Six-fold improvement in nanotopography sensing via temperature control of a heated atomic force microscope cantilever

Heated atomic force microscope (AFM) cantilevers can be used to thermally sense the nanotopography of a surface. Previous reports show that cantilever nanotopography sensitivity can be increased by either modifying the cantilever design or by increasing the operating temperature of the cantilever. This article describes six-fold improvement to cantilever sensitivity by using control mechanisms to maintain either constant cantilever electrical resistance, cantilever dissipated power, or the voltage across the circuit. Topographical imaging was performed on a 20 nm tall silicon calibration grating under each of these control schemes. The topographies obtained by the laser-deflection and the thermal signal corresponding to each control mechanism were compared. The thermal nanotopography sensitivity is improved by as much as 570% by controlling cantilever resistance and 345% by controlling power supply to the cantilever. Overall, the topography sensitivity using heated cantilevers is 500 times greater than that using similarly sized piezoresistive cantilevers.