System and method for detecting flow in a mass flow controller

Abstract

Systems and methods are provided for detecting flow in a mass flow controller (MFC). The position of a gate in the MFC is sensed or otherwise determined to monitor flow through the MFC and to immediately or nearly immediately detect a flow failure. In one embodiment of the present invention, a novel MFC is provided. The MFC includes an orifice, a mass flow control gate, an actuator and a gate position sensor. The actuator moves the control gate to control flow through the orifice. The gate position sensor determines the gate position and/or gate movement to monitor flow and immediately or nearly immediately detect a flow failure. According to one embodiment of the present invention, the gate position sensor includes a transmitter for transmitting a signal and a receiver for receiving the signal such that the receiver provides an indication of the position of the gate based on the signal received. Other embodiments of the gate position sensor are described herein, as well as systems and methods that incorporate the novel MFC within a semiconductor manufacturing process.

1 . A method, comprising: 
 oscillating a gate in an ultrasonic mass flow controller; and    monitoring the gate to detect gate operability.    
   
   
       2 . The method of  claim 1 , wherein monitoring the gate includes verifying an actual gate position against a desired gate position.  
   
   
       3 . The method of  claim 1 , wherein monitoring the gate includes transmitting a signal, receiving the signal, and determining whether the gate has moved or is moving based on a received signal.  
   
   
       4 . The method of  claim 1 , wherein monitoring the gate includes transmitting a signal, receiving the signal, and determining gate operability based on the signal received.  
   
   
       5 . The method of  claim 1 , wherein monitoring the gate includes applying electric potential across the gate and an orifice in the flow controller, and detecting current flowing through a junction formed by the orifice and the gate when the gate is closed.  
   
   
       6 . The method of  claim 1 , wherein monitoring the gate includes generating a physical wave in the mass flow controller using a physical wave generator, receiving a physical wave in the mass flow controller using a physical wave receiver, and determining whether a position of the gate based on a detected physical wave signal.  
   
   
       7 . The method of  claim 1 , wherein monitoring the gate includes transmitting a light signal in the mass flow controller, receiving the light signal, and determining a positioned of the gate based on a detected light signal.  
   
   
       8 . The method of  claim 1 , wherein monitoring the gate includes producing magnetic flux, detecting a magnetically induced signal in a cooperating induction coil positioned within the magnetic flux, and determining that the gate has moved based on a detected signal in the induction coil.  
   
   
       9 . A method, comprising: 
 providing a mass flow controller in an ultrasonic mass flow line;    oscillating a gate in the mass flow controller at a desired frequency between an opened position and a closed position in order to control flow in the mass flow line; and    monitoring gate movement.    
   
   
       10 . The method of  claim 9 , wherein monitoring gate movement includes verifying an actual gate position against a desired gate position.  
   
   
       11 . The method of  claim 9 , wherein monitoring gate movement includes transmitting a signal in the mass flow controller, receiving the signal, and determining whether the gate is opened or closed based on the signal received.  
   
   
       12 . The method of  claim 9 , wherein oscillating a gate at a desired frequency includes varying a duty cycle to adjust mass flow through the mass flow controller.  
   
   
       13 . A semiconductor processing method for delivering a semiconductor gas, comprising: 
 providing a mass flow controller in an ultrasonic semiconductor gas flow line;    oscillating a gate in the mass flow controller between an opened position and a closed position to control semiconductor gas flow; and    monitoring operation of the gate by transmitting a signal, receiving the signal, and determining whether the gate is opened or closed based on the signal received.    
   
   
       14 . The method of  claim 13 , wherein 
 transmitting a signal includes applying electric potential across the gate and an orifice in the flow controller, and    receiving the signal includes the step of detecting current flowing through a junction formed by the orifice and the gate when the gate is closed.    
   
   
       15 . The method of  claim 13 , wherein 
 transmitting a signal includes generating a physical wave in the mass flow controller using a physical wave generator,    receiving the signal includes receiving a physical wave in the mass flow controller using a physical wave receiver, and    determining whether the gate is opened or closed includes determining whether a position of the gate based on a detected physical wave signal.    
   
   
       16 . The method of  claim 13 , wherein 
 transmitting a signal includes transmitting a light signal in the mass flow controller,    receiving a signal includes receiving the light signal, and    determining whether the gate is opened or closed includes determining a positioned of the gate based on a detected light signal.    
   
   
       17 . The method of  claim 13 , wherein 
 transmitting a signal includes producing magnetic flux,    receiving a signal includes detecting a magnetically induced signal in a cooperating induction coil positioned within the magnetic flux, and    determining whether the gate is opened or closed includes determining that the gate has moved based on a detected signal in the induction coil.    
   
   
       18 . A method for detecting a gas flow failure in a semiconductor manufacturing process, comprising: 
 providing a flow controller in a semiconductor gas inflow line;    oscillating a gate in the flow controller to control flow; and    monitoring the gate to detect gate operability.    
   
   
       19 . The method of  claim 18 , wherein monitoring the gate includes verifying an actual gate position against a desired gate position.  
   
   
       20 . The method of  claim 18 , wherein monitoring the gate includes transmitting a signal, receiving the signal, and determining whether the gate has moved or is moving based on a received signal.  
   
   
       21 . The method of  claim 18 , wherein the monitoring the gate includes determining that the gate is either stuck in an open position or stuck in a closed position.