dielectric film and the interface oxide or oxynitride layer and Al—O dipoles are generated by interfacial reaction thereby adjusting the effective work function of the metal gate of the PMOS device;
• 10) forming a NiSi film;
• and
• 11) forming contacts on the NiSi film and metalizing by alloying annealing in N2 or (N2+H2) in an alloying furnace at about 380-430° C. for about 30-60 minutes.