Structure analysis of the system hafnium/silicon(100) by means of X-ray photoelectron spectroscopy and X-ray photoelectron diffraction (XPD)

Due to the ongoing miniaturization of semiconductor devices new gate dielectrics are required for future applications. In this work we investigated hafnium silicide as a pre-system for hafnium oxide, one of the most promising candidates. One of the major problems of HfO2-films on silicon is the formation of hafnium silicide at the HfO2/Si interface. Therefore, ultrathin films of the system HfSi on Si(100) with a systematic varied thickness from 3 to 30 angstrom were prepared. Measurements were conducted by means of X-ray photoelectron spectroscopy and low energy electron diffraction (LEED). Also full 2 pi X-ray photoelectron diffraction (XPD) patterns with high spectral resolution were recorded. Against other reports related to thicker films, several heating cycles showed no phase transitions of the ultrathin films. However, above temperatures of 630 degrees C an island formation is strongly indicated. The experimental XPD patterns are compared to simulated patterns of model structures. For the first time we present a modification of the C49 structure a possible structure for ultrathin HfSi2-films on bulk Si. As an outlook possibilities for preparing the system HfO2/Si(100) are introduced. (c) 2006 Elsevier Ltd. All rights reserved.