EVIDENCE FOR ACOUSTIC-WAVES INDUCED BY FOCUSED ION-BEAMS

Acoustic waves induced by an intensity modulated focused ion beam have been measured. The experiments were performed with Ga+ ions of 35 keV at a current of 3 nA and variable chopping frequency up to 10 MHz in a common focused ion beam system, The acoustic signals were detected b y means of a piezoelectric sensor with integrated preamplifier. Freque ncy and position sensitivity of the sensor has been measured by laser excitation. Ion acoustic measurements have been carried out at the res onance frequencies of the sensor. A dependence on the sample material was found. The results show that the ion acoustic effect can be utiliz ed for imaging and material analysis in focused ion beam systems. (C) 1996 American Institute of Physics.