JPH0527599B2 - - Google Patents
Info
- Publication number
- JPH0527599B2 JPH0527599B2 JP62159330A JP15933087A JPH0527599B2 JP H0527599 B2 JPH0527599 B2 JP H0527599B2 JP 62159330 A JP62159330 A JP 62159330A JP 15933087 A JP15933087 A JP 15933087A JP H0527599 B2 JPH0527599 B2 JP H0527599B2
- Authority
- JP
- Japan
- Prior art keywords
- diamond
- substrate
- single crystal
- film
- crystal film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000010432 diamond Substances 0.000 claims description 59
- 229910003460 diamond Inorganic materials 0.000 claims description 58
- 239000000758 substrate Substances 0.000 claims description 50
- 239000013078 crystal Substances 0.000 claims description 46
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 18
- 239000004065 semiconductor Substances 0.000 claims description 15
- 239000000395 magnesium oxide Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 229910020068 MgAl Inorganic materials 0.000 claims description 6
- 239000011029 spinel Substances 0.000 claims description 6
- 229910052596 spinel Inorganic materials 0.000 claims description 6
- 239000010408 film Substances 0.000 description 49
- 239000000463 material Substances 0.000 description 14
- 230000037230 mobility Effects 0.000 description 14
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 12
- 229910052710 silicon Inorganic materials 0.000 description 10
- 239000010703 silicon Substances 0.000 description 10
- 238000000034 method Methods 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 125000004429 atom Chemical group 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 150000002500 ions Chemical class 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 239000012495 reaction gas Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 125000004432 carbon atom Chemical group C* 0.000 description 4
- 238000005229 chemical vapour deposition Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 238000002834 transmittance Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 229910052787 antimony Inorganic materials 0.000 description 2
