WO2026008160A1

WO2026008160A1 - Cvd sic production reactor having a heating unit for heating a deposition surface of a sic growth substrate

Info

Publication number: WO2026008160A1
Application number: PCT/EP2024/069053
Authority: WO
Inventors: Friedrich Schaaff; Hilmar Richard Tiefel; Carlo BRZUSKA
Original assignee: Zadient Technologies SAS
Current assignee: Zadient Technologies SAS
Priority date: 2024-07-05
Filing date: 2024-07-05
Publication date: 2026-01-08
Anticipated expiration: 2027-01-05
Also published as: WO2026008496A1

Abstract

The present invention refers to a CVD SiC production reactor (850), wherein the CVD SiC production reactor (850) at least comprises a process chamber (856), a gas inlet unit (866) for feeding one feed-medium or multiple feed-mediums into a reaction space (966) of the process chamber (856) for providing a source medium, a gas outlet unit (216) for removing a vent gas mixture from the reaction space of the process chamber (856), a holding section (2824) for holding at least or exactly one SiC growth substrate (857) inside the reaction space (966) in a holding position, a heating unit (954) for heating a deposition surface (861) of the at least or exactly one SiC growth substrate, wherein the heating unit (954) is configured to heat the at least or exactly one SiC growth substrate (857) from at least multiple sides, in particularly along the entire circumference (2826) of the at least or exactly one SiC growth substrate (857).

Description

CVD SiC production reactor having a heating unit for heating a deposition surface of a SiC growth substrate

The present patent application refers according to claim 1 to a CVD SiC production reactor, according to claim 31 to a method for producing solid SiC, according to claim 34 to a method for the production of a carrier wafer, according to claim 39 to a method for the production of a multi-substrate wafer, according to claim 45 to a carrier wafer, according to claim 46 to a multi-substrate wafer and according to claims 58 and 59 to an electronic device.

Technological background is disclosed e.g. by US2010/291328A1 ; JP2009117533A; EP3351660A1 ; WO2021191511 A1 ; WO2022123078A1 ; or

JOURNAL OF THE ELECTROCHEMICAL SOCIETY, vol. 151 , no. 6, 1 January 2004 (2004—01—01), page C399, XP093142518, ISSN: 0013-4651 , DOI: 10.1149/1.1737386;

DESAIN JOHN D. ET AL: "Reaction of chlorine atom with trichlorosilane from 296to473K"; or

THE JOURNAL OF CHEMICAL PHYSICS, vol. 125, no. 22, 14 December 2006 (2006—12— 14), XP093136567, US ISSN: 0021—9606, DOI: 10.1063/1.2404673; or

Jennings Michael R. ET AL: "Bow Free 4" Diameter 3C-SiC Epilayers Formed upon Wafer- Bonded Si/SiC Substrates", ECS solid state letters, 25 September 2012 (2012-09-25), pages P85-P88, XP093087492, DOI: 10.1149/2.007206ss1.

Document GB1128757 discloses a method for the depositing of a thin coating of SiC. However, the teaching of GB1128757 does not relate to a method for the production of large quantities of SiC, in particular not to a solid SiC bodies which could be separated into a plurality of wafers. Document US2007/0251455A1 discloses a CVD process for the production of polysilicon. However, due to different temperature profiles and different source materials and different chemistry resulting during SiC deposition document

US2007/0251455A1 describes a significantly different subject-matter.

DE1184738 (B) discloses a method for producing silicon carbide crystals in monocrystalline and polycrystalline form by reacting silicon halides with carbon tetrachloride in a molar ratio of 1 :1 in the presence of hydrogen on heated graphite bodies. In this process, a mixture of 1 volume percent silicon chloroform, 1 volume percent carbon tetrachloride and hydrogen is first passed over the graphite body at a flow rate of 400 to 600 l/h until a compact silicon carbide layer is formed on the graphite body, and then at a flow rate of 250 to 350 l/h over the deposition body at 1300°C to 2000°C, in particular at 1500°C to 1600°C. This state of the art is disadvantageous because it does not meet today's requirements for high-purity SiC cheaply produced in large scale industrial processes. SiC is used in many areas of technology, in particular power applications and/or electromobility, to increase efficiency. In order for the products requiring SiC to be accessible to a mass market, the manufacturing costs must decrease and/or the quality must increase.

It is therefore the object of the present invention to provide a low-cost supply of silicon carbide (SiC). Additionally, or alternatively, high purity SiC shall be provided. Additionally, or alternatively SiC shall be provided very fast. Additionally, or alternatively SiC shall be producible very effectively.

The before mentioned object is solved by a CVD SiC production reactor according to the present invention, in particular according to claim 1 . The CVD SiC production reactor according to the present invention at least comprises a process chamber, wherein the process chamber is preferably surrounded by a bottom wall section, in particular a base plate wall section, a side wall section and a top wall section, a gas inlet unit for feeding one feedmedium or multiple feed-mediums into a reaction space of the process chamber for providing a source medium, wherein the gas inlet unit is preferably coupled with at least one feedmedium source, or wherein the gas inlet unit is preferably coupled with at least two feedmedium sources, or wherein the gas inlet unit is preferably coupled with at least three feedmedium sources, a gas outlet unit for removing a vent gas mixture from the reaction space of the process chamber, a holding section for holding at least or exactly one SiC growth substrate inside the reaction space in a holding position, a heating unit for heating a deposition surface of the at least or exactly one SiC growth substrate, wherein the heating unit is configured to heat the at least or exactly one SiC growth substrate from at least multiple sides, in particularly along the entire circumference of the at least or exactly one SiC growth substrate.

This solution is beneficial since the deposition surface can be heated in a very precise manner and a temperature difference between the deposition temperature and the core temperature of the SiC growth substrate can be reduced to avoid thermal induced tensions inside the grown SiC. As a result less cracks are present inside the deposited SiC, thus more crack free pieces, in particular wafer, can be produced.

Further preferred embodiment of the present invention are subject matter of the dependent claims and the following specification passages

The heating unit is according to a preferred embodiment of the present invention configured to inductively heat the at least or exactly one SiC growth substrate. This embodiment is beneficial since inductive heating is well known from other technical fields. The heating unit is according to a preferred embodiment of the present invention configured to provide alternating current with a frequency above 1 kHz, in particular with a frequency above 20kHz and preferably with a frequency above 50kHz and most preferably with a frequency above 100kHz. This embodiment is beneficial since penetration depth of an electro-magnetic field can be tuned by defining or adjusting the frequency. The higher the frequency the lower the penetration depth.

The heating unit comprises according to a preferred embodiment of the present invention a coil, wherein the coil is formed by a longitudinal conductor having a first end and a second end, wherein the conductor forms a plurality of turns between the first end and the second end. The turns preferably extend above at least 50% and preferably at least or up to 70% and highly preferably at least or up to 90% of the height of the SiC growth substrate.

The conductor is according to a preferred embodiment of the present invention made of tantalum. This embodiment is beneficial since the melting temperature of tantalum is very high and thus does not require any cooling of the conductor during heating.

The turns form according to a preferred embodiment of the present invention a core, wherein the core has a core center axis, and wherein the at least or exactly one SiC growth substrate has a SiC growth substrate center axis, wherein the coil is arranged in such a manner that the core center axis and the SiC growth substrate center axis are parallel or coaxial during operation of the SiC production reactor. This embodiment is beneficial since a very homogeneous heating of the SiC growth substrate respectively the deposition surface takes place in case the SiC growth substrate center axis and the core center axis are arranged in coaxial manner.

The conductor is according to a preferred embodiment of the present invention formed by a pipe, wherein the pipe is made of metal and wherein the pipe is configured to conduct a fluid from the first end of the conductor to the second end of the conductor for cooling the conductor. This embodiment is beneficial since the conductor can be made of less expensive materials having a melting point below 1500°C. Such metals can be e.g. copper or steal. The fluid is a gas or a liquid, in particular water or oil. A pump for circulating the fluid is preferably provided, wherein the pump is configured to circulate the fluid in such a manner to cool the conductor during operation to a maximum temperature of 1200°C and preferably to a maximum temperature of 1200°C and highly preferably to a maximum temperature of 1000°C.

The heating unit is according to a preferred embodiment of the present invention configured to emit heat radiation, in particular to heat the deposition surface by means of heat radiation. This embodiment is beneficial since the costs for radiation elements are small. The heating unit comprises according to a preferred embodiment of the present invention at least 2 and preferably at least 3 and highly preferably at least 4 heat radiation elements arrange around the holding position. The heat radiation elements are preferably configured to be electrically heated, in particular by means of resistive heating. The heat radiation elements are preferably made of tantalum or graphite or comprise tantalum or graphite or Carbon Fiber Composite (CFG) material. Additionally or alternatively the heat radiation elements are preferably configured to be heated by means of one or multiple gas flame/s.

A glas tube, in particular made of quartz, is arranged according to a preferred embodiment of the present invention between the heating unit and the holding position for separating the reaction space from the heating unit, in particular for shielding the heating unit during operation from the source medium. This embodiment is beneficial since the glas tube is transparent for heat radiation but shields the heating unit from the source medium.

The process chamber is according to a preferred embodiment of the present invention surrounded by a bell jar, wherein an inner surface of the bell jar is polished or coated, in particular silver or gold coated. This embodiment is beneficial since heat losses can be reduced. The bell jar can be made e.g. of quartz.

The bell jar comprises according to a preferred embodiment of the present invention a cooling fluid guide unit for guiding a cooling fluid. This embodiment is beneficial since the bell jar can be made of steel.

The holding section for holding at least or exactly one SiC growth substrate comprises according to a preferred embodiment of the present invention a first metal electrode for coupling to a first end of the at least or exactly one SiC growth substrate and a second metal electrode for coupling to a second end of the at least or exactly one SiC growth substrate, wherein the first and second electrode are configured to conduct electric power through the at least or exactly one SiC growth substrate for heating the at least or exactly one SiC growth substrate by means of resistive heating, in particular during an initial heating phase and/or a cool down phase. This embodiment is beneficial since a further means for heating is provided. It is therefore possible to heat the SiC growth substrate respectively the grown SiC during heat up, during growth and/or during cool down in different manner. Thus, it is e.g. possible to heat the SiC growth substrate in an initial heating phase or cool down phase from the inside (resistive heating) and from the outside (inductive I radiation heating) to maintain a homogeneous temperature distribution inside the SiC growth substrate.

The holding section for holding at least or exactly one SiC growth substrate comprises according to a preferred embodiment of the present invention a first electric isolator for coupling to a first end of the at least or exactly one SiC growth substrate and/or a second electric isolator for coupling to a second end of the at least or exactly one SiC growth substrate, wherein the first electric isolator and/or the second electric isolator prevent flow of electric power via the first end and/or the second end of the at least or exactly one SiC growth substrate.

The vent gas of the CVD SiC production reactor is preferably a mixture of multiple fractions, in particular four fractions. A first fraction of the vent gas mixture is HCI, a second fraction of the vent gas mixture consists of vent gas Chlorosilanes, in particular STC and/or TCS, a third fraction of the vent gas mixture comprises or consists of H2 and a fourth fraction of the vent gas mixture comprises or consists of at least one C-bearing-molecule, in particular methane.

According to a further preferred embodiment of the present invention a vent gas recycling unit is provided.

A bed reactor, in particular a fixed bed reactor or a fluidized bed reactor, is provided as part of the vent gas recycling unit according to a further preferred embodiment of the present invention for generating Chlorosilanes, wherein the bed reactor comprises a bed reactor input opening, wherein the bed reactor input opening is coupled via a pipe with the gas outlet unit for conducting the vent gas mixture into the bed reactor, wherein the bed reactor comprises a reactor chamber for receiving solid Si and for reacting the SI with the first fraction of the vent gas mixture, wherein the solid Si comprises metal impurities of more than 10OOppmw,

This embodiment is beneficial since vent gas fractions can be used to generate Chlorosilanes. Thus, the overall output can be increased and less feed gas needs to be delivered from a feed gas production plant. Therefore, less resource consumption takes place since less transportation takes place and also risks for accidents and therefore pollution is reduced.

In view of the present disclosure the term “reacting” has to be understood in terms of a chemical vapor deposition step.

The bed reactor comprises according to a further preferred embodiment of the present invention a bed reactor outlet, wherein the bed reactor outlet is coupled with the gas inlet unit for conducting generated Chlorosilanes into the reaction space. This embodiment is beneficial since Chlorosilanes can be generated in a cheap and efficient manner and thereby the need for buying and transporting Chlorosilanes from a different location to the location of the CVD SiC production reactor is reduced or avoided.

The vent gas recycling unit comprises according to a further preferred embodiment of the present invention a separating unit for reducing the amount of metal impurities within the generated Chlorosilanes below 20ppmw and preferably below 10ppmw and highly preferably below 5ppmw and most preferably below 1 ppmw and for separating the generated Chlorosilanes and the third fraction of the vent gas mixture and the fourth fraction of the vent gas mixture into a first fluid and into a second fluid. Alternatively, the vent gas recycling unit comprises a separating unit and a Chlorosilane distillation column, wherein the separating unit is configured for removing a first amount of metal impurities from the Chlorosilanes and for separating the generated Chlorosilanes and the third fraction of the vent gas mixture and the fourth fraction of the vent gas mixture into a first fluid and into a second fluid, wherein the Chlorosilane distillation column is configured for removing a second amount of metal impurities from the Chlorosilanes.

This embodiment is beneficial since the amount of metal impurities can be significantly reduced. A reduced amount of metal impurities allows the production of very pure SiC and thus SiC that can be utilized in high end applications.

A solid Si supply device is provided according to a further preferred embodiment of the present invention for feeding solid Si during operation of the bed reactor into the bed reactor. Thus, solid Si can be feed into the bed reactor during the step of generating Chlorosilanes by reacting HCI and Si is carried out. This embodiment is beneficial since the bed reactor can be run in continuous manner and therefore could be coupled to one or multiple CVD SiC production reactors for generating Chlorosilanes based on the vent gas of said multiple CVD SiC production reactors.

The vent gas recycling unit comprises according to a further preferred embodiment of the present invention a further separating unit for separating STC (Silicon tetrachloride) and TCS (Trichlorosilane). A first storage and/or conducting element for connecting the separating unit with the further separating unit is preferably provided as part of the vent gas recycling unit and a STC storage and a TCS storage is preferably provided as part of the vent gas recycling unit. The further separating unit is highly preferably coupled with the STC storage and the TCS storage, wherein the STC storage and/or the TCS storage forms a section of a Chlorosilanes mass flux path for conducting STC and/or TCS into the process chamber.

This embodiment is beneficial since supply of Chlorosilanes removed from the vent gas and produced by reacting one or multiple fraction/s of the vent gas with Si into the process chamber does not depend on the actual output from the reactor chamber, since the necessary mass or volume of Chlorosilanes can be removed from the respective storage, namely the STC storage and/or the TCS storage). The further separating unit is according to a further preferred embodiment of the present invention a distillation column. This embodiment is beneficial since distillation columns are very reliable and are able to handle high throughput.

The distillation column is preferably configured to separate one or multiple metallic components, in particular B, Al, Fe and/or P, from the first fluid, in particular prior to the separation of STC and TCS, wherein separated metallic component/s is/are preferably feedable to a waste storage.

