Crucible for growing crystals

Abstract

The invention relates to a crucible (1) for growing crystals, comprising a crucible lid (2) and a crucible bottom (3), and a crucible wall (4), which extends with respect to a longitudinal central axis (L) of the crucible (1), a growth chamber (5) within the crucible wall (4) being delimited by the crucible lid (2) and the crucible bottom (3). The crucible also comprises a crystal holder (6), which is located in the region of the crucible lid (2) and is designed to receive at least one seed crystal (7), the crucible (7) being designed to receive starting material (8) which is provided for deposition on the seed crystal (7) in a growing process. The crucible (1) has multiple receiving elements (13) for receiving the starting material (8), the receiving elements (13) being arranged one above the other with respect to the longitudinal central axis (L).

Description

[0001] Crucibles for growing crystals

[0002] The invention relates to a crucible for growing crystals, in particular SiC crystals, comprising a crucible lid and a crucible base, as well as a crucible wall extending along a longitudinal center axis of the crucible, and wherein a growth chamber is defined within the crucible wall by means of the crucible lid and the crucible base. Furthermore, the crucible comprises a crystal holder arranged in the region of the crucible lid and configured to receive at least one seed crystal. The crucible is configured to receive solid (e.g., powdered) starting material intended for deposition on the seed crystal in a growth process.

[0003] JP2007308355 A discloses a device comprising a crucible for growing SiC crystals. A crystal substrate is arranged on the crucible's top surface and a raw material for growing a crystal is accommodated in the bottom region of the crucible. Furthermore, an upper portion of the crucible wall is tapered with respect to its receiving space toward the crucible lid, which is placed on a lower portion of the crucible in which the raw material is accommodated.

[0004] A disadvantage of such crucibles from the state of the art is that they often do not provide an optimal distribution of the raw material within the crucible, or an ideal, uniform sublimation behavior of the raw material over the duration of the growth process.

[0005] The object of the present invention was to overcome the disadvantages of the prior art and to provide a crucible by means of which a user is able to carry out an improved arrangement and distribution of the starting material for crystal growth in the crucible.

[0006] This object is achieved by a crucible according to the claims.

[0007] The crucible according to the invention comprises a plurality of receiving elements for receiving (or storing) the starting material, wherein the receiving elements are arranged one above the other with respect to the longitudinal central axis.

[0008] By means of the configuration according to the invention, it is possible to provide a spaced-apart arrangement of several layers or receiving areas of the starting material (with respect to the longitudinal central axis), as well as to be able to better vary its surface intended for sublimation. This makes it possible to create individual, separate receiving areas for the starting material, which are arranged in a common growth chamber. Furthermore, it is possible to provide different compositions and particle sizes of the starting material in the crucible, which can be arranged on the individual receiving elements. Thus, the multiple receiving elements enable a (spatially) separate / spaced receiving of starting materials from one another, so that they can be arranged in the crucible in the form of spaced-apart layers.

[0009] For the sake of completeness, it should be mentioned that “several” receiving elements means at least two receiving elements arranged one above the other, whereby one of them can also be formed, for example, by the crucible base.

[0010] With regard to the arrangement “on top of each other”, these are preferably arranged in such a way that the receiving elements form individual receiving zones or receiving planes transverse to the longitudinal central axis in the crucible.

[0011] The support elements according to the invention are load-transferring or load-absorbing elements intended for supporting the starting material for the growth process. These are preferably arranged substantially transversely to the longitudinal central axis (or perpendicular to it) in the crucible and thus extend (each) at least from the crucible wall toward the crucible center.

[0012] Furthermore, the receiving elements are preferably designed such that the plurality of receiving elements form a continuous opening in the region of the longitudinal central axis from the crucible bottom (or above the bottom) to the crystal.

