Quartz-crystal scanning probe microcantilevers with a silicon tip based on direct bonding of silicon and quartz

This paper reports on the design, fabrication and characterization of cantilever-shaped quartz-crystal resonators for scanning probe microscopy (SPM) in order to operate under various environments, especially in liquids for biological applications. The cantilevers have functions of self-sensing and self-actuation using piezoelectric effects, and these properties are demonstrated experimentally. Compared to conventional SPM cantilevers, this quartz cantilever is easy to utilize as a SPM based force sensor in liquids because the self-actuating properties can lead to no spurious resonant peaks. In addition, the self-sensing properties will enable its use even in an opaque liquid and can simplify the SPM system. In this research, quartz cantilevers are fabricated on silicon using a silicon-quartz direct bonding technique, and the sharp silicon tip is integrated at the end of the cantilever as well. Additionally, the electrical Q-enhancement (active Q-control) was tested.