Apparatus for rotatable positioning of a substrate - Patent application

Abstract

An apparatus (1) for manipulating a flat substrate (3) within a vacuum chamber is described. The apparatus (1) comprises an arm (6) having a length axis (9) extending between a first end (7) and a second end (8). The arm (6) comprises a cooling surface (10) at the second end (8) for cooling the flat substrate (3) in contact with the cooling surface (10), the cooling surface (10) having a central axis (11) extending essentially perpendicular to the axis (9) of the cooling surface (10). The clamping device (17) comprises a first bearing device (21) arranged about the central axis (11) and movable in a direction along the central axis (11), and a substrate clamping device (22) comprising a second bearing device (23) engaging the first bearing device (21) such that the second bearing device (23) is rotatable about the central axis (11), and a substrate engagement device (24) fixed to the second bearing device (23) and configured to engage a peripheral edge (47) of the substrate (3). The clamping device (17) also comprises an adjustable actuation device (25) configured to apply an adjustable actuation force to the first bearing device (21) in a direction along the central axis (11) such that the substrate (3) is pressed towards the cooling surface (10).

Description

[Technical field]

[0001] The present invention relates to an apparatus for rotatable positioning of a substrate, more particularly to an apparatus for enabling the rotation of a flat substrate in a vacuum chamber, which apparatus allows for cooling of the flat substrate. [Background technology]

[0002] Many investigations of the properties of a surface of a substrate require both precise temperature control of the substrate and the ability to manipulate its orientation relative to an incoming probe beam while performed in a vacuum chamber. Similar requirements for precise temperature control of the substrate and the ability to manipulate its orientation exist when performing various processes on a surface in a vacuum chamber, such as, for example, plasma etching and deposition. Existing manipulators for manipulation of the orientation of a substrate can be configured for linear motion about one or more of three Cartesian coordinates, as well as for polar and azimuthal rotation. It is desirable to provide efficient cooling of the substrate while allowing for motion.

[0003] In the article "Azimuthal rotation of a continuously cooled UHV substrate holder for surface physics investigations", Rev. Sci. Instrum. 63(9), September 1992, pp. 4227-4228, an apparatus for simultaneous manipulation and cooling of substrates is described. The apparatus comprises a vertical shaft about which polar rotation is possible, and a horizontal shaft about which azimuthal rotation is possible. The substrate holder is attached to the horizontal shaft. The horizontal shaft is rotatable relative to the vertical shaft by means of an angular gear. The horizontal shaft is linked to cooling fingers on the vertical shaft by a copper braid. The copper braid limits the cooling of the substrate holder and therefore the substrate.

[0004] In some investigations of the properties of the surface of a substrate and when performing various processes on the surface of the substrate, it is necessary to cool the substrate to very low temperatures. In particular, when depositing metal layers on some semiconductor substrates, it has been shown that cooling the substrate can improve the quality of the layer for some applications. With prior art devices, cooling the substrate to very low temperatures in a vacuum and with the freedom to adjust the orientation of the substrate relative to the orientation of the process sources is difficult or impossible to achieve, especially for large substrate areas such as semiconductor wafers or substrates exposed to a thermal load radiated from the deposition source. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Rev. Sci. Instrum. 63(9), September 1992, pp. 4227-4228. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide an apparatus for handling substrates having two essentially parallel main surfaces, which allows azimuthal rotation at the end of an arm extending into a vacuum chamber, which is an alternative to prior art apparatus.

[0007] Another object of the invention is to provide an apparatus for handling a substrate having two essentially parallel major surfaces, which allows azimuthal rotation at the end of an arm extending into a vacuum chamber, and which allows more efficient cooling of the substrate than is possible with prior art apparatus. [Means for solving the problem]

[0008] The above object is achieved with a device according to the independent claims.

[0009] Further advantages are provided with the features of the dependent claims.

