JP4986131B2 - Diamond single crystal substrate and manufacturing method thereof - Google Patents
Diamond single crystal substrate and manufacturing method thereof Download PDFInfo
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- JP4986131B2 JP4986131B2 JP2007013858A JP2007013858A JP4986131B2 JP 4986131 B2 JP4986131 B2 JP 4986131B2 JP 2007013858 A JP2007013858 A JP 2007013858A JP 2007013858 A JP2007013858 A JP 2007013858A JP 4986131 B2 JP4986131 B2 JP 4986131B2
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- 239000013078 crystal Substances 0.000 title claims description 73
- 239000000758 substrate Substances 0.000 title claims description 73
- 239000010432 diamond Substances 0.000 title claims description 53
- 229910003460 diamond Inorganic materials 0.000 title claims description 51
- 238000004519 manufacturing process Methods 0.000 title claims description 24
- 229910052757 nitrogen Inorganic materials 0.000 claims description 49
- 125000004433 nitrogen atom Chemical group N* 0.000 claims description 40
- 230000015572 biosynthetic process Effects 0.000 claims description 39
- 239000007789 gas Substances 0.000 claims description 16
- 238000001004 secondary ion mass spectrometry Methods 0.000 claims description 15
- 125000004432 carbon atom Chemical group C* 0.000 claims description 14
- 238000001308 synthesis method Methods 0.000 claims description 10
- 239000012808 vapor phase Substances 0.000 claims description 10
- 238000003786 synthesis reaction Methods 0.000 claims description 5
- 239000012071 phase Substances 0.000 claims description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 40
- 239000004065 semiconductor Substances 0.000 description 22
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 12
- 229910001873 dinitrogen Inorganic materials 0.000 description 10
- 239000001257 hydrogen Substances 0.000 description 9
- 229910052739 hydrogen Inorganic materials 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 8
- 238000005259 measurement Methods 0.000 description 7
- 239000012535 impurity Substances 0.000 description 6
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000009832 plasma treatment Methods 0.000 description 3
- 238000001069 Raman spectroscopy Methods 0.000 description 2
- 150000001721 carbon Chemical group 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
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- Crystals, And After-Treatments Of Crystals (AREA)
- Chemical Vapour Deposition (AREA)
Description
本発明は、ダイヤモンド単結晶基板に関し、詳しくは、半導体用途にも使用できる高品質な単結晶を、短時間でコストを下げて製造する方法に関する。 The present invention relates to a diamond single crystal substrate, and more particularly to a method for producing a high-quality single crystal that can be used for semiconductor applications in a short time and at a low cost.
ダイヤモンドは高熱伝導率、高い電子・正孔移動度、高い絶縁破壊電界強度、低誘電損失、そして広いバンドギャップといった、半導体材料として他に類を見ない、優れた特性を数多く備えている。特に近年では、広いバンドギャップを活かした紫外発光素子や、優れた高周波特性を持つ電界効果トランジスタなどが開発されつつある。さらに、紫外から赤外領域にわたり透明であることから、光学部品材料としても有望である。 Diamond has many unique properties that are unparalleled as a semiconductor material, such as high thermal conductivity, high electron / hole mobility, high breakdown field strength, low dielectric loss, and wide band gap. In particular, in recent years, ultraviolet light emitting elements utilizing a wide band gap and field effect transistors having excellent high frequency characteristics are being developed. Furthermore, since it is transparent from the ultraviolet region to the infrared region, it is also promising as an optical component material.
ダイヤモンドを半導体として利用することを考えた場合、高品質の単結晶基板が必要となる。現在、ダイヤモンド単結晶は主に高温高圧合成法を用いて作製している。これは結晶性に優れ、物性上は半導体基板として利用可能であるが、得られる単結晶のサイズは１ｃｍ級までが限界となっている。そこで、気相合成法による単結晶のエピタキシャル成長させる条件が検討されており、さらには気相合成法により大面積の単結晶を製造する方法が検討されている。これまでのところ、ダイヤモンドをヘテロエピタキシャル成長により単結晶を得る方法は結晶欠陥が多く、光学用や半導体基板としては充分な品質ではない。 When considering using diamond as a semiconductor, a high-quality single crystal substrate is required. Currently, diamond single crystals are mainly produced using a high-temperature and high-pressure synthesis method. This is excellent in crystallinity and can be used as a semiconductor substrate in terms of physical properties, but the size of a single crystal obtained is limited to the 1 cm class. Therefore, conditions for epitaxial growth of a single crystal by a vapor phase synthesis method have been studied, and a method for producing a single crystal having a large area by a vapor phase synthesis method has been studied. So far, the method of obtaining a single crystal by heteroepitaxial growth of diamond has many crystal defects and is not of sufficient quality as an optical or semiconductor substrate.
