Applications for closed-loop motor control

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. The closed-loop motor control approach of the present invention has also been adapted to other semiconductor and vacuum processing applications, including linear and rotary feedthrough devices and impedance matching networks.

What is claimed is:  
     
         1 . A feedthrough device, comprising: 
 a sample head;    a sample head motor means operatively connected to position said sample head, said sample head motor means further comprising a feedback signal generator for generating motor position feedback signals; and    a sample head drive means in communication with said sample head motor means, said drive means configured to generate discrete position commands for said motor means and said sample head drive means further configured to receive said motor position feedback signals.    
     
     
         2 . The device of  claim 1 , further comprising an internal sample head command conduit for carrying said commands and said signals between said sample head motor means and said sample head drive means.  
     
     
         3 . The device of  claim 2 , wherein said sample head drive means further comprises a summing junction for summing said position feedback signals and said position commands and responsively generating resultant position commands.  
     
     
         4 . The device of  claim 3 , wherein said summing junction, said internal sample head command conduit and said feedback signal generator comprise a sample head motor drive and feedback system.  
     
     
         5 . The device of  claim 4 , wherein said sample head motor means comprises a X-motor means, said X-motor means operatively connected to position said sample head along an X-axis, said X-motor means further comprising an X-axis feedback signal generator for generating X-motor means position feedback signals.  
     
     
         6 . The device of  claim 4 , wherein said sample head motor means comprises a Y-motor means, said Y-motor means operatively connected to position said sample head along a Y-axis, said Y-motor means further comprising a Y-axis feedback signal generator for generating Y-motor means position feedback signals.  
     
     
         7 . The device of  claim 4 , wherein said sample head motor means comprises a Z-motor means, said Z-motor means operatively connected to position said sample head along an Z-axis, said Z-motor means further comprising a Z-axis feedback signal generator for generating Z-motor means position feedback signals.  
     
     
         8 . The device of  claim 4 , wherein said sample head motor means comprises an R-motor means, said R-motor means operatively connected to rotationally position said sample head around a primary axis, said R-motor means further comprising an R-axis feedback signal generator for generating R-motor means position feedback signals.  
     
     
         9 . The device of  claim 5 , wherein said sample head motor means comprises a Y-motor means, said Y-motor means operatively connected to position said sample head along a Y-axis, said Y-motor means further comprising a Y-axis feedback signal generator for generating Y-motor means position feedback signals.  
     
     
         10 . The device of  claim 9 , wherein said sample head motor means comprises a Z-motor means, said Z-motor means operatively connected to position said sample head along an Z-axis, said Z-motor means further comprising a Z-axis feedback signal generator for generating Z-motor means position feedback signals.  
     
     
         11 . The device of  claim 10 , wherein said sample head motor means comprises an R-motor means, said R-motor means operatively connected to rotationally position said sample head around a primary axis, said R-motor means further comprising an R-axis feedback signal generator for generating R-motor means position feedback signals.  
     
     
         12 . An impedance matching network for controlling generated RF power, said power usedby an RF electrode to generate and control a plasma field in a process chamber, said network comprising a rotor linkage means for actuating a rotor, the impedance matching network comprising: 
 a feedback generating rotor assembly motor means for actuating said rotor linkage means, said motor means further comprising a position feedback signal generator means;    a rotor shaft drive means in communication with said motor means, said rotor shaft drive means configured to send position command signals to said motor means and further to receive signals generated by said position feedback signal generator means; and    a motor means/drive means feedback system interconnecting said motor means and said rotor shaft drive means.    
     
     
         13 . The network of  claim 12 , wherein said motor means further comprises a motor drive attached to said rotor linkage means.  
     
     
         14 . The network of  claim 13  wherein said motor means further comprises reduction gear means operatively attached between said motor drive and said rotor linkage means.