JP5440977B2 - Method for producing high-purity silicon nitride fine powder - Google Patents
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- JP5440977B2 JP5440977B2 JP2009204049A JP2009204049A JP5440977B2 JP 5440977 B2 JP5440977 B2 JP 5440977B2 JP 2009204049 A JP2009204049 A JP 2009204049A JP 2009204049 A JP2009204049 A JP 2009204049A JP 5440977 B2 JP5440977 B2 JP 5440977B2
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- 239000000843 powder Substances 0.000 title claims description 67
- 229910052581 Si3N4 Inorganic materials 0.000 title claims description 34
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 title claims description 34
- 238000004519 manufacturing process Methods 0.000 title claims description 23
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 49
- 238000005121 nitriding Methods 0.000 claims description 48
- 239000010703 silicon Substances 0.000 claims description 39
- 229910052710 silicon Inorganic materials 0.000 claims description 39
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000002699 waste material Substances 0.000 claims description 6
- 238000000227 grinding Methods 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000002994 raw material Substances 0.000 description 25
- 239000002245 particle Substances 0.000 description 20
- 238000000034 method Methods 0.000 description 19
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- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000004065 semiconductor Substances 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000012159 carrier gas Substances 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 239000007795 chemical reaction product Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000006082 mold release agent Substances 0.000 description 4
- 239000007921 spray Substances 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 229910052582 BN Inorganic materials 0.000 description 3
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 3
- 239000004677 Nylon Substances 0.000 description 3
- 239000011575 calcium Substances 0.000 description 3
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- 229910052786 argon Inorganic materials 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
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- 239000011810 insulating material Substances 0.000 description 2
- 101100004297 Caenorhabditis elegans bet-1 gene Proteins 0.000 description 1
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
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- 239000013078 crystal Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
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- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000010902 jet-milling Methods 0.000 description 1
- 229910052743 krypton Inorganic materials 0.000 description 1
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
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- 239000004570 mortar (masonry) Substances 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
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- 230000000630 rising effect Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Description
本発明は、金属シリコン粉末を直接窒化し、特に高純度が要求される半導体製造用各種治具用原料、高熱伝導窒化ケイ素基板用原料、太陽電池用シリコンインゴット製造時に用いる離型剤等に使用可能な窒化ケイ素粉末の製造方法に関する。 The present invention directly nitrifies metal silicon powder, and is used as a raw material for various jigs for semiconductor manufacturing, which is particularly required for high purity, a raw material for a high thermal conductivity silicon nitride substrate, a mold release agent used when manufacturing a silicon ingot for solar cells, etc. The present invention relates to a method for producing possible silicon nitride powder.
窒化ケイ素粉末の製造法の一つとして、金属シリコン粉末を窒素ガス又はアンモニアガスを含む非酸化性雰囲気で窒化する直接窒化法が知られている。この方法はプロセスが単純で比較的安価に窒化ケイ素粉を製造できるが、高純度の窒化ケイ素粉末の製造には不向きと言われている。なぜなら、高純度の窒化ケイ素粉末を得るためには、窒化反応の触媒として働くフッ化カルシウム等を添加することが出来ず、また原料として用いるシリコン粉末は、高純度でなければならないので窒化反応を促進すると言われている鉄系不純物等をわずかしか含まないので反応を制御しにくいからである。 As one method for producing silicon nitride powder, a direct nitriding method is known in which metal silicon powder is nitrided in a non-oxidizing atmosphere containing nitrogen gas or ammonia gas. Although this method is simple and can produce silicon nitride powder at a relatively low cost, it is said to be unsuitable for producing high-purity silicon nitride powder. This is because, in order to obtain high-purity silicon nitride powder, calcium fluoride or the like that acts as a catalyst for the nitriding reaction cannot be added, and the silicon powder used as a raw material must have a high purity. This is because the reaction is difficult to control because it contains only a small amount of iron-based impurities that are said to promote.
原料に窒化促進触媒を含まないので、加熱温度を通常より高くしなければ窒化反応が進みにくいが、窒化反応が発熱反応なので、温度を高くすると反応が始まると共に急激な温度上昇が起きて、原料シリコン粉末が溶融してしまう場合がある。一旦部分的にでも溶融するとその部分の窒化反応が進まなくなるので、未反応のシリコンが多く残ることになる。これを回避するために原料粒径や窒化反応条件を厳密に制御して窒化反応をゆっくり進行させて未反応シリコン量を減らす技術が開示されている。しかしこの方法は、ゆっくり反応させるために反応終了まで数日間にわたって非常に長い時間をかける必要があるし、反応条件の制御が面倒である。 Since the raw material does not contain a nitriding promotion catalyst, the nitriding reaction is difficult to proceed unless the heating temperature is raised higher than usual. However, since the nitriding reaction is an exothermic reaction, if the temperature is raised, the reaction starts and a sudden temperature rise occurs. Silicon powder may melt. Once partially melted, the nitriding reaction of that part does not proceed, so a large amount of unreacted silicon remains. In order to avoid this, a technique for reducing the amount of unreacted silicon by slowly controlling the raw material particle size and nitriding reaction conditions to slowly advance the nitriding reaction is disclosed. However, this method requires a very long time for several days to complete the reaction in order to react slowly, and the control of the reaction conditions is troublesome.
