Process techniques and electrical characterization for high-k (HfO/sub x/N/sub y/) gate dielectric in MOS devices

• Published in: Proceedings. 7th International Conference on Solid-State and Integrated Circuits Technology, 2004 Vol. 1; pp. 372 - 377 vol.1
• Main Authors: Kuei-Shu Chang-Liao, Chun-Yuan Lu, Chin-Lung Cheng, Tien-Ko Wang
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2004
• Subjects: Dielectric devices; Electron traps; Hafnium oxide; High K dielectric materials; High-K gate dielectrics; Leakage current; Nitrogen; Sputtering; Stress; Tunneling
• ISBN: 078038511X; 9780780385115
• DOI: 10.1109/ICSICT.2004.1435029

Effects of nitrogen concentration profiles in HfO/sub x/N/sub y/ on the electrical properties of metal-oxide-semiconductor (MOS) devices were investigated. The nitrogen concentration profiles in HfO/sub x/N/sub y/ gate dielectric was adjusted by sputtering the Hf target in ambient of modulated nitrogen flow. The trapped charges in HfO/sub x/N/sub y/ dielectric are positive. The current-conduction mechanisms of HfO/sub x/N/sub y/ film at the low- and high-electrical field are dominated by Schottky emission and Frenkel-Poole emission, respectively. The mechanism relevant to the relatively larger stress induced leakage current (SILC) at low electrical fields can be explained by the trap-assisted tunneling. On the other hand, the relatively smaller leakage current found at high electric fields can be attributed to the electron trapping in bulk defects. Smaller flat-band voltage shift and SILC are observed for devices with HfO/sub x/N/sub y/ dielectric containing more nitrogen at the dielectric/Si interface or/and less bulk nitrogen, which can be attributed to less interface strain/stress and bulk trap. Electrical characterization of high-k MOSFET was performed by charge-pumping and charge separation techniques. Some interesting results are quite different from those generally observed in SiO: MOSFETs.