JPS61146783A - Method for growing compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To obtain the titled single crystal having uniform composition by keeping a quartz ampule wherein component elements are enclosed at the melting temp., then changing the temp. rapidly to a specified temp. to grow a crystalline nucleus, and then cooling the ampule slowly. CONSTITUTION:Plural component elements which are mixed in a desired ratio are enclosed in a quartz ampule, and the ampule is kept at the melting temp. above the liq. phase line shown in the figure. Then the temp. is changed rapidly to a temp. between the liq. phase line and the solid phase line to generate a crystalline nucleus having the same composition as the melt, and the crystal is grown. The ampule is slowly cooled to continue the growth of the crystal, and the melt is transformed into a single crystal. By applying the modified Bridgman method to this method, the growth of a single crystal having the same composition with respect to a multi-element compd. semiconductor material is made possible, and hence the manufacture of a compd. semiconductor device is facilitated.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は変形ブリッジマン法を用いて所定の組成比をも
つ化合物半導体の単結晶を成長させる方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for growing a compound semiconductor single crystal having a predetermined composition ratio using a modified Bridgman method.

半導体にはシリコン（Ｓｉ）　、ゲルマニウム（Ｇｅ）
のような単体半導体とガリウム砒素（ＧａＡｓ）、イン
ジウム燐（Ｉｎ　Ｐ）のような化合物半導体とがあり、
これらの単結晶基板を用いて各種のデバイスが形成され
て使用されている。Semiconductors include silicon (Si) and germanium (Ge).
There are elemental semiconductors such as gallium arsenide (GaAs) and compound semiconductors such as indium phosphide (InP).
Various devices are formed and used using these single crystal substrates.

ここで半導体デバイスにはＩＣ，ＬＳＩなどのような電
子回路素子の他にホトトランジスタ、盪像素子（イメー
ジセンサ）のような光電素子があり、検知光の波長領域
を赤外にまで拡張するために上記の二元化合物半導体以
外にインジウム・砒素・アンチモン（Ｉｎ−Ａｓｉｂ）
や水銀・カドミウム・テルル（Ｈｇ　　−Ｃｄ−Ｔｅ）
などの三元化合物半導体を基板としてデバイスが形成さ
れている。In addition to electronic circuit elements such as ICs and LSIs, semiconductor devices include photoelectric elements such as phototransistors and image sensors, which expand the wavelength range of detected light to infrared. In addition to the above binary compound semiconductors, indium, arsenic, and antimony (In-Asib)
and mercury, cadmium, tellurium (Hg -Cd-Te)
Devices are formed using ternary compound semiconductors such as ternary compound semiconductors as substrates.

本発明はこのような多元化合物半導体単結晶の成長方法
に関するものである。The present invention relates to a method for growing such a multi-compound semiconductor single crystal.

〔従来の技術〕[Conventional technology]

単結晶を成長させる方法としてブリッジマン法がある。 The Bridgman method is a method for growing single crystals.

この方法は石英製で円錐形の底をもつ細管状のアンプル
に単結晶を成長させる材料を封入し、これを懸垂状態に
保持して溶融し、適当な温度勾配をもつ炉の中を移動さ
せるか或いは容器を固定したままで炉を移動させる。In this method, the material used to grow the single crystal is sealed in a narrow quartz ampoule with a conical bottom, held in a suspended state, melted, and moved through a furnace with an appropriate temperature gradient. Alternatively, move the furnace with the container fixed.

このようにすると温度の低いアンプルの下端でまず結晶
化が始まり、成長に都合のよい方位をもった結晶が太い
アンプルの部分に及んで次第に単結晶が成長し育成され
てゆく方法である。In this way, crystallization begins first at the lower end of the ampoule where the temperature is low, and crystals with a favorable orientation for growth reach the thick part of the ampoule, gradually growing into a single crystal.

然し三元以上の多数の元素からなる合金或いは化合物に
ついてはこの方法では一定の組成比の結晶を成長させる
ことはできない。However, this method cannot grow crystals with a fixed composition ratio for alloys or compounds consisting of a large number of ternary or higher elements.

例えばＣｄｘ　Ｈｇ＋−、Ｔｅからなる三元化合物につ
いてｘ＝０．２の化合物半導体材料を用いて単結晶を成
長させる場合を述べると次のようになる。For example, the case where a single crystal of a ternary compound consisting of Cdx Hg+- and Te is grown using a compound semiconductor material with x=0.2 is as follows.

図はＣｄｗ　Ｈｇ、、Ｔｅの組成をもつ化合物半導体の
状態図であって横軸にはＣｄの組成比Ｘがとってあり、
また縦軸には温度が目盛られている。The figure is a phase diagram of a compound semiconductor with a composition of Cdw Hg, Te, and the horizontal axis shows the composition ratio X of Cd.
Also, the temperature is scaled on the vertical axis.

ここで例えばｘ　＝０．２の組成比に混合されアンプル
に封入された材料は加熱溶融されるが、その際の融液の
組成は破線１で示される。Here, for example, the materials mixed to a composition ratio of x = 0.2 and sealed in an ampoule are heated and melted, and the composition of the melt at that time is indicated by a broken line 1.

