AVS 47th International Symposium
    Manufacturing Science and Technology Friday Sessions
       Session MS-FrM

Paper MS-FrM6
A Wide Range Vacuum Sensor Fabricated by MEMS

Friday, October 6, 2000, 10:00 am, Room 304

Session: Langmuir Award/Ultra Clean Society and Contamination Free Manufacturing
Presenter: Y. Kitamura, ANELVA Corporation, Japan
Authors: H. Miyashita, ANELVA Corporation, Japan
Y. Kitamura, ANELVA Corporation, Japan
H. Watanabe, ANELVA Corporation, Japan
M. Esashi, Tohoku University, Japan
Correspondent: Click to Email
A wide range capacitive vacuum sensor has been developed by microelectromechanical system (MEMS) technology. Use of MEMS technology has many advantages such as ability to miniaturization of the sensor, mass production, cost reduction etc. when compared to the conventional mechanical processes. The reason is that MEMS process is very similar to that of semiconductor device fabrication processes. The sensor is comprised of an SD2 glass and a silicon substrate. The length, width and thickness of the sensor is 20mm, 20mm, and 1.4mm, respectively. The fabricated vacuum sensor has two silicon diaphragms with 4mm x 4mm and 1mm x 1mm dimensions, and the thickness of the diaphragms is 7µm. Since the deflection of a diaphragm depends on the diaphragm size, the sensor measures a wide range of pressure. The smaller diaphragm shows linear characteristics of electrostatic capacitance at the pressures below 40,000Pa. The larger diaphragm shows linear characteristics of electrostatic capacitance at the pressures below 200Pa. The developed sensor is able to measure pressure in the range of 0.04Pa to 40,000Pa. This is achieved by using an electrical circuit which converts electrostatic capacitance into voltage over three orders. The same technology is applicable to the fabrication of vacuum sensors that measure pressures in other ranges by changing the size of the diaphragms. Moreover, the number of diaphragms in a sensor also can be increased to enhance the pressure-monitoring region without increasing the fabrication processing steps.