JP4006716B2 - High purity silicon carbide powder and method for producing the same - Google Patents
High purity silicon carbide powder and method for producing the same Download PDFInfo
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Description
【０００１】
【産業上の利用分野】
本発明は、高純度炭化珪素粉及びその製造方法、詳しくは高純度化が進む半導体工業で有用な高純度炭化珪素粉及びその製造方法に関する。特に、シリコンウエハを重ねて熱処理する際の焼き付け防止緩衝剤として有用な高純度炭化珪素粉及びその製造方法に関する。
【０００２】
【従来技術】
従来、炭化珪素粉はセラミックス材料として用いられてきたが、半導体工業で使用する炭化珪素セラミックス部材は高純度であることが要請され、各種高純度の炭化珪素部材が提案されている。しかしながら、従来の炭化珪素セラミックス部材は最近特に問題となっている鉄成分の含有量が多く、それを原料として作成した半導体処理用部材で半導体製品を処理すると含有する鉄成分で半導体製品を汚染し、最悪の場合使用不能となることがある。特に炭化珪素粉をシリコンウエハの熱処理時の融着防止緩衝剤として使用する場合には１０００℃を超える高温に晒されるところから、含有する鉄成分が放出し易くシリコンウエハの汚染が起りウエハの劣化が起る。こうした不純物を除去するため塩酸や硝酸のような一般的な鉱酸や、これに過酸化水素を添加した洗浄液で処理することが提案されているが、いずれもシリコンウエハの熱処理時の融着防止緩衝剤とするには純度が満足するものではなかった。前記に加えて、市販の炭化珪素粉は硬度が高く、しかも高温下で軟化しにくいため、それを用いた融着防止緩衝剤は特公昭６３−４３４４号公報に記載するように炭化珪素粉がシリコンウエハの表面にくい込みそのまま残こり、ウエハの格子欠陥の原因となり、またその除去に薬剤による長時間の処理が必要であるなどの欠点があった。
【０００３】
【発明が解決しようとする課題】
こうした現状に鑑み本発明者等は鋭意研究を続けた結果、市販の高純度の炭化珪素粉、特にβ型炭化珪素粉を加圧下で加熱した鉱酸、特に加熱したフッ化水素酸で処理すると抽出される鉄成分がナノグラム単位まで容易に除去でき、融着防止緩衝剤として使用してもシリコンウエハを汚染することがないことを見出した。さらに前記炭化珪素粉はシリコンウエハに損傷を与えることがないこともわかった。こうした知見に基づいて本発明は完成したものである。すなわち、
【０００４】
本発明は、半導体工業用部材の原料として有用な高純度炭化珪素粉を提供することを目的とする。
【０００５】
また、本発明は、上記高純度炭化珪素粉からなるウエハの融着防止用緩衝剤を提供することを目的とする。
【０００６】
さらに、本発明は、上記高純度炭化珪素粉の製造方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成する本発明は、１６０℃の加熱したフッ化水素酸に溶出する鉄成分の溶出量が炭化珪素粉１グラム当たり１０ナノグラム以下であることを特徴とする高純度炭化珪素粉、および該高純度炭化珪素粉の製造方法に係る。
【０００８】
本発明の高純度炭化珪素粉は、上述のとおり１６０℃の加熱したフッ化水素酸に溶出する鉄成分の溶出量が炭化珪素粉１グラム当たり１０ナノグラム以下の超高純度の炭化珪素粉である。前記炭化珪素粉をウエハの融着防止用緩衝剤として使用し１０００℃を超える高温で加熱しても鉄成分を放出し、シリコンウエハを汚染することがない。本発明の炭化珪素粉の純度を１６０℃の加圧下で加熱したフッ化水素酸に溶出する鉄成分の溶出量と規定したのは１０００℃を超えるウエハの熱処理時に放出される鉄成分が前記加熱フッ化水素酸に抽出される状態の鉄成分に類似するとの知見に基づくものである。
【０００９】
上記高純度炭化珪素粉は、炭化珪素粉に鉱酸を加え、加圧下で加熱することで製造できるが、好ましくは室温で炭化珪素粉とフッ化水素酸を密閉容器に導入し、それを１６０℃に加熱保持して内部に加圧状態を作り出すのがよい。後に室温にまで冷却しフッ化水素酸中に抽出された鉄成分含有量を炭化珪素粉１グラム当たり１０ナノグラム以下であるかを確認する。前記抽出される鉄成分の含有量はフッ化水素酸中の鉄成分含有量をモニターすることで測定できる。前記製造方法の１回目でフッ化水素酸中の鉄成分含有量が炭化珪素粉１グラム当たり１０ナノグラムを超えるときは、フッ化水素酸を取り替えたのち加圧下の加熱フッ化水素酸処理を溶出する鉄成分含有量が１０ナノグラム以下になるまで繰り返す。より好ましい製造方法は炭化珪素粉重量１ｇに対して５ｍｌの割合で５０％フッ化水素酸を加える方法である。前記製造方法では炭化珪素粉に付着する不純物のすすぎと処理効率とがバランスよく行え経済的である。
【００１０】
本発明の製造方法における加熱温度は精製効率から高温の方がよい。高純度の耐熱性容器としてフッ素樹脂容器が好適であり、この容器の耐熱限界である１６０℃を加熱温度とし、加熱時間を３〜１０時間とするのがよい。加熱時間が３時間未満では容器内の温度の均一化が不十分で抽出が充分行われず。また１０時間を超えても処理効率の向上が望めない。こうした加圧下での加熱処理で炭化珪素粒子の表面に形成されている二酸化珪素の酸化膜中の鉄成分が容易に溶出され、ウエハの熱処理時にウエハを鉄成分で汚染することがない。
【００１１】
上記製造方法で使用する容器としては加圧に耐えるオートクレーブが考えられるが、フッ化水素酸を１６０℃に加熱するとフッ素成分が揮発し容器内圧力を上昇させるところから密閉容器で充分である。前記密閉容器に炭化珪素粉とフッ化水素酸を導入し１６０℃に加熱すると、容器内はおよそ１．５気圧に達し、二酸化珪素が激しくエッチングされ含有鉄成分の精製が充分に行なわれる。前記密閉容器の具体例としては、フッ素樹脂の密閉容器をステンレスのような金属ジャケットに収めた二重容器が挙げられる。
