Smart seal for monitoring and analysis of seal properties useful in semiconductor valve

Abstract

To provide monitoring and analysis of seal properties and seal life data.SOLUTION: The method includes providing a valve assembly movable from an open position to a closed position and including a seal seated within the valve and in contact with a surface of the valve assembly, where when the seal is in operation it is subject to degradation. At least one sensor is placed for measuring micro strain on a surface of the valve assembly or within the valve assembly. The valve assembly is placed in an operation where the seal is subject to degradation and the operation of the valve assembly is initiated. At a time after the operation is initiated, micro strain data is recorded and at least one other property related to a condition selected from an ambient condition of operation and a condition related to degradation of the seal is recorded; and the recorded data is analyzed against baseline data associated with 100% seal life to evaluate seal life at the time after the operation is initiated as a percentage of seal life less than 100%.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This U.S. non - provisional patent application claims the benefit under 35 U.S.C. Section 119(e) (Title 35, United States Code, Section 119(e)) of U.S. Provisional Patent Application No. 62 / 855,639, filed on May 31, 2019, entitled "Smart Seals for Monitoring and Analysis of Seal Properties Useful in Semiconductor Slit and Gate Valves", the entire disclosure of which is incorporated herein by reference.

[0002] (Field of the Invention) The present invention relates to seals that are capable of self - sensing, and in particular, to the field of seals that provide the ability for monitoring and analysis of seal characteristics and seal life data.

Background Art

[0003] Various valve assemblies for use in semiconductor manufacturing, including slit valves and partition valve doors and others, are well - known. With respect to slit valves and partition valve doors, such doors are closed against semiconductor manufacturing equipment using a seal or gasket to ensure that contaminants remain outside the reaction chamber and that reactants from within the chamber do not leak out. However, such reaction chambers need to open and close during manufacturing to allow wafers for manufacturing chips and similar target substrates to move into and out of the reaction chamber. In one preferred design, seals for such slit valves and partition valves are incorporated into a bonding assembly called a bonded partition valve or bonded slit valve ("BSV").

[0004] For purposes of illustration, generally, such a door will be referred to as a slit valve or BSV. For example, a slit valve door used within a semiconductor etching and deposition system provides the required seal characteristics, but can be variably affected by different reactants and different reactant conditions. Such a slit valve incorporating a door and a seal operates in a valve that opens and closes to cover a "slit" opening into the chamber. The seal is provided to seal around the opening or slit within the chamber when the valve is in the closed position and to seal the opening of the chamber. When the valve is open, a substrate for semiconductor manufacturing is moved into and out of the process chamber through the slit.

[0005] Harsh precursors, plasmas, high temperatures, and other conditions can wear different types of seals at various rates. Most such reaction chambers operate under vacuum conditions and use seals throughout the system to maintain the vacuum environment.

[0006] Since such seals are generally formed from highly chemically resistant elastomeric materials, it is understandable that they are expensive to purchase themselves and, therefore, one may not desire to replace the seals lightly. However, due to the variability of the effects of reactants and conditions on the various elastomeric materials used to make the seals, it is not always easy to predict when the seal level will begin to be compromised and / or when an unexpected failure is imminent. The elastomeric seal characteristics and other physical characteristics of the materials can be tested and that information used to estimate failure in different environments and the expected seal life information. However, with the various environments, conditions, and usage expectations, one would expect to replace the seal before damage to a particular product, non-uniformity of product results, or failure occurs in order to be safe.

[0007] The products to be manufactured are very expensive to manufacture themselves, so unnecessary maintenance downtimes and / or breakdowns are even more expensive for the manufacturer than replacing the seals. Therefore, the effective seal life is a crucial factor affecting the operating time of the chamber, the use of the chamber, the scheduling of maintenance, and product failures due to seal material degradation. Chemical, temperature, and other process conditions affect the materials of the seals and doors, and mechanical stresses occur due to the operation of the valves, all of which can lead to seal degradation and failure.

[0008] One way to address such issues in the prior art involves the expected seal life and the use of testing, which can incur additional costs as described above. Monitors are also sometimes positioned within the reaction chamber, and the reaction chamber is monitored for changing conditions within the chamber, which can affect manufacturing. Reactants are also monitored. Degradation is typically understood by detecting the presence of a vacuum leak or particle generation from the degraded seal material.

[0009] However, if there is a good way to determine when the seal is damaged and / or when the process requiring maintenance is affected, such problems can be improved, cost savings can be achieved, and failures can be minimized. Further, if there is a way to avoid the drawbacks of seal degradation while maximizing the seal life, as described above, the operation can be improved.

[0010] In some other environments where conditions are harsh, such as in in - well applications in an oil field area, a certain development in seal monitoring has been developed that generates a seal providing feedback. For example, U.S. Patent Publication No. 2017 / 0130562 A1 (Patent Document 1) teaches embodiments of seals for oil field applications in both wellbores and other components of wellhead assemblies, which embed sensors within the seals to obtain data that can be used to determine and monitor the condition of the seals by monitoring physical operating conditions and stress or strain on the seals. This data is used to determine when the seal will need to be replaced, regardless of its condition, in a scheduled manner. The collected data is compared with baseline data using data analyzers and predictive algorithms to evaluate the expected performance characteristics of the seals. Antennas and RFID tags or wear sensors can also be incorporated. The sensors can also be embedded within the packing.

[0011] Other prior arts have attempted to monitor aspects of seal life or employ sensors and other detectors in semiconductor processing steps (e.g., including installing sensors on slit valves, sealing plates, and monitoring aspects of the process), but such attempts generally do not focus on seal degradation and more typically focus on door functions, door pressures, or avoidance of damage to ensure proper transfer and positioning of substrates moving into and out of the chamber. Such patents insert or incorporate sensors into or on seals to monitor pressure differences or separate them between chambers and / or inside and outside of chambers or doors.

[0012] Examples of such types of sensor use include the following.

[0013] U.S. Patent No. 7,841,582 B2 (Patent Document 2) describes a method and apparatus for controlling the pressure on a slit valve door using an actuator during cleaning, as opposed to during reaction when the internal pressure would be higher than during cleaning, and applying different pressures to the actuator and the door (thereby preventing the seal from being under unnecessarily high vacuum conditions during cleaning).

[0014] U.S. Patent No. 8,815,616 (Patent Document 3) describes a slit valve unit with a housing around the slit valve and a series of packing units (O-ring seals) for making the area airtight. Small conduits communicate with a sensor unit that monitors the airtight area between the seals for pressure changes and can avoid an explosion or leakage of process gas, and a control unit that can stop the unit and prevent an event.

[0015] U.S. Patent No. 9,347,495 includes a bearing assembly formed using an RFID having an inlet IC chip, an antenna connected to the chip, and a magnetic sheet function embedded in either a bearing seal or a raceway ring.

[0016] U.S. Patent No. 8,282,013 describes an embedded RFID responder that is placed centrally within a seal and then vulcanized. The seal is thus described as being able to communicate through an RFID transducer that can be programmed to contain information about the seal (part number, manufacturing number, batch number, and / or lot number, code, dimensions, manufacturing date or sale date, installation date and / or expiration date).

[0017] U.S. Patent No. 7,398,692 is directed to a circuit chip mounted in an integrated manner on an O-ring seal having information transmission means for transmitting information outside the seal ring. The chip is sandwiched within a notch in the seal body, and then the notch is fixed. Wiring attached to the sensor is drawn out from the main body portion and connected to a pressure measuring device. Pressure monitoring is evaluated to measure the internal seal stress and to stop its operation when the seal reduces the internal stress to 80%.

[0018] U.S. Patent Publication No. 2018 / 0052104 A1 describes the use of component wear indicator materials that can be installed at various locations in a chamber. The wear indicator has different layers and a phosphorescent material for indicating wear.

[0019] U.S. Patent No. 9,975,758 includes microsensors that can be mounted on wafer processing equipment for monitoring various conditions in real time. The microsensors can be installed throughout the process chamber and also on the tool.

[0020] U.S. Patent No. 7,658,200 B2 discloses the use of a pressure adjustment system for two chambers separated by a slit valve. The purpose is to monitor the pressure difference in the chambers and avoid accidentally opening the chambers. This patent teaches the use of pressure sensors in each chamber that communicate with a controller to prevent unintentional opening. The sensors are not used to monitor conditions that affect the effectiveness of the seal.