[0013] Preferably, it can be provided that at least one of the receiving elements is ring-disk-shaped. One advantage of ring-disk-shaped receiving elements is that they direct the gas flow in the crucible centrally onto the growing crystal. This promotes a convex shape of the growing crystal, which has a positive effect on polytype stability and defect density. For the sake of completeness, it should be mentioned that the ring-disk shape is preferably arranged concentrically to the longitudinal central axis. Furthermore, it should be mentioned that, regardless of the specific design, the receiving elements preferably bear radially circumferentially against the crucible wall so that this delimits a receiving area for the starting material to the outside, or the receiving area is formed between the crucible wall and the respective receiving element.

[0014] A possible further development provides that the receiving elements each have a boundary wall facing the longitudinal central axis, wherein the boundary wall delimits the receiving area of ​​the respective receiving elements for receiving the starting material radially to the longitudinal central axis. This ensures that the receiving elements can accommodate the greatest possible amount between the crucible wall and the crucible center. In the case of ring-disk-shaped receiving elements, these boundary walls are preferably also ring-shaped or hollow-cylindrical (with respect to the longitudinal central axis). The boundary walls can form an integral part of the receiving elements or else a further element which is fastened to the receiving elements or at least mounted. For the sake of completeness, it should be mentioned that the boundary walls are preferably arranged at a radially inner end of the receiving elements or in the region of the formed opening.

[0015] In an advantageous development, it can be provided that the boundary wall is formed at least partially from a shaped solid body, wherein the solid body consists of a material that has the same or a similar (chemical) composition as the starting material (e.g. SiC). Thus, the boundary wall can be formed from a, e.g., pressed or sintered starting material, which is (gradually or step by step) converted into the gas phase during the process together with the starting material stored on the receiving elements. The purity of the material preferably corresponds to that of the starting material. For the sake of completeness, it should be mentioned that a "similar composition" means a material selection that would not cause any undesired contamination of the crystal and thus comprises the same elements.

[0016] Furthermore, it can also be provided that the density of the solid increases toward the receiving element, so that a section facing the crucible lid can dissolve more quickly during the growth process than a deeper section, or the deeper section is less reactive, thus ensuring stability relative to the stored starting material. In this regard, it can also be provided that the material (of the boundary walls) is also designed in the form of a composite material, e.g., consisting of SiC and carbon, whereby SiC dissolves more easily during the process and carbon dissolves less easily.

[0017] In a further embodiment, the boundary wall can be inclined to the longitudinal central axis in a direction extending from the receiving element to the crucible lid. This allows for a larger receiving volume for the starting material, as well as improved gas flow guidance in the region of the crucible center toward the crystal.

[0018] One possible embodiment provides for a radial distance between the respective stacked receiving elements and the longitudinal center axis to decrease, starting from the crucible lid toward the crucible bottom, so that an opening formed by the respective receiving elements becomes smaller in the region of the crucible center. This also contributes to a favorable flow behavior of the gas during the growth process and simultaneously increases the possible receiving volume for the starting material.

[0019] Furthermore, the receiving elements can be attached to the crucible wall. This can be achieved by a fixed arrangement or connection of the receiving elements to the crucible wall, or by a detachable connection so that they can be removed from the wall after the process.

[0020] Another embodiment provides for the receiving elements to be inserted into the crucible along the longitudinal center axis. This configuration enables particularly simple filling of the receiving elements with the starting material, since they can, for example, be at least partially filled before insertion, but can also be easily filled from above after insertion. Above all, the next receiving element can then be inserted from above, and this process can be repeated.

[0021] According to an advantageous embodiment, it can be provided that the crucible wall has at least one stepped shoulder, with at least one receiving element being placed on the at least one stepped shoulder. In one possible form, the receiving elements can, for example, have different outer diameters, or the crucible wall can have different inner diameters. In a possible further development, it can be provided that a thickness of at least one of the receiving elements decreases, starting from the crucible wall in the direction of the longitudinal central axis. In this way, the receiving element can be designed in a material-saving manner in its shape as a support structure for the starting material and yet can still be sufficiently dimensioned with regard to its load-bearing capacity.