STC is according to a further preferred embodiment of the present invention feed from the further separating unit, in particular the distillation column, to the STC storage and wherein TCS is feed from the further separating unit, in particular distillation column, to the TCS storage.

According to a further preferred embodiment of the present invention Metal chlorides (such as FeCI3 or AICI3) leave the reactor chamber, in particular of the bed reactor, in the form of particles or in the gas phase, depending on the conditions. Particulate solid metal chlorides can be discharged e.g. via solid separation (cyclones, filters). It is herewith referred to document DE2161641A1 , since document DE2161641A1 discloses e.g. a separating device or a further separating device, in particular distillation column.

According to a further preferred embodiment of the present invention gaseous metal chlorides can be carried on towards condensation and form a solution and/or suspension that can be separated by distillation. The resulting metal-rich heavy-boiling fraction is preferably discharged.

STC is according to a further preferred embodiment of the present invention feedable from the STC storage to the bed reactor, without feeding TCS from the TCS storage to the bed reactor. This embodiment is beneficial since the STC can be reacted to TCS inside the bed reactor.

According to a further preferred embodiment of the present invention the CVD SiC production reactor comprises a vent gas recycling unit, wherein the vent gas recycling unit is connected to the gas outlet unit, wherein the vent gas recycling unit comprises at least a separator unit for separating the vent gas into a first fluid and into a second fluid, wherein the first fluid is a liquid and wherein the second fluid is a gas, wherein a first storage and/or conducting element for storing or conducting the first fluid is part of the separator unit or coupled with the separator unit and wherein a second storage and/or conducting element for storing or conducting the second fluid is part of the separator unit or coupled with the separator unit. This solution is beneficial since the vent gases can be reused, thus the amount of recycled Si, C respectively at least one C-bearing molecule and H2 can be used again for the production of SiC material, in particular PVT source material. Thus, a much higher amount of SiC can be produced based on an initial amount of source gases compared to a SiC production reactor which does not recycle the vent gases.

The vent gas recycling unit preferably comprises a further separator unit for separating the first fluid into at least two parts, wherein the two parts are a mixture of chlorosilanes and a mixture of HCI, H2 and at least one C-bearing molecule. Alternatively the further separator unit separates the first fluid into at least three parts, wherein the three parts are a mixture of chlorosilanes and HCI and a mixture of H2 and at least one C-bearing molecule, wherein the first storage and/or conducting element connects the separator unit with the further separator unit. The further separator unit is preferably coupled with a mixture or chlorosilanes storage and/or conducting element and with a HCI storage and/or conducting element and with a H2 and C storage and/or conducting element. The mixture of chlorosilanes storage and/or conducting element preferably forms a section of a mixture of chlorosilanes mass flux path for conducting the mixture of chlorosilanes into the process chamber. A Si mass flux measurement unit for measuring an amount of Si of the mixture of chlorosilanes is preferably provided as part of the mass flux path prior to the process chamber, in particular prior to a mixing device, and preferably as further Si feed-medium source providing a further Si feed medium. The mixture of chlorosilanes storage and/or conducting element preferably forms a section of a mixture of chlorosilanes mass flux path for conducting the mixture of chlorosilanes into a further process chamber of a further SiC production reactor. The H2 an C storage and/or conducting element preferably forms a section of a H2 and C mass flux path for conducting the H2 and at least one C-bearing molecule into the process chamber. A C mass flux measurement unit for measuring an amount of C of the mixture of H2 and the at least one C-bearing molecule is preferably provided as part of the H2 and C mass flux path prior to the process chamber, in particular prior to a mixing device, and preferably as further C feed-medium source providing a further C feed medium. The H2 an C storage and/or conducting element preferably forms a section of a H2 and C mass flux path for conducting the H2 and the at least one C-bearing molecule into a further process chamber of a further SiC production reactor. The second storage and/or conducting element preferably forms a section of the H2 and C mass flux path for conducting the second fluid, which comprises H2 and the at least one C-bearing molecule, into the process chamber, wherein the second storage and/or conducting element and the H2 an C storage and/or conducting element are preferably fluidly coupled. The second storage and/or conducting element preferably forms a section of a further H2 and C mass flux path for conducting the second fluid, which comprises H2 and the at least one C-bearing molecule, into the process chamber. A further C mass flux measurement unit for measuring an amount of C of the second fluid is preferably provided as part of the further H2 and C mass flux path prior to the process chamber, in particular prior to a mixing device. The second storage and/or conducting element is alternatively coupled with a flare unit for burning the second fluid. The separator unit is preferably configured to operate at a pressure above 5bar and a temperature below -30°C. A first compressor for compressing the vent gas to a pressure above 5bar is preferably provided as part of the separator unit or in a gas flow path between the gas outlet unit and the separator unit. The further separator unit is preferably configured to operate at a pressure above 5bar and a temperature below -30°C and/or a temperature above 100°C. A further compressor for compressing the first fluid to a pressure above 5bar is preferably provided as part of the further separator unit or in a gas flow path between the separator unit and the further separator unit. The further separator unit preferably comprises a cryogenic distillation unit, wherein the cryogenic distillation unit is preferably configured to be operated at temperatures between -180C° and -40C°. A control unit for controlling fluid flow of a feedmedium or multiple feed-mediums is preferably part of the SiC production reactor, wherein the multiple feed-mediums comprise the first medium, the second medium, the third medium and the further Si feed medium and/or the further C feed medium via the gas inlet unit into the process chamber is provided. The further Si feed medium preferably consists of at least 95% [mass] or at least 98% [mass] or at least 99% [mass] or at least 99,9% [mass] or at least 99,99% [mass] or at least 99,999% [mass] and highly preferably of at least 99,99999% [mass] of a mixture of chlorosilanes. The further C feed medium preferably comprises the at least one C-bearing molecule, HCI, H2 and a mixture of chlorosilanes, wherein the further C feed medium comprises at least 3% [mass] or preferably at least 5% [mass] or highly preferably at least 10% [mass] of C respectively of the at least one C-bearing molecule and wherein the further C feed medium comprises up to 10% [mass] or preferably between 0.001% [mass] and 10%[mass], highly preferably between 1% [mass] and 5%[mass], of HCI, and wherein the further C feed medium comprises more than 5% [mass] or preferably more than 10% [mass] or highly preferably more than 25% [mass] of H2 and wherein the further C feed medium comprises more than 0.01% [mass] and preferably more than 1% [mass] and highly preferably between 0.001% [mass] and 10%[mass] of the mixture of chlorosilanes.

A heating unit is preferably arranged in fluid flow direction between the further separator unit and the gas inlet unit for heating the mixture of chlorosilanes to transform the mixture of chlorosilanes from a liquid form into a gaseous form.

The above-mentioned object is also solved by a method for producing solid SiC, in particular according claim 31. Said method for producing solid SiC comprises the steps: Providing a CVD SiC production reactor, in particular according to any of the claims 1 to 30, providing at least or exactly one SIC growth substrate inside the CVD reactor, holding the at least or exactly one SiC growth substrate inside the reaction space in a holding position by means of a holding section, wherein the SiC growth substrate forms a deposition surface surrounding the SiC growth substrate in circumferential direction of the SiC growth substrate, feeding one feed-medium or multiple feed-mediums into a reaction space of the process chamber for providing a source medium, heating the deposition surface of the at least or exactly one SiC growth substrate by means of a heating unit transfer SiC from the source medium on a deposition surface of the at least or exactly one SiC growth substrate, wherein the heating unit is configured to heat the at least or exactly one SiC growth substrate from at least multiple sides, in particularly along an entire circumference of the at least or exactly one SiC growth substrate, in particular by means of heat radiation or induction, growing a SiC solid and removing a vent gas mixture from the reaction space of the process chamber.

The SiC solid preferably has a diameter of at least 7,5cm or a cross-sectional area size orthogonal to the length direction of the SiC growth substrate of at least 44, 17cm².

According to a further preferred embodiment of the present invention a step of feeding the one feed-medium or multiple feed-mediums into a reaction space of the process chamber is preferably carried out by means of at least one feed-medium source, wherein the gas inlet unit is preferably coupled with the at least one feed-medium source or by means of at least two feed-medium sources, wherein the gas inlet unit is preferably coupled with the at least two feed-medium sources or by means of at least three feed-medium sources, wherein the gas inlet unit is preferably coupled with the at least three feed-medium sources.

According to a preferred embodiment of the present invention the heating unit inductively heats the at least or exactly one SiC growth substrate, wherein the heating unit is operated with alternating current with a frequency above 1 kHz, in particular with a frequency above 20kHz and preferably with a frequency above 500kHz and most preferably with a frequency above 1 MHz.

The step of growing a SiC solid comprises according to a further preferred embodiment of the present invention setting up a deposition rate, in particular perpendicular deposition rate, of more than 200 pm/h, in particular of more than 250 pm/h and preferably of more than 300 pm/h and highly preferably of more than 400 pm/h and most preferably of more than 500 pm/h or of up to 2000 pm/h. The above-mentioned object is also solved according to a method for the production of a carrier wafer, in particular according to claim 34. The method at comprises the step of providing a SiC solid, in particular produced according to a method according to claim 31 , 32 or 33, and a step of analyzing the SiC solid to determine a crack-free section of the SiC solid, wherein the step of analyzing the SiC solid is carried out prior to the step of mechanically removing, in particular by means of sawing, the at least one SiC piece from the SiC solid. This embodiment is beneficial since the crack-free volume of the SiC solid can be identified and utilized for SiC carrier wafer production.

The at least one SiC piece is removed according to a preferred embodiment of the present invention from the crack-free section of the SiC solid or wherein the crack-free section of the SiC solid is removed as the at least one SiC piece.

The step of analyzing the SiC solid to determine a crack-free section of the SiC solid is carried out according to a preferred embodiment of the present invention by optical inspection, in particular by means of a caliper or threshold detection. This embodiment is beneficial since an optical inspection does not damage the SiC solid, furthermore optical inspection methods are well established and provide high quality information.

According to a preferred embodiment of the present invention a step of analyzing the SiC piece or the SiC carrier wafer is carried out to determine defects, in particular cracks. This embodiment is beneficial since further processing of a wafer having defects can be avoided and therefore reduces overall costs.

The step of analyzing the SiC piece or the SiC carrier wafer to determine defects is carried out according to a preferred embodiment of the present invention by means of a bend test, in particular a 2 point bend test, a 3 point bend test or a 4 point bend test, an eddy current testing and/or optical analyzing methods, in particular caliper testing or threshold testing or transmission testings. This embodiment is beneficial since the mentioned detection methods are well established and provide high quality information. Testing methods and systems are described in https://www.isravision.com/en/semiconductor/applications/back-end-of- line/internal-cracks/crack-detection-for-semiconductor-wafers/; https://www.hindawi.com/journals/amse/2013/950791/; https://cjme.springeropen.eom/articles/10.1186/s10033-018-0229-2.

The SiC piece preferably has such a size that multiple, in particular 2 or more than 2 or up to 5 or more than 5 and highly preferably up to 10 or more than 10, carrier wafer respectively SiC carrier wafer can be removed, in particular cut or splitted, from the SiC piece.

The present invention is also directed to a method for the production of a compound or composite wafer or multi-substrate wafer, in particular according to any of claims 39 to 44. Said method preferably comprises at least the step of providing a first substrate, wherein the first substrate is a monocrystalline SiC crystal, wherein the monocrystalline SiC crystal is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis, wherein the monocrystalline SiC crystal has a preferably flat top surface, a preferably flat bottom surface and a connecting-surface connecting the top surface and bottom surface, wherein the c-axis is aligned in an angle between 0° and 8° and preferably in an angle between 2° and 6° with respect to a normal on the top surface.

It is herewith also referred to the production of a monocrystalline SiC crystal, which is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis, which is previously described in the previously mentioned patent application EP22174029.3, filed 18.05.2022 with the European Patent Office and to a before described method for producing the first substrate.

The method also comprises the step of providing a second substrate, wherein the second substrate is preferably produced according to a method according to any of claims 34 to 38, wherein the second substrate consists of SiC, in particular polycrystalline 3C-SiC, wherein the at least 60% [volume] of the SiC, in particular polycrystalline SiC, is grown in radial direction, wherein the second substrate has a specific electrical resistance of less than 15m0hmcm, in particular of less than lOmOhmcm or preferably less than 5m0hmcm or most preferably less than 3m0hmcm.

It is herewith also referred to the production of a second substrate, which is at least partially radially grown, in particular by means of a CVD process. Such a CVD process is e.g., described in: Patent application EP22173970.9, filed 18.05.2022 with the European Patent Office.

The method additionally comprises the step of bonding the first substrate and the second substrate together. The flat bottom surface of the monocrystalline SiC crystal is preferably bonded to a flat top surface of the second substrate. This method is beneficial since a composite wafer is provided which can be produced at low cost and which provided a high- quality growth face for further processing, in particular epitaxial methods. The high-quality growth face is hereby materialized a surface of the monocrystalline SiC crystal, in particular by a surface opposite respectively parallel to the surface which is bonded to the second substrate.

According to a further preferred embodiment of the present invention the method also comprises the step of transforming the first substrate in a thin substrate layer by reducing the thickness of the first substrate to less than 20pm, in particular less than 10 pm or less than 5 pm or less than 2 pm or less than 1 pm. This embodiment is beneficial since very little monocrystalline SIC crystal can be used. The production of monocrystalline SiC crystal generally causes high costs, thus reducing the necessary amount of monocrystalline SiC crystal reduces the overall costs.

The step of reducing the thickness of the first substrate to less than 20 pm is carried out according to a further preferred embodiment of the present invention after the first and second substrate are bonded together. This embodiment is beneficial since the resulting thin layer of monocrystalline SiC crystal is always supported by a solid structure.

A step of implanting ions into to the first substrate via the surface of the first substrate which is bonded to the second substrate before the first substrate and the second substrate are bonded together for defining a crack-plane inside the first substrate is carried out according to a further preferred embodiment of the present invention. This embodiment is beneficial since the ions can be implanted via the bottom surface of the monocrystalline SiC crystal before the bottom surface of the monocrystalline SiC crystal is bonded to the second substrate. Ion implantation is generally not possible deep inside a monocrystalline SiC crystal. Thus, due to implanting the ions via the bottom surface the monocrystalline SiC crystal can have a thickness of more than 50 pm and preferably of more than 100 pm and highly preferably of more than 200 pm prior to the reduction of the thickness.

A step of heating at least the implanted ions to a temperature above 800°C, in particular to a temperature between 850°C and 1200°C, is carried out according to a further preferred embodiment of the present invention after the first substrate and the second substrate are bonded together for splitting the first substrate along the defined crack-plane into at least two pieces, wherein one piece is the thin substrate layer. This embodiment is beneficial since the remaining monocrystalline SiC crystal, which is divided from the thin substrate layer, can preferably be used multiple times for dividing thin substrate layers therefrom.

The step of bonding the first substrate and the second substrate together is carried out according to a further preferred embodiment of the present invention by means of plasma bonding or argon beam bonding. This embodiment is beneficial since such bonding processes are well known and easy to handle.

