Angled electrode comb drives for enhanced actuator in silicon photonic applications

This paper presents an in-depth analysis of electrostatic comb drives, specifically focusing on angled finger configurations to optimize performance for high-demand silicon photonic devices. The study contributes to the advancement of optical microsystems, particularly for beam steering configurations, by simultaneously considering three key figures of merit: traveling range (or displacement), force, and footprint, which are essential for achieving high force intensity and large travel ranges. We investigate critical design parameters such as the number of fingers per arm, their dimensions, and arm dimensions to understand their influence on actuator performance. The research also adheres to design rules for commercially available foundries, ensuring that the proposed designs are manufacturable and suitable for practical implementation. Our findings highlight that angled fingers significantly enhance force intensity and travel range, providing operational flexibility essential for applications requiring a compact footprint alongside high-force capabilities. Through detailed simulations and experimental validations, we demonstrate how specific adjustments in comb drive configuration, like finger geometry and comb arrangement, effectively maintain extensive travel ranges while improving force intensity. We achieved a force intensity of over 200 mN/m² through optimized comb configurations and demonstrated how changes in configuration, even with the same finger and arm dimensions, significantly affect the force intensity. Furthermore, we introduce correction functions to compensate for common fabrication discrepancies, such as over-etching, enhancing the precision of manufacturing processes and ensuring alignment with design specifications. This work establishes a robust framework for developing high-performance MEMS actuators that balance the need for a compact footprint with stringent force and travel range requirements in beam steering and other advanced optical applications.