Material supply system

Abstract

The present invention relates to a gas supply and distribution system and method of operation thereof, the system comprising a first online vessel and a first back-up vessel, wherein the system is for dispensing gas at a preset gas flow rate; a sensor in communication with a controller to sense a predetermined end point of the first online vessel, thereby causing the controller to initiate automatic switching from the first online vessel to the first back-up vessel in an array in which the gas is contained for subsequent dispensing of the gas from the first back-up vessel; wherein the controller initiates gas flow from the first back-up vessel after sensing the predetermined end point, thereby the first back-up vessel becomes a second online vessel dispensing gas concurrently with the first online vessel for a period of time before terminating gas flow from the first online vessel.

Description

[0001] Cross Reference to Related Applications

[0002] This patent application claims priority to U.S. Provisional Patent Application 63 / 080,481 filed September 18, 2020. BACKGROUND

[0003] The present invention relates generally to any material (solid, liquid or gas) stored in a dispensing vessel and supplied as a gas from the dispensing vessel, and in particular to a multi-vessel array requiring continuous switching to provide a continuous supply of gas to one or more gas-consuming process units. In one particular aspect, the invention can relate to a gas cabinet or bulk supply system comprising a plurality of storage and dispensing vessels for providing gases to semiconductor manufacturing tools in a semiconductor manufacturing facility, and to an automated exchange system for vessel exchange to maintain continuity of gas dispensing.

[0004] Materials are provided to many manufacturing processes, particularly in semiconductor manufacturing. Some materials are gases, liquids or solids, which are stored in vessels and dispensed as a gas to semiconductor manufacturing equipment or tools, such as deposition chambers, etch chambers and ion implanters. Typically, process materials are stored in gas cylinders, but can also be stored in any storage vessel, such as a Y-type gas cylinder, ampoule, ISO container or tank. The materials can be stored in the vessels at elevated or atmospheric pressure.

[0005] In one application in semiconductor manufacturing, the aforementioned type of gas storage and dispensing vessels are often arranged in a gas cabinet, where multiple vessels are manifolded to appropriate flow lines or manifolds, including, for example, tubing, valves, flow restriction orifice elements, flow regulators, mass flow controllers, purge loops, instrumentation and monitoring equipment, etc. Such flow lines can be associated with an automated exchange system that allows the storage and dispensing vessels to be taken offline when the gas is depleted or otherwise approaching an empty condition, such as by appropriate exchange of a valve from open to closed (or from open to closed), so that the depleted or otherwise substantially exhausted vessel is isolated from the gas feed relationship of the flow line to facilitate replacement of the vessel. Subsequently or concurrently, a full gas storage and dispensing vessel is exchanged online, such as by appropriate exchange of a flow control valve in the manifold from closed to open (or from closed to open), to place this new vessel in gas feed relationship with the flow line. The isolated, exhausted vessel can then be decoupled from the flow line and removed from the gas cabinet to enable installation of the full vessel to be used when the previously exchanged online vessel has been depleted of gas during subsequent operations.

[0006] The gas distribution hardware and electronics can be programmably configured to effectuate an automatic container changeover at a pre-set pressure at which the first container reaches an end point at which it can no longer maintain the pre-set pressure. To this end, the gas distribution hardware and electronics can be constructed and arranged for automatic or manual evacuation, purging, and leak detection of the gas flow path. A programmable logic controller (PLC) can be used in the system to monitor valve status, system pressure, container weight, and temperature, and to provide pre-programmed sequences that control the following functions: container change, initiation of gas flow, automatic exchange of containers, purge gas control, process / purge gas evacuation, assurance of process gas flow prior to shut down, and temperature control of container heaters (e.g., heating blankets).

[0007] Thus, for example, a standard gas cylinder or a container of the type based on a sorbent and / or equipped with an internal pressure regulator can be arranged in a multi-container array in which an automatic exchange of containers from a depleted container to a full container occurs when an end point of the active (on-line) container is reached. The end point can be determined in various ways - it can be determined by a drop in the dispensing gas pressure and / or flow rate that indicates depletion of the container contents, or it can be determined by a loss of weight of the container that accompanies the continuous dispensing of gas, or by a cumulative volume flow of the dispensing gas, or by a predetermined operating time, or in other suitable ways.

[0008] Regardless of the manner or mode of determining the end point of the container, the automatic exchange from a depleted container to a full container involves a large drop in pressure and a perturbation of the gas flow. This pressure drop during the changeover can cause the pressure to drop below the set point (pre-set pressure) limit that triggers a response. This pressure perturbation can cause an alarm to be initiated, and under extreme pressure change conditions, safety monitoring elements of the gas delivery system can cause a shut down of the gas flow and an undesirable stoppage of the downstream gas consumption process. Alternatively, if the process control of the system is calibrated to allow such a large pressure drop, the system can react sluggishly to the actual problem that caused the large pressure drop and needs to be addressed.

[0009] In Figure 1 the pressure variation during an exchange in a typical prior art gas delivery system, such as the Versum Materials Gas Delivery Cabinet. Figure 1 The significant drop in pressure between cylinder exchanges is shown. The variation in pressure is variable and can have unpredictable effects on the gas flow, for example, to the deposition equipment and the resulting film produced therein and thereby. The effects on the gas flow will have a negative impact on the variability of the process.

[0010] Accordingly, it would be a progress in the art to provide an automatic changeover apparatus and method for a gas delivery system (for dispensing a gas) that minimizes pressure disturbances attendant to container changeover. SUMMARY

[0011] The present invention relates generally to material storage and dispensing containers, and in particular to a multiple container array that requires continuous switching in the array from one or more depleted containers to one or more containers containing fresh material in order to provide a continuous supply of gas to a gas-consuming process.

