JPWO2020090832A1 - Manufacturing method of silicon nitride substrate and silicon nitride substrate - Google Patents

Manufacturing method of silicon nitride substrate and silicon nitride substrate Download PDF

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JPWO2020090832A1
JPWO2020090832A1 JP2020553947A JP2020553947A JPWO2020090832A1 JP WO2020090832 A1 JPWO2020090832 A1 JP WO2020090832A1 JP 2020553947 A JP2020553947 A JP 2020553947A JP 2020553947 A JP2020553947 A JP 2020553947A JP WO2020090832 A1 JPWO2020090832 A1 JP WO2020090832A1
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道夫 本田
道夫 本田
昌孝 藤永
昌孝 藤永
卓司 王丸
卓司 王丸
耕司 柴田
耕司 柴田
山田　哲夫
哲夫 山田
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Abstract

窒化ケイ素粉末および焼結助剤を含む複数枚のグリーンシートをそれらの間に分離材を介在させて積層し、焼結した後に、分離することによって複数枚の窒化ケイ素焼結体を得て、窒化ケイ素焼結体から窒化ケイ素基板を得る、窒化ケイ素基板の製造方法であって、分離材が窒化ケイ素粉を含むことを特徴とする。得られる窒化ケイ素基板は表面に窒化ホウ素粉を含まないので、銅と接合した際のヒートサイクル性に優れる。分離材は、ＢＥＴ法により測定される比表面積が１ｍ２／ｇ以上２０ｍ２／ｇ以下であり、レーザ回折散乱法により測定される体積基準の５０％粒子径Ｄ５０が２０μｍ以下であり、かつ、酸素量が０．３重量％以上２重量％未満であり、分離材を０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下の塗布量でグリーンシート表面に塗布することで、熱伝導率が室温において８０Ｗ／（ｍ・Ｋ）以上であり、４点曲げ強度が室温において８００ＭＰa以上である窒化ケイ素基板を得ることができる。A plurality of green sheets containing silicon nitride powder and a sintering aid are laminated with a separating material interposed therebetween, sintered, and then separated to obtain a plurality of silicon nitride sintered bodies. A method for producing a silicon nitride substrate, which obtains a silicon nitride substrate from a silicon nitride sintered body, characterized in that the separating material contains silicon nitride powder. Since the obtained silicon nitride substrate does not contain boron nitride powder on its surface, it has excellent heat cycle properties when bonded to copper. The separating material has a specific surface area measured by the BET method of 1 m2 / g or more and 20 m2 / g or less, a volume-based 50% particle diameter D50 measured by the laser diffraction / scattering method of 20 μm or less, and an oxygen content. Is 0.3% by weight or more and less than 2% by weight, and by applying the separating material to the surface of the green sheet at a coating amount of 0.1 mg / cm2 or more and 3 mg / cm2 or less, the thermal conductivity is 80 W / (m) at room temperature. -K) or more, and a silicon nitride substrate having a four-point bending strength of 800 MPa or more at room temperature can be obtained.

Description

本発明は、絶縁基板および回路基板に用いられる窒化ケイ素基板の製造方法、および、この製造方法によって製造される窒化ケイ素基板に関する。 The present invention relates to a method for manufacturing a silicon nitride substrate used for an insulating substrate and a circuit board, and a silicon nitride substrate manufactured by this manufacturing method.

近年、各種のセラミックス（焼結体）基板が半導体モジュール用基板や構造用部材として広く用いられている。例えば、大電力で発熱量の大きな半導体素子を実装する半導体モジュール用基板としては、機械的強度の高さ、熱伝導率の高さ、電気的絶縁性の高さが要求される。窒化アルミニウムや窒化ケイ素等の窒化物焼結体はこれらの特性に優れており、これらの窒化物焼結体基板が広く用いられている。 In recent years, various ceramic (sintered) substrates have been widely used as substrates for semiconductor modules and structural members. For example, a substrate for a semiconductor module on which a semiconductor element having a large power and a large calorific value is mounted is required to have high mechanical strength, high thermal conductivity, and high electrical insulation. Nitride sintered bodies such as aluminum nitride and silicon nitride are excellent in these characteristics, and these nitride sintered body substrates are widely used.

窒化物基板の元となる窒化物焼結体は、窒化物（ＡｌＮ、Ｓｉ３Ｎ４等）粉末を主成分としたグリーンシートを高温の窒素雰囲気中で焼結することによって作製される。この際、大面積の窒化物焼結体を製造し、この焼結体から所望の大きさをもつ上記の基板を複数枚切り出すという製造方法が一般的である。この焼結は電気炉等を用いて行われるが、製造コストを低減するために、複数のグリーンシートを積層して焼結することにより、複数の窒化物焼結体を同時に得るという手法が用いられる。The nitride sintered body, which is the basis of the nitride substrate, is produced by sintering a green sheet containing nitride (AlN, Si 3 N 4, etc.) powder as a main component in a high-temperature nitrogen atmosphere. At this time, a general manufacturing method is to manufacture a nitride sintered body having a large area and cut out a plurality of the above-mentioned substrates having a desired size from the sintered body. This sintering is performed using an electric furnace or the like, but in order to reduce the manufacturing cost, a method of obtaining a plurality of nitride sintered bodies at the same time by laminating and sintering a plurality of green sheets is used. Be done.

この焼結の際には、積層した窒化物焼結体間の接着を防止するため、窒化物焼結体とされるべきグリーンシートは、分離材を表面に塗布した上で積層される。焼結後、分離材によって複数の窒化物焼結体を分離することができる。 At the time of this sintering, in order to prevent adhesion between the laminated nitride sintered bodies, the green sheet to be the nitride sintered body is laminated after applying a separating material on the surface. After sintering, a plurality of nitride sintered bodies can be separated by a separating material.

窒化アルミニウムや窒化ケイ素等の窒化物焼結体は１６００℃以上の高温で焼結する必要があるため、焼結温度以上の高温で安定な窒化ホウ素（ＢＮ）粉が窒化物焼結体間の剥離性を良好にするために分離材として広く用いられている。 Since a nitride sintered body such as aluminum nitride or silicon nitride needs to be sintered at a high temperature of 1600 ° C. or higher, stable boron nitride (BN) powder at a high temperature of 1600 ° C. or higher is generated between the nitride sintered bodies. It is widely used as a separating material to improve peelability.

上記のように、ＢＮ粉は、窒化物焼結体間に介在させたまま焼結が行われるため、焼結時に窒化物焼結体を拘束したり、窒化物焼結体と反応したりすることにより、変形させることがないようにしなければならない。そのため、使用するＢＮ粉の性状やＢＮ粉の塗布方法等の製造条件を選択する必要がある。 As described above, since the BN powder is sintered while being interposed between the nitride sintered bodies, the nitride sintered body is restrained at the time of sintering or reacts with the nitride sintered body. By doing so, it must be prevented from being deformed. Therefore, it is necessary to select the manufacturing conditions such as the properties of the BN powder to be used and the method of applying the BN powder.

特許文献１には、複数のグリーンシートをその間に高耐熱性の微粒子からなる剥離材を介在させて積層し、この積層グリーンシートの積層方向に押圧しながら、焼成する板状セラミック焼結体の製造方法が開示されている。この発明では、焼結時の反りやクラックを防止し、重ね合わせたシートが固着することなく、容易に剥離できることが記載されている。しかしながら、セラミック焼結体として窒化ケイ素薄板に関する記載はなく、窒化ケイ素薄板の製造に剥離材として窒化ケイ素粉を用いることについての記載は全くない。 Patent Document 1 describes a plate-shaped ceramic sintered body in which a plurality of green sheets are laminated with a release material made of highly heat-resistant fine particles interposed between them, and the laminated green sheet is fired while being pressed in the laminating direction. The manufacturing method is disclosed. In the present invention, it is described that warpage and cracks at the time of sintering are prevented, and the stacked sheets can be easily peeled off without sticking. However, there is no description about the silicon nitride thin plate as the ceramic sintered body, and there is no description about using the silicon nitride powder as the release material in the production of the silicon nitride thin plate.

特許文献２には、分離材が酸素量０．０１〜０．５重量％、平均粒子径４〜２０μｍ、比表面積２０ｍ２／ｇ以下の窒化ホウ素（ＢＮ）粉であり、前記ＢＮ粉を０．０５〜１．４ｍｇ／ｃｍ２の塗布量でグリーンシート表面に塗布する窒化珪素基板の製造方法が開示されている。この発明では、剥離性が良好で、相対密度が高くかつ、高強度、高熱伝導率であって、変形の少ない窒化珪素基板を提供することが記載されている。しかしながら、曲げ強度は７９０ＭＰａ以下、熱伝導率は９３Ｗ／ｍＫ以下である。In Patent Document 2, the separating material is a boron nitride (BN) powder having an oxygen content of 0.01 to 0.5% by weight, an average particle diameter of 4 to 20 μm, and a specific surface area of 20 m 2 / g or less, and the BN powder is 0. A method for producing a silicon nitride substrate to be applied to the surface of a green sheet at a coating amount of .05 to 1.4 mg / cm 2 is disclosed. The present invention describes providing a silicon nitride substrate having good peelability, high relative density, high strength, high thermal conductivity, and little deformation. However, the bending strength is 790 MPa or less, and the thermal conductivity is 93 W / mK or less.

特許文献３には、窒化珪素粒子と、少なくとも酸化マグネシウムからなる焼結助剤を含有する窒化珪素焼結体からなる窒化ケイ素基板であって、前記窒化珪素粒子は、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子を面積比で３０％以上含み、前期基板表面の算術平均粗さＲａが０．３〜２μｍ以上であり、基板表面に残存するＢＮと窒化ケイ素の比がＢの蛍光Ｘ線強度とＳｉの蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で６．５×１０−５を超え３００×１０−５以下であることを特徴とする窒化珪素基板の製造方法、及び窒化珪素基板、並びにそれを使用した回路基板が開示されている。しかしながら、窒化ケイ素基板表面に残存する分離材である窒化ホウ素の残存量を適正な範囲とすることで銅板を接合した際の耐ヒートサイクル性が改善されるが、曲げ強度は７５０ＭＰａ以上、８３０ＭＰａ以下である。Patent Document 3 describes a silicon nitride substrate made of silicon nitride particles and a silicon nitride sintered body containing a sintering aid composed of at least magnesium oxide, and the silicon nitride particles have a minor axis a of 0.5. When columnar crystal particles with an area ratio of ~ 5 μm and a major axis b ratio (b / a) of 2 or more to a minor axis a are contained in an area ratio of 30% or more, and the arithmetic average roughness Ra of the surface of the substrate in the first half is 0.3 to 2 μm or more. Yes, the ratio of BN and silicon nitride remaining on the substrate surface is more than 6.5 × 10-5 and 300 × 10-5 or less in the ratio (B / Si) of the fluorescent X-ray intensity of B and the fluorescent X-ray intensity of Si. A method for manufacturing a silicon nitride substrate, a silicon nitride substrate, and a circuit substrate using the same are disclosed. However, by setting the residual amount of boron nitride, which is a separating material remaining on the surface of the silicon nitride substrate, to an appropriate range, the heat cycle resistance when the copper plates are joined is improved, but the bending strength is 750 MPa or more and 830 MPa or less. Is.

特開平１−８７５７４号公報Japanese Unexamined Patent Publication No. 1-87574 特開２０１１−１７８５９８号公報Japanese Unexamined Patent Publication No. 2011-178598 特開２０１１−２１６５７７号公報Japanese Unexamined Patent Publication No. 2011-216577 国際公開第２０１３／１４６７１３号International Publication No. 2013/146713

これらの従来技術によれば、セラミックグリーンシートの表面に分離材である窒化ホウ素を塗布することで、複数枚のグリーンシートを積層して焼結した後、剥離性が良好で、変形の少ない窒化ケイ素基板が得られるが、基板表面に分離材である窒化ホウ素が残存するために、銅板を接合した際の耐ヒートサイクル性に問題が生じており、改善されることが望まれている。 According to these conventional techniques, by applying boron nitride, which is a separating material, to the surface of a ceramic green sheet, a plurality of green sheets are laminated and sintered, and then the peelability is good and the silicon nitride is less deformed. A silicon substrate can be obtained, but since boron nitride, which is a separating material, remains on the surface of the substrate, there is a problem in heat cycle resistance when the copper plates are joined, and it is desired to improve the heat cycle resistance.

また、これらの従来技術では、近年益々発熱量が増大する半導体モジュールに対しては熱伝導性または機械的特性が不足しがちであり、特に動作中の高温域まで放熱性を安定に確保することがより一層望まれている現状においては、熱伝導性と機械的特性の両面で性能不足であるという問題もある。 Further, in these conventional techniques, thermal conductivity or mechanical characteristics tend to be insufficient for semiconductor modules whose heat generation amount is increasing more and more in recent years, and in particular, stable heat dissipation is ensured even in a high temperature region during operation. In the present situation where is further desired, there is also a problem that the performance is insufficient in terms of both thermal conductivity and mechanical properties.

例えば、耐ヒートサイクル性を改善すべく、グリーンシート表面への窒化ホウ素（ＢＮ）分離材の塗布量を少なくする方法、あるいは、窒化珪素焼結体表面をラッピング、あるいはホーニング等の加工条件を強化してＢＮ分離材を強制的に除去加工する方法などを採用して、基板表面に残存するＢＮと窒化ケイ素の比を表すＢ／Ｓｉ蛍光Ｘ線強度比を５×１０−５以下とすると、窒化ケイ素焼結体表面に欠陥が残存またはダメージが発生することに伴って、その曲げ強度が低下する。For example, in order to improve heat cycle resistance, a method of reducing the amount of boron nitride (BN) separating material applied to the surface of the green sheet, or strengthening processing conditions such as wrapping or honing the surface of the silicon nitride sintered body. Then, by adopting a method of forcibly removing the BN separator and setting the B / Si fluorescent X-ray intensity ratio, which represents the ratio of BN and silicon nitride remaining on the substrate surface, to 5 × 10 -5 or less, As defects remain or damage occurs on the surface of the silicon nitride sintered body, its bending strength decreases.

特許文献３では、窒化珪素粒子と、少なくとも酸化マグネシウムからなる焼結助剤を含有する窒化珪素焼結体からなる窒化ケイ素基板において、前記窒化珪素粒子が、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子を面積比で３０％以上含み、前記基板表面の算術平均粗さＲａが０．３〜２μｍであり、基板表面に残存するＢＮと窒化ケイ素の比がＢの蛍光Ｘ線強度とＳｉの蛍光Ｘ線強度の比（Ｂ／Ｓｉ）を６．５×１０−５を超え３００×１０−５以下という適正な範囲とすることによって、窒化ケイ素基板表面に銅板を接合する際の接合強度を高め、耐ヒートサイクル性を改善している。しかしながら、特許文献３の方法では、前記ｂ／ａ比が２以上の柱状結晶粒子の面積比を３０％以上にして、基板表面に所定の深さの凹部を形成することによって、分離材であるＢＮが凹部に残留して、最表面にＢＮが存在しなくなるようにするという方法で耐ヒートサイクル性を改善しているため、窒化ケイ素基板表面の凹凸が大きくなっている。このため、窒化ケイ素焼結体の曲げ強度は８３０ＭＰａ以下のレベルに留まっている。In Patent Document 3, in a silicon nitride substrate made of silicon nitride particles and a silicon nitride sintered body containing a sintering aid composed of at least magnesium oxide, the silicon nitride particles have a minor axis a of 0.5 to 5 μm. In addition, columnar crystal particles having a major axis b ratio (b / a) of 2 or more to a minor axis a are contained in an area ratio of 30% or more, the arithmetic average roughness Ra of the substrate surface is 0.3 to 2 μm, and the substrate surface. The ratio of BN and silicon nitride remaining in is an appropriate range in which the ratio of fluorescent X-ray intensity of B to fluorescent X-ray intensity of Si (B / Si) exceeds 6.5 × 10-5 and is 300 × 10-5 or less. By doing so, the bonding strength when the copper plate is bonded to the surface of the silicon nitride substrate is increased, and the heat cycle resistance is improved. However, in the method of Patent Document 3, the separating material is formed by forming recesses having a predetermined depth on the surface of the substrate by setting the area ratio of the columnar crystal particles having a b / a ratio of 2 or more to 30% or more. Since the heat cycle resistance is improved by a method in which the BN remains in the concave portion and the BN does not exist on the outermost surface, the unevenness on the surface of the silicon nitride substrate is increased. Therefore, the bending strength of the silicon nitride sintered body remains at the level of 830 MPa or less.

本発明者らは、分離材として、従来の窒化ホウ素粉に代えて窒化ケイ素粉を用いることで、銅と接合した際のヒートサイクル性が十分でないという問題を解決できるとともに、所定の特性を有する窒化ケイ素粉を用いることで、さらに上記の曲げ強度が低下するという問題とヒートサイクルに対する耐久性が十分でないという問題の両方をも一気に解決できることを見出した。 By using silicon nitride powder instead of the conventional boron nitride powder as the separating material, the present inventors can solve the problem that the heat cycle property when bonded to copper is not sufficient, and have predetermined characteristics. It has been found that by using the silicon nitride powder, both the above-mentioned problem of lowering the bending strength and the problem of insufficient durability against the heat cycle can be solved at once.

即ち、本発明は、上記の問題点を鑑みてなされたものであり、銅と接合した際のヒートサイクル性に優れた窒化ケイ素基板及びその製造方法と、従来技術よりもはるかに高強度、高熱伝導であって、変形の少ない窒化ケイ素基板及びその製造方法を提供することを目的とする。 That is, the present invention has been made in view of the above problems, and is a silicon nitride substrate having excellent heat cycle property when bonded to copper, a method for producing the same, and much higher strength and heat than the prior art. It is an object of the present invention to provide a silicon nitride substrate which is conductive and has little deformation and a method for producing the same.

本発明者らは、前記課題を解決するために鋭意研究を重ね、窒化ケイ素基板の製造のための分離材として窒化ホウ素（ＢＮ）粉ではなく窒化ケイ素（ＳＮ）粉を用いることができること、またそれにより耐ヒートサイクル性に優れた窒化ケイ素基板が得られること、並びに、特定の比表面積、粒度、酸素量を有し、アルミニウム含有量が少ない窒化ケイ素（ＳＮ）粉を分離材として、塗布量などの製造条件を特定の範囲とすることにより、剥離性が良好で、高強度、高熱伝導であって、変形の少ない窒化ケイ素基板が得られることを見出し、本発明に至った。すなわち本発明は以下に関する。 The present inventors have conducted intensive studies to solve the above problems, and can use silicon nitride (SN) powder instead of silicon nitride (BN) powder as a separating material for producing a silicon nitride substrate. As a result, a silicon nitride substrate having excellent heat cycle resistance can be obtained, and a coating amount of silicon nitride (SN) powder having a specific specific surface area, particle size, and oxygen content and a low aluminum content as a separating material. The present invention has been made by finding that a silicon nitride substrate having good peelability, high strength, high thermal conductivity, and little deformation can be obtained by setting the production conditions such as the above to a specific range. That is, the present invention relates to the following.

〔態様１〕 窒化ケイ素粉末および焼結助剤を含む複数枚のグリーンシートをそれらの間に分離材を配置して積層し、前記分離材は窒化ケイ素粉を含み、
得られる積層体中の前記複数枚のグリーンシートを焼結し、
前記積層体から分離することによって複数枚の窒化ケイ素焼結体を得、
前記窒化ケイ素焼結体から窒化ケイ素基板を得る、
ことを特徴とする窒化ケイ素基板の製造方法。[Aspect 1] A plurality of green sheets containing silicon nitride powder and a sintering aid are laminated by arranging a separating material between them, and the separating material contains silicon nitride powder.
The plurality of green sheets in the obtained laminate are sintered and
By separating from the laminate, a plurality of silicon nitride sintered bodies can be obtained.
A silicon nitride substrate is obtained from the silicon nitride sintered body.
A method for manufacturing a silicon nitride substrate, which is characterized by the above.

〔態様２〕 前記複数枚のグリーンシートの前記焼結を、窒化ケイ素製囲繞体又は窒化ホウ素製囲繞体内で行うことを特徴とする態様１に記載の窒化ケイ素基板の製造方法。 [Aspect 2] The method for producing a silicon nitride substrate according to Aspect 1, wherein the sintering of the plurality of green sheets is performed in a silicon nitride enclosure or a boron nitride enclosure.

