JP2000103695A - Vapor phase growing of diamond thin film - Google Patents
Vapor phase growing of diamond thin filmInfo
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- JP2000103695A JP2000103695A JP10272749A JP27274998A JP2000103695A JP 2000103695 A JP2000103695 A JP 2000103695A JP 10272749 A JP10272749 A JP 10272749A JP 27274998 A JP27274998 A JP 27274998A JP 2000103695 A JP2000103695 A JP 2000103695A
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- Prior art keywords
- thin film
- diamond thin
- substrate surface
- hydrogen
- substrate
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- Crystals, And After-Treatments Of Crystals (AREA)
- Carbon And Carbon Compounds (AREA)
- Chemical Vapour Deposition (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、熱伝導率が非常に大き
く、バンドギャップが大きいことから高出力電子デバイ
ス，紫外域の発光デバイス，高温で動作可能なデバイス
の半導体材料として期待されているダイヤモンド薄膜を
製造する方法に関する。The present invention is expected to be used as a semiconductor material for high-power electronic devices, ultraviolet light-emitting devices, and devices that can operate at high temperatures because of its extremely high thermal conductivity and large band gap. The present invention relates to a method for producing a diamond thin film.
【０００２】[0002]
【従来の技術】ダイヤモンド薄膜は、低圧気相合成法，
ＧＳＭＢＥ（ガスソース分子線エピタキシ法）等で製造
されている。一般的な低圧気相合成法では、水素で希釈
したメタンを原料ガスとして使用し、マイクロ波，熱タ
ングステンフィラメント等で発生させたメタンラジカル
や原子状水素を基板表面に供給し、基板表面にダイヤモ
ンドを気相成長させている。メタンラジカルと共に供給
された原子状水素は、非ダイヤモンド成分に対してエッ
チング効果を示す。原子状水素によるエッチング速度
は、ダイヤモンドの成長速度に比較して格段に大きい。2. Description of the Related Art A diamond thin film is formed by a low pressure gas phase synthesis method,
It is manufactured by GSMBE (gas source molecular beam epitaxy method) or the like. In a general low-pressure gas-phase synthesis method, methane diluted with hydrogen is used as a source gas, and methane radicals and atomic hydrogen generated by microwaves, a hot tungsten filament or the like are supplied to the substrate surface, and diamond is deposited on the substrate surface. Is grown in vapor phase. Atomic hydrogen supplied with methane radicals has an etching effect on non-diamond components. The etching rate by atomic hydrogen is much higher than the growth rate of diamond.
【０００３】低圧合成法では、成長条件を最適化すると
き非常に高品質のダイヤモンド薄膜が得られるものの成
長速度が非常に遅い。たとえば、熱フィラメントＣＶＤ
法では数μｍ／時に過ぎない。また、異種基板上でダイ
ヤモンド単結晶膜がヘテロ成長せず、ｎ型不純物もドー
ピングもできないことから、電子デバイス用への展開も
疑問がもたれている。他方、ＧＳＭＢＥ法では、電子，
原子状水素等の粒子ビームにより表面反応が励起される
ので、粒子ビームが照射されている表面領域のみにおけ
るダイヤモンド薄膜の選択的な成長が期待できる。そこ
で、本発明者等は、高圧合成したＣ（００１）表面をも
つダイヤモンド基板上でメタンのみを熱分解しダイヤモ
ンド薄膜の成長可能性を調査したところ、原子状水素を
使用しなくても非ダイヤモンド成分がほとんど含まれな
いダイヤモンド薄膜が得られることを見出し、Ｔ．Ｎｉ
ｓｈｉｍｏｒｉ，Ｈ．Ｓａｋａｍｏｔｏ，Ｙ．Ｔａｋａ
ｋｕｗａ，Ｓ．Ｋｏｎｏ，Ｊｐｎ．Ｊ．Ａｐｐｌ．Ｐｈ
ｙｓ．３４，Ｌ１２９７（１９９５）で報告した。In the low-pressure synthesis method, a very high-quality diamond thin film can be obtained when optimizing the growth conditions, but the growth rate is very slow. For example, hot filament CVD
The method is only a few μm / hour. In addition, since a diamond single crystal film does not grow heterogeneously on a heterogeneous substrate and cannot be doped with an n-type impurity or doped, it is also questionable to develop it for electronic devices. On the other hand, in the GSMBE method, electrons,
Since a surface reaction is excited by a particle beam such as atomic hydrogen, selective growth of a diamond thin film only in the surface region irradiated with the particle beam can be expected. Thus, the present inventors investigated the feasibility of growing a diamond thin film by thermally decomposing only methane on a diamond substrate having a C (001) surface synthesized at a high pressure. Found that a diamond thin film containing almost no component was obtained. Ni
Shimori, H .; Sakamoto, Y .; Taka
kuwa, S .; Kono, Jpn. J. Appl. Ph
ys. 34, L1297 (1995).
【０００４】[0004]
【発明が解決しようとする課題】ＧＳＭＢＥ法によるダ
イヤモンド薄膜の成長速度は、数Å／時と非常に遅く、
熱フィラメントＣＶＤ法の約１／１００００でしかな
い。遅い成長速度は、１０００〜１３５０℃の成長温度
域において基板のほぼ全面が水素で覆われていることに
原因がある。水素は、加熱だけでは基板表面から効果的
に除去できず、しかもメタンの吸着係数に比較して約一
桁小さい脱離係数をもつ。したがって、水素脱離で生じ
た僅かな数の未結合手の位置でメタン吸着が生じ、非常
に小さな成長速度でダイヤモンド薄膜が堆積するものと
推察される。The growth rate of the diamond thin film by the GSMBE method is as very low as several Å / hour.
It is only about 1/10000 of the hot filament CVD method. The slow growth rate is caused by the fact that almost the entire surface of the substrate is covered with hydrogen in the growth temperature range of 1000 to 1350 ° C. Hydrogen cannot be effectively removed from the substrate surface by heating alone, and has a desorption coefficient that is about one order of magnitude smaller than the adsorption coefficient of methane. Therefore, it is presumed that methane adsorption occurs at a small number of dangling bonds generated by hydrogen desorption, and a diamond thin film is deposited at a very low growth rate.
【０００５】この前提に立つとき、基板表面から水素を
除去するとダイヤモンド薄膜の成長が促進されることが
予想される。実際、ダイヤモンド薄膜の成長表面に電子
線を照射すると、成長速度が約１０００倍程度になり、
成長速度が０．１μｍ／時オーダー程度に改善される
［Ｔ．Ｎｉｓｈｉｍｏｒｉ，Ｈ．Ｓａｋａｍｏｔｏ，
Ｙ．Ｔａｋａｋｕｗａ，Ｓ．Ｋｏｎｏ，Ｄｉａｍｏｎｄ
Ｒｅｌａｔ．Ｍａｔｅｒ．６，４６３（１９９
７）］。しかし、基板表面の水素を除去するとき非ダイ
ヤモンド成分の析出も促進され、アモルファスカーボン
が成長膜に混入し、高品位のダイヤモンド薄膜が得られ
ない。[0005] Under this assumption, it is expected that removing hydrogen from the substrate surface will promote the growth of the diamond thin film. In fact, when the growth surface of the diamond thin film is irradiated with an electron beam, the growth rate becomes about 1000 times,
The growth rate is improved to the order of 0.1 μm / hour [T. Nishimori, H .; Sakamoto,
Y. Takakuwa, S .; Kono, Diamond
Relat. Mater. 6,463 (199
7)]. However, when hydrogen on the substrate surface is removed, precipitation of non-diamond components is also promoted, and amorphous carbon is mixed into the grown film, so that a high-quality diamond thin film cannot be obtained.
【０００６】[0006]
【課題を解決するための手段】本発明は、このような問
題を解消すべく案出されたものであり、ダイヤモンド成
長表面を電磁波で照射すると共に、基板に負のバイアス
電圧を印加して負性電子親和力による電子を加速させる
ことにより、成長表面近傍の炭素源ガス及び水素ガス源
を電子衝撃励起して局所プラズマを発生させ、高品位の
ダイヤモンド薄膜を高速で成長させることを目的とす
る。本発明のダイヤモンド薄膜成長法は、その目的を達
成するため、真空雰囲気に保持された基板表面を負性電
子親和状態に維持し、炭素源ガス及び水素ガスを基板表
面に供給しながら基板表面を電磁波で照射し、基板に負
のバイアス電圧を印加することにより基板表面からの負
性親和力による電子を加速し、基板表面近傍の炭素源ガ
ス及び水素ガスを電子衝撃励起し、吸着水素が除去され
た基板表面にダイヤモンド薄膜を成長させることを特徴
とする。SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem. The present invention irradiates a diamond growth surface with an electromagnetic wave, and applies a negative bias voltage to a substrate to produce a negative voltage. An object of the present invention is to accelerate local electrons by accelerating electrons due to ionic electron affinity to excite a carbon source gas and a hydrogen gas source near the growth surface to generate local plasma and grow a high-quality diamond thin film at high speed. In order to achieve the object, the diamond thin film growth method of the present invention maintains the surface of a substrate held in a vacuum atmosphere in a negative electron affinity state, and cleans the substrate surface while supplying a carbon source gas and a hydrogen gas to the substrate surface. By irradiating with electromagnetic waves and applying a negative bias voltage to the substrate, electrons with a negative affinity from the substrate surface are accelerated, and the carbon source gas and hydrogen gas near the substrate surface are excited by electron impact to remove adsorbed hydrogen. A diamond thin film is grown on the substrate surface.
【０００７】[0007]
【作用】本発明においては、低温低圧でダイヤモンド結
晶を基板上で気相成長させる。ダイヤモンド薄膜を成長
させる基板を真空紫外線，軟Ｘ線等の電磁波を照射して
電子励起すると共に、負のバイアス電圧を基板に印加す
る。水素吸着によってダイヤモンド薄膜表面の電子状態
がＮＥＡ（負性電子親和力）状態になっている基板に負
のバイアス電圧を印加すると、基板表面からの負性親和
力による電子が加速される。ＮＥＡとは、真空準位が伝
導帯の底よりも低いエネルギーに位置するため、価電子
帯や内殻準位から励起されて伝導帯の底に溜まった二次
電子がポテンシャルの障壁無しに容易に表面から飛び出
すことができる表面状態をいう。逆に、真空準位が伝導
帯の底よりもエネルギー的に高いと、二次電子の放出が
著しく減少する。ダイヤモンド薄膜表面のＮＥＡは、水
素吸着によって引き起こされ、Ａｒプラズマ，電子照射
等で表面水素が除去されると、ＰＥＡ（正の電子親和
力）に変わる。According to the present invention, a diamond crystal is vapor-phase grown on a substrate at a low temperature and a low pressure. The substrate on which the diamond thin film is grown is irradiated with electromagnetic waves such as vacuum ultraviolet rays and soft X-rays to excite the substrate electronically and apply a negative bias voltage to the substrate. When a negative bias voltage is applied to a substrate whose electron state on the diamond thin film surface is in a NEA (negative electron affinity) state due to hydrogen adsorption, electrons from the substrate surface due to the negative affinity are accelerated. With NEA, the vacuum level is located at an energy lower than the bottom of the conduction band, so that the secondary electrons excited at the bottom of the conduction band by being excited from the valence band or the core level can be easily formed without a potential barrier. Refers to the surface state that can jump out of the surface. Conversely, if the vacuum level is energetically higher than the bottom of the conduction band, the emission of secondary electrons is significantly reduced. NEA on the surface of the diamond thin film is caused by hydrogen adsorption, and changes to PEA (positive electron affinity) when surface hydrogen is removed by Ar plasma, electron irradiation, or the like.
【０００８】ＧＳＭＢＥ法でダイヤモンド薄膜を成長さ
せるとき、成長用基板の表面はほとんど吸着水素で覆わ
れている。吸着水素は、従来のＧＳＭＢＥ法ではダイヤ
モンド薄膜の成長速度を遅くする原因と考えられてい
る。他方、原子状水素は、非ダイヤモンド成分の析出を
抑制しながらダイヤモンド薄膜の成長を促進させるた
め、基板表面に供給する必要がある。本発明において
は、電磁波照射及び負バイアス電圧の印加を併用するこ
とにより、成長中のダイヤモンド薄膜表面からの電子放
出を加速させ、放出電子を用いて水素を電子衝撃で解離
することによりダイヤモンド薄膜の成長促進に有効な原
子状水素を得ている。[0008] When a diamond thin film is grown by the GSMBE method, the surface of the growth substrate is almost covered with adsorbed hydrogen. The adsorbed hydrogen is considered to be a cause of slowing down the growth rate of the diamond thin film in the conventional GSMBE method. On the other hand, atomic hydrogen needs to be supplied to the substrate surface in order to promote the growth of a diamond thin film while suppressing the precipitation of non-diamond components. In the present invention, the combined use of electromagnetic wave irradiation and the application of a negative bias voltage accelerates electron emission from the surface of the growing diamond thin film, and dissociates hydrogen by electron impact using the emitted electrons to form the diamond thin film. Atomic hydrogen effective for promoting growth is obtained.
【０００９】ＮＥＡによる電子放出は基板表面の極近傍
（基板表面から数μｍ〜数ｍｍ）に限られており、この
状態で基板表面を電磁波で照射すると、図１のモデルに
示すようにラジカル，イオン等からなる局所プラズマが
発生する。このとき、負のバイアス電圧が基板に印加さ
れているので、局所プラズマ中の正イオンも加速されて
基板表面に衝突する。これによっても電子励起が生じ、
基板から放出される電子が増加する。The electron emission by the NEA is limited to the vicinity of the substrate surface (several μm to several mm from the substrate surface). In this state, when the substrate surface is irradiated with an electromagnetic wave, radicals, as shown in the model of FIG. Local plasma composed of ions and the like is generated. At this time, since the negative bias voltage is applied to the substrate, the positive ions in the local plasma are also accelerated and collide with the substrate surface. This also causes electronic excitation,
The electrons emitted from the substrate increase.
【００１０】局所プラズマの励起には、気相中での吸収
が少ない真空紫外線，Ｃ１ｓ内殻電子を励起する軟Ｘ線
等が使用される。ダイヤモンドのエネルギーバンドギャ
ップの５．５ｅＶ以上の電磁波を照射すると、電子が伝
導帯に励起される。このとき、ダイヤモンド表面がＮＥ
Ａ状態に維持されていると、伝導帯に励起された電子が
効率よくダイヤモンド表面から放出される。なかでも、
ダイヤモンドの伝導帯への電子の励起は、１０〜４０ｅ
Ｖのエネルギーをもつ真空紫外線領域，３００〜５００
ｅＶの軟Ｘ線領域で高い効率が得られる。また、後述す
るイオンによる効果を考慮すると、５．５ｅＶ以上のエ
ネルギーをもつ電磁波は全て利用可能である。これら電
磁波の照射によってダイヤモンド表面から水素を直接除
去し、メタンを解離させることも原理的には可能である
が、ＮＥＡによる電子を用いて局所プラズマを発生させ
る方が水素除去及びメタン解離の効率が桁違いに上昇す
る。励起光源としては、局所プラズマ中の正イオンが基
板表面に衝突することによりダイヤモンド成長反応の励
起に正のフィードバックがかかるため、比較的小さな出
力源も使用可能である。For excitation of the local plasma, vacuum ultraviolet rays which absorb little in the gas phase, soft X-rays for exciting C1s core electrons, and the like are used. When diamond is irradiated with an electromagnetic wave having an energy band gap of 5.5 eV or more, electrons are excited to the conduction band. At this time, the diamond surface is NE
When maintained in the A state, electrons excited in the conduction band are efficiently emitted from the diamond surface. Above all,
Excitation of electrons into the conduction band of diamond is 10-40 e
Vacuum ultraviolet region with V energy, 300-500
High efficiency is obtained in the soft X-ray region of eV. Further, in consideration of the effect of ions described later, all electromagnetic waves having energy of 5.5 eV or more can be used. In principle, it is possible to dissociate methane by removing hydrogen directly from the diamond surface by irradiating these electromagnetic waves, but it is more efficient to generate local plasma using NEA electrons to remove hydrogen and dissociate methane. It rises by orders of magnitude. As the excitation light source, a relatively small output source can be used because positive ions in local plasma collide with the substrate surface and thus positive feedback is applied to the excitation of the diamond growth reaction.
【００１１】基板表面からダイヤモンド薄膜の成長に必
要な原子状水素を得ているため、従来法から窺い知れな
い作用・効果が発現する。まず、基板表面近傍でより高
濃度の原子状水素が生成されるため、原子状水素が効率
よく表面反応に利用される。熱タングステンフィラメン
トＣＶＤ法にみられるように電子放出源から発生する不
純物による悪影響がないので、高品位のダイヤモンド薄
膜が得られる。また、基板に印加される負バイアス電圧
でＮＥＡによる放出電子のエネルギーを制御できるた
め、水素の運動エネルギーを電子衝撃解離可能な数十ｅ
Ｖに調節できる。しかも、基板バイアスが小さいため、
中性の原子状水素と同時に生じる水素イオンが基板表面
に衝突するときの加速エネルギーも小さくなり、ダイヤ
モンド薄膜の成長面に与える損傷も抑制される。更に
は、原子状水素の発生が表面近傍に限られているので、
真空壁に向けて飛翔する原子状水素があったとしても、
途中でメタンや水素との衝突を繰り返して消滅するた
め、真空槽の槽壁から放出される不純物がない。Since the atomic hydrogen necessary for growing the diamond thin film is obtained from the substrate surface, an action and an effect which cannot be seen from the conventional method are exhibited. First, since a higher concentration of atomic hydrogen is generated in the vicinity of the substrate surface, the atomic hydrogen is efficiently used for the surface reaction. Since there is no adverse effect due to impurities generated from the electron emission source as seen in the hot tungsten filament CVD method, a high-quality diamond thin film can be obtained. In addition, since the energy of the electrons emitted by the NEA can be controlled by the negative bias voltage applied to the substrate, the kinetic energy of hydrogen is reduced to several tens of electrons capable of electron impact dissociation.
V can be adjusted. Moreover, since the substrate bias is small,
Acceleration energy when hydrogen ions generated simultaneously with neutral atomic hydrogen collides with the substrate surface is also reduced, and damage to the growth surface of the diamond thin film is suppressed. Furthermore, since the generation of atomic hydrogen is limited to near the surface,
Even if there is atomic hydrogen flying toward the vacuum wall,
There is no impurity released from the tank wall of the vacuum tank because the collision with methane and hydrogen disappears repeatedly on the way.
【００１２】ＮＥＡによる電子放出を成長励起に利用す
ることは、薄膜の多結晶化を抑え、（００１）面の単結
晶膜を優先的に成長させる原因ともなる。すなわち、Ｎ
ＥＡによる電子放出をしやすい結晶面がより成長励起さ
れ優先的に成長するため、結晶面の揃ったダイヤモンド
薄膜が得られる。電磁波照射及び負バイアス電圧の併用
は、ＮＥＡによる放出電子の密度及び運動エネルギーの
独立制御を可能にする。具体的には、基板表面の照射光
強度で放出電子密度が制御され、基板に印加する負バイ
アス電圧で運動エネルギーが制御される。したがって、
数十ｅＶの運動エネルギーをもつＮＥＡ電子を用い、メ
タン等の炭素源を効率よく電子衝撃解離させ、生成した
メタンラジカルやイオンが効率よく供給されるため、ダ
イヤモンド薄膜の成長速度が飛躍的に上昇する。Utilization of electron emission by NEA for growth excitation suppresses polycrystallization of a thin film and causes preferential growth of a (001) plane single crystal film. That is, N
Since the crystal plane that facilitates electron emission by the EA is more excited to grow and grow preferentially, a diamond thin film having a uniform crystal plane can be obtained. The combined use of electromagnetic radiation and a negative bias voltage allows independent control of the density and kinetic energy of the emitted electrons by the NEA. Specifically, the density of emitted electrons is controlled by the intensity of irradiation light on the substrate surface, and the kinetic energy is controlled by a negative bias voltage applied to the substrate. Therefore,
Using NEA electrons with kinetic energy of several tens of eV, the carbon source such as methane is efficiently dissociated by electron impact, and the generated methane radicals and ions are efficiently supplied, so that the growth rate of the diamond thin film is dramatically increased. I do.
【００１３】基板には、ダイヤモンド基板を始め、Ｓｉ
を代表とする電子デバイス用の基板や金属基板を使用で
きる。基板は、真空度１０-7〜１０-8Ｐａに維持された
真空槽にセットされ、−１０〜−４０Ｖの負バイアス電
圧が印加され、８００〜１０００℃の温度に保持され
る。負バイアス電圧の印加によりＮＥＡ状態になった基
板表面に、メタン，エタン等の炭化水素，メタノール，
エタノール等のアルコール，一酸化炭素等の炭素ガス源
及び水素ガスを１〜１０3 Ｐａのガス圧で供給し、真空
紫外線，軟Ｘ線等の電磁波を照射すると、図１のモデル
に示すように局所プラズマが発生する。これにより、十
分な量の原子状水素が基板表面に供給され、１〜１００
μｍ／時と従来法に比較して格段に高い成長速度でダイ
ヤモンド薄膜が基板表面に成長する。しかも、得られる
ダイヤモンド薄膜は、電子放出源からの不純物発生がほ
とんどないため、極めて高品位の薄膜になる。また、ダ
イヤモンド基板以外にＳｉ，酸化物，金属等を基板とし
て使用し、ダイヤモンド薄膜をヘテロ成長させることが
できる。The substrate includes a diamond substrate and a Si substrate.
A substrate for an electronic device or a metal substrate as a representative can be used. The substrate is set in a vacuum chamber maintained at a degree of vacuum of 10 -7 to 10 -8 Pa, a negative bias voltage of -10 to -40 V is applied, and the temperature is maintained at 800 to 1000C. A hydrocarbon such as methane or ethane, methanol,
When an alcohol such as ethanol, a carbon gas source such as carbon monoxide, and a hydrogen gas are supplied at a gas pressure of 1 to 10 3 Pa and irradiated with electromagnetic waves such as vacuum ultraviolet rays and soft X-rays, as shown in the model of FIG. Local plasma is generated. As a result, a sufficient amount of atomic hydrogen is supplied to the substrate surface, and 1 to 100
A diamond thin film grows on the substrate surface at a rate of μm / hour, which is much higher than the conventional method. In addition, the resulting diamond thin film has very little impurity generation from the electron emission source, and thus has a very high quality thin film. In addition, a diamond thin film can be hetero-grown by using Si, oxide, metal or the like as a substrate other than the diamond substrate.
【００１４】また、ＧＳＭＢＥ法を採用した本発明で
は、ｎ型及びｐ型ドーパントの添加も容易である。電気
伝導率の高いダイヤモンド薄膜を作製する場合には、ｎ
型又はｐ型のドーパントを製膜時に原料ガスの水素で希
釈して成長槽に導入する。ｎ型ドーピング材としてはト
リブチル燐，トリメチル燐等の有機燐化合物等，ｐ型ド
ーピング剤としてはジボラン（Ｂ2 Ｈ6 ）等が使用され
る。本発明法では、ダイヤモンド表面における成長反応
を直接制御しているので、高濃度にドーパントが導入さ
れる。しかも、ダイヤモンド膜中の欠陥が少なく、特性
に悪影響を及ぼす不純物も少ないため、電気伝導率が１
０（Ωｃｍ）-1以上の高い電気伝導率を示す薄膜となる
ため、ｐ−ｎ接合，ｐ−ｎ−ｐ接合，ｐ−ｉ−ｎ接合等
をもつダイオード，トランジスタ等の半導体デバイスも
作製される。In the present invention employing the GSMBE method, addition of n-type and p-type dopants is also easy. When producing a diamond thin film having high electric conductivity, n
The p-type or p-type dopant is diluted with hydrogen as a source gas during film formation and introduced into a growth tank. Organic phosphorus compounds such as tributyl phosphorus and trimethyl phosphorus are used as the n-type doping material, and diborane (B 2 H 6 ) is used as the p-type doping agent. In the method of the present invention, since the growth reaction on the diamond surface is directly controlled, the dopant is introduced at a high concentration. In addition, since the number of defects in the diamond film is small and the number of impurities that adversely affect the characteristics is small, the electric conductivity is one.
Semiconductor devices such as diodes and transistors having a pn junction, a pnp junction, a pin junction, and the like are also manufactured because the thin film exhibits a high electrical conductivity of 0 (Ωcm) −1 or more. You.
【００１５】[0015]
【実施例】到達真空度３×１０-8Ｐａの真空槽に高圧合
成のＣ( ００１) 表面をもつダイヤモンド基板を配置
し、８００℃に保持した。共に純度９９．９９９９９％
の高純度メタン及び高純度水素を炭素源及び水素源とし
て真空槽に導入し、原料ガス圧力をＰH2＝５０Ｐａ，Ｐ
CH4 ＝１Ｐａに維持した。基板に−２０Ｖのバイアス電
圧を印加しながら、ヘリウム放電ランプから出射された
２１．２ｅＶのＨｅ−Ｉ共鳴線で基板表面を照射した。
高純度メタンの分解によって生じたＣが水素除去された
基板表面に析出し、成長速度１０μｍ／時でダイヤモン
ド薄膜が基板表面に成長した。得られたダイヤモンド薄
膜は、膜厚が１００μｍであり、不純物が極めて少なく
欠陥のない薄膜であった。EXAMPLE A high-pressure synthesized diamond substrate having a C (001) surface was placed in a vacuum chamber having an ultimate vacuum of 3 × 10 -8 Pa, and kept at 800 ° C. Both are 99.99999% pure
High-purity methane and high-purity hydrogen are introduced into a vacuum chamber as a carbon source and a hydrogen source, and the source gas pressure is P H2 = 50 Pa, P
CH4 was maintained at 1 Pa. The substrate surface was irradiated with a 21.2 eV He-I resonance line emitted from a helium discharge lamp while applying a bias voltage of −20 V to the substrate.
C generated by the decomposition of high-purity methane was deposited on the substrate surface from which hydrogen had been removed, and a diamond thin film grew on the substrate surface at a growth rate of 10 μm / hour. The resulting diamond thin film had a thickness of 100 μm and had very few impurities and was free from defects.
【００１６】[0016]
【発明の効果】以上に説明したように、本発明において
は、ＮＥＡ状態の基板表面から放出される電子を負性バ
イアス電圧の印加によって加速させ、基板表面に供給さ
れた炭素源ガス及び水素ガスを電子衝撃励起することに
より局所プラズマを発生させている。その結果、基板表
面に吸着している水素が原子状水素によって効果的に除
去されてダイヤモンド核の生成を促進させ、従来法に比
較して格段に早い成長速度でダイヤモンド薄膜が成長す
る。しかも、不純物の混入がないため、高品質のダイヤ
モンド薄膜が得られる。このようにして得られたダイヤ
モンド薄膜は、ダイヤモンド本来の極めて大きな熱伝導
率及びバンドギャップを活用し大出力デバイス，高温動
作可能なデバイス等の材料として使用される。また、ダ
イヤモンド表面が水素吸着によってＮＥＡ状態になるこ
とを利用し、高効率の電子放出源としても期待できる。As described above, in the present invention, the electrons emitted from the substrate surface in the NEA state are accelerated by applying a negative bias voltage, and the carbon source gas and the hydrogen gas supplied to the substrate surface are accelerated. Is excited by electron impact to generate local plasma. As a result, the hydrogen adsorbed on the substrate surface is effectively removed by the atomic hydrogen to promote the generation of diamond nuclei, and the diamond thin film grows at a much higher growth rate than the conventional method. In addition, since no impurities are mixed, a high-quality diamond thin film can be obtained. The diamond thin film thus obtained is used as a material for a high-output device, a device capable of operating at high temperatures, and the like, utilizing the extremely large thermal conductivity and band gap inherent to diamond. Further, by utilizing the fact that the diamond surface is brought into the NEA state by hydrogen adsorption, it can be expected as a highly efficient electron emission source.
【図１】 本発明に従ってダイヤモンド薄膜が基板表面
に成長することを示すモデルFIG. 1 is a model showing that a diamond thin film grows on a substrate surface according to the present invention.
Claims (3)
電子親和状態に維持し、炭素源ガス及び水素ガスを基板
表面に供給しながら基板表面を電磁波で照射し、基板に
負のバイアス電圧を印加することにより基板表面からの
負性親和力による電子を加速し、基板表面近傍の炭素源
ガス及び水素ガスを電子衝撃励起し、吸着水素が除去さ
れた基板表面にダイヤモンド薄膜を成長させることを特
徴とするダイヤモンド薄膜の気相成長法。1. A substrate surface maintained in a vacuum atmosphere is maintained in a negative electron affinity state, the substrate surface is irradiated with an electromagnetic wave while supplying a carbon source gas and a hydrogen gas to the substrate surface, and a negative bias voltage is applied to the substrate. Is applied to accelerate the electrons due to negative affinity from the substrate surface, excite the carbon source gas and hydrogen gas near the substrate surface by electron impact, and grow a diamond thin film on the substrate surface from which adsorbed hydrogen has been removed. Characteristic vapor phase growth method of diamond thin film.
モンド薄膜。2. A diamond thin film produced by the method according to claim 1.
層及びｎ型層を備えたダイヤモンド薄膜からなる半導体
デバイス。3. A semiconductor device comprising a diamond thin film having a p-type layer and an n-type layer having an electric conductivity of 10 (Ωcm) −1 or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27274998A JP3642385B2 (en) | 1998-09-28 | 1998-09-28 | Vapor growth of diamond thin films. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27274998A JP3642385B2 (en) | 1998-09-28 | 1998-09-28 | Vapor growth of diamond thin films. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000103695A true JP2000103695A (en) | 2000-04-11 |
| JP3642385B2 JP3642385B2 (en) | 2005-04-27 |
Family
ID=17518231
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP27274998A Expired - Fee Related JP3642385B2 (en) | 1998-09-28 | 1998-09-28 | Vapor growth of diamond thin films. |
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| Country | Link |
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| JP (1) | JP3642385B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007173479A (en) * | 2005-12-21 | 2007-07-05 | National Institute Of Advanced Industrial & Technology | High quality synthetic diamond film, its manufacturing method, and its application |
-
1998
- 1998-09-28 JP JP27274998A patent/JP3642385B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007173479A (en) * | 2005-12-21 | 2007-07-05 | National Institute Of Advanced Industrial & Technology | High quality synthetic diamond film, its manufacturing method, and its application |
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| Publication number | Publication date |
|---|---|
| JP3642385B2 (en) | 2005-04-27 |
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