JPS6285423A - Organic metal thermal decomposition vapor crystal growth apparatus - Google Patents

Abstract

PURPOSE:To improve the uniformity of the thickness and the composition of a grown crystal by using a substrate supporting tray capable of rotating around its own axis and revolving around the tray at crystal growing time by an MOVPE method, thereby averaging gas flow and temperature on the substrates. CONSTITUTION:Mixture gas is fed from a gas inlet 1 into a reaction tube 2, thermally decomposed on GaAs substrates 9, 9', and A GaAs crystal is accumulated and grown. The substrates 9, 9' are placed one by one on sub supporting trays 10, 10' on a main supporting tray 11. The tray 11 rotates entirely by a rotary driving shaft 4, but a gear 8 secured to a thermocoupler tube 3 does not move. Accordingly, the trays 10, 10' secured at rotational axes to the tray 11 having a gear engaged with the gear 8 rotate around its own axis on the tray 11. As a result, the trays 10, 10' perform so-called 'rotation and r evolution movement'. This movement performs uniform heating, thereby uniformizing the temperature distribution of the substrates 9, 9'.

Description

【発明の詳細な説明】 〔発明の技術分野〕 本発明は、気相結晶成長装置に係わり、特に化合物半導
体に適した有機金属熱分解法を用いた気相結晶成長装置
に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vapor phase crystal growth apparatus, and particularly to a vapor phase crystal growth apparatus using an organometallic thermal decomposition method suitable for compound semiconductors.

〔発明の技術的背景とその問題点〕[Technical background of the invention and its problems]

半導体レーザのような化合物半導体素子の製造に用いる
結晶成長として、有機金属熱分解気相結晶成長法（Ｍｅ
ｔａｌ　Ｏｒｇａｎｉｃ　Ｖａｐｏｒ　Ｐｈａｓｅ旦ｐ
ｉｔａｘｙ；ＭＯＶＰＥ）が最近広く用いられるように
なっている。Metal-organic pyrolysis vapor phase crystal growth (Me
tal Organic Vapor Phase
itaxy; MOVPE) has recently become widely used.

これは、ＭＯＶＰＥ法が、原料を全てガス状で供給する
気相結晶成長法の一種であるため、組成・膜厚の制御が
容易で、かつ大面積もしくは多数枚の基板上に結晶成長
が可能であり、半導体レーザのように、化合物半導体の
組成・膜厚の異なる多層薄膜の結晶成長技術を必要とす
る素子の製造に適した優れた量産技術として期待されて
いることによる。This is because the MOVPE method is a type of vapor phase crystal growth method in which all raw materials are supplied in gaseous form, so it is easy to control the composition and film thickness, and it is possible to grow crystals over a large area or on multiple substrates. This is because it is expected to be an excellent mass production technology suitable for manufacturing elements such as semiconductor lasers, which require crystal growth technology for multilayer thin films of compound semiconductors with different compositions and film thicknesses.