特許文献１には複数の単結晶ダイヤモンドの方位を揃えて並べ、これの上にダイヤモンドを気相合成法により成長させることによりダイヤモンド単結晶を製造する方法が述べられている。
特許文献２では、１つ又は複数の層に窒素、ホウ素などの不純物を含有させて、成膜速度を落とすことなく特性を向上させたダイヤモンド単結晶を製造する方法が述べられている。また特許文献３では、窒素を含有させることで成膜速度を向上させられることが示されている。また特許文献４では窒素原子含有量が異なる層を積み重ねた構造が示されている。
Patent Document 1 describes a method for producing a diamond single crystal by aligning the orientations of a plurality of single crystal diamonds and growing diamond on the diamonds by a vapor phase synthesis method.
Patent Document 2 describes a method of manufacturing a diamond single crystal with improved characteristics without reducing the film formation rate by containing impurities such as nitrogen and boron in one or more layers. Patent Document 3 shows that the film formation rate can be improved by containing nitrogen. Patent Document 4 shows a structure in which layers having different nitrogen atom contents are stacked.
特許文献１のような従来技術で得られたダイヤモンド単結晶を半導体等へと利用するためには、大量の高圧高温合成ダイヤモンド単結晶基板が必要とされる。大量のダイヤモンド単結晶基板を高温高圧合成で用意するには、コストと時間がかかる。また、特許文献２の製造方法では成膜開始直後に成膜条件の制御、特に基板温度の制御が困難であり、多結晶が成長してしまうことがある。特許文献３では、成膜速度を向上することができるが、窒素不純物量が多く、半導体へ利用可能な基板にすることはできない。特許文献４の製造方法では、ダイヤモンド作成に時間がかかるために、製造コストが高くなってしまう。 In order to use the diamond single crystal obtained by the prior art as in Patent Document 1 for a semiconductor or the like, a large amount of high-pressure and high-temperature synthetic diamond single crystal substrate is required. It takes cost and time to prepare a large amount of diamond single crystal substrate by high-temperature and high-pressure synthesis. Further, in the manufacturing method of Patent Document 2, it is difficult to control the film forming conditions, particularly the substrate temperature, immediately after the start of film formation, and the polycrystal may grow. In Patent Document 3, the deposition rate can be improved, but the amount of nitrogen impurities is large, so that the substrate cannot be used for a semiconductor. In the manufacturing method of patent document 4, since it takes time to create diamond, the manufacturing cost is increased.
本発明者らは、上記課題を解決すべく鋭意検討を重ねた結果、成膜開始時の基板温度の不安定さにより成膜するダイヤモンドが多結晶化しやすくなるが、窒素原子を含有する導入ガスの添加量を増やすことで、多結晶化しない基板温度範囲を広げられることを見出し
、本発明を完成させた。すなわち、本発明は以下の構成を採用する。
As a result of intensive studies to solve the above problems, the inventors of the present invention are likely to polycrystallize diamond due to instability of the substrate temperature at the start of film formation, but the introduced gas containing nitrogen atoms The inventors have found that the substrate temperature range in which polycrystallization does not occur can be expanded by increasing the amount of addition of, and the present invention has been completed. That is, the present invention adopts the following configuration.
（１）ダイヤモンド単結晶基板において、気相合成法で得られる窒素原子含有量の異なる各層が１０μｍ以上の厚みを有する二以上の層からなり、少なくとも炭素原子に対する２次イオン質量分析法で測定した窒素原子含有量が０ｐｐｍ以上１０ｐｐｍ以下の層、及び５ｐｐｍ以上１００ｐｐｍ以下である層を有し、かつ前記０ｐｐｍ以上１０ｐｐｍ以下の層より前記５ｐｐｍ以上１００ｐｐｍ以下の層の方が窒素原子含有量が多いことを特徴とするダイヤモンド単結晶基板である。
（２）前記ダイヤモンド単結晶基板において、気相合成法で得られる窒素原子含有量の異なる各層が１０μｍ以上の厚みを有する三以上の層からなり、前記炭素原子に対する２次イオン質量分析法で測定した窒素原子含有量が０ｐｐｍ以上１０ｐｐｍ以下の層と、前記５ｐｐｍ以上１００ｐｐｍ以下の層の間に一層以上の層が形成されていることを特徴とする上記（１）に記載のダイヤモンド単結晶基板である。
(1) In a diamond single crystal substrate, each layer having a different nitrogen atom content obtained by a vapor phase synthesis method is composed of two or more layers having a thickness of 10 μm or more, and measured by secondary ion mass spectrometry for at least carbon atoms . It has a layer having a nitrogen atom content of 0 ppm to 10 ppm and a layer of 5 ppm to 100 ppm, and the layer of 5 ppm to 100 ppm has a higher nitrogen atom content than the layer of 0 ppm to 10 ppm. A diamond single crystal substrate characterized by the following.
