Dual workfunction Ni-Silicide/HfSiON gate stacks by phase-controlled full-silicidation (PC-FUSI) technique for 45nm-node LSTP and LOP devices

• Main Authors: Takahashi, K., Manabe, K., Ikarashi, T., Ikarashi, N., Hase, T., Yoshihara, T., Watanabe, H., Tatsumi, T., Mochizuki, Y.
• Format: Conference Proceeding
• Language: English
• Subjects: Annealing; Applied sciences; Capacitance-voltage characteristics; Control systems; Design. Technologies. Operation analysis. Testing; Dielectrics; Electronics; Exact sciences and technology; Integrated circuits; Laboratories; MOS devices; National electric code; Phase control; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicidation; Silicides; Transistors
• DOI: 10.1109/IEDM.2004.1419074

We present a new threshold-voltage (Vth) control technique for fully-silicided (FUSI) metal/high-k gate stacks which are suitable for 45nm-node LOP and LSTP CMOS. The key is the phase control of FUSI Ni-silicide by changing Ni film thickness prior to silicidation anneal. As a result, Ni/sub 3/Si and NiSi/sub 2/ are formed whose effective workfunctions (WFs) on HfSiON are found to be 4.8eV and 4.4eV, respectively, being largely displaced from Si-midgap by /spl plusmn/0.2eV. Meanwhile, the dopant segregation method, known to be successful in Vth-control of NiSi on SiO/sub 2/, did not work on HfSiON. With Ni/sub 3/Si-PMOS and NiSi/sub 2/-NMOS transistors, a wide range of Vth-tuning is achieved coping with both LSTP and LOP requirements. At the same time, leakage suppression merit is better than the 45nm-node targets at electrical thickness (Tinv) around 2.0 nm. Also, our phase-controlled fully silicided (PC-FUSI) devices show excellent mobility characteristics.