また、窒化反応の制御性を向上するために、通常より高温の反応場にシリコン粉を噴霧して短時間で窒化させる噴霧窒化法が開発されたが、これに使用するシリコン原料粉は、噴霧に適しており、かつ短時間で窒化反応が完結するように、十分に微細なものでなければならない。一般に、シリコン原料粉は塊状のシリコンを粉砕して製造するため、噴霧窒化法に適した微粉原料を得ようとすると、原料粉砕工程に於ける不純物混入量が多くなって、高純度窒化ケイ素粉を得にくくなる。 In addition, in order to improve controllability of the nitriding reaction, a spray nitriding method has been developed in which silicon powder is sprayed onto a reaction field at a temperature higher than usual to perform nitriding in a short time. It must be sufficiently fine so that the nitriding reaction can be completed in a short time. In general, since silicon raw material powder is produced by pulverizing bulk silicon, an attempt to obtain a fine powder raw material suitable for spray nitriding increases the amount of impurities mixed in the raw material pulverization process, resulting in high-purity silicon nitride powder. It becomes difficult to obtain.
本発明の目的は、上記に鑑み、特に高純度が要求される半導体製造用各種治具用原料、高熱伝導窒化ケイ素基板用原料、太陽電池用シリコンインゴット製造時に用いる離型剤等に使用可能な高純度窒化ケイ素粉末を、直接窒化法によって製造する方法を提供することである。 In view of the above, the object of the present invention can be used as a raw material for various jigs for semiconductor manufacturing, a raw material for a high thermal conductivity silicon nitride substrate, a mold release agent used when manufacturing a silicon ingot for solar cells, etc. It is to provide a method for producing a high purity silicon nitride powder by a direct nitriding method.
本発明は、比表面積が２０ｍ２／ｇ以上の高純度シリコンの加工屑を湿式ジェットミルにより粉砕してＤ５０を１．１μｍ以下、Ｄ９０を４μｍ以下、好ましくはＤ５０が０．７μｍ以下、Ｄ９０が２μｍ以下とした微粉を作成する微粉作成工程と、微粉作成工程によって作成された微粉を窒素ガス又はアンモニアガスのいずれか一方又は双方を含む雰囲気下で最高温度１３００℃〜１７００℃に加熱して反応させる窒化工程を有する高純度窒化ケイ素微粉末の製造方法である。 In the present invention, D50 is 1.1 μm or less, D90 is 4 μm or less, preferably D50 is 0.7 μm or less, and D90 is pulverized by wet jet milling with high-purity silicon processing waste having a specific surface area of 20 m 2 / g or more. A fine powder producing step for producing a fine powder having a particle size of 2 μm or less, and the fine powder produced by the fine powder producing step is heated to a maximum temperature of 1300 ° C. to 1700 ° C. in an atmosphere containing one or both of nitrogen gas and ammonia gas. It is a manufacturing method of the high purity silicon nitride fine powder which has the nitriding process made to react.
好ましくは、本発明は、また、微粉におけるＦｅ、Ａｌ、Ｃａの合計が、４０ｐｐｍ以下であることを特徴とする高純度窒化ケイ素微粉末の製造方法である。
なお、Ｄ５０とＤ９０は粉体の粒度分布（体積分布）の指標となる粒径であり、Ｄ５０（いわゆるメジアン径）を境に粒径の小さい側と大きい側が等量になり、Ｄ９０を境に粒径小さい側の累積分布が９０％、大きい側の累積分布が１０％になる。
Preferably, the present invention is, or, Fe in the fine, Al, the sum of Ca is high purity silicon nitride fine powder production method of, wherein the at 40ppm or less.
D50 and D90 are particle sizes that serve as an index of the particle size distribution (volume distribution) of the powder. The smaller and larger sides of D50 (so-called median diameter) are the same, and D90 is the boundary. The cumulative distribution on the smaller particle size side is 90%, and the cumulative distribution on the larger particle side is 10%.
本発明によれば、特に高純度が要求される半導体製造用各種治具用原料、高熱伝導窒化ケイ素基板用原料、太陽電池用シリコンインゴット製造時に用いる離型剤等に使用可能な高純度窒化ケイ素粉末を、簡便な反応条件の制御のみで直接窒化法によって製造することができる。 According to the present invention, high-purity silicon nitride that can be used as a raw material for various jigs for semiconductor manufacturing, a raw material for a high thermal conductivity silicon nitride substrate, a mold release agent used when manufacturing a silicon ingot for solar cells, etc. The powder can be produced by a direct nitriding method only by simple control of reaction conditions.
以下、更に詳しく本発明を説明する。 Hereinafter, the present invention will be described in more detail.
