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EP-4479813-B1 - APPARATUS FOR PRESSURE BASED MASS FLOW CONTROL AND ASSEMBLY METHOD OF SAID APPARATUS

EP4479813B1EP 4479813 B1EP4479813 B1EP 4479813B1EP-4479813-B1

Inventors

  • DING, JUNHUA

Dates

Publication Date
20260506
Application Date
20230123

Claims (15)

  1. A mass flow controller (200), comprising: a body (210) having a valve outlet bore (246) defining a flow path; an adjustable valve (220) configured to control flow of a gas through the flow path, characterized in that the mass flow controller (200) further comprises: i) a pressure drop element (350) disposed in an outlet orifice (328) of the adjustable valve, or ii) a valve element (226) comprising an outlet orifice (228) of the adjustable valve, the valve element disposed within the valve outlet bore, and a pressure drop element (250) disposed coaxially with the valve element within the valve outlet bore; an upstream pressure sensor (260) configured to detect a pressure at a location in the flow path between the adjustable valve and the pressure drop element (250; 350); a downstream pressure sensor (262) configured to detect a pressure downstream of the pressure drop element; and a controller (270) configured to determine a flow rate through the flow path based on pressure as detected by the upstream pressure sensor or by the upstream pressure sensor and the downstream pressure sensor.
  2. The mass flow controller of claim 1, wherein the pressure drop element is adjacent to the outlet orifice within the valve outlet bore.
  3. The mass flow controller of claim 1, wherein a volume between the pressure drop element and the outlet orifice within the valve outlet bore is less than about 0.05 cm 3 .
  4. The mass flow controller of claim 1, wherein the body further defines a pressure measurement conduit extending from the location in the flow path between the adjustable valve and the pressure drop element to a surface of the body, the conduit enabling communication with the upstream pressure sensor.
  5. The mass flow controller of claim 4, wherein the pressure measurement conduit extends laterally from the valve outlet bore to a surface of the body at which the upstream pressure sensor is mounted.
  6. The mass flow controller of claim 1, wherein the pressure drop element is one of a flow nozzle, a laminar flow element, or a porous media flow restrictor.
  7. The mass flow controller of claim 1, wherein the body further includes a controller inlet bore and a controller outlet bore, the valve outlet bore disposed generally transverse to at least one of the controller inlet and outlet bores.
  8. The mass flow controller of claim 1, wherein a valve actuator of the adjustable valve drives a valve member in a direction coaxial with the valve outlet bore.
  9. The mass flow controller of claim 1, wherein the adjustable valve comprises the pressure drop element disposed in the outlet orifice of the valve, and the upstream pressure sensor is configured to detect the pressure at a location in the flow path between an armature of the adjustable valve and the pressure drop element.
  10. The mass flow controller of claim 9, wherein the outlet orifice of the valve comprises a body defining a pressure measurement conduit disposed upstream of the pressure drop element.
  11. The mass flow controller of claim 10, wherein the body defining the flow path further defines a pressure measurement conduit in fluid communication with the pressure measurement conduit of the outlet orifice.
  12. A method of assembling a mass flow controller (200), characterized in that : disposing a pressure drop element (250) and a valve element (226) comprising an outlet orifice (228) of an adjustable valve (220) substantially coaxially within a body (210) having a valve outlet bore defining a flow path, the adjustable valve configured to control flow of a gas through the flow path; and disposing an upstream pressure sensor (260) at a pressure measurement conduit (238) extending from the flow path to a surface of the body.
  13. The method of claim 12, wherein the pressure drop element is disposed adjacent to the outlet orifice within the valve outlet bore.
  14. The method of claim 12, wherein the pressure drop element is disposed at a minimum distance from the outlet orifice within the valve outlet bore.
  15. The method of claim 12, wherein the pressure drop element and the outlet orifice of the adjustable valve are integral, and wherein a valve actuator of the adjustable valve is configured to drive the valve element in a direction coaxial with the valve outlet bore.

