In-depth Profile Analysis in Metal/high-k Gate Stack Structures Studied by Synchrotron-radiation Photoelectron Spectroscopy

Abstract

We have investigated the thermal stability of TiN/HfSiON gate stack structures using synchrotron-radiation photoemission spectroscopy. Spectral intensities of the Si-oxide components in Si 2p core-level spectra systematically increase with annealing temperature, which strongly depends on thickness of the TiN metal gate layer. Changes brought by annealing procedures in in-depth profiles indicate segregation of Si atoms at the TiN surface. Furthermore, chemical-states-resolved in-depth analyses by angle-resolved photoemission spectroscopy suggest formation of TiSi_x and HfN_y components, due to chemical bond breaking in the HfSiON layer during TiN film growth. This can be related to the degradation of thermal stability.