JPH06168886A - Formation of thin film by plasma cvd - Google Patents
Formation of thin film by plasma cvdInfo
- Publication number
- JPH06168886A JPH06168886A JP32003292A JP32003292A JPH06168886A JP H06168886 A JPH06168886 A JP H06168886A JP 32003292 A JP32003292 A JP 32003292A JP 32003292 A JP32003292 A JP 32003292A JP H06168886 A JPH06168886 A JP H06168886A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- film
- material gas
- film forming
- raw material
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、薄膜トランジスタや太
陽電池等に利用される結晶質若しくは非晶質シリコン等
の薄膜形成方法に係り、特に、形成された薄膜内に不純
物や欠陥の少ない膜質均一な薄膜を簡便に製膜できるプ
ラズマＣＶＤによる薄膜形成方法の改良に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film of crystalline or amorphous silicon used in a thin film transistor, a solar cell or the like, and more particularly to a uniform film quality with few impurities and defects in the formed thin film. The present invention relates to improvement of a thin film forming method by plasma CVD capable of easily forming a thin film.
【０００２】[0002]
【従来の技術】この種の薄膜として多結晶シリコン薄膜
を例に挙げてその製膜方法を説明すると、多結晶シリコ
ン薄膜の製膜方法としては、従来、熱ＣＶＤによる方法
が知られている。例えば、特開昭５８−１７２２１７号
公報においては４００〜９００℃に加熱された製膜室内
へシラン化合物を供給して熱ＣＶＤを行い、基板上へ多
結晶シリコン薄膜を形成する方法が開示されている。2. Description of the Related Art A polycrystalline silicon thin film is taken as an example of this type of thin film and its film forming method will be described. As a method of forming a polycrystalline silicon thin film, a method by thermal CVD has been conventionally known. For example, Japanese Unexamined Patent Publication No. 58-172217 discloses a method of supplying a silane compound into a film forming chamber heated to 400 to 900 ° C. and performing thermal CVD to form a polycrystalline silicon thin film on a substrate. There is.
【０００３】しかし、この熱ＣＶＤによる製膜方法は伝
熱効率の悪い反応ガスを高温に加熱するため多量のエネ
ルギーを必要とし、かつ、加熱冷却に時間とコストがか
かりその生産性が悪いという問題があり、また、その温
度条件を４００〜７００℃程度の低温に設定した場合に
は製膜速度が極端に遅くなる欠点があった。However, this method of forming a film by thermal CVD requires a large amount of energy in order to heat a reaction gas having a poor heat transfer efficiency to a high temperature, and has a problem that heating and cooling take time and cost, resulting in poor productivity. However, when the temperature condition is set to a low temperature of about 400 to 700 ° C., there is a drawback that the film forming rate becomes extremely slow.
【０００４】また、この熱ＣＶＤによる製膜方法におい
ては、通常、基板が７００℃以上の高温に晒されるため
安価なガラス基板等の適用が困難となる欠点があり、か
つ、アルミナ基板や炭素系基板等の耐熱性基板を適用し
た場合、この基板が７００℃以上の高温に晒されると基
板中に含まれるアルミニウム等の不純物が製膜された多
結晶シリコン等薄膜内へ拡散され易いためその薄膜特性
を悪化させてしまうことも報告されている（「最新ＬＳ
Ｉプロセス技術」、ｐ１０９、昭和５８年発行、前田和
夫著、工業調査会編）。Further, in this film forming method by thermal CVD, the substrate is usually exposed to a high temperature of 700 ° C. or higher, so that it is difficult to apply an inexpensive glass substrate or the like, and an alumina substrate or a carbon-based substrate is used. When a heat-resistant substrate such as a substrate is applied, when the substrate is exposed to a high temperature of 700 ° C. or higher, impurities contained in the substrate such as aluminum are easily diffused into a thin film such as polycrystalline silicon, so that the thin film It has also been reported that it deteriorates the characteristics ("Latest LS"
I Process Technology ", p109, published in 1983, by Kazuo Maeda, edited by the Industrial Research Committee).
【０００５】このため、最近、低温で多結晶シリコン等
の薄膜を製膜できるプラズマＣＶＤ法が注目されている
（例えば、特開昭６３−１５７８７２号公報、特開昭６
３−１７５４１７号公報参照）。すなわち、これ等公報
に開示されている方法は、密閉された製膜室内にシリコ
ン原子、ハロゲン原子、及び、水素原子を含有する原料
ガスを供給し、かつ、これをプラズマ化すると共に、基
板上で反応させて多結晶シリコンの薄膜を製膜する方法
で、上述した熱ＣＶＤ法に較べて低温条件で薄膜の形成
が可能となる利点を有する方法であった。For this reason, recently, a plasma CVD method capable of forming a thin film of polycrystalline silicon or the like at a low temperature has attracted attention (for example, JP-A-63-157872 and JP-A-6-157782).
(See Japanese Patent Laid-Open No. 3-175417). That is, the method disclosed in these publications is to supply a source gas containing silicon atoms, halogen atoms, and hydrogen atoms into a closed film forming chamber, and to convert the source gas into a plasma and to The method of forming a thin film of polycrystalline silicon by reacting with the above method has an advantage that a thin film can be formed under low temperature conditions as compared with the above-mentioned thermal CVD method.