[0022] Furthermore, it can be provided that (along the longitudinal center axis) a surface facing the crucible lid and / or a surface facing away from the crucible lid of at least one of the receiving elements is inclined, wherein the respective surface, starting from the crucible wall in the direction of the longitudinal center axis, is inclined towards the crucible lid. With an inclined surface or underside of the receiving elements facing away from the crucible lid, a gas flow can in turn be directed more effectively towards the center of the crucible. An inclination of the surface facing the crucible lid or the receiving surface of the receiving elements can in turn enable improved load-bearing behavior or improved statics.

[0023] An alternative embodiment provides that the receiving elements are designed in the form of closed containers, wherein the containers are made of permeable material and / or have gas-permeable openings.

[0024] One possible embodiment provides that, with respect to the longitudinal center axis, a respective wall thickness of the crucible wall in a respective receiving region of at least two of the receiving elements arranged one above the other differs from one another. By means of such a configuration, it is possible to achieve different process conditions in the respective receiving region so that, for example, a temperature can be specifically controlled in this region via the wall thickness using, for example, an inductive heater. In this way, the starting material located within this wall can be specifically heated earlier or later. This can be controlled more effectively, in particular if the material in this region is to be transferred into the gas phase at a specific time during the process, e.g. for a doping process.

[0025] For a better understanding of the invention, it is explained in more detail using the following figures.

[0026] They show in a highly simplified, schematic representation: Fig. 1 A device for producing crystals with a crucible accommodated therein;

[0027] Fig. 2 shows a possible embodiment of a crucible with receiving elements;

[0028] Fig. 3 shows another possible embodiment of the crucible;

[0029] Fig. 4 shows a possible arrangement of the receiving elements;

[0030] Fig. 5 shows a possible design of the receiving elements;

[0031] Fig. 6 shows another possible design of the receiving elements.

[0032] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the position information chosen in the description, such as top, bottom, side, etc., refer to the directly described and illustrated figure, and these position information must be applied analogously to the new position in the event of a change in position.

[0033] Fig. 1 shows a device for producing single crystals by means of vapor deposition. The device 9 comprises an evacuable chamber 10, with a crucible 1 according to the preamble accommodated therein (whereby a crucible according to the invention can also be accommodated therein in this way). An underside of the crucible lid 2 can form a crystal holder 6 of the crucible 1 and is designed to attach (at least) one seed crystal 7. In a bottom region of the crucible 1, delimited by the crucible wall 4 and the crucible bottom 3, there is a starting material 8, which is intended for crystal growth on the seed crystal 7 and is used up during the growth or breeding process.

[0034] The transition of the starting material into the gas phase is achieved by heating it with at least one heater 11. According to this exemplary embodiment, the heating of the starting material 8 and the crucible 1 by the heater 11 occurs inductively. The crucible 1 arranged in the chamber 10 can also be enclosed by insulation 12 for thermal insulation. The insulation 12 simultaneously prevents heat loss from the crucible 1 and achieves a heat distribution in the interior of the crucible 1 that is favorable for the crystal growth process on the seed crystal 7.

[0035] The material for the chamber 10 is preferably a glass material, in particular quartz glass. The crucible 1 and the insulation 12 surrounding it are preferably made of graphite, with the insulation 12 being formed by a graphite felt or the like.

[0036] When the starting material 8 is heated, its atoms or molecules pass into the gas phase. They can diffuse into the interior of the crucible 1 via the gas phase and deposit on the seed crystal 7, thereby causing crystal growth. The aim is to form a single crystal that is as free of defects as possible. The quality of the crystal forming on the seed crystal 7 depends predominantly on the temperature gradient between the starting material 8 and the seed crystal 7, and also, among other things, on the evaporation rate of the starting material 8. The latter, in turn, depends on the form in which the starting material 8 is made available in the crucible 1. It can prove advantageous if the starting material 8 is formed from a mixture of a powdered raw material and a raw material in the form of lumps.Alternatively, this can also be in the form of particles (especially silicon carbide) with a very limited size distribution.

