Electrostatically actuated gas microvalve based on a Ta-Si-N membrane

An electrostatically actuated gas microvalve has been designed, fabricated and characterized. This valve is composed of a vertically moving, double-clamped Ta-Si-N membrane, located over a small (10 /spl mu/m), round orifice machined by deep reactive ion etching (DRIE) through the silicon substrate. The valve can be actuated as an on/off switch, or using pulse width modulation (PWM) to achieve a controlled flow rate. To our knowledge, previously reported, electrostatically actuated microvalves have had much larger orifices, which limited the operating pressures to less than 200 mbar, an order of magnitude lower than the valve presented. Furthermore, a controlled flow rate using PWM has never been demonstrated experimentally. The valve reported here thus represents the first working MEMS device integrating a sputtered Ta-Si-N layer, for use at differential pressures greater than 2 bar and capable of achieving controlled flow rates.