[0021] U.S. Patent No. 6,575,186 uses a series of sensors on a joining slit valve door to provide additional soft landing during the door closing process and control the speed of the air pressure on the door to avoid seal damage. The three sensors used are for positioning and interacting with a pneumatic closing system.

[0022] U.S. Patent No. 6,291,814 installs sensors at both ends of a slit valve with an emitter to avoid damage to the movable wafer on the seal plate and receives a signal to monitor the movement near the door.

[0023] U.S. Patent No. 5,363,872 describes the control of a slit valve door based on the pressure difference across a barrier (described as a wall) between an inlet chamber and a reaction chamber. Each chamber has a sensor, and the pressure difference is analyzed to control the operation of the door and the pressure applied by the slit valve door.

[0024] The applicant of the present specification contributed to the development of a product for monitoring the properties inside a reaction chamber and previously developed a camera known as a "wafer cam" that enabled camera sensing inside a process chamber. However, such a camera was not developed for the operation of monitoring the integrity of seals within a BSV or other semiconductor valve assembly.

[0025] In the art, there is a need for a maximum useful seal life and critical analysis that would assist in selecting the optimal seal to minimize downtime and operating time, improve maintenance cycles, and avoid seal degradation failures, and an improved method for ensuring the associated maximum seal life for use in semiconductor processing.

Prior Art Documents

Patent Documents

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Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Means for Solving the Problems

[0027] The invention herein includes embodiments of a method for monitoring seal life. The method includes providing a valve assembly that is movable from an open position to a closed position, has a seal fixed within the valve and contacting the surface of the valve assembly, where the seal is subject to degradation when operating; installing at least one sensor for measuring micro-strain on or within the surface of the valve assembly; placing the valve assembly in an operating state where the seal is subject to degradation and starting the operation of the valve assembly; recording, at a time after the operation has started, the micro-strain data and at least one other characteristic related to a condition selected from the ambient conditions of the operation and conditions related to the degradation of the seal; analyzing the recorded data against baseline data associated with 100% seal life and evaluating the seal life at a time after the operation has started as a percentage of seal life less than 100%.

[0028] The seal preferably has elastomeric properties. The valve assembly can be one of a valve assembly with a door, a pendulum valve assembly, and an isolation valve assembly, or other similar valve assemblies. In one embodiment, the valve assembly is a valve assembly with a door, the door is configured to cover an opening in a process chamber, the valve assembly further includes a valve for moving the door from an open position to a closed position, and the seal contacts the door.

[0029] In a further embodiment, the method further includes installing at least one sensor for measuring micro-strain on the outer surface of the door. In the method, the operation of the valve assembly can be started by initiating a vacuum process when the door is in the closed position. The method can further include evaluating the seal life at a time after the vacuum process has started as a percentage of seal life less than 100%. In such an embodiment, the movable valve door can be a buttress valve or a partition valve. The seal can be mechanically attached to the surface of the door and preferably has elastomeric properties.

[0030] Furthermore, two or more sensors for measuring minute strains, each positioned at a different location on the door, may be present. Such sensors may be bonded to the outer surface of the door. Additionally, one or more strain gauge rosette patterns may be positioned on the door. In the case of using two or more strain gauge rosette patterns, they are preferably positioned at different locations on the door.

[0031] In one embodiment of a method of using a valve with a door, baseline data is measured after calibrating the door. The baseline data can also be measured when a load is applied to and then removed from the door, at least in part based on initial minute strain data. In such an embodiment, the baseline data can be generated by measuring the initial minute strain data at 100% seal life and then again at one or more percentages of seal life to generate adjusted baseline data. The baseline data can be stored and incorporated into a database to predict the seal life for a particular type of door and seal in a particular process.

[0032] In a further embodiment of the method herein, at least one sensor can be a strain gauge. Additionally, at least one other characteristic is related to the ambient conditions of operation and is selected from one or more of temperature, humidity, and vibration, and monitoring of such operating conditions is used to compensate for ambient noise. At least one sensor is preferably installed to measure each of at least one other characteristic.

[0033] The microstrain data of the skew gauge is preferably converted into a digital signal through the use of a circuit including a Wheatstone bridge for converting the microstrain data into a change in voltage. The method also includes adjusting an analog signal from the measured change in voltage and converting the analog signal into a digital signal. In such a method, the circuit is incorporated within a printed circuit board. The Wheatstone bridge preferably incorporates high-precision resistors having a tolerance of about 0.25% or less, preferably about 0.1% or less. The circuit may comprise an amplifier.

[0034] In a further embodiment, the baseline data is measured after calibrating the valve assembly. The baseline data is preferably measured after the valve assembly comes into an operating state and the valve is under pressure, based at least in part on the initial microstrain data. The baseline data can also be measured when a load is applied to and then removed from the valve, based at least in part on the initial microstrain data. The baseline data can be generated by measuring the initial microstrain data at 100% seal life and again at one or more percentages of seal life to generate a range of adjusted baseline data. In an embodiment, using a valve assembly with a door, the baseline data can be stored and incorporated into a database to predict the seal life for a certain type of door and seal in a particular process.

[0035] The present invention further includes a system for analyzing seal life, the system comprising at least one memory for storing computer-executable instructions and at least one processing unit for executing the instructions stored in the memory, the execution of the instructions engaging a valve assembly movable from an open position to a closed position and bringing the valve assembly into an operating state, the valve assembly comprising a seal, the seal being fixed within the valve and in contact with the surface of the valve assembly, pressure being applied to the valve assembly during operation, the seal being subject to degradation, receiving a signal from a circuit from a change in voltage, the circuit communicating with at least one sensor for measuring microstrain on or within the surface of the valve assembly, recording microstrain data and at least one other characteristic related to a condition selected from the ambient conditions of operation and conditions related to seal degradation after the operation of the valve assembly is initiated, analyzing the data recorded against baseline data associated with 100% seal life, and evaluating the seal life at a time after the operation of the valve assembly is initiated as a percentage of seal life less than 100%, and programming at least one processing unit to perform operations including these.

[0036] In one embodiment of the system, the seal has elastomeric properties. The valve assembly can be one of a valve assembly with a door, a flapper valve assembly, and an isolation valve assembly. The valve assembly can be a valve assembly with a door, the door being configured to cover an opening in a process chamber, the valve assembly further comprising a valve for moving the door from an open position to a closed position, and the seal contacting the door. The system can further comprise at least one sensor installed on the outer surface of the door for measuring microstrain. The operation of the valve assembly can be initiated by starting a vacuum process when the door is in the closed position. In the system, the seal life can be evaluated as a percentage of seal life less than 100% at a time after the vacuum process is initiated. The movable valve door can be a buttress valve or a partition valve.

[0037] The present invention further includes a self-sensing valve assembly, the self-sensing valve assembly being movable from an open position to a closed position, fixed within the valve assembly, and having a seal that contacts the surface of the valve assembly. During operation of the valve assembly, the seal is under pressure and undergoes degradation. The valve assembly includes at least one sensor for measuring microstrain on or within the surface of the valve assembly. The at least one sensor measures at least one other characteristic related to conditions selected from the ambient conditions of operation and conditions related to the degradation of the seal during operation. The sensor communicates with a circuit capable of transmitting a signal from a change in voltage.

[0038] In one embodiment, the self-sensing valve assembly further includes a thermocouple that communicates with one of the sensors for measuring microstrain on the outer surface of the valve assembly. The seal preferably has elastomeric properties. The valve assembly can be one of a valve assembly with a door, a flapper valve assembly, and an isolation valve assembly. Preferably, the valve assembly is a valve assembly with a door, the door being configured to cover an opening in the process chamber, the valve assembly further including a valve for moving the door from the open position to the closed position, and the seal contacting the door. The at least one sensor is preferably installed on the outer surface of the door for measuring microstrain. The operation of the valve assembly can be initiated by starting a vacuum process when the door is in the closed position. In such an embodiment, the seal life can be evaluated as a percentage of seal life less than 100% at the time after the vacuum process is started. The movable valve door is preferably a pinch valve or a diaphragm valve.

