Towards Robust Thermal MEMS: Demonstration of a Novel Approach for Solid Thermal Isolation by Substrate-Level...

Area of Science:

• Materials Science
• Mechanical Engineering
• Electrical Engineering

Background:

• Current microelectromechanical systems (MEMS) for thermal applications rely on fragile components like thin-film membranes and microcantilevers, limiting their robustness.
• There is a need for solid, MEMS-compatible thermal insulators to improve the durability of microscale devices.

Purpose of the Study:

• To develop and evaluate a novel approach for microscale thermal isolation using porous microstructures fabricated with the PowderMEMS process.
• To assess the thermal conductivity of these porous structures in both ambient air and vacuum conditions.

Main Methods:

• Microelectromechanical systems (MEMS) devices with integrated heaters on thin-film membranes were modified with porous microstructures made from three distinct materials.
• A thermal model was developed to estimate the resulting thermal conductivity of the porous structures.
• Experimental measurements of thermal conductivity were performed for the fabricated structures under ambient air and vacuum.

Main Results:

• The PowderMEMS process successfully created microscale thermal insulators within silicon cavities at the wafer level.
• The best-performing porous material exhibited thermal conductivities close to 0.1 W/mK in ambient air and approximately 0.04 W/mK under vacuum.
• These measured thermal conductivities are lower than those reported for glass and porous silicon.

Conclusions:

• The PowderMEMS process offers a viable and robust alternative for creating solid microscale thermal insulators.
• The developed porous microstructures demonstrate significantly low thermal conductivity, enhancing thermal isolation in MEMS devices.
• This technology presents a promising solution for improving the reliability and performance of thermal MEMS.