〔態様３〕 前記複数枚のグリーンシートの周りを窒化ケイ素粉で覆って前記焼結を行うことを特徴とする態様１又は２に記載の窒化ケイ素基板の製造方法。 [Aspect 3] The method for producing a silicon nitride substrate according to Aspect 1 or 2, wherein the plurality of green sheets are covered with silicon nitride powder to perform the sintering.

〔態様４〕 前記焼結後に得られる前記窒化ケイ素焼結体の表面に残存する前記分離材を除去することを特徴とする態様１〜３のいずれか一項に記載の窒化ケイ素基板の製造方法。 [Aspect 4] The method for producing a silicon nitride substrate according to any one of aspects 1 to 3, wherein the separating material remaining on the surface of the silicon nitride sintered body obtained after the sintering is removed. ..

〔態様５〕 前記分離材は、ＢＥＴ法により測定される比表面積が１ｍ２／ｇ以上２０ｍ２／ｇ以下であり、レーザ回折散乱法により測定される体積基準の５０％粒子径Ｄ５０が２０μｍ以下であり、かつ、酸素量が０．３重量％以上２重量％未満であり、
前記分離材は０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下の塗布量で前記グリーンシートの表面に塗布されていることを特徴とする態様１〜４のいずれか一項に記載の窒化ケイ素基板の製造方法。[Aspect 5] The separating material has a specific surface area measured by the BET method of 1 m 2 / g or more and 20 m 2 / g or less, and a volume-based 50% particle diameter D50 measured by the laser diffraction / scattering method is 20 μm or less. And the amount of oxygen is 0.3% by weight or more and less than 2% by weight.
The silicon nitride substrate according to any one of aspects 1 to 4, wherein the separating material is applied to the surface of the green sheet at a coating amount of 0.1 mg / cm 2 or more and 3 mg / cm 2 or less. Manufacturing method.

〔態様６〕 前記分離材のアルミニウム含有量が５０ｐｐｍ未満であることを特徴とする態様５に記載の窒化ケイ素基板の製造方法。 [Aspect 6] The method for producing a silicon nitride substrate according to Aspect 5, wherein the aluminum content of the separating material is less than 50 ppm.

〔態様７〕 前記焼結が、窒素雰囲気中でガス圧力０．１５ＭＰａ以上３ＭＰａ以下、焼結温度１７５０℃以上１９１０℃以下で６時間以上２２時間以下保持して行われることを特徴とする態様５又は６に記載の窒化ケイ素基板の製造方法。 [Aspect 7] Aspect 5 is characterized in that the sintering is carried out in a nitrogen atmosphere at a gas pressure of 0.15 MPa or more and 3 MPa or less and a sintering temperature of 1750 ° C. or more and 1910 ° C. or less for 6 hours or more and 22 hours or less. Alternatively, the method for manufacturing a silicon nitride substrate according to 6.

〔態様８〕 窒化ケイ素粒子と焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、厚さが０．５ｍｍ以下であり、前記基板の表面に窒化ホウ素粉を有していないことを特徴とする窒化ケイ素基板。 [Aspect 8] A silicon nitride substrate made of a silicon nitride sintered body containing silicon nitride particles and a sintering aid, having a thickness of 0.5 mm or less and having boron nitride powder on the surface of the substrate. A silicon nitride substrate characterized by not being used.

〔態様９〕 前記基板の表面における窒化ホウ素と窒化ケイ素の比がホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１５×１０−５以下であることを特徴とする態様８に記載の窒化ケイ素基板。 [Aspect 9] The ratio of boron nitride to silicon nitride on the surface of the substrate is 15 × 10 -5 or less in terms of the ratio (B / Si) of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si). The silicon nitride substrate according to aspect 8, wherein the silicon nitride substrate is characterized by the above.

〔態様１０〕 前記基板が窒化ホウ素（ＢＮ）を含まないことを特徴とする態様８に記載の窒化ケイ素基板。 [Aspect 10] The silicon nitride substrate according to aspect 8, wherein the substrate does not contain boron nitride (BN).

〔態様１１〕 窒化ケイ素粒子と焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、前記窒化ケイ素粒子は、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子を前記基板表面における面積比で３５％以下とし、かつ前記基板表面の算術平均表面粗さが０．０３μｍ以上０．５μｍ以下であり、前記基板表面における窒化ホウ素と窒化ケイ素の比がホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１５×１０−５以下であることを特徴とする窒化ケイ素基板。[Aspect 11] A silicon nitride substrate made of a silicon nitride sintered body containing silicon nitride particles and a sintering aid, wherein the silicon nitride particles have a minor axis a of 0.5 to 5 μm and a minor axis a with respect to the minor axis a. Columnar crystal particles having a major axis b ratio (b / a) of 2 or more have an area ratio of 35% or less on the substrate surface, and the arithmetic average surface roughness of the substrate surface is 0.03 μm or more and 0.5 μm or less. The ratio of boron nitride to silicon nitride on the surface of the substrate is 15 × 10-5 or less in terms of the ratio (B / Si) of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si). A characteristic silicon nitride substrate.

〔態様１２〕 前記基板の表面に窒化ホウ素粉を有していないことを特徴とする態様１１に記載の窒化ケイ素基板。 [Aspect 12] The silicon nitride substrate according to aspect 11, wherein the surface of the substrate does not have boron nitride powder.

〔態様１３〕 熱伝導率が室温において８０Ｗ／（ｍ・Ｋ）以上であり、４点曲げ強度が室温において８００ＭＰa以上であることを特徴とする態様１１または１２に記載の窒化ケイ素基板。 [Aspect 13] The silicon nitride substrate according to Aspect 11 or 12, wherein the thermal conductivity is 80 W / (m · K) or more at room temperature, and the four-point bending strength is 800 MPa or more at room temperature.

〔態様１４〕 前記分離材のアルミニウム含有量が５０ｐｐｍ未満であることを特徴とする態様１１〜１３のいずれか一項に記載の窒化ケイ素基板。 [Aspect 14] The silicon nitride substrate according to any one of aspects 11 to 13, wherein the aluminum content of the separating material is less than 50 ppm.

〔態様１５〕 厚さが０．５ｍｍ以下であることを特徴とする態様１１〜１４のいずれか一項に記載の窒化ケイ素基板。 [Aspect 15] The silicon nitride substrate according to any one of aspects 11 to 14, characterized in that the thickness is 0.5 mm or less.

〔態様１６〕 態様８〜１５のいずれか一項に記載の窒化ケイ素基板を用いたことを特徴とする絶縁基板および回路基板。 [Aspect 16] An insulating substrate and a circuit board, wherein the silicon nitride substrate according to any one of aspects 8 to 15 is used.

本発明の窒化ケイ素基板によれば、基板表面に窒化ホウ素（ＢＮ）粉が存在しないため、銅板を接合した際の耐ヒートサイクル性が改善され、長期にわたって安定して使用できる窒化ケイ素基板を得ることができる。 According to the silicon nitride substrate of the present invention, since boron nitride (BN) powder is not present on the surface of the substrate, the heat cycle resistance when the copper plates are joined is improved, and a silicon nitride substrate that can be used stably for a long period of time can be obtained. be able to.

また本発明によれば、複数枚のグリーンシートをＳＮ分離材を介して積層した後に窒化ケイ素焼結体を焼結した場合に、複数枚の窒化ケイ素焼結体を容易に剥離でき、高強度、高熱伝導を有し、かつ変形の少ない窒化ケイ素基板を得ることができる。特に、酸化マグネシウムを焼結助剤として用いる窒化ケイ素焼結体の場合に、特に本発明は有効である。 Further, according to the present invention, when a plurality of green sheets are laminated via an SN separator and then the silicon nitride sintered body is sintered, the plurality of silicon nitride sintered bodies can be easily peeled off and have high strength. , A silicon nitride substrate having high thermal conductivity and little deformation can be obtained. In particular, the present invention is particularly effective in the case of a silicon nitride sintered body using magnesium oxide as a sintering aid.

本発明の窒化ケイ素基板の製造方法においてグリーンシート２を積層した状態を示す図である。It is a figure which shows the state which laminated the green sheet 2 in the manufacturing method of the silicon nitride substrate of this invention. 本発明の窒化ケイ素基板の製造方法においてグリーンシート２を積層し詰め粉５をした状態を示す図である。It is a figure which shows the state which the green sheet 2 was laminated and packed powder 5 in the manufacturing method of the silicon nitride substrate of this invention. 窒化ケイ素焼結体表面の窒化ケイ素粒子８及び分離材９の微細構造を示す模式図である。It is a schematic diagram which shows the fine structure of the silicon nitride particle 8 and the separating material 9 on the surface of the silicon nitride sintered body.

本発明の窒化ケイ素基板の製造方法および窒化ケイ素基板について詳しく説明する。本発明の窒化ケイ素基板は絶縁性セラミックス基板として好適に用いられるものである。 The method for manufacturing the silicon nitride substrate and the silicon nitride substrate of the present invention will be described in detail. The silicon nitride substrate of the present invention is suitably used as an insulating ceramic substrate.

〔第一の側面：分離材として窒化ケイ素粉の使用〕
本発明のこの側面では、
「窒化ケイ素粉末および焼結助剤を含む複数枚のグリーンシートをそれらの間に分離材を配置して積層し、前記分離材は窒化ケイ素粉を含み、
得られる積層体中の前記複数枚のグリーンシートを焼結し、
前記積層体から分離することによって複数枚の窒化ケイ素焼結体を得、
前記窒化ケイ素焼結体から窒化ケイ素基板を得る、
ことを特徴とする窒化ケイ素基板の製造方法」と、
「窒化ケイ素粒子と焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、厚さが０．５ｍｍ以下であり、前記基板の表面に窒化ホウ素粉を有していないことを特徴とする窒化ケイ素基板」
が提供される。[First aspect: use of silicon nitride powder as a separating material]
In this aspect of the invention,
"A plurality of green sheets containing silicon nitride powder and a sintering aid are laminated by arranging a separating material between them, and the separating material contains silicon nitride powder.
The plurality of green sheets in the obtained laminate are sintered and
By separating from the laminate, a plurality of silicon nitride sintered bodies can be obtained.
A silicon nitride substrate is obtained from the silicon nitride sintered body.
A method for manufacturing a silicon nitride substrate, which is characterized by this. "
"A silicon nitride substrate made of a silicon nitride sintered body containing silicon nitride particles and a sintering aid, having a thickness of 0.5 mm or less and having no boron nitride powder on the surface of the substrate. Silicon Nitride Substrate Featuring
Is provided.

従来、分離材を介して、窒化ケイ素粉末および焼結助剤を含む複数枚のグリーンシートを積層して焼結する際には、原料の窒化ケイ素粉末の焼結温度より高い焼結あるいは反応温度を有する窒化ホウ素粉が分離材として用いられ、板状窒化ケイ素焼結用の分離材として窒化ケイ素粉は用いられていない。しかし、本発明者は、従来技術の予想に反して、意外にも、窒化ケイ素粉が板状窒化ケイ素焼結用の分離材として用いることができること、しかも板状焼結体表面に窒化ホウ素粉が残留しないので、得られる窒化ケイ素基板に銅を接合した際にヒートサイクル性が改良される効果を有する、優れた分離材であることを見出した。分離材は、焼結すべき基材と全く反応しないものではなく、かえって基材とある程度の反応をしないと分離材として機能を発揮できないので、窒化ケイ素粉は、基材と反応することは分離材としての使用から排除されるものではなく、基材に対して異物（不純物）でない点で、板状窒化ケイ素焼結用の分離材として優れていることを確認した。 Conventionally, when a plurality of green sheets containing silicon nitride powder and a sintering aid are laminated and sintered via a separating material, the sintering or reaction temperature is higher than the sintering temperature of the raw material silicon nitride powder. Boron nitride powder having the above is used as a separating material, and silicon nitride powder is not used as a separating material for sheet-shaped silicon nitride sintering. However, contrary to the expectation of the prior art, the present inventor can unexpectedly use the silicon nitride powder as a separating material for sheet-shaped silicon nitride sintering, and the boron nitride powder on the surface of the plate-shaped sintered body. It was found that it is an excellent separating material having an effect of improving the heat cycle property when copper is bonded to the obtained silicon nitride substrate because the residue does not remain. The silicon nitride powder does not react with the base material at all because the separating material does not react at all with the base material to be sintered, but rather cannot function as a separating material unless it reacts with the base material to some extent. It was confirmed that it is excellent as a separating material for plate-shaped silicon nitride sintering in that it is not excluded from its use as a material and is not a foreign substance (impurity) with respect to the base material.

本発明のこの側面では、窒化ケイ素基板の製造方法において、まず、原料調整・混合工程として、窒化ケイ素粉末に焼結助剤となるセラミックス粉末を分散媒となる有機溶剤を使用し、ボールミル等で混合し、さらに、バインダー及び可塑剤と混合してスラリーを作製する。 In this aspect of the present invention, in the method for manufacturing a silicon nitride substrate, first, as a raw material preparation / mixing step, an organic solvent is used as a dispersion medium of ceramic powder as a sintering aid in silicon nitride powder, and a ball mill or the like is used. It is mixed and further mixed with a binder and a plasticizer to prepare a slurry.

窒化ケイ素粉末としては、シート成形法及びグリーンシートの焼結による窒化ケイ素基板の製造に原料として用いられる任意の窒化ケイ素粉末を用いることができるが、好ましい窒化ケイ素粉末として、比表面積が１０．０ｍ２／ｇ以上、酸素含有量が１．０ｗｔ％以上、アルミニウム含有量が１００ｐｐｍ未満であってよく、より好ましくは、比表面積が１３．０ｍ２／ｇ以上、酸素含有量が１．２ｗｔ％以上２．３ｗｔ％以下、アルミニウム含有量が５０ｐｐｍ未満である。窒化ケイ素粉末は、１つの態様において、比表面積が２５．０ｍ２／ｇ以下、酸素含有量が２．３ｗｔ％以下であってよい。As the silicon nitride powder, any silicon nitride powder used as a raw material for producing a silicon nitride substrate by a sheet molding method and sintering of a green sheet can be used, but a preferable silicon nitride powder has a specific surface area of 10.0 m. It may be 2 / g or more, the oxygen content is 1.0 wt% or more, and the aluminum content may be less than 100 ppm, more preferably the specific surface area is 13.0 m 2 / g or more and the oxygen content is 1.2 wt% or more. It is 2.3 wt% or less and the aluminum content is less than 50 ppm. In one embodiment, the silicon nitride powder may have a specific surface area of 25.0 m 2 / g or less and an oxygen content of 2.3 wt% or less.

焼結助剤としては、窒化ケイ素基板の製造に用いられる任意の焼結助剤を用いることができ、特に限定されないが、酸化物焼結助剤が好適に用いられる。酸化物としては、酸化マグネシウム、希土類元素の酸化物は、希土類元素としてはＹ、Ｌａ、Ｃｅ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ等があげられるが、酸化物Ｙ２Ｏ３が好ましい。焼結助剤として例えば二酸化ケイ素を用いてもよい。As the sintering aid, any sintering aid used in the production of the silicon nitride substrate can be used, and the oxide sintering aid is preferably used without particular limitation. Examples of oxides include magnesium oxide and oxides of rare earth elements, and examples of rare earth elements include Y, La, Ce, Nd, Pm, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu. However, oxide Y 2 O 3 is preferable. For example, silicon dioxide may be used as the sintering aid.

例えば、窒化ケイ素原料９８質量％から８１質量％に対して、酸化マグネシウムの添加量０．５質量％から４質量％、希土類元素の酸化物の添加量１．５質量％から１５質量％の範囲であってよく、より好ましくは、窒化ケイ素原料９７．５質量％から９１質量％に対して、酸化マグネシウムの添加量１．０質量％から３質量％、かつ希土類元素の酸化物の添加量１．５質量％から６質量％の範囲であってよい。 For example, the amount of magnesium oxide added is in the range of 0.5% by mass to 4% by mass and the amount of rare earth element oxide added is in the range of 1.5% by mass to 15% by mass with respect to 98% by mass to 81% by mass of the silicon nitride raw material. The amount of magnesium oxide added is 1.0% by mass to 3% by mass, and the amount of rare earth element oxide added is 1 with respect to 97.5% by mass to 91% by mass of the silicon nitride raw material. It may be in the range of .5% by mass to 6% by mass.

高熱伝導率の窒化ケイ素基板を得るため焼結助剤としては、酸化マグネシウム（ＭｇＯ）および希土類元素の酸化物（ＲＥｘＯy）が好ましい。酸化マグネシウムは比較的低温で液相を形成するため、窒化ケイ素焼結体の焼結を促進することができ、且つ、窒化ケイ素粒子に固溶し難いため、窒化ケイ素基板の熱伝導率を高くすることができる。また希土類元素としてはＹ、Ｌａ、Ｃｅ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ等があげられるが、中でもＹの酸化物Ｙ２Ｏ３は窒化ケイ素基板の高密度化に有効であり、より好ましい。Magnesium oxide (MgO) and an oxide of a rare earth element (RExOy) are preferable as the sintering aid in order to obtain a silicon nitride substrate having high thermal conductivity. Since magnesium oxide forms a liquid phase at a relatively low temperature, it is possible to promote the sintering of the silicon nitride sintered body, and it is difficult to dissolve in the silicon nitride particles, so that the thermal conductivity of the silicon nitride substrate is high. can do. Examples of rare earth elements include Y, La, Ce, Nd, Pm, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, etc. Among them, Y oxide Y 2 O 3 is silicon nitride. It is effective for increasing the density of the substrate, which is more preferable.

次に、成形工程として、上記混合して作製したスラリーを必要に応じて粘度調整し、これをドクターブレード法、押し出し成形法、もしくはそれに準じた方法により所定厚さのシート状に成形する。このときのシート成形体の板厚は、半導体パワーモジュールなどの用途に応じて適宜決定できるが、０．１ｍｍから０．６ｍｍ程度までの範囲とすること、さらには０．２ｍｍから０．５ｍｍ程度、さらには０．２ｍｍから０．４０ｍｍ程度までの範囲とすることが好ましい。シート成形体の板厚は、任意の十箇所以上の測定値の平均値とする。 Next, as a molding step, the viscosity of the slurry produced by the above mixing is adjusted as necessary, and this is molded into a sheet having a predetermined thickness by a doctor blade method, an extrusion molding method, or a method similar thereto. The plate thickness of the sheet molded product at this time can be appropriately determined depending on the application such as a semiconductor power module, but it should be in the range of about 0.1 mm to 0.6 mm, and further, about 0.2 mm to 0.5 mm. Further, it is preferably in the range of about 0.2 mm to 0.40 mm. The plate thickness of the sheet molded product shall be the average value of the measured values at any ten or more points.

次に、グリーンシートを所望の形状に切断した後、切断されたグリーンシートの片面もしくは両面に分離材を塗布した後、分離材が塗布されたグリーンシートを複数枚、積層して焼結する。積層体の最下層の下側、最上層の上側には、分離材を塗布することが好ましいが、塗布しなくてもよい。 Next, after cutting the green sheet into a desired shape, a separating material is applied to one or both sides of the cut green sheet, and then a plurality of green sheets coated with the separating material are laminated and sintered. It is preferable to apply a separating material to the lower side of the lowermost layer and the upper side of the uppermost layer of the laminate, but it is not necessary to apply the separating material.

