Mass flow controller and system

Abstract

A method and apparatus for pulsed gas delivery with pressure control is provided. A pulsed gas supply with mass flow control is obtained by using a thermal mass flow sensor and a control valve. The controller is augmented for pressure control with a downstream pressure sensor. In separate control operating modes, the control valve is controlled in response to the flow sensor in a pulsed gas supply mode and in response to the downstream pressure sensor in a pressure control operating mode.

Description

[Technical Field]

[0001] Related applications This application claims the benefits of U.S. Provisional Patent Application No. 63 / 116,599, filed on November 20, 2020. The teachings of this application are entirely incorporated herein by reference. [Background technology]

[0002] Semiconductor manufacturing processes, such as atomic layer deposition (ALD), may require the supply of several different gases and gas mixtures in varying quantities across several processing steps. Generally, the gases are stored in tanks within the processing facility, and gas metering systems are used to supply metered quantities of gas from the tanks to processing tools such as chemical vapor deposition reactors, vacuum sputtering equipment, and plasma etchers.

[0003] Pulsed gas supply devices have been developed to deliver pulsed gas flows to semiconductor process tools. Several such devices are described below.

[0004] Figure 1 shows one basic configuration of pulsed gas supply. Gas flowing from input 101 through channel 103 is pulsed by shut-off valve 102. The shut-off valve is a conventional on / off type isolation valve that is completely open or completely closed under control from a host controller 104. Control from the host controller may be via an electrical connection 106, or the electrical input may be to a pilot valve that supplies pressurized air to the shut-off valve to open or close it. A pressure controller 108 can be positioned inline upstream of the shut-off valve.

[0005] Figure 2 shows a simple configuration of a pressure controller. A pressure sensor 202 detects the gas pressure in channel 103 and provides the detected pressure to a microprocessor control unit 204. This microprocessor compares the detected pressure to a pressure setpoint and controls the opening state of an adjustable control valve 206 based on the error between the two. The opening of the control valve in channel 103 can be controlled in response to a control signal from the microprocessor 204.

[0006] The pressure controller maintains the gas pressure supplied to the process chamber through the shut-off valve 102 at a desired setpoint. Furthermore, when the shut-off valve 102 is closed, the pressure in channel 103 can be controlled by allowing leakage through a leak line 110 to a secondary leak line. The leak line may include a needle valve or an orifice 112. To maintain the pressure in channel 103 through leakage through line 110, the flow through the control valve 206 can be controlled in response to the pressure sensor 202. In addition, some pressure controllers include a flow sensor, which may be useful in pressure control. Flow peaks and troughs can also be useful diagnostic information.

[0007] Figure 3 shows another configuration of the pulsed gas supply system in which the pressure controller of Figure 1 is replaced by a mass flow controller (MFC) 310. Similar to the pressure controller in Figure 2, the mass flow controller also includes a control valve to control the flow in response to a control signal from a microprocessor control unit within the MFC. However, the MFC relies on a flow sensor rather than a pressure sensor. The flow sensor is typically a thermal flow sensor upstream of the control valve or a pressure-based flow sensor downstream of the control valve. The two-way shut-off valve and leak line of Figure 1 may be used, or they may be replaced by a three-way isolation valve in 330 that pulses the gas to the process chamber or diverts the gas to a diversion line 340 under the control of a host controller 320. The host controller 320 also communicates with the processor within the MFC 310 to set a flow setpoint so that the MFC 310 maintains a constant flow in the pulsed gas supply process. The host controller 320 controls and switches the downstream isolation valve 330 so that the gas flow is directed to the process chamber or to the diversion line in order to supply gas pulses to the chamber.

[0008] The drawbacks of the pulsed gas supply systems in Figures 1 and 3 are that the pulse accuracy and repeatability depend on the speed and reliability of the shut-off valves 102 or 330, which can degrade over time. Furthermore, gas is constantly flowing in each system, which leads to the waste of process gas through leak lines or diversion lines.

