Low-Actuation Voltage MEMS Digital-to-Analog Converter with Parylene Spring Structures

Area of Science:

• Microelectromechanical Systems (MEMS)
• Materials Science
• Nanotechnology

Background:

• Microelectromechanical digital-to-analog converters (M-DACs) are crucial for interfacing digital and analog signals in microscale systems.
• Traditional M-DACs often require high actuation voltages, limiting their power efficiency and integration possibilities.
• Silicon-based MEMS fabrication typically utilizes materials with high Young's modulus, necessitating higher electrostatic actuation forces.

Purpose of the Study:

• To develop an electrostatically-actuated M-DAC with significantly reduced actuation voltage.
• To leverage the unique material properties of parylene-C for enhanced microactuator performance.
• To demonstrate the potential of the proposed M-DAC as a component in noncontact surface profiling systems.

Main Methods:

• Monolithic fabrication of silicon-based M-DAC spring structures using parylene-C.
• Design and implementation of electrostatic microactuators utilizing parylene-C's low Young's modulus.
• Characterization of actuation voltage, total displacement, and motion step of the fabricated three-bit M-DAC.

Main Results:

• The proposed M-DAC achieved a low actuation voltage of approximately 6 V, less than half of previously reported devices.
• The parylene-C springs enabled electrostatic microactuators requiring substantially lower voltages.
• A measured total displacement of nearly 504 nm and a motion step of approximately 72 nm were achieved for the three-bit M-DAC.

Conclusions:

• The developed M-DAC effectively utilizes parylene-C to lower electrostatic actuation voltage requirements.
• The device demonstrates promising performance metrics for displacement and motion step.
• The M-DAC's capability as a mirror platform for noncontact surface profiling was successfully demonstrated, highlighting its practical applications.