JPS61235579A - Method for cleaning inside of reaction furnace - Google Patents

Abstract

PURPOSE:To remove easily film or powder adhered and formed at inner wall of a reaction furnace, by forming film on a base plate by generating plasma in the reaction furnace, then plasma gas etching inside the reaction furnace. CONSTITUTION:Reactive gas is introduced in the reaction furnace 5, and converted to plasma by a high frequency induction furnace 6, a base plate 10 on a boat 8 is heated by an electric furnace 7, to form film on the base plate 10. By repeating the procedure, a reaction product 9 is adhered and formed as film or powder at inner wall of the furnace 5. The base plate 10 on which film is formed is taken out from the furnace 5, then NF4 and inert gas are introduced to the furnace 5, about 0.5-50MHz or about 1-10GHz induction energy is applied by the furnace 6 at about 0.01-10Torr pressure, to convert the gas to plasma, and plasma gas phase etching is carried out. In this way, the product 9 is removed and the furnace is cleaned, without dismounting the furnace 5.

Description

【発明の詳細な説明】 この発明はＣＶＤ法（気相蓄積法）、グロー放電法によ
り珪素または珪化物のアモルファスまたはセミアモルフ
ァス（半非晶質）の被膜を基板上の被形成面に形成する
に際し、壁面に同時に形成される被膜または付着形成さ
れた粉体が再び飛翔して半導体被膜中に混入し、特性を
きわめて悪化させることに対しなされたもので、この反
応炉を装置よりはずすことなく、これらの付着物を化学
的にエッチして除去せしめること、さらにこの付着物の
発生を防止または少なくすることを特徴とする。DETAILED DESCRIPTION OF THE INVENTION This invention forms an amorphous or semi-amorphous film of silicon or silicide on a surface to be formed on a substrate by a CVD method (vapor phase accumulation method) or a glow discharge method. This was done to prevent the coating that is simultaneously formed on the wall surface or the powder that has been deposited on the wall surface to fly off again and get mixed into the semiconductor coating, seriously deteriorating the characteristics. , it is characterized by chemically etching and removing these deposits, and further by preventing or reducing the occurrence of these deposits.

従来、かかる気相法により被膜を形成させる場合、反応
生成物の一部が石英等の反応管の内壁部にその内壁部の
温度が高いため被膜として形成されたり、または粉末と
して被着したりしていた。Conventionally, when a film is formed by such a gas phase method, a part of the reaction product is formed as a film on the inner wall of a reaction tube made of quartz or the like due to the high temperature of the inner wall, or is deposited as a powder. Was.

しかしこの内壁に形成される被膜は容易に離脱しやすく
、そのため、離脱した粉体は飛翔して基板上にも付着し
、スノーフレーク等を作り、結果として形成される被膜
にピンホール等を作る等の欠点があった。さらにこの粉
体は粒界が明確であるため、その粒界に不対結合手を集
中的に発生させ、半導体の特性を悪化させてしまった。However, the coating formed on this inner wall easily separates, and as a result, the separated powder flies and adheres to the substrate, creating snowflakes, etc., and as a result, pinholes, etc. are created in the formed coating. There was a drawback. Furthermore, since this powder has clear grain boundaries, dangling bonds are generated intensively at the grain boundaries, deteriorating the characteristics of the semiconductor.

このため反応は被膜形成を５〜１０回繰り返した後必ず
装置よりとりはずし、弗酸等の溶液に浸漬して付着物を
溶去することを常としていた。しかしこの装置へのとり
つけ、真空もれのチェック等きわめて操作が煩雑であり
、そのため口、トバラツキが発生してしまい、製品特に
半導体装置のバラツキの原因になっていた。For this reason, in the reaction, after repeating film formation 5 to 10 times, the film was always removed from the apparatus and immersed in a solution such as hydrofluoric acid to dissolve away the deposits. However, the operations such as attaching the device to the device and checking for vacuum leaks are extremely complicated, and this results in variations in the quality of the product, especially semiconductor devices.