[0009] Figure 4 shows a conventional pulsed gas supply device 400 that uses pressure-based pulsed gas supply. Pressure-based molar measurement techniques utilize the pressure (P) versus time (t) response of a gas introduced into a known volume. The device 400 consists of a chamber 450 providing a known volume, and an upstream (V) of the chamber 450. in The valve 440 is located in the ) and downstream of the chamber 450 ("V out This includes a valve 445 positioned in the chamber 450. A pressure sensor 465 and a temperature sensor 460 are also provided, positioned in the chamber 450.

[0010] First, the device 400 is filled by opening the upstream valve 440 while the downstream valve 445 is closed, thereby filling the chamber 450 over a predetermined time period ("filling" period Δt = t1 - t0) with a gas flow (Q i ) may enter the apparatus and a change in pressure may occur. At time t1 and pressure P2, the upstream valve 440 is closed ("Vin CLOSE"). The process then includes a period (t2-t1) during which the gas in the chamber 450 is allowed to stabilize at a setpoint. During this period, pressure and temperature measurements are taken by the pressure sensor 465 and the temperature sensor 460. When the downstream valve 445 is opened ("Vout OPEN" at time t2), the gas flow (Q o The device 400 is then disconnected until valve 345 is closed again ("Vout CLOSE" at time t3), thereby supplying a pulse of gas and a pressure change (ΔP=P2-P1) from the device to the processing tool over a predetermined period of time ("supply" period Δt=t3-t2). The time t3 at which the pulse ends to obtain the desired number of moles of gas is determined from the known volume, pressure P2, and temperature of the gas through a fall velocity calculation.

[0011] The system shown in Figure 4 has several limitations. The accuracy and repeatability of pulse supply depend on the speed and reliability of the downstream shut-off valve 445. A shut-off valve with a fast response time is desirable. However, if the valve has aged, it may be necessary to implement adaptive adjustments, which may result in added complexity or the need to replace the valve, which usually requires process interruption. Often, the pulse shape (e.g., pulse width) is not desirable, or the pulse does not adequately match the desired square wave. Furthermore, the need to fill the chamber 350 with a predetermined volume of gas takes time. The gas filling time and stabilization time before each pulse limit the rapid gas supply cycle time.

[0012] However, the advantage of pressure-based molar measurement techniques lies in the fact that they can be applied without knowledge of the specific gas or gas mixture being measured. The gas flow rate, derived from the application of mass balance and ideal gas laws across the chamber volume, is gas-independent and depends on three state variables—pressure (P), temperature (T), and volume (V)—to characterize the behavior of the gas being measured.

[0013] Figure 5 shows another conventional system 500 for pulsed feeding based on gas moles. A pressure-based MFC 510 is configured for pulsed feeding. A host controller 520 communicates with the control unit 505 of the MFC 510 to provide desired pulsed feeding information, such as the pulse mole setpoint, pulse-on period, pulse-off period, and the number of pulses to be repeated. To initiate a pulsed feeding cycle, the host controller 520 sends a trigger signal to the MFC 510. The MFC 510 includes a control valve 580 (e.g., a proportional control valve) to control the flow of gas from the gas source into the flow channel 515. The control unit 505 of the MFC 510 is configured to control the flow of gas through the control valve 580 to control the gas supplied to the process chamber in gas pulses. The control unit 505 controls the flow of gas through the control valve 580 based on feedback from a flow sensor 525 provided to measure the flow rate (Q) in the flow channel. Each flow sensor 525 includes a flow restrictor 570 in the flow channel 515 and upstream and downstream pressure sensors 555 and 565, respectively. The control valve 580 is typically located upstream of the restrictor 570 and the pressure sensors. An alternative to the pressure-based flow sensor is a heat-based flow sensor, which would typically be located upstream of the control valve. Additionally, the temperature sensor 560 can communicate with the control unit 505.

[0014] Figure 6 shows pulsed supply in the system of Figure 5, utilizing a gas supply rate defined by the product of an ideal rectangular flow setpoint (Q) and supply time (Δt). A gas supply cycle 600 can be defined by a "pulse-on" period (t2-t1), a "pulse-off" period (t3-t2), a gas supply rate (e.g., moles of gas / pulse), and the number of pulses / cycle. For the purpose of pulsed supply, the gas mole supply rate can be defined as ideal flow setpoint (Q) × supply time (Δt=t2-t1).

