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.