【０００６】[0006]
【発明が解決しようとする課題】ところで、このプラズ
マＣＶＤ法においては上述したように低温製膜を可能に
する利点を有しているが、その反面、製膜工程中におい
て粉状の浮遊異物が製膜室内に多量に発生しこの浮遊異
物が製膜途上の薄膜内に混入されてその薄膜特性を劣化
させ易い問題点があった。By the way, the plasma CVD method has an advantage of enabling low temperature film formation as described above, but on the other hand, powdery floating foreign matters are generated during the film formation process. There has been a problem that a large amount of the floating foreign matter is generated in the film forming chamber and is mixed in the thin film during film formation, and the thin film characteristics are easily deteriorated.
【０００７】すなわち、このプラズマＣＶＤ法は原料ガ
スをプラズマ化しその反応性を高めることにより低温条
件での薄膜形成を可能にする製膜方法である。That is, the plasma CVD method is a film forming method which makes it possible to form a thin film under a low temperature condition by converting a raw material gas into a plasma and increasing its reactivity.
【０００８】従って、製膜室内のプラズマ化された原料
ガスは励起状態にあるため、製膜室の空間において原料
ガスが互いに反応して薄膜材料の粉状体を生成したり、
基板以外の部位すなわち製膜室の内壁面においてプラズ
マ化された原料ガスが反応して析出しこれが粉状体とな
って剥離する等粉状の浮遊異物が多量に発生し易い状態
にある。また、原料ガスにはハロゲン原子等腐食性の高
いガスも含まれるため、この腐食性ガスにより製膜室の
内壁面が腐食されかつその腐食面が剥離して上記浮遊異
物の一部を構成することになる。Therefore, since the raw material gas which has been turned into plasma in the film forming chamber is in an excited state, the raw material gases react with each other in the space of the film forming chamber to generate a powdery material of the thin film material,
In a portion other than the substrate, that is, on the inner wall surface of the film forming chamber, the raw material gas that has been turned into plasma reacts and deposits, which becomes a powder and is easily peeled off. Further, since the raw material gas also contains highly corrosive gases such as halogen atoms, the corrosive gas corrodes the inner wall surface of the film forming chamber and separates the corroded surface to form a part of the above-mentioned suspended foreign matter. It will be.
【０００９】このように、このプラズマＣＶＤ法におい
ては製膜工程中に粉状の浮遊異物が製膜室内に多量に発
生し、これが製膜途上の薄膜内に混入されてその薄膜特
性を劣化させ易い問題点があった。As described above, in this plasma CVD method, a large amount of powdery floating foreign matter is generated in the film forming chamber during the film forming process, and this is mixed in the thin film during film formation and deteriorates the thin film characteristics. There was an easy problem.
【００１０】尚、製膜室内における浮遊異物の発生量が
増大した段階で製膜処理を一旦中断し、製膜室内を排気
して粉状の浮遊異物を完全に取除いた後、原料ガスを供
給し製膜処理を再開して上記問題を回避する方法も考え
られる。When the amount of floating foreign matter generated in the film forming chamber increases, the film forming process is temporarily interrupted, the film forming chamber is evacuated to completely remove the powdery floating foreign matter, and then the raw material gas is discharged. A method of avoiding the above problem by supplying the film and restarting the film forming process is also conceivable.
【００１１】しかし、このような方法を採った場合、中
断前と後でその製膜条件が大きく相違し製膜された薄膜
に膜特性の異なる界面が形成され易くなるため、その厚
み方向の特性がばらついてしまう問題点があった。However, when such a method is adopted, the film forming conditions before and after the interruption are largely different, and an interface having different film characteristics is easily formed in the formed thin film, so that the characteristics in the thickness direction are formed. However, there was a problem in that
【００１２】本発明はこのような問題点に着目してなさ
れたもので、その課題とするところは、薄膜内に不純物
や欠陥の少ない膜質均一な薄膜を簡便に製膜できるプラ
ズマＣＶＤによる薄膜形成方法を提供することにある。The present invention has been made by paying attention to such a problem, and its object is to form a thin film by plasma CVD capable of easily forming a thin film having a uniform film quality with few impurities and defects in the thin film. To provide a method.
【００１３】[0013]
【課題を解決するための手段】すなわち請求項１に係る
発明は、密閉された製膜室内に原料ガスを供給しこれを
プラズマ化して基板上に製膜するプラズマＣＶＤによる
薄膜形成方法を前提とし、製膜工程途中において上記原
料ガスの供給を停止することなく製膜室内を排気して製
膜中に発生した粉状の浮遊異物を排除する排気工程を付
加したことを特徴とするものである。That is, the invention according to claim 1 is premised on a thin film forming method by plasma CVD in which a raw material gas is supplied into a closed film forming chamber, and this is turned into plasma to form a film on a substrate. The present invention is characterized in that an exhaust step for exhausting the powdery suspended foreign matter generated during film formation by exhausting the film forming chamber without stopping the supply of the raw material gas during the film forming step is added. .
【００１４】このような技術的手段において上記原料ガ
スとしてはその目的とする薄膜の種類によって任意に選
定され、例えば、上記薄膜がシリコンの単結晶膜、多結
晶膜若しくは非晶質膜の場合には、シリコン原子、ハロ
ゲン原子、及び、水素原子を含有する混合ガスが選定さ
れる。In such a technical means, the raw material gas is arbitrarily selected according to the kind of the intended thin film. For example, when the thin film is a silicon single crystal film, a polycrystalline film or an amorphous film. Is selected as a mixed gas containing silicon atoms, halogen atoms, and hydrogen atoms.
