Vibration sensor and measurement method

Abstract

A hollow device comprising a hollow interior and at least one vibration sensor configured to measure a vibration of the device or of a component of the device. The at least one vibration sensor is positioned outside the interior of the device and the hollow device is, for example, a pipe, a tube, a duct, a container or a treatment chamber. Associated methods for measuring a vibration of a device or of a component of a device are also disclosed.

Description

[0001] VIBRATION SENSOR AND MEASUREMENT METHOD

[0002] TECHNICAL FIELD

[0003] 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.

[0004] BACKGROUND OF THE INVENTION

[0005] 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.

[0006] DESCRIPTION OF THE INVENTION

[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 alternative means or an alternative method for monitoring the status of a device with respect to the status of its components and / or material deposition on its components .

[0008] This task is solved by a device with the features of claim 1. Further embodiments of the device, as well as a corresponding method are defined by the features of further claims . In a first aspect , the present invention is directed to a hollow device comprising a hollow interior, in particular an interior to be evacuated, and at least one vibration sensor configured to measure a vibration of the device or of a component of the device , wherein the at least one vibration sensor is positioned outside the interior of the device , wherein the hollow device is in particular selected from the group consisting of a pipe , a tube , a duct , a container and a treatment chamber .

[0009] The hollow device can be any obj ect that comprises a hollow section . Examples of such hollow devices include pipes , tubes , ducts , containers or more complex bodies such as treatment chambers and / or devices , for example vacuum treatment or vacuum deposition chambers and / or devices . The hollow device as used herein comprises a housing, walls or other structural elements that at least partially define a hollow volume . The term "hollow interior" or "hollow volume" refers to any space within the device . For example , i f the hollow device comprises an interior to be evacuated, the hollow interior extends to any spaces that are fluidly connected to the hollow interior within the device , e . g . by tubing, that can be evacuated, too . Therefore , the hollow interior in this case is the "vacuum side" of the device and all other spaces outside the interior are the exterior of the device under atmospheric pressure . The hollow device may be made of any solid material or mixture of materials, for example from metal, plastic or glass.

[0010] The vibration sensor is not necessarily physically connected to the hollow device. It may be detachable and may be positioned at any given position outside of the hollow device. In particular in the example of a hollow device with an interior to be evacuated, "outside" refers to the atmospheric pressure side of the hollow device, i.e. not the interior to be evacuated. It is noted, however, that the "outside" in more complex devices may refer to a position on the hollow device that can be covered by other structural elements, e.g. a dust cover, as long as this position is not in an evacuated space of the hollow device. The vibration sensor may be positioned such that it is in physical contact with the hollow device or such that it is not in physical contact with the hollow device as long as it can measure a vibration emitted by the hollow device or by a component of the hollow device.

[0011] If not explicitly stated otherwise, the term "device" as used herein refers to the hollow device.

[0012] As used herein a "component of the device" refers to a part of the hollow device. Hence, the sensor can be configured to measure a vibration of the entire hollow device (i.e. of the device) , or the vibration of a selected part of the hollow device. The sensor can be, e.g., configured to measure either a vibration of the entire hollow device or of a part of the hollow device by its positioning and by the number of sensors used to measure a vibration. For example, the sensor can measure the frequency and / or amplitude of the vibration, and, e.g. by means of a processing unit operably connected to the sensor, measure a change in frequency, vibration amplitude and / or intensity of harmonics over time.

[0013] It was surprisingly found that the device of the present invention including the sensor allows for the determination of changes to the device's mass and mechanical dampening properties due to, e.g., internal deposition of materials, corrosion, ablation, or cracking of the device or components thereof. These changes can be captured, in particular, due to changes in the resonance frequency spectrum that evolves over time vs. a base line resonance of the device. Vibrations may be monitored at multiple locations along the hollow device (e.g. along pipes, ducts, or chambers) enabling a higher resolution and the localization of changes to the device. In particular in the context of vacuum deposition devices, a side product of the deposition process is the deposition of materials on parts of the device such as the interior walls, ducts, pipes, etc., which can be monitored with the sensor described herein, e.g. to determine when cleaning of the device is needed. Further details are provided in the context of the method disclosed herein, further below.

[0014] In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the hollow device is a vacuum deposition device comprising an interior volume to be evacuated .

[0015] For the purposes of the present invention, the interior volume may extend from a processing chamber to tubing that is used to evacuate the processing chamber .

