G. B. Rayner

Microscopic model for enhanced dielectric constants in low concentration SiO2-rich noncrystalline Zr and Hf silicate alloys

Dielectric constants, k, of Zr(Hf) silicate alloy gate dielectrics obtained from analysis of capacitance–voltage curves of metal–oxide–semiconductor capacitors with 3–6 at. % Zr(Hf) are significantly larger than estimates of k based on linear extrapolations between SiO2 and compound silicates, Zr(Hf)SiO4. Analysis of infrared spectra of Zr silicate alloys with 3–16 at. % Zr indicates increases in the coordination of Zr to O atoms from 4 to approximately 8 with increasing Zr content. The major contributions to enhancements in k in these low Zr(Hf) content alloys are explained by a transverse infrared effective charge that scales inversely with increasing Zr–O bond coordination.

Nonlinear composition dependence of x-ray photoelectron spectroscopy and Auger electron spectroscopy features in plasma-deposited zirconium silicate alloy thin films

The local bonding of Zr, Si, and O atoms in plasma-deposited, and post-deposition annealed Zr silicate pseudobinary alloys [(ZrO2)x(SiO2)1−x] was studied by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Systematic decreases in XPS binding energies, and increases in AES kinetic energies with alloy composition x are consistent with an empirical chemical bonding model based on electronegativity equalization; however, there are significant departures from the predicted linear composition dependencies of that model. Deviations from linearity in the XPS compositional dependencies are correlated with dipolar network atom fields as determined from ab initio calculations. The nonlinearities in the x dependence of ZrMVV and OKVV AES spectral features are determined primarily by oxygen–atom coordination dependent shifts in valence band offset energies. The energy spread in the compositional dependence of binding energies (∼1.85 eV) for the XPS Zr 3d5/2 and Si 2p features combined with...

Electronic structure of noncrystalline transition metal silicate and aluminate alloys

A localized molecular orbital description ~LMO! for the electronic states of transition metal ~TM! noncrystalline silicate and aluminate alloys establishes that the lowest conduction band states are derived from d states of TM atoms. The relative energies of these states are in agreement with the LMO approach, and have been measured by x-ray absorption spectroscopy for ZrO2 ‐ SiO2 alloys, and deduced from an interpretation of capacitance‐voltage and current‐voltage data for capacitors with Al2O3 ‐T a 2O5 alloy dielectrics. The LMO model yields a scaling relationship for band offset energies providing a guideline for selection of gate dielectrics for advanced Si devices.

Spectroscopic study of chemical phase separation in zirconium silicate alloys

This article presents a comprehensive spectroscopic study of chemical phase separation in zirconium silicate alloys, (ZrO2)x(SiO2)1−x, using Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, extended x-ray absorption fine structure spectroscopy, and near edge x-ray absorption spectroscopy. These measurements are complemented by measurements of x-ray diffraction and high resolution transmission electronic microscopy imaging. This combination has been applied to Zr silicate alloys, providing the first comprehensive comparisons of the relative sensitivities of these spectroscopic techniques applied to micro- and nanoscale chemical phase separation of high-k dielectric alloys.

Electronic structure of high-k transition metal oxides and their silicate and aluminate alloys

This article addresses differences between the electronic structure of: (i) alternative high-k transition metal (TM) rare earth dielectrics and (ii) SiO2 and Si oxynitride alloys by presenting a systematic x-ray absorption spectroscopy study of transitions between TM n p-core states and TM metal n+1−d⋆ and n+2 s⋆ antibonding/conduction band states (n=2, 3, and 4) that is complemented by studies of O atom K1 edge absorption spectra. Ab initio calculations based on small clusters establish the localization of the n+1 d⋆ states on the TM metals. Ab initio electronic structure calculations are also used to interpret other aspects of the optical, ultraviolet, x-ray, and electron spectroscopies, and also provide a basis for interpretation of electrical results, thereby narrowing the field of possible replacement dielectrics for advanced semiconductor devices.

Electronic structure of transition metal high-k dielectrics: interfacial band offset energies for microelectronic devices

Transition metal silicates, (ZrO2)x(SiO2)1� x, have dielectric constants k > 10 that make them attractive for advanced Si devices. Band offset energies relative to Si are an important factor in determining tunneling leakage current, and internal photoemission. Studies by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and X-ray absorption spectroscopy (XAS) are combined with ab initio calculations to identify the compositional variation of the band-gap, and valence and conduction band offset energies of Zr silicate alloys with respect to Si. The minimum conduction band offset, due to

Chemical and physical limits on the performance of metal silicate high-k gate dielectrics

Abstract This research identifies four significant limitations on the performance of high- k alternative gate dielectrics that derive from inherent relationships between (i) chemical bonding and physical properties, and (ii) device operation. These include interfacial band offset energies, thermal stability against chemical phase separation, coordination dependent dielectric constants, and interfacial fixed charge. Then these are applied to transition metal silicate alloys, e.g., (ZrO 2 ) x (SiO 2 ) 1− x . The paper also includes results for other high- k oxides, Al 2 O 3 and Ta 2 O 5 , and their alloys that relate to the issues addressed in this paper, and in particular help to put the results on the silicate alloys into a better perspective. This portion of the paper provides additional perspective with regard to the differences in the chemical and physical limitations of elemental oxides and binary oxide alloys.