Through-Silicon Stroboscopic Characterization of an Oscillating MEMS Thermal Actuator Using Supercontinuum Interferometry

We measured the surface profile of the hidden face of a thermally actuated oscillating 4-μm-thick silicon microelectromechanical system (MEMS) bridge. To do this, we employed a stroboscopically synchronized supercontinuum light source incorporated into a scanning low-coherence interferometer. The instrument exploited the near-infrared part (1.1-1.7 μm) of the emitted spectrum and a camera sensitive to near infrared. The MEMS bridge was driven with 6.8-V sinusoidal voltage at 10 Hz, which resulted in oscillation amplitudes of 1.50 ± 0.07 μm and 1.35 ± 0.07 μm for the top and bottom surfaces, respectively. We believe this technique opens up new possibilities for validating simulation effort as well as for qualifying new device designs.