METHODS, SYSTEMS, AND APPARATUS FOR MASS FLOW VERIFICATION BASED ON CHOKED FLOW

• US 20170370763A1
• Filed: 06/27/2016
• Published: 12/28/2017
• Est. Priority Date: 06/27/2016
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Brashear, Kevin M., Ye, Zhiyuan, Hough, Justin, Rajaram, Jaidev, Josephson, Marcel E., Okada, Ashley M.
• Granted Patent: US 10,684,159 B2
• Time in Patent Office: Days
• CPC Class Codes: G01F 1/40 Details of construction of the flow constriction devices
• CPC Class Codes: G01F 1/86 Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure
• CPC Class Codes: G01F 25/15 specially adapted for gas meters G01F25/11 - G01F25/14, G01F25/17 take precedence

Abstract

Mass flow verification systems and apparatus may verify mass flow rates of mass flow controllers (MFCs) based on choked flow principles. These systems and apparatus may include a plurality of differently-sized flow restrictors coupled in parallel. A wide range of flow rates may be verified via selection of a flow path through one of the flow restrictors based on an MFC'"'"'s set point. Mass flow rates may be determined via pressure and temperature measurements upstream of the flow restrictors under choked flow conditions. Methods of verifying a mass flow rate based on choked flow principles are also provided, as are other aspects.

Claims

1. A mass flow verification system, comprising:

an inlet;

a first pressure sensor and a temperature sensor each coupled downstream of the inlet;

a plurality of isolation valves coupled downstream of the inlet;

a plurality of differently-sized flow restrictors coupled in parallel and downstream of the inlet, each one of the plurality of differently-sized flow restrictors coupled in series with the inlet and a respective one of the plurality of isolation valves;

an outlet coupled downstream of and in series with each one of the plurality of differently-sized flow restrictors;

and

a controller coupled to the first pressure sensor, the temperature sensor, and the plurality of isolation valves, wherein the controller is configured to determine a mass flow rate in response to a temperature measured by the temperature sensor under a choked flow condition and a first pressure measured by the first pressure sensor under the choked flow condition.

2. The mass flow verification system of claim 1, wherein the controller is configured to:

cause a gas to flow through only one of the plurality of differently-sized flow restrictors by closing some of the plurality of isolation valves;

measure pressure via the first pressure sensor to obtain a measured pressure value in response to flowing the gas through the one of the plurality of differently-sized flow restrictors;

measure temperature via the temperature sensor to obtain a measured temperature value in response to flowing the gas through the one of the plurality of differently-sized flow restrictors; and

determine a mass flow rate by applying a predetermined flow restrictor coefficient, a predetermined gas correction factor, and a predetermined temperature value to the measured pressure value and the measured temperature value.

3. The mass flow verification system of claim 2, wherein the controller is configured to determine the mass flow rate by multiplying the measured pressure value by:

the predetermined flow restrictor coefficient;

the predetermined gas correction factor; and

a ratio of the predetermined temperature value to the measured temperature value.

4. The mass flow verification system of claim 1, wherein each one of the plurality of differently-sized flow restrictors is coupled upstream of the respective one of the plurality of isolation valves.

5. The mass flow verification system of claim 1, wherein each one of the plurality of differently-sized flow restrictors is coupled downstream of the respective one of the plurality of isolation valves.

6. The mass flow verification system of claim 5, wherein the first pressure sensor and the temperature sensor are each coupled between each one of the plurality of differently-sized flow restrictors and the respective one of the plurality of isolation valves.

7. The mass flow verification system of claim 6, wherein:

the plurality of isolation valves comprises a sub-plurality of isolation valves; and

each one of the sub-plurality of isolation valves has a first port coupled to the first pressure sensor and to the temperature sensor and has a second port coupled between a respective one of the plurality of differently-sized flow restrictors and the respective one of the plurality of isolation valves.

8. The mass flow verification system of claim 1, further comprising a gas temperature acclamation accelerator coupled upstream of the temperature sensor.

9. The mass flow verification system of claim 1, further comprising a second pressure sensor coupled downstream of at least one of the plurality of differently-sized flow restrictors, the controller coupled to the second pressure sensor.

10. The mass flow verification system of claim 1, further comprising:

a tank coupled downstream of and in series with each one of the plurality of differently-sized flow restrictors; and

a vacuum pump coupled downstream of the tank and in series between the tank and an input port, the vacuum pump having an exhaust port.

11. The mass flow verification system of claim 1, further comprising a vacuum pump coupled to the outlet, the vacuum pump having an exhaust port.

12. The mass flow verification system of claim 1, wherein the first pressure sensor comprises one or more manometers and the temperature sensor comprises one or more thermocouples.

13. An electronic device manufacturing system, comprising:

a mass flow controller;

a mass flow verification system having an inlet and an outlet, the inlet coupled to the mass flow controller, the mass flow verification system comprising;

a plurality of isolation valves coupled downstream of the inlet; and

a plurality of differently-sized flow restrictors coupled in parallel and downstream of the inlet, each one of the plurality of differently-sized flow restrictors coupled in series with the inlet, a respective one of the plurality of isolation valves, and the outlet;

a controller coupled to the plurality of isolation valves and configured to receive a pressure measurement and a temperature measurement upstream of the plurality of differently-sized flow restrictors under a choked flow condition through only one of the plurality of isolation valves, the controller also configured to determine a mass flow rate in response to receiving the pressure measurement and the temperature measurement; and

a process chamber coupled to a flow path coupled to the mass flow controller and configured to receive one or more process chemistries via the mass flow controller.

14. The electronic device manufacturing system of claim 13, wherein the controller is configured to determine a mass flow rate by applying a predetermined flow restrictor coefficient, a predetermined gas correction factor, and a predetermined temperature value to the pressure measurement and the temperature measurement.

15. The electronic device manufacturing system of claim 13, wherein the mass flow verification system further comprises:

a tank coupled downstream of and in series with each one of the plurality of differently-sized flow restrictors; and

a vacuum pump coupled downstream of the tank and in series between the tank and an input port, the vacuum pump having an exhaust port.

16. The electronic device manufacturing system of claim 13, wherein the process chamber is configured to have a reduced-pressure chemical vapor deposition process, or a reduced-pressure epitaxy process, or at least one deposition, oxidation, nitration, etching, polishing, cleaning, and lithography process performed therein.

17. A method of verifying a mass flow rate, the method comprising:

causing a gas to flow through only one of a plurality of differently-sized flow restrictors during a choked flow condition;

measuring a pressure upstream of the one of the plurality of differently-sized flow restrictors to obtain a measured pressure value during the choked flow condition;

measuring a temperature upstream of the one of the plurality of differently-sized flow restrictors to obtain a measured temperature value during the choked flow condition; and

determining a mass flow rate by applying a predetermined flow restrictor coefficient, a predetermined gas correction factor, and a predetermined temperature value to the measured pressure value and the measured temperature value.

18. The method of claim 17, further comprising characterizing each one of a plurality of differently-sized flow restrictors to determine a respective flow restrictor coefficient.

19. The method of claim 17, further comprising reducing pressure via a vacuum pump and a tank coupled downstream of the plurality of differently-sized flow restrictors to create a choked flow condition.

20. A non-transitory computer-readable storage medium on which computer readable instructions are stored, wherein the computer readable instructions, when executed by a processor, cause the processor to perform the method of claim 17.