Title :
An ultrasensitive silicon pressure-based flowmeter
Author :
Cho, S.T. ; Najafi, K. ; Lowman, C.L. ; Wise, K.D.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI, USA
Abstract :
An ultrasensitive silicon pressure-based flowmeter has been developed for use in measuring sub-SCCM gas flows in semiconductor process equipment. The device utilizes a capacitive pressure sensor to measure the pressure drop induced by flow across a micromachined silicon microchannel. The flowmeter is fabricated using a single-sided dissolved-wafer process and requires only six masks. The processed silicon wafer is electrostatically bonded to a glass substrate and the wafer is selectively etched away, using boron etch-stops to define the final silicon-on-glass device structure. The capacitive pressure sensor uses a thin (2.2- mu m) stress-compensated membrane, which enables the sensor to monitor differential pressure as low as 1 mtorr while withstanding overpressures greater than 700 torr. The flowmeter is capable of measuring flows in the 10/sup -5/ SCCM range.<>
Keywords :
elemental semiconductors; flowmeters; micromechanical devices; pressure transducers; semiconductor technology; silicon; 1*10/sup -3/ to 720 torr; 2.2 micron; Si wafer; capacitive pressure sensor; differential pressure; electrostatic bonding; etch-stops; glass substrate; masks; micromachined microchannel; overpressures; pressure drop; semiconductor process equipment; single-sided dissolved-wafer process; stress-compensated membrane; sub-SCCM gas flows; ultrasensitive pressure-based flowmeter; wafer processing; Capacitive sensors; Electrostatic measurements; Etching; Fluid flow; Fluid flow measurement; Glass; Microchannel; Pressure measurement; Silicon; Wafer bonding;
Conference_Titel :
Electron Devices Meeting, 1989. IEDM '89. Technical Digest., International
Conference_Location :
Washington, DC, USA
Print_ISBN :
0-7803-0817-4
DOI :
10.1109/IEDM.1989.74330