[0016] In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the at least one vibration sensor is configured to measure a mechanical vibration and / or an acoustic vibration signal emitted by the device or by a component of device .

[0017] For the purposes of the present invention, the term "vibration" includes mechanical vibrations and acoustic vibrations .

[0018] In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the mechanical vibration and / or an acoustic vibration signal emitted by the device is caused by a component of the device , in particular by a vibration source of the device , in particular by moving mechanical parts , in particular by an exhaust fan, a vacuum pump, and / or a valve of the device .

[0019] The vibration of the hollow device that is measured by the sensor can be , in principle , caused, i . e . induced, by any means , e . g . external means or means that are part of the device . In an example , the means that induce the vibrations are part of the device in its operating state , such as pumps , fans , valves , etc . , which are , e . g . , functional parts of the device .

[0020] In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the at least one vibration sensor is in physical contact with the device or is not in physical contact with the device .

[0021] As mentioned above , the senor may be detachable from the hollow device in order to be repositioned or in order to measure a vibration remotely, i . e . while not being attached to the device .

[0022] In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the at least one vibration sensor is selected from the group consisting of a piezo electric accelerometer, a capacitance vibration sensor, a mechanical vibrometer and a microphone .

[0023] The skilled person can select a suitable sensor, e . g . according to the frequency that should be measured or according to the position on the device at which the measurement should take place . In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the device further comprises a processing unit for analyzing data from the at least one vibration sensor .

[0024] The processing unit can be operably connected to the sensor while the measurement is in progress and it can be used to record and process measurement data, e . g . according to known procedures in the art of vibration / sound recording .

[0025] In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the hollow device is a vacuum deposition device and the interior volume to be evacuated is formed by a processing chamber of the device , and the device further comprises at least one of : a housing comprising the processing chamber, a vacuum pump, in particular a vacuum pump connected to the processing chamber, in particular by tubing, an exhaust fan, in particular an exhaust fan connected to the processing chamber, in particular by tubing, and valves .

[0026] The sensor can be , e . g . positioned on the atmospheric side of the housing, the vacuum pump tubing or the exhaust fan tubing . The vacuum pump, the exhaust fan and / or the valves can serve to cause the vibration that will be measured by the sensor . In an embodiment of the hollow device according to the present invention, which may be combined with any of the embodiments of the hollow device preaddressed or still to be addressed unless in contradiction, the hollow device is a vacuum deposition device and the vibration sensor is configured to measure a vibration of the housing, of a part of the housing, of the vacuum pump tubing, of the exhaust fan tubing, or of a combination thereof .

[0027] In another aspect which may be combined with any of the embodiments or aspects preaddressed or still to be addressed unless in contradiction, the present invention is directed to a method for measuring a vibration of a device or of a component of a device , the method comprising the following steps :

[0028] ( a ) providing a hollow device as defined herein, and

[0029] (b ) measuring, in particular recording, a vibration of the device or of a component of the device with the at least one vibration sensor .

[0030] All definitions and explanations provided above in the context of the hollow device also apply to the method disclosed herein, and vice versa .

[0031] As noted above , an exhaust fan, a vacuum pump, or (mechanical ) valves , or any other ( existing or added) means can be the means that cause the vibrations which are present in the device . Preferably, the means cause a stable and / or continues vibration . For example , transient vibrations are excited in the device during the "natural" operation of the device, e.g. due to vacuum systems which require vacuum pumps, isolation valves and other moving parts. Resulting vibrations are measured using the sensor described herein, e.g. a microphone or vibration sensor (e.g. a piezo electric accelerometer, a capacitance vibration sensor, or a mechanical vibrometer) . The measurement signal is received by the sensor and vibrations are measured and optionally recorded. Recorded measurement signals can be, e.g., digitized and analyzed by using a rolling time window or using fixed time bins, e.g. by the processing unit operably connected to the sensor as described herein. The measurement signal in the window can be weighted using an appropriate apodization function, and the apodized signal can be converted from a time domain into a frequency domain using Fast Fourier Transform (FFT) . Principal frequency and harmonics can be measured, and peak shapes can be analyzed. The results can be used to create a sonogram, and neighboring "snapshots" can be averaged to improve a signal-to-noise ratio. Also, a reference response, i.e. a base line vibration of the device, can be recorded when the device under test is in a known state (e.g., immediately after installation when "new" or in a well-defined condition) . Changes in the frequency spectrum can be used to measure and monitor changes in device weight (due to internal deposition, corrosion / ablation, and / or cracks and mechanical failures) . Changes in the spectrum of the vibration frequencies (peak shapes) can be used to measure and monitor changes in vibration dampening elements, and appearance of cracks. Relative changes in the intensity of harmonics carry additional information pertaining to localization and / or physical state of device changes (e.g., localized or distributed deposition inside pipes, hard or "fluffy" deposits, cracks in pipe walls, deterioration of system mounts etc.) .

