JPH0633227B2 - Liquid phase epitaxial growth system - Google Patents

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、液相エピタキシャル成長装置、特に異種の成
長層を複数形成する場合の各成長層厚および境界面の制
御を行なう結晶成長用スライドボートの構造に関する。The present invention relates to a liquid phase epitaxial growth apparatus, and more particularly to a crystal growth slide boat for controlling the thickness of each growth layer and the boundary surface when a plurality of different growth layers are formed. Concerning the structure of.

〔従来の技術〕[Conventional technology]

半導体レーザダイオードの結晶成長には、オーバシード
ウォッシュメルト法が用いられている。すなわち、成長
層厚を制御するためには基板結晶への成長前に成長用溶
液に飽和度の調整用として板状の種結晶（オーバシー
ド）を載置して薄層溶液を形成し、溶液が過飽和である
ために生ずる不安定な急激成長および成長に寄与しない
生成核の発生を抑える方法である。さらに組成制御のた
めには先の成長層の成長面に残った溶液を次に成長せし
めようとする溶液と同じ組成の溶液（以下洗浄液又はウ
ォッシュメルトと称する）で洗浄して、溶液の混りによ
る成長層境界面での組成のバラツキを防止していた。し
かし、従来の方法においては第３図（ａ）および（ｂ）
に示すように、洗浄溶液３４には溶液の過飽和度調整用
のオーバシードが配置されないために、先の成長層を得
るための降温中に洗浄溶液３４の中に成長に寄与しない
核が発生し、結晶欠陥の原因になることが発明者等の研
究で明らかになり、第２図（ａ），（ｂ）に示す洗浄溶
液２３ａ，２３ｂにオーバシート２６ａ，２６ｂを載置
する方法および構造が提案された（特願昭５５−１５８
６９６）。The overseed wash melt method is used for crystal growth of a semiconductor laser diode. That is, in order to control the thickness of the growth layer, a plate-like seed crystal (overseed) is placed on the growth solution for adjusting the saturation before the growth to the substrate crystal to form a thin layer solution. Is a method of suppressing the unstable rapid growth caused by supersaturation and the generation of nuclei that do not contribute to the growth. Furthermore, in order to control the composition, the solution remaining on the growth surface of the previous growth layer is washed with a solution having the same composition as the solution to be grown next (hereinafter referred to as a washing solution or wash melt), and the solution is mixed. It was possible to prevent the compositional variation at the boundary surface of the growth layer due to. However, in the conventional method, FIGS. 3 (a) and 3 (b) are used.
As shown in Fig. 3, since the cleaning solution 34 is not provided with an overseed for adjusting the degree of supersaturation of the solution, nuclei that do not contribute to growth are generated in the cleaning solution 34 during the temperature decrease for obtaining the previous growth layer. It has become clear by the research of the inventors that this causes crystal defects, and a method and structure for placing the oversheets 26a and 26b on the cleaning solutions 23a and 23b shown in FIGS. Proposed (Japanese Patent Application No. Sho 55-158)
696).

〔発明が解決しようとする問題点〕[Problems to be solved by the invention]

従来方法の場合、薄層溶液形成のための溶液槽のスライ
ド（以下メルトカットと称する）の際に洗浄用オーバシ
ードおよび成長用オーバシードの両者に、一度のメルト
カット操作で同一溶液を全面にわたって一様に接触せし
めることが困難であった。すなわち、第２図（ａ）に示
すように、溶液は洗浄用オーバシード２６ａ，２６ｂに
接触し、残りが成長用オーバシード２７ａ，２７ｂに導
入されるため、第２図（ｂ）のように成長用溶液２４
ａ，２４ｂが局部的にしかオーバシード２７ａ，２７ｂ
に接触しない“ぬれ不良”が発生し、メルトカットによ
るオーバシードのぬれの再現性が悪かった。In the case of the conventional method, when the solution tank slide (hereinafter referred to as melt cut) for forming a thin layer solution is formed, the same solution is applied to both the cleaning overseed and the growth overseed in a single melt cut operation. It was difficult to make uniform contact. That is, as shown in FIG. 2 (a), the solution comes into contact with the cleaning overseed 26a, 26b and the rest is introduced into the growth overseed 27a, 27b, so that as shown in FIG. 2 (b). Growth solution 24
a and 24b are locally overseeded 27a and 27b
"Wet failure" that did not touch the touch screen occurred, and the reproducibility of wetness of the overseed due to melt cutting was poor.

