Title :
Work-Function Tuning of TaN by High-Temperature Metal Intermixing Technique for Gate-First CMOS Process
Author :
Ren, C. ; Chan, D.S.H. ; Loh, W.-Y. ; Balakumar, S. ; Du, A.Y. ; Tung, C.H. ; Lo, G.Q. ; Kumar, R. ; Balasubramanian, N. ; Kwong, D.L.
Author_Institution :
Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore
Abstract :
This letter investigates the feasibility of adjusting the work function (WF) of TaN metal gate by intermixing (InM) of ultra-thin TaN/Metal stacks at high temperature. This could be useful for the integration of dual-WF metal gates in a gate-first CMOS process without exposing gate dielectric during metal-etching process. TaN/Tb and TaN/Ir stacks were studied, and it is found that the WF of TaN can be readily modulated through metal InM in TaN/Tb stack after high-temperature treatment (~1000 degC), which simulates the source/drain dopant activation process in a gate-first CMOS process. Factors affecting the InM process will be discussed. Successful transistor threshold voltage adjustment by ~300 mV on high-kappa HfTaON/HfO2 dielectrics has also been demonstrated in TaN/Tb stack using this technique
Keywords :
CMOS integrated circuits; dielectric materials; hafnium compounds; heat treatment; tantalum compounds; work function; HfTaON-HfO2; dual work function; gate dielectric; gate-first CMOS process; high-K dielectrics; high-temperature treatment; metal gates; metal-etching; source-drain dopant activation; Alloying; Buffer layers; CMOS process; Dielectrics; Laboratories; MOS devices; Microelectronics; Silicon; Temperature; Threshold voltage; CMOS; dual work function (WF); gate first; intermixing (InM); metal gate;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2006.882569