(2) In the diamond single crystal substrate, each layer having different nitrogen atom contents obtained by a vapor phase synthesis method is composed of three or more layers having a thickness of 10 μm or more, and measured by secondary ion mass spectrometry for the carbon atoms. The diamond single crystal substrate according to (1) above, wherein one or more layers are formed between the layer having a nitrogen atom content of 0 ppm to 10 ppm and the layer of 5 ppm to 100 ppm. is there.
（３）製造時における導入ガスが、気相合成法で得られる炭素原子に対する２次イオン質量分析法で測定した窒素原子含有量が５〜１００ｐｐｍまたは０〜１０ｐｐｍの層のダイヤモンド層を成長させるのに必要な量の窒素原子を含んでおり、該窒素原子を含むガスの導入量を調整することで窒素原子含有量の異なるダイヤモンド単結晶層を製造することを特徴とする上記（１）又は（２）に記載のダイヤモンド単結晶基板の製造方法である。 (3) The introduced gas at the time of production grows a diamond layer having a nitrogen atom content of 5 to 100 ppm or 0 to 10 ppm measured by secondary ion mass spectrometry with respect to carbon atoms obtained by a gas phase synthesis method. (1) or (1) , wherein a diamond single crystal layer having a nitrogen atom content different from the nitrogen atom content is prepared by adjusting an introduction amount of a gas containing the nitrogen atom. The method for producing a diamond single crystal substrate according to 2) .
元になる単結晶基板（種基板）をＣＶＤ法で作製することで、大量の単結晶基板を準備することが可能となる。本発明では、この際窒素を含むガスを導入することで成膜速度を速くし、製造スピードを上げ製造コストを下げることができるとともに、特に成膜開始直後の、成長条件の制御が難しく多結晶化しやすいという問題を、窒素原子含有量を調整することで多結晶生成を防ぐことができる。更にその上に、窒素原子含有量を減らした層を持つことで、低コストで半導体用途にも使用可能な基板を得ることができる。 By manufacturing a single crystal substrate (seed substrate) as a base by a CVD method, a large amount of single crystal substrates can be prepared. In the present invention, by introducing nitrogen-containing gas at this time, the film forming speed can be increased, the manufacturing speed can be increased, and the manufacturing cost can be reduced. It is possible to prevent the formation of polycrystals by adjusting the nitrogen atom content of the problem of being easily converted. Furthermore, by having a layer with a reduced nitrogen atom content thereon, a substrate that can be used for semiconductor applications at low cost can be obtained.
本発明ではＣＶＤ法でダイヤモンド基板を作製することで、大量の単結晶基板の製造スピードを上げ、製造コストを下げることができる。また、特に成膜開始直後での多結晶生成を防ぐことができる。更にその上に、窒素添加量を減らした層を持つことで、低コストで半導体用途にも使用可能な基板を得ることも可能である。
本発明のダイヤモンド単結晶基板は半導体用途にも使用できる高品質な単結晶で、製作時には比較的安価で短時間に入手することが可能である。
In the present invention, by manufacturing a diamond substrate by a CVD method, the manufacturing speed of a large amount of single crystal substrates can be increased and the manufacturing cost can be reduced. In addition, it is possible to prevent the formation of polycrystals immediately after the start of film formation. Furthermore, it is possible to obtain a substrate that can be used for semiconductor applications at low cost by having a layer with a reduced amount of nitrogen added thereon.
The diamond single crystal substrate of the present invention is a high-quality single crystal that can be used for semiconductor applications, and can be obtained at a relatively low cost in a short time during manufacture.
以下、本発明を詳細に説明する。
本発明に係るダイヤモンド単結晶基板は、窒素原子含有量の異なる２つ以上の層からなり、少なくとも炭素原子に対する窒素原子含有量が０ｐｐｍ以上１０ｐｐｍ以下の層、及び５ｐｐｍ以上１００ｐｐｍ以下である層を有し、かつ０ｐｐｍ以上１０ｐｐｍ以下の層に比べ、５ｐｐｍ以上１００ｐｐｍ以下の層の方で窒素原子含有量が多く、これらの層が気相合成法で作られることを特徴とするダイヤモンド単結晶基板である。この場合の層とは種基板の面積を持ち１０μｍ以上の厚みを持つ部分を指し、同一層の製作時に導入する炭素に対する窒素を含んだガス量が±１０％以内のものとする。範囲内であれば、同一層内でも窒素原子含有量が変化しているものでも良い。図１は、本発明のダイヤモンド単結晶基板の典型的な構造の一例である。
Hereinafter, the present invention will be described in detail.