Description

RELATED APPLICATION This application is a continuation of U.S. Application No. 17/651,751, filed on February 18, 2022. BACKGROUND A semiconductor fabrication process can involve the delivery of several different gases and gas mixtures in various quantities over several processing steps. Generally, gases are stored in tanks at a processing facility, and gas metering systems are used to deliver metered quantities of gases from the tanks to processing tools, such as chemical vapor deposition reactors, vacuum sputtering machines, plasma etchers, etc. Other components, such as valves, pressure regulators, mass flow controllers (MFCs), mass flow ratio controllers (FRCs), mass flow meters (MFMs), mass flow verifiers (MFVs), and the like can be included in the gas metering system or in a flow path from the gas metering system to a processing tool. Components such as MFCs, FRCs, MFMs, and MFVs are provided to ensure the precise delivery of process gases. Various examples of pressure-based mass-flow controllers can be found in US 10.514.712, WO 2004/020956, US 2020/033895, and in the article "Pressure-Based Mass-Flow Control Using Thermopneumatically-Actuated Microvalves", by John Fitch et al, Processing sensors and actuators workshop, 30 January 1998. A traditional pressure-based mass flow controller (PBMFC) includes a flow control valve and a pressure drop element, such as a flow nozzle, a laminar flow element, or a porous media flow restrictor. The MFC can measure flow rate with use of one pressure sensor when the flow nozzle is used and flow is under a critical flow condition, or with use of two pressure sensors under a non-critical flow condition. If a laminar flow element or a porous media flow restrictor is used as a pressure drop element, two pressure sensors are used to measure the flow rate. SUMMARY Improvements to pressure-based mass flow controllers are provided. The improved mass flow controllers can provide for reduced dead volume within the device, allowing for reduced bleeding time upon valve closure. The mass flow controllers can also be manufactures with reduced complexity and cost. A mass flow controller includes a body having a valve outlet bore defining a flow path and an adjustable valve configured to control flow of a gas through the flow path. A valve element includes an outlet orifice of the adjustable valve and is disposed within the bore. The mass flow controller further includes a pressure drop element disposed coaxially with the valve element within the bore. An upstream pressure sensor is configured to detect a pressure at a location in the flow path between the adjustable valve and the pressure drop element, and a controller is configured to determine a flow rate through the flow path based on pressure as detected by the upstream pressure sensor. The pressure drop element can be adjacent to the outlet orifice within the bore, disposed at a minimum distance within the bore with respect to the outlet orifice, or a combination thereof. For example, a volume between the pressure drop element and the outlet orifice within the bore can be less than about 0.05 cm3. The bore can be substantially perpendicular to a surface of the body at which the adjustable valve is mounted. The pressure drop element can be or include a flow nozzle, a laminar flow element, a porous media flow restrictor, or a combination thereof. The body can further define a pressure measurement conduit extending from the location in the flow path between the adjustable valve and the pressure drop element to a surface of the body. For example, the pressure measurement conduit can extend laterally from the bore to a surface of the body at which the upstream pressure sensor is mounted. The mass flow controller can further include a downstream pressure sensor configured to detect a pressure downstream of the pressure drop element, and the controller can be further configured to determine the flow rate based on pressure as detected by the downstream pressure sensor. The body can further include a controller inlet bore and a controller outlet bore, with the valve outlet bore being disposed generally transverse to at least one of the controller inlet and outlet bores. A valve actuator of the adjustable valve can drive a valve member (e.g., a valve plug or armature) in a direction coaxial with the valve outlet bore. A mass flow controller includes a body defining a flow path and an adjustable valve configured to control flow of a gas through the flow path. The adjustable valve includes a pressure drop element disposed in an outlet orifice of the valve. The mass flow controller further includes an upstream pressure sensor configured to detect a pressure at a location in the flow path between an armature of the adjustable valve and the pressure drop element. A controller of the device is configured to determine a flow rate through the flow path based on pressure as detected by the upstream pressure sensor. The outlet orifice of the val