Patent Publication Number: US-2021190131-A1

Title: Treatment machine, drive unit for a treatment machine and use of the treatment machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This present application claims priority to German Patent Application No. DE 10 2019 008 884.0, filed Dec. 19, 2019, which is hereby incorporated by reference in its entirety. 
     FIELD OF THE INVENTION 
     The invention relates to devices and methods for treating substrates. The invention in particular relates to such devices and methods in which a heated shaft extends into a chamber. 
     TECHNICAL FIELD 
     Treatment machines for the treatment of substrates, which can be configured as continuous machines or as batch-type machines, are widely used. Exemplary machines are chalcogen vapor deposition machines or machines for the thermal treatment of substrates, for example to carry out a heat treatment of layers deposited onto the substrates. 
     It may be necessary or desirable to adjust the temperature of components present in a process chamber to a specific temperature or temperature range. For example, in chalcogen vapor deposition machines without such a temperature control, undesired high condensations may occur on non-temperature-controlled components of the treatment machine which are located close to the substrates or substrate carriers. Such depositions on components of the treatment machine can shorten the maintenance intervals in an undesirable way. 
     While the temperature control of stationary elements in the process chamber can usually be carried out with little effort, the temperature control of components extending into the process chamber, especially moving components in the process chamber, such as rotating shafts, may be technically more complex. In the case of shafts with temperature control by means of oil, for example, it may be difficult to avoid leakages on mechanical rotary transmission feedthroughs due to technical reasons. In the case of such shafts with temperature control by means of oil, heated thermal oil is typically introduced into a double-walled shaft through a mechanical rotary transmission feedthrough. 
     DE 10 2009 016 677 A1 describes a hollow shaft that can be heated with steam. The steam ducts render the configuration complex. 
     EP 0 918 945 B1 discloses a roller which can be heated and the roller body of which comprises channels with a vaporizable fluid, wherein an electrical radiant heating system is provided. The use of the channels in the roller body renders the configuration of the roller complex. 
     DE 693 659 A discloses an electrically heated calender roll the roll shell of which tightly encloses a roll core. The electrical components are stationarily installed. 
     DE 3 033 689 A1 discloses an electrically heatable roll with an inner tube and an outer tube coaxially arranged at a distance from the inner tube and forming a roll shell, said inner and outer tubes defining an annular space in which several heating mats butting against each other and being circumferentially distributed are inserted. Sliding contacts are provided for the energy supply of the heating mats. Such sliding contacts are susceptible to wear. 
     DE 10 2011 082 334 A1 describes a substrate treatment machine for treating disk-shaped substrates in a horizontal position with a transport device comprising a plurality of transport rollers with a hollow space in which a heating medium is arranged. The heating medium is to be insertable into the hollow space of the roller body from outside through a hollow shaft of a rotary transmission feedthrough. However, this design is disadvantageous, inter alia, because the provision of such a rotatably supported hollow shaft is technically complex, expensive and prone to errors. 
     There is a need for improved devices and methods by means of which the temperature of a shaft extending at least partially in a process chamber of a treatment machine can be controlled, in particular heated. In particular, there is a need for such devices and methods that allow temperature control of the shaft by means of a simple arrangement and that avoid the problem of liquid leakage, which may occur in the case of shafts with temperature control by means of oil or vapor. 
     SUMMARY OF THE INVENTION 
     According to the invention, a treatment machine, a drive unit and uses of such treatment machines and drive units comprising the features specified in the independent claims are provided. The dependent claims define preferred embodiments. 
     According to the invention, a configuration is proposed in which an electrical heating device, in particular a heating cartridge, is arranged in a non-rotating manner in the interior of a shaft. An accommodation mandrel is provided to accommodate an electrical heating device or heating cartridge. The accommodation mandrel is arranged in a non-rotating manner relative to a chamber of the treatment machine. 
     A gap extends between an outer surface of the accommodation mandrel and an inner surface of the shaft. Heat transfer between the accommodation mandrel and the rotatably supported shaft can take place in particular by means of a gas provided between the shaft and the accommodation mandrel. The heat transfer can essentially take place by means of heat conduction through this gas in the interior of the shaft. 
     The leakages on rotary transmission feedthroughs frequently occurring in the case of temperature control by means of oil can be prevented by using an electrically temperature-controlled shaft. The treatment machine and the drive unit used therein are robust and of a mechanically simple design. 
     By using an accommodation mandrel that does not rotate relative to the chamber, a heating cartridge or any other electrical heating device can be arranged and electrically connected in the accommodation mandrel in such a way that it is reversibly removable in an easy and non-destructive manner. 
     It is not necessary to provide a slip ring contact as would be necessary in the case of a rotating heating cartridge. Such a slip ring contact would be more complicated to implement and could shorten the maintenance intervals in an undesirable way. 
     In addition, it is difficult to measure/control the temperature of a rotating shaft since the thermoelectric voltages would also have to be tapped via slip rings. 
     The stationary accommodation mandrel, i.e., the accommodation mandrel not rotating during operation, may be configured to accommodate conventional heating cartridges, in particular standard heating cartridges. 
     The accommodation mandrel may be configured such that it is relatively resistant to bending and can also be used for shafts having a length of more than 600 mm. 
     A treatment machine according to the invention comprises a chamber for the treatment of one or more substrates. A rotatably supported temperature-controlled shaft is provided. The shaft defines a cylindrical, advantageously gas-tight, hollow space. The treatment machine comprises a heating arrangement for electrically heating at least a part of the shaft arranged in the chamber. The heating arrangement comprises an accommodation mandrel for accommodating an electrical heating device, said accommodation mandrel being arranged in a non-rotating manner and extending into the hollow space of the shaft. An outer surface of the accommodation mandrel is spaced apart from an inner surface of the shaft by a gap. 
     If the shaft defines a gas-tight hollow space, the hollow space defined by the shaft is gas-tight with respect to a treatment space defined in the interior of the chamber. However, it is not excluded that even in the case of a “gas-tight hollow space” the hollow space in the interior of the shaft comprises openings that allow gas to pass between the hollow space in the interior of the shaft and a volume outside the treatment space. For example, even in the case of a hollow space that is configured to be gas-tight (which means in particular a hollow space that is sealed against the treatment space), ambient air may be able to enter the hollow space in the interior of the shaft from volumes outside the treatment space and/or air may be able to exit the hollow space in the interior of the shaft into volumes outside the treatment space. Alternatively or additionally, feedthroughs may be provided, for example for introducing a heat-conducting fluid into the hollow space and/or for removing a heat-conducting fluid from the hollow space, wherein the gas exchange between the treatment space of the chamber and the hollow space in the interior of the shaft remains prevented. 
     At least a part of the shaft may extend in a treatment space defined by the chamber. 
     The electrical heating device may be a heating cartridge or may comprise a heating cartridge. 
