Growth chamber and method for crystal growth by sublimation

Abstract

The present disclosure relates to a method for growing a crystal in a growth chamber, the method (300) comprises providing (310) a seed crystal (180) into an internal volume (110) of said growth chamber (100), wherein said crystal is arranged to grow at said seed crystal (180); providing (320) a source material (120) comprising material for growing said crystal at said seed crystal (180) into said internal volume (110), wherein the source material (120) is gas- permeable; flowing (340) carrier gas (130) through the source material (120) and thereafter to the seed crystal (180); and heating (350) the internal volume and generating a temperature gradient, thereby releasing material from the source material (120) and allowing the carrier gas flow (130) to transport said released material to the seed crystal (180), whereby the crystal is grown at the seed crystal (180).

Description

[0001] Growth chamber and method for crystal growth by sublimation

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to single-crystal growth, crystal growth by sublimation, SiC and AIN crystal growth, growth chambers for crystal growth, and mass transport by carrier gas.

[0004] BACKGROUND ART

[0005] Silicon carbide (SiC) is a compound that can be grown as a single crystal and has various applications. The common techniques for growing silicon carbide single crystals are based on vapor growth or solution growth. Existing solutions for producing bulk SiC include physical vapor transport, PVT, high temperature chemical vapor deposition, HTCVD, modified physical vapor transport, M-PVT, closed-field physical vapor transport, CF-PVT, halide chemical vapor deposition H-CVD, and solution growth.

[0006] Vapor growth methods involve sublimation of raw materials, mass transport, and surface crystallization on a seed crystal. The most widely used vapor growth method is PVT which typically uses an induction furnace to heat the source material and the seed crystal. PVT can produce large-size SiC boules, but it has challenges such as low growth rate, high defect density, and non-uniform doping. Crystal cracking may be caused by built in stress during growth, which is normally caused by thermal gradients. Existing methods show significant issues when attempting to produce SiC crystals with diameters of 8” or larger. Typically, traditional methods use inductive heating utilizing a copper coil which encircles a quartz tube containing the heated graphite crucible surrounded by a thick insulating layer of graphite felt heated by the coil. The static design of such crucible heating solutions makes it difficult to adapt the thermal gradients required for crystal growth. At high temperature Si diffuses out through the graphite crucible and condenses in the insulating felt which now becomes conductive, coupling to the inductive heating which leads to drift in the system. The Si may also cause etching of the graphite and degradation of the insulation.

[0007] Solution growth methods involve dissolving the source material in a molten solvent and crystallizing it on the seed crystal, such as liquid phase epitaxy, LPE . The most widely used solution growth method is top-seeded solution growth, TSSG, which uses a crucible with a concave bottom to hold the solvent and the seed crystal. TSSG can achieve high growth rate, low defect density, and uniform doping, but it has challenges such as high temperature, high pressure, and complex fluid dynamics. There is a need for new solutions to grow larger crystals with improved quality and crystal growth rates.

[0008] SUMMARY OF THE INVENTION

[0009] Existing solutions to grow crystals have large costs associated with operating growth chambers, such as high energy demands, high source material consumption, and slow growth rates.

[0010] One object of the invention is to provide a growth chamber for producing silicon carbide crystals with a diameter of at least 300 mm.

[0011] This has in accordance with the present disclosure been achieved by means of a method for growing a crystal in a growth chamber. The method comprises

[0012] - providing a seed crystal into an internal volume of said growth chamber, wherein said crystal is arranged to grow at said seed crystal;

[0013] - providing a source material comprising material for growing said crystal at said seed crystal into said internal volume, wherein the source material is gas-permeable;

[0014] - flowing carrier gas through the source material and thereafter to the seed crystal; and

[0015] - heating the internal volume and generating a temperature gradient, thereby releasing material from the source material and allowing the carrier gas flow to transport said released material to the seed crystal, whereby the crystal is grown at the seed crystal.

[0016] This has the advantage of allowing reliable gas transported crystal growth. This further allows the crystal growth to be performed at higher pressure than traditional physical vapor transport methods, thus increasing the potential crystal growth rate and quality.

[0017] In some embodiments, the method further comprises measuring a state of the internal volume through an optical port utilizing a set of sensors, and wherein flowing carrier gas and / or heating based on said measured state.

[0018] This has the advantage of allowing the crystal growth to be controlled based on a measured state of the internal volume.

[0019] In some embodiments, the crystal to be grown at the seed crystal is a crystal of silicon carbide, SiC, aluminium nitride, AIN, gallium nitride, GaN, gallium oxide, Ga2Os, and / or zinc oxide, ZnO, and wherein the source material comprises SiC, AIN, GaN, Ga2Os, and / or ZnO.

[0020] In some embodiments, the seed crystal and the source material are heated to the temperature range of 1700-2700°C. In some embodiments, heating utilizes at least a first heating device arranged to heat the source material and a second heating device arranged to heat the crystal holder and / or the seed crystal.

[0021] This has the advantage of providing improved control of temperature gradients in the internal volume.

[0022] In some embodiments, the method comprises providing a curtain gas flow through the internal volume, wherein the curtain gas flow is arranged to provide a gas curtain for the flow of carrier gas exiting through the source material.

[0023] In some embodiments, crystal growth is performed with a gas pressure in the range of 20 to 150 kPa.

[0024] The present disclosure further relates to a growth chamber for growing a crystal. The growth chamber comprises an internal volume, a seed crystal holder arranged to hold a seed crystal in said internal volume, and a heating device arranged to heat the internal volume to at least 1700°C; wherein the growth chamber is arranged to receive the seed crystal at the seed crystal holder, and to receive, in said internal volume, a gas-permeable source material comprising material for growing said crystal, and to provide a flow of carrier gas through the source material and thereafter to the seed crystal; and wherein the heating device is arranged to provide heat to the internal volume and generating a temperature gradient, thereby releasing material from the source material and allowing the carrier gas flow to transport said released material to the seed crystal, whereby the crystal is grown at the seed crystal.

[0025] In some examples, the growth chamber is arranged to provide a curtain gas flow through the internal volume, wherein the curtain gas flow is arranged to provide a gas curtain for the flow of carrier gas exiting through the source material.

[0026] In some embodiments, the growth chamber comprises a computer arranged to control the heating device, the seed crystal holder, the flow of carrier gas, and / or the flow of curtain gas.