【００１２】
本発明の製造方法では、最大粒径が１５０μｍ以下、かさ密度が１．２ｇ／ｃｍ3以下の高純度の炭化珪素粉、好ましくはβ型炭化珪素粉を使用するのがよい。前記炭化珪素粉の原料として一次粒子の粗いものを用いると、抽出される鉄成分を炭化珪素粉１グラム当たり１０ナノグラム以下とするための処理回数を多くする必要があるので、最大粒径を１５０μｍとする。最大粒径が１５０μｍ以下の細粉であっても、かさ密度が１．２ｇ／ｃｍ3を超えるような、強く凝集した状態は鉄成分の抽出が良好に行われず処理回数が多くなる。前記珪素粉原料としては、例えばイビデン社製炭化珪素粉（商品名ＳＣＰ−００）などを挙げることができる。
【００１３】
本発明の製造方法で製造された炭化珪素粉は、高純度であるところから、緩衝剤にとどまらず、焼結して半導体製品処理用部材としても使用できる。
【００１４】
【発明の実施の態様】
次に具体例に基づいて本発明を詳細に説明するが、本発明はそれにより限定されるものではない。
【００１５】
【実施例】
実施例１
β型結晶の高純度炭化珪素粉（イビデン株式会社ＳＣＰ−００）１ｇをフッ化樹脂製容器に入れ、５ｍｌの５０％フッ化水素酸を加え、密閉蓋をしたのち、金属ジャケットに収めた。前記高純度炭化珪素粉は１００メッシュのふるいをパスした最大粒径が１４０μｍ以下、かさ密度が１．０１ｇ／ｃｍ3の炭化珪素粉である。
【００１６】
上記金属ジャケットごと１６０℃に加熱し、４時間保持した後室温にまで冷却し、その上澄みのフッ化水素酸中の鉄成分を原子吸光光度法で測定した。その結果は１０２０ナノグラムであった。この炭化珪素粉を取り出して純水で２回洗浄し、再び５ｍｌのフッ化水素酸を新たに加え加熱抽出した。２回目に抽出された鉄成分は２０ナノグラムであった。さらに繰り返して処理を行ったところ、３回目には原子吸光光度法の定量限界の１０ナノグラム以下となった。この炭化珪素粉を取り出して純水で洗浄し、クリーンオーブンで乾燥して、高純度炭化珪素粉を得た。前記炭化珪素粉を、直径３インチのウエハ５０枚の間に少量ずつ撒き散らして縦に積み重ねて熱処理したところ、緩衝効果は良好であり、ミノリティキャリアーのライフタイムの劣化もなかった。
【００１７】
比較例１
実施例１で製造した炭化珪素粉を単に純水で洗浄し、乾燥しただけで、実施例１と同様にして３インチの口径のウエハ５０枚の間に少量ずつ撒き散らして縦に積み重ねて熱処理したところ、ウエハ同士の貼り付きは生じなかったが、鉄成分による汚染が原因と思われるミノリティキャリアーのライフタイムの劣化が起こった。
【００１８】
比較例２
１００メッシュふるい上の、平均粒径が１７０μｍの炭化珪素粉を実施例１と同様にして加圧下でフッ化水素酸で洗浄した。前記炭化珪素粉のかさ密度は１．４ｇ／ｃｍ3あった。フッ化水素酸に抽出された鉄成分は炭化珪素粉１ｇあたりで、１回目が８００ナノグラム、２回目が６２０ナノグラム、３回目が４９０ナノグラム、４回目が４９０ナノグラムであった。実施例１と同様にウエハ貼り付き防止に用いたところ、ライフタイムの劣化が生じて、ウエハは総て規格外のものになってしまった。
【００１９】
【発明の効果】
本発明の高純度炭化珪素粉は、鉄成分の含有量が極めて少なく半導体工業で使用する各種部材の原料として有用である。特にウエハの熱処理時の融着防止用緩衝剤として使用してもウエハを鉄成分で汚染することがない。前記高純度炭化珪素粉は容器内に炭化珪素粉末と鉱酸を導入し、加圧下で加熱することで容易に製造でき工業的価値が高いものである。[0001]
[Industrial application fields]
The present invention relates to a high-purity silicon carbide powder and a method for producing the same, and more particularly to a high-purity silicon carbide powder useful in the semiconductor industry where purification is advanced and a method for producing the same. In particular, the present invention relates to a high-purity silicon carbide powder useful as an anti-baking buffer when heat-treating a silicon wafer, and a method for producing the same.
[0002]
[Prior art]
Conventionally, silicon carbide powder has been used as a ceramic material, but silicon carbide ceramic members used in the semiconductor industry are required to have high purity, and various high-purity silicon carbide members have been proposed. However, conventional silicon carbide ceramic members have a particularly high content of iron components, which has become a problem in recent years. When semiconductor products are processed with semiconductor processing members made from such raw materials, the semiconductor products are contaminated