本発明及び第一の側面において用いる分離材は、窒化ケイ素（ＳＮ）粉を含む粉末である。本発明及び第一の側面によれば、窒化ケイ素のグリーンシート間の分離材として窒化ケイ素（ＳＮ）粉を用いることにより、焼結後に窒化ケイ素焼結体の表面に従来技術のように窒化ホウ素（ＢＮ）粉が残留することがなく、残留するとしても窒化ケイ素（ＳＮ）粉であるので、窒化ケイ素基板を銅と接合した際のヒートサイクル性に優れることができる。分離材としては窒化ケイ素（ＳＮ）粉だけを好ましく用いることができるが、分離材として窒化ケイ素（ＳＮ）粉を用いる効果が得られる限り、窒化ホウ素（ＢＮ）粉が一部含まれてもよい。例えば、窒化ホウ素（ＢＮ）粉を３０重量％以下、さらに１０重量％以下含んでもよい。しかし、本発明では好ましく分離材として窒化ケイ素（ＳＮ）粉だけを用いるので、以下では特に断らない限り分離材として窒化ケイ素（ＳＮ）粉を用いるものとして説明する。 The separating material used in the present invention and the first aspect is a powder containing silicon nitride (SN) powder. According to the present invention and the first aspect, by using silicon nitride (SN) powder as a separating material between the green sheets of silicon nitride, boron nitride is applied to the surface of the silicon nitride sintered body after sintering as in the prior art. Since the (BN) powder does not remain and even if it does remain, it is silicon nitride (SN) powder, so that the heat cycle property when the silicon nitride substrate is bonded to copper can be excellent. Although only silicon nitride (SN) powder can be preferably used as the separating material, a part of boron nitride (BN) powder may be contained as long as the effect of using silicon nitride (SN) powder as the separating material can be obtained. .. For example, boron nitride (BN) powder may be contained in an amount of 30% by weight or less, and further 10% by weight or less. However, since only silicon nitride (SN) powder is preferably used as the separating material in the present invention, it will be described below assuming that silicon nitride (SN) powder is used as the separating material unless otherwise specified.

分離材の比表面積は、ＢＥＴ法により測定される比表面積が１ｍ２／ｇ以上２０ｍ２／ｇ以下であることが好ましい。分離材の比表面積は、分離材のグリーンシート表面への密着性を考慮して選択される。比表面積が小さすぎて密着性が不足すると取扱い時に剥離し易くなる一方、比表面積が大きすぎると焼結時にグリーンシート中の焼結助剤と著しく反応して、分離材を介して焼結体同士がくっついて剥離出来なくなるおそれがある。比表面積は、１ｍ２／ｇ以上１２ｍ２／ｇ以下、２ｍ２／ｇ以上７ｍ２／ｇ以下であることがより好ましい。The specific surface area of the separating material is preferably such that the specific surface area measured by the BET method is 1 m 2 / g or more and 20 m 2 / g or less. The specific surface area of the separating material is selected in consideration of the adhesion of the separating material to the surface of the green sheet. If the specific surface area is too small and the adhesion is insufficient, it will be easy to peel off during handling, while if the specific surface area is too large, it will react significantly with the sintering aid in the green sheet during sintering, and the sintered body will react through the separating material. There is a risk that they will stick to each other and cannot be peeled off. The specific surface area is more preferably 1 m 2 / g or more and 12 m 2 / g or less, 2 m 2 / g or more and 7 m 2 / g or less.

分離材の平均粒子径としては、レーザ回折散乱法により測定される体積基準の５０％粒子径（Ｄ５０）が２０μｍ以下であることが好ましい。分離材のＤ５０が大きすぎると、分離材のグリーンシートへの密着性が悪くなって取扱い時に剥離し易い。Ｄ５０は、１０μｍ以下、５μｍ以下、３μｍ以下、２μｍ以下であることがより好ましい。Ｄ５０は１μｍ以下であってよい。Ｄ５０の下限は限定されないが、Ｄ５０は０．３μｍ以上であってよい。体積基準の５０％粒子径（Ｄ５０）とは、体積基準の粒子径の累積値が全累積値の５０％になる粒子径をいう。 As the average particle size of the separating material, it is preferable that the volume-based 50% particle size (D50) measured by the laser diffraction / scattering method is 20 μm or less. If the D50 of the separating material is too large, the adhesion of the separating material to the green sheet deteriorates and it is easy to peel off during handling. D50 is more preferably 10 μm or less, 5 μm or less, 3 μm or less, and 2 μm or less. D50 may be 1 μm or less. The lower limit of D50 is not limited, but D50 may be 0.3 μm or more. The volume-based 50% particle size (D50) means a particle size in which the cumulative value of the volume-based particle size is 50% of the total cumulative value.

分離材の酸素量は０．１質量％以上２．０質量％未満であることが好ましい。分離材の酸素量は、焼結時に分離材が窒化ケイ素焼結体の焼結助剤成分と、適度に反応して、窒化ケイ素焼結体の表面に存在して、隣接する窒化ケイ素焼結体同士の接着を防ぎ、剥離性を良くするとともに、窒化ケイ素焼結体の変形を防止できる範囲になるように選択することが望ましい。酸素量が多すぎると、焼結時にグリーンシート中の焼結助剤と著しく反応して、分離材を介して焼結体同士がくっついて剥離出来なくなる。特に、この現象は、焼結助剤として酸化マグネシウムを用いた場合、焼結助剤との反応が起こり易く、窒化ケイ素基板の厚さが０．１〜０．６ｍｍの場合に顕著になる。一方、酸素量が少なすぎると、焼結時に分離材と窒化ケイ素焼結体の反応がほとんど起こらないため、焼結収縮に伴い分離材が基板表面を移動することもあり、グリーンシート表面に塗布された分離材の均一性が損なわれ、分離材の存在割合の少ない場所が発生して隣接する窒化ケイ素焼結体が接着し剥離性が損なわれる。分離材の酸素量は上記観点から０．３〜２．０質量％未満、０．３〜１．２質量％がより好ましい。 The oxygen content of the separating material is preferably 0.1% by mass or more and less than 2.0% by mass. The amount of oxygen in the separating material is such that the separating material reacts appropriately with the sintering aid component of the silicon nitride sintered body during sintering and is present on the surface of the silicon nitride sintered body, and the adjacent silicon nitride sintered body is present. It is desirable to select a range that can prevent the silicon nitride sintered body from being deformed while preventing the bodies from adhering to each other and improving the peelability. If the amount of oxygen is too large, it reacts remarkably with the sintering aid in the green sheet at the time of sintering, and the sintered bodies stick to each other via the separating material and cannot be peeled off. In particular, this phenomenon is likely to occur when magnesium oxide is used as the sintering aid, and becomes remarkable when the thickness of the silicon nitride substrate is 0.1 to 0.6 mm. On the other hand, if the amount of oxygen is too small, the reaction between the separating material and the silicon nitride sintered body hardly occurs during sintering, so the separating material may move on the substrate surface due to sintering shrinkage, and is applied to the surface of the green sheet. The uniformity of the separated material is impaired, a place where the abundance ratio of the separating material is low is generated, and the adjacent silicon nitride sintered bodies are adhered to each other, and the peelability is impaired. From the above viewpoint, the oxygen content of the separating material is more preferably 0.3 to less than 2.0% by mass and more preferably 0.3 to 1.2% by mass.

分離材のアルミニウム含有量は１００ｐｐｍ未満であることが好ましい。アルミニウム含有量が多すぎると、焼結後にβ型窒化ケイ素粒子内部に固溶するアルミニウムが増加する。固溶したアルミニウムイオンによるフォノン散乱は熱伝導率低下の原因となり、得られる窒化ケイ素基板の熱伝導率が低下するので好ましくない。アルミニウム含有量の好ましい範囲は５０ｐｐｍ以下、さらには４０ｐｐｍ以下であることがより好ましい。 The aluminum content of the separating material is preferably less than 100 ppm. If the aluminum content is too high, the amount of aluminum that dissolves inside the β-type silicon nitride particles after sintering increases. Phonon scattering by solid-melted aluminum ions causes a decrease in thermal conductivity, which is not preferable because the thermal conductivity of the obtained silicon nitride substrate is reduced. The preferable range of the aluminum content is 50 ppm or less, more preferably 40 ppm or less.

分離材のグリーンシート表面への塗布量は、０．１ｍｇ／ｃｍ２以上４．０ｍｇ／ｃｍ２以下であることが好ましい。分離材の塗布量が多すぎると、多量の分離材が焼結過程で窒化ケイ素焼結体表面の窒化ケイ素粒子間に容易に入り込み、収縮を阻害するため、窒化ケイ素焼結体の密度が低下し、強度も低下する。一方、分離材の塗布量が少なすぎると、分離材が不十分となる箇所が出現し、隣接する窒化ケイ素焼結体間の反応により、窒化ケイ素焼結体同士が付着してしまい、剥離出来なくなる。上記観点から、分離材の好ましい塗布量は、０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下、さらには０．２ｍｇ／ｃｍ２以上１ｍｇ／ｃｍ２以下であることがより好ましい。The amount of the separating material applied to the surface of the green sheet is preferably 0.1 mg / cm 2 or more and 4.0 mg / cm 2 or less. If the amount of the separating material applied is too large, a large amount of separating material easily enters between the silicon nitride particles on the surface of the silicon nitride sintered body during the sintering process and hinders shrinkage, so that the density of the silicon nitride sintered body decreases. However, the strength is also reduced. On the other hand, if the amount of the separating material applied is too small, there will be places where the separating material is insufficient, and due to the reaction between the adjacent silicon nitride sintered bodies, the silicon nitride sintered bodies will adhere to each other and can be peeled off. It disappears. From the above viewpoint, the preferable coating amount of the separating material is 0.1 mg / cm 2 or more and 3 mg / cm 2 or less, and more preferably 0.2 mg / cm 2 or more and 1 mg / cm 2 or less.

分離材の塗布方法としては、グリーンシート表面へ均一に塗布するため、分離材を有機溶媒に分散させたスラリーを作製した後に、スプレー式の塗布機により霧状にして片面若しくは両面に塗布してもよいし、分離材を刷毛で直接片面若しくは両面に塗布してもよい。ここで、スラリーを作製する際には、分離材と有機溶媒とを窒化ケイ素製ボールを用いて混合することが好ましい。有機溶媒を用いてスラリーとする理由は、水を用いてスラリーを作製した場合、水存在下では分離材の酸素量が増加し、剥離性が悪化するためである。分離材と有機溶媒の割合は重量比で分離材／有機溶媒＝１／１０から１／２程度の範囲が適当である。また、窒化ケイ素製ボールを用いて混合するのは、分離材の凝集を壊砕し、均一分散させるためである。 As a method of applying the separating material, in order to apply it uniformly to the surface of the green sheet, after preparing a slurry in which the separating material is dispersed in an organic solvent, it is atomized by a spray-type coating machine and applied to one or both sides. Alternatively, the separating material may be applied directly to one side or both sides with a brush. Here, when producing the slurry, it is preferable to mix the separating material and the organic solvent using silicon nitride balls. The reason why the slurry is prepared by using an organic solvent is that when the slurry is prepared by using water, the amount of oxygen in the separating material increases in the presence of water and the peelability deteriorates. The ratio of the separating material to the organic solvent is appropriately in the range of about 1/10 to 1/2 of the separating material / organic solvent in terms of weight ratio. Further, the reason for mixing using the silicon nitride balls is to crush the agglomeration of the separating material and uniformly disperse it.

分離材を有機溶媒に分散させたスラリーが塗布、乾燥されたグリーンシートは数枚〜数十枚重ねて、積層された後、グリーンシート中のバインダー等の有機成分を除去するために脱脂を行う。脱脂は９００℃以下の大気中、もしくは窒素、アルゴン等の不活性雰囲気中で行うことが好ましい。積層するグリーンシートの枚数は５〜５０枚が好ましい。 A slurry in which the separating material is dispersed in an organic solvent is applied, and several to several tens of dried green sheets are stacked and laminated, and then degreasing is performed to remove organic components such as binders in the green sheet. .. The degreasing is preferably performed in the air at 900 ° C. or lower, or in an inert atmosphere such as nitrogen or argon. The number of green sheets to be laminated is preferably 5 to 50.

脱脂工程の後、グリーンシートを焼結する（焼結工程）。図１に、複数のグリーンシート２を分離材１を介在して積層し、セッタ３上に置き、周囲をスペーサ４が囲い、さらに頂部をセッタ３で押さえた状態の例を断面図として示す。上下のセッタ３と周囲のスペーサ４とによって、複数のグリーンシート２の積層体の囲繞体が形成されている。セッタ３と周囲のスペーサ４とに囲まれた複数のグリーンシート２の積層体は、加熱炉内に配置され、所定の温度に加熱される。本発明において、セッタ３及びスペーサ４は、窒化ホウ素製であってよいが、好ましくは窒化ケイ素製である。セッタ３及びスペーサ４が窒化ホウ素製であると、焼結時にセッタ３及びスペーサ４から焼結体に窒化ホウ素が蒸気拡散するので、窒化ケイ素製のセッタ３及びスペーサ４を用いることが好ましい。窒化ケイ素製のセッタ３及びスペーサ４は、窒化ケイ素焼結体からなればよいが、窒化ケイ素焼結体からの焼結助剤などの蒸散を抑えるためにグリーンシート２の最高焼結温度より高い温度で焼成したものを用いてよい。また、図２を参照すると、窒化ホウ素製のセッタ３及びスペーサ４を用いる場合であっても、複数のグリーンシート２の積層体の周囲に窒化ケイ素粉を詰め粉５で覆うことによっても、窒化ホウ素製のセッタ３及びスペーサ４から焼結体への窒化ホウ素の蒸気拡散を防止することができるので好ましい。さらに、窒化ケイ素製のセッタ３及びスペーサ４を用い、かつ窒化ケイ素粉を詰め粉５で覆ってもよい。なお、本発明において、分離材としての窒化ケイ素粉を介在した複数のグリーンシート２の積層体を熱処理する装置は、図１及び図２に示す態様に限定されるものではない。 After the degreasing step, the green sheet is sintered (sintering step). FIG. 1 is a cross-sectional view showing an example of a state in which a plurality of green sheets 2 are laminated with a separating material 1 interposed therebetween, placed on a setter 3, surrounded by a spacer 4, and further pressed by the setter 3. The upper and lower setters 3 and the surrounding spacers 4 form a surrounding body of a plurality of laminated bodies of the green sheets 2. The laminate of the plurality of green sheets 2 surrounded by the setter 3 and the surrounding spacer 4 is arranged in a heating furnace and heated to a predetermined temperature. In the present invention, the setter 3 and the spacer 4 may be made of boron nitride, but are preferably made of silicon nitride. If the setter 3 and the spacer 4 are made of boron nitride, boron nitride diffuses from the setter 3 and the spacer 4 into the sintered body at the time of sintering. Therefore, it is preferable to use the setter 3 and the spacer 4 made of silicon nitride. The silicon nitride setter 3 and spacer 4 may be made of a silicon nitride sintered body, but the temperature is higher than the maximum sintering temperature of the green sheet 2 in order to suppress evaporation of a sintering aid and the like from the silicon nitride sintered body. Those fired at a temperature may be used. Further, referring to FIG. 2, even when the boron nitride setter 3 and the spacer 4 are used, the silicon nitride powder can be wrapped around the laminate of the plurality of green sheets 2 with the stuffing powder 5 to nitrid the mixture. It is preferable because it is possible to prevent the vapor diffusion of boron nitride from the boron-made setter 3 and the spacer 4 to the sintered body. Further, a silicon nitride setter 3 and a spacer 4 may be used, and the silicon nitride powder may be covered with the filling powder 5. In the present invention, the apparatus for heat-treating a laminate of a plurality of green sheets 2 having silicon nitride powder as a separating material is not limited to the embodiments shown in FIGS. 1 and 2.

分離材を介在したグリーンシートの積層体は、脱脂及び焼結される。分離材を介在したグリーンシートの積層体は、耐熱性セッタ上に設置され、側面を耐熱性スペーサで囲んでから、頂面を耐熱性セッタで押圧した状態で、加熱してよい。セッタ及びスペーサ（本明細書においてセッタとスペーサを合わせて囲繞体ともいう。）は従来の窒化ホウ素（ＢＮ）製のほか、本発明によれば、好ましく窒化ケイ素（ＳＮ）製のものにすることができる。囲繞体は窒化ホウ素（ＢＮ）製であっても、分離材として窒化ケイ素（ＳＮ）粉を用いると、焼結後の窒化ケイ素基板表面に窒化ホウ素（ＢＮ）粉が残留しないので、得られる窒化ケイ素基板は銅と接合した際の耐熱性、ヒートサイクル性に優れることができる。また、窒化ホウ素（ＢＮ）粉を用いないので、窒化ケイ素基板表面に含まれるＢＮの含有量も顕著に少なくすることができる。さらに、囲繞体を窒化ケイ素（ＳＮ）製にすれば、ＢＮの蒸気拡散に基づく混入も完全に防止することができる。また、グリーンシートの積層体の周りに窒化ケイ素（ＳＮ）粉を詰めて焼結することによっても、ＢＮの混入を防止することができる。 The laminate of green sheets with the separating material interposed is degreased and sintered. The laminated body of the green sheet with the separating material interposed therebetween may be placed on the heat-resistant setter, the side surface may be surrounded by the heat-resistant spacer, and then the top surface may be heated while being pressed by the heat-resistant setter. The setter and the spacer (in the present specification, the setter and the spacer are collectively referred to as a surrounding body) are made of conventional boron nitride (BN) or, according to the present invention, preferably made of silicon nitride (SN). Can be done. Even if the enclosure is made of boron nitride (BN), if silicon nitride (SN) powder is used as the separating material, the boron nitride (BN) powder does not remain on the surface of the silicon nitride substrate after sintering, so that the obtained nitridation can be obtained. The silicon substrate can be excellent in heat resistance and heat cycle property when bonded to copper. Further, since the boron nitride (BN) powder is not used, the content of BN contained on the surface of the silicon nitride substrate can be remarkably reduced. Further, if the surrounding body is made of silicon nitride (SN), contamination due to vapor diffusion of BN can be completely prevented. Further, by packing silicon nitride (SN) powder around the laminated body of the green sheet and sintering it, it is possible to prevent BN from being mixed.

脱脂後のグリーンシートは例えば１０Ｐａ以下の真空にして残留ガスを除去した後、真空中あるいは希ガスなどの不活性雰囲気中でもよいが、窒素で置換した雰囲気中で焼結することが好ましい。 The degreased green sheet may be vacuumed at 10 Pa or less to remove residual gas, and then sintered in a vacuum or in an inert atmosphere such as a rare gas, but preferably in an atmosphere substituted with nitrogen.

窒素雰囲気圧力は、例えば１０ＭＰａ以下の高圧でもよいが、好ましくは０．１５ＭＰａ以上３ＭＰａ以下の低圧であってよい。高圧にするにはコストがかかり、一方、雰囲気ガス圧力が低すぎると、焼結時の最高保持温度を好適な焼成温度にあげることが困難になる。 The nitrogen atmospheric pressure may be, for example, a high pressure of 10 MPa or less, but preferably a low pressure of 0.15 MPa or more and 3 MPa or less. High pressure is costly, while if the atmospheric gas pressure is too low, it becomes difficult to raise the maximum holding temperature during sintering to a suitable firing temperature.

焼結温度は、例えば１６００℃以上１９５０℃以下であってよいが、１７５０℃以上１９００℃以下であることがより好ましく、例えば、１７９０℃以上１８８０℃以下であってよい。焼結時の最高保持温度が低いと、焼結の進行速度が遅く、緻密な窒化ケイ素基板を得ることが難しい。あるいは、低い最高保持温度で緻密な窒化ケイ素基板が得られたとしても、柱状のβ型窒化ケイ素粒子の成長が不十分になるので、低い熱伝導率の窒化ケイ素基板しか得られないので、熱伝導率をあげることは困難である。最高保持温度が高すぎると、柱状のβ型窒化ケイ素粒子の成長が著しく速くなり、窒化ケイ素基板表面の凹凸が大きくなり、隣接する窒化ケイ素焼結体間の反応により、窒化ケイ素焼結体同士が付着してしまい、剥離が困難になる。 The sintering temperature may be, for example, 1600 ° C. or higher and 1950 ° C. or lower, but more preferably 1750 ° C. or higher and 1900 ° C. or lower, and for example, 1790 ° C. or higher and 1880 ° C. or lower. If the maximum holding temperature at the time of sintering is low, the progress rate of sintering is slow, and it is difficult to obtain a dense silicon nitride substrate. Alternatively, even if a dense silicon nitride substrate can be obtained at a low maximum holding temperature, the growth of columnar β-type silicon nitride particles is insufficient, so that only a silicon nitride substrate having a low thermal conductivity can be obtained. It is difficult to increase the conductivity. If the maximum holding temperature is too high, the growth of columnar β-type silicon nitride particles becomes extremely fast, the surface irregularities of the silicon nitride substrate become large, and the reaction between adjacent silicon nitride sintered bodies causes the silicon nitride sintered bodies to grow together. Will adhere, making peeling difficult.

