Title :
NMOS Compatible Work Function of TaN Metal Gate With Gadolinium Oxide Buffer Layer on Hf-Based Dielectrics
Author :
Thareja, Gaurav ; Wen, Huang Chun ; Harris, Rusty ; Majhi, Prashant ; Lee, Byung Hun ; Lee, Jack C.
Author_Institution :
Dept. of Electr. & Comput. Eng., Texas Univ., Austin, TX
Abstract :
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 Gd2O3/HfSiOx dielectric. By using Gd-Si cosputtered layer on HfO2, 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
Keywords :
MOSFET; dielectric materials; electron mobility; gadolinium compounds; hafnium compounds; semiconductor device testing; tantalum compounds; work function; Gd2O3; HfO2; NMOSFET; TaN; channel electron mobility; effective work function; high-K gate stack; metal gates; Buffer layers; Dielectrics; Fabrication; Hafnium oxide; Leakage current; MOS devices; MOSFETs; Silicon; Thermal conductivity; Transconductance; Dipole theory; metal gate; tantalum nitride (TaN); terraced oxide; work function;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2006.882521
