RF based temperature sensor unit, RF receiver antenna unit and vacuum coating system comprising both units

Abstract

A RF based temperature sensor unit and a RF receiver antenna unit for usage within a vacuum coating system the RF based temperature sensor unit comprising an antenna assembly having an antenna wire and an antenna body; and a temperature sensor assembly having a temperature sensor and a temperature sensor body and configured to be coupled to the antenna wire, wherein the antenna body comprises a bore extending in longitudinal direction of the antenna body, wherein a proximal part of the antenna wire is accommodated within the bore and a distal part of the antenna wire extends outside the bore, wherein a proximal end of the proximal part of the antenna wire is surrounded by an electrical insulator coupled to the temperature sensor.

Description

[0001] Oerlikon Surface Solutions AG, Pfaffikon

[0002] OEROlOl.PCT

[0003] RF based temperature sensor unit, RF receiver antenna unit and vacuum coating system comprising both units

[0004] Technical Field

[0005] The present invention relates to a RF based temperature sensor unit for temperature sensing in a vacuum coating process, to a RF receiver antenna unit for contactless receiving a signal from the RF based temperature sensor unit, and to a vacuum coating system in which both RF based temperature sensor unit and RF receiver antenna unit are provided.

[0006] State of the Art

[0007] When performing a PVD and / or CDV coating process, it is often important to control a substrate temperature, for example, if temperature-sensitive substrates are to be provided with a functional coating or if the temperature existing during the coating process influences the properties of a layer material.

[0008] For temperature sensing in a vacuum coating process, it is known to use a SAW (Surface Acoustic Wave)-device which is attached to components or parts to be coated which typically move in a process chamber of a vacuum coating system relatively to static coating sources within the process chamber. The SAW-device can be used as a temperature sensing element by detecting its shift in resonance frequency with temperature, which is caused by the thermal expansion of the SAW-device. The shift of the resonance frequency is directly correlated with the temperature of the SAW-device and is correspondingly a measure of the temperature of the component to which it is attached.

[0009] Such SAW-device is electrically coupled to a RF antenna receiving a RF signal emitted from a static antenna within the vacuum chamber and inducing a current in the electrical circuit of the Oerlikon Surface Solutions AG, Pfaffikon

[0010] OEROlOl.PCT

[0011] SAW-device and the RF antenna. The RF antenna is typically further in communication with a RF receiver antenna within the vacuum chamber for transmitting a signal indicative of the shift of resonance frequency and, thus, of the temperature if the signal has been appropriately calibrated offline at predetermined temperature levels.

[0012] For correctly controlling the temperature in a PVD and / or CDV coating process, it is necessary to sense the temperature as accurately as possible. However, in vacuum coating processes, a temperature sensor such as the above SAW-device provided in the vacuum chamber is exposed to coating vapor and a film of layer material grows and deposits, respectively, on it, which impairs electrical coupling, for example also capacitive and / or inductive coupling between the RF antenna and a temperature sensor, which in turn generates RF signal loss resulting in lower signal-to-noise ratio levels determining the accuracy of the temperature measurement values.

[0013] Another problem in vacuum coating processes involving plasma phenomena is the possibility of short occasional energetic plasma arcs which can potentially harm or destroy the SAW-device if an arc discharge strikes the antenna.

[0014] WO2024 / 124264 Al discloses a reduced dipole antenna design with a selectable length coaxial transmission line between a SAW-device and an antenna. The antenna is configured as a loop made of a coaxial line with the core conductor at the end connected to the shield of the coaxial line at the beginning of the antenna structure, wherein it is proposed to cover this connection with some polymetric shield to ensure electrical insulation which must either be often and thoroughly cleaned from coating or often replaced.

[0015] Object of the invention

[0016] An object of the present invention is to provide a RF based temperature sensing unit and a corresponding RF receiver antenna unit for use within a vacuum coating system solving the above-mentioned problems. Oerlikon Surface Solutions AG, Pfaffikon

[0017] OEROlOl.PCT

[0018] The object is solved by an RF based temperature sensing unit according to claim 1, RF receiver antenna units according to claims 17 and 18, and a vacuum coating system according to claim 19. Preferred embodiments of the invention are defined in the dependent claims.

[0019] A RF based temperature sensing unit according to the invention comprises an antenna assembly having an antenna wire and an antenna body, and a temperature sensor assembly having a temperature sensor and a temperature sensor body and configured to be coupled to the antenna wire. The antenna body comprises a bore extending in longitudinal direction of the antenna body, wherein a proximal part of the antenna wire is accommodated within the bore and a distal part of the antenna wire extends outside the bore, wherein a proximal end of the proximal part of the antenna wire is surrounded by an electrical insulator coupled to the temperature sensor.

[0020] According to a preferred embodiment, the antenna may be a monopole quarter wave type. At a RF frequency band of 2.4 GHz, for example, a vacuum wavelength is approximately 12.5 cm For the quarter wave antenna design, the length of antenna wire sticking out of the antenna body corresponds to % of the vacuum wavelength or approximately 3 cm, i.e. the length of the distal part of the antenna wire extending outside the bore is 3 cm. Further, for the antenna body to act as a base for the quarter wave antenna, its length should be larger than the quarter wavelength of the RF signal, i.e. for the typical 2.4 GHz case, it is typically at least 3 cm long.

[0021] Further, according to a preferred embodiment, the temperature sensor may be a SAW-device, so that the antenna wire extending through the bore in the antenna body connects to a SAW- device contact.

[0022] By the above features, it is possible to provide an RF based temperature sensing unit, wherein the part of the antenna connecting to the SAW-device contact wire is surrounded by the electrical insulator, so that the antenna is mechanically fixed. Additionally, by arranging the Oerlikon Surface Solutions AG, Pfaffikon

[0023] OEROlOl.PCT electrical insulator deep in the bore, i.e. far away from the bore opening, the electrical insulator can securely be hidden from coating vapour flux in a vacuum coating system in which the RF based temperature sensing unit is used.

[0024] The bore diameter in the antenna body is adapted to the antenna wire diameter such that a coaxial transmission line with fixed impedance is adapted to the impedance of the SAW-device at its resonance frequency. For a typical 50 Ohm impedance, the ratio of the antenna wire diameter to the bore diameter is approximately 2.3 if the space between bore wall and the antenna wire is empty.

[0025] According to a preferred embodiment, the bore may have a distal region, a middle region and a proximal region, wherein the proximal region has a diameter that is larger than the diameter of the middle region, so that it is possible to make the diameter of the electrical insulator larger than the diameter of the middle region of the bore. This further improves the above-mentioned advantages of fixing the antenna wire on the one hand and protecting the electrical insulation from coating vapour flux on the other hand. For impedance matching, the diameter of the electrical insulator must appropriately be chosen according to the dielectric constant of the insulator material and the antenna wire diameter. For a 50 Ohm impedance and Teflon as a typical example of an insulator material with a dielectric constant of 2.0 in the RF frequency range of 2.4 GHz, the diameter of the electrical insulator must be 3.2 times of the antenna wire diameter, i.e. about a 1.4 times larger diameter than for the impedance matching without electrical insulator, as mentioned above.

[0026] Further, according to a further preferred embodiment, the distal region of the bore within the antenna body may have a diameter different from the diameter of the middle region of the bore to achieve a better matching of the antenna impedance to the transmission line in the antenna body, because both the diameter and the depth of the distal region determine the resulting RF impedance which should be matched to the antenna and the SAW-device at resonance for achieving a maximum RF signal strength. Oerlikon Surface Solutions AG, Pfaffikon

[0027] OEROlOl.PCT

[0028] Alternatively, according to another preferred embodiment, the diameter of the bore may be constant along the longitudinal direction thereof, wherein at least one metallic sleeve is provided on the antenna wire within the bore for impedance matching. Le. instead of providing different diameters and length of regions of the bore, impedance matching is achieved by one or more metallic sleeves. Those metallic sleeves may be of different materials and different dimensions. In particular, the length and the outer diameter of the sleeve can be used for optimizing the impedance matching of the antenna to the transmission line. Additionally, the position of the sleeve on the antenna wire also influences the impedance of the antenna and, thus, may be chosen appropriately.