焼結温度、特に最高保持温度における保持時間は、一般的には４時間以上、また３０時間以下であってよいが、６時間以上２２時間以下の程度が好ましく、焼成温度のプロファイルなどによっても変化してよい。 The holding time at the sintering temperature, particularly the maximum holding temperature, may be generally 4 hours or more and 30 hours or less, but is preferably about 6 hours or more and 22 hours or less, and changes depending on the profile of the firing temperature and the like. You can do it.

窒化ケイ素焼結体は、特に表面に窒化ホウ素粉を含まないので、そのまま窒化ケイ素基板として用いてもよいが、ブラスト加工等による表面処理を施すことが好ましい。ブラスト加工は例えば、１０〜１００μｍのＳｉＣ砥粒を窒化ケイ素基板表面に噴射することによって、表面に突出した窒化ケイ素粒子を削り、表面粗さを低減して、金属板との接合性を良好にするために実施する。ブラスト加工、さらにはラップ処理によって除去される窒化ケイ素基板の表面の深さ（厚さ）は、例えば、３０μｍ以下であってよいが、好ましくは２０μｍ以下、さらには１０μｍ以下、特には５μｍ以下であってよい。本発明の第一の側面によれば、最低限のブラスト加工によって、分離材の除去、優れた表面特性を実現することができる。 Since the surface of the silicon nitride sintered body does not contain boron nitride powder, it may be used as it is as a silicon nitride substrate, but it is preferable to perform surface treatment such as blasting. In the blasting process, for example, by injecting 10 to 100 μm SiC abrasive particles onto the surface of the silicon nitride substrate, the silicon nitride particles protruding from the surface are scraped off, the surface roughness is reduced, and the bondability with the metal plate is improved. To carry out. The surface depth (thickness) of the silicon nitride substrate removed by blasting or wrapping may be, for example, 30 μm or less, but preferably 20 μm or less, further 10 μm or less, and particularly 5 μm or less. It may be there. According to the first aspect of the present invention, it is possible to remove the separating material and realize excellent surface properties with a minimum of blasting.

上記した窒化ケイ素基板の製造方法を採用することにより、複数枚の窒化ケイ素焼結体を容易に剥離でき、焼結体表面の凹凸も適正なレベルに制御されているため、高強度を有し、かつ変形の少ない窒化ケイ素基板を得ることができる。また、窒化ケイ素基板表面にＢＮ粉が存在しないため、さらには基板がＢＮを含まないか極微量にしか含まないため、銅板を接合した際の耐ヒートサイクル性が改善され、長期にわたって安定して使用できる。 By adopting the above-mentioned method for manufacturing a silicon nitride substrate, a plurality of silicon nitride sintered bodies can be easily peeled off, and the unevenness on the surface of the sintered body is controlled to an appropriate level, so that the silicon nitride has high strength. Moreover, it is possible to obtain a silicon nitride substrate with less deformation. In addition, since BN powder is not present on the surface of the silicon nitride substrate, and because the substrate does not contain BN or contains only a very small amount, the heat cycle resistance when the copper plates are joined is improved and stable for a long period of time. Can be used.

この側面によれば、分離材として従来のＢＮ粉に代えてＳＮ粉を用いることで、基板表面にＢＮ粉が残留していない窒化ケイ素基板を得ることができる。この側面において、基板表面のＢＮは蛍光Ｘ線分析によって分析できるが、窒化ケイ素基板は、ホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１５×１０−５以下、１２×１０−５以下、１０×１０−５以下、８×１０−５以下であってよく、さらには６．５×１０−５未満、５×１０−５未満であることができる。特に、焼結の際にグリーンシート積層体を窒化ケイ素製の囲繞体（セッタ）内に設置したり、グリーンシート積層体の周りを窒化ケイ素粉で覆って焼結することで、基板表面にＢＮ粉及び本体にＢＮを含まない窒化ケイ素基板を得ることができる。この側面の窒化ケイ素基板は、ＢＮ含有量を任意に少なくすることができ、蛍光Ｘ線分析によってホウ素（Ｂ）が検出限界以下とし、ＢＮを含まないものにすることができる。窒化ケイ素基板がＢＮを含まないとは、蛍光Ｘ線分析によってホウ素（Ｂ）が検出限界以下であることを意味するが、本発明では分離材にも囲繞体にも窒化ケイ素を用いることで、窒化ケイ素基板がＢＮを完全に含まないものであってよい。According to this aspect, by using SN powder instead of the conventional BN powder as the separating material, a silicon nitride substrate in which BN powder does not remain on the surface of the substrate can be obtained. In this aspect, the BN on the surface of the substrate can be analyzed by fluorescent X-ray analysis, but the silicon nitride substrate is obtained by the ratio (B / Si) of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si). It may be 15 × 10-5 or less, 12 × 10-5 or less, 10 × 10-5 or less, 8 × 10-5 or less, and further less than 6.5 × 10-5 and less than 5 × 10-5 . There can be. In particular, at the time of sintering, the green sheet laminate is installed in a silicon nitride enclosure (setter), or the green sheet laminate is covered with silicon nitride powder and sintered to BN on the substrate surface. A silicon nitride substrate containing no BN in the powder and the main body can be obtained. The silicon nitride substrate on this side can have an arbitrarily low BN content, and boron (B) can be set to be below the detection limit by fluorescent X-ray analysis and can be free of BN. The fact that the silicon nitride substrate does not contain BN means that boron (B) is below the detection limit by fluorescent X-ray analysis. However, in the present invention, silicon nitride is used for both the separating material and the enclosure. The silicon nitride substrate may be completely BN-free.

この側面における窒化ケイ素基板は、分離材を用いて製造される窒化ケイ素基板、厚さが例えば０．５ｍｍ以下の窒化ケイ素基板に好適に適用される。さらには、厚さは０．４５ｍｍ以下、０．４ｍｍ以下、０．３５ｍｍ以下であってよい。また厚さが０．１ｍｍ以上、０．１５ｍｍ以上であってよい。この側面においてシート成形を経て得られる窒化ケイ素基板は、算術平均粗さＲａが０．０３μｍ以上０．５μｍ以下に研磨された表面にＸ線を照射した際に得られるβ型窒化ケイ素の（１０１）面の回折強度Ｉ（１０１）と（２１０）面の回折強度Ｉ（２１０）の比Ｉ（１０１）／Ｉ（２１０）が０．６２以上０．９５以下であることを特徴としてよい。 The silicon nitride substrate on this side surface is preferably applied to a silicon nitride substrate manufactured by using a separating material, and a silicon nitride substrate having a thickness of, for example, 0.5 mm or less. Further, the thickness may be 0.45 mm or less, 0.4 mm or less, and 0.35 mm or less. Further, the thickness may be 0.1 mm or more and 0.15 mm or more. The silicon nitride substrate obtained through sheet molding on this side surface is made of β-type silicon nitride (101) obtained by irradiating a surface polished to an arithmetic average roughness Ra of 0.03 μm or more and 0.5 μm or less with X-rays. ) The ratio I (101) / I (210) of the diffraction intensity I (101) of the surface to the diffraction intensity I (210) of the surface (210) may be 0.62 or more and 0.95 or less.

この側面における窒化ケイ素基板の製造方法及び窒化ケイ素基板の好ましい態様は、下記に記載する第二の側面の窒化ケイ素基板の製造方法及び窒化ケイ素基の各態様を含む。
この側面において、熱伝導率が室温において８０Ｗ／（ｍ・Ｋ）以上、さらには９０Ｗ／（ｍ・Ｋ）以上、かつ４点曲げ強度が室温において８００ＭＰa以上、さらには９００ＭＰa以上の窒化ケイ素基板を得ることが可能である。本発明の窒化ケイ素基板はシート成形で得られる薄いグリーンシートを焼結して得られるものであり、ＣＩＰ成形や金型プレス成形及び焼結して得られるバルクの焼結体とは本質的に異なる。The method for producing the silicon nitride substrate and the preferred embodiment of the silicon nitride substrate on this side surface include the method for producing the silicon nitride substrate on the second side surface and each aspect of the silicon nitride group described below.
In this aspect, a silicon nitride substrate having a thermal conductivity of 80 W / (m · K) or more at room temperature, further 90 W / (m · K) or more, and a four-point bending strength of 800 MPa or more at room temperature, and further 900 MPa or more is used. It is possible to obtain. The silicon nitride substrate of the present invention is obtained by sintering a thin green sheet obtained by sheet molding, and is essentially a bulk sintered body obtained by CIP molding, die press molding and sintering. different.

〔第二の側面：高強度、高熱伝導度の窒化ケイ素基板〕
本発明の第二の側面では、特定の比表面積、粒度、酸素量を有し、アルミニウム含有量が少ない窒化ケイ素（ＳＮ）粉を分離材として、塗布量などの製造条件を特定の範囲とすることにより、剥離性が良好で、高強度、高熱伝導であって、変形の少ない窒化ケイ素基板が得られることを見出した。また、この側面で得られる窒化ケイ素基板は柱状結晶粒子を特定の面積比で含むものであってよい。本発明の第二の側面は、本発明の第一の側面に対して好適な実施態様という側面を有するものであり、第一の側面で説明した事項は、さらに限定する点は別として、原則として、この側面でも適用できる。[Second aspect: Silicon nitride substrate with high strength and high thermal conductivity]
In the second aspect of the present invention, silicon nitride (SN) powder having a specific specific surface area, particle size, and oxygen content and a low aluminum content is used as a separating material, and production conditions such as a coating amount are set within a specific range. As a result, it has been found that a silicon nitride substrate having good peelability, high strength, high thermal conductivity, and little deformation can be obtained. Further, the silicon nitride substrate obtained on this side surface may contain columnar crystal particles in a specific area ratio. The second aspect of the present invention has an aspect of an embodiment suitable for the first aspect of the present invention, and the matters described in the first aspect are, apart from further limiting points, in principle. As, this aspect can also be applied.

この側面によれば、「窒化ケイ素粉末および焼結助剤を含む複数枚のグリーンシートをそれらの間に分離材を配置して積層し、
得られる積層体中の前記複数枚のグリーンシートを焼結し、
前記積層体から分離することによって複数枚の窒化ケイ素焼結体を得、
前記窒化ケイ素焼結体から窒化ケイ素基板を得る、窒化ケイ素基板の製造方法であって、
前記分離材は、窒化ケイ素粉を含み、ＢＥＴ法により測定される比表面積が１ｍ２／ｇ以上２０ｍ２／ｇ以下であり、レーザ回折散乱法により測定される体積基準の５０％粒子径をＤ５０とし、前記Ｄ５０が２０μｍ以下であり、かつ、酸素量が０．３重量％以上２重量％未満であり、
前記分離材は０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下の塗布量で前記グリーンシートの表面に塗布されていることを特徴とする窒化ケイ素基板の製造方法」が提供され、
さらに、「窒化ケイ素粒子と焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、前記窒化ケイ素粒子は、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子を前記基板表面における面積比で３５％以下とし、かつ前記基板表面の算術平均表面粗さが０．０３μｍ以上０．５μｍ以下であり、前記基板表面における窒化ホウ素と窒化ケイ素の比がホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１５×１０−５以下であることを特徴とする窒化ケイ素基板」が提供される。According to this aspect, "a plurality of green sheets containing silicon nitride powder and a sintering aid are laminated with a separating material placed between them.
The plurality of green sheets in the obtained laminate are sintered and
By separating from the laminate, a plurality of silicon nitride sintered bodies can be obtained.
A method for manufacturing a silicon nitride substrate, which obtains a silicon nitride substrate from the silicon nitride sintered body.
The separating material contains silicon nitride powder, has a specific surface area of 1 m 2 / g or more and 20 m 2 / g or less measured by the BET method, and has a 50% particle diameter based on the volume measured by the laser diffraction / scattering method of D50. The D50 is 20 μm or less, and the amount of oxygen is 0.3% by weight or more and less than 2% by weight.
A method for producing a silicon nitride substrate, characterized in that the separating material is applied to the surface of the green sheet at a coating amount of 0.1 mg / cm 2 or more and 3 mg / cm 2 or less ”is provided.
Further, "a silicon nitride substrate made of a silicon nitride sintered body containing silicon nitride particles and a sintering aid, wherein the silicon nitride particles have a minor axis a of 0.5 to 5 μm and a major axis with respect to the minor axis a. Columnar crystal particles having a ratio of b (b / a) of 2 or more have an area ratio of 35% or less on the substrate surface, and the arithmetic average surface roughness of the substrate surface is 0.03 μm or more and 0.5 μm or less. The ratio of boron nitride to silicon nitride on the surface of the substrate is 15 × 10-5 or less in terms of the ratio (B / Si) of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si). "Silicon nitride substrate" is provided.

本発明の第二の側面の窒化ケイ素基板の製造方法においては、まず、原料調整・混合工程として、窒化ケイ素粉末に焼結助剤となるセラミックス粉末を分散媒となる有機溶剤を使用し、ボールミル等で混合し、さらに、バインダー及び可塑剤と混合してスラリーを作製する。 In the method for producing a silicon nitride substrate on the second aspect of the present invention, first, as a raw material preparation / mixing step, a ball mill is used in which a ceramic powder as a sintering aid is used as a dispersion medium for the silicon nitride powder. Etc., and further mixed with a binder and a plasticizing agent to prepare a slurry.

第二の側面において、原料の窒化ケイ素粉末は、第一の側面におけると同様に、窒化ケイ素基板の製造に通常用いられる窒化ケイ素粉末のいずれも用いることができ、好ましくは、比表面積が１０．０ｍ２／ｇ以上、酸素含有量が１．０ｗｔ％以上、アルミニウム含有量が１００ｐｐｍ未満、より好ましくは、比表面積が１３．０ｍ２／ｇ以上、酸素含有量が１．２ｗｔ％以上２．３ｗｔ％以下、アルミニウム含有量が５０ｐｐｍ未満の窒化ケイ素粉末であってよい。窒化ケイ素粉末は、１つの態様において、比表面積が２５．０ｍ２／ｇ以下、酸素含有量が２．３ｗｔ％以下であってよい。In the second aspect, as the raw material silicon nitride powder, any of the silicon nitride powders usually used for producing a silicon nitride substrate can be used as in the first aspect, and the specific surface area is preferably 10. 0 m 2 / g or more, oxygen content 1.0 wt% or more, aluminum content less than 100 ppm, more preferably specific surface area 13.0 m 2 / g or more, oxygen content 1.2 wt% or more 2.3 wt It may be a silicon nitride powder having an aluminum content of less than 50 ppm. In one embodiment, the silicon nitride powder may have a specific surface area of 25.0 m 2 / g or less and an oxygen content of 2.3 wt% or less.

さらに、原料の窒化ケイ素粉末は、比表面積が５〜３０ｍ２／ｇであり、粒子表面から粒子表面直下３ｎｍまでに存在する酸素の含有割合をＦＳＯ（質量％）とし、粒子表面直下３ｎｍから内側に存在する酸素の含有割合をＦＩＯ（質量％）とし、比表面積をＦＳ（ｍ２／ｇ）とした場合に、ＦＳ／ＦＳＯが８〜２５であり、ＦＳ／ＦＩＯが２２以上である窒化ケイ素粉末であってよく、この窒化ケイ素粉末は特許文献４に開示された製法により製造できる。Further, the raw material silicon nitride powder has a specific surface area of 5 to 30 m 2 / g, and the content ratio of oxygen existing from the particle surface to 3 nm directly below the particle surface is FSO (mass%), and the content ratio is FSO (mass%), and the inside is from 3 nm directly below the particle surface. When the content ratio of oxygen present in is FIO (mass%) and the specific surface area is FS (m 2 / g), FS / FSO is 8 to 25 and FS / FIO is 22 or more. It may be a powder, and this silicon nitride powder can be produced by the production method disclosed in Patent Document 4.

高熱伝導率の窒化ケイ素基板を得るため焼結助剤としては、酸化マグネシウム（ＭｇＯ）および希土類元素の酸化物（ＲＥｘＯy）が好ましい。酸化マグネシウムは比較的低温で液相を形成するため、窒化ケイ素焼結体の焼結を促進することができ、且つ、窒化ケイ素粒子に固溶し難いため、窒化ケイ素基板の熱伝導率を高くすることができる。また希土類元素としてはＹ、Ｌａ、Ｃｅ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ等があげられるが、中でもＹの酸化物Ｙ２Ｏ３は窒化ケイ素基板の高密度化に有効であり、より好ましい。焼結助剤としてさらに例えば二酸化ケイ素を用いてもよい。Magnesium oxide (MgO) and an oxide of a rare earth element (RExOy) are preferable as the sintering aid in order to obtain a silicon nitride substrate having high thermal conductivity. Since magnesium oxide forms a liquid phase at a relatively low temperature, it is possible to promote the sintering of the silicon nitride sintered body, and it is difficult to dissolve in the silicon nitride particles, so that the thermal conductivity of the silicon nitride substrate is high. can do. Examples of rare earth elements include Y, La, Ce, Nd, Pm, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, etc. Among them, Y oxide Y 2 O 3 is silicon nitride. It is effective for increasing the density of the substrate, which is more preferable. Further, for example, silicon dioxide may be used as the sintering aid.

窒化ケイ素原料９８質量％から８１質量％に対して、酸化マグネシウムの添加量は０．５質量％から４．０質量％までの範囲であることが好ましく、希土類元素の酸化物の添加量は１．５質量％から１５質量％までの範囲であることが好ましい。より好ましくは、窒化ケイ素原料９７．５質量％から９１質量％に対して、酸化マグネシウムの添加量は、１．０質量％から３質量％、かつ希土類元素の酸化物の添加量は、１．５質量％から６質量％の範囲であってよい。二酸化ケイ素など追加の酸化物を添加する場合には、酸化マグネシウムと別途０．３質量％から１．５質量％の範囲で添加してもよい。 The amount of magnesium oxide added is preferably in the range of 0.5% by mass to 4.0% by mass with respect to 98% by mass to 81% by mass of the silicon nitride raw material, and the amount of oxide of a rare earth element added is 1. It is preferably in the range of .5% by mass to 15% by mass. More preferably, the amount of magnesium oxide added is 1.0% by mass to 3% by mass, and the amount of rare earth element oxide added is 1. It may be in the range of 5% by mass to 6% by mass. When an additional oxide such as silicon dioxide is added, it may be added in the range of 0.3% by mass to 1.5% by mass separately from magnesium oxide.

次に、成形工程として、上記混合して作製したスラリーを必要に応じて粘度調整し、これをドクターブレード法、押し出し成形法、もしくはそれに準じた方法により所定厚さのシート状に成形する。このときのシート成形体の板厚は、半導体パワーモジュールに応じて適宜決定できるが、０．２ｍｍから０．６ｍｍ程度までの範囲とすることが好ましい。のシート成形体の板厚は、任意の十箇所以上の測定値の平均値とする。 Next, as a molding step, the viscosity of the slurry produced by the above mixing is adjusted as necessary, and this is molded into a sheet having a predetermined thickness by a doctor blade method, an extrusion molding method, or a method similar thereto. The plate thickness of the sheet molded product at this time can be appropriately determined depending on the semiconductor power module, but is preferably in the range of about 0.2 mm to 0.6 mm. The plate thickness of the sheet molded product is the average value of the measured values at any ten or more points.

次に、グリーンシートを所望の形状に切断した後、切断されたグリーンシートの片面もしくは両面に分離材を塗布した後、分離材が塗布されたグリーンシートを複数枚、積層して焼結する。 Next, after cutting the green sheet into a desired shape, a separating material is applied to one or both sides of the cut green sheet, and then a plurality of green sheets coated with the separating material are laminated and sintered.

