Publications
Laser-induced damage of polycrystalline silicon optically powered MEMS actuators
Optical MEMS devices are commonly interfaced with lasers for communication, switching, or imaging applications. Dissipation of the absorbed energy in such devices is often limited by dimensional constraints which may lead to overheating and damage of the component. Surface micromachined, optically powered thermal actuators fabricated from two 2.25 μm thick polycrystalline silicon layers were irradiated with 808 nm continuous wave laser light with a 100 μm diameter spot under increasing power levels to assess their resistance to laser-induced damage. Damage occurred immediately after laser irradiation at laser powers above 275 mW and 295 mW for 150 urn diameter circular and 194 urn by 150 μm oval targets, respectively. At laser powers below these thresholds, the exposure time required to damage the actuators increased linearly and steeply as the incident laser power decreased. Increasing the area of the connections between the two polycrystalline silicon layers of the actuator target decreases the extent of the laser damage. Additionally, an optical thermal actuator target with 15 μm × 15 μm posts withstood 326 mW for over 16 minutes without exhibiting damage to the surface. Copyright © 2005 by ASME.