[0012] The present invention provides a gas supply and dispensing system, the system comprising an array of at least two gas storage and dispensing containers arranged for sequential inline dispensing, involving switching in the array from one or more first inline containers to one or more first reserve containers, the system for dispensing gas at a preset gas flow rate; at least one controller; and one or more sensors in communication with the controller, wherein the one or more sensors sense one or more predetermined end points of the one or more first inline containers, thereby causing the controller to initiate automatic switching in the array having gas therein from the one or more first inline containers to the one or more first reserve containers for subsequent dispensing of gas from the one or more first reserve containers; wherein the controller initiates gas flow from the one or more first reserve containers after sensing the one or more predetermined end points, whereby the one or more first reserve containers become one or more second inline containers that dispense gas concurrently with the one or more first inline containers for a period of time before termination of gas flow from the one or more first inline containers.

[0013] The present invention also provides a method of substantially reducing pressure variations of a gas dispensed from a gas supply and dispensing system, the gas supply and dispensing system comprising an array of at least two gas storage and dispensing containers arranged for sequential inline dispensing, involving switching in the array from one or more first inline containers to one or more first reserve containers, the system for dispensing gas at a preset gas flow rate, the method comprising the steps of: supplying process gas from the one or more first inline containers; depleting the one or more first inline containers of process gas; sensing one or more predetermined end points of the one or more first inline containers; opening one or more valves to initiate supply of process gas from the one or more first reserve containers, the one or more first reserve containers thereby becoming one or more second inline containers that dispense process gas concurrently with the one or more first inline containers; increasing the flow of the process gas from the one or more second inline containers above the preset flow rate; detecting the increased flow rate from one or more second inline containers;

[0014] returning a gas flow from one or more second online vessels to a preset flow rate; and closing one or more valves to isolate the one or more first online vessels from the system.

[0015] The present invention provides the benefit of reducing large pressure changes due to gas supply switching from one or more vessels in a gas delivery system to another one or more vessels.

[0016] Other aspects, features, and embodiments of the present invention will become more fully apparent in light of the following disclosure and appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a plot of pressure versus time measured during a switching process in a prior art gas delivery system.

[0018] Figure 2 is an elevational view of a gas delivery system having vessel switching capability according to one embodiment of the present invention.

[0019] Figure 3 is a schematic view of a flow manifold of a gas delivery system according to one embodiment of the present invention.

[0020] Figure 4 is a process flow diagram involving steps of an automatic switching sequence according to one embodiment of the present invention.

[0021] Figure 5 is a plot of pressure versus time measured during a switching process in a gas delivery system according to the present invention. DETAILED DESCRIPTION

[0022] The present invention provides an automatic switching apparatus and method for a gas delivery or distribution system for a multi-vessel array. Delivery of gas can be from two gas supply vessels to a single outlet connection, as shown in the embodiments of Figure 2 and 3 The system is configured and arranged to control automatic switching from an online gas supply vessel to a backup or spare gas supply vessel when the online gas supply vessel is depleted, as shown. After replacement of the depleted gas vessel, the system can be reset or automatically reset to automatically return to the now replenished or replaced spare gas vessel. In alternative embodiments, more than two vessels can be connected to a single outlet, more than one vessel can be online and / or more than one vessel can be spare, and each vessel can be individually manifolded to the outlet and individually controlled. In this embodiment, typically, the system includes the same number of vessels in spare as online vessels; however, in the system, any number of vessels can be online and any number of vessels can be spare.

[0023] Note that the terms "deliver" and "dispense" are used interchangeably herein, and the terms "active" and "on-line" are also used interchangeably herein. In addition, while the term "swap" will be used, the swapping can not be limited to just back and forth between one or more on-line and one or more reserve containers, meaning that there can be any number of groups of one or more on-line containers and any number of groups of one or more reserve containers. For example, the array of containers can include two or more individually controlled containers or groups of two or more containers (each typically having a separate manifold with at least one flow regulator, at least one valve, and at least one sensor) that are on-line and only one container or group of one or more containers that are in reserve, or vice versa, i.e., the array of containers can include two or more individually controlled containers or groups of two or more containers (each typically having a separate manifold with at least one flow regulator, at least one valve, and at least one sensor) that are in reserve and only one container or group of one or more containers that are on-line. The term "end point" or "predetermined end point" is used to describe a sensed set point that triggers the system to begin swapping. It should be understood that, for example, for some embodiments, the predetermined end point will likely be a value in the case where the gas pressure is greater than the lowest possible value (i.e., it is not the actual end point), but substantially less than the desired preset set point for the gas pressure. The term "depleted" is a relative term and does not necessarily mean completely empty. The preset gas flow rate, as well as other values measured or sensed, can change over time due to changing process gas requirements for the system or other reasons. Open language, such as "comprising" and "having," is used in the specification and claims including partial closed and closed transitional language: "consisting essentially of and "consisting of," and therefore, the language can be replaced with "comprising" wherever it appears. Similarly, any list "selected from the group of" also includes "consisting of a group of," and can be replaced accordingly.

[0024] The present invention is based on the discovery that by providing for one or more vessels on-line and one or more vessels on standby to provide gas simultaneously until one or more of the following settings are met: a set point pressure as measured by one or more pressure sensors in the system is reached (typically below a desired preset gas flow rate), or a measured time period has elapsed, or a set flow rate is reached in an automatic switching system, or the weight of the on-line gas cylinder has dropped below a set point weight, or a high or low temperature set point different from a preset temperature has been reached, the adverse pressure effects of the exchange of material storage and dispensing vessels in a multiple vessel array can be eliminated. Once one or more of these criteria are met, the on-line one or more vessels are shut down and the previously standby (new supply) one or more vessels supply process gas. With the present invention, the pressure drop caused by shutting down the on-line one or more vessels and bringing the standby one or more vessels on-line is substantially or completely eliminated.