しかしながら、ＭＯＶＰＥ法を用いて大面積もしくは複
数枚の基板上に結晶成長を行なうと、膜厚や組成のムラ
が大きく、量産技術としては未完成であった。このこと
を、縦型反応管を用いたＭＯＶＰＥ法による１ｌＧａＡ
ｓ系の結晶成長を例にとり説明する６第４図において、
所定の原料濃度に調合された混合ガスは、ガス導入口１
から石英ガラス製の反応管２の内部に導入される。原料
ガスとしては有機金属であるトリメチルアルミニウム、
トリメチルガリウムと、砒素の水素化物であるアルシン
を用いる。導入された混合ガスは、所定の成長温度に加
熱されたＧａＡｓ基板１２．１２’の上で熱分解し、１
！ＧａＡｓの結晶が堆積成長する。ＧａＡｓ基板１２．
１２’は、高周波誘導加熱により所定の温度に設定され
たグラファイト製の支持台１３により間接的に加熱され
ている。支持台１３の内部には温度モニター用の熱電対
３が挿入されており、又、反応管２との軸ずれによるガ
ス流の不均一をならすために結晶成長中は回転軸４によ
り支持台１３は回転している。However, when crystal growth is performed on a large area or on a plurality of substrates using the MOVPE method, there are large variations in film thickness and composition, and the technique has not been perfected as a mass production technique. This was confirmed by the MOVPE method using a vertical reaction tube.
In Figure 4, which is explained using s-based crystal growth as an example,
The mixed gas blended to a predetermined raw material concentration is passed through the gas inlet port 1.
from the inside of the reaction tube 2 made of quartz glass. The raw material gas is trimethylaluminum, which is an organic metal,
Trimethylgallium and arsine, a hydride of arsenic, are used. The introduced mixed gas is thermally decomposed on the GaAs substrate 12, 12' heated to a predetermined growth temperature, and 1
! GaAs crystals are deposited and grown. GaAs substrate 12.
12' is indirectly heated by a support base 13 made of graphite that is set at a predetermined temperature by high-frequency induction heating. A thermocouple 3 for temperature monitoring is inserted into the support base 13, and during crystal growth, the support base 13 is rotated by a rotating shaft 4 in order to smooth out non-uniform gas flow due to misalignment with the reaction tube 2. is rotating.

厚さ２ｐのＡＱ□、２　Ｇａｏ、８Ａｓ膜を、内径１５
０＋ｎｍの反応管２と外径１２０ｍｍの支持台１３を用
いて、支持台１３上に敷き詰めたＧａＡｓ基板１２．１
２’上に成長させると、支持台１３が回転しているため
、支持台１３の円周方向にはほとんど無いが、半径方向
では著しい膜厚ムラと組成ムラが観察された。AQ□, 2 Gao, 8As film with a thickness of 2p and an inner diameter of 15
Using a 0+nm reaction tube 2 and a support base 13 with an outer diameter of 120 mm, a GaAs substrate 12.1 is spread on the support base 13.
When grown on 2', since the support 13 was rotated, there was almost no unevenness in the circumferential direction of the support 13, but significant unevenness in film thickness and composition was observed in the radial direction.

膜厚は、第５図に示すように、支持台１３の周辺部はど
薄くなり、±５％（２，０±０．１μｓ）以内に納まる
のは、支持台中央部の高々直径３０ｍｍ以内の領域にす
ぎない。この膜厚ムラは、原料である混合ガスが、基板
１２．１２’の表面に沿って支持台１３の中央部から周
辺に向かって流れるため、支持台中央部で原料が消費さ
れ、周辺部になるにつれて混合ガス中の原料濃度が低下
して、結晶の成長速度が低下することにより生じる。As shown in Fig. 5, the film thickness becomes thinner at the periphery of the support base 13, and the film thickness is within ±5% (2.0 ± 0.1 μs) within a diameter of at most 30 mm at the center of the support base. It is only the domain of This film thickness unevenness is caused by the mixed gas that is the raw material flowing from the center of the support base 13 toward the periphery along the surface of the substrate 12, 12', so that the raw material is consumed in the center of the support base and spreads to the periphery. This occurs because the raw material concentration in the mixed gas decreases as the temperature increases, and the crystal growth rate decreases.

一方、成長したＡｊｌＧａＡｓ結晶の組成を測定したと
ころ、第６図に示すように、支持台１３の周辺に近いほ
どｉ濃度が大きく、±１％（０，２０±０．０１ｉ／Ｇ
ａモル比）以内に納まるのは、支持台中央部の高々直径
２０＋ｎｎ＋以内の領域にすぎないことがわかった。On the other hand, when the composition of the grown AjlGaAs crystal was measured, as shown in FIG.
It was found that the area within the diameter of 20+nn+ at the center of the support stand was within the range of (a molar ratio).