The diamond single crystal substrate according to the present invention comprises two or more layers having different nitrogen atom contents, and has at least a layer having a nitrogen atom content of 0 ppm to 10 ppm and a layer having a nitrogen atom content of 5 ppm to 100 ppm. In addition, the diamond single crystal substrate is characterized in that the nitrogen atom content is higher in the layer of 5 ppm or more and 100 ppm or less than the layer of 0 ppm or more and 10 ppm or less, and these layers are formed by a vapor phase synthesis method. . The layer in this case refers to a portion having the area of the seed substrate and having a thickness of 10 μm or more, and the amount of gas containing nitrogen relative to carbon introduced when manufacturing the same layer is within ± 10%. Within the range, the nitrogen atom content may be changed even in the same layer. FIG. 1 is an example of a typical structure of a diamond single crystal substrate of the present invention.
気相合成で作製したものと、その他の製法によるものとの判別は、水素原子の含有量の差で見ることができる。上記単結晶を得るためには、例えば高圧高温合成で作製した単結晶基板上に気相合成法により成長をさせる方法がある。この際、窒素を添加することで成膜速度を向上させるこができ、製造スピードが上がるとともに、コストも低減することができる。成膜開始時は、成長条件が変わりやすく特に基板温度が不安定となる。ダイヤモ
ンド成膜時の基板温度が、ダイヤモンド単結晶成長条件に比べ低くなる、もしくは高くなることによって多結晶化してしまう。ここで窒素添加量を増やすことで、多結晶化しない基板温度範囲を広げられることを見出した。これにより、初期層は５ｐｐｍ以上１００ｐｐｍ以下となる層が好ましい。窒素添加量が５ｐｐｍ以下では多結晶化しやすく、１００ｐｐｍ以上では不純物量が多くなりすぎ新たな多結晶化の原因となってしまう。
The distinction between those produced by vapor phase synthesis and those produced by other production methods can be seen by the difference in the hydrogen atom content. In order to obtain the single crystal, for example, there is a method of growing by a vapor phase synthesis method on a single crystal substrate produced by high-pressure and high-temperature synthesis. At this time, the film formation rate can be improved by adding nitrogen, the manufacturing speed can be increased, and the cost can be reduced. At the start of film formation, the growth conditions are likely to change, and in particular, the substrate temperature becomes unstable. When the substrate temperature at the time of diamond film formation becomes lower or higher than the diamond single crystal growth condition, polycrystallization occurs. Here, it has been found that by increasing the amount of nitrogen added, the substrate temperature range in which polycrystallization does not occur can be expanded. Thereby, the initial layer is preferably a layer having a concentration of 5 ppm to 100 ppm. If the amount of nitrogen added is 5 ppm or less, polycrystallization tends to occur, and if it is 100 ppm or more, the amount of impurities becomes too large, causing new polycrystallization.
この方法で作製した５ｐｐｍ以上１００ｐｐｍ以下の層上に、更にダイヤモンドを成膜することが可能である。この際、取り出せるダイヤモンド単結晶の厚み、枚数を増やすためには、成膜をつづける必要がある。前述したとおり、成膜開始時は基板温度が安定しないが、時間がたつにつれ基板温度は安定していく。そのため、段階的に、もしくは連続的に窒素添加量を変化させることで、多結晶化させず、更に成膜速度を落とさずに成膜することが可能である。この際、最終的には炭素原子に対する窒素原子含有量が０ｐｐｍ以上１０ｐｐｍ以下の層となるよう窒素添加量を調整することで、多結晶化させず、また成膜速度を落とさずに成膜が可能である。また図２に示す基板を半導体用途へ使用するためには、更にその上への成膜を行い、この場合意図する窒素添加を行わないようにする方法が好ましい。 A diamond film can be further formed on the layer of 5 ppm to 100 ppm produced by this method. At this time, in order to increase the thickness and number of diamond single crystals that can be taken out, it is necessary to continue film formation. As described above, the substrate temperature is not stable at the start of film formation, but the substrate temperature becomes stable with time. Therefore, by changing the amount of nitrogen added stepwise or continuously, it is possible to form a film without polycrystallization and without lowering the film formation rate. At this time, by adjusting the nitrogen addition amount so that the nitrogen atom content with respect to carbon atoms is finally in a layer of 0 ppm or more and 10 ppm or less, the film can be formed without polycrystallization and without reducing the film formation rate. Is possible. Further, in order to use the substrate shown in FIG. 2 for a semiconductor application, it is preferable to form a film thereon so that the intended addition of nitrogen is not performed.
