Method and apparatus for pulse gas delivery

Abstract

To provide a pressure-controlled pulse gas delivery system which can accurately deliver a prescribed amount of gas in a prescribed pulse width (pulse duration time).SOLUTION: In a pulse gas delivery system, a chamber is pre-charged to a prescribed pressure through an upstream valve. Thereafter, a downstream control valve is opened to control a flow of gas during a gas pulse. A dedicated controller may control the downstream control valve in a feedback loop during the pulse on the basis of pressure and temperature detected during the pulse.SELECTED DRAWING: Figure 5

Description

Related Applications

[0001] This application is a continuation of U.S. Application No. 16 / 376,861, filed April 5, 2019, the entire teachings of which are incorporated herein by reference. [Background technology]

[0002] Semiconductor manufacturing processes, such as atomic layer deposition (ALD) processes, may require the delivery of multiple different gases or gas mixtures in varying amounts over multiple steps. Typically, each gas is stored in a respective tank in a processing facility, and a gas metering system is used to deliver a metered amount of each gas from the respective tank to a processing tool, such as a chemical vapor deposition reactor, a vacuum sputtering tool, a plasma etcher, etc. Components such as valves, pressure regulators, mass flow controllers (MFCs), mass flow ratio control systems, etc., are typically included in the gas metering system or in the flow path from the gas metering system to the processing tool.

[0003] Pulsed gas delivery systems have been developed to provide pulsed mass flows of gas to semiconductor processing tools. In high speed processes, pulsed gas delivery can be used to fabricate advanced three-dimensional integrated circuits with through silicon vias (TSVs) that provide die-to-die and wafer-to-wafer interconnects.

[0004] In a conventional pressure-based pulsed gas supply system, a volume is filled to a predetermined pressure through an inlet shutoff valve with an outlet shutoff valve closed. The inlet valve is then closed and the outlet valve is opened to allow gas to pass to the processing tool until the pressure of the volume drops to another predetermined level. According to the ideal gas law, the mass of gas flowing through the open outlet valve depends on the pressure difference when the valve is opened and closed, the volume, and the temperature of the gas. Recently, mass flow controllers have been applied for pulsing based on a feedback loop from a flow sensor. Typically, an MFC includes an inlet, an outlet, a mass flow sensor, and a proportional control valve adjusted to achieve the desired mass flow. A fast closing control valve can be used to pulse the flow. Summary of the Invention [Problem to be solved by the invention]

[0005] An improvement is provided to pressure-based pulsed gas delivery systems. In particular, the usual ON / OFF shut-off valve downstream of the chamber is replaced with an adjustable control valve. The opening of the control valve can be controlled to restrict flow and control the pressure-based delivery during the pulse. With appropriate control during the pulse, including a feedback loop, a precisely defined amount of gas can be delivered at a defined pulse width (pulse duration). [Means for solving the problem]

[0006] The pulsed gas delivery system includes a chamber having a volume, a pressure sensor configured to detect a pressure of a gas in the chamber, and a temperature sensor configured to detect a temperature of the gas in the chamber. An upstream valve is configured to control a flow of gas into the chamber. A downstream control valve is configured to control a flow of the gas out of the chamber. A controller is configured to control the upstream valve and the downstream control valve to fill the chamber to an initial pressure, and then control the flow of the gas out of the chamber through the downstream control valve during a gas pulse (for each individual gas pulse) to control the time and amount of the gas pulse based on the detected pressure and temperature.

[0007] The controller may be configured to control the downstream control valve in a feedback loop to adjust the flow during the pulse based on the pressure and temperature detected during the pulse.

[0008] The controller may be further configured to calculate a flow rate of the gas out of the chamber and control the downstream control valve to adjust the flow rate of the gas out of the chamber based on the calculated flow rate and a target flow set point. The controller may be configured to calculate the flow rate, Q, based on a pressure decay rate:

[0009] Q = -(V × T stp / P stp )×(d(P / T) / dt)

[0010] where V represents the volume of the chamber and T stp stands for standard temperature, and P stp represents standard pressure, P represents the pressure of the gas in the chamber, and T represents the temperature of the gas in the chamber.