この組成のムラは、高周波誘導加熱されている支持台１
３の温度つまりは結晶成長温度が支持台周辺部で高いこ
とと、ＡＱは高温になるほど結晶中に取り込まれ易い性
質をもっことに起因している。This compositional unevenness is caused by the fact that the support base 1 is heated by high-frequency induction.
This is due to the fact that the temperature No. 3, that is, the crystal growth temperature, is high around the support base, and AQ has a property that the higher the temperature, the more easily it is incorporated into the crystal.

半導体レーザを例にとると、駆動電流や光放射角の仕様
を満たすには、膜厚ムラを±５％以下に押えなければな
らず、発振波長の仕様を満たすに　ｊ− は、ＡＱ濃度を±１％以下の精度で制御する必要がある
。従って、前述のＮ０ＶＰＥ結晶成長装置が直径１２０
ｍｍ基板支持台を持ち、寸法的には直径５０ＩＩＩ１１
の基板であれば３枚同時に結晶成長可能でありながら、
半導体レーザ用としての結晶成長の仕様を満足するには
、前記基板支持台の中央部で、直径５０Ｉの基板を１枚
毎に結晶成長を行う必要があった。Taking a semiconductor laser as an example, in order to meet specifications for drive current and light emission angle, film thickness unevenness must be suppressed to ±5% or less, and to meet specifications for oscillation wavelength, the AQ concentration must be It is necessary to control with an accuracy of ±1% or less. Therefore, the N0VPE crystal growth apparatus described above has a diameter of 120 mm.
It has a substrate support stand with a diameter of 50III11 mm.
Although it is possible to grow crystals on three substrates at the same time,
In order to satisfy the specifications for crystal growth for a semiconductor laser, it was necessary to perform crystal growth on each substrate with a diameter of 50I at the center of the substrate support.

以上が、ＭＯＶＰＥ法の特徴として期待される高い量産
性が未だに実現されない理由である。These are the reasons why the high mass productivity expected as a feature of the MOVPE method has not yet been achieved.

〔発明の目的〕[Purpose of the invention]

本発明は、複数枚の基板上に化合物半導体薄膜を結晶成
長させた時の、膜厚ムラ・組成ムラを激減して、量産性
を格段に向上させたＭＯＶＰＥ装置を提供することを目
的とする。An object of the present invention is to provide an MOVPE apparatus that drastically reduces film thickness unevenness and composition unevenness when crystal-growing compound semiconductor thin films on a plurality of substrates, and significantly improves mass productivity. .

〔発明の概要〕[Summary of the invention]

本発明は、ＭＯＶＰＥ法による結晶成長時に、各基板を
個々に自公転運動させることのできる基板支持台を用い
ることにより、各基板上のガス流、温度を平均化して、
成長した結晶の膜厚・組成の均一性を向上させるもので
ある。The present invention uses a substrate support that can rotate each substrate individually during crystal growth using the MOVPE method, thereby averaging the gas flow and temperature on each substrate.
This improves the uniformity of the film thickness and composition of the grown crystal.

〔発明の実施例〕[Embodiments of the invention]

以下、本発明の詳細を実施例により説明する。 The details of the present invention will be explained below using examples.

第１図は、本発明によるＭＯＶＰＥ装置の反応部の概略
図である。本実施例は、２枚の基板上への良好な結晶成
長を可能としたもので、ＧａＡｓ基板上への１ｔＧａＡ
ｓ結晶成長に関するものである。FIG. 1 is a schematic diagram of the reaction section of the MOVPE apparatus according to the invention. This example enables good crystal growth on two substrates, including 1tGaA on a GaAs substrate.
s-crystal growth.

所定の原料濃度に調合された混合ガス（原料ガス）は、
ガス導入口１から反応管２の内部へ導入され、加熱され
た直径５０＋ａｍのＧａＡｓ基板９，９′上で熱分解し
て、ＡＱＧａＡｓの結晶が堆積・成長する。The mixed gas (raw material gas) prepared to a predetermined raw material concentration is
The gas is introduced into the reaction tube 2 through the gas inlet 1 and is thermally decomposed on the heated GaAs substrates 9 and 9' having a diameter of 50+ am, so that AQGaAs crystals are deposited and grown.