前記ダイヤモンド単結晶基板において、窒素原子含有量の異なる３つ以上の層からなり、炭素原子に対する窒素原子含有量が０ｐｐｍ以上１０ｐｐｍ以下の層と５ｐｐｍ以上１００ｐｐｍ以下の層の間に一層以上の層があることが好ましい（図３）。５ｐｐｍ以上１００ｐｐｍ以下の層上に、更にダイヤモンドを成膜する場合に、導入窒素含有ガス量を更に増やすことで成膜速度を上げることが可能である。 The diamond single crystal substrate includes three or more layers having different nitrogen atom contents, and one or more layers are provided between a layer having a nitrogen atom content of 0 ppm to 10 ppm and a layer having a nitrogen atom content of 5 ppm to 100 ppm with respect to carbon atoms. There is preferably (FIG. 3). In the case where a diamond film is further formed on a layer of 5 ppm or more and 100 ppm or less, the film formation rate can be increased by further increasing the amount of introduced nitrogen-containing gas.
この方法で作製した基板は、切り出しを行うことで半導体用として使用することも可能であり、更に同様の工程を行うために高温高圧単結晶基板の代わりに使うことも可能である。この場合には５ｍｍ角といった比較的大型のサイズでも、大量に速く作ることが可能となる。
この方法で得たダイヤモンド単結晶は、Ｘ線ロッキングカーブの半値幅が１００秒以内またはラマン散乱スペクトルの半値幅が２ｃｍ−１という結晶性の良い単結晶を得ることができ、半導体用途への使用も可能である。
A substrate manufactured by this method can be used for a semiconductor by cutting out, and can also be used in place of a high-temperature high-pressure single crystal substrate to perform a similar process. In this case, even a relatively large size such as 5 mm square can be made quickly in large quantities.
The diamond single crystal obtained by this method can obtain a single crystal with good crystallinity having an X-ray rocking curve half-width within 100 seconds or a Raman scattering spectrum half-width of 2 cm −1 , and can be used for semiconductor applications. Is also possible.
［実施例１］
５ｍｍ×５ｍｍ、厚さ０．５ｍｍの人工Ｉｂ型単結晶｛１００｝基板を用意して、マイクロ波プラズマＣＶＤによるエピタキシャル成長を行った。基板温度は１１００℃、圧力９０ｔｏｒｒでおこなった。導入したガスはメタン２００ｓｃｃｍ（ｓｔａｎｄａｒｄ ｃｕｂｉｃ ｃｍ）、水素１０００ｓｃｃｍとした。
添加する窒素ガスは、成膜開始から２時間は１ｓｃｃｍとし、２時間後からは０．４ｓｃｃｍとした。計２０時間成膜を行った。このとき、平均成膜速度は５１μｍ／ｈとなった。成膜したダイヤモンド単結晶から、ＣＶＤで作製した部分から１ｍｍｔ厚みの単結晶を切り出した。ＳＩＭＳ（ｓｅｃｏｎｄａｒｙ ｉｏｎ ｍａｓｓ ｓｐｅｃｔｒｏｍｅｔｒｙ：２次イオン質量分析法）による炭素原子に対する窒素原子含有量の計測を行ったところ、上記人工Ｉｂ型単結晶基板に接していた部分から上２０μｍの位置では２０ｐｐｍとなっており、更にその上２００μｍの位置では４ｐｐｍとなっていた。同時に水素原子量も同様の位置で測定し、それぞれ１０ｐｐｍ、１５ｐｐｍ含有することを確認した。最表面についてＸ線回折測定、ラマン分光測定を行った結果、単結晶であることを確認した。
[Example 1]
An artificial Ib type single crystal {100} substrate having a size of 5 mm × 5 mm and a thickness of 0.5 mm was prepared, and epitaxial growth was performed by microwave plasma CVD. The substrate temperature was 1100 ° C. and the pressure was 90 torr. The introduced gas was methane 200 sccm (standard cubic cm) and hydrogen 1000 sccm.
The nitrogen gas to be added was 1 sccm for 2 hours from the start of film formation and 0.4 sccm after 2 hours. Film formation was performed for a total of 20 hours. At this time, the average film formation rate was 51 μm / h. From the formed diamond single crystal, a 1 mm thick single crystal was cut out from the portion produced by CVD. When the nitrogen atom content with respect to the carbon atom was measured by SIMS (secondary ion mass spectrometry), it became 20 ppm at a position 20 μm above the portion in contact with the artificial Ib type single crystal substrate. Furthermore, it was 4 ppm at the position of 200 μm. At the same time, the amount of hydrogen atoms was also measured at the same position and confirmed to contain 10 ppm and 15 ppm, respectively. As a result of X-ray diffraction measurement and Raman spectroscopic measurement on the outermost surface, it was confirmed to be a single crystal.