[0025] Figure 2 is a front view of one embodiment of a gas delivery system 100 incorporating the vessel exchange capability of one embodiment of the present invention.

[0026] In one embodiment, the gas delivery system 100 can include a main cabinet 12 as the main housing and an electronics housing 26, where the main cabinet and electronics housing are bolted together to form an integrated gas delivery system. The gas supply manifold and gas supply vessels can be housed within the main cabinet 12, which can be constructed of, for example, 12 gauge cold rolled steel. As shown, the main cabinet 12 features a left side door 14 with a latch 18 and a viewing window 22, and a right side door 16 with a latch 20 and a viewing window 24. As shown, the electronics housing 26 with a screen interface 30 and on / off button 28 is mounted on top of the main cabinet 12. The windows 22, 24 can be fire rated safety glass windows to allow visual inspection of the condition of the manifold before opening the doors. In alternative embodiments, the gas delivery system can be remotely controlled and / or the removal of the gas cylinders can be performed by a robot, and thus the gas delivery system can not have a touch screen, buttons, or even a metal cabinet as shown. In alternative embodiments, the electronics, such as the controller and all associated wiring, can be located within the main cabinet, if desired. In other embodiments, the main cabinet and electronics housing can be optional and / or replaced with, for example, a valve manifold box or valve manifold panel (which does not house one or more vessels) and / or a separate controller located away from the manifold and one or more vessels. Figure 1

[0027] ​As shown, the electronics enclosure 26 includes a programmable logic controller (PLC) for controlling the integrated gas delivery system through a touch screen interface 30, communication between the PLC unit and the touch screen being achieved through a serial port connection on the PLC unit. The screen has a touch sensitive grid corresponding to text and graphics and communicates instructions to the PLC unit. The touch screen displays user menus, operational and informational screens and security barriers to facilitate authorized access to the system only.

[0028] A programmable logic controller (PLC) can be used in the system for monitoring valve status, system pressure, container weight and temperature, other sensors, and for providing preprogrammed sequences for controlling the following functions: container change, initiation of gas flow, automatic exchange of containers, optional purge gas control, optional process / purge gas evacuation, assurance of process gas flow prior to shutdown, and optional temperature control of container heaters such as heating blankets. In alternative embodiments, the gas delivery system of the present invention can be controlled by a general master controller and / or remote controller for semiconductor manufacturing. Thus, it should be understood that the controller for the delivery system of the present invention can include any type of controller that is based on programmed algorithms with preset variables or operating ranges, and set points that trigger actions, as well as receive inputs from sensors in the delivery system including one or more of pressure sensors, valve positions, timers, flow controllers, scales, thermocouples or other, to open and close valves and sound alarms, etc.

[0029] In the embodiment shown, the main cabinet 12 contains a pair of gas storage and dispensing containers, and a manifold connected to each container; the manifold thereof includes tubing, valves, etc. for gas flow, purge, and venting.

[0030] The gas supply container, sometimes referred to hereinafter as a cylinder, but not limited to a cylinder, can be of any suitable type. In alternative embodiments, the container can be one or more Y-type cylinders, ampoules, ISO containers, or tanks. The material can be stored in the container at elevated or sub-atmospheric pressure. The gas supply container can store the material at a pressure above atmospheric pressure, or can store the material at a pressure below atmospheric pressure, for example, in the case of a container containing a solid phase physical adsorbent, where gas adsorption is held on the solid phase physical adsorbent. Solid phase physical adsorbents include, for example, molecular sieves, activated carbon, silica, alumina, adsorptive clays, large mesh polymers, metal organic frameworks (MOFs), etc. It should be understood that the gas supply container can be of any other suitable type in which the material is held for dispensing gas from the container. The gas supply container can contain the process material in solid phase, liquid phase, or gas, compressed gas, or supercritical fluid form. The vapor pressure of the contents can vary between 0 Torr and 3000 psig, or even more.

[0031] Figure 3 isFigure 2 A schematic view of the flow circuit or manifold 80 of the gas delivery system 100 of FIG. 1, including left gas storage and distribution vessel 70A and right gas storage and distribution vessel 70B, interconnected with a flow circuit including manifold gas flow lines 58, 58A, 58B, 60, 60A, 60B, 62, 62A, and 62B. The A side (left side as shown) of the manifold 80 of the system includes piping and gas cylinders labeled with numbers having suffixes A, a, or aa. The A side portion of the manifold 80 also includes at least one valve, at least one control valve, and at least one pressure sensor in the piping, more preferably at least two valves, at least one control valve, and at least one pressure sensor in the piping. The B side portion of the manifold 80 of the system includes piping and gas cylinders labeled with numbers having suffixes B, b, or bb. The B side also includes at least one valve, at least one control valve, and at least one pressure sensor in the piping, more preferably at least two valves, at least one control valve, and at least one pressure sensor in the piping. In alternative embodiments, each manifold connected to a vessel can include at least one valve and at least one regulator that controls the flow of gas from that vessel in the manifold. The regulator can be a control valve in the piping and at least one pressure sensor in communication with or directly with the control valve. The term manifold can refer to all of the piping and valves in the system and can also be used to describe the portion of the piping, valves, and sensors connected to one or more online vessels (or one or more backup vessels) in the system.

[0032] Piping without a suffix is in fluid communication with both the A side and the B side (manifold and gas cylinders) of the system. The flow circuit of this configuration is designed for flow of pressurized gas that can have low internal volume and minimal dead volume. In the embodiment shown, there are four types of connections to the gas manifold flow circuit: (i) process gas outlet-manifold connections, (ii) optional purge gas-manifold connections, (iii) gas supply vessel-manifold connections, and (iv) vent-manifold connections. Each of these is discussed below.

