Method and apparatus for an integrated pressure and flow controller

Abstract

A pressure control method and device are provided. The pressure controller includes a control valve configured to control the pressure of a fluid in a flow path, a flow limiter positioned in the flow path, and distal and proximal pressure sensors. The distal pressure sensor detects the fluid pressure in the flow limiter at a position distal to the control valve, and the proximal pressure sensor detects the fluid pressure in the flow limiter at a position proximal to the control valve. The pressure controller further includes a controller configured to 1) control the drive of the control valve based on the pressure detected by the distal pressure sensor and a pressure setpoint, and 2) determine the mass flow rate based on the pressures detected by the distal and proximal pressure sensors.

Description

[Technical Field]

[0001] Related applications This application is a continuation of U.S. Patent Application No. 18 / 170,964, filed on 17 February 2023, claiming priority of said application. The entire teachings of the said application are incorporated herein by reference. [Background technology]

[0002] background Pressure controllers with integrated mass flow meters are used in critical process applications such as back wafer cooling to provide fluid pressure measurement and control while monitoring the mass flow rate of the fluid. There is a need for improved methods and devices to provide pressure control and monitor some process fluids. [Overview of the project]

[0003] overview A pressure controller with an integrated mass flow meter is provided, which is advantageously used for pressure control and monitoring of reactive fluids, including reactive gases such as O3 / O2 mixtures.

[0004] The pressure controller includes a control valve configured to control the pressure of the fluid in the flow path, a flow limiter positioned in the flow path, and distal and proximal pressure sensors. The distal pressure sensor detects the fluid pressure in the flow path at a position distal to the control valve, and the proximal pressure sensor detects the fluid pressure in the flow path at a position proximal to the control valve. The flow limiter is positioned between the distal and proximal positions in the flow path. The pressure controller further includes a controller configured to control the operation of the control valve based on the pressure detected by the distal pressure sensor and a pressure setpoint, and to determine the mass flow rate based on the pressures detected by the distal and proximal pressure sensors.

[0005] The pressure controller includes a control valve configured to control the pressure of the fluid in the flow path, a flow limiter positioned in the flow path, and distal and proximal pressure sensors. The distal pressure sensor detects the fluid pressure in the flow limiter at a position distal to the control valve, and the proximal pressure sensor detects the fluid pressure in the flow limiter at a position proximal to the control valve. The pressure controller further includes a controller configured to control the operation of the control valve based on the pressure detected by the distal pressure sensor and a pressure setpoint. The controller is configured to determine the mass flow rate based on the pressures detected by the distal and proximal pressure sensors.

[0006] A method for controlling fluid pressure includes controlling the drive of a control valve based on the pressure detected by a distal pressure sensor and a pressure setpoint. The distal pressure sensor detects the fluid pressure in the flow path at a position distal to the control valve. The method further includes determining the mass flow rate based on the pressure detected by the distal pressure sensor and a proximal pressure sensor that detects the fluid pressure in the flow path at a position proximal to the control valve. A flow limiter is positioned between the distal and proximal positions in the flow path.

[0007] A method for controlling fluid pressure includes controlling the drive of a control valve based on the pressure detected by a distal pressure sensor and a pressure setpoint. The control valve controls the pressure of the fluid in the flow path, and a flow limiter is located in the flow path. The distal pressure sensor detects the fluid pressure in the flow limiter at a position distal to the control valve. The method further includes determining the mass flow rate based on the pressure detected by the distal pressure sensor and a proximal pressure sensor that detects the fluid pressure in the flow limiter at a position proximal to the control valve.

[0008] To provide upstream pressure control, the proximal and distal positions may be upstream of the control valve. Alternatively, to provide downstream pressure control, the proximal and distal positions may be downstream of the control valve.

[0009] Pressure control of a control valve may include providing closed-loop feedback control of the control valve based on the pressure detected by a distal pressure sensor and a pressure setpoint.

[0010] The mass flow rate Q is, Q=f(R,P u ,P d ,T,mw,μ,γ) (1) This can be determined by the function given by , where R is a characteristic of the flow limiter and P u P is the upstream pressure of the flow limiter detected by either the distal or proximal pressure sensor, and d is the downstream pressure of the flow limiter detected by the other of the distal and proximal pressure sensors, T is the fluid temperature, mw is the fluid molecular weight, μ is the fluid viscosity, and γ is the specific heat ratio of the fluid. The determined mass flow rate can be output.

