Developing analytical techniques using x-ray reflectivity and diffraction to study thin film systems.

摘要

The rapid expansion of thin films has driven the need for experimental techniques capable of measuring their unique properties. A method is developed using x-ray reflectivity (XRR) to measure the thermal expansion coefficient (TEC) for sub-micron thin films. The thin film mechanics required to extract the thermal expansion parameter for a free-standing film as opposed to a supported film are discussed. The technique is capable of differentiating the physical properties of many classes of low-k dielectric materials. Results of measurements for a series of plasma-enhanced chemical vapor deposited and spin-on low-k dielectric thin films are provided and compared. The measured values show that low-k materials can have very large TEC which underlines the importance for continued study of this property in new materials. Complications with polymer thin films around the glass transition using this technique are discussed.;X-ray analysis has long been considered a bulk characterization technique, however XRR and grazing incidence x-ray diffraction (GIXRD) have emerged as tools for non-destructive thin film characterization. The application of x-ray analysis to the understanding of novel nanolaminate thin film systems is discussed.;New thin-film dielectrics and nanolaminates have been developed on the basis of aqueous solution deposition of Hf and Zr sulfates. The functionality and quality of the films have been assessed by performance in electrical devices and x-ray reflectivity.;W/Al2O3 nanolaminates were fabricated using atomic layer deposition (ALD) techniques. X-ray reflectivity (XRR) investigations indicated that the W/Al2O3 nanolaminates were off from target thickness due to a lower than expected ALD film density for thin Al 2O3 ALD nanolayers. The films were found to be thermally stable up to 500°C, placing a limit on the application of W/Al2O 3 nanolaminates as thermal barrier coatings and x-ray mirrors.;This work highlights the importance for continued study and development of x-ray metrology for measuring the properties of new thin film material systems.;This work consists, in part, of previously published and co-authored material.