SCANNING FORCE MICROSCOPY IN THE DYNAMIC-MODE USING MICROFABRICATED CAPACITIVE SENSORS

We report on the first successful operation of a scanning force micros cope using microfabricated capacitive force sensors. The sensors, whic h are made from single crystal silicon on insulator wafers, consist of a cantilever spring with integrated tip at the free end and an electr ically insulated counter electrode. Dynamic force gradient sensing is the preferred operating mode. Here, tip-sample interactions are detect ed by letting the sensor act as a resonator in a phase controlled osci llator setup and measuring corresponding shifts of the oscillation fre quency. Experiments were performed in vacuum using a standard tunnelin g microscope. A Cr grating on a quartz substrate served as the test sa mple. Topographic images showing details on a 10 nm scale were obtaine d operating at a constant force gradient of the order of 0.01 N/m. In addition, critical design parameters are discussed based on an analysi s of the electromechanical properties of the sensors. (C) 1996 America n Vacuum Society.