[0037] Fig. 2 shows a possible embodiment of a crucible 1 according to the invention, which is preferably used for growing SiC crystals.

[0038] The crucible 1 comprises a crucible lid 2, a crucible bottom 3, and a crucible wall 4, wherein the crucible wall 4 extends with respect to a longitudinal central axis L of the crucible 1 and a growth chamber 5 is delimited within the crucible wall 4 by means of the crucible lid 2 and the crucible bottom 3.

[0039] In the area of ​​the crucible lid 2, a crystal holder 6 is arranged, which is designed to hold at least one seed crystal 7. The crucible 1 is designed to hold solid or powdered starting material 8, which is intended for deposition on the seed crystal 7 in a growth process.

[0040] According to the invention, the crucible 1 has a plurality of receiving elements 13 for the spaced-apart reception or storage of the starting material 8, wherein the receiving elements 13 are arranged one above the other with respect to the longitudinal central axis L. Thus, the individual receiving elements 13 can form individual receiving regions 15 for the starting material 8 with respect to an axial direction, which are spatially separated from one another but are arranged in the same process chamber with respect to the gas phase. Preferably, the receiving elements 13 extend radially from the crucible wall 4 in the direction of the longitudinal central axis L. Furthermore, the receiving elements 13 can be designed in the shape of an annular disk, corresponding to a shape of the crucible 1, so that a radially inner end of the receiving elements 13 is spaced from the longitudinal central axis L or an opening is formed.

[0041] Regardless of the design of the receiving elements 13, these are preferably delimited by the crucible wall 4 as shown, or the receiving elements 13 together with the crucible wall 4 form a type of container or define the receiving area 15 for the starting material 8.

[0042] As can further be seen from Fig. 2, the receiving elements 13, regardless of the embodiment, are preferably arranged one above the other (spaced apart) in such a way that a small free space is formed between a receiving area of ​​a receiving element 13 and a receiving element 13 arranged above it, so that a gas flow of the starting material 8 to be evaporated can flow on the underside of the receiving element 13 arranged above it to the center of the crucible (in the direction of the opening).

[0043] Preferably, the receiving elements 13 can each have a boundary wall 14 facing the longitudinal center axis L, wherein a respective boundary wall 14 delimits the receiving area 15 of the respective receiving elements 13 for receiving the starting material 8, starting from the crucible wall 4 radially to the longitudinal center axis L. The receiving elements 13 and boundary walls 14 can be formed in one piece, but the boundary walls 14 can also be placed on the receiving elements 13, as can be seen, for example, from Fig. 3. The boundary walls 14 also each extend from the receiving element 13 in the direction of the crucible lid 2. As mentioned at the beginning, the boundary walls can also be formed from a shaped solid body whose material has the same or a similar composition as the starting material 8.

[0044] As shown in Fig. 2, the boundary wall 14 can be inclined in a direction starting from the receiving element 13 to the longitudinal center axis L. In other words, the boundary wall 14 can be tapered from the crucible base 3 in the direction of the crucible lid 2 to the longitudinal center axis L. Furthermore, it can be provided independently of this that a radial distance 16 of the superimposed receiving elements 13 to the longitudinal center axis L is decreasing, starting from the crucible lid 2 in the direction of the crucible base 3. By means of the radial distance 16, an opening of the receiving element can be defined in the region of the crucible center.

[0045] Preferably, the receiving elements 13 can be inserted into the crucible 1 along the longitudinal central axis L. The crucible wall 4 can have at least one stepped shoulder 17, with at least one receiving element 13 being placed on the at least one stepped shoulder 17. With such an arrangement of several receiving elements 13 on stepped shoulders 17 of the crucible wall 4, the respective receiving elements 13 can become smaller in terms of their outer dimensions or outer diameter 19 in the direction of the crucible bottom 3. Alternatively or additionally, with regard to the stepped shoulders 17, it can be provided that the crucible wall 4 is conically tapered in the direction of the crucible bottom 3.

