Title :
Systematical investigation and physical mechanism of HfO2 gate stacks band alignment, VFB shift and Fermi level pinning
Author :
Wang, Xia L. ; Wang, W.W. ; Han, Kwangseok ; Zhang, Juyong ; Xiang, J.J. ; Ma, X.L. ; Yang, Hongming ; Chen, D.P. ; Ye, T.C.
Author_Institution :
Key Lab. of Microelectron. Devices & Integrated Technol., Inst. of Microelectron., Beijing, China
Abstract :
Band alignment of TiN/HfO2/SiO2/Si stack is systematically investigated by X-ray photoelectron spectroscopy. The differences of Si 2p binding energies between SiO2 and Si substrate are experimentally found to decrease with the sequence of SiO2/Si, 4 nm HfO2/SiO2/Si and 2 nm HfO2/SiO2/Si stacks. The p-type Schottky barrier heights at TiN/HfO2 interface of TiN/HfO2/SiO2/Si stack are experimentally estimated to increase with thicker HfO2 thickness. A physical model based on band alignment of TiN/HfO2/SiO2/Si stack is employed to successfully explain these experimental results. The positive VFB shift of TiN/HfO2/SiO2/Si stack and Fermi level pinning are also physically demonstrated by this model and attributed to interface induced gap states at TiN/HfO2 and HfO2/SiO2 interfaces.
Keywords :
Fermi level; Schottky barriers; binding energy; hafnium compounds; silicon compounds; titanium compounds; Fermi level pinning; HfO2 gate stacks band alignment; HfO2-SiO2-Si; Si 2p binding energy; TiN-HfO2; TiN-HfO2-SiO2-Si; VFB shift; X-ray photoelectron spectroscopy; interface induced gap state; p-type Schottky barrier height; Hafnium oxide; Logic gates; Silicon; Tin;
Conference_Titel :
VLSI Technology, Systems, and Applications (VLSI-TSA), 2012 International Symposium on
Conference_Location :
Hsinchu
Print_ISBN :
978-1-4577-2083-3
DOI :
10.1109/VLSI-TSA.2012.6210159
