Design and Fabrication of High Vacuum Gauge Based on Micro Hotplate

Abstract

Vacuum gauge based on micro hotplate (MHP) is a kind of promising MEMS vacuum gauge due to its advantages including high sensitivity, wide measurement range, fast response speed and comparably easy fabrication, etc. In this paper, through analyzing various of heat dissipation approaches including solid heat conduction, gas heat conduction, heat radiation, and convection, the sensor output expression of MHP-based vacuum gauge is obtained when keeping electric current of heating resistor constant. With the structure size and material properties, the relationship curve between vacuum gauge output and gas pressure can be obtained. By wet etching silicon under the compound dielectric films with embedded metal film resistor, MHP suspended over silicon substrate is fabricated. Then the sensor chip is assembled and put into vacuum system, and test is conducted when keeping the heating resistor at constant heating current of 5mA. The measurement results show that the sensor measurement range is 5×10-3Pa~103Pa, which is basically consistent with the theoretical analyzing results.