[0011] The temperature of the fluid in a flow path can be detected. For example, a pressure controller may include a temperature sensor configured to detect the temperature of the fluid in the flow path. The temperature sensor may detect the fluid temperature at or near a flow limiter in the flow path.

[0012] The fluid may be a reactive gas, such as an O3 / O2 gas mixture or an HBr / Cl2 gas mixture.

[0013] The pressure controller includes a control valve configured to control the pressure of the fluid in the flow path, a flow limiter positioned in the flow path, an upstream pressure sensor, and a downstream pressure sensor. The upstream pressure sensor detects the fluid pressure in the flow limiter upstream of the flow limiter, and the downstream pressure sensor detects the fluid pressure in the flow limiter downstream of the flow limiter. The pressure controller further includes a controller configured to control the operation of the control valve based on the pressure detected by either the upstream or downstream pressure sensor and a pressure setpoint. This controller is further configured to determine the mass flow rate based on the pressure detected by the upstream and downstream pressure sensors.

[0014] A method for controlling the pressure of a fluid includes controlling the driving of a control valve based on the pressure detected by one of an upstream pressure sensor and a downstream pressure sensor and a pressure set value. The upstream pressure sensor detects the fluid pressure in the flow restrictor upstream of the flow restrictor, and the downstream pressure sensor detects the fluid pressure in the flow restrictor downstream of the flow restrictor. The control valve controls the pressure of the fluid in the flow path, and the flow restrictor is disposed in the flow path. The method further includes determining a mass flow rate based on the pressures detected by the upstream and downstream pressure sensors.

[0015] While one of the upstream and downstream pressure sensors is used as a pressure sensor for pressure control, the flow restrictor, the upstream pressure sensor, and the downstream pressure sensor may be disposed upstream of the control valve. Alternatively, while one of the upstream and downstream pressure sensors is used as a pressure sensor for pressure control, the flow restrictor, the upstream pressure sensor, and the downstream pressure sensor may be disposed downstream of the control valve.

Brief Description of the Drawings

[0016] Brief explanation of the drawing As shown in the accompanying drawings, the above will become apparent from a more detailed description of the following example embodiments. The reference numerals of those accompanying drawings may indicate the same elements through different figures. The drawings are not necessarily to scale and emphasis is made in illustrating the present embodiment.

[0017] [Figure 1] FIG. 1 is a schematic diagram of the prior art of a pressure controller having an integrated mass flow meter.

[0018] [Figure 2] FIG. 2 is a schematic diagram of an embodiment of a downstream pressure controller having an integrated mass flow meter.

[0019] [Figure 3] FIG. 3 is a schematic diagram of an embodiment of an upstream pressure controller having an integrated mass flow meter.

[0020] [Figure 4] Figure 4 shows a method for providing pressure control and monitoring of the mass flow of a reactive gas. [Modes for carrying out the invention]

[0021] Detailed explanation Pressure controllers with integrated mass flowmeters can provide fluid pressure control while monitoring the mass flow rate of the fluid for critical process applications (e.g., back wafer cooling processes). Such pressure controllers can provide both pressure control and mass flow rate monitoring in a compact package. Examples of pressure controllers include the General Purpose Downstream Pressure Controller with Mass Flowmeter (GPCMA) and the High Performance Downstream Pressure Controller with Mass Flowmeter (PPCMA) from MKS Instruments (Andover, Massachusetts).

[0022] Figure 1 shows an example of prior art for a pressure controller with an integrated mass flow meter. The pressure controller 100 includes a thermal flow sensor 102, a control valve 110, and a pressure sensor 104. The pressure of the fluid flowing through the device's flow path 130 is controlled by the control valve 110 based on the pressure detected by the pressure sensor 104. In particular, a controller 120 such as a microprocessor monitors the pressure (P u The drive of the control valve 110 can be controlled so that the pressure (P) of the fluid leaving the device is limited to the pressure setpoint. d The pressure is controlled to a set value. Simultaneously, the heat flow sensor 102 provides measurement of the mass flow rate of the fluid. The mass flow rate and, if necessary, the monitored pressure may be output by the device for reporting to the user.

