JPS62119919A - Device for crystal growth of compound semiconductor - Google Patents

Abstract

PURPOSE:To grow a uniform film effectively by providing a gas cooling device between a material gas supply hole and a pedestal for supporting a substrate. CONSTITUTION:A gas cooling device 7 is arranged between a material gas supply hole 1 and a pedestal 5 for supporting a substrate 4. The material gas is mixed into a carrier gas and is led from a supply hole 1 to a reaction chamber 3, and further to the substrate 4 through the device 7. Then, the material gas is decomposed there and the crystal of a compound semiconductor is deposited on the substrate 4 by the chemical reaction among the decomposition products. Accordingly, also when the substrate 4 is heated to high temperature, the temperature of gas phase of the upstream of the substrate 4 does not increase and the transported material gas is decomposed only on the substrate 4 or in the vicinity of the substrate 4. The temperature distribution in the vicinity of the substrate 4 becomes uniform and the uniform film can be grown effectively.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明はｆヒ合物半導体の結晶成長装置に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to an apparatus for growing f-hyde compound semiconductor crystals.

〔従来の技術〕[Conventional technology]

有機金属化合物の熱分解を利用した気相成長法（以下Ｍ
Ｏ−ＣＶＤ法と記す）は、トリメチルガリウム、トリメ
チルアルミニウムなどの有機金属化合物とアルシン（Ａ
−８３）、ホスフィン（ＰＨｓ　）などの水素化合物を
反応管内の基板結晶上に導き、基板加熱により原料ガス
を熱分解し反応させて、基板結晶上に化合物半導体を成
長させる方法である。Vapor phase growth method (hereinafter referred to as M) that utilizes thermal decomposition of organometallic compounds
O-CVD method) is a method that combines organometallic compounds such as trimethylgallium and trimethylaluminum with arsine (A
-83) is a method in which a hydrogen compound such as phosphine (PHs) is introduced onto a substrate crystal in a reaction tube, and the source gas is thermally decomposed and reacted by heating the substrate, thereby growing a compound semiconductor on the substrate crystal.

この方法は、原料がすべて気体であることから成長膜の
大面積化、均一化が容易にでき、しかも急峻な界面が得
られ、組成制御性にもすぐれている。またこれらの特長
をさらに向上させるため装置を減圧にしたり、ガス導入
管の形に特別な工夫を施すなどの方法も用いられる。In this method, since all the raw materials are gases, it is possible to easily grow a large-area and uniform film, and also to obtain a steep interface, and to have excellent composition controllability. In addition, in order to further improve these features, methods such as reducing the pressure in the device or making special improvements to the shape of the gas introduction pipe are also used.

ＭＯ−ＣＶＤ法では、一般に原料ガスを基板結晶上に輸
送したり、あるいは液体原料に適当な蒸気圧を持たせて
バブリン・グを行ないガス状にして輸送するためにキャ
リアガスを用いる。キャリアガスとしては通常、水素が
使用される。またエピタキシャル膜を成長させる化合物
半導体基板はカーボンペデスタルに設置し、これを抵抗
加熱あるいは高周波誘導加熱により加熱する。このよう
に基板のみ加熱するのがＭＯ−ＣＶＤ法の一つの特徴で
ある。In the MO-CVD method, a carrier gas is generally used to transport a raw material gas onto a substrate crystal, or to give a liquid raw material an appropriate vapor pressure and perform bubbling to turn it into a gas and transport it. Hydrogen is usually used as carrier gas. Further, a compound semiconductor substrate on which an epitaxial film is to be grown is placed on a carbon pedestal, and this is heated by resistance heating or high frequency induction heating. One of the characteristics of the MO-CVD method is that only the substrate is heated in this way.