本発明に用いるシリコン源として、シリコンの各種加工時に発生する加工屑を含むシリコンスラッジを用いる。例えば、シリコン単結晶をウェハー状に切断するときに発生する切断屑を含むスラリーや、表面に半導体素子を形成した後のシリコンウェハーを薄くするときに発生するバックグラインド屑を含むスラリーを集めて、フィルター等でシリコン粉以外の異物を除去し、濃縮して、水分を１０〜５０質量％含むシリコンスラッジを得る。 As a silicon source used in the present invention, silicon sludge containing processing waste generated during various processing of silicon is used. For example, collect slurry containing cutting waste generated when cutting a silicon single crystal into a wafer, and slurry containing back grinding waste generated when thinning a silicon wafer after forming a semiconductor element on the surface, Foreign matter other than silicon powder is removed with a filter or the like and concentrated to obtain silicon sludge containing 10 to 50% by mass of water.
本発明で用いるシリコンスラッジは、スラッジを乾燥して得られるシリコン粉の比表面積が１０ｍ２／ｇ以上のものを使用しなければならない。好ましくは、２０ｍ２／ｇ以上のシリコン粉を使用する。大きな比表面積は粉体の一次粒子径が小さいことを示しており、後述するシリコンスラッジの粉砕後にレーザー回折散乱粒度分布測定装置で測定する二次粒子径と同様に、一次粒子径も小さい方が窒化反応は速やかに進行する。シリコンスラッジの段階で比表面積が十分大きいことが重要である。シリコン粉の比表面積が１０ｍ２／ｇ未満では、窒化反応が進みにくく、未反応シリコンが多く残る可能性がある。また、比表面積が小さいと、一次粒子径を十分に細かくするために、次の粉砕工程で強力に粉砕しなければならず、不純物が混入したり、粉砕時間が非常に長くなったりして不都合である。 As the silicon sludge used in the present invention, a silicon powder having a specific surface area of 10 m 2 / g or more obtained by drying the sludge must be used. Preferably, silicon powder of 20 m 2 / g or more is used. A large specific surface area indicates that the primary particle size of the powder is small. Like the secondary particle size measured with a laser diffraction / scattering particle size distribution measuring device after pulverization of silicon sludge described later, the smaller the primary particle size is, The nitriding reaction proceeds quickly. It is important that the specific surface area is sufficiently large at the stage of silicon sludge. When the specific surface area of the silicon powder is less than 10 m 2 / g, the nitriding reaction is difficult to proceed, and a large amount of unreacted silicon may remain. In addition, if the specific surface area is small, in order to make the primary particle diameter sufficiently fine, it must be pulverized strongly in the next pulverization process, which is inconvenient because impurities are mixed in and the pulverization time becomes very long. It is.
シリコンスラッジを粉砕するには、ボールミル、湿式ジェットミル等を用いる。ボールミルで粉砕するには、樹脂製ポットに固形分濃度（シリコンスラリー濃度）が１０〜３０質量％程度になるようにスラッジと水を入れ、粉砕用ボールを適当量加えて、１２〜４８時間程度回転させる。粉砕用ボールは摩耗して原料に混入するため、混入量を勘案して材質を選択しなければならない。好ましい材質は、鉄芯入りナイロンボールであり、混入するナイロンを分解するために、後の窒化工程の昇温パターンを工夫する必要がある。 In order to pulverize the silicon sludge, a ball mill, a wet jet mill or the like is used. To pulverize with a ball mill, add sludge and water in a resin pot so that the solid content (silicon slurry concentration) is about 10 to 30% by mass, add an appropriate amount of pulverizing balls, and about 12 to 48 hours. Rotate. Since the balls for grinding are worn and mixed into the raw material, the material must be selected in consideration of the amount of mixing. A preferable material is an iron-cored nylon ball, and it is necessary to devise a temperature rising pattern in a subsequent nitriding step in order to decompose the mixed nylon.
湿式ジェットミルは、スラリー同士を高速で衝突させる粉砕方法であり、一般に、加圧によりスラリーを加速させる。
湿式ジェットミルで粉砕するには、固形分濃度が１０質量％程度になるようにスラッジに水を加えてスラリーをつくり、噴射圧力９０ＭＰａ以上の圧力で１０分〜６０分処理すればよい。湿式ジェットミルは、ボールミルと異なり、ボールなどの粉砕媒体を使わないので、高純度の微粉を得るには好適である。また、微粉作成工程で湿式ジェットミルを用いると、ボールミルより短時間で容易に二次粒子径を小さくすることができ、そのためか、その後の窒化工程において反応が進みやすいという特徴がある。
The wet jet mill is a pulverization method in which slurries collide with each other at high speed, and generally the slurry is accelerated by pressurization.
In order to pulverize with a wet jet mill, a slurry is prepared by adding water to sludge so that the solid content concentration is about 10% by mass, and the treatment is performed for 10 minutes to 60 minutes at a pressure of 90 MPa or more. Unlike the ball mill, the wet jet mill does not use a pulverizing medium such as a ball, and is therefore suitable for obtaining a high-purity fine powder. In addition, when a wet jet mill is used in the fine powder preparation process, the secondary particle diameter can be easily reduced in a shorter time than a ball mill, and for this reason, there is a feature that the reaction easily proceeds in the subsequent nitriding process.