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 230000005355 Hall effect Effects 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000002003 electron diffraction Methods 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- -1 oxygen ions Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Description
（産業上の利用分野）
本発明は酸化物単結晶基板ないしは、半導体基
板上に形成させた酸化物単結晶膜上に炭化水素化
合物気体と水素を原料とし、気相成長せしめるこ
とを特徴とするダイヤモンド単結晶膜の製造方法
に関する。
（従来技術と発明が解決しようとする問題点）
ダイヤモンドはエネルギーギヤツプが大きく、
高絶縁性を示すと同時に500W／ｍ・ｋ〜
2000W／ｍ・ｋと大きな熱伝導度を持ち、更に高
硬度で耐磨耗性に優れる等の他の材料では得られ
ない種々の特性を有すことは良く知られている。
また、ダイヤモンドは不純物のドーピングによつ
て半導体化でき、電子移動度は1800cm／Ｖ・sec、
ホール移動度は1600cm／Ｖ・secでシリコンの電
子移動度1200cm／Ｖ・sec、ホール移動度600cm／
Ｖ・secに比較しても大きくエネルギーギヤツプ
の大きいこと等と合わせて、高性能半導体素子の
実現が可能であることが予想されている。
従来ダイヤモンドを合成するには、超高圧高温
下で炭素を原料として合成する手法が工業化され
ているが、この方法では得られるダイヤモンド結
晶は高々数mmのものでしかない。工業的実用性を
考慮すると、少なくとも１インチ以上望ましくは
４インチ程度の大面積化が要請されているが、超
高圧・高温を用いる手法ではダイヤモンドの大面
積化は非現実的である。
一方低温低圧下で大面積のダイヤモンド膜を得
る手法が近年種々開発されつつある。即ち炭化水
素ガスや水素ないしはアルゴンガスを原料とし、
熱分解を用いる化学気相析出法（CVD）、プラズ
マCVD法、イオンビーム法ないしはスパツタ法
等がそれである。この手法は比較的安価に大面積
のダイヤモンド膜が得られるので実用的である
が、基板としてダイヤモンド以外の材料例えばシ
リコン、モリブデン、タングステンあるいはタン
グステンカーバイトないしはシリコンカーバイト
などを用いると、得られるダイヤモンド膜は、直
径１ミクロンから５ミクロン程度の粒子からなる
多結晶膜で、膜の表面の凹凸が0.1〜１ミクロン
程度あり、膜表面での光の散乱が大きく電子材料
としての応用は限られたものでしかなかつた。
即ちダイヤモンドの優れた光学的性質を利用し
ようとしても光は膜表面で散乱反射され膜内に光
が導入できなかつたり、たとえ膜内に光が導入で
きたとしても、ミクロン程度の多結晶では、結晶
粒界での光の散乱や粒界に存在する結晶欠陥によ
る光の吸収などのため光学的特性は利用できない
という問題があつた。
また近年の高度に発達した電子デバイスは微細
化・高集積化が著しくこれに伴つて素子の問題は
極めて深刻になつている。ダイヤモンドの2000／
Wm・ｋに達する高熱伝導特性は、熱放散の効率
を著しく高め素子の性能・信頼性を高め得ること
がわかつているが、多結晶ダイヤモンド膜では素
子作製技術上要求される微細加工は不可能で利用
することはできなかつた。
更に電気特性を利用するにも多結晶膜では、表
面凹凸や粒界での散乱やキヤリアトラツピング等
が生じ半導体化したとしても高移動度は期待でき
ないことは自明である。即ち、ホールないしは電
子移動度は結晶の完全性に大きく影響されること
は良く知られている。
結晶粒界のないダイヤモンド単結晶膜が実現で
きれば、大きな移動度が期待でき、また、微細加
工技術の適用も可能となり素子作製が可能となる
ため、実用的価値は量り知れない。
ところでダイヤモンド単結晶膜は、ダイヤモン
ド単結晶基板上には成長できることは知られてい
るが、また利用可能なダイヤモンド単結晶基板は
高々数mm角でしかなく、またその価格も高く、実
用的ではない。従つて、ダイヤモンド以外の基板
例えばシリコンやヒ化ガリウム等の半導体単結晶
基板上にダイヤモンド単結晶膜を製造する技術が
望まれているが、これまでダイヤモンド単結晶基
板以外で単結晶ダイヤモンド膜が作製できる基板
材料は知られていなかつた。