[0015] The step function flow supply shown in Figure 6, while ideal, is impractical due to the time constants of the actual sensors and valves. In practical applications, accuracy and repeatability of the supply amount within the required time frame are important objectives. Therefore, it is desirable to supply the gas accurately and repeatedly. To this end, the computational capabilities of the MFC can be used to calculate and adjust the flow to supply the required amount of gas within a specified time. Specifically, the MFC can be configured to calculate the actual amount of gas supplied and to adjust it to a target pulse gas supply amount.

[0016] An improvement to the pulse MFC controller shown in Figure 5 is presented in U.S. Patent No. 10,649,471 to Ding et al., which is incorporated herein by reference. As disclosed in this patent, an isolation valve can be coupled to the output of the MFC to make the pulse shape relatively rectangular or ideal. [Prior art documents] [Patent Documents]

[0017] [Patent Document 1] U.S. Patent No. 10,649,471 [Overview of the Initiative] [Means for solving the problem]

[0018] A system that relies on a pressure controller and shut-off valve to supply gas pulses, as shown in Figure 1, can be upgraded to pulsed MFC pulsing as shown in Figure 5 with minimal upgrades using a pulsed MFC with integrated pressure control, while maintaining the functionality of pressure control. The resulting system provides substantially improved pulsed gas supply in terms of accuracy, repeatability, and reproducibility, and further enables mole-based pulsing. The otherwise stringent requirements for shut-off valves for pressure-controlled pulsing are reduced because shut-off valves are no longer required for pulsing.

[0019] In a pulsed gas supply system, the advantages of both a pulsed mass flow controller gas supply system and a pressure controller are obtained through a single integrated controller. In pulsed gas supply operating mode, the controller relies on the flow rate measured by the flow sensor to control the control valve. In pressure control mode, the controller relies on the pressure measured by the downstream pressure sensor to control the control valve.

[0020] The gas supply system has a flow channel, a flow sensor configured to measure the flow rate in the flow channel, a control valve configured to control the gas flow in the flow channel, and a downstream pressure sensor downstream of the flow sensor and the control valve configured to measure the gas pressure in the flow channel. The control unit is configured to receive signals from the flow sensor and from the pressure sensor, and to apply a control signal to the control valve. The control unit is configured for separate operating modes including (1) a pulsed gas supply mode in which the control unit is configured to start a pulse of gas flow by opening the control valve, to end a pulse of gas flow by closing the control valve, and to control the mass of gas supplied in the pulse based on the flow rate measured by the flow sensor and the control of the control valve in the pulse, and (2) a pressure control mode in which the control unit is configured to control the pressure at the pressure sensor based on the pressure measured by the pressure sensor and the control of the control valve.

[0021] The method of gas supply has the steps of providing a flow sensor for measuring the flow rate in the flow channel, a control valve for controlling the gas flow in the flow channel, and a downstream pressure sensor downstream of the flow sensor and the control valve for measuring the gas pressure in the flow channel. The control unit controls the gas flow through the control valve in separate operating modes including (1) a pulsed gas supply mode in which a pulse of gas flow is started by opening the control valve and ended by closing the control valve, and the mass of gas supplied during the pulse is controlled based on the flow rate measured by the flow sensor and the control of the control valve during the pulse, and (2) a pressure control mode in which the pressure at the pressure sensor is controlled based on the pressure measured by the pressure sensor and the control of the control valve.

[0022] In the pulse gas supply mode, the number of moles of gas supplied in a pulse can be controlled as a function of the measured flow rate, the start time when the pulse of the gas flow is initiated, and the stop time when the pulse of the gas ends. Alternatively, instead of this, the control unit can also be configured for supply based on the time during which the control of the gas flow with respect to the flow setpoint is carried out.

[0023] The isolation valve can be located within the flow channel downstream of the pressure sensor. The isolation valve can be opened in the pulse gas supply mode so that the pulse accuracy and repeatability are not affected by the state of the isolation valve. A leakage line can be coupled to the flow channel upstream of the isolation valve or as a diversion line in the isolation valve. The isolation valve can be closed in the pressure control operation mode while gas leaks or leaks through the leakage line.

