Band alignment at metal-gate/high-k/semiconductor interfaces
|S. J. Wang 1, Y. F. Dong 2, Q. Li 2, Y. P. Feng 2, A. C. H. Huan 1|
1. Institute of Materials Research and Engineering, Singapore, Singapore
The interfaces between metal, oxide and semiconductor are very critical for the application of metal/oxide thin films, including gate dielectrics and ferroelectric transistors. Much research has focused on understanding and exploiting the properties of novel metal/oxide/semiconductor interfaces to fulfill the stringent requirements for these and other applications. With the alternative high-k gate dielectrics are expected to replace current SiO2 gate oxide for the continued scaling of metal-oxide-semiconductor field-effect transistors (MOSFET), there is an immense interest in replacing conventional poly-Si gate with metal gates because of the serious problems related to poly-Si gate depletion and high gate resistance. However, the possible atomic bonds of metal-metal or metal-oxygen at metal gate/oxide gate dielectric interface are quit different from conventional silicon-oxygen bond at poly-Si-SiO2 interface. How these bonds affect the band alignment at the metal/high-k oxide interface is important issue for the implementation of this gate stack. In this presentation, we present the band alignment studies for Ni/ZrO2(HfO2)/Semiconductor interfaces by photoemission study and first-principle calculation. The Schottky-barrier heights for the Ni and ZrO2 (HfO2) interfaces have been determined by means of x-ray photoemission spectroscopy (XPS). Depending on the interface treatment, the band alignment could be tuned. First-principles calculations for model interfaces provide a microscopic explanation of such variation. The results show that the band alignment at metal/high-k/semiconductor could be engineered through the interface structure-control.
Presentation: oral at E-MRS Fall Meeting 2005, Symposium F, by S. J. Wang
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-19 05:04 Revised: 2009-06-07 00:44