[0029] According to the present invention, the RF based temperature sensing unit may comprise an antenna body back structure attached to the antenna body and formed by one or several separated beams extending in the longitudinal direction of the antenna body along the distal part of the antenna wire. Alternatively, the antenna body back structure may be integrally formed with the antenna body, i.e. antenna body back structure and antenna body are formed so to make up a single piece such as for example by manufacturing the antenna body back structure and antenna body from the same piece of material, e.g., by drilling or cutting. In both cases the beams may have an elongate rectangular and straight or appropriately bend shape. The beams preferably have a length larger than the distal part of the antenna wire and a predetermined distance perpendicular to the longitudinal direction thereto. Such antenna body back structure suppresses reflected RF waves from surrounding elements such as for example fixtures of neighboring parts in a vacuum coating system. This is important for achieving a good RF signal strength, because such reflected waves may adversely influence the RF signal in the antenna and / or the SAW-device by changing interference conditions, for example. The resulting fluctuation by the motion of the temperature sensing unit in the signal strength might result in erroneous temperature measurements. Oerlikon Surface Solutions AG, Pfaffikon

[0030] OEROlOl.PCT

[0031] Additionally, the antenna body back structure has the function of a reflector for the antenna. For an ideal RF signal strength, it should be separated and spaced apart, respectively, from the antenna by one quarter wavelength, which is about 3 cm for a typical 2.4 GHz RF frequency, as mentioned above. Because in typical applications of vacuum coated components, the diameter of the temperature sensor body may not allow the above ideal distance between the beams of the antenna body back structure and the antenna, the distance may be extended according to the invention by using a S-shaped antenna instead of straight antenna, wherein the wire length must be of the same (quarter wave) length as the straight wire antenna. In case of a S-shaped antenna, the antenna is formed such that its distal end of the distal part is more distant from the antenna body back structure than the remaining of the distal part, for example. Other shapes may be possible depending on the form of the beams and the diameter of the antenna body for achieving the above ideal distance.

[0032] According to a further preferred embodiment, the RF based temperature sensing unit may comprise an antenna body top structure attached to the antenna body back structure for forming a metallic top in the shape of a lid, for example a disc shaped lid. Such a disc lid acts as an arrestor for electric arcs that may occur in plasma vacuum processes from plasma coating sources such as cathodic arc sources or sputtering sources and from electrical biasing of the fixtures with the parts to be coated. This is important, because such arcs igniting to the antenna may harm or destroy the SAW-device if the arc energy is high enough. With the antenna body top and back structure made of solid metal, the conductance for arc is much higher in the antenna body top and back structures than the conductance via the antenna through the SAW- device to the fixture with the part to be coated. According to the invention, the total length of the antenna back structure together with the top lid should be larger than a quarter wavelength of the RF signal to act as a reflector for the RF waves.

[0033] According to a preferred embodiment, the RF based temperature sensing unit may comprise an antenna connector attached to the proximal end of the proximal part of the antenna wire by a metallic bond and a temperature sensor connector connected to the temperature sensor by Oerlikon Surface Solutions AG, Pfaffikon

[0034] OEROlOl.PCT another metallic bond, wherein the antenna connector and the temperature sensor connector are mutually mating RF-type connectors for detachably connecting the antenna wire and the temperature sensor. The metallic bond may be a solder bond, a wire wrap bond, a clamped bond or a threaded connection. This facilitates accessibility of the electrical insulator for cleaning or replacing, which might be necessary, because the electrical insulator may receive some film coating from the vacuum coating process over time. By means of the antenna connector and the temperature sensor connector, an easy installation of the antenna structure with the critical electrical insulator and of the SAW-device into their respective body structures is possible. The antenna body and the temperature sensor body are then assembled with one or more fixing screws, for example.

[0035] According to a further preferred embodiment, the RF based temperature sensing unit may comprise an antenna consisting of two straight wires separated with a 180° bending connecting the wires. One of the straight wire parts connects to a SAW device in an antenna body through a bore in the antenna body and this straight part is sticking out of the antenna body by approximately one quarter wavelength of the Rf wave. The other straight part has a length of approximately one quarter of length of the Rf wavelength and its distal end is electrically connected to the antenna body wherein the distal end thereof is electrically connected to the 180° bending to be connected to the one of the straight wire parts. This antenna design is commonly called a quarter wave monopole loop antenna or a folded monopole quarter wave loop antenna. Unless the simple monopole quarter wave antenna described above, the quarter wave loop antenna has an impedance about four time larger than the simple monopole quarter wave antenna. A conductive back structure of elongated rectangular shape connected to the antenna body is located at a distance from the straight wire part connecting to the SAW device. The length of this back structure must be substantially longer than the quarter wave length of the antenna. By properly choosing the distance of this back structure to the antenna wire, the impedance of the folded monopole quarter wave antenna can be tuned to the usually lower impedance of the SAW device. The choice of the distance d however is not critical. With larger distance, the gain of the folded quarter wave antenna improves, however the mismatch of the Oerlikon Surface Solutions AG, Pfaffikon

[0036] OEROlOl.PCT impedance to the SAW device becomes larger, resulting in an approximate cancellation of both effects on the RF signal strength to the SAW device. Despite these two partially opposing effects, a maximum resulting signal strength can be obtained with a proper choice of the distance d.

[0037] The folded loop antenna has an important advantage over the simple monopole quarter wave antenna in an environment with plasma discharges in vacuum process chambers. In a plasma environment electrically charging of the simple monopole antenna can occur by erratic and sudden plasma instabilities like arc events, which result in higher voltage spike transmitted to the SAW device. SAW devices however are very sensitive to high voltage events and even short spikes can kill them. Since the folded monopole quarter wave loop antenna is electrically connected to the antenna body, plasma events cannot charge the antenna and cannot create an over voltage at the SAW device.

[0038] A RF receiver antenna unit according to the invention comprises a patch antenna having an approximately square metallic patch and a base, wherein a feeding point of the patch antenna is located on a side facing to the base and on the backside off the center of the patch. The center of the patch is preferentially mechanically and electrically connected with the base in order to provide mechanical robustness of the patch with respect to the base and to avoid any buildup of a voltage of the patch in the plasma environment of a PVD processing system which can harm the electronics connected to the patch antenna. In particular, the feeding point is at a position to match the RF impedance of an electrical connection to a resonance frequency detection electronics to which the RF receiver antenna unit is connected. The RF receiver antenna unit according to the invention receives a signal from the above-described RF based temperature sensing unit which is representative of a resonance shift of the SAW-device and the resonance frequency detection electronics detects the resonance shift which indicates the temperature of the SAW-device and therefore of the part to be coated to which the SAW-device is attached. Oerlikon Surface Solutions AG, Pfaffikon

[0039] OEROlOl.PCT

[0040] According to an embodiment of the invention, the shape of the patch and / or the base of the patch antenna may preferably of circular shape. In this case, the linear extension of this geometry is smaller compared to a rectangular shape which makes adaptation in a PVD system simpler. Additionally, since PVD systems generally comprise a vacuum flange having preferably a circular shape, a patch antenna with a circular shape can easily be mounted on a standard vacuum flange, wherein the electrical connection is integrated on the flange, so that the RF receiver antenna unit according to this embodiment can be mounted from outside of the vacuum system.

