Patent Number: 6,612,331

Title: Pressure controller and method

Abstract: A closed loop pressure controller system that sets, measures and controls the process pressure within a semiconductor process is shown. The system is commonly composed of a pressure sensor to collect the pressure information, a controller box that hosts the control electronics, and a valve to physically affect the conductivity of the inlet or outlet gas line and accordingly the process pressure. The present invention differs from the prior art by using closed-loop motor control of the valve, rather than the method of the prior art, where the valve position is controlled by a stepper motor actuator driven in an open loop fashion. It is demonstrated that the utility of such prior art open-loop configurations is limited by the fact that the achievable precision of the valve position is hindered by static friction in the valve system, and the non-linear character of the torque versus shaft-angle of the motor (among other error components). The method of the present invention more accurately positions the valve, and accordingly enhances the overall precision and allowable loop-gain of the pressure control system by providing the valve drive with feedback as to the actual angular position of the valve in extremely high resolution.

Inventors: Cederstav; Per (San Diego, CA), Mallory; Sean (San Diego, CA), Vyers; Emmanuel (San Diego, CA), Ballard; William (San Diego, CA), Kruse; David (San Diego, CA)


International Classification: G05D 16/20 (20060101); F16K 031/04 (); G05D 007/06 ()

Expiration Date: 09/02/2020