CRYSTAL GROWTH APPARATUS

Abstract

The present invention relates to an apparatus for growing crystals. The apparatus comprises a chamber and a crucible being arranged in a heatable accommodation space of the chamber, wherein the crucible comprises an inner volume which is configured for growing crystals inside. The crucible comprises a bottom from which respective side walls extend to a top section of the crucible. The crucible comprises at least one a deposition section which is configured for attaching a seed crystal, wherein the deposition section is formed on at least one of the side wall and the top section of the crucible.

Claims

1. Apparatus for growing crystals, the apparatus comprising a chamber, and a crucible being arranged in a heatable accommodation space of the chamber, wherein the crucible comprises an inner volume which is configured for growing crystals inside, wherein the crucible comprises a bottom from which respective side walls extend to a top section of the crucible, wherein the crucible comprises at least one deposition section which is configured for attaching a seed crystal, wherein the deposition section is formed on at least one of the side wall and the top section of the crucible.

2. Apparatus according to claim 1, wherein the bottom is free of a deposition section for a seed crystal.

3. Apparatus according to claim 1, wherein the crucible extends between the bottom and the top section along a vertical direction.

4. Apparatus according to claim 1, wherein the crucible comprises plurality of deposition sections, each being configured for attaching a seed crystal, wherein the deposition sections are spaced apart from each other and are formed on at least one of the side wall and the top section of the crucible.

5. Apparatus according to claim 1, wherein the crucible comprises at least one protrusion extending from an inner surface, in particular from the side wall or the top section of the crucible, into the inner volume, wherein the deposition section is formed at the protrusion.

6. Apparatus according to claim 5, wherein the crucible comprises a plurality of protrusions extending from the inner surface of the crucible into the inner volume, wherein the protrusions are spaced apart from each other.

7. Apparatus according to claim 1, wherein the crucible comprises at least one nozzle, wherein the nozzle is configured for injecting a reaction fluid into the inner volume of the crucible.

8. Apparatus according to claim 7, wherein the at least one nozzle is configured for ejecting the reaction fluid in a direction towards one of the deposition sections.

9. Apparatus according to claim 7, wherein the crucible comprises an ejection column element extending partially between the bottom and the top section of the crucible, wherein the ejection column element comprises the at least one nozzle.

10. Apparatus according to claim 9, wherein the ejection column element is coupled with a reaction fluid interface formed in the bottom of the crucible.

11. Apparatus according to claim 1, wherein the crucible comprises an injection interface for injecting an injection fluid, wherein the injection interface is coupleable to a pressure regulating valve for regulating a pressure inside the inner volume.

12. Apparatus according to claim 1, wherein the chamber comprises a plurality of heating elements, which surround an outer wall of the chamber to provide a heat energy to the crucible.

13. Apparatus according to claim 12, wherein the plurality of heating elements are configured for heating up the inner volume to a temperature between 1350° C. and 1450° C.

14. Apparatus according to claim 12, wherein the plurality of heating elements is selected from one of RF heaters, resistive heaters, and heating generators.

15. Apparatus according to claim 1, further comprising an insulating material arranged in the accommodation space between the crucible and a wall of the chamber.

16. Apparatus according to claim 1, wherein the crucible is made of a material selected from one of the group comprising metal based, oxide based, nitride based, carbon based and dense graphite.

17. Apparatus according to claim 1, further comprising a growth power enhancing device to enhancing the nucleation of a crystal on the deposition site, wherein the growth power enhancing device is selected from one of the group consisting of a plasma source, microwave source and a laser source.

18. Method for growing crystals, the method comprising attaching a seed crystal to a deposition section of a crucible, wherein the deposition section is formed on at least one of a side wall and a top section of the crucible, growing crystals inside an inner volume of the crucible being arranged in a heatable accommodation space of a chamber.

19. Method according to claim 18, further comprising providing a source material consisting of one of a reaction fluid, in particular liquid, and an injection fluid, in particular liquid, in the crucible, wherein the source material is selected from one of the group consisting of solid phase material, liquid phase material, gaseous phase and mixture phase material comprising a C—, H—, CH— solution.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0042] The aspects defined above and further aspects of the present invention are apparent from the examples of embodiments to be described hereinafter and are explained with reference to the examples. The invention will be described in more detail hereinafter with reference to examples of embodiments but to which the invention is not limited.