[0011] The controller may be further configured to calculate the amount of gas dispensed from the chamber and control the downstream control valve to dispense a predetermined amount of gas during the gas pulse. The controller may calculate the amount of gas dispensed from the chamber based on the volume of the chamber, the initial pressure of the gas in the chamber detected by the pressure sensor at the beginning of the pulse, the pressure of the gas in the chamber detected by the pressure sensor during the pulse, and the temperature detected by the temperature sensor during the pulse. The molar amount Δn(t) of the gas dispensed from the chamber at time t during the pulse may be calculated as a function Δn(t)=V×(P t0 -P t ) / (R×T t ) where V represents the volume of the chamber and P t0 represents the pressure of the gas in a volume at the start of the pulse, P t represents the pressure of the gas in the chamber at the time t during the pulse, and T t represents the temperature of the gas at the time t during the pulse.

[0012] The controller may be configured to adjust the flow rate during the pulse to achieve a predetermined pulse waveform.The controller may be configured to adjust the downstream control valve to achieve a substantially constant flow rate during the pulse.

[0013] A method of pulsed gas delivery includes filling a chamber with gas to an initial pressure by closing a downstream control valve and opening an upstream valve, closing the upstream valve when the initial pressure is reached, opening the downstream control valve after closing the upstream valve to initiate a pulse of the gas flowing out of the chamber, and controlling the downstream control valve during the pulse of the gas flowing out of the chamber to deliver a predetermined amount at a predetermined time in the pulse.

[0014] A method of providing a pulse of fluid may include controlling a flow of the fluid into the chamber with an inlet valve, sensing a pressure of gas in the chamber with a pressure sensor, sensing a temperature of the gas in the chamber with a temperature sensor, and controlling a flow of fluid through a downstream control valve during the pulse of fluid.

[0015] The pressure and temperature of the gas in the chamber may be sensed and the downstream control valve may be controlled based on the sensed pressure and temperature. The downstream control valve may be closed when the predetermined volume or a predetermined time of the pulse is reached. Each step of the method may be repeated for a predetermined number of pulses under the control of a dedicated controller.

[0016] A flow rate of gas exiting the chamber may be measured and the downstream control valve may be controlled during the pulse to regulate the measured flow rate to a flow set point, and an amount of gas delivered from the chamber during the pulse may be calculated and the downstream control valve may be controlled to deliver a predetermined amount of gas during the predetermined pulse time.

[0017] The flow rate may be adjusted during the pulse to achieve the predetermined pulse waveform. The downstream control valve may be adjusted during the pulse to achieve a substantially constant flow rate during the pulse.

[0018] The flow of fluid through the downstream control valve may be controlled based on feedback from the pressure and the temperature sensed during the pulse. A flow rate of the gas out of the chamber may be calculated and the downstream control valve may be controlled to adjust the flow rate of the gas out of the chamber based on the calculated flow rate and a target flow set point.

[0019] The method may comprise calculating an amount of the gas to be delivered from the chamber and controlling the downstream control valve to deliver a predetermined amount of gas during the gas pulse. [Brief description of the drawings]

[0020] The foregoing will become apparent from the following more particular description of exemplary embodiments in light of the accompanying drawings, in which like reference characters denote the same parts throughout the different drawings, and in which the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the embodiments. [Figure 1] FIG. 1 illustrates a pressure-based pulse supply system in the prior art. [Diagram 2] 2 is a diagram showing the operation of the pressure-type pulse gas supply system of FIG. 1. [Diagram 3] FIG. 1 is a diagram showing a prior art pulse mass flow controller using a temperature sensor. [Figure 4] FIG. 1 is a diagram showing a conventional pulse mass flow controller using a pressure-type flow sensor. [Diagram 5] FIG. 1 illustrates a pulse delivery system according to an embodiment of the present invention. [Figure 6] FIG. 6 is a diagram illustrating the operation of the system of FIG. 5. [Figure 7] 6 is a flowchart showing the operation of the pulsed gas supply system of FIG. 5. [Figure 8] 6 is a flow chart illustrating a pulse delivery process of the system of FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Exemplary embodiments are described below.