[0033] In the process gas outlet-manifold connections, downstream gas-consuming process units (e.g., a plasma chamber) are connected to the manifold. The process gas outlet-manifold connections are connected to the A side of the manifold. The process gas outlet-manifold connections are connected to the B side of the manifold. The process gas outlet-manifold connections are connected to both the A side and the B side of the manifold. Figure 3The process gas outlet line 58 is in fluid communication with and can be directly connected to the first end of the manifold 60 (not shown). In the illustrated embodiment, the gas line 58 can be an internal line of the semiconductor fabrication plant and include an optional pressure sensor PT 50. Alternatively, the gas line 58 can be directly connected to a single piece of equipment or one or more pieces of equipment. Optionally, the gas line 58 can additionally contain manual and / or automatic valves, such as pneumatic valves (not shown). The process gas outlet line 58 also has process gas feed lines 58A and 58B engaged therewith, which are each connected to vessels 70A and 70B, respectively, and provide process gas from the vessels 70A and 70B to the process gas outlet line 58. Each process gas feed line includes at least one automatic or manual valve, and optionally one or more automatic or manual valves, one or more pressure sensors, and / or one or more regulators. In Figure 2 In the illustrated embodiment, the process gas feed line 58A includes a plurality of automatic valves V12, V13, V14, V15, and V16 in fluid communication with the vessel 70A, and the process gas feed line 58B includes a plurality of automatic valves V22, V23, V24, and V25 and V26 in fluid communication with the vessel 70B. The preferred at least two valves of the system are cylinder valves and valves that isolate a portion of the manifold (and cylinder) from the process gas outlet line. As shown for the A side of the manifold, these valves include cylinder valve V11 and valve V16 that isolates the A side of the manifold and the cylinder 70A from the process gas outlet line 58. In addition, the manifold preferably includes a control valve PCV 31 and a pressure sensor PT 32 for the A side of the manifold 80, where the pressure sensor PT 32 can be used to control the control valve PCV 31.

[0034] As Figure 3 shown, the valves V12, V13, and V15 are three-way valves that are normally closed to the purge and vent lines, meaning that they are normally open to process gas flow in the process gas feed line 58A. This is true for V22, V23, and V25 in the process gas feed line 58B. The valves need to be actuated to have them open to the purge line and vent line. However, different valves can be used in alternative embodiments, so when these valves are described as being open, it should be understood that this means open to flow in the process gas feed lines 58A, 58B or purge and vent lines as described, although open to flow in the process gas feed lines 58A, 58B is the most common. Figure 3 For the valves shown in FIG. 1, the valve position can be considered to be "closed" for those three-way valves by one of ordinary skill in the art.

[0035] In Figure 3In the illustrated embodiment, process gas feed line 58A includes pressure sensors PT30 and PT32 and regulator PCV31 in fluid communication with vessel 70A, and process gas feed line 58B includes pressure sensors PT40 and PT42 and regulator PCV41 in fluid communication with vessel 70B. Pressure sensors PT30 and PT40 monitor the pressure of vessels 70A and 70B, respectively. Also, vessels 70A and 70B each have valves V11 and V21, respectively, incorporated or connected to each vessel, so that the vessels can be isolated from the system 100 when connected to the system, and segregated when not connected to the system, such as during the process of changing an empty vessel for a full vessel. In the gas supply vessel-manifold connection, gas storage and dispensing vessel 70A engages process gas feed line 58A via releasable tubing connection 63A downstream of vessel valve V11. Gas storage and dispensing vessel 70B engages process gas feed line 58B via releasable tubing connection 63B downstream of vessel valve V21.

[0036] In the illustrated embodiment, process gas feed line 58A includes pressure sensors PT30 and PT32 and regulator PCV31 in fluid communication with vessel 70A, and process gas feed line 58B includes pressure sensors PT40 and PT42 and regulator PCV41 in fluid communication with vessel 70B. Pressure sensors PT30 and PT40 monitor the pressure of vessels 70A and 70B, respectively. Also, vessels 70A and 70B each have valves V11 and V21, respectively, incorporated or connected to each vessel, so that the vessels can be isolated from the system 100 when connected to the system, and segregated when not connected to the system, such as during the process of changing an empty vessel for a full vessel. In the gas supply vessel-manifold connection, gas storage and dispensing vessel 70A engages process gas feed line 58A via releasable tubing connection 63A downstream of vessel valve V11. Gas storage and dispensing vessel 70B engages process gas feed line 58B via releasable tubing connection 63B downstream of vessel valve V21. Figure 3 In the illustrated embodiment, process gas feed line 58A includes pressure sensors PT30 and PT32 and regulator PCV31 in fluid communication with vessel 70A, and process gas feed line 58B includes pressure sensors PT40 and PT42 and regulator PCV41 in fluid communication with vessel 70B. Pressure sensors PT30 and PT40 monitor the pressure of vessels 70A and 70B, respectively. Also, vessels 70A and 70B each have valves V11 and V21, respectively, incorporated or connected to each vessel, so that the vessels can be isolated from the system 100 when connected to the system, and segregated when not connected to the system, such as during the process of changing an empty vessel for a full vessel. In the gas supply vessel-manifold connection, gas storage and dispensing vessel 70A engages process gas feed line 58A via releasable tubing connection 63A downstream of vessel valve V11. Gas storage and dispensing vessel 70B engages process gas feed line 58B via releasable tubing connection 63B downstream of vessel valve V21.

