The present invention relates to an apparatus for blocking and unblocking a loading/unloading opening of at least one process chamber for treatment of substrates, particularly for treatment of semiconductor substrates.

In the semiconductor and photovoltaic industry, it is known to treat substrates, particularly semiconductor substrates, in different process chambers. Such process chambers each have at least one loading/unloading opening, which is usually closable by a door element. This is necessary, in order to isolate the process chamber from the surrounding environment, and particularly in order to seal the process chamber in a gas-tight manner. This is particularly necessary for vacuum processes in a process chamber, however, may also be advantageous for other processes. Such door elements are usually pivotably fixed to the process chamber such that the door elements are movable from an open (unblocked) position to a closed (blocked) position. In the open position, the door elements unblock the loading/unloading opening for loading and unloading substrates into the process chamber or from the process chamber. In the closed position, the door elements block the loading/unloading opening. Usually, sealing elements are provided at the process chamber casing and/or at the door element, in order to seal the process chamber in the closed position. However, a sufficient pivot space is required for such pivotable door elements, which may lead to space problems. Furthermore, also the construction for the pivot mechanism is quite expensive, since very low tolerances need to be provided for the pivoting movement, in order to provide for gas-tight sealing of the loading/unloading opening. Such door elements may also cause problems in adjacent process chambers, where the process chambers comprise loading/unloading openings facing each other, a substrate is to be moved directly between these process chambers, and the substrate is not to be exposed to the environment. Pivotally moved door elements are usually not adapted for such arrangements. Thus, the problem to be solved by the present invention is to provide an apparatus for blocking and unblocking a loading/unloading opening of at least one process chamber, which allows for simple and economical gas-tight sealing of the process chamber while requiring little space.

According to the invention, this problem is solved by an apparatus according to claim 1. The dependent claims are directed to further embodiments of the invention.

In particular, an apparatus for blocking and unblocking a loading/unloading opening of at least one process chamber for treating substrates is provided, the apparatus comprising at least one tube element and a casing having a chamber axially extending in the casing for housing the tube element, and a passage intersecting the chamber laterally to the axial direction, wherein the passage is aligned with the loading/unloading opening of the process chamber and wherein the chamber has a circular cross-sectional area. Furthermore, at least one fixing unit for positioning and holding a section of the tube element in a predetermined position with respect to the loading/unloading opening of the process chamber is provided. The tube element comprises at least one inlet and/or outlet opening connectable to a fluid source and/or a vacuum source, and the tube element is movable via applying a fluid and/or a vacuum to the inner space selectively between a deployed condition and a retracted condition, in which the tube element is retracted towards the fixed section, wherein the tube element blocks the loading/unloading opening of the process chamber in the deployed condition and unblocks the loading/unloading opening of the process chamber in the retracted condition. Such an apparatus has a simple construction and may provide for securely blocking and unblocking the process chamber. The casing allows for locating the tube in a well defined manner with respect to the loading/unloading opening and comprises a defined abutment area for the tube in a deployed condition, resulting in good sealing characteristics. The circular cross-sectional area of the chamber may be produced in an easy and economical manner even over greater lengths, and is particularly well-adapted to usually round tubes.

Preferably, the tube element has a diameter, which is at least twice as large as a height of the loading/unloading opening of the process chamber to be loaded in a deployed or inflated condition, in order to provide for reliable blocking and unblocking of the loading/unloading opening.

In one embodiment of the invention, the chamber is sized in such a way that the tube element contacts walls of the chamber in a radial direction in the deployed condition of the tube element, such that the tube element seals the passage through the casing and thus the loading/unloading opening of the process chamber, and such that the tube element unblocks the passage in its retracted condition.

In one embodiment of the invention, the fixing unit comprises a pole or rod element that extends in the inner space of the tube element adjacent to the fixed section of the tube element, wherein the rod element may prevent a movement of the section towards the center of the tube. Particularly, the tube element may press the section of the tube element to be fixed against a support in a radial direction, particularly to the casing mentioned above.

The rod element may comprise an axially extending chamber, which comprises a first opening connectable to a fluid source and/or a vacuum source, as well as at least one passage extending from the chamber to the outside of the rod element. In this case, the rod element may provide a distribution function for distributing a fluid and/or a vacuum in the tube besides the holding function.