粉砕後のスラリーに含まれる二次粒子の粒度分布を、レーザー回折散乱粒度分布測定装置を用いて測定し、Ｄ５０が１．１μｍ以下、Ｄ９０が４μｍ以下になるように粉砕する。Ｄ５０が０．７μｍ以下、Ｄ９０が２μｍ以下が好ましい。それぞれ、それ以上の粒径の場合、同じ温度条件で窒化反応が十分に進まず未反応シリコンが多く残ったり、得られた窒化ケイ素粉の粒径が大きくなって焼結性が悪くなることがある。 The particle size distribution of the secondary particles contained in the pulverized slurry is measured using a laser diffraction / scattering particle size distribution measuring device, and pulverized so that D50 is 1.1 μm or less and D90 is 4 μm or less. D50 is preferably 0.7 μm or less and D90 is preferably 2 μm or less. When the particle size is larger than that, the nitriding reaction does not proceed sufficiently under the same temperature condition, and a lot of unreacted silicon remains, or the particle size of the obtained silicon nitride powder becomes large and the sinterability may deteriorate. is there.
また、Ｄ５０が１．１μｍ、Ｄ９０が４μｍを越えると、窒化反応が進まなくなることがある。微粉原料は、Ｆｅ、Ａｌ、Ｃａの合計が４０ｐｐｍ以下、特に３０ｐｐｍ以下であることが好ましく、このような不純物が多いと、高純度が要求される半導体用途等には使用できない。
粉砕方法としては、粉砕開始から所定時間経過後に、スラリーの一部を取り出して粒径分布を測定し、Ｄ５０、Ｄ９０が所定の値（１．１μｍ、４μｍ）以下の場合は粉砕を終了し、所定の値以下でない場合は、粉砕を続ける。Ｄ５０、Ｄ９０が所定値以下になるまで、粉砕と粒径分布の測定とを繰り返す。
又は、所定量のスラリーについて、Ｄ５０、Ｄ９０が所定値以下になるのに要する粉砕時間を予め調べておけば、実際の製造現場で粒径分布を測定しなくても、所定量のスラリーについて、予め求めた粉砕時間だけ粉砕を行えばよいから、製造工程が簡易である。
If D50 exceeds 1.1 μm and D90 exceeds 4 μm, the nitriding reaction may not proceed. The fine powder raw material preferably has a total of Fe, Al, and Ca of 40 ppm or less, particularly 30 ppm or less. If there are many such impurities, the fine powder raw material cannot be used for semiconductor applications that require high purity.
As a pulverization method, after a predetermined time has elapsed from the start of pulverization, a part of the slurry is taken out and the particle size distribution is measured. If D50 and D90 are equal to or smaller than a predetermined value (1.1 μm, 4 μm), the pulverization is terminated. If not below the predetermined value, the pulverization is continued. The pulverization and the measurement of the particle size distribution are repeated until D50 and D90 are below a predetermined value.
Or, for a predetermined amount of slurry, if the pulverization time required for D50 and D90 to be less than or equal to a predetermined value is examined in advance, even if the particle size distribution is not measured at the actual manufacturing site, Since the pulverization is performed for the pulverization time obtained in advance, the manufacturing process is simple.
得られたシリコンの微粉を後述する窒化工程で窒化する。窒化工程には、シリコンの微粉のみを用いてもよいが、高純度の窒化ケイ素粉末との混合粉末とすることによって窒化反応の制御が容易となり、所望の粒径の窒化ケイ素が得やすくなる。混合原料中の窒化ケイ素粉末の割合は、生産性との兼ね合いから１０質量％以上、５０質量％以下であることが好ましい。 The silicon fine powder obtained is nitrided in a nitriding step described later. In the nitriding step, only fine silicon powder may be used, but by using a mixed powder with high-purity silicon nitride powder, the nitriding reaction can be easily controlled and silicon nitride having a desired particle size can be easily obtained. The proportion of the silicon nitride powder in the mixed raw material is preferably 10% by mass or more and 50% by mass or less in view of productivity.
窒化工程はシリコンの微粉からなる微粉原料、又はシリコンの微粉及び窒化ケイ素粉末からなる粉末原料を、窒化ガスと接触させながら加熱する。
窒化ガスは窒素ガスとアンモニアガスのいずれか一方又は両方からなるものを用いる。窒化ガスと一緒に希ガスを用いてもよい。希ガスはアルゴン、ヘリウム、ネオン、キセノン、クリプトンとからなるガス群より選択されるいずれか１種以上のガスを用いる。窒化工程の一例を下記に示す。
シリコンスラッジを粉砕して得られたシリコンスラリーを乾燥して水分を除去した後、軽くほぐして得たシリコン微粉原料を、窒化ホウ素や炭素製のるつぼに入れ、電気炉内にセットする。電気炉内を真空引きした後、窒素ガス、アンモニアガス、アルゴンガスまたはそれらの混合ガスを流通させ、昇温を開始する。適当な昇温速度で１１５０℃まで加熱し、３０分〜２時間程度保持して温度の均一化を図った後、１３００〜１４５０℃、好ましくは１３００℃〜１３７５℃の範囲で選択される所定温度（最高温度）まで０．１〜５℃／分程度で昇温し、その間の適当な温度で３０分〜１２時間程度保持する。
In the nitriding step, a fine powder material made of silicon fine powder or a powder raw material made of silicon fine powder and silicon nitride powder is heated while being in contact with a nitriding gas.