[0041] Instead of the above patch antenna design, a loop antenna design can be used in an alternative embodiment. In this case, the RF receiver antenna unit according to the invention comprises a double loop antenna and a back reflector structure.

[0042] Regardless of patch antenna design or loop antenna design, the RF receiver antenna unit preferably comprises a receiver antenna body having a distal end and a proximal end and extending perpendicular to the patch and the base, wherein the distal end is connected to the base / back reflector structure and the proximal end is connected to an antenna connector. The RF receiver antenna body is preferably a cylindrical tube, but other shapes are possible. The antenna connector is a standard RF connector to which a standard RF coaxial cable can be connected for connecting the RF receiver antenna unit to the resonance frequency detection electronics.

[0043] The RF receiver antenna unit according to a preferred embodiment comprises an electric connection within the receiver antenna body as an equal impedance vacuum coaxial transmission line connecting the feeding point and the antenna connector, wherein an electrical insulator is provided within the receiver antenna body at the proximal end between an inner conductor and a cylindric shield. By this configuration, the electrical insulator is located at the far end from the feeding point of the path antenna, i.e. at a position where a minimal amount of Oerlikon Surface Solutions AG, Pfaffikon

[0044] OEROlOl.PCT coating material can reach the electrical insulator and cause a buildup of a conducting layer which may cause RF signal loss.

[0045] According to a preferred embodiment, the RF receiver antenna unit comprises at least one sleeve element provided over the coaxial transmission line within the receiver antenna body and located closer to the feeding point than the electrical insulator for adapting the impedance of the coaxial transmission line to the resonance frequency detection electronics impedance. For a typically used 50 Ohm impedance, the diameter of a cylindrical receiver antenna body is 2.3 times the diameter of the sleeve for a coaxial transmission line without insulator material between inner conductor and cylindrical shield.

[0046] A vacuum coating system according to the invention comprising a vacuum chamber, a vacuum coating vapor source within the vacuum chamber, at least one rotating fixture provided within the vacuum chamber on which at least one part to be coated is mounted, at least one RF based temperature sensor unit according to the invention, as mentioned above, located within the vacuum chamber, at least one RF receiver antenna according to the invention, as mentioned above, arranged in close proximity to the at least one RF based temperature sensor unit for receiving a signal indicative of a temperature of the at least one part to be coated, and at least one resonance frequency detection electronics connected to the at least one RF receiver antenna for determining the temperature of the at least one part to be coated based on the received signal.

[0047] According to a preferred embodiment, the at least one RF based temperature sensor unit may be mounted on the at least one rotating fixture equivalent to the at least one part to be coated such that the resulting temperature measured represents the actual temperature of the at least one part to be coated. This means that the RF based temperature sensor unit is equivalent to the part to be coated and mounted on the fixture in the same manner as the part to be coated. For example, the RF based temperature sensor is integrated into a dummy part of similar size Oerlikon Surface Solutions AG, Pfaffikon

[0048] OEROlOl.PCT and similar heat capacity as a part to be coated to be as representative as possible (equivalent) to the part to be coated.

[0049] Preferably, the sensor assembly of the at least one RF based temperature sensor unit may be located on the at least one part to be coated at a location different from the location of the corresponding antenna assembly. In this way, it is possible to sense the temperature at a preferred location of the part to be coated. Multiple RF based temperature units may be placed in the same part to be coated to measure temperatures at different locations. The SAW-devices of these multiple RF based temperature units may be placed at different locations, for example. The SAW-devices are connected to the antenna body by a coaxial cable with the same impedance as the SAW-device at resonance frequency and the transmission line in the antenna body.

[0050] In a preferred embodiment, an antenna assembly of at least one of the RF based temperature sensor units may be oriented in a direction parallel or perpendicular to the rotating fixture on which the part to be coated is mounted. By choosing an appropriate orientation, it can be avoided that excessive coating material reaches the electrical insulator within the RF based temperature sensor unit.

[0051] Preferably, at least two of the rotating fixtures on which parts to be coated may be mounted stacked onto each other. More than one fixture with parts to be coated may be stacked, each rotating on individual rotating axes. The parts itself may rotate on individual rotating axes on the fixture. Since the temperatures on the stacked fixtures might deviate, the RF based temperature sensor unit according to the invention may be placed on each fixture of the stack.

[0052] Brief description of the Figures

[0053] In the following, preferred embodiments of the invention are described with reference to the attached figures, wherein same reference signs indicate same components. Oerlikon Surface Solutions AG, Pfaffikon

[0054] OEROlOl.PCT

[0055] Fig. la shows cross-sectional side and top views of a RF based temperature sensing unit according to a first embodiment of the invention, and Fig. lb shows a 3D view thereof; Fig. 2a shows cross-sectional side and top views of a RF based temperature sensing unit according to a second embodiment of the invention, and Fig. 2b shows a 3D view thereof; Fig. 3 shows a cross-sectional side view of a RF based temperature sensing unit according to a third embodiment of the invention;

[0056] Fig. 4a shows a cross-sectional side view of a RF based temperature sensing unit according to a fourth embodiment of the invention in a first pre-assembled state, Fig. 4b in a second preassembled state, and Fig. 4c in an assembled state;

[0057] Fig. 5a shows a cross-sectional side view and top view of a RF receiver antenna unit according to a first embodiment of the invention, and Fig. 5b shows a 3D view thereof;

[0058] Fig. 6a shows a cross-sectional side view and top view of a RF receiver antenna unit according to a second embodiment of the invention, and Fig. 6b shows a 3D view thereof;

[0059] Fig. 7 shows schematically a vacuum coating system according to a preferred embodiment of the invention;

[0060] Figs. 8 to 11 show different mounting positions of an RF based temperature sensor unit according to a fifth embodiment of the invention on a part to be coated in the vacuum coating system of Fig. 7; and

[0061] Fig. 12a shows cross-sectional side and top views of a RF based temperature sensing unit according to a further embodiment of the invention, and Fig. 12b shows a 3D view thereof; Fig. 13a shows cross-sectional side and top views of a RF based temperature sensing unit according to a further embodiment of the invention, and Fig. 13b shows a 3D view thereof; Fig. 14a shows cross-sectional side and top views of a RF based temperature sensing unit according to a further embodiment of the invention, and Fig. 14b shows a 3D view thereof;

[0062] Fig. 15a shows a cross-sectional side view and top view of a RF receiver antenna unit according to a further embodiment of the invention, and Fig. 15b shows a 3D view thereof;

[0063] Fig. 16a shows a cross-sectional side view and top view of a RF receiver antenna unit according to a further embodiment of the invention, and Fig. 16b shows a 3D view thereof. Oerlikon Surface Solutions AG, Pfaffikon

[0064] OEROlOl.PCT

[0065] Description of the Figures

[0066] Figures la and lb show an RF based temperature sensor unit 1 according to a first embodiment of the invention comprising an antenna assembly 2 and temperature sensor assembly 3.

[0067] According to the first embodiment, both antenna assembly 2 and temperature sensor assembly 3 are separate components fixed to each other by means of a fixing screw 4, as shown in Fig. la. However, the antenna assembly 2 can be provided separately from the temperature sensor assembly 3, as described in more detail with reference to Figs. 8 to 11.

[0068] As shown in Fig. la, a temperature sensor 5 is embedded within a temperature sensor body 6 of the temperature sensor assembly 3 and is a SAW (Surface Acoustic Wave) device. The temperature sensor body 6 having a cylindrical shape has a proximal region 7 and a distal region 8 and aligns to a proximal portion 9 of an antenna body 10 when the temperature sensor assembly 3 is fixed to the antenna assembly 2, as shown in Figs, la and lb.

