The interphase between polymer and metal was investigated for further understanding of the mechanical properties. In particular, an analysis of the stiffness can provide significant information to determine the stress distribution in the interphase. The polymer-metal interphase was prepared by applying epoxy on micrometer-scale copper structures, which were created by electron beam lithography (EBL). The stiffness was characterized by force modulation microscopy (FMM), which is a scanning force microscopy (SFM)-based technique. According to the analysis, a stiffness variation was observed in the interphase. It showed a lower stiffness in the interphase than in the bulk epoxy, which is far from the copper structures. In addition, the morphology of epoxy surface was studied. The nodules on the epoxy surface were characterized and the average length was found to be approx. 76 nm. FMM showed adequate sensitivity to visualize the nodules on the epoxy. Therefore, FMM can also be a very effective method to analyze epoxy morphology and the stiffness in the interphase along with the topography images.