[0037] Figure 3 In the illustrated embodiment, process gas feed line 58A includes pressure sensors PT30 and PT32 and regulator PCV31 in fluid communication with vessel 70A, and process gas feed line 58B includes pressure sensors PT40 and PT42 and regulator PCV41 in fluid communication with vessel 70B. Pressure sensors PT30 and PT40 monitor the pressure of vessels 70A and 70B, respectively. Also, vessels 70A and 70B each have valves V11 and V21, respectively, incorporated or connected to each vessel, so that the vessels can be isolated from the system 100 when connected to the system, and segregated when not connected to the system, such as during the process of changing an empty vessel for a full vessel. In the gas supply vessel-manifold connection, gas storage and dispensing vessel 70A engages process gas feed line 58A via releasable tubing connection 63A downstream of vessel valve V11. Gas storage and dispensing vessel 70B engages process gas feed line 58B via releasable tubing connection 63B downstream of vessel valve V21.

[0038] ​As shown, purge gas can be introduced into process gas feed line 58A through valve V12, and can exit process gas feed line 58A at a valve downstream of the point of introduction of the purge gas into the process gas feed line. For example, purge gas can enter process gas feed line 58A through valve V12 and exit process gas feed line 58A through valve V15 to second purge gas outlet line 60aa, which connects to purge gas outlet line 60A to vent line 60. Alternatively or additionally, purge gas can enter process gas feed line 58A through valve V12 and exit process gas feed line 58A through valve V13 to first purge gas outlet line 60a, which connects to purge gas outlet line 60A to vent line 60. The open positions of valves V12, V13, V14, and / or V15 are automatically and / or manually operated to provide the described purge gas and venting.

[0039] The purge gas source joined to purge gas feed line 62 to make up the purge gas-manifold connection can be any suitable source of purge gas, such as a supply tank of purge gas, such as ultra-high purity nitrogen gas or ultra-high purity nitrogen / helium gas mixture, or other suitable single or multi-component gas medium effective for purging flow passages of the manifold lines and associated components. So-called "house nitrogen" (i.e., nitrogen gas available from a general supply facility in a semiconductor manufacturing facility) or clean dry air (CDA) from a suitable source thereof can be used for this purpose.

[0040] Venting manifold connection will now be described. When the respective sides of the pre-conditioner or high pressure side of the process gas feed lines 58A and 58B upstream of the regulators PCV31 and PCV41 respectively are on-line, the valves V13 and V23 on the A and B sides of the manifold 80 respectively provide a venting path for the process gas. The valves V15 and V25 on the A and B sides of the manifold 80 respectively provide a venting path for the post-conditioner or low pressure side of the process gas feed lines 58A and 58B downstream of the regulators PCV31 and PCV41 respectively. By opening the valves just described and preferably also closing V16 or V26 respectively, the process gas can be directed to the lines 60a (60b) or 60aa (60bb), 60A (60B) and 60 to the vent of the process gas feed lines 58A (58B). The vent can be at atmospheric pressure or to a vacuum source (not shown), such as a Venturi vacuum generator or vacuum pump. In addition, if required or desired, the valves V14 and V24 can be used to isolate the high pressure side (upstream of the regulators PCV31 and PCV41 respectively) from the low pressure side (downstream of the regulators PCV31 and PCV41 respectively) of the process gas feed lines 58A and 58B. In an emergency situation, it can become necessary to direct the process gas in the manifold to the vent during a shutdown or just prior to purging the manifold with a purge gas (e.g. as part of a cylinder change).

[0041] Under normal operating conditions, either vessel 70A or vessel 70B supplies process gas while the opposite vessel will be in standby. If vessel 70A supplies process gas, vessel valve V11, regulator isolation valve V14, regulator PCV31 and process isolation valve V16 are all open. If vessel 70B supplies process gas, vessel valve V21, regulator isolation valve V24, regulator PCV41 and process isolation valve V26 are all open; and process isolation valve V26 is closed if vessel 70B is not supplying process gas at a minimum. Process isolation valve V26 is preferably located downstream of one or more pressure sensors PT40, PT42 and control valve PCV41 in process gas feed line 58B on the B side of the manifold 80 (and all downstream of cylinder 70B). Note that any steps or valve positions and process steps performed on the A side of the manifold after a swap are the same for the corresponding valves etc. on the B side of the manifold and vice versa. When vessel 70A is supplying, valves V12, V13 and V15 are open for flow in line 58A. When vessel 70B is supplying, valves V22, V23 and V25 are open for flow in line 58B.

[0042] The output of each of the regulators PCV31 and PCV41 is controlled based on feedback from outlet pressure sensors PT32 and PT42 located in process outlet feed lines 58A and 58B, respectively, or alternatively, by pressure sensor PT50 or a combination of pressure sensors in the process gas outlet line. At least one of PT32 and PT42 or PT50 is present in the system for this purpose. Pressure sensor PT32 controls the flow from cylinder 70A on the A side of manifold 80, and pressure sensor PT42 controls the flow from cylinder or vessel 70B on the B side of the manifold. This control is achieved through a proportional-integral-derivative controller (PID) with a user-determined set point for pressure sensor PT32, PT42 and / or PT50 as the output target. The pressure sensor measures the actual pressure in the line, which is then compared to the set point pressure and used in the control loop to control the valve opening in the regulator. The output set points of both regulators PCV31 and PCV41 are typically the same under normal supply conditions.

[0043] Operation of the gas supply system during exchange will now be described with reference to Figure 3 and 4 the drawings.

[0044] In the embodiment shown in Figure 3 and 4 , in step 1, vessel 70A and the A side manifold 80 are on-line and supplying process gas, and vessel 70B is connected to the B side of the manifold, ready to deliver gas when needed and in standby mode. The B side is isolated from the A side, while the A side is supplying gas until exchange is initiated. (The previous empty vessel or one that has been depleted to a desired extent on the B side of the manifold can have been replaced with vessel 70B containing the necessary material, preferably a full vessel, to provide process gas.) As vessel 70A is depleted or reaches one or more predetermined end points for another cylinder change (exchange initiated), in step 2, a low source notification or cylinder change signal is generated by PT30 for low pressure and / or scale 19A for low weight or other indicator that senses the predetermined end point (e.g., cumulative time of dispensing). As another alternative, the empty / predetermined end point can be determined by a decrease in the flow rate of dispensed gas as measured by a pressure sensor, a decrease in the rate of change of one or more properties of the dispensed gas (e.g., phase change, or removal of process gas from a solvent or solid adsorbent), and / or other indicators can be used to establish or detect an end of run limit (one or more predetermined end points) related to gas dispensing from the on-line gas supply vessel.