本発明の目的は、以上述べてきたような従来の
種々の欠点を除去し、ダイヤモンド以外の基板上
に成長させることのできるダイヤモンド単結晶膜
の製造方法を提供するところにある。
（問題点を解決するための手段）
本発明によれば基板として酸化物単結晶ないし
は、ダイヤモンド以外の単結晶上に成長させた酸
化物単結晶膜を用いることによつてダイヤモンド
単結晶膜を製造することができる。
なお、酸化物単結晶として、化学式MgAl2O4
ないしMgOとAl2O3の固溶体であるMgO・
nAl2O3（１≦ｎ≦3.5）で示されるマグネシアスピ
ネルを用い、またダイヤモンド以外の単結晶基板
として、シリコンを用い該シリコン基板上に化学
気相析出法（CVD）によつて、マグネシアスピ
ネル（MgAl2O4）薄膜をエピタキシヤル成長さ
せた基板を用いるのが有効である。
（作用）
一般に基板物質とその上に成長できる薄膜物質
の間のエピタキシー関係を支配している因子につ
いては現在まで十分には解明されていないが、基
板物質表面の格子面での原子配列の状況や表面の
形状・形態、更に付着物質と基板物質の物理的化
学的相互作用が大きく影響する。
即ち基板上への薄膜の成長は成長すべき原子種
の表面への吸着および基板原子との結合、吸着種
の表面格散による結晶核発生と成長を通して進行
すると推定されるので、これらの膜成長のプロセ
スが制御できる技術が必要である。
基板上へのエピタキシヤル成長させるには特に
基板と成長すべき膜物質の格子マツチングは特に
重要とされている。このことを示すパラメーター
としてミスフイツトフアクタなる量が一応の目安
とされている。即ち基板の表面での原子の周期ds
と、膜物質の原子の周期dfの違いの割合（df−
ds）／dsをミスフイツトフアクタの称するが、こ
の量が通常約15％以下でエピタキシヤル成長する
と云われている。しかしながら現実には15％を越
える材料でもエピタキシヤル成長の例もあるので
必要十分条件というわけではない。更に基板物質
と異なる物質間のヘテロエピタキシヤル成長を考
えると、基板の原子の周期の整数倍と成長させる
物質の原子の周期の整数倍とが一致していても良
いことは知られているが、全ての物質で成立する
原則であるかどうかは明らかではない。
本発明者は、ダイヤモンドのヘテロエピタキシ
ヤル成長については、ダイヤモンドを構成する炭
素原子と相互作用の大きい基板表面原子の周期を
一致させることを意図し、種々の基板材料につい
て検討を重ね、特にイオン半径の大きい酸素を構
成元素の一部とする酸化物単結晶を用いれば、炭
素原子の表面拡散を制御することができ、ダイヤ
モンド単結晶膜を結晶成長させ得ることを着想
し、本発明に至つた。
本発明においては、先に述べた様にダイヤモン
ドの炭素原子の配列周期と基板となる酸化物の原
子の配列周期が一致できる必要がある。
ダイヤモンドは良く知られているようにダイヤ
モンド構造を取り、空間群Fd3mに属し、その格
子定数は3.5667Åである。一方酸化物として同じ
空間群に属する物質の一として、マグネシアピネ
ルMgAl2O4を考える。この物質の格子定数は
8.0831Åである。またこの物質を構成する元素の
イオン半径はMg2+、Al3+およびO2-でそれぞれ
0.78Å、0.57Åおよび1.32Åで酸素イオンのイオ
ン半径は金属イオンの約２倍ある。従つて酸化物
単結晶表面には酸素の占める面積が非常に大き
く、ダイヤモンドを炭化水素ガスの分解を通して
気相成長させる場合には、表面金属原子のみなら
ず酸素の効果も重要である。即ち、メタンガス
（CH4）を例に取ると、プラズマや熱フイラメン
ト等によつて励起されたCH3 *ラジカルないし
CH3イオンは基板表面上で炭素原子と基板原子と
が吸着反応するものと考えられる。この過程の詳
細については不明であるが、大きなイオン半径の
負のイオンである酸素と正のイオンであるCH3 +
イオンがより吸着及び反応しやすいと考えるのが
適当である。即ち、負のイオンである酸素の方向
性を反映してCH3 +イオンが方向性を持つて配列
し、水素引き抜き反応及び再吸着等の機構により
ダイヤモンドが酸化物単結晶基板上にヘテロエピ
タキシヤル成長することになる。
次に格子周期のマツチングフアクターである
が、必ずしも格子定数の値が一致することは必要
ではなく、それぞれの整数倍が一致することでも
エピタキシヤル成長できることは先に述べた。ダ
イヤモンドの（100）面と、マグネシアスピネル
の（100）面では、ダイヤモンドの格子の９倍と
スピネルの４倍はそれぞれ32.100Åおよび32.332
Åでミスフイツトフアクターは−0.7％であり、
極めて格子整合が良好であり、エピタキシヤル成
