Chemical phase separation at device processing temperatures is an important issue for integration of Zr and Hf silicates alloys into advanced complementary metal oxide semiconductor (CMOS) devices. Chemical phase separation into ZrO2 and SiO2 has been detected by different spectroscopic techniques, including Fourier transform infrared, X-ray photoelectron, and X-ray absorption spectroscopy, as well as X-ray diffraction and high resolution transmission electron microscopy imaging as well. Comparisons between these techniques for Zr silicates identify an unambiguous approach to distinguishing between chemical phase separation with different degrees of micro- and nano-crystallinity. (C) 2004 Elsevier B.V. All rights reserved.