更に、この方法で作製した単結晶基板上にマイクロ波プラズマＣＶＤによるエピタキシャル成長を行った。基板温度は１１５０℃、圧力７０ｔｏｒｒでおこなった。導入したガ
スはメタン２０ｓｃｃｍ、水素１００ｓｃｃｍとした。この際に意図した窒素ガスの導入は行わなかった。１００時間の成膜を行った。
成膜後、基板について結晶性を評価した。まず半導体特性の評価として試料を水素プラズマ処理し、ホール測定によって水素化表面伝導層の常温における正孔移動度を評価した結果、１１００ｃｍ２／Ｖ・ｓｅｃと半導体基板として十分高速な値を得た。次に、二次イオン質量分析により結晶中の窒素不純物量を定量した結果、炭素原子に対して窒素原子量は１．２ｐｐｍと十分少ない値を得た。本実施例のダイヤモンド単結晶基板は大型かつ高品質であることを確認した。
Further, epitaxial growth by microwave plasma CVD was performed on the single crystal substrate manufactured by this method. The substrate temperature was 1150 ° C. and the pressure was 70 torr. The introduced gas was methane 20 sccm and hydrogen 100 sccm. At this time, the intended introduction of nitrogen gas was not performed. The film was formed for 100 hours.
After film formation, the crystallinity of the substrate was evaluated. Samples were hydrogen plasma treatment initially as an evaluation of the semiconductor characteristics, the results of evaluation of the hole mobility at normal temperature of the hydrogenated surface conduction layer by Hall measurement, to obtain a fast enough value as 1100cm 2 / V · sec and the semiconductor substrate . Next, as a result of quantifying the amount of nitrogen impurities in the crystal by secondary ion mass spectrometry, the amount of nitrogen atoms was sufficiently low at 1.2 ppm with respect to carbon atoms. The diamond single crystal substrate of this example was confirmed to be large and high quality.
［実施例２］
６ｍｍ×２ｍｍ、厚さ１．０ｍｍの人工Ｉｂ型単結晶｛１００｝基板を用意して、マイクロ波プラズマＣＶＤによるエピタキシャル成長を行った。基板温度は１０００℃、圧力７０ｔｏｒｒでおこなった。導入したガスはメタン１５０ｓｃｃｍ（ｓｔａｎｄａｒｄ ｃｕｂｉｃ ｃｍ）、水素１０００ｓｃｃｍとした。
添加する窒素ガスは、成膜開始から２時間は１ｓｃｃｍとし、２時間後からは０．４ｓｃｃｍとした。２０時間後からは添加する窒素ガスを０ｓｃｃｍとし（窒素ガスを導入せずに）、成膜を更に８０時間行った。この時、平均成膜速度は１８μｍ／ｈとなった。成膜したダイヤモンド単結晶から、ＣＶＤで作製した部分から１ｍｍｔ厚みの単結晶を切り出した。ＳＩＭＳによる炭素原子に対する窒素原子含有量の計測を行ったところ、上記人工Ｉｂ型単結晶基板に接していた部分から上２０μｍの位置では２０ｐｐｍとなっており、更にその上２００μｍの位置では４ｐｐｍとなっていた。最表面について半導体特性の評価として試料を水素プラズマ処理し、ホール測定によって水素化表面伝導層の常温における正孔移動度を評価した結果、１０００ｃｍ２／Ｖ・ｓｅｃと半導体基板として十分高速な値を得た。次に、二次イオン質量分析により結晶中の窒素不純物量を定量した結果、炭素原子に対して窒素原子量は１．２ｐｐｍと十分少ない値を得た。本実施例のダイヤモンド単結晶基板は大型かつ高品質であることを確認した。
[Example 2]
An artificial Ib type single crystal {100} substrate having a size of 6 mm × 2 mm and a thickness of 1.0 mm was prepared, and epitaxial growth was performed by microwave plasma CVD. The substrate temperature was 1000 ° C. and the pressure was 70 torr. The introduced gases were methane 150 sccm (standard cubic cm) and hydrogen 1000 sccm.
The nitrogen gas to be added was 1 sccm for 2 hours from the start of film formation and 0.4 sccm after 2 hours. After 20 hours, the nitrogen gas to be added was set to 0 sccm (without introducing nitrogen gas), and film formation was further performed for 80 hours. At this time, the average film formation rate was 18 μm / h. From the formed diamond single crystal, a 1 mm thick single crystal was cut out from the portion produced by CVD. When the nitrogen atom content with respect to carbon atoms was measured by SIMS, it was 20 ppm at the position 20 μm above the portion in contact with the artificial Ib type single crystal substrate, and further 4 ppm at the position 200 μm above it. It was. Samples were hydrogen plasma treatment as an evaluation of the semiconductor characteristics of the outermost surface, the result of evaluating the hole mobility at normal temperature of the hydrogenated surface conduction layer by Hall measurement, a sufficiently high speed value as 1000cm 2 / V · sec and the semiconductor substrate Obtained. Next, as a result of quantifying the amount of nitrogen impurities in the crystal by secondary ion mass spectrometry, the amount of nitrogen atoms was sufficiently low at 1.2 ppm with respect to carbon atoms. The diamond single crystal substrate of this example was confirmed to be large and high quality.
