Title :
Wide Controllability of Flatband Voltage by Tuning Crystalline Microstructures in Metal Gate Electrodes
Author :
Ohmori, K. ; Chikyow, T. ; Hosoi, T. ; Watanabe, H. ; Nakajima, K. ; Adachi, T. ; Ishikawa, A. ; Sugita, Y. ; Nara, Y. ; Ohji, Y. ; Shiraishi, K. ; Yamabe, K. ; Yamada, K.
Author_Institution :
Waseda Univ., Tokyo
Abstract :
We propose a novel approach to control the effective workfunction (WF) by taking advantage of crystal structures in metal gate electrodes. The crystal structures determine the predominant material elements at the metal/high-k interface. We have found that, in a Ru-Mo alloy system, a randomly-oriented Ru (fcc) structure promotes the segregation of Mo at the interface, enabling us to achieve a wide controllability of flatband voltage (Vfb) from 0.6-0.8 eV In addition, the segregation of Mo within a Ru-rich electrode is a key to reducing Fermi level pinning at metal/HfSiON interfaces. Further tunability in Vfb has been examined by employing C-incorporation in the RuMo alloy, thus reducing the crystal grain size and facilitating the control of Vfb for a HfSiON (2 nm)/SiO2(0.7 nm)/Si capacitor. These results demonstrate that the crystal structure control in metal gates is essential for realizing the MIS-FET devices with a short gate length in the 32-22 nm node and beyond.
Keywords :
Fermi level; MISFET; carbon; dielectric materials; doping; electrodes; grain size; hafnium compounds; high-k dielectric thin films; molybdenum alloys; ruthenium alloys; segregation; silicon compounds; voltage control; work function; Fermi level pinning reduction; HfSiON-SiO2-Si; MIS-FET devices; RuMo:C; capacitor; carbon-incorporation; crystal grain size reduction; crystal structures; crystalline microstructures; effective workfunction; electron volt energy 0.6 eV to 0.8 eV; flatband voltage control; metal gate electrodes; metal-high-k interface; segregation process; voltage tunability; Controllability; Crystal microstructure; Crystalline materials; Crystallization; Electrodes; Grain size; High K dielectric materials; High-K gate dielectrics; Inorganic materials; Tuning;
Conference_Titel :
Electron Devices Meeting, 2007. IEDM 2007. IEEE International
Conference_Location :
Washington, DC
Print_ISBN :
978-1-4244-1507-6
Electronic_ISBN :
978-1-4244-1508-3
DOI :
10.1109/IEDM.2007.4418942