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

本発明は、溶媒用浴槽と、洗浄用溶液を形成するための
浴槽と、成長用薄層溶液を形成するための浴槽と、溶液
分離板と、基板結晶スライド板とを有し、洗浄用および
成長用浴槽の一部に洗浄用溶液と成長用溶液の飽和度調
整用種結晶を洗浄用溶液の液厚が成長用溶液の液厚より
厚くなる様に格納し、浴槽を溶液分離板と相対的に移動
させることによって種結晶が載置された洗浄用溶液およ
び成長用溶液を実現するようにして液相エピタキシャル
成長装置である。The present invention has a bath for solvent, a bath for forming a cleaning solution, a bath for forming a thin layer solution for growth, a solution separation plate, and a substrate crystal slide plate for cleaning and The washing solution and the seed crystal for adjusting the saturation of the growth solution are stored in a part of the growth bath so that the thickness of the washing solution is thicker than that of the growth solution, and the bath is separated from the solution separation plate. It is a liquid phase epitaxial growth apparatus that realizes a cleaning solution and a growth solution on which a seed crystal is placed by moving the seed crystal.

〔実施例〕〔Example〕

本発明を半導体レーザダイオードの液相成長に適用した
一実施例を図面を参照して述べる。An embodiment in which the present invention is applied to liquid phase growth of a semiconductor laser diode will be described with reference to the drawings.

第１図（ａ）は成長前の液相成長用ボートの断面図であ
り、簡単のため第１層と第２層に溶液が配置された様子
を示すものである。成長の詳細は、特願昭５３−４９２
６に述べられているので要点だけ述べる。FIG. 1 (a) is a cross-sectional view of the liquid phase growth boat before growth, and shows a state in which the solutions are arranged in the first layer and the second layer for simplification. For details of growth, see Japanese Patent Application No. 53-492.
As described in No. 6, only the main points will be described.

例えば、第１層，第２層用として溶媒Ga，溶質GaAsとＡ
ｌ、不純物としてのTeおよびMgをあらかじめ溶解度曲線
から求められる必要量を秤量し、第１層用浴槽１１ａと
第２層用浴槽１１ｂに投入配置し、さらに基板結晶１９
および各層の洗浄液用および成長液用オーバシード１６
ａ，１６ｂ，１７ａ，１７ｂをオーバシード格納浴槽１
４に配置する。第１図（ａ）の状態で溶媒Gaを水素雰囲
気中で約８００℃、２Ｈ保持し酸化膜等の汚染物を還元
し、その後、溶液仕切り板１３を移動せしめると、第１
図（ｂ）に示すごとく溶液だめの穴を通じて、溶媒Gaが
導入され洗浄液用のオーバシード１６ａ，１６ｂに接触
する。この状態でさらに２〜３Ｈ保持することによって
投入したGaおよびＡｌの量によって決まるGaAsが溶解す
る。For example, solvent Ga, solute GaAs and A for the first and second layers
1, Te and Mg as impurities are weighed in a required amount obtained from the solubility curve in advance, placed in the first layer bath 11a and the second layer bath 11b, and placed in the substrate crystal 19
And overseed 16 for cleaning liquid and growth liquid for each layer
a, 16b, 17a, 17b are overseed storage tub 1
Place in 4. In the state of FIG. 1 (a), the solvent Ga is kept in a hydrogen atmosphere at about 800 ° C. for 2H to reduce contaminants such as an oxide film, and then the solution partition plate 13 is moved.
As shown in FIG. 6B, the solvent Ga is introduced through the holes of the solution reservoir and comes into contact with the overseed 16 a and 16 b for the cleaning liquid. In this state, by further holding for 2 to 3 H, GaAs, which is determined by the amounts of Ga and Al, is melted.