【００１５】そして、上記シリコン膜を例に挙げてその
具体的材料を説明すると、製膜性を有するシリコン原子
の供給ガスとしてはＳｉＨ4、Ｓｉ2Ｈ6、Ｓｉ3Ｈ8 等の
水素化珪素、ＳｉＨmＸ4-m（但し、ｍは１〜３、好まし
くは２〜３、ＸはＣｌ又はＦ原子、好ましくはＦ原子で
ある）で示されるハロゲン化シラン、ＳｉＦ4 、ＳｉＣ
ｌ4並びにＳｉ2Ｆ6より任意に選択されたハロゲン化珪
素が適用できる。A specific material will be described by taking the above-mentioned silicon film as an example. As a supply gas of silicon atoms having film-forming properties, silicon hydrides such as SiH 4 , Si 2 H 6 and Si 3 H 8 are used. , SiH m X 4-m (provided that m is 1 to 3, preferably 2 to 3, X is Cl or F atom, preferably F atom), SiF 4 , SiC
Silicon halides arbitrarily selected from l 4 and Si 2 F 6 can be applied.
【００１６】また、エッチング性を有するハロゲン原子
の供給ガスとしては、上記ＳｉＦ4、ＳｉＣｌ4及びＳｉ
2Ｆ6 等のハロゲン化珪素や、ＳｉＨmＸ4-mで示される
ハロゲン化シラン、及び、Ｆ2、Ｃｌ2等のハロゲンガス
が適用でき、他方、水素原子の供給ガスとしては、水素
ガス、ＳｉＨ4、Ｓｉ2Ｈ6、Ｓｉ3Ｈ8 等の水素化珪素、
ＳｉＨmＸ4-mで示されるハロゲン化シラン等の適用が可
能である。Further, as the supply gas of the halogen atom having an etching property, the above SiF 4 , SiCl 4 and Si are used.
Silicon halides such as 2 F 6 and the like, halogenated silanes represented by SiH m X 4-m , and halogen gases such as F 2 and Cl 2 can be applied. On the other hand, hydrogen gas can be supplied as hydrogen gas. , SiH 4 , Si 2 H 6 , Si 3 H 8 and other silicon hydrides,
A halogenated silane represented by SiH m X 4-m or the like can be applied.
【００１７】尚、上記原料ガス中に希釈ガスとして、ヘ
リウム、ネオン、アルゴン等の不活性ガスを加えてもよ
い。An inert gas such as helium, neon or argon may be added as a diluent gas to the raw material gas.
【００１８】上述したような原料ガスを製膜室内に導入
し、かつ、この原料ガスを電力密度０．０１〜１０Ｗ／
ｃｍ2 、好ましくは０．０５〜５Ｗ／ｃｍ2 程度の条件
で放電してプラズマ化すると共に、略一定温度に加熱さ
れたガラス、セラミックス、金属等の基板上に、若しく
は単結晶シリコン基板等の単結晶基板上にシリコン等の
薄膜を製膜する方法である。The raw material gas as described above is introduced into the film forming chamber, and the raw material gas is supplied at a power density of 0.01 to 10 W /
cm 2 , preferably about 0.05 to 5 W / cm 2 and discharged to plasma, and on a substrate of glass, ceramics, metal, etc. heated to a substantially constant temperature, or on a single crystal silicon substrate, etc. This is a method of forming a thin film of silicon or the like on a single crystal substrate.
【００１９】ここで、上記基板の加熱温度についてはそ
の目的とする薄膜が結晶質か非晶質かによって適宜設定
され、その薄膜が結晶質の場合には高温に、また目的と
する薄膜が非晶質の場合にはこれより低温に設定され
る。Here, the heating temperature of the substrate is appropriately set depending on whether the target thin film is crystalline or amorphous. If the thin film is crystalline, the temperature is high and the target thin film is non-crystalline. In the case of crystalline, the temperature is set lower than this.
【００２０】また、上記電力密度については原料ガスの
種類、及び、製膜室内の設定圧力によって異なるが、電
力密度が０．０１Ｗ／ｃｍ2 より小さいと上記原料ガス
の圧力を十分低下させなければならないため製膜速度が
遅くなり、１０Ｗ／ｃｍ2 を越えると薄膜の品質を高く
維持することが難しくなるため、通常、上述したように
０．０１〜１０Ｗ／ｃｍ2 に設定される。The power density varies depending on the type of raw material gas and the set pressure in the film forming chamber, but if the power density is less than 0.01 W / cm 2 , the pressure of the raw material gas must be sufficiently reduced. film speed is slower made for not, since is possible to maintain high exceeds 10 W / cm 2 the quality of the thin film becomes difficult, typically, is set to 0.01 to 10 / cm 2 as described above.
【００２１】他方、上記プラズマを発生させる製膜室内
の圧力は基板上に到達する原子等が有するエネルギー量
に関係し、通常、その圧力は０．０１Ｔｏｒｒ〜１５Ｔ
ｏｒｒに設定される。On the other hand, the pressure in the film forming chamber for generating the plasma is related to the amount of energy of atoms or the like reaching the substrate, and the pressure is usually 0.01 Torr to 15T.
Set to orr.