次に平衡状態を保ちながら融液の温度を下げてゆき、ア
ンプル先端部にある融液の温度がａの温度（８００℃）
すなわち液相線２に達すると先端部の融液から結晶核が
発生するが、この結晶核の組成はａ点から水平に引いた
線が固相″ｆａ３に交わるｂ点の組成すなわちｘ＝０．
５２である。Next, the temperature of the melt is lowered while maintaining an equilibrium state, and the temperature of the melt at the tip of the ampoule reaches the temperature a (800°C).
In other words, when the liquidus line 2 is reached, a crystal nucleus is generated from the melt at the tip, but the composition of this crystal nucleus is the composition at point b, where a line drawn horizontally from point a intersects the solid phase "fa3", that is, x = 0 ．．
It is 52.

次に平衡状態を維持しながら融液の温度を下げてゆくと
結晶の組成はその温度の固相線３が示す組成比で、また
融液の組成は液相＆？ｉ　２の示す組成で変化してゆく
。Next, when the temperature of the melt is lowered while maintaining the equilibrium state, the composition of the crystal will be the composition ratio indicated by the solidus line 3 at that temperature, and the composition of the melt will be the liquid phase &? It changes with the composition indicated by i2.

例えば融液の温度が降下してＣの温度（７２０℃）にな
った場合は析出してくる結晶の組成は固相線３のｄ点の
示す組成すなわちｘ＝０．２４、また融液の組成は液相
線２のｅ点の組成すなわちｘ＝０゜０６である。For example, when the temperature of the melt drops to temperature C (720°C), the composition of the precipitated crystals is the composition indicated by point d of solidus line 3, that is, x = 0.24, and The composition is the composition at point e of liquidus line 2, that is, x=0°06.

このようにして単結晶が成長するがＣｄ、　Ｈｇ、−８
Ｔｅのように状態図で液相線と固相線とが離れている化
合物半導体では単結晶が成長するが所定の均一な組成比
の単結晶を得ることは不可能である。In this way, a single crystal grows, but Cd, Hg, -8
In a compound semiconductor such as Te, in which the liquidus line and the solidus line are far apart in the phase diagram, a single crystal grows, but it is impossible to obtain a single crystal with a predetermined uniform composition ratio.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

以上説明したように従来のブリッジマン法では構成元素
が三種類以上の化合物半導体については組成比が全域に
互って一定な単結晶を成長させることができないことが
問題である。As explained above, the problem with the conventional Bridgman method is that it is not possible to grow a single crystal with a constant composition ratio over the entire region for compound semiconductors containing three or more types of constituent elements.

〔問題点を解決するための手段〕[Means for solving problems]

上記の問題は希望する組成比に混合した複数の構成元素
を石英アンプルに封入し、該アンプルを前記組成比の状
態図が示す液相線以上の融解温度に保持した後、該温度
より液相線と固相線との間の温度まで急激に変化せしめ
て融液の組成比に近い組成比を持つ単結異核を発生させ
ると共に該結晶核を成長せしめ、その後に該アンプルを
徐冷して結晶成長を続け、該融液を単結晶化せしめるこ
とを特徴とする化合物半導体単結晶の成長方法により解
決することができる。The above problem is solved by sealing a plurality of constituent elements mixed in a desired composition ratio in a quartz ampoule, holding the ampoule at a melting temperature higher than the liquidus line shown in the phase diagram of the composition ratio, and then The temperature is suddenly changed to a temperature between the line and the solidus line to generate a single crystal nucleus having a composition ratio close to that of the melt, and the crystal nucleus is allowed to grow, and then the ampoule is slowly cooled. This problem can be solved by a method for growing a compound semiconductor single crystal, which is characterized in that the crystal growth is continued to make the melt into a single crystal.

〔作用〕[Effect]

本発明はＣｄ、　Ｈｇ、ＸＴｅのような化合物半導体は
相互拡散が起こり易く、結晶の成長が比較的容易であり
、また再結晶化し易い材料であることに着目してなされ
たもので、平衡状態を維持することなく急冷することに
よって偏析を無くし、混合比の組成の侭の単結晶を複数
個発生せしめる。The present invention was made based on the fact that compound semiconductors such as Cd, Hg, and XTe are materials that are easily interdiffused, relatively easy to grow crystals, and easy to recrystallize. Segregation is eliminated by rapid cooling without maintaining the mixture ratio, and a plurality of single crystals with different compositions are generated.

続いて成長アンプルを降下させながら一端から徐冷し、
融液との共存状態でから再結晶化することによって結晶
を成長させる手法をとる。Next, the growth ampoule is lowered and gradually cooled from one end.
A method is used to grow crystals by recrystallizing them in a state of coexistence with the melt.

すなわち徐冷の段階で急冷時に発生した小結晶群は大結
晶に統合されて単結晶化する。That is, during the slow cooling stage, small crystal groups generated during rapid cooling are integrated into large crystals and become single crystals.

この結晶成長過程において徐冷の段階で結晶化してくる
結晶の組成は偏析によって当初析出した結晶組成とは異
なっているが単結晶化後の構成元素の相互拡散によって
組成比のずれは徐冷の段階で解消し、組成比が均一な単
結晶を得ることができる。In this crystal growth process, the composition of the crystal that crystallizes during the slow cooling stage is different from the crystal composition that initially precipitated due to segregation, but the deviation in the composition ratio due to mutual diffusion of the constituent elements after single crystallization is caused by slow cooling. This can be resolved in stages and a single crystal with a uniform composition ratio can be obtained.

〔実施例〕〔Example〕

縦型の分割炉で下側が低い温度勾配をもつ炉を用い、石
英製の縦長のアンプルにＣｄ、　Ｈｇ、Ｊｅ但しｘ　＝
０．２の組成比の原料を混合封入したものを用いて単結
晶を成長させた例を状態図を用いて説明する。Using a vertical split furnace with a low temperature gradient at the bottom, Cd, Hg, Je, where x =
An example in which a single crystal is grown using a mixture of raw materials having a composition ratio of 0.2 will be described using a phase diagram.

アンプル内の融液の温度が液相領域の温度、この場合は
破線１のｇ点の温度（８２０℃）に約８時間保持した後
、アンプル全体の温度が０点の温度（７２０℃）になる
位置にまで急速に移動させた。After the temperature of the melt in the ampoule is maintained at the temperature of the liquid phase region, in this case the temperature of point g (820°C) of broken line 1, for about 8 hours, the temperature of the entire ampoule reaches the temperature of point 0 (720°C). It was quickly moved to a certain position.

この場合に析出した結晶の組成比は融液の組成比に近い
。In this case, the composition ratio of the precipitated crystals is close to that of the melt.

その後約０．２ｍｍ／時の微少速度でアンプルを降下さ
せることによって結晶成長を行わせ、アンプル内の融液
を結晶化させた。Thereafter, crystal growth was performed by lowering the ampoule at a very low speed of about 0.2 mm/hour, and the melt in the ampoule was crystallized.

このようにして得られた結晶を縦に分割して調べてみる
と単結晶化しており、また成長結晶から位置を変えて試
料を採取し組成比を分析した結果は何れも同一であった
。When the thus obtained crystal was vertically divided and examined, it was found that it had become a single crystal, and when samples were taken from different positions from the growing crystal and analyzed for composition ratio, the results were the same.

このことは徐冷過程において再結晶化と成分原子の拡散
が充分に行われていることを示すものである。This indicates that recrystallization and diffusion of component atoms are sufficiently carried out during the slow cooling process.

なおこの例証として次に状態図で破ｖ！１のｇの温度（
８２０℃）にアンプルを先と同様に８時間保持した後、
アンプルの先端部をｈの温度にまで急速に変え、先端部
の融液を総て結晶化させ、以後光と同様な条件で徐冷を
行ったが、この場合でも単結晶化と均一組成化を達成す
ることができた。As an illustration of this, we will use the following state diagram: 1 g temperature (
After holding the ampoule at 820°C for 8 hours as before,
The temperature at the tip of the ampoule was rapidly changed to h, all of the melt at the tip was crystallized, and then slow cooling was performed under the same conditions as with light, but even in this case, single crystallization and uniform composition were achieved. was able to achieve this.

〔発明の効果〕〔Effect of the invention〕

以上記したように本発明に係る変形ブリッジマン法の実
施により多元組成の化合物半導体材料について同一組成
をもつ単結晶の成長が可能となり、これにより化合物半
導体デバイスの製造が容易となる。As described above, by implementing the modified Bridgman method according to the present invention, single crystals having the same composition can be grown for compound semiconductor materials having multiple compositions, thereby facilitating the manufacture of compound semiconductor devices.

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

図はＣｄ、　Ｈｇ、−、Ｔｅ化合物半導体の状態図であ
る。 図において、 ２は液相線、　　　　　　　３は固相線、である。The figure is a state diagram of Cd, Hg, -, Te compound semiconductors. In the figure, 2 is a liquidus line, and 3 is a solidus line.

Claims (1)

【特許請求の範囲】[Claims] 希望する組成比に混合した複数の構成元素を石英アンプ
ルに封入し、該アンプルを前記組成比の状態図が示す液
相線以上の融解温度に保持した後、該温度より液相線と
固相線との間の温度まで急激に変化せしめて融液の組成
比を持つ結晶核を発生させると共に該結晶核を成長せし
め、その後に該アンプルを徐冷して結晶成長を続け、該
融液を単結晶化せしめることを特徴とする化合物半導体
単結晶の成長方法。A plurality of constituent elements mixed at a desired composition ratio are sealed in a quartz ampoule, and the ampoule is held at a melting temperature higher than the liquidus line indicated by the phase diagram of the composition ratio, and then the liquidus line and solid phase are The ampoule is then slowly cooled to continue crystal growth, and the ampoule is gradually cooled to continue the crystal growth, and the melt A method for growing a compound semiconductor single crystal, characterized by forming a single crystal.