EP3997033A1 - Procédé de purification du carbure de silicium - Google Patents

Procédé de purification du carbure de silicium

Info

Publication number
EP3997033A1
EP3997033A1 EP20737176.6A EP20737176A EP3997033A1 EP 3997033 A1 EP3997033 A1 EP 3997033A1 EP 20737176 A EP20737176 A EP 20737176A EP 3997033 A1 EP3997033 A1 EP 3997033A1
Authority
EP
European Patent Office
Prior art keywords
silicon carbide
starting product
purity
heating
product
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20737176.6A
Other languages
German (de)
English (en)
Inventor
Matthias Hausmann
Wenzel KLIETZ
Josef GARBES
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Esk Sic GmbH
Original Assignee
Esk Sic GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Esk Sic GmbH filed Critical Esk Sic GmbH
Publication of EP3997033A1 publication Critical patent/EP3997033A1/fr
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/90—Carbides
    • C01B32/914—Carbides of single elements
    • C01B32/956—Silicon carbide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity

Definitions

  • the invention relates to the field of the production of raw materials for the semiconductor and electronics industry and relates to a method for purifying powdered silicon carbide as a starting product to a silicon carbide with a degree of purity of at least 99.9%.
  • Silicon carbide is an extremely hard, temperature-resistant synthetic industrial mineral. Due to its hardness and high melting point, it is used as an abrasive (carborundum, e.g. for optical mirrors and lenses) and as a component for refractory materials. However, the use as a semiconductor material is also essential. In addition to its use as an LED and photodiode, SiC is used for varistors, ultra-fast Schottky diodes, insulating layer and barrier layer field effect transistors, as well as electronic circuits and sensors based on them that have to withstand high temperatures or high doses of ionizing radiation. SiC-based semiconductor circuits can be used under laboratory conditions at temperatures of up to 600 ° C. Silicon carbide is also used in particular in automotive and environmental technology, for example for the manufacture of diesel particulate filters.
  • silicon carbide ceramics can be differentiated between non-species and intrinsically bound ceramics, as well as between open-pore and dense ceramics.
  • the type and proportion of the bond types are decisive for the respective characteristic properties of the silicon carbide ceramics.
  • the production can, for example, follow the so-called Acheson process.
  • Acheson process an elongated board made of synthetic carbon molded bodies is embedded in powdered coke and then covered with sand.
  • the shaped bodies are connected to electrodes and an electric current is applied which heats the shaped body to 2200-2400 ° C., whereby sufficient energy is made available to produce hexagonal ⁇ -silicon carbide from silicon dioxide in an endothermic reaction.
  • Highly pure SiC crystals for electronic applications and semiconductor technology who, according to the state of the art, are mostly produced from SiC substrate powders by means of a physical vapor deposition. This sublimation and recondensation process takes place at temperatures> 2000 ° C.
  • the physical vapor transport is promoted by a temperature difference between the vaccination stable and the starting material.
  • the starting material exposed to a higher temperature is deposited on the seed crystal. It is also possible to apply thin SiC layers to prefabricated semiconductor components using the same process as the starting product substrate powder.
  • the further processing to ultimately required grain sizes is carried out by grinding, cleaning and fractionating into appropriate grain bands.
  • silicon carbide from recycling processes from contaminated silicon carbide.
  • the degree of purity in particular is essential for the further processing of silicon carbide.
  • a degree of purity of almost 100% is required for numerous applications, which makes corresponding processes for cleaning or enriching the starting material complex and costly.
  • Impurities in silicon carbide are inorganic (non-metallic and inorganic metallic impurities).
  • thermal processes can also be used, for example the oxidation of free carbon in air.
  • the object of the present invention is to propose a method for increasing the degree of purity of silicon carbide.
  • the method should make it possible to convert a silicon carbide starting product with a degree of purity of more than 98%, preferably of more than 99%, into a highly pure silicon carbide product with a degree of purity of at least 99.9%.
  • the method should be inexpensive and easy to carry out.
  • the method according to the invention has the following method steps
  • the starting product is heated in a vacuum or an oxygen-free atmosphere to a temperature of over 1700 ° C for a period of at least 8 minutes.
  • the essential finding of the invention is that it is possible to significantly increase the degree of purity of a suitable silicon carbide starting product (hereinafter starting product) via a thermal process.
  • the result is a highly pure silicon carbide product (hereinafter product) with a degree of purity of at least 99.9%, preferably significantly higher.
  • the degree of purity refers to the pure silicon carbide in the product.
  • a suitable starting product for the high-purity silicon carbide product to be produced is, for example, silicon carbide powder in loose bulk.
  • powder with a low degree of compression can preferably have a percentage density, based on the true density of the powder or powder mixture, of up to a maximum of 50%.