その後、第１図（ｃ）に示す様にオーバシード格納浴槽
１４を矢印の方向に移動せしめるメルトカット操作によ
って溶液１２ａ，１２ｂが移動し、第１図（ｄ）に示す
位置で各オーバシード１６ａ，１６ｂおよび１７ａ，１
７ｂが洗浄用溶液４１ａ，４１ｂおよび成長用薄層溶液
４２ａ，４２ｂ上方に配置され、飽和度の調整が図られ
る。溶液の均一な平行状態を得るに必要な時間（約１〜
３Ｈ）保持した後に、第１層ｐ−ＡｌGaAsの成長温度ま
で一定の降温速度（0.1〜0.3℃／min）で降温する。こ
の過程で各溶液においてオーバシードが核の生成を定常
状態にするための飽和度調整機能を担い基板結晶への析
出は安定な量となり、成長に寄与しない核の発生を抑え
る。降温によって第１層ｐ−ＡｌGaAs成長開始温度に達
したならば第１図の基板スライド板１８を矢印の方向に
移動して、第１層成長用薄層溶液４２ａの下側に基板結
晶１９を位置せしめる。基板結晶１９の表面には、核生
成が安定した溶液であるために一定の成長速度で結晶成
長が行なわれる。１〜３℃降温し第１層を所定の層厚
（0.2〜２μｍ）を成長せしめた後、基板結晶１９を移
動せしめ第２層ｐ−GaAs成長用薄層溶液４２ｂの下部に
停止配置する。その移動の際第１図（ｄ）の洗浄用溶液
４１ｂを通過するが、前述したように洗浄用溶液におい
てもオーバシードが載置されているため従来のように多
量の生成核が第１層成長表面に付着せず欠陥のない良質
の結晶表面が得られる。Thereafter, as shown in FIG. 1 (c), the solutions 12a and 12b are moved by a melt cut operation for moving the overseed storage bath 14 in the direction of the arrow, and each of the overseed 16a is moved at the position shown in FIG. 1 (d). , 16b and 17a, 1
7b is arranged above the cleaning solutions 41a and 41b and the growth thin layer solutions 42a and 42b to adjust the degree of saturation. The time required to obtain a uniform parallel state of the solution (about 1 to
3H), the temperature is lowered to the growth temperature of the first layer p-AlGaAs at a constant temperature decreasing rate (0.1 to 0.3 ° C./min). In this process, in each solution, the overseed has a saturation adjusting function for making the nucleation steady state, and the precipitation on the substrate crystal becomes a stable amount, thereby suppressing the generation of nuclei that do not contribute to the growth. When the first layer p-AlGaAs growth start temperature is reached by lowering the temperature, the substrate slide plate 18 of FIG. 1 is moved in the direction of the arrow to form the substrate crystal 19 under the first layer growth thin layer solution 42a. Position it. On the surface of the substrate crystal 19, crystal growth is carried out at a constant growth rate because the solution has stable nucleation. After the temperature is lowered by 1 to 3 ° C. and the first layer is grown to a predetermined layer thickness (0.2 to 2 μm), the substrate crystal 19 is moved and placed under the second layer p-GaAs growing thin layer solution 42b. When it moves, it passes through the cleaning solution 41b of FIG. 1 (d), but as described above, since the overseed is placed in the cleaning solution as well, a large amount of generated nuclei are generated in the first layer as in the conventional case. A good quality crystal surface that does not adhere to the growth surface and has no defects can be obtained.

以上順次基板をスライドせしめ第２層として１〜２℃降
温し所望の成長層厚を得ることができる。As described above, the substrate is slid sequentially and the temperature is lowered by 1 to 2 ° C. as the second layer to obtain a desired growth layer thickness.

従って、本発明の洗浄溶液の厚みを成長溶液の厚みより
大きくすることを特徴とする構造の成長装置によって、
成長溶液用オーバシードへの溶液の全面的ぬれが安定し
て実現できるため、オーバシード法の効果を充分に発揮
することが可能になった。なお、本発明はInGaAsP形の
四元化合物等各種の結晶成長にも適用可能である。Therefore, by the growth apparatus having a structure characterized in that the thickness of the cleaning solution of the present invention is made larger than the thickness of the growth solution,
Since the complete wetting of the solution to the overseed for the growth solution can be stably realized, the effect of the overseed method can be sufficiently exhibited. The present invention can also be applied to various crystal growths such as InGaAsP type quaternary compounds.

〔発明の効果〕〔The invention's effect〕

本発明の効果は、溶液の過飽和度が調整されるため降温
時（成長時）に発生していた成長に寄与しない核が激減
し、基板スライドにより洗浄用溶液を通過する際の成長
表面への核の付着が極限まで減少し、組成制御が容易に
行なわれ、かつ結晶欠陥の少ない良質なエピタキシャル
層が得られることにある。したがって、従来のウォッシ
ュメルト法の欠陥を克服し、洗浄溶液と成長溶液との両
者に均一かつ全面にわたって安定してオーバシードを接
触せしめることによって核生成を制御し基板結晶への析
出が安定なものとなって層厚の再現性が得られ、かつ成
長層境界面に生ずる結晶欠陥を減少せしめ、半導体レー
ザダイオードの良品歩留を大巾に向上せしめた。又、同
一溶液を洗浄および成長の２段階で使用するため資材費
低減の効果もある。The effect of the present invention is that, since the supersaturation degree of the solution is adjusted, the number of nuclei that do not contribute to the growth generated during the temperature decrease (during growth) is drastically reduced, and the growth surface when the cleaning solution is passed by the substrate slide is reduced. It is to reduce the adhesion of nuclei to the utmost, to easily control the composition, and to obtain a high-quality epitaxial layer with few crystal defects. Therefore, overcoming the deficiencies of the conventional wash-melt method and controlling the nucleation by bringing the overseed into contact with both the cleaning solution and the growth solution uniformly and stably over the entire surface, the deposition on the substrate crystal is stable. As a result, the reproducibility of the layer thickness was obtained, and the crystal defects generated at the boundary surface of the grown layer were reduced, and the yield of good semiconductor laser diodes was greatly improved. Further, since the same solution is used in two stages of washing and growth, there is an effect of reducing the material cost.

【図面の簡単な説明】[Brief description of drawings]

第１図（ａ）は本発明の実施例によるオーバシードウォ
ッシュメルト法のスライド式液相成長装置の断面図であ
り、成長工程前の保持状態を示す。第１図（ｂ）と
（ｃ）は溶液と薄層溶液を形成する過程を示すものであ
り第１図（ｄ）はオーバシードが載置された洗浄溶液と
薄層溶液を示す断面図である。第２図は従来の成長装置
の断面図であり、第２図（ａ）は溶液の均一化をはかる
ための保持状態を示し、第２図（ｂ）は洗浄溶液および
薄層溶液が形成された状態を示すものである。第３図
（ａ），（ｂ）は従来のオーバシードウォッシュメルト
法ボートの原理図である。 １１……浴槽、１１ａ，１１ｂ……第１層，第２層用浴
槽、１２ａ，１２ｂ……第１層，第２層成長用溶液、４
１ａ，４１ｂ……第１層，第２層洗浄用溶液、４２ａ，
４２ｂ……第１，第２層成長用薄層溶液、１３……溶液
仕切り板、１４……オーバシード格納浴槽、１５……溶
液分離板、１６ａ，１６ｂ……第１層，第２層洗浄液用
オーバシード、１７ａ，１７ｂ……第１層，第２層成長
液用オーバシード、１８……基板スライド板、１９……
基板結晶、２１，３１……従来の浴槽、２２ａ，２２
ｂ，３２……従来の溶液、２６ａ，２７ａ，２６ｂ，２
７ｂ，３３……従来のオーバシード、２３ａ，２３ｂ，
３４……従来の洗浄用溶液、２４ａ，２４ｂ，３５……
従来の成長用溶液。FIG. 1A is a sectional view of a slide type liquid phase growth apparatus of an overseed wash melt method according to an embodiment of the present invention, showing a holding state before a growth step. FIGS. 1 (b) and 1 (c) show a process of forming a solution and a thin layer solution, and FIG. 1 (d) is a sectional view showing a cleaning solution and a thin layer solution on which an overseed is placed. is there. FIG. 2 is a cross-sectional view of a conventional growth apparatus, FIG. 2 (a) shows a holding state for making the solution uniform, and FIG. 2 (b) shows a cleaning solution and a thin layer solution formed. It shows the state of being closed. 3 (a) and 3 (b) are principle views of a conventional overseed wash melt method boat. 11 ... tub, 11a, 11b ... first layer, second layer bath, 12a, 12b ... first layer, second layer growth solution, 4
1a, 41b ... First layer, second layer cleaning solution, 42a,
42b ... Thin layer solution for growing first and second layers, 13 ... Solution partition plate, 14 ... Overseed storage bath, 15 ... Solution separating plate, 16a, 16b ... First layer, second layer cleaning liquid Overseed, 17a, 17b ... First seed layer, second layer growth liquid overseed, 18 ... Substrate slide plate, 19 ...
Substrate crystal 21, 31 ... Conventional bath, 22a, 22
b, 32 ... Conventional solution, 26a, 27a, 26b, 2
7b, 33 ... Conventional overseed, 23a, 23b,
34 ... Conventional cleaning solution, 24a, 24b, 35 ...
Conventional growth solution.

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】溶媒用浴槽と、洗浄用溶液を形成するため
の浴槽と、成長用薄層溶液を形成するための浴槽と、溶
液分離板と、基板結晶スライド板とを有し、前記洗浄用
および成長用浴槽の一部に洗浄用溶液と成長用溶液の飽
和度調整用種結晶を前記洗浄用溶液の液厚が成長用溶液
の液厚より厚くなる様に格納し、前記浴槽を溶液分離板
と相対的に移動せしめることによって前記種結晶が載置
された洗浄用溶液および成長用薄層溶液を実現すること
を特徴とする液相エピタキシャル成長装置。1. A washing bath comprising a solvent bath, a bath for forming a washing solution, a bath for forming a thin layer solution for growth, a solution separating plate, and a substrate crystal slide plate. The cleaning solution and a seed crystal for adjusting the degree of saturation of the growth solution are stored in a part of the growth bath so that the thickness of the cleaning solution is thicker than that of the growth solution, and the bath is filled with the solution. A liquid phase epitaxial growth apparatus, which realizes a cleaning solution on which the seed crystal is placed and a thin layer solution for growth by moving the seed crystal relatively to the separation plate.