Methods and assemblies for gas flow ratio control
Methods and gas flow control assemblies configured to deliver gas to process chamber zones in desired flow ratios. In some embodiments, assemblies include one or more MFCs and a back pressure controller (BPC). Assemblies includes a controller, a process gas supply, a distribution manifold, a pressure sensor coupled to the distribution manifold and configured to sense back pressure of the distribution manifold, a process chamber, a one or more mass flow controllers connected between the distribution manifold and process chamber to control gas flow there between, and a back pressure controller provided in fluid parallel relationship to the one or more mass flow controllers, wherein precise flow ratio control is achieved. Alternate embodiment include an upstream pressure controller configured to control flow of carrier gas to control back pressure. Further methods and assemblies for controlling zonal gas flow ratios are described, as are other aspects.
1. A gas flow control assembly, comprising:
a process controller;
a process gas supply;
a distribution manifold fluidly coupled to the process gas supply;
a back pressure sensor operatively connected to the distribution manifold and configured to sense gas pressure in the distribution manifold;
a process chamber including a plurality of zones;
a plurality of mass flow controllers, each mass flow controller fluidly and operatively connected to the distribution manifold and the process chamber and configured to control gas flow into a first zone subset of one or more of the plurality of zones of the process chamber; and
a back pressure controller fluidly and operatively connected to the distribution manifold and configured to control an upstream pressure in the distribution manifold and control gas flow into a second zone subset of one or more of the plurality of zones of the process chamber, the second zone subset not including any one of the plurality of zones included in the first zone subset.
2. The gas flow control assembly of claim 1 wherein the process controller is operatively connected to the one or more mass flow controllers to set a flow set point through each of the one or more mass flow controllers.
3. The gas flow control assembly of claim 1 wherein each of the one or more mass flow controllers is configured to flow a gas from the process gas supply at a flow rate of greater than 90 slm.
4. The gas flow control assembly of claim 1 , comprising a process gas supply fluidly coupled to the distribution manifold, the process gas supply comprising a carrier gas and one or more process gases.
5. A gas flow control assembly, comprising:
a process controller;
a process gas supply including a plurality of zones;
a distribution manifold fluidly coupled to the process gas supply, the distribution manifold having at least two outlets;
a back pressure sensor operatively connected to the process controller and configured to sense gas pressure in the distribution manifold;
a process chamber;
a plurality of mass flow controllers, each of the plurality of mass flow controllers fluidly and operatively connected to an outlet of the distribution manifold and to one or more of the plurality of zones of the process chamber to control gas flow percentage into a first zone subset of the one or more of the plurality of zones; and
a back pressure controller fluidly connected to the distribution manifold and operatively connected to the process controller to control the back pressure controller to a back pressure set point responsive to output from the back pressure sensor and to control gas flow into a second zone subset of the one or more of the plurality of zones of the process chamber, the second zone subset not including any one of the plurality zones included in the first zone subset.