Transient heating study of microhotplates by using a high-speed thermal imaging system

A high-speed thermal imaging system is used to investigate the dynamic thermal behavior of MEMS (microelectromechanical systems) based microhotplate devices. These devices are suspended microstructures fabricated in CMOS technology and are used in various sensor applications. Measurements reveal delayed surface heating of the microhotplate and temperature redistribution during both the heating and cooling phases. Reflected infrared (IR) radiation from the hidden backside of the heater is used with a normalization technique to determine peak heater temperature. The measurements are shown to be useful in optimizing the design of microhotplate structures. It is found that the use of a heat-spreading layer improves the local temperature uniformity between the heater strips. It is also found that the use of the thinner layers of the 1.5 /spl mu/m CMOS technology improve the global temperature uniformity over the top surface of the microhotplate.