[0039] The systems and self-sensing valve assemblies herein can further incorporate any of the other variations of the methods as described above and elsewhere herein. The present invention provides, for example, the following items. (Item 1) A method for monitoring seal life, the method comprising To provide a valve assembly movable from an open position to a closed position, the valve assembly comprising a seal, the seal being fixed within the valve and in contact with a surface of the valve assembly, the seal being subject to degradation when operating, and installing at least one sensor for measuring microstrain on a surface of the valve assembly or within the valve assembly; placing the valve assembly in an operating state in which the seal is subject to degradation and initiating operation of the valve assembly; recording microstrain data and at least one other characteristic at a time after the operation has been initiated, the at least one other characteristic being related to conditions selected from ambient conditions of the operation and conditions related to degradation of the seal; analyzing the recorded data against baseline data associated with 100% seal life and evaluating the seal life at the time after the operation has been initiated as a percentage of seal life less than 100%; A method comprising. (Item 2) The method according to item 1, wherein the seal has elastomeric properties. (Item 3) The method according to item 1, wherein the valve assembly is one of a valve assembly with a door, a pendulum valve assembly, and an isolation valve assembly. (Item 4) The valve assembly is a valve assembly with the door, the door being configured to cover an opening in a process chamber, the valve assembly further comprising a valve for moving the door from the open position to the closed position, and the seal being in contact with the door. The method according to item 3. (Item 5) The method according to item 4, further comprising installing the at least one sensor on an outer surface of the door for measuring microstrain. (Item 6) The method according to item 5, wherein starting the operation of the valve assembly includes starting a vacuum process when the door is in the closed position. (Item 7) The method according to item 5, further comprising evaluating the seal life at the time after the vacuum process is started as a seal life at a rate less than 100%. (Item 8) The method according to item 4, wherein the movable valve door is a joining slit valve or a partition valve. (Item 9) The method according to item 8, wherein the movable valve door is a joining slit valve. (Item 10) The method according to item 4, wherein the seal is mechanically attached to the surface of the door. (Item 11) The method according to item 4, wherein the seal has elastomeric properties. (Item 12) The method according to item 4, wherein there are two or more sensors for measuring microstrain, and each of the two or more sensors is positioned at a different location on the door. (Item 13) The method according to item 12, wherein the sensor is joined to the outer surface of the door. (Item 14) The method according to item 12, wherein one or more strain gauge rosette patterns are positioned on the door. (Item 15) The method according to item 14, wherein there are two or more strain gauge rosette patterns, and they are positioned at different locations. (Item 16) The method according to item 4, wherein the baseline data is measured after calibrating the door. (Item 17) The method according to item 4, wherein the baseline data is measured when a load is applied to the door and then removed, based at least in part on initial microstrain data. (Item 18) The baseline data is generated by measuring the initial microstrain data at 100% seal life, measuring again at one or more certain percentages of seal life, and generating adjusted range of baseline data, the method according to item 17. (Item 19) The baseline data is stored and incorporated into a database to predict the seal life for a certain type of door and seal in a specific process, the method according to item 18. (Item 20) The at least one sensor is a strain gauge, the method according to item 1. (Item 21) The at least one other characteristic is related to the ambient conditions of the operation, is selected from one or more of temperature, humidity, and vibration, and monitoring of such operating conditions is used to compensate for ambient noise, the method according to item 1. (Item 22) At least one sensor is installed to measure each of the at least one other characteristic, the method according to item 1. (Item 23) The microstrain data of the strain gauge is converted into a digital signal through the use of a circuit including a Wheatstone bridge for converting the microstrain data into a change in voltage, the circuit adjusts an analog signal from the measured change in voltage and converts the analog signal into the digital signal, the method according to item 1. (Item 24) The circuit is incorporated into a printed circuit board, the method according to item 23. (Item 25) The Wheatstone bridge incorporates high-precision registers with a tolerance of about 0.25% or less, the method according to item 23. (Item 26) The high-precision register has a tolerance of about 0.1% or less, the method according to item 25. (Item 27) The circuit is provided with an amplifier, the method according to item 23. (Item 28) The baseline data is measured after calibrating the valve assembly, by the method described in Item 1. (Item 29) The baseline data is measured after the valve assembly comes into an operating state and the valve is under pressure, based at least in part on initial microstrain data, by the method described in Item 1. (Item 30) The baseline data is measured when a load is applied to and then removed from the valve, based at least in part on initial microstrain data, by the method described in Item 1. (Item 31) The baseline data is generated by measuring initial microstrain data at 100% seal life and then again at one or more fractional seal lives to generate adjusted baseline data, by the method described in Item 30. (Item 32) The baseline data is stored and incorporated into a database to predict seal life for a certain type of door and seal in a particular process, by the method described in Item 31. (Item 33) A system for analyzing seal life, the system comprising at least one memory for storing computer-executable instructions, and at least one processing unit for executing the instructions stored in the memory wherein execution of the instructions engages a valve assembly movable from an open position to a closed position and places the valve assembly in an operating state, the valve assembly comprising a seal, the seal being fixed within the valve and in contact with a surface of the valve assembly, pressure being applied to the valve assembly during operation, and the seal being subject to degradation; and receives a signal from a circuit from a change in voltage, the circuit communicating with at least one sensor for measuring microstrain on or within the surface of the valve assembly; After the operation of the valve assembly is started, recording micro-strain data and at least one other characteristic, wherein the at least one other characteristic is related to conditions selected from the ambient conditions of the operation and conditions related to the deterioration of the seal. Analyzing the recorded data against baseline data associated with 100% seal life and evaluating the seal life at a time after the operation of the valve assembly is started as a percentage of seal life less than 100%. Programming the at least one processing unit to perform an operation including the above to implement a system. (Item 34) The system according to item 33, wherein the seal has elastomeric properties. (Item 35) The system according to item 33, wherein the valve assembly is one of a valve assembly with a door, a pendulum valve assembly, and an isolation valve assembly. (Item 36) The valve assembly is a valve assembly with the door, the door is configured to cover an opening in a process chamber, the valve assembly further includes a valve for moving the door from the open position to the closed position, and the seal is in contact with the door. The system according to item 35. (Item 37) At least one sensor is installed on the outer surface of the door to measure micro-strain. The system according to item 36, which is installed. (Item 38) The operation of the valve assembly is started by starting a vacuum process when the door is in the closed position. The system according to item 37. (Item 39) The seal life is evaluated as a percentage of seal life less than 100% at the time after the vacuum process is started. The system according to item 38. (Item 40) The movable valve door is a joined slit valve or a partition valve. The system according to item 36. (Item 41) A self-sensing valve assembly, wherein the self-sensing valve assembly is A valve assembly movable from an open position to a closed position, the valve assembly comprising a seal, the seal being fixed within the valve assembly and in contact with the surface of the valve assembly, and during operation of the valve assembly, the seal being under pressure and subject to degradation, a valve assembly, and At least one sensor for measuring microstrain on the surface of the valve assembly or within the valve assembly Comprising At least one sensor measures at least one other characteristic, the at least one other characteristic being related to conditions selected from ambient conditions of operation and conditions related to degradation of the seal during operation, and the sensor communicates with a circuit capable of transmitting a signal from a change in voltage, a self-sensing valve assembly. (Item 42) Further comprising a thermocouple, the thermocouple communicating with one of the sensors for measuring microstrain on the outer surface of the valve assembly, the self-sensing valve assembly according to item 41. (Item 43) The seal has elastomeric properties, the self-sensing valve assembly according to item 41. (Item 44) The valve assembly is one of a valve assembly with a door, a pendulum valve assembly, and an isolation valve assembly, the self-sensing valve assembly according to item 41. (Item 45) The valve assembly is a valve assembly with a door, the door being configured to cover an opening in a process chamber, the valve assembly further comprising a valve for operating the door from the open position to the closed position, and the seal being in contact with the door, the self-sensing valve assembly according to item 44. (Item 46) At least one sensor is installed on the outer surface of the door for measuring microstrain, the self-sensing valve assembly according to item 45. (Item 47) The self-sensing valve assembly according to item 45, wherein the operation of the valve assembly is initiated by starting a vacuum process when the door is in the closed position. (Item 48) The self-sensing valve assembly according to item 47, wherein the seal life is evaluated as a seal life percentage of less than 100% at the time after the vacuum process is started. (Item 49) The self-sensing valve assembly according to item 45, wherein the movable valve door is a joined slit valve or a partition valve.