The nitriding gas is made of one or both of nitrogen gas and ammonia gas. A rare gas may be used together with the nitriding gas. As the rare gas, one or more gases selected from a gas group consisting of argon, helium, neon, xenon, and krypton are used. An example of the nitriding process is shown below.
The silicon slurry obtained by pulverizing the silicon sludge is dried to remove moisture, and then the silicon fine powder raw material obtained by lightly loosening is placed in a boron nitride or carbon crucible and set in an electric furnace. After evacuating the inside of the electric furnace, nitrogen gas, ammonia gas, argon gas or a mixed gas thereof is circulated, and the temperature rise is started. After heating to 1150 ° C. at an appropriate rate of temperature rise and holding for about 30 minutes to 2 hours to equalize the temperature, a predetermined temperature selected in the range of 1300 ° C. to 1450 ° C., preferably 1300 ° C. to 1375 ° C. The temperature is raised to (maximum temperature) at about 0.1 to 5 ° C./minute, and held at an appropriate temperature for about 30 minutes to 12 hours.
一般の焼結用原料に用いるα率の高い窒化ケイ素粉を得るには、粒径の小さい微粉を使用し、１１５０℃以上の昇温速度を遅くすると共に、最高温度を１３７５℃以下とするとよい。また、高熱伝導窒化ケイ素基板の原料に適したα率の低い窒化ケイ素粉を得るには、昇温速度を早くしてもよい。太陽電池用シリコンインゴット製造時に用いる離型剤用にはβ型窒化ケイ素粉で良いので、本発明の製造方法によれば、窒化反応時間を短くして生産性をあげることができる。冷却後、電気炉からるつぼを取り出し、必要に応じて窒化反応物を軽く解砕し、目的とする高純度窒化ケイ素粉を得る。 In order to obtain a silicon nitride powder having a high α ratio used as a general sintering raw material, it is preferable to use a fine powder having a small particle diameter, slow the temperature increase rate of 1150 ° C. or higher, and set the maximum temperature to 1375 ° C. or lower. . Further, in order to obtain silicon nitride powder having a low α ratio suitable for the raw material of the high thermal conductivity silicon nitride substrate, the temperature raising rate may be increased. Since the β-type silicon nitride powder may be used for the release agent used in the production of the solar cell silicon ingot, according to the production method of the present invention, the nitriding reaction time can be shortened to increase the productivity. After cooling, the crucible is taken out from the electric furnace, and the nitriding reaction product is lightly crushed as necessary to obtain the desired high-purity silicon nitride powder.
また、例えば特許文献２に記載された装置を用いて、噴霧窒化法で窒化して高純度窒化ケイ素粉を得ることもできる。その場合、キャリアガスである窒素ガス及び／又はアンモニアガス中にシリコンスラッジを粉砕、乾燥して得た微粉原料を分散し、反応部に供給する。反応部で１４００〜１７００℃に加熱されて窒化反応が進み、バグフィルター、サイクロン等により、キャリアガスで搬送されてきた窒化ケイ素粉末を分離捕集する。反応部の温度が１４００℃未満では、反応速度が遅いために未窒化の金属シリコンが残存し、１７００℃を越えると粒成長が進み、焼結性が悪くなる。また、反応場における滞留時間が２秒未満では、反応時間が不十分であるため未窒化の金属シリコンが残存し、１０秒をこえると、粒成長が進み焼結性が悪くなる。
すなわち本発明は、反応炉に窒化ガスを含む温度１４００〜１７００℃の反応場（反応環境）を形成し、上述した微粉作成工程によって作成された微粉を、炉内圧とキャリアガス圧との差圧が０．２ＭＰａ以上にしてキャリアーガスを分散させながら供給し、反応場に２〜１０秒間滞留させ、微粉末を窒化させる場合も含む。
なお、本願発明で最高温度とは、窒化工程における加熱温度の最高点であり、上述したように、微粉をるつぼ等に静置して加熱する場合、最高温度は１３００〜１４５０℃が好ましく、噴霧窒化法の最高温度は１４００〜１７００℃が好ましい。すなわち、本願発明において、最高温度の下限は静置加熱の１３００℃であり、上限は噴霧窒化法の１７００℃である。
Further, for example, using the apparatus described in Patent Document 2, high purity silicon nitride powder can be obtained by nitriding by spray nitriding. In that case, a fine powder material obtained by pulverizing and drying silicon sludge in nitrogen gas and / or ammonia gas as a carrier gas is dispersed and supplied to the reaction section. The reaction part is heated to 1400 to 1700 ° C. and the nitriding reaction proceeds, and the silicon nitride powder conveyed by the carrier gas is separated and collected by a bag filter, a cyclone or the like. If the temperature of the reaction part is less than 1400 ° C., the reaction rate is slow, so that non-nitrided metal silicon remains. If the residence time in the reaction field is less than 2 seconds, the reaction time is insufficient, so that unnitrided metal silicon remains, and if it exceeds 10 seconds, the grain growth proceeds and the sinterability deteriorates.
