Method and apparatus for pulse gas delivery using an external pressure trigger
A fluid control system and associated method for pulse delivery of a fluid includes a shutoff valve and a mass flow controller (MFC) upstream of the shutoff valve. The MFC includes a flow channel, a control valve to control flow of fluid in the flow channel, a flow sensor to measure flow rate in the flow channel, and a controller having a valve input from the shutoff valve indicating opening of the shutoff valve. The controller is configured to respond to the valve input to control flow of fluid through the control valve to initiate and terminate a pulse of fluid from the flow channel to the shutoff valve to control a mass of fluid delivered during the pulse of fluid. The valve input can be a pressure signal, and the MFC can include a pressure sensor to sense the pressure signal.
1. A fluid control system for pulse delivery of a fluid, the system comprising:
a shutoff valve; and
a mass flow controller (MFC) upstream of the shutoff valve, including:
a flow channel,
a control valve to control flow of fluid in the flow channel,
a flow sensor to measure flow rate in the flow channel, and
a controller having a valve input from the shutoff valve indicating opening of the shutoff valve, the controller configured to respond to the valve input to control flow of fluid through the control valve to initiate and terminate a pulse of fluid from the flow channel to the shutoff valve to control a mass of fluid delivered during the pulse of fluid.
2. The system of claim 1 , wherein the controller controls the flow of fluid through the control valve based on feedback from the flow sensor during the pulse of fluid.
3. The system of claim 1 , wherein the valve input is a pressure signal, and wherein the MFC includes a pressure sensor to sense the pressure signal.
4. The system of claim 3 , wherein the pressure sensor receives the pressure signal via a tap into a pneumatic line, pressure in the pneumatic line opening and closing the shutoff valve.
5. The system of claim 3 , wherein the pressure sensor receives the pressure signal via a pneumatic line controlled by a host controller.
6. The system of claim 3 , wherein the controller is configured to convert a rising edge of the pressure signal into a trigger signal for starting pulse gas delivery.
7. The system of claim 1 , wherein the shutoff valve is controlled by a host controller.
8. The system of claim 1 , wherein the controller is configured to calculate a mole set point n SP from flow set point Q SP and a pulse-on period Δt, the mole set point n SP being a targeted amount of the mass of fluid to be delivered during the pulse of fluid.
9. The system of claim 8 , wherein the pulse-on period Δt is a default value stored in the WC and the flow set point Q SP is received from a host controller.
10. The system of claim 9 , wherein the WC is programmable to change the pulse-on period Δt from the stored default value.
11. The system of claim 8 , wherein the controller is configured to close the control valve based on a computation of the mass of fluid delivered and/or the duration of the pulse-on period Δt during the pulse of fluid.
12. The system of claim 1 , wherein the shutoff valve is a 3-way valve coupled to a process chamber and a divert line.
13. A method of delivering a pulse of fluid, the method comprising:
controlling flow of fluid into a flow channel with a control valve;
measuring flow rate in the flow channel with a flow sensor;
receiving a valve input from a shutoff valve downstream of the control valve indicating opening of the shutoff valve; and
responding to the valve input to control flow of fluid through the control valve to initiate and terminate a pulse of fluid from the flow channel to the shutoff valve to control a mass of fluid delivered during the pulse of fluid.
14. The method of claim 13 , wherein controlling the flow of fluid through the control valve is based on feedback from the flow sensor during the pulse of fluid.
15. The method of claim 13 , wherein receiving the valve input includes sensing a pressure signal received via a tap into a pneumatic line, pressure in the pneumatic line opening and closing the shutoff valve.
16. The method of claim 13 , further comprising:
receiving a flow set point Q SP ; and
calculating a mole set point n SP from a flow set point Q SP and a pulse-on period Δt, the mole set point n SP being a targeted amount of the mass of fluid to be delivered during the pulse of fluid.
17. The method of claim 13 , further comprising controlling opening and closing of the shutoff valve.
18. A mass flow controller (MFC) for pulse delivery of a fluid, the MFC comprising:
a flow channel;
a control valve to control flow of fluid in the flow channel;
a flow sensor to measure flow rate in the flow channel; and
a controller having a valve input from a shutoff valve downstream of the control valve indicating opening of the shutoff valve, the controller configured to respond to the valve input to control flow of fluid through the control valve to initiate and terminate a pulse of fluid from the flow channel to the shutoff valve to control a mass of fluid delivered during the pulse of fluid.
19. The MFC of claim 18 , wherein the controller controls the flow of fluid through the control valve based on feedback from the flow sensor during the pulse of fluid.
20. The MFC of claim 18 , wherein the valve input is a pressure signal, and wherein the MFC includes a pressure sensor to sense the pressure signal.
21. The MFC of claim 20 , wherein the pressure sensor receives the pressure signal via a tap into a pneumatic line, pressure in the pneumatic line opening and closing the shutoff valve.
22. The MFC of claim 20 , wherein the pressure sensor receives the pressure signal via a pneumatic line controlled by a host controller.
23. The MFC of claim 20 , wherein the controller is configured to convert a rising edge of the pressure signal into a trigger signal for starting pulse gas delivery.
24. The MFC of claim 18 , wherein the controller is configured to calculate a mole set point n SP from a flow set point Q SP and a pulse-on period Δt, the mole set point n SP being a targeted amount of the mass of fluid to be delivered during the pulse of fluid.
25. The MFC of claim 24 , wherein the pulse-on period Δt is a default value stored in the WC and the flow set point Q SP is received from a host controller.
26. The MFC of claim 25 , wherein the WC is programmable to change the pulse-on period Δt from the stored default value.
27. The MFC of claim 24 , wherein the controller is configured to close the control valve based on a computation of the mass of fluid delivered and/or the duration of the pulse-on period Δt during the pulse of fluid.