[0027] The present disclosure further relates to a system for growing a crystal. The system comprises a growth chamber according to said growth chamber of the present invention, a computer, and a set of gas flow control devices, wherein the computer is connected to the growth chamber and the set of gas flow control devices, and wherein the computer is arranged to control the set gas flow control devices to control the carrier gas flow through the growth chamber, and control the heating device comprised in the growth chamber to heat the source material. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Fig. 1 shows a cross section of a growth chamber for crystal growth

[0029] Fig. 2 shows a cross section of a growth chamber for crystal growth utilizing gas curtains

[0030] Fig. 3 illustrates gas flow in growth chamber with gas curtains

[0031] Fig. 4 shows a system comprising a growth chamber for crystal growth

[0032] Fig. 5 shows a method for growing a crystal with a growth chamber

[0033] DETAILED DESCRIPTION

[0034] Throughout the figures, same reference numerals refer to same parts, concepts, and / or elements. Consequently, what will be said regarding a reference numeral in one figure applies equally well to the same reference numeral in other figures unless explicitly stated otherwise.

[0035] Terms and expressions

[0036] The term seed crystal relates to a crystal from which crystal growth in the growth chamber starts. It is to be understood that expressions describing transporting material to the seed crystal, or crystal growth occurring at the seed crystal, relates to both the seed crystal and any crystal that has been grown on the seed crystal.

[0037] The term source material relates to material from which the crystal is grown. Typically, the source material is a sintered source material or a powder source material.

[0038] The expression “a gas-permeable source material” relates to a source material that is arranged to allow gas to pass through the source material while at the source material. For example, a gas-permeable source material may be a porous or sintered bulk material, or a powder.

[0039] The expression “material released by sublimation of the source material” relates to source material and derivatives thereof that have been released from the source material due.

[0040] The term carrier gas flow relates to a gas arranged to transport sublimated species from the source material to the region of crystal growth. In some examples, the carrier gas main component is an atom or a molecule with high mass and low diffusivity, such as argon.

[0041] The term curtain gas flow relates to gas arranged to guide the carrier gas. Typically, curtain gas comprises heavy species arranged to push into the carrier gas, thus reducing the probability of species in the carrier gas moving out of the flow of carrier gas. The expression “a heating device comprised in the growth chamber” relates to being arranged at the exterior of the growth chamber, at the internal volume of the growth chamber, or within the walls of the growth chamber that separate the internal volume and the environment.

[0042] Fig. 1 shows a cross section of an example growth chamber 100 for crystal growth. The growth chamber 100 comprises an internal volume 110 surrounded by a first layer comprising a heating device 150 and a second layer comprising insulation 160. The heating device 150 comprised in the first layer is arranged to heat the internal volume 110 to a temperature within a first temperature range.

[0043] The growth chamber 100 comprises a seed crystal holder 170 in said internal volume 110, wherein the seed crystal holder 170 is arranged to hold a seed crystal 180 for growing a crystal (not shown). Typically, the seed crystal holder 170 is arranged to move the seed crystal 180, such as rotating the seed crystal 180. The growth chamber 100 is arranged to hold a source material 120 comprising material to be grown at the seed crystal 180, wherein the source material 120 is arranged to allow a flow of carrier gas 130 pass through said source material 120. The growth chamber 100 is arranged to heat the source material 120 so as to sublimate at least some material to be grown at the seed crystal 180.

[0044] In some examples, the seed crystal holder 170 is arranged to move the seed crystal 180. In some of these examples, the seed crystal holder 170 is arranged to rotate and / or lift the seed crystal 180. Rotating the seed crystal 180 may allow for a more uniform crystal growth, and upon the thickness of the grown crystal increasing, the surface of the crystal may be kept in substantially the same plane by lifting the grown crystal, which may allow flow conditions to be maintained during crystal growth.

[0045] The growth chamber 100 comprises a set of heating devices arranged to maintain temperature gradients between the source material 120 and the seed crystal 180. In some embodiments the growth chamber 100 comprises one heating device 150 providing heat at position(s) closer to the source material 120 than the seed crystal 180. In some embodiments the growth chamber comprises a plurality heating devices 150 arranged to together provide heat so as to maintain temperature gradients between the source material 120 and the seed crystal 180. In some of these examples, each heating devices 150 may be controlled independently. In some examples a first heater is arranged at the source material 120 and a second heater is arranged at the seed crystal holder 170 and / or the seed crystal 180.

[0046] In some examples, the growth chamber 100 is arranged to transport carrier gas 130 through the source material 120 and thereafter to the seed crystal 180. In the example in fig. 1 , the carrier gas 130 enters into the lower section of the internal volume 110, passes through the source material 120, passes the seed crystal 180, and exits the internal volume 110 at the upper section of the internal volume 110 via at least one outlet (not shown). It is to be understood that the geometry of the internal volume 110 and / or the geometry of the path of the carrier gas 130 in relation to the source material 120 and / or the seed crystal 180 may be designed in other ways than shown in the examples.

[0047] In the example in fig. 1 , the seed crystal 180 is a silicon carbide seed crystal, and the source material 120 comprises sintered silicon carbide. The heating device 150 comprised in the first layer comprises a resistive heater arranged to heat the internal volume 110 to 1700°C to 2700°C. Carrier gas comprising argon and hydrogen is transported through the source material 120 and thereafter to the seed crystal 180, thereby transporting any silicon carbide sublimated from the source material 120.

[0048] For a SiC source material, a temperature of 2600°C is expected to result in stoichiometric sublimation. An advantage of a stoichiometric reaction is a reduced need for hydrogen in the carrier gas 130 to remove carbon from the source material 120.

[0049] Preferably, the carrier gas 130 comprises a gas with high mass and low diffusivity, such as Ar. Preferably the carrier gas has a low thermal conductivity, which allows the gas cloud created at the source material 120 to maintain temperature until it is transported by the carrier to the seed crystal and cooled by the "contact" with the crystal surface. If the temperature is not maintained then homogeneous nucleation may occur, homogeneous nucleation here relating to growth in the gas phase where the sublimed species will start recombining to form microcrystals.

[0050] In some examples, the growth chamber 100 comprises a computer (not shown) arranged to control the heating device and / or the seed crystal holder 170. In some examples, said computer is comprised in a programmable logic controller and / or a hardware controller for automation of the growth chamber 100.

[0051] It is to be understood that utilizing one heater may be a challenge as the source material 120 will heat the seed crystal through radiation, typically making it necessary to cool the seed crystal 180. A second heater may provide heat around the edge of the seed crystal holder 170 to keep it hotter than the centre of the seed crystal 180, thus reducing growth on the seed crystal holder 170 itself. The second heater may be a second resistive heater. Preferably, the face of the source material 120 directed towards the seed crystal 180 has a smaller diameter than the diameter of the crystal holder 170, and the second heater controls the radial gradient of the seed crystal. In some examples, a third heater is arranged behind the seed crystal 180. In some of these examples, the third heater is a pancake heater. In some example, the computer is arranged to control a plurality of heaters. For example, the computer controls two resistive heaters to maintain a thermal gradient in the internal volume of the growth chamber 100.