That is, the present invention forms a reaction field (reaction environment) at a temperature of 1400 to 1700 ° C. containing a nitriding gas in the reaction furnace, and the fine powder produced by the fine powder production process described above is converted into a differential pressure between the furnace pressure and the carrier gas pressure. Including a case where the carrier gas is supplied while being dispersed at a pressure of 0.2 MPa or more and is allowed to stay in the reaction field for 2 to 10 seconds to nitride the fine powder.
In the present invention, the maximum temperature is the highest heating temperature in the nitriding step. As described above, when the fine powder is left standing in a crucible or the like and heated, the maximum temperature is preferably 1300 to 1450 ° C. The maximum temperature of the nitriding method is preferably 1400 to 1700 ° C. That is, in this invention, the minimum of the maximum temperature is 1300 degreeC of stationary heating, and an upper limit is 1700 degreeC of the spray nitriding method.
本発明にかかる実施例を、比較例と対比しつつ詳細に説明する。 Examples according to the present invention will be described in detail in comparison with comparative examples.
＜参考例１〜２＞
主として半導体工場のバックグラインド工程から発生したシリコン加工屑を含むスラッジを準備し、その少量を乾燥器で乾燥し、乾燥減量を測定したところ、２６．５質量％であった。乾燥したスラッジを、比表面積測定装置（装置名：Ｑｕａｎｔａｃｈｒｏｍｅ社製Ｑｕａｎｔａｓｏｒｂ）を用いてＢＥＴ１点法で比表面積を測定したところ、２４．３ｍ２／ｇであった。このスラッジ６８．０ｇを５００ｍｌのポリエチレン製ポットにとり、イオン交換水１８２ｇ、直径１１ｍｍの鉄芯入りナイロンボール約２５０ｇをポットに加え、ふたをして、２４時間ないし４８時間ボールミルで粉砕処理した。ボットから取り出したスラリーを、超音波発生装置で６０秒間分散し、レーザー回折散乱法粒度分布測定装置（装置名：島津製作所社製ＳＡＬＤ−７０００）で粒度分布を測定したところ、Ｄ５０およびＤ９０は表１に示す値だった。
< Reference Examples 1-2>
Sludge containing silicon processing waste mainly generated from the back grinding process of a semiconductor factory was prepared, a small amount thereof was dried with a drier, and the loss on drying was measured to be 26.5% by mass. It was 24.3 m < 2 > / g when the specific surface area was measured for the dried sludge by the BET 1 point method using the specific surface area measuring apparatus (apparatus name: Quantachrome by Quantachrome). 68.0 g of this sludge was put in a 500 ml polyethylene pot, 182 g of ion exchange water and about 250 g of an iron core nylon ball having a diameter of 11 mm were added to the pot, capped and ground in a ball mill for 24 to 48 hours. The slurry taken out from the bot was dispersed with an ultrasonic generator for 60 seconds, and the particle size distribution was measured with a laser diffraction / scattering particle size distribution measuring device (device name: SALD-7000, manufactured by Shimadzu Corporation). It was the value shown in 1.
得られた微粉１０ｇを窒化ホウ素製ルツボに入れ、カーボンヒーターとカーボン断熱材を備えた電気炉（装置名：富士電波社製ハイマルチ５０００）内にセットし、炉内を真空置換して窒素ガスで満たし、窒素ガスを１Ｌ／分流通させながら、１２００℃まで１０℃／分で昇温し、途中６００℃で１時間保持し、１２００℃で３０分保持した後、３℃／分で表１の「焼成条件、温度」の欄に示す所定温度まで昇温し、その温度で所定時間保持し、炉令してルツボを取り出した。窒化したサンプルを乳鉢で軽く解砕し、エックス線回折装置（装置名：Ｒｉｇａｋｕ社製Ｍｕｌｔｉｆｌｅｘ）を用いて得られた回折パターンから残存シリコン量を定量し、窒化率を算出した。また、前記と同様にして、得られた窒化反応物の比表面積を測定し、それらの値を表1に示した。表１から、比較的単純な温度制御と短い反応時間で、窒化反応が良く進んでいることが分かる。 10 g of the obtained fine powder is put into a boron nitride crucible and set in an electric furnace (device name: High Multi 5000, manufactured by Fuji Radio Co., Ltd.) equipped with a carbon heater and a carbon heat insulating material. The temperature was raised to 1200 ° C. at 10 ° C./min while nitrogen gas was passed at 1 L / min, held at 600 ° C. for 1 hour, held at 1200 ° C. for 30 minutes, and then at 3 ° C./min. The temperature was raised to a predetermined temperature shown in the column of “Baking conditions and temperature”, held at that temperature for a predetermined time, and a furnace was ordered to take out the crucible. The nitrided sample was lightly crushed with a mortar, the amount of residual silicon was quantified from the diffraction pattern obtained using an X-ray diffractometer (device name: Multiflex manufactured by Rigaku), and the nitriding rate was calculated. Further, the specific surface area of the obtained nitriding reaction product was measured in the same manner as described above, and those values are shown in Table 1. From Table 1, it can be seen that the nitriding reaction proceeds well with relatively simple temperature control and a short reaction time.