[0023] Pressure controllers like the pressure controller 100 in Figure 1 are generally suitable for monitoring process gases. However, such pressure controllers may be unreliable and unsuitable when used with reactive gases. As used herein, “reactive gas” refers to a gas or gas mixture that is unstable and / or highly chemically reactive. Examples of reactive gases include ozone (O3), a mixture of ozone and oxygen (O3 / O2), and a gas mixture of hydrogen bromide and chlorine (HBr / Cl2).

[0024] A thermal flow sensor typically includes a heat source through which the measured gas passes and operates based on temperature measurements obtained from the gas. For example, a thermal flow sensor may include a sensor tube where a thermal element is located. The thermal element may be, for example, a coil resistor wrapped around the sensor tube and heated to a temperature above the ambient temperature. As the gas passes through the sensor tube, the gas, typically at ambient temperature, has a cooling effect on the coil, lowering the coil's temperature as a function of mass flow. The flowing gas cools the upstream coil more than the downstream coil, thereby allowing the mass flow rate of the gas to be determined based on the temperature difference measured between the coils, as indicated by the measured resistance difference between the coils. Further examples of thermal flow sensors are described in U.S. Patent No. 5,461,913.

[0025] The imparting of heat to reactive gases and / or heat generation due to exothermic reactions involving reactive gases interfere with the measurement of heat flow. For example, when using a process gas containing ozone (O3), the ozone is unstable and releases heat when it decomposes, which can lead to inaccurate mass flow measurements due to the heat flow sensor 102. Furthermore, the imparting of heat to gases containing ozone can accelerate ozone degradation. As a result, the signal from the heat flow sensor tends to become saturated when used with ozone and other reactive gases. In addition, the heat flow sensor tends to be more susceptible to damage when used with reactive gases.

[0026] Examples of embodiments are described below.

[0027] A pressure control device and a pressure control method suitable for use with reactive gases are provided. Such a pressure control device can further provide both pressure control and mass flow monitoring in a compact form.

[0028] Figure 2 illustrates an example of a pressure controller. The pressure controller 200 includes a control valve 210 configured to control the pressure of the fluid in a flow path 230. The flow path 230 is defined by the body 232 of the device. A flow limiter 208 is located within the flow path 230. The device further includes pressure sensors 204 and 206. Pressure sensor 204 is a proximal pressure sensor that detects the fluid pressure in the flow path at a position 214 proximal to the control valve. Pressure sensor 206 is a distal pressure sensor that detects the fluid pressure in the flow path at a position 216 distal to the control valve. The controller 220 controls the operation of the control valve 210 based on the pressure detected by the distal pressure sensor 206 and the pressure setpoint. The controller further controls the pressure (P) detected by the distal pressure sensor 206 and the proximal pressure sensor 204. u and P d The pressure controller 200 is configured to determine the mass flow rate based on the following. The pressure controller 200 may further include a temperature sensor 202. The temperature sensor 202 is configured to detect the temperature of the fluid in or near the flow limiter 208 for use in determining the mass flow rate of the fluid.

[0029] Pressure sensors 204, 206 may be configured to detect pressure in the flow limiter 208. As used herein, “in” the flow limiter means the inlet or outlet of the flow limiter and includes locations in the flow path adjacent to the flow limiter and close enough to the inlet or outlet of the flow limiter to provide a pressure measurement usable in determining the mass flow rate. For example, a pressure sensor or part thereof may be positioned in the flow path so as to be adjacent to the flow limiter in the flow path.

[0030] As shown in FIG. 2, the pressure controller 200 is a downstream pressure controller that controls the pressure (P d ) of the fluid flowing through the device based on the pressure measurement obtained downstream of the control valve 210. For this reason, the pressure of the fluid exiting the device at the outlet 236 is controlled to the pressure set value. In this configuration, the pressure sensor (pressure sensor 204) proximal to the control valve is an upstream pressure sensor that obtains the pressure indication (P u ) upstream of the flow restrictor 208, and the pressure sensor (pressure sensor 206) distal to the control valve is a downstream pressure sensor that obtains the pressure indication (P u ) downstream of the flow restrictor 208.