[0010] According to an aspect of the invention, an apparatus is provided for manipulating a flat substrate having two main surfaces in a vacuum chamber. The apparatus comprises an arm having a first end disposed outside the vacuum chamber, a second end disposed within the vacuum chamber, and a length axis extending between the first and second ends. The arm comprises a cooling surface at the second end for cooling the flat substrate in contact with the cooling surface. The cooling surface has a central axis that is essentially perpendicular to the cooling surface and extends non-parallel to the length axis, and the cooling surface is configured to be cooled by cooling the first end of the arm outside the vacuum chamber. The apparatus further comprises a clamping device for fixing the substrate in contact with the cooling surface. The apparatus is characterized in that the clamping device comprises a first bearing device disposed around and movable in a direction along the central axis, and a substrate clamping device. The substrate clamping device comprises a second bearing device engaging the first bearing device so as to be rotatable about a central axis, and a substrate engagement device fixed to the second bearing device and configured to engage a peripheral edge of the substrate on a side of the substrate facing away from the cooling surface. The apparatus further comprises an adjustable actuation device configured to apply an adjustable actuation force to the first bearing device in a direction along the central axis such that the substrate is pressed towards the cooling surface. The first bearing device and the second bearing device are configured to transfer the actuation force from the first bearing device to the second bearing device and the substrate engagement device.

[0011] With the device according to the above, manipulation of a flat substrate relative to a cooling surface is possible in combination with efficient cooling of the substrate. By decoupling the axial movement of the substrate from its rotation, an advantageous device is achieved that provides high thermal conductivity between the cooling surface and a mounted flat substrate, while at the same time offering the possibility of rotating the substrate around a central axis at any angle.

[0012] By a substrate is meant that it has a main surface and a sub-surface, the main surface being essentially parallel and clearly larger than the sub-surface. The surfaces do not have to be flat, but can be provided with structures. The surface of the substrate facing away from the cooling surface can have larger structures than the surface facing the cooling surface. The dimensions of the structures on the main surface are preferably smaller than the thickness of the flat substrate.

[0013] The substrate can be composed of different materials in different layers, however it is also possible for the substrate to comprise a single layer, such as a semiconductor wafer.

[0014] With this apparatus it is further possible to have a large cross-sectional area for the arm, from the first end to the cooling surface as a whole, which allows for high thermal conductivity and therefore efficient cooling of the substrate.

[0015] The adjustable actuation device can be implemented in many different ways. An important function of the adjustable actuation device is to provide an adjustable actuation force. A higher actuation force can be used to improve cooling efficiency, while a lower actuation force facilitates rotation of the substrate relative to the cooling surface.

[0016] The arm may comprise a protrusion at a second end of the arm extending between the arm and the cooling surface, the first and second bearing devices being arranged around the protrusion. With such a protrusion and with such an arrangement of the first and second bearing devices, access to the cooling surface and therefore to the substrate clamped to the cooling surface is improved. In other words, particles and radiation can reach the substrate from a larger solid angle compared to the absence of the protrusion, in which case the first and second bearing devices would need to be arranged on the same side of the cooling surface as the substrate.

[0017] The length axis of the arm can be positioned orthogonal to a processing device, e.g., a deposition source. In this case, orthogonal positioning of the arm means that the direction of deposition is orthogonal to the length axis of the arm. In this configuration, the substrate surface on the arm can be aligned in any direction from normal incidence to glancing incidence. This is useful for controlling deposition on substrates carrying microstructures on their front side, with sides that are not parallel to the front surface of the main substrate.

[0018] The cooling surface can have a maximum extent smaller than the maximum extent across the substrate between engagement points between the substrate engagement device and the substrate. The substrate is clamped towards the cooling surface by a force from the substrate engagement device on the substrate. An equal and large reaction force is exerted on the substrate by the cooling surface. Due to the difference in extent, the torque of the force from the substrate engagement device is greater than the torque of the force from the cooling surface if the coefficient of friction between the cooling surface and the substrate were equal to the coefficient of friction between the substrate engagement device and the substrate. Thus, rotation of the substrate is possible while keeping it in contact with the cooling surface.

