In Situ Nanoindentation Research Of Film By SEM/SPM Hybrid System

With the application and development of the nano-science, the microelectromechanical systems (MEMS) has already become the important point in the research of high technology field. MEMS strong vitality lies in high-volume, small size, low cost and high reliability, the scope of application of its technology is quite extensive, involving almost all areas of the natural sciences and engineering, which makes MEMS has broad application prospects. For MEMS chip, the material used mostly are the single crystal silicon and thin-film deposited on it; in the design and application of MEMS, we need to focus on understanding its mechanical properties; Therefore, understanding these micro-nano film mechanical properties has become a hot topic of current research. Nanoindentation technique, as the most ideal mechanical property test method to study the structure of thin film material, has experienced years of development. But with the decreasing size of the film reaching micro-nano level, the traditional test equipment in the load and displacement measurement accuracy will not meet the requirements. focusing on the problem in the research of mechanical property of the thin film in nano size, this study achieves the in situ quantitative measurement by using the SEM/SPM system developed by our group. The Ag thin films with thickness of1um and100nm are deposited on the Si wafer by using the direct current magnetron sputtering technology. The analysis of XRD indicated that the preferred orientation of Ag film is along [111] direction and the film possesses high degree of purity. Moreover, the scanning electronic microscope (SEM) and the SEM/SPM reflects that the grain are equiaxed with uneven distribution of size. by applying indentation experiment on the1um Ag film with Nanoindenter G200and SEM/SPM, we can clearly see the pile-ups at the edge of indentation area. The piled-up will be more clear with deeper indentation.SEM/SPM system enables the indentation experiment using the AFM cantilever with Cube corner diamond indenter, to acquire the voltage signal curve, transforming into the curve of load versus displacement and then calculating the hardness. The result of this study is10.04GPa by choosing fused silicon as the sample to be indented, with only0.6%differences comparing the10.1GPa resulted from Nanoindenter G200, which demonstrate the reliability of the system.For self-designed SEM/SPM system, we developed two methods to test the mechanical properties of the film, one is in-situ testing based on the capabilities SEM/SPM system that can record the morphology after indentation by SEM, the development of research methods for the mechanical properties of plastic films. this method develop the study focusing on the plastic mechanical property of thin film. Another is a method based on the high resolution of SEM/SPM system, which is capable of obtaining load-displacement curve with small depth of indentation, developing method to test mechanical property of ultra-thin film(≤100nm). The results of two methods have made a comparsion with those from Nanoindenter G200.