[0022] A gas control system is provided for pulsing specific masses of gas, such as process gases in semiconductor manufacturing processes or chemical processes.

[0023] The mass of gas may be specified as the desired number of moles of fluid to be delivered in a fluid pulse delivered to the process chamber. The term "mole" is a unit of measure for the amount of a substance in the International System of Units (SI), with the unit symbol mol. A "mole" is defined as an amount or sample of a substance that contains the same number of constituent particles (e.g., atoms, molecules, ions, electrons, or photons) as there are atoms in 12 grams of Carbon-12 (12C, which by definition is an isotope of carbon with a standard atomic weight of 12). This number is expressed by the Avogadro constant, approximately 6.022140857×10^23 mol-1 (022140857×10 23 The mole is a convenient and widely used way of expressing the amounts of reactants and products in chemical reactions. Molar volume (symbol V m ) is the volume occupied by one mole of a substance at a given temperature and pressure. Molar volume is equal to the molar mass (M) divided by the mass density (ρ).

[0024] FIG. 1 illustrates a conventional pulsed gas supply apparatus 102 using pressure-based pulsed gas supply (see, for example, U.S. Patent No. 7,628,860, issued Dec. 8, 2009, by Shajii et al., the entire contents of which are incorporated herein by reference). As shown in FIG. 1, pressure-based molar metering techniques utilize the response of pressure (P) versus time (t) for a gas introduced into a known volume. The apparatus 102 includes a chamber 104 having a known volume (V), an inlet valve 106 ("Vin") located upstream of the chamber 104, and an outlet valve 107 ("Vout") located downstream of the chamber 104. Also provided are a pressure sensor 108 located in the chamber 104, and a temperature sensor 110 for measuring the temperature of the walls of the chamber as an indication of the gas temperature within the chamber.

[0025] First, the device 102 is filled to a predetermined pressure from the gas supply 105 by closing the downstream valve 107 and opening the upstream valve 106, which results in a gas flow (Q i ) enters the device and fills the chamber (volume) 104, causing a change in pressure. At time t1 and pressure P1, the upstream valve 106 is closed ("Vin CLOSE"). This allows the process time (t2-t1) for the gas in chamber 104 to stabilize at the set point. During this time, pressure and temperature measurements are taken by pressure sensor 108 and temperature sensor 110. When the downstream valve 107 opens ("Vout OPEN" at time t2 in FIG. 2), a gas flow (Q0) exits the device 102, providing a pulse of gas from the device to the process tool 111, until the valve 107 is closed again at a predetermined pressure P2 ("Vout CLOSE" at time t3).

[0026] 2 can be implemented by a program on the dedicated controller 112 of the device 102 that executes the supply content instructed by the host controller 114. The pulse supply is initiated by a trigger signal, such as a control signal, from the host controller 114. The number of moles of gas supplied can be estimated based on the principle of the ideal gas law, Δn=(ΔP×V) / (R×T).

[0027] A multi-channel pulsed gas supply in which the flow rate is determined based on the pressure drop in a supply chamber is described in U.S. Pat. No. 9,348,339 to Ding et al., issued May 24, 2016, the entire contents of which are incorporated herein by reference.

[0028] The approach shown in Figures 1 and 2 has several limitations. The fill pressure must be tightly controlled. The accuracy and repeatability of the pulse delivery depends on the speed and reliability of the downstream closing valve. A shutoff valve with a fast response time is required. However, if the valve ages, adaptive adjustments may have to be made, which adds complexity, or the valve may have to be replaced, which typically requires a process interruption. Often the pulse shape (e.g., pulse width) is not as desired, or the pulse does not match the desired square wave well enough. Furthermore, it is time consuming because a certain amount of gas needs to be filled into the chamber 104. The gas filling and stabilization times before each pulse limit the fast gas delivery cycle time.