[0024] The control unit can be configured to receive a signal from the host controller so as to switch between the pulse gas supply operation mode and the pressure control operation mode. The system can switch to the pressure control mode after the completion of the pulse sequence in the pulse supply mode. The measured gas pressure may be used for diagnosis in the pulse gas supply mode, and the measured flow rate may be used for diagnosis in the pressure control mode.

[0025] The flow sensor may be a thermal flow sensor upstream of the control valve.

[0026] The system has a specific application for an ALD tool.

[0027] Regarding the above content, it will become clear from the following more specific description of the exemplary embodiments shown in the accompanying drawings, in which the same reference numerals refer to the same parts throughout different figures. The scale of the drawings is not necessarily accurate, and instead, emphasis is placed on the illustration of the embodiments.

Brief Description of the Drawings

[0028] [Figure 1] This is a diagram of a conventional pulsed gas supply system in which pulses are controlled via an on / off valve. [Figure 2] This is a diagram of a pressure controller suitable for use in the system shown in Figure 1. [Figure 3] This is a diagram of another conventional pulsed gas supply system that relies on a mass flow controller and / or an on / off isolation valve. [Figure 4] This is a diagram of a conventional fall velocity pulse gas supply system. [Figure 5] This is a diagram of a pulsed gas supply system based on conventional pulsed MFC technology. [Figure 6] Figure 5 shows the sequence of pulses supplied by the system. [Figure 7] This is a diagram of a pulsed gas supply device (PGDPC) with integrated pressure control according to the present invention. [Figure 8A] Figure 7 is a control diagram of the PGDPC in pulse gas supply operation mode. [Figure 8B] Figure 7 is a control diagram of the PGDPC in pressure control operation mode. [Figure 9] Figure 7 shows the PGDPC in a system including an on / off valve. [Figure 10] This is a diagram of a modified PGDPC with an upstream pressure sensor. [Modes for carrying out the invention]

[0029] The following describes an exemplary embodiment.

[0030] Figure 7 shows a pulsed gas supply device (PGDPC) with integrated pressure control. In pulsed gas supply operating mode, the controller components are those found in a typical pulsed mass flow controller. The flow channel 702 has a gas inlet 704 and a gas outlet 706. The flow through the channel 702 is measured by a thermal flow sensor 708, which receives a portion of the flow in the channel 702, with the remainder flowing through a bypass 710. The flow detected by the flow sensor 708 is provided to a control unit 712, which may be a microprocessor. The control unit 712 compares the detected flow to a flow setpoint so as to control the amount by which the control valve 714 is opened to obtain a desired flow rate.

[0031] In pressure control operation mode, the controller includes a pressure sensor 716 that measures the downstream pressure in channel 702 and provides the detected pressure to the microprocessor control unit. In this operation mode, the control unit compares the detected pressure to a pressure setpoint and controls the amount by which the control valve 714 is opened to maintain the desired pressure in channel 702. The control valve 580 is adjustable independently of the on / off isolation valve. The degree of opening of the control valve can be controlled to limit the flow and to enable control of the flow in the flow channel 515.

[0032] Therefore, in separate operating modes, the microprocessor responds to separate sensors that control the common control valve 714. With a single integrated device, the system can improve the performance of both pulsed gas supply and pressure control functions. When the device is in pulsed gas supply mode, including mole-based and time-based supply, the downstream pressure sensor 716 can provide diagnostic signals for pulsed gas supply. As gas pulses pass through the control valve 714, the downstream pressure sensor 716 can detect the pressure rise and fall generated by these gas pulses. The user can use this pressure diagnostic signal to monitor pulsed gas supply performance. When the device is in pressure control mode, the upstream flow sensor 708 can provide diagnostic signals for the pressure control process. As the control valve 714 controls the flow through the valve, the upstream flow sensor can detect the flow changes generated by this pressure control action. The user can use this flow diagnostic signal to monitor pressure control performance.

[0033] Parameters for both pulsed gas supply and pressure control are downloaded from the host controller via line 720. When a pulsed gas supply sequence is required, the host controller provides a trigger signal to the microprocessor, and the microprocessor executes the pulse sequence. Upon receiving the trigger signal, the microprocessor 712 controls the pulsed gas supply process according to a pre-downloaded recipe by turning on the control valve 714 at the start of each pulse, controlling the flow to a target flow setpoint by adjusting the openness of the control valve, and controlling the flow to zero by closing the valve to end each pulse.

