NMOS Compatible Work Function of TaN Metal Gate With Gadolinium Oxide Buffer Layer on Hf-Based Dielectrics

• Published in: IEEE electron device letters 2006-10, Vol.27 (10), p.802-804
• Main Authors: Thareja, G., Huang Chun Wen, Harris, R., Majhi, P., Byung Hun Lee, Lee, J.C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Buffer layers; Compatibility; Dielectrics; Dipole theory; Electronics; Exact sciences and technology; Fabrication; Gadolinium; Gadolinium oxides; Gates; Hafnium oxide; Leakage current; metal gate; MOS devices; MOSFETs; Reduction; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon; Stacks; tantalum nitride (TaN); terraced oxide; Thermal conductivity; Transconductance; Transistors; work function; Work functions
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2006.882521

Reduction in effective work function (EWF) of midgap-tantalum nitride (TaN) metal gate with gadolinium-oxide buffer layer on Hafnium-based high-kappa gate stack has been demonstrated. EWF of 4.2 eV is achieved for TaN with a bilayer arrangement of Gd 2 O 3 /HfSiO x dielectric. By using Gd-Si cosputtered layer on HfO 2 , a reduction in EWF to nMOS compatible value of 4.05 eV is obtained. Electrical and material characterization indicate that the conversion of gadolinium to gadolinium oxide and presence of silicon in the high-kappa layer are responsible for the EWF shift. nMOSFETs with improved output current, transconductance, and channel electron mobility highlight the approach of using gadolinium in the gate stack