According to a further preferred embodiment of the present invention a step of growing a monocrystalline SiC layer by means of epitaxy onto the thin substrate layer is carried out, wherein monocrystalline SiC layer has a thickness between 1 pm and 50 pm, in particular between 2 pm and 40 pm or between 3 pm and 30 pm or between 4 pm and 20 pm or between 5 pm and 10 pm. This embodiment is beneficial since the compound or composite wafer according to the present invention can be integrated into an electronic device production process. According to a preferred embodiment of the present invention the thin substrate layer has a thickness of less than 1pm, wherein the c-axis is preferably aligned in an angle of 4°. Permissible deviation of the angle is 0,5° or less than 0,5° preferably 0,2° or less than 0,2° and most preferably 0,1° or less than 0,1°.

According to a preferred embodiment of the present invention a monocrystalline SiC crystal layer is provided on the thin substrate layer, wherein the monocrystalline SiC crystal is grown by means of epitaxy.

According to a preferred embodiment of the present invention the thin substrate layer has a thickness between 2pm and 20pm, in particular between 5pm and 12pm, and wherein the thin substrate layer comprises 10¹⁵-10¹⁶ nitrogen atoms per cm³, wherein the c-axis is preferably aligned in an angle of 0°. Permissible deviation of the angle is 0,5° or less than 0,5° preferably 0,2° or less than 0,2° and most preferably 0,1° or less than 0,1°.

The above-mentioned object is also solved by a carrier wafer, in particular according to claim 45. The carrier wafer according to the present invention is preferably produced according to a method according to any of claims 34 to 38. The carrier wafer according to the present invention comprises at least 90% [volume] polycrystalline 3C-SiC or consists of polycrystalline 3C-SiC, wherein the at least 30% [volume], in particular at least 50% [volume] and preferably at least 70% [volume], of the polycrystalline 3C-SiC is grown in radial direction around at least one or exactly one central element, wherein the central element preferably comprises or consists of SiC, wherein the carrier wafer has a specific electrical resistance of less than 30mOhmcm, in particular of less than 15m0hmcm, wherein the carrier wafer is at least nitrogen doped, wherein more than 10¹⁸ nitrogen atoms per cm³ are present inside the second substrate due to doping, wherein the carrier wafer forms a flat top surface, a flat bottom surface and a connecting-surface connecting the top surface and bottom surface and wherein the connecting-surface is grinded to form a defined profile, in particular a R-Type Profile or a F-Type Profile (cf. Fig. 12).

The carrier wafer is preferably predominantly formed by a 3C crystal structure and comprises crystallites extending in length direction of the individual crystallite more than 5pm, in particular more than 10pm and preferably more than 20pm and particular preferably more than 50 pm and most preferably up to 500 pm or up to 300 pm, wherein a bow of the carrier wafer is below 50pm, in particular below 20pm, and/or wherein a warp of the carrier wafer is below 50pm, in particular below 20pm.

The carrier wafer according to the present invention, preferably has a diameter of at least 7,5cm, wherein the SiC carrier wafer has a height between 200pm and 500pm. The SiC carrier wafer preferably comprises at least one or exactly one inner section, in particular one central inner section, and wherein the SiC carrier wafer comprises an outer section, wherein the outer section surrounds the inner section, wherein the inner section consists of a part of a SiC growth substrate, wherein the inner section is formed by a crystal structure, wherein the crystal structure of the inner section is predominantly formed by a 3C crystal structure, and wherein the outer section is formed by a crystal structure, wherein the crystal structure of the outer section is predominantly formed by a 3C crystal structure and comprises crystallites extending in length direction of the individual crystallite more than 5pm, in particular more than 10pm and preferably more than 20pm and particular preferably more than 50 pm and most preferably up to 500 pm or up to 300 pm, wherein a bow of the SiC carrier wafer is below 50pm, in particular below 20pm, and/or wherein a warp of the SiC carrier wafer is below 50pm, in particular below 20pm.

The present invention can also refer to a multi-substrate wafer, at least comprising a first substrate and a second substrate, wherein the first substrate and the second substrate are bonded together, wherein the first substrate is a monocrystalline SiC crystal, wherein the monocrystalline SiC crystal is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis, wherein the monocrystalline SiC crystal has a preferably flat top surface, a preferably flat bottom surface and a connecting-surface connecting the top surface and bottom surface, wherein the c-axis is aligned in an angle between 0° and 8° and preferably in an angle between 2° and 6° with respect to a normal on the top surface, wherein the second substrate consists of polycrystalline Sic, wherein the second substrate is a carrier wafer according to claim 45.

According to a preferred embodiment of the present invention the monocrystalline SiC crystal is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis, wherein the monocrystalline SiC crystal has a preferably flat top surface, a preferably flat bottom surface and a connectingsurface connecting the top surface and bottom surface, wherein the c-axis is aligned in an angle between 0° and 8° and preferably in an angle between 2° and 6° with respect to a normal on the top surface, wherein the monocrystalline SiC crystal preferably consists of SiC preferably of the 4H type. The distance between the flat bottom surface and the flat top surface of the thin substrate layer is preferably below 20pm. This embodiment is beneficial since due to the growth direction perpendicular to the c-axis the number of screw dislocations is significantly reduced.

Production of a monocrystalline SiC crystal, which is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis is previously described by patent application EP22174029.3, filed 18.05.2022 with the European Patent Office. The subject-matter of EP22174029.3 is entirely incorporated by reference.

The polycrystalline structure forms according to a further preferred embodiment of the present invention a plurality of band shaped or line shaped, in particular at least partially curved, in particular at least partially circular or at least partially arc shaped, and/or at least partially straight elements. Said plurality of band shaped or line shaped and/or at least partially straight elements are preferably visible on or via the bottom or top surface. Said plurality of band shaped or line shaped and/or at least partially straight elements preferably extend preferably in height direction of the second substrate and at least partially surrounding a center of the second substrate. Said plurality of band shaped or line shaped and/or at least partially straight elements are beneficial since they allow assignment of the individual second substrates to one ingot or boule. Additionally, or alternatively the plurality of band shaped or line shaped and/or at least partially straight elements allow an analysis of growth speed and composition of the grown polycrystalline structure. Said plurality of band shaped or line shaped and/or at least partially straight elements preferably result from variances of densities in the polycrystalline structure. According to a preferred embodiment the plurality of band shaped or line shaped and/or at least partially straight elements are generated by varying the gas supply during growth of the polycrystalline structure.

The plurality of line shaped, in particular at least partially curved, in particular at least partially circular or at least partially arc shaped, and/or at least partially straight elements is according to a further preferred embodiment of the present invention formed in a distance of at least 1 nm to the preferably flat top surface inside, the preferably flat bottom surface and the connecting-surface. This embodiment is beneficial since the plurality of line shaped, in particular at least partially curved, in particular at least partially circular or at least partially arc shaped, and/or at least partially straight elements can be easily captured by optical analysis tools. At least one and preferably at least two curved, circular and/or arc-shaped and/or straight elements have according to a further preferred embodiment of the present invention a length in circumferential direction of the second substrate of at least 10 nm, in particular at least 20nm or at least 50nm or at least 10Onm or at least or up to 5000nm, in particular up to 2000nm or 10000nm.

The polycrystalline structure comprises according to a further preferred embodiment of the present invention crystallites extending in length direction of the individual crystallite more than 5pm, in particular more than 10pm and preferably more than 20pm. The length directions of more than 30%, in particular more than 50% and preferably more than 70%, of the crystallites, which extend more than 5pm in the length direction of the individual crystallite, in particular more than 10pm or more than 20pm, are preferably aligned in an angle of less than 75°, in particular less than 60° or preferably less than 45° and most preferably less than 30°, to the radial direction of the polycrystalline structure, in particular in a section of the polycrystalline structure.

The radially direction of the polycrystalline structure is preferably determined for multiple sections of the polycrystalline structure, wherein each section comprises in the center the radial direction of the respective section, wherein the respective section has a width of less than 500pm, in particular of less than 300pm and preferably of less than 100pm, wherein the alignment between the radial direction of the polycrystalline structure and the length direction of the individual crystallite which extends more than 5pm, in particular more than 10pm and preferably more than 20pm, is limited to crystallites present in a respective section and the radial direction of the respective section.

The height of the second substrate is according to a further preferred embodiment of the present invention below 500 pm, in particular below 400 pm. This embodiment is beneficial since a higher number of second substrates can be divided from one ingot or boule compared to larger second substrates.

The crystal structure of the monocrystalline SiC crystal comprises according to a further preferred embodiment less than 99,9999% (ppm wt) and preferably less than 99,99999% (ppm wt) and highly preferably less than 99,999999% (ppm wt) and most preferably less than 99,999999% (ppm wt) of one, multiple or all of the following substances B (Bor), Al (Aluminum), P (Phosphor), Ti (Titan), V (Vanadium), Fe (Eisen), Ni (Nickel). This embodiment is beneficial since power devices or units used in power devices and logic devices or units used in logic devices having better efficiency factors can be produced on top of the monocrystalline SiC crystal.

Y1 The flat top surface of the polycrystalline SIC has a surface roughness of Ra < 20 nm and preferably of Ra<10nm and most preferably of Ra<5nm, wherein the monocrystalline SiC crystal is bonded to the flat top surface of the polycrystalline SiC. The surface roughness of Ra < 20 nm and preferably of Ra<10nm and most preferably of Ra<5nm is preferably generated by means of grinding and/or lapping and/or etching, wherein Ra is preferably reduced due to grinding and/or lapping and/or etching more than 30nm, in particular more than 50nm or more than 100nm or more than 200nm or more than 500nm or more than 1000nm or more than 2000nm and/or up to 5000nm or up to 10000nm or up to 20000nm.

According to a further preferred embodiment of the present invention the number of screw dislocations per cm³ present inside the monocrystalline SiC crystal is below the number of basal plane dislocations per cm³.

The top surface and bottom surface are considered to be “flat” since each surface has a Ra of less than 1pm and preferably less than 100nm and highly preferably less than 10nm and most preferably less than 1 nm.

The top surface and the bottom surface are considered to be “parallel” since a virtual plane extending through the at least three highest peaks of the bottom surface is inclined less than 1° and preferably less than 0,1° and highly preferably less than 0,01° and most preferably less than 0,001° to a virtual plane extending through the at least three highest peaks of the top surface. The term “peaks” herewith refer to surface roughness and describes the distance from a mean line as used to calculate the arithmetic average of profile height deviations from the mean line (cf. Ra calculation; https://en.wikipedia.org/wiki/Surface_roughness; 27.03.2023).

According to a preferred embodiment of the present invention the thin substrate layer has a thickness of less than 1pm, wherein the c-axis is preferably aligned in an angle of 4°. Permissible deviation of the angle is 0,5° or less than 0,5° preferably 0,2° or less than 0,2° and most preferably 0,1° or less than 0,1°.

A monocrystalline SiC crystal layer is provided or generated according to a further embodiment of the present invention on the first substrate or on the thin substrate layer, wherein the monocrystalline SiC crystal is grown by means of epitaxy. This embodiment is beneficial since device production can be carried out on and/or in that monocrystalline SiC crystal layer. The thin substrate layer is preferably less doped compared to the second substrate, in particular comprises less than 1/10 or preferably less than 1/100 or highly preferably less than 1/1000 of the doping per cm3 compared to the second substrate. The thin substrate layer preferably has a distance between the flat bottom surface and the flat top surface of the thin substrate layer between 0,01 pm and 1 pm respectively below 1 pm or preferably below 0,8pm or highly preferably below 0,5pm.

The present invention also refers to an electronic device, in particular according to claim 58. The electronic device according to the present invention at least comprises a multi-substrate wafer, in particular according to any of claims 46 to 57, wherein at least one electronic component is grown or produced on or in the monocrystalline SiC crystal layer and wherein the second substrate has a thickness of more than 50pm, in particular more than 60pm or more than 80pm or more than 100pm or more than 150pm or up to 350.

The present invention also refers to an electronic device, in particular according to claim 59. The electronic device according to the present invention at least comprises a multi-substrate wafer, in particular according to claim 57, wherein at least one electronic component is grown or produced on or in the first substrate and wherein the second substrate has a thickness of more than 50pm, in particular more than 60pm or more than 80pm or more than 100pm or more than 150pm or up to 350.

The electronic device can be a MOSFET or a Schottky Diode. This solution is beneficial since said electronic device can be produced at lower costs and higher quality.

In case the CVD SiC production reactor is additionally equipped with at least a vent gas recycling unit and/or a further CVD SiC production reactor the term “CVD SiC production reactor” has to be understood as “CVD SiC production reactor system”.

Further advantages, objectives and features of the present invention are explained with reference to the following description of accompanying drawings, in which the device(s) according to the invention are shown by way of example. Components or elements of the composite wafer or method according to the invention, which at least substantially correspond in the figures with respect to their function, can be marked with the same reference signs, whereby these components or elements do not have to be numbered or explained in all figures.

Fig. 1 shows a first schematic example of components of a CVD SiC production reactor according to the present invention;

Fig. 2 shows a second schematic example of components of a CVD SiC production reactor according to the present invention;

Fig. 3 shows a third schematic example of components of a CVD SiC production reactor according to the present invention; Fig. 4 shows a fourth schematic example of components of a CVD SiC production reactor according to the present invention, wherein a water cooled coil is shown;

Fig. 5 shows schematically a CVD SiC production reactor and a first vent gas recycling unit, wherein HCI is removed from the vent gas mixture;

Fig. 6 shows schematically a CVD SiC production reactor and a second vent gas recycling unit, wherein a HCI vent gas fraction is transformed into Chlorosilanes;

Fig. 7 shows a fifth schematic example of components of a CVD SiC production reactor according to the present invention, wherein multiple SiC growth substrates are arranged coaxial,

Fig. 8a/b show a sixth schematic example of components of a CVD SiC production reactor according to the present invention, wherein a bell jar covers the process chamber;

Fig. 9a/b show a seventh schematic example of components of a CVD SiC production reactor according to the present invention, wherein heating is carried out by means of induction and wherein multiple SiC growth substrates are arranged inside the reaction space;

Fig. 10a/b show a tenth schematic example of components of a CVD SiC production reactor according to the present invention; wherein heating is carried out by means of radiation elements;

Fig. 11 a/b show an eleventh schematic example of components of a CVD SiC production reactor according to the present invention, wherein heating is carried out by means of radiation elements;

Fig. 12a shows a first a first edge shape after mechanical treatment;

Fig. 12b shows a second edge shape after mechanical treatment;

Fig. 13 shows an example of the CVD SiC apparatus respectively CVD SiC production reactor according to the present invention, wherein also a vent gas treatment unit is shown,

Fig. 14 shows an example of the CVD SiC apparatus respectively CVD SiC production reactor according to the present invention, wherein also a vent gas recovery unit is shown, Fig. 15 shows an example of the vent gas treatment unit according to the present invention,

Fig. 16 shows an example of the vent gas recovery unit according to the present invention,

Fig. 17 shows a further example of a vent gas recovery unit according to the present invention,

Fig. 18-25 show different settings according to the present invention, wherein in each setting a vent gas recycling unit is provided, wherein said vent gas recycling unit at least comprises a bed reactor;

Fig. 26a-d show the steps of the production of composite wafer according to the present invention;

Fig. 26e further shows an optional further step of growing an epi-layer on the composite wafer;

Fig. 27a-d show a similar method compared to fig. 26a-d, wherein the thin substrate layer is thicker compared to fig. 26a-d to provide a composite wafer that can be used for device production without an epi-layer production step;

Fig. 28 shows a high-resolution photo of the crystal structure of the second substrate,

Fig. 29 shows fig. 28 with modifications indicating the main growth direction (radial direction) as well as multiple orientations of large crystallites;

Fig. 30a shows a conventional growth of a carrier wafer;

Fig. 30b-d show schematic illustrations of the growth direction in specific sections;

Fig. 31 shows an enlarged section of fig. 28, wherein the length direction and boundary of one crystallite is highlighted;

Fig. 32a/b show line shaped elements generated during the growth process.