[0069] The antenna body 10 further has a distal portion 11 and extends in longitudinal direction from the proximal portion 9 to the distal portion 11, as shown in Fig. 1. Like the temperature sensor body 6, the antenna body 10 has a cylindrical shape matching to the cylindrical shape of the temperature sensor body, wherein other shapes than a cylindrical shape are conceivable for both, e.g. square, rectangular, etc.

[0070] As shown in Fig. 1, a bore 12 having a circular cross-section is provided within the antenna body 10 and linearly extends in the longitudinal direction through the antenna body 10. According to the first embodiment, the bore 12 has a proximal region 13, a middle region 14 and a distal region 15, wherein the diameter of the proximal region 13 and the distal region 15 of the bore is larger than the diameter of the middle region 14. The diameter of the distal region 15 of the bore can also be smaller than the diameter of the middle region 14, wherein depth and Oerlikon Surface Solutions AG, Pfaffikon

[0071] OEROlOl.PCT diameter thereof are appropriately chosen for impedance adjustment requirements, as mentioned above.

[0072] As shown in Fig. 1, a straight antenna wire 16 extends through the bore 12, wherein a proximal part 17 of the antenna wire 16 is accommodated within the bore 12 and a distal part 18 thereof extends out of the bore 12. Further, an electrical insulator 19, as shown in Fig. la is located within the proximal region 13 of the bore 12 such that it surrounds a proximal end 20 of the proximal part 17 of the antenna wire 16. The electrical insulator 19 is coupled to the SAW- device 5 and protects an electrical contact between the proximal end 20 of the proximal part 17 of the antenna wire 16 and the SAW-device 5. As mentioned above, the electrical contact is in particular protected from coating vapour flux and flittering particles when used in a vacuum coating system.

[0073] Further, the RF based temperature sensor unit 1 shown in Fig. 1 comprises an antenna body back structure 21 attached to or integrally formed with the distal portion 11 of the antenna body 10 and extending in the longitudinal direction of the antenna body 10 along the distal part 18 of the antenna wire 16. The antenna body back structure 21 according to this embodiment is formed by one or more separated beams 22 (in this embodiment for example two beams) having a length larger than the distal part 18 of the antenna wire 16, being of an electrically conducting material (for example metal) or a non-conducting material with a conducting surface for achieving its function as a reflector, as mentioned above. Further, the antenna body structure 21 has a predetermined distance d to the distal part 18 of the antenna wire 16 perpendicular to the longitudinal direction, equal or less than one quarter wavelength of the RF signal, as mentioned above.

[0074] Further, on top of the antenna body back structure 21 an antenna body top structure 23 is attached or integrally formed. According to this embodiment, the antenna body top structure 23 is formed as a metallic top in the shape of a lid. As shown in Fig. 1, the antenna body top Oerlikon Surface Solutions AG, Pfaffikon

[0075] OEROlOl.PCT structure 23 is circular, but other shapes are possible for protecting the SAW-device from arcs which may occur in the vacuum coating system.

[0076] Fig. la further shows a fixing bore 24 within the antenna body 10 and the temperature sensor body 6 which is used for fixing the RF based temperature sensor unit 1 to an external component such as a fixture in a vacuum coating system. When the antenna assembly 2 is fixed to the temperature sensor assembly 3, as shown in Fig.l, the fixing bore 24 in the antenna body 10 aligns with fixing bore 24 in the temperature sensor body 6.

[0077] Figures 2a and 2b show a RF based temperature sensor unit 25 according to a second embodiment of the invention. The RF based temperature sensor unit 25 according to a second embodiment substantially comprises the same elements and components as the RF based temperature sensor unit shown in Fig.l and described above. These elements are indicated with the same reference sign and a description thereof is not repeated. Instead, only the difference between the first and second embodiments is described below.

[0078] The RF based temperature sensor unit 25 shown in Fig. 2 differs from the RF based temperature sensor unit 1 shown in Fig. 1 in that the diameter of the bore 12 is constant along the longitudinal direction. Instead of different diameters of the bore, for impedance adjustment, metallic sleeves 26, 27 are arranged on the antenna wire 16. In particular, the metallic sleeve 26 is located in the distal region 15 of the bore 12, and the metallic sleeve 27 is located in the middle region 14 of the bore 12. As shown in Fig. 2, the metallic sleeve 26 abuts the metallic sleeve 27 which abuts the electrical insulator 19. The dimensions and materials of both metallic sleeves 26, 27 are appropriately chosen according to the impedance matching requirements.

[0079] Figure 3 shows a RF based temperature sensor unit 28 according to a third embodiment of the invention. The RF based temperature sensor unit 28 according to the third embodiment substantially comprises the same elements and components as the RF based temperature sensor unit 25 shown in Fig. 2 and described above. These elements and components are Oerlikon Surface Solutions AG, Pfaffikon

[0080] OEROlOl.PCT indicated with the same reference sign and a description thereof is not repeated. Instead, only the difference between the second and third embodiments is described below.

[0081] The RF based temperature sensor unit 28 shown in Fig. 3 differs from the RF based temperature sensor unit 25 shown in Fig. 2 in that the distal part 18 of the antenna wire 16 which extends out of the bore 12 is not straight, but S-shaped.

[0082] As mentioned above, for an ideal RF signal strength, the antenna body back structure 21 should be separated from the antenna by one quarter wavelength, which is about 3 cm for a typical 2.4 GHz RF frequency. Because in typical applications of vacuum coated components the diameter of the temperature sensor body 6 may not allow the above ideal distance between the beams 22 of the antenna body back structure 21 and the antenna wire 16, the distance may be extended according to the third embodiment by using a S-shaped antenna instead of straight antenna, wherein the wire length must be of the same (quarter wave) length as the straight wire antenna.

[0083] Fig. 4a shows a cross-sectional side view of a RF based temperature sensing unit 29 according to a fourth embodiment of the invention in a first pre-assembled state, Fig. 4b in a second preassembled state, and Fig. 4c in an assembled state. The RF based temperature sensor unit 29 according to the fourth embodiment substantially comprises the same elements and components as the RF based temperature sensor unit 25 shown in Fig. 2 and described above. These elements and components are indicated with the same reference signs and a description thereof is not repeated. Instead, only the difference to the second embodiment is described below.

[0084] As shown in Fig. 4a, the RF based temperature sensor unit 29 comprises an antenna connector 30 and a SAW-device connector 31. The antenna connector 30 is attached to the proximal end 20 of the proximal part 17 of the antenna wire 16 by a metallic bond 32. The SAW-device connector 31 is attached to the SAW-device 5 by other metallic bonds 33. The antenna Oerlikon Surface Solutions AG, Pfaffikon

[0085] OEROlOl.PCT connector 30 and the SAW-device connector 31 are mutually mating RF-type connectors for detachably connecting the antenna wire 16 and the SAW-device 5. This configuration facilitates accessibility of the electrical insulator 19 for cleaning or replacing. By means of the antenna connector 30 and the SAW-device connector 31 an easy installation into their respective body structures is possible as shown in Fig. 4b. Further, by means of the connectors it is possible to separate the antenna assembly 2 from the temperature sensor assembly 3 when the RF based temperature sensor unit 29 is used in a vacuum coating system, as described in more detail with reference to Fig. 8 to 11.

[0086] In the pre-assembly state shown in Fig. 4b, the SAW-device 5 with attached SAW-device connector 31 is inserted into the temperature sensor body 6 and the antenna structure shown in Fig. 4a is inserted into the bore 12 of the antenna body 10. Finally, as shown in Fig. 4c, the antenna body 10 and the temperature sensor body 6 are then assembled with the fixing screw 4.