分離材は、窒化ケイ素（ＳＮ）粉を含み、ＢＥＴ法により測定される比表面積が１ｍ２／ｇ以上２０ｍ２／ｇ以下、レーザ回折散乱法により測定される体積基準の５０％粒子径Ｄ５０が２０μｍ以下、酸素量０．３質量％以上２質量％未満、アルミニウム含有量が５０ｐｐｍ未満であり、塗布量は０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下である。より好ましくは、Ｄ５０は１０μｍ以下、５μｍ以下、酸素量は０．３質量％以上１．２質量％以下、アルミニウム含有量は４０ｐｐｍ以下、塗布量は０．２ｍｇ／ｃｍ２以上１ｍｇ／ｃｍ２以下であってよい。分離材は、窒化ケイ素（ＳＮ）粉のみからなることが好ましく、以下では分離材ＳＮ粉について記載するが、ＳＮ粉を用いる効果が得られる限り、一部を窒化ホウ素（ＢＮ）粉にしてもよい。The separating material contains silicon nitride (SN) powder, has a specific surface area of 1 m 2 / g or more and 20 m 2 / g or less measured by the BET method, and has a 50% particle size D50 based on the volume measured by the laser diffraction scattering method. The oxygen content is 20 μm or less, the oxygen content is 0.3% by mass or more and less than 2% by mass, the aluminum content is less than 50 ppm, and the coating amount is 0.1 mg / cm 2 or more and 3 mg / cm 2 or less. More preferably, D50 is 10 μm or less, 5 μm or less, oxygen content is 0.3% by mass or more and 1.2% by mass or less, aluminum content is 40 ppm or less, and coating amount is 0.2 mg / cm 2 or more and 1 mg / cm 2 or less. May be. The separating material is preferably composed of only silicon nitride (SN) powder, and the separating material SN powder will be described below. However, as long as the effect of using the SN powder can be obtained, a part of the separating material may be boron nitride (BN) powder. good.

本発明のこの側面の分離材のＢＥＴ法により測定される比表面積は１ｍ２／ｇ以上２０ｍ２／ｇ以下である。比表面積が１ｍ２／ｇ以上では、分離材のグリーンシート表面への密着性がよくなって取扱い時に剥離し難くなる。比表面積が２０ｍ２／ｇ以下であると、分離材の前記酸素量を少なくでき、２質量％を超えないようにして、分離材が焼結時にグリーンシート中の焼結助剤と反応して、分離材を介して焼結体同士がくっついて剥離出来なくなることを回避できる。上記観点から、分離材の比表面積は１ｍ２／ｇ以上１２ｍ２／ｇ以下が好ましく、２ｍ２／ｇ以上７ｍ２／ｇ以下がより好ましい。The specific surface area of the separating material of this aspect of the present invention measured by the BET method is 1 m 2 / g or more and 20 m 2 / g or less. When the specific surface area is 1 m 2 / g or more, the adhesion of the separating material to the surface of the green sheet is improved and it becomes difficult to peel off during handling. When the specific surface area is 20 m 2 / g or less, the amount of oxygen in the separating material can be reduced so as not to exceed 2% by mass, and the separating material reacts with the sintering aid in the green sheet during sintering. , It is possible to prevent the sintered bodies from sticking to each other via the separating material and becoming unable to be peeled off. From the above viewpoint, the specific surface area of the separating material is preferably 1 m 2 / g or more and 12 m 2 / g or less, and more preferably 2 m 2 / g or more and 7 m 2 / g or less.

本発明のこの側面の分離材のＤ５０は２０μｍ以下である。Ｄ５０が２０μｍ以下であると、分離材のグリーンシートへの密着性がよいので取扱い時に剥離し難い。Ｄ５０は５μｍ以下、３μｍ以下、２μｍ以下であることがより好ましい。Ｄ５０は１μｍ以下であってよい。Ｄ５０の下限は限定されないが、Ｄ５０は０．３μｍ以上であってよい。 The D50 of the separating material on this side of the present invention is 20 μm or less. When D50 is 20 μm or less, the separating material has good adhesion to the green sheet and is difficult to peel off during handling. D50 is more preferably 5 μm or less, 3 μm or less, and 2 μm or less. D50 may be 1 μm or less. The lower limit of D50 is not limited, but D50 may be 0.3 μm or more.

本発明のこの側面の分離材の酸素量は０．３質量％以上２質量％未満である。分離材の酸素量がこの範囲であれば、焼結時に分離材粉が窒化ケイ素焼結体の焼結助剤成分と、適度に反応して、窒化ケイ素焼結体の表面に存在して、隣接する窒化ケイ素焼結体同士の接着を防ぎ、剥離性を良くするとともに、窒化ケイ素焼結体の変形を防止できる。酸素量が２質量％より少ないと、焼結時にグリーンシート中の焼結助剤と著しく反応して、分離材を介して焼結体同士がくっついて剥離出来なくなることを防止できる。この反応及び現象は、焼結助剤として酸化マグネシウムを用いた場合に、焼結助剤との反応が起こり易く、窒化ケイ素基板の厚さが０．２〜０．６ｍｍの場合に顕著になる。一方、酸素量が０．３質量％以上であると、焼結時に分離材と窒化ケイ素焼結体の反応が起こり易いので、焼結収縮に伴い分離材が基板表面を移動することがなく、グリーンシート表面に塗布された分離材の均一性が保たれ、分離材の存在割合の少ない場所が発生せず、隣接する窒化ケイ素焼結体が接着し剥離性が損なわれることが防止される。分離材の酸素量は上記観点から０．３〜１．２質量％がより好ましい。 The amount of oxygen in the separating material of this aspect of the present invention is 0.3% by mass or more and less than 2% by mass. If the amount of oxygen in the separating material is within this range, the separating material powder reacts appropriately with the sintering aid component of the silicon nitride sintered body during sintering and is present on the surface of the silicon nitride sintered body. It is possible to prevent adhesion between adjacent silicon nitride sintered bodies, improve peelability, and prevent deformation of the silicon nitride sintered body. When the amount of oxygen is less than 2% by mass, it is possible to prevent the sintered bodies from sticking to each other via the separating material and becoming unable to be peeled off due to a significant reaction with the sintering aid in the green sheet during sintering. This reaction and phenomenon are likely to occur when magnesium oxide is used as the sintering aid, and become remarkable when the thickness of the silicon nitride substrate is 0.2 to 0.6 mm. .. On the other hand, when the amount of oxygen is 0.3% by mass or more, the reaction between the separating material and the silicon nitride sintered body is likely to occur at the time of sintering, so that the separating material does not move on the substrate surface due to the sintering shrinkage. The uniformity of the separating material applied to the surface of the green sheet is maintained, a place where the abundance ratio of the separating material is small does not occur, and it is prevented that the adjacent silicon nitride sintered bodies adhere to each other and the peelability is impaired. The amount of oxygen in the separating material is more preferably 0.3 to 1.2% by mass from the above viewpoint.

本発明のこの側面の分離材のアルミニウム含有量は５０ｐｐｍ未満であることが好ましい。５０ｐｐｍ以上では、焼結後にβ型窒化ケイ素粒子内部に固溶するアルミニウムが増加する。固溶したアルミニウムイオンによるフォノン散乱は熱伝導率低下の原因となり、得られる窒化ケイ素基板の熱伝導率が９０Ｗ／（ｍ・Ｋ）未満、さらには８０Ｗ／（ｍ・Ｋ）未満に低下することがあるので好ましくない。アルミニウム含有量の好ましい範囲は４０ｐｐｍ以下である。 The aluminum content of the separator on this side of the invention is preferably less than 50 ppm. At 50 ppm or more, the amount of aluminum that dissolves inside the β-type silicon nitride particles after sintering increases. Phonon scattering by solid-melted aluminum ions causes a decrease in thermal conductivity, and the thermal conductivity of the obtained silicon nitride substrate is reduced to less than 90 W / (m · K) and further to less than 80 W / (m · K). It is not preferable because there is. The preferred range of aluminum content is 40 ppm or less.

本発明のこの側面の分離材のグリーンシート表面への塗布量は０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下である。分離材の塗布量が３ｍｇ／ｃｍ２以下の場合、多量の分離材が焼結過程で窒化ケイ素焼結体表面の窒化ケイ素粒子間に容易に入り込むことがなく、収縮を阻害しないので、窒化ケイ素焼結体の密度が向上し、強度も向上する。一方、分離材の塗布量が０．１ｍｇ／ｃｍ２以上であると、分離材が十分に存在するので、隣接する窒化ケイ素焼結体間の反応により、窒化ケイ素焼結体同士が付着して、剥離出来なくなることを防止できる。上記観点から、分離材の好ましい塗布量は０．２ｍｇ／ｃｍ２以上１ｍｇ／ｃｍ２以下である。The amount of the separating material on this side surface of the present invention applied to the surface of the green sheet is 0.1 mg / cm 2 or more and 3 mg / cm 2 or less. When the coating amount of the separating material is 3 mg / cm 2 or less, a large amount of the separating material does not easily enter between the silicon nitride particles on the surface of the silicon nitride sintered body during the sintering process and does not hinder shrinkage. The density of the sintered body is improved, and the strength is also improved. On the other hand, when the coating amount of the separating material is 0.1 mg / cm 2 or more, the separating material is sufficiently present, so that the silicon nitride sintered bodies adhere to each other due to the reaction between the adjacent silicon nitride sintered bodies. , It is possible to prevent the peeling from becoming impossible. From the above viewpoint, the preferable coating amount of the separating material is 0.2 mg / cm 2 or more and 1 mg / cm 2 or less.

分離材の塗布方法としては、グリーンシート表面へ均一に塗布するため、分離材を有機溶媒に分散させたスラリーを作製した後に、スプレー式の塗布機により霧状にして片面若しくは両面に塗布してもよいし、分離材を刷毛で直接片面若しくは両面に塗布してもよい。ここで、スラリーを作製する際には、分離材と有機溶媒とを窒化ケイ素製ボールを用いて混合することが好ましい。有機溶媒を用いてスラリーとする理由は、水を用いてスラリーを作製した場合、水存在下では分離材の酸素量が増加し、剥離性が悪化するためである。分離材と有機溶媒の割合は重量比で分離材／有機溶媒＝１／１０から１／２程度の範囲が適当である。また、窒化ケイ素製ボールを用いて混合するのは、分離材の凝集を壊砕し、均一分散させるためである。 As a method of applying the separating material, in order to apply it uniformly to the surface of the green sheet, after preparing a slurry in which the separating material is dispersed in an organic solvent, it is atomized by a spray-type coating machine and applied to one or both sides. Alternatively, the separating material may be applied directly to one side or both sides with a brush. Here, when producing the slurry, it is preferable to mix the separating material and the organic solvent using silicon nitride balls. The reason why the slurry is prepared by using an organic solvent is that when the slurry is prepared by using water, the amount of oxygen in the separating material increases in the presence of water and the peelability deteriorates. The ratio of the separating material to the organic solvent is appropriately in the range of about 1/10 to 1/2 of the separating material / organic solvent in terms of weight ratio. Further, the reason for mixing using the silicon nitride balls is to crush the agglomeration of the separating material and uniformly disperse it.

分離材を有機溶媒に分散させたスラリーが塗布、乾燥されたグリーンシートは数枚〜数十枚重ねて、積層された後、グリーンシート中のバインダー等の有機成分を除去するために脱脂を行う。脱脂は９００℃以下の大気中、もしくは窒素、アルゴン等の不活性雰囲気中で行うことが好ましい。積層するグリーンシートの枚数は５〜５０枚が好ましい。 A slurry in which the separating material is dispersed in an organic solvent is applied, and several to several tens of dried green sheets are stacked and laminated, and then degreasing is performed to remove organic components such as binders in the green sheet. .. The degreasing is preferably performed in the air at 900 ° C. or lower, or in an inert atmosphere such as nitrogen or argon. The number of green sheets to be laminated is preferably 5 to 50.

分離材を介在したグリーンシートの積層体は、脱脂及び焼結される。グリーンシートの積層体は、耐熱性セッタ上に設置され、側面を耐熱性スペーサで囲んでから、頂面を耐熱性セッタで押圧した状態で、（脱脂及び）焼結されてよいが、セッタ及びスペーサ（本明細書において囲繞体ともいう。）は従来の窒化ホウ素（ＢＮ）製のほか、本発明によれば、好ましく窒化ケイ素（ＳＮ）製のものにすることができる。囲繞体は窒化ホウ素（ＢＮ）製であっても、分離材として窒化ケイ素（ＳＮ）粉を用いると、焼結後の窒化ケイ素基板表面に窒化ホウ素（ＢＮ）粉が残留しないので、得られる窒化ケイ素基板は銅を接合した際の耐熱性に優れることができる。さらに、囲繞体を窒化ケイ素（ＳＮ）製にすれば、蒸気拡散に基づくＢＮの混入も完全に防止することができる。窒化ケイ素製囲繞体は高い温度で焼成したものを用いてよい。また、グリーンシートの積層体の周りに窒化ケイ素（ＳＮ）粉を詰めて焼結することによっても、ＢＮの混入を防止することができる。 The laminate of green sheets with the separating material interposed is degreased and sintered. The laminated body of the green sheet may be installed on a heat-resistant setter, the side surface may be surrounded by a heat-resistant spacer, and then the top surface may be pressed by the heat-resistant setter and sintered (defatted and). The spacer (also referred to as an enclosure in the present specification) can be preferably made of silicon nitride (SN) in addition to the conventional boron nitride (BN) according to the present invention. Even if the enclosure is made of boron nitride (BN), if silicon nitride (SN) powder is used as the separating material, the boron nitride (BN) powder does not remain on the surface of the silicon nitride substrate after sintering, so that the obtained nitridation can be obtained. The silicon substrate can be excellent in heat resistance when copper is bonded. Further, if the surrounding body is made of silicon nitride (SN), it is possible to completely prevent the mixing of BN due to vapor diffusion. As the silicon nitride enclosure, one fired at a high temperature may be used. Further, by packing silicon nitride (SN) powder around the laminated body of the green sheet and sintering it, it is possible to prevent BN from being mixed.

脱脂後のグリーンシートは１０Ｐａ以下の真空にして残留ガスを除去した後、窒素で置換した雰囲気中で焼結することが好ましい。窒素雰囲気中で圧力０．１５ＭＰａ以上３ＭＰａ以下、焼結温度１７５０℃以上１９１０℃以下、より好ましくは１７９０℃以上１８８０℃以下で６時間以上２２時間以下保持して焼結することが好ましい。 After degreasing, the green sheet is preferably vacuumed at 10 Pa or less to remove residual gas, and then sintered in an atmosphere replaced with nitrogen. It is preferable to hold the sinter at a pressure of 0.15 MPa or more and 3 MPa or less, a sintering temperature of 1750 ° C. or more and 1910 ° C. or less, more preferably 1790 ° C. or more and 1880 ° C. or less for 6 hours or more and 22 hours or less in a nitrogen atmosphere.

窒素ガス圧力０．１５ＭＰａ以上であると、焼結時の最高保持温度を１７５０℃以上、さらには１７９０℃以上にあげることは出来る。最高保持温度が１７５０℃以上、さらには１７９０℃以上であると、焼結の進行速度が速く、緻密な窒化ケイ素基板を得ることができる。あるいは、最高保持温度１７５０℃以上、さらには１７９０℃以上で、緻密な窒化ケイ素基板を得ると、柱状のβ型窒化ケイ素粒子の成長が十分であり、高い熱伝導率の窒化ケイ素基板が得られるので、熱伝導率を８０Ｗ／（ｍ・Ｋ）以上、さらには９０Ｗ／（ｍ・Ｋ）以上にすることができる。最高保持温度が１９１０℃以下、さらには１８８０℃以下であると、柱状のβ型窒化ケイ素粒子の成長が適当な速度であり、窒化ケイ素基板表面の凹凸が大きくならず、隣接する窒化ケイ素焼結体間の反応により、窒化ケイ素焼結体同士が付着してしまい、剥離出来なくなることが防止される。 When the nitrogen gas pressure is 0.15 MPa or more, the maximum holding temperature at the time of sintering can be raised to 1750 ° C. or higher, and further to 1790 ° C. or higher. When the maximum holding temperature is 1750 ° C. or higher, further 1790 ° C. or higher, the sintering progress rate is high, and a dense silicon nitride substrate can be obtained. Alternatively, when a dense silicon nitride substrate is obtained at a maximum holding temperature of 1750 ° C. or higher, further 1790 ° C. or higher, columnar β-type silicon nitride particles grow sufficiently, and a silicon nitride substrate having high thermal conductivity can be obtained. Therefore, the thermal conductivity can be 80 W / (m · K) or more, and further 90 W / (m · K) or more. When the maximum holding temperature is 1910 ° C. or lower, and further 1880 ° C. or lower, the growth of the columnar β-type silicon nitride particles is at an appropriate rate, the unevenness on the surface of the silicon nitride substrate does not increase, and the adjacent silicon nitride sintered. It is prevented that the silicon nitride sintered bodies adhere to each other due to the reaction between the bodies and cannot be peeled off.

窒化ケイ素焼結体は、基板表面状態は優れており、特に基板表面にＢＮ粉が残留せず、ＢＮ含有量もなしか極めて少ないので、そのまま窒化ケイ素基板として用いてもよいが、ブラスト加工等による表面処理を施すことが好ましい。ブラスト加工は例えば、１０〜１００μｍのＳｉＣ砥粒を窒化ケイ素基板表面に噴射することによって、表面に突出した窒化ケイ素粒子を削り、表面粗さを低減して、金属板との接合性を良好にするために実施する。ブラスト加工、さらにはラップ処理によって除去される窒化ケイ素基板の表面の深さ（厚さ）は、例えば、３０μｍ以下であってよいが、好ましくは２０μｍ以下、さらには１０μｍ以下、特には５μｍ以下であってよい。本発明の第二の側面では、最低限のブラスト加工によって、分離材の除去、優れた表面特性を実現することができる。 The silicon nitride sintered body has an excellent substrate surface condition, and in particular, BN powder does not remain on the substrate surface and the BN content is extremely low. Therefore, the silicon nitride sintered body may be used as it is as a silicon nitride substrate, but it may be blasted or the like. It is preferable to perform the surface treatment according to. In the blasting process, for example, by injecting 10 to 100 μm SiC abrasive particles onto the surface of the silicon nitride substrate, the silicon nitride particles protruding from the surface are scraped off, the surface roughness is reduced, and the bondability with the metal plate is improved. To carry out. The surface depth (thickness) of the silicon nitride substrate removed by blasting or wrapping may be, for example, 30 μm or less, but preferably 20 μm or less, further 10 μm or less, and particularly 5 μm or less. It may be there. In the second aspect of the present invention, it is possible to remove the separating material and realize excellent surface properties with a minimum of blasting.

上記した窒化ケイ素基板の製造方法を採用することにより、複数枚の窒化ケイ素焼結体を容易に剥離でき、窒化ケイ素焼結体を構成する柱状窒化ケイ素粒子が適度な大きさであって、焼結体表面の凹凸も適正なレベルに制御されているため、高強度、高熱伝導を有し、かつ変形の少ない窒化ケイ素基板を得ることができる。また、基板表面にＢＮ粉が存在しないため、銅板を接合した際の耐ヒートサイクル性が改善され、長期にわたって安定して使用できる。具体的には、窒化ケイ素粒子と、少なくとも酸化マグネシウムからなる焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、前記窒化ケイ素粒子は、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子を面積比で３５％以下、さらには３０％以下、２５％以下とし、かつ前記基板表面の算術平均表面粗さが０．０３μｍ以上０．５μｍ以下の窒化ケイ素基板が得られる。 By adopting the above-mentioned method for manufacturing a silicon nitride substrate, a plurality of silicon nitride sintered bodies can be easily peeled off, and the columnar silicon nitride particles constituting the silicon nitride sintered body have an appropriate size and are baked. Since the unevenness of the surface of the body is also controlled to an appropriate level, it is possible to obtain a silicon nitride substrate having high strength, high thermal conductivity, and little deformation. Further, since BN powder is not present on the surface of the substrate, the heat cycle resistance when the copper plates are joined is improved, and the copper plates can be used stably for a long period of time. Specifically, it is a silicon nitride substrate made of silicon nitride particles and a silicon nitride sintered body containing a sintering aid composed of at least magnesium oxide, and the silicon nitride particles have a minor axis a of 0.5 to 0.5 to. Columnar crystal particles having an area ratio of 5 μm and a major axis b ratio (b / a) of 2 or more to a minor axis a are 35% or less, further 30% or less, 25% or less in terms of area ratio, and the arithmetic average surface of the substrate surface. A silicon nitride substrate having a roughness of 0.03 μm or more and 0.5 μm or less can be obtained.