【００２２】そして、この発明においては製膜工程途中
において上記原料ガスの供給を停止することなく製膜室
内を排気して製膜中に発生した粉状の浮遊異物を排除す
る排気工程を付加したことを特徴としている。すなわ
ち、この技術的手段においては、製膜室内における浮遊
異物の発生量が増大した段階で製膜室内への原料ガスの
供給を停止することなく（すなわち製膜処理を中断する
ことなく）製膜室内を排気して上記浮遊異物を排除する
ことを特徴とするものである。このようにこの発明にお
いては、上記浮遊異物を排除する排気工程中、製膜処理
は中断することなく継続しているため膜特性の異なる界
面が薄膜内に形成されることがなくその厚み方向の膜質
を均一にすることが可能となり、かつ、上記浮遊異物も
排除されこの浮遊異物が製膜途上の薄膜内に混入される
可能性も少なくなるため薄膜内における不純物や欠陥の
低減が図れる。Further, in the present invention, an exhaust step is added during the film forming step to exhaust the inside of the film forming chamber without stopping the supply of the raw material gas to eliminate the powdery suspended foreign matter generated during the film forming. It is characterized by that. That is, in this technical means, the film formation is not stopped (that is, the film formation process is not interrupted) without stopping the supply of the raw material gas into the film formation chamber when the amount of floating foreign matter generated in the film formation chamber is increased. The inside of the room is evacuated to eliminate the floating foreign matter. As described above, in the present invention, since the film forming process is continued without interruption during the evacuation process for eliminating the floating foreign matter, an interface having different film characteristics is not formed in the thin film, and the film thickness direction is increased. The film quality can be made uniform, and the above-mentioned floating foreign matter is eliminated and the possibility that this floating foreign matter is mixed into the thin film during film formation is reduced, so that impurities and defects in the thin film can be reduced.
【００２３】但し、この発明において製膜処理を中断す
ることなく浮遊異物の排除を行うためには、上記製膜室
内への原料ガスの供給量とこの製膜室から排除する浮遊
異物の排気量とのバランスを図ることが前提となる。However, in the present invention, in order to remove the floating foreign matter without interrupting the film forming process, the amount of the source gas supplied to the film forming chamber and the exhaust amount of the floating foreign matter to be removed from the film forming chamber. It is a prerequisite to balance with.
【００２４】すなわち、上記製膜室に接続された排気ポ
ンプ等により排気処理を行う際、その排気量を極端に大
きく設定すると浮遊異物と共に製膜室内に供給された原
料ガスまで全て排除されてしまい上記製膜処理を継続さ
せることが困難になる場合があるからである。That is, when performing an exhaust process with an exhaust pump or the like connected to the film forming chamber, if the exhaust amount is set to an extremely large amount, all the raw material gas supplied into the film forming chamber together with suspended foreign matter will be excluded. This is because it may be difficult to continue the film forming process.
【００２５】従って、原料ガスの供給量と浮遊異物の排
気量とのバランスを図ることが必要となり、例えば、以
下のような方法を例示できる。尚、上記プラズマを継続
させた状態で排気処理を行う場合と、一旦プラズマを切
った状態で排気処理を行う場合とでその条件は若干相違
する。すなわち、プラズマが継続されていると製膜室内
の浮遊異物はこのプラズマの影響を受けて排気され難く
なるからである。Therefore, it is necessary to balance the supply amount of the raw material gas and the exhaust amount of the floating foreign matter. For example, the following method can be exemplified. The conditions are slightly different between the case where the exhaust process is carried out while the plasma is continued and the case where the exhaust process is carried out once the plasma is cut off. That is, if the plasma is continued, the floating foreign matter in the film forming chamber is affected by the plasma and is difficult to be exhausted.
【００２６】以下、具体的に説明すると、上記プラズマ
を継続させながら製膜室内の真空度を１×１０-4Ｔｏｒ
ｒ程度まで高めて排気する方法が挙げられる。この場
合、製膜室内の真空度を高めるために原料ガスの供給量
は低減されるが、製膜室内の原料ガスが完全になくなる
ことはないため製膜処理が中断されることはない。More specifically, the vacuum degree in the film forming chamber is set to 1 × 10 −4 Tor while continuing the above plasma.
An example is a method of exhausting after elevating to about r. In this case, the supply amount of the raw material gas is reduced to increase the degree of vacuum in the film forming chamber, but the raw material gas in the film forming chamber is not completely exhausted, so that the film forming process is not interrupted.
【００２７】また、上記プラズマを継続させると共に製
膜室内の真空度を変えずに排気条件を強めて浮遊異物を
排除する方法を採ってもよい。すなわち、従来のプラズ
マＣＶＤ法においても製膜処理中にこの製膜室内の真空
度を維持するため低い条件ながら排気はなされている。
そこで、この排気条件を上記浮遊異物が排除される程度
まで強めて行う方法を採ってもよい。但し、その条件が
強過ぎると上述したように製膜処理を継続させることが
困難になるため、例えば、製膜室内の浮遊異物の存在量
に合わせて排気ポンプに接続された調圧弁の開き具合を
調整する（すなわち、浮遊異物が多量に存在する排気工
程の初期段階においては排気量を大きく設定し、かつ、
浮遊異物の減少に伴ってその排気量を順次小さく設定す
る）と共に、この浮遊異物の排気量に追随させて原料ガ
スの供給量を調整して（すなわち、上記排気量が大きい
ときには原料ガスの供給量を増大させその供給量を過多
にして浮遊異物と共に排除される原料ガスを補う一方、
排気量の減少に追随させて原料ガスの供給量を排気工程
前の供給量に順次戻す）製膜室内の真空度を維持させる
方法が挙げられる。Further, a method may be adopted in which the above-mentioned plasma is continued and the exhaust conditions are strengthened without changing the degree of vacuum in the film forming chamber to eliminate suspended foreign matters. That is, even in the conventional plasma CVD method, exhaust is performed under low conditions in order to maintain the degree of vacuum in the film forming chamber during the film forming process.