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

ＭＯ−ＣＶＤ法において、原料ガスを基板上もしくは基
板近傍で分解させ、化合物半導体の生成反応を起こさせ
る必要がある。しかるに、従来の方法では、基板加熱を
した場合、基板上方の気相中の温度も上昇し、そこで原
料ガスが分解する。In the MO-CVD method, it is necessary to decompose the source gas on or near the substrate to cause a compound semiconductor production reaction. However, in the conventional method, when the substrate is heated, the temperature in the gas phase above the substrate also rises, and the source gas decomposes there.

このため次のような問題が起る。This causes the following problems.

その一つは、例えば、■−Ｖ族化合物を成長させる場合
基板温度が７００℃以上の高温では、原料ガスの大部分
は気相中で分解し反応するので、成長膜の成長速度が著
しく低下することである。One of them is, for example, when growing ■-V group compounds, when the substrate temperature is at a high temperature of 700°C or higher, most of the raw material gas decomposes and reacts in the gas phase, so the growth rate of the grown film decreases significantly. It is to be.

あるいは、基板温度が６００〜７００℃という通常の成
長温度であっても原料ガスに低温で分解するようなもの
を用いると、同じように気相中で分解し成長膜の成長速
度が減少する。即ち、輸送した原料ガスに対する成長効
率が低下する。Alternatively, even if the substrate temperature is a normal growth temperature of 600 to 700° C., if a source gas that decomposes at a low temperature is used, it will similarly decompose in the gas phase and the growth rate of the grown film will decrease. That is, the growth efficiency with respect to the transported raw material gas decreases.

もう一つの問題は、基板上方の気相の温度分布の相違か
ら気相中での原料ガスの分解の度合が異なり、成長膜の
厚さが不均一になることである。Another problem is that the degree of decomposition of the source gas in the gas phase differs due to the difference in temperature distribution in the gas phase above the substrate, resulting in non-uniform thickness of the grown film.

例えば、横型ＭＯ−ＣＶＤ装置では、基板加熱時にガス
流に対して基板の下流側の気相が加熱されやすく、上流
に比べて下流側で原料ガスの分解と化合物半導体の生成
反応が進み、成長膜は上流で厚く、下流側で薄くなる傾
向がある。また縦型ＭＯ−ＣＶＤ装置でも基板の中央と
端での気相の温度分布に差違があるため膜厚が不均一に
なる。For example, in a horizontal MO-CVD apparatus, when heating the substrate, the gas phase on the downstream side of the substrate is easily heated by the gas flow, and the decomposition of the raw material gas and the reaction to generate compound semiconductors progress downstream compared to the upstream, resulting in growth. The membrane tends to be thicker upstream and thinner downstream. Further, even in a vertical MO-CVD apparatus, there is a difference in the temperature distribution of the gas phase between the center and the edge of the substrate, resulting in non-uniform film thickness.

上述したように、従来の結晶成長装置は、成長速度が遅
く効率が低いとか、厚さの均一な成長膜が得られないと
いう問題があった。As mentioned above, conventional crystal growth apparatuses have problems such as slow growth rate and low efficiency, and inability to obtain a grown film with a uniform thickness.

゛本発明の目的は、均一な成長膜を効率よく成長させる
ことのできる化合物半導体の結晶成長装置を提供するこ
とにある。An object of the present invention is to provide a compound semiconductor crystal growth apparatus that can efficiently grow a uniform film.

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

本発明の化合物半導体の結晶成長装置は、原料ガス供給
口とガス排出口とを有する反応室と、前記反応室内に設
置され基板を保持するペデスタルと、基板及び又は前記
へデスタルを加熱する加熱装置と、前記原料ガス供給口
と前記ペデスタルとの間に配置されたガス冷却装置とを
含んで構成される。The compound semiconductor crystal growth apparatus of the present invention includes a reaction chamber having a raw material gas supply port and a gas discharge port, a pedestal installed in the reaction chamber for holding a substrate, and a heating device for heating the substrate and/or the pedestal. and a gas cooling device disposed between the source gas supply port and the pedestal.