長条件を満たすものである。
以上述べた様に本発明の主旨は必ずしもマグネ
シアスピネルに限られるものではなく、比較的イ
オン半径の大きい酸素が基板表面に格子整合が取
れる状態にできれば良いことは云うまでもない。
（実施例）
第１図は、本発明に用いたダイヤモンド単結晶
膜の製造装置である。ダイヤモンド単結晶膜の製
造プロセスを以下に示す。
基板１を基板支持台２に載せ、コツク３を止め
て真空排気装置４によつて真空槽５内を10-5トー
ル以下に予備排気する。所定の比率で混合された
反応ガス６を真空槽５内に導入し、圧力調整バル
ブ７によつて所定の圧力に設定する。赤外ランプ
８により基板支持台２及び基板１を所定の温度に
昇温後、電流導入端子９に交流ないしは直流を通
電し、熱フイラメントを2000℃以上に加熱するこ
とによつて基板１上にダイヤモンド単結晶膜を成
長させた。
大面積化を容易にする為に、第２図に示すよう
な構成にした。熱フイラメント１を多数本密に張
り大面積化を達成すると共に基板支持台２に設置
した基板３を図中にある方向に回転かつ移動させ
ることによつて均一化を達成した。
用いた基板は直径30mmのMgAl2O4（100）面、
（110）面、（111）面及び直径100mmのシリコン
（110）上にエピタキシヤル成長させたMgAl2O4
（110）である。反応ガスは炭素源として水素希釈
メタン又は水素希釈アセトン蒸気を用い、Ｐ型半
導体化の為に水素希釈B2H6を用いＮ型半導体化
の為に水素希釈PH3、水素希釈AsH3又は水素希
釈アンチモン蒸気を用いた。
ダイヤモンドの単結晶化に影響する条件とし
て、基板温度及び反応ガス中の炭素の割合が考え
られるので、良質のダイヤモンド単結晶膜が得ら
れる条件を調べた。その結果基板温度は高い程
（800℃以上）、反応ガス中の炭素の割合は低い程
（１％以下）良好なエピタキシヤルダイヤモンド
膜が得られた。膜の構造は、高速電子線回折法で
評価したが、良好なエピタキシヤル膜では縦に伸
びたストリークが観察され、表面平坦性および結
晶性共に良好であつた。
第１表に各種基板を用いた時のダイヤモンド単
結晶膜の方位、ホール効果測定による室温での移
動度を示す。合成条件は反応ガス（0.2％メタ
ン）、圧力（30トール）、基板温度（900℃）、時間
（20時間）、フイラメント（タングステン、2200
℃）、フイラメント−基板間距離（10mm）である。
またＰ型半導体化の為に水素希釈B2H6及びＮ型
半導体の為にAsH3を用いた。
(Industrial Application Field) The present invention is characterized by vapor phase growth using a hydrocarbon compound gas and hydrogen as raw materials on an oxide single crystal substrate or an oxide single crystal film formed on a semiconductor substrate. The present invention relates to a method for manufacturing a diamond single crystal film. (Problems to be solved by the prior art and the invention) Diamond has a large energy gap;
500W/m・k~ while showing high insulation properties
It is well known that it has a high thermal conductivity of 2000 W/m·k, and also has various properties that cannot be obtained with other materials, such as high hardness and excellent wear resistance.
Also, diamond can be made into a semiconductor by doping with impurities, and its electron mobility is 1800 cm/V・sec.
The hole mobility is 1600cm/V・sec, the electron mobility of silicon is 1200cm/V・sec, and the hole mobility is 600cm/V・sec.
