JPS6197191A - Process for growing thin film of epitaxial single crystal - Google Patents

Abstract

PURPOSE:To obtain the titled thin film having low degree of defect and contg. different element in high concentration by irradiating a constitutional element of an epitaxial single crystal with a specified element and forming solid solution by heating the surface for a short time by irradiating simultaneously with energy beam intermittently and repeatedly. CONSTITUTION:A wafer of a constitutional element (e.g. Si) of an epitaxial single crystal thin film is inserted to a molecular beam epitaxial growth device, and irradiated with Si beam and beam of an element (e.g. Ga) for forming solid solution, simultaneously to continue epitaxial growth, then irradiated with energy beam (e.g. Ar laser) pulsatorily for a short time to heat the surfacial layer extremely close the surface (e.g. 0.1-0.3mum) alone to form solid solution and to activate. By repeating the procedures, the titled thin film having large thickness and contg. a useful different element in the form of solid solution at high concn. concn. is obtd.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は、薄膜型電子部品の基板として広く活用される
。特に半導体装置においても応用し得る。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is widely utilized as a substrate for thin film electronic components. In particular, it can be applied to semiconductor devices.

従来例の構成とその問題点 低温での単結晶薄膜の形成は種々の電子部品材料として
の応用があり、そのため、各種の方式が提案されテイル
。Ｉ、ＰＣＶＤ、ＰＥＣＶＤ、ＭＢＥなｇがある。Conventional configurations and problems The formation of single-crystal thin films at low temperatures has applications in various electronic component materials, and various methods have been proposed for this purpose. There are I, PCVD, PECVD, and MBE.

工業的に確立された技術であるＬＰＣＶＤ法によるエピ
成長では、一般的に１０６０℃以上、望ましくは１１０
０°Ｃ以上の温度が必要であシ、このため、基板構成元
素の相互拡散が顕著であり、この低減が大きな問題点と
なっていた。In epitaxial growth using the LPCVD method, which is an industrially established technology, the temperature is generally 1060°C or higher, preferably 110°C.
A temperature of 0° C. or higher is required, and as a result, mutual diffusion of the constituent elements of the substrate is significant, and reduction of this has been a major problem.

又、技術的には進展してきたＭＢＥ（分子線エピ）法に
おいても、６００’Ｃ程度の低温で、エピ成長が可能と
なってきたが、高濃度に、Ｇａ　、　Ｓｂ等の必須構成
元素を導入し得ない状態にある。これは欠陥を低減し、
析出させない状態にＧａ　、　Ｓｂ等を導入するには基
板を高温にしなければならないが、高温にすると、Ｇａ
、Ｓｂなどの耐着係数が大巾に減少し、（１００°Ｃで
１桁以上変化する。）従って高濃度にし得ないといった
矛盾がある。この改善のため、イオン化法などが試みら
れているが、十分な効果を得ていない。Furthermore, with the technologically advanced MBE (molecular beam epitaxy) method, it has become possible to perform epitaxial growth at a low temperature of about 600'C. It is in a state where it cannot be introduced. This reduces defects and
In order to introduce Ga, Sb, etc. in a state where they do not precipitate, the substrate must be heated to a high temperature, but if the temperature is raised, Ga
There is a contradiction in that the adhesion resistance coefficients of , Sb, etc. decrease drastically (change by more than one order of magnitude at 100° C.), and therefore cannot be made to a high concentration. Ionization methods have been attempted to improve this problem, but have not been sufficiently effective.

発明の目的 本発明は、以上の低温、高濃度固溶を両立させ、欠陥の
少ない、良質のエピ単結晶薄膜を提供することにある。OBJECTS OF THE INVENTION The object of the present invention is to provide a high-quality epitaxial single-crystal thin film that is compatible with the above-mentioned low temperature and high concentration solid solution, and has few defects.