[0046] As further illustrated in Fig. 2, the receiving element 13 that is lowest with respect to the longitudinal center axis can simultaneously form the crucible bottom 3. Furthermore, the receiving element 13 arranged in the bottom region can be designed to be closed, so that, as illustrated, in such an inclined embodiment, the boundary wall 14 forms, for example, a closed conical shape.

[0047] Irrespective of the embodiment shown, a thickness 18 of the receiving elements 13 can be designed to decrease with respect to the longitudinal central axis L, starting from the crucible wall 4 in the direction of the longitudinal central axis L. In this regard, it can preferably be provided that at least one of the receiving elements 13 is designed to be inclined at an angle α to the horizontal on a surface 27 facing away from the crucible lid 2, wherein the surface 27, starting from the crucible wall 4 in the direction of the longitudinal central axis L, is designed to be inclined towards the crucible lid 2, as shown. The angle to the horizontal can be designed to be constant for all receiving elements 13, or else different, e.g. increasing in the direction of the crucible bottom.

[0048] Furthermore, the receiving elements 13 as a whole can also have an inclination to the longitudinal central axis L, so that, for example, a radially inner end of the receiving elements 13, in the region of the longitudinal central axis L, is closer to the crucible lid 2 than a radially outer end of the receiving elements 13, in the region of the crucible wall 4. For example, it can also be provided that the receiving element 13 is also inclined on a surface 26 facing the crucible lid 2, which surface is also inclined towards the crucible lid 2, starting from the crucible wall 4 in the direction of the longitudinal central axis L, as indicated by dashed lines in Fig. 2. The surface 26 facing the crucible lid 2 is a receiving surface for the starting material.

[0049] A cover element 20 can be arranged above the receiving elements 13, by means of which a gas flow toward the center of the crucible is promoted. The cover element can be made of the crucible material and is preferably impermeable, and also, as shown, can have an inclined surface.

[0050] As further evident from Fig. 2, it can be provided that, with respect to the longitudinal center axis L, a respective wall thickness 28 of the crucible wall 4 in a respective receiving area 15 of at least two of the superimposed receiving elements 13 differs from one another. Furthermore, the wall thickness 28 can increase toward the crucible bottom 3.

[0051] 3 and 4, it can be provided that the receiving elements 13 are mounted in the crucible 1 by means of the boundary walls 14. The boundary walls 14 can be inclined to the longitudinal center axis L, as shown in Fig. 3, or else parallel to this, as in Fig. 4, for example. The receiving elements 13 arranged above are thus placed on the boundary wall 14 of the next receiving element 13 located below it, or are supported by it and are thereby spaced from the next receiving element 13. In such a configuration, the crucible base 3 can preferably form the lowest receiving element 13. Alternatively, a receiving element 13 can also be inserted on the crucible base 3, as indicated by the dashed lines.

[0052] If the receiving elements 13 and the boundary walls 14 are formed separately, the receiving elements 13 and / or the crucible bottom 3 can have a groove, elevation or the like for centering the boundary walls 14.

[0053] The boundary walls 14 and / or the receiving elements 13 can be designed to be permeable or can also have gas-permeable openings 21, as indicated by the openings 21 in the boundary walls 14. In principle, such a design with regard to gas permeability can be provided in all embodiments of the receiving elements and boundary walls.

[0054] As shown in Fig. 3, a respective boundary wall 14 of the receiving elements 13 can be inclined with respect to their axial extension from the receiving element 13 in a direction starting from the longitudinal center axis L to the crucible wall 4. In other words, the boundary wall 14 can be tapered from the crucible lid 2 in the direction of the crucible bottom 3 to the longitudinal center axis L.

[0055] By means of this design, a gas flow between the boundary walls 14 and the longitudinal center axis L is particularly favored, since the available volume becomes larger in the direction of the crucible lid 2.

