In-situ compensation of the parasitic capacitance for nanoscale hysteresis measurements

Ferroelectric capacitors of submicron sizes for nonvolatile memory applications are entering the structure size of nanotechnology. Therefore the signal level for hysteresis measurements is getting much smaller than the influence of the parasitic capacitance of the measurement setup, which is caused by the cantilever of a scanning force microscope (SFM) used for contacting. Our novel compensation method significantly increases the signal to noise ratio by active cancellation of the parasitic capacitance of the setup during the measurement. From measurements and simulations the parasitic capacitance of an SFM has been determined to be 170 fF. This is about two orders of magnitude higher than the capacitance of a ferroelectric capacitor of submicron size. The new compensation method will be demonstrated on single ferroelectric PbZrxTi1−xO3 (PZT) submicron capacitors.