[0029] However, pressure-based molar metering techniques have the advantage that they can be applied without knowledge of the particular gas or gas mixture being measured. The gas delivery rate derived by mass balance and application of the ideal gas law to the chamber volume is gas independent, but depends on three state variables that characterize the behavior of the gas being measured: pressure (P), temperature (T), and volume (V).

[0030] FIG. 3 shows a conventional pulse delivery system based on a mass flow controller. In a typical mass flow controller, a proportional control valve 304 opens at a predefined set point of flow detected by a flow sensor 306, which may be, for example, a thermal flow sensor. Feedback from a dedicated controller 308 is used to control the opening of the proportional control valve 304 to match the set point. A pulse delivery system uses a valve 304 that can open and close quickly. The host controller 114 sends the desired set point and pulses to the dedicated controller 308 in time. It may also send pulse ON / OFF times for a pulse train that is initiated by a trigger from the host controller.

[0031] Disadvantages of thermal pulsed MFCs such as the one shown in Figure 3 include limited high temperature operation and potential long-term drift issues.

[0032] FIG. 4 shows a conventional pressure-based MFC 402 system for pulsing gas. The host controller 114 communicates with the MFC 402 and provides the dedicated controller 404 with information regarding the desired pulsing, such as the pulse molar set point, pulse ON time, pulse OFF time, and pulse repetition rate. To initiate a pulsing cycle, the host controller 114 sends a trigger signal to the dedicated controller 404. The MFC 402 includes a control valve 406 (e.g., a proportional control valve) for controlling the flow of fluid from a gas source into a flow path 408. The controller 404 of the MFC 402 is configured to control the flow of fluid through the control valve 406 to control the fluid delivered to the process chamber during the fluid pulse. The controller 404 controls the flow of fluid through the control valve 406 based on feedback from a flow sensor 410 that is provided to measure the flow rate (Q) in the flow path. The flow sensor 410 includes a flow restrictor 412 in the flow path 410, and includes an upstream pressure sensor 414 and a downstream pressure sensor 416. The control valve 406 is upstream of the restrictor 412 and each pressure sensor. The flow control may also be responsive to a temperature sensor 418.

[0033] The pulse gas supply amount in the apparatus in FIGS.

[0034]

number

[0035] Here, Δn is the number of moles of the supply gas, Q is the flow rate measured by the flow sensor, t1 is the start time of the pulse, and t2 is the end time of the pulse.

[0036] Pulsed MFC gas delivery is further described in WO 2012 / 116281 by Junhua Ding et al., entitled "System for and Method of Fast Pulse Gas Delivery," the entire contents of which are incorporated herein by reference.

[0037] An improvement to the pressure-based MFC of Figure 4 is shown in pending U.S. Patent Application No. 15 / 887,447, filed February 2, 2018, and corresponding PCT Application PCT / US2019 / 015356, filed January 28, 2019. In this system, a shutoff valve is provided at the output of the MFC to initiate and terminate a pulse faster than would be possible with just a proportional control valve. The controller can be configured to control the flow through the control valve and switching of the shutoff valve based on an estimated number of moles of fluid to be delivered.

[0038] FIG. 5 illustrates an improvement to a pressure-based rate-of-decay pulsed gas delivery system in accordance with the present invention. Chamber 504 has a known volume V. The pressure of the fluid in chamber 504 is sensed by pressure sensor 506, and the gas temperature is sensed by temperature sensor 508. Both the sensed pressure and temperature are sent to a dedicated controller 514, which communicates with host controller 114. Controller 514 controls the operation of upstream valve 510 and downstream valve 512. Upstream valve 510 can be a traditional on / off shutoff valve, which fills volume 504, but can also be a control valve. Importantly, downstream valve 512 is not a typical on / off shutoff valve, but rather an adjustable control valve, such as a proportional control valve typically used in mass flow controllers, whose opening can be controlled in response to a control signal.

[0039] The operation of the pulsed gas delivery system of Figure 5 is illustrated in Figure 6, and a control flow chart is shown in Figures 7 and 8. Figure 6 illustrates the formation of a controlled flow pulse 602 followed by a preceding pulse 604.