ＧａＡｓ基板９，９′は、主支持台１１上の副支持台１
０゜１０′上に１枚ずつ載置される。主支持台１１は回
転駆動軸４により全体が回転するが、熱電対管３に固定
された歯車８は動かない。従って、歯車８と噛み合った
歯車をもち、回転軸を主支持台１１に固定された副支持
台ｉｏ、　ｉｏ’は、各々主支持台ｌｌ上で自転する。The GaAs substrates 9, 9' are mounted on the sub-support stand 1 on the main support stand 11.
One sheet is placed on 0°10'. The main support base 11 is entirely rotated by the rotary drive shaft 4, but the gear 8 fixed to the thermocouple tube 3 does not move. Therefore, the auxiliary supports io and io', which have gears meshing with the gear 8 and whose rotating shafts are fixed to the main support 11, each rotate on the main support 11.

この結果、副支持台１０．１０’は、いわゆる「自公転
運動」を行なう。なお、副支持台ｉｏ、　ｉｏ’および
主支持台１１に対応する反応管２の周囲には、高周波誘
導加熱のための高周波コイル（１５）が配置されている
。副支持台１０．１０’は高周波誘導により発熱する材
料１例えばグラファイトで構成され、自公転運動により
均一加熱が達成され、ＧａＡｓ基板９，９′　　の温度
分布も均一になる。As a result, the sub-support stand 10.10' performs a so-called "rotation-revolution motion." Note that a high frequency coil (15) for high frequency induction heating is arranged around the reaction tube 2 corresponding to the sub-support stands io, io' and the main support stand 11. The auxiliary support 10, 10' is made of a material 1, such as graphite, which generates heat by high-frequency induction, and uniform heating is achieved by rotation and revolution, and the temperature distribution of the GaAs substrates 9, 9' is also made uniform.

ＧａＡｓ基板９，９′は結晶成長中に自公転運動を行な
い、各基板上のガス流が平均されると共に、温度分布も
均一になる。The GaAs substrates 9, 9' perform rotation and revolution during crystal growth, so that the gas flow on each substrate is averaged and the temperature distribution is also made uniform.

各部の寸法は、基本的には従来例として第４図に示した
ものと同じで、石英ガラス製の反応管２は内径１５０ｍ
ｎ　、グラファイト製の主支持台１１は外径１２０ｍｍ
　、同じくクラファイト製の副支持台１０゜１０′は外
径５０ｍｎである。The dimensions of each part are basically the same as those shown in Figure 4 as a conventional example, and the reaction tube 2 made of quartz glass has an inner diameter of 150 m.
n, the main support base 11 made of graphite has an outer diameter of 120 mm.
The sub-support stand 10°10', also made of graphite, has an outer diameter of 50 mm.

厚さ２陣のＡｌ１．２　Ｇａｏ、ａ　Ａｓ膜を成長させ
た時の、基板９，９′での膜厚と組成の分布を調べた結
果を、以下に説明する。The results of examining the film thickness and composition distribution on the substrates 9 and 9' when two thick Al1.2 Gao, a As films were grown will be described below.

第２図は膜厚分布を各基板の１つの直径上で測定した結
果で、横軸は基板中心からの距離、縦軸は膜厚を示す。FIG. 2 shows the results of measuring the film thickness distribution on one diameter of each substrate, where the horizontal axis shows the distance from the center of the substrate, and the vertical axis shows the film thickness.

実線、破線は各々、基板９，９′に対応する。同図から
、２枚の基板の間の膜厚差は非常に小さく、又、各基板
内の膜厚ムラも±３％程度と小さいことがわかる。The solid line and the broken line correspond to the substrates 9 and 9', respectively. From the figure, it can be seen that the difference in film thickness between the two substrates is very small, and the unevenness in film thickness within each substrate is also as small as about ±3%.

