Suppression of chemical phase separation in high-k zirconium an hafnium nitro-silicate and alumino-silicate alloys for CMOS applications

Thin film pseudo-binary Zr and Hf silicate alloys are non-crystalline as-deposited, but display chemical phase separation (CPS) into ZrO/sub 2//HfO/sub 2/ and SiO/sub 2/ on annealing to temperatures greater than 900/spl deg/C. In addition, and depending on the ZrO/sub 2//HfO/sub 2/ concentrations, the ZrO/sub 2//HfO/sub 2/ phases may crystallize as well. Application of bond-constraint theory (BCT) indicates that these alloys are over-constrained, or stress-rigid, so that CPS is anticipated. If concentrations are controlled within narrow limits in pseudo-ternary Zr(Hf) nitro-silicate and alumino-silicate alloys, CPS is completely suppressed by self-organizations which relieve local bond-strain.