[0040] In 702, the host controller transmits parameters to configure the controller 514. Two configurations are presented here. In "time-based delivery", the host controller transmits the following parameters to the system: flow set point (Qsp), pulse on time (Ton), pulse off time (Toff), and / or pulse number (N). In "molar-based delivery", the host controller transmits the following parameters to the system: pulse delivery molar quantity set point (Msp), pulse on time (Ton), pulse off time (Toff), and / or pulse repetition number (N). In this molar-based delivery, assuming that the pulse waveform is rectangular, the target flow rate set point Qsp can be calculated from the molar quantity set point (Msp) as follows:

[0041] Qsp = k1 × Msp / Ton (2)

[0042] where k1 is a conversion constant.

[0043] In either method, the process proceeds as follows: downstream valve 512 is closed at 704, the upstream valve is opened at 706, and the chamber 504 is filled to a predetermined pressure measured at 708. The upstream valve is then closed at 710. At 712, the host controller sends a trigger signal to dedicated controller 514 to begin the pulsed gas delivery process of FIG.

[0044] At 802, the pulse ON timer in the controller 514 is reset. At 804, at time t0 when the pulse 604 in Figure 6 begins, the downstream valve 512 is opened and a feedback control loop is used to control the downstream valve opening, thereby regulating the flow to the target flow set point (Qsp) based on the pulse quantity set point and pulse ON time such that the pulse delivery meets the desired quantity set point and pulse ON time. The measured flow rate is calculated based on the decay rate approach for the delivery chamber volume as follows:

[0045] Q = -(V × T stp / P stp )×(d(P / T) / dt)

[0046] where Q is the gas flow through the valve 512, V is the volume of the chamber 504, and T stp is the standard temperature constant, P stp is the standard pressure constant, P is the pressure measured by sensor 506, and T is the temperature of the gas measured by temperature sensor 508.

[0047] In a time-based delivery method, once the pulse ON time (Ton) is reached, the controller 514 closes the downstream valve 512 at 704, terminating the delivery of one pulse.

[0048] In a molar based delivery method, an additional feedback control loop is provided at 804. The amount of gas delivered during a delivery pulse may be calculated using the following formula:

[0049] Δn(t)=V×(P t0 -P t ) / (R×T)

[0050] where Δn(t) is the number of moles of gas passing through valve 512 versus time, and P t0 is the initial filling pressure when the downstream valve is first opened, and P t is the final pressure when the downstream valve is closed at t1, T is the gas temperature, and R is the ideal gas constant.

[0051] The system may estimate the total amount of gas in moles to be delivered when the pulse ON time is reached.

[0052] The system may adjust the flow set point Qsp if the estimate does not meet the molar set point Msp. In other words, a second feedback loop is used to adjust the flow set point Qsp. The first feedback control loop is used to control the flow rate to the flow set point at all times in both time-based and molar-based delivery. In molar-based delivery, the controller 514 automatically adjusts the flow set point Qsp during pulse delivery, thereby adjusting the control valve 512 based on feedback of the calculated number of moles delivered during a pulse to ensure that the desired number of moles is delivered exactly within the target pulse ON time for each pulse. In molar-based delivery, the two feedback control loops can meet both the molar set point (Msp) and pulse ON time (Ton) requirements.

[0053] The controller can also adjust the opening of the control valve 512 based on feedback from the previous pulse delivery.

[0054] At 806, at time t1, the downstream control valve 512 is closed when the pulse ON time has elapsed or when the amount has been reached. Either way, a pulse OFF timer is reset at 808. At 810, the upstream valve is opened to fill the chamber volume to a predetermined pressure at time t1. Although FIG. 6 shows the upstream valve opening as soon as the downstream valve closes, a suitable delay may be provided. At 812, once the predetermined pressure is reached at t2, the upstream valve is closed. At 814, the system waits for the pulse OFF time while the gas in the chamber stabilizes. Due to the control provided by the control valve 512, the starting pressure P after stabilization is reached. t0 is not as critical as traditional decay rate approaches. As a result, the pulse off time may be relatively short. If, at 816, the number of pulses delivered is less than the pulse number set point, steps 802-814 are repeated.

[0055] The disclosed system offers several advantages: It provides accurate molar delivery by controlling the flow rate during the pulse time; It allows for control of the pulse shape; It allows high temperature operation; It allows for fast filling by fully opening the upstream valve; It allows for the use of the ideal gas equation since the flow rate and delivery are gas independent (although non-ideal gas equations can also be used); It allows for the initial pressure P to be calculated since the amount of molar delivered can be calculated during the pulse and the flow can be controlled; t0 does not need to be very accurate. The system can be used in many high speed pulsing applications such as ALD / ALE and TSV processes.

[0056] Although exemplary embodiments have been shown and described in detail, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the embodiments encompassed by the appended claims. The present invention includes the following embodiments. [Aspect 1] a chamber having a volume; a pressure sensor configured to detect a pressure of gas within the chamber; a temperature sensor configured to detect a temperature of the gas within the chamber; an upstream valve configured to control the flow of gas into the chamber; a downstream control valve configured to control the flow of the gas out of the chamber; a controller configured to control the upstream valve and the downstream control valve to fill the chamber to an initial pressure, and then control flow of the gas out of the chamber through the downstream control valve during a gas pulse to control the time and amount of the gas pulse based on the detected pressure and temperature. [Aspect 2] 2. The pulsed gas supply system of claim 1, wherein the controller is configured to control the downstream control valve in a feedback loop to adjust the flow out of the system during the pulse based on pressure and temperature detected during the pulse. [Aspect 3] In the pulsed gas supply system described in aspect 1, the controller is further configured to calculate a flow rate of the gas flowing out of the chamber and control the downstream control valve to adjust the flow rate of the gas flowing out of the chamber based on the calculated flow rate and a target flow set point. [Aspect 4] 4. The pressure-type pulsed gas supply system according to claim 3, wherein the controller is configured to calculate the flow rate Q based on the following function: Q = -(V × T stp / P stp )×(d(P / T) / dt) where V represents the volume of the chamber and T stp stands for standard temperature, and P stprepresents standard pressure, P represents the pressure of the gas in the chamber, and T represents the temperature of the gas in the chamber. [Aspect 5] A pulsed gas supply system as described in aspect 3, wherein the controller is further configured to calculate the amount of gas supplied from the chamber and control the downstream control valve to supply a predetermined amount of gas during the gas pulse. [Aspect 6] A pulsed gas supply system as described in aspect 5, wherein the controller is configured to calculate the amount of gas supplied from the chamber based on the volume of the chamber, the initial pressure of the gas in the chamber detected by the pressure sensor at the start of the pulse, the pressure of the gas in the chamber detected by the pressure sensor during the pulse, and the temperature of the gas detected by the temperature sensor during the pulse. [Aspect 7] 7. The pulsed gas supply system of claim 6, wherein the controller is configured to calculate the amount Δn(t) of the gas supplied from the chamber at time t during the pulse using the following function: Δn(t)=V×(P t0 -P t ) / (R×T t ) where V represents the volume of the chamber, and P t0 represents the pressure of the gas in the chamber at the start of the pulse, P t represents the pressure of the gas in the chamber at the time t during the pulse, and T t represents the temperature of the gas at the time t during the pulse. [Aspect 8] A pulsed gas supply system as described in aspect 1, wherein the controller is further configured to calculate the amount of gas supplied from the chamber and control the downstream control valve to supply a predetermined amount of gas during the gas pulse. [Aspect 9] A pulsed gas supply system as described in aspect 8, wherein the controller is configured to calculate the amount of gas supplied from the chamber based on the volume of the chamber, the initial pressure of the gas in the chamber detected by the pressure sensor at the start of the pulse, the pressure of the gas in the chamber detected by the pressure sensor during the pulse, and the temperature of the gas detected by the temperature sensor during the pulse. [Aspect 10] 10. The pulsed gas supply system of claim 9, wherein the controller is configured to calculate the amount Δn(t) of the gas supplied from the chamber at time t during the pulse using the following function: Δn(t)=V×(P t0 -P t ) / (R×T t ) where V represents the volume of the chamber, and P t0 represents the pressure of the gas in the chamber at the start of the pulse, P t represents the pressure of the gas in the chamber at the time t during the pulse, and T t represents the temperature of the gas at the time t during the pulse. [Aspect 11] 2. The pulsed gas delivery system of claim 1, wherein the controller is configured to adjust the flow rate during the pulse to achieve a predetermined pulse waveform. [Aspect 12] 2. The pulsed gas supply system of claim 1, wherein the controller is configured to adjust the downstream control valve to achieve a substantially constant flow rate during the pulse. [Aspect 13] (i) filling the chamber with gas to an initial pressure by closing the downstream control valve and opening the upstream valve; (ii) closing the upstream valve when the initial pressure is reached; and (iii) once the initial pressure is reached and the upstream valve is closed, opening the downstream control valve to initiate the pulse of gas flowing out of the chamber; (iv) controlling the downstream control valve during the pulse of gas exiting the chamber to deliver a predetermined amount at a predetermined time in the pulse. [Aspect 14] A pulsed gas supply method as described in aspect 13, further comprising detecting the pressure and temperature of the gas in the chamber during the pulse and controlling the downstream control valve based on the detected pressure and temperature. [Aspect 15] 14. The pulsed gas supply method according to claim 13, further comprising controlling the downstream control valve to close when the predetermined amount of gas is reached. [Aspect 16] The pulsed gas supply method according to aspect 13, further comprising controlling the downstream control valve to close when a desired pulse ON time is reached. [Aspect 17] A pulsed gas supply method according to aspect 13, further comprising repeating (i) to (iv) every certain number of pulses under the control of a dedicated controller. [Aspect 18] A pulsed gas supply method as described in aspect 13, further comprising measuring a flow rate of gas flowing out of the chamber and controlling the downstream control valve during the pulse to adjust the measured flow rate to a target flow set point. [Aspect 19] A pulsed gas supply method according to aspect 13, further comprising: calculating an amount of gas supplied from the chamber during the pulse; and controlling the downstream control valve to supply a predetermined amount of gas during a predetermined pulse time. [Aspect 20] A pulsed gas supply method according to aspect 13, further comprising adjusting a flow rate during the pulse to achieve a predetermined pulse waveform. [Aspect 21] 14. The method of pulsed gas delivery according to claim 13, further comprising adjusting the downstream control valve during the pulse to achieve a substantially constant flow rate during the pulse. [Aspect 22] 1. A method of delivering a pulse of fluid, comprising: controlling the flow of fluid into the chamber with an inlet valve; detecting a pressure of the gas in the chamber with a pressure sensor; detecting a temperature of the gas in the chamber with a temperature sensor; and controlling a flow of fluid through a downstream control valve during the pulse of fluid. [Aspect 23] 23. The method of claim 22, wherein control of the flow of the fluid through the downstream control valve is based on feedback from the pressure and the temperature sensed during the pulse. [Aspect 24] 23. The method of claim 22, further comprising calculating a flow rate of the gas flowing out of the chamber and controlling the downstream control valve to adjust the flow rate of the gas flowing out of the chamber based on the calculated flow rate and a target flow set point. [Aspect 25] 25. The method of claim 24, further comprising calculating the flow rate Q based on the following function: Q = -(V × T stp / P stp )×(d(P / T) / dt) where V represents the volume of the chamber and T stp stands for standard temperature, and P stp represents standard pressure, P represents the pressure of the gas in the chamber, and T represents the temperature of the gas in the chamber. [Aspect 26] 23. The method of claim 22, further comprising calculating the amount of gas supplied from the chamber and controlling the downstream control valve to supply a predetermined amount of gas during the gas pulse. [Aspect 27] 23. The method of claim 22, further comprising calculating the amount of gas supplied from the chamber based on a volume of the chamber, an initial pressure of the gas in the chamber detected by the pressure sensor at the start of the pulse, the pressure of the gas in the chamber detected by the pressure sensor during the pulse, and the temperature of the gas detected by the temperature sensor during the pulse. [Aspect 28] 28. The method of claim 27, further comprising calculating the amount Δn(t) of the gas supplied from the chamber at time t during the pulse according to the following function: Δn(t)=V×(P t0 -P t ) / (R×T t ) where V represents the volume of the chamber, and P t0 represents the pressure of the gas in the chamber at the start of the pulse, P t represents the pressure of the gas in the chamber at the time t during the pulse, and T t represents the temperature of the gas at the time t during the pulse. [Aspect 29] 23. The method of claim 22, further comprising adjusting a flow rate during the pulse to achieve a predetermined pulse waveform. [Aspect 30] 23. The method of claim 22, further comprising adjusting the downstream control valve to achieve a substantially constant flow rate during the pulse.