[0052] In some examples, the internal volume 110 comprises a region that is substantially cylinder shaped. In some examples, the source material 120 is arranged opposite to the crystal holder 170. In some of these examples, the crystal holder 170 and / or the seed crystal 180 has a diameter that is larger than the diameter of the source material 120 facing the crystal holder 170. If the seed crystal 180 is significantly larger than the source material 120 then heat from the source material 120 may heat the central region of the seed crystal 180 significantly more than the edges of the seed crystal 180.

[0053] In some examples, the growth chamber comprises a heater for the perimeter of the crystal holder 170 and / or the perimeter of the seed crystal 180. In some examples, the growth chamber 100 comprises openings (not shown) on the insulation 160 in proximity to seed crystal holder 170. Reduced insulation 160 coverage may be utilized to bring the seed crystal 170 to a desired temperature, and may allow radial gradients in the growth chamber 100 to be adjusted by the temperature of the source material 120, and the seed crystal holder heater around the perimeter. In some examples, the growth chamber 100 comprises a pancake heater 151 behind the seed crystal holder. In some of these examples, the pancake heater 151 is arranged between the seed crystal holder 170 and the insulation 160.

[0054] In some examples, the growth chamber 100 is arranged to, during crystal growth, allow keeping the side of the source material 120 furthest from the crystal holder 170 at a lower temperature than the side of the source material 120 closest from the crystal holder 170. Said temperature difference may prevent condensation and crystal growth on the source material 120. It is to be understood that “the side of the source material 120 closest from the crystal holder 170” is the side from which material from the source material is typically transported to the crystal being grown.

[0055] In some examples, the growth chamber 100 is arranged to, during crystal growth, transfer heat from the side of the source material 120 furthest from the crystal holder 170 to the carrier gas 130, thereby facilitating that the side of the source material 120 closest from the crystal holder 170 is kept at a higher temperature.

[0056] It is to be understood that in order to provide a high crystal growth rate and avoid etching the seed crystal 180 it is of great importance to adequately utilize heaters to control the source material 120 and seed crystal 180 temperature, as well as the thermal gradients in the growth chamber 100. In some examples, the growth chamber 100 is arranged to, during crystal growth, consume source material at a higher rate at the side of the source material 120 furthest from the crystal holder 170 compared to the rate at the side of the source material 120 closest from the crystal holder 170. In some of these examples, the growth chamber 100 comprises an external port (not shown) arranged to allow source material to be added to the side of the source material 120 closest from the crystal holder 170. In some of these examples, the source material 120 is added as a powder.

[0057] The growth chamber 100 may be arranged to grow crystals of SiC, aluminium nitride AIN, gallium nitride, GaN, gallium oxide, Ga2Os, and / or zinc oxide, ZnO.

[0058] It is to be understood that pressure range, temperature range, carrier gases and several additional parameters for performing crystal growth with the growth chamber 100 are dependent on the type of crystal being grown. Examples herein predominantly describe growing SiC crystals, however, the growth chamber, system and method are not limited to SiC crystal growth, and the examples also relate to corresponding examples for other types of crystals.

[0059] In some examples, the growth chamber 100 is arranged to grow crystals with a diameter of at least 200 mm, or at least 300 mm. In some of these examples, the growth chamber 100 is arranged to grow silicon carbide crystals with a diameter of at least 200 mm, or at least 300 mm.

[0060] In some examples, the source material 120 comprises SiC, AIN, gallium nitride, GaN, gallium oxide, Ga2Os, and / or zinc oxide, ZnO.

[0061] In some examples, the source material 120 comprises at least 50 wt% of SiC, AIN, gallium nitride, GaN, gallium oxide, Ga2Os, and / or zinc oxide, ZnO.

[0062] In some examples, the source material 120 comprises vanadium, wherein vanadium is arranged to dope the grown crystal.

[0063] In some examples, the source material 120 comprises sintered source material and / or a plurality of particles.

[0064] It is to be understood that the level of sintering or the particle size of the source material 120 is important. A compact sintered source will have a fairly decent thermal conductivity which will benefit the way any spreads in the source material 120. For some embodiments, the best efficiency is achieved when the thermal conductivity of the source is high as it will allow heat spreading through the source. In some examples, the source material 120 comprises a plurality of particles with an average diameter of 10-400 pm. In some of these examples, the average diameter is 20-200 pm, or 40- 100 pm.

[0065] In some examples, the source material 120 comprises sintered source material formed by a plurality of particles with an average diameter of 10-4000 pm. In some of these examples, the average diameter is 20-2000 pm, 40-1000 pm, 100-600 pm, or 200-400 pm.

[0066] In some examples, the growth chamber 100 comprises a holder (not shown) for said source material 120. In some of these examples, the growth chamber 100 and holder upon receiving a corresponding source material 120 creates two volumes separated by the source material 120, such that the flow paths for carrier gas 130 has to pass through the source material 120 to move between said two volumes. Typically, the two volumes compartments relate to a first volume where the carrier gas 130 enters and a second volume between the source material 120 and the seed crystal 180.

[0067] In some examples, the growth chamber 100 comprises the holder for said source material 120, wherein the carrier gas 130 flows at, or through, the source material 120 comprised in said holder.

[0068] It is to be understood that, even though the seed crystal 180 and the source material 120 are needed for crystal growth, the growth chamber 100 is typically not manufactured or sold with the seed crystal 180 or the source material 120 installed. Instead, the seed crystal 180 and the source material 120 may be considered consumables that will be replaced multiple times over the lifespan of a growth chamber, much like paper and ink cartridges for a printer. Typically, the seed crystal 180 and the source material 120 are replaced each crystal growth run.

[0069] It is to be understood that “sublimating the source material 120” releases and forms a plurality of species, such as Si, Si2C and SiC2, by providing heat to the source material 120.

[0070] In some examples, the flow of carrier gas 130 comprises at least one inert gas and hydrogen. If the source material is SiC then the sublimation is typically not stoichiometric and carbon is left behind in the source material, this may be mitigated by introducing hydrogen in the carrier gas. Hydrogen may readily react with excess carbon to form hydrocarbons, which keeps the source clean and also increases the growth rate which normally is carbon limited, this benefit does not occur in Si-limited CVD.

[0071] In some examples, the flow of carrier gas 130 comprises and / or consists of argon and hydrogen. In some of examples, the flow of carrier gas 130 comprises 0.5-10 SLM argon and 0-10 SLM hydrogen. In some of these examples, the flow of carrier gas 130 comprises 1-6 SLM, or 2-4 SLM argon. In some of these examples, the flow of carrier gas 130 comprises 0.5- 6 SLM, or 1-4 SLM hydrogen.

[0072] In some examples, the growth chamber 100 is arranged to have a flow of carrier gas 130 corresponding to a volumetric exchange rate in the internal volume 110 in a range of 0.1 min-1to 2 min-1. In some of these examples, the volumetric exchange rate in the internal volume 110 is in the range of 0.2 min-1to 1 min-1, or 0.4 min-1to 0.8 min-1.