Brief Description of the Drawings

[0040] The foregoing summary and the following detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, the presently preferred embodiments are shown in the drawings. However, it should be understood that the invention is not limited to the precise arrangements and means shown.

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Mode for Carrying Out the Invention

[0066] As used herein, words such as "inner" and "outer", "upper" and "lower", "proximal" and "distal", "top" and "bottom", and words of similar import are used herein to assist the reader of the disclosure in a deeper understanding of the invention in light of the drawings of the specification, while intending to serve the purpose that the reader is not intended to be limited in any manner.

[0067] The present applicants have developed related systems and methods that can provide a self-sensing seal for use in a semiconductor valve assembly having a seal (a slit valve door with a seal, e.g., BSV, flapper valve, and other chamber or flow isolation valves, etc.), and the real-time status of the effective seal life for use in such valve assemblies (such as seals used within the door of a BSV, etc.). The system can detect a plurality of characteristics and phenomena that can affect seal life, including changes in pressure applied to the seal, temperature at the interface between the door or other valve assembly surface and the seal, processing intensity at the door or other assembly surface interface, chemical and pathway exposure of the seal to semiconductor or other harsh chemical treatments, and other characteristics. The system can optionally also include a visual camera interface. The detected information is then received in the system and then used to estimate the relative seal life in light of the actual variables affecting the door in a particular valve assembly or BSV in that process. Thus, each seal in use can be optimized for its best seal life. Additionally, the user of the system can monitor the integrity of the seal while the seal is being used to estimate the expected life of the seal and avoid failures of door seals and other valve seals that can lead to product loss.

[0068] The self-sensing seals and methods and systems herein for monitoring seal life are, in this specification, particularly useful in semiconductor manufacturing valve assemblies including BSVs, but they can be employed in similar valves used in fluid handling conditions and other environments where seal life is important for operation, where the seal is under pressure, strain, and environmental or ambient operating conditions where the seal is subject to degradation. This is a particularly difficult problem in semiconductor manufacturing, with particular emphasis on semiconductor seal assemblies such as BSVs, flapper valves, and isolation valves. For the purpose of describing the use of such self-sensing door seals and other valve assemblies and related methods and systems herein, the Applicant will illustrate the invention through a preferred embodiment of a self-sensing BSV seal, but it should be understood that based on this disclosure, the described embodiments can be employed for use in other similar valve seal assemblies.

[0069] Gate valves and slit valves having seals are known in the art, and the methods and systems can be implemented using any of these designs. Examples of commercially acceptable doors of this nature are available from Greene, Tweed & Co. (Kulpsville, Pennsylvania, USA) and are also described, for example, in U.S. Patent Application Publication No. 2012 / 0100379A1 (incorporated by reference in relevant part). Other BSVs and gate valves with joined or other assemblies with known or undeveloped seals can be used in the systems and methods herein.

[0070] Such gate valves and slit valves are generally formed from a metallic door material (metal or metal alloy) with a preferred material including aluminum or stainless steel. The seals in such doors are preferably formed from an elastomeric material or a material having elastomeric properties under operating conditions. Typical materials used are fluoroelastomers, perfluoroelastomers, silicon-based elastomers, or polyarylene materials having elastomeric properties. In addition, backup rings or seals such as fluoropolymers (such as polytetrafluoroethylene) can also be incorporated either alone or as a backup protection seal for a primary seal formed using an elastomer or a material with elastomeric properties.

[0071] Such seals can be mechanically affixed, joined, or molded in place on the door using a variety of commercially available materials and door assemblies.

[0072] Since there are various conditions that affect seal life and BSV, Applicant has evaluated those conditions and properties affected by temperature (such as thermal expansion, stress relaxation, and compression set of the seal), pressure (vacuum level and forces on the seal, actuator forces (i.e., forces required by the actuator based on the state of the seal)), and the effect of chemical erosion on the seal material and the door (affected by levels of plasma etching, erosion, and microstrains). Based on such evaluations, Applicant has developed a monitoring system for measuring these properties and providing real-time feedback to a learning system while the BSV is in operation. The system uses relevant algorithms that were developed to evaluate properties against seal life in a learning database so as to control and evaluate seal life, maximize seal life, and predict failures and maintenance during use.

[0073] In one embodiment, it has been demonstrated that the micro-strain on the back surface of the BSV door contributes to the reaction pressure on the back surface of the door plate, which can be used as a characteristic to be monitored in the methods herein. The curvature or strain on the door material, typically metal, provides a slight strain change within the door, and that strain data is used to monitor the seal. The seal in this case is located on the door itself or milled into the door, and the BSV will include a strain gauge (also identified as a strain gage). gage).

[0074] In another embodiment, a linear variable differential transformer (LVDT), which is an electromechanical sensor used to convert mechanical motion or vibration, specifically linear motion, into a variable current, voltage, or electrical signal and vice versa, is employed and installed proximate to the seal to internally measure the distance within the gap between the door and the mating surface. The distance is then converted into a method of monitoring seal degradation. Suitable commercially available LVDTs that can be employed are available, for example, from Omega Engineering, Inc. (Norwalk, Connecticut, USA).

[0075] In a further embodiment of the method, a capacitive sensor can be used on the door to measure the capacitance (which varies with distance) between the door and the mating surface using a proximity switch.

[0076] Such sensors of various types can be installed in various locations of the valve assembly. For example, in the BSV, the sensor can be installed at any location on the outer surface of the valve assembly (facing towards the reaction chamber (inside the door) or the outside of the chamber (outside the door or on another component of the valve assembly), or facing towards the edge / sides of the door or the assembly), and can be installed within another component part of the door or the assembly (by machining or otherwise forming a location in the door to receive the sensor). It is also within the scope of the present invention that the sensor can be installed on, in the vicinity of, or within the seal itself. However, in the preferred embodiment, the sensor is not employed in a manner that would damage or interfere with the operation of the seal.

[0077] In the preferred embodiment of the present specification, it has been found that when a plurality of sensors, such as strain gauges, are installed in closer proximity to the seal, they function with a higher resolution and can be installed further on or within the seal without departing from the scope of the present invention. However, in order to avoid affecting the seal function, those skilled in the art will understand, based on the present disclosure, that in the preferred embodiment, an installation location near the seal is shown that allows for sufficient reproducibility, sensor data collection, and resolution to generate good resolution and not unduly affect the seal function.

[0078] The properties described above and others can also be measured in the methods herein to evaluate seal life. The methods herein can monitor BSV and other similar shield door life and can be used in real time, and the data can be incorporated into a learning database that can also be collected based on variable seal cross-sectional profiles. Since not all seal profiles are the same in cross-section, seal life data can also be used to evaluate the best seal profile for a given end use, for the same or different seal materials. This data can provide a basis for important insights into how a particular seal design behaves over its measurable life from a new state (as a baseline) over time in a given environment.

[0079] Based on such measurements, the methods herein were devised to detect seal degradation, detect changes in O-ring degradation, and measure seal wear, at least by using strain gauges to measure strain on the BSV door. Such measurements correlate strain data over millions of cycles of loading and unloading to seal wear during operation for long-term sensing. For a given seal cross-sectional geometry, microstrain / microstress data, and data regarding stress relaxation, vacuum force pressure on the door, and temperature are preferably measured throughout the process to evaluate seal life.

[0080] Based on the strain gauge test, it was determined that the strain gauge can preferably be used at one or more locations on the BSV door plate located on the face or side of the BSV door to provide a preferred resolution. However, since the location of the strain gauge installation can be varied as desired, the location and number of strain gauges used are not limited. Preferably, at least about two strain gauges are used. In some embodiments, about 10 or fewer gauges are used. However, no specific number is required, and those exceeding 10 can likewise be employed. Whether the strain gauge is on the surface (inside of the door) where the seal is installed so as to contact the degradation sources such as plasma and chemicals, or on the opposite surface of the door (outside of the degradation source), or on another surface of the door or valve assembly (such as on the seal, in the vicinity thereof, or on the side or edge of the door within it), or is made to enable fixation of the sensor, it is preferably installed at different locations on the external surface of the door or on the external surface of another component of the valve assembly. In the preferred embodiments described herein, the sensors are varied to include several on the inside, outside, and edge / surface portions of the overall external door surface.