with the contained iron components. In the worst case, it may become unusable. In particular, when silicon carbide powder is used as an anti-fusing buffer during the heat treatment of silicon wafers, it is exposed to high temperatures exceeding 1000 ° C., so that the contained iron components are likely to be released and the silicon wafers are contaminated and the wafers deteriorate. Happens. In order to remove these impurities, it has been proposed to treat with a general mineral acid such as hydrochloric acid or nitric acid, or a cleaning solution to which hydrogen peroxide has been added. The purity of the buffer was not satisfactory. In addition to the above, since commercially available silicon carbide powder has high hardness and is difficult to soften at high temperature, the anti-fusing buffer using the same is disclosed in Japanese Patent Publication No. 63-4344. The surface of the silicon wafer remains difficult to be left, which causes a lattice defect of the wafer, and it requires a long time treatment with a chemical agent to remove it.
[0003]
[Problems to be solved by the invention]
In view of the current situation, the present inventors have conducted intensive research, and as a result, when commercially available high-purity silicon carbide powder, particularly β-type silicon carbide powder, is treated with a mineral acid heated under pressure, particularly heated hydrofluoric acid. It has been found that the iron component to be extracted can be easily removed to the nanogram level, and even when used as an anti-fusing buffer, the silicon wafer is not contaminated. Further, it has been found that the silicon carbide powder does not damage the silicon wafer. Based on these findings, the present invention has been completed. That is,
[0004]
An object of this invention is to provide the high purity silicon carbide powder useful as a raw material of the member for semiconductor industries.
[0005]
Another object of the present invention is to provide a buffering agent for preventing fusion of a wafer made of the high-purity silicon carbide powder.
[0006]
Furthermore, an object of this invention is to provide the manufacturing method of the said high purity silicon carbide powder.
[0007]
[Means for Solving the Problems]
The present invention that achieves the above object provides a high-purity silicon carbide powder characterized in that the elution amount of an iron component eluted in 160 ° C. heated hydrofluoric acid is 10 nanograms or less per gram of silicon carbide powder, and The present invention relates to a method for producing the high purity silicon carbide powder.