Therefore, a method may be adopted in which the exhaust conditions are strengthened to the extent that the floating foreign matter is eliminated. However, if the conditions are too strong, it becomes difficult to continue the film forming process as described above.For example, the opening degree of the pressure regulating valve connected to the exhaust pump is adjusted according to the amount of floating foreign matter in the film forming chamber. (That is, set a large exhaust amount in the initial stage of the exhaust process in which a large amount of airborne foreign matter exists, and
The exhaust amount is set to be smaller in sequence as the amount of suspended particles decreases, and the supply amount of the source gas is adjusted to follow the exhaust amount of the suspended particles (that is, the source gas is supplied when the exhaust amount is large). While increasing the amount and supplying too much to supplement the raw material gas that is eliminated together with the floating foreign matter,
There is a method of maintaining the degree of vacuum in the film forming chamber by following the decrease of the exhaust amount and sequentially returning the supply amount of the raw material gas to the supply amount before the exhaust step.
【００２８】他方、上記プラズマを切った状態で排気処
理を行う場合には浮遊異物と共に原料ガスも製膜室内か
ら容易に排除されてしまうため、原料ガスの供給量が過
多になる条件でこれを行う方法が挙げられる。尚、この
方法においては浮遊異物が短時間で排除されるため、プ
ラズマを継続させた条件で排気を行う前者の方法に較べ
その停止タイミングを早く設定することが望ましい。On the other hand, when performing the exhaust treatment with the plasma turned off, the raw material gas is easily removed from the film forming chamber together with the floating foreign matter, so that the raw material gas is supplied under an excessive amount. The method to do is mentioned. In this method, suspended foreign matter is eliminated in a short time, so it is desirable to set the stop timing earlier than the former method in which exhaust is performed under the condition that plasma is continued.
【００２９】次に、上記排気工程を行うタイミングにつ
いては、製膜室内における浮遊異物の発生量が増大し製
膜途上の薄膜内に混入される可能性が大となった時点で
これを行うことが薄膜形成の効率上望ましい。Next, regarding the timing of performing the above-mentioned exhaust step, it should be performed when the amount of floating foreign matter generated in the film forming chamber increases and there is a high possibility that it will be mixed into the thin film during film formation. Is desirable in terms of thin film formation efficiency.
【００３０】但し、製膜室内の状態を外部から目視する
ことは通常困難なため、以下のような方法によりその開
始タイミングを設定する方法を例示できる。すなわち、
製膜室内に原料ガスを供給しこれをプラズマ化して基板
上に薄膜を連続的に製膜する予備試験をまず行う。この
場合、その製膜時間を１時間、２時間、３時間、………
１０時間等（求める薄膜の目的とする膜厚の値に応じて
最長時間を設定する）各々設定して個々に製膜処理を行
い、かつ、求められた各薄膜内の欠陥密度を各々調べる
と共に、各予備試験の結果から製膜時間と欠陥密度との
関係をプロットして排気工程の開始タイミングを事前に
求める方法が挙げられる。However, since it is usually difficult to visually check the state of the inside of the film forming chamber from the outside, a method of setting the start timing by the following method can be exemplified. That is,
First, a preliminary test for supplying a raw material gas into the film forming chamber and converting it into plasma to continuously form a thin film on a substrate is performed. In this case, the film forming time is 1 hour, 2 hours, 3 hours, ...
10 hours or the like (the maximum time is set according to the desired film thickness value of the thin film to be set), the film forming process is individually performed, and the defect densities in the respective thin films thus obtained are examined. The method of plotting the relationship between the film formation time and the defect density from the result of each preliminary test to obtain the start timing of the exhaust process in advance can be mentioned.
【００３１】[0031]
【作用】請求項１に係る発明によれば、製膜工程途中に
おいて原料ガスの供給を停止することなく製膜室内を排
気して製膜中に発生した粉状の浮遊異物を排除する排気
工程を付加しており、この排気工程中、製膜処理は中断
することなく継続しているため膜特性の異なる界面が薄
膜内に形成されなくなりその厚み方向の膜質を均一にす
ることが可能となり、かつ、上記浮遊異物も排除されこ
の浮遊異物が製膜途上の薄膜内に混入される可能性も少
なくなるため薄膜内における不純物や欠陥の低減が図れ
る。According to the first aspect of the invention, an exhaust process for exhausting the powdery suspended foreign matter generated during film formation by exhausting the film forming chamber without stopping the supply of the raw material gas during the film forming process. In addition, during this evacuation process, since the film forming process is continued without interruption, interfaces with different film characteristics are not formed in the thin film, and the film quality in the thickness direction can be made uniform, In addition, since the floating foreign matter is also eliminated and the possibility that the floating foreign matter is mixed into the thin film during film formation is reduced, impurities and defects in the thin film can be reduced.
【００３２】[0032]
【実施例】以下、本発明の実施例について詳細に説明す
るが本発明はこれ等実施例によって限定されるものでは
ない。EXAMPLES Examples of the present invention will now be described in detail, but the present invention is not limited to these examples.
【００３３】尚、図１は実施例で適用されたプラズマＣ
ＶＤ装置の概略構成を示した説明図で、図中１１は密閉
された製膜室、１２は電極、１３はヒータ１５が組込ま
れた電極、１４はこの電極１３に取付けられた基板、１
６は高周波電源、１７、１８は原料ガスの供給源、及
び、１９は調圧弁２０を介し製膜室１１に接続された減
圧ポンプをそれぞれ示している。Incidentally, FIG. 1 shows the plasma C applied in the embodiment.