[0087] Fig. 5a shows a cross-sectional side view and top view of a RF receiver antenna unit 34 according to a first embodiment of the invention, and Fig. 5b shows a 3D view thereof. The RF receiver antenna unit 34 receives a signal from the RF based temperature senor unit 1, 25, 28, 59 described above indicative of the temperature of the SAW-device 4, i.e. of a part on which it is mounted.

[0088] The RF receiver antenna unit 34 has a patch antenna design with a patch antenna 35 having a square metallic patch 36 and a base 37, wherein a feeding point 38 of the patch antenna 35 is located on a side facing to the base 37 and on the backside off the center of the patch 36. As shown in Fig. 5, the RF receiver antenna unit 34 has a transmission line 39 having a distal end 40 and a proximal end 41 which extends perpendicular to the patch 36 and the base 37, wherein the distal end 40 is connected to the base 37 and the proximal end 41 is connected to an antenna connector 42. The position of the feeding point 38 has to be chosen according the impedance of the transmission line 39. Oerlikon Surface Solutions AG, Pfaffikon

[0089] OEROlOl.PCT

[0090] As shown in Fig. 5b, the transmission line 39 has a tube shape and encompasses a sleeve 43 located within the transmission line 39 at the distal end 40 thereof, and a sleeve 44 within the transmission line 39 in a middle region of the transmission line 39 between the distal end 40 and the proximal end 41 thereof. Both sleeves 43 and 44 are located over an electric connection 45 and are used for impedance adjustment, similar to the above-described sleeves 26 and 27 of the RF based temperature sensor units 25,28. The sleeves 43, 44 of a metal material or other material suitable and have appropriate dimensions for impedance adjustment.

[0091] The electric connection 45 within the transmission Iine39 is configured as an equal impedance vacuum coaxial transmission line connecting the feeding point 38 and the antenna connector 42, wherein an electrical insulator 46 is provided within the transmission line 39 at the proximal end 41 between an inner conductor and a cylindric shield of the transmission line.

[0092] As shown in Fig. 5a, the sleeves 43, 44 are located closer to the feeding point 38 than the electrical insulator 46, for minimizing exposure of the electrical insulator 46 to coating vapor flux when it is used during a coating process within a vacuum coating system. As shown in Fig. 5b, the RF receiver antenna unit 34 according to this embodiment is connected to resonance frequency detection electronics 47 via a standard RF coaxial cable 48. The resonance frequency detection electronics 47 determines the temperature of the SAW-device 5 based on a resonance frequency shift of the SAW-device 5 by analyzing the RF signal received from the RF receiver antenna 34.

[0093] The patch antenna 34 shown in Fig. 5a, 5b with has a linear polarization characteristics determined by the exact shape of the patch and the feeding point 38. The sensor quarter wave antenna to be oriented approximately along the polarization direction of the receiver antenna for good coupling of the Rf signal between the antennas. If the sensor antenna is oriented at 90° to the polarization direction of the receiver antenna, no or only residually week signal coupling is achieved. By choosing an patch antenna design for circular polarization (e.g. truncated square Oerlikon Surface Solutions AG, Pfaffikon

[0094] OEROlOl.PCT with two edges cut off), the directional orientation of the sensor antenna becomes irrelevant, making the system more versatile and more robust in signal quality. However, the signal strength of the Rf coupling between the antennas is only at 50% of the ideally oriented antennas for the linear polarized case.

[0095] Fig. 6a shows a cross-sectional side view and top view of a RF receiver antenna unit 49 according to a second embodiment of the invention, and Fig. 6b shows a 3D view thereof. The RF receiver antenna unit 49 differs from the RF receiver antenna unit 34 of the first embodiment shown in Fig. 5 in that a double loop antenna design is used instead of a patch antenna design. The remaining elements and components are identical to those already described with respect to the first embodiment shown in Fig. 5, wherein the same reference signs are used without repeating their description.

[0096] The RF receiver antenna unit 49 comprises a double loop antenna 50 and a back reflector structure 51 having a pronounced forward direction characteristic, for example. In contrast to the above patch antenna design, this design has the advantage of a reduced surface area which is exposed to buildup of coating layers.

[0097] As shown in Fig. 6, the double loop antenna 50 is mechanically supported by connection wires 52 at its antenna electric field minimums. Like the RF receiver antenna unit 34 shown in Fig. 5, the antenna loop antenna 50 is fed by a coaxial transmission line 45. The remaining elements and components shown in Fig. 6 are the same as in Fig. 5 and not described again.

[0098] Fig. 7 shows schematically a vacuum coating system 53 according to a preferred embodiment of the invention in which the above described Rf based temperature sensor units 1, 25, 28, 29 and the RF receiver antenna units 34, 49 are used.

[0099] The vacuum coating system 53 comprises a vacuum chamber (not shown in the Figure). In this vacuum chamber parts 54 to be coated are mounted on rotating fixtures 55. According to the Oerlikon Surface Solutions AG, Pfaffikon

[0100] OEROlOl.PCT preferred embodiment, the RF based temperature sensor units 1, 25, 28, 29 according to the invention are arranged on the fixtures 55 equivalent to the parts 54 to be such that the resulting temperature measured represents the actual temperature of the parts 54 to be coated. This means that the RF based temperature sensor units 1, 25, 28, 29 are equivalent to the part to be coated and mounted on the fixture 55 in the same manner as the part 54 to be coated. Preferably, the RF based temperature sensor unit 1, 25, 28, 29 is integrated into a dummy part of similar size and similar capacity as a part to be coated to be as representative (equal) as possible to the part to be coated. In this embodiment, the RF based temperature sensor units 1, 25, 28, 29 have the same shape, as shown in Fig. 6. Different shapes of the RF based temperature sensor units 1, 25, 28, 29 and parts 54 to be coated are possible.

[0101] As shown in Fig. 7, more than one fixture 55 with parts 54 mounted thereon are stacked on individually rotating axes 56. Since the temperatures on the stacked fixtures 55 might deviate, a RF based temperature sensor unit 1, 25, 28, 29 is placed on each fixture 55 of the stack, as shown in Fig. 7. In this case, the SAW-device in each RF based temperature sensor unit 1, 25, 28, 29 must have a different resonance frequency to distinguish the RF response signals. According to the preferred embodiment the same antenna design should be used if multiple RF based temperature sensor units are installed on the fixtures, because the resonance spectrum of SAW- devices is very narrow compared to the bandwidth of the antenna, and the resonance frequency only slightly differs.

[0102] As shown in Fig. 7, the parts 54 on the fixtures 55 as well as the RF based temperature sensor units 1, 25, 28, 29 are rotating about its own axis driven by gears (not shown) integrated into the fixture 55. Further, the rotating axes 56 of the fixtures 55 are mounted on a rotating platform 57 and are driven by gears (not shown) integrated into a platform 57. The parts 54 to be coated rotating about their axes are passing a vacuum coating vapor source 58 over time at a certain frequency defined by the gear ratio of the driving mechanism and the rotation speed of the rotating platform 57. In this way, each portion of the cylindrical surface of the part 54 is Oerlikon Surface Solutions AG, Pfaffikon

[0103] OEROlOl.PCT equally exposed to the vacuum coating vapor source 58 over time ensuring good coating uniformity.

[0104] When the fixtures 55 rotate, the RF based temperature sensor units 1, 25, 28, 29 pass the RF receiver antennas 34, 49 which are static and connected to resonance frequency detector electronics 47. When the antennas of the RF based temperature sensor units 1, 25, 28, 59 are in close proximity to the RF receiver antennas 34, 49, and are facing the receiver antennas, good signal strength is achieved enabling the resonance frequency detection electronics 47 to provide good signal quality for the temperature measurement extracted from the shift of the resonance frequency of the SAW-device.

[0105] Fig. 8 to 11 show different mounting positions of an RF based temperature sensor unit 59 according to a fifth embodiment of the invention on a part 54 to be coated in the vacuum coating system 53 of Fig. 7.