[0056] Independently of the support by the boundary walls 14, individual webs 22 for supporting the receiving elements 13 can be provided on the crucible wall 4, wherein the receiving elements 13 can have complementary recesses 23, by means of which the receiving elements 13 can be guided through the webs 22 along the longitudinal center axis L, so that they can be placed or mounted in the underlying planes. The webs 22 can preferably be formed as partial webs on the crucible wall 4 in the circumferential direction and offset from one another by an angular amount, e.g. 2 webs by 180° or 3 webs by 120° in the circumferential direction and likewise offset from one another by an additional angular amount with respect to the different receiving planes for supporting the receiving elements 13.

[0057] Furthermore, further support elements 24 can also be arranged between the receiving elements, which support elements promote a space for a flow of the gas between the receiving elements 13, which support elements 24 are schematically indicated by way of example in Fig. 4.

[0058] In a possible further development, it can be provided that the receiving elements 13 (at least after insertion into the crucible wall) are designed in the form of closed containers, wherein the containers are made of permeable material and / or have gas-permeable openings. Furthermore, it can be provided that the receiving elements 13 are fastened to the crucible wall 4. As can be seen from Fig. 5, in one possible embodiment, it is provided that the receiving elements 13 are formed integrally with the crucible wall 4. In this regard, the crucible wall 4 can consist of several segments 25 which can be stacked one above the other, so that the crucible wall 4 and the individual receiving areas for the starting material 8 are formed by means of the segments 25. Furthermore, the receiving elements 13 or the segments 25 can also be formed integrally with the various embodiments of the aforementioned boundary walls, as indicated by dashed lines.Furthermore, the segments 25 may each have individual, preferably equally sized, ring webs for supporting the receiving elements.

[0059] Furthermore, Fig. 5 indicates a possible configuration of different wall thicknesses 28, whereby the respective segments 25 can, for example, have different outer and / or inner diameters. Using such a configuration, any desired area can be provided with a different wall thickness.

[0060] Fig. 6 shows a further possible embodiment of the receiving elements 13, in which the surface 26 facing the crucible lid 2 and the surface 27 of the receiving elements 13 facing away from the crucible lid 2 are inclined, with the respective surface 26, 27 being inclined toward the crucible lid 2, starting from the crucible wall 4 in the direction of the longitudinal center axis L. Furthermore, additional boundary walls (not shown) mentioned above can be provided, in particular to achieve a higher degree of filling.

[0061] The facing and the remote surfaces 26, 27 can be configured parallel to one another, so that the thickness of the receiving elements 13 remains constant, or they can also run at an angle to one another, so that the thickness decreases, as previously mentioned. Regarding the aforementioned inclinations, these can, for example, be configured at an angle a of 2° to 30° relative to the horizontal, although larger angles, e.g., approximately 45°, are also conceivable.

[0062] Furthermore, Fig. 6 also shows the previously mentioned webs 22 in the crucible wall 4, by means of which the receiving elements 13 can be mounted. To guide the receiving elements 13 arranged underneath, through the webs 22, these also have the aforementioned recesses 23. The webs 22 can be arranged offset with respect to the individual layers or, for example, all arranged one above the other in axial alignment, for example by simply rotating the receiving elements 13 slightly after being passed through, or the like. The receiving elements 13 can all be of identical design in this respect.

[0063] In addition, it is also conceivable to use a receiving element 13 as a cover element 20 (and not to store any starting material on it).

[0064] In addition, such an inclined design of the receiving elements 13 together with the crucible walls can also be designed in the form of previously mentioned segments 25.

[0065] Figures 5 and 6 show a further, possibly independent, embodiment of the crucible, wherein the same reference numerals or component designations are used for identical parts as in the preceding figures. To avoid unnecessary repetition, reference is made to the detailed description in the preceding figures.

[0066] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with each other are also possible and this possibility of variation lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action by means of the objective invention.

[0067] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0068] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10. For the sake of clarity, it should be pointed out that in order to improve understanding of the structure, some elements have been shown out of scale and / or enlarged and / or reduced.