[0019] The substrate engagement device can be configured for rotationally fixed engagement with the substrate, such that the substrate can be rotated even if the coefficient of friction between the cooling surface and the substrate is not equal to or less than the coefficient of friction between the substrate engagement device and the substrate.

[0020] The adjustable actuation device can be configured to apply an adjustable actuation force between the first bearing device and a surface of the arm opposite the cooling surface. Such an arrangement facilitates uniform application of the adjustable actuation force. Additionally, such an arrangement provides a large space for the adjustable actuation device.

[0021] The substrate engaging device and the second bearing device may be a single ring-shaped part. Such an arrangement facilitates assembly of the clamping device.

[0022] The outer surfaces of the substrate engagement device and the second bearing device may include recesses or protrusions for engaging with protrusions and recesses, respectively, on the wheels of the first actuator device to rotate the substrate engagement device and the second bearing device relative to the first bearing device. Using such recesses or protrusions, well-controlled rotation of the substrate is achieved.

[0023] The arm can rotate about its length axis. With such an arrangement, the substrate can be manipulated about two axes while maintaining high thermal conductivity between the first end of the arm and the cooling surface.

[0024] Rotation of the arm about its length axis can be performed manually. Alternatively, the device can include a second actuator for rotation of the arm about its length axis.

[0025] The central axis can be perpendicular to the length axis, which provides for well-controlled manipulation of the substrate.

[0026] The apparatus can be configured such that a surface of the substrate at the central axis, having a predetermined thickness, is essentially at the same position regardless of the rotational position of the arm about the longitudinal axis, said surface facing away from the cooling surface, which may be preferable, for example, when a deposition source is maintained at a constant distance from the substrate.

[0027] The continuous portion of the arm from the first end to the cooling surface can be made of copper, silver, molybdenum, or platinum. The continuous portion can include a joint. It is important that any joint is designed to have high thermal conductivity. The entire arm can constitute the continuous portion.

[0028] In the following, preferred embodiments of the present invention will be described with reference to the accompanying drawings. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 shows an apparatus for handling a flat substrate in a vacuum chamber. [Diagram 2] 2 is a cross-sectional view of the clamping device of the apparatus of FIG. 1 with a substrate attached to the clamping device; [Diagram 3] FIG. 3 is a cross-sectional view of the clamping device of FIG. 2 without a substrate attached. [Figure 4] 3 is a perspective view of the clamping device of FIG. 2 with a substrate placed in the clamping device. [Diagram 5] FIG. 4 is a perspective view of the clamping device of FIG. 3. [Figure 6] FIG. 2 is a plan view taken along the long axis or arm of FIG. 1. [Figure 7] FIG. 2 is a perspective view of a clamping device. [Figure 8] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the following embodiments, the invention will be described with reference to the accompanying drawings, in which like features are designated by like reference numerals in the various drawings, and in which the drawings are not drawn to scale.

[0031] FIG. 1 shows an apparatus 1 for manipulating a flat surface 3 (FIG. 2) having two main faces 4, 5 (FIG. 2) in a vacuum chamber 2, the apparatus 1 comprising an arm 6 having a first end 7 arranged outside the vacuum chamber 2, a second end 8 arranged inside the vacuum chamber 2 and a length axis 9 extending between the first end 7 and the second end 8. The object of the apparatus shown in FIG. 1 allows to simultaneously manipulate and cool a flat substrate 3 (FIG. 2) at the second end 8 of the arm 6. The substrate 3 to be manipulated and cooled is flat, meaning that it has a main plane and a subordinate plane, which are essentially parallel and clearly larger than the subordinate surface. At the second end 8, the arm 6 comprises a cooling surface 10 for cooling the flat substrate 3 (FIG. 2) in contact with the cooling surface 10, the cooling surface 10 having a central axis 11 that essentially extends perpendicular to the cooling surface 3 or non-parallel to the length axis 9. By the central axis 11 essentially extending perpendicularly to the cooling surface 10, it is understood that the central axis 11 extends from the cooling surface 10 at an angle of 90±5 degrees, or more preferably at an angle of 90±1 degree. It is therefore possible that the central axis 11 does not extend perfectly perpendicularly from the cooling surface 10. The cooling surface 10 is preferably flat, but can also have a slight curvature and / or protrusion. If the cooling surface is curved, it is preferably convex. The height difference between the lowest part of the cooling surface and the highest part of the cooling surface is preferably less than 1 percent of the maximum extension of the cooling surface. If the cooling surface is curved and / or has protrusions, they are preferably arranged symmetrically with respect to the central axis 11.

