AVS 50th International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeM

Paper AS-WeM6
Synchrotron UPS and EXAFS Analysis of High-k and Si Interfaces

Wednesday, November 5, 2003, 10:00 am, Room 324/325

Session: High-K Materials Interface Analysis
Presenter: Y.-S. Lin, University of California, Los Angeles
Authors: Y.-S. Lin, University of California, Los Angeles
R. Puthenkovilakam, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
Ultra-thin dielectric films with high permittivity such as ZrO@sub 2@, HfO@sub 2@, and HfO@sub x@N@sub y@ have numerous applications in advanced microelectronics, especially on silicon substrates for gate dielectric application in metal-oxide-semiconductor (MOS) devices. In this work, we combine synchrotron based ultra-violet electron spectroscopy (UPS) and extended x-ray absorption fine structures (EXAFS) analysis to characterize the interface of ZrO@sub 2@, HfO@sub 2@, and HfO@sub x@N@sub y@ on silicon. Specifically, the interfacial composition and chemical coordination of the deposited metal oxides and oxynitrides films on silicon are determined. By tuning the photon energy in UPS analysis, we determined the composition of the interfaces between high-k dielectrics and silicon and their corresponding valence band structures. The experimental results were compared to first principle calculations using density functional theory to validate the measurements and elucidate the effect of chemical coordination at the interface on the electronic structure, band gap, and band offsets. The energy shifts measured in oxygen s and p states compared favorably with first principle calculations and closely related to the bonding to metal atoms. The Fourier transformed EXAFS spectra also agreed very well with the first principle prediction and allowed the determination of interatomic spacings and the chemical nature of the nearest and second-nearest neighboring atoms. Based on the experimental validation, we used density functional theory to calculate the electronic band gaps, conduction and valence band offsets, and interface states for dielectric/Si interfaces, and found that these properties are greatly affected by the metal, oxygen, and nitrogen coordinations.