[0106] The RF based temperature sensor unit 59 differs from the RF based temperature sensor unit 1, 25, 28 29 according to the above described first to fourth embodiments shown in Figs. 1 to 4 only in that the antenna assembly 2 is separated from the temperature sensor assembly 3 and both are connected via a RF coaxial cable. In particular, according to this embodiment, the RF based temperature sensor unit 59 comprises the antenna connector 30 and the SAW-device connector 31 similar to the fourth embodiment shown in Fig. 4 which are connected via a RF coaxial cable 48.

[0107] By separating the temperature sensor assembly 3 from the antenna assembly 2 it is possible to place the SAW-device at a certain position on the part 54 to be coated which position is for example more representative for the actual temperature of the part 54. Further, as shown in Figs 9 to 11, more than one temperature sensor assembly 3 is placed on the part 54 to be coated at different locations. In this case, for example a mean value of measured temperatures Oerlikon Surface Solutions AG, Pfaffikon

[0108] OEROlOl.PCT can be used for more accurately determining the actual temperature of the part 54 to be coated.

[0109] As shown in Fig. 9, two antenna assemblies 2 are located on opposite sides of a part 54 to be coated. In this case, the part 54 has a rectangular shape, however any arbitrary shape of the part 54 is possible. For each of the antenna assemblies 2 a separate RF receiver antenna unit 34, 49 is provided.

[0110] Similar to Fig. 9, two antenna assemblies 2 with corresponding RF receiver antenna units 34, 49 are shown in Fig. 10. However, in contrast to Fig. 9, the longitudinal orientation of the antenna assemblies 2 is different than in Fig. 9. In Fig. 9 the orientation of the antenna assemblies 2 is vertical, i.e. parallel to the long side of the rectangular part 54, whereas in Fig. 10, the orientation of the antenna assemblies 2 is horizontal, i.e. parallel to the short side of the rectangular part 54. The orientation of the antenna assemblies 2 shown in Fig. 9 may be advantageous, because flitters of coating material falling downwards by gravity and originating from coatings of fixtures and chamber wall cannot fall into the transmission line in the antenna body where they can result in a short circuit between the antenna wire and the antenna body in case the flitters are of a conductive material.

[0111] Fig. 11 shows two antenna assemblies 2 and only one associated RF receiver antenna unit 34,49. With multiple remotely connected SAW-devices, the respective antenna assemblies 2 may be located on the moving parts 54 to be coated at geometrical positions that pass the same RF receiver antenna 34, 49 at different times. In this case, the antenna assemblies 2 must be separated in their motion path to ensure that there is no interference of the RF signals. Further, in this case, the resonance frequency detection electronics must be capable of handling multiple resonance frequency detection cycles separated in time from the same antenna signal.

[0112] Figures 12a and 12b show a further embodiment of a RF based temperature sensor unit 60 according to the invention with a folded quarter wave antenna Oerlikon Surface Solutions AG, Pfaffikon

[0113] OEROlOl.PCT comprising a first straight wire element 61 substantially corresponding to the distal part 18 of the antenna wire 16 according to the embodiments shown in Figures 1 and 2, and a second straight wire element 62 connected to the first straight wire element 61 with a 180° bending 63 in between. In particular, a distal end of the first straight wire element 61 is connected to one end of the 180° bending 63 and a distal end of the second straight wire element 62 is connected to the other end of the 180° bending 63. Further, the proximal end of the first straight wire element 61 is connected to the temperature sensor 5 (SAW device) through a bore 12 in the antenna body 10, which diameter is adapted to the wire diameter to match the wave impedance of the SAW device. The length of the distal part 18 of the first straight wire element 61 sticking (extending) out of the antenna body 10 has a length of approximately a quarter wavelength of the Rf wave. The proximal end of the second straight wire element is attached to the antenna body 10 by an electrical contact 64. Further, according to this embodiment, an elongated rectangular metallic back structure 65, which substantially corresponds to one beam 22 of the antenna body back structure 22 shown in Figures 1 and 2, is connected to the antenna body 10 or can be part of the antenna body 10 and extends longitudinally in the same direction of the antenna body 10 and elongates the antenna body 10. The length of this back structure 65 must be longer than a quarter wavelength of the Rf wave. The distance d from the metallic back structure 65 and the distal part 18 of the first straight wire element 61 extending out of the bore 12 of the folded quarter wave antenna is chosen such that the wave impedance of the folded quarter wave antenna is matching the impedance of the SAW device. Further, the first straight wire element 61 and the second straight wire element 61 are substantially parallel and electrically connected to each other.

[0114] Figures 13a and 13b shows another embodiment of a folded quarter wave antenna design. Instead of the bent wire structure (180° bending 63 shown in Figs. 12a and 12b), the antenna consists of a straight antenna wire 16, the distal part 18 thereof extending through the bore 12 and connecting to the SAW device as with the simple monopole antennas according to the embodiments shown in Figs. 1 and 2. The structure of the RF based temperature sensor unit 70 shown in Figures 13a and 13b is substantially the same as of the RF based temperature sensor Oerlikon Surface Solutions AG, Pfaffikon

[0115] OEROlOl.PCT unit 1 and 25 shown in Fig. 1 and 2 and only the different parts are described in more detail below.

[0116] The RF based temperature sensor unit 70 comprises an elongated rectangular metallic plate 71 electrically connected to the antenna body 10 and extending to the same length as the distal part 18 of the antenna wire 16 which extends out of the bore 12. The distal end of the distal part 18 of the antenna wire 16 and the elongated rectangular plate 71 are electrically connected by a metallic element 72 and an electrical contact 64 with each other. The elongated rectangular plate 71 acts as an additional preventive element for coating material vapor to reach the insulator 19 of the RF based temperature sensor unit 70. Additionally, with the elongated rectangular metallic plate 71 having a certain width, the bandwidth of the folded quaterwave antenna design becomes broader, allowing more tolerance in matching to the RF wavelength chosen in the setup. This can be of relevance if more than one temperature sensing unit is used in a PVD coating process system, each having a slightly different RF wavelength to distinguish the individual temperature sensing signals. Further, as shown in Fig . 13, the elongated rectangular metallic plate 71 is substantially parallel to the back structure 65.

[0117] Figures 14a and 14b shows a RF based temperature sensor unit 80 according to a further embodiment of the invention. The RF based temperature sensor unit 80 differs from the embodiment shown in Figures 13a and 13b substantially in that an additional element 81 is attached to the end of the elongated back structure 65 to enable using the RF based temperature sensor unit 80 in an upside-down orientation. This additional element 81 has a structure 82 with which the sensor unit can be mounted in a typical substrate fixture 83 in a PVD processing chamber setup. In a simple case like schematically depicted in Figures 14a and 14b, the substrate fixture 83 has a pin 84, wherein a hole 85 in the additional element 81 is matching with the pin 84 of the substrate fixture 83. Obviously other embodiments of the additional element 81 and the structure 82 can be envisioned to enable securely holding the sensor unit on a fixture in a PVD coating process system and making it removable in a simple way. Oerlikon Surface Solutions AG, Pfaffikon

[0118] OEROlOl.PCT

[0119] Figure 15a shows a further embodiment of a RF receiver antenna unit 90 according to the invention. The RF receiver antenna unit 90 substantially differs from the embodiment shown in Figures 5a and 5b in that the center of the patch 36 is mechanically and electrically connected to the base 37 in the center thereof by a metallic element 91 substantially extending perpendicular from the patch 26 to the base 37 by a predetermined length. Further, the feeding point 38 connecting the patch 36 to the sleeve 43 of the transmission line 39 is arranged in a distance to the metallic element 91, i.e. spaced apart not at the center of the base 37. Similar to the embodiment shown in Figure 5a, the feeding point 38 corresponds to a wire electrically connecting the patch 36 and the sleeve 43 of the transmission line 39. According to this embodiment, the length of the feeding point 38 is substantially the same as the length of the metallic element 91, wherein the length of the metallic element 91 defines a distance between the patch 36 and a surface of the base 37. Further, as shown in Figure 15a, the feeding point (wire) 38 extends substantially parallel to the metallic element 91. All the other elements in Fig 15a are equivalent to the rectangular patch described in Fig 5a.