[0032] 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 after step (a) and before step (b) further includes the step (al) of positioning the at least one vibration sensor on the device such that the sensor measures a vibration of a component of interest of the device.

[0033] As noted above, the sensor can be, e.g. positioned on the atmospheric side of the housing, the vacuum pump tubing or the exhaust fan tubing.

[0034] 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, step (b) is continuously carried out during a period of time, in particular over a time period of 1 second to 1 week, to determine a change in the vibration measured by the at least one sensor during the period of time. 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 (bO ) of measuring and storing a base line vibration of the device or of a component of the device with the at least one vibration sensor before step (b ) is carried out .

[0035] 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 device comprises a processing unit , and the method further comprises the step of processing the vibration measured with the at least one vibration sensor, in particular to create a sonogram which is optionally compared to the base line vibration of the device or of a component of the device measured in step (bO ) .

[0036] 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 ( c ) 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 in the hollow interior, in particular in the interior volume of a vacuum deposition device , in particular on structural elements forming the hollow interior or positioned within the hollow interior, or of tubing connected within or to the device .

[0037] In another aspect which may be combined with any of the embodiments or aspects preaddressed or still to be addressed unless in contradiction, the present invention is directed to a use of the vibration sensor as defined herein in the method defined herein .

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Embodiments of the current invention are described in more detail in the following with reference to the figures .

[0040] These are for illustrative purposes only and are not to be construed as limiting . It shows

[0041] Fig . 1 a side view of an exemplary device ;

[0042] Fig . 2 a side view of an exemplary device ;

[0043] Fig . 3 a side view of an exemplary device ;

[0044] Fig . 4 an exemplary flow chart of a method .

[0045] DETAILED DESCRIPTION OF THE INVENTION Figure 1 is a side view of an exemplary device 1 comprising a hollow interior 2 and at least one vibration sensor 3. The vibration sensor 3 is positioned on the outside of the device, i.e. outside the interior 2 of the device 1. The device 1 can be, e.g. a vacuum processing device. In the hollow interior 2 of the device 1, there can be a deposition 4 of materials. The component with numeral 4 can also represent corrosion, ablation, or cracking of the device or components thereof. The sensor 3 may be positioned such that it is in physical contact with the device 1 or such that it is not in physical contact with the device 1 as long as it can measure a vibration emitted by the device 1. The sensor 3 is configured to measure a vibration of the device 1 or of a component of the device (e.g. a side wall) , and can determine the frequency and / or amplitude of the vibration, and, e.g. by means of a processing unit operably connected to the sensor (not shown) , measure a change in frequency, vibration amplitude and / or intensity of harmonics over time. Thereby, the sensor 3 can determine the presence and extent of deposition 4 of materials, corrosion, ablation, or cracking of the device or components thereof.

[0046] Figure 2 is a perspective view of an exemplary device 1, wherein the device 1 is a tube, pipe, or duct, for example of a vacuum treatment or vacuum deposition chamber and / or device. The explanations provided above for Figure 1 apply mutatis mutandis for the device shown in Figure 2.

[0047] Figure 3 is a side view of an exemplary device 1 wherein the sensor 3 is positioned on a tube, pipe, or duct of a vacuum treatment or vacuum deposition chamber . Multiple devices can be positioned at di f ferent locations on the device , e . g . depending on where a deposition should be determined (not shown) .