     The shaft may be configured to be dividable. 
     The shaft may be configured to be dividable such that it is mountable at the chamber in at least two different orientations. This renders the treatment machine reconfigurable such that depending on how the shaft is mounted the heating cartridge is insertable into the accommodation mandrel from different side walls of the chamber. 
     Dividable connections of the shaft may be provided with a seal to seal a volume defined between the accommodation mandrel and the inner surface of the shaft against a treatment space defined by the chamber. 
     The treatment machine may further comprise an evacuation device for evacuating the treatment space. 
     The treatment machine may be configured such that the treatment space is evacuable to a static pressure of less than 1 Pa, in particular less than 0.1 Pa, in particular less than 10 −2  Pa, in particular less than 10 −3  Pa and in particular less than 10 −4  Pa. 
     The treatment machine may be configured to maintain an overpressure in a volume defined between the accommodation mandrel and the shaft relative to a treatment space defined by the chamber. 
     The treatment machine may be configured to maintain the volume defined between the accommodation mandrel and the shaft at atmospheric pressure when evacuating the treatment space. 
     Optionally, a gaseous medium, in particular air, helium or hydrogen, may be present in the volume defined between the accommodation mandrel and the shaft. 
     The gap between the outer surface of the accommodation mandrel and the inner surface of the shaft may be greater than 0.3 mm, in particular greater than 0.5 mm, in particular greater than 0.7 mm, in particular greater than 1 mm. 
     The gap between the outer surface of the accommodation mandrel and the inner surface of the shaft may be smaller than 4 mm, in particular smaller than 3 mm, in particular smaller than 2.2 mm, in particular smaller than 1.9 mm. 
     The gap can be measured in a central plane between the walls of the chamber extending perpendicularly to the rotation axis of the shaft. If the distance between the outer surface of the accommodation mandrel and the inner surface of the shaft (in each case measured along a radial direction from the central axis of the shaft) varies along the circumference of the accommodation mandrel, the gap can be defined as the circumferentially averaged distance. 
     The gap between the outer surface of the accommodation mandrel and the inner surface of the shaft may be dimensioned such that the inner surface of the shaft is rotatable around the outer surface of the accommodation mandrel without any contact. 
     The outer surface of the accommodation mandrel may have a diameter of at least 15 mm, in particular at least 20 mm, in particular at least 22 mm. 
     The diameter of the outer surface of the accommodation mandrel can be measured in a central plane between the walls of the chamber extending perpendicularly to the rotation axis of the shaft. If the radius of the outer surface of the accommodation mandrel (in each case measured along a radial direction from the central axis of the accommodation mandrel) varies along the circumference of the accommodation mandrel, the diameter can be defined as the circumferentially averaged diameter. 
     The outer surface of the accommodation mandrel may be blackened. Heat transfer by thermal radiation can thus be improved. 
     The inner surface of the accommodation mandrel may be blackened. Heat transfer by thermal radiation can thus be improved. 
     A thermal conductivity between the outer surface of the accommodation mandrel and the inner surface of the shaft per unit of axial length of the outer surface of the accommodation mandrel may be at least 0.4 W/(K·m), at least 0.5 W/(K·m), at least 0.6 W/(K·m), at least 0.8 W/(K·m) or at least 0.9 W/(K·m). 
     The thermal conductivity between the outer surface of the accommodation mandrel and the inner surface of the shaft per unit of axial length of the outer surface of the accommodation mandrel may be maximally 9 W/(K·m), maximally 8 W/(K·m), maximally 7 W/(K·m), maximally 6 W/(K·m) or maximally 4 W/(K·m). 
     The outer surface of the accommodation mandrel may be cylindrical along at least a portion of the accommodation mandrel. 
     The outer surface of the accommodation mandrel may comprise portions having different outer cross-sections arranged along an axis of the accommodation mandrel. This facilitates the arrangement of bearings with smaller diameters, e.g., in areas at the tail of the accommodation mandrel. 
     The treatment machine may further comprise at least one bearing between the accommodation mandrel and the inner surface of the shaft. 
     The shaft may be rotatably connected to the chamber via at least one further bearing. 
     The accommodation mandrel may have a maximum wall thickness of at least 2 mm, of at least 3 mm or of at least 4.5 mm. 
     The maximum wall thickness of the accommodation mandrel can be measured in a central plane between the walls of the chamber extending perpendicularly to the rotation axis of the shaft. 
     The accommodation mandrel may define a further cylindrical hollow space in its interior. 
     The treatment machine may comprise an electrical heating device, in particular a heating cartridge, which is or can be arranged in the further cylindrical hollow space of the accommodation mandrel. 
     The heating cartridge may be a single-piece element that is insertable into the hollow space of the accommodation mandrel. 
     The heating cartridge and the accommodation mandrel may be configured such that the heating cartridge is reversibly insertable into and removable from the accommodation mandrel in a non-destructive manner. 
     A configuration of the heating cartridge may be adapted to a position of a seal or bearing that may be provided between the accommodation mandrel and the shaft and/or between different parts of the shaft that are detachably connectable to each other. 
     The heating cartridge may be configured such that active heating elements are only arranged in an area of the heating cartridge that ends (viewed in the axial direction of the shaft) at a distance from the seal and/or bearing. 
     An outer surface of the heating cartridge arranged in the accommodation mandrel may be spaced apart from an inner surface of the accommodation mandrel by at most 1 mm, by at most 0.5 mm or by at most 0.25 mm. 
     A further cylindrical hollow space in the interior of the accommodation mandrel may comprise a material that is provided between the heating cartridge and the accommodation mandrel. In particular, there may be a casting material between the heating cartridge or electrical heating element and the accommodation mandrel, by means of which the electrical heating element is permanently integrated into the accommodation mandrel. Suitable casting materials are, for example, temperature-resistant heat-conducting media, preferably on a metallic basis. For example, a silver paste from the company PELCO may be used. 
     Accordingly, the electrical heating element may also be an integral component of the accommodation mandrel. In the case of this embodiment, the electrical heating element preferably cannot be removed from the accommodation mandrel in a reversible and non-destructive manner. Rather, the accommodation mandrel is replaced together with the heating element if a replacement of the heating element becomes necessary. Accordingly, the accommodation mandrel preferably can be removed in a reversible and non-destructive manner from the hollow space of the shaft to replace the electrical heating element. This involves the advantage that the possibly sensitive heating element cannot be accidentally damaged when it is inserted into the accommodation mandrel. Rather, the heating element and the accommodation mandrel form a compact, dimensionally stable unit. Furthermore, a particularly good heat conduction from the heating element into the mandrel can be achieved in the case of this arrangement. For this purpose, it is preferred that the material provided between the heating cartridge and the accommodation mandrel has a thermal conductivity of at least 4 W/(K·m), more preferably of at least 6 W/(K·m) and particularly preferably of at least 8 W/(K·m). 