In one embodiment, the fixing unit comprises an element located outside the tube element. The section of the tube element to be fixed may be fixed to this element, in particular by gluing or vulcanizing.

In order to provide for secure fixing of the tube element and possibly also sealing thereof with respect to the environment also in the open position, at least one support sleeve may be provided in an end region of the tube element, wherein the support sleeve maintains the end region in a predetermined shape, regardless of whether the tube element is in the deployed condition or in the retracted condition. Preferably, the support sleeve pushes the tube element against a support in a radial direction, particularly against a seal in the above-mentioned casing. In one embodiment, at least one biasing element for biasing the tube element towards the retracted position or condition is provided. Such a biasing element allows for controlling the condition of the tube element only by positive pressure in the inner space of the tube element. Particularly, also in a retracted condition of the tube, a fluid may flow through the tube, in order to cool the tube or in order to provide a predetermined temperature for the tube. In a simple construction, the biasing element may be an elastic strap located in the inner space of the tube element, wherein the strap may be particularly formed as an integrated part of the tube element.

In an alternative embodiment, at least two tube elements are provided in such a way that a first tube element at least partially surrounds the second tube element, wherein the first tube element comprises at least one opening for applying a vacuum to the inner space thereof, and wherein the second tube element comprises at least one opening for applying a pressurized fluid to the inner space thereof. In such an arrangement, the inner tube element may be retracted by applying a vacuum to the outer tube element, as far as the pressure in the inner tube element is not too high. Particularly, this also allows for a fluid flow in the inner tube element in the retracted condition as well.

Preferably, the tube element comprises an opening at the opposing ends thereof, in order to allow for directing a fluid through the tube element. Furthermore, such a tube element has a simple construction compared to a tube element closed at one end.

The apparatus for treating substrates comprises at least one process chamber for receiving said substrate, at least one loading/unloading opening for the substrate, the loading/unloading opening being formed in one wall of the process chamber, and at least one closing apparatus of the above-mentioned type for opening and closing the at least one loading/unloading opening. Preferably, the apparatus comprises two process chambers, each of the process chambers comprising at least one

loading/unloading opening facing the other process chamber, wherein the

loading/unloading openings of the process chambers are facing each other and are aligned with each other, in order to allow transporting of the substrates between the process chambers. The closing apparatus may be arranged between facing loading/unloading openings in such a way that the closing apparatus blocks and seals both loading/unloading openings in a deployed condition, and thus isolates the process chambers, and the closing apparatus unblocks a connection between the process chambers in a retracted condition.

Unblocking of the loading/unloading opening, as is used above, means that the tube element opens the loading/unloading opening so far that loading/unloading a substrate through the opening is possible. Preferably, unblocking means that the tube element is located completely outside a projection of the opening.

The invention will be explained in more detail in the following, referring to the figures. In the figures:

Fig. 1 shows a schematic sectional view of an apparatus for treating substrates having a closing apparatus according to the invention in a closed condition;

Fig. 2 shows a schematic sectional view as shown in Fig. 1 , wherein the closing apparatus is in an open condition;

Fig. 3 is a schematic sectional view of an apparatus for treating substrates

according to an alternative embodiment, having a closing apparatus according to the invention in a closed position;

Fig. 4 is a schematic sectional view similar to Fig. 3, wherein the closing

apparatus is in an open position;

Fig. 5 shows a perspective view of a closing apparatus, according to the present invention;

Fig. 6 is a longitudinal sectional view of a closing apparatus according to Fig. 5, wherein the closing apparatus is shown in an open condition;

Fig. 7 is a sectional view similar to Fig. 6, wherein the closing apparatus is

shown in a closed condition;

Fig. 8 is an enlarged partial view of the closing apparatus according to Fig. 6, in an open condition;

Fig. 9 is a perspective sectional view of the closing apparatus according to Fig.

5, in a closed condition;

Fig. 10 is a sectional view of the closing apparatus according to Fig. 5, in an open condition; Fig. 11 is an enlarged perspective partial sectional view of an alternative closing apparatus, in a closed condition;

Fig. 12 is an enlarged perspective partial sectional view of the apparatus

according to Fig. 11 , in an open condition.

Positions and/or orientations, as mentioned in the following specification, relate to the views in the figures and shall not be regarded as limiting the application. However, these positions and/or directions may relate to preferred embodiments.

