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: 
 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 physical wave generator, the signal is a physical wave propagating through a junction formed by the orifice and the gate when the gate is closed, and the receiver is a physical wave receiver for detecting the physical wave propagating through the junction.    
   
   
       2 . The gate position sensor of  claim 1 , wherein the receiver detects when the gate is in a closed position by sensing an increased amplitude in the physical signal received by the receiver.  
   
   
       3 . The gate position sensor of  claim 1 , wherein the physical wave receiver detects a complex wave formed from a superposition of a first physical signal propagated through a structure when the gate is in an opened positioned and a second physical signal directly propagated from the physical wave generator to the physical wave receiver when the gate is in a closed position.  
   
   
       4 . The gate position sensor of  claim 1 , wherein the physical wave generator and the physical wave receiver include piezoelectric crystals.  
   
   
       5 . The gate position sensor of  claim 1 , wherein the physical wave generator is the gate such that closing the gate generates a physical wave detectable by the physical wave receiver.  
   
   
       6 . The gate position sensor of  claim 1 , further comprising at least one intermediate receiver located between the generator and the receiver.  
   
   
       7 . The gate position sensor of  claim 6 , wherein the generator is adapted to send a coded signal.  
   
   
       8 . A gate position sensor for a flow controller having an orifice and a gate for closing the orifice, comprising: 
 a physical wave generator for generating a physical signal in the flow controller; and    at least one physical wave receiver for detecting the physical signal propagating from the generator based on a relative position of the gate to the orifice.    
   
   
       9 . The gate position sensor of  claim 8 , wherein the receiver detects when the gate is in a closed position by sensing an increased amplitude in the physical signal received by the receiver.  
   
   
       10 . The gate position sensor of  claim 8 , wherein the physical wave receiver detects a complex wave formed from a superposition of a first physical signal propagated through a structure when the gate is in an opened positioned and a second physical signal directly propagated from the physical wave generator to the physical wave receiver when the gate is in a closed position.  
   
   
       11 . The gate position sensor of  claim 8 , wherein the physical wave generator and the physical wave receiver include piezoelectric crystals.  
   
   
       12 . The gate position sensor of  claim 8 , wherein the physical wave generator is the gate such that closing the gate generates a physical wave detectable by the physical wave receiver.  
   
   
       13 . The gate position sensor of  claim 8 , wherein the at least one receiver includes a first receiver and a second receiver intermediately positioned with respect to the first receiver and the generator.  
   
   
       14 . A system, comprising: 
 an ultrasonic mass flow controller including a gate adapted to move between an open and closed position;    a sensor, including:    a physical wave generator for generating a physical signal in the flow controller; and at least one physical wave receiver for detecting the physical signal propagating from the generator based on a relative position of the gate to the orifice.    
   
   
       15 . The system of  claim 14 , wherein the at least one receiver includes a first receiver and a second receiver intermediately positioned with respect to the first receiver and the generator.  
   
   
       16 . The system of  claim 14 , wherein the generator generates a coded signal.  
   
   
       17 . 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 physical wave generator and a physical wave receiver, and wherein the physical wave generator generates a physical signal, at least one physical wave receiver receives the physical signal, and the physical wave receiver detects the physical signal propagating from the generator through a junction formed by the orifice and the gate when the gate is closed.    
   
   
       18 . The system of  claim 17 , further comprising: 
 a semiconductor gas source; and    a semiconductor processing chamber, wherein the flow controller is adapted to control gas flow through the inflow line from the gas source to the processing chamber.    
   
   
       19 . The system of  claim 18 , wherein the flow controller includes an ultrasonic mass flow controller.  
   
   
       20 . The system of  claim 17 , wherein the receiver detects when the gate is in a closed position by sensing an increased amplitude in the physical signal received by the receiver.  
   
   
       21 . The system of  claim 17 , wherein the physical wave receiver detects a complex wave formed from a superposition of a first physical signal propagated through a structure when the gate is in an opened positioned and a second physical signal directly propagated from the physical wave generator to the physical wave receiver when the gate is in a closed position.  
   
   
       22 . The system of  claim 17 , wherein the physical wave generator and the physical wave receiver include piezoelectric crystals.  
   
   
       23 . The system of  claim 17 , wherein the physical wave generator is the gate such that closing the gate generates a physical wave detectable by the physical wave receiver.  
   
   
       24 . The system of  claim 17 , further comprising at least one intermediate receiver located between the generator and the receiver.  
   
   
       25 . The system of  claim 17 , wherein the generator is adapted to send a coded signal.