FIG. 1 is an explanatory view showing a schematic configuration of a VD apparatus, in which 11 is a sealed film forming chamber, 12 is an electrode, 13 is an electrode in which a heater 15 is incorporated, 14 is a substrate attached to this electrode 13, 1
Reference numeral 6 denotes a high-frequency power source, 17 and 18 denote a source of a source gas, and 19 denotes a decompression pump connected to the film forming chamber 11 via a pressure regulating valve 20, respectively.
【００３４】［実施例１］まず、以下の予備試験を行い
図２の製膜時間（ｈｒ）と欠陥密度 ( ／ｃｍ2)との関
係を示したグラフ図を求めた。Example 1 First, the following preliminary test was performed to obtain a graph showing the relationship between the film forming time (hr) and the defect density (/ cm 2 ) shown in FIG.
【００３５】すなわち、１×１０-6Ｔｏｒｒの真空にし
た製膜室１１内にＳｉＦ4：ＳｉＨ4：Ｆ2（ガス比率は
容積比で２：１：５、また、Ｆ／Ｈ比率は９：２であ
る）の混合ガスを原料ガスとして８０ＳＣＣＭで供給
し、原料ガスの圧力を０．３Ｔｏｒｒに調整した。That is, SiF 4 : SiH 4 : F 2 (the gas ratio is 2: 1: 5 in volume ratio, and the F / H ratio is 9 in the film forming chamber 11 evacuated to 1 × 10 -6 Torr). : 2) was mixed as a raw material gas at 80 SCCM, and the pressure of the raw material gas was adjusted to 0.3 Torr.
【００３６】次いで、この原料ガスを１３．５６ＭＨｚ
の高周波電源を用いて電力密度０．１Ｗ／ｃｍ2 でプラ
ズマ化し、３５０℃に加熱された単結晶シリコン基板上
にエピタキシャルシリコン薄膜を連続的に製膜した。Next, this raw material gas is fed at 13.56 MHz.
Plasma was formed at a power density of 0.1 W / cm 2 by using the high frequency power source of No. 1 , and an epitaxial silicon thin film was continuously formed on the single crystal silicon substrate heated at 350 ° C.
【００３７】そして、製膜時間を１時間、２時間、３時
間……７時間（この例では求めるエピタキシャルシリコ
ン薄膜の膜厚を１０〜２０μｍに設定している）と順次
設定し、かつ、求められた各エピタキシャルシリコン薄
膜の欠陥密度を各々調べると共に、図２の製膜時間（ｈ
ｒ）と欠陥密度（ ／ｃｍ2 ）との関係を示したグラフ
図を求めた。Then, the film forming time is sequentially set to 1 hour, 2 hours, 3 hours, ... 7 hours (in this example, the film thickness of the epitaxial silicon thin film to be obtained is set to 10 to 20 μm), and the film forming time is obtained. The defect densities of the respective epitaxial silicon thin films thus obtained were examined and the film formation time (h
A graph showing the relationship between r) and the defect density (/ cm 2 ) was obtained.
【００３８】尚、上記欠陥密度はエピタキシャルシリコ
ン薄膜の表面積当りの結晶欠陥（均一分布）を測定して
求めたもので、欠陥密度が１０3 （ ／ｃｍ2 ）程度の
ものは欠陥の少ない結晶性良好なシリコン膜を意味して
おり、欠陥密度が１０6 （／ｃｍ2 ）程度になると欠陥
の多い結晶性があまり良好でないシリコン膜を意味して
いる。そして、図２の結果から上記欠陥密度が１×１０
5 〜２×１０5 （／ｃｍ2 ）程度（すなわち製膜時間が
１〜２時間）になった時点で排気工程を開始すればよい
ことが確認された。The defect density is obtained by measuring the crystal defects (uniform distribution) per surface area of the epitaxial silicon thin film, and the defect density of about 10 3 (/ cm 2 ) has a low crystallinity. This means a good silicon film, and when the defect density is about 10 6 (/ cm 2 ), it means a silicon film with many defects and not so good crystallinity. From the result of FIG. 2, the defect density is 1 × 10.
It was confirmed that the evacuation process should be started when the film formation time reaches about 5 to 2 × 10 5 (/ cm 2 ) (that is, the film formation time is 1 to 2 hours).
【００３９】そこで、この予備試験の結果に基づき以下
の条件により結晶性良好な膜厚１０〜２０μｍのエピタ
キシャルシリコン薄膜を求めた。Therefore, based on the results of this preliminary test, an epitaxial silicon thin film having a good crystallinity and a film thickness of 10 to 20 μm was obtained under the following conditions.
【００４０】すなわち、予備試験と同様に、１×１０-6
Ｔｏｒｒの真空にした製膜室１１内にＳｉＦ4：Ｓｉ
Ｈ4：Ｆ2（ガス比率は容積比で２：１：５、また、Ｆ／
Ｈ比率は９：２である）の混合ガスを原料ガスとして８
０ＳＣＣＭで供給し、原料ガスの圧力を０．３Ｔｏｒｒ
に調整した。That is, as in the preliminary test, 1 × 10 -6
SiF 4 : Si in the film forming chamber 11 which is evacuated to Torr.
H 4 : F 2 (gas ratio is 2: 1: 5 by volume, and F /
The H gas ratio is 9: 2) and the mixed gas is 8
Supply at 0 SCCM and set the source gas pressure to 0.3 Torr
Adjusted to.
【００４１】次いで、この原料ガスを１３．５６ＭＨｚ
の高周波電源を用いて電力密度０．１Ｗ／ｃｍ2 でプラ
ズマ化し、３５０℃に加熱された単結晶シリコン基板上
にエピタキシャルシリコン薄膜を連続的に製膜した。Next, this raw material gas is fed at 13.56 MHz.
