The fundamental studies on interface and interphase of advanced thin film materials have attracted significant attention in recent years. As the starting point of many experimental projects, characterisation of thin films with one or more advanced analytical techniques, such as electron microscopes and X-ray diffractometers etc., is essential. It is our ultimate goal to conduct the unambitious measurements across various advanced analytical platforms, and enable reliable cross references for the same research project, as well as comprehension studies on the similar projects between different research groups.
In this case study, a Pt-Cr multilayer ultrathin film (30 nm x 6 layers) sample was fabricated with a twin-target sputter coater in the lab. We defined the nominated thickness of multilayer films by inputting a serious of operating parameters, including working distance and sputtering current etc. The deposition process was monitored with an in-situ quartz sensor, which measured the dynamic sputter rate. The fluctuation of the rate was less than 5%. The calibration of the thickness monitor was done by the manufacturer. The post-deposition measurement of the sample was carried out with the TEM analysis. Focused ion beam was used to prepare an electron transparent thin cross section slice, which was cut perpendicular to the sample surface. This enables the thickness of the multilayer film to be directly measured on the electron micrograph. The difference between the nominated thickness and the thickness measured with TEM was further validated with the depth profiles of the same sample generated with other advanced analytical platforms, including XPS, TOF-SIMS, and glazing-angle X-ray reflectivity measurement techniques. It is our attempt to explore pros and cons of these advanced analytical techniques, and in turn to provide a roadmap for further applications.