[0081] In one preferred embodiment, the strain gauge can be employed in one or more strain gauge rosettes, in which two or more closely positioned gauge grids individually oriented to measure strain in different directions are positioned. Such rosettes are useful for obtaining independent strain measurements due to the directional installation and facilitate the determination of principal strains and stresses. Strain gauge rosettes are sold in various forms, including two grids perpendicular to each other, rectangular rosettes with three grids (two of which are angled 45 degrees and 90 degrees respectively from the first grid), and more triangular arrays with three grids (two of which are angled 60 degrees and 120 degrees respectively from the first one), Vishay Precision Group,Strain Gages and Instruments,Tech Refer to Note TN-515. Suitable strain gages can be purchased from Vishay Precision Group (Raleigh, North Carolina, USA). When two or more rosettes are used, it is preferred that they be present at different locations on the outer surface of the door or other valve assembly (including parts of the outer surface that can be the inner, outer, or side surfaces where the seal contacts the surface which may or may not be the source of degradation).

[0082] Similarly, other sensors can be employed to monitor pressure, temperature, and other monitored process conditions and can be positioned at various locations on the valve assembly including near, on, or in the seal, or on the outer surface of component parts (including within the components to which they are fixed). For example, thermocouples can also be used, either alone or in communication with at least one of the strain gages for monitoring the effect of ambient operating temperature conditions on microstrain.

[0083] The various sensor types that can be used to measure the various seal characteristics and conditions to evaluate seal life include, but are not limited to, strain gages as described above, LVDTs, capacitive sensors, piezoelectric sensors, and temperature and pressure sensors.

[0084] The measured values of microstrain are preferably converted to a digital signal for evaluating the data by various methods known or undeveloped in the art. In one embodiment of the present specification, the sensor incorporates a circuit including a Wheatstone bridge. When using a Wheatstone bridge circuit, an example thereof is shown in FIG. 1, where resistors R1, R2, and R3 are the same and equal to R', and R g is set differently, R g =R'+ΔR, ΔR = 2×ε×R, and the voltage applied to the circuit can be measured. For example, the voltage │V o │ can be expressed as in Equation (I): │V o │=V in / 2×ε / (1 + ε) (I) This is variable with respect to the applied voltage and can convert the changing microstrain data into a voltage difference or change.

[0085] As shown in Figure 2, in the overall signal conversion process 1, the signal 10 calculated from the Wheatstone bridge 12 undergoes signal conditioning 13 using any suitable signal conditioning steps known or undeveloped in the art, providing a conditioned analog signal 14, which is then transmitted to an analog / digital converter (ADC) 15. The analog signal 14 converted to a digital signal 16 is transmitted to an external device using a serial interface 20. If some noise can occur at frequencies of no interest, this effect is preferably minimized by applying a frequency - selective component, for example, using the digital clock in an ADC that starts at 64 kHz, to remove the unwanted frequencies. In one embodiment, an anti - aliasing filter is employed to remove signal components at these frequencies from the input signal.

[0086] Since the target signal is very small, it is preferred that a high - resolution converter be employed and amplification be applied before the conversion to increase the ratio between the signal and the noise. An amplifier is preferably employed for this purpose. Such an amplifier can be added to the instrumentation or an integrated circuit already incorporating such an amplifier can be used.

[0087] A serial interface or Serial Peripheral Interface (SPI) is preferably employed to read data from the ADC and provide the ability to configure the data to the required specifications.

[0088] As shown in FIG. 3, the circuit of the system is designed to include the functional components and passive elements of the circuit on a printed circuit board. FIG. 3 provides an example of a voltage circuit diagram that can be used. Those skilled in the art will understand, based on the present disclosure, that various other circuit elements can also be used or presented to perform the steps as described herein.

[0089] The PCB is preferably designed to minimize the influence of noise from power sources, digital switches, and clocks, etc., and to couple between analog components. A typical AC / DC wall converter can introduce significant noise within the supply of 60 Hz and its harmonics. In light of the sensitivity of elements such as the Wheatstone bridge and the analog elements of the ADC, a low dropout voltage regulator is preferably used to mitigate this and provide a cleaner voltage source.

[0090] In addition, various components within the PCB circuit draw power from the same voltage source through copper traces within the PCB. However, since copper is not a perfect conductor, signals can interact with each other in an undesirable manner. This can be minimized or prevented by using multiple layers in the PCB. The traces are preferably cut in a manner that avoids interaction between analog and digital elements. Further, a larger ground plane can be used to provide a low impedance feedback path. To further minimize the influence of noise at higher frequencies, in one embodiment, a decoupling capacitor C can be used and applied to the PCB in the vicinity of the analog and digital inputs of the ADC. Such capacitors effectively "short-circuit" higher frequencies to ground, preventing them from affecting the circuit.

[0091] The circuit includes a Wheatstone bridge that must maintain an equilibrium configuration with all resistance values equal, as described above, in order to function properly. High-precision registers are incorporated to achieve such purposes and functionality with a preferred tolerance of about 0.1% or less, preferably about 0.005% or lower values.

[0092] The sensor and the circuitry communicate through digital signals that are mounted and communicate with a computer.

[0093] Generally, referring to the entire process system as shown in FIG. 4, generally referred to herein as system 100, the implementation of system 100 can use appropriate hardware or software. For example, system 100 can run and boot operating systems such as Microsoft Windows® operating system, Apple OS X® operating system, Apple iOS® platform, Google Android® platform, Linux® operating system, and other odd-shaped operating systems such as the UNIX® platform.

[0094] Some or all of the functionality and signals provided and described can be implemented in and through software and / or hardware on a user device. The user device is preferably, but not limited to, a general-purpose computer or a special-purpose hardware device capable of executing the functionality described herein, such as a camera, a wireless device, an information device, a workstation, a minicomputer, a mainframe computer, or a computer having other computing devices, a smartphone, a smartwatch, a tablet computer, a portable computer, a television, a virtual reality headset, a laptop, a smart or dumb terminal, a network computer, a personal digital assistant, a home assistant device (Alexa TMor Google (registered trademark) Home TM and the like). The software can be implemented on a general-purpose computing device in the form of a computer, including, for example, a processing unit, a system memory, and a system bus that couples various system components including the system memory to the processing unit.

[0095] In addition, or alternatively, some or all of the functionality can be implemented remotely, in the cloud, or via software as a service. For example, the matching function can be implemented on one or more remote servers or other devices as described in communicating with the user device. The remote functionality can be executed on a server-class computer, which has sufficient memory, data storage, and processing power and runs a server-class operating system (e.g., Oracle (registered trademark) Solaris (registered trademark), GNU / Linux (registered trademark), and Microsoft (registered trademark) Windows (registered trademark) operating systems).

[0096] The system can include a plurality of software processing modules stored in memory and executed on a processor. By way of illustration, the program modules can be in the form of one or more suitable programming languages that are converted to machine language or object code to enable the processor or processors to execute the instructions. The software can be in the form of a stand-alone application implemented within a suitable programming language or framework.

[0097] The method steps of the techniques described herein can be performed by one or more programmable processors that execute one or more computer programs, operate on input data, and generate output. The method steps can also be performed by special-purpose logic circuitry, such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the apparatus can be implemented as such. A module can refer to a computer program that implements its functionality and / or a portion of a processor / special circuitry.

[0098] Processors suitable for the execution of a computer program include, by way of example, both general-purpose and special-purpose microprocessors. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. Essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Information carriers suitable for embodying computer program instructions and data include, by way of example, all forms of non-volatile memory, including semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices, magnetic disks, such as internal hard disks or removable disks, magneto-optical disks, and CD-ROM and DVD-ROM disks. One or more memories can store instructions that, when executed by a processor, form the modules, engines, and other components described herein, and implement the functionality associated with those components, for media assets (such as audio, video, graphics, interface elements and / or other media files), configuration files, and / or the like. The processor and memory can be supplemented by, or incorporated in, special-purpose logic circuitry.

