Design And Fabrication Of Micro-hotplate Based On MEMS Technology

Micro-heater based on MEMS technology has a greater development in the gas sensor, infrared emitter, gas flowmeter, micro calorimetry, infrared source areas and so on. It has advantages of low heating power, fast response time, low thermal loss, compatible with CMOS technology, easy to integrate with other microelectronic devices etc. The suspended micro-hotplate can effectively reduce the thermal conductivity and heat loss, improve the micro-heater temperature, becomes the dominant type of micro-heater.This paper aims to design and fabricate the suspended micro-hotplate with silicon-on-insulator (SOI) substrate, carry out the micro-heater's theoretical analysis and experiment study, which mainly include:(1) Summarizing the working principle, the structure type and the traditional processing technology of micro-hotplate, while analyzing its thermal, mechanical theory simply. Design the structure and optimize the size of micro-heater based on theoretical analysis; according to laboratory's experimental conditions, choose suitable materials, present a set of fabrication processes. Besides, draw a complete set of mask.(2) Using COMSOL multi-physics coupling analysis software simulate the thermal and mechanical properties of micro-hotplate structure we designed, get the temperature distribution, thermal stress distribution, thermal expansion and deformation results, which provide a theoretical basis for the micro-hotplate.(3) Suspended micro-hotplate were produced, and the key experimental parameters were explored, including photolithography, thin film deposition, lift-off, dry etching and wet etching processes. Lift-off process has certain requirements for photolithography and thin film deposition process; Prior to RIE dry etching process, a nickel/cadmium film was deposited as a protective layer; In the wet etching process, a specially crafted fixture was used to protect the front structure of the substrate; finally the micro-hotplate was completed.