Fig. 1 shows components of a SiC production reactor 850 according to the present invention. The SiC production reactor 850 comprises a heating unit 954, wherein the heating unit 954 preferably comprises a conductor 2830 forming a coil 2828. The conductor 2830 comprises a first end 2832 and a second end 2834, wherein the first end 2832 and the second end 2834 are preferably arranged or positioned in a coupling unit 2858. The first end 2832 and the second end 2834 are preferably fixed by welding (cf. reference number 2860) to the coupling unit 2858. Reference number 866 indicates a gas flow into a reaction space 966 and reference number 216 indicates a gas flow out of the reaction space 966, in particular into a vent gas recycling unit (not shown).

A first end 2854 of the SiC growth substrate 850 is preferably arranged or positioned in a holding section 2824a, wherein the holding section 2824a can be configured as electrode 206a or electric isolator, in particular made of graphite. A second end 2856 of the SiC growth substrate 850 is preferably arranged or positioned in a holding section 2824b, wherein the holding section 2824b can be configured as electrode 206b or electric isolator, in particular made of graphite.

Fig. 2 shows a configuration of the CVD SiC production reactor 850 which is similar to the one shown in Fig. 1 . However, reference numbers 851 , 852, 853 indicate that multiple, in particular two or three, feed-medium sources are coupled to the CVD SiC production reactor 850 for providing gas to the gas inlet unit 866. Reference number 2826 indicates that the heating unit preferably heats the entire circumference of the SiC growth substrate 857. Fig. 2 further shows that a core center axis 2838 and a SiC growth substrate center axis 2840 can be coaxial. The conductor 2830 can be shaped or formed as pipe for conducting a cooling fluid, in particular a cooling liquid, like water or oil. The conductor 2830 is preferably made of copper or steel. Fig. 2 also shows that the gas inlet unit 866 can be arranged below the heating unit and the gas outlet unit 216 can be arranged above the heating unit, this can be applied to all other CVD SiC production reactors of the present invention. Alternatively, the CVD SiC production reactors 850 according to the present invention can have a gas inlet unit 866 for feeding gas from the side into the reaction space 966 and a gas outlet unit 216 for removing the vent gas mixture via a side (cf. Fig. 4). Combinations of such gas inlet unit 866 arrangements and gas outlet unit 216 arrangements are also possible.

Fig. 3 shows a generator 2844 coupled with the conductor 2830. The generator is preferably configured to provided alternating current with at least one frequency above 10kHz, in particular above 500kHz and highly preferably above 1 MHz. Reference number 2836 indicates a plurality of turns. The coil 2828 comprises preferably at least four turns or more than or up to 8 turns or highly preferably more than or up to 20 turns and most preferably more than or up to 100 turns.

Fig. 4 shows a cooling unit 2842 for cooling a cooling fluid which is circulated inside the conductor 2830. It has to be understood that a cooling unit 2842 for cooling a cooling fluid which is circulated inside the conductor 2830 can be present in all CVD SiC production reactors of the present invention having a heating unit for inductively heating a deposition surface.

Fig. 5 shows a CVD SiC production reactor 850 according to the present invention, wherein a distillation unit 602 is provided for removing HCI from the vent gas mixture. HCI 956 is removed from the vent gas recycling unit 600. Chlorosilanes 956 can be feed from the distillation unit 602 to a storage means 2422/2424. The storage 2422/2424 is preferably coupled with the gas input unit 866 of the CVD SiC production reactor 850. It has to be understood that this setting can be applied to all CVD SiC production reactors 850 of the present invention. A more detailed description of said vent gas recycling unit and variants thereof is/are described with respect to figures 13-17.

Fig. 6 shows a CVD SiC production reactor 850 according to the present invention, wherein a bed reactor 2416 is coupled to the CVD SiC production reactor 850 for treating the vent gas mixture generated inside the CVD SiC production reactor 850. The bed reactor 2416 preferably comprises solid Si and reacts the solid Si with HCI of the vent gas mixture. A distillation unit 602 for purification of the generated Chlorosilanes and the remaining fractions of the vent gas mixture is preferably provided downstream the bed reactor 2416. Excess H2 is preferably outputted via a first outlet of the distillation unit 602. The remaining and generated Chlorosilanes 956 are preferably conductable to a TCS and/or STC storage 2422/2424. The TCS and/or STC storage 2422/2424 is preferably coupled with the gas input unit 866 of the CVD SiC production reactor 850. It has to be understood that this setting can be applied to all CVD SiC production reactors 850 of the present invention. A more detailed description of said vent gas recycling unit and variants thereof is/are described with respect to figures 18-25.

Fig. 7 schematically shows an embodiment similar to the one shown in fig. 4. However, a plurality of SiC growth substrates 857, in particular two or exactly two SiC growth substrates 857, is arranged in coaxial manner, wherein a spacer or coupling element 2850, in particular made of graphite or CFG material, is arranged between the SiC growth substrates 857a and 857b.

Fig. 8a schematically shows a cross-sectional view of a CVD SiC production reactor 850 according to the present invention, wherein a process chamber 856 is covered by means of a bell jar 864. The bell jar 864 comprises a side wall section 864a and a top wall section 864b, wherein an inner surface 2852 of the bell jar 864 can be polished and/or coated, in particular silver or gold coated. The coating is beneficial sine it increases reflectivity and chemical resistance. It has to be understood that all SiC production reactors 850 according to the present invention can be equipped with a bell jar 864. The bell jar 864 can be a fluid cooled metal bell jar or a bell jar 864 made of quartz respectively at least partially made of quartz. Reference numbers 2834 and 2848 indicate a first and second end of a coil 2828. It has to be understood that all SiC production reactors 850 according to the present invention can be equipped with one, exactly one or more than one SiC growth substrate 850, wherein the SiC growth substrate can comprise graphite or SiC or can consist of graphite or SiC.

Fig. 8b shows a CVD SiC production reactor 850, wherein the CVD SiC production reactor 850 at least comprises a process chamber 856. The CVD SiC production reactor 850 preferably comprises a gas inlet unit 866 for feeding one feed-medium or multiple feedmediums into a reaction space 966 of the process chamber 856 for providing a source medium. The gas inlet unit 866 of all CVD SiC production reactors 850 according to the present invention and disclosed herein can be coupled with a vent gas recycling unit 600 (cf. any of Figures 13 to 17 or any of Figures 18 to 25) for feeding recycled or generated Chlorosilanes into the reaction space 966. The CVD SiC production reactor 850 preferably also comprises a gas outlet unit 216 for removing a vent gas mixture from the reaction space of the process chamber 856. The gas outlet unit 216 of all CVD SiC production reactors according to the present invention and disclosed herein can be coupled with a vent gas recycling unit 600 (cf. any of Figures 13 to 17 or any of Figures 18 to 25) for feeding the vent gas mixture to the respective vent gas recycling unit 600. Reference number 2824 indicates a holding section for holding at least or exactly one SiC growth substrate 857 inside the reaction space 966 in a holding position. A heating unit for heating a deposition surface 861 of the at least or exactly one SiC growth substrate 857 is indicated by reference number 954, wherein the heating unit 954 is configured to heat the at least or exactly one SiC growth substrate 857 from at least multiple sides, in particularly along the entire circumference 2826 of the at least or exactly one SiC growth substrate 857. In the present example the heating unit 954 is an inductive heating unit, wherein a coil 2828 (cf. Fig. 8a) surrounds the SiC growth substrate 857. Reference number 2848 refers to a glas tube, in particular a quartz tube, wherein the tube 2848 shields the heating unit 954 from a source medium but allows the electro-magnetic field to heat the deposition surface of the SiC growth substrate 857. It is possible to avoid the tube 2848 in case the heating unit 954 is less hot compared with the temperature of the deposition surface 861 during depositing, in particular more than 100°C colder and preferably 300°C colder and most preferably up to or more than 500°C colder.

Fig. 9a shows a further example of a CVD SiC production reactor 850 according to the present invention, wherein a coil 2828 of a heating unit 954 surrounds a plurality of SiC growth substrates 857, in particular up to 5 or exactly 5 or more than 5 SiC growth substrates 857a-e.

Reference number 872 in Fig. 9b indicates a cooling unit 872 for fluidly cooling the bell jar 864. It has to be understood that all SiC production reactors 850 according to the present invention can be equipped with a bell jar 864 and a cooling unit 872 for cooling the bell jar 864.

Fig. 10a schematically shows a cross-sectional view of a CVD SiC production reactor 850 according to the present invention, wherein a process chamber 856 is covered by means of a bell jar 864. A plurality of heat radiation elements 2846a-d, in particular at least 3 heat radiation elements 2846 and preferably more than 3 heat radiation elements 2846 and highly preferably up to 10 radiation elements 2846, is arranged around one or at least one SiC growth substrate 857. A tube 2848, in particular a glas tube or quartz tube, is arranged around the SiC growth substrate 857 respectively between the SiC growth substrate holding position and the radiation elements 2846. The radiation elements 2846 belong to a heating unit, wherein the radiation elements 2846 are configured to heat the deposition surface 861 of the SiC growth substrate 857 to a temperature above 1500°C. The distance DI between a center axis of the SiC growth substrate 857 and the radiation elements 2846a is preferably at least 12cm and highly preferably at least or up to 15cm. It has to be understood that all SiC production reactors 850 according to the present invention can be equipped with SiC growth substrates having a diameter prior to SiC deposition between 5mm and 20mm and highly preferably between 8mm and 12mm, in particular 10mm.

Fig. 10b schematically shows that the radiation elements 2846a preferably extend in height direction more than the SiC growth substrate 857.

Fig. 11a and 11 b are similar to Fig. 10a/b, wherein the number of radiation elements 2846 is higher (cf. Fig. 11 a) and wherein reference number 2824 indicates a holding section, wherein the holding section 2824 can be materialized by an electrode or an electric isolation element.

Fig. 12a shows a R-type edge design of a wafer, in particular carrier wafer of the present invention or multi-substrate wafer of the present invention, wherein the edge comprises preferably two beveled sections and a radiused section. The radiused section is preferably arranged between the beveled sections.

Fig. 12b shows a F-type edge design of a wafer, in particular carrier wafer of the present invention or multi-substrate wafer of the present invention, wherein the edge comprises preferably two beveled sections, two radiused sections and a flat section. The flat section is preferably arranged between the beveled sections. On one side of each radiused section is the flat section and on the other side of the radiused section are the beveled sections formed.

In one preferred embodiment of the present invention, Fig. 13 shows preferred main units of the SiC, in particular UPSiC, production reactor 850, in particular for the production of SiC, wherein the SiC production reactor 850 comprises according to this embodiment a SiC vent gas treatment. The separate feed gases 98 are pumped from their respective storage units to the feed gas unit 1000 where there are mixed in the required mass ratios to form the feed gas mixture 198. The feed gas mixture 198 is the fed to the CVD unit respectively CVD reactor respectively SiC production reactor, in particular SiC PVT source material production reactor, 850 where the deposition reaction occurs resulting in the production of SiC rods 298 and vent gas 296. The vent gas 296 is routed to the vent gas treatment unit 500 where preferably scrubber inlet water 496 is used to remove Si-bearing compounds and HCI from the vent gas 296. The scrubber outlet water 598 containing the absorbed Si-bearing compounds and HCI is discharged and the scrubbed vent gas is preferably sent to a flare for combustion. The flare can use flare combustion gas 497 such as natural gas to achieve the combustion of the scrubbed vent gas and the resulting flare exhaust gas is discharged.

The SiC rods 298 are preferably conveyed to the comminution unit 300 where they are reduced to the required form factor, e.g., granules. Also, any heterogenous material, e.g., graphite seed rods, are preferably separated from the SiC material in such a manner as to minimize any residual contamination from this material, e.g., by heating the SiC to at least 1500°C to burn off any residual graphite. The SiC, in particular UPSiC, granules 398 are preferably conveyed to the acid etching unit 400 where they preferably undergo an additional or alternative surface cleaning step of acid etching in an acid bath. Finally, the SiC, in particular UPSiC, etched granules 498 which have been washed and dried after the acid bath are ready for packaging and shipment.

In another preferred embodiment of the present invention, Fig. 14 shows the main units of the entire CVD SiC, in particular UPSiC, apparatus 850 in this case with vent gas recycling. Here the vent gas 296 exits the CVD unit respectively CVD reactor respectively SiC production reactor, in particular SiC PVT source material production reactor, 850 and is routed to the vent gas recycling unit 600. HCI is preferably separated from the vent gas 296 and exits the vent gas recycling unit 600 as the HCI discharge 696. The recycled vent gas 698 is then fed back to the CVD unit respectively CVD reactor respectively SiC production reactor, in particular SiC PVT source material production reactor, 850 thus reducing the amount of fresh feed gas mixture 198 required and reducing production costs. Since product purity is highly beneficial, in the apparatuses described in Fig. 13, preferably extreme care is taken not to introduce any contaminants, particularly trace metals and nitrogen or oxygen into the feed gases or any intermediate and final products. Virtually all equipment and piping is fabricated from metals, particularly various steel alloys, but they are highly preferably kept at temperatures where the entrainment of metal particles into the feed gases and products is minimized. The feed gases and products are preferably further isolated from any moisture or air that could result in nitrogen and or oxygen contamination. Nitrogen could be used as a blanket and purge gas in tanks, pipes and vessels, but it is preferably removed from any liquid feedstocks with degassing equipment and any nitrogen purge gases are preferably chased with hydrogen to minimize the possibility of nitrogen contamination.

Fig. 15 shows the vent gas treatment unit 500 of the CVD SiC, in particular UPSiC, apparatus 850 in one preferred embodiment of the present invention where the vent gas 296 is treated and discharged rather than recycled. The vent gas 296 is routed from the CVD unit respectively CVD reactor respectively SiC production reactor, in particular SiC PVT source material production reactor, 850 to the filter unit 502 of the vent gas treatment unit 500 where any particulates that may have formed in the gas are removed. The filtered vent gas 504 is then preferably sent to the scrubber unit 506 where it is preferably absorbed into scrubber inlet fluid, in particular water 496. Scrubber outlet water 598 preferably containing any Si-bearing compounds and HCI then exits the scrubber, in particular to be processed for disposal. The scrubbed vent gas 512 is then preferably sent to the flare unit 514 where it is combusted with flare combustion gas 497, preferably natural gas, and the resulting flare exhaust gas 596 is suitable for discharge.

Fig. 16 shows an example of a vent gas recycling unit 600 of the CVD SiC, in particular UPSiC, apparatus 850 in another preferred embodiment of the present invention where the vent gas 296 is recycled rather than treated and discharged. The vent gas 296 is routed from the CVD unit respectively CVD reactor respectively SiC production reactor, in particular SiC PVT source material production reactor 850 to the cold distillation unit 602 which preferably operates in a temperature range of -30°C to -196°C. In this temperature range any Si-bearing gases condense and exit the bottom of the distillation unit 602 as an Si- bearing liquid mixture 604. This Si-bearing liquid mixture 604 is periodically routed to a HMW distillation unit 606 which operates in a temperature range that evaporates the Si- bearing liquid 604 while any heavy-molecular-weight compounds remain liquid and exit the bottom of the HMW distillation unit 606 as the HMW liquids discharge 608.