[0031] As shown in FIG. 3, the pressure controller can alternatively be configured as an upstream pressure controller. The pressure controller 300 includes elements similar to those illustrated with respect to the pressure controller 200, except that the pressure sensors 304, 306 are disposed upstream of the control valve 210. In this configuration, the pressure sensor (pressure sensor 306) distal to the control valve is an upstream pressure sensor that detects the fluid pressure in the flow path at the distal position 316 from the control valve, and the pressure sensor (pressure sensor 304) proximal to the control valve is a downstream pressure sensor that detects the fluid pressure in the flow path at the proximal position 314 from the control valve. The pressure of the fluid entering the device at the inlet 234 is controlled to the pressure set value by the controller 220 based on the pressure (P u ) detected by the distal pressure sensor 306. The controller 320 is further configured to determine the mass flow rate based on the pressures (P u and P d ) detected by both the pressure sensors 304, 306.

[0032] In both upstream and downstream configurations (200, 300), pressure sensors distal to the control valve (pressure sensors 206, 306) advantageously provide two applications simultaneously. In particular, the pressure detected by the distal pressure sensors is selected as a target value for pressure control and is used by the controller (220, 320) to control the drive of the control valve 210 for fluid pressure control at the downstream outlet (Figure 2) or upstream outlet (Figure 3). In addition, the pressure detected by the distal pressure sensors, together with the pressure detected by the proximal pressure sensors (pressure sensors 204, 304), is used by the controller (220, 320) to determine the mass flow rate of the fluid. In this way, distal pressure measurement enables both pressure control and mass flow rate determination.

[0033] The control of the control valve 210 may be closed-loop. In particular, the controllers (220, 320) may be configured to provide closed-loop feedback control of the control valve 210 based on the pressure detected by the distal pressure sensor and the pressure setpoint. The drive of the control valve may be directly based on the detected pressure. The detected pressure may be compared with the pressure setpoint, and as a result, the opening and closing of the valve may be adjusted so that the distal pressure is equal to or within the allowable range of the pressure setpoint. The distal pressure may also be monitored throughout the pressure control process, and as a result, the drive of the control valve may be adjusted to maintain the upstream or downstream pressure control at the pressure setpoint.

[0034] As used herein, the term “control valve” likely refers to a valve whose opening range can be controlled between an on and off state, excluding on / off type valves. The opening degree of an adjustable control valve can be controlled in response to a control signal, thereby controlling the flow rate or pressure of the fluid moving through the valve. Adjustable control valves include proportional control valves. Suitable examples for use as adjustable control valves in the devices described herein include solenoid valves, piezo valves, and stepping motor valves.

[0035] The mass flow rate (Q) of a fluid is, Q=f(R,P u,P d ,T,mw,μ,γ) (1) This can be determined by the function given by , where R is a characteristic of the flow limiter and P u P is the upstream pressure of the flow limiter detected by either the distal or proximal pressure sensor, and d is the downstream pressure of the flow restrictor detected by the other of the distal and proximal pressure sensors, T is the fluid temperature, mw is the fluid molecular weight, μ is the fluid viscosity, and γ is the fluid specific heat ratio. Examples of flow restrictor properties (R) include the restrictor orifice size. One or more flow restrictor properties may be considered when determining the mass flow rate by Equation 1 (for example, R may represent or encompass more than one physical parameter of the flow restrictor). Fluid properties, including molecular weight, viscosity, and specific heat ratio, may be known values.

[0036] Methods for determining mass flow rate based on pressures detected upstream and downstream of a flow restrictor are generally known in the art. A flow restrictor can be any suitable type for restricting fluid flow. Examples include critical nozzles, laminar flow elements, porous media flow restrictors, orifices, valves, or tubes. Any suitable form for restricting flow is acceptable.

[0037] Controllers 220 and 320 may be configured to output a determined mass flow rate. For example, pressure controllers 200 and 300 may include an output 240 for reporting the determined mass flow rate to other devices, or output 240 may be a display. While pressure controllers are configured to control the pressure of a fluid (rather than, for example, controlling mass flow to a mass setpoint), the monitored mass flow rate is useful information for process monitoring and may be reported to and / or used by other process devices. Selectively, the monitored pressure (for example, detected by distal pressure sensors 206 and 306) may also be an output.