[0120] Figure 16a shows a further embodiment of a RF receiver antenna unit 100 comprising a circular patch antenna 36 and a co-circular base 37. The RF receiver antenna unit 100 differs from the embodiment shown in Figure 15a in that the patch antenna and the base 37 have a circular shape. All the other elements in Fig 16a are equivalent to the rectangular patch described in Figures 15a and 5a.

[0121] Figure 16b shows an embodiment according to the invention, wherein the RF receiver antenna unit 100 of Figure 16a is mounted on a vacuum flange 92 by three rods 93. The vacuum flange 92 comprises a vacuum feedthrough 94 integrated into the vacuum flange 92 which provides the connection to the resonance frequency detection electronics 47 via a standard RF coaxial cable 48. Oerlikon Surface Solutions AG, Pfaffikon

[0122] OEROlOl.PCT

[0123] List of reference signs:

[0124] 1 RF based temperature sensor unit

[0125] 2 antenna assembly

[0126] 3 temperature sensor assembly

[0127] 4 fixing screw

[0128] 5 temperature sensor

[0129] 6 temperature sensor body

[0130] 7 proximal region of sensor body

[0131] 8 distal region of sensor body

[0132] 9 proximal portion of antenna body

[0133] 10 antenna body

[0134] 11 distal portion of antenna body

[0135] 12 bore

[0136] 13 proximal region of bore

[0137] 14 middle region of bore

[0138] 15 distal region of bore

[0139] 16 antenna wire

[0140] 17 proximal part of antenna wire

[0141] 18 distal part of antenna wire

[0142] 19 electrical insulator

[0143] 20 proximal end

[0144] 21 antenna body back structure

[0145] 22 beams

[0146] 23 antenna body top structure

[0147] 24 fixing bore

[0148] 25 RF based temperature sensor unit

[0149] 26 metallic sleeve

[0150] 27 metallic sleeve Oerlikon Surface Solutions AG, Pfaffikon

[0151] OEROlOl.PCT

[0152] 28 RF based temperature sensor unit

[0153] 29 RF based temperature sensor unit

[0154] 30 antenna connector

[0155] 31 SAW-device connector

[0156] 32 metallic bond

[0157] 33 other metallic bonds

[0158] 34 RF receiver antenna unit

[0159] 35 patch antenna

[0160] 36 patch

[0161] 37 base

[0162] 38 feeding point

[0163] 39 transmission line

[0164] 40 distal end of receiver antenna body

[0165] 41 proximal end of receiver antenna body

[0166] 42 antenna connector

[0167] 43 sleeve

[0168] 44 sleeve

[0169] 45 coaxial transmission line

[0170] 46 electrical insulator

[0171] 47 resonance frequency detection electronics

[0172] 48 RF coaxial cable

[0173] 49 RF receiver antenna unit

[0174] 50 double loop antenna

[0175] 51 back reflector structure

[0176] 52 connection wires

[0177] 53 vacuum coating system

[0178] 54 parts to be coated

[0179] 55 rotating fixtures

[0180] 56 rotation axes Oerlikon Surface Solutions AG, Pfaffikon

[0181] OEROlOl.PCT

[0182] 57 rotating platform

[0183] 58 vacuum coating vapor source

[0184] 59 RF based temperature sensor unit60 RF based temperature sensor unit

[0185] 61 first straight wire element

[0186] 62 second straight wire element

[0187] 63 bending

[0188] 64 electrical contact

[0189] 65 back structure

[0190] 70 RF based temperature sensor unit

[0191] 71 metallic plate

[0192] 72 metallic element

[0193] 80 RF based temperature sensor unit

[0194] 81 additional element

[0195] 82 structure

[0196] 83 substrate fixture

[0197] 84 pin

[0198] 85 hole

[0199] 90 RF receiver antenna unit

[0200] 91 metallic element

[0201] 92 vacuum flange

[0202] 93 rods

[0203] 94 vacuum feedthrough

Claims

Oerlikon Surface Solutions AG, PfaffikonOEROlOl.PCTClaims1. RF based temperature sensor unit comprising: an antenna assembly (2) having an antenna wire (16) and an antenna body (10); and a temperature sensor assembly (3) having a temperature sensor ( 5) and a temperature sensor body (6) and configured to be coupled to the antenna wire (16), wherein the antenna body (10) comprises a bore (12) extending in longitudinal direction of the antenna body (10), wherein a proximal part (17) of the antenna wire (16) is accommodated within the bore (12) and a distal part (18) of the antenna wire (16) extends outside the bore (12), wherein a proximal end (20) of the proximal part (17) of the antenna wire (16) is surrounded by an electrical insulator (19) coupled to the temperature sensor (5).

2. RF based temperature sensor unit according to claim 1, wherein the antenna assembly (2) comprises a monopole quarter-wave type antenna.

3. RF based temperature sensor unit according to claim 1, wherein a distal end of the distal part (18) of the antenna wire (16) is electrically connected to the antenna body (10).

4. RF based temperature sensor unit according to claim 3, wherein the antenna wire (16) comprises a first straight wire element (16a) extending outside the bore (12) and a second straight wire element (16b) electrically connected to a distal end of the first straight wire element (16a) via a 180° bending (63).

5. RF based temperature sensor unit according to claim 3, wherein the distal end of the distal part (18) of the antenna wire (16) is electrically connected to the antenna body (12) via a metallic plate (71) extending parallel to the antenna wire (16) and having the same length, and via a metallic element (72) connecting the distal end of the distal part (18) of the antenna wireOerlikon Surface Solutions AG, PfaffikonOEROlOl.PCT(16) and the metallic plate (71) and having a length defining the distance between the metallic element (72) and the distal part (18) of the antenna wire (16).

6. RF based temperature sensor unit according to any one of claims 3 to 5, wherein the antenna assembly (2) comprises a monopole quarter-wave loop type antenna.

7. RF based temperature sensor unit according to any one of claims 1 to 6, wherein the temperature sensor (5) is a SAW (Surface Acoustic Wave)-device.

8. RF based temperature sensor unit according to any one of the preceding claims, wherein the bore (12) has a distal region (15), a middle region (14) and a proximal region (13), and the proximal region (13) accommodating the electrical insulator (19) has a diameter that is larger than the diameter of the middle region (14).

9. RF based temperature sensor unit according to claim 8, wherein the distal region (15) has a diameter different from the diameter of the middle region (14) of the bore (12).

10. RF based temperature sensor unit according to claim 8 or 9, wherein the diameter of the electrical insulator (19) is larger than the diameter of the middle region (14) of the bore (12).

11. RF based temperature sensor unit according to any one of the preceding claims, wherein the diameter of the electrical insulator (19) is configured in dependency of the dielectric constant of the insulator material and the antenna wire diameter.

12. RF based temperature sensor unit according to any one of claims 1 to 11, wherein the diameter of the bore (12) is constant along the longitudinal direction thereof, and at least one metallic sleeve (26, 27) is provided on the antenna wire (16) within the bore (12) for impedance matching.Oerlikon Surface Solutions AG, PfaffikonOEROlOl.PCT13. RF based temperature sensor unit according to any one of the preceding claims, comprising an antenna body back structure (21) attached to the antenna body (10) and formed by one or several separated beams (22) extending in the longitudinal direction of the antenna body (10) along the distal part of the antenna wire (16), having a length larger than the distal part of the antenna wire (16) and having a predetermined distance perpendicular to the longitudinal direction thereto.