[0048] Figure 4 is a flowchart of an exemplary method disclosed herein . In a first step A, a hollow device as defined herein is provided . In optional step Al , the vibration sensor can be positioned on the device such that the sensor measures a vibration of a component of interest of the device , in particular i f the device and the sensor are provided separately . In subsequent step B, a vibration of the device or of a component of the device is measured, in particular recorded, with the vibration sensor . Optionally, a base line vibration of the device or of a component of the device can also be measured and stored with the sensor before step B is carried out . In optional step C, at least one of the following can be determined : 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 / or accumulation of material in the hollow interior, in particular in the interior volume of a vacuum deposition device , in particular on structural elements forming the hollow interior or positioned within the hollow interior, or of tubing connected within or to the device . Also , but not necessarily, the skilled person can carry out step X of determining whether the device comprises suf ficient deposition, corrosion or cracking that would require cleaning or repair of the device .

Claims

1. CLAIMS1. A hollow device (1) comprising a hollow interior (2) , in particular an interior to be evacuated, and at least one vibration sensor (3) configured to measure a vibration of the device or of a component of the device, wherein the at least one vibration sensor is positioned outside the interior of the device, wherein the hollow device is in particular selected from the group consisting of a pipe, a tube, a duct, a container and a treatment chamber.

2. The hollow device (1) according to claim 1, wherein the hollow device is a vacuum deposition device comprising an interior volume (2) to be evacuated.

3. The hollow device (1) according to claim 1 or 2, wherein the at least one vibration sensor (3) is configured to measure a mechanical vibration and / or an acoustic vibration signal emitted by the device or by a component of device.

4. The hollow device (1) according to any of claims 1 to3, wherein the mechanical vibration and / or an acoustic vibration signal emitted by the device is caused by a component of the device, in particular by a vibration source of the device, in particular by movingmechanical parts, in particular by an exhaust fan, a vacuum pump, and / or a valve of the device.

5. The hollow device (1) according to any of claims 1 to4, wherein the at least one vibration sensor (3) is in physical contact with the device or is not in physical contact with the device.

6. The hollow device (1) according to any of claims 1 to5, wherein the at least one vibration sensor (3) is selected from the group consisting of a piezo electric accelerometer, a capacitance vibration sensor, a mechanical vibrometer and a microphone.

7. The hollow device (1) according to any of claims 1 to6, wherein the device further comprises a processing unit for analyzing data from the at least one vibration sensor (3) .

8. The hollow device (1) according to any of claims 2 to 7, wherein the hollow device is a vacuum deposition device and wherein the interior volume (2) to be evacuated is formed by a processing chamber of the device, and wherein the device further comprises at least one of: a housing comprising the processing chamber, a vacuum pump, in particular a vacuum pump connected to the processing chamber, in particular by tubing,an exhaust fan, in particular an exhaust fan connected to the processing chamber, in particular by tubing, and valves .

9. The vacuum deposition device (1) according to claim 8, wherein the vibration sensor (3) is configured to measure a vibration of the housing, of a part of the housing, of the vacuum pump tubing, of the exhaust fan tubing, or of a combination thereof.

10. A method for measuring a vibration of a device or of a component of a device, the method comprising the following steps:(a) providing a device (1) as defined in any of claims 1 to 9, and(b) measuring, in particular recording, a vibration of the device or of a component of the device with the at least one vibration sensor (3) .

11. The method according to claim 10, wherein the method after step (a) and before step (b) further includes the step (al) of positioning the at least one vibration sensor (3) on the device (1) such that the sensor measures a vibration of a component of interest of the device.

12. The method according to claim 10 or 11, wherein step (b) is continuously carried out during a period of time, in particular over a time period of 1 second to 1 week, to determine a change in the vibration measured by the at least one sensor (3) during the period of time.

13. The method according to any of claims 10 to 12, wherein the method further comprises step (bO) of measuring and storing a base line vibration of the device (1) or of a component of the device with the at least one vibration sensor (3) before step (b) is carried out.

14. The method according to any of claims 10 to 13, wherein the device (1) comprises a processing unit, and wherein the method further comprises the step of processing the vibration measured with the at least one vibration sensor (3) , in particular to create a sonogram which is optionally compared to the base line vibration of the device or of a component of the device measured in step (bO) .

15. The method according to any of claims 10 to 14, wherein after step (b) , the method further comprises step (c) of determining at least one of: changes in the rigidity of the device (1) , 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 in the hollow interior ( 2 ) , in particular in the interior volume of a vacuum deposition device , in particular on structural elements forming the hollow interior or positioned within the hollow interior, or of tubing connected within or to the device .16 . A use of the vibration sensor ( 3 ) as defined in any of claims 1 to 9 in the method defined in any of claims 10 to 15 .

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