Meanwhile, the Si-bearing gas mixture 620 is exiting the top of the HMW distillation unit 606 and passing through an Si detector unit 622 which determines the mass of Si present. The Si detector unit 622 communicates this information to the central process control unit of the CVD SiC, in particular UPSiC, apparatus 850 which then adjusts the mass flow meter 1120 on the Si-bearing gas 110 line such that the total mass of Si coming from the Si-bearing gas mixture 620 and the Si-bearing gas 110 is in the desired ratio with the total mass of C coming from the H/C-bearing gas mixture 616 and the C-bearing gas 111. Meanwhile, cold distillation gas 610 is exiting the top of the top of the cold distillation unit 602 and is sent to the cryogenic distillation unit which preferably operates in a temperature range between - 140°C and -40°C. in this temperature range, the H/C-bearing gas mixture 616 remains in the gaseous form but the HCI condenses and is removed from the bottom of the Cryogenic distillation unit 612 as the HCI liquid discharge 696 to be further processed for disposal.

The H/C-bearing gas mixture 616 is passed through an H/C detector unit which determines the masses of H and C present. The H/C detector unit communicates this information to the central process control unit of the CVD SiC, in particular UPSiC, apparatus 850 which then adjusts the mass flow meters 1120 on the hydrogen gas 102 line and the C-bearing gas 111 line such that the mass ratios of H, C, and Si are all in the desired range.

Fig. 17 shows a further example of a vent gas recycling unit 600. According to this example the vent gas recycling unit 600 is attached or coupled to at least von gas outlet unit for outputting vent gas 216 of at least one SiC production reactor 850.

The vent gas recycling unit 600 preferably comprises at least a separator unit 602 for separating the vent gas 216 into a first fluid 962 and into a second fluid 964. The first fluid 962 is preferably a liquid and the second fluid 964 is preferably a gas. A first storage and/or conducting element for storing or conducting the first fluid 962 is part of the separator unit 602 or coupled with the separator unit 602 and a second storage and/or conducting element 626 for storing or conducting the second fluid 964 is part of the separator unit 602 or coupled with the separator unit 602.

The vent gas recycling unit 600 preferably comprises a further separator unit 612 for separating the first fluid into at least two parts, wherein the two parts are a (a) mixture of chlorosilanes and (b) a mixture of HCI, H2 and at least one C-bearing molecule. Alternatively the further separator unit 612 separates the first fluid into at least three parts, wherein the three parts are (a) a mixture of chlorosilanes and (b) HCI and (c) a mixture of H2 and at least one C-bearing molecule. The first storage and/or conducting element 624 preferably connects the separator unit 602 with the further separator unit 612. The further separator unit 612 is preferably coupled with a mixture of chlorosilanes storage and/or conducting element 628 and with a HCI storage and/or conducting element 630 and with a H2 and C storage and/or conducting element 632. The mixture of chlorosilanes storage and/or conducting element 628 preferably forms a section of a mixture of chlorosilanes mass flux path for conducting the mixture of chlorosilanes into the process chamber 856, in particular to a mixing device 854.

A Si mass flux measurement unit 622 for measuring an amount of Si of the mixture of chlorosilanes can be provided as part of the mass flux path prior to the process chamber 856, in particular prior to a mixing device 854. The Si mass flux preferably serves as further Si feed-medium source providing a further Si feed medium. It has to be noted that the mixture of chlorosilanes preferably can be a random mixture respectively can have a random composition of different chlorosilanes. The mixture of chlorosilanes storage and/or conducting element 628 alternatively forms a section of a mixture of chlorosilanes mass flux path for conducting the mixture of chlorosilanes into a further process chamber 952 of a further SiC production reactor 950, in particular via fluid path 948.

The H2 an C storage and/or conducting element 632 preferably forms a section of a H2 and C mass flux path for conducting the H2 and the at least one C-bearing molecule into the process chamber 850. A C mass flux measurement unit 618 for measuring an amount of C of the mixture of H2 and the at least one C-bearing molecule is preferably provided as part of the H2 and C mass flux path prior to the process chamber 856, in particular prior to a mixing device 854, and preferably as further C feed-medium source providing a further C feed medium. The H2 an C storage and/or conducting element 632 alternatively forms a section of a H2 and C mass flux path for conducting the H2 and the at least one C-bearing molecule into a further process chamber 952 of a further SiC production reactor 950, in particular via fluid path 949.

The second storage and/or conducting element 626 preferably forms a section of the H2 and C mass flux path for conducting the second fluid, which comprises H2 and at least one C- bearing molecule, into the process chamber 856, wherein the second storage and/or conducting element 626 and the H2 an C storage and/or conducting element 632 are preferably fluidly coupled.

The second storage and/or conducting element 626 preferably forms a section of a further H2 and C mass flux path for conducting the second fluid, which comprises H2 and C, into the process chamber 856. A further C mass flux measurement unit for measuring an amount of C of the second fluid is preferably provided as part of the further H2 and C mass flux path prior to the process chamber 856, in particular prior to a mixing device 854. The mixing device 854 can be part of the gas inlet unit 866 or can belong to the gas inlet unit 866 or can be a sub unit of the gas inlet unit 866. The second storage and/or conducting element 626 can be coupled with a flare unit for burning the second fluid. The separator unit 602 is highly preferably configured to operate at a pressure above 5bar and a temperature below -30°C.

A first compressor 634 for compressing the vent gas to a pressure above 5bar can be provided as part of the separator unit 602 or in a gas flow path between the gas outlet unit 216 and the separator unit 602. The further separator unit 612 is highly preferably configured to operate at a pressure above 5bar and a temperature below -30°C and/or a temperature above 100°C. A further compressor 636 for compressing the first fluid to a pressure above 5bar can be provided as part of the further separator unit 612 or in a gas flow path between the separator unit 602 and the further separator unit 612. The further separator unit 612 highly preferably comprises a cryogenic distillation unit, wherein the cryogenic distillation unit is preferably configured to be operated at temperatures between -180C⁰ and -40C°.

A control unit 929 for controlling fluid flow of a feed-medium or multiple feed-mediums is preferably part of the SiC production reactor 850, wherein the multiple feed-mediums comprise the first medium, the second medium, the third medium and the further Si feed medium and/or the further C feed medium via the gas inlet unit into the process chamber 856. The further Si feed medium highly preferably consists of at least 95% [mass] or at least 98% [mass] or at least 99% [mass] or at least 99,9% [mass] or at least 99,99% [mass] or at least 99,999% [mass] of a mixture of chlorosilanes. Additionally or alternatively the further C feed medium preferably comprises the at least one C-bearing molecule, H2, HCI and a mixture of chlorosilanes. The further C feed medium highly comprises the at least one C- bearing molecule, HCI, H2 and a mixture of chlorosilanes, wherein the further C feed medium comprises of at least 3% [mass] or preferably at least 5% [mass] or highly preferably at least 10% [mass] of C respectively the at least one C-bearing molecule and wherein the further C feed medium comprises up to 10% [mass] or preferably between 0.001% [mass] and 10%[mass], highly preferably between 1% [mass] and 5%[mass], of HCI, and wherein the further C feed medium comprises more than 5% [mass] or preferably more than 10% [mass] or highly preferably more than 25% [mass] of H2 and wherein the further C feed medium comprises more than 0.01% [mass] and preferably more than 1% [mass] and highly preferably between 0.001% [mass] and 10%[mass] of the mixture of chlorosilanes.

Additionally, a heating unit 954 can be arranged in fluid flow direction between the further separator unit and the gas inlet unit, in particular as part of the further separator unit 612, for heating the mixture of chlorosilanes to transform the mixture of chlorosilanes from a liquid form into a gaseous form. Fig. 18 shows an example of a system according to the present invention. Said system comprises at least one CVD SiC reactor 850 (reference numbers 850a and 850b in case of multiple CVD SiC reactors) and at least on vent gas recycling unit 600, wherein the vent gas recycling unit 600 comprises at least a reactor, in particular a bed reactor 2416, for reacting Si and one or more than one fractions of the vent gas mixture of the CVD SiC reactor 850 to produce Chlorosilanes, in particular STC and/or TCS. It is possible to forward Chlorosilanes produced inside the reactor 2416 to the CVD SiC reactor 850a that provided the vent gas for the Chlorosilane production. Additionally or alternatively it is possible to forward the generated Chlorosilanes to another CVD SiC reactor 850b.

According to the present invention a CVD SiC reactor 850a/b preferably comprises at least one process chamber 856a/b and at least one and preferably multiple SiC growth substrates 857a/b arranged respectively arrangeable inside the CVD SiC reactor 850a/b. The CVD SiC reactor 850/a/b preferably comprises at least or exactly one vent gas outlet 216, wherein said vent gas outlet 216 is preferably directly or indirectly coupled via a vent gas conduit 2400 with a gas inlet 2417 of reactor 2416. Reactor 2416 comprises a reactor chamber 2419, wherein solid Si 2398 is provided inside the reactor chamber 2419. The solid Si 2398 is preferably provided in form of particles.

The solid Si 2398 particles preferably have a length between 1 mm and 50mm and preferably between 1 mm and 40mm and highly preferably between 1 mm and 15mm and most preferably between 1 mm and 5mm or 10mm. The solid Si 2398 is preferably crushed by means of a crushing device (not shown). The crushing device can be part of the present system. The crushing device is preferably a jaw crusher or a water pulse crusher. The crushing device preferably continuously provides Si particles. This also applies to following figures.

With respect to fig. 18 and the remaining figures it must be noted that fluid outlet 216 and fluid inlet 2417 are schematically shown only, other fluid inlets and/or outlets do not have to be explicitly mentioned and/or shown.

The reactor 2416 preferably outputs at least Chlorosilanes 2394. The arrows indicate that the Chlorosilanes 2394 can be fed into CVD SiC reactor 850a and/or 850b.

Additionally the dotted arrow shows that further substances can be optionally fed into the CVD SiC reactor 850a (the same applies to the further CVD SiC reactor 850b). The further substances can be e.g. a c-bearing molecule, in particular CH4 (methane), and/or H2 (hydrogen). It is also possible to feed the further substance/s via the same inlet via which the Chlorosilanes are fed into the CVD SiC reactor 850.

According to a further preferred embodiment of the present invention an exchange device 2460 is optionally provided for exchanging 3-15% Vol. of the second fluid 964. The second fluid 964 preferably comprises H2, Methane, HCI, Chlorosilane, wherein the ration of the composition ((H2:Methane:HCI:Chlorosilane) of the second liquid is preferably between 3:1 :0, 1 :0, 1 Vol. and 7:1 :0, 1 :0, 1 Vol. it is alternatively possible to provide an absorber device (cf. fig. 25 ref. 2436) for removing further impurities, e.g. phosphor, dust and/or metal/s. Both the exchange device 2460 and the absorber device 2436 are optional but could be also part of the following figures. With respect to the exchange device 2460 it is also possible to establish that functionality by removing 3-15% Vol of the second fluid 964 and adding the same amount of the removed substances via one or more other input devices, in particular input path 2462. Thus, it is possible that the exchange device 2460 is only a removing device for removing 3-15% Vol. of the second fluid 964. This also applies to following figures.

Fig. 19 shows a further detailed example of the system according to the present invention. According to fig. 19 a separating unit 602 is provided downstream the reactor 2416 as part of the vent gas recycling unit 600. The separating unit 602 is preferably configured for separating the generated Chlorosilanes 2394 and the third fraction 2401 of the vent gas mixture 2400 and the fourth fraction of the vent gas mixture 2400 into a first fluid 962 and into a second fluid 964. The first fluid 962 is preferably fed to a storage unit, in particular a first fluid storage unit 2412, or to the CVD SiC reactor 850a and/or to another CVD SiC reactor 850b. The second fluid 964 is preferably fed to another storage unit, in particular a second fluid storage unit 2414, or to the CVD SiC reactor 850a and/or to another CVD SiC reactor 850b.

Additionally the separating unit 602 could be configured according to a further preferred embodiment for reducing the amount of metal impurities within the generated Chlorosilanes below 20ppmw and preferably below 10ppmw and highly preferably below 5ppmw and most preferably below 1 ppmw. The removed metal impurities are preferably feedable to a waste storage 2426.

Additionally the dotted arrow 2462 shows that further substances can be optionally fed into the CVD SiC reactor 850a (the same applies to the further CVD SiC reactor 850b). The further substances can be e.g. a c-bearing molecule, in particular CH4 (methane), and/or H2 (hydrogen). Additionally, it is possible to feed the Chlorosilanes and the second fluid via a common gas inlet into the CVD SiC reactor. It is also possible to feed the further substance/s via the same inlet via which the Chlorosilanes and/or the second liquid is/are fed into the CVD SiC reactor 850. This also applies to following figures.

Fig. 20 shows a further detailed example of the system according to the present invention. The further CVD SiC reactor 850b is not shown in this figure, however it has to understood that the treated vent gas fraction could be additionally or alternatively provided to such a further CVD SiC reactor 850b in case such a further CVD SiC reactor 850b is desired (this also applies to the further figures).

Even if a waste storage 2426 is provided as part of the vent gas recycling unit 600 after the metal removing device 2425 it is still possible that separating unit 602 is also connected to said waste storage 2426 or to another waste storage.

The vent gas recycling unit 600 preferably comprises a further separating unit 612, wherein the further separating unit 612 preferably comprises a metal removing device 2425, wherein the metal removing device 2425 preferably removes remaining metal impurities from the first fluid 962. The first fluid 962 is preferably fed from the metal removing device 2425 to a STC and TCS dividing device 2421 . Alternatively, the first fluid could be fed into the CVD SiC reactor 850a. STC is preferably stored in a STC storage 2422 and TCS is preferably stored in a TCS storage 2424.

The further separating unit 612 could be configured according to a further preferred embodiment for reducing the amount of metal impurities, in particular B, Al, P, Ti, V, Fe and/or Ni, within the first fluid 962, in particular the Chlorosilanes below 20ppmw, in particular of one or multiple or all of the metals B, Al, P, Ti, V, Fe and/or Ni, and preferably below 10ppmw, in particular of one or multiple or all of the metals B, Al, P, Ti, V, Fe and/or Ni, and highly preferably below 5ppmw, in particular of one or multiple or all of the metals B, Al, P, Ti, V, Fe and/or Ni, and most preferably below 1ppmw, in particular of one or multiple or all of the metals B, Al, P, Ti, V, Fe and/or Ni. The removed metal impurities are preferably feedable to a waste storage 2426.

TCS and/or STC can be fed from STC storage 2422 and/or TCS storage 2424 into the CVD SiC reactor 850. Volume or mass of the STC and/or TCS which is fed into the CVD SiC reactor is preferably controlled, in particular by means of a mass flux controller respectively one mass flux controller for STC and /or one mass flux controller for TCS. Fig. 21 schematically indicates that the separating unit 602 of the vent gas recycling unit 600 is not or not directly coupled with a waste storage 2426, in particular it is possible that the separating unit 602 is not configured for separating or removing metal impurities. Alternatively it is possible to remove the amount of metal impurities within the generated Chlorosilanes only with the further separating unit 612 below 20ppmw and preferably below 10ppmw and highly preferably below 5ppmw and most preferably below 1 ppmw.