Claims

1. a chamber having a volume; a pressure sensor configured to detect a pressure of gas within the chamber; a temperature sensor configured to detect a temperature of the gas within the chamber; an upstream valve configured to control the flow of gas into the chamber; an adjustable downstream control valve configured to control the flow rate of the gas out of the chamber; a controller configured to control the upstream valve and the downstream control valve to fill the chamber to an initial pressure and then control the flow of the gas out of the chamber through the downstream control valve during a gas pulse to control the time and amount of the gas pulse based on the detected pressure and temperature; The controller is further configured to calculate a flow rate of the gas flowing out of the chamber during the pulse using a pressure decay rate based on the detected pressure and temperature, and to control the opening of the downstream control valve to regulate the calculated flow rate to a target flow rate set point.

2. 2. The pulsed gas delivery system of claim 1, wherein the controller is configured to calculate the flow rate Q based on the following function: Q=-(V×T ｓｔｐ / P ｓｔｐ )×(d(P / T) / dt) where V represents the volume of the chamber and T ｓｔｐ represents the standard temperature, and P ｓｔｐ represents standard pressure, P represents the pressure of the gas in the chamber, and T represents the temperature of the gas in the chamber.

3. 10. The pulsed gas delivery system of claim 1, wherein the controller is configured to adjust the flow rate during the pulse to achieve a predetermined pulse waveform.

4. 2. The pulsed gas delivery system of claim 1, wherein the controller is configured to adjust the downstream control valve to achieve a constant flow rate during the pulse.

5. (i) filling the chamber with gas to an initial pressure by closing an adjustable downstream control valve and opening an upstream valve; (ii) closing the upstream valve when the initial pressure is reached; and (iii) once the initial pressure is reached and the upstream valve is closed, opening the downstream control valve to initiate the pulse of gas flowing out of the chamber; (iv) controlling the downstream control valve during the pulse of gas exiting the chamber to provide a predetermined amount at a predetermined time in the pulse; 11. The method of claim 10, further comprising: sensing a pressure and temperature of the gas in the chamber during the pulse; calculating a flow rate of the gas out of the chamber using a pressure decay rate based on the sensed pressure and temperature; and controlling an aperture of the downstream control valve to regulate the calculated flow rate to a target flow rate set point.

6. 6. The method of claim 5, further comprising controlling the downstream control valve to close when the predetermined amount of gas is reached.

7. 6. The method of claim 5, further comprising controlling the downstream control valve to close when a desired pulse ON time is reached.

8. 6. The pulsed gas supply method according to claim 5, further comprising repeating (i) to (iv) every certain number of pulses under the control of a dedicated controller.

9. 6. The method of claim 5, further comprising adjusting a flow rate during the pulse to achieve a predetermined pulse waveform.

10. 6. The method of claim 5, further comprising adjusting the downstream control valve during the pulse to achieve a constant flow rate during the pulse.

11. 6. The pulse gas supply method according to claim 5, further comprising: calculating the flow rate Q based on the following function: Q=-(V×T ｓｔｐ / P ｓｔｐ )×(d(P / T) / dt) where V represents the volume of the chamber and T ｓｔｐ represents the standard temperature, and P ｓｔｐ represents standard pressure, P represents the pressure of the gas in the chamber, and T represents the temperature of the gas in the chamber.

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