Title :
A Microdischarge-Based Monolithic Pressure Sensor
Author :
Eun, C.K. ; Xin Luo ; Jun-Chieh Wang ; Zhongmin Xiong ; Kushner, M. ; Gianchandani, Y.
Author_Institution :
Center for Wireless Integrated MicroSensing & Syst., Univ. of Michigan, Ann Arbor, MI, USA
Abstract :
This paper describes the investigation of a microdischarge-based approach for sensing the diaphragm deflection in a monolithically fabricated pressure sensor. This transduction approach is appealing from the viewpoint of miniaturization. The device consists of a deflecting Si diaphragm with a sensing cathode, and a glass substrate with an anode and a reference cathode. The total exterior volume of the device is 0.05 mm3; typical electrode size and separations are 35 and 10 mm3. Pulsed microdischarges are initiated in a sealed chamber formed between Si and glass chips, and are filled with Ar gas. External pressure deflects the Si diaphragm and changes the interelectrode spacing, thereby redistributing the current between the anode and two competing cathodes. The differential current is indicative of the diaphragm deflection which is determined by the external pressure. A 6-mask microfabrication process is investigated for device fabrication. Electrode connections to the interior of the chamber are provided by laser drilling and copper electroplating through high aspect ratio glass vias. The Si and glass substrates are bonded by Au-In eutectic. The redistribution of plasma current between competing cathodes, as a consequence of diaphragm deflection over a range of pressure, was experimentally demonstrated. First principles modeling of transient microdischarges have provided insights to the fundamental processes responsible for the differential current and guidance for scaling the device to smaller dimension.
Keywords :
bonding processes; electrochemical electrodes; electroplating; elemental semiconductors; glass; laser beam machining; microfabrication; microsensors; pressure measurement; pressure sensors; pressure transducers; silicon; 6-mask microfabrication process; Si; anode; copper electroplating; diaphragm deflection sensing; differential current; distance 10 mum; electrode connection; eutectic bonding; glass substrate; interelectrode spacing; laser drilling; plasma current redistribution; pulsed microdischarge-based monolithically fabricated pressure sensor; reference cathode; sealed chamber; size 35 mum; transduction approach; Cathodes; Microfabrication; Monolithic integrated circuits; Pressure measurement; Sensors; Thermal factors; Through-glass vias (TGVs); electroplating; eutectic bonding; plasma modeling; plasma modeling.;
Journal_Title :
Microelectromechanical Systems, Journal of
DOI :
10.1109/JMEMS.2014.2312174