Fig. 22 schematically shows that a Si supply unit 2432 can be part of the inventive system. The Si supply unit 2432 is preferably a Si storage for storing and providing Si particles. Alternatively the Si supply unit 2432 can be a crushing device, in particular a jaw crusher and/or a water pulse crusher. However, it is also possible that the Si supply unit 2432 comprises a Si storage for storing and providing Si particles and a crusher device, in particular a jaw crusher and/or a water pulse crusher, for crushing Si.

Fig. 23 schematically shows that - additionally to the Si supply unit 2432- a HCI supply unit 2434 can be provided for supplying HCI, in particular from a HCI storage, into the reactor 2416. It is also possible that the HCI supply 2434 is present in case no Si supply unit 2432 is provided. The HCI supply unit 2434 can be used to add the amount of HCI removed from the system, in particular removed by the exchange device 2460 (cf. Fig. 19) respectively removing device.

Fig. 24 shows Si supply unit 2432, HCI supply unit 2434 and a vent gas storage unit 2450 coupled to the reactor 2416. It has to be understood that the Si supply unit 2432, the HCI supply unit 2434 and the vent gas storage unit 2450 are optional. However, it is possible to have one of them or two of them or all of them present according to the invention. The vent gas storage unit 2450 is configured to store vent gas and to provide vent gas, in particular above the condensation temperature of the vent gas. This embodiment is beneficial since during start up and/or shut down of the CVD SiC reactor 850 a continuous vent gas supply to the reactor 2416 can be established. Thus, the production of Chlorosilanes can take place even if the CVD SiC reactor does not provide vent gas.

Additionally or alternatively, HCI can be supplied during start up and/or shut down of the CVD SiC reactor 850. Since HCI reacts with Si to Chlorosilanes.

Additionally or alternatively Chlorosilanes, in particular TCS, are supplied to the reactor 2416, in particular from TCS storage 2422. A combined supply of Chlorosilanes, in particular TCS, preferably from TCS storage 2422, and HCI, preferably from HCI supply 2434, to the reactor 2416 is also possible.

Furthermore, in the case of HCI, vent gas or Chlorosilane supply further Chlorosilanes are produced.

It is further possible to supply a c-bearing molecule, in particular methane, and H2 into the reactor, in particular for holding the reactor in an idle state. It is herewith beneficial to also heat the reactor 2416, in particular the reactor chamber 2419.

All that optional or additional supply steps are beneficial since the reactor 2416 does not have to shut down during start up or shut down of the CVD SiC reactor.

Reference number 2428 indicates a paused/reduced vent gas mixture feeding from the CVD SiC reactor e.g. due to start up or shut down phase.

Fig. 25 shows that the second fluid 964 can be fed through an absorber device 2436 for removing phosphor, dust and/or metal impurities. The removed substances are preferably fed into a washer 2438 and the resulting substances can be burned in a combustion unit 2440, in particular a flare. The combustion unit 2440 is preferably used to provide heat for heating the reactor 2416, in particular in case no exothermic reaction takes place inside the reactor 2416 or in case the reactor is in a startup phase.

The systems respectively CVD SiC production reactor/s described with respect to Fig. 18 to 25 are able to carry out a preferred method of the present invention for the production of SiC. Said method preferably comprises at least the steps:

Providing a vent gas mixture 2400, wherein the vent gas mixture 2400 is preferably generated during SiC production and highly preferably generated during CVD SiC production, wherein at least a first fraction of the vent gas mixture is HCI, wherein a second fraction of the vent gas mixture consists of vent gas Chlorosilanes, in particular STC and/or TCS, wherein a third fraction 2401 of the vent gas mixture 2400 comprises or consists of H2 2402 and wherein a fourth fraction of the vent gas mixture 2400 comprises or consists of at least one C-bearing-molecule, in particular methane, 2404. The method preferably also comprises a step of providing solid Si inside a reactor chamber, wherein the solid Si comprises metal impurities of more than 1000ppmw. The method preferably also comprises a step of forwarding at least the second fraction of the vent gas mixture 2400 and the third fraction of the vent gas mixture 2400 into the reactor chamber and/or the first fraction of the vent gas mixture 2400. The method preferably also comprises a step of generating Chlorosilanes inside the reactor chamber by reacting the second fraction of the vent gas mixture, in particular STC and/or TCS, and the third fraction 2401 of the vent gas mixture 2400 and the solid Si and/or by reacting the first fraction of the vent gas mixture 2400 and the solid Si.

The method preferably also comprises the steps: Forwarding at least the generated Chlorosilanes 2394 into a process chamber 856a of the CVD SiC production reactor 850a, and forwarding at least one C-bearing molecule into the CVD SiC production reactor 850a, and producing SiC inside the process chamber 856a of the CVD SiC production reactor 850a by reacting the generated Chlorosilanes and C from the at least one C-bearing molecule on at least one deposition surface. Alternatively the method preferably also comprises the steps: Forwarding at least the generated Chlorosilanes 2394 into a process chamber 856b of a further CVD SiC production reactor 850b, and forwarding at least one C-bearing molecule into the further CVD SiC production reactor 850b, and producing SiC inside the process chamber 856 of the further CVD SiC production reactor 850b by reacting the generated Chlorosilanes and C from the at least one C-bearing molecule on at least one deposition surface.

With respect to the before mentioned figures the process according to the present invention can be divided into a phase “during operation of the CVD SiC reactor” and a phase “ during start up or shut down”. By means of example, both phases are described in the following with additional or alternative features (with respect to the description of Fig. 18-25).

During operation of the SiC CVD reactors under deposition of SiC, the process gas preferably comprises or consisting of STC, TCS, H2, CH4 and HCI. The process gas leaves the SiC CVD reactor chamber as “vent gas” and is preferably cooled down to a temperature of about 200°C, in particular by means of heat exchangers. This vent gas stream remains completely in gas phase. The complete vent gas stream is then continuously fed into the reactor, in particular bed reactor and preferably fixed bed reactor. The reactor preferably comprises a steel vessel, in particular with dimensions of more than 5m height and preferably of 8 m height or of more than 8m height and highly preferably of 10m or more than 10m height, and a diameter of 1 m or of more than 1 m, in particular of 1,5m or of more than 1 ,5m or preferably of 2m or of more than 2m or between 1 ,7m and 2,3m. In the reactor there is a bed of silicon. The vent gas is introduced in the lower part of the reactor, which allows the vent gas to flow optimally through the silicon bed. The contact of the gas phase with silicon leads to an exothermic chemical reaction with the formation of a new STC, TCS, H2, CH4 and HCI gas mixture, in which the HCI content is significantly reduced and the chlorosilane content, comprising or consisting of STC and/or TCS, is increased. The silicon bed is preferably kept at a temperature of 400-450°C and a pressure between 1 ,2 and 2 bar, in particular 1 .5 bar, which ensures optimum HCI conversion. The proportion of chlorosilanes in gas phase increases in the reactor with degradation of silicon. To cool the reactor chamber in the reactor, the reactor is preferably operated with a cooling water jacket.

Furthermore, liquid chlorosilane mixture of STC and/or TCS can be introduced in the upper part of the reactor. On the one hand, this process serves to cool the reaction chamber and thus to control the reaction temperature, and on the other hand, metal chloride constituents, such as ferric chloride and aluminum chloride, are thereby transferred from the gas phase to a solid particle form.

After vent gas leaves the reactor, the solid components formed are preferably separated from the gaseous fluid, in particular by means of a solids separation system preferably using cyclones and/or filters.

In addition, a downstream gas scrubber can be provided, which is preferably operated with liquid chlorosilane. This embodiment is beneficial since it ensures that even very small solid components can be washed out of the gas stream, thus further reducing the metal chloride content of the fluid.

After separation of the solid components from the gas stream, the condensable components of the process gas are preferably liquefied by cooling. The liquid phase is preferably separated and contains mainly the chlorosilanes STC and TCS as well as dissolved portions of HCI, H2 and CH4 and trace components of chlorosilane boilers, such as hexachlorodisilane, and metal chlorides.

The gas phase preferably comprises or consists predominantly of H2, CH4 and minor amounts of HCI, STC and TCS.

For further purification of the chlorosilanes from metal chlorides and separation into the individual components STC and TCS, the liquid phase is preferably subjected to one or multiple further distillation steps and purified STC and/or TCS is/are collected individually in tanks.

The gas phase is preferably returned to the CVD SiC reactor or another CVD SiC reactor or a storage unit, in particular a tank, after separation of liquid components. Preferably no process gas leaves the SIC CVD reactor chamber during start up or shut down phases of the SIC CVD reactor/s. No CVD SIC reactor vent gas flow can be continuously introduced into the reactor if taken directly from the CVD SiC reactor.

The reactor preferably is a steel vessel with dimensions of 10m in height and a diameter of about 2m. In the reactor 2416 there is a bulk of silicon 2398. Gas comprising or consisting mainly of H2 and CH4 and small amounts of STC, TCS and HCI is introduced in the reactor, in particular in the lower part of the reactor 2416. The bulk silicon 2398 is preferably maintained at a temperature of 400-450°C and a pressure of 1 .5 bar. Due to the lack of exothermic reaction between silicon, HCI and chlorosilanes, to heat the bulk of silicon 2398 in the reactor, the gas is preferably heated up to 800°C or to a temperature between 700°C and 900, in particular to a temperature between 750°C and 850°C, in particular at the gas inlet or prior to the gas inlet.

The gas phase is preferably returned to the CVD SiC reactor or another CVD SiC reactor or a storage unit, in particular a tank, after separation of liquid components. Fig. 26a shows a polycrystalline SiC piece 2800, in particular an ingot or boule. Reference number 2814 schematically refers to a crystallite at least mainly orientated into radial direction (R). Line 2816 schematically illustrates a dividing plane along which the SiC Piece 2800 is divided in two pieces. In the shown example the smaller section of the SiC piece 2800 respectively the section above line 2816 forms a “second substrate” 2822 according to the present invention respectively a carrier wafer 2822.

Fig. 26b shows a first substrate 2317 and a second substrate 2822 according to the present invention. The first substrate 2822 is preferably a monocrystalline SiC crystal and the second substrate is preferably a polycrystalline SiC structure, wherein the first substrate 2317 and the second substrate 2822 are both at least partially (vol.) and preferably mainly (vol.) or most preferably entirely grown in radial direction.

The first substrate 2317 preferably comprises ions arranged on a layer 2418 for dividing a thin substrate layer 2818 from the first substrate 2317. The ions can be expanded during a later heating process and locally cause the crystal structure to crack and thereby divide the first substrate 2317 into two pieces. Such a dividing is known as “Smart-Cut-Process”.

Fig. 26c shows the first substrate 2317 and the second substrate 2822 bonded together. Arrow “H” indicates the height direction respectively the direction in which the top surface of second substrate 2406 and bottom surface of second substrate 2408 are arranged in a distance to each other as well as the top surface of first substrate 2801 and bottom surface of first substrate 2803 are arranged in a distance to each other.

Fig. 26d shows the composite wafer 2820 of the present invention after the step of dividing the thin substrate layer 2818 from the first substrate 2317.

Fig. 26e shows an optional step of growing an epi-layer 2319 on top of the thin substrate layer 2818.

The epi-layer 2319 is a monocrystalline SiC crystal layer 2319 which is produced on the thin substrate layer 2818, wherein the monocrystalline SiC crystal layer 2319 is grown by means of epitaxy and wherein the thin substrate layer 2818 has a thickness of less than 1 pm and wherein the monocrystalline SiC crystal layer 2319 preferably has a thickness of 0,5pm to 20pm, in particular of 1 pm to 15pm or 1 pm to 12pm or preferably 2pm to 15pm or 2pm to 12pm.

Thus, in view of Fig. 26a-d and Fig. 27a-d the method for the production of a compound respectively composite wafer respectively or multi-substrate wafer 2820 according to the present invention preferably comprises the steps of providing a first substrate, providing a second substrate 2822 and bonding the first substrate 2317 and the second substrate 2822 together. The first substrate 2317 is preferably a monocrystalline SiC crystal, wherein the monocrystalline SiC crystal 2317 is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis, wherein the monocrystalline SiC crystal 2317 has a preferably flat top surface 2801 , a preferably flat bottom surface 2803 and a connecting-surface 2802 connecting the top surface 2801 and bottom surface 2803, wherein the c-axis is aligned in an angle between 0° and 8° and preferably in an angle between 2° and 6° with respect to a normal on the top surface 2801 . The second substrate 2822 preferably comprises or consists of polycrystalline SiC, in particular 3C-SiC, wherein the at least 60% [volume] of the polycrystalline SiC is grown in radial direction, wherein the second substrate 2822 has a specific electrical resistance of less than 15m0hmcm, bonding the first substrate 2317 and the second substrate 2822 together.

The method preferably also comprises the step of transforming the first substrate 2317 in a thin substrate layer 2818 by reducing the thickness of the first substrate 2317 to less than 20pm, wherein the step of reducing the thickness of the first substrate 2317 to less than 20 pm is carried out after the first and second substrate 2822 are bonded together.

Thus, the present invention refers to a multi-substrate wafer 2820. Said multi-substrate wafer 2820 comprises at least a first substrate 2317 and a second substrate, wherein the first substrate 2317 and the second substrate 2822 are bonded together, wherein the first substrate 2317 is a monocrystalline SiC crystal 2317, wherein the second substrate 2822 comprises polycrystalline 3C-SiC, wherein the at least 30% [volume], in particular at least 50% [volume] and preferably at least 70% [volume], of the polycrystalline 3C-SiC is grown in radial direction around at least one or exactly one central element 2857, wherein the central element 2857 preferably comprises or consists of SiC, wherein the second substrate 2822 has a specific electrical resistance of less than 15m0hmcm, wherein the second substrate 2822 is at least nitrogen doped, wherein more than 10¹⁸ nitrogen atoms per cm³ are present inside the second substrate 2822 due to doping.

Fig. 27a corresponds to Fig. 26a.

Fig. 27b shows the first substrate 2317 comprising an ion layer 2418 for removing the thin layer 2818, wherein the ion layer 2418 is arranged in a larger distance compared to fig. 26b.

Fig. 27a-d show that the thin substrate layer 2818 preferably has a thickness between 2pm and 20pm, in particular between 5pm and 12pm, and wherein the thin substrate layer 2818 highly preferably comprises 10¹⁵-10¹⁶ nitrogen atoms per cm³. Thus, the substrate layer 2818 can act as n-Drift region and the second substrate can act as n+ substrate in case of an electric device, like e.g., a SCHOTTKEY Diode.

Fig. 28 show a high-resolution photo of a section of a second substrate 2822. Reference numbers 2814 refer to crystallites having a length extension of more than 5pm and refence numbers 2415 refer to crystallites having a length extension of less than 5pm.

Fig. 29 shows a modified version of fig. 28. Multiple large crystallites 2814 are identified and the length direction of said large crystallites 2814 is indicated by dotted lines. An overall radial direction R indicates the direction of expansion of the polycrystalline SiC during growth.