［実施例３］
６ｍｍ×３ｍｍ、厚さ０．７ｍｍの人工Ｉｂ型単結晶｛１００｝基板を用意して、マイクロ波プラズマＣＶＤによるエピタキシャル成長を行った。基板温度は１０５０℃、圧力７０ｔｏｒｒでおこなった。導入したガスはメタン２００ｓｃｃｍ（ｓｔａｎｄａｒｄ ｃｕｂｉｃ ｃｍ）、水素１０００ｓｃｃｍとした。
添加する窒素ガスは、成膜開始から２時間は１ｓｃｃｍとした。更にその後、連続的に２時間かけて０．３ｓｃｃｍまで減らすようにした。添加する窒素ガス量を減らし始めてから２時間後からは０．３ｓｃｃｍと一定とし、計２０時間成膜を行った。平均成膜速度は４８μｍ／ｈとなった。成膜したダイヤモンド単結晶からＣＶＤで作製した部分から０．５ｍｍｔ厚みの単結晶を切り出した。ＳＩＭＳによる炭素原子に対する窒素原子含有量の計測を行ったところ、１５ｐｐｍの層と３ｐｐｍの層が存在した。その間には、８ｐｐｍの層も見られた。
[Example 3]
An artificial Ib type single crystal {100} substrate having a size of 6 mm × 3 mm and a thickness of 0.7 mm was prepared, and epitaxial growth was performed by microwave plasma CVD. The substrate temperature was 1050 ° C. and the pressure was 70 torr. The introduced gas was methane 200 sccm (standard cubic cm) and hydrogen 1000 sccm.
The nitrogen gas to be added was 1 sccm for 2 hours from the start of film formation. After that, it was continuously reduced to 0.3 sccm over 2 hours. After 2 hours from the start of reducing the amount of nitrogen gas to be added, film formation was carried out for a total of 20 hours with a constant 0.3 sccm. The average film formation rate was 48 μm / h. A single crystal having a thickness of 0.5 mmt was cut out from a portion formed by CVD from the formed diamond single crystal. When the nitrogen atom content with respect to carbon atoms was measured by SIMS, a 15 ppm layer and a 3 ppm layer were present. In the meantime, an 8 ppm layer was also observed.
この方法で作製した単結晶基板の主面、側面研磨を行い、マイクロ波プラズマＣＶＤによるエピタキシャル成長を行った。基板温度は１１００℃、圧力５０ｔｏｒｒでおこなった。導入したガスはメタン１１０ｓｃｃｍ、水素９００ｓｃｃｍとした。この際に意図した窒素ガスの導入は行わなかった。成膜後、結晶性を評価した。まず半導体特性の評価として試料を水素プラズマ処理し、ホール測定によって水素化表面伝導層の常温における正孔移動度を評価した結果、１０００ｃｍ２／Ｖ・ｓｅｃと半導体基板として十分高速な値を得た。次に、二次イオン質量分析により結晶中の窒素不純物量を定量した結果、炭素原子に対して窒素原子量は１．１ｐｐｍと十分少ない値を得た。本実施例のダイヤモンド単結晶基板は大型かつ高品質であることを確認した。 The main surface and side surfaces of the single crystal substrate manufactured by this method were polished, and epitaxial growth was performed by microwave plasma CVD. The substrate temperature was 1100 ° C. and the pressure was 50 torr. The introduced gas was methane 110 sccm and hydrogen 900 sccm. At this time, the intended introduction of nitrogen gas was not performed. After film formation, crystallinity was evaluated. Samples were hydrogen plasma treatment initially as an evaluation of the semiconductor characteristics, the results of evaluation of the hole mobility at normal temperature of the hydrogenated surface conduction layer by Hall measurement, to obtain a fast enough value as 1000cm 2 / V · sec and the semiconductor substrate . Next, as a result of quantifying the amount of nitrogen impurities in the crystal by secondary ion mass spectrometry, the amount of nitrogen atoms was sufficiently low at 1.1 ppm with respect to carbon atoms. The diamond single crystal substrate of this example was confirmed to be large and high quality.
