Thin Film Heater on a Thermally Isolated Microstructure

Abstract

ABSTRACTA microheater was fabricated on a thermally isolated silicon (Si) membrane and its electrical and thermomechanical properties were assessed. The sensor design was adjusted for good thermal isolation and good resistance to thermal shock. The heater was a platinum (Pt) thin-film meandering filament deposited with electron beam evaporation and patterned with lift-off methods. In order to operate the heater at high temperatures with minimum loss of Pt by evaporation, the heater was encapsulated with a ceramic film. During the heater operation, most of the heat was dissipated via conduction through the Si membrane which supported the multi-layered heater. When the Si membrane was completely etched away to suspend the heater, the power needed to heat the filament to strong incandescence (about 700–800°C) was 110 mW. Structural failure was not observed when the device was subjected to thermocycling up to approximately 500°C. The importance of the thermomechanical match of layers in a multi-layered heater structure, especially for use at high temperatures, is addressed.