Evaluation of silicon tuning-fork resonators under space-relevant radiation conditions

Abstract

This work reports on irradiations made on silicon bulk-acoustic wave resonators. The resonators were based on a tuning fork geometry and actuated by a piezoelectric aluminum nitride layer. They had a resonance frequency of 150 kHz and a quality factor of about 20000 under vacuum. The susceptibility of the devices to radiation induced degradation was investigated using 60 Co γ-rays and 50 MeV protons with space-relevant doses of up to 170 krad. The performance of the devices after irradiation indicated a high tolerance to both ionizing damage and displacement damage effects. The results support the efforts towards design and fabrication of highly reliable MEMS devices for space applications.

Mechanical properties of MEMS materials: reliability investigations by mechanical- and HRXRD-characterization related to environmental testing

“…The results were attributed to a combination of displacement damage, injection annealing and thermal spike effects. The radiation tolerance of silicon tuning fork resonators activated by a thin film of AlN (the same devices on which the residual stresses were measured by HRXRD, as discussed above) was investigated in [67]. A very good immunity to irradiation both for ionizing radiation and displacement damage effects was observed and no significant variation of the resonance frequency was found within the experimental uncertainty of ±10 ppm Figure 3.…”

“…(◊ Directly after the irradiation and □ after 4 weeks annealing at room temperature). The figure was adapted from[67]. (b) Encapsulated MEMS tuning fork resonator and (c) X-ray tomography showing the sealing rings and the electrodes.…”