＜参考例３〜４、実施例５〜１４、比較例１〜４＞
表１に示す各種比表面積を持ったスラッジを用い、固形分濃度１０質量％になるようにイオン交換水を加えてスラリーを作成した。これを、液体ジェットミル（装置名：スギノマシン社製アルティマイザーシステム）を用いて、表１に示す条件で粉砕した。参考例１と同様に測定して得られた微粉の粒径を表１に示す。
<Reference Example 3-4, Example 5-14, Comparative Example 1-4>
Using sludge having various specific surface areas shown in Table 1, slurry was prepared by adding ion-exchanged water so that the solid concentration was 10% by mass. This was pulverized under the conditions shown in Table 1 using a liquid jet mill (device name: Optimizer System manufactured by Sugino Machine). Table 1 shows the particle size of the fine powder obtained by measurement in the same manner as in Reference Example 1.
得られた微粉１０ｇを窒化ホウ素製ルツボに入れ、カーボンヒーターとカーボン断熱材を備えた電気炉（装置名：富士電波社製ハイマルチ５０００）内にセットし、炉内を真空置換して窒素ガスで満たし、窒素ガスを１Ｌ／分流通させながら、１２００℃まで１０℃／分で昇温し、１２００℃で３０分保持した後、３℃／分で表１に示す所定温度まで昇温し、その温度で所定時間保持し、炉令してルツボを取り出した。参考例１と同様に残存シリコン量を定量し、窒化率を算出した。 10 g of the obtained fine powder is put into a boron nitride crucible and set in an electric furnace (device name: High Multi 5000, manufactured by Fuji Radio Co., Ltd.) equipped with a carbon heater and a carbon heat insulating material. The temperature was raised to 1200 ° C. at 10 ° C./min while maintaining nitrogen gas flowing at 1 L / min, held at 1200 ° C. for 30 minutes, and then heated to the predetermined temperature shown in Table 1 at 3 ° C./min. The temperature was maintained for a predetermined time, and the crucible was taken out at the furnace age. In the same manner as in Reference Example 1, the amount of remaining silicon was quantified and the nitriding rate was calculated.
＜実施例１５、１６＞
実施例１４と同様にして得られた微粉を、実施例１４と同様にして、表１に示す所定温度まで昇温し、所定時間保持した後、表１の備考欄に示す条件で更に加熱した。すなわち、実施例１５、１６の最高温度は、表１の備考欄に記載された温度（１３５０℃）である。その後、窒化反応物を取り出して、参考例１と同様に窒化率と比表面積を測定し、また、α率をＪＩＳＲ１６４０に準じて測定した。実施例１１〜１４で得られた窒化反応物についても同様にしてα率を求め、それらの値を表１に示した。１１５０℃以上の昇温速度が、窒化ケイ素のα率に大きな影響を及ぼすことが分かる。
<Examples 15 and 16>
The fine powder obtained in the same manner as in Example 14 was heated to the predetermined temperature shown in Table 1 and held for a predetermined time in the same manner as in Example 14, and then further heated under the conditions shown in the remarks column of Table 1. . That is, the maximum temperature of Examples 15 and 16 is the temperature (1350 ° C.) described in the remarks column of Table 1. Thereafter, the nitriding reaction product was taken out, the nitriding rate and the specific surface area were measured in the same manner as in Reference Example 1, and the α rate was measured according to JIS R1640. The α rate was similarly determined for the nitridation products obtained in Examples 11 to 14 and the values are shown in Table 1. It can be seen that the temperature increase rate of 1150 ° C. or higher has a great influence on the α ratio of silicon nitride.
表１には、参考例１に記載した方法で測定した窒化反応物の比表面積を記載した。これらの値から、比表面積の大きい窒化ケイ素粉を得るには、最高加熱温度を１３７５℃以下、好ましくは１３５０℃以下とするとよいことがわかる。また、実施例１０、１１、１２、１４の微粉に含まれるＡｌ、Ｃａ、Ｆｅの量を備考欄に示した。このように本発明のシリコン原料を用いると、特に金属不純物の含有量の少ない窒化ケイ素粉末が要求される用途、例えば、半導体製造治具や離型剤等の用途に好適である。 Table 1 shows the specific surface area of the nitriding reaction product measured by the method described in Reference Example 1. From these values, it can be seen that in order to obtain silicon nitride powder having a large specific surface area, the maximum heating temperature should be 1375 ° C. or lower, preferably 1350 ° C. or lower. The amounts of Al, Ca, and Fe contained in the fine powders of Examples 10, 11, 12, and 14 are shown in the remarks column. Thus, when the silicon raw material of the present invention is used, it is particularly suitable for applications requiring silicon nitride powder with a low content of metal impurities, such as semiconductor manufacturing jigs and mold release agents.