  • Particularly suitable starting products have a density between 20 and 50%, advantageously between 25 and 40%.
  • a bulk can be created by pouring loose powder into a container or by pouring it onto a base. It can be distributed using simple mechanical aids. A slight compression can be achieved, for example, by using vibrations, for example by a vibrating table or by tapping.
  • the density of the starting product i.e. the bulk or the powder
  • the true density can be determined, for example, by gas pycnometry. If the composition is known, the density can also be calculated from the known true density of the components.
  • the pure density of silicon carbide is 3.21 g / cm 3 , for example.
  • the grain size of the starting product is less than 100 pm, preferably less than 70 pm.
  • the powder that can be used as the starting product can either be commercially available on the market and / or be chemically pretreated.
  • the starting product is subjected to a temperature treatment under vacuum or in an oxygen-free atmosphere at temperatures of over 1700 ° C.
  • the temperatures are advantageously between 1800 ° C and 2300 ° C, in particular around 1900 ° C to 2100 ° C.
  • a major advantage of the method according to the invention is in particular that it is not necessary to fractionate the product at any time. This leads both to a significant simplification of the process and to a considerable reduction in costs.
  • the product can be further processed in the form it is in after the thermal treatment. This applies especially if, for example, due to the thermal treatment and / or the transport of the starting product through the furnace, changes in grain sizes or volume changes due to caking have resulted. Such changes no longer have any influence on the purity of the product.
  • the starting product is only thermally treated and, if necessary, chemically cleaned; the resulting product is not post-treated, in particular not fractionated.
  • Thermal treatment is possible both in batch ovens and in continuous operation.
  • the duration of the thermal treatment ie the holding time with the correspondingly high temperature, is advantageously between about 8 minutes and 400 minutes at the temperatures mentioned.
  • the duration depends, among other things, on the physical properties of the starting product (e.g. the grain size), the volume to be treated and the temperature of the furnace.
  • Technical protective gas atmospheres such as an argon atmosphere, are preferably used as the oxygen-free atmosphere.
  • the thermal treatment is possible under a slight overpressure and under vacuum, up to and including vacuum. It has been shown that particularly good results are achieved if the thermal treatment is carried out under vacuum, preferably under low vacuum, in particular at about 10 mbar.
  • the pressure levels are varied depending on the driving style, depending on the temperature.
  • the degree of purity of the product is advantageously determined by a suitable method. As a rule, this is already over 99.9%. If the degree of purity is not sufficiently high, chemical cleaning can advantageously follow. It may be necessary to crush the thermally treated silicon carbide in order to dissolve possible caking.
  • chemical cleaning is also possible and useful even before the first thermal treatment, depending on the quality of the initial product, in order to remove the first impurities.
  • the chemical cleaning is advantageously carried out in a chemical reactor.
  • a chemical reactor For example, hydrofluoric acid (HF), nitric acid (HN03), phosphoric acid (H3P04), sulfuric acid (H2S04), hydrochloric acid (HCl), caustic soda (NaOH), ammonia (NH40H) or similar acidic or basic compounds, whereby the acids have a pH -Value of 0 and the alkalis produce a pH-value of 14
  • a silicon carbide starting product with a degree of purity of more than 98%, preferably more than 99%, is provided.
  • the starting product does not have to be present in various individual fractions; a single fraction is sufficient.
  • a first chemical cleaning can be carried out in order to separate out impurities. This procedural step depends on the starting product; if the starting product is sufficiently pure, the first chemical cleaning can be dispensed with.
  • the next step 24 is the filling of the oven and the thermal treatment of the starting product.
  • the starting product is heated to at least 1700 ° C., advantageously to at least 1900 ° C. to 2100 ° C., under an argon atmosphere and a rough vacuum during a furnace run.
  • the temperature is held for at least 8 minutes, but the temperature can also be held for up to about 400 minutes.
  • the thermally treated silicon carbide is chemically analyzed; in particular, the degree of purity is determined using a suitable method (method step 28). If the degree of purity is still too low, chemical cleaning (possibly the second chemical cleaning) can take place in an optional next method step 30.
  • the purity content is checked again via a final chemical analysis (process step 32). If the purity content is sufficient, that of the finished product 34 according to the invention can be used for further use.
  • the inventive method offers numerous advantages over already known methods. In particular, the method according to the invention can save considerable costs. In addition, in the optimal case, only thermal treatment of a suitable starting product is necessary. The method can thus be carried out quickly and easily.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

