| AVS 65th International Symposium & Exhibition | |
| MEMS and NEMS Group | Thursday Sessions |
| Session MN+2D+AN+NS-ThA |
| Session: | Nonlinear and Thermal Resonators |
| Presenter: | Hailong Chen, Case Western Reserve University |
| Authors: | H.L. Chen, Case Western Reserve University H. Jia, Case Western Reserve University V. Pashaei, Case Western Reserve University W. Liao, Vanderbilt University C.N. Arutt, Vanderbilt University M.L. McCurdy, Vanderbilt University P. Hung, The Aerospace Corporation R.A. Reed, Vanderbilt University R.D. Schrimpf, Vanderbilt University M.L. Alles, Vanderbilt University P.X.-L. Feng, Case Western Reserve University |
| Correspondent: | Click to Email |
Space radiation (e.g., solar, galaxy) and man-made radiation environments (e.g., nuclear plant) can expose devices to radiation at doses that may lead to severe damage [1]. In recent decades, a large body of work has been performed to understand radiation effects on mainstream solid state electronic devices [1-3], in particular on MOS devices [2] and integrated circuits [3]. Lately, microelectromechanical systems (MEMS) have seen widespread adoption in consumer, military and aerospace products due to their small size, low power consumption, and in some cases, monolithic integration with electronics [4]. As such, the reliability of MEMS devices for many applications in relatively benign environments has been well established [5]. However, the study of impact on mechanical properties due to radiation-induced damages is an area where limited research has been conducted.
In this work, we report on experimental investigation of heavy ion radiation effects on mechanical properties of Si crystals, by exploiting a novel 3D scheme of using 5 vertically stacked micromachined vibrating Si diaphragms (2 mm × 2 mm x 2 µm) exposed to oxygen ions. Simulations find the stop range of oxygen ions in Si is 7.3 µm. A Pelletron system is employed to irradiate oxygen ions into the Si diaphragms (10.3MeV, with a dose of 5.6 ×1013/cm2). Before and after radiation, multimode resonances are characterized in vacuum by using an ultrasensitive optical interferometry system. We have observed that diaphragms D1 and D2, which oxygen ions are expected to pass completely through, present modest multimode redshifts ranging from 0.85 kHz to 1.67 kHz, and 0.85 kHz to 1.19 kHz, corresponding to an average fractional frequency shift of 10.5% and 7.0%, respectively. In contrast, for devices D3 and D4, in which most ions are expected to stop, each resonance peak shifts much more dramatically, with a frequency shift of 27.3% and 20.4%. We attribute these large shifts to the very large capture area of the diaphragms, the very heavy and energetic oxygen ions, and high ion dose. Device D5 shows minimal frequency shifts among the five diaphragms because few oxygen ions reach and interact with this device layer. The diaphragm stack exhibits outstanding capability for probing radiation damages in MEMS, not only able to capture the radiation events obviously, but also help analyze different amount and types of damages induced in each stacking layer.
[1] L. Gregory, et al., Proc. IEEE. 62, 1974. [2] J. R. Srour, et al., Proc. IEEE. 76, 1988. [3] H. L. Hughes, et al., IEEE Trans. Nucl. Sci. 50, 2003. [4] N. Arutt, et al., Semicond. Sci. Technol. 32, 2017. [5] H. R. Shea, Proc. SPIE. 7928, 2011.