Near field acoustic ultrasonic microscope system and method

Abstract

An acoustic microscope assembly for atomic level inspection of a target object includes a cantilever arm with a sharp tip on its lower surface and a zinc oxide piezoelectric thin film on its upper surface. High frequency excitation signals, having a frequency of at least 50 Megahertz, are applied to the piezoelectric thin film so as to generate high frequency acoustic signals that are transmitted through the sharp tip so as to impact on a target object. The assembly can either receive acoustic signals reflected by the target object, or it can receive acoustic signals that have propagated through the target object. One method of using this assembly is to apply a continuous wave signal to the piezoelectric thin film while scanning the target object, and measuring characteristics of the target object at various positions thereof by measuring the resonant frequency of the transmitted high frequency acoustic signals. Other methods include pulsed operation, and combining acoustic measurements with atomic force measurements and/or tunneling current measurements to characterize a target object. The acoustic microscope assembly can also be used for storing information on a substrate, by deforming the substrate at selected positions, and for reading such stored information by determining which positions on a substrate have been deformed.