[0034] Pulse gas supply may be disclosed in the preceding U.S. Patents No. 10,353,408 and No. 10,649,471, which are incorporated herein by reference.

[0035] In the case of mole-based pulse supply, the user specifies the following parameters: (1) mole supply setpoint (SP), (2) duration of the target pulse-on period, (3) total pulse-on and pulse-off periods, and (4) number of pulses (N). Based on this information, the dedicated control unit 712 is configured to automatically adjust the flow setpoint and / or pulse-on period according to the following formula, based on the measurement values ​​obtained by the flow sensor 708, in order to accurately supply the target amount of moles of gas within the target pulse-on period.

number

[0036] Accordingly, by using a mole-based pulse supply mode, the control unit 712 controls and adjusts the flow to control the number of moles supplied by each pulse as needed. Based on these parameters, the device automatically supplies N pulses of flow in a precise timing sequence, with each pulse supplying Δn moles during a portion of each total pulse period in which the device is ON, as shown in Figure 6, and turning off the device for the remainder of the total pulse ON and OFF periods.

[0037] Figure 8A shows the control diagram of the control unit 712 in the mole-based pulse supply mode. The error E is the difference between the mole supply setpoint SP and the measured supplied amount Δn, which is the integral of the measured flow Q.

number

[0038] The output of controller K is the manipulated variable U, i.e., the valve drive current for control valve 714. For example, when the controller is a PID controller, the output of controller K is as follows:

Equation

[0039] As an alternative to the mole-based pulsed gas supply, the time-based pulsed gas supply process can be followed. In the time-based pulsed supply process, the host configures a dedicated control unit 712 based on parameters of a process that requires control of (1) at least one target flow setpoint (Q sp ), (2) at least one duration (T on ) of the pulse-on period, (3) at least one duration (T off ) of each pulse-off period, and the total number (N) of pulses required to complete the process.

[0040] In the time-based supply, the setpoint SP applied to the control in Fig. 8A is the flow setpoint, and the error is the difference between the flow setpoint and Q.

[0041] Fig. 8B is a control diagram of control unit 712 in the pressure control operation mode. Here, the error is the difference between the pressure setpoint (SP) and the controlled variable, i.e., the measured pressure P. E = SP - P

[0042] The output from controller K is the manipulated variable U, i.e., the valve drive current for control valve 714. For example, when the controller is a PID controller, the output of the controller is as follows.

Equation

[0043] Under normal operation, the PGDPC operates in pressure control mode until it is triggered by the host controller to enter pulsed gas supply mode. The device may switch to pressure control mode between pulses of pulsed gas supply, but this is generally unnecessary or undesirable. After the completion of pulsed gas supply mode through the entire pulse sequence, the device can automatically switch to pressure control mode.

[0044] Figure 9 shows the PGDPC700 of Figure 7 in a system having a shut-off valve 902, both controlled by a host controller 904. A leak line 906 having a needle valve or orifice 908 allows for pressure control when the shut-off valve is closed. Control of the shut-off valve (on / off isolation valve) may be via a direct electrical signal or via a control gas pilot valve. As an alternative to a two-way isolation valve with a leak line, a three-way valve with a flow diversion line can be used.

[0045] Generally, in pulsed gas supply mode, the host controller 904 signals the shut-off valve 902 to open, and then triggers the pulsed gas supply sequence of the PGDPC 700. The shut-off valve is normally closed when the PGDPC is not in pulsed gas supply mode, but it may be opened for diagnostic or other purposes. During this time, the PGDPC 700 may be configured to operate in constant flow control mode.

[0046] Figure 10 shows a modification of the PGDPC in Figure 7, further including an upstream pressure sensor 1302 to provide upstream line pressure and to allow pressure-insensitive flow control for pulsed gas supply.