[0045] Regardless of how the predetermined end point is sensed, such as by a weight sensor, pressure sensor, flow rate sensor, volumetric (cumulative) flow meter, cycle timer, temperature sensor, or combinations thereof, etc., the low source notification or cylinder change signal is generated when the predetermined end point is reached. Figure 4Step 2) in the sequence, as appropriate for the particular mode of determining the predetermined end point (limit point), and the predetermined end point or limit sensing signal is generated in the electronic circuit of the system, which is programmably arranged with the electronic circuit (controller) of the gas delivery system to implement the automatic exchange sequence. The predetermined end point sensing signal (limit sensing signal) causes the system to proceed to Step 3 to check for the presence and status of the gas cylinder on the B side of the system. If the scale 19B and / or other detection means, such as one or more pressure sensors (PT 40 and / or PT 42) and / or operator manual input, indicate that the gas cylinder 70B is ready for use and in standby mode, the automatic exchange process continues. If not, the system will issue an alarm.

[0046] In Step 4, if the container 70B in Step 3 is determined to be in standby state and thus ready to support process gas flow from said container, the container 70B is opened via actuation of the container valve V21, if not already open. If V21 is a manual valve, it needs to be opened by the operator prior to entering standby mode. If V21 is pneumatic, it will be automatically opened by the system controller at this time. At the same time, the process isolation valve V26 is also automatically opened by the system controller. In the embodiment shown, if any of the valves V22, V23, V24, and V25 are closed, they will also be opened. Upon opening these valves, process gas begins to flow from the cylinder 70B through the process outlet feed line 58B to the process gas outlet line 58, and the automatic exchange program is initiated.

[0047] In Step 5, when the container valve V21 is opened, a timer in the system and electronic circuit is activated, which either counts up to a set time, or counts down from a set time to 0. This time period is the set time for the completion of the supply exchange of process gas from the depleting cylinder 70A to the new cylinder 70B. The set time for the exchange is typically greater than 0 seconds to 1 hour, or 5 seconds to 30 minutes, or 5 seconds to 10 minutes.

[0048] In Step 6, an equalization timer is started at this time (either counting up to a set time or counting down from a set time), and the system waits for a preset equalization time period, which can be any time greater than 0 seconds to 1 hour, or 5 seconds to 30 minutes, or 5 seconds to 10 minutes, to allow the gas flow from both sides of the cylinders (from the cylinder 70A on the A side and from the cylinder 70B on the B side) to equalize. During this equalization time period, the supply from the container 70A is still in the "leading" position due to the output of the regulator PCV31 still being at a higher pressure than the "lagging" regulator PCV41.

[0049] In Step 7, when the equalization timer expires and the process gas flow from cylinders 70A and 70B is substantially equalized, the set point pressure in pressure sensor PT42 or PT50 (whichever is controlling the regulator PCV41) is increased. The set point pressure in pressure sensor PT42 or PT50 (previously set by the user (via the controller (PLC)) for the supply of process gas by the gas delivery system under normal supply conditions) is temporarily increased by 0.01 psi to 10 psi to the temporary swap set point pressure. This allows the regulator PCV41 to allow an increase in process gas flow from cylinder 70B and manifold B side, ultimately achieving a higher set point pressure value than the process gas flow from manifold A side. This step places cylinder 70B in the leading position, and cylinder 70A in the lagging position. The increased flow is maintained until Step 9 of the process.

[0050] In Step 8, pressure sensor PT42 or PT50 measures the pressure to confirm that the pressure has reached the temporary swap set point pressure. Once the pressure measured at PT42 or PT50 exceeds the set point pressure under normal supply conditions, it is considered that cylinder 70B is now in the "leading" position, while cylinder 70A is in the "lagging" position.

[0051] In Step 9, when the temporary swap set point pressure is confirmed by pressure sensor PT42 or PT50, the system returns to the set point pressure at pressure sensor PT42 or PT50 under normal supply conditions, and the B side of the manifold returns to the normal supply set point pressure PID of the regulator. In other words, at this time, the temporary PCV41 output set point increase is removed, and the original user-determined set point is re-established.

[0052] In step 10, after the pre-specified amount of time has elapsed on the timer that started measuring the time of the above step 5 exchange, the system (if automatic) or the operator (if manual) closes the gas cylinder 70A by closing one or more of the following in any combination: cylinder or vessel valve V11, regulator isolation valve V14 (if present in the system), and process isolation valve V16, and the process gas continues to be supplied from the B side of the system including gas cylinder 70B. The time to complete the exchange before the alarm indicating a problem to the operator sounds is 1 second to 1 hour, or 5 seconds to 30 minutes, or 5 seconds to 10 minutes to complete the process after V21 and V26 are opened in step 4. The time to complete the exchange allows for stabilization of the control valve PCV41 and provides for fault tolerance in the event of an error on the vessel 70B side of the system during the exchange process. Possible errors include a pneumatic valve failure or the operator not opening the manual isolation valve (if present in the system). Once the exchange alarm delay timer has expired and no error is detected on the currently online new vessel 70B on the B side of the manifold, the vessel isolation valve V11 and process isolation valve V16 are closed on the spent vessel 70A on the A side of the manifold. The vessel 70B now supplies the process gas, the regulator PCV41 output is controlled using the normal supply set point pressure from feedback from PT42 or PT50. The vessel 70A is considered spent, and the A side of the system is idle or offline.