また、この側面によれば、分離材として従来のＢＮ粉に代えてＳＮ粉を用いることで、基板表面にＢＮ粉が残留していない窒化ケイ素基板を得ることができる。この側面において、基板表面のＢＮは蛍光Ｘ線分析によって分析できるが、窒化ケイ素基板は、ホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１５×１０−５以下で、１２×１０−５以下、１０×１０−５以下、８×１０−５以下あってよく、さらには６．５×１０−５未満、５×１０−５以下であることができる。特に、焼結の際にグリーンシート積層体を窒化ケイ素製の囲繞体（セッタ）内に設置したり、グリーンシート積層体の周りを窒化ケイ素粉で覆って焼結することで、基板表面及び本体にＢＮを含まない窒化ケイ素基板を得ることができる。この側面の窒化ケイ素基板は、ＢＮ含有量を任意に少なくすることができ、蛍光Ｘ線分析によってホウ素（Ｂ）が検出限界以下とし、またＢＮを含まないものにすることができる。Further, according to this aspect, by using SN powder instead of the conventional BN powder as the separating material, it is possible to obtain a silicon nitride substrate in which BN powder does not remain on the surface of the substrate. In this aspect, the BN on the surface of the substrate can be analyzed by fluorescent X-ray analysis, but the silicon nitride substrate is obtained by the ratio (B / Si) of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si). It may be 15 × 10-5 or less, 12 × 10-5 or less, 10 × 10-5 or less, 8 × 10-5 or less, and further less than 6.5 × 10-5 and 5 × 10-5 or less. There can be. In particular, at the time of sintering, the green sheet laminate is installed in a silicon nitride enclosure (setter), or the green sheet laminate is covered with silicon nitride powder and sintered to form the substrate surface and the main body. A silicon nitride substrate containing no BN can be obtained. The silicon nitride substrate on this side can have an arbitrarily low BN content, and boron (B) can be below the detection limit by fluorescent X-ray analysis and can be free of BN.

また、この側面によれば、熱伝導率が室温において８０Ｗ／（ｍ・Ｋ）以上、かつ４点曲げ強度が室温において８００ＭＰa以上の窒化ケイ素基板を得ることが可能である。熱伝導率は、室温において８５Ｗ／（ｍ・Ｋ）以上、９０Ｗ／（ｍ・Ｋ）以上、９５Ｗ／（ｍ・Ｋ）以上、９７Ｗ／（ｍ・Ｋ）以上、１００Ｗ／（ｍ・Ｋ）以上、であってよく、４点曲げ強度は、室温において８４０ＭＰa以上、９００ＭＰa以上、９３０ＭＰa以上、９６０ＭＰa以上、１０００ＭＰa以上であってよい。本発明の窒化ケイ素基板はシート成形で得られる薄いグリーンシートを焼結して得られるものであり、ＣＩＰ成形や金型プレス成形及び焼結して得られるバルクの焼結体とは本質的に異なる。 Further, according to this aspect, it is possible to obtain a silicon nitride substrate having a thermal conductivity of 80 W / (m · K) or more at room temperature and a four-point bending strength of 800 MPa or more at room temperature. Thermal conductivity is 85 W / (m · K) or more, 90 W / (m · K) or more, 95 W / (m · K) or more, 97 W / (m · K) or more, 100 W / (m · K) at room temperature. The four-point bending strength may be 840 MPa or more, 900 MPa or more, 930 MPa or more, 960 MPa or more, and 1000 MPa or more at room temperature. The silicon nitride substrate of the present invention is obtained by sintering a thin green sheet obtained by sheet molding, and is essentially a bulk sintered body obtained by CIP molding, die press molding and sintering. different.

この側面における窒化ケイ素基板は、分離材を用いて製造される厚さが０．５ｍｍ以下の窒化ケイ素基板に好適に適用される。さらには、厚さは０．４５ｍｍ以下、０．４ｍｍ以下、０．３５ｍｍ以下であってよい。また厚さが０．１ｍｍ以上、０．１５ｍｍ以上であってよい。この側面においてシート成形を経て得られる窒化ケイ素基板は、算術平均粗さＲａが０．０３μｍ以上０．５μｍ以下に研磨された表面にＸ線を照射した際に得られるβ型窒化ケイ素の（１０１）面の回折強度Ｉ（１０１）と（２１０）面の回折強度Ｉ（２１０）の比Ｉ（１０１）／Ｉ（２１０）が０．６２以上０．９５以下であることを特徴とする。 The silicon nitride substrate on this side surface is preferably applied to a silicon nitride substrate having a thickness of 0.5 mm or less manufactured by using a separating material. Further, the thickness may be 0.45 mm or less, 0.4 mm or less, and 0.35 mm or less. Further, the thickness may be 0.1 mm or more and 0.15 mm or more. The silicon nitride substrate obtained through sheet molding on this side surface is made of β-type silicon nitride (101) obtained by irradiating a surface polished to an arithmetic average roughness Ra of 0.03 μm or more and 0.5 μm or less with X-rays. The ratio I (101) / I (210) of the diffraction intensity I (101) on the surface () and the diffraction intensity I (210) on the surface (210) is 0.62 or more and 0.95 or less.

少なくとも酸化マグネシウムからなる焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、前記窒化ケイ素粒子は、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子を面積比で３５％以下、さらには３０％以下、特に２５％以下としたのは、柱状結晶粒子を面積比を小さくすると、焼成時に基板表面に柱状結晶粒子によって形成される凹部にＤ５０が２０μｍ以下の分離材が偏析して、分離材の無い箇所が出来ることを防止でき、分離材の無い箇所で隣接する基板同士が反応して剥離出来なくなったり、強制的に引き剥がして窒化ケイ素焼結体表面に欠陥が残存することご防止するができるので、曲げ強度を向上させることができるからである。 A silicon nitride substrate made of a silicon nitride sintered body containing a sintering aid made of at least magnesium oxide, wherein the silicon nitride particles have a minor axis a of 0.5 to 5 μm and a major axis b with respect to the minor axis a. Columnar crystal particles with a ratio (b / a) of 2 or more were set to 35% or less in area ratio, and further to 30% or less, especially 25% or less. It is possible to prevent the separating material having a D50 of 20 μm or less from segregating into the recess formed by the columnar crystal particles to form a part without the separating material, and the adjacent substrates can react and peel off at the part without the separating material. This is because it is possible to prevent defects from remaining on the surface of the silicon nitride sintered body by being forcibly peeled off or disappearing, so that the bending strength can be improved.

図３に、窒化ケイ素焼結体表面の微細構造の模式図を示す。図３において、柱状結晶粒子である窒化ケイ素粒子８が存在する領域において、窒化ケイ素粒子８の柱状結晶粒子間に窒化ケイ素（ＳＮ）粉からなる分離材９が埋没する形で存在する様子が示されている。 FIG. 3 shows a schematic view of the microstructure of the surface of the silicon nitride sintered body. FIG. 3 shows how a separating material 9 made of silicon nitride (SN) powder is embedded between the columnar crystal particles of the silicon nitride particles 8 in the region where the silicon nitride particles 8 which are columnar crystal particles are present. Has been done.

窒化ケイ素基板表面の算術平均表面粗さが０．０３μｍ以上０．５μｍ以下としたのは、０．０３μｍ以上では、加工時の残留応力等による窒化ケイ素基板の曲げ強度の低下を防止できるからである。０．５μｍ以下であると、回路形成用の金属板との接合が容易となるからである。基板表面の算術平均表面粗さは、０．４μｍ以下、０．３μｍ以下であってよい。 The arithmetic average surface roughness of the silicon nitride substrate surface is set to 0.03 μm or more and 0.5 μm or less because when it is 0.03 μm or more, it is possible to prevent a decrease in bending strength of the silicon nitride substrate due to residual stress during processing. be. This is because if the thickness is 0.5 μm or less, joining with a metal plate for forming a circuit becomes easy. The arithmetic mean surface roughness of the substrate surface may be 0.4 μm or less and 0.3 μm or less.

以下に実施例を挙げて、本発明を詳しく説明するが、本発明は、それらの実施例により限定されるものではない。本発明の分離材および原料として使用したＳＮ粉の物性測定と本発明の窒化ケイ素基板の評価方法は以下の方法により行った。 Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to those examples. The physical properties of the SN powder used as the separating material and the raw material of the present invention and the evaluation method of the silicon nitride substrate of the present invention were carried out by the following methods.

（ＳＮ粉の比表面積の測定方法）
ＳＮ粉の比表面積は、Ｍｏｕｎｔｅｃｈ社製Ｍａｃｓｏｒｂを用いて、窒素ガス吸着によるＢＥＴ１点法にて測定して求めた。(Measuring method of specific surface area of SN powder)
The specific surface area of the SN powder was determined by measuring with a BET 1-point method by adsorbing nitrogen gas using a Macsorb manufactured by Mountech.

（ＳＮ粉のＤ５０の測定方法）
分離材ＳＮ粉の粒度分布は、レーザ回折散乱法により以下のようにして測定した。前記粉末を、ヘキサメタリン酸ソーダ０．２質量％水溶液中に投入して、直径２６ｍｍのステンレス製センターコーンを取り付けた超音波ホモジナイザーを用いて３００Ｗの出力で６分間分散処理して希薄溶液を調製し、測定試料とした。レーザ回折／散乱式粒子径分布測定装置（日機装株式会社製マイクロトラックＭＴ３０００）を用いて測定試料の粒度分布を測定し、体積基準の粒度分布曲線とそのデータを得た。得られた粒度分布曲線とそのデータより、Ｄ５０を算出した。(Measuring method of D50 of SN powder)
The particle size distribution of the separating material SN powder was measured by the laser diffraction / scattering method as follows. The powder was put into a 0.2 mass% aqueous solution of sodium hexametaphosphate and dispersed for 6 minutes at an output of 300 W using an ultrasonic homogenizer equipped with a stainless steel center cone having a diameter of 26 mm to prepare a dilute solution. , As a measurement sample. The particle size distribution of the measurement sample was measured using a laser diffraction / scattering type particle size distribution measuring device (Microtrac MT3000 manufactured by Nikkiso Co., Ltd.), and a volume-based particle size distribution curve and its data were obtained. D50 was calculated from the obtained particle size distribution curve and its data.

（ＳＮ粉の酸素量の測定方法）
ＳＮ粉の全酸素含有量ＦＴＯと表面酸素含有量ＦＳＯは、以下の方法により測定した。まず、窒化ケイ素粉末を秤量し、窒化ケイ素粉末の表面酸素と内部酸素の合計である全酸素含有量ＦＴＯをＪＩＳ Ｒ１６０３−１０酸素の定量方法に準拠した不活性ガス融解−二酸化炭素赤外線吸収法（ＬＥＣＯ社製、ＴＣ−１３６型）で測定した。次に、秤量した窒化ケイ素粉末を、窒化ケイ素粉末１質量部に対しフッ化水素が５質量部となるように、窒化ケイ素粉末とフッ酸水溶液とを混合し、室温で３時間攪拌した。これを吸引濾過し、得られた固形物を１２０℃で１時間真空乾燥した後、このフッ酸処理粉末の重量と酸素含有量を測定した。この値を補正前ＦＩＯ（フッ酸処理粉末に対する質量％）とした。内部酸素量ＦＩＯ（窒化ケイ素粉末に対する質量％）は下記の式（１）から算出し、表面酸素量ＦＳＯ（窒化ケイ素粉末に対する質量％）を下記の式（２）から算出した。このようにして求めた表面酸素量が、粒子表面から粒子表面直下３ｎｍの範囲に存在する酸素に起因することは、前記のフッ酸処理前後における窒化ケイ素粉末のＸ線光電子スペクトルのデプス・プロファイル及び処理前後の粉末重量変化より確認した。
ＦＩＯ（質量％）＝（（フッ酸処理粉末の重量）（ｇ））／（窒化ケイ素粉末重量（ｇ））×補正前ＦＩＯ（質量％）・・・・（１）
ＦＳＯ（質量％）＝ＦＴＯ（質量％）−ＦＩＯ（質量％）・・・・（２）(Measuring method of oxygen content of SN powder)
The total oxygen content FTO and the surface oxygen content FSO of the SN powder were measured by the following methods. First, the silicon nitride powder is weighed, and the total oxygen content FTO, which is the sum of the surface oxygen and the internal oxygen of the silicon nitride powder, is determined by the inert gas melting-carbon dioxide infrared absorption method based on the method for quantifying JIS R1603-10 oxygen. It was measured with a TC-136 type manufactured by LECO. Next, the weighed silicon nitride powder was mixed with the silicon nitride powder and the hydrofluoric acid aqueous solution so that hydrogen fluoride was 5 parts by mass with respect to 1 part by mass of the silicon nitride powder, and the mixture was stirred at room temperature for 3 hours. This was suction-filtered, and the obtained solid was vacuum-dried at 120 ° C. for 1 hour, and then the weight and oxygen content of the hydrofluoric acid-treated powder were measured. This value was defined as FIO (% by mass with respect to hydrofluoric acid-treated powder) before correction. The internal oxygen amount FIO (mass% with respect to the silicon nitride powder) was calculated from the following formula (1), and the surface oxygen amount FSO (mass% with respect to the silicon nitride powder) was calculated from the following formula (2). The fact that the amount of surface oxygen thus determined is due to the oxygen existing in the range of 3 nm below the particle surface from the particle surface is due to the depth profile of the X-ray photoelectron spectrum of the silicon nitride powder before and after the hydrofluoric acid treatment and the depth profile of the X-ray photoelectron spectrum. It was confirmed from the change in powder weight before and after the treatment.
FIO (mass%) = ((hydrofluoric acid-treated powder) (g)) / (silicon nitride powder weight (g)) × FIO before correction (mass%) ... (1)
FSO (mass%) = FTO (mass%) -FIO (mass%) ... (2)

（ＳＮ粉末のＡｌの含有量の測定方法）
分離材ＳＮ粉のＡｌの含有量は、以下のようにして測定した。フッ酸と硝酸とを混合した液を収容した容器に、上記粉末を投入し密栓して、同容器にマイクロ波を照射して加熱し、窒化ケイ素を完全に分解し、得られた分解液を超純水で定容して検液とした。エスアイアイ・ナノテクノロジー社製ＩＣＰ−ＡＥＳ（ＳＰＳ５１００型）を用いて、検出された波長とその発光強度から検液中のＡｌの金属不純物を定量し、Ａｌの含有量を算出した。(Method of measuring Al content of SN powder)
The Al content of the separating material SN powder was measured as follows. The above powder is put into a container containing a liquid containing a mixture of hydrofluoric acid and nitric acid, sealed tightly, and the container is heated by irradiating with microwaves to completely decompose silicon nitride, and the obtained decomposition liquid is used. The volume was adjusted with ultrapure water to prepare a test solution. Using ICP-AES (SPS5100 type) manufactured by SII Nanotechnology, the metal impurities of Al in the test solution were quantified from the detected wavelength and its emission intensity, and the Al content was calculated.

（窒化ケイ素基板の剥離性の評価方法）
窒化ケイ素基板の剥離性の評価は、窒化ケイ素基板に割れやクラックが発生することなく容易に剥離できた場合を（○）、木製ハンマーで衝撃を加えて剥離する際に窒化ケイ素基板に割れやクラックが発生する基板が一枚でもあった場合を（△）と判定した。(Evaluation method of peelability of silicon nitride substrate)
The peelability of the silicon nitride substrate is evaluated when the silicon nitride substrate can be easily peeled off without cracking or cracking (○), and when the silicon nitride substrate is peeled off by applying an impact with a wooden hammer, the silicon nitride substrate cracks or cracks. When there was even one substrate on which cracks occurred, it was determined to be (Δ).

（短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子の面積比の測定方法）
短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子の面積比は、以下の方法で、短径ａ及び長径ｂを測定することにより算出した。窒化ケイ素基板の任意の断面を研磨した後、エッチングして焼結助剤成分を溶出させた後に走査型電子顕微鏡（ＳＥＭ）を用いて、観察倍率５０００倍にてＳＥＭ写真を撮影し、画像解析装置により短径ａ及び長径ｂを測定する。これらの測定結果から、短径ａが０．５〜５μｍの窒化ケイ素粒子を選択し、かつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上である柱状結晶粒子の合計面積を求める。この柱状結晶粒子の合計面積が測定面積に占める面積率（面積比）を算出した。(Method for measuring the area ratio of columnar crystal particles having a minor axis a of 0.5 to 5 μm and a ratio (b / a) of the major axis b to the minor axis a of 2 or more)
For the area ratio of columnar crystal particles having a minor axis a of 0.5 to 5 μm and a ratio of the major axis b to the minor axis a (b / a) of 2 or more, the minor axis a and the major axis b are measured by the following method. It was calculated by. After polishing an arbitrary cross section of the silicon nitride substrate, etching is performed to elute the sintering aid component, and then a scanning electron microscope (SEM) is used to take an SEM photograph at an observation magnification of 5000 times for image analysis. The minor axis a and the major axis b are measured by the device. From these measurement results, select silicon nitride particles having a minor axis a of 0.5 to 5 μm, and determine the total area of columnar crystal particles having a ratio (b / a) of major axis b to minor axis a of 2 or more. .. The area ratio (area ratio) of the total area of the columnar crystal particles to the measured area was calculated.

（窒化ケイ素基板表面の算術平均表面粗さの測定方法）
窒化ケイ素基板表面の算術平均表面粗さは、以下のようにして測定した。得られた窒化ケイ素基板表面の算術平均粗さＲａはＪＩＳ Ｂ ０６０１−２００１（ＩＳＯ４２８７−１９９７）に準拠して測定した。触針式の表面粗さ計を用い、焼結後のブラスト加工等による表面処理を施した窒化ケイ素質焼結体の表面に、触針先端半径が２μｍの触針を当て、測定長さを５ｍｍ、触針の走査速度を０．５ｍｍ／秒に設定して表面粗さを測定し、この測定で得られた５箇所の平均値を算術平均粗さＲａの値とした。(Measurement method of arithmetic mean surface roughness of silicon nitride substrate surface)
The arithmetic mean surface roughness of the surface of the silicon nitride substrate was measured as follows. The arithmetic mean roughness Ra of the surface of the obtained silicon nitride substrate was measured according to JIS B 0601-2001 (ISO4287-197). Using a stylus type surface roughness meter, apply a stylus with a stylus tip radius of 2 μm to the surface of the silicon nitride sintered body that has been surface-treated by blasting after sintering to measure the measurement length. The surface roughness was measured by setting the scanning speed of the stylus to 5 mm and 0.5 mm / sec, and the average value of the five points obtained by this measurement was taken as the value of the arithmetic mean roughness Ra.

（窒化ケイ素基板の曲げ強度の測定方法）
窒化ケイ素基板の曲げ強度は、以下のようにして測定した。得られた窒化ケイ素基板の曲げ強度測定には、幅４．０ｍｍ×厚さ０．３５ｍｍ×長さ４０ｍｍの曲げ試験片を使用した。インストロン社製万能材料試験機を用いて、試験片の厚み（０．３５ｍｍｔ）が異なる以外は、ＪＩＳ Ｒ１６０１に準拠した方法で、内スパン１０ｍｍ、外スパン３０ｍｍの４点曲げ試験冶具により、室温の４点曲げ強度を測定した。(Measuring method of bending strength of silicon nitride substrate)
The bending strength of the silicon nitride substrate was measured as follows. A bending test piece having a width of 4.0 mm, a thickness of 0.35 mm, and a length of 40 mm was used for measuring the bending strength of the obtained silicon nitride substrate. Room temperature using a 4-point bending test jig with an inner span of 10 mm and an outer span of 30 mm by a method compliant with JIS R1601 except that the thickness (0.35 mmt) of the test piece is different using an Instron universal material tester. The 4-point bending strength was measured.

（窒化ケイ素基板の熱伝導率の測定方法）
窒化ケイ素基板の熱伝導率測定では、窒化ケイ素基板の直径１０ｍｍφ×厚さ１ｍｍｔの円盤形状試験片を作製し、この円盤状試験片を用いて、ＪＩＳ Ｒ１６１１に準拠したフラッシュ法により熱伝導率を室温で測定した。(Measurement method of thermal conductivity of silicon nitride substrate)
In the measurement of thermal conductivity of a silicon nitride substrate, a disk-shaped test piece having a diameter of 10 mmφ and a thickness of 1 mmt is prepared, and the disk-shaped test piece is used to measure the thermal conductivity by a flash method conforming to JIS R1611. Measured at room temperature.