     The accommodation mandrel comprises a first end on the side of the access to the hollow space of the shaft and an opposite second end. Preferably, the accommodation mandrel is supported at its second end in the hollow space of the shaft. In order to facilitate the correct positioning of the second end in this bearing when the accommodation mandrel is inserted, the accommodation mandrel preferably has a taper or other guiding device at its second end to be inserted into the bearing. 
     When the heating cartridge and the accommodation mandrel are not connected to each other via a casting material, the material provided between the heating cartridge and the accommodation mandrel may have a thermal conductivity of at least 0.05 W/(K·m) or at least 0.1 W/(K·m). 
     The accommodation mandrel may comprise one or a combination of the following materials: structural steel such as ST 37-2 or S235JR (according to EN 100025-2), stainless steel, aluminum, aluminum alloys as well as other metals or metal alloys having sufficiently high thermal conductivity. 
     Preferably, the accommodation mandrel is black-oxide finished to blacken the surface. 
     The shaft may have a length of at least 600 mm. 
     The heating arrangement may be configured to heat the shaft to a temperature between 140° C. and 220° C. 
     The heating arrangement may be configured to heat the shaft to a temperature between 160° C. and 200° C. 
     The heating arrangement may be configured to heat the shaft to a temperature of approximately 180° C. 
     The treatment machine may be a coating machine. 
     The treatment machine may comprise a source of reactive gas or reactive vapor. 
     The treatment machine may be a machine for the vapor deposition of materials at temperatures of the chamber wall and/or installed components of at least 140° C., for example, for the vapor deposition of chalcogens, in particular selenium. 
     The treatment machine may be a machine for thermal treatment. 
     The treatment machine may comprise a temperature control for controlling a temperature of the electrical heating device located in the accommodation mandrel in an open loop or in a closed loop mode. 
     The temperature control may comprise at least one thermocouple element. 
     A drive unit for a treatment machine according to the invention comprises a rotating shaft. The shaft defines a cylindrical hollow space. The drive unit comprises a heating arrangement for electrically heating at least a part of the shaft, wherein the heating arrangement comprises an accommodation mandrel for accommodating an electrical heating device, in particular a heating cartridge, which is mountable in a non-rotating manner and which extends into the hollow space of the shaft, wherein an outer surface of the accommodation mandrel is spaced apart from an inner surface of the shaft by a gap. 
     The drive unit may comprise a thermocouple element for temperature control of the heating arrangement in a closed loop mode. 
     The shaft may be configured to be dividable, wherein each of one or more dividable connections of the shaft is provided with a seal to seal a volume defined between the accommodation mandrel and the inner surface of the shaft against a treatment space. 
     The drive unit may comprise an electrical heating device, in particular a heating cartridge, which is or can be arranged in a further cylindrical hollow space of the accommodation mandrel. 
     A configuration of the heater cartridge may thus be adapted to a position of a seal or bearing that may be provided between the accommodation mandrel and the shaft and/or between different parts of the shaft that are detachably connectable to each other. 
     The heating cartridge may be configured such that active heating elements are only arranged in an area of the heating cartridge that ends (viewed in the axial direction of the shaft) at a distance from the seal and/or bearing. 
     The drive unit may be configured such that it is mountable at the treatment machine in two different orientations. This renders the treatment machine easily reconfigurable such that the heating cartridge is insertable into the accommodation mandrel from different sides of the treatment machine. 
     The drive unit may be configured for use in the treatment machine according to the invention. Further optional features of the drive unit correspond to the features explained with reference to the treatment machine. 
     According to the invention, a method is specified which comprises: rotating a rotatably supported element in a chamber of a treatment machine, wherein the treatment machine is a treatment machine according to the invention and/or comprises a drive unit according to the invention. 
     The method may be a method for coating substrates. 
     The method may be a method for thermally treating substrates, for example, for thermally treating layers deposited onto the substrates. 
     The treatment machine according to the invention, the drive unit according to the invention and the uses according to the invention allow temperature control of the shaft by means of a simple arrangement when treating substrates and avoid the problem of liquid leakage. 
     Aspects of the invention include the following: 
     1. A treatment machine comprising: 
     a chamber ( 11 ) for the treatment of one substrate ( 18 ) or a plurality of substrates ( 18 ), 
     a rotatably supported temperature-controlled shaft ( 30 ), wherein said shaft ( 30 ) defines a cylindrical, gas-tight hollow space, and 
     a heating arrangement ( 40 ,  50 ) for electrically heating at least a part of the shaft ( 30 ) arranged in the chamber ( 11 ), 
     wherein said heating arrangement ( 40 ,  50 ) comprises an accommodation mandrel ( 40 ) for accommodating at least one electrical heating element ( 50 ), in particular a heating cartridge, said accommodation mandrel ( 40 ) being arranged in a non-rotating manner and extending into the hollow space of the shaft ( 30 ), 
     wherein an outer surface ( 41 ) of the accommodation mandrel ( 40 ) is spaced apart from an inner surface ( 31 ) of the shaft ( 30 ) by a gap ( 39 ). 
     2. The treatment machine according to aspect  1 , wherein the shaft ( 30 ) is configured to be dividable, wherein dividable connections of the shaft ( 30 ) are provided with a seal ( 37 ,  38 ) to seal a volume defined between the accommodation mandrel ( 40 ) and the inner surface ( 31 ) of the shaft ( 30 ) against a treatment space ( 15 ) defined by the chamber ( 11 ). 
     3. The treatment machine according to aspect  1  or aspect  2 , further comprising an evacuation device for evacuating the treatment space ( 15 ). 
     4. The treatment machine according to aspect  3 , wherein the treatment space ( 15 ) is evacuable to a static pressure of less than 1 Pa, in particular less than 0.1 Pa, in particular less than 10 −2  Pa, in particular less than 10 −3  Pa and in particular less than 10 −4  Pa. 
     5. The treatment machine according to any one of the preceding aspects, wherein said treatment machine ( 10 ) is configured to maintain an overpressure in a volume defined between the accommodation mandrel ( 40 ) and the shaft ( 30 ) relative to a treatment space ( 15 ) defined by the chamber ( 11 ), in particular to maintain the pressure in the volume defined between the accommodation mandrel ( 40 ) and the shaft ( 30 ) at atmospheric pressure when evacuating the treatment space ( 15 ), wherein optionally a gaseous medium, in particular air, helium or hydrogen, is present in the volume defined between the accommodation mandrel ( 40 ) and the shaft ( 30 ). 
     6. The treatment machine according to any one of the preceding aspects, 
     wherein the gap ( 39 ) between the outer surface ( 41 ) of the accommodation mandrel ( 40 ) and the inner surface ( 31 ) of the shaft ( 30 ) is greater than 0.3 mm, greater than 0.5 mm, greater than 0.7 mm or greater than 1 mm. 