〔作用〕[Effect]

反応管内にガス冷却ブロックを設置することにより、基
板を高温まで加熱した際にも、゛基板上流での気相の温
度が上昇せず、輸送された原料ガスは基板上又は基板近
傍でのみ分解する。又、基板近傍の温度分布が均一にな
る。By installing a gas cooling block in the reaction tube, even when the substrate is heated to a high temperature, the temperature of the gas phase upstream of the substrate does not rise, and the transported raw material gas decomposes only on or near the substrate. do. Furthermore, the temperature distribution near the substrate becomes uniform.

〔実施例〕　・ 次に、本発明の実施例について図面を参照して説明する
。[Example] - Next, an example of the present invention will be described with reference to the drawings.

第１図は本発明の一実施例の構成を示す模式図□である
。FIG. 1 is a schematic diagram □ showing the configuration of an embodiment of the present invention.

この実施例は、原料ガス供給口１とガス排出口２とを有
する、石英からなる反応室３と、反応室３内に設置され
基板４を保持するカーボンからなるペデスタル５と、基
板４及び又はペデスタル５を加熱する加熱装置である高
周波コイル６と、原料ガス供給口１とペデスタル５との
間に配置されたガス冷却装置７とを含んで構成されてい
る。This embodiment includes a reaction chamber 3 made of quartz and having a raw material gas supply port 1 and a gas discharge port 2, a pedestal 5 made of carbon installed in the reaction chamber 3 and holding a substrate 4, and a substrate 4 and/or a pedestal 5 made of carbon. It is configured to include a high frequency coil 6 which is a heating device for heating the pedestal 5, and a gas cooling device 7 disposed between the source gas supply port 1 and the pedestal 5.

第２図（ａ）及び（ｂ）はそれぞれガス冷却装置の上面
図及び正面図である。このガス冷却装置７は、冷却水流
入口８と冷却水排出口９を有する石英容器の天井と底を
貫通して複数のガス導入管１０が設けられたものである
。FIGS. 2(a) and 2(b) are a top view and a front view of the gas cooling device, respectively. This gas cooling device 7 is provided with a plurality of gas introduction pipes 10 penetrating through the ceiling and bottom of a quartz container having a cooling water inlet 8 and a cooling water outlet 9.

原料ガスはキャリアガスに混合されて原料ガス供給口１
から反応室３内へ導かれ、ガス冷却装置７のガス導入管
１０を通って基板４へと導かれ、そこで分解され、分解
生成物間の化学反応により、化合物半導体の結晶が基板
上へ析出される。The raw material gas is mixed with the carrier gas and supplied to the raw material gas supply port 1.
The gas is guided into the reaction chamber 3, passed through the gas introduction pipe 10 of the gas cooling device 7, and guided to the substrate 4, where it is decomposed and crystals of the compound semiconductor are deposited on the substrate due to a chemical reaction between the decomposition products. be done.

第３図は基板温度と成長速度の関係の一例を示す特性図
である。キャリアガスは水素、原料ガスはトリメチルガ
リウムとＡ、Ｈ，、成長する結晶はＧ、Ａ、である。点
線は冷却装置を設けない場合の曲線、実線は冷却装置を
設けた場合の曲線である。冷却装置を設けることにより
、成長速度が一定の基板温度範囲が高温側へ広がること
がわかる。FIG. 3 is a characteristic diagram showing an example of the relationship between substrate temperature and growth rate. The carrier gas is hydrogen, the raw material gases are trimethyl gallium, A, H, and the growing crystals are G, A. The dotted line is the curve when no cooling device is provided, and the solid line is the curve when the cooling device is provided. It can be seen that by providing a cooling device, the substrate temperature range in which the growth rate is constant is expanded to the higher temperature side.