本発明は、気相法により被膜形成を行った同一装置に対
して、反応炉内壁に付着した被膜または粉体を弗化窒素
（ＮＦ、ＮＦ！、ＮＦ３等のエツチング用ガス、代表的
にはＮＦ３）を利用してプラズマ気相エツチングを反応
炉をとりはずすことな〈実施せしめてクリーニングを行
うことを特徴とする。加えてこのエツチングの際、被膜
が形成される反応炉の・内域を特に清浄にするため、こ
の領域をプラズマエッチによるクリーニングの際、水冷
をやめて加熱昇温せしめて、反応炉壁面での反応を助長
せしめ清浄度を高めることを特徴としている。The present invention uses an etching gas such as nitrogen fluoride (NF, NF!, NF3, etc.) to remove the coating or powder adhered to the inner wall of the reactor using the same equipment that forms the coating by the gas phase method. The method is characterized in that cleaning is performed by performing plasma vapor phase etching using NF3) without removing the reactor. In addition, during this etching, in order to particularly clean the inner area of the reactor where the film is formed, when cleaning this area by plasma etching, water cooling is stopped and the temperature is raised to prevent the reaction on the reactor wall surface. It is characterized by promoting cleanliness and increasing cleanliness.

以下にその実施例を図面に従って説明する。Examples thereof will be described below with reference to the drawings.

第１図は本発明を用いた反応炉の概要を示した図面であ
る。本発明は、気相法において被膜が形成される領域よ
り離れてプラズマ発生源（６）を有し、基板（１０）は
ボート（８）上で誘導または抵抗輻射加熱型電気炉（７
）により加熱されることができるようにした。さらにこ
の基板の前方の反応炉はその外側を二重管とし水冷させ
、壁面での核形成を防止または少なくした。またプラズ
マクリーニングにおいては、冷却水を除去した反応炉全
体をこのボートの設置される領域を中心としてクリーニ
ングが強く行われるようにするため、この反応炉を１０
０−１０００℃に加熱してエツチング速度を速くしたこ
とが他の特徴である。FIG. 1 is a diagram showing an outline of a reactor using the present invention. The present invention has a plasma generation source (6) located away from a region where a film is formed in a vapor phase method, and a substrate (10) is placed in an induction or resistance radiation heating electric furnace (7) on a boat (8).
) so that it can be heated by Furthermore, the outside of the reactor in front of the substrate is double-walled and water-cooled to prevent or reduce nucleation on the wall. In addition, during plasma cleaning, in order to perform intensive cleaning of the entire reactor from which cooling water has been removed, focusing on the area where the boat is installed, the reactor is cleaned for 10 minutes.
Another feature is that the etching rate is increased by heating to 0-1000°C.

反応炉（５）はその内壁に反応生成物（９）が被膜また
は粉体にて被着形成される。The reaction product (9) is formed as a coating or powder on the inner wall of the reactor (5).

即ち、珪化物気体例えばシラン（ＳｉＨ２）ｌ　ポリシ
ラン（Ｓｉｘ）ｌｙ　Ｘ、Ｙ＞１）、５ｉＨｔＣ１ｚ、
ＳｉＦ＋＋５ｉＣ１ｎ等の気体または不活性気体により
希釈されたこれらの反応性気体を（１）より導入し、高
周波誘導炉（６）により０．５〜５０ＭＨｚまたは１〜
１０ＧＨｚの周波数の誘導エネルギを１０〜５００１１
加えることにより、反応炉内で０．０１〜１０ｔｏｒｒ
に減圧された雰囲気をプラズマ化する。このプラズマ化
された気体を加熱炉により２００〜８００℃に加熱した
基板（１０）上・にアモルファス、セミアモルファス（
半非晶質、半結晶質といってもよいＳｅａ＋ｉ−ａｍｏ
ｒｐｈｏｕｓ、　Ｑｕａｓｉ−ａｍｏｒｐｈｏｕｓ。That is, silicide gases such as silane (SiH2), polysilane (Six), X, Y>1), 5iHtC1z,
These reactive gases diluted with a gas such as SiF++5iC1n or an inert gas are introduced from (1) and are heated to 0.5 to 50 MHz or 1 to 50 MHz using a high frequency induction furnace (6).
The induced energy of the frequency of 10 GHz is 10~50011
By adding 0.01 to 10 torr in the reactor
Converts the reduced pressure atmosphere into plasma. This plasma gas is heated to 200 to 800°C in a heating furnace to form an amorphous or semi-amorphous (
Sea+i-amo can be said to be semi-amorphous or semi-crystalline.
rphous, Quasi-amorphous.

