Impact of design factors and environment on the ESD sensitivity of MEMS micromirrors

In this paper, electrostatic discharge (ESD) tests on electrostatically actuated torsional micromirrors are performed in various pressure conditions and the ESD failure levels are reported for the first time in literature. The influence of device design factors of the micromirror, such as the torsional hinge width and the actuation bottom electrode area, on the ESD sensitivity is investigated. HBM ESD stress tests are performed in standard atmospheric pressure and in vacuum. These design parameters and the ambient pressure conditions are shown to affect the ESD failure levels of the MEMS micromirrors. Two distinct failure signatures are observed for micromirrors, viz., pull-in and sticking to the bottom electrode or getting destroyed and broken under the impact of the ESD stress.