     7. The treatment machine according to any one of the preceding aspects, 
     wherein the gap ( 39 ) between the outer surface ( 41 ) of the accommodation mandrel ( 40 ) and the inner surface ( 31 ) of the shaft ( 30 ) is smaller than 3 mm, smaller than 2.2 mm or smaller than 1.9 mm. 
     8. The treatment machine according to aspect  7 , wherein the gap ( 39 ) is dimensioned such that the inner surface ( 31 ) of the shaft ( 30 ) is rotatable around the outer surface ( 41 ) of the accommodation mandrel ( 40 ) without any contact. 
     9. The treatment machine according to any one of the preceding aspects, wherein the outer surface ( 41 ) of the accommodation mandrel ( 40 ) has a diameter of at least 15 mm, at least 20 mm or at least 22 mm. 
     10. The treatment machine according to any one of the preceding aspects, wherein the outer surface ( 41 ) of the accommodation mandrel ( 40 ) and/or the inner surface ( 31 ) of the shaft ( 30 ) are blackened. 
     11. The treatment machine according to any one of the preceding aspects, wherein a thermal conductivity between the outer surface ( 41 ) of the accommodation mandrel ( 40 ) and the inner surface ( 31 ) of the shaft ( 30 ) per unit of axial length of the outer surface ( 41 ) of the accommodation mandrel ( 40 ) is at least 0.4 W/(K·m) or at least 0.5 W/(K·m). 
     12. The treatment machine according to any one of the preceding aspects, wherein the outer surface ( 41 ) of the accommodation mandrel ( 40 ) is cylindrical along at least a portion of the accommodation mandrel ( 40 ). 
     13. The treatment machine according to aspect  12 , wherein the outer surface ( 41 ) of the accommodation mandrel ( 40 ) comprises portions having different outer cross-sections arranged along an axis of the accommodation mandrel ( 40 ). 
     14. The treatment machine according to any one of the preceding aspects, wherein the shaft ( 30 ) is rotatably connected to the chamber ( 11 ) via at least one bearing ( 14 ). 
     15. The treatment machine according to any one of the preceding aspects, further comprising at least one bearing ( 60 ) between the accommodation mandrel ( 40 ) and the inner surface ( 31 ) of the shaft ( 30 ). 
     16. The treatment machine according to any one of the preceding aspects, wherein the accommodation mandrel ( 40 ) defines a further cylindrical hollow space in its interior. 
     17. The treatment machine according to aspect  16 , further comprising a heating cartridge ( 50 ), which is or can be arranged in the further cylindrical hollow space of the accommodation mandrel ( 40 ). 
     18. The treatment machine according to aspect  17 , wherein a configuration of the heating cartridge ( 50 ) is adapted to a position of a seal ( 16 ,  17 ,  37 ,  38 ) or a bearing ( 14 ,  60 ), wherein in particular the heating cartridge ( 50 ) is configured such that an area ( 51 ) of the heating cartridge ( 50 ) containing active heating elements ends at a distance from the seal ( 16 ,  17 ,  37 ,  38 ) or the bearing ( 14 ,  60 ). 
     19. The treatment machine according to aspect  17  or aspect  18 , wherein an outer surface ( 41 ) of the heating cartridge ( 50 ) arranged in the accommodation mandrel ( 40 ) is spaced apart from an inner surface ( 31 ) of the accommodation mandrel ( 40 ) by at most 1 mm, 0.5 mm or 0.25 mm. 
     20. The treatment machine according to aspect  18  or aspect  19 , wherein the further cylindrical hollow space comprises a material between the heating cartridge ( 50 ) and the accommodation mandrel ( 40 ), wherein said material has a thermal conductivity of at least 0.05 W/(K·m), in particular of at least 0.1 W/(K·m), preferably of at least 4 W/(K·m), more preferably of at least 6 W/(K·m). 
     21. The treatment machine according to any one of the preceding aspects, wherein the electrical heating element ( 50 ) is an integral component of the accommodation mandrel ( 40 ), preferably cast with it. 
     22. The treatment machine according to any one of the preceding aspects, wherein the accommodation mandrel ( 40 ) can be removed from the hollow space of the shaft ( 30 ) to replace the electrical heating element ( 50 ). 
     23. The treatment machine according to aspect  22 , wherein the accommodation mandrel is supported at its distal end in the hollow space of the shaft ( 30 ) and comprises a taper at its distal end to be inserted into the bearing ( 60 ). 
     24. The treatment machine according to any one of the preceding aspects, wherein the shaft ( 30 ) has a length of at least 600 mm. 
     25. The treatment machine according to any one of the preceding aspects, wherein the heating arrangement ( 40 ,  50 ) is configured to heat the shaft ( 30 ) to a temperature between 140° C. and 220° C., in particular to approximately 180° C. 
     26. The treatment machine according to any one of the preceding aspects, wherein said treatment machine is a coating machine. 
     27. The treatment machine according to aspect  26 , further comprising a source of reaction gas or reaction vapor. 
     28. The treatment machine according to aspect  26  or aspect  27 , wherein said treatment machine is a machine for the vapor deposition of materials at temperatures of at least 140° C. of the chamber wall and installed components, for example, for the vapor deposition of chalcogens, in particular selenium. 
     29. The treatment machine according to any one of the preceding aspects, wherein said treatment machine is a machine for thermal treatment. 
     30. The treatment machine according to aspect  29 , further comprising a temperature control for controlling a temperature of the heating device ( 50 ) located in the accommodation mandrel ( 40 ) in an open loop or in a closed loop mode. 
     31. A drive unit ( 20   a - c ) for a treatment machine ( 10 ), comprising: 
     a rotating shaft ( 30 ), wherein said shaft ( 30 ) defines a cylindrical hollow space, and 
     a heating arrangement ( 40 ,  50 ) for electrically heating at least a part of the shaft ( 30 ), wherein said heating arrangement ( 40 ,  50 ) comprises an accommodation mandrel ( 40 ) for accommodating at least one electrical heating element ( 50 ), in particular a heating cartridge, which accommodation mandrel ( 40 ) is mountable in a non-rotating manner and which extends into the hollow space of the shaft ( 30 ), wherein an outer surface ( 41 ) of the accommodation mandrel ( 40 ) is spaced apart from an inner surface ( 31 ) of the shaft ( 30 ) by a gap ( 39 ). 
     32. The drive unit according to aspect  31 , further comprising a thermocouple element for controlling a temperature of the heating arrangement ( 40 ,  50 ) in a closed loop mode. 
