A sensor arrangement and a method for monitoring a status of a technical facility

Abstract

A sensor arrangement and a method for monitoring a status of a technical facility, the sensor arrangement comprising a mechanical actuator, at least one acoustic vibration sensor and a processing unit operationally connected to the acoustic vibration sensor.

Description

[0001] A SENSOR ARRANGEMENT AND A METHOD FOR MONITORING A STATUS

[0002] OF A TECHNICAL FACILITY

[0003] TECHNICAL FIELD OF THE INVENTION

[0004] The invention addressed herein relates to the technical field of measuring and testing. Specifically, the invention may be used in the technical field of monitoring the status of a technical facility, in particular of a vacuum deposition device. In a specific application, the invention relates to the field of semiconductor fabrication. More specifically, the invention relates to an apparatus for monitoring material deposition on a wall of a device, for monitoring the status of the wall itself, and to a method for such monitoring.

[0005] BACKGROUND OF THE INVENTION

[0006] As an illustrative example of technological relevance, wafer processing tools used in semiconductor manufacturing suffer from accumulation of deposits, i.e. byproduct buildup, on the chamber walls of a vacuum deposition chamber. From time to time the chamber walls need to undergo a cleaning process. Information on the appropriate time for the next cleaning process is valuable, as too frequent cleaning increases downtime of the facility, and too late cleaning involves the risk of, e.g., buildup flaking off during processing, resulting in particle contamination and yield loss as well as impacting other process parameters (e.g., film deposition thickness) . Quartz crystal microbalance (QCM) sensors have been used to monitor deposition inside various facilities. A QCM has extremely high sensitivity, but it must come in contact with the media inside the device under test. I.e., it needs to be mounted on the inside of the device under test, e.g. inside a pipe, duct or processing chamber. QCM's are not suitable to monitor gross phenomena, such as deposition of layer thickness in the order of millimeters or centimeters of deposition. QCM's are not suitable for cases, where liquids or sludges are present. QCM based sensors are limited to monitoring relatively low amounts of material, typically, at maximum microns of deposited layer. In addition, sensors based on QCM technology are highly localized and measure mass change at the active area of the quartz crystal only.

[0007] The object of the invention is a device or a method, which avoids or at least reduces problems of the state of art. More specifically, an object of the present invention is to provide an alternative device or an alternative method for monitoring the status of a device with respect to material deposition on its interior walls, volume changes inside the device, damages in the device's housing, etc.

[0008] SUMMARY OF THE INVENTION

[0009] This object is solved in a first aspect by a sensor arrangement with the features of claim 1, in a second aspect by a method with the features of claim 6, and in a third aspect by a device with the features of claim 12. Further embodiments of the sensor arrangement, the method and the device are defined by the features of the dependent claims .

[0010] In a first aspect , the invention is directed to a sensor arrangement .

[0011] In one embodiment of the sensor arrangement , which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the sensor arrangement comprises a mechanical actuator configured to provide a physical strike on an obj ect , at least one acoustic vibration sensor configured to measure an acoustic vibration signal of the obj ect , the acoustic vibration signal in particular resulting from the physical strike on the obj ect , and a processing unit operationally connected to the acoustic vibration sensor and configured to analyse data from the at least one acoustic vibration sensor .

[0012] For example , the mechanical actuator may be any obj ect configured to provide a physical strike , such as a hammer, an electric actuator, a linear actuator, a pneumatic, actuator, a hydraulic actuator, or generally speaking any device that uses a power source to attain a physical movement . The acoustic vibration sensor which may be physically connected, e . g . via an electric wire or a glass fibre , to the processing unit , may be any sensor configured to measure the frequency and / or amplitude of an acoustic vibration, and, e . g . by means of a processing unit operationally connected to the sensor, analyze data measurable by the acoustic vibration sensor, such as for example a change in frequency and / or amplitude over time . In an embodiment , the sensor arrangement may also comprise more than one mechanical actuator, more than one vibration sensor and / or more than one processing unit .

[0013] In another embodiment of the sensor arrangement , which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the acoustic vibration sensor comprises or is a microphone , a piezo electric accelerometer, a capacitance vibration sensor, or a mechanical vibrometer .

[0014] In another embodiment of the sensor arrangement , which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the acoustic vibration sensor is configured to digiti ze the acoustic vibration signal . In an embodiment of the invention, the acoustic vibration sensor and / or the processing unit are further configured to weight a digiti zed acoustic vibration signal using an appropriate apodi zation function . In another embodiment , the acoustic vibration sensor and / or the processing unit are configured to perform a Fourier trans formation of an acoustic vibration signal and / or to measure its principal frequency and harmonics . In an especially compact and space-saving embodiment of the sensor arrangement , the mechanical actuator and the acoustic vibration sensor, the acoustic vibration sensor and the processing unit , or mechanical actuator and the processing unit are accommodated in a common casing .

[0015] In another embodiment of the sensor arrangement , which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the processing unit is configured to perform a Fourier Trans formation, in particular a Fast Fourier Trans formation ( FFT ) , further in particular of a transient acoustic vibration signal .

