Tzu-Chen Wang

Thermal stability of Hf/sub x/Ta/sub y/N metal gate electrodes for advanced MOS devices

In this letter, the composition effects of hafnium (Hf) and tantalum (Ta) in Hf/sub x/Ta/sub y/N metal gate on the thermal stability of MOS devices were investigated. The work function of the Hf/sub x/Ta/sub y/N metal gate can reach a value of /spl sim/4.6 eV (midgap of silicon) by suitably adjusting the Hf and Ta compositions. In addition, with a small amount of Hf incorporated into a TaN metal gate, excellent thermal stability of electrical properties, including the work function, the equivalent oxide thickness, interface trap density and defect generation rate characteristics, can be achieved after a post-metal anneal up to 950/spl deg/C for 45 s. Experimental results indicate that Ta-rich Hf/sub x/Ta/sub y/N is a promising metal gate for advanced MOS devices.

HfxTayNz Metal Gate Electrodes for Advanced MOS Devices Applications

With a small amount of hafnium (Hf) incorporated into tantalum nitride (TaN) metal gate, excellent thermal stability of electrical properties can be achieved up to post-metal anneal at 950 degC for 45 s. Besides, a work function tuning range from 4.2 to 4.6 eV can be obtained by suitably adjusting nitrogen (N) concentration in Hfx TayNz metal gate

Effects of nitrogen incorporation by plasma immersion ion implantation on electrical characteristics of high-k gated MOS devices

The electrical characteristics of high-k gated MOS devices can be improved by a nitridation treatment using plasma immersion ion implantation (PHI). The suitable process conditions for PHI treatment are at a low ion energy and with a short implantation time.

Reliability and Thermal Stability of Clustered Vertical Furnace-Grown

Native oxides at the Si surface on the electrical properties of MOS devices are crucial problems. To study these issues, the thermal stability and electrical characteristics of MOS devices with clustered vertical furnace-grown, native oxide-free, ultrathin gate oxides and Hf xTayN metal gates were investigated. Postmetallization annealing (PMA) was carried out to study the metal-diffusion effects. Time-of-flight secondary ion mass spectroscopy analysis results show that the diffusion depths of Hf and Ta in the gate oxide are small and stay almost constant with a PMA temperature of up to 950 degC. Compared to those with conventional horizontal furnace-grown oxides, MOS devices with advanced clustered vertical furnace-grown gate oxides show excellent electrical characteristics, such as equivalent oxide thickness, hysteresis, interface trap density, stress-induced leakage current, defect generation rate, and stress-induced flat-band voltage shift. With an increase in PMA temperature, the electrical characteristics remain almost unchanged, which, in turn, achieve the excellent thermal stability and electrical reliabilities of MOS devices with clustered vertical furnace-grown gate oxides and Hf0.27Ta0.58N0.15 metal gates

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treatment using plasma immersion ion implantation (PIII) Kuei-Shu Chang-Liao*, Ping-Hung Tsai, H.Y. Kao, T.K. Wang, S.F. Huang, W.F. Tsai, and C.F. Ai Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan, R.O.C. Physics Division, Institution of Nuclear Energy Research, Taoyuan, Taiwan, R.O.C. *TEL: (886)-(3)-5742674, FAX: (886)-(3)-5720724, E-mail: Lkschang@ess.nthu.edu.tw