     33. The drive unit according to aspect  30  or aspect  32 , wherein the shaft ( 30 ) is configured to be dividable, wherein dividable connections of the shaft ( 30 ) are provided with a seal ( 37 ,  38 ) to seal a volume defined between the accommodation mandrel ( 40 ) and the inner surface ( 31 ) of the shaft ( 30 ) against a treatment space ( 15 ). 
     34. The drive unit according to aspects  31  to  33 , further comprising a heating cartridge ( 50 ), which is or can be arranged in a further cylindrical hollow space of the accommodation mandrel ( 40 ). 
     35. The drive unit according to aspect  34 , wherein a configuration of the heating cartridge ( 50 ) is adapted to a position of a seal ( 16 ,  17 ,  37 ,  38 ) or a bearing ( 14 ,  60 ), wherein in particular the heating cartridge ( 50 ) is configured such that an area ( 51 ) of the heating cartridge ( 50 ) containing active heating elements ends at a distance from the seal ( 16 ,  17 ,  37 ,  38 ) or the bearing ( 14 ,  60 ). 
     36. The drive unit according to any one of aspects  31  to  35 , wherein the electrical heating element ( 50 ) is an integral component of the accommodation mandrel ( 40 ), preferably cast with it. 
     37. The drive unit according to any one of aspects  31  to  36 , wherein the accommodation mandrel ( 40 ) can be removed from the hollow space of the shaft ( 30 ) to replace the electrical heating element ( 50 ). 
     38. The drive unit according to aspect  37 , wherein the accommodation mandrel is supported at its distal end in the hollow space of the shaft ( 30 ) and comprises a taper at its distal end to be inserted into the bearing ( 60 ). 
     39. The drive unit according to any one of aspects  31  to  38 , which is configured to be used in the treatment machine ( 10 ) according to any one of aspects  1  to  30 . 
     40. Use of the treatment machine ( 10 ) according to any one of aspects  1  to  30  or the drive unit ( 20   a - 20   c ) according to any one of aspects  31  to  39  for coating substrates ( 18 ). 
     41. Use of the treatment machine ( 10 ) according to any one of aspects  1  to  30  or the drive unit ( 20   a - 20   c ) according to any one of aspects  31  to  39  for a thermal treatment of substrates ( 18 ). 
    
    
     
       SHORT DESCRIPTION OF THE FIGURES 
       Preferred embodiments of the invention are described in detail below with reference to the Figures, in which identical reference signs denote identical or similar elements. 
         FIG. 1  shows a side view of a treatment machine according to a preferred embodiment. 
         FIG. 2  shows a sectional view through the treatment machine in a sectional plane containing a rotation axis of a temperature-controlled shaft. 
         FIG. 3  shows a sectional view through the treatment machine in a sectional plane containing the rotation axis of the temperature-controlled shaft. 
         FIG. 4  shows a sectional view in a sectional plane perpendicular to the rotation axis of the temperature-controlled shaft along the line IV-IV indicated in  FIG. 3 . 
         FIG. 5  shows a sectional view in a sectional plane perpendicular to the rotation axis of the temperature-controlled shaft along the line V-V indicated in  FIG. 3 . 
         FIG. 6  shows a partial sectional view through the treatment machine in the area denoted by A in  FIG. 3  in a sectional plane containing a rotation axis of a temperature-controlled shaft. 
         FIG. 7  shows a partial sectional view through the treatment machine in the area denoted by B in  FIG. 3  in a sectional plane containing a rotation axis of a temperature-controlled shaft. 
         FIG. 8  shows a partial sectional view through the treatment machine in the area denoted by C in  FIG. 3  in a sectional plane containing a rotation axis of a temperature-controlled shaft. 
         FIG. 9  shows a partial sectional view through the treatment machine in the area denoted by D in  FIG. 3  in a sectional plane containing a rotation axis of a temperature-controlled shaft. 
         FIG. 10  shows a dependence of a temperature of the shaft on the distance between an outer surface of an accommodation mandrel and an inner surface of the shaft. 
         FIG. 11  shows a dependence of a temperature of the shaft on the distance between an outer surface of an accommodation mandrel and an inner surface of the shaft. 
         FIG. 12  shows a dependence of a temperature of the shaft on the distance between an outer surface of an accommodation mandrel and an inner surface of the shaft. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     While preferred or advantageous embodiments are described with reference to the Figures, additional or alternative configurations can be realized in further embodiments. 
     While, for example, with reference to the Figures, embodiments are explained in the context of continuous machines in which a temperature-controlled shaft is used to transport substrates or substrate carriers, the embodiments are not limited thereto. While embodiments are described in the context of treatment machines for vapor phase deposition or thermal treatment, the disclosed embodiments can also be used for other purposes. 
       FIG. 1  shows a side view of a treatment machine  10  according to the invention. The treatment machine  10  comprises a chamber  11 , which defines a treatment space  15  in its interior. The treatment machine  10  may be configured as a continuous machine or as a batch-type machine. A plurality of drive units  20   a ,  20   b ,  20   c  may be mounted at the chamber  11  to move substrates or a substrate carrier along a transport direction  19 . 
     Alternatively or additionally, drive units comprising a temperature-controlled shaft according to the invention may also be provided for other purposes, for example, for rotating substrates. 
     Each of the drive units  20   a ,  20   b ,  20   c  may comprise a shaft  30  rotatably supported relative to chamber  11 , an accommodation mandrel  40  and an electrical heating device  50  accommodated in the accommodation mandrel  40 . The accommodation mandrel  40  and the electrical heating device  50  may form an electrical heating arrangement. 
     The accommodation mandrel  40  is mounted in a non-rotating manner so that it does not rotate relative to the chamber  11  even when the shaft  30  is rotating. The accommodation mandrel  40  extends into the shaft  30  such that the shaft  30  is rotatable around the accommodation mandrel  40  without any contact. 
       FIG. 2  shows a sectional view through an exemplary drive unit  20  in a sectional plane containing a rotation axis of the shaft  30 . The shaft  30  may be rotatably supported at opposite side walls  12 ,  13  by bearings  14 . One or more bearings (not shown in  FIG. 2 ) may be provided between the accommodation mandrel  40  and the shaft  30 . 
     The treatment machine  10  may be configured such that the treatment space  15  can be evacuated to a static pressure of less than 1 Pa, in particular less than 0.1 Pa, in particular less than 10 −2  Pa, in particular less than 10 −3  Pa and in particular less than 10 −4  Pa. For that purpose, appropriate pumps and optionally controllable valve arrangements may be provided. The treatment machine may comprise vacuum locks (not shown) for inserting substrates into the treatment space  15  therethrough and/or removing substrates from the treatment space  15  therethrough. 
     The shaft  30  is configured such that a hollow space defined in the interior of the shaft  30  is sealed in a gas-tight manner against the treatment space  15 . If the shaft  30  is configured as a multi-part shaft, the shaft may comprise seals between different parts of the shaft  30  to seal the inner volume of the shaft  30  against the treatment space  15 . 
     During the operation of the treatment machine  10 , an overpressure may prevail in the inner volume of the shaft  30  in comparison to the pressure in the treatment space  15 . This allows good thermal conductivity to be achieved by heat transfer between the accommodation mandrel  40  and the shaft  30  via a gas or gas mixture present in the inner volume of the shaft  30 . 
     The accommodation mandrel  40  may be configured to have an outer diameter and/or a wall thickness that ensures a relatively high bending stiffness even when used in a long shaft  30  having a length of more than 600 mm. The outer surface of the accommodation mandrel  40  may have a diameter of at least 15 mm, in particular at least 20 mm, in particular at least 22 mm. The accommodation mandrel  40  may have a maximum wall thickness of at least 2 mm, at least 3 mm or at least 4.5 mm. 
     An electrical heating device  50  may be insertable into the accommodation mandrel  40 . The electrical heating device  50  may be configured in one piece so that it is easily insertable into and removable from the accommodation mandrel  40 . The electrical heating device  50  may be a conventional heating cartridge comprising a housing and one or more active heating elements arranged in the housing of the heating cartridge. 
     The electrical heating device  50  and the accommodation mandrel  40  are configured such that the electrical heating device  50  is separated from an inner surface of the accommodation mandrel  40  by a relatively small gap when inserted into the accommodation mandrel  40 . An outer surface of the heating cartridge  50  arranged in the accommodation mandrel may be spaced apart from an inner surface of the accommodation mandrel  40  by at most 1 mm, by at most 0.5 mm or by at most 0.25 mm. In the case of the above-discussed variant comprising a cast heating element, this distance may also be greater since in this case the greater distance can be compensated for by means of a material having a higher thermal conductivity. 
     In order to ensure good heat transfer from the electrical heating device  50  to the accommodation mandrel  40 , a medium, in particular a gaseous medium, may be provided in the interior of the accommodation mandrel  40  between the accommodation mandrel  40  and the electrical heating device  50 . The medium provided in the interior of the accommodation mandrel  40  may comprise a thermal conductivity λ of at least 0.05 W/(K·m)) or at least 0.1 W/(K·m). As already mentioned above, in the case of the above-discussed variant comprising a cast heating element, the material provided between the heating cartridge and the accommodation mandrel may have a thermal conductivity of at least 4 W/(K·m), more preferably of at least 6 W/(K·m) and particularly preferably of at least 8 W/(K·m). 
     Due to the fact that the accommodation mandrel  40  and the electrical heating device  50  do not rotate, it becomes possible to separate these two components by only a small gap so that a good heat transfer can be achieved. Therefore, the electrical heating device  50  can be easily replaced. This is particularly the case when the electrical heating device  50  is not attached to any functional element such as, for example, support bearings. Thus, the electrical heating device  50  may have a relatively small diameter. Any deflection of the electrical heating device  50  is limited by the accommodation mandrel. The electrical heating device  50  can be reversibly removed in a non-destructive manner through a small opening diameter on the drive side of the rotary transmission feedthrough. 
     Due to its larger diameter, the accommodation mandrel  40  has a higher bending stiffness and thus ensures low deflection even in the case of a long shaft  30 . Therefore, a gap relative to the rotating shaft  30  can be kept relatively consistent both over the circumference of the accommodation mandrel  40  and along the longitudinal direction of the shaft  30 , i.e. with only small deviations over the circumference and the longitudinal direction of the shaft  30 . Again, this allows the gap between the rotating shaft  30  and the accommodation mandrel  40  to be set relatively small. 
     For example, the gap between the outer surface of the accommodation mandrel  40  and the inner surface of the shaft  30  may be less than 4 mm, less than 3 mm, less than 2.2 mm or less than 1.9 mm. 
     The gap between the outer surface of the accommodation mandrel  40  and the inner surface of the shaft  30  may be greater than 0.3 mm, greater than 0.5 mm, greater than 0.7 mm or greater than 1 mm to eliminate or reduce the risk of contact between the accommodation mandrel  40  and the shaft  30  during operation. 
     The gap between the rotating shaft  30  and the accommodation mandrel  40  is larger than the distance between the heating device  50  and the accommodation mandrel  40 . 
     A good heat transfer of thermal energy from the accommodation mandrel  40  to the shaft  30  can be achieved by using a gap between the outer surface of the accommodation mandrel  40  and the inner surface of the shaft  30  that is, for example, larger than 0.3 mm and smaller than 4 mm. 
     A thermal conductivity per axial length of shaft  30  can be defined as 
       Q/t/|T 1 −T 2 |,  (1)
 
     wherein Q denotes a thermal energy transferred in a time t per unit of length of the shaft  30  and |T 1 −T 2 | denotes an absolute value of a temperature difference between an inner surface of the shaft  30  and an outer surface of the accommodation mandrel  40 . 
     The thermal conductivity between the outer surface of the accommodation mandrel  40  and the inner surface of the shaft  30  per unit of axial length of the outer surface of the accommodation mandrel  40  may be at least 0.4 W/(K·m), at least 0.5 W/(K·m), at least 0.6 W/(K·m), at least 0.8 W/(K·m) or at least 0.9 W/(K·m). 
     The thermal conductivity between the outer surface of the accommodation mandrel  40  and the inner surface of the shaft  30  per unit axial length of the outer surface of the accommodation mandrel  40  may be maximally 9 W/(K·m), maximally 8 W/(K·m), maximally 7 W/(K·m), maximally 6 W/(K·m) or maximally 4 W/(K·m). 
     A relatively large outer diameter of the accommodation mandrel  40  of at least 15 mm or at least 20 mm offers a larger surface area for better energy transfer to the shaft  40 . 
     The material of the accommodation mandrel  40  may be selected such that it exhibits good heat conduction so that there is no noteworthy temperature difference between the inner and the outer surface of the accommodation mandrel  40  during operation. The accommodation mandrel  40  may contain, for example, structural steel or consist of structural steel. 
     Preferably, the accommodation mandrel is black-oxide finished to blacken the surface. 
     The accommodation mandrel  40  is configured as a purely passive component. Since the accommodation mandrel  40  does not exhibit any wear during operation, it is not subject to any replacement interval. Therefore, the accommodation mandrel  40  can be mounted in the treatment machine without the need that the accommodation mandrel  40  has to be replaceable from the outside. This allows, for example, to select an outer diameter of the accommodation mandrel  40  being larger than an inner diameter of a bearing for the shaft  30 . 
       FIG. 3  shows a sectional view through a treatment machine with a chamber  11  and a drive unit, which comprises a rotatably supported shaft  30  and an electrical heating arrangement. The electrical heating arrangement comprises an accommodation mandrel  40 , in which an electrical heating device  50  can be reversibly detachably mounted. The accommodation mandrel  40  forms a component of the electrical heating arrangement, wherein a heating cartridge or other electrical heating element  50  is insertable into the accommodation mandrel  40  such that it is again removable from the accommodation mandrel  40 . 
     The shaft  30  may be configured as a transport roller. Contact surfaces on the shaft  30  may be used to laterally guide and/or support a substrate  18  or a substrate carrier  18 . The shaft  30  is not limited to such a configuration. For example, the shaft  30  may also rotate a holder for a substrate while a substrate is treated. The shaft  30  does not have to extend in a horizontal direction through the chamber  11 , but may also extend, for example, in a vertical direction into or through the chamber  11 . 
       FIG. 4  shows a sectional view in a sectional plane perpendicular to the rotation axis of the shaft  30  at the position indicated by IV-IV in  FIG. 3 . 
     The shaft  30 , which is rotatably supported relative to the chamber  11 , comprises an inner surface  31 . The inner surface  31  may be blackened for better heat transfer. 
     The accommodation mandrel  40 , which is not rotatable relative to the chamber  11 , comprises an outer surface  41 . The outer surface  41  may be blackened for better heat transfer. 
     As schematically shown in  FIG. 4 , the accommodation mandrel  40  may have a relatively large ratio of its wall thickness to its outer diameter. For example, at least in a central plane of the accommodation mandrel  40  perpendicular to the longitudinal axis of the accommodation mandrel  40 , a ratio of the wall thickness of the accommodation mandrel  40  to the outer diameter of the accommodation mandrel  40  may be at least 0.1, at least 0.15 or at least 0.2. 
     The outer surface  41  of the accommodation mandrel  40  is spaced apart from the inner surface  31  of the shaft  30  by a gap  39 . By a further gap  49 , an inner surface of the accommodation mandrel  40  may be spaced apart from an outer surface of the electrical heating device  50 , for example the heating cartridge, which is inserted into the accommodation mandrel  40  during operation. 
     The gap  39  between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30  may be from 0.3 mm to 4 mm, from 0.5 mm to 3 mm, from 0.7 mm to 2.2 mm or from 1 mm to 1.9 mm. 
     The further gap  49  between the outer surface of the heating cartridge  50  and the inner surface of the accommodation mandrel  40  may be at most 1 mm, at most 0.5 mm or at most 0.25 mm. 
     The shaft  30  and/or the accommodation mandrel  40  may have a varying cross-section along a longitudinal direction of the shaft  30  and the accommodation mandrel  40 . For example, a wall thickness and/or an outer diameter of the accommodation mandrel  40  may vary along the longitudinal direction of the accommodation mandrel  40 . The wall thickness and/or the outer diameter of the accommodation mandrel  40  may decrease in a direction from a center of the accommodation mandrel  40  towards one of the chamber walls  12 ,  13  or towards both chamber walls  12 ,  13 . Thereby, it is possible to take account of the fact that good heat transfer between the accommodation mandrel  40  and the shaft  30  is typically not required in the end areas of the accommodation mandrel  40 . Alternatively or additionally, available space may be created between the accommodation mandrel  40  and the shaft  30 , for example, for mounting a further bearing  60  (also shown in  FIG. 9 ). 
       FIG. 5  shows a sectional view in a sectional plane perpendicular to the rotation axis of the shaft  30  at the position indicated by V-V in  FIG. 3 , wherein the sectional plane extends through the further bearing  60  between the accommodation mandrel  40  and the shaft  30 . As can be seen in both  FIG. 5  and  FIG. 9 , the wall thickness and/or outer diameter of the accommodation mandrel  40  may decrease from a central plane of the treatment machine located between the side walls  12 ,  13  towards one or both side walls  12 ,  13 . 
     Optional additional configuration features of the treatment machine and drive unit are described with reference to  FIGS. 6, 7, 8 and 9 . It is understood that the described features do not have to be cumulatively present, but that the described features can be used in any combinations. 
       FIGS. 6, 7, 8 and 9  show details of the portions of the treatment machine denoted by the letters A, B, C and D in  FIG. 3 . 
       FIG. 6  shows a partial view of a treatment machine according to a preferred embodiment. An electrical heating arrangement comprises the accommodation mandrel  40 , which is mounted at a wall  12  of the chamber  11  such that it does not rotate relative to said chamber. The electrical heating arrangement may comprise a heating cartridge  50  or any other electrical heating device which is inserted into the accommodation mandrel  40  during operation. The rotatably supported shaft  30  is rotatably supported at the chamber  11  via a bearing  14 . 
     A mounting arrangement  70  may be provided to fix the accommodation mandrel  40  in a non-rotating manner to the chamber  11  and to rotatably support the shaft  30 . The mounting arrangement  70  may be configured as a multi-part arrangement with a plurality of components  71 ,  72 ,  73 ,  74 ,  75  and  76 . For example, one or more fixing components  72  of the mounting arrangement  70  projecting outwards from the chamber wall  12  may support one end of the accommodation mandrel  40  such that a longitudinal axis of the accommodation mandrel  40  coincides with a rotation axis of the shaft  30 . 
     A static guide (not shown in  FIG. 6 ) may be used to support the accommodation mandrel  40 , said static guide fixing the accommodation mandrel in relation to the fixing component  72 . This guide may be attached to the fixing component  72  or be configured to be integral with the fixing component  72 . It can thus be ensured that the longitudinal axis of the accommodation mandrel  40  coincides with the rotation axis of the shaft  30 . 
     The mounting arrangement  70  may comprise one or more components that secure the accommodation mandrel  40  against rotation. In order to secure the accommodation mandrel  40  against rotation, for example, the fixing components  71  and  72  may be connected to each other by means of a pin  76 . The fixing component  71  may be separably connected to the accommodation mandrel  40 . 
     A bearing component  73  of the mounting arrangement  70  may be connected to an outer ring of the bearing  14 . Sealing components  74  may be provided to securely seal the treatment space  15  of the chamber  11 , wherein said sealing components may comprise one seal  16  or a plurality of seals and hold them in position. The hollow cylinder  75  is used to shadow the vapor jet so that no deposits are formed on the seal  16 . 
     As shown in  FIG. 3 ,  FIG. 7  and  FIG. 9 , the shaft  30  may be configured as a multi-part shaft. The shaft  30  may comprise a plurality of shaft portions  32 ,  33 ,  34 . The shaft portions  32  and  33  may be connected to each other in a gas-tight manner by means of connectors  35 . The shaft portions  33  and  34  may be connected to each other in a gas-tight manner by means of further connectors  36 . Seals  37 ,  38  may be provided at the connection sites to seal the inner volume of the shaft  30  in a gas-tight manner against the treatment space  15 . 
