Temperature Stabilization for MEMS Devices
By Seri Lee, Ph.D., Nextreme Thermal Solutions
Advances in thin-film thermoelectrics enable novel temperature stabilization for applications in MEMS packaging. As the electronics industry moves towards smaller packaging form factors and higher heat densities, non-uniform thermal conditions can directly affect the performance and reliability of MEMS devices.
Designers of MEMS-based products not only need to worry about the environmental stresses but also the thermal stresses devices may experience as a part of the fabrication or packaging process. For this reason and due to their typically low thermal mass, MEMS devices, when in operation, must have a tightly controlled thermal management system.
MEMS devices tend to be sensitive, fragile, and difficult to fabricate and package. As such, they can be affected by thermal excursions during the manufacturing process or during operation. Minimizing these temperature excursions and package-induced stresses will lead to a more reliable, tightly controlled device.
Thermal management systems comprise either passive or active devices. Because MEMS devices tend to be temperature sensitive, passive thermal management schemes offer minimal control for these types of devices. Active thermal management systems such as water-based cooling with mechanical pumps tend to be bulky, unreliable, and more difficult to implement. From an electromechanical point of view, bulk and now thin-film thermoelectric coolers (TECs) offer an attractive option for active control with enhanced reliability.
TECs have been used to temperature stabilize these very sensitive devices and allow for more well-defined performance characteristics. Thin-film based TECs offer an additional level of control due to their exceptionally low thermal mass which is oftentimes on the order of the mass of the device itself as opposed to traditional TECs that may be 100