（窒化ケイ素基板の表面のＢ／Ｓｉ蛍光Ｘ線強度比の測定方法）
窒化ケイ素基板の表面のＢ／Ｓｉ蛍光Ｘ線強度比は、ＸＲＦ（蛍光Ｘ線分析：Ｘ−ｒａｙ Ｆｌｕｏｒｅｓｃｅｎｃｅ Ａｎａｌｙｓｉｓ）を用いて、窒化珪素基板表面における特にホウ素（Ｂ）とシリコン（Ｓｉ）の組成分析を行い、ＸＲＦの測定結果からＢ／Ｓｉ蛍光Ｘ線強度比を求めた。ここで、蛍光Ｘ線としては、ＢのＫα線（エネルギー０．１８３ｋｅＶ）、ＳｉのＫα線（エネルギー １．７４ｋｅＶ）が対象となり、これらの強度比がＢ／Ｓｉ蛍光Ｘ線強度比である。なお、実施例の表において「Ｂ／Ｓｉ」欄の「不検出」とは、蛍光Ｘ線分析においてＢ元素が検出されなかったことを表す。(Measurement method of B / Si fluorescent X-ray intensity ratio on the surface of silicon nitride substrate)
The B / Si X-ray fluorescence intensity ratio on the surface of the silicon nitride substrate is determined by using XRF (X-ray Fluorescence Analysis), in particular, the composition of boron (B) and silicon (Si) on the surface of the silicon nitride substrate. The analysis was performed, and the B / Si fluorescent X-ray intensity ratio was obtained from the measurement result of XRF. Here, as the fluorescent X-rays, B Kα rays (energy 0.183 keV) and Si Kα rays (energy 1.74 keV) are targeted, and these intensity ratios are B / Si fluorescent X-ray intensity ratios. In the table of Examples, "not detected" in the "B / Si" column means that element B was not detected in the fluorescent X-ray analysis.

（実施例１）
焼結助剤として酸化マグネシウム（ＭｇＯ）粉末（比表面積３ｍ２／ｇ、高純度化学研究所製）、酸化イットリウム（Ｙ２Ｏ３）粉末（比表面積３ｍ２／ｇ、信越化学工業製）を用意した。(Example 1)
Magnesium oxide (MgO) powder (specific surface area 3 m 2 / g, manufactured by High Purity Chemical Laboratory) and yttrium oxide (Y 2 O 3 ) powder (specific surface area 3 m 2 / g, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) are used as sintering aids. I prepared it.

特許文献４に開示された方法により製造した比表面積１８．５ｍ２／ｇ、酸素含有量１．７７重量％の原料ＳＮ粉９４．５質量部に、焼結助剤として前記の酸化イットリウム３．５質量部および前記の酸化マグネシウム２質量部を配合し、アミン系の分散剤を粉末に対して２質量部溶解したトルエン−イソプロパノール−キシレン溶媒および粉砕媒体である窒化ケイ素製ボールと共にボールミル用樹脂製ポットに投入して、２４時間湿式混合した。得られたスラリーを目開き４４μｍの篩に通した後、前記樹脂製ポット中の混合粉末１００質量部に対しＰＶＢ系樹脂バインダー１６質量部および可塑剤（ジメチルフタレ−ト）４質量部を溶解したトルエン−イソプロパノール−キシレン溶媒を添加し、さらに２４時間湿式混合して、シート成形用スラリーを得た。この成形用スラリーの粘度が５０ポイズ程度となるよう真空脱泡して溶媒量を調整後、ドクターブレード装置を使用して、得られた混合粉末スラリーをキャリアフィルム上に所定の厚みでキャストして、シート成形されたグリーンシートを得た。さらに、得られたグリーンシートを温度１２０℃、所定の圧力で３枚積層圧着処理して、焼き上がり寸法が０．３５ｍｍ程度の厚みとなるシートを作製した。その後、これを６０ｍｍ×７０ｍｍに切断してグリーンシートとした。3. The above-mentioned yttrium oxide as a sintering aid was added to 94.5 parts by mass of the raw material SN powder having a specific surface area of 18.5 m 2 / g and an oxygen content of 1.77% by mass produced by the method disclosed in Patent Document 4. Made of resin for ball mills together with a toluene-isopropanol-xylene solvent in which 5 parts by mass and 2 parts by mass of the above-mentioned magnesium oxide are blended and an amine-based dispersant is dissolved in powder in 2 parts by mass, and a silicon nitride ball as a pulverizing medium. It was put into a pot and wet-mixed for 24 hours. The obtained slurry was passed through a sieve having a mesh size of 44 μm, and then 16 parts by mass of a PVB-based resin binder and 4 parts by mass of a plasticizer (dimethyl phthalate) were dissolved in 100 parts by mass of the mixed powder in the resin pot. -Isopropanol-xylene solvent was added and wet-mixed for another 24 hours to obtain a sheet-forming slurry. After adjusting the amount of solvent by vacuum defoaming so that the viscosity of this molding slurry becomes about 50 poise, the obtained mixed powder slurry is cast on a carrier film to a predetermined thickness using a doctor blade device. , A sheet-molded green sheet was obtained. Further, the obtained green sheet was laminated and crimped at a temperature of 120 ° C. and a predetermined pressure to prepare a sheet having a baked size of about 0.35 mm. Then, this was cut into 60 mm × 70 mm to obtain a green sheet.

表１に示す分離材ＳＮ粉とエタノールとを分離材ＳＮ粉／エタノール＝１／５の割合で直径１０ｍｍの窒化ケイ素製ボールを用いてバッチ式振動ミルを用いて、振動数１２００ｃｐｍ、振幅８ｍｍで５分間混合して、分離材ＳＮ粉スラリーを作製した後、スプレー式の塗布機を用いて、グリーンシートの片側の表面（最下段のグリーンシートは両面のそれぞれ）に、０．６ｍｇ／ｃｍ２の塗布量で塗布した。分離材を塗布したグリーンシートの乾燥は、２５℃大気中で５分間行った。また、分離材ＳＮ粉の塗布量は塗布・乾燥工程前後のシートの重量を測定し、その重量の差をシートの塗布面の面積で割ることにより算出した。The separating material SN powder and ethanol shown in Table 1 are separated from the separating material SN powder / ethanol = 1/5 with a silicon nitride ball having a diameter of 10 mm and a batch type vibration mill at a frequency of 1200 cpm and an amplitude of 8 mm. After mixing for 5 minutes to prepare a separating material SN powder slurry, 0.6 mg / cm 2 was applied to one surface of the green sheet (the bottom green sheet is on both sides) using a spray-type coating machine. It was applied with the amount of application of. The green sheet coated with the separating material was dried in the air at 25 ° C. for 5 minutes. The coating amount of the separating material SN powder was calculated by measuring the weight of the sheet before and after the coating / drying step and dividing the difference in weight by the area of the coated surface of the sheet.

分離材ＳＮ粉１が塗布されたグリーンシート２は塗布された面を上面とし１０枚積層して、ＢＮ製セッタ３上に配置し、ＢＮ製セッタ３上の積層されたグリーンシート２の脇にＢＮ製スペーサ４を配置して、その上にＢＮ製セッタ３を載せた（図１）。空気中４００〜６００℃で２〜５時間加熱することにより、予め添加した有機バインダー成分等を十分に脱脂（除去）した。次いで、この脱脂体を、０．８ＭＰａの窒素雰囲気下で、１８５０℃まで加熱し、さらに１８５０℃で１０時間保持して焼結した。室温まで冷却し、１０枚の窒化ケイ素焼結体が積層された窒化ケイ素焼結体を得た。その後、各窒化ケイ素焼結体を分離し、窒化ケイ素焼結体間が剥離できるか否かを確認した。１０枚の窒化ケイ素焼結体に割れやクラックが発生することなく容易に剥離できた。分離した窒化ケイ素質焼結体をブラスト研磨加工し、実施例１の窒化ケイ素基板を得た。なお、ブラスト研磨加工による除去厚みは、平均値で１０μｍ以下であった。 The green sheet 2 coated with the separating material SN powder 1 is laminated on the BN setter 3 with the coated side facing the upper surface, and is placed on the side of the laminated green sheet 2 on the BN setter 3. A BN spacer 4 was arranged, and a BN setter 3 was placed on the spacer 4 (FIG. 1). By heating in air at 400 to 600 ° C. for 2 to 5 hours, the organic binder component and the like added in advance were sufficiently degreased (removed). Next, the degreased body was heated to 1850 ° C. under a nitrogen atmosphere of 0.8 MPa, and further held at 1850 ° C. for 10 hours for sintering. The mixture was cooled to room temperature to obtain a silicon nitride sintered body in which 10 silicon nitride sintered bodies were laminated. Then, each silicon nitride sintered body was separated, and it was confirmed whether or not the silicon nitride sintered bodies could be separated from each other. The 10 silicon nitride sintered bodies could be easily peeled off without cracks or cracks. The separated silicon nitride sintered body was blast-polished to obtain the silicon nitride substrate of Example 1. The thickness removed by the blast polishing process was 10 μm or less on average.

実施例１における、原料粉末に用いたＳＮ粉（原料ＳＮ粉）、分離材に用いたＳＮ粉（分離材ＳＮ粉）の物性値および塗布量と、焼結条件を表１に示す。また、剥離性、窒化ケイ素基板の特性を表２に示す。表２における「面積比」は、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子の面積比である。 Table 1 shows the physical property values and coating amount of the SN powder (raw material SN powder) used for the raw material powder and the SN powder (separation material SN powder) used for the separating material in Example 1, and the sintering conditions. Table 2 shows the peelability and the characteristics of the silicon nitride substrate. The "area ratio" in Table 2 is the area ratio of columnar crystal particles having a minor axis a of 0.5 to 5 μm and a ratio of the major axis b to the minor axis a (b / a) of 2 or more.

（実施例２〜７）
分離材に使用するＳＮ粉（分離材ＳＮ粉）を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 2 to 7)
A silicon nitride substrate was produced by the same method as in Example 1 except that the SN powder used for the separation material (separation material SN powder) was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例８）
原料に使用するＳＮ粉（原料ＳＮ粉）を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 8)
A silicon nitride substrate was produced by the same method as in Example 1 except that the SN powder used as the raw material (raw material SN powder) was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例９〜１３）
分離材ＳＮ粉の塗布量を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 9 to 13)
A silicon nitride substrate was produced by the same method as in Example 1 except that the coating amount of the separating material SN powder was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例１４および１５）
焼結時の最高温度を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 14 and 15)
A silicon nitride substrate was produced by the same method as in Example 1 except that the maximum temperature at the time of sintering was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例１６〜１８）
焼結時の最高温度での保持時間を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 16 to 18)
A silicon nitride substrate was produced by the same method as in Example 1 except that the holding time at the maximum temperature during sintering was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例１９）
焼結時の窒素ガス圧力を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 19)
A silicon nitride substrate was produced by the same method as in Example 1 except that the nitrogen gas pressure at the time of sintering was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２０）
焼結時の窒素ガス圧力と最高温度での保持時間を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 20)
A silicon nitride substrate was produced by the same method as in Example 1 except that the nitrogen gas pressure at the time of sintering and the holding time at the maximum temperature were changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２１）
ブラスト研磨の後にラップ研磨加工を行った以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 21)
A silicon nitride substrate was produced by the same method as in Example 1 except that the wrap polishing process was performed after the blast polishing, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２２）
得られた窒化ケイ素基板のＲａが０．４８μｍとなるように表面研磨加工におけるブラスト研磨の程度を調整した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 22)
A silicon nitride substrate was manufactured by the same method as in Example 1 except that the degree of blast polishing in the surface polishing process was adjusted so that the Ra of the obtained silicon nitride substrate was 0.48 μm, and the same evaluation was performed. .. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２３）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 23)
A silicon nitride substrate was manufactured by the same method as in Example 1 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２４）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 24)
A silicon nitride substrate was produced by the same method as in Example 1 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２５）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例２と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 25)
A silicon nitride substrate was produced by the same method as in Example 2 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２６）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例３と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 26)
A silicon nitride substrate was produced by the same method as in Example 3 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２７）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例４と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 27)
A silicon nitride substrate was produced by the same method as in Example 4 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２８）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例５と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 28)
A silicon nitride substrate was produced by the same method as in Example 5 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例２９）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例６と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 29)
A silicon nitride substrate was produced by the same method as in Example 6 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３０）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例７と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 30)
A silicon nitride substrate was produced by the same method as in Example 7 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３１）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例９と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 31)
A silicon nitride substrate was produced by the same method as in Example 9 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３２）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例１０と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 32)
A silicon nitride substrate was produced by the same method as in Example 10 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３３）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例１１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 33)
A silicon nitride substrate was produced by the same method as in Example 11 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３４）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例１２と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 34)
A silicon nitride substrate was produced by the same method as in Example 12 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３５）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例２と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 35)
A silicon nitride substrate was manufactured by the same method as in Example 2 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３６）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例３と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 36)
A silicon nitride substrate was manufactured by the same method as in Example 3 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３７）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例４と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 37)
A silicon nitride substrate was manufactured by the same method as in Example 4 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３８）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例５と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 38)
A silicon nitride substrate was manufactured by the same method as in Example 5 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例３９）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例６と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 39)
A silicon nitride substrate was manufactured by the same method as in Example 6 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例４０）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例７と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 40)
A silicon nitride substrate was manufactured by the same method as in Example 7 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例４１）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例９と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 41)
A silicon nitride substrate was manufactured by the same method as in Example 9 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例４２）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例１０と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 42)
A silicon nitride substrate was manufactured by the same method as in Example 10 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例４３）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例１１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 43)
A silicon nitride substrate was manufactured by the same method as in Example 11 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例４４）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例１２と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 44)
A silicon nitride substrate was manufactured by the same method as in Example 12 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例５１〜５３）
分離材のＳＮ粉を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 51 to 53)
A silicon nitride substrate was produced by the same method as in Example 1 except that the SN powder of the separating material was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例５４および５５）
分離材のＳＮ粉の塗布量を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 54 and 55)
A silicon nitride substrate was produced by the same method as in Example 1 except that the coating amount of the SN powder of the separating material was changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例５６〜５８）
焼結時の焼成条件を表１に記載された条件に変更した以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 56 to 58)
A silicon nitride substrate was produced by the same method as in Example 1 except that the firing conditions at the time of sintering were changed to the conditions shown in Table 1, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例５９）
焼結条件を表1に記載された条件に変更し、ブラスト研磨の後にＲａが０．０２μｍとなるまでラップ研磨加工を行った以外は、実施例１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 59)
A silicon nitride substrate was produced by the same method as in Example 1 except that the sintering conditions were changed to the conditions shown in Table 1 and lap polishing was performed until Ra became 0.02 μm after blast polishing. A similar evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例６１〜６６）
実施例６１〜６６では、公知の方法である、非晶質Ｓｉ−Ｎ（−Ｈ）系化合物（アモルファス窒化ケイ素）を坩堝に充填して焼成するイミド熱分解法で製造された比表面積１１．５ｍ２／ｇ、酸素含有量１．３５重量％の原料ＳＮ粉に変更した以外は、それぞれ、実施例１〜６と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Examples 61-66)
In Examples 61 to 66, the specific surface area of 11. Silicon nitride substrates were produced by the same methods as in Examples 1 to 6 except that the raw material SN powder was changed to 5 m 2 / g and an oxygen content of 1.35% by weight, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例６７）
ＢＮ製セッタ３上に積層されたグリーンシート２の周りに窒化ケイ素（ＳＮ）粉を詰めた以外は、実施例６１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 67)
A silicon nitride substrate was produced by the same method as in Example 61 except that silicon nitride (SN) powder was packed around the green sheet 2 laminated on the BN setter 3, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例６８）
ＢＮ製セッタ３を窒化ケイ素（ＳＮ）製セッタに変更した以外は、実施例６１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 68)
A silicon nitride substrate was manufactured by the same method as in Example 61 except that the BN setter 3 was changed to a silicon nitride (SN) setter, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例６９）
焼結時の最高温度での保持時間を２２時間に変更した以外は、実施例６１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 69)
A silicon nitride substrate was produced by the same method as in Example 61 except that the holding time at the maximum temperature during sintering was changed to 22 hours, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例７０）
焼結時の最高温度を１９００℃に変更した以外は、実施例６１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 70)
A silicon nitride substrate was produced by the same method as in Example 61 except that the maximum temperature at the time of sintering was changed to 1900 ° C., and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例７１）
焼結助剤として表１に記載された量のＳｉＯ２を追加した以外は、実施例６１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 71)
A silicon nitride substrate was produced by the same method as in Example 61 except that the amounts of SiO 2 shown in Table 1 were added as a sintering aid, and the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例７２）
焼結助剤に表１に記載された量のＳｉＯ２を追加し、焼結時の最高温度での保持時間を２２時間に変更した以外は、実施例６１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 72)
A silicon nitride substrate was manufactured by the same method as in Example 61, except that the amounts of SiO 2 shown in Table 1 were added to the sintering aid and the holding time at the maximum temperature during sintering was changed to 22 hours. Then, the same evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

（実施例７３）
焼結助剤として表１に記載された量のＳｉＯ２を追加し、焼結時の最高温度を１９００℃に変更した以外は、実施例６１と同じ方法で窒化ケイ素基板を製造し、同様の評価を行った。剥離性、窒化ケイ素基板の特性を表２に示す。(Example 73)
A silicon nitride substrate was produced by the same method as in Example 61 except that the amount of SiO 2 shown in Table 1 was added as a sintering aid and the maximum temperature at the time of sintering was changed to 1900 ° C. Evaluation was performed. Table 2 shows the peelability and the characteristics of the silicon nitride substrate.

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Figure 2020090832
Figure 2020090832

上記実施例では、分離材としてＳＮ粉を用いることによって、窒化ケイ素基板の表面にはＢＮ粉が残存することがないので、窒化ケイ素基板に銅を接合した際の耐ヒートサイクル性に優れることができる。さらに、窒化ケイ素基板の表面から分離材を除去した後に表面に残存するＢＮ量は、ＢＮセッタを用いた場合であっても、ホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１２×１０−５以下と極めて少なく、窒化ケイ素基板に銅を接合した際の耐ヒートサイクル性に優れるのみならず、ＳＮ製セッタを用いたり、ＳＮ粉の詰め粉をすると、窒化ケイ素基板の表面にＢＮは検出されなかった。In the above embodiment, by using the SN powder as the separating material, the BN powder does not remain on the surface of the silicon nitride substrate, so that the heat cycle resistance when copper is bonded to the silicon nitride substrate is excellent. can. Further, the amount of BN remaining on the surface after removing the separating material from the surface of the silicon nitride substrate is the fluorescent X-ray intensity of boron (B) and the fluorescent X of silicon (Si) even when a BN setter is used. The linear strength ratio (B / Si) is extremely small, 12 × 10-5 or less, and it not only has excellent heat cycle resistance when copper is bonded to a silicon nitride substrate, but also uses an SN setter or uses SN powder. When stuffing was performed, no BN was detected on the surface of the silicon nitride substrate.

上記表１および表２の実施例１〜４４に示されるように、分離材として比表面積が１ｍ２／ｇ以上２０ｍ２／ｇ以下、Ｄ５０が２０μｍ以下、酸素量が０．３質量％以上２重量％未満、アルミニウム含有量が５０ｐｐｍ未満の窒化ケイ素（ＳＮ）粉を用いＳＮ粉のグリーンシート表面への塗布量を０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下とすると、実施例１〜４４の全てにおいて焼結後の剥離性が良好であり、曲げ強度が９００ＭＰａ以上、熱伝導率が９０Ｗ／（ｍ・Ｋ）以上、さらには９５Ｗ／（ｍ・Ｋ）以上の高い窒化ケイ素基板が得られることを確認した。As shown in Examples 1 to 44 of Tables 1 and 2 above, the specific surface area of the separating material is 1 m 2 / g or more and 20 m 2 / g or less, D50 is 20 μm or less, and the amount of oxygen is 0.3% by mass or more 2 When silicon nitride (SN) powder having a specific surface area of less than% by weight and an aluminum content of less than 50 ppm is used and the amount of the SN powder applied to the surface of the green sheet is 0.1 mg / cm 2 or more and 3 mg / cm 2 or less, Examples 1-44 In all of the above, the peelability after sintering is good, and a silicon nitride substrate having a bending strength of 900 MPa or more, a thermal conductivity of 90 W / (m · K) or more, and a high silicon nitride substrate of 95 W / (m · K) or more can be obtained. I confirmed that it was possible.