[0016] In another embodiment of the sensor arrangement , which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the mechanical actuator, at least one acoustic vibration sensor, and optionally the processing unit , are arranged in a common sensor unit , which sensor unit is mountable or mounted in a direct contact with the obj ect and outside the obj ect , in particular in a direct contact with at least a part of a housing of a device , further in particular to the housing of a processing chamber, a vacuum deposition device , optionally a processing and / or vacuum chamber of a vacuum deposition device , a reactor, a pipe or a duct of a vacuum deposition device , a tank, or a glovebox .

[0017] In a second aspect , the invention is directed to a method for monitoring a status of an obj ect , in particular a device , further in particular inside the device , and / or for monitoring a status of a housing of the device , the housing of the device defining an inner volume as the inside .

[0018] In an embodiment of the method, which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the method comprises or consists of the following steps , in particular in the given order : a) providing a sensor arrangement according to one of the claims 1 to 5, b) arranging the mechanical actuator in a physical contact with at least a part of the object, in particular the housing of the device, and outside the device, c) providing a physical strike to at least a part of the object, in particular the housing of the device, by the mechanical actuator, d) measuring an acoustic vibration signal, in particular a transient acoustic vibration signal, emitted by at least a part of the object, in particular the housing of the device, after the physical strike has been provided to at least a part of the object, in particular the housing, wherein the measuring is performed by the acoustic vibration sensor, and e) determining if the acoustic vibration signal, in particular the transient acoustic vibration signal, differs from a reference acoustic vibration signal, in particular a reference transient vibration signal.

[0019] In an embodiment of the method, the arranging of the mechanical actuator is either a loose arranging without the use of any fixing elements, such as screws, sleeves, clamps or welds, or a fixed arranging, for example a mounting using fixing elements. Since the arranging of the mechanical actuator in step b) is performed outside the device, i.e. not within the inner volume of the device, no opening of the device is necessary . The latter is particularly advantageous in case of monitoring a device under vacuum, a device having an inside sensitive to contamination, or a device in which hazardous or sensitive compounds are handled .

[0020] In step e ) it is determined i f the acoustic vibration signal , in particular being a transient acoustic vibration signal , has di f ferent properties ( e . g . frequency, vibration amplitude , or vibration amplitude decay) than a reference acoustic vibration signal . In an embodiment of the method, the reference acoustic vibration signal is obtained by performing the method steps a ) -d) according to any of the method embodiments described herein, however at an earlier point of time than performing the same method steps for the ( actual ) measurement of the acoustic vibration signal . It should be noted that the measurement of the acoustic vibration signal and the reference acoustic vibration signal should be performed with respect to the same device , preferably at the same position of the housing of the device , and preferably but not mandatory using the same sensor arrangement .

[0021] In another embodiment of the method, which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, providing the physical strike in step c ) generates a transient acoustic vibration of at least a part of the obj ect , in particular the housing of the device . In another embodiment of the method, which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the determining of step e ) comprises digiti zing the measured acoustic vibration signal of step d) , optionally apodi zing and Fourier trans forming the digiti zed acoustic vibration signal .

[0022] In another embodiment of the method, which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the determining of step e ) comprises determining a frequency of the measured acoustic vibration signal of step d) .

[0023] In an embodiment of the method, the frequency of the measured acoustic vibration signal , in particular transient acoustic vibration signal , is in step e ) compared with the frequency of the reference acoustic vibration signal , in particular reference transient acoustic vibration signal . In an embodiment of the method, a di f ference between these two parameters is used to measure and / or monitor changes in the weight of the device .

[0024] In another embodiment of the method, which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the determining of step e ) comprises determining a vibration amplitude decay of the measured acoustic vibration signal , in particular a vibration amplitude decay of a Fourier trans formed acoustic vibration signal from step d) .

[0025] In an embodiment of the method, a vibration amplitude decay of the measured acoustic vibration signal , in particular transient acoustic vibration signal , is in step e ) compared with the vibration amplitude decay of the reference acoustic vibration signal , in particular reference transient acoustic vibration signal . In an embodiment of the method, a di f ference between these two parameters is used to measure and / or monitor changes in the mounting of the device , changes in vibration dampening elements , and / or the appearance of cracks in the housing of the device .

[0026] In another embodiment of the method, which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the determining of step e ) comprises or consists of comparing a frequency of the measured acoustic vibration signal of step d) with a frequency of the reference acoustic vibration signal and / or comparing a vibration amplitude decay of the measured acoustic vibration signal of step d) with a vibration amplitude decay of the reference acoustic vibration signal .

[0027] In another embodiment of the method, which may be combined with any other embodiments and / or aspects already addressed or still to be addressed, unless in contradiction, the determining of step e ) comprises or consists of comparing an intensity of harmonics of the measured acoustic vibration signal of step d) with the intensity of harmonics of the reference acoustic vibration signal .

[0028] The inventors have found that relative changes in the intensity of harmonics surprisingly carry additional information pertaining to locali zation and / or physical state of device changes , e . g . locali zed or distributed deposition inside the device , pipes , the consistency of the deposit , cracks in pipe walls , etc .

[0029] In a third aspect , the invention is directed to a device comprising the sensor arrangement according to one of the claims 1 to 5 .

[0030] In an embodiment of the method according to the present invention, which may be combined with any of the embodiments of the method preaddressed or still to be addressed unless in contradiction, the method further comprises step f ) of determining at least one of : changes in the rigidity of the device , in particular the detection of cracks in the device , changes in the chemical composition of the device or of parts of the device , in particular corrosion, and accumulation of material inside the device , in particular in the inner volume of a vacuum deposition device , in particular on the inner wall side of the housing, or of tubing connected within or to the device .

[0031] In a fourth aspect , the invention is directed to a use of the sensor arrangement and / or the method, both according to any of the addressed or still to be addressed embodiments , for monitoring the status of a technical facility, such as for example a processing chamber, a vacuum deposition device , optionally a processing and / or vacuum chamber of a vacuum deposition device , a reactor, a pipe or a duct of a vacuum deposition device , a tank, or a glovebox . In particular, the sensor arrangement or the method may be used in the context of semiconductor manufacturing, for example to avoid running a semiconductor production facility when a precursor ampoule is empty, to monitor deposition and / or clogging inside an exhaust line of a semiconductor production facility, to monitor internal corrosion of a semiconductor production facility, etc .

[0032] The features of the above-mentioned embodiments of the sensor arrangement , the method, the device and the use can be applied in any combination within the scope of the claims , unless in contradiction . Also , the features of the above-mentioned aspects can be used in any combination, provided they do not contradict each other .

Claims

CLAIMS1 . A sensor arrangement comprising a mechanical actuator configured to provide a physical strike on an obj ect , at least one acoustic vibration sensor configured to measure an acoustic vibration signal of the obj ect , and a processing unit operationally connected to the acoustic vibration sensor and configured to analyse data from the at least one acoustic vibration sensor .2 . The sensor arrangement according to claim 1 , wherein the acoustic vibration sensor comprises or is a microphone , a piezo electric accelerometer, a capacitance vibration sensor, or a mechanical vibrometer .3 . The sensor arrangement according to claim 1 or 2 , wherein the acoustic vibration sensor is configured to digiti ze the acoustic vibration signal .4 . The sensor arrangement according to one of the claims 1 to 3 , wherein the processing unit is configured to perform a Fourier Trans formation, in particular a Fast Fourier Trans formation ( FFT ) , further in particular of a transient acoustic vibration signal .

5. The sensor arrangement according to one of the claims 1 to 4, wherein the mechanical actuator, at least one acoustic vibration sensor, and optionally the processing unit, are arranged in a common sensor unit, which sensor unit is mountable or mounted to the object, in particular at least a part of a housing of a device.

6. A method for monitoring a status of an object, in particular a device, further in particular inside the device, and / or for monitoring a status of a housing of the device, the housing of the device defining an inner volume as the inside, the method comprising or consisting of the following steps, in particular in the given order: a) providing a sensor arrangement according to one of the claims 1 to 5, b) arranging the mechanical actuator in a physical contact with at least a part of the object, in particular the housing of the device, and outside the device, c) providing a physical strike to at least a part of the object, in particular the housing of the device, by the mechanical actuator, d) measuring an acoustic vibration signal, in particular a transient acoustic vibration signal, emitted by at least a part of the object, in particular the housing of the device, after the physical strike has beenprovided to at least a part of the object, in particular the housing, wherein the measuring is performed by the acoustic vibration sensor, and e) determining if the acoustic vibration signal, in particular the transient acoustic vibration signal, differs from a reference acoustic vibration signal, in particular a reference transient vibration signal.

7. The method according to claim 6, wherein providing the physical strike in step c) generates a transient acoustic vibration of at least a part of the object, in particular the housing of the device.

8. The method according to claim 6 or 7, wherein the determining of step e) comprises digitizing the measured acoustic vibration signal of step d) , optionally apodizing and Fourier transforming the digitized acoustic vibration signal.

9. The method according to one of the claims 6 to 8, wherein the determining of step e) comprises determining a frequency of the measured acoustic vibration signal of step d) .

10. The method according to one of the claims 6 to 9, wherein the determining of step e) comprises determining a vibration amplitude decay of themeasured acoustic vibration signal , in particular a vibration amplitude decay of a Fourier trans formed acoustic vibration signal from step d) .11 . The method according to one of the claims 6 to 10 , wherein the determining of step e ) comprises or consists of comparing a frequency of the measured acoustic vibration signal of step d) with a frequency of the reference acoustic vibration signal and / or comparing a vibration amplitude decay of the measured acoustic vibration signal of step d) with a vibration amplitude decay of the reference acoustic vibration signal .12 . A device comprising the sensor arrangement according to one of the claims 1 to 5 .13 . The method according to one of the claims 6 to 11 , or the device according to claim 12 , wherein the device is a processing chamber, a vacuum deposition device , in particular a processing and / or vacuum chamber of a vacuum deposition device , a reactor, a pipe or a duct of a vacuum deposition device , a tank, or a glovebox .