[0047] A suitable flow sensor is a thermal flow sensor, but instead, a pressure-based flow sensor with flow limiting, having upstream and downstream pressure sensors, can also be used. In the case of a pressure-based flow sensor, the flow sensor is usually located downstream of the control valve. This configuration is not very desirable because the flow sensor isolates the control valve from the downstream pressure sensor in pressure-controlled operating mode. Also, when a pressure-based flow sensor is used, the downstream pressure sensor of the pressure sensor will function as a downstream pressure sensor for pressure control.

[0048] All patents, published applications, and teachings cited herein are, by reference, entirely incorporated herein.

[0049] While the embodiments described above are illustrative and descriptive, those skilled in the art will understand that various modifications in form and detail can be made therein without departing from the scope of the embodiments covered by the appended claims. Furthermore, the present invention includes the following embodiments. [Aspect 1] A gas supply system, Flow channels and A flow sensor configured to measure the flow rate in the flow channel, A control valve configured to control the flow of gas in the flow channel, The flow sensor and the downstream pressure sensor located downstream of the control valve are configured to measure the gas pressure in the flow channel. A control unit configured to receive signals from the flow sensor and the pressure sensor, and to apply control signals to the control valve, Includes, The control unit is A pulse gas supply mode is configured such that the control unit starts a pulse of gas flow by opening the control valve, ends the pulse of gas flow by closing the control valve, and controls the mass of gas supplied during the pulse based on the flow rate measured by the flow sensor and the control of the control valve during the pulse, The control unit is configured to control the pressure at the pressure sensor based on the pressure measured by the pressure sensor and the control of the control valve, in a pressure control mode, A system configured for separate operating modes, including [Aspect 2] The gas supply system according to embodiment 1, wherein in the pulsed gas supply mode, the number of moles of gas supplied between pulses is controlled as a function of the measured flow rate. [Aspect 3] The gas supply system according to embodiment 1, wherein in the pulsed gas supply mode, the control unit is configured for time-based supply having control of the gas flow relative to a flow setpoint. [Aspect 4] The gas supply system according to embodiment 1, further comprising an isolation valve downstream of the pressure sensor. [Aspect 5] The gas supply system according to embodiment 4, further comprising a leak line upstream of the isolation valve. [Aspect 6] The gas supply system according to embodiment 1, further comprising an upstream pressure sensor upstream of the control valve. [Aspect 7] The gas supply system according to embodiment 1, wherein the control unit is configured to receive a signal from a host controller to switch between a pulse gas supply operation mode and a pressure control operation mode. [Aspect 8] The gas supply system according to embodiment 1, wherein the flow sensor is a heat flow sensor located upstream of the control valve. [Aspect 9] The gas supply system according to embodiment 1, wherein the control unit is configured to use the pressure measured by the downstream pressure sensor for diagnosis in the pulse gas supply mode and to use the measured flow rate for diagnosis in the pressure control mode. [Aspect 10] A method of supplying gas, The steps include providing a flow sensor for measuring the flow rate in a flow channel, a control valve for controlling the flow of gas in the flow channel, and a downstream pressure sensor downstream of the flow sensor and the control valve for measuring the gas pressure in the flow channel, The control unit controls the gas flow through the control valve in a separate operating mode, Includes, The aforementioned separate operating modes are: A pulsed gas supply mode in which a gas flow pulse is started by opening the control valve and ended by closing the control valve, and the mass of the gas supplied during the pulse is controlled based on the flow rate measured by the flow sensor and the control of the control valve during the pulse, The pressure in the pressure sensor is controlled based on the pressure measured by the pressure sensor and the control of the control valve, and the pressure control mode is controlled accordingly. Methods that include... [Aspect 11] The method according to embodiment 10, wherein, in the pulsed gas supply mode, the number of moles of gas supplied between pulses is controlled as a function of the measured flow rate. [Aspect 12] The method according to embodiment 10, wherein in the pulsed gas supply mode, the control unit is configured for time-based supply having control of the gas flow relative to a flow setpoint. [Aspect 13] The method according to embodiment 10, further comprising the step of opening an isolation valve downstream of the pressure sensor in the pulse gas supply mode. [Aspect 14] The method according to embodiment 13, further comprising the step of closing the isolation valve and allowing gas to leak through the leak line upstream of the isolation valve in the pressure control operation mode. [Aspect 15] The method according to embodiment 10, further comprising the steps of measuring the upstream pressure by an upstream pressure sensor upstream of the control valve and providing pressure-sensing flow control based on the measured upstream pressure. [Aspect 16] The method according to embodiment 10, further comprising the step of switching between the pulse gas supply mode and the pressure mode in response to a signal from a host controller. [Aspect 17] The method according to embodiment 10, further comprising the step of switching to the pressure control mode after the completion of the pulse sequence in the pulse supply mode. [Aspect 18] The method according to embodiment 10, further comprising the step of supplying the gas to an ALD tool. [Aspect 19] The method according to embodiment 10, wherein the measured gas pressure is used for diagnosis in the pulsed gas supply mode, and the measured flow rate is used for diagnosis in the pressure control mode. [Aspect 20] A mass flow controller, As a single, integrated assembly, Flow channels and A flow sensor configured to measure the flow rate within the flow channel, A control valve configured to control the flow of gas within the flow channel, The flow sensor and the downstream pressure sensor located downstream of the control valve are configured to measure the gas pressure within the flow channel. A control unit configured to receive signals from the flow sensor and the pressure sensor, and to apply control signals to the control valve, Includes, The control unit is A pulsed gas supply mode is configured such that the control unit starts a pulse of gas flow by opening the control valve, ends the pulse of gas flow by closing the control valve, and controls the mass of gas supplied during the pulse based on the flow rate measured by the flow sensor and the control of the control valve during the pulse, The control unit is configured to control the pressure at the pressure sensor based on the pressure measured by the pressure sensor and the control of the control valve, in a pressure control mode, A mass flow controller configured for separate operating modes, including [Aspect 21] The mass flow controller according to embodiment 20, wherein in the pulsed gas supply mode, the number of moles of gas supplied between pulses is controlled as a function of the measured flow rate. [Aspect 22] In the pulsed gas supply mode, the controller is configured for time-based supply having control of the gas flow relative to a flow setpoint, according to embodiment 20. [Aspect 23] The mass flow controller according to embodiment 20, further comprising an upstream pressure sensor upstream of the control valve. [Aspect 24] The mass flow controller according to embodiment 20, wherein the controller is configured to receive a signal from a host controller in order to switch between a pulse gas supply operation mode and a pressure control operation mode. [Aspect 25] The mass flow controller according to embodiment 20, wherein the flow sensor is a heat flow sensor located upstream of the control valve. [Aspect 26] The mass flow controller according to embodiment 20, wherein the control unit is configured to use the pressure measured by the downstream pressure sensor for diagnosis in the pulse gas supply mode and to use the measured flow rate for diagnosis in the pressure control mode.

