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 gate position sensor, comprising: 
 an orifice and a gate adapted to adjust flow through the orifice;    a light source to generate a light signal; and    a light detector adapted to receive the light signal, the light detector being operably positioned with respect to the light source and the orifice such that movement of the gate with respect to the orifice affects a received light signal.    
   
   
       2 . The sensor of  claim 1 , wherein gate movement interrupts the light signal.  
   
   
       3 . The sensor of  claim 1 , wherein the orifice and the gate are an orifice and a gate from an ultrasonic mass flow controller adapted to control gas flow from a semiconductor gas source to a semiconductor processing chamber.  
   
   
       4 . The system of  claim 1 , wherein the gate is adapted to oscillate between an open and closed position with respect to the orifice.  
   
   
       5 . A gate position sensor, comprising: 
 a transmitter for transmitting a signal in a flow controller, wherein a position of a gate in the flow controller affects the signal; and    a receiver for receiving the signal, wherein the receiver is adapted to provide a signal output for the sensor to indicate a gate position within the flow controller based on the signal received,    wherein the transmitter is a light source, the signal is a light signal transmitted by the light source, and the receiver is a light detector operably positioned with respect to the light source and an orifice such that movement of the gate oscillating between an opened position and a closed position interrupts the light signal from being received by the light detector.    
   
   
       6 . The sensor of  claim 5 , wherein the transmitter includes a transmitter for transmitting a signal in a mass flow controller.  
   
   
       7 . The sensor of  claim 5 , wherein the transmitter includes a transmitter for transmitting a signal in an ultrasonic mass flow controller.  
   
   
       8 . A gate position sensor for a flow controller having an orifice and a gate for closing the orifice, comprising: 
 a light source positioned on a first side of the orifice; and    a light detector positioned with respect to the light source and the orifice such that movement of the gate oscillating between an opened position and a closed position interrupts a light signal generated by the light source from being received by the light detector.    
   
   
       9 . The sensor of  claim 8 , wherein the sensor is adapted to sense gate movement for an ultrasonic mass flow controller.  
   
   
       10 . The sensor of  claim 8 , wherein the sensor is adapted for use in monitoring a frequency of gate oscillations.  
   
   
       11 . The sensor of  claim 8 , wherein the sensor is adapted for use in detecting a position of the gate.  
   
   
       12 . The sensor of  claim 11 , wherein the sensor is adapted to detect a light intensity.  
   
   
       13 . A system, comprising: 
 an ultrasonic mass flow controller with an orifice and a gate adapted to close the orifice;    a sensor, including:    a light source positioned on a first side of the orifice; and    a light detector positioned with respect to the light source and the orifice such that movement of the gate oscillating between an opened position and a closed position affects light received by the light detector from the light source.    
   
   
       14 . The system of  claim 13 , further comprising: 
 a semiconductor gas source;    a semiconductor processing chamber; and    a gas flow line connecting the gas source to the processing chamber, the ultrasonic mass flow controller being adapted to control gas flow through the line from the gas source to the processing chamber.    
   
   
       15 . The system of  claim 13 , further comprising a processor connected to the ultrasonic mass flow controller, the light source, and the light detector.  
   
   
       16 . The system of  claim 13 , wherein the sensor is adapted to sense gate movement.  
   
   
       17 . The system of  claim 13 , wherein the sensor is adapted for use in monitoring a frequency of gate oscillations.  
   
   
       18 . The system of  claim 13 , wherein the sensor is adapted for use in detecting a position of the gate.  
   
   
       19 . The system of  claim 18 , wherein the sensor is adapted to detect a light intensity.  
   
   
       20 . A system, comprising: 
 an inflow line;    a flow controller positioned in the inflow line for controlling flow, the flow controller including a gate and an actuator for moving the gate to control flow; a gate position sensor for monitoring whether the gate is in an opened position or a closed position, the sensor including means for transmitting a signal in the flow controller such that a position of the gate in the flow controller affects the signal, and means for receiving the signal and providing a signal output for the sensor to indicate a gate position within the flow controller based on the signal received; and    a processor for controlling the position of the gate and for interfacing with the sensor,    wherein the sensor includes a light source and a light detector, and wherein the light source and the light detector are operably positioned with respect to each other and an orifice such that movement of the gate oscillating between an opened position and a closed position interrupts the light signal from being received by the light detector.    
   
   
       21 . The system of  claim 20 , further comprising: 
 a semiconductor gas source; and    a semiconductor processing chamber, wherein the ultrasonic mass flow controller is adapted to control gas flow through the inflow line from the gas source to the processing chamber.    
   
   
       22 . The system of  claim 20 , wherein the sensor is adapted to sense gate movement.  
   
   
       23 . The system of  claim 20 , wherein the sensor is adapted for use in monitoring a frequency of gate oscillations.  
   
   
       24 . The system of  claim 20 , wherein the sensor is adapted for use in detecting a position of the gate.  
   
   
       25 . The system of  claim 24 , wherein the sensor is adapted to detect a light intensity.