Fig. 30a shows a state-of-the-art carrier wafer 2500. Said carrier wafer 2500 is grown by means of epitaxy in a flat growth substrate 2502. The growth direction 2504 is only in one direction respectively orthogonal to the plane surface of growth substrate 2502. Fig. 30a also schematically shows that the length direction of the plurality of large crystallites 2506 is mainly orientated in one direction.

Fig. 30b shows that a central element respectively growth substrate 2857 provides a growth face extending in 3D space and therefore not only in 2D space as shown in fig. 30b.

Fig. 30b and 30c/d show that the central element I SiC growth substrate 857 can have multiple shapes.

With respect to fig. 30b, 30c and 30d it has to be understood that “radial” does not only apply in cases, in which the central element I SiC growth substrate 2857 has a circular shape (cross-sectional) respectively in cases in which a “radius” is present. “Radial” describes in the context of the present invention the growth direction during expanding of the polycrystalline structure, along a lateral surface respectively growth face. Thus, the radial direction R of the polycrystalline structure can be preferably determined for multiple sections of the polycrystalline structure 2822, wherein each section 2420 preferably comprises in its center the radial direction R of the respective section 2420, wherein the respective section 2420 preferably has a width of less than 500pm, in particular of less than 300pm and preferably of less than 100pm, wherein the alignment between the radial direction R of the polycrystalline structure 2822 and the length direction L of the individual crystallite 2814 which extends more than 5pm, in particular more than 10pm and preferably more than 20pm, is limited to crystallites 2814 present in a respective section 2420 and the radial direction R of the respective section 2420. The central element / SiC growth substrate 2857 is preferably also grown in radial direction, in particularly removed from a radially grown section of a SiC piece 2800, in particular ingot or boule.

Fig. 30d schematically shows that the orientation of the large crystallites 2814 changes in circumferential direction of the polycrystalline crystal structure 2822.

Fig. 31 shows an enlarged section of Fig. 28. Said section shows a crystallite 2814, wherein the boundary 2422 of said crystallite 2814 is marked with a thin white line. A straight white line connects two points of the crystallite 2814 which are arranged in the largest distance to each other. Thus, the white line represents the length direction of the crystallite 2814. Said definition of the length direction L of the crystallite 2814 is used with respect to all embodiments of the present invention.

Fig. 32a and 32b schematically show that band shaped or line shaped or straight elements 2412 representing growth rings or growth lines are present in the grown SiC piece 2800. The plurality of line shaped, in particular at least partially curved, in particular at least partially circular or at least partially arc shaped, and/or at least partially straight elements 2412 is preferably formed in a distance of at least 1 nm to the preferably flat top surface 2406 inside, the preferably flat bottom surface 2408 and the connecting-surface 2410.

At least one and preferably at least two curved, circular, straight and/or arc-shaped elements 2412 have at least a length in circumferential direction of the second substrate 2822 of at least 10 nm, in particular at least 20nm or 50nm or 100nm. Preferably are at least one or two curved, circular, straight and/or arc-shaped elements 2412 extending entirely around the central element I SiC growth substrate 2857.

List of reference signs 298 UPSIC rods

398 UPSiC granules

102 Hydrogen gas 400 Acid etching unit

198 Feed gas mixture 496 Scrubber inlet water

206a first electrode 497 Flare combustion gas

206b second electrode 498 UPSiC etched granules

216 Vent gas outlet respectively gas 500 Vent gas treatment unit outlet unit

502 Vent gas filter unit

296 Vent gas

504 Filtered vent gas 506 Scrubber unit 636 further compressor

512 Scrubbed vent gas

514 Flare unit 696 HCI liquid discharge

596 Flare exhaust gas 698 Recycled vent gas

598 Scrubber outlet water 850 manufacturing device or CVD unit or CVD reactor respectively SiC

600 Vent gas recycling unit production reactor, in particular SiC PVT

602 Cold distillation unit respectively source material production reactor separator unit respectively separating unit

851 first feeding device respectively first

604 Si-bearing liquid mixture feed-medium source

606 HMW distillation unit 852 second feeding device respectively

608 HMW liquids discharge second feed-medium source

610 Cold distillation gas 854 mixing device

612 Cryogenic distillation unit or further 856 process chamber separator unit 857 separating element or SiC growth

616 H/C-beari ng gas mixture substrate or deposition substrate

861 deposition surface of SiC growth

620 Si-bearing gas mixture substrate or SiC growth surface

622 Si detector unit respectively Si mass flux measurement unit 862 base plate

624 first storage and/or conducting 864 bell jar element 864a side wall section

626 second storage and/or conducting 864b top wall section element

866 gas inlet unit

628 mixture of chlorosilanes storage

867 reflective coating and/or conducting element

872 cooling fluid guide unit

630 HCI storage and/or conducting element 926 control device or control unit

632 H2 and C storage and/or 929 control unit conducting element

930 boundary surface

634 first compressor 932 cross-sectional area 2414 second storage and/or conducting element

948 additional or alternative path to

2415 Crystallites having length extension further SiC production reactor 950 of less than 5pm

949 additional or alternative further path 2416 bed reactor to further SiC production reactor 950 2417 gas inlet

950 further SiC production reactor 2418 layer respectively CVD reactor for the 2419 reactor chamber production of SiC 2420 section

2421 STC and TCS dividing device

952 further process chamber of further

2422 STC storage SiC production reactor

2424 TCS storage

954 heating unit 2425 metals removing device

2426 waste storage

956 mixture of chlorosilanes

2428 paused/reduced vent gas mixture

962 first fluid feeding

2430 TCS storage to bed reactor path

964 second fluid

2432 SI supply unit

966 reaction space 2434 HCI supply unit

1000 feed gas unit 2436 second fluid treatment unit I absorber

1120 Mass flow meter

2438 washer

2317 first substrate 2440 combustion unit I flare

2319 monocrystalline SiC crystal I epi 2450 vent gas storage layer 2460 exchange device

2394 Chlorosilanes 2462 dotted arrow I input path

2398 Si 2500 sate of the art carrier wafer

2400 vent gas conduit with vent gas 2502 flat growth substrate mixture 2504 growth direction

2401 further fraction or thirst fraction of 2506 plurality of large crystallites vent gas mixture 2800 SiC piece

2406 top surface of second substrate 2801 top surface of first substrate 2408 bottom surface of second substrate 2802 connecting surface 2410 connecting surface 2803 bottom surface of first substrate

2412 first storage and/or conducting 2812 curved, circular and/or arc-shaped element elements 2814 Crystallites having length extension 2860 clamping and/or welding of more than 5pm 2862 electric isolator

2864 C-bearing gas

2816 dividing plane 2866 excess H2

2817 bed reactor outlet 2868 HCI output

2818 thin substrate layer

2820 composite wafer

2822 second substrate I carrier wafer I polycrystalline structure

2824 holding section

2826 circumferential direction

2828 coil CA central axis

2830 conductor

PL particle length

2832 first end of conductor

2834 second end of conductor

2836 turns

2838 core center axis D1 first direction

2840 SiC growth substrate center axis OD1 opposite to first direction

2842 cooling fluid cooling unit D2 second direction

2844 generator D3 third direction

2846 heat radiation element D4 fourth direction

2848 tubes D5 fifth direction

2850 coupling element D6 sixth direction

2852 inner surface of bell jar DI distance

2854 first end of SiC growth substrate D Depth

2856 second end of SiC growth substate ML Main body length

2858 coupling unit W Width

Claims

1 . CVD SiC production reactor (850), at least comprising a process chamber (856), a gas inlet unit (866) for feeding one feed-medium or multiple feed-mediums into a reaction space (966) of the process chamber (856) for providing a source medium, wherein the gas inlet unit (866) is coupled with at least one feed-medium source (851), or wherein the gas inlet unit (866) is coupled with at least two feed-medium sources (851 , 852), or wherein the gas inlet unit (866) is coupled with at least three feed-medium sources (851 , 852, 853), a gas outlet unit (216) for removing a vent gas mixture from the reaction space of the process chamber (856), a holding section (2824) for holding at least or exactly one SiC growth substrate (857) inside the reaction space (966) in a holding position, a heating unit (954) for heating a deposition surface (861) of the at least or exactly one SiC growth substrate, wherein the heating unit (954) is configured to heat the at least or exactly one SiC growth substrate (857) from at least multiple sides, in particularly along the entire circumference (2826) of the at least or exactly one SiC growth substrate (857).

2. SiC production reactor (850) according to claim 1 , characterized in that the heating unit (954) is configured to inductively heat the at least or exactly one SiC growth substrate (857).

3. SiC production reactor (850) according to claim 1 or 2, characterized in that the heating unit (954) is configured to provide alternating current with a frequency above 1 kHz, in particular with a frequency above 20kHz and preferably with a frequency above 50kHz and most preferably with a frequency above 100kHz.

4. SiC production reactor (850) according to claim 2 or 3, characterized in that the heating unit (954) comprises a coil (2828) wherein the coil (2828) is formed by a longitudinal conductor (2830) having a first end (2832) and a second end (2834), wherein the conductor (2830) forms a plurality of turns (2836) between the first end (2832) and the second end (2834).

5. SiC production reactor (850) according to claim 4, characterized in that the conductor (2830) is made of tantalum.

6. SiC production reactor (850) according to claim 4, characterized in that the turns (2836) form a core, wherein the core has a core center axis (2838), and wherein the at least or exactly one SiC growth substrate (857) has a SiC growth substrate center axis (2840), wherein the coil (2828) is arranged in such a manner that the core center axis (2838) and the SiC growth substrate center axis (2840) are parallel or coaxial during operation of the SiC production reactor (850).

7. SiC production reactor (850) according to claim 4 or 6, characterized in that the conductor (2830) is formed by a pipe, wherein the pipe is made of metal and wherein the pipe is configured to conduct a fluid from the first end (2832) of the conductor (2830) to the second end (2834) of the conductor (2830) for cooling the conductor (2830).

8. SiC production reactor (850) according to claim 1 , characterized in that the heating unit (954) is configured to emit heat radiation.

9. SiC production reactor (850) according to claim 8, characterized in that the heating unit (954) comprises at least 2 and preferably at least 3 and highly preferably at least 4 heat radiation elements (2846a, b, c) arrange around the holding position.

10. SiC production reactor (850) according to claim 8, characterized in that a glas tube (2848), in particular made of quartz, is arranged between the heating unit (954) and the holding position for separating the reaction space (966) from the heating unit (954), in particular for shielding the heating unit (954) during operation from the source medium.

11 . SiC production reactor (850) according to any of the preceding claims, characterized in that the process chamber (856) is surrounded by a bell jar (864), wherein an inner surface of the bell jar is polished or coated, in particular silver coated.

12. SiC production reactor (850) according to claim 11 , characterized in that the bell jar (864) comprises a cooling fluid guide unit (872) for guiding a cooling fluid.

13. SiC production reactor (850) according to any of the preceding claims, characterized in that the holding section (2824) for holding at least or exactly one SiC growth substrate (857) comprises a first metal electrode (206a) for coupling to a first end (2854) of the at least or exactly one SiC growth substrate (857) and a second metal electrode (206b) for coupling to a second end (2856) of the at least or exactly one SiC growth substrate (857), wherein the first and second electrode (206a, 206b) are configured to conduct electric power through the at least or exactly one SiC growth substrate (857) for heating the at least or exactly one SiC growth substrate (857) by means of resistive heating, in particular during an initial heating phase and/or a cool down phase.

14. SiC production reactor (850) according to any of the preceding claims, characterized in that the holding section (2824) for holding at least or exactly one SiC growth substrate (857) comprises a first electric isolator (2862a) for coupling to a first end (2854) of the at least or exactly one SiC growth substrate (857) and/or a second electric isolator (2862b) for coupling to a second end (2856) of the at least or exactly one SiC growth substrate (857), wherein the first electric isolator (2862a) and/or the second electric isolator (2862b) prevent flow of electric power via the first end (2854) and/or the second end (2856) of the at least or exactly one SiC growth substrate (857).

15. SiC production reactor (850) according to any of the preceding claims, characterized in that at least a first fraction of the vent gas mixture is HCI, a second fraction of the vent gas mixture consists of vent gas Chlorosilanes, in particular STC and/or TCS, a third fraction (2401) of the vent gas mixture (2400) comprises or consists of H2 (2402) and a fourth fraction of the vent gas mixture (2400) comprises or consists of at least one C-bearing-molecule, in particular methane, (2404),

16. SiC production reactor (850) according to any of the preceding claims, characterized in that a vent gas recycling unit (600) is provided, wherein the vent gas recycling unit comprises a bed reactor, wherein the bed reactor (2416), in particular a fixed bed reactor or a fluidized bed reactor, is provided for generating Chlorosilanes (2394), wherein the bed reactor (2416) comprises a bed reactor input opening (2417), wherein the bed reactor input opening (2417) is coupled via a pipe (2400) with the gas outlet unit (216) for conducting the vent gas mixture into the bed reactor (2416), wherein the bed reactor (2416) comprises a reactor chamber (2419) for receiving solid Si (2398) and for reacting the SI (2398) with the first fraction of the vent gas mixture, wherein the solid Si (2398) comprises metal impurities of more than 10OOppmw,

17. SiC production reactor (850) according to claim 16, characterized in that the bed reactor (2416) comprises a bed reactor outlet (2817), wherein the bed reactor outlet (2817) is coupled with the gas inlet unit (866) for conducting generated Chlorosilanes into the reaction space (966).

18. SiC production reactor (850) according to claim 16 or 17, characterized in that the vent gas recycling unit (600) further comprises a separating unit (602) is provided for reducing the amount of metal impurities within the generated Chlorosilanes below 20ppmw and preferably below 10ppmw and highly preferably below 5ppmw and most preferably below 1 ppmw and for separating the generated Chlorosilanes (2394) and the third fraction (2401) of the vent gas mixture (2400) and the fourth fraction of the vent gas mixture (2400) into a first fluid (624) and into a second fluid (626) or the vent gas recycling unit (600) further comprises a separating unit (602) and a Chlorosilane distillation column (612) are provided, wherein the separating unit (602) is configured for removing a first amount of metal impurities from the Chlorosilanes and for separating the generated Chlorosilanes (2394) and the third fraction (2401) of the vent gas mixture (2400) and the fourth fraction of the vent gas mixture (2400) into a first fluid (624) and into a second fluid (626) and wherein the Chlorosilane distillation column (612) is configured for removing a second amount of metal impurities from the Chlorosilanes.

19. SiC production reactor (850) according to claim 16 or 17 or 18, characterized in that the vent gas recycling unit (600) further comprises a further separating unit (2421) for separating STC and TCS, and a first storage and/or conducting element (624) for connecting the separating unit (602) with the further separating unit (612), and a STC storage (2422) and a TCS storage (2424), wherein the further separating unit (612) is coupled with the STC storage (2422) and the TCS storage (2424), wherein the STC storage (2422) and/or the TCS storage (2424) forms a section of a Chlorosilanes mass flux path for conducting STC and/or TCS into the process chamber (856).