第４図は基板内の成長膜厚分布の一例を示す特性図であ
る。直径５０朋のＧ、Ａ、基板を縦型の結晶成長装置中
に置いて、６００°Ｃに加熱してＧ、Ａ、を成長させた
場合の図である。点線は冷却装置を設けない場合の曲線
、実線は冷却装置を設けた場合の曲線である。冷却装置
を設けることにより、成長膜厚分布の均一性が改善され
ていることがわかる。FIG. 4 is a characteristic diagram showing an example of the growth film thickness distribution within the substrate. This is a diagram showing a case where G, A, and substrates having a diameter of 50 mm are placed in a vertical crystal growth apparatus and heated to 600° C. to grow G, A. The dotted line is the curve when no cooling device is provided, and the solid line is the curve when the cooling device is provided. It can be seen that the uniformity of the grown film thickness distribution is improved by providing the cooling device.

有機金属化合物として分解温度の低いトリエチルガリウ
ムやジエチルガリウムクロライドを用いても類似の結果
が得られた。Similar results were obtained using triethylgallium and diethylgallium chloride, which have low decomposition temperatures, as organometallic compounds.

また■−Ｖ族化合物のみでなく、ＩＩ−ＶＩ族化合物も
亦この結晶成長装置を用いて成長させることができるの
はいうまでもない。It goes without saying that not only the ■-V group compounds but also the II-VI group compounds can be grown using this crystal growth apparatus.

〔発明の効果〕〔Effect of the invention〕

以上説明したように本発明は、原料ガス供給口とペデス
タルとの間にガス冷却装置を設置することにより、ペデ
スタルの上流の気相中の温度上昇を防ぎガスの対流をお
さえることができ、成長速度の温度依存性が緩和され、
また成長膜厚分布の均一性も改善されるという効果があ
る。As explained above, in the present invention, by installing a gas cooling device between the raw material gas supply port and the pedestal, it is possible to prevent the temperature rise in the gas phase upstream of the pedestal and suppress the gas convection. Temperature dependence of speed is relaxed,
It also has the effect of improving the uniformity of the grown film thickness distribution.

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

第１図は本発明の一実施例の構成を示す模式図、第２図
（ａ）及び（ｂ）はそれぞれガス冷却装置の上面図及び
正面図、第３図は基板温度と成長速度の関係の一例を示
す特性図、第４図は基板内の成長膜厚分布の一例を示す
特性図である。 １・・・原料ガス供給口、２・・・ガス排出口、３・・
・反応室、４・・・基板、５・・・ペデスタル、６・・
・高周波コイル、７・・・ガス冷却装置、８・・・冷却
水流入口、９・・・冷却水排出口、１０・・・ガス導入
管。 ＄ＩＩ！Ｉ 茅　２ＭＡ （ａンFigure 1 is a schematic diagram showing the configuration of an embodiment of the present invention, Figures 2 (a) and (b) are top and front views of a gas cooling device, respectively, and Figure 3 is the relationship between substrate temperature and growth rate. FIG. 4 is a characteristic diagram showing an example of the growth film thickness distribution within the substrate. 1... Raw material gas supply port, 2... Gas discharge port, 3...
・Reaction chamber, 4...Substrate, 5...Pedestal, 6...
- High frequency coil, 7... Gas cooling device, 8... Cooling water inlet, 9... Cooling water outlet, 10... Gas introduction pipe. $II! I Kaya 2MA (a)

Claims (1)

【特許請求の範囲】[Claims] 原料ガス供給口とガス排出口とを有する反応室と、前記
反応室内に設置され基板を保持するペデスタルと、基板
及び又は前記ペデスタルを加熱する加熱装置と、前記原
料ガス供給口と前記ペデスタルとの間に配置されたガス
冷却装置とを含むことを特徴とする化合物半導体の結晶
成長装置。a reaction chamber having a raw material gas supply port and a gas discharge port; a pedestal installed in the reaction chamber for holding a substrate; a heating device for heating the substrate and/or the pedestal; 1. A compound semiconductor crystal growth apparatus, comprising: a gas cooling device disposed between the crystals.