＜実施例１７〜１９＞
特開２００４−１１５３３４号公報に示された装置を用いて窒化ケイ素粉末の製造試験を行った。実施例１４で用いた金属シリコン微粉とα率９０％、比表面積が８．７ｍ２／ｇの窒化ケイ素粉末を表２で示す割合で混合し、これを原料供給機（スクリューフィーダー（日清エンジニアリング社製商品名「フィードコンμ」）を用い、原料撹拌槽に輸送した。スクリューにより切り出された微粉原料は、原料攪拌槽内で窒素ガスと撹拌された後、窒素ガスをキャリアガスとして１６００℃の反応場に分散させながら供給した。反応場の生成物をブロワで吸引して捕集部に搬送し、捕集装置（バグフィルター）で捕集し、捕集品に含まれる金属ケイ素量を参考例１と同様に測定して窒化率を算出した。また、実施例１５と同様にα率と比表面積を求めた。それらの結果を表２に示す。
<Examples 17 to 19>
A production test of silicon nitride powder was performed using an apparatus disclosed in Japanese Patent Application Laid-Open No. 2004-115334. The metal silicon fine powder used in Example 14 and the silicon nitride powder having an α ratio of 90% and a specific surface area of 8.7 m 2 / g were mixed in the ratio shown in Table 2, and this was mixed with a raw material feeder (screw feeder (Nisshin Engineering). The fine powder raw material cut out by the screw was stirred with nitrogen gas in the raw material stirring tank, and then the nitrogen gas was used as a carrier gas at 1600 ° C. The product in the reaction field was sucked with a blower and transported to a collection part, collected with a collection device (bag filter), and the amount of metal silicon contained in the collected product was reduced. The nitriding rate was calculated by measurement in the same manner as in Reference Example 1. The α rate and specific surface area were determined in the same manner as in Example 15. Table 2 shows the results.
表２から、高純度高強度焼結体原料に適した、未反応シリコンを含まない、非常にα率の高い、大きな比表面積を持った粒径の小さい粉が得られることが分かる。 From Table 2, it can be seen that a powder having a large specific surface area and a small particle size, which does not contain unreacted silicon, is suitable for a high-purity high-strength sintered body raw material, is obtained.
Claims (3)
微粉作成工程によって作成された前記微粉を窒素ガス又はアンモニアガスのいずれか一方又は双方を含む雰囲気下で最高温度１３００℃〜１７００℃に加熱して反応させる窒化工程を有する高純度窒化ケイ素微粉末の製造方法。 A fine powder producing step of producing fine powder having a D50 of 1.1 μm or less and a D90 of 4 μm or less by grinding high-purity silicon processing waste having a specific surface area of 20 m 2 / g or more by a wet jet mill ;
A high-purity silicon nitride fine powder having a nitriding step in which the fine powder produced by the fine powder production step is reacted by heating to a maximum temperature of 1300 ° C. to 1700 ° C. in an atmosphere containing one or both of nitrogen gas and ammonia gas. Production method.
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| JP5930637B2 (en) * | 2011-09-28 | 2016-06-08 | デンカ株式会社 | Silicon nitride powder for mold release agent and method for producing the same |
| JP5901448B2 (en) * | 2012-06-28 | 2016-04-13 | デンカ株式会社 | Silicon nitride powder for mold release agent |
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| JPH02239108A (en) * | 1989-03-14 | 1990-09-21 | Shin Etsu Chem Co Ltd | Production of silicon nitride |
| JPH0492804A (en) * | 1990-08-06 | 1992-03-25 | S T K Ceramics Kenkyusho:Kk | Production of beta type silicon nitride powder |
| JP2541019B2 (en) * | 1991-01-22 | 1996-10-09 | 信越化学工業株式会社 | Method for producing silicon nitride powder |
| JPH0532405A (en) * | 1991-07-29 | 1993-02-09 | Shin Etsu Chem Co Ltd | Silicon nitride powder, its production and sintered compact therefrom |
| JP2649220B2 (en) * | 1994-11-29 | 1997-09-03 | 本田技研工業株式会社 | Silicon nitride / silicon carbide composite powder, composite compact, method for producing them, and method for producing silicon nitride / silicon carbide composite sintered body |
| JP3279128B2 (en) * | 1994-08-12 | 2002-04-30 | 宇部興産株式会社 | Silicon nitride powder |
| JP3907515B2 (en) * | 2002-04-08 | 2007-04-18 | 電気化学工業株式会社 | Method for producing high-purity silicon nitride fine powder |
| JP3877645B2 (en) * | 2002-06-03 | 2007-02-07 | 電気化学工業株式会社 | Method for producing silicon nitride powder |
| JP3804947B2 (en) * | 2002-09-27 | 2006-08-02 | 電気化学工業株式会社 | Method for producing high α-type silicon nitride fine powder |
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