[0038] By using proximal and distal pressure sensors, an integrated mass flow monitoring pressure controller can be provided, particularly suitable for use with reactive gases. While thermal flow sensors can be inaccurate for reactive gases, the pressure sensors in this device can accurately report the pressure of such gases, and this information can then be used to calculate the mass flow rate. Examples of suitable pressure sensors include Baratron® manometers (MKS Instruments) and pressure transducers.

[0039] A flowchart illustrating the operation of either the pressure controller in Figure 2 or Figure 3 is shown in Figure 4. Process 400 begins with the reception of the pressure setpoint (Psp) from the host (402). Upstream pressure (P u ), downstream pressure (P d ), and gas temperature (T) are measured (404). Flow (Q) is calculated based on the measured values ​​(406). Pressure setpoint (Psp) and measured distal pressure (depending on whether the pressure controller is configured for upstream or downstream pressure control, P u or P d Either of the above is provided to the feedback controller (K), and the feedback controller (K) determines a control command (I) for the control valve (408). The control valve is adjusted by the control command (I) to control the distal pressure to a pressure setpoint (410). The flow (Q) is adjusted to a monitored target pressure (P) as needed. u or P d (either of the above) and / or other information (e.g., control command (I), proximal pressure (P) u or P dThe pressure is reported to the host along with (412) one of the following (408, 410). The process can be repeated when a new pressure setpoint (Psp) is received from the host (402) while continuously or periodically monitoring the pressure against a given pressure setpoint. In process 400 of Figure 4, the flow calculation (406) is shown preceding the provision of the measured pressure to the feedback controller (408) and the adjustment of the control valve (410), but it should be understood that the flow calculation (406) may alternatively occur simultaneously with or after the provision of pressure feedback control (408, 410).

[0040] The provided method and device offer several improvements over existing methods and devices for providing pressure control along with integrated mass flow measurement. The pressure-based fluid measurement provided by the exemplary device and method can be more reliable than prior art devices that rely on thermal fluid measurement, particularly in reactive gas (e.g., ozone and oxygen mixture) environments. The provided device may be more durable than prior art devices. A compact and cost-effective pressure controller can be provided while using one of two pressure sensors (i.e., a pressure sensor distal to the control valve) in dual mode.

[0041] The pressure sensors shown in Figures 2 and 3, and the positions in the flow path where the sensors acquire pressure measurements, are generally described as “proximal” and “distal” based on the proximity of the devices to the control valve. The “distal pressure sensor” and / or “distal position” in the flow path can be on the side furthest from the control valve to the flow limiter. The “proximal pressure sensor” and / or “proximal position” in the flow path can be on the side closest to the control valve to the flow limiter.

[0042] All patent teachings, published applications and documents cited herein are incorporated by reference into this application.

[0043] While examples of specific embodiments are shown and described, it will be understood by those skilled in the art that various modifications can be made in form and detail without departing from the scope of these embodiments as encompassed by the appended claims.

Claims

1. A control valve configured to control the pressure of the fluid in the flow path, A flow limiter placed within the aforementioned flow path, A distal pressure sensor that detects the fluid pressure in the flow limiter at a position distal to the control valve, A proximal pressure sensor detects the fluid pressure in the flow limiter at a position proximal to the control valve, It is a controller, The drive of the control valve is controlled based on the pressure detected by the distal pressure sensor and the pressure set value. The mass flow rate is determined based on the pressure detected by the distal pressure sensor and the proximal pressure sensor. A controller configured in such a way Equipped with, Pressure controller.

2. The pressure controller according to claim 1, wherein the proximal position and the distal position are upstream of the control valve.

3. The pressure controller according to claim 1, wherein the proximal position and the distal position are downstream of the control valve.

4. The pressure controller according to claim 1, wherein the controller is configured to provide closed-loop feedback control of the control valve based on the pressure detected by the distal pressure sensor and the pressure setpoint.

5. The controller controls the mass flow rate Q Q=f(R,P u ,P d ,T,mw,μ,γ) (1) It is configured to be determined by a function given by, R is a characteristic of the flow limiter, and P u P is the upstream pressure of the flow limiter detected by either the distal pressure sensor or the proximal pressure sensor, d The pressure controller according to claim 1, wherein is the downstream pressure of the flow limiter detected by the other of the distal pressure sensor and the proximal pressure sensor, T is the temperature of the fluid, mw is the molecular weight of the fluid, μ is the viscosity of the fluid, and γ is the specific heat ratio of the fluid.