第３図はＡＩ１組成を同様に調べた結果で、横軸は基板
中心からの距離、縦軸は１ＧａＡｓ膜中のＡｆｉ濃度を
示す。実線、破線は各々基板９，９′に対応する。FIG. 3 shows the results of a similar investigation of the AI1 composition, where the horizontal axis shows the distance from the center of the substrate, and the vertical axis shows the Afi concentration in the 1GaAs film. The solid line and the broken line correspond to the substrates 9 and 9', respectively.

ＡＱ濃度のバラつきも小さく、基板間で１％以下、基板
内でも１％以下であった。The variation in AQ concentration was also small, being less than 1% between substrates and less than 1% within a substrate.

膜厚ムラ及び組成ムラは上述のように小さいこ　−とか
ら、本実施例では半導体レーザのような化合物半導体素
子の結晶成長として要求される仕様を充分満たしている
。Since the film thickness unevenness and composition unevenness are small as described above, this example sufficiently satisfies the specifications required for crystal growth of compound semiconductor devices such as semiconductor lasers.

〔発明の効果〕〔Effect of the invention〕

上述のように本発明によれば、膜厚、組成ともに従来法
による１枚だけの基板を用いた場合に比べ、勝るとも劣
らないほどの小さなムラに抑えることができ、しかも生
産性は一気に増加する。また本実施例では、反応管や支
持台の径等の反応部の基本的な構造や寸法に手を加える
必要はなく、基板支持台の変更のみで生産性向上が実現
されるという利点がある。As mentioned above, according to the present invention, it is possible to suppress unevenness in both film thickness and composition to a level that is much smaller than when using only one substrate using the conventional method, and productivity is increased at once. do. Furthermore, this embodiment has the advantage that it is not necessary to modify the basic structure and dimensions of the reaction section, such as the diameter of the reaction tube and support, and productivity can be improved simply by changing the substrate support. .

また基板内の厚さムラは従来法では中央部は必ず周辺部
より厚くなるが、本発明においては基板中心（自転軸）
と主支持台中心（公転軸）との距離を変えることで、基
板中央部を厚く、あるいは周辺部を厚くするかの制御が
可能である。これにより例えば半導体レーザ製造におけ
る面内分布のある工程、例えばエツチング工程等のバラ
つき傾向に、膜厚ムラの傾向を合せることで、エツチン
グ量の適正領域を広げることが可能となり、製造歩留り
が向上するという利点がある。In addition, in the conventional method, the thickness unevenness within the substrate is always thicker at the center than at the periphery, but in the present invention, the center of the substrate (rotation axis)
By changing the distance between the substrate and the center of the main support (revolution axis), it is possible to control whether the substrate is thick at the center or at the periphery. This makes it possible to expand the range of appropriate etching amounts by matching the tendency of film thickness unevenness to the tendency of variation in processes with in-plane distribution in semiconductor laser manufacturing, such as the etching process, thereby improving manufacturing yield. There is an advantage.

〔他の実施例〕[Other Examples]

上述の実施例では、２枚の基板上の結晶成長について説
明したが、同様の構造をもつ反応部を用いて３枚以上の
基板についても、各基板を個別に自公転運動させること
により良質な結晶成長が行なえる。また、各基板を個々
に回転させる方法として、実施例では歯車を用いたが、
同じ機能を有する他の方法でも良い。In the above example, crystal growth on two substrates was explained, but it is also possible to grow crystals on three or more substrates using a reaction section with a similar structure, by making each substrate rotate and rotate individually. Capable of crystal growth. In addition, gears were used in the embodiment to rotate each board individually, but
Other methods having the same function may also be used.

更に、′実施例では、ＡｊｔＧａＡｓ系の化合物半導体
の結晶成長装置について説明したが、本発明はＩｎＧａ
ＡｓＰ等の他の化合物半導体のＭＯＶＰＥ法による結晶
成長装置や、同様の反応部を用いる気相結晶成長装置、
例えばＳｉの熱分解気相結晶成長装置等についても適用
できる。Furthermore, in the example, a crystal growth apparatus for an AjtGaAs-based compound semiconductor was explained, but the present invention
A crystal growth device using the MOVPE method for other compound semiconductors such as AsP, a vapor phase crystal growth device using a similar reaction section,
For example, it can also be applied to a Si pyrolysis vapor phase crystal growth apparatus.

