Title :
High performance tantalum carbide metal gate stacks for nMOSFET application
Author :
Hou, Y.T. ; Yen, F.Y. ; Hsu, P.F. ; Chang, V.S. ; Lim, P.S. ; Hung, C.L. ; Yao, L.G. ; Jiang, J.C. ; Lin, H.J. ; Jin, Y. ; Jang, S.M. ; Tao, H.J. ; Chen, S.C. ; Liang, M.S.
Author_Institution :
Taiwan Semicond. Manuf. Co., Hsinchu
Abstract :
A systematic study is performed on tantalum carbide (TaC) metal electrode on HfO2 and HfSiON dielectrics using conventional CMOS process. TaC´s effective work function (EWF) is estimated to be 4.28 eV on HfO2 using Vfb~EOT methodology, where both interfacial oxide and high-K film thickness are varied and thus charge effect is corrected successfully. Investigation of the EWF dependence on underlying dielectrics reveals that TaC EWF on HfSiON is about 0.17eV higher than that on HfO2. This phenomenon cannot be explained by the usual metal induced gap states (MIGS) theory. In addition, mobility higher than 90% of poly/SiO2 reference and EOT scaling down to 12.5A has been achieved. Reduction of HfO2 thickness is identified as an effective approach to suppress charge trapping in the gate stack. With reduced thickness, threshold voltage stability and electron mobility are significantly improved. All these results prove that TaC/high-K stack is a promising candidate in nMOSFET application
Keywords :
MOSFET; high-k dielectric thin films; interface states; tantalum compounds; CMOS process; EOT methodology; EOT scaling; HfO2; HfSiON; TaC; high-K film thickness; interfacial oxide; metal electrode; nMOSFET application; tantalum carbide metal gate stack; CMOS process; Electrodes; Electron mobility; Electron traps; Hafnium oxide; High K dielectric materials; High-K gate dielectrics; MOSFET circuits; Stability; Threshold voltage;
Conference_Titel :
Electron Devices Meeting, 2005. IEDM Technical Digest. IEEE International
Conference_Location :
Washington, DC
Print_ISBN :
0-7803-9268-X
DOI :
10.1109/IEDM.2005.1609258
