THE EFFECTS OF ELECTRON-BEAM AND ION-BEAM IRRADIATION ON THE MECHANICAL RESPONSE OF SILICON MICRORESONATORS

We have investigated the mechanical response of silicon microresonator s exposed to electron- and ion-beam irradiation. The microresonators w ere single-crystal silicon structures consisting of beams similar to 0 .7 mu m wide, and having preirradiation frequency of 48 kHz and Q(-1) of 2.5x10(-5). For the electron-beam experiment, microresonator respon se was measured after 10 min irradiations with 10 keV electrons, for b eam currents ranging from 2 to 20 nA. The frequency shows a monotonic increase with electron dose, while the Q(-1) shows a peak versus dose. For the ion-beam experiment, the microresonator was irradiated with 3 .5 keV Ar+ ions for timed intervals up to 10 min. The microresonator f requency and Q(-1) exhibit extrema versus irradiation time. These mech anical-response changes are significant for both electron- and ion-irr adiation experiments, with frequency shifts similar to 0.1% and Q(-1) changes of a factor similar to 3. (C) 1995 American Vacuum Society.