[0032] The cooling surface 10 is configured to be cooled by cooling a first end 7 of the arm 6 outside the vacuum chamber 2. To be able to cool the first end 7 of the arm 6 outside the vacuum chamber 2, the device comprises a cryocooling unit 12 at the first end 7. The cryocooling chamber 12 can be a known cryocooler such as a multi-stage Gifford-MacMahon (GM) cryocooler, a pulse tube cryocooler or a heat exchanger cryostat to which a cooling liquid is supplied externally. The cooling liquid can be, for example, liquid helium or liquid nitrogen, but other cooling liquids can also be envisaged depending on the desired temperature to be reached for the cooling surface 10.

[0033] The arm is also preferably surrounded by a heat shield 45. The heat shield 45 is preferably mounted at an intermediate stage of the cooling assembly 46 to minimize heat radiation to the cooling arm 6 from the surroundings or from other processing sources within the chamber 2. Suitable openings in the bottom or sides of the heat shield can ensure that deposition or other processing occurs only on the portion of the substrate device 3, while ensuring that deposition or other processing does not occur on other parts of the machine.

[0034] In order to be able to achieve a low temperature relative to the cooling surface 10, it is necessary to have a high thermal conductivity in the arm 6, from the cooling surface 10 to the cooling chamber 12. In order to be able to achieve a high thermal conductivity in the arm 6, the continuous part of the arm, from the first end to the cooling surface, is made of a material that has a low specific thermal resistivity at low temperatures. The continuous part can be made of copper, silver, molybdenum and / or platinum. If copper is used, it is advantageous to use copper that is oxygen-free and has a high conductivity. The continuous part can comprise connections, such as the connection 15, which is fixed by the bolt 16. It is important that the connections are designed so that every connection has a high thermal conductivity. In FIG. 1, the whole arm can constitute a continuous part. However, it is also possible that some parts of the arm are not made of a material that has a low specific thermal resistivity, such as the bolt 16. Furthermore, it is of course also possible to have various parts that consist of continuous parts of various materials. One part can be made, for example, of copper, while an adjacent part can be made of another material, such as, for example, of silver.

[0035] The apparatus comprises a clamping device 17 for fixing the substrate 3 (Figure 2) in contact with the cooling surface 10 at the second end 8. The apparatus 1 comprises a first actuator device 43 for rotating the substrate 3 about a central axis 11. The clamping device 17 and the first actuator device 43 shall be described in more detail with reference to Figure 6 below. The clamping device is configured to allow exchange of the substrate 3.

[0036] The arm is rotatable about the length axis 9 by a second actuator 19. Preferably, the apparatus is configured so that the surface of the substrate 3 facing away from the cooling surface 10 at the central axis 11 is essentially in the same position, regardless of the rotational position of the arm 6 about the length axis 9. This is advantageous when the substrate 3 is positioned in a clamping device and undergoes some kind of treatment, e.g. deposition, since the substrate can be rotated about the length axis 9 without changing the distance to the deposition source. The main desired technical effect is to maintain the position of the surface of the substrate 3 (FIG. 2) at the central axis 11, rather than the cooling surface 10 at the central axis 11. This requires that a substrate 3 with a known and predetermined thickness is used. However, slight movements of the surface of the substrate 3 at the central axis are acceptable for many applications. In such cases, the thickness of the substrate should not be pre-determined.