Figures 1 and 2 show a schematic sectional view of an apparatus 1 for treating substrates, particularly for treating semiconductor substrates.

The apparatus 1 generally consists of a process chamber 3 and a closing apparatus 6.

The process chamber 3 has a casing 8, wherein the inner space of the casing defines a process chamber 0. A loading/unloading opening 12 is formed in a lateral wall of the casing 8, the loading/unloading opening being sized for transferring substrates. In the process chamber, a substrate holder 14 for holding and supporting a substrate (not shown) is located. The substrate holder 14 may be rotatably supported in the process chamber 10 by a rotational shaft 16, as is shown in Figures 1 and 2. Such process chambers 3 are well known in the art and may comprise various treatment units for treating the substrates, such as heating units, plasma units, gas feeding units, and/or gas exhaust units for obtaining defined gas

environments in the process chamber and so on. The process chamber 3 may also have a construction differing from the shown construction, as long as a

loading/unloading opening is provided.

The closing apparatus 6 will be explained in the following in more detail, particularly referring to Figures 5-12. The closing apparatus 6 has a casing 20, wherein a passage 22 laterally extends through the casing 20 corresponding to the

loading/unloading opening 12 of the process chamber 3. The casing 20 is connected to the process chamber 3 in a sealed manner and in such a way that the passage 22 is aligned with the loading/unloading opening 12 of the process chamber 3. Thus, loading/unloading of substrates into and out of the process chamber 3 is carried out through the passage 22 of the closing apparatus 6 and the loading/unloading opening 12 of the process chamber 3.

Figures 3 and 4 show an alternative construction of an apparatus for treating substrates, which comprises two substrate chambers 3 in the shown embodiment, the two process chambers generally having the same construction, as was described above. The two process chambers 3 are adjacently arranged such that a

loading/unloading opening 12 of the first process chamber 3 faces the

loading/unloading opening 12 of the second process chamber 3. The closing apparatus 6 and the casing 20 thereof are arranged between the two process chambers 3 such that the casing 20 is mounted in a sealed manner between both process chambers 3. In this arrangement, the passage 22 is arranged such that the passage connects the loading/unloading openings 12 of both process chambers 3. By this means, a direct transport of substrates from one process chamber to the other process chamber is facilitated, as long as the closing apparatus 6 is in an open condition, as is shown in Figure 4.

At least one of the process chambers 3, particularly the right process chamber 3, as shown in Figures 3 and 4, comprises at least one additional loading/unloading opening 12, which may be opened (unblocked) and closed (blocked) via another closing apparatus 6.

The closing apparatus 6 will be described in more detail in the following, also referring to Figures 5-12. Of these figures, Figures 5-10 show the closing apparatus 6, located between two process chambers 3, wherein only a small portion of the process chambers is indicated. It should be noted that the closing apparatus 6 may also be arranged adjacent to a single process chamber 3, as is shown in Figures 1 and 2. In Figures 11 and 12, showing alternative embodiment of the closing apparatus 6, the process chambers were omitted from the figures.

Fig. 5 shows a perspective view of the closing apparatus 6. Figures 6 and 7 show schematic longitudinal sectional views of the closing apparatus 6, wherein Fig. 6 shows an open condition of the closing apparatus 6, and wherein Fig. 7 shows a closed condition. Figure 8 is an enlarged partial view of an end portion of the closing apparatus 6 in an open condition, and Figures 9 and 10 are sectional views of the closing apparatus 6, wherein Figure 9 shows a closed condition and Figure 10 shows an open condition.

The closing apparatus 6 comprises the casing 20 mentioned above, wherein the casing is formed of a rectangular main body 24, as well as end covers 26. In the main body 24, the laterally extending passage 22 mentioned above, as well as an axially extending passage 27, are formed.

The laterally extending passage 22 is generally shaped and sized in accordance with the loading/unloading openings of the process chambers 3 and thus is adapted for transferring substrates for loading and unloading the process chamber. The passage 22 intersects the passage 27 such that substrates also pass a part of the passage 27 when transported through the passage 22. The passage 22 intersects the passage 27 above the center but below the highest point of the passage 22, as may be best seen in Figures 9 and 10.

The axially extending passage 27 has a circular sectional area, which is interrupted in the region of the passage 22, as is obvious.

