Quantifying the Work of Adhesion Between an AFM Cantilever Tip and MEMS Test Structures After Packaging

Abstract

Abstract Adhesion is important to the yield and performance of MEMS (Micro-Electro-Mechanical Systems) and NEMS (Nano- Electro-Mechanical Systems). Measuring the work of adhesion, with an AFM (Atomic-Force Microscope), allows one to study surface interactions from an energy perspective as opposed to an adhesion (force) perspective. The works of adhesion were measured with different AFM tip radii on multiple types of samples. Two sample variables were examined: four die attach conditions (no attachment, silicone, polyimide silicone, and silver glass), and two surface conditions (native oxide with and without a few angstroms of vapor-deposited diphenyl siloxane). For a normal silicon cantilever, the work of adhesion seems to be slightly less for the treated surfaces than the untreated, except for the silverglass die attach material. There were at least three orders of magnitude difference in the works of adhesion for the different AFM tip radii. Presumably, the trend is due to some combination of material properties, interfacial roughness, and torque on the AFM cantilever.