[0099] In various implementations, the user device includes a web browser, a native application, or both to facilitate the execution of the functionality described herein. The web browser enables the device to request a web page or other downloadable program, applet, or document (e.g., from a server) using a web page request. An example of a web page is a data file that can include computer-executable or interpretable information, graphics, sound, text, and / or video that can be displayed, executed, played, processed, distributed, and / or stored and can include links or pointers to other web pages. In one implementation, a user of the system can manually request a web page from the server. Alternatively, the device can automatically make the request using the web browser. This can enable the system to be implemented in multiple locations. Examples of commercially available web browser software include Google® Chrome®, Microsoft® Internet Explorer®, Mozilla® Firefox®, and Apple® Safari®.

[0100] In some implementations, the system includes client software. The client software provides the device with functionality to implement and execute the features described herein. The client software can be implemented in various forms; for example, it can be a native application downloaded to the device and launched in conjunction with a web browser, a web page, a widget, and / or in the form of Java®, JavaScript, .Net, Silverlight, Flash®, and / or other applets or plugins. The client software and the web browser can be part of a single client-server interface; for example, the client software can be implemented as a plugin in the web browser or another framework or operating system. Other suitable client software architectures, including but not limited to widget frameworks and applet technologies, can also be employed with the client software. The software can also be stored and processed locally without accessing web-based communication if it is only for internal use within the system and is being executed.

[0101] The communication network can connect the device to one or more servers and / or connect them to each other. The communication can occur via media such as, for example, standard telephone lines, LAN or WAN links (e.g., T1, T3, 56kb, X.25), broadband connections (ISDN, frame relay, ATM), wireless links (802.11 (Wi-Fi), Bluetooth®, GSM®, CDMA, etc.), and the like. Other communication media are also possible. The network can execute TCP / IP protocol communication and HTTP / HTTPS requests made by a web browser, and the connection between the client and the server can be communicated via such a TCP / IP network. Other communication protocols are also possible.

[0102] The system can also be practiced in a distributed computing environment where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in both local and remote computer storage media including memory storage devices. Other types of system hardware and software as described herein can also be used depending on the capacity of the device and the amount of data processing capability required. The system can also be implemented on one or more virtual machines that execute a virtualized operating system such as those described above and operate on one or more computers having hardware such as those described herein.

[0103] In some cases, a related or other structured database can be provided as a database management system that stores data for processing, for example. Examples of databases include a MySQL database server, or an ORACLE database server made by ORACLE Corp. (Redwood Shores, California), a PostgreSQL database server made by PostgreSQL Global Development Group (Berkeley, California), or an IBM-made DB2 database server.

[0104] Note also that the implementation of the system and method can be provided as one or more computer-readable programs embodied on or in one or more products. The program instructions can be encoded on an electrical, optical, or electromagnetic signal generated by a machine that is generated artificially to propagate signals, for example, to encode information for transmission to a suitable receiver device for execution by a data processing device. For example, the use of the Wheatstone bridge described herein converts microstrain data into a voltage difference, which can be converted into an analog signal and then into a digital signal. A computer storage medium can be, or can be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. Further, a computer storage medium can be a source or destination of computer program instructions encoded within an artificially generated propagated signal, although not a propagated signal. A computer storage medium can be, or can be included in, one or more distinct physical components or media (e.g., multiple CDs, disks, or other storage devices).

[0105] A user can interact with the system through a user interface such as a welcome page. The user interface logs in the user and instructs the user to select various options based on whether it is at system startup or during the monitoring of an ongoing application in the system. The interface can have a list or scroll-type option to enable the user to select an operation.

[0106] On a single page, the user can log in and then start the method illustrated in FIG. 4 by participating in the system at the initial step 102 of the BSV installation. In the installation, the preferred first step 102 of the system 100 will also include the calibration of the newly installed door. The door can be any suitable isolation valve or joining slit valve having a seal. The seal can be any of those described above and can be permanently joined or set during installation. The door is then preferably integrated into the system 100 in step 104 by ensuring that the door is properly installed for the vacuum and operating environment and is in an equilibrium state.

[0107] The door preferably has one or more sensors as described above mounted on the door at one or more locations to measure minute distortions on the door. The door is then operated in step 106 by engaging the door with the valve in the closed position. Such door operation is known in the art and any valve operation for opening and closing the BSV or other doors can be used within the scope of this process. In addition, other sensors can also be incorporated into the process equipment to measure temperature, pressure, and other reaction conditions for later analysis and adjustment regarding the predicted seal life of the seal in the BSV in that particular process.

[0108] The door is engaged in the closed position at step 108, and when the door is under pressure load, a vacuum is engaged within the system to draw a vacuum pressure on the side of the door facing the inside of the reaction chamber, as would occur in the normal operation of a BSV or other similar door. Next, at step 110, baseline data is collected using at least one microstrain sensor and any other sensors installed within the system to measure pressure, temperature, and / or force on the seal. The baseline data is important for subsequent comparison and analysis against a database, such as a learning database or other similar data cache. The baseline in initial use zeros out the system so as to represent 100% seal life / effectiveness. The baseline data is then adjusted at step 112 by applying in real time data developed from the position sensors based on curves generated by the sensor performance for microstrains evaluated against microforces, temperatures evaluated against the cross-sectional geometry of the seal, and curves representing the effect of temperature on microstrains, using data from the stress / strain curve, stress relaxation curve, and measured applied forces brought about by the baseline data. The database of generated relationship information is compared against the baseline data to establish in real time an output in the form of adjusted baseline data.

[0109] The adjusted baseline data is then evaluated and interpreted in step 114. Sensor data for the sensor data database is developed by performing steps at various sensor levels and measuring data at their set seal life levels, generating a database for use within a system for the same type of door and seal assembly that is interpreted based on various relationships between the sensor data. Using the established curves, the micro stress / micro strain, stress relaxation, micro strain measured against the operating vacuum pressure on the door, temperature as evaluated against the cross-sectional geometry of the seal, and the effect of temperature on the micro strain are compared to the adjusted baseline data to determine the seal life in real time. The user interface provides a manner in which the user can view the data in real time and interpret the data in order to adjust the process to maximize the seal life or to fit the seal.

[0110] The incoming data is interpreted in step 116 and converted using system software based on the developed algorithms (which can vary depending on the relationships being tracked), converting the incoming sensor range data 118 developed from the adjusted baseline data measured at different levels (e.g., 100% in step 120 as interpreted in step 121, and further 50% as interpreted based on the sensor range data 118 in step 122). The ongoing status is then measured in real time (124) and interpreted and converted (126) using the sensor range baseline data as interpreted to provide a basis for evaluating the real-time measurement data from the monitoring step (124), providing output data that measures the seal integrity and status at a point in time in the seal life.

[0111] Referring to FIG. 5, the step of collecting baseline data in step 110 is further described in data collection sub-step 200. Data is provided through sensors including the sensors described above in step 210, and the sensors receive micro-strain data 212, temperature data 214, pressure from vacuum 216, the force on the door 218 resulting from such pressure, or another source, and such collected data is input into the developed algorithm 220. A door with a seal is installed within the BSV valve, forming a valve assembly with the door, and the door is activated. The door then engages the seal surface under load / force. The vacuum force thus engaged is applied to the side surface facing the interior of the door and on the seal. Baseline sensor data is then established.

[0112] Referring to FIG. 6, the incoming data collected in step 110 above is adjusted in step 112. The adjusted data 112 is evaluated in sub-step 300 to provide appropriate curves and equations incorporated into the algorithm to adjust the baseline data, from measured values of data at various levels of seal life in the database, through the stress relaxation curve 312, through the relationship equation 314 defining the relationship of micro-strain to force, through the equation 316 defining the effect of temperature on the geometry of the seal cross-section, and from the measured effect 318 of the ambient operating temperature on the micro-strain, as shown in FIG. 6. The initial sensor data is collected and then calibrated to account for the effects on data arising from different physical phenomena. Values are assigned to different characteristics that affect the collected sensor data (110) as described above based on the collected (modeled or measured) data. However, since the seal deteriorates over time, multiple variables can be adopted and monitored in light of their effect on the physical properties of the material over time.