6. The pressure controller according to claim 1, further configured to output the determined mass flow rate.

7. The pressure controller according to claim 1, further comprising a temperature sensor for detecting the temperature of the fluid in the flow path.

8. The pressure controller according to claim 1, wherein the fluid is a reactive gas.

9. A method for controlling the pressure of a fluid, The control valve is driven based on the pressure and pressure setpoint detected by the distal pressure sensor, the control valve controls the fluid pressure in the flow path, the distal pressure sensor detects the fluid pressure in the flow limiter at a position distal to the control valve, and the flow limiter is located in the flow path. The mass flow rate is determined based on the pressure detected by the distal pressure sensor and the proximal pressure sensor, which detects the fluid pressure in the flow limiter at a position proximal to the control valve. method.

10. The method according to claim 9, wherein the proximal position and the distal position are upstream of the control valve.

11. The method according to claim 9, wherein the proximal position and the distal position are downstream of the control valve.

12. The method according to claim 9, wherein the drive control of the control valve includes providing closed-loop feedback control of the control valve based on the pressure detected by the distal pressure sensor and the pressure setpoint.

13. The aforementioned mass flow rate Q is Q=f(R,P u ,P d ,T,mw,μ,γ) (1) Determined by the function provided by, R is a characteristic of the flow limiter, and P u P is the upstream pressure of the flow limiter detected by either the distal pressure sensor or the proximal pressure sensor, d The method according to claim 9, wherein is the downstream pressure of the flow limiter detected by the other of the distal pressure sensor and the proximal pressure sensor, T is the temperature of the fluid, mw is the molecular weight of the fluid, μ is the viscosity of the fluid, and γ is the specific heat ratio of the fluid.

14. The method according to claim 9, further comprising outputting the determined mass flow rate.

15. The method according to claim 9, further comprising detecting the temperature of the fluid in the flow path.

16. The method according to claim 9, wherein the fluid is a reactive gas.

17. A control valve configured to control the pressure of the fluid in the flow path, A flow limiter placed within the aforementioned flow path, An upstream pressure sensor is provided upstream of the flow limiter to detect the fluid pressure in the flow limiter. A downstream pressure sensor located downstream of the flow limiter detects the fluid pressure in the flow limiter. It is a controller, The drive of the control valve is controlled based on the pressure and pressure setpoint detected by either the upstream pressure sensor or the downstream pressure sensor. The mass flow rate is determined based on the pressure detected by the upstream pressure sensor and the downstream pressure sensor. A controller configured as follows, Equipped with, Pressure controller.

18. The pressure controller according to claim 17, wherein the flow limiter, the upstream pressure sensor, and the downstream pressure sensor are arranged upstream of the control valve, and one of the upstream pressure sensor and the downstream pressure sensor is the upstream pressure sensor.

19. The pressure controller according to claim 17, wherein the flow limiter, the upstream pressure sensor, and the downstream pressure sensor are arranged downstream of the control valve, and one of the upstream pressure sensor and the downstream pressure sensor is the downstream pressure sensor.

20. A method for controlling fluid pressure, The control valve is driven based on a pressure setpoint and the pressure detected by either the upstream pressure sensor or the downstream pressure sensor, the upstream pressure sensor detects the fluid pressure in the flow limiter upstream of the flow limiter, the downstream pressure sensor detects the fluid pressure in the flow limiter downstream of the flow limiter, the control valve controls the pressure of the fluid in the flow path, and the flow limiter is located in the flow path. A method for determining mass flow rate based on the pressure detected by the upstream pressure sensor and the downstream pressure sensor.

21. The method according to claim 20, wherein the flow limiter, the upstream pressure sensor, and the downstream pressure sensor are arranged upstream of the control valve, and one of the upstream pressure sensor and the downstream pressure sensor is the upstream pressure sensor.

22. The method according to claim 21, wherein the flow limiter, the upstream pressure sensor, and the downstream pressure sensor are arranged downstream of the control valve, and one of the upstream pressure sensor and the downstream pressure sensor is the downstream pressure sensor.

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