[0053] In step 11, the spent gas cylinder 70A is replaced with a new gas cylinder. This step 11 can include one or more additional steps in the method of the present invention. Prior to removal of the spent gas cylinder 70A, the A side of the manifold can undergo a number of optional purging and purging steps before and after removal of the spent gas cylinder 70A, and the spent gas cylinder A is replaced with a full new gas cylinder 70A, either manually or automatically. After the necessary connections are made between the manifold A side piping and the new gas cylinder 70A, an optional leak check can be performed, and the gas cylinder 70A can be manually or automatically set to ready and in standby mode in the controller (PLC).

[0054] Steps 1-11 are repeated to continuously supply process gas from one or more online vessels to a single process gas outlet line as needed.

[0055] Example

[0056] The above process is used in a 2 gas cylinder test system according to the improvements and operation of the present invention. The resulting Figure 5 The exchange process and pressure versus time plot shown. Figure 5 The system of the present invention is shown to eliminate the need for Figure 1The large pressure drop characteristic of the prior art system shown has been eliminated or significantly reduced. The resulting reduction in process variability is believed to have the benefit of improving overall process control and increasing product yield of semiconductor devices by constantly flowing process gas to the equipment that needs it.

[0057] The above-described application has been described in relation to specific embodiments. However, it will be appreciated that the application is not limited to those precise embodiments, and that it can be practiced with any multi-vessel array in which gas supply is switched from one vessel to another. Furthermore, although the application has been described illustratively with reference to a dual-vessel array, it will be appreciated that the application is suitable for implementation in a multi-vessel array comprising more than two gas supply vessels. In addition, although reference has been made to a cabinet, it will be appreciated that the application can be applied to a large gas supply system in which the gas vessels are not housed in a cabinet as Figure 3 A cabinet is shown and described, but the application can be applied to a large gas supply system in which the gas vessels are not contained in a cabinet as Figure 2 While the application has been described herein with reference to particular features, aspects and embodiments, it will be appreciated that the application is not limited to those precise embodiments, and that it can be practiced with other variations, modifications and embodiments as will occur to those skilled in the art. Therefore, the application is intended to be broadly interpreted as including all such other variations, modifications and embodiments as are within the scope of the application as claimed below.

[0058] It will be understood that the devices and methods of the present application can be practiced with modifications within the spirit and scope of the disclosure broadly as described herein. It is to be understood that the application is not limited to the specific features, aspects, and embodiments described herein, but only to the extent of the requirements of the patent laws. Accordingly, although specific features, aspects, and embodiments have been described herein, it will be appreciated that the application is not limited to these but can be embodied in other variations, modifications and embodiments within the scope of the application as claimed below.

Claims

1. A gas supply and distribution system comprising: an array of at least two gas storage and distribution vessels arranged for sequential inline distribution involving a switch from one or more first inline vessels to one or more first backup vessels in the array, the system for distributing gas at a preset gas flow rate; a manifold comprising pipes and at least two valves in fluid communication with the array of vessels; a controller; and one or more sensors in communication with the controller, wherein the one or more sensors sense one or more predetermined endpoints of the one or more first inline vessels, whereby the controller initiates an automatic switch from the one or more first inline vessels to the one or more first backup vessels in the array with gas therein for subsequent distribution of gas from the one or more first backup vessels; wherein the controller initiates a gas flow from the one or more first backup vessels after sensing the one or more predetermined endpoints, whereby the one or more first backup vessels become one or more second inline vessels that distribute gas concurrently with the one or more first inline vessels for a period of time before terminating the gas flow from the one or more first inline vessels; wherein during the period of time before terminating the gas flow from the one or more first inline vessels, the controller increases the gas flow from the one or more second inline vessels to a flow rate greater than the preset gas flow rate, and subsequently decreases the flow rate from the one or more second inline vessels to the preset gas flow rate after sensing that the flow rate is higher than the preset gas flow rate.

2. The gas supply and distribution system of claim 1, wherein the period of time is sufficient for the one or more first inline vessels and the one or more second inline vessels to reach equilibrium.

3. The gas supply and distribution system of claim 1 or 2, wherein during the period of time before terminating the gas flow from the one or more first inline vessels, the controller increases the gas flow from the one or more second inline vessels to a flow rate greater than the preset gas flow rate.

4. The gas supply and distribution system of claim 1 or 2, wherein during the period of time before terminating the gas flow from the one or more first inline vessels, the controller increases the gas flow from the one or more second inline vessels to a flow rate greater than the preset gas flow rate, and subsequently decreases the flow rate from the one or more second inline vessels to the preset gas flow rate after sensing that the flow rate is higher than the preset gas flow rate, and terminates the gas flow from the one or more first inline vessels. ​ 5. The gas supply and distribution system of claim 1 or 2, wherein the controller further comprises a timer that is activated upon sensing the predetermined endpoint to define a time period for the one or more second inline vessels and the one or more first inline vessels to dispense the gas, and triggers the system to terminate the gas flow from the one or more first inline vessels at the end of the time period.

6. The gas supply and distribution system of claim 3, wherein the controller further comprises a timer that is activated to define a time period for the flow rate from the one or more second inline vessels to be greater than the preset gas flow rate, and triggers the system to reduce the gas flow rate from the one or more second inline vessels at the end of the defined amount of time measured by the timer.

7. The gas supply and distribution system of claim 1 or 2, wherein the one or more sensors are selected from the group consisting of pressure sensors, timers, load scales, mass flow controllers, and temperature sensors.

8. The gas supply and distribution system of claim 1 or 2, wherein the one or more predetermined endpoints comprise a predetermined endpoint weight of the one or more first inline vessels.