[0073] In some examples, the flow of carrier gas 130 has a flow rate in the range of 0.1 to 10 m / s in the internal volume 110 in the growth chamber 100 at the source material 120 where carrier gas 130 exits the source material 120. In some of these examples, the flow of carrier gas 130 has a flow rate in the range of 0.2 to 5 m / s, 0.4 to 2 m / s, or 0.6 to 1 m / s.

[0074] It is to be understood that said flow rate of carrier gas 130 relates to an average gas flow.

[0075] In some examples, the flow of carrier gas 130 comprises argon and hydrogen in an Ar:H2 ratio within the range of 5-95%. In some of these examples, the flow of carrier gas 130 comprises argon and hydrogen in an Ar:H2 ratio within the range of 10-90%, 15-80%, 25-75%, or 30-60%.

[0076] For an example scenario, the internal volume 110 is evacuated prior to starting the growth process, and thereafter Ar gas is introduced and the pressure controlled to between 20 kPa to 150 kPa absolute. Several other parameters for performing the crystal growth are typically determined based on the pressure, such as the velocity of the gas, gas density, the etch rate at the seed crystal, the spread of the “cloud” of sublimed species from the source material, and the homogeneous nucleation. Thus, pressure regulation is important for reliable performance of the crystal growth. Typically, there is no pressure difference or a minor pressure difference between the inlet and outlet. The average flow through the growth chamber is quite small and slow, so no major pressure differences are required. The pressure in the internal volume 110 and the pressure difference between inlet and outlet may be selected based on the expected partial pressure of the sublimed species, to make sure that the whole gas “cloud” of released source material is guided in a controlled manner. Precise pressure control may be utilized to control the growth front of the crystal and to reduce homogeneous nucleation at high rates.

[0077] In some examples, wherein a SiC crystal is being grown, the source material 120 comprises SiC particles mixed with a plastic, whereby the stoichiometry of the source material 120 is tuned towards having more carbon.

[0078] In some examples, the carrier gas comprises one or more dopants, or precursors thereof, for the crystal being grown. In some examples, the carrier gas comprises nitrogen. N2 is a n-type dopant at least for SiC and it is essential in order to produce crystals for power devices, such as power electronics used in electric vehicles and charging stations. In some examples, the carrier gas comprises vapours of Tri-Methyl-Aluminium, TMA, vanadozine, and / or vanadium chloride. The aluminium comprised in TMA is a p-type dopant at least for SiC.

[0079] It is to be understood that for growing doped crystals the carrier gas and / or the source material may comprise dopants or precursors thereof.

[0080] In some examples, wherein an AIN crystal is being grown, the carrier gas comprises nitrogen.

[0081] In some examples, wherein a GaN crystal is being grown, the carrier gas comprises chlorine and / or HCI. These species may be useful due to the low vapor pressure of gallium.

[0082] In some examples, wherein a ZnO crystal is being grown, the carrier gas comprises oxygen. In some of these examples, the seed crystal holder 170 comprises quartz, or another high temperature oxide with low vapor pressure. In some of these examples, the crystal growth chamber 100 comprising at least one heating device comprising Molybdenum disilicide, MoSi2.

[0083] It is to be understood that raising the temperature of at least part of the source material 120 may be performed in many ways based on some sensor data relating to the source material or the crystal being grown. It is further to be understood that the position on the source material being heated may impact the distribution of crystal growth at the seed crystal, such as increased crystal growth at a position of the seed crystal that is closest to the part being heated.

[0084] In some examples, the growth chamber 100 comprises a resistive heater and / or an induction heater arranged to heat the seed crystal 180 and / or the source material 120.

[0085] In some examples, the heating device 150 comprises a resistive heater and / or an induction heater. In some examples, growth chamber 100 comprises a set of heating devices comprising one or more heating devices 150. In some examples, the set of heating devices comprises a heating device 150 arranged to uniformly heat the internal volume, and a heating device 150 arranged to provide heat to the internal volume to generate a temperature gradient between the seed crystal 180 and the source material 120.

[0086] It is to be understood that the temperature gradients between the seed crystal 180 and the source material 120 may divided into axial gradients and radial gradients in relation to a path between the two, such as a line between the centre of the seed crystal 180 and the source material 120. In some examples, one or more heating devices 150 are arranged to, predominantly, generate a radial gradient. In some examples, one or more heating devices 150 are arranged to, predominantly, generate an axial gradient.

[0087] In some examples, the growth chamber comprises at least two heating devices arranged to create a temperature gradient between the seed crystal 180 and the source material 120. In some of these examples, the growth chamber comprises at least three, or at least four heating devices arranged to create a temperature gradient between the seed crystal 180 and the source material 120.

[0088] It is to be understood that the expression “create a temperature gradient between the seed crystal 180 and the source material 120” relates to creating or maintaining said temperature gradient during crystal growth.

[0089] In some examples, the growth chamber 100 comprises insulation. In some of these examples, the insulation 160 is arranged outside the first layer comprising the heater device 150. In some examples, the first layer comprising at least one heater device 150 is arranged between the internal volume of the growth chamber 100 and the second layer comprising insulation 160. In some of these examples, the growth chamber 100 comprises a set of heaters comprising a plurality of heaters arranged to maintain a temperature gradient in the internal volume during crystal growth. Adding insulation to the outside of the growth chamber 100 allows for saves a lot of energy which is a major cost in crystal growth.

[0090] In some examples, the growth chamber 100 is arranged to heat the seed crystal 180 and / or the source material 120 to a temperature in the range of 1700-2700°C. In some of these examples, the growth chamber 100 is arranged to heat the seed crystal 180 and / or the source material 120 to a temperature in the range of 1800-2500°C, 2000-2300°C, or 2100-2200°C.

[0091] In some examples, the growth chamber 100 is arranged to heat the seed crystal 180 and the source material 120 to substantially the same temperature. In some of these examples, the temperature difference between the seed crystal 180 and the source material 120 is, during crystal growth, at most 200°C. In some of these examples, said temperature difference is at most 150°C, at most 100°C, at most 70°C, at most 50°C, at most 40°C, at most 30°C, at most 20°C, or at most 10°C. In some of these examples, the temperature difference between the seed crystal 180 and the source material 120 is, during crystal growth, at least 10°C.

[0092] Preferably for SiC the temperature difference is in the range of 50 to 100°C.

[0093] It is to be understood that the temperature of the seed crystal may be increased to increase growth rate. A high seed crystal temperature may add risks as it results in a higher etch rate. This can be reduced by a higher growth pressure. The crystal shape typically is essentially convex to cause a higher growth rate in the centre than the edge. This may be done to reduce poor crystalline quality. Without proper control of heaters and gas flows, the edge may consequently be hotter than the centre which may lead to an undesired increased etch rate.