Plasma was formed at a power density of 0.1 W / cm 2 by using the high frequency power source of No. 1 , and an epitaxial silicon thin film was continuously formed on the single crystal silicon substrate heated at 350 ° C.
【００４２】次に、製膜開始から１〜２時間経過した
後、調圧弁２０を製膜時より大きく開いた状態で減圧ポ
ンプ１９により製膜室１１内を排気しこの製膜室１１内
で発生した粉状の浮遊異物を排除する一方、上記原料ガ
スの供給量を８０ＳＣＣＭから１６０ＳＣＣＭに増大さ
せて上記浮遊異物といっしょに排除されてしまう原料ガ
スの一部を補い上記エピタキシャルシリコン膜の製膜処
理を継続させた。Next, after 1 to 2 hours have elapsed from the start of film formation, the inside of the film formation chamber 11 was evacuated by the decompression pump 19 with the pressure regulating valve 20 opened more widely than during film formation. The generated powdery floating foreign matter is excluded, while the supply amount of the raw material gas is increased from 80 SCCM to 160 SCCM to compensate for a part of the raw material gas that is removed together with the floating foreign matter. The process was continued.
【００４３】そして、製膜室１１内の浮遊異物を排除し
た後、上記減圧ポンプ１９による排気条件を元に戻すと
共に、原料ガスの供給量を排気処理前の８０ＳＣＣＭに
戻してエピタキシャルシリコン膜の製膜を継続し膜厚１
０〜２０μｍのエピタキシャルシリコン薄膜を製造し
た。After removing the floating foreign matter in the film forming chamber 11, the exhaust conditions by the decompression pump 19 are returned to the original condition, and the supply amount of the source gas is returned to 80 SCCM before the exhaust process to form the epitaxial silicon film. Continue film and film thickness 1
An epitaxial silicon thin film having a thickness of 0 to 20 μm was manufactured.
【００４４】得られた薄膜についてラマン分光分析を行
ったところ、５２０ｃｍ-1の位置に半値巾３．５ｃｍ-1
の結晶シリコンに基づく非常にシャープなスペクトルが
観測された。[0044] The obtained thin film was subjected to Raman spectroscopic analysis, the half width 3.5 cm -1 to the position of 520 cm -1
A very sharp spectrum based on the crystalline silicon was observed.
【００４５】また、求められたエピタキシャルシリコン
薄膜内の欠陥密度を測定したところ、結晶性が良好と評
価される１０4 （ ／ｃｍ2 ）程度の値を示すと共に、
不純物の混入も極めて少なかった。Further, when the defect density in the obtained epitaxial silicon thin film was measured, it showed a value of about 10 4 (/ cm 2 ) at which the crystallinity was evaluated as good, and
The inclusion of impurities was extremely small.
【００４６】更に、反射高速電子線回折（ＲＨＥＥＤ）
によってシリコン結晶薄膜の評価を行ったところ、スト
リークパターンと菊池ラインが観測され良好な単結晶で
あることが確認された。この薄膜の比抵抗は５０Ω・ｃ
ｍであり、電子移動度をファンデアポー法を適用したホ
ール効果測定装置により求めたところ１３００ｃｍ2／
Ｖ・Ｓであった。Furthermore, reflection high-energy electron diffraction (RHEED)
When the silicon crystal thin film was evaluated by, a streak pattern and a Kikuchi line were observed, and it was confirmed that the film was a good single crystal. The resistivity of this thin film is 50Ω · c
m, and the electron mobility was 1300 cm 2 / as determined by the Hall effect measuring device applying the van der Pauw method.
It was VS.
【００４７】［実施例２］予め１×１０-6 ｏｒｒの真
空にした製膜室１１内に、ＳｉＦ4：Ｈ2：Ｆ2（ガス比
率は容積比で２：１：５、また、Ｆ／Ｈ比率は９：１で
ある）の混合ガスを原料ガスとして８０ＳＣＣＭで供給
し、原料ガスの圧力を０．５Ｔｏｒｒに調整した。[Embodiment 2] SiF 4 : H 2 : F 2 (gas ratio is 2: 1: 5 by volume ratio, and F ratio is F in the film forming chamber 11 previously evacuated to 1 × 10 −6 orrr). The mixed gas (H / H ratio is 9: 1) was supplied as a raw material gas at 80 SCCM, and the pressure of the raw material gas was adjusted to 0.5 Torr.
【００４８】次いで、この原料ガスを１３．５６ＭＨｚ
の高周波電源を用いて電力密度０．１Ｗ／ｃｍ2 でプラ
ズマ化し、４５０℃に加熱されたガラス基板上に多結晶
シリコン薄膜を連続的に製膜した。Next, this raw material gas is fed at 13.56 MHz.
The plasma generation was carried out at a power density of 0.1 W / cm 2 using the above high frequency power source, and a polycrystalline silicon thin film was continuously formed on the glass substrate heated at 450 ° C.
【００４９】次に、製膜開始から１〜２時間経過した
後、調圧弁２０を製膜時より大きく開いた状態で減圧ポ
ンプ１９により製膜室１１内を排気しこの製膜室１１内
で発生した粉状の浮遊異物を排除する一方、上記原料ガ
スの供給量を８０ＳＣＣＭから１６０ＳＣＣＭに増大さ
せて上記浮遊異物といっしょに排除されてしまう原料ガ
スの一部を補い上記多結晶シリコン膜の製膜処理を継続
させた。Next, after 1 to 2 hours have elapsed from the start of film formation, the inside of the film formation chamber 11 was evacuated by the decompression pump 19 with the pressure regulating valve 20 opened more widely than during film formation. While removing the generated powdery floating foreign matter, the supply amount of the raw material gas is increased from 80 SCCM to 160 SCCM to compensate for a part of the raw material gas that is removed together with the floating foreign matter. The membrane treatment was continued.