[0113] Regarding the development of data, in order to further develop monitoring algorithms and accuracy, the physical erosion due to the force (load) of the valve, the degree of vacuum drawn, and changes in geometry are varied, and data can be accumulated and constructed over time. The data can be continuously fed and calibrated with each application of the load, i.e., over the operating cycle on each valve assembly, associated with the state where the load is applied, the state where the load is held, and the state where the load is released. For example, on the BSV on each closed door, during operation, it can be held in the state where the door is closed, and continuously fed and calibrated with the cycle where the door is opened. Such cycles can be circulated about 1,000 - 1,800 times for data collection or to generate operating data during use, and during use, can be circulated during all operating cycles. In the final application, calibration will be required each time a new seal / valve assembly is incorporated into the application (e.g., when a new door is installed). Thus, in the initial step, the door is installed, then the door is engaged under load and calibrated, then the door is engaged in actual operation with the installed sensors, an algorithm is adopted, analyzes the data, and feeds real data into the system to display real-time sensor health data to the user.

[0114] Regarding the algorithms as discussed above, exemplary algorithms are provided below. Microstrain = x (force) + y (stress / strain) + z (stress relaxation) + e (temperature effect) + f (geometry of seal cross-section) + g (atmospheric pressure) In the formula, each of the variables x, y, z, e, f, g is each ratio (proportion) of the overall microstrain reading. The ratios (constants) are determined by internal models and tests as described in the examples of this specification.

[0115] As shown in FIG. 7, the adjusted baseline data from 118 is then used in sub-step 400 to interpret the adjusted baseline data. The adjusted baseline data 118 is used in sub-step 410 and interpreted in multiple ranges. Assuming that the initial data point at the start is 100% seal life (at the top of the seal life range), the extrapolated data will be set at 50% (used as the lower limit of the range to be interpreted) in step 412. The selection of 50% as the low point is just a preference in evaluating the seal life data. The low point can be lower than 50% if there is a level of degradation below which potential users do not desire to map or evaluate, or if a higher or more detailed analysis and / or a higher level of degradation is acceptable (e.g., in a lower pressure process). The data extrapolated in this way provides a range that can be compared with the signal sent to the end-user interface indicating the seal integrity compared to the range as a function of the incoming sensor data. In some cases, for example, since the conditions can vary, the change in microstrain can be as low as about 20 microstrains equivalent between a new seal and a degraded seal, or as high as about 150 microstrains equivalent, and other conditions may simply be similar due to the variation in the applied door pressure. However, such relationships can also vary and be affected by the change in microstrain depending on the operating environment or other peripheral operating conditions such as temperature, pressure, load, or other forces on the BSV. Therefore, it is important to monitor and develop relationships for different processes using the baseline and adjusted baseline data so that the change in microstrain can be analyzed against the existing data to best predict and evaluate the seal life and filter out noise from the effects of ambient or other monitored operating conditions.

[0116] As shown in FIG. 8, while the process is in progress, the collection of real-time data is monitored, and the data is interpreted using an algorithm as described above to determine the seal life within the range used for the adjusted baseline data. Each time the system is engaged, when the door is closed, a load is applied by the connection of the door, whereby data is developed while the door is engaged (under load) and when the vacuum pressure is engaged. The baseline data for the closed door is for initial calibration, and since the system collects data in an ongoing manner, the system generates an initial calibration baseline and ongoing data collection during use each time it is engaged.

[0117] As discussed above and based on the present disclosure, the ranges employed for adjusted baseline data and real-time monitoring can be modified to vary from 50% to 100%, but depending on the actual intended use and / or the level of data analysis desired to be implemented, it will be understood by those skilled in the art that it can have higher or lower endpoints, for example, perhaps as low as about 30% or as high as about 70%. The real-time integrity of the seal is then provided to the user on the user interface at 512 as a measure of the seal life measured at a 100% integrity rate at 514.

[0118] (Example) The present invention will now be described in connection with the following non-limiting examples.

[0119] (Example 1) To initially evaluate the seal behavior, a BSV model door D with 1 / 4 symmetry was used as the base level test sample. See FIGS. 9A-9D. In modeling the finite element analysis, the model was based on BSVs including Chemraz® BSV, and the seal was a 1 / 4 symmetry Chemraz® 656 seal S (i.e., a seal having a cross-sectional view as shown in FIGS. 9A, B, and 9D), an 8-node linear brick seal, door, and plate. See FIGS. 9A-9D. The seal S and door D were further modeled as hybrids in the finite element analysis with reduced integration and hourglass control. The plate P (FIGS. 9A, 9B, and 9D) was also modeled with reduced integration and hourglass control, and the door (FIGS. 9A-9D) was modeled using 4-node linear tetrahedra in 1 / 4 symmetry. The modeling of the seal was evaluated for the purpose of finite element analysis within the model described herein and included those characteristics to be considered.

[0120] Deterioration was modeled by segmenting the seal at 0%, 3%, 10%, 20%, 27%, and 34% seal loss to simulate seal deterioration. See FIG. 10. The BSV model received various levels of contact pressure along the longitudinal center path (measured in inches) along the segmented seal. As seen in FIG. 11, the percentage of material loss was shown and was considered in the algorithm model (the seal is shown in a representative manner and in an undeformed state). The effect on the seal along path L-L' demonstrates a change in the behavior of the seal over time as the simulated deterioration increases (i.e., as the seal becomes in a state of more vulnerable lost material). See FIG. 12 for the effect of contact pressure on the seal at various levels of deterioration as shown as seal S along the path of the seal and in a deformed state.

[0121] (Example 2) For testing, a test BSV was prepared, strain gauges were measured, integrated onto the door, and the door was stacked on another door. The effect on the microstrain was measured as the pressure was applied at the initial level and held for a period of 2 minutes. 1 cm The change in microstrain on the BSV door was about 26.6 microstrains. See Figure 13. On 1 mm BSV, the average change in microstrain while pressure was applied was about 33 microstrains. See Figure 14. The measured value of the voltage from the Wheatstone bridge was calculated based on the microstrain, and a voltage of 0.825 mV was measured as the output voltage when 5 V corresponding to an average measured strain of 330×10 -6 i.e., 33 microstrains was applied.

[0122] A further circuit including an AD7799 combined instrumentation amplifier and a voltage regulator was incorporated. See the experimental circuit shown in Figure 3. Although this exemplary circuit was used, others could also be designed to achieve this purpose.

[0123] Based on the evaluation, it was determined that the best resolution and data were generated by installing the strain gauges in the concavities in the surface of the BSV and in the door with an opening for the wire to pass through. Two gauges, one in parallel (2) and the other vertical (1), were also implemented in a preferred manner. See Figure 15. Similar examinations were performed using strain gauges at the vertical (1’) and parallel (2’) positions on the side of the door. See Figure 16.

[0124] (Example 3) Four strain gauges were installed on the peripheral area of the BSV door as close as possible to the seal. The force applied to the door was simulated for test purposes and simulated using a compression test with an Instron tensile tester. A load of 7 kN was applied to the door over 10 seconds, then held for 2 minutes and then released over another 10 seconds. The load cycle (the state where the load was applied, the state where the load was held, and the state where the load was released) was repeatedly executed over approximately 1,000 hours. A data acquisition system was employed to measure the strain gauge readings and was modified in a manner known to those skilled in the art to nullify any increase or decrease in strain from ambient temperature changes. The tests were conducted on two different BSV doors. One of the BSV doors was new and the other had a seal with simulated degradation through a cut within the side edge of the seal using a computer numerical control (CNC) machine.

[0125] To relate the simulated degradation to the integrity of the O-ring, the degraded door was cut twice and the O-ring types at different levels of degradation were taken. The tests on the two doors were conducted both under loaded and unloaded conditions.

[0126] Figure 17 shows a new BSV with strain gauges at different locations 1 (back center), 2 (front right), 3 (front left), and 4 (left end). A degraded BSV door with the same number of strain gauges at the same locations on the door but with additional thermocouples for temperature tracking was also employed. Each BSV was evaluated both with and without load. As an example, a representative photograph of a degraded BSV under load is shown in Figure 18.

[0127] Figure 19 is a graphical representation showing the effect of temperature on the strain data over time from the evaluation of a new BSV door with four strain gauges and thermocouples as described above without the use of load.