[0037] The device 1 may comprise further actuators for linear actuation of the entire arm along one or more linear axes 14. This allows for more accurate alignment of the position of the substrate device 3 undergoing some processing in the chamber 2.

[0038] Figure 2 shows in cross section the clamping device 17 mentioned above with a substrate 3 attached to it. Figure 3 shows in cross section the clamping device 17 without a substrate attached to it. Only the second end 8 of the arm 6 is shown in Figure 2. At the second end 8 the arm 6 is provided with a protrusion 20 which extends between the arm 6 and the cooling surface.

[0039] Figures 4 and 5 show perspective views of the clamping device 17 of Figures 2 and 3. In Figure 4, a substrate 3 is placed in the clamping device 17. Figure 6 is a plan view looking along the longitudinal axis 9 in the direction from the second end 8 to the first end 7. Figure 7 is a perspective view of the clamping device. Figure 8 is a perspective view of the substrate 3.

[0040] The clamping device 17 comprises a first bearing device 21 arranged around the central axis 11 and movable in a direction along the central axis 11. The first bearing device 21 is arranged around the protrusion 20. The clamping device 17 also comprises a substrate clamping device 22 arranged around the protrusion 20 and comprising a second bearing device 23 engaging with the first bearing device 21, such that the second bearing device 23 is rotatable around the central axis 11 at any angle. The substrate clamping device 22 also comprises a substrate engagement device 24 fixed to the second bearing device 23 and configured to engage the periphery of the substrate 3 against a side of the substrate 3 facing away from the cooling surface 10. In the embodiment shown, the substrate engagement device 24 and the second bearing device 23 are parts forming a single ring.

[0041] The clamping device also comprises an adjustable actuation device 25 configured to apply an adjustable actuation force to the first bearing device 21 in a direction along the central axis 11, such that the substrate 3 is pressed towards the cooling surface 10. The first bearing device 21 and the second bearing device 23 are configured to transmit the actuation force from the first bearing device 21 to the second bearing device 23 and the substrate engagement device 24.

[0042] In FIG. 2, the substrate 3 has a stepped cross-sectional shape. A first side 4 of the substrate 3 is arranged against the cooling surface 10, whereas a second side 5 of the substrate 3 is arranged opposite the cooling surface 10. The substrate 3 can be made of several materials that are joined together, for example by soldering, preferably with a metal having a low melting point, such as gallium, indium, or an alloy of gallium or indium. In some applications of the assembly, the front side of the substrate 3, i.e. the surface of the substrate facing away from the cooling surface 10, can be made of a semiconductor wafer, whereas the holder 28 of the substrate device can be made of a material that has a high thermal conductivity at low temperatures, such as oxygen-free high conductivity copper, silver, molybdenum, or platinum. The holder 28 has a larger extent than the semiconductor wafer. As a result, the periphery of the substrate 3 is thinner than the rest of the substrate 3. The step in thickness occurs at the second side 5 of the substrate 3. In this embodiment, the periphery 47 of the substrate, which is the periphery of the holder 28, comes into contact with the substrate engagement device 24. The step in the cross-sectional shape of the substrate 3 results in the engagement device not protruding below the second side 5 of the substrate. This means that access to the second side 5 of the substrate is improved. As can be seen in FIG. 3, the substrate engagement device comprises a shelf 29 on which the periphery 47 of the substrate 3 (FIG. 2) can be supported. Of course, it is also possible for the substrate 3 to have only a single layer, which may or may not comprise a step in thickness at the periphery. The substrate 3 may for example be a semiconductor wafer.