[0094] In some examples, the growth chamber 100 is arranged to produce semi insulating SiC that is grown using extremely high purity, wherein the carrier gas is purified to remove nitrogen, and wherein the source material is generated through a gas fed process utilizing silane and ethylene. For example, this may be performed in-situ by allowing said gases to react on a grid or a plurality of short cylinders of graphite and then sublime the SiC from the cylinder walls or grid.

[0095] In some examples, the seed crystal holder 170 is arranged to rotate the seed crystal 180 and / or lift the seed crystal 180. In some of these examples, the seed crystal holder 170 is in communication with a computer (not shown) arranged to control the movement of said seed crystal 180.

[0096] In some examples, the growth chamber 100 comprises a set of sensors (not shown) arranged to measure and / or capture an image of at least one of

[0097] - temperature in the internal volume 110,

[0098] - pressure in the internal volume 110,

[0099] - temperature of the source material 120,

[0100] - temperature of the crystal holder 170 and / or the crystal being grown,

[0101] - temperature of carrier gas 130 entering and / or exiting the internal volume 110,

[0102] - the surface of the crystal holder 170 and / or the crystal being grown,

[0103] - the surface of the source material 120, and

[0104] - composition of carrier gas 130 entering and / or exiting the internal volume 110.

[0105] It is to be understood that the composition of the carrier gas 130 exiting the internal volume 110 relates to both the carrier gas 130 and any species transported out of the internal volume 110, such as silicon dicarbide, SiC2.

[0106] In some examples, the growth chamber 100 comprises at least one optical port (not shown) arranged to allow, from outside the internal volume 110, detection of electromagnetic radiation from within the internal volume 110 of the growth chamber 100, such as light in the visible or infrared spectrum. In some of these examples, at least one of the set of sensors is arranged to measure a value and / or capture an image through said at least one optical port. In some of these examples, the seed crystal 180 and / or the source material 120 is in the field of view of said optical port. In some of these examples, at least one of the set of sensors is arranged to measure a value and / or capture an image of the seed crystal 180 and / or the source material 120. In some examples, the growth chamber 100 comprises said set of sensors and a computer,

[0107] - wherein the computer controls the set of sensors to measure the temperature of the crystal holder 170 and / or the crystal being grown, measures a value and / or captures an image of the surface of the crystal holder 170 and / or the crystal being grown, or measures a value and / or captures an image of the source material 120; and

[0108] - wherein the computer is arranged to control the at least one heating device 150, the crystal holder 170, and / or control flows based on said measurement by the set of sensors. In some of these examples, the growth chamber comprises at least one actuator arranged to control gas flow, and wherein the computer is arranged to control gas flow by controlling said at least one actuator.

[0109] In some of these examples, the computer is arranged to measure the temperature of the crystal holder 170 and / or the crystal being grown, compare measured values with a target temperature, and control the temperature of the crystal holder 170 and / or the crystal being grown utilizing a heater based on said comparison.

[0110] In some examples, the computer is arranged to measure the crystal being grown, determine a growth rate of the crystal, compare the determined growth rate with a target growth rate, and control flow of carrier gas and / or curtain gas flow based on said comparison.

[0111] In some examples, the computer is arranged to measure the gas composition in the internal volume 110 the growth chamber 100, compare the measured composition values with a target composition, and control flow of carrier gas and / or the hydrogen content of the carrier gas based on said comparison.

[0112] In some examples, the growth chamber 100 comprises a set of sensors and a computer,

[0113] - wherein the set of sensors measures the temperature of the crystal holder 170 and / or the crystal being grown, or measures a value and / or captures an image of the surface of the crystal holder 170 and / or the crystal being grown, and

[0114] - wherein the computer is arranged to determine crystal growth rate, defects, polytypes, and / or facet development based on said measurement.

[0115] In some examples, the growth chamber 100 comprises a set of sensors and a computer,

[0116] - wherein the set of sensors measures the composition of carrier gas 130 exiting the internal volume 110, and

[0117] - wherein the computer is arranged to determine the ratio of hydrocarbons based on said measurement. It is to be understood that the expression “measures the composition of carrier gas 130” may relate to performing a measurement such that the measured data is indicative of the composition.

[0118] In some of these examples, the computer is arranged to control set of heating devices and / or the seed crystal holder 170 based on determined crystal growth rate, defects, polytypes, facet development, and / or the ratio of hydrocarbons. Thus, impacting said metrics by controlling the temperature and temperature gradients in the internal volume.

[0119] In some of these examples, the computer is arranged to control set of heating devices and / or the seed crystal holder 170 based on measured values and / or capture images of the crystal holder 170 and / or the source material 120 via the optical port.

[0120] In some examples, the growth chamber 100 is arranged to adjust the hydrogen content of the carrier gas 130, and the set of sensors is arranged to measure hydrocarbons in the internal volume 110 of the growth chamber 100, wherein the computer is arranged to

[0121] - measure hydrocarbons in the internal volume 110 the growth chamber 100,

[0122] - compare the measured values with a target value for hydrocarbons, and

[0123] - control the hydrogen content of the carrier gas 130 and / or the flow rate of the carrier gas 130 based on said comparison.

[0124] In some examples, the set of sensors comprise a Fourier transform infrared, FTIR, sensor. It is to be understood that measurement values from an FTIR sensor arranged to measure the gas in the internal volume 110 may be utilized to determine molecules in gas inside the internal volume 110. In some of these examples, the computer is arranged to compare the chemical composition in the gas against a predetermined set of criteria, and present a warning and / or perform control the growth chamber 100 based on said comparison. In some of these examples, the computer is arranged to control the hydrogen content of the carrier gas 130 and / or the flow rate of the carrier gas 130 based on said comparison.

[0125] In some examples, the set of sensors comprise an optical sensor arranged to detect the optical spectrum emitted from the source material 120 and / or the crystal being grown. In some of these examples, the computer is arranged to determine the chemical composition and / or structural properties of the source material 120 and / or the crystal being grown. In some of these examples, the computer is arranged to compare the chemical composition and / or structural properties of the source material 120 and / or the crystal being grown against a predetermined set of criteria, and present a warning and / or perform control the growth chamber 100 based on said comparison. In some of these examples, the computer is arranged to control the hydrogen content of the carrier gas 130 and / or the flow rate of the carrier gas 130 based on said comparison.

[0126] In some examples, the set of sensors comprise an optical sensor arranged to measure in the infrared, visible, and / or UV spectral ranges inside the internal volume 110 of the growth chamber. It is to be understood that, at least for measurements, “inside the internal volume 110” includes the source material 120, the crystal being grown and other parts inside or in contact with the internal volume 110.