9. The gas supply and distribution system of claim 1 or 2, wherein the one or more predetermined endpoints comprise a predetermined endpoint pressure of the gas dispensed from the one or more first inline vessels.

10. The gas supply and distribution system of claim 1 or 2, wherein the one or more predetermined endpoints comprise a predetermined endpoint flow rate of the gas dispensed from the one or more first inline vessels.

11. The gas supply and distribution system of claim 1 or 2, wherein the one or more predetermined endpoints comprise a predetermined endpoint cumulative volume of the gas dispensed from the one or more first inline vessels.

12. The gas supply and distribution system of claim 1 or 2, wherein the one or more predetermined endpoints comprise a predetermined endpoint rate of change of a property of the gas dispensed from the one or more first inline vessels.

13. The gas supply and distribution system of claim 1 or 2, wherein the one or more predetermined endpoints comprise a predetermined endpoint dispensing time of the gas from the one or more first inline vessels.

14. The gas supply and distribution system of claim 1 or 2, wherein the manifold comprises one or more pressure sensors to measure the gas pressure of the one or more first inline vessels.

15. The gas supply and distribution system of claim 1 or 2, wherein the manifold comprises a process gas supply line and one or more pressure sensors located in the process gas supply line to measure the pressure of the gas flowing in the process gas supply line.

16. The gas supply and distribution system of claim 1 or 2, wherein the manifold comprises one or more control valves with proportional-integral-derivative (PID) control loops to control the flow of the gas.

17. The gas supply and distribution system of claim 16, wherein the one or more control valves having proportional-integral-derivative (PID) control loops are operatively coupled with pressure sensors.

18. The gas supply and distribution system of claim 1 or 2, wherein the gas storage and distribution vessels are disposed in a gas cabinet.

19. The gas supply and distribution system of claim 1 or 2, wherein the valves comprise process isolation valves.

20. A method of substantially reducing pressure variations of a gas dispensed from a gas supply and distribution system, the system comprising: an array of at least two gas storage and distribution vessels arranged for sequential inline dispensing involving an exchange from one or more first inline vessels to one or more first backup vessels in the array, the system being configured to dispense a gas at a preset gas flow rate, the method comprising the steps of: supplying a process gas from the one or more first inline vessels; depleting the process gas from the one or more first inline vessels; sensing one or more predetermined end points of the one or more first inline vessels; opening one or more valves to initiate the supply of the process gas from the one or more first backup vessels, the one or more first backup vessels thereby becoming one or more second inline vessels dispensing the process gas concurrently with the one or more first inline vessels; increasing the flow of the process gas from the one or more second inline vessels above the preset gas flow rate; detecting the increased flow rate from the one or more second inline vessels; re-adjusting the flow of gas from the one or more second inline vessels to the preset gas flow rate; and closing one or more valves to isolate the one or more first inline vessels from the system.

21. The method of claim 20, further comprising the step of initiating an exchange timer at the step of opening one or more valves to initiate the supply of the process gas from the one or more first backup vessels, wherein the exchange timer measures a preset time period until the step of closing one or more valves to isolate the one or more first inline vessels from the system.

22. The method of claim 20 or 21, wherein the system further comprises one or more sensors selected from a weight sensor, a pressure sensor, a flow rate sensor, a volume cumulative flow meter, a cycle timer, a temperature sensor, or a combination thereof, for performing the step of sensing one or more predetermined end points of the one or more first inline vessels.

23. The method of claim 20 or 21, further comprising the step of checking the presence and status of the one or more first backup vessels prior to the step of opening one or more valves to initiate the supply of the process gas from the one or more first backup vessels.

24. The method of claim 20 or 21, wherein the step of sensing one or more predetermined end points of the one or more first in-line containers senses a decreasing flow rate of the process gas measured by a pressure sensor, or a decreasing rate of change of one or more properties of the process gas.

25. The method of claim 20 or 21, further comprising the step of: prior to the step of increasing the flow of process gas from the one or more second in-line containers above the preset gas flow rate, the one or more second in-line containers are allowed to dispense gas concurrently with the one or more first in-line containers to equalize.

26. The method of claim 25, wherein the step of allowing the one or more second in-line containers to dispense gas concurrently with the one or more first in-line containers to equalize is measured by an equalization timer initiated at the step of opening one or more valves to begin supplying the process gas from the one or more first backup containers.

27. The method of claim 20 or 21, wherein the system will issue an alarm if an error is detected at any step.

28. The method of claim 20 or 21, wherein after the step of closing one or more valves to isolate the one or more first in-line containers from the system, the method further comprises the step of replacing the one or more first in-line containers with one or more new containers.

29. The method of claim 28, wherein the system further comprises a manifold in fluid communication with the one or more first in-line containers, and prior to the step of removing the one or more first in-line containers, the method further comprises the step of purging and flushing the manifold.

30. The method of claim 20 or 21, wherein the one or more predetermined end points are selected from an end point weight of the one or more first in-line containers, an end point pressure of gas dispensed from the one or more first in-line containers, an end point flow rate of gas dispensed from the one or more first in-line containers, an end point cumulative volume of gas dispensed from the one or more first in-line containers, an end point rate of change of a property of gas dispensed from the one or more first in-line containers, and an end point dispensing time of gas dispensed from the one or more first in-line containers.

31. The method of claim 20 or 21, wherein the step of increasing the flow of process gas from the one or more second in-line containers above the preset gas flow rate is performed by using a proportional-integral-derivative (PID) control loop operatively coupled to a pressure sensor in fluid communication with the one or more second in-line containers.

32. The method of claim 28, wherein the method steps in claims 20-31 are repeated, wherein the one or more second in-line containers are the one or more first in-line containers, and the one or more new containers are the one or more first backup containers.

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