[0043] FIG. 1 shows a schematic view of the apparatus for growing crystals according to an exemplary embodiment.

[0044] FIG. 2 shows a piece of polycrystalline formed at a top side deposition section of an apparatus according to an exemplary embodiment.

[0045] FIG. 3 shows multiple crystals at respective lateral deposition sections of an apparatus according to an exemplary embodiment.

[0046] FIG. 4 shows multiple unoriented crystals generated below lateral deposition sections of an apparatus according to an exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0047] The illustrations in the drawings are schematic. It is noted that in different figures similar or identical elements are provided with the same reference signs.

[0048] FIG. 1 shows a schematic view of the apparatus 100 for growing crystals according to an exemplary embodiment. The apparatus comprises a chamber 101 and a crucible 102 being arranged in a heatable accommodation space 103 of the chamber 101, wherein the crucible 102 comprises an inner volume 104 which is configured for growing crystals inside. The crucible 102 comprises a bottom 105 from which respective side walls 106 extend to a top section 107 of the crucible 102. The crucible 102 comprises at least one a deposition section which is configured for attaching a seed crystal 108, wherein the deposition section is formed on at least one of the side wall 106 and the top section 107 of the crucible 102.

[0049] The chamber 101 provides a heatable accommodation space 103 for the crucible 102. The apparatus 100 and the crucible 102, respectively, heat the inner volume 104 of the crucible until a desired temperature is reached. The temperature which may be provided inside the inner volume 104 may be 100° C. to 1400° C., preferably to approximately 2100° C. or more. The camber 101 comprises an insulating material 121, such that the inner volume 104 of the crucible is thermally isolated from an environment, i.e. an intermediate volume, surrounding the camber 101.

[0050] The crucible 102 comprises the inner volume 104 in which the crystal growing takes place. Inside the crucible 104, a seed element 108 is placed. The seed element 108 is made of a desired single crystal material, such as sapphire. Furthermore, a reaction gas/liquid 111, such as a desired crystal material, e.g. high purity alumina crackle, is injected into the inner volume 104 of the crucible 102. If the temperature inside the crucible 102 increases, the desired material within the reaction gas/liquid growth onto a surface of the seed crystal 108. The crucible 102 may comprise a cylindrical shape having a circular, elliptical or rectangular base surface.

[0051] The seed crystal 108 is located at deposition sections D1 to D7 which are defined at side walls 106 of the crucible 102 or at a top section 107 of the crucible 102. The seed crystal 108 is attached for example by a specific glue to the deposition sections D1 to D7. Furthermore, the deposition sections D1 to D7 form a step at the inner wall 106 of the crucible 102, such that the seed crystal 108 may be arranged onto the step forming the deposition section D1 to D7 without any adhesive materials.

[0052] Hence, the crystal growth takes place spaced apart from the bottom 105 in regions of the inner volume 104, which can be temperature controlled more precise. If the deposition sections D1 to D7 are arranged at side walls 106 of the crucible or at its top section 107, the crystals growth from the respective seed crystal 108 is directed laterally from the sidewall 106 of the crucible 102 to the centre of the crucible 102 or upside down, from the top section 107 of the crucible 102 to the bottom 105 of the crucible 102. Based on the lateral growth and a growth direction from the top section 107 to the bottom 105, a nucleation on the deposition sections D1 to D7 is properly controlled so that atomic stacking faults can be reduced. As can be taken from FIG. 1, the bottom 105 is free of a deposition section D1 to D7 for a seed crystal 108. Hence, the temperatures in the vicinity of the bottom 1005 within the inner volume 104 do not affect the homogeneous crystal growth within the centre section and upper section of the crucible 102.

[0053] As can be taken from FIG. 1, the crucible 102 comprises plurality of deposition sections D1 to D7, each being configured for attaching a respective seed crystal 108. The deposition sections D1 to D7 are spaced apart from each other and are formed on at least one of the side wall 106 and the top section 107 of the crucible 102. Hence, from different lateral and top positions of the crucible 100 to, a plurality of crystals may be grown in the direction to the centre of the crucible 100 to.

[0054] The deposition sections D1 to D7 are formed by protrusions extending from an inner surface, in particular from the side wall 106 or the top section 107 of the crucible 102, into the inner volume 104.