Ｓｅｍ１−ｃｒｙｓｔａｌまたはＱｕａｓｉ−ｃｒｙｓ
ｔａｌの如き非晶質と結晶質の中間構造を有する半導体
をここでは総称する）膜を０．００１〜１０μｍの膜厚
に形成する。Sem1-crystal or Quasi-crys
Semiconductors having an intermediate structure between amorphous and crystalline, such as tal, are collectively referred to herein) are formed to a thickness of 0.001 to 10 μm.

これをさらに複数回繰り返すと、この基板上の被膜形成
と同様の反応生成物が内壁（９）に付着してしまう、特
に加熱された領域は被膜化し、その後側の排気口付近は
粉末状の膜が内壁に付着する。If this is repeated several more times, reaction products similar to the film formation on this substrate will adhere to the inner wall (9), especially the heated area will become a film, and the area near the exhaust port on the rear side will become powdery. A membrane adheres to the inner wall.

もちろん大部分の反応生成物はキャリアガスとともにニ
ードルバルブ（１１）、ストップバルブ（１２）　ヲ経
てロータリーポンプ（１３）により外へ排出される。Of course, most of the reaction products together with the carrier gas are discharged to the outside by the rotary pump (13) via the needle valve (11) and stop valve (12).

本発明において、誘導エネルギにより反応性気体を化学
的に活性、分解または反応せしめると、そのエネルギ供
給部にて活性気体が反応炉壁面に衝突し、この壁面の温
度を２００〜８００℃にまで上昇させてしまった。その
ため、この壁面に反応物の付着、被膜化がおきてしまっ
た。In the present invention, when the reactive gas is chemically activated, decomposed or reacted by induced energy, the activated gas collides with the wall surface of the reactor at the energy supply section, raising the temperature of this wall surface to 200 to 800 degrees Celsius. I let it happen. As a result, reactants adhered to this wall surface and formed a film.

本発明はかかる欠点を除去するため、この誘導エネルギ
を与えた部分およびその前後の反応炉内壁を含む反応炉
壁面を冷却し、この壁面の温度を１０〜５０℃におさえ
、結果として被膜形成の際、反応物の付着を壁面の冷却
を行わない場合に比べて１／１０〜１／３０にした。In order to eliminate such drawbacks, the present invention cools the reactor wall including the part to which the induction energy is applied and the inner walls of the reactor before and after the part, and controls the temperature of this wall to 10 to 50°C, thereby preventing film formation. At this time, the adhesion of reactants was reduced to 1/10 to 1/30 compared to the case where the wall surface was not cooled.

さらに形成する被膜が珪素の場合、この被膜をＰまたは
Ｎ型の導電型にするには、ホウ素、インジェームの如き
■価の不純物またはリン、砒素、アンチモンの如き７価
の不純物を水素化物または塩化物（ハロゲン化物）にし
て（４）より導入すればよい。Furthermore, when the film to be formed is silicon, in order to make the film P or N type conductivity, it is necessary to add a valent impurity such as boron or ingeme or a heptavalent impurity such as phosphorus, arsenic, or antimony to a hydride or It may be introduced as a chloride (halide) through step (4).

また、かかる被膜形成法によるｏ、ｏｏｉ〜１０μの被
膜を１〜３回繰り返すと、０．０１〜１００μの厚さの
被膜または粒の集まりであるみかけの厚さの被膜（９）
が内壁に形成された。この後、本発明はかかる被膜また
は粉体（９）の除去を、弗化窒素（以下ＮＦ３という）
さらにまたは該気体に＾ｒ等の不活性ガスを（４）より
混入して０．０１〜１０ｔｏｒｒの圧力にて０．５〜５
０Ｍ）ｌｚ又は１〜１０ＧＨｚの誘導エネルギを（６）
により与えてプラズマ化して実施した。弗化窒素のかわ
りに塩化窒素その他のエツチングガスまたはこれらの混
合ガスまたは弗化塩化窒素の如き化合物を用いてもよい
。この際反応炉内では活性弗素と窒素（Ｎ”またはＮ、
）ができ、これまでのＣＦ、の如き半導体に有害な固体
の炭素の発生または膜中への混入がない。本発明におい
てはボートに設置する領域を形成した温度またはそれ以
上の温度に加熱昇温したり、さらにまたは１００〜１０
００℃の温度に加熱し反応炉の内壁での反応性気体を容
易に内壁の反応生成物と反応せしめエツチング除去させ
るとともに、内壁でのクリーニング工程の後の白濁化を
防ぐことができた。In addition, when a film of o, ooi to 10μ by this film formation method is repeated 1 to 3 times, a film (9) with an apparent thickness of 0.01 to 100μ or a collection of grains is formed.
was formed on the inner wall. After this, the present invention removes the film or powder (9) using nitrogen fluoride (hereinafter referred to as NF3).
Furthermore, or by mixing an inert gas such as
0M)lz or 1-10GHz induction energy (6)
The experiment was carried out by giving plasma and converting it into plasma. In place of nitrogen fluoride, other etching gases such as nitrogen chloride, mixed gases thereof, or compounds such as nitrogen fluoride chloride may be used. At this time, activated fluorine and nitrogen (N" or N,
), and there is no generation of solid carbon harmful to semiconductors or mixing into the film, such as conventional CF. In the present invention, the area to be installed on the boat is heated to a temperature equal to or higher than the temperature at which the area is installed, or
By heating to a temperature of 00°C, the reactive gas on the inner wall of the reactor was easily reacted with the reaction product on the inner wall and removed by etching, and it was possible to prevent the inner wall from becoming cloudy after the cleaning process.

このプラズマエッチを充分にした後、不活性気体または
窒素のみまたはそれに水素を２〜１０％添加した気体中
でさらにプラズマ化を１５分〜１時間行い、内壁に残存
する活性エツチングガスである弗素を除去した後再び基
板を反応炉内に導入し珪化物気体の被膜の作成を行った
。After sufficient plasma etching, plasma formation is further performed for 15 minutes to 1 hour in an inert gas, nitrogen alone, or a gas containing 2 to 10% hydrogen to remove fluorine, which is an active etching gas, remaining on the inner wall. After removal, the substrate was introduced into the reactor again to form a film of silicide gas.

かくすることにより、これまでは１０〜１００回被膜形
成した後、反応炉をとりはずして溶液を用いて化学エッ
チを施し清浄にしたのに対し、本発明においては１〜１
０回の被膜形成毎に内壁の洗浄を装置をとりはずすこと
な（できるため、次に形成される基板上にピンホールの
ない均一な被膜を半連続的に形成させることができ、そ
の再現性はきわめて著しく優れたものであった。By doing this, in the past, after forming a film 10 to 100 times, the reactor was removed and chemically etched using a solution to clean it, whereas in the present invention, the film was formed 1 to 1 times.
It is possible to clean the inner wall after every film formation without removing the equipment (this makes it possible to semi-continuously form a uniform film without pinholes on the next substrate to be formed, and its reproducibility is It was extremely excellent.

本発明にては反応炉は管状を有する反応管を構成し、そ
の大きさは直径が５〜３０ｃｍ、長さ１〜５ｍを有する
大口径の可動しに（いＣｖ口詰装置場合に特に有効であ
り、さらに従来公知の溶液によるエツチングの如く、公
害源の毒物を副生成物として発生させることなく、さら
に反応に用いるガスも副生成物が窒素であるため半導体
的に非反応性気体であり、格子欠陥の発生等の影響がま
ったくなく、その面においても好ましかった。In the present invention, the reactor has a tubular shape, and its size is 5 to 30 cm in diameter and 1 to 5 m in length. Furthermore, unlike etching with a conventionally known solution, no toxic substances that cause pollution are generated as by-products, and the gas used for the reaction is a non-reactive gas in terms of semiconductors since the by-product is nitrogen. , there was no influence such as the occurrence of lattice defects, and it was preferable from that point of view as well.

本発明は珪素またはその化合物を形成する気相法を基本
とした。しかしまた、ゲルマニューム、ＢＰ、ＧａＡｓ
等のｍ−ｖ化合物であっても同様であり、アルミニュー
ム等の金属をＣＶＤ法で形成させる場合も同様に有効で
あり、特に付着物がアルミニュームの場合は塩化窒素に
よりエツチングするとさらに効果が大きかった。The present invention is based on a gas phase method for forming silicon or its compounds. But also germanium, BP, GaAs
The same is true for m-v compounds such as aluminum, etc., and it is also effective when forming metals such as aluminum by the CVD method. Especially when the deposit is aluminum, etching with nitrogen chloride is even more effective. It was big.

本発明方法は被着物が粉体の如く大きな表面積を有し、
かつその粒界に界面準位が多数存在する塊として被膜中
に混在することを防ぎ、半導体の如き被膜をミクロな面
においても均質なアモルファス、セミアモルファスまた
はセミクリスタル構造を有する半導体とすることに有効
であった。In the method of the present invention, the adherend has a large surface area like powder,
In addition, it is possible to prevent a large number of interface states from being mixed in the film at the grain boundaries, and to make a film such as a semiconductor into a semiconductor having a homogeneous amorphous, semi-amorphous, or semi-crystalline structure even in the microscopic plane. It was effective.

これまでは特に不本意に発生する粉体が逆に被膜形成の
際被膜をスパッタし、被膜中にボイドまたはビ、ンホー
ル等を形成させやすかった。しかし本発明方法は、気相
法において気相法にプラズマ・エツチング法とを組み合
わせた以上の効果を有し、特にプラズマ・エツチングを
基板に対し行うのではなく、反応炉の内壁の付着物の除
去およびその付着物の除去の際加熱昇温しで反応を助長
せしめ、弗素の如き反応性の強いラジカルを弗素それ自
体ではなく反応終了物も弗化珪素、弗化窒素および不活
性の窒素等の化学的に安定な気体とするため、その気体
の放出光であるロータリーポンプをへて外部に放出させ
ても実質的に無公害であることも本発明方法の他の特徴
である。In the past, the unintentionally generated powder was likely to sputter the film during film formation, resulting in the formation of voids, holes, etc. in the film. However, the method of the present invention has more effects than the combination of the gas phase method and the plasma etching method in the gas phase method. During removal and the removal of attached substances, the reaction is promoted by increasing the temperature, and highly reactive radicals such as fluorine are removed not from fluorine itself, but also from the reaction products such as silicon fluoride, nitrogen fluoride, and inert nitrogen. Another feature of the method of the present invention is that since the gas is chemically stable, it is substantially non-polluting even when the emitted light of the gas is emitted to the outside through a rotary pump.

本発明の実施例において、冷却は水冷を主として記した
。しかしこの冷却を木取外の例えばフロンガスをその冷
凍器により冷却し、−３０℃に至るまでの適当な温度に
下げることはさらに壁面への反応生成物の付着を防ぐの
に効果があった。In the examples of the present invention, cooling was mainly described as water cooling. However, cooling the chlorofluorocarbon gas outside the wood using a refrigerator to lower the temperature to an appropriate temperature of -30°C was effective in preventing the reaction products from adhering to the wall surface.

