Automated gate valve operation for pressure control

An automated pressure control system is described. The components consist of a reversible, geared, ac motor, a gate valve, a Granville-Phillips Stabil-ion pressure gauge with set-points and an electronics switching unit. The reversible motor is attached to the adjustment shaft of the Sate valve and the system is operated in conjunction with a diffusion pump. The orifice of the gate valve is varied so that the chamber pressure is maintained between two selected set-points fixed on the control unit of the Stabil-ion pressure gauge. The system is used to control the operating pressure in a chemical vapor deposition process. It has been found to work satisfactorily for bath gas and liquid phase precursor materials. The simplicity of the system together with its low cost allows for its use in a variety of low-pressure processes. (C) 1998 American Institute of Physics.