Claims

1. A gas supply system, Flow channels and A flow sensor configured to measure the flow rate in the flow channel, A control valve configured to control the flow of gas in the flow channel, The flow sensor and the pressure sensor downstream of the control valve are configured to measure the gas pressure in the flow channel. A control unit configured to receive signals from the flow sensor and the pressure sensor, and to apply control signals to the control valve, Includes, The control unit is A pulse gas supply mode is configured such that the control unit starts a pulse of gas flow by opening the control valve, ends the pulse of gas flow by closing the control valve, and controls the mass of gas supplied during the pulse based on the flow rate measured by the flow sensor and the control of the control valve during the pulse, The control unit is configured to control the pressure at the pressure sensor based on the pressure measured by the pressure sensor and the control of the control valve, in a pressure control mode, A system configured for separate operating modes, including

2. The gas supply system according to claim 1, wherein in the pulsed gas supply mode, the number of moles of gas supplied between pulses is controlled as a function of the measured flow rate.

3. The gas supply system according to claim 1, wherein in the pulsed gas supply mode, the control unit is configured for time-based supply having control of the gas flow with respect to a flow setpoint.

4. The gas supply system according to claim 1, further comprising an isolation valve downstream of the pressure sensor.

5. The gas supply system according to claim 4, further comprising a leak line upstream of the isolation valve.

6. The gas supply system according to claim 1, further comprising an upstream pressure sensor upstream of the control valve.

7. The gas supply system according to claim 1, wherein the control unit is configured to receive a signal from a host controller to switch between a pulse gas supply operation mode and a pressure control operation mode.