発明の構成 本発明は、エピ単結晶薄膜の構成元素、主たる元素及び
導入すべき元素を低温で高濃度に導入する。この時、間
けつ的に極く短時間のみ表面層にエイ、ルギービーム（
例えばレーザ光、電子線）を照射して吸収せしめ、その
結果、極く表面層のみを高温に短時間熱し、この効果に
よって、高濃度に導入されている元素の固溶化、活性化
を行う。Structure of the Invention According to the present invention, constituent elements, main elements, and elements to be introduced into an epitaxial single crystal thin film are introduced in high concentration at low temperature. At this time, rays and lugie beams (
For example, laser light, electron beam) is irradiated and absorbed, and as a result, only the very surface layer is heated to a high temperature for a short period of time, and this effect causes the elements introduced at a high concentration to become a solid solution and become activated.

次の瞬間には冷却され、元の基板温度に戻シ、引き続き
高濃度の元素導入を行う。In the next moment, the substrate is cooled down to return to its original temperature, and elements are subsequently introduced at a high concentration.

以上の操作を繰り返すことにより、厚い、高濃度に有用
な異種元素の固溶したエピ成長単結晶薄膜が形成される
。By repeating the above operations, a thick epitaxially grown single crystal thin film in which a useful foreign element is dissolved in a solid solution at a high concentration is formed.

実施例の説明 エピ単結晶薄膜の評価が非常に進んでおシ、その品質を
非常に厳しく評価できるＳｉのエピ成長を例にとって説
明する。さらにその中でも欠陥が生じ易すい（１１１）
面を使用する。DESCRIPTION OF EMBODIMENTS The following describes an example of epitaxial growth of Si, where the evaluation of epitaxial single crystal thin films is very advanced and its quality can be evaluated very strictly. Furthermore, defects are more likely to occur among them (111)
Use the surface.

分子線エピ成長装置にＮ（１１１）２−４ΩｍのＳｉ　
ウェハーを挿入し、先ず、８５０’Ｃ，２分間Ｓｉ　　
ビームを０．２人／Ｓ照射することによって清浄化した
。この後、温度を６００〜７ｏＱ′Ｃに下け、Ｓｉ　　
ビームを３八／Ｓに増やし、且つ、クヌーセンセルから
Ｇａ　ビームを同時に照射せしめた。N(111) 2-4Ωm Si in molecular beam epitaxial growth equipment
Insert the wafer and first heat the Si at 850'C for 2 minutes.
Cleaning was performed by irradiating the beam at 0.2 persons/S. After this, the temperature was lowered to 600~7oQ'C, and the Si
The beam was increased to 38/S, and a Ga beam was simultaneously irradiated from the Knudsen cell.

セル温度は６５０〜８６０°Ｃに種々変化させた。The cell temperature was varied from 650 to 860°C.

この状態でエピ成長を続け、厚さ約１μｍに成長した後
、ジルトールエッチによシ、欠陥を検査した。なお濃度
についてはシート抵抗値から計算した。Ｇａを共存させ
ない場合には、積層欠陥密度（Ｓ、Ｆ、Ｄ・）及び微小
欠陥密度（Ｅ、Ｐ、Ｄ、）は共に１♂／　ｃｒｄ以下の
非常に小さい観察限界以下であったのに対して、以上の
例では、重大な欠陥であるＳＦＤでも、第１図に示すよ
うに、Ｇａ濃度が高くなるにつれ、１ｏ５／１０８／ｃ
ｄと急増している。Epitaxial growth was continued in this state, and after the film had grown to a thickness of about 1 μm, it was subjected to dilthole etching and inspected for defects. Note that the concentration was calculated from the sheet resistance value. When Ga was not coexisting, both the stacking fault density (S, F, D) and micro defect density (E, P, D,) were below the very small observation limit of 1♂/crd. On the other hand, in the above example, even in SFD, which is a serious defect, as the Ga concentration increases, as shown in Figure 1, 1o5/108/c
d, which is rapidly increasing.

ＥＰＤについてはこの１０〜５０倍存在している。EPD is present 10 to 50 times more than this.

これに対し、本発明では上記のエピ成長中にアルゴンレ
ーザ（波長的０．５μｍ）をパルス状に照射せしめた。In contrast, in the present invention, argon laser (wavelength: 0.5 μm) is irradiated in a pulsed manner during the epitaxial growth.

１パルス当シ約ｏ、ｓｌ／ｃＡを３０秒に１度照射した
。この結果、ＳＦＤはほぼ観察されなくなり第２図に示
すように、Ｅ、Ｐ、Ｄ、においても１〜２桁にのぼるか
なりの改良がみられた。Approximately 0, sl/cA per pulse was irradiated once every 30 seconds. As a result, SFD was almost no longer observed, and as shown in FIG. 2, significant improvements of 1 to 2 orders of magnitude were observed in E, P, and D.

次にＰ（１１１）３〜ｓΩｍのＳｔ　ウェハーを用いて
、同様の実験を行った。清浄化は８００’Ｃ１分３０秒
、Ｓｔ　　ビーム照射０．３八／Ｓで行ないエピ成長温
度を６００〜７００℃、Ｓｉ　　ビーム４八／Ｓ　、Ｓ
ｂ用のクヌーセンセル温度２６ｏ−３００’Ｃの範囲で
種々に変化させたエピ単結晶薄膜の評価結果を第３図に
示す。Ｇａよシも（第１図）少し減少しているが、ＳＦ
Ｄは非常に多い。Next, a similar experiment was conducted using a St wafer with P(111)3 to sΩm. Cleaning was performed at 800'C for 1 minute and 30 seconds, St beam irradiation at 0.38/S, epitaxial growth temperature at 600-700°C, Si beam at 48/S, S.
FIG. 3 shows the evaluation results of epitaxial single crystal thin films at various Knudsen cell temperatures ranging from 26o to 300'C. Ga Yoshi (Figure 1) has also decreased slightly, but SF
There are a lot of D's.

これに対し、本発明では、連続発振型アルゴンレーザ照
射（ビーム径１００μｍφ、走査速度１　ｍ／Ｓｅｃ　
。In contrast, in the present invention, continuous wave argon laser irradiation (beam diameter 100 μmφ, scanning speed 1 m/Sec
.

ビーム出力９Ｗ、走査ステップ２００μｍのインターレ
ース方式、走査範囲５ｃｒｎ角）を同時に施こしながら
ｓｂ照射を行った所、ＳＦＤはほぼ皆無となり、Ｅ、Ｐ
、Ｄ、においても１ｏ／ｃｒＩｉ以下に下がるなどの大
巾な改良が認められた。When sb irradiation was performed while simultaneously applying a beam output of 9 W, an interlace method with a scanning step of 200 μm, and a scanning range of 5 crn angle), there was almost no SFD, and E, P
, D also showed a significant improvement, such as a decrease to 1o/crIi or less.

以上の大巾な改良の原理を次に推測する。前述したよう
に、高濃度に異種元素を導入するには、例えば第５図に
示すように、Ｇａ、Ｓｂのいずれにしても低温にしなく
てはならない。温度が１００°Ｃ上昇すると耐着係数は
ほぼ１．６桁低下する。ところが、このような高濃度に
低温で異種元素を導入すると、格子間に析出し易すく、
これが大きな否を生じ、欠陥を生ずる。当初微小欠陥で
あったものが、成長と共に大きくなり、積層欠陥として
明白に認められるようになる。欠陥を防止するためには
、高温にすればよいが、高温にすれば、濃度をあげるこ
とができないという矛盾が生じている。The principle of the above-mentioned drastic improvement is speculated as follows. As mentioned above, in order to introduce a different element at a high concentration, the temperature must be lowered to either Ga or Sb, as shown in FIG. 5, for example. When the temperature increases by 100°C, the adhesion resistance coefficient decreases by approximately 1.6 orders of magnitude. However, when foreign elements are introduced at such high concentrations at low temperatures, they tend to precipitate between the lattices.
This causes major failures and defects. What was initially a microscopic defect becomes larger as it grows, and becomes clearly recognized as a stacking fault. In order to prevent defects, it is sufficient to raise the temperature, but a contradiction arises in that if the temperature is raised, the concentration cannot be increased.