[0069] Reference symbol list

[0070] crucible

[0071] Crucible lid Crucible bottom Crucible wall

[0072] Growing chamber Crystal holder Seed crystal Starting material Device Chamber

[0073] Heating

[0074] Insulation mounting elements

[0075] Boundary wall recording area

[0076] Distance

[0077] Paragraph

[0078] thickness

[0079] Outer diameter cover element

[0080] Breakthroughs

[0081] Webs Recesses Support elements

[0082] Segments facing surface facing away surface wall thickness

[0083] angle

Claims

Patent claims 1. Crucible (1) for growing crystals comprising; - a crucible lid (2) and a crucible bottom (3), and - a crucible wall (4), wherein the crucible wall (4) extends with respect to a longitudinal central axis (L) of the crucible (1) and a growth chamber (5) is delimited within the crucible wall (4) by means of the crucible lid (2) and the crucible bottom (3); - a crystal holder (6), wherein the crystal holder (6) is arranged in an upper region of the crucible (1) and is designed to receive at least one seed crystal (7); and wherein the crucible (1) is provided for receiving starting material (8) which is intended for deposition on the seed crystal (7) in a growth process; characterized in that the crucible (1) has a plurality of receiving elements (13) for receiving the starting material (8), wherein the receiving elements (13) are arranged one above the other with respect to the longitudinal central axis (L).

2. Crucible (1) according to claim 1, characterized in that at least one of the receiving elements (13) is ring-disk-shaped.

3. Crucible (1) according to claim 1 or 2, characterized in that at least one of the receiving elements (13) has a boundary wall (14) facing the longitudinal center axis (L), wherein the boundary wall (14) delimits a receiving area (15) of the receiving element (13) for receiving the starting material (8) radially to the longitudinal center axis (L).

4. Crucible (1) according to claim 3, characterized in that the boundary wall (14) is inclined to the longitudinal central axis (L) in a direction starting from the receiving element (13) to the crucible lid (2).

5. Crucible (1) according to claim 3 or 4, characterized in that the boundary wall (14) is formed at least partially from a shaped solid body, wherein the solid body consists of a material which has the same or similar composition as the starting material (8).

6. Crucible (1) according to one of claims 1 to 5, characterized in that a radial distance (16) of the respective superimposed receiving elements (13) to the longitudinal center axis (L) is designed to decrease, starting from the crucible lid (2) in the direction of the crucible bottom (3).

7. Crucible (1) according to one of claims 1 to 6, characterized in that at least one of the receiving elements (13) is fastened to the crucible wall (4).

8. Crucible (1) according to one of claims 1 to 7, characterized in that at least one of the receiving elements (13) is inserted into the crucible (1) along the longitudinal central axis (L).

9. Crucible (1) according to one of claims 1 to 8, characterized in that the crucible wall (4) has at least one step-shaped shoulder (17), wherein at least one of the receiving elements (13) is placed on the at least one step-shaped shoulder (17).

10. Crucible (1) according to one of claims 1 to 9, characterized in that a thickness (18) of at least one of the receiving elements (13) is designed to decrease starting from the crucible wall (4) in the direction of the longitudinal central axis (L).

11. Crucible according to one of claims 1 to 10, characterized in that a surface facing the crucible lid (2) and / or a surface facing away from the crucible lid (2) of at least one of the receiving elements (13) is inclined, wherein the respective surface is inclined towards the crucible lid (2) starting from the crucible wall (4) in the direction of the longitudinal central axis (L).

12. Crucible (1) according to one of claims 1 to 11, characterized in that at least one of the receiving elements (13) is designed in the form of a closed container, wherein the container is made of permeable material and / or has gas-permeable openings.

13. Crucible (1) according to one of claims 1 to 12, characterized in that with respect to the longitudinal center axis (L) a respective wall thickness of the crucible wall (4) in a respective receiving area (15) of at least two of the receiving elements (13) arranged one above the other is different from one another.

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