     The heating cartridge  50  or any other electrical heating device  50  comprises an area  51  that contains all active heating elements of the electrical heating device. The heating cartridge  50  or other electrical heating device  50  may be configured such that there are no active heating elements outside the area  51 . Ends  52 ,  53  of the area  51  containing the active heating elements (most clearly visible in  FIG. 7  and  FIG. 9 ) are positioned such that the ends  52 ,  53  of the area  51  are spaced apart from the seals and/or bearings  14 ,  60  in the longitudinal direction of the shaft  30 . The seals and/or bearings  14 ,  60  are positioned such that they do not overlap with the area  51  containing all active heating elements when viewed in the axial direction of the shaft  30 . 
       FIG. 8  shows a central area along the longitudinal direction of the shaft  30 . As already explained with reference to  FIG. 4 , the inner surface  31  of the shaft  30  in the central area is spaced apart from the outer surface  41  of the accommodation mandrel  40  by a gap  39 , which is larger than a gap between the heating cartridge  50  or any other electrical heating device  50  and the inner surface of the accommodation mandrel  40 . 
     The shaft  30  may be configured as a drive roller. The shaft  30  may be used in a continuous machine or a batch-type machine. Guide elements  81  for laterally guiding the substrate  18  or the substrate carrier  18  may be arranged at the shaft  30 . Support elements  82  for supporting a lower side of the substrate  18  or the substrate carrier  18  may be arranged at the shaft  30 . The guide elements  81  and/or support elements  82  may be circumferentially arranged around the shaft  30 . 
       FIG. 9  shows a partial view of a treatment machine according to a preferred embodiment. The rotatably supported shaft  30  is rotatably supported at the chamber  11  via a bearing  14 . A further bearing  60  may be arranged between the accommodation mandrel  40  and the shaft  30 . Active heating elements are arranged in the heating cartridge  50  or the other heating device  50  such that they do not extend beyond an end  53  of an area  51  which ends at a distance from bearing  60 . 
     Seals  17  may be provided to ensure that treatment space  15  in the chamber  11  can be evacuated to a static pressure of less than 1 Pa, in particular less than 0.1 Pa, less than 10 −2  Pa, less than 10 −3  Pa or less than 10 −4  Pa. 
     Each of  FIG. 10 ,  FIG. 11  and  FIG. 12  shows a temperature of the outer surface of the accommodation mandrel  40  (open circles and broken lines) as well as a temperature of the outer surface of the shaft  30  (filled circles and solid lines) as a function of a distance g (which corresponds to the distance  39  shown in  FIG. 4  and  FIG. 8 ) between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30 . As regards the data shown in  FIG. 10 ,  FIG. 11  and  FIG. 12 , the shaft  30  has an outer radius of 23 mm and an inner radius of 12.5 mm. The accommodation mandrel  40  has an inner radius of 6.25 mm. The wall thickness of the accommodation mandrel  40  varies between 5.5 mm and 3 mm so that the distance g between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30  varies from 0.75 mm to 3.25 mm. 
     In  FIG. 10 , the temperature of the heating cartridge is 200° C., and the gap between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30  is filled with air. 
     In  FIG. 11  the temperature of the heating cartridge is 300° C., and the gap between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30  is filled with air. 
     In  FIG. 12 , the temperature of the heating cartridge is 300° C., and the gap between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30  is filled with helium. 
     As illustrated by  FIG. 10 ,  FIG. 11  and  FIG. 12 , the heat transfer to the shaft  30  can be improved and the shaft  30  can be heated to a higher temperature when using a smaller gap between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30  (i.e., when using a larger outer diameter d of the accommodation mandrel  40 ). 
     As revealed by a comparison between  FIG. 11  and  FIG. 12 , the heat transfer to the shaft  30  can be improved and the shaft  30  can be heated to a higher temperature by using helium as a gas in the gap between the outer surface  41  of the accommodation mandrel  40  and the inner surface  31  of the shaft  30  than by using air in the inner volume of the shaft  30 . 
     A plurality of drive units having the configuration described in detail with reference to  FIG. 2  to  FIG. 12  may be provided at a single treatment machine. 
     The treatment machine and/or drive unit may be used for different purposes. For example, the treatment machine may be configured as a vapor deposition machine. The treatment machine may be configured to deposit chalcogens, for example selenium. To this end, the treatment machine may comprise at least one vapor source for a reaction vapor. Alternatively or additionally, the treatment machine may be configured for gas phase deposition and comprise at least one source of reaction gas. Alternatively or additionally, the treatment machine or the drive unit may be used for a thermal treatment of substrates/layers deposited onto the substrates. 
     The heating cartridge  50  or any other heating device  50  may be controlled in an open loop or in a closed loop mode via a thermocouple element or a plurality of thermocouple elements. 
     The accommodation mandrel  40  may be configured in different ways depending on the desired application. The accommodation mandrel  40  is advantageously configured such that a ratio of its wall thickness to its outer diameter in a central plane of the chamber may be, for example, at least 0.1, at least 0.15 or at least 0.2. The accommodation mandrel  40  advantageously contains structural steel or consists of structural steel. 
     In an exemplary embodiment, the static accommodation mandrel  40 , which does not rotate along with the shaft  30 , may be configured to accommodate a standard electrical heating cartridge. The heating cartridge may transfer heat energy to the accommodation mandrel  40  via a small gap, which, for example, may be maximally 0.5 mm or maximally 0.25 mm. Thus, it is ensured that the heating cartridge can efficiently transfer its heat energy and does not overheat. Negative influences on the lifetime of the heating cartridge  50  can be prevented. 
     Due to the relatively large wall thickness of the accommodation mandrel  40 , the accommodation mandrel  40  can efficiently absorb heat energy and then transfer it to the rotatably supported shaft. The wall thickness of the accommodation mandrel may be, for example, at least 2 mm, at least 3 mm, at least 4 mm or approximately 4.5 mm in a central plane of the chamber  11 . Such a configuration is particularly suitable for shaft lengths of more than 600 mm, without being limited thereto. 
     The drive unit and treatment machine according to various embodiments allow a temperature control of a shaft  30  rotating during operation, in particular a heating of the shaft  30  rotating during operation. The problems with leakages at rotary transmission feedthroughs, which often occur in the case of shafts with temperature control by means of oil, can be avoided. Due to the use of an accommodation mandrel  40  into which a heating cartridge  50  or any other electrical heating device  50  can be inserted as a replacement part, it is not necessary to contact the heating cartridge  50  via a slip ring contact. Due to the configuration of the accommodation mandrel  40  as a passive component, a simple design can be implemented. Efficient heat transfer to the shaft  30  can be achieved by a gas in the gap between the accommodation mandrel  40  and the shaft  30 . 
     Embodiments of the invention may be advantageously used for machines for vapor phase deposition, gas phase deposition and/or thermal treatment of substrates, without being limited thereto. Embodiments of the invention may be advantageously used in continuous machines or batch-type machines.