8. The gas supply system according to claim 1, wherein the flow sensor is a heat flow sensor located upstream of the control valve.

9. The gas supply system according to claim 1, wherein the control unit is configured to use the pressure measured by the downstream pressure sensor for diagnosis in the pulse gas supply mode and to use the measured flow rate for diagnosis in the pressure control mode.

10. A method of supplying gas, A flow sensor for measuring the flow rate in a flow channel, a control valve for controlling the flow of gas in the flow channel, and a pressure sensor downstream of the flow sensor and the control valve for measuring the gas pressure in the flow channel. The steps to be provided, The control unit controls the gas flow through the control valve in a separate operating mode, Includes, The aforementioned separate operating modes are: A pulsed gas supply mode in which a gas flow pulse is started by opening the control valve and ended by closing the control valve, and the mass of the gas supplied during the pulse is controlled based on the flow rate measured by the flow sensor and the control of the control valve during the pulse, The pressure in the pressure sensor is controlled based on the pressure measured by the pressure sensor and the control of the control valve, and the pressure control mode is controlled accordingly. Methods that include...

11. The method according to claim 10, wherein, in the pulsed gas supply mode, the number of moles of gas supplied between pulses is controlled as a function of the measured flow rate.

12. The method according to claim 10, wherein in the pulsed gas supply mode, the control unit is configured for time-based supply having control of the gas flow relative to a flow setpoint.

13. The method according to claim 10, further comprising the step of opening an isolation valve downstream of the pressure sensor in the pulse gas supply mode.

14. The method according to claim 13, further comprising the step of closing the isolation valve and allowing gas to leak through the leak line upstream of the isolation valve in the pressure control mode.

15. The method according to claim 10, further comprising the steps of measuring the upstream pressure using an upstream pressure sensor upstream of the control valve, and providing pressure-sensing flow control based on the measured upstream pressure.

16. The method according to claim 10, further comprising the step of switching between the pulse gas supply mode and the pressure control mode in response to a signal from a host controller.

17. The method according to claim 10, further comprising the step of switching to the pressure control mode after the completion of the pulse sequence in the pulse gas supply mode.

18. The method according to claim 10, further comprising the step of supplying the gas to an ALD tool.

19. The method according to claim 10, wherein the measured gas pressure is used for diagnosis in the pulsed gas supply mode, and the measured flow rate is used for diagnosis in the pressure control mode.

20. A mass flow controller, As a single, integrated assembly, Flow channels and A flow sensor configured to measure the flow rate within the flow channel, A control valve configured to control the flow of gas within the flow channel, The flow sensor and the pressure sensor downstream of the control valve are configured to measure the gas pressure within the flow channel. A control unit configured to receive signals from the flow sensor and the pressure sensor, and to apply control signals to the control valve, Includes, The control unit is A pulsed gas supply mode is configured such that the control unit starts a pulse of gas flow by opening the control valve, ends the pulse of gas flow by closing the control valve, and controls the mass of gas supplied during the pulse based on the flow rate measured by the flow sensor and the control of the control valve during the pulse, The control unit is configured to control the pressure at the pressure sensor based on the pressure measured by the pressure sensor and the control of the control valve, in a pressure control mode, A mass flow controller configured for separate operating modes, including

21. The mass flow controller according to claim 20, wherein in the pulsed gas supply mode, the number of moles of gas supplied between pulses is controlled as a function of the measured flow rate.

22. The mass flow controller according to claim 20, wherein in the pulsed gas supply mode, the control unit is configured for time-based supply having control of the gas flow with respect to a flow setpoint.

23. The mass flow controller according to claim 20, further comprising an upstream pressure sensor upstream of the control valve.

24. The mass flow controller according to claim 20, wherein the control unit is configured to receive a signal from a host controller in order to switch between a pulse gas supply operation mode and a pressure control operation mode.

25. The mass flow controller according to claim 20, wherein the flow sensor is a heat flow sensor located upstream of the control valve.

26. The mass flow controller according to claim 20, wherein the control unit is configured to use the pressure measured by the downstream pressure sensor for diagnosis in the pulse gas supply mode and to use the measured flow rate for diagnosis in the pressure control mode.

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