La présente invention concerne un procédé de purification du carbure de silicium pulvérulent en tant que produit de départ pour obtenir un carbure de silicium ayant un degré de pureté d'au moins 99,9 %. Ce processus comprend les étapes suivantes : - la fourniture d'un produit de départ ayant une teneur en carbure de silicium ayant une pureté d'au moins 98 % et une taille de grain inférieure à 100 μm, - le chauffage du produit de départ sous vide ou sous atmosphère privée d'oxygène à une température supérieure à 1700 °C pendant une période d'au moins 8 minutes.
EP20737176.6A 2019-07-11 2020-07-07 Procédé de purification du carbure de silicium Pending EP3997033A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102019118866 2019-07-11
DE102019131592.1A DE102019131592A1 (de) 2019-07-11 2019-11-22 Verfahren zum Aufreinigen von Siliciumcarbid
PCT/EP2020/069085 WO2021005039A1 (fr) 2019-07-11 2020-07-07 Procédé de purification du carbure de silicium

Publications (1)

Publication Number Publication Date
EP3997033A1 true EP3997033A1 (fr) 2022-05-18

Family

ID=74092049

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20737176.6A Pending EP3997033A1 (fr) 2019-07-11 2020-07-07 Procédé de purification du carbure de silicium

Country Status (4)

Country Link
US (1) US20220250918A1 (fr)
EP (1) EP3997033A1 (fr)
DE (1) DE102019131592A1 (fr)
WO (1) WO2021005039A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112758934A (zh) * 2021-03-17 2021-05-07 北方民族大学 一种β-碳化硅微粉的提纯方法

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1047180B (de) * 1958-04-03 1958-12-24 Wacker Chemie Gmbh Verfahren zur Herstellung von sehr reinem kristallinem Siliciumcarbid
JP4086936B2 (ja) * 1996-10-03 2008-05-14 株式会社ブリヂストン ダミーウェハ
US6280496B1 (en) * 1998-09-14 2001-08-28 Sumitomo Electric Industries, Ltd. Silicon carbide based composite material and manufacturing method thereof
US6419757B2 (en) * 1998-12-08 2002-07-16 Bridgestone, Corporation Method for cleaning sintered silicon carbide in wet condition
JP2000351614A (ja) * 1999-06-10 2000-12-19 Bridgestone Corp 炭化ケイ素粉体、及びその製造方法
JP5706671B2 (ja) * 2010-11-15 2015-04-22 独立行政法人産業技術総合研究所 昇華再結晶法による炭化ケイ素単結晶製造用炭化ケイ素粉体及びその製造方法
DE102013218450B3 (de) 2013-09-14 2014-06-05 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zum Recycling von pulverförmigen Siliciumcarbid-Abfallprodukten

Also Published As

Publication number Publication date
WO2021005039A1 (fr) 2021-01-14
DE102019131592A1 (de) 2021-01-14
US20220250918A1 (en) 2022-08-11

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