Abstract-The susceptibility of single-crystal silicon and SU-8 resonators to proton-radiation induced degradation was investigated. Both materials are in widespread use for microsystems structures, thus the stability of the mechanical properties must be ensured over the full device lifecycle. Effects of spacerelevant proton doses were examined by monitoring minute changes in the Young's modulus and by structural investigations using high-resolution X-ray diffraction (HRXRD). Single crystal silicon resonators were exposed to 10 MeV and 60 MeV protons with doses up to 10 13 cm −2 . Even at the highest doses neither a change of the Young's modulus was observed nor did Xray diffraction indicate the formation of elevated concentrations of structural defects. The compatibility of SU-8 with inorbit radiation environments was investigated at fluences of 10 10 -10 12 cm −2 using protons with energies ranging from 10 MeV to 200 MeV. Its elastic modulus changed by less than 5.5% at the highest doses.[2013-0009]

We report on the susceptibility of structural MEMS materials to proton radiation damage. Radiation tests at spacerelevant doses were conducted on MEMS resonators. The two materials examined were single crystal silicon and SU-8, which are both in widespread use in microsystems. The resonance frequency was monitored for measuring minute changes of the Young's modulus. No radiation-induced changes of the elasticity were observed in the silicon devices up to fluences of 10 13 cm-2 , corresponding to a total ionizing dose (TID) of over 5.5 MRad for 10 MeV protons. The SU-8 resonators showed a variation of less than ±5.5% at doses of up to 1.4 Mrad (TID). Chemical and structural analyses of the polymer were performed using infrared absorption spectroscopy and x-ray diffraction methods. We discuss possible mechanisms for the observed changes of the elasticity of SU-8.