[0008]
The high-purity silicon carbide powder of the present invention is an ultra-high-purity silicon carbide powder in which the amount of iron component eluted in 160 ° C. heated hydrofluoric acid is 10 nanograms or less per gram of silicon carbide powder as described above. . Even when the silicon carbide powder is used as a buffering agent for preventing wafer fusion and heated at a high temperature exceeding 1000 ° C., the iron component is released and the silicon wafer is not contaminated. The purity of the silicon carbide powder of the present invention is defined as the amount of iron component eluted in hydrofluoric acid heated under a pressure of 160 ° C. The iron component released during the heat treatment of the wafer exceeding 1000 ° C. It is based on the knowledge that it is similar to the iron component in the state extracted to hydrofluoric acid.
[0009]
The high-purity silicon carbide powder can be produced by adding a mineral acid to silicon carbide powder and heating it under pressure. Preferably, silicon carbide powder and hydrofluoric acid are introduced into a sealed container at room temperature, It is desirable to create a pressurized state by heating and holding at ℃. After cooling to room temperature, it is confirmed whether the iron component content extracted in hydrofluoric acid is 10 nanograms or less per gram of silicon carbide powder. The content of the extracted iron component can be measured by monitoring the iron component content in hydrofluoric acid. When the content of iron component in hydrofluoric acid exceeds 10 nanograms per gram of silicon carbide powder in the first manufacturing process, heat hydrofluoric acid treatment under pressure is eluted after replacing hydrofluoric acid. Repeat until the iron component content is 10 nanograms or less. A more preferable production method is a method in which 50% hydrofluoric acid is added at a rate of 5 ml per 1 g of silicon carbide powder. The manufacturing method is economical because the rinsing of impurities adhering to the silicon carbide powder and the treatment efficiency can be well balanced.
[0010]
The heating temperature in the production method of the present invention is preferably higher from the viewpoint of purification efficiency. A fluororesin container is suitable as a high-purity heat-resistant container, and the heating temperature is preferably 160 ° C., which is the heat resistance limit of the container, and the heating time is preferably 3 to 10 hours. If the heating time is less than 3 hours, the temperature in the container is not sufficiently uniform, and the extraction is not performed sufficiently. Moreover, the improvement of processing efficiency cannot be expected even if it exceeds 10 hours. By such heat treatment under pressure, the iron component in the silicon dioxide oxide film formed on the surface of the silicon carbide particles is easily eluted, and the wafer is not contaminated with the iron component during the heat treatment of the wafer.
[0011]
As the container used in the above production method, an autoclave that can withstand pressurization is conceivable. However, when hydrofluoric acid is heated to 160 ° C., the fluorine component volatilizes and the internal pressure of the container is increased, so a sealed container is sufficient. When silicon carbide powder and hydrofluoric acid are introduced into the sealed container and heated to 160 ° C., the container reaches approximately 1.5 atm. The silicon dioxide is vigorously etched and the contained iron component is sufficiently purified. A specific example of the sealed container is a double container in which a sealed container made of fluororesin is housed in a metal jacket such as stainless steel.
[0012]
In the production method of the present invention, high-purity silicon carbide powder having a maximum particle size of 150 μm or less and a bulk density of 1.2 g / cm 3 or less, preferably β-type silicon carbide powder is used. When the raw material for the silicon carbide powder is coarse, it is necessary to increase the number of treatments to make the extracted iron component 10 nanogram or less per gram of silicon carbide powder, so the maximum particle size is 150 μm. And Even in the case of a fine powder having a maximum particle size of 150 μm or less, in a strongly aggregated state where the bulk density exceeds 1.2 g / cm 3 , the iron component is not extracted well and the number of treatments increases. Examples of the silicon powder raw material include silicon carbide powder (trade name SCP-00) manufactured by Ibiden.
[0013]
Since the silicon carbide powder produced by the production method of the present invention has a high purity, it can be used not only as a buffer but also as a semiconductor product processing member by sintering.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in detail based on specific examples, but the present invention is not limited thereto.
[0015]
【Example】
Example 1
1 g of β-type crystal high-purity silicon carbide powder (IBIDEN Co., Ltd. SCP-00) was placed in a fluororesin container, 5 ml of 50% hydrofluoric acid was added, and a hermetically sealed lid was placed in a metal jacket. The high-purity silicon carbide powder is a silicon carbide powder having a maximum particle size of 140 μm or less and a bulk density of 1.01 g / cm 3 after passing through a 100-mesh sieve.