[0043] The actuation device 25 shall now be described in more detail. In the embodiment shown in Figures 2 and 3, the actuation device 25 comprises a disk spring 30, i.e. a circular disk. The periphery of the disk spring 30 is connected to the first bearing device 21 by a first screw 31. The central part of the disk spring is attached to an actuator 32, which in the embodiment shown consists of an adjustment screw 33 in threaded engagement with a disk 34 and in rotational engagement with a bottom plate 35. The disk 34 is connected to the disk spring 30 by a second screw 36. When the adjustment screw is rotated, it will force the disk 34 up or down depending on the direction of rotation. When the disk moves up, the disk spring 30 transfers the movement in a direction along the central axis to the first bearing device 21 and also to the second bearing device 23 and the substrate engagement device 24. In Figure 2, the substrate engagement device 24 contacts the substrate 3, which contacts the cooling surface. The substrate 3 is pushed towards the cooling surface by the substrate engagement device 24. In Fig. 2, when the disk 34 moves upwards, this will cause an increased force between the bottom plate 35 and the disk 34, and therefore an increased force from the disk spring 30 on the first bearing device 21, on the second bearing device 23 and on the substrate engagement device 24. Thus, by turning the adjustment screw, an adjustable actuation force is applied to the first bearing device 21, to the second bearing device 23 and to the substrate engagement device 24. Furthermore, in Figs. 2 and 3 a locking ring 37 is shown, which prevents movement of the second bearing device 23 relative to the first bearing device 21.

[0044] It is also possible to use an actuation device 25 different from that shown in Figures 2 and 3. It would also be possible to replace the adjustment screw with a piezoelectric actuator. Of course, it would not be necessary to apply a force between the arm 6 and the substrate engagement device 24 as shown in Figures 2 and 3.

[0045] It would also be possible to eliminate the protrusion 20. However, doing so would require the first bearing device 21 and the second bearing device 23 to protrude below the cooling surface 10. This would result in poor access to the second surface 5 of the substrate 3.

[0046] In the embodiment shown in FIG. 2, the cooling surface 10 has a maximum extension that is smaller than the maximum extension across the substrate 3 between the engagement points between the substrate engagement device 24 and the substrate. This facilitates rotation of the substrate 3 relative to the cooling surface 10. Assuming that the coefficient of friction between the substrate engagement device 24 and the substrate 3 is the same as the coefficient of friction between the cooling surface 10 and the substrate 3, a large diameter at the periphery would result in a large torque from the substrate engagement device 24. However, if the coefficient of friction between the substrate engagement device 24 and the substrate 3 is lower than the coefficient of friction between the cooling surface 10 and the substrate 3, it may be advantageous to have a substrate engagement device that is configured to have a rotationally fixed engagement with the substrate. As can be seen in FIG. 5, a protrusion 38 is formed on the substrate engagement device 24. The protrusion is for engaging a corresponding recess 39 in the substrate 3, as can be seen in FIG. 8.

[0047] As can be seen in Figures 4 to 7, the outer surfaces of the substrate engagement device 24 and the second bearing device 23 are provided with recesses 40 for engaging with protrusions 41 on a wheel 42 (Figure 6) of a first electric actuator device 43 for rotating the substrate engagement device 24 and the second bearing device 23 relative to the first bearing device. Of course, it is also possible to have recesses on the wheel 42 and protrusions on the substrate engagement device 24 and the second bearing device 23. The first actuator device 43 and the adjusting screw 33 can be configured to be operated manually from outside the vacuum chamber or automatically using an electric actuator motor 44 as shown by the wheel 42 in Figure 6.

[0048] The above described embodiments can be modified in many ways without departing from the scope of the invention, which is limited only by the appended claims. [Explanation of symbols]

[0049] 1 device 2. Vacuum chamber 3. Flat Surface 4 Main surface, first side 5 Main surface, second side surface 6 Arm 7 First end 8 Second end 9 Length Axis 10 Cooling surface 11 Center axis 12 Refrigerator cooling unit, cooling chamber 14 Linear axis 15 Connecting part 16 Volts 17 Clamping Device 19 Second Actuator 20 Protrusion 21 First bearing device 22 Substrate clamp device 23 Second bearing device 24 Substrate Engagement Device 25 Adjustable Actuation Device 28 Holder 29 Shelves 30 Disc spring 31 First screw 32 Actuator 33 Adjustment screw 34 Discs 35 Bottom Plate 36 Second screw 37 Locking Ring 38 Protrusion 39 Depression 41 Protrusion 42 Wheels 43 First Actuator Device 44 Electric Actuator Motor 45 Heat Shield 46 Cooling Group Stereo 47 Zhou Yu d1 Maximum extension length d2 Maximum extension length