【００５０】そして、製膜室１１内の浮遊異物を排除し
た後、上記減圧ポンプ１９による排気条件を元に戻すと
共に、原料ガスの供給量を排気処理前の８０ＳＣＣＭに
戻して製膜を継続し膜厚１０〜２０μｍの多結晶シリコ
ン薄膜を製造した。Then, after the floating foreign matter in the film forming chamber 11 is eliminated, the exhaust condition by the decompression pump 19 is returned to the original condition and the supply amount of the raw material gas is returned to 80 SCCM before the exhaust treatment to continue the film formation. A polycrystalline silicon thin film having a film thickness of 10 to 20 μm was manufactured.
【００５１】尚、製膜途中において浮遊異物の排除処理
を行わなかった比較例に係る多結晶シリコン薄膜とその
結晶性を比較したところ、実施例に係る多結晶シリコン
薄膜が格段に優れていた。When the polycrystal silicon thin film according to the comparative example in which the floating foreign matter was not removed during the film formation was compared with the crystallinity, the polycrystal silicon thin film according to the example was remarkably excellent.
【００５２】[0052]
【発明の効果】請求項１に係る発明によれば、製膜工程
途中において原料ガスの供給を停止することなく製膜室
内を排気して製膜中に発生した粉状の浮遊異物を排除す
る排気工程を付加しており、この排気工程中、製膜処理
は中断することなく継続しているため膜特性の異なる界
面が薄膜内に形成されなくなりその厚み方向の膜質を均
一にすることが可能となり、かつ、上記浮遊異物も排除
されこの浮遊異物が製膜途上の薄膜内に混入される可能
性も少なくなるため薄膜内における不純物や欠陥の低減
が図れる。According to the invention of claim 1, the film-forming chamber is evacuated without stopping the supply of the raw material gas during the film-forming process to eliminate the powdery foreign matter generated during the film-forming process. An evacuation process is added, and during this evacuation process, the film formation process continues without interruption, so that interfaces with different film characteristics are not formed in the thin film, and the film quality in the thickness direction can be made uniform. In addition, since the floating foreign matter is also eliminated and the possibility that the floating foreign matter is mixed into the thin film during film formation is reduced, impurities and defects in the thin film can be reduced.
【００５３】従って、形成された薄膜内に不純物や欠陥
の少ない膜質均一な薄膜を簡便に製膜できる効果を有し
ている。Therefore, there is an effect that a thin film having a uniform film quality with few impurities and defects can be easily formed in the formed thin film.
【図１】実施例において適用されたプラズマＣＶＤ装置
の概略構成説明図。FIG. 1 is a schematic configuration explanatory view of a plasma CVD apparatus applied in an example.
【図２】予備試験により求められた製膜時間と欠陥密度
との関係を示すグラフ図。FIG. 2 is a graph showing the relationship between film formation time and defect density obtained by a preliminary test.
１１ 製膜室 １２ 電極 １３ 電極 １４ 基板 １５ ヒータ １６ 高周波電源 １７ 原料ガス供給源 １８ 原料ガス供給源 １９ 減圧ポンプ ２０ 調圧弁 11 film forming chamber 12 electrode 13 electrode 14 substrate 15 heater 16 high frequency power supply 17 raw material gas supply source 18 raw material gas supply source 19 pressure reducing pump 20 pressure regulating valve
Claims (1)
れをプラズマ化して基板上に製膜するプラズマＣＶＤに
よる薄膜形成方法において、 製膜工程途中において上記原料ガスの供給を停止するこ
となく製膜室内を排気して製膜中に発生した粉状の浮遊
異物を排除する排気工程を付加したことを特徴とするプ
ラズマＣＶＤによる薄膜形成方法。1. A method for forming a thin film by plasma CVD in which a raw material gas is supplied into a closed film forming chamber and the plasma is formed into a film on a substrate to stop the supply of the raw material gas during the film forming process. A method for forming a thin film by plasma CVD, characterized in that an exhaust step of exhausting the inside of the film forming chamber to eliminate powdery floating foreign matter generated during film forming is added.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32003292A JPH06168886A (en) | 1992-11-30 | 1992-11-30 | Formation of thin film by plasma cvd |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32003292A JPH06168886A (en) | 1992-11-30 | 1992-11-30 | Formation of thin film by plasma cvd |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06168886A true JPH06168886A (en) | 1994-06-14 |
Family
ID=18116991
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32003292A Pending JPH06168886A (en) | 1992-11-30 | 1992-11-30 | Formation of thin film by plasma cvd |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06168886A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005243951A (en) * | 2004-02-26 | 2005-09-08 | Semiconductor Energy Lab Co Ltd | Film-formation method of semiconductor film |
| JP2012054613A (en) * | 2005-02-04 | 2012-03-15 | Asm America Inc | Selective deposition of silicon-containing film |
-
1992
- 1992-11-30 JP JP32003292A patent/JPH06168886A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005243951A (en) * | 2004-02-26 | 2005-09-08 | Semiconductor Energy Lab Co Ltd | Film-formation method of semiconductor film |
| JP2012054613A (en) * | 2005-02-04 | 2012-03-15 | Asm America Inc | Selective deposition of silicon-containing film |
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