An 8-bit microflow controller using pneumatically-actuated microvalves [for semiconductor process gases]

This paper reports a pneumatically actuated, integrated 8-bit mass microflow controller (/spl mu/FC) that utilizes silicon microvalves. It is intended for the precision control of semiconductor process gases in the range from 0.1 to 10 sccm. The structure was designed to be batch-fabricated and compatible with on-chip thermopneumatic actuation. Assembled /spl mu/FC devices operate over a flow range of 0.5-10 sccm at 16 psid (800 torr). The valves alone may achieve significantly higher flow rates. Valve leak rates are as low as 10/sup -3/ sccm under 26 psig actuation pressure. Depositing parylene on the microvalves further improves leak rates by a factor as great as 3.5. This lays the foundation for a precision 0.1-10 sccm microflow controller for process gases, as well as a reliable silicon microvalve for other applications.