20. SiC production reactor (850) according to any of the claims 1 to 14, characterized in that a vent gas recycling unit (600), wherein the vent gas recycling unit (600) is connected to the gas outlet unit, wherein the vent gas recycling unit (600) comprises at least a separator unit (602) for separating the vent gas mixture into a first fluid (962) and into a second fluid (964), wherein the first fluid (962) is a liquid and wherein the second fluid (964) is a gas, wherein a first storage and/or conducting element for storing or conducting the first fluid (962) is part of the separator unit (602) or coupled with the separator unit (602) and wherein a second storage and/or conducting element for storing or conducting the second fluid (964) is part of the separator unit (602) or coupled with the separator unit (602), wherein the vent gas recycling unit (600) comprises a further separator unit (612) for separating the first fluid into at least two parts, wherein the two parts are a mixture of chlorosilanes and

- a mixture of HCI, H2 and at least one C-bearing molecule, and preferably into at least three parts, wherein the three parts are a mixture of chlorosilanes and

- HCI and

- a mixture of H2 and at least one C-bearing molecule, wherein the first storage and/or conducting element (624) connects the separator unit (602) with the further separator unit (612).

21 . SiC production reactor (850) according to claim 20, characterized in that the further separator unit (612) is coupled with a mixture of chlorosilanes storage and/or conducting element (628) and with a HCI storage and/or conducting element (630) and with a H2 and C storage and/or conducting element (632).

22. SiC production reactor according to claim 21 , characterized in that the mixture of chlorosilanes storage and/or conducting element (628) forms a section of a mixture of chlorosilanes mass flux path for conducting the mixture of chlorosilanes into the process chamber (856)

23. SiC production reactor according to claim 22, characterized in that a Si mass flux measurement unit (622) for measuring an amount of Si of the mixture of chlorosilanes is provided as part of the mass flux path prior to the process chamber (856), in particular prior to a mixing device (854), and preferably as further Si feed-medium source providing a further Si feed medium.

24. SiC production reactor according to claim 21 , characterized in that the mixture of chlorosilanes storage and/or conducting element (628) forms a section of a mixture of chlorosilanes mass flux path for conducting the mixture of chlorosilanes into a further process chamber (952) of a further SiC production reactor (950)

25. SiC production reactor according to claim 24, characterized in that the H2 an C storage and/or conducting element (632) forms a section of a H2 and C mass flux path for conducting the H2 and the at least one C-bearing molecule into the process chamber (850).

26. SiC production reactor according to claim 23, characterized in that a C mass flux measurement unit (618) for measuring an amount of C of the mixture of H2 and the at least one C-bearing molecule is provided as part of the H2 and C mass flux path prior to the process chamber (856), in particular prior to a mixing device (854), and preferably as further C feed-medium source providing a further C feed medium and/or the H2 an C storage and/or conducting element (632) forms a section of a H2 and C mass flux path for conducting the H2 and the at least one C-bearing molecule into a further process chamber (856) of a further SiC production reactor (950) and/or the second storage and/or conducting element (626) forms a section of the H2 and C mass flux path for conducting the second fluid, which comprises H2 and the at least one C-bearing molecule, into the process chamber (856), wherein the second storage and/or conducting element (626) and the H2 an C storage and/or conducting element (632) are preferably fluidly coupled and/or the second storage and/or conducting element (626) forms a section of a further H2 and C mass flux path for conducting the second fluid, which comprises H2 and the at least one C- bearing molecule, into the process chamber (856) and/or a further C mass flux measurement unit for measuring an amount of C of the second fluid is provided as part of the further H2 and C mass flux path prior to the process chamber (856), in particular prior to a mixing device (854).

27. SiC production reactor according to any of claims 20 to 26, characterized in that the second storage and/or conducting element (626) is coupled with a flare unit for burning the second fluid.

28. SiC production reactor according to any of claims 20 to 27, characterized in that the separator unit (602) is configured to operate at a pressure above 5bar and a temperature below -30°C, wherein a first compressor (634) for compressing the vent gas to a pressure above 5bar is provided as part of the separator unit (602) or in a gas flow path between the gas outlet unit (216) and the separator unit (602).

29. SiC production reactor according to any of claims 20 to 28, characterized in that the further separator unit (612) is configured to operate at a pressure above 5bar and a temperature below -30°C and/or a temperature above 100°C.

30. SiC production reactor according to claim 20 to 29, characterized in that the further separator unit (612) comprises a cryogenic distillation unit, wherein the cryogenic distillation unit is preferably configured to be operated at temperatures between -180C⁰ and - 40C°.

31 . Method for producing solid SiC, at least comprising the steps: providing a CVD SiC production reactor (850), in particular according to any of the preceding claims, providing at least or exactly one SiC growth substrate (857) inside the CVD reactor (850), holding the at least or exactly one SiC growth substrate (857) inside the reaction space (966) in a holding position by means of a holding section (2854), wherein the SiC growth substrate (857) forms a deposition surface (861) surrounding the SiC growth substrate (857) in circumferential direction of the SiC growth substrate (857), feeding one feed-medium or multiple feed-mediums into a reaction space of the process chamber (856) for providing a source medium, heating the deposition surface of the at least or exactly one SiC growth substrate by means of a heating unit transfer SiC from the source medium on a deposition surface of the at least or exactly one SiC growth substrate, wherein the heating unit is configured to heat the at least or exactly one SiC growth substrate from at least multiple sides, in particularly along an entire circumference of the at least or exactly one SiC growth substrate, in particular by means of heat radiation or induction, growing a SiC solid (211), removing a vent gas mixture from the reaction space of the process chamber (856).

32. Method according to claim 31 , characterized in that the heating unit inductively heats the at least or exactly one SiC growth substrate, wherein the heating unit is operated with alternating current with a frequency above 1kHz, in particular with a frequency above 20kHz and preferably with a frequency above 500kHz and most preferably with a frequency above 1 MHz.

33. Method according to claim 31 or 32, characterized in that the step of growing a SiC solid (211) comprises setting up a deposition rate, in particular perpendicular deposition rate, of more than 200 pm/h, in particular of more than 250 pm/h and preferably of more than 300 pm/h and highly preferably of more than 400 pm/h and most preferably of more than 500 pm/h or of up to 2000 pm/h.

34. Method for the production of a carrier wafer,

Providing a SiC solid produced according to a method according to claim 31 or claim 32 or claim 33,

Mechanically removing, in particular by means of sawing, the at least one SiC piece from the SiC solid (211), and

Mechanically removing the at least one SiC carrier wafer (2822) from the SiC piece (2800), in particular by means of sawing.

35. Method according to claim 34, characterized by the step of

Analyzing the SiC solid (211) to determine a crack-free section of the SiC solid (211), wherein the step of analyzing the SiC solid (211) is carried out prior to the step of mechanically removing, in particular by means of sawing, the at least one SiC piece from the SiC solid (211).

36. Method according to claim 35, characterized in that the step of analyzing the SiC solid (211 ) to determine a crack-free section of the SiC solid (211) is carried out by optical inspection, in particular by means of a caliper or threshold detection.

37. Method according to claims 35 or 36, characterized by the step of

Analyzing the SiC piece or the SiC carrier wafer to determine defects, in particular cracks.

38. Method according to claim 37, characterized in that the step of analyzing the SiC piece or the SiC carrier wafer to determine defects is carried out by means of a bend test, in particular a 2 point bend test, a 3 point bend test or a 4 point bend test, an eddy current testing and/or optical analyzing methods, in particular caliper testing or threshold testing or transmission testings.

39. Method for the production of a multi-substrate wafer at least comprising the steps:

Providing a first substrate (2317), wherein the first substrate (2317) is a monocrystalline SiC crystal, wherein the monocrystalline SiC crystal (2317) is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis, wherein the monocrystalline SiC crystal (2317) has a preferably flat top surface (2401), a preferably flat bottom surface (2403) and a connectingsurface (2802) connecting the top surface (2401) and bottom surface (2403), wherein the c-axis is aligned in an angle between 0° and 8° and preferably in an angle between 2° and 6° with respect to a normal on the top surface (2401) providing a second substrate (2822), wherein the second substrate is produced according to a method according to any of claims 34 to 38, wherein the second substrate (2822) consists of polycrystalline 3C-SiC, wherein the at least 60% [volume] of the polycrystalline SiC is grown in radial direction, wherein the second substrate (2822) has a specific electrical resistance of less than 15m0hmcm, bonding the first substrate (2317) and the second substrate (2822) together.

40. Method according to claim 39, characterized by transforming the first substrate (2317) in a thin substrate layer (2818) by reducing the thickness of the first substrate (2317) to less than 20pm, in particular less than 10 pm or less than 5 pm or less than 2 pm or less than 1 pm.

41 . Method according to claim 40, characterized in that the step of transforming the first substrate (2317) in a thin substrate layer (2818) by reducing the thickness of the first substrate (2317) to less than 20 pm is carried out after the first and second substrate (2822) are bonded together.

42. Method according to claim 39 or 40 or 41 , characterized by implanting ions into to the first substrate (2317) via the surface of the first substrate (2317) which is bonded to the second substrate (2822) before the first substrate (2317) and the second substrate (2822) are bonded together for defining a crack-plane inside the first substrate (2317) and heating at least the implanted ions to a temperature above 800°C, in particular to a temperature between 850°C and 1200°C, after the first substrate (2317) and the second substrate (2822) are bonded together for splitting the first substrate (2317) along the defined crack-plane into at least two pieces, wherein one piece is the thin substrate layer (2818).

43. Method according to any of claims 39 to 42, characterized in that the step of bonding the first substrate (2317) and the second substrate (2822) together is carried out by means of plasma bonding or argon beam bonding.

44. Method according to any of claims 39 to 43, characterized by growing a monocrystalline SiC layer (2319) by means of epitaxy onto the thin substrate layer (2818), wherein monocrystalline SiC layer (2319) has a thickness between 1 pm and 50 pm, in particular between 2 pm and 40 pm or between 3 pm and 30 pm or between 4 pm and 20 pm or between 5 pm and 10 pm.

45. Carrier wafer, in particular produced according to a method according to any of claims 34 to 38, characterized in that

The carrier wafer comprises at least 90% [volume] polycrystalline 3C-SiC or consists of polycrystalline 3C-SiC, wherein the at least 30% [volume], in particular at least 50% [volume] and preferably at least 70% [volume], of the polycrystalline 3C-SiC is grown in radial direction around at least one or exactly one central element (2857), wherein the central element (2857) preferably comprises or consists of SiC, wherein the carrier wafer (2822) has a specific electrical resistance of less than 30mOhmcm, in particular of less than 15m0hmcm, wherein the carrier wafer (2822) is at least nitrogen doped, wherein more than 10¹⁸ nitrogen atoms per cm³ are present inside the second substrate (2822) due to doping, wherein the carrier wafer (2822) forms a flat top surface (2406), a flat bottom surface (2408) and a connecting-surface (2410) connecting the top surface (2406) and bottom surface (2408) and wherein the connecting-surface (2410) is grinded to form a defined profile, in particular a R-Type Profile or a F-Type Profile.

46. Multi-substrate wafer (2820), in particular produced according to a method according to any of claims 39 to 44, at least comprising a first substrate (2317) and a second substrate, wherein the first substrate (2317) and the second substrate (2822) are bonded together, wherein the first substrate (2317) is a monocrystalline SiC crystal (2317), wherein the second substrate (2822) is a carrier wafer according to claim 45.

47. Multi-substrate wafer (2820) according to claim 46, characterized in that the monocrystalline SiC crystal (2317) is formed by a crystal structure, wherein the crystal structure defines a c-axis, wherein the crystal structure is grown perpendicular to the c-axis, wherein the monocrystalline SiC crystal (2317) has a preferably flat top surface (2401), a preferably flat bottom surface (2403) and a connectingsurface (2802) connecting the top surface (2401) and bottom surface (2403), wherein the c-axis is aligned in an angle between 0° and 8° and preferably in an angle between 2° and 6° with respect to a normal on the flat top surface (2401), wherein the monocrystalline SiC crystal (2317) consists of SiC of the 4H type.

48. Multi-substrate wafer (2820) according to claim 46 or 47, characterized in that the polycrystalline structure (2822) forms a plurality of band shaped or line shaped, in particular at least partially curved, in particular at least partially circular or at least partially arc shaped, and/or at least partially straight elements (2812).

49. Multi-substrate wafer (2820) according to claim 48, characterized in that the plurality of line shaped, in particular at least partially curved, in particular at least partially circular or at least partially arc shaped, and/or at least partially straight elements (2812) is formed in a distance of at least 1 nm to the preferably flat top surface (2406) inside, the preferably flat bottom surface (2408) and the connecting-surface (2410).

50. Multi-substrate wafer (2820) according to claim 48 or 49, characterized in that at least one and preferably at least two curved, circular and/or arc-shaped elements (2812) have at least a length in circumferential direction of the second substrate (2822) of at least 10 nm, in particular at least 20nm or 50nm or 100nm.

51 . Multi-substrate wafer (2820) according to claim 46, 47, 48, 49 or 50, characterized in that the polycrystalline structure (2822) comprises crystallites (2814) extending in length direction of the individual crystallite more than 5 pm, in particular more than 10pm and preferably more than 20pm, wherein the length directions of more than 30%, in particular more than 50% and preferably more than 70%, of the crystallites, which extend more than 5pm in the length direction of the individual crystallite, in particular more than 10pm or more than 20pm, are aligned in an angle of less than 75°, in particular less than 60° or preferably less than 45° and most preferably less than 30°, to the radial direction of the polycrystalline structure.

52. Multi-substrate wafer (2820) according to claims 46 to 51 , characterized in that the height of the second substrate (2822) is below 500 pm, in particular below 400 pm.

53. Multi-substrate wafer (2820) according to claims 46 to 52, characterized in that the crystal structure of the monocrystalline SiC crystal (2317) comprises less than 99,9999% (ppm wt) and preferably less than 99,99999% (ppm wt) and highly preferably less than 99,999999% (ppm wt) and most preferably less than 99,999999% (ppm wt) of one, multiple or all of the following substances B (Bor), Al (Aluminum), P (Phosphor), Ti (Titan), V (Vanadium), Fe (Eisen), Ni (Nickel).

54. Multi-substrate wafer (2820) according to claims 46 to 53, characterized in that the flat top surface (2406) of the polycrystalline 3C-SiC has a surface roughness of Ra < 20 nm and preferably of Ra<10nm and most preferably of Ra<5nm, wherein the monocrystalline SiC crystal (2317) is bonded to the flat top surface (2406) of the polycrystalline 3C-SiC.

55. Multi-substrate wafer (2820) according to claims 46 to 54, characterized in that the number of screw dislocations present inside the monocrystalline SiC crystal (2317) is below number of basal plane dislocations.

56. Multi-substrate wafer (2820) according to claims 46 to 55, characterized in that the first substrate (2317) has a thickness of less than 1 pm, wherein the c-axis is preferably aligned in an angle of 4°.

57. Multi-substrate wafer (2820) according to claim 56, characterized in that a monocrystalline SiC crystal (2319) layer is provided on the first substrate (2317), wherein the monocrystalline SiC crystal (2319) is grown by means of epitaxy.

58. Electronic device at least comprising a multi-substrate wafer (2820) according to any of claims 46 to 57, wherein at least one electronic component is grown or produced on or in the monocrystalline SiC crystal (2317) layer and wherein the second substrate (2822) has a thickness of more than

50pm, in particular more than 60pm or more than 80pm or more than 100pm or more than 150pm or up to 350.

59. Electronic device at least comprising a multi-substrate wafer (2820) according to claim 57, wherein at least one electronic component is grown or produced on or in the first substrate (2317) and wherein the second substrate (2822) has a thickness of more than