Simple Fabrication and Characterization of a Platinum Microhotplate Based on Suspended Membrane Structure

摘要

One of the key components of a microsensor is the Micro electromechanical system (MEMS) microheater. It has a wide range of applications such as gas sensors, pressure sensors, and so on. In this study, a platinum microhotplate based on suspended membrane structure is introduced. A simple microfabrication process is adopted to form the micromachined suspended microheater. Some integrated circuit processes such as E-beam evaporation of Pt and Au, oxidation, wet etching process, and photolithography process are used to fabricate the device. As the usage of deep-reactive ion etching and low-pressure chemical vapor deposition systems are avoided, the microfabrication process of the hotplate is accessible even in laboratories with limited equipment. In order to achieve uniform temperature distribution over the active heater area and to increase the robustness of the membrane, a thin silicon island was placed underneath the dielectric membrane. Thermal and thermomechanical behaviors of this structure obtained by finite element analysis show that the designed microhotplate is relatively strong. Experimental results show that power consumption and time constant are 50mW and 4.23 ms, respectively, for the temperature variation from 30 degrees C to 500 degrees C in the fabricated microhotplates.