Surface Modification of MEMS Chips for Increased Thermal and Chemical Stability

Sammanfattning

The introduction of the Environmental Transmission Electron Microscope (ETEM) has revolutionized scientific studies by allowing in-situ studies of nano and angstrom scale samples in varying environments. In combination with the introduction of the Microelectromechanical Systems (MEMS) chip the ETEM has become a powerful tool for high resolution imaging of material interaction. However, the MEMS chips use a thin silicon nitride film which reacts with certain metals to form silicides. The unwanted reaction results in a limitation when observing metal reactions in the ETEM. In this report, a thin film will be applied to the MEMS chip by using Atomic Layer Deposition (ALD) in order to prevent the formation of silicides by creating a barrier between the metal particles and silicon nitride film. For this purpose SiO2, Al2O3 and ZrO2 go through thorough testing inside the ETEM evaluating reactivity, structural integrity and effect on temperature output of the MEMS chip. The results point to a possible solution where Al2O3 showed the most promising results. In comparison, ZrO2 lacked structural uniformity and SiO2 was heavily damaged by the electron beam. Additionally, no major difference on MEMS chip operation temperature was found.