[0055] Furthermore, a nozzle 110 of the crucible 102 is shown which is configured for injecting a reaction gas/liquid into the inner volume 104 of the crucible 102. The nozzles 110 are configured for ejecting the reaction gas/liquid 111 in a direction towards one of the deposition sections D1 to D7. The reaction gas/liquid 111 may be a gas, a vapor or a liquid medium. Specifically, the reaction gas/liquid may be a gas mixture or vapor mixture having a single or mixture of C—, H—, CH— solutions or vapor.

[0056] The nozzles 110 are arranged within an ejection column element 112 extending from the bottom 105 at least partially to the top section 107 of the crucible 102. The ejection column element 112 comprises a rod like shape and is fixed to bottom 105 of the crucible 102. The ejection column element 112 is for example a kind of showerhead comprising the plurality of nozzles 110, wherein each nozzle 110 is directed to a respective deposition side D1 to D7. Specifically, the ejection column element 112 extends along a centre axis of the e.g. cylindrical shape of the crucible 102. Hence, the respective nozzles 110 arranged at the ejection column element 112 direct from the centre of the crucible 102 to the side walls 106. Furthermore, the top end of the ejection column element 112 is spaced to the top section 107 of the crucible 102. At the top end of the ejection column element 112 a respective nozzle 110 is arranged which directs to a deposition section D1 located at the top section 107 of the crucible 102.

[0057] The ejection column element 112 is coupled with a reaction gas/liquid interface 113 formed in the bottom 105 of the crucible 102. The ejection column element 112 comprises a gas line extending from the bottom 105 of the column 102 to the respective nozzles 110 arranged at the ejection column element 112.

[0058] The crucible 102 comprises an injection liquid/gas interface 116 for injecting an injection liquid/gas 115, wherein the injection liquid interface 116 is coupleable to a pressure regulating valve 114 for regulating a pressure inside the inner volume 104. For example, the injection liquid interface 116 comprises a plurality of openings arranged for example in the top section 107 of the crucible 102. The injection liquid interface 116 is arranged at an opposite location of the crucible 102 with respect to the reaction liquid interface 113.

[0059] A pressure regulating valve 120 is coupled to the injection liquid/gas interface 116. The pressure regulating valve 120 for regulating a pressure inside the inner volume and the injection liquid/gas interface 116 are coupled to inject liquid/gas and also to bleed of liquid/gas in order to control, i.e. increase or reduce, the pressure inside the crucible.

[0060] The chamber 102 comprises a plurality of heating elements 119, which surround in particular an outer wall of the chamber 102 to provide a heat energy to the crucible 102.

[0061] The apparatus 100 further comprises a growth power enhancing device 117 to enhancing the nucleation of a crystal on the deposition site D1 to D7, wherein the growth power enhancing device 117 is selected from one of the group consisting of a plasma source, microwave source and a laser source.

[0062] At the bottom 105 reaction gas/liquid 111 which is not used is gathered. Hence, because the deposition sides D1 to D7 are spaced apart from the bottom 105 and the bottom 105 is free of any deposition sides D1 to D7, the seed crystals 108 are not in contact with the reaction liquid 111 gathered at the bottom region of the crucible 102. Hence, reaction liquid 111 and the injection liquid 115 already injected from the nozzles 110 and liquid interfaces 116, respectively, to the deposition sides D1 to D7, reacts to the source material 118 and flows down to the bottom 105. The source material 118 gathered at the bottom 105 of the crucible 102 do not affect any more the growing of the crystals.

[0063] FIG. 2 shows a piece of polycrystalline 200 formed at a top side deposition section D1 of the crucible 102 shown in FIG. 1. In order to provide sufficient space for the grown crystal, the ejection column element 112 may be movable along a center (vertical) axis of the crucible 102, such that the distance between the top end nozzle 110 of the ejection column element 112 to the closest point of the grown crystal can be kept constant.

[0064] FIG. 3 shows multiple crystals at respective lateral deposition sections D2 to D7 of the crucible 102 shown in FIG. 1. As can be taken from FIG. 3, a large number of respective crystals can be formed at the same time with one common crucible 102.

[0065] FIG. 4 shows multiple unorientated crystals generated below lateral deposition sections (e.g. at undersides of deposition sections D2 to D7) of the crucible 102 shown in FIG. 1. The multiple unorientated crystals can be gathered and melted to receive the injection liquid and reaction liquid again.

[0066] It should be noted that the term “comprising” does not exclude other elements or steps and “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined.