JP3735145B2 - Silicon carbide thin film and method for manufacturing the same - Google Patents

Description

【０００６】
このため、上記Si[110]方向への収縮は互いに直行する２方向に対してほぼ同じ確立で起こり、この異なる方向性を有する２種類のSiC結晶粒は互いに異なるフェーズを有する。異なるフェーズを有するSiC結晶粒は、成長によって互いに結合して一体になることが出来ず、界面にAPBを含む２フェーズの薄膜となってしまい問題であった。
【０００７】
本発明は、前記従来の問題を解決するため、Si基板表面にヘテロエピタキシャル成長させることにより、Siウェハ上に結晶欠陥の少ない単相の3C-SiC単結晶薄膜を形成する炭化珪素薄膜およびその製造方法を提供することを目的とする。
【０００８】
【課題を解決するための手段】
前記目的を達成するため、本発明の炭化珪素薄膜は、Ｓｉ基板表面に積層された炭化珪素結晶であって、炭化珪素３Ｃ−ＳｉＣ [ １１０ ] 方向に短く、上記３Ｃ−ＳｉＣ[１１０]方向と垂直な方向に長い異方性を有する炭化珪素結晶粒によって構成されており、上記Ｓｉ基板表面がＳｉ ( ００１ ) ｏｆｆ−ｃｕｔ面であり、Ｓｉ[１１０]方向に対して異方性を有するテラスとステップを含み、上記Ｓｉ基板のステップエッジ方向に垂直に近いＳｉ[１１０]方向に上記炭化珪素３Ｃ−ＳｉＣ[１１０]方向が一致するように、上記Ｓｉ ( ００１ ) 表面のＳｉ [ １１０ ] 原子列が炭素原子と反応して収縮した３Ｃ−ＳｉＣ ( ００１ )/ Ｓｉ ( ００１ ) 界面を有し、１００ｎｍ以上の膜厚で積層されていることを特徴とする。
【０００９】
本発明の炭化珪素薄膜の製造方法は、Ｓｉ[１１０]方向に対して異方性を有するテラスとステップを含むｏｆｆ−ｃｕｔしたＳｉ(００１)基板表面に、加熱し昇温中にＳｉ基板表面の温度が６００℃以下の段階で、炭素原子等の分子線を含む炭素源を供給し、前記Ｓｉ基板表面を１０５０℃まで加熱することにより表面を炭化させて炭化珪素を形成し、Ｓｉ ( ００１ ) 表面のステップエッジ方向に垂直に近いＳｉ [ １１０ ] 原子列が炭素原子と反応して収縮した３Ｃ−ＳｉＣ ( ００１ )/ Ｓｉ ( ００１ ) 界面を形成する第一のプロセスと、炭素と珪素を供給し、炭化珪素表面がＳｉターミネイト表面に過剰なＳｉ原子が付加している構造を成長表面として保持する第二のプロセスを含み、上記第二のプロセスにより成長する炭化珪素３Ｃ−ＳｉＣ [ １１０ ] 方向に短く、上記３Ｃ−ＳｉＣ[１１０]方向と垂直な方向に長い異方性を有する炭化珪素結晶粒を、上記Ｓｉ基板表面がＳｉ ( ００１ ) ｏｆｆ−ｃｕｔ面であり、上記Ｓｉ基板のステップエッジ方向に垂直に近いＳｉ[１１０]方向に上記炭化珪素３Ｃ−ＳｉＣ[１１０]方向が一致するように積層させて、成長させることを特徴とする。
【００１０】
前記構成においては、Ｓｉ基板表面のテラスの幅が５オングストローム（０．５ｎｍ）以上１０００オングストローム（１００ｎｍ）以下であることが好ましい。
【００１２】
前記した本発明において、炭化して炭化珪素を形成するSi基板の表面に異方性を付けてテラスとステップを導入することにより、従来の技術において問題であった２種類のフェーズを有する結晶粒の形成が、１つのフェーズの結晶粒に限定され、APBの形成が抑制される。
【００１３】
更に、炭化後に炭素とSiを供給して炭化珪素を成長させるプロセスにおいて、炭化珪素表面がSiターミネイト表面に過剰なSi原子が付加している構造を成長表面として保持している場合に、炭化珪素の成長容易軸が上記異方性を有するSi基板表面のテラスに沿う方向に対応することとなり、１種類のフェーズの結晶粒が選択的に成長し上記アンチフェーズバウンダリー (APB)の形成が更に抑制される。
【００１４】
更に、Si基板表面を加熱して炭化し炭化珪素を形成する時に供給する炭素源が、炭化水素等のガス状の物質だけではなく、少なくとも炭素原子等の分子線を含む場合にツウィンの形成が抑制される。
【００１５】
【発明の実施の形態】
本発明の異方性をつけてテラスとステップを導入したSi基板表面の模式図を図２に示す。Si(001)表面４が[110]方向に傾けてoff-cutされており、テラス５とステップ６が導入されている。テラスの幅（ステップエッジと垂直方向：図２中のN方向７）は、ステップエッジと平行（図２中のP方向８）なテラスの長さに比べて非常に短く、off-cut角度が４度でステップ６の高さが１原子層の場合は、20オングストローム程度である。この短く連なったSi[110]原子列（図２のN方向７）は、長く連なっている図２のP方向８のSi[110]原子列に比べて、炭素と反応して収縮しSiC原子構造を形成することが容易である。つまり、テラスとステップが導入された表面においては、テラスの幅方向（図２のN方向７）のSi[110]原子列が選択的に収縮し供給炭素９とともにSiC原子構造を形成する。このように、just Si(001)表面に形成され問題であった２つのフェーズのSi結晶粒が、テラスとステップの導入により１つのフェーズに限定され単相のSiC単結晶薄膜となることを本発明者は確認した。
【００１６】
テラス５とステップ６を含むSi(001)表面に炭素９を供給し炭化しSiC結晶粒を形成する場合、炭素９を炭化水素などのガス状の物質として供給するとツウィンが形成されやすく、例えば炭素原子などの分子線を含む炭素源を供給するとツウィンの形成が抑制されることも、本発明者は確認した。これは、次のような理由によると考えられる。ガスフェーズの炭素源とSi表面との反応を考えると、Si表面で最も反応性の高い状態にある原子から炭素との反応が始まると考えられる。Si表面で最も反応性の高い状態にあるSi原子は、表面に存在するステップエッジ１０の位置にある原子であり、ガスフェーズの炭素９によるSi表面４の炭化は、ステップエッジ１０から始まると考えられる。ステップエッジ１０においては、基板のSi原子配列に段差が存在するため、その位置から方位の異なるツウィンが成長しやすい。一方、ガスフェーズの炭素だけでなく、例えば炭素原子などの分子線を含む炭素源を供給すると、Si基板との反応が、炭素が供給された任意の位置から起こり、ステップエッジ１０の位置から選択的に起こることが抑制されテラス５上で起こる。このため、ステップエッジ１０の位置からのツウィンの成長も抑制され、ツウィンの少ないSiC結晶薄膜が形成されることを確認した。
【００１７】
【実施例】
以下実施例により本発明をさらに具体的に説明する。
（実施例１）
まず、Si(001) 4度 off-cut 基板をMBE装置内に導入し、10^-9Torr以下の高真空下で９００℃以上に加熱し、RHEED観察によりSi(001)(2x1)表面再配列が観測されるSi清浄表面を形成した。この清浄表面を４００℃以下に冷却した後、昇温速度１００−２５０℃／分で昇温した。基板温度が４００℃に達した時点から、黒鉛粒を充填した坩堝に電子銃を照射する電子線蒸着器から炭素原子を蒸発させて、基板表面に供給した。この場合の坩堝から基板までの距離は４０ｃｍ程度で、電子線蒸着器への供給電力は、８kV,100mA程度が適当であった。基板温度は、炭素の供給を受けつつ昇温され、昇温過程で炭化処理がなされた。この場合、上記off-cut基板を用いると、炭化過程で形成されるSiC結晶粒の結晶方向が揃うことが確認された。これは、図２に示したように、off-cut基板表面にはテラス５とステップ６が多数存在し、ステップエッジ１０に平行な長く連なる原子列のＰ方向８と、ステップエッジ１０に垂直でステップエッジ１０により分断された短いテラス上の原子列のＮ方向７について異なった表面反応性を示すためである。
【００１８】
炭素原子１がSi(001)表面のSi[110]原子列２と反応して収縮することが、炭化の基本メカニズムであるため、Si[110]の原子列の連なりが短い方がより容易に収縮することができ、均一な3C-SiC(001)/Si(001)界面が形成できると考えられる。上記図２のoff-cut基板表面においては、上記Ｎ方向にSi[110]原子列の収縮が容易に起こり、3C-SiC結晶の[110]のSi(下)C(上)方向がＮ方向と一致する。
【００１９】
基板温度が１０５０℃に達した時点から、炭素に加えて珪素もクヌーセンセルから供給され、その後は１０５０℃に保持された。この場合のSiクヌーセンセルの温度は１３５７℃に保たれた。基板表面の結晶性は、MBEの成長室中で常にRHEEDにより観測されており、in-situ分析が行われている。3C-SiC(001)成長表面に供給されるC/Si量は、3C-SiC(001)表面が安定な(3x2)表面再配列構造を常に保つように制御された（表面制御成長）。3C-SiC(001)(3x2)表面は、Si-terminated表面に過剰なSi原子が付加された構造を有し、C/Si=1のSiCの構造に比べてSi過剰な表面となっている。この表面制御成長による3C-SiC(001)表面の成長は、常にSi過剰な表面からSi原子が供給されるため、Si(上)C(下)の方向への成長が選択的に起こり結晶粒がこの方向へより長く成長する。この結晶粒の選択成長方向がoff-cut基板表面のテラス上に長く連なっている図２中のＰ方向８に一致していれば、結晶粒の成長がテラス上でステップによる妨害無しに進行し、容易に単相の3C-SiC単結晶の成長が得られる。一方上記結晶方向と９０度の関係にあるアンチフェーズドメインは、選択成長方向が図２中のＮ方向７となり、成長がステップによって常に阻害される。上記２種類のアンチフェーズドメインが成長する場合には、選択成長方向がＰ方向８に一致している結晶粒が選択的に成長し、もう一方のアンチフェーズドメインは成長に伴って消失してゆくと考えられる。上記、off-cut表面の炭化によって形成される3C-SiCの結晶方向はSi(下)C(上)//N方向であったが、この結晶方位は、テラス上の選択成長を考慮したSi(上)C(下)//P方向と一致する。つまり、上記炭化処理と表面制御成長を行えば、方位の揃った3C-SiC単結晶が選択的に成長し、他のアンチフェーズドメインの成長は阻害され、ある程度の膜厚を成長させれば単相の3C-SiC単結晶薄膜が得られる。
【００２０】
図３に上記表面制御成長を３時間行った１０００オングストローム（１００ｎｍ）膜厚の単相3C-SiC(001)表面のSEM写真を示す。方位の揃った結晶粒がテラス上を選択的に成長しコアレスして大型の単結晶を形成していっているのが観察できる。膜厚１０００オングストローム（１００ｎｍ）に対して、観測されるそれぞれの結晶粒の大きさは１０００オングストローム（１００ｎｍ）程度であった。さらにこの薄膜の成長を続けると、膜厚の増大に伴ってこれらの結晶粒は更に大きくコアレスして大きな単結晶粒を形成した。
【００２１】
図４に、この(a)１０００オングストローム（１００ｎｍ）厚の単相3C-SiC単結晶薄膜のESRスペクトルを、(b)just-cut Si(001)表面上に形成されたAPBを含む２フェーズの薄膜のESRスペクトルと比較して示す。(b)において観測される格子欠陥に対応するSiダングリングボンドのスペクトルが、本発明の炭化珪素薄膜の製造方法により形成された(a)においては確認されず、薄膜中のAPBに起因する格子欠陥が飛躍的に減少していることが確認された。
【００２２】
本実施例においては、異方性を有するSi基板としてoff-cut基板を用いたが、 表面に異方性がありテラスとステップを含んでいれば、just-cut基板であって異方性エッチングなどにより表面に凸凹を付けた表面でも良く、off-cutの方向も[110]方向に限るものではなく、[110]方向と下記式（数２）方向について同等でなく異方性があればどの方向にoff-cutしたものでも良い。
【００２３】
【数２】

【００２４】
本実施例において、off-cutの角度は４度でテラスの幅は20オングストローム（２ｎｍ）程度であったが、off-cutの角度を変化させてテラス幅を変えても、テラス幅が５オングストローム（０．５ｎｍ）−１０００オングストローム（１００ｎｍ）の範囲では、良好な単相の3C-SiC単結晶薄膜が得られた。５オングストローム（０．５ｎｍ）以下のテラス幅の場合は、炭化によって多数のツウィンが形成され、単相の単結晶薄膜が形成できない。また、１０００オングストローム（１００ｎｍ）以上のテラス幅においては、炭化メカニズムにおいて異方性が有効に機能せず、APBを含む２フェーズの薄膜となった。
【００２５】
本実施例においては、炭化処理において基板の昇温中に４００℃から炭素の供給を始めたが、６００℃以下の温度であれば適用でき、４００℃に限るものではない。６００℃以上の温度から炭素を供給し炭化するとSiC/Si界面にピットが形成され易くなり、薄膜中に結晶方位の異なる結晶粒が成長しやすい。
【００２６】
本実施例において、炭素は電子線蒸着器から原子またはクラスターの形で供給されており、ガス状の炭素の供給とは異なっている。本実施例の薄膜形成中にC₂H₄等のガス状の炭素源を5x10^-8Torr以上供給すると、実施例で述べた単相の3C-SiCの形成が悪化し、多数のツウィンが形成されることが確認された。このことより、本発明の炭化珪素薄膜の形成方法の実現のためには、ガス状ではない分子線の炭素の供給が必要であることが確認された。
【００２７】
本実施例においては、炭化後に炭素と珪素を供給して炭化珪素を成長させるプロセスにおいて、3C-SiC(001)表面が(3x2)の表面再配列を有しSiターミネイト(001)表面上に付加Siが存在するSi過剰な表面を保持して成長させた。表面再配列がSi過剰な他の再配列構造(5x2),(7x2),・・(2n+1,2)（nは任意の正の整数）を 保持するように成長させた場合も本発明は有効であった。また、Siターミネイト(001)表面である(2x1)表面でも有効であった。
【００２８】
本実施例においては、Si(001)表面について説明したが、例えばSi(111)面のようなSi基板の他の表面でも本発明が有効であることを発明者は確認した。
【００２９】
【発明の効果】
以上説明した通り本発明によれば、炭化珪素（Ｓｉ−Ｃ）薄膜の製造方法であって、炭素を供給しＳｉ基板表面を加熱することにより表面を炭化させて炭化珪素を形成する工程と、炭化後に炭素と珪素を供給して炭化珪素を成長させる工程からなり、前記Ｓｉ基板表面に異方性がありテラスとステップを形成することにより、Si基板表面にヘテロエピタキシャル成長させ、Siウェハ上に結晶欠陥の少ない単相の3C-SiC単結晶薄膜を形成できる。
【００３０】
また本発明の炭化珪素薄膜の製造方法により、APBを含まない単相の3C-SiC単結晶薄膜が制御性良く成長可能となり、電子デバイスに応用可能な3C-SiC単結晶薄膜が、Si基板上に形成できるようになった。
【図面の簡単な説明】
【図１】Si(001)基板の表面炭化のプロセス概念図。
【図２】本発明の一実施例の炭化珪素薄膜の製造方法に用いるSi基板の表面の模式図。
【図３】本発明の一実施例の炭化珪素薄膜の製造方法により形成された3C-SiC(001)表面のSEM写真のトレース図。
【図４】(a)は本発明の一実施例の炭化珪素薄膜の製造方法により形成され た単相3C-SiC単結晶薄膜のESRスペクトルのトレース図、(b)は比較例のjust-cut Si(001)表面上に形成されたAPBを含む２フェーズの薄膜のESRスペクトルのトレース図。
【符号の説明】
１ 炭素原子
２ 炭素と結合したSi基板原子（Si[110]原子列）
３ 炭素と結合したSi原子の一層下のSi基板原子
４ Si基板表面
５ テラス
６ ステップ
７ ステップエッジと垂直なＮ方向
８ ステップエッジと平行なＰ方向
９ 供給炭素
１０ ステップエッジ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-crystal thin film and its manufacturing method of the high power devices, high temperature devices, environmental resistance device silicon carbide is a wide bandgap semiconductor material that can be applied to a semiconductor element such as (SiC). In particular, the present invention relates to a silicon carbide thin film that forms a single-phase 3C-SiC single crystal thin film with few crystal defects on a Si wafer by heteroepitaxial growth on the surface of the Si substrate, and a method for manufacturing the same .
[0002]
[Prior art]
Conventionally, 6H-type and 4H-type SiC single crystal substrates are commercially available, but for 3C-SiC having the highest mobility, crystals heteroepitaxially grown on the Si substrate were formed. In the case of growing silicon carbide on the Si substrate surface, first, carbon hydrogen gas was supplied to the Si surface and heated to carbonize, and then carbon and silicon were supplied to heteroepitaxially grow silicon carbide.
[0003]
[Problems to be solved by the invention]
The silicon carbide thin film formed by this conventional technique grows at a high density of lattice defects, twins, etc. at the SiC / Si interface, which is a problem for producing a silicon carbide substrate for forming an electronic device. there were. Furthermore, single crystal grains of two types of phases grow on the Si substrate, and anti-phase boundary (APB) is formed at the interface between the two types of crystal grains of different phases. Met.
[0004]
FIG. 1 shows a conceptual diagram of a process mechanism for forming SiC crystal grains by supplying carbon to the Si surface, heating it, and carbonizing it. On a clean Si (001) surface, Si atoms having two dangling bonds are connected in the [110] direction. When this dangling bond is compensated by carbon atoms, a Si-C atom string connected to Si-C-Si .. is formed in the [110] direction. Here, when the bond between the Si atom 2 bonded to the carbon atom 1 and the Si atom 3 therebelow is cut, the Si—C—Si.. 2 contracts in the Si [110] direction to form a SiC atomic structure. On the just Si (001) surface without off-cut, the direction of the following equation (Equation 1) perpendicular to the Si [110] direction cannot be distinguished, and appears on the Si (001) surface with the same probability.
[0005]
[Expression 1]

[0006]
For this reason, the shrinkage in the Si [110] direction occurs with almost the same probability with respect to the two directions orthogonal to each other, and the two types of SiC crystal grains having different directions have phases different from each other. The SiC crystal grains having different phases cannot be bonded to each other by growth and become a two-phase thin film containing APB at the interface.
[0007]
In order to solve the above conventional problems, the present invention provides a silicon carbide thin film that forms a single-phase 3C-SiC single crystal thin film with few crystal defects on a Si wafer by heteroepitaxial growth on the surface of the Si substrate, and a method for manufacturing the same The purpose is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the silicon carbide thin film of the present invention is a silicon carbide crystal laminated on the surface of a Si substrate, which is short in the silicon carbide 3C-SiC [ 110 ] direction , and has the 3C-SiC [110] direction. is constituted by a silicon carbide crystal grains having a long anisotropy in a direction perpendicular, the Si substrate surface is the Si (001) off-cut surface, a terrace having anisotropy with respect to Si [110] direction and includes a step, so that the silicon carbide 3C-SiC [110] direction coincides with the Si [110] direction nearly perpendicular to the step edge direction of the Si substrate, Si [110] atoms of the Si (001) surface The column has a 3C-SiC ( 001 ) / Si ( 001 ) interface contracted by reacting with carbon atoms, and is stacked with a film thickness of 100 nm or more .
[0009]
The method of manufacturing a silicon carbide thin film according to the present invention includes heating an Si substrate having an anisotropy relative to the Si [110] direction and an off-cut Si (001) substrate surface including steps during heating to increase the Si substrate surface. at a temperature of 600 ° C. or less steps, supplying a carbon source comprising molecular beam such as carbon atoms, the Si by carbonizing the surface by heating the substrate surface to 1050 ° C. to form silicon carbide, Si (001 ) A first process for forming a 3C-SiC ( 001 ) / Si ( 001 ) interface in which a Si [ 110 ] atomic sequence close to perpendicular to the step edge direction of the surface reacts with carbon atoms and contracts ; And a silicon carbide 3C-SiC grown by the second process, including a second process of maintaining a structure in which the silicon carbide surface has an excess of Si atoms added to the Si-terminated surface as a growth surface . 110 ] direction and silicon carbide crystal grains having long anisotropy in a direction perpendicular to the 3C-SiC [110] direction, the Si substrate surface is a Si ( 001 ) off-cut plane, and the Si substrate step edges perpendicular to the direction close to Si [110] by stacking so that the direction in the silicon carbide 3C-SiC [110] direction coincides the to and growing.
[0010]
In the above configuration, the width of the terrace on the Si substrate surface is preferably 5 angstroms (0.5 nm) or more and 1000 angstroms (100 nm) or less.
[0012]
In the above-described present invention, crystal grains having two types of phases, which have been a problem in the prior art, by introducing terraces and steps by adding anisotropy to the surface of the Si substrate that is carbonized to form silicon carbide. Is limited to one phase of crystal grains, and the formation of APB is suppressed.
[0013]
Furthermore, in the process of growing silicon carbide by supplying carbon and Si after carbonization, if the silicon carbide surface holds as a growth surface a structure in which excess Si atoms are added to the Si terminator surface The axis of easy growth corresponds to the direction along the terrace of the Si substrate surface having the above anisotropy, and one kind of phase crystal grains is selectively grown to further form the anti-phase boundary (APB). It is suppressed.
[0014]
Furthermore, if the carbon source supplied when the silicon substrate surface is heated and carbonized to form silicon carbide includes not only gaseous substances such as hydrocarbons but also molecular beams such as carbon atoms, twin formation is formed. It is suppressed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 shows a schematic diagram of the Si substrate surface with terraces and steps with anisotropy of the present invention. The Si (001) surface 4 is tilted in the [110] direction and is off-cut, and the terrace 5 and step 6 are introduced. The terrace width (perpendicular to the step edge: N direction 7 in FIG. 2) is very short compared to the terrace length parallel to the step edge (P direction 8 in FIG. 2), and the off-cut angle is If it is 4 degrees and the height of step 6 is one atomic layer, it is about 20 angstroms. This short chain of Si [110] atoms (N direction 7 in FIG. 2) reacts with carbon and contracts with SiC atoms compared to the long chain of Si [110] atoms in P direction 8 in FIG. It is easy to form a structure. That is, on the surface where the terrace and the step are introduced, the Si [110] atomic sequence in the terrace width direction (N direction 7 in FIG. 2) selectively contracts to form a SiC atomic structure with the supplied carbon 9. In this way, the two-phase Si crystal grains formed on the surface of just Si (001) are limited to one phase by the introduction of terraces and steps and become a single-phase SiC single crystal thin film. The inventor confirmed.
[0016]
When carbon 9 is supplied to the Si (001) surface including terrace 5 and step 6 and carbonized to form SiC crystal grains, twins are easily formed when carbon 9 is supplied as a gaseous substance such as hydrocarbon. The present inventor has also confirmed that the formation of twins is suppressed when a carbon source including molecular beams such as atoms is supplied. This is considered to be due to the following reasons. Considering the reaction between the carbon source in the gas phase and the Si surface, it is considered that the reaction with the carbon starts from the atom in the most reactive state on the Si surface. The Si atom in the most reactive state on the Si surface is the atom at the position of the step edge 10 existing on the surface, and the carbonization of the Si surface 4 by the carbon 9 in the gas phase starts from the step edge 10. It is done. At the step edge 10, there is a step in the Si atom arrangement of the substrate, so that twins having different orientations tend to grow from that position. On the other hand, when supplying not only carbon in the gas phase but also a carbon source including a molecular beam such as a carbon atom, the reaction with the Si substrate occurs from an arbitrary position where the carbon is supplied, and is selected from the position of the step edge 10. Happening on the terrace 5 is suppressed. For this reason, it was confirmed that the growth of twins from the position of the step edge 10 was suppressed and a SiC crystal thin film with few twins was formed.
[0017]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
First, Si (001) 4 degree off-cut substrate was introduced into the MBE device, heated to 900 ° C or higher under high vacuum of 10 ^-9 Torr or less, and Si (001) (2x1) surface rearrangement by RHEED observation The Si clean surface was observed. After this clean surface was cooled to 400 ° C. or lower, the temperature was increased at a temperature increase rate of 100-250 ° C./min. When the substrate temperature reached 400 ° C., carbon atoms were evaporated from an electron beam evaporator that irradiates an electron gun onto a crucible filled with graphite grains, and supplied to the substrate surface. In this case, the distance from the crucible to the substrate was about 40 cm, and the power supplied to the electron beam evaporator was suitably about 8 kV, 100 mA. The substrate temperature was raised while receiving the supply of carbon, and carbonization was performed during the temperature raising process. In this case, it was confirmed that when the off-cut substrate was used, the crystal directions of the SiC crystal grains formed during the carbonization process were aligned. As shown in FIG. 2, there are a large number of terraces 5 and steps 6 on the surface of the off-cut substrate, and the P direction 8 of the long atomic sequence parallel to the step edge 10 is perpendicular to the step edge 10. This is because different surface reactivity is exhibited in the N direction 7 of the atomic sequence on the short terrace divided by the step edge 10.
[0018]
Since the basic mechanism of carbonization is that carbon atom 1 reacts with Si [110] atom sequence 2 on the Si (001) surface and contracts, it is easier when the sequence of Si [110] atom sequences is shorter. It can be shrunk and a uniform 3C-SiC (001) / Si (001) interface can be formed. On the surface of the off-cut substrate in FIG. 2 above, the Si [110] atomic column contracts easily in the N direction, and the [110] Si (down) C (up) direction of the 3C-SiC crystal is in the N direction. Matches.
[0019]
When the substrate temperature reached 1050 ° C., silicon was also supplied from the Knudsen cell in addition to carbon, and thereafter maintained at 1050 ° C. The temperature of the Si Knudsen cell in this case was maintained at 1357 ° C. The crystallinity of the substrate surface is always observed by RHEED in the MBE growth chamber, and in-situ analysis is performed. The amount of C / Si supplied to the 3C-SiC (001) growth surface was controlled so that the 3C-SiC (001) surface always maintained a stable (3x2) surface rearrangement structure (surface controlled growth). The 3C-SiC (001) (3x2) surface has a structure in which excess Si atoms are added to the Si-terminated surface, and has a Si-rich surface compared to the structure of SiC with C / Si = 1. . The growth of 3C-SiC (001) surface by this surface-controlled growth is always supplied with Si atoms from the Si-rich surface, so that the growth in the direction of Si (upper) and C (lower) occurs selectively. Grow longer in this direction. If the selective growth direction of the crystal grains coincides with the P direction 8 in FIG. 2 which is long and continuous on the terrace on the surface of the off-cut substrate, the growth of the crystal grains proceeds on the terrace without interference by steps. Therefore, single-phase 3C-SiC single crystal growth can be easily obtained. On the other hand, in the anti-phase domain having a relationship of 90 degrees with the crystal direction, the selective growth direction is the N direction 7 in FIG. 2, and the growth is always inhibited by the step. When the above two types of anti-phase domains grow, crystal grains whose selective growth direction coincides with the P direction 8 selectively grow, and the other anti-phase domain disappears with the growth. it is conceivable that. The crystal orientation of 3C-SiC formed by carbonization of the off-cut surface was the Si (lower) C (upper) // N direction, but this crystal orientation was determined by considering the selective growth on the terrace. (Upper) C (Lower) Aligns with // P direction. That is, by performing the carbonization treatment and surface control growth, orientation of uniform 3C-SiC single crystal selectively grown, the growth of other antiphase domain is inhibited, it is grown a certain thickness single Phase 3C-SiC single crystal thin film is obtained.
[0020]
FIG. 3 shows a SEM photograph of a single-phase 3C—SiC (001) surface having a thickness of 1000 Å (100 nm) obtained by performing the above surface-controlled growth for 3 hours. It can be observed that crystal grains with uniform orientation are selectively grown on the terrace and coreless to form a large single crystal. For a film thickness of 1000 angstroms (100 nm), the size of each observed crystal grain was about 1000 angstroms (100 nm). Further, when the growth of this thin film was continued, as the film thickness increased, these crystal grains became more coreless and formed large single crystal grains.
[0021]
Figure 4 shows the ESR spectrum of this (a) 1000 angstrom (100 nm) thick single-phase 3C-SiC single crystal thin film, and (b) two-phase including APB formed on the just-cut Si (001) surface. It is shown in comparison with the ESR spectrum of the thin film. The spectrum of Si dangling bonds corresponding to the lattice defects observed in (b) was not confirmed in (a) formed by the method for producing a silicon carbide thin film of the present invention, and was caused by APB in the thin film. It was confirmed that defects were dramatically reduced.
[0022]
In this embodiment, an off-cut substrate is used as the Si substrate having anisotropy. However, if the surface has anisotropy and includes a terrace and a step, the substrate is a just-cut substrate and is anisotropically etched. For example, the surface may be uneven, and the off-cut direction is not limited to the [110] direction. If the [110] direction and the following equation (Equation 2) are not equal and anisotropic, It may be off-cut in any direction.
[0023]
[Expression 2]

[0024]
In this embodiment, the off-cut angle is 4 degrees and the terrace width is about 20 angstroms (2 nm). However, even if the terrace width is changed by changing the off-cut angle, the terrace width is 5 angstroms. In the range of (0.5 nm) -1000 Å (100 nm), a good single-phase 3C—SiC single crystal thin film was obtained. In the case of a terrace width of 5 angstroms (0.5 nm) or less, a large number of twins are formed by carbonization, and a single-phase single crystal thin film cannot be formed. In addition, at a terrace width of 1000 angstroms (100 nm) or more, anisotropy did not function effectively in the carbonization mechanism, resulting in a two-phase thin film containing APB.
[0025]
In the present embodiment, the carbon supply is started from 400 ° C. during the temperature raising of the substrate in the carbonization treatment, but it can be applied at a temperature of 600 ° C. or lower, and is not limited to 400 ° C. When carbon is supplied from a temperature of 600 ° C. or more and carbonized, pits are easily formed at the SiC / Si interface, and crystal grains having different crystal orientations are likely to grow in the thin film.
[0026]
In this embodiment, carbon is supplied in the form of atoms or clusters from an electron beam evaporator, which is different from the supply of gaseous carbon. When a gaseous carbon source such as C ₂ H _{4 is} supplied in an amount of 5 × 10 ⁻⁸ Torr or more during the thin film formation of this example, the formation of single-phase 3C—SiC described in the example deteriorates and a large number of twins are formed. It was confirmed that From this, it was confirmed that the supply of molecular beam carbon that is not gaseous is necessary to realize the method for forming a silicon carbide thin film of the present invention.
[0027]
In this example, in the process of growing silicon carbide by supplying carbon and silicon after carbonization, the 3C-SiC (001) surface has a (3x2) surface rearrangement and is added onto the Si terminator (001) surface. The Si-excess surface where Si was present was retained and grown. The present invention also includes the case where the surface rearrangement is grown so as to retain other rearrangement structures (5x2), (7x2), ... (2n + 1,2) (n is an arbitrary positive integer) containing Si. Was effective. It was also effective on the (2x1) surface, which is the Si terminator (001) surface.
[0028]
In the present embodiment, the Si (001) surface has been described, but the inventors have confirmed that the present invention is effective for other surfaces of the Si substrate such as the Si (111) surface.
[0029]
【The invention's effect】
As described above, according to the present invention, there is provided a method for manufacturing a silicon carbide (Si-C) thin film, wherein carbon is supplied and the surface of the Si substrate is heated to carbonize the surface to form silicon carbide; It consists of a step of growing silicon carbide by supplying carbon and silicon after carbonization. By forming terraces and steps with anisotropy on the surface of the Si substrate, heteroepitaxial growth is performed on the surface of the Si substrate, and crystals are formed on the Si wafer. Single phase 3C-SiC single crystal thin film with few defects can be formed.
[0030]
In addition, according to the method for producing a silicon carbide thin film of the present invention, a single-phase 3C-SiC single crystal thin film containing no APB can be grown with good controllability, and a 3C-SiC single crystal thin film applicable to an electronic device is formed on a Si substrate. It became possible to form.
[Brief description of the drawings]
FIG. 1 is a process conceptual diagram of surface carbonization of a Si (001) substrate.
FIG. 2 is a schematic view of the surface of a Si substrate used in the method for manufacturing a silicon carbide thin film according to one embodiment of the present invention.
FIG. 3 is a trace drawing of an SEM photograph of the surface of 3C—SiC (001) formed by the method for producing a silicon carbide thin film according to one embodiment of the present invention.
4A is a trace diagram of an ESR spectrum of a single-phase 3C—SiC single crystal thin film formed by the method for producing a silicon carbide thin film of one embodiment of the present invention, and FIG. 4B is a just-cut of a comparative example. The trace figure of the ESR spectrum of the thin film of 2 phases containing APB formed on the Si (001) surface.
[Explanation of symbols]
1 carbon atom 2 Si substrate atom bonded to carbon (Si [110] atomic sequence)
3 Si substrate atoms below Si atoms bonded to carbon 4 Si substrate surface 5 Terrace 6 Step 7 N direction perpendicular to step edge 8 P direction parallel to step edge 9 Supply carbon 10 Step edge

Claims (3)

A silicon carbide crystal laminated on the surface of the Si substrate,
The silicon carbide 3C-SiC [ 110 ] direction is short, the silicon carbide crystal grains having a long anisotropy in a direction perpendicular to the 3C-SiC [110] direction,
The Si substrate surface is a Si ( 001 ) off-cut plane ,
Comprising a terrace and steps having anisotropy relative to the Si [110] direction;
In order that the silicon carbide 3C-SiC [110] direction coincides with the Si [110] direction that is perpendicular to the step edge direction of the Si substrate,
The Si [ 110 ] atomic sequence on the Si ( 001 ) surface has a 3C-SiC ( 001 ) / Si ( 001 ) interface contracted by reacting with a carbon atom ,
A silicon carbide thin film characterized by being laminated with a film thickness of 100 nm or more .   The silicon carbide thin film according to claim 1, wherein the width of the terrace on the surface of the Si substrate is 5 angstroms (0.5 nm) or more and 1000 angstroms (100 nm) or less. A method of manufacturing a silicon carbide thin film,
On an off-cut Si (001) substrate surface including a terrace and steps having anisotropy with respect to the Si [110] direction,
Supplying a carbon source containing molecular beams such as carbon atoms at a stage where the temperature of the Si substrate surface is 600 ° C. or lower during heating and heating ,
By heating the surface of the Si substrate to 1050 ° C., the surface is carbonized to form silicon carbide, and the Si [ 110 ] atomic sequence near the step edge direction on the Si ( 001 ) surface reacts with carbon atoms and contracts. A first process of forming a 3C-SiC ( 001 ) / Si ( 001 ) interface ,
Including a second process of supplying carbon and silicon, and maintaining a structure in which the silicon carbide surface has an excess of Si atoms added to the Si termination surface as a growth surface;
Short in the direction of silicon carbide 3C-SiC [ 110 ] grown by the second process,
Silicon carbide crystal grains having long anisotropy in a direction perpendicular to the 3C-SiC [110] direction,
The Si substrate surface is a Si ( 001 ) off-cut plane,
The Si by stacking such that the silicon carbide 3C-SiC [110] direction nearly vertical Si [110] direction in the step edge direction of the substrate coincide, a method for manufacturing a silicon carbide thin film and growing.

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