The rectangular main body 24 is appropriately mounted in a sealed manner between two process chambers 3 or at one end of one process chamber 3, such that the passage 22 is aligned with a corresponding loading/unloading opening 12 of the process chamber 3.

The end covers 26 are detachably mounted to axially opposing ends of the main body 24, e.g. by bolts. In this context, detachably mounting means all types of mountings which allow non-destructive detaching of the end covers from the main body 24. The end covers are identically constructed and only one end cover is described in the following.

The end cover 26 has a rectangular base body 30 as well as a mounting flange 32. The rectangular base body 30 has a circumferential shape corresponding to the circumferential shape of the rectangular main body 24. The base body 30 has a circular recess 34 having generally the same diameter as the passage 27 in the main body 24, and the recess 34 is aligned with the passage 27. The passage 27 in the main body 24 opens into the recess 34. The recess 34 has a step for housing an 0- ring 36 in the free end thereof (facing the main body 24), as may best be seen in Fig. 8. The recess 34 has a circular projection 38 at the bottom.

The mounting flange 32 is generally tube-shaped having a passage 40 extending through the projection 38 to the recess 34. The mounting flange 32 is sized in such a way that the mounting flange 32 is connectable to a fluid source and/or a vacuum source (both not shown), e.g. by connecting to a tube. In case the end covers 26 are connected to the main body 24, the passage 27 is covered at its ends.

The closing apparatus 6 further comprises a closing mechanism 50 housed in the passage 27 of the main body 24 and partially housed in the recess 34 in the end covers 26.

The closing mechanism 50 generally consists of a tube 52, support rings 54, and a fixing element 56.

The tube 52 may be a straight tube made of an appropriate material such as viton, rubber, silicon, or another appropriate material. The material needs to have sufficient flexibility so as to be able to move or deform between a retracted condition, as is shown e.g. in Fig. 6, and a projected or deployed condition, as is shown e.g. in Fig. 7. Furthermore, the material needs to be able to conform to the passage 27 and particularly needs to be able to provide a sealing function for the passage 22.

The tube 52 has a generally circular cross-sectional area corresponding to the passage 27 in the main body 24. In an unloading condition, the tube 52 has an outer circumference which is slightly smaller than the inner circumference of the passage 27 in the main body 24. The tube 52 has a length which is longer than the length of the passage 27, such that the tube may extend completely through the passage 27 and may extend from both sides of the passage 27. However, the length is sized in such a way that the extending part of the tube may be housed in the recesses 34 in the end covers 26, as is shown in Figures 6 and 7.

Each of the support sleeves 54 is ring-shaped. Each of the support sleeves 54 is housed in one respective end portion of the tube 52 and maintains the tube in a predetermined open configuration, as will be explained in more detail in the following. The support sleeves 54 are made of an appropriate material having sufficient stability to maintain the ends of the tube 52 in a predetermined open configuration. The support sleeves 54 are sized in such a way that the support sleeves bias the corresponding end of the tube 52 slightly open and press the ends towards the O- ring 38.

The fixing element 56 comprises an elongated rod element having a length which is longer than the length of the passage 27 in the main body 24. However, the length of the rod element is sized in such a way that, when the closing apparatus 6 is in an assembled condition, the rod element may be received between the end covers 26. The fixing element is arranged in such a way that it extends through the tube 52. The fixing element 56 is rounded on the top surface and the bottom surface thereof, respectively. The rounded shape of the bottom surface generally conforms to the round shape of the passage 27 in the main body 24, and the rounded shape of the top surface generally conforms to the rounded shape of the projection 38 in the recess 34, as is shown in Fig. 8.

The fixing element 56 has a middle region 58 as well as end regions 59. The middle region 58 has a larger thickness than the end regions 59. Particularly, the middle region has a thickness which is larger than the thickness of the end regions 59 by the thickness of the support sleeve 54. Thus, the fixing element 56 is clampable in a predetermined position by the end covers 26, wherein the fixing element forces the tube 52 towards the passage 27 in the main body 24 into said predetermined position, as may best be seen in Fig. 8. By this means, a section of the tube 52, in this case the lower section, is fixed in a defined position. By this means, the tube 52 is prevented from moving away from the passage 27 in this section. One particular effect which may be achieved by this means is that the tube contracts towards the thus fixedly mounted section once e.g. vacuum is applied to the tube 52, as will be explained in more detail in the following.

