A Self-Controlled Microcontrolled Microvalve

Integrated microvalves are needed for a broad range of semiconductor-processing-related applications. These include precision mass microflow controllers (laFCs) for dry etch systems, miniature gas chromatography systems for real-time monitoring, point-of-use semiconductor process reactant generators, and compact control systems for minienvironments. This paper reports a pneumatically actuated, integrated silicon microvalve, which was developed as a forerunner to an 8b }.tFC intended for the precision control of semiconductor process gases in the range from 0.1 to 10sccm. The structure was designed to be batch-fabricated and compatible with on-chip thermopneumatic actuation. Assembled single-bit ~tFC devices achieve the targeted flow rate of 5sccm (determined by an in-line flow channel) at 20psid (1034torr). The valve alone may achieve significantly higher flow rates. The leak rate is 0.08sccm under 26. l psig actuation pressure, and the valve can seal against pressures greater than 29psid (1500tort).