なお、実施例５１では、分離材ＳＮ粉の比表面積が０．４ｍ２／ｇのとき、焼結後の剥離性が実施例１と比べて劣り、曲げ強度は８５０ＭＰａを示した。In Example 51, when the specific surface area of the separating material SN powder was 0.4 m 2 / g, the peelability after sintering was inferior to that of Example 1, and the bending strength was 850 MPa.

実施例５２では、分離材ＳＮ粉の比表面積を２３．２ｍ２／ｇのとき、焼結後の剥離性が実施例１と比べて劣り、曲げ強度は８００ＭＰａを示した。In Example 52, when the specific surface area of the separating material SN powder was 23.2 m 2 / g, the peelability after sintering was inferior to that of Example 1, and the bending strength was 800 MPa.

実施例５３では、分離材ＳＮ粉のアルミニウム含有量を７０ｐｐｍとしたとき、剥離性は良好だが、熱伝導率が８０Ｗ／（ｍ・Ｋ）であった。 In Example 53, when the aluminum content of the separating material SN powder was 70 ppm, the peelability was good, but the thermal conductivity was 80 W / (m · K).

実施例５４および５５では、分離材ＳＮ粉の塗布量を０．０７および３．５ｍｇ／ｃｍ２としたとき、焼結後の剥離性が実施例１と比べて劣り、曲げ強度が８３０および８００ＭＰａであった。In Examples 54 and 55, when the coating amounts of the separating material SN powder were 0.07 and 3.5 mg / cm 2 , the peelability after sintering was inferior to that of Example 1, and the bending strength was 830 and 800 MPa. Met.

実施例５６では、焼結時の最高温度が１９００℃としたとき、得られた窒化ケイ素基板の柱状結晶粒子の面積比が４３％と高くなり、剥焼結後の剥離性が実施例１と比べて劣り、曲げ強度は７８０ＭＰａを示した。 In Example 56, when the maximum temperature at the time of sintering was 1900 ° C., the area ratio of the columnar crystal particles of the obtained silicon nitride substrate was as high as 43%, and the peelability after sintering was the same as that of Example 1. It was inferior to the comparison, and the bending strength was 780 MPa.

実施例５７では、焼結時の最高温度の保持時間を３０時間としたとき、得られた窒化ケイ素基板の柱状結晶粒子の面積比が５３％と高くなり、焼結後の剥離性が実施例１と比べて劣り、曲げ強度は７３０ＭＰａを示した。 In Example 57, when the maximum temperature holding time at the time of sintering was set to 30 hours, the area ratio of the columnar crystal particles of the obtained silicon nitride substrate was as high as 53%, and the peelability after sintering was Example. It was inferior to No. 1 and showed a bending strength of 730 MPa.

実施例５８では、焼結時のガス圧力を４ＭＰａとしたとき、得られた窒化ケイ素基板の面積比が３７％と高くなり、焼結後の剥離性が実施例１と比べて劣り、曲げ強度は８４０ＭＰａを示した。 In Example 58, when the gas pressure at the time of sintering was 4 MPa, the area ratio of the obtained silicon nitride substrate was as high as 37%, the peelability after sintering was inferior to that of Example 1, and the bending strength. Showed 840 MPa.

実施例５９では、焼結時の最高温度が１７８０℃としたとき、面積比が１２％で、剥離性は良好だが、曲げ強度が８６０ＭＰａと熱伝導率が８０Ｗ／（ｍ・Ｋ）を示した。 In Example 59, when the maximum temperature at the time of sintering was 1780 ° C., the area ratio was 12% and the peelability was good, but the bending strength was 860 MPa and the thermal conductivity was 80 W / (m · K). ..

実施例５１〜５９においては、窒化ケイ素基板の曲げ強度及び熱伝導率は、実施例１〜４４には劣るものの、従来技術によるものと比べると同等以上に優れている。さらに、窒化ケイ素基板の表面にはＢＮ粉が残存することがなく、ＢＮセッタを用いているにもかかわらず、ホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１６×１０−５以下と極めて少なく、窒化ケイ素基板に銅を接合した際の耐ヒートサイクル性に優れることができるものである。In Examples 51 to 59, the bending strength and thermal conductivity of the silicon nitride substrate are inferior to those of Examples 1 to 44, but are equal to or higher than those of the prior art. Further, no BN powder remains on the surface of the silicon nitride substrate, and the ratio of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si) despite the use of a BN setter. The (B / Si) value is as small as 16 × 10-5 or less, and the heat cycle resistance when copper is bonded to the silicon nitride substrate can be excellent.

実施例６１〜６６では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％のとき、窒化ケイ素基板の曲げ強度は８３０〜８８０ＭＰａ、熱伝導率は８６〜８７Ｗ／（ｍ・Ｋ）を示した。In Examples 61 to 66, when the specific surface area of the raw material SN powder is 11.5 m 2 / g and the total oxygen content is 1.35%, the bending strength of the silicon nitride substrate is 830 to 880 MPa and the thermal conductivity is 86 to 87 W. / (M · K) was shown.

実施例６７では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％とし、グリーンシートの周りを窒化ケイ素（ＳＮ）粉で覆ったとき、窒化ケイ素基板にホウ素（Ｂ）は検出されず、窒化ケイ素基板の曲げ強度は８９０ＭＰａ、熱伝導率は８７Ｗ／（ｍ・Ｋ）を示した。In Example 67, when the specific surface area of the raw material SN powder was 11.5 m 2 / g, the total oxygen content was 1.35%, and the green sheet was covered with silicon nitride (SN) powder, the silicon nitride substrate was coated with boron. (B) was not detected, and the bending strength of the silicon nitride substrate was 890 MPa, and the thermal conductivity was 87 W / (m · K).

実施例６８では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％とし、窒化ケイ素（ＳＮ）製セッタを用いたとき、窒化ケイ素基板にホウ素（Ｂ）は検出されず、窒化ケイ素基板の曲げ強度は８７０ＭＰａ、熱伝導率は８６Ｗ／（ｍ・Ｋ）を示した。In Example 68, when the specific surface area of the raw material SN powder was 11.5 m 2 / g, the total oxygen content was 1.35%, and a silicon nitride (SN) setter was used, boron (B) was present on the silicon nitride substrate. It was not detected, and the bending strength of the silicon nitride substrate was 870 MPa, and the thermal conductivity was 86 W / (m · K).

実施例６９では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％とし、焼結時の最高温度での保持時間を２２時間にしたとき、窒化ケイ素基板の曲げ強度は８３０ＭＰａ、熱伝導率は９０Ｗ／（ｍ・Ｋ）を示した。In Example 69, when the specific surface area of the raw material SN powder was 11.5 m 2 / g, the total oxygen content was 1.35%, and the holding time at the maximum temperature during sintering was 22 hours, the silicon nitride substrate was formed. The bending strength was 830 MPa, and the thermal conductivity was 90 W / (m · K).

実施例７０では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％とし、焼結時の最高温度を１９００℃にしたとき、窒化ケイ素基板の曲げ強度は８２０ＭＰａ、熱伝導率は９２Ｗ／（ｍ・Ｋ）を示した。In Example 70, when the specific surface area of the raw material SN powder was 11.5 m 2 / g, the total oxygen content was 1.35%, and the maximum temperature during sintering was 1900 ° C., the bending strength of the silicon nitride substrate was 820 MPa. , The thermal conductivity was 92 W / (m · K).

実施例７１では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％とし、焼結助剤として０．８質量％のＳｉＯ２を追加し、焼結時の最高温度を１９００℃にしたとき、窒化ケイ素基板の曲げ強度は８５０ＭＰａ、熱伝導率は８８Ｗ／（ｍ・Ｋ）を示した。In Example 71, the specific surface area of the raw material SN powder was 11.5 m 2 / g, the total oxygen content was 1.35%, and 0.8% by mass of SiO 2 was added as a sintering aid to perform sintering. When the maximum temperature was 1900 ° C., the bending strength of the silicon nitride substrate was 850 MPa, and the thermal conductivity was 88 W / (m · K).

実施例７２では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％とし、焼結助剤として０．８質量％のＳｉＯ２を追加し、焼結時の最高温度での保持時間を２２時間にしたとき、窒化ケイ素基板の曲げ強度は８３０ＭＰａ、熱伝導率は９３Ｗ／（ｍ・Ｋ）を示した。In Example 72, the specific surface area of the raw material SN powder was 11.5 m 2 / g, the total oxygen content was 1.35%, and 0.8% by mass of SiO 2 was added as a sintering aid during sintering. When the holding time at the maximum temperature was 22 hours, the bending strength of the silicon nitride substrate was 830 MPa, and the thermal conductivity was 93 W / (m · K).

実施例７３では、原料ＳＮ粉の比表面積が１１．５ｍ２／ｇ、全酸素量が１．３５％とし、焼結助剤として０．８質量％のＳｉＯ２を追加し、焼結時の最高温度での保持時間を２２時間にしたとき、窒化ケイ素基板の曲げ強度は８１０ＭＰａ、熱伝導率は９５Ｗ／（ｍ・Ｋ）を示した。In Example 73, the specific surface area of the raw material SN powder was 11.5 m 2 / g, the total oxygen content was 1.35%, and 0.8% by mass of SiO 2 was added as a sintering aid during sintering. When the holding time at the maximum temperature was 22 hours, the bending strength of the silicon nitride substrate was 810 MPa, and the thermal conductivity was 95 W / (m · K).

実施例６１〜７３においては、窒化ケイ素基板の曲げ強度及び熱伝導率は、実施例１〜４４には劣るものの、従来技術によるものと比べると同等以上に優れている。さらに、ＢＮセッタを用いた場合でも、分離材としてＳＮ紛を用いることで、窒化ケイ素基板の表面にはＢＮ粉が残存することがなく、窒化ケイ素基板におけるホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１４．５×１０−５以下と極めて少ない。また、グリーンシートの周りをＳＮ紛で覆ったり、ＳＮ製セッタを用いると、窒化ケイ素基板にホウ素（Ｂ）の蛍光Ｘ線強度は検出されなかった。したがって、実施例６１〜７３の窒化ケイ素基板は、銅を接合した際の耐ヒートサイクル性に優れることができるものである。In Examples 61 to 73, the bending strength and thermal conductivity of the silicon nitride substrate are inferior to those of Examples 1 to 44, but are equal to or higher than those of the prior art. Further, even when a BN setter is used, by using SN powder as a separating material, BN powder does not remain on the surface of the silicon nitride substrate, and the fluorescent X-ray intensity of boron (B) on the silicon nitride substrate is increased. The ratio of fluorescent X-ray intensity of silicon (Si) (B / Si) is 14.5 × 10-5 or less, which is extremely small. Further, when the green sheet was covered with SN powder or an SN setter was used, the fluorescent X-ray intensity of boron (B) was not detected on the silicon nitride substrate. Therefore, the silicon nitride substrates of Examples 61 to 73 can be excellent in heat cycle resistance when copper is bonded.

本発明の窒化ケイ素基板の製造方法により、複数枚のグリーンシートを積層して焼結した後に分離することによって得られる窒化ケイ素基板であって、銅を接合した際の耐ヒートサイクル性に優れる窒化ケイ素基板が提供され、さらに、剥離性がよく、高い曲げ強度および高い熱伝導率を有し、変形の少ない窒化ケイ素基板を得ることができる。この窒化ケイ素基板はパワー素子モジュール等の基板として用いることができる。 A silicon nitride substrate obtained by laminating a plurality of green sheets, sintering them, and then separating them according to the method for manufacturing a silicon nitride substrate of the present invention, which has excellent heat cycle resistance when copper is bonded. A silicon nitride substrate is provided, and further, a silicon nitride substrate having good peelability, high bending strength and high thermal conductivity, and less deformation can be obtained. This silicon nitride substrate can be used as a substrate for a power element module or the like.

１ 分離材（ＳＮ粉）
２ グリーンシート
３ セッタ
４ スペーサ
５ 詰め粉（ＳＮ粉）
８ 窒化ケイ素粒子（柱状結晶粒子）
９ 分離材（ＳＮ粉）1 Separator (SN powder)
2 Green sheet 3 Setter 4 Spacer 5 Stuffing powder (SN powder)
8 Silicon nitride particles (columnar crystal particles)
9 Separator (SN powder)

Claims (16)

窒化ケイ素粉末および焼結助剤を含む複数枚のグリーンシートをそれらの間に分離材を配置して積層し、前記分離材は窒化ケイ素粉を含み、
得られる積層体中の前記複数枚のグリーンシートを焼結し、
前記積層体から分離することによって複数枚の窒化ケイ素焼結体を得、
前記窒化ケイ素焼結体から窒化ケイ素基板を得る
ことを特徴とする窒化ケイ素基板の製造方法。A plurality of green sheets containing silicon nitride powder and a sintering aid were laminated by arranging a separating material between them, and the separating material contained silicon nitride powder.
The plurality of green sheets in the obtained laminate are sintered and
By separating from the laminate, a plurality of silicon nitride sintered bodies can be obtained.
A method for manufacturing a silicon nitride substrate, which comprises obtaining a silicon nitride substrate from the silicon nitride sintered body. 前記複数枚のグリーンシートの前記焼結を、窒化ケイ素製囲繞体又は窒化ホウ素製囲繞体内で行うことを特徴とする請求項１に記載の窒化ケイ素基板の製造方法。 The method for producing a silicon nitride substrate according to claim 1, wherein the sintering of the plurality of green sheets is performed in a silicon nitride enclosure or a boron nitride enclosure. 前記複数枚のグリーンシートの周りを窒化ケイ素粉で覆って前記焼結を行うことを特徴とする請求項１又は２に記載の窒化ケイ素基板の製造方法。 The method for producing a silicon nitride substrate according to claim 1 or 2, wherein the plurality of green sheets are covered with silicon nitride powder to perform the sintering. 前記焼結後に得られる前記窒化ケイ素焼結体の表面に残存する前記分離材を除去することを特徴とする請求項１〜３のいずれか一項に記載の窒化ケイ素基板の製造方法。 The method for producing a silicon nitride substrate according to any one of claims 1 to 3, wherein the separating material remaining on the surface of the silicon nitride sintered body obtained after the sintering is removed. 前記分離材は、ＢＥＴ法により測定される比表面積が１ｍ２／ｇ以上２０ｍ２／ｇ以下であり、レーザ回折散乱法により測定される体積基準の５０％粒子径Ｄ５０が２０μｍ以下であり、かつ、酸素量が０．３重量％以上２重量％未満であり、
前記分離材は０．１ｍｇ／ｃｍ２以上３ｍｇ／ｃｍ２以下の塗布量で前記グリーンシートの表面に塗布されていることを特徴とする請求項１〜４のいずれか一項に記載の窒化ケイ素基板の製造方法。The separating material has a specific surface area measured by the BET method of 1 m 2 / g or more and 20 m 2 / g or less, a volume-based 50% particle diameter D50 measured by the laser diffraction / scattering method of 20 μm or less, and , The amount of oxygen is 0.3% by weight or more and less than 2% by weight,
The silicon nitride according to any one of claims 1 to 4, wherein the separating material is applied to the surface of the green sheet at a coating amount of 0.1 mg / cm 2 or more and 3 mg / cm 2 or less. Substrate manufacturing method. 前記分離材のアルミニウム含有量が５０ｐｐｍ未満であることを特徴とする請求項５に記載の窒化ケイ素基板の製造方法。 The method for producing a silicon nitride substrate according to claim 5, wherein the aluminum content of the separating material is less than 50 ppm. 前記焼結が、窒素雰囲気中でガス圧力０．１５ＭＰａ以上３ＭＰａ以下、焼結温度１７５０℃以上１９１０℃以下で６時間以上２２時間以下保持して行われることを特徴とする請求項５又は６に記載の窒化ケイ素基板の製造方法。 5. The method for manufacturing a silicon nitride substrate according to the above method. 窒化ケイ素粒子と焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、厚さが０．５ｍｍ以下であり、前記基板の表面に窒化ホウ素粉を有していないことを特徴とする窒化ケイ素基板。 A silicon nitride substrate made of a silicon nitride sintered body containing silicon nitride particles and a sintering aid, having a thickness of 0.5 mm or less and having no boron nitride powder on the surface of the substrate. A characteristic silicon nitride substrate. 前記基板の表面における窒化ホウ素と窒化ケイ素の比がホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１５×１０−５以下であることを特徴とする請求項８に記載の窒化ケイ素基板。 The ratio of boron nitride to silicon nitride on the surface of the substrate is 15 × 10-5 or less in terms of the ratio (B / Si) of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si). The silicon nitride substrate according to claim 8, wherein the silicon nitride substrate is characterized. 前記基板が窒化ホウ素（ＢＮ）を含まないことを特徴とする請求項８に記載の窒化ケイ素基板。 The silicon nitride substrate according to claim 8, wherein the substrate does not contain boron nitride (BN). 窒化ケイ素粒子と焼結助剤を含有する窒化ケイ素焼結体からなる窒化ケイ素基板であって、前記窒化ケイ素粒子は、短径ａが０．５〜５μｍでかつ短径ａに対する長径ｂの比（ｂ／ａ）が２以上の柱状結晶粒子を前記基板表面における面積比で３５％以下とし、かつ前記基板表面の算術平均表面粗さが０．０３μｍ以上０．５μｍ以下であり、前記基板表面における窒化ホウ素と窒化ケイ素の比がホウ素（Ｂ）の蛍光Ｘ線強度とケイ素（Ｓｉ）の蛍光Ｘ線強度の比（Ｂ／Ｓｉ）で１５×１０−５以下であることを特徴とする窒化ケイ素基板。A silicon nitride substrate made of a silicon nitride sintered body containing silicon nitride particles and a sintering aid, wherein the silicon nitride particles have a minor axis a of 0.5 to 5 μm and a ratio of a major axis b to a minor axis a. Columnar crystal particles having (b / a) of 2 or more have an area ratio of 35% or less on the substrate surface, and the arithmetic average surface roughness of the substrate surface is 0.03 μm or more and 0.5 μm or less, and the substrate surface. The ratio of boron nitride to silicon nitride in the above is 15 × 10 -5 or less in the ratio (B / Si) of the fluorescent X-ray intensity of boron (B) to the fluorescent X-ray intensity of silicon (Si). Silicon substrate. 前記基板の表面に窒化ホウ素粉を有していないことを特徴とする請求項１１に記載の窒化ケイ素基板。 The silicon nitride substrate according to claim 11, wherein the surface of the substrate does not have boron nitride powder. 熱伝導率が室温において８０Ｗ／（ｍ・Ｋ）以上であり、４点曲げ強度が室温において８００ＭＰa以上であることを特徴とする請求項１１又は１２に記載の窒化ケイ素基板。 The silicon nitride substrate according to claim 11 or 12, wherein the silicon nitride substrate has a thermal conductivity of 80 W / (m · K) or more at room temperature and a four-point bending strength of 800 MPa or more at room temperature. 前記分離材のアルミニウム含有量が５０ｐｐｍ未満であることを特徴とする請求項１１〜１３のいずれか一項に記載の窒化ケイ素基板。 The silicon nitride substrate according to any one of claims 11 to 13, wherein the aluminum content of the separating material is less than 50 ppm. 厚さが０．５ｍｍ以下であることを特徴とする請求項１１〜１４のいずれか一項に記載の窒化ケイ素基板。 The silicon nitride substrate according to any one of claims 11 to 14, wherein the silicon nitride substrate has a thickness of 0.5 mm or less. 請求項８〜１５のいずれか一項に記載の窒化ケイ素基板を用いたことを特徴とする絶縁基板または回路基板。 An insulating substrate or a circuit board using the silicon nitride substrate according to any one of claims 8 to 15.
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