As a first step in the identification of suitable alternative gate dielectrics for metal oxide semiconductor field-effect transistors (MOSFETs), we have used tabulated thermodynamic data to comprehensively assess the thermodynamic stability of binary oxides and nitrides in contact with silicon at temperatures from 300 K to 1600 K. Sufficient data exist to conclude that the vast majority of binary oxides and nitrides are thermodynamically unstable in contact with silicon. The dielectrics that remain are candidate materials for alternative gate dielectrics. Of these remaining candidates, the oxides have a significantly higher dielectric constant (ĸ) than the nitrides. We then extend this thermodynamic approach to multicomponent oxides comprising the candidate binary oxides. The result is a relatively small number of silicon-compatible gate dielectric materials with ĸ values substantially greater than that of SiO2 and optical bandgaps ≥ eV.

This brief article sets the context for the March 2002 issue of MRS Bulletin focusing on Alternative Gate Dielectrics for Microelectronics. Contributors are several experts from industry and academia engaged in the search for manufacturable solutions for a suitable alternative gate dielectric to SiO2 using high-dielectric-constant (high-ĸ) materials. Issues discussed in the articles include thermodynamics criteria for materials selection, materials interactions in the construction of the transistor gate stack, characterization of alternative materials, determination of suitable band offsets for candidate dielectrics, and integration of these alternative gate dielectrics in a manufacturable environment.