Fig. 7: Impact of Fabrication Tolerances and Over-Etching on Triangular Comb Drive Performance.
From: Angled electrode comb drives for enhanced actuator in silicon photonic applications
a Singel beam spring over-etch study. The graph shows Stiffness vs. Displacement curves comparing ideal design (solid black) and a device with 20% reduced spring width (dashed red), showing decreased stiffness and increased displacement due to fabrication tolerances. Analysis of over-etching effects on MEMS actuator electrodes. b sketch for calculation of the effective angle (α1) post-overetch using tip over-etch (η), initial angle (α), and finger length (\({L}_{f}\)). c Comparison of designed (black dash line) vs. actual (red over etched parts and green non over etched parts) electrode profiles after over-etching. d Analysis for configurations with 6+ fingers shows stabilized over-etch effects. e Expanded view differentiates over-etched (orange) and unchanged (green) regions, highlighting changes in electrode angle (α‘) and gap. f Detailed adjustments and measurements for MEMS actuators with varying numbers of fingers per arm. g Pull-in voltage for different comb drive configurations (N = 1 to N = 5) using the analytical model, corrected model, and experimental results. h Maximum force, travel range, and bias voltage for each configuration based on the analytical calculations without correction function, highlighting performance differences across designs
