A noncontact scanning electrostatic force microscope for surface profile measurement

A scanning electrostatic force microscope is presented for noncontact surface profile measurement. A charged conducting probe tip is oscillated by a tuning fork quartz crystal resonator. The probe tip is scanned over the sample surface by using an XY scanner in such a way that the frequency shift of the tuning fork oscillation, which corresponds to the electrostatic force gradient, is kept constant by controlling the probe Z position with a Z scanner. A dual height method is proposed to accurately obtain the tip to sample distances through removing the influence of the electric field distribution on the sample surface.