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

第１図は本発明の一実施例によるＮ０ＶＰＥ装置の各基
板が自公転可能な反応部の構成を示す図、第２図及び第
３図はそれぞれ第１図に示した装置を用いて成長したＡ
ＰＩＯ１２Ｇａ０．８　Ａｓ膜の厚さ分布とＡβ濃度分
布を表わす図、第４図は従来のＮ０ＶＰＥ装置の反応部
の構成を示す図、第５図は第４図で示した装置を用いて
成長したＡｌ１，２　Ｇａｏ、ａ　Ａｓ膜の厚さ分布を
表わす図、第６図は同じ＜ＡＩｌ濃度の分布を表わす図
である。 １・・・ガス導入口　　　　　２・・・反応管３・・・
熱電対管　　　　　　４・・・回転駆動軸５・・・フラ
ンジ　　　　　　６・・・熱電対端子７・・・ガス排気
口　　　　　８・・・固定歯車９．９′・・・ＧａＡｓ
基板　　　　　１０．１０’　−・・副支持台１１・・
・主支持台　　　　　　１２．１２’・・・ＧａＡｓ基
板１３・・・基板支持台　　　　　１５・・・高周波コ
イル第　　１　　図 膜厚 第　　２　　図 第　　３　　図 ｗＩ４図 第　　５　　図 第　　６　　図FIG. 1 is a diagram showing the configuration of a reaction section in which each substrate of an N0VPE apparatus according to an embodiment of the present invention can rotate around its axis, and FIGS. 2 and 3 show growth using the apparatus shown in FIG. 1. A
A diagram showing the thickness distribution and Aβ concentration distribution of a PIO12Ga0.8 As film. Figure 4 is a diagram showing the configuration of the reaction section of a conventional N0VPE apparatus. Figure 5 is a diagram showing the structure of a PIO12Ga0.8 As film grown using the apparatus shown in Figure 4. A diagram showing the thickness distribution of the Al1,2 Gao, a As film, and FIG. 6 are diagrams showing the distribution of the same <Al1 concentration. 1...Gas inlet 2...Reaction tube 3...
Thermocouple tube 4... Rotation drive shaft 5... Flange 6... Thermocouple terminal 7... Gas exhaust port 8... Fixed gear 9.9'... GaAs
Substrate 10.10' - Sub-support stand 11...
・Main support stand 12.12'...GaAs substrate 13...Substrate support stand 15...High frequency coil Figure 1 Film thickness Figure 2 Figure 3 Figure wI4 Figure 5 Figure 6

Claims (3)

【特許請求の範囲】[Claims] （１）反応管内に導入された原料ガスを熱分解し、反応
管内の基板支持台上に載置された基板上に結晶を成長さ
せる有機金属熱分解気相結晶成長装置において、前記基
板支持台が自公転することを特徴とする有機金属熱分解
気相結晶成長装置。(1) In an organometallic pyrolysis vapor phase crystal growth apparatus that thermally decomposes a raw material gas introduced into a reaction tube and grows crystals on a substrate placed on a substrate support in the reaction tube, the substrate support An organometallic pyrolysis vapor phase crystal growth device characterized by rotation and revolution. （２）前記基板支持台は高周波誘導加熱により発熱する
材料から構成されることを特徴とする特許請求の範囲第
１項記載の有機金属熱分解気相結晶成長装置。(2) The organometallic pyrolysis vapor phase crystal growth apparatus according to claim 1, wherein the substrate support is made of a material that generates heat by high-frequency induction heating. （３）前記基板支持台を複数有することを特徴とする特
許請求の範囲第２項記載の有機金属熱分解気相結晶成長
装置。(3) The organometallic pyrolysis vapor phase crystal growth apparatus according to claim 2, characterized in that it has a plurality of said substrate support stands.