[0127] In some examples, the set of sensors comprises a weighing scale arranged to measure the weight of the source material 120 and / or the weight of the holder of said source material. In some of these examples, the computer is arranged to determine the depletion of the source material 120 based on the measured weight. In some of these examples, the computer is arranged to control the hydrogen content of the carrier gas 130 and / or the flow rate of the carrier gas 130 based on said determined depletion of the source material 120.

[0128] In some examples, the set of sensors comprises a Michelson interferometer arranged to measure the surface of the crystal being grown. In some of these examples, the computer is arranged to determine the growth rate of the crystal based on the measurement. In some of these examples, the computer is arranged to measure and determine the growth rate for two or more positions on the surface of the crystal being grown.

[0129] In some examples, the set of sensors comprises an emissometer arranged to measure the emissivity of the surface of the crystal being grown. In some of these examples, the computer is arranged to determine the surface geometry of the crystal being grown based on the measured emissivity. In some of these examples, the computer is arranged to control the hydrogen content of the carrier gas 130 and / or the flow rate of the carrier gas 130 based on said determined surface geometry of the crystal being grown.

[0130] In some examples, the set of sensors comprises an emissometer arranged to measure the emissivity of the surface of the crystal being grown, and the set of sensors comprises a temperature measuring device arranged to determine the temperature of the surface of the crystal being grown. In some of these examples, the computer is arranged to determine the surface geometry of the crystal being grown based on the measured emissivity and the measured temperature.

[0131] In some examples, the growth chamber comprises at least one actuator arranged to adjust the curtain gas flow in the internal volume. In some of these examples, the computer is arranged to control the at least one actuator based on determined crystal growth rate, defects, polytypes, facet development, and / or the ratio of hydrocarbons; or to determine crystal growth rate, defects, polytypes, facet development, and / or the ratio of hydrocarbons.

[0132] In some of these examples, the growth chamber 100 is arranged to adjust a first and / or a second curtain gas flow in the internal volume 110, and the set of sensors is arranged to measure crystal growth rate, wherein the computer is arranged to

[0133] - measure the crystal being grown,

[0134] - determine a growth rate of the crystal,

[0135] - compare the determined growth rate with a target growth rate, and

[0136] - control said curtain gas flow(s) in the internal volume 110 based on said comparison.

[0137] It is to be understood that the computer may be arranged to control carrier gas flow 130 and / or curtain gas flow based on any combination of the determined properties in the previous examples.

[0138] Fig. 2 shows a cross section of an example growth chamber for crystal growth utilizing gas curtains. The growth chamber 100 may be a growth chamber as described in fig. 1 further arranged to provide a curtain gas flow 131 comprising argon through the internal volume 110. The curtain gas flow 131 is arranged to provide a gas curtain for the flow of carrier gas 130 exiting the source material 120. Typically, the curtain gas flow 131 is configured to force the flow of carrier gas 130 exiting the source material 120 along a flow path towards the seed crystal 180, such that more of the material carried from the source material 120 by the carrier gas 130 is brought into proximity of the seed crystal 180. This further reduces parasitic deposition on the walls. In some examples, the curtain gas flow 131 comprises argon, krypton, xenon, helium, and / or neon. It is to be understood that the impact of utilizing curtain gas flow 120 is significantly amplified by operating the growth chamber 100 under relatively high pressures compared to typical physical vapor transport, PVT, systems.

[0139] It is to be understood that the expression “brought into proximity" relates to material carried from the source material 120 by the carrier gas to the vicinity of the seed crystal surface, close enough for diffusion to act as the main gas transport mechanism. Typically, the carrier gas 130 will not bring the carried material into direct contact with the seed crystal surface, as the likely scenario is that there is a stagnant layer of non-descript gas that exists closest to the surface and the incoming specie diffuse through this onto the surface of the crystal being grown. Diffusion is quick at the operating temperatures and pressures used so a good measure of the stagnant layer thickness relates to the diffusion length and forced convection velocity parallel to the surface of the crystal being grown. For a likelihood of a molecule reaching the surface being 50%, the efficiency of transport is 50%. In fig. 2 the curtain gas flow 131 is depicted as travelling in parallel with the flow of carrier gas 130 passing through the source material 120, such that in an example with a cylinder symmetric internal volume 110, the flow of carrier gas 130 passing through the source material 120 forms a cylinder that is surrounded by a tube of curtain gas flow 131 pushing the flow of carrier gas 130 transporting material from the source material 120 towards the centreline and towards the seed crystal 180. It is to be understood that the curtain gas flow 131 may enter the internal volume 110 in other ways than depicted in fig. 2, such as being entering at or slightly downstream of the side of the source material 120 where the flow of carrier gas 130 exits.

[0140] In some examples, growth chamber 100 is arranged to generate at least two curtain gas flows. In some of these examples, an inner curtain gas flow is parallel to the carrier gas flow and forms a "tube" surrounding the carrier gas flow, and a second curtain gas flow, typically called the focus flow, comes in at an angle and is arranged to further push the carrier gas flow towards its centre line. It is to be understood that these curtain gas flows may be adapted to obtain different flow profiles for growing a crystal. The example growth chamber 100 shown in fig. 2 and fig. 3 has a rotationally symmetric disc shaped source material 120 and the curtain gas flow 131 enters the internal volume 110 via the ring-shaped gap between the source material 120 and the inner wall of the growth chamber 100 formed by the heating device 150.

[0141] Fig. 3 illustrates gas flow in an example growth chamber with gas curtains. The growth chamber 100 may be a growth chamber as described in fig. 2. Fig. 3 shows an example schematic gas boundary 135 between regions predominantly containing carrier gas and curtain gas. The depicted gas boundary 135 aims to illustrate how the curtain gas 131 may impact the flow of carrier gas 130, and the shape of the example gas boundary 135 may differ from real world measurements.

[0142] It is to be understood that the flow of gases through the internal volume 110 may be altered by the flow of the carrier gas 130 passing through the source material 120, the flow of the curtain gas flow 131 , and / or the composition of the curtain gas flow 131. Typically, the purpose of utilizing curtain gas flow 131 is to improve control over the carrier gas 130 after passing through the source material 120, so as to obtain an increased growth rate and / or a higher quality crystal growth.

[0143] In some examples, at least one curtain gas flow 131 is angled towards a centreline of the flow of carrier gas 130, thereby concentrating the flow of carrier gas 130 to said centreline.

[0144] In the example shown in fig. 2 and fig. 3 the curtain gas flow 131 is depicted as entering the internal volume 110 at the edges of the source material 120. In some examples, the curtain gas flow 131 is introduced into the internal 110 volume via one or more channel, each with an outlet (not shown) arranged inside the internal volume 110.

[0145] In some examples, the curtain gas flow 131 is introduced into the internal volume 110 in a rotationally symmetric fashion. In some of these examples, the curtain gas flow 131 is released into the internal volume 110 from a continuous outlet arranged in the rotationally symmetric fashion, such as depicted in fig. 2 and fig. 3.