[0016]
The metal jacket was heated to 160 ° C., held for 4 hours, cooled to room temperature, and the iron component in the supernatant hydrofluoric acid was measured by atomic absorption spectrophotometry. The result was 1020 nanograms. The silicon carbide powder was taken out and washed twice with pure water, and 5 ml of hydrofluoric acid was newly added again and extracted by heating. The iron component extracted a second time was 20 nanograms. When the treatment was further repeated, the third time the quantitation limit of the atomic absorption spectrophotometry was 10 nanograms or less. The silicon carbide powder was taken out, washed with pure water, and dried in a clean oven to obtain high purity silicon carbide powder. When the silicon carbide powder was dispersed in small portions between 50 wafers having a diameter of 3 inches and stacked vertically and heat-treated, the buffering effect was good and the lifetime of the minority carrier was not deteriorated.
[0017]
Comparative Example 1
The silicon carbide powder produced in Example 1 was simply washed with pure water and dried, and was dispersed little by little between 50 wafers having a diameter of 3 inches in the same manner as in Example 1 and vertically stacked. As a result, there was no sticking between the wafers, but the lifetime of the minority carrier, which seems to be caused by contamination with iron components, was deteriorated.
[0018]
Comparative Example 2
Silicon carbide powder having an average particle size of 170 μm on a 100 mesh sieve was washed with hydrofluoric acid under pressure in the same manner as in Example 1. The bulk density of the silicon carbide powder was 1.4 g / cm 3 . The iron component extracted into hydrofluoric acid per 800 g of silicon carbide powder was 800 nanograms for the first time, 620 nanograms for the second time, 490 nanograms for the third time, and 490 nanograms for the fourth time. When used for preventing wafer sticking in the same manner as in Example 1, the lifetime deteriorated and the wafers were all out of specification.
[0019]
【The invention's effect】
The high-purity silicon carbide powder of the present invention has a very low iron component content and is useful as a raw material for various members used in the semiconductor industry. In particular, even when used as a buffering agent for preventing fusion during heat treatment of the wafer, the wafer is not contaminated with iron components. The high-purity silicon carbide powder can be easily manufactured by introducing silicon carbide powder and a mineral acid into a container and heating under pressure, and has high industrial value.
Claims (6)
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| JP17917597A JP4006716B2 (en) | 1997-06-20 | 1997-06-20 | High purity silicon carbide powder and method for producing the same |
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| Application Number | Priority Date | Filing Date | Title |
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| JP17917597A JP4006716B2 (en) | 1997-06-20 | 1997-06-20 | High purity silicon carbide powder and method for producing the same |
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| Publication Number | Publication Date |
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| JPH1111923A JPH1111923A (en) | 1999-01-19 |
| JP4006716B2 true JP4006716B2 (en) | 2007-11-14 |
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| WO2013027790A1 (en) | 2011-08-24 | 2013-02-28 | 太平洋セメント株式会社 | Silicon carbide powder and method for producing same |
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|---|---|---|---|---|
| KR101352661B1 (en) * | 2008-12-29 | 2014-01-16 | 그린, 트위드 오브 델라웨어, 인코포레이티드 | Crosslinkable fluorine-containing elastomer composition and molded article made of said composition |
| US9556073B2 (en) * | 2013-07-01 | 2017-01-31 | Dale Adams | Process for sintering silicon carbide |
| WO2015002968A1 (en) * | 2013-07-01 | 2015-01-08 | Dale Adams | Process for sintering silicon carbide |
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| JP2798684B2 (en) * | 1989-01-31 | 1998-09-17 | イビデン株式会社 | Purification method of silicon carbide powder |
| JPH0784351B2 (en) * | 1990-11-20 | 1995-09-13 | 旭硝子株式会社 | Semiconductor heat treatment apparatus, high-purity silicon carbide member for semiconductor heat treatment apparatus, and method for manufacturing the same |
| JP3934695B2 (en) * | 1995-05-31 | 2007-06-20 | 株式会社ブリヂストン | Method for producing high-purity silicon carbide powder for producing silicon carbide single crystal |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2013027790A1 (en) | 2011-08-24 | 2013-02-28 | 太平洋セメント株式会社 | Silicon carbide powder and method for producing same |
| US9382121B2 (en) | 2011-08-24 | 2016-07-05 | Taiheiyo Cement Corporation | Silicon carbide powder and method for producing same |
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| JPH1111923A (en) | 1999-01-19 |
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