Combined with the large energy gap compared to Vsec, it is expected that high-performance semiconductor devices will be possible. Conventional methods for synthesizing diamonds have been industrialized, using carbon as a raw material under ultra-high pressure and high temperatures, but this method produces diamond crystals that are only a few millimeters in size at most. Considering industrial practicality, a large area of at least 1 inch or more, preferably about 4 inches is required, but it is unrealistic to increase the area of diamond using methods that use ultra-high pressure and high temperature. On the other hand, various methods have been developed in recent years to obtain large-area diamond films at low temperatures and low pressures. That is, using hydrocarbon gas, hydrogen or argon gas as raw material,
Examples include chemical vapor deposition (CVD) using thermal decomposition, plasma CVD, ion beam method, and sputtering method. This method is practical because it allows a large area diamond film to be obtained at a relatively low cost, but if a material other than diamond is used as the substrate, such as silicon, molybdenum, tungsten, tungsten carbide, or silicon carbide, The film is a polycrystalline film consisting of particles with a diameter of about 1 to 5 microns, and the surface of the film has irregularities of about 0.1 to 1 micron, and the scattering of light on the film surface is large, limiting its application as an electronic material. It was nothing but a thing. In other words, even if you try to take advantage of diamond's excellent optical properties, the light will be scattered and reflected on the film surface and you will not be able to introduce it into the film, or even if you can introduce light into the film, if it is polycrystalline on the order of microns, There was a problem that optical properties could not be used because of light scattering at grain boundaries and light absorption by crystal defects existing at grain boundaries. In addition, in recent years highly developed electronic devices have become extremely fine and highly integrated, and as a result, problems with the elements have become extremely serious. Diamond 2000/
It is known that the high thermal conductivity of Wm・k can significantly increase the efficiency of heat dissipation and improve the performance and reliability of devices, but polycrystalline diamond films cannot perform the microfabrication required for device fabrication technology. It was not possible to use it. Furthermore, even when using electrical properties, it is obvious that polycrystalline films cannot be expected to have high mobility even if they are made into semiconductors due to surface irregularities, scattering at grain boundaries, carrier trapping, etc. That is, it is well known that hole or electron mobility is greatly influenced by crystal perfection. If a diamond single-crystal film without grain boundaries can be realized, a large mobility can be expected, and it will also be possible to apply microfabrication technology to fabricate devices, so its practical value is immeasurable. By the way, it is known that diamond single-crystal films can be grown on diamond single-crystal substrates, but the available diamond single-crystal substrates are only a few mm square at most, and their prices are high, making them impractical. . Therefore, there is a need for a technology for manufacturing single crystal diamond films on substrates other than diamond, such as semiconductor single crystal substrates such as silicon or gallium arsenide. There was no known substrate material that could do this. An object of the present invention is to provide a method for producing a diamond single crystal film that can be grown on a substrate other than diamond, while eliminating the various drawbacks of the conventional methods as described above. (Means for Solving the Problems) According to the present invention, a diamond single crystal film is manufactured by using an oxide single crystal film or an oxide single crystal film grown on a single crystal other than diamond as a substrate. can do. In addition, as an oxide single crystal, the chemical formula MgAl 2 O 4
Or MgO, which is a solid solution of MgO and Al 2 O 3
Magnesia spinel represented by nAl 2 O 3 (1≦n≦3.5) was used, and silicon was used as a single crystal substrate other than diamond, and magnesia spinel was deposited on the silicon substrate by chemical vapor deposition (CVD). It is effective to use a substrate on which a (MgAl 2 O 4 ) thin film is epitaxially grown. (Function) In general, the factors governing the epitaxial relationship between the substrate material and the thin film material that can be grown on it have not been fully elucidated to date, but the state of the atomic arrangement on the lattice plane on the surface of the substrate material The shape and form of the surface, as well as the physical and chemical interactions between the deposited substance and the substrate substance have a major influence. In other words, it is assumed that the growth of a thin film on a substrate proceeds through adsorption of the atomic species to be grown on the surface, bonding with the substrate atoms, and crystal nucleation and growth due to the dispersion of the adsorbed species on the surface. Technology that can control this process is needed. In epitaxial growth on a substrate, lattice matching between the substrate and the film material to be grown is particularly important. As a parameter indicating this, a quantity called misfit factor is used as a rough guide. That is, the period of atoms on the surface of the substrate ds
and the ratio of difference in the period df of the atoms of the film material (df−
ds)/ds is called a misfit factor, and it is said that epitaxial growth occurs when this amount is usually about 15% or less. However, in reality, there are cases of epitaxial growth even with materials exceeding 15%, so this is not a necessary and sufficient condition. Furthermore, when considering heteroepitaxial growth between a substrate material and a different material, it is known that an integral multiple of the atomic period of the substrate may match an integral multiple of the atomic period of the growing material. It is not clear whether this principle holds true for all substances. Regarding the heteroepitaxial growth of diamond, the present inventors aimed to match the period of the substrate surface atoms that have a large interaction with the carbon atoms that make up the diamond. The inventors came up with the idea that by using an oxide single crystal containing oxygen as a constituent element, which has a large amount of oxygen, it would be possible to control the surface diffusion of carbon atoms and grow a diamond single crystal film, which led to the present invention. . In the present invention, as described above, it is necessary that the arrangement period of the carbon atoms of the diamond and the arrangement period of the atoms of the oxide serving as the substrate can match. As is well known, diamond has a diamond structure, belongs to the space group Fd3m, and has a lattice constant of 3.5667 Å. On the other hand, consider magnesia pinel MgAl 2 O 4 as one of the substances belonging to the same space group as the oxide. The lattice constant of this material is
It is 8.0831 Å. The ionic radius of the elements constituting this material is Mg 2+ , Al 3+ and O 2- respectively.
