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 2O 3 and Ta 2O 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.