[0146] In some examples, at least one curtain gas flow 131 comprises and / or consists of 0.5-10 SLM argon. In some of these examples, at least one curtain gas flow 131 comprises and / or consists of 1-6 SLM, or 2-4 SLM argon.

[0147] Fig. 4 shows an example system for crystal growth, the system 200 comprises a growth chamber 100 for crystal growth, a computer 210, and a set of gas flow control devices 221 ,222. The growth chamber 100 may be a growth chamber according to any of the growth chambers 100 described in relation to fig. 1 and fig. 2. The computer 210 is connected to the growth chamber and the set of gas flow control devices 221,222, and is arranged to control the set of flow control devices to control the carrier gas flow through the growth chamber 100.

[0148] In some examples, the set of gas flow control devices 221,222 comprises an inlet mass flow controller and an outlet gas pump. In some examples, the set of gas flow control devices 221,222 comprise a mass flow controller and / or a gas pump.

[0149] It is to be understood that the set of gas flow control devices 221 ,222 in fig. 4 may be a set of valves controlling the flow of high pressure gases. Typically, utilizing a pump or compressor makes it easier to reclaim the exhaust gases from the growth chamber 100. In some examples, gas flow control device(s) 221 at the inlet is arranged to control the ratio of H2 to Ar, or other heavy carrier gas. In some examples, the gas flow control device(s) at the inlet is arranged to remove any hydrocarbons.

[0150] In some examples, the set of gas flow control devices 221 ,222 comprises a gas inlet valve and an outlet valve.

[0151] It is to be understood that the set of gas flow control devices 221 ,222 and the connections between themselves and the growth chamber 100 may comprise one or more of the plurality of standard components comprised in a pipeline, and are not limited to pumps, valves and mass flow controllers.

[0152] In some examples, the computer 210 is connected to the heater device and / or the seed crystal holder comprised in the growth chamber 100, and is arranged to control the heater device and / or the seed crystal holder. In some examples, the system 200 further comprises a gas recovery device 230 arranged to purify and / or recover the carrier gas and / or material transported by said carrier gas that has exited the growth chamber 100. In some of these examples, the gas recovery device 230 is connected to the gas inlet pump 221 by a gas tube 227, whereby recovered gas may be fed back into the growth chamber 100.

[0153] In some examples, the set of gas flow control devices are arranged to control the carrier gas, the curtain gas, the exhaust gases from the growth chamber 100, and / or the recovered gas.

[0154] For example, sublimation of SiC occurs at approximately 1800°C in an inert and low pressure environment. By utilizing a heating device locally at the source material 120, the source material 120 may be heated to a temperature where significant amounts of sublimation occurs. Preferably, the carrier gas 130 transports the material released from the source material 120 away from the surface of the source material 120 at a flow rate and concentration of released material that allows for an even and high crystal growth at the seed crystal 180.

[0155] In some examples, the system 200 comprises a memory storage 211 comprised in the computer 210 and / or is connected to the computer 210, wherein the memory storage 211 is arranged to comprise a computer program arranged to, upon execution on the computer, control the system to grow crystals.

[0156] In some examples, the system 200 comprise a set of analytical equipment (not shown) comprising at least one pyrometer, thickness measurement device, camera, thermal imaging camera, optical spectrometer; or a device for quantitative mineral analysis, Fourier transform infrared spectroscopy, X-ray diffraction, or emissivity measurement arranged to measure the growth chamber 100 and / or the gas entering and / or exiting the growth chamber 100.

[0157] Fig. 4 depicts the parts of the system 200 as separate parts connected by communication or gas tubes 225,226, however, any of said parts may be arranged at or comprised in the growth chamber 100. It is to be understood that the growth chamber 100 may comprise any or all of the parts of the system 200. In some examples, the system 200 is comprised in one unit.

[0158] In some examples, the system 200 is arranged to maintain a gas pressure in the range of 20 to 150 kPa inside the internal volume of the growth chamber 100 during crystal growth. In some of these examples, the system 200 is arranged to maintain a gas pressure in the range of 25 to 200 kPa, 15 to 400 kPa, or 10 to 1000 kPa.

[0159] Fig. 5 shows a method for growing a crystal with a growth chamber. The method comprises the steps of

[0160] - providing 310 a seed crystal into an internal volume of said growth chamber, wherein said crystal is arranged to grow at said seed crystal;

[0161] - providing 320 a source material comprising material for growing said crystal at said seed crystal into said internal volume;

[0162] - flowing 340 carrier gas to the source material and thereafter to the seed crystal; and

[0163] - heating 350 the internal volume and generating a temperature gradient, thereby releasing material from the source material and allowing the carrier gas flow to transport said released material to the seed crystal, whereby the crystal is grown at the seed crystal.

[0164] It is to be understood that “generating a temperature gradient” relates to a temperature difference between the source material and the seed crystal.

[0165] In some examples, providing 320 a source material comprising material for growing said crystal comprises providing said source material in a holder for source material; and flowing 340 carrier gas to the source material comprises flowing 340 carrier gas to, and / or through, said source material comprised in said holder for source material.

[0166] It is to be understood that typically, the source material is held in place by a holder, as in a structure keeping the bulk of the source material in place, allowing carrier gas to flow at or through the source material in the holder, and allowing heating the source material at or in the holder.

[0167] In some examples, heating 350 the internal volume is performed with a heating device comprised in the growth chamber. In some of these examples, the heating device comprises a resistive heater and / or an induction heater.

[0168] In some examples, heating 350 the internal volume and generating the temperature gradient, comprises generating a temperature gradient within the source material, wherein the temperature of the side of the source material facing the seed crystal is higher than the side opposite side. Said side facing the seed crystal corresponds to the surface where the carrier gas exits the source material, and said opposite side relates to the surface where the carrier gas enters the source material. Preferably, the side of the source material facing the seed crystal is kept at high enough temperature to keep crystal growth at a minimum.

[0169] In some examples, the method 300 comprises measuring 330 a state of the internal volume utilizing a set of sensors, and wherein flowing 340 carrier gas and / or heating 350 based on said measured state.

[0170] In some of these examples, the set of sensors measures the state comprising the temperature of the crystal holder 170 and / or the crystal being grown, and / or measures a value and / or captures an image of the surface of the crystal holder 170 and / or the crystal being grown. In some examples, the state of the internal volume is indicative of crystal growth rate, defects, polytypes, and / or facet development.

[0171] In some examples, the set of sensors measures the state comprising the composition of carrier gas 130 exiting the internal volume 110. In some examples, the state of the internal volume is indicative of the ratio of hydrocarbons in the carrier gas exiting the growth chamber.

