Band alignment at metal-gate/high-k/semiconductor interfaces

S. J. Wang 1Y. F. Dong 2Q. Li 2Y. P. Feng 2A. C. H. Huan 1

1. Institute of Materials Research and Engineering, Singapore, Singapore
2. Department of Physics, National University of Singapore, Singapore, Singapore

Abstract

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