Theoretical study on influence of impulity concentration on behavior of a semiconductor electrostatic actuator

Abstract

Influence of impulity concentration on behavior of a semiconductor electrostatic actuator in low frequency drive voltage has been analyzed theoretically. The actuator has a p-type silicon movable electrode supported by cantilever beams and a metal fixed electrode opposing to the movable one. When gap width between the electrodes is fixed, capacitance between them changes depending on the drive voltage and rate of the change increases with decrease of the concentration N_a (15% in N_a=10¹⁴cm^-3 and 0.3%in N_a=10¹⁸cm^-3). For Na<10¹⁶cm^-3, pull-in voltage and release voltage of displacement-voltage curves increases with decrease of the concentration, especially when positive voltage is applied to the fixed electrode. For N_a>10¹⁶cm^-3, the impulity concentration has almost no influences on the behavior of the actuator independent of the polarity of the drive voltage.