[0172] In some examples, the method comprises maintaining a gas pressure in the range of 20 to 150 kPa inside the internal volume while heating 350 to cause the source material to sublimate.

[0173] In some of these examples, the method comprises maintaining a gas pressure in the range of 25 to 200 kPa, 15 to 400 kPa, or 10 to 1000 kPa.

[0174] Returning to fig. 2 and fig. 3 an example scenario of utilizing the growth chamber for SiC single crystal growth will be described.

[0175] The source material is weighed and poured into a cup with small holes in the bottom to allow the carrier gas to flow through the cup, the cup acting as a holder for the source material. The size of the holes are smaller than the SiC particles that are loaded. The size of the particles that are loaded match the desired porosity and hence thermal conductivity after the sintering process. The sintering should generate as high thermal conductivity as possible, yet still allow a flow of gases through the porous source. The sintering may be done in-situ or externally. The growth chamber is loaded with the cup containing the source material and the lower chamber hatch is closed. The source distance to the top edge of the chamber is checked and adjusted with a lifting mechanism. A seed crystal is prepared with an optional backside coating. The seed is attached or otherwise fixed to the seed holder which is attached to the upper hatch via a graphite rod. The height of the seed is checked to the bottom of the hatch and adjusted if necessary with the lifting mechanism. The source to seed distance is preferably between 20 - 200 mm. The example source material is 120 mm in diameter and 200 mm in height, and the seed holder is 270 mm in diameter. The internal volume of the example growth chamber is 10 dm3. The growth chamber comprises a heating device encircling the source material, and a heating device encircling the seed holder.

[0176] The upper hatch is closed and rotation of the source and seed are started. The chamber is carefully evacuated down to a vacuum below 1 mbar. With the pump still running, the throttle valve set to control mode maintaining the desired growth pressure (normally between 20 - 800 mbar), and a small flow of Ar is introduced into the chamber through the cup and the source material. The carrier gas flows are gradually increased until the desired flow is reached. In this example scenario there is no curtain gas flow. A carrier gas flow of 1 - 5 SLM is normally enough. The flow may be blended with 0.5 - 2 SLM of hydrogen depending on the source temperature. Heating may be started while the flows and pressure is ramping up. The heating should not be too fast, and the entire temperature ramp up to 2000 °C should take around 60 - 120 minutes. A typical growth temperature is around 2000 °C. The heating should also ensure that the seed temperature is uniform and at the same temperature as the source or slightly lower. This can be achieved by controlling the heating devices individually around the source material and seed holder. The source temperature should gradually be increased and the growth rate and quality monitored via the viewports. The shape of the crystal can be controlled by the curtain gas flows, carrier flow, pressure, and radial gradient. If a pancake heater is mounted behind the seed crystal, the temperature may be adjusted with this to increase the temperature of the centre of the crystal and the heater around the crystal holder can adjust the edge temperature. The final temperature of the source should be somewhere between 2000 - 2700 °C. Depending on the flow settings, a growth rate of 1 mm / h is reached with the source at 2500 °C and the seed at 2000 °C.

Claims

CLAIMS1. A method for growing a crystal in a growth chamber, the method (300) comprises- providing (310) a seed crystal (180) into an internal volume (110) of said growth chamber (100), wherein said crystal is arranged to grow at said seed crystal (180);- providing (320) a source material (120) comprising material for growing said crystal at said seed crystal (180) into said internal volume (110), wherein the source material (120) is gas-permeable;- flowing (340) carrier gas (130) through the source material (120) and thereafter to the seed crystal (180); and- heating (350) the internal volume and generating a temperature gradient, thereby releasing material from the source material (120) and allowing the carrier gas flow (130) to transport said released material to the seed crystal (180), whereby the crystal is grown at the seed crystal (180).

2. The method according to claim 1, measuring (330) a state of the internal volume through an optical port utilizing a set of sensors, and wherein flowing (340) carrier gas and / or heating (350) based on said measured state.

3. The method according to any preceding claim, wherein the crystal to be grown at the seed crystal (180) is a crystal of silicon carbide, SiC, aluminium nitride, AIN, gallium nitride, GaN, gallium oxide, GajOs, and / or zinc oxide, ZnO, and wherein the source material (120) comprises SiC, AIN, GaN, GajOs, and / or ZnO.

4. The method according to any preceding claim, wherein the seed crystal (180) and the source material (120) are heated to the range of 1700-2700°C.

5. The method according to any preceding claim, wherein heating (350) is performed utilizing a resistive heater and / or an induction heater.

6. The method according to any preceding claim, wherein heating (350) utilizes at least a first heating device (150) arranged to heat the source material (120) and a second heating device (150) arranged to heat the crystal holder (170) and / or the seed crystal (180).

7. The method according to any preceding claim, further comprising the step of providing a curtain gas flow (131) through the internal volume (110), wherein the curtain gas flow (131) is arranged to provide a gas curtain for the flow of carrier gas (130) exiting through the source material (120).

8. The method according to any preceding claim, wherein the carrier gas comprises argon and / or hydrogen.

9. The method according to any preceding claim, wherein crystal growth is performed with a gas pressure in the range of 20 to 150 kPa.

10. A growth chamber for growing a crystal, the growth chamber (100) comprises an internal volume (110), a seed crystal holder (170) arranged to hold a seed crystal (180) in said internal volume (110), and a heating device (150) arranged to heat the internal volume (110) to at least 1700°C; wherein the growth chamber (100) is arranged to receive the seed crystal (180) at the seed crystal holder (170), and to receive, in said internal volume (110), a gas-permeable source material (120) comprising material for growing said crystal, and to provide a flow of carrier gas (130) through the source material (120) and thereafter to the seed crystal (180); and wherein the heating device (150) is arranged to provide heat to the internal volume and generating a temperature gradient, thereby releasing material from the source material (120) and allowing the carrier gas flow (130) to transport said released material to the seed crystal (180), whereby the crystal is grown at the seed crystal (180).

11. The growth chamber according to claim 10, wherein the growth chamber (100) is arranged to provide a curtain gas flow (131) through the internal volume (110), wherein the curtain gas flow (131) is arranged to provide a gas curtain for the flow of carrier gas (130) exiting through the source material (120).

12. The growth chamber according to claim 10 or 11, wherein the growth chamber comprises a computer arranged to control the heating device (150), the seed crystal holder (170), the flow of carrier gas (130), and / or the flow of curtain gas (131).

13. A system for growing a crystal, the system (200) comprises a growth chamber (100) according to any of claims 10 to 12, a computer (210), and a set of gas flow control devices (221,222), wherein the computer (210) is connected to the growth chamber (100) and the set of gas flow control devices (221,222), and wherein the computer (210) is arranged to control the set gas flow control devices (221,222) to control the carrier gas flow through the growth chamber (100), and control the heating device (150) comprised in the growth chamber (100) to heat the source material (120).

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