At 0.78 Å, 0.57 Å, and 1.32 Å, the ionic radius of oxygen ions is approximately twice that of metal ions. Therefore, oxygen occupies a very large area on the surface of an oxide single crystal, and when diamond is grown in a vapor phase through the decomposition of hydrocarbon gas, not only the surface metal atoms but also the effect of oxygen are important. In other words, taking methane gas (CH 4 ) as an example, CH 3 * radicals or
It is thought that CH 3 ions are caused by an adsorption reaction between carbon atoms and substrate atoms on the substrate surface. The details of this process are unknown, but oxygen, a negative ion with a large ionic radius, and CH 3 + , a positive ion,
It is appropriate to consider that ions are more easily adsorbed and reacted. In other words, CH 3 + ions are arranged in a directional manner reflecting the directionality of oxygen, which is a negative ion, and diamond is heteroepitaxially formed on an oxide single crystal substrate through mechanisms such as hydrogen abstraction reaction and re-adsorption. It will grow. Next, regarding the matching factor of the lattice period, it is not necessarily necessary that the values of the lattice constants match, and as mentioned earlier, epitaxial growth can be achieved even if the integral multiples of each match. For the (100) plane of diamond and the (100) plane of magnesia spinel, the 9x lattice of diamond and the 4x lattice of spinel are 32.100 Å and 32.332 Å, respectively.
The misfit factor in Å is −0.7%,
It has extremely good lattice matching and satisfies epitaxial growth conditions. As mentioned above, the gist of the present invention is not necessarily limited to magnesia spinel, and it goes without saying that oxygen having a relatively large ionic radius can be brought into a state in which lattice matching can be achieved on the substrate surface. (Example) FIG. 1 shows an apparatus for manufacturing a diamond single crystal film used in the present invention. The manufacturing process of the diamond single crystal film is shown below. The substrate 1 is placed on the substrate support 2, the pot 3 is stopped, and the inside of the vacuum chamber 5 is preliminarily evacuated to 10 -5 Torr or less using the vacuum exhaust device 4. Reaction gas 6 mixed at a predetermined ratio is introduced into vacuum chamber 5 and set to a predetermined pressure by pressure regulating valve 7 . After raising the temperature of the substrate support 2 and the substrate 1 to a predetermined temperature using the infrared lamp 8, AC or DC current is applied to the current introduction terminal 9 to heat the thermal filament to 2000° C. or more, thereby causing a temperature drop on the substrate 1. A diamond single crystal film was grown. In order to easily increase the area, a configuration as shown in FIG. 2 was adopted. A large number of thermal filaments 1 were tightly stretched to achieve a large area, and uniformity was achieved by rotating and moving the substrate 3 placed on the substrate support stand 2 in a certain direction in the figure. The substrate used was a MgAl 2 O 4 (100) surface with a diameter of 30 mm.
MgAl 2 O 4 epitaxially grown on silicon (110) with (110) plane, (111) plane and 100 mm diameter.