一方、上述のような短時間のごく表面層の加熱を考える
。レーザのエネルギーは極く表面層のみに吸収され、表
面の０．１〜０．３μｍ位までの厚さで顕著な温度上昇
が生ずると推定される。この温度上昇は、第６図に一例
を示すように、基板温度６００°Ｃから０．２ｍ５ｅＣ
位で１０００′Ｃ程度に上昇し、５ｍ５ｅＣ位でほぼ元
のｅ　ｏ　Ｏ”Ｃに戻ると推定される。On the other hand, consider heating the very surface layer for a short time as described above. It is estimated that the laser energy is absorbed only in the surface layer, and a significant temperature increase occurs in the thickness of about 0.1 to 0.3 μm on the surface. This temperature rise is 0.2m5eC from the substrate temperature of 600°C, as shown in Fig. 6.
It is estimated that the temperature rises to about 1000'C at about 5m5eC and returns to almost the original e o O'C at about 5m5eC.

この高温になっている時間、約１　ｍ５ｅｃは、−周期
の基板温度にある時間、約３０秒に対しては１／３０．
０００の短時間である。即ち、低温の基板温度で高濃度
に異種元素が導入されるが、高温では逆にほとんど陰暦
しない。このため、原理的には濃度が幾分低下すること
になるが、その量は全く無視できる量である。所が、こ
の短時間の高温処理の効果は、欠陥からみると大きな効
果がある。The time during which the temperature is at this high temperature, approximately 1 m5ec, is 1/30 of the time during which the substrate temperature is at a -period, approximately 30 seconds.
000 for a short time. That is, a foreign element is introduced at a high concentration at a low substrate temperature, but on the contrary, there is almost no lunar calendar at a high temperature. Therefore, in principle, the concentration will decrease somewhat, but the amount is completely negligible. However, the effect of this short-time high-temperature treatment is significant in terms of defects.

即ち、高温になシ、瞬時に格子振動が大きくなると同時
に、異種元素を格子内に取り込んで固溶してしまい、又
、微小欠陥核を焼鈍してしまう。That is, if the temperature is not high, the lattice vibration becomes large instantaneously, and at the same time, foreign elements are incorporated into the lattice and form a solid solution, and micro defect nuclei are annealed.

以上の操作により、異種元素の析出や微小欠陥核が成長
しない点ですべて消去することができる。The above operations can completely eliminate the precipitation of foreign elements and the growth of microdefect nuclei.

そのため、優れたエピ単結晶薄膜が形成されると考えら
れる。Therefore, it is considered that an excellent epitaxial single crystal thin film is formed.

なお、以上の説明で明らかになったように、エネルギー
ビームとしては電子線でもよい。Note that, as has been made clear from the above explanation, the energy beam may be an electron beam.

発明の効果 以上の説明で明らかなように、本発明の方法によシ、高
濃度に異種元素を含有し、且つ低欠陥であるエピ成長単
結晶薄膜を形成することができた。Effects of the Invention As is clear from the above explanation, the method of the present invention was able to form an epitaxially grown single crystal thin film containing a high concentration of a different element and having a low number of defects.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図〜第４図にそれぞれＧａ、Ｓｂを異種元素として
導した場合の、従来例２本発明例における欠陥密度を示
す図、第５図は耐着係数の温度依存性を、第６図はレー
ザ照射後の試料表面の温度変化を示す図である。 第１図 一一−ｉ濃友 第２図 一一φら係度 第　３　ｒＭ −５ｂ　Ｊ浅 Ｓｂ　ｙｋ度 第　５　因 第６図 □う】Ｖノｌ　＜、０ｃノFigures 1 to 4 are diagrams showing the defect density in the conventional example and the present invention example when Ga and Sb are introduced as different elements, Figure 5 shows the temperature dependence of the adhesion resistance coefficient, and Figure 6 shows the temperature dependence of the adhesion resistance coefficient. FIG. 2 is a diagram showing temperature changes on the sample surface after laser irradiation. Fig. 1 1-i No. 2 Fig. 11 φ et coefficient 3rd rM -5b J shallow Sb yk degree 5th factor Fig. 6 □ U] V nol <, 0c no

Claims (1)

【特許請求の範囲】[Claims] エピ単結晶の構成元素それに固溶すべき元素を照射する
と同時に、間けつ的に繰り返しエネルギービームを照射
し、極く表面を短時間加熱することを特徴としたエピ単
結晶薄膜の形成方法。A method for forming an epitaxial single crystal thin film characterized by irradiating constituent elements of the epitaxial single crystal with elements to be solid-dissolved and at the same time irradiating an energy beam repeatedly intermittently to heat the surface for a very short period of time.