14. RF based temperature sensor unit according any one of claims 1 to 12, comprising an antenna body back structure (21) integrally formed with the antenna body (10) and formed by one or several separated beams (22) extending in the longitudinal direction of the antenna body (10) along the distal part of the antenna wire (16), having a length larger than the distal part of the antenna wire (16) and having a predetermined distance perpendicular to the longitudinal direction thereto.

15. RF based temperature sensor unit according to claim 13 or 14, comprising an antenna body top structure (23) attached to the antenna body back structure (21) and forming a metallic top in the shape of a lid.16 RF based temperature sensor unit according to claims 13 or 14, wherein the antenna body back structure (21) comprises an additional element (81) provided at a distal end thereof and having a structure (82) configured for fixing the RF based temperature sensor unit (80) to a substrate fixture (83) used in a PVD processing chamber setup.

17. RF based temperature sensor unit according to any one of the preceding claims, wherein the distal part (18) of the antenna wire (16) is straight.

18. RF based temperature sensor unit according to any one of claims 1 to 17, wherein the distal part (18) of the antenna wire (16) is S-shaped for adjusting a distance to the antenna body back structure (21).Oerlikon Surface Solutions AG, PfaffikonOEROlOl.PCT19. RF based temperature sensor unit according to any one of the preceding claims, comprising an antenna connector (30) attached to the proximal end (20) of the proximal part (17) of the antenna wire (16) by metallic bond (32) and a temperature sensor connector (31) connected to the temperature sensor (5) by another metallic bond (33), wherein the antenna connector (30) and the temperature sensor connector (31) are mutually mating RF-type connectors for detachably connecting the antenna wire (16) and the temperature sensor (5).

20. RF based temperature sensor unit according to claim 19, wherein the antenna body (10) and the temperature sensor body (6) are separated from each other and the antenna wire (16) is connected to the temperature sensor (5) via a coaxial cable (48) between the antenna connector (30) and the temperature sensor connector (31).

21. RF based temperature sensor unit according to any one of claims 1 to 19, wherein the antenna body (10) and the temperature sensor body (6) are directly coupled to each other by fixing means (4).

22. RF receiver antenna unit (34, 90, 100) configured to be connected to resonance frequency detection electronics (47), comprising a patch antenna (35) having an approximately square or circular metallic patch (36) and a corresponding square or co-circular base (37), wherein a feeding point (38) of the patch antenna (35) is located on a side facing to the base (37) and on the backside off the center of the patch (36), a transmission line (39) having a distal end (40) and a proximal end (41) and extending perpendicular to the patch (36) and the base (37), wherein the distal end (40) is connected to the base (37) and the proximal end (41) is connected to an antenna connector (42), an electric connection (45) within the transmission line (39) as an equal impedance vacuum coaxial transmission line connecting the feeding point (38) and the antenna connectorOerlikon Surface Solutions AG, PfaffikonOEROlOl.PCT(42), wherein an electrical insulator (46) is provided within the transmission line (39) at the proximal end (41) between an inner conductor and a cylindric shield; and at least one sleeve element (43, 44) provided over the coaxial transmission line (45) within the transmission line (39) and located closer to the feeding point (38) than the electrical insulator (46) for adapting the impedance of the coaxial transmission line (45) to the resonance frequency detection electronics impedance.

23. RF receiver antenna unit (90, 100) according to claim 22, wherein the patch antenna (35) comprises a metallic element (91) connecting at a center of the metallic patch (36) and the base (37) the metallic patch (36) to the base (37), wherein the metallic element (91) and the feeding point (38) are spaced apart and extend parallel to each other.

24. RF receiver antenna unit (100) according to claim 21 or 22, further comprising a circular vacuum flange (92) connected to the base (37) via one or more rods (93) and having a vacuum feedthrough (94) through which a RF coaxial cable (48) passes for connecting the RF receiver antenna unit (100) to the resonance frequency detection electronics (47).

25. RF receiver antenna unit (49) configured to be connected to resonance frequency detection electronics (49), comprising a double loop antenna (50) having a feeding point (38) and a back reflector structure (51), a transmission line (39) having a distal end (40) and a proximal end (41) and extending perpendicular to the back reflector structure (51), wherein the distal end (40) is connected to the back reflector structure (51) and the proximal end (41) is connected to an antenna connector (42), an electric connection (45) within the transmission line (39) as an equal impedance vacuum coaxial transmission line connecting the feeding point (38) and the antenna connector (42), wherein an electrical insulator (46) is provided within the transmission line (39) at the proximal end (1) between an inner conductor and a cylindric shield, andOerlikon Surface Solutions AG, PfaffikonOEROlOl.PCT at least one sleeve element (43, 44) provided over the coaxial transmission line (45) within the transmission line (39) and located closer to the feeding point (38) than the electrical insulator (46) for adapting the impedance of the coaxial transmission line (45) to the resonance frequency detection electronics impedance.

26. A vacuum coating system (53) comprising a vacuum chamber, a vacuum coating vapor source (58) within the vacuum chamber, at least one rotating fixture (55) provided within the vacuum chamber on which at least one part (54) to be coated is mounted, at least one RF based temperature sensor unit (1, 25, 28, 29) according to any one of claims 1 to 21 located within the vacuum chamber, at least one RF receiver antenna unit (34, 49, 90, 100) according to any one of claims 22 to 25 arranged in close proximity to the at least one RF based temperature sensor unit (1, 25, 28, 29) for receiving a signal indicative of a temperature of the at least one part (54) to be coated; and at least one resonance frequency detection electronics (49) connected to the at least one RF receiver antenna (34, 49) for determining the temperature of the at least one part (54) to be coated based on the received signal.

27. The vacuum coating system (53) according to claim 26, wherein the at least one RF based temperature sensor unit (1, 25, 28, 29) is configured and mounted on the at least one rotating fixture (55) equivalent in the same manner as the at least one part (54) to be coated such that the resulting temperature measured represents the actual temperature of the at least one part (54) to be coated.

28. The vacuum coating system (53) according to claims 26 or 27, wherein the temperature sensor assembly (3) of the at least one RF based temperature sensor unit (1, 25, 28, 29) isOerlikon Surface Solutions AG, PfaffikonOEROlOl.PCT located on the at least one part (54) to be coated at a location different from the location of the corresponding antenna assembly (2).

29. The vacuum coating system (53) according to any one of claims 26 to 28, wherein each RF receiver antenna (34, 49) is located in close proximity to the temperature sensor assembly (3) of at least one of the RF based temperature sensor units (1, 25, 28, 29).

30. The vacuum coating system (53) according to any one of claims 26 to 29, wherein the antenna assembly (2) of at least one of the RF based temperature sensor units (1, 25, 28, 29) is oriented in a direction perpendicular to the rotating fixture (55) on which the part (54) to be coated is mounted.

31. The vacuum coating system (53) according to any one of claims 26 to 29, wherein the antenna assembly (2) of at least one of the RF based temperature sensor units (1, 25, 28, 29) is oriented in a direction parallel to the rotating fixture (55) on which the part (54) to be coated is mounted.

32. The vacuum coating system (53) according to any one of claims 26 to 31, wherein at least two antenna assemblies (2) of the RF based temperature sensor units (1, 25, 28, 29) have different orientations.

33. The vacuum coating system (53) according to any one of claims 26 to 31, wherein at least two of the rotating fixtures (55) on which parts (54) to be coated are mounted are stacked onto each other, wherein each part (54) to be coated and each fixture (55) rotate on individual rotating axis

Images