(110). For the reaction gas, hydrogen-diluted methane or hydrogen-diluted acetone vapor is used as a carbon source, hydrogen-diluted B 2 H 6 is used to make a P-type semiconductor, and hydrogen-diluted PH 3 , hydrogen-diluted AsH 3 or hydrogen is used to make an N-type semiconductor. Diluted antimony vapor was used. Since the substrate temperature and the proportion of carbon in the reaction gas are considered to be conditions that affect single crystallization of diamond, we investigated the conditions under which a high quality diamond single crystal film can be obtained. As a result, the higher the substrate temperature (800° C. or higher) and the lower the proportion of carbon in the reaction gas (1% or less), the better the epitaxial diamond film was obtained. The structure of the film was evaluated by high-speed electron diffraction, and vertical streaks were observed in good epitaxial films, and both surface flatness and crystallinity were good. Table 1 shows the orientation of diamond single crystal films using various substrates and the mobility at room temperature measured by Hall effect measurements. Synthesis conditions were reaction gas (0.2% methane), pressure (30 Torr), substrate temperature (900°C), time (20 hours), and filament (tungsten, 2200°C).
°C), and the filament-to-substrate distance (10 mm).
Further, hydrogen diluted B 2 H 6 was used to make a P-type semiconductor, and AsH 3 was used to make an N-type semiconductor.
【表】
室温における天然ダイヤモンドのホール移動度
は1600cm2／Ｖ・sec、電子移動度1800cm2／Ｖ・sec
であることが知られているので、本発明によるダ
イヤモンド単結晶膜のホール及び電子移動度はほ
ぼ天然ダイヤモンド並みの大きな値であつた。電
気抵抗率は、絶縁性即ち不純物を添加しない状態
ですべて1015Ω・cm以上の高絶縁性を示した。一
方Ｐ型半導体膜で１〜10Ω・cm、Ｎ型半導体膜で
は不純物元素としてリンを添加した場合105〜106
Ω・cmと抵抗率が高く、アンチモン又はヒ素を添
加すると１〜10Ω・cmと抵抗率を下げることがで
きた。基板にシリコン（100）面を用いＰ型又は
Ｎ型多結晶ダイヤモンド膜を厚さ約200ミクロン
成長後、シリコン基板をエツチングして取り除き
移動度を調べると、ホール移動度及び電子移動度
共に数cm2／Ｖ・sec程度であり、本発明によるダ
イヤモンド単結晶膜の数百分の一程度であつた。
表面平滑性を触針式の表面荒さ計で評価する
と、多結晶ダイヤモンド膜の場合数ミクロンの凹
凸が観察されたが、単結晶では数百オングストロ
ームの凹凸で、ステツプ状となり表面平滑性は良
好であつた。
光透過率を調べる為に、波長可変レーザ光をプ
リズムにより膜中に導入し、膜中を多重回折させ
て出力光を調べた所、多結晶ダイヤモンド膜で
は、プリズムから膜中に光が導入せずたとえ導入
しても透過率は高々１〜２％であつたのに対し、
ダイヤモンド単結晶膜では赤外から紫外までのほ
とんどすべての波長で透過率は40〜50％とほぼ天
然ダイヤモンド単結晶と同様な値が得られた。
（発明の効果）
本発明によれば、ダイヤモンド以外の安価な基
板上に大面積でダイヤモンド単結晶膜が得られ
る。更に得られるダイヤモンド単結晶膜の表面は
極めて平坦にできるので、微細加工が可能となり
また、光学的性質の利用も可能である。更に半導
体化したダイヤモンド単結晶膜を使用した半導体
素子の作製も可能である。
更にシリコン等の半導体基板上に酸化物単結晶
膜を介してダイヤモンド単結晶膜が成長できシリ
コンデバイスの高性能化も可能となる等その実用
的価値は極めて大きい。[Table] The hole mobility of natural diamond at room temperature is 1600cm 2 /V・sec, and the electron mobility is 1800cm 2 /V・sec
Therefore, the hole and electron mobilities of the diamond single crystal film according to the present invention were almost as large as those of natural diamond. The electrical resistivity of all samples was insulating, that is, they exhibited high insulating properties of 10 15 Ω·cm or more without adding any impurities. On the other hand, when phosphorus is added as an impurity element to a P-type semiconductor film and 1 to 10 Ωcm to an N-type semiconductor film, it is 10 5 to 10 6
It has a high resistivity of Ω·cm, and by adding antimony or arsenic, it was possible to lower the resistivity to 1 to 10 Ω·cm. After growing a P-type or N-type polycrystalline diamond film to a thickness of approximately 200 microns using a silicon (100) surface as the substrate, the silicon substrate was removed by etching and the mobility was examined. Both hole mobility and electron mobility were several centimeters. 2 /V·sec, which was about one hundredth of that of the diamond single crystal film according to the present invention. When surface smoothness was evaluated using a stylus-type surface roughness tester, irregularities of several microns were observed in the case of polycrystalline diamond films, but irregularities of several hundred angstroms were observed in single-crystal diamond films, resulting in step-like surface smoothness. It was hot. In order to investigate the light transmittance, we introduced wavelength-tunable laser light into the film through a prism, caused multiple diffraction within the film, and examined the output light.We found that in polycrystalline diamond films, light was not introduced into the film through the prism. Even if they were introduced, the transmittance was only 1 to 2% at most.