[0128] The change in strain at various points on the door corresponds to the ambient temperature change in the room. From the graphical representation and data, it can be determined that, on average across the entire door, a temperature fluctuation of ±1 °C of the room temperature can result in a response of ±20 με.

[0129] Figure 20 shows a graphical representation of the relationship between the minute strain and temperature over time for a new BSV door with four strain gauges positioned as described above and a thermocouple, with the door under an applied load. The ambient temperature change still had an effect on the strain during the compression test. This was most significant at 800 - 1,000 minutes. A temperature change of ±1 °C resulted in a strain response of ±4 με, i.e., 80% lower than when no load was applied.

[0130] Figure 21 shows a graphical representation of the relationship between the minute strain and temperature over time for a simulated deteriorated BSV with four strain gauges positioned in the same manner as the new BSV without the application of a load and with a thermocouple. The change in strain at various points on the door corresponds to the ambient temperature change in the room. From the data and the graph, it was determined that, on average across the entire door, a change of ±1 °C of the room temperature resulted in a response of ±15 με, which was 5 με lower than the new BSV without a load.

[0131] Figure 22 shows a graphical representation of the minute strain and temperature over time for a simulated BSV with four strain gauges positioned in the same manner as the new BSV and with a thermocouple, but with the door under a load. The deteriorated BSV under load was similarly discriminated from the deteriorated BSV without a load.

[0132] The average strain results for the new BSV and the deteriorated BSV are shown below in Table 1 at the various strain gauge positions described above.

Table 1

[0133] The table demonstrates the correlation between a door installed as a new door and a door whose seal has been partially eroded by chemical degradation in a manner similar to that experienced in the end use of such a door. Changes in strain, and extrapolation of changes in strain including its slope, can be converted using the analysis steps of this specification into a real-time assessed seal integrity.

[0134] Those skilled in the art will understand that modifications can be made to the embodiments described above without departing from its broad inventive concept. Accordingly, it is to be understood that the invention is not limited to the specific embodiments disclosed, and is intended to cover modifications within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for monitoring seal life, said method comprising: providing a valve assembly movable from an open position to a closed position, the valve assembly including a seal, the seal having elastomeric properties, fixed within the valve assembly and in contact with a surface of the valve assembly, the seal being subject to deterioration when the seal is in operation; providing at least one sensor for measuring microstrain and at least one sensor for measuring at least one other characteristic related to ambient conditions of operation or related to degradation of the seal on or within the valve assembly; placing the valve assembly in an operational state in which the seal is subject to degradation and initiating operation of the valve assembly; recording micro-strain data and data related to the at least one other characteristic at a time after the operation is initiated; generating baseline data by first measuring the microstrain and the at least one other property of the seal before degradation occurs, corresponding to 100% seal life, and generating an adjusted range of baseline data by again measuring the microstrain and the at least one other property after degradation occurs; analyzing the recorded microstrain data against the baseline data and / or an adjusted range of the baseline data to assess the seal life at the time after the operation was initiated as a percentage of seal life less than 100%; A method comprising:

2. The method of claim 1, wherein the valve assembly is one of a valve assembly with a door, a pendulum valve assembly, and an isolation valve assembly.

3. The method of claim 2, wherein the valve assembly is a valve assembly with a door, the door configured to cover an opening in a process chamber, the valve assembly further comprising a valve for operating the door from the open position to the closed position, and the seal contacting the door.

4. The method of claim 3, further comprising installing at least one of the at least one micro-strain sensor on an exterior surface of the door.

5. The method described in claim 4, wherein initiating operation of the valve assembly includes initiating a vacuum process when the door is in the closed position.

6. The method of claim 5, further comprising evaluating the seal life at the time after the vacuum process is initiated as a percentage of the seal life that is less than 100%.

7. The method described in claim 3, wherein the movable valve door is a joint slit valve or a check valve.

8. The method described in claim 7, wherein the movable valve door is a jointed slit valve.

9. The method of claim 3, wherein the seal is mechanically affixed to the surface of the door.

10. The method described in claim 3, wherein there are two or more sensors for measuring micro-strains, and each of the two or more sensors is positioned at a different location on the door.

11. The method described in claim 10, wherein the sensor is bonded to an exterior surface of the door.

12. The method of claim 10, wherein one or more strain gauge rosette patterns are positioned on the door.

13. The method of claim 12, wherein there are two or more strain gauge rosette patterns, which are positioned in different locations.

14. The method of claim 1, wherein the baseline data is stored and incorporated into a database to predict seal life for certain types of doors and seals in a particular process.

15. The method of claim 1, wherein at least one sensor is a strain gauge.

16. The method of claim 1, wherein the at least one other characteristic is selected from one or more of temperature, humidity, and vibration, and monitoring of such operating conditions is used to compensate for ambient noise.

17. The method of claim 1, wherein at least one sensor is installed to measure each of the at least one other characteristic.

18. The method of claim 1, wherein the micro-strain data of the strain gauge is converted into a digital signal through the use of a circuit including a Wheatstone bridge for converting the micro-strain data into a change in voltage, the circuit conditions an analog signal from the measured change in voltage and converts the analog signal into the digital signal, and the Wheatstone bridge incorporates high precision resistors having a tolerance of 0.25% or less.

19. The method of claim 18, wherein the circuit is incorporated into a printed circuit board.

20. The method of claim 18, wherein the circuit comprises an amplifier.

21. The method of claim 1, wherein the baseline data is measured after calibrating the valve assembly.

22. The method of claim 1, wherein the baseline data is measured after the valve assembly is in an operating state and the valve is under pressure, based in part on initial microstrain data.

23. The method of claim 1, wherein the baseline data is measured when a load is applied to the valve and then removed, based at least in part on initial microstrain data.

24. A system for analyzing seal life, comprising: at least one memory for storing computer-executable instructions; at least one processing unit for executing the computer-executable instructions stored in the memory; Equipped with Execution of the computer-executable instructions includes: engaging a valve assembly movable from an open position to a closed position to operate the valve assembly, the valve assembly including a seal, the seal having elastomeric properties, the seal secured within the valve and in contact with a surface of the valve assembly, and pressure being applied to the valve assembly during operation, the seal being subject to deterioration; receiving a signal from a change in voltage from a circuit in communication with at least one sensor for measuring microstrain and at least one sensor for measuring at least one other characteristic related to ambient conditions of operation or related to degradation of the seal on or within the valve assembly; recording microstrain data and data related to the at least one other characteristic at a time after operation of the valve assembly is initiated; generating baseline data by measuring the microstrain and the at least one other characteristic of the seal before degradation occurs, corresponding to 100% seal life, and generating an adjusted range of baseline data by again measuring the microstrain and the at least one other characteristic after degradation occurs; analyzing the recorded data against the baseline data and / or an adjusted range of the baseline data to assess seal life at a time after operation of the valve assembly begins as a percentage of seal life less than 100%; and programming the at least one processing unit to perform operations including:

25. The system described in claim 24, wherein the valve assembly is one of a valve assembly with a door, a pendulum valve assembly, and an isolation valve assembly.

26. A method for monitoring seal life, said method comprising: providing a valve assembly movable from an open position to a closed position, the valve assembly including a seal, the seal having elastomeric properties, fixed within the valve assembly and in contact with a surface of the valve assembly, the seal undergoing degradation when the seal is in operation, the valve assembly being one of a valve assembly with a door, a pendulum valve assembly, and an isolation valve assembly; providing at least one sensor for measuring microstrain and at least one sensor for measuring at least one other characteristic related to ambient conditions of operation or related to degradation of the seal on or within the valve assembly; placing the valve assembly in an operational state where the seal is subject to degradation and initiating operation of the valve assembly, wherein initiating operation of the valve assembly includes initiating a vacuum process when the valve assembly is in the closed position; recording micro-strain data and data related to the at least one other characteristic at a time after the operation is initiated; generating baseline data by first measuring the microstrain and the at least one other property of the seal before degradation occurs, corresponding to 100% seal life, and generating an adjusted range of baseline data by again measuring the microstrain and the at least one other property after degradation occurs; analyzing the recorded microstrain data against the baseline data and / or an adjusted range of the baseline data to assess the seal life at the time after the operation was initiated as a percentage of seal life less than 100%; A method comprising:

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