Claims

1. An apparatus (1) for manipulating a flat substrate (3) having two main surfaces (4, 5) in a vacuum chamber (2), comprising: an arm (6) having a first end (7) disposed outside the vacuum chamber (2), a second end (8) disposed within the vacuum chamber (2), and a length axis (9) extending between the first end (7) and the second end (8); The arm (6) at the second end (8) a cooling surface (10) for cooling the flat substrate (3) in contact with said cooling surface (10), said cooling surface (10) having a central axis (11) extending essentially perpendicular to said cooling surface (10) and non-parallel to said length axis (9), said cooling surface (10) being configured to be cooled by cooling said first end (7) of said arm (6) outside said vacuum chamber (2); a clamping device (17) for fixing the substrate (3) in contact with the cooling surface (10); Equipped with The clamping device (17) a first bearing device (21) arranged around said central axis (11) and movable in a direction along said central axis (11); A substrate clamping device (22), comprising: a second bearing device (23) engaging with the first bearing device (21) such that the second bearing device (23) is rotatable about the central axis (11); and a substrate engagement device (24) fixed to the second bearing device (23) and configured to engage a peripheral edge (47) of the substrate on a side of the substrate facing away from the cooling surface (10); a substrate clamping device (22) comprising: an adjustable actuation device (25) configured to apply an adjustable actuation force to the first bearing device (21) in a direction along the central axis (11) such that the substrate (3) is pressed towards the cooling surface (10), the first bearing device (21) and the second bearing device (23) being configured to transmit the actuation force from the first bearing device (21) to the second bearing device (23) and the substrate engagement device (24); An apparatus (1), comprising:

2. 2. The apparatus (1) of claim 1, wherein the arm (6) comprises a protrusion (20) at the second end (8) of the arm (6) extending between the arm (6) and the cooling surface (10), and the first bearing device (21) and the second bearing device (23) are arranged around the protrusion (20).

3. The apparatus (1) of claim 1 or 2, wherein the cooling surface (10) has a maximum extension length (d1) that is smaller than a maximum extension length (d2) across the substrate (3) between engagement points between the substrate engagement device (24) and the substrate (3).

4. The apparatus (1) of claim 3, wherein the substrate engagement device (24) is configured for rotationally fixed engagement with the substrate (3).

5. 5. The apparatus (1) according to claim 1, wherein the adjustable actuation device (25) is configured to apply the adjustable actuation force between the first bearing device (21) and a surface of the arm opposite the cooling surface (10).

6. The apparatus (1) according to any one of the preceding claims, wherein the substrate engagement device (24) and the second bearing device (23) are part of a single ring-shaped member.

7. 7. The apparatus (1) of claim 6, wherein outer surfaces of the substrate engagement device (24) and the second bearing device (23) are provided with recesses (40) or protrusions for engaging with protrusions (41) and recesses, respectively, on a wheel (42) of a first actuator device (43) to rotate the substrate engagement device (24) and the second bearing device (23) relative to the first bearing device (21).

8. 8. The device (1) according to any one of the preceding claims, wherein the arm (6) is rotatable about its longitudinal axis (9).

9. 9. The device (1) according to claim 8, comprising a second actuator (19) for rotating the arm (6) about its longitudinal axis (9).

10. 10. The device (1) according to claim 8 or 9, wherein the central axis (11) is perpendicular to the longitudinal axis (9).

11. The apparatus (1) according to any one of claims 8 to 10, wherein the apparatus (1) is configured such that, at the central axis (11), a surface of a substrate (3) having a predetermined thickness is in essentially the same position regardless of the rotational position of the arm (6) about the length axis (9).

12. 12. The device (1) according to any one of the preceding claims, wherein the continuous portion of the arm (6) from the first end to the cooling surface (10) is made from copper, silver, molybdenum or platinum.

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