Replacement/maintenance of the actual closing element, i.e. of the tube, may be carried out in a simple way by detaching at least one of the end covers and by axially removing the tube from the passage 27, wherein the tube may possibly be in a collapsed or retracted condition. On the contrary, the main body 24 may remain in its sealed position, which is particularly advantageous in an arrangement between two process chambers.

Operation of the closing apparatus 6 will be explained in more detail referring to the figures.

The starting point is a situation in which the closing apparatus 6 is in the position shown in Figure 7. A pressurized fluid, such as water, is directed through the tube 52 via the connecting flanges 32. By this means, the tube is slightly extended outwardly and is firmly pressed against the passage 27 in the main body 24. In this situation, the tube 52 completely blocks the laterally extending passage 22 and the tube may even slightly extend into the passage 22, as is obvious for the person skilled in the art. By this means, the passage 22 is blocked in the region of the two sectional areas defined by intersecting the passage 27, and is sealed. Accordingly, the

loading/unloading openings 12 of the process chamber are sealed from the environment at this point in time. In case the passage 22 of the closing apparatus 6 and thus the loading/unloading opening 12 in the process chamber 3 are to be opened, vacuum may be generated in the area of the tube via at least one of the connecting flanges 32. The tube contracts, as is shown in Fig. 6, and unblocks the passage 22 in the main body 24. In this situation, the support sleeves 54 function to hold the end regions of the tube 52 in a defined, sealed position in contact with the O-ring 38. The fixing element 56 causes the tube to contract generally only downwardly towards the section of the tube fixed by the fixing element. Without the fixing element 56, the tube would symmetrically contract towards the center and possibly would not completely unblock the passage 22. Thus, the effect of the fixing element 56 is to increase the lifting distance or moving distance of the tube between a closed position and an open position. In the condition of the tube 52 shown in Fig. 6, a substrate may be transported through the passage 22 and the loading/unloading opening 12 in the process chamber 3. A substrate may be e.g. removed from the process chamber, and a new substrate may be loaded into the process chamber for treatment. Thereafter, the vacuum may be released, wherein the tube 52 will move to a deployed or extended condition after releasing the vacuum. By applying a pressurized fluid, e.g. water, another

appropriate liquid, or an appropriate gas, the tube 52 may be extended or deployed into contact with the passage 27 again.

In the above description, a fixing element 56 in the form of a rod element is provided, the fixing element extending through the tube 52 and forcing the tube against the passage 27 from the inner part thereof. Alternatively, a fixing element might also be provided outside the tube 52, wherein the fixing element is firmly connected to the tube 52 at a section to be fixed, e.g. by gluing or by fitting the fixing element e.g. through loops connected to the tube. Furthermore, the fixing element 56 may be formed as a straight rod, wherein the tube 52 may also slightly lift from the bottom of the passage 27 until the tube contacts the fixing element and is retained by the fixing element, when applying vacuum to the tube.

In the above description, it was mentioned that the tube 52 is either connected to pressurized fluid or to vacuum in order to provide for closed and open positions of the tube 52. It is also possible to provide biasing means which bias the tube 52 to an open position, such as an internal elastic strap which biases the tube 52 towards a retracted condition in the middle region of the tube 52. Also, an external biasing element is conceivable, the external biasing element biasing the tube towards a retracted condition in the middle region. The advantage of such a biasing element is that the tube may also be filled with a fluid even if the tube is retracted, in order to e.g. cool the tube.

Even though the main body 24 is shown having a passage 27 which is covered at each of its ends by an end cover, it should be noted that also a blind bore may be provided in the main body 24. In this case, only one end of the blind bore would be covered by a corresponding end cover. In this case this end cover may comprise two connection flanges in order to provide input and output for a fluid. Thus, it would be possible to provide only one end cover wherein a fluid may be fed into the tube via this end cover or wherein vacuum may be generated in the tube via this end cover. It would be an option to provide a distribution element for distributing a fluid in the tube, wherein the distribution element is connectable to a fluid/vacuum source. To this end, the fixing element 56 may be adapted, wherein such a fixing element could comprise an axially extending chamber or passage, and wherein the chamber or passage could comprise intersecting horizontal openings. Fluid/vacuum could be evenly distributed in the tube via the fixing element. In particular, it would be possible to provide a fluid flow from one end of the tube to the other end. A distribution element might also be advantageous in an embodiment in which both ends of the passage are open.

Figures 11 and 12 show an alternative embodiment of the closing apparatus 6, which differs from the embodiment described above, particularly with respect to the end covers 26, and also with respect to the construction of the closing mechanism 50.

The main body 24 may be constructed as described above. The end covers 26 may also be similarly constructed, i.e. having a rectangular base body 30 and a connecting flange 32. Again, a recess 34 is provided, as in the previous embodiment, wherein the recess is deeper in this embodiment.

Furthermore, a lateral bore 60 is provided in the base body 30, wherein the lateral bore 60 intersects the recess 34.

The closing mechanism 50 comprises a tube 52, a support sleeve 54, and a fixing element, which is not shown in the figures for simplification. The closing mechanism 50 further comprises a second tube 62. The tube 62 may be generally constructed in the same way as the tube 52 described above. The tube 62 may also be made from the same material as the tube 52;

however, the tube 62 has a smaller outer diameter in the unloaded condition than the inner diameter of the tube 52 in an unpressurized condition. Furthermore, the tube 62 is longer than the tube 52. Particularly, the tube 62 is sized such that the tube 62 may extend through the tube 52 and may project from the tube 52 on both ends, as is shown in Figures 11 and 12 for one side. Between the tubes 52 and 62, a small annular gap is formed.

Particularly, the length of the tube 62 is sized such that the tube 62 may also extend over the lateral bore 60 in the recess 34 into the corresponding recess 34, as may be seen in Figures 11 and 12. The support sleeve 54 has a ring body, however, in the embodiment of Figures 11 and 12, the ring body is longer than in the previous embodiment. The support sleeve or support ring 54 is sized such that the support sleeve 54 fits into the tube 62 and widens the tube 62 slightly in an end region.

Furthermore, the support ring 54 is sized such that the support ring partly extends into an end region of the tube 52, which extends over the tube 62, as may be seen in Figures 11 and 12. The support ring 54 is sized such that the support ring 54 is able to force the tube 62 against an O-ring 68 received in the recess 34, while at the same time the support ring 54 provides for the tube 52 being forced against the O-ring 38 in the transition region between the end cover 26 and the main body 24.

Thus, a ring space is formed in the recess 34 between the O-ring 68 and one end of the tube 52, wherein the ring space may be connected to vacuum via the lateral bore 60, as will be explained in more detail in the following. Operation of the closing mechanism 50 according to Figures 11 and 12 will be explained in more detail in the following.

As a starting point, the closing mechanism 50 is in the position according to Figure 11. A pressurized fluid is directed through the tube 62 via the connection flange 32 in order to expand the tube 62 and force the tube 62 outwardly against the tube 52. By this means, the tube 52 is forced against the passage 27 in the main body 24, in order to seal the laterally extending passage 22. For opening the passage 22, the pressure within the tube 62 is reduced, and vacuum is applied between the two tubes 62, 52 via the lateral bore 60. Because of the vacuum, the tube 52 contracts and causes the tubes 52 and 62 to collectively contract and to unblock the passage 22, as shown in Fig. 12. The contracting may be controlled via a corresponding fixing element such as the fixing element 56. The advantage of this arrangement is that vacuum is applied between the two tubes 52, 62 in order to provide the unblocking action. By this means, it is possible to constantly direct a fluid through the inner tube 62, however at a reduced pressure, even in the open condition of the opening mechanism, thus e.g. maintaining a predetermined temperature, particularly for cooling.

Besides a simple and cost-effective construction, the closing apparatus according to the present invention may offer the following benefits:

- the closing element itself, i.e. the tube, may be fed with a fluid and may thus be directly cooled or controlled to a predetermined temperature, which inhibits or at least reduces e.g. condensation of gases in the vapor phase or other particle deposition.

- the closing element itself, i.e. the tube, may be easily maintained/replaced without the need to disconnect the main body from the process chamber. - the actual closing element, i.e. the tube, is subject to self-cleaning due to

movement between the closed and open positions because of the flexibility of the tube;

- the closing apparatus is adapted for vacuum. The invention has been described referring to preferred embodiments, however, the invention is not limited to the directly shown embodiments. Furthermore, it is possible to combine and/or exchange features of different embodiments, as far as these features are compatible.