The diamond single crystal film had a transmittance of 40 to 50% at almost all wavelengths from infrared to ultraviolet, which is almost the same value as natural diamond single crystal. (Effects of the Invention) According to the present invention, a diamond single crystal film can be obtained over a large area on an inexpensive substrate other than diamond. Furthermore, since the surface of the resulting diamond single crystal film can be made extremely flat, microfabrication is possible and optical properties can also be utilized. Furthermore, it is also possible to fabricate a semiconductor element using a semiconductor single crystal diamond film. Furthermore, it is of extremely great practical value, as it enables the growth of a diamond single crystal film on a semiconductor substrate such as silicon via an oxide single crystal film, thereby making it possible to improve the performance of silicon devices.
第１図および第２図は、本発明に用いたダイヤ
モンド単結晶膜の製造装置を示す図。
図において、１……基板、２……基板支持台、
３……コツク、４……真空排気装置、５……真空
槽、６……反応ガス、７……圧力調整バルブ、８
……赤外ランプ、９……電流導入端子、１０……
熱フイラント。
FIG. 1 and FIG. 2 are diagrams showing a diamond single crystal film manufacturing apparatus used in the present invention. In the figure, 1... substrate, 2... substrate support stand,
3... Kotoku, 4... Vacuum exhaust device, 5... Vacuum chamber, 6... Reaction gas, 7... Pressure adjustment valve, 8
...Infrared lamp, 9...Current introduction terminal, 10...
heat fillant.
Claims (1)
3.5）で示されるマグネシアスピネル単結晶を、
ダイヤモンド単結晶膜成長用基板として、もしく
は半導体単結晶基板上に単結晶膜として積層して
用いることを特徴とする、ダイヤモンド単結晶膜
の製造方法。1 MgAl 2 O 4 or MgO・nAl 2 O 3 (1≦n≦
3.5) The magnesia spinel single crystal shown in
A method for producing a diamond single crystal film, characterized in that the diamond single crystal film is used as a substrate for growing a diamond single crystal film or by being stacked as a single crystal film on a semiconductor single crystal substrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62-159330A JPH013098A (en) | 1987-06-25 | Manufacturing method of diamond single crystal film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62-159330A JPH013098A (en) | 1987-06-25 | Manufacturing method of diamond single crystal film |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JPS643098A JPS643098A (en) | 1989-01-06 |
| JPH013098A JPH013098A (en) | 1989-01-06 |
| JPH0527599B2 true JPH0527599B2 (en) | 1993-04-21 |
Family
ID=
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61106494A (en) * | 1984-10-29 | 1986-05-24 | Kyocera Corp | Member coated with diamond and its production |
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61106494A (en) * | 1984-10-29 | 1986-05-24 | Kyocera Corp | Member coated with diamond and its production |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS643098A (en) | 1989-01-06 |
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