Fluid control system

Abstract

An improved fluid delivery system and method that directly controls the concentration of constituent components in a fluid mixture delivered, for example, to a process chamber. Pressure of the fluid mixture can also be directly controlled. A concentration sensor capable of measuring concentration of all of the constituent components in a fluid mixture is used to provide signals used to vary the flow rate of constituent gases under a closed loop feedback system. The signal output of one or more pressure sensors can also be used to provide a signal used to vary the flow rate of constituent gases under a closed loop feedback system. By directly controlling these two extremely important process variables, embodiments of the present invention provide a significant advantage in measurement accuracy over the prior art, enable real-time process control, reduce system level response time, and allow for a system with a significant footprint reduction.

What is claimed is: 
     
         1 . A method of delivering gases, the method comprising:
 providing a plurality of gases, each gas provided by a gas source;   causing the plurality of gases to flow along a flow path so that the plurality of gases are combined into a gas mixture, the flow path extending from the gas sources to a process chamber;   providing a concentration sensor fluidly coupled to the flow path;   sampling the gas mixture using the concentration sensor by directing a portion of the gas mixture to the concentration sensor; and   venting the portion of the gas mixture to a vacuum source, bypassing the process chamber.   
     
     
         2 . The method of  claim 1  wherein the concentration sensor samples a concentration of a first gas within the gas mixture. 
     
     
         3 . The method of  claim 1  further comprising a step of adjusting subsequent to the step of sampling, the step of adjusting comprising adjusting a control valve within the flow path to control the flow of a first gas of the plurality of gases within the gas mixture. 
     
     
         4 . The method of  claim 3  wherein the step of adjusting further comprises adjusting a plurality of control valves within the flow path to control the flow of more than one gas of the plurality of gases. 
     
     
         5 . The method of  claim 1  wherein the step of sampling comprises determining concentrations of two or more of the plurality of gases within the gas mixture using the concentration sensor. 
     
     
         6 . The method of  claim 1  wherein the step of causing comprises using calculated setpoints to deliver the gas mixture to the process chamber at a first flow rate, the first flow rate being higher than a second flow rate used during system operation. 
     
     
         7 . The method of  claim 1  wherein the step of causing comprises using calculated setpoints to deliver the gas mixture to the process chamber at a first flow rate that is more than 50% of a maximum flow rate for the control valve. 
     
     
         8 . The method of  claim 1  wherein the step of sampling comprises venting the portion of the gas mixture to a side stream fluidly coupled to the flow path, the concentration sensor and a first valve fluidly coupled to the side stream, the first valve disposed between the concentration sensor and the flow path. 
     
     
         9 . The method of  claim 8  wherein the side stream further comprises a bypass line. 
     
     
         10 . The method of  claim 9  wherein a second valve is fluidly coupled to the bypass line. 
     
     
         11 . The method of  claim 9  wherein the bypass line is fluidly coupled to a vacuum source. 
     
     
         12 . A method of delivering gases, the method comprising:
 providing a plurality of gases, each gas provided by a gas source fluidly coupled to a control valve, each gas having a gas flow rate controlled by the control valve;   causing the plurality of gases to flow along a flow path at a first mixture flow rate so that the plurality of gases are combined into a gas mixture, the flow path extending from the gas sources to a process chamber;   providing a concentration sensor fluidly coupled to the flow path;   sampling the gas mixture using the concentration sensor by directing a portion of the gas mixture to the concentration sensor;   adjusting one of the control valves to alter a concentration of the gas mixture; and   delivering the plurality of gases to the process chamber at a second mixture flow rate.   
     
     
         13 . The method of  claim 12  wherein the step of adjusting further comprises adjusting a plurality of the control valves within the flow path to control the flow rate of more than one gas of the plurality of gases. 
     
     
         14 . The method of  claim 1  wherein the second mixture flow rate is less than the first mixture flow rate. 
     
     
         15 . The method of  claim 12  wherein the step of causing comprises using calculated setpoints to deliver the gas mixture to the process chamber at the first mixture flow rate, the first mixture flow rate being higher than the second mixture flow rate. 
     
     
         16 . The method of  claim 12  further comprising the step of venting the portion of the gas mixture to a vacuum source, the portion of the gas mixture bypassing the process chamber. 
     
     
         17 . The method of  claim 12  further comprising a side stream fluidly coupled to the flow path, the concentration sensor fluidly coupled to the side stream. 
     
     
         18 . The method of  claim 17  wherein the side stream further comprises a bypass line. 
     
     
         19 . The method of  claim 18  wherein the bypass line is fluidly coupled to a vacuum source. 
     
     
         20 . A method of delivering gases, the method comprising:
 providing a plurality of gases, each gas provided by a gas source fluidly coupled to a control valve, each gas having a gas flow rate controlled by the control valve;   causing the plurality of gases to flow along a flow path so that the plurality of gases are combined into a gas mixture and delivered to a process chamber, the flow path extending from the gas sources to the process chamber;   providing a concentration sensor fluidly coupled to the flow path;   determining a concentration of a first gas within the gas mixture using the concentration sensor;   adjusting the control valve of a second gas of the plurality of gases in accordance with the determined concentration of the first gas within the gas mixture;   measuring a first mixture flow rate in the flow path; and   adjusting each of the control valves of the plurality of gases to alter the mixture flow rate without altering a composition of the mixture.