We have performed photoemission spectroscopy of high-k gate insulators HfO2/HfSiON/Si to investigate the interlayer formation by Hf metal predeposition and the annealing effect systematically. Comparing the line shapes of core-level photoemission spectra for two systems with and without Hf-metal predeposition, we found that Hf-metal predeposition effectively reduces the growth of interface layer. Hf 4f core-level spectra revealed that the annealing at 1000 °C for both samples causes the formation of the metallic Hf and Hf-silicide clusters. Surface morphology was also observed by atomic force microscopy. © 2004 American Institute of Physics.