加えて該当する部分が反応炉の活性領域のみならず基板
が設けられた領域の反応管の壁面をも併せて冷却し、ま
た基板の加熱ヒータを反応炉内に設け、それに密接させ
て基板をおき基板を加熱する方法をとってもよい。In addition, the corresponding part cools not only the active area of the reactor, but also the wall surface of the reaction tube in the area where the substrate is provided, and a heater for heating the substrate is installed in the reactor, and the substrate is placed in close contact with it. A method may also be used in which the substrate is heated.

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

第１図は本発明を実施するための反応装置の概要を示す
。FIG. 1 shows an overview of a reactor for carrying out the invention.

Claims (1)

【特許請求の範囲】 １、反応炉内に基板を配設させ該基板上に被膜を形成す
るとともに、前記反応炉の内壁に前記被膜または粉体を
付着形成させてしまう工程と、前記基板を前記反応炉よ
り除去する工程と、該工程の後、前記反応炉をとりはず
すことなく前記反応炉内壁に付着した被膜または粉体を
プラズマ気相エッチングせしめて除去する工程とを有す
ることを特徴とする反応炉内を清浄にする方法。 ２、反応炉内に基板を配設させ該基板上に被膜を形成す
るとともに、前記反応炉内に前記被膜または粉体を付着
形成させてしまう工程と、前記基板を前記反応炉より除
去する工程と、前記反応炉をとりはずすことなく前記反
応炉内壁に付着した前記被膜または粉体をプラズマ気相
エッチングせしめて除去する工程と、該工程の後、不活
性気体または窒素、またはそれに水素を添加した気体を
導入し、内壁に残存するエッチング用気体を除去する工
程と、該工程の後、前記反応炉内に基板を導入し、該基
板上に被膜を形成する工程とを有せしめることを特徴と
する反応炉内を清浄にする方法。 ３、特許請求の範囲第１項または第２項において、基板
上に形成される被膜は珪素、ゲルマニュームまたはその
化合物、ＢＰ、ＧａＡｓ等のIII−Ｖ化合物またはアル
ミニューム等の金属をＣＶＤ法で形成させることを特徴
とする反応炉内を清浄にする方法。 ４、特許請求の範囲第１項または第２項において、プラ
ズマ気相エッチング用気体は弗化窒素または塩化窒素よ
りなることを特徴とする反応炉内を清浄にする方法。 ５、特許請求の範囲第１項または第２項において、反応
炉は管状を有し、該反応管は５〜３０ｃｍの直径と１〜
５ｍの長さを有する大口径の可動しにくい装置よりなる
ことを特徴とする反応炉内を清浄にする方法。[Claims] 1. A step of disposing a substrate in a reactor, forming a film on the substrate, and depositing the film or powder on the inner wall of the reactor; It is characterized by comprising a step of removing it from the reactor, and a step of removing the film or powder attached to the inner wall of the reactor by plasma vapor phase etching after the step, without removing the reactor. How to clean the inside of a reactor. 2. A step of disposing a substrate in a reactor, forming a film on the substrate, and depositing the film or powder in the reactor, and a step of removing the substrate from the reactor. a step of removing the film or powder attached to the inner wall of the reactor without removing the reactor by plasma vapor phase etching; and after the step, adding an inert gas or nitrogen, or hydrogen to it. It is characterized by comprising the steps of introducing a gas and removing the etching gas remaining on the inner wall, and after the step, introducing a substrate into the reactor and forming a film on the substrate. How to clean the inside of a reactor. 3. In claim 1 or 2, the film formed on the substrate is made of silicon, germanium or a compound thereof, a III-V compound such as BP, GaAs, or a metal such as aluminum by a CVD method. A method for cleaning the inside of a reactor, characterized by: 4. A method for cleaning the inside of a reactor according to claim 1 or 2, characterized in that the gas for plasma vapor phase etching consists of nitrogen fluoride or nitrogen chloride. 5. In claim 1 or 2, the reactor has a tubular shape, and the reaction tube has a diameter of 5 to 30 cm and a diameter of 1 to 30 cm.
A method for cleaning the inside of a reactor, characterized by comprising a large-diameter, difficult-to-move device having a length of 5 m.