Interfacial strain-induced self-organization in semiconductor dielectric gate stacks. II. Strain-relief at internal dielectric interfaces between SiO2 and alternative gate dielectrics

摘要

This article applies bond constraint theory to develop a scaling relationship for the density of bond-strain induced defects such as fixed charge localized at internal dielectric interfaces. The magnitude of this charge scales with the square of the difference between the average number of bonds/atom of the interface constituents such as SiO2 and Si3N4, or ZrO2 or HfO2. Consistent with equilibrium phase diagrams of the SiO2-Zr(Hf)O-2 binary alloy systems, interfaces between: (i) SiO2 and (ii) ZrO2, HfO2, and Zr and Hf silicate alloys exhibit a strain-induced self-organization after annealing to temperatures of similar to600-800 degreesC producing a diphasic interfacial transition region comprised of ZrO2 encapsulated by SiO2. This reduces fixed charge by more than I order of magnitude. In marked contrast, and also consistent with differences in their equilibrium phase diagrams, strain-induced self-organization does not occur for temperatures up to at least 1000 degreesC at interfaces between: (i) SiO2 and Al2O3 and (ii) SiO2 and Si oxynitride alloys due to binary alloy compound phases with congruent melting points that prevent formation of the diphasic interfacial transition region comprised of the end member oxide dielectrics. (C) 2004 American Vacuum Society.