［実施例４］
実施例１と同様にし、５ｍｍ×５ｍｍ、厚さ０．５ｍｍの人工Ｉｂ型単結晶｛１００｝基板を用意して、マイクロ波プラズマＣＶＤによるエピタキシャル成長を行った。基板温度は１１００℃、圧力９０ｔｏｒｒでおこなった。導入したガスはメタン２００ｓｃｃｍ（ｓｔａｎｄａｒｄ ｃｕｂｉｃ ｃｍ）、水素１０００ｓｃｃｍとしたが、添加する窒素ガスは、成膜開始２時間は１ｓｃｃｍとし、２時間後から１２時間後までは１０ｓｃｃｍとし、その後更に２０時間後までは０．４ｓｃｃｍで成膜を行った。結果、平均成膜速度は７０μｍ／ｈと、実施例１の５１μｍ／ｈと比較して速くなった。
成膜後、結晶性を評価した。ＳＩＭＳによる炭素原子に対する窒素原子含有量の計測を行ったところ、上記人工Ｉｂ型単結晶基板に接していた部分から上２０μｍの位置では２０ｐｐｍとなっており、更にその上２００μｍの位置では４０ｐｐｍとなっていた。成膜後、最も上面だった部分より下側２０μｍの部分でも測定を行ったところ４ｐｐｍとなっていた。
[Example 4]
In the same manner as in Example 1, an artificial Ib type single crystal {100} substrate having a size of 5 mm × 5 mm and a thickness of 0.5 mm was prepared, and epitaxial growth was performed by microwave plasma CVD. The substrate temperature was 1100 ° C. and the pressure was 90 torr. The introduced gas was 200 sccm of methane (standard cubic cm) and 1000 sccm of hydrogen, but the nitrogen gas to be added was 1 sccm for 2 hours from the start of film formation, 10 sccm from 2 hours to 12 hours, and then 20 hours later. Until then, film formation was performed at 0.4 sccm. As a result, the average film formation rate was 70 μm / h, which was faster than 51 μm / h in Example 1.
After film formation, crystallinity was evaluated. When the nitrogen atom content with respect to carbon atoms was measured by SIMS, it was 20 ppm at a position 20 μm above the portion in contact with the artificial Ib type single crystal substrate, and further 40 ppm at a position 200 μm above that. It was. After the film formation, measurement was carried out even at a portion 20 μm below the uppermost portion, and it was 4 ppm.
［比較例１］
実施例１と同様の成膜方法で、添加窒素ガス量を以下の表の窒素原子含有量になるように調整して成膜した。作成した基板の人工単結晶部分を切り取り、その底面から２０μｍから４０μｍの領域を第一層とし、基板の上面５μｍから２５μｍの領域を第二層とした。
それぞれの成膜品について、ＳＩＭＳ測定によって炭素原子に対する窒素原子量を各層について測定した。作製した単結晶基板の最表面について、Ｘ線ロッキングカーブ測定を行った。結果の半値幅は以下の通りとなった。
[Comparative Example 1]
Film formation was performed by the same film formation method as in Example 1 so that the amount of added nitrogen gas was adjusted to the nitrogen atom content shown in the following table. The artificial single crystal portion of the prepared substrate was cut out, and a region from 20 μm to 40 μm from the bottom was used as the first layer, and a region from 5 μm to 25 μm from the top of the substrate was used as the second layer.
About each film-forming article, the amount of nitrogen atoms with respect to a carbon atom was measured about each layer by SIMS measurement. X-ray rocking curve measurement was performed on the outermost surface of the produced single crystal substrate. The half width of the result is as follows.
Ｎo.１〜２では成膜速度も速く、半導体用途へ使用可能な程度に良質な膜質であった。Ｎo.３，４では第１層作成段階で多結晶が生成してしまい、その後窒素導入量を減らして成膜した場合でも、多結晶は存在しつづけた。２０時間以上の成膜でも膜厚は厚くならなかった。Ｎo.５では、最終的に生成されたダイヤモンドの膜質が悪く、半導体基板への使用はできなかった。 In No. 1-2, the film formation rate was high, and the film quality was high enough to be used for semiconductor applications. In Nos. 3 and 4, polycrystals were produced in the first layer preparation stage, and polycrystals continued to exist even when the film was formed with a reduced amount of nitrogen introduced. Even when the film was formed for 20 hours or more, the film thickness did not increase. No. 5 could not be used for a semiconductor substrate because of the poor film quality of the finally produced diamond.
以上詳述したように、本発明のダイヤモンド単結晶基板は半導体用途にも使用できる高品質な単結晶で、製作時には比較的安価で短時間に入手することが可能である。 As described above in detail, the diamond single crystal substrate of the present invention is a high-quality single crystal that can be used for semiconductor applications, and can be obtained at a relatively low cost in a short time during manufacture.
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| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |