JP2004087585A - Film-forming apparatus and film-forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film-forming apparatus and method capable of performing the MOCVD method without generating particles. <P>SOLUTION: In the film-forming apparatus consisting of a film-forming chamber 7, a mixing chamber 3 for generating mixing gas, vaporization chamber 1 for raw gas, and a gas head 8 formed on the upper surface of the film-forming chamber 7, particle traps are arranged between the vaporization chamber and the mixing chamber and on the downstream side in the mixing chamber and a by-pass line 10 provided with a valve is connected between the primary side and secondary side of particle traps 6a, 6b arranged on the downstream side in the mixing chamber. In the case of forming a film by using the apparatus, gas components such as raw gas, reactive gas and carrier gas are allowed to flow in the opened state of the valve of the by-pass line and then the valve is closed, or in the case of a variable valve, film formation is started while gradually closing the valve. <P>COPYRIGHT: (C)2004,JPO

Description

【００６０】
成膜室内の圧力を６Ｔｏｒｒに調圧した。この時の混合室の拡散室内の圧力は１３Ｔｏｒｒであり、原料ガスの気化部の圧力は２０Ｔｏｒｒであった。一般に液体原料の安定気化は３０Ｔｏｒｒ以下が望ましいため、十分にその要件を満足している。
まず、図６に示す半球型仕切り板６４を設けた混合室６１内に、上記原料ガス及び反応ガスを、それぞれ、ガス導入管６５及び６６を経てガス導入口６５ａ及び６６ａから混合室内へ導入して攪拌・混合・拡散し、混合室６１から成膜室内に成膜ガスを導入し、この成膜室内で、ＭＯＣＶＤ方法によって通常の条件で基板上にＰＺＴ薄膜を形成した。成膜室内に導入された成膜ガス中にはパーティクルは含まれていなかった。かくして形成された薄膜の膜厚分布を観察したところ、混合室内に仕切り板６４を設けたものを使用した場合は、基板上に形成された膜の厚さが均一であり、良好な膜質を有する膜を連続的に形成することができた。この時の膜厚分布は±１．２％程度であり、デバイス製作上の観点から半導体チップの歩留まりを上げるために必要な±３％以下を充分に満足した。この結果は、所定の仕切り板６４を設けたことにより、撹拌室６２及び拡散室６３での対流・撹拌・混合・拡散が効率よく行われ、原料ガスと反応ガスとが均一に混合され、均一な厚さを有する薄膜が形成されたことを示している。
【００６１】
上記パーティクルトラップを備えているが、上記仕切り板を有しない従来の混合室を用い、混合室内に上記と同じ原料ガス及び反応ガスを導入して混合・拡散し、ＭＯＣＶＤ方法によって薄膜を形成した。かくして形成された薄膜の膜厚分布を観察したところ、基板上に形成された膜の厚さの厚い部分は反応ガス導入口側に偏っており、薄い部分は原料ガス導入口側に偏っていた。また、混合室内の空間（仕切り板を設けた場合の撹拌室と拡散室とを合わした空間）において、その空間の底では、各導入口の位置に対する各ガス濃度の比較的濃い領域の反転現象が起こり、成膜ガス排出口からガスヘッドまでその反転現象を引きずったまま層流となり、基板へその濃度分布が転写されたものと推察される。この時の膜厚分布は±３．０％程度であった。
【００６２】
上記ＰＺＴの原料ガスとして、Ｚｒ（ｔｈｄ）_４／ＴＨＦの代わりにＺｒ（ｄｍｈｄ）_４／ＴＨＦを用いて、また、ＢＳＴの原料ガスと反応ガスとを用いて、上記方法を繰り返した。両者とも、形成された薄膜の膜質も膜厚分布も上記と同じ傾向が得られ、パーテイクルのない成膜ガスを用いて、効率よく均一な膜厚分布を有する薄膜を連続的に製造することができた。膜厚分布は±３％以下を充分に満足した。
【００６３】
（実施例４）
本実施例では、実施例１と同様に、図３に示す成膜装置を用い、強誘電体であるＰＺＴの原料ガスと反応ガスである酸素ガス（Ｏ_２）とを選択して、ＰＺＴ薄膜を形成せしめた。その際の成膜室として図８に示すものを用いた。なお、成膜室内の圧力は、圧力調整バルブで５Ｔｏｒｒに維持した。

【００６４】
得られた結果について、以下説明する。
図８における成膜室８１内壁面とスリーブ部材９３との間の間隙（排気口の大きさ）の寸法ｒ（排気クリアランスｒ：ｍｍ）とスリーブ部材の高さ寸法Ｌを変化させて、膜厚１００ｎｍのＰＺＴ膜を成膜したときの膜厚分布（％）を図１２に示す。図１３に、間隙ｒと高さ寸法Ｌを変化させてＰＺＴ膜を成膜したときの基板中央部の成膜レート（Ｒａｔｅ）（ｎｍ／ｍｉｎ）を示す。
【００６５】
ここで、膜厚分布を２％以内に維持するには、高さ寸法Ｌ７０ｍｍ以上の場合、間隙ｒを１０ｍｍ以上に設定する必要がある。量産性を考慮すれば、成膜時間は３ｍｉｎ以下が望ましいので、膜厚１００ｎｍの薄膜を成膜する場合、成膜レートが３５ｎｍ／ｍｉｎ以上でなければならない。従って、図１３から明らかなように、間隙の寸法ｒを１０ｍｍ以上、好ましくは１０ｍｍから１７ｍｍに、高さ寸法Ｌを７０ｍｍ以上に設定しておけば、良好な膜厚分布と量産に適した成膜レートとが得られる。
【００６６】
次に、上記条件より間隙ｒを１５ｍｍ、高さ寸法Ｌを７０ｍｍに設定して、ガスリング９４からプロセスに寄与しない不活性ガスＮ_２を成膜室８１内に導入して膜厚分布と成膜ダストとを測定した。図１４は、ガス（Ｇａｓ）ヘッド周り不活性ガスを０〜４０００ｓｃｃｍの流量の範囲で変化させて８インチの電極基板上にＰＺＴ膜を形成したときの膜厚分布と成膜ダスト（パーティクルＴｏｔａｌ）の関係を示す。図１４から明らかなように、ガスリング９４から１０００〜２０００ｓｃｃｍの範囲で不活性ガスを流した場合、パーティクル数が最も小さくなった。このため、不活性ガスを流さない場合に比べて優位性を有する。
【００６７】
図１５は、上記と同様に、間隙ｒを１５ｍｍ、高さ寸法Ｌを７０ｍｍに設定すると共に、ガスリング９４から不活性ガスＮ_２を０〜４０００ｓｃｃｍの流量の範囲で変化させて成膜室８１内に導入し、８インチの電極基板上にＰＺＴ膜の成膜したときの組成比（線ａ）と膜厚分布（線ｂ）とを示す。図１５によれば、不活性ガスの流量を変更しても膜厚分布に変化は見られないが、不活性ガス流量が２０００ｓｃｃｍの近傍で組成比が乱れる。なお、組成比は、Ｚｒ／（Ｚｒ＋Ｔｉ）の比を意味する。
【００６８】
図１２〜１５から明らかなように、図８に示す成膜装置では、間隙ｒが１０ｍｍ以上、好ましくは１０〜１７ｍｍ、スリーブ部材９３高さ寸法Ｌが７０ｍｍ以上、及びガスリング９４から成膜室８１に導入される不活性ガスの流量を１０００〜１５００ｓｃｃｍの範囲にすると、ガスリング９４からの不活性ガス自体が乱流、対流の発生源とはならず、その整流作用を最大限に発揮させることができる。その結果、膜厚分布（２％以下）、組成比、組成分布及び成膜レートが良好であって、安定し、その上、成膜ダストが少なく（０．２μｍ以上のパーティクルが２０個以下）、連続成膜を行い得る。
ＰＺＴ膜の代わりにＢＳＴ膜を形成する場合も、上記と同様の結果が得られる。
また、ステージ８２に昇降手段を付設しなくても防着板を配置することで、対流、乱流及び熱対流することなく等方排気するようにすれば混合ガスのガス流を均一にできる。
【００６９】
【発明の効果】
本発明によれば、パーティクルトラップを配設し、また、混合室内に配設されたパーティクルトラップの一次側と二次側との間にバイパスラインを設けることにより、成膜室内に導入される原料ガスその他のガス類、ひいては成膜ガス中にパーティクルがほとんど含まれなくなると共に、装置運転時の圧力変動によるパーティクルトラップからのパーティクルの巻き上げ、下流への流出を押さえることができ、その結果として、良好な膜質を有する薄膜を形成することができる成膜装置を提供できる。
【００７０】
また、上記装置を用いて成膜する場合、原料ガス等のガス類を、混合室内下流側に配設されたパーティクルトラップの一次側と二次側との間に設けられたバイパスラインのバルブを開いた状態で流した後、このバルブを閉じ、成膜を開始することにより、パーティクルトラップの一次側と二次側との間に一時的な大きな圧力差を生じさせること無く成膜を開始させることが可能となる。かくして、この方法により、装置運転時の圧力変動によるパーティクルトラップからのパーティクルの巻き上げ、下流への流出を押さえることができる。また、このバルブを可変バルブとし、初めバルブを開いた状態でガス類を流し、次いで、可変バルブを調節しながらガス類を流すことにより、パーティクルトラップの一次側と二次側との間に一時的な大きな圧力変動を生じさせること無く成膜を開始させることが可能となり、パーティクルの発生を更に減少させることができる。
【図面の簡単な説明】
【図１】パーティクルトラップを有する従来成膜装置の構成の概略を模式的に示す構成図。
【図２】図１の成膜装置を用いて行った１００枚連続成膜時のパーティクル挙動を示すグラフ。
【図３】本発明の成膜装置の構成の一例の概略を模式的に示す構成図。
【図４】本発明で用いる集塵式スクリーンの構成・配置の一例を模式的に示す図であり、（ａ）はその構成・配置の一例を模式的に示す断面図、（ｂ）はその構成・配置の別の例を模式的に示す断面図。
【図５】本発明で用いる板状の金属燒結フィルターの配置・構成の一例を模式的に示す断面図。
【図６】本発明の成膜装置で用いる混合室の一例を模式的に示す断面図。
【図７】図６に示す混合室の撹拌室の内部構成を模式的に示す図であり、（ａ）は断面図、（ｂ）は上面図。
【図８】本発明の成膜装置の別の構成の概略を模式的に示す構成図。
【図９】図８に示す装置において、成膜室内の混合ガスのガスの流れを説明する図であり、（ａ）はステージとガスヘッドとの間隔が広い場合、（ｂ）はステージとガスヘッドとの間隔が狭い場合についての成膜室断面図。
【図１０】実施例１で得られた１００枚連続成膜時のパーティクル挙動を示すグラフ。
【図１１】実施例２で得られた１００枚連続成膜時のパーティクル挙動を示すグラフ。
【図１２】図８に示す成膜室で間隙ｒ及び高さ寸法Ｌを変化させてＰＺＴ膜を形成したときの膜厚分布を示すグラフ。
【図１３】図８で示す成膜室で間隙ｒと高さ寸法Ｌを変化させてＰＺＴ膜を成膜したときの基板中央部の成膜レートを示すグラフ。
【図１４】図８に示す成膜室でガスリングを介して不活性ガスの流量を変化させて基板上にＰＺＴ膜を形成したときの膜厚分布と成膜ダストの関係を示すグラフ。
【図１５】図８に示す成膜室でガスリングからの不活性ガスの流量を変化させて成膜室内に導入し、基板上にＰＺＴ膜を形成したときの組成分布と膜厚分布とを示すグラフ。
【符号の説明】
１　気化室　　　　　　　　　　　　　２　集塵式スクリーン
３　混合室　　　　　　　　　　　　　４　原料ガス用配管
５　反応ガス用配管　　　　　　　　　６ａ、６ｂ　金属燒結フィルター
７　成膜室　　　　　　　　　　　　　８　ガスヘッド
９　基板　　　　　　　　　　　　　１０　バイパスライン
４２　スクリーン板　　　　　　　　　４５　フィルター
５０　成膜室　　　　　　　　　　　　５１　混合室
５１ａ　攪拌室　　　　　　　　　　　５１ｂ　拡散室
５２　原料ガス用配管　　　　　　　　５３　反応ガス用配管
５４　ガスヘッド　　　　　　　　　　５６　板状フィルター
６１　混合室　　　　　　　　　　　　６２　撹拌室
６３　拡散室　　　　　　　　　　　　６４　仕切り板
６５　原料ガス導入管　　　　　　　　６５ａ　原料ガス導入口
６６　反応ガス導入管　　　　　　　　６６ａ　反応ガス導入口
６７　ガス吹き出し口　　　　　　　　８０　成膜装置
８１　成膜室　　　　　　　　　　　　８１ａ　第一空間
８１ｂ　第二空間　　　　　　　　　　８２　ステージ
８６　ガスヘッド　　　　　　　　　　８７　混合室
８８　気化室　　　　　　　　　　　　９１　集塵式スクリーン　　　　　　　９２　金属燒結フィルター　　　　　　９３　スリーブ部材
９４　ガスリング　　　　　　　　　　９６　基板搬送口[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a film forming apparatus and a film forming method, and in particular, to a film forming apparatus for performing a CVD method such as a metal organic chemical vapor deposition (MOCVD) method, and to forming a metal oxide film using the apparatus. About the method.
[0002]
[Prior art]
In order to satisfy the recent demand for high integration of semiconductor devices, when forming a thin film by a CVD method such as the MOCVD method, the number of minute particles containing foreign matter fine particles and moisture contained in a raw material gas is reduced as much as possible. It is necessary. Conventionally, for example, in order to remove these particles to the ppt level, it has been proposed to introduce a raw material gas into a film forming chamber (reaction chamber) which is a vacuum chamber after passing through a filter member having high filtration characteristics. Have been.
In addition, the present inventors provide particle traps whose temperature can be controlled between the vaporizing chamber for raw material gas generation and the mixing chamber, and on the downstream side of the mixing chamber, respectively, so that the gas traps are generated in the vaporizing chamber and the piping. (Japanese Patent Application No. 2002-117123) has proposed a technique for preventing particles from flowing into a film formation chamber.
[0003]
[Problems to be solved by the invention]
When a thin film is formed by the MOCVD method, generally, a mixed gas (hereinafter, also referred to as a “deposition gas”) including a vaporized source gas and a reaction gas is introduced into a deposition chamber which is a vacuum chamber, and the mixed gas is introduced into the vacuum chamber. A film is formed by a gas phase chemical reaction on a substrate placed on a stage provided. A gas head such as a shower plate is provided on the upper surface of the film forming chamber so as to face the stage, and the gas head is provided with a gas mixing chamber. At the time of film formation, the raw material gas and the reaction gas supplied to the mixing chamber are introduced into a film formation chamber evacuated to a predetermined degree of vacuum through a gas head as a mixed gas having a predetermined mixing ratio, and A thin film is formed by the chemical reaction of
[0004]
In this case, in order to form a thin film having uniform film quality and film thickness distribution on the substrate, a uniform flow distribution, a uniform concentration distribution, and a uniform temperature distribution of the film forming gas in the film forming chamber or directly above the substrate are required. In addition to the necessity, the smaller the number of microparticles contained in the film forming gas, particularly the source gas, the better.
However, when a thin film is formed by the MOCVD method, even if the raw material gas is introduced into the reaction chamber after passing through the filter member as in the above-described prior art, particles are not completely removed only through the filter member. There is a problem that the life of the filter member at that time is short.
[0005]
Further, in the case of Japanese Patent Application No. 2002-117123, also in a film forming apparatus (FIG. 1) provided with a particle trap for preventing particles from flowing into the film forming chamber, the raw material is supplied to the film forming chamber 7 via the gas head 8. When a gas such as a gas, a reaction gas, and a carrier gas is started to flow, a large pressure difference ((pressure) between the primary side and the secondary side of the particle traps 6a and 6b disposed in the mixing chamber 3 is temporarily increased. (The pressure of the gauge P2) − (the pressure of the pressure gauge P3)), which causes the particles to be wound up from the particle trap in the mixing chamber 3 and to flow out downstream, and the initial stage of the production lot is started. An increase in the number of particles on the wafer (FIG. 2) was observed. In FIG. 1, reference numeral 1 denotes a vaporization chamber, 1a to 1d a raw material supply system, 2 a dust collecting screen, 3 a mixing chamber, 4 a raw gas pipe, 5 a reactive gas pipe, 6a and 6b particle traps. , A metal sintering filter, 7 a film forming chamber, 8 a gas head, 9 a substrate, 11 an exhaust gas treatment system, 12 a cold trap, 13 a vacuum pump such as a dry pump, 14 an exhaust system, and 15 a dry pump. And the like.
[0006]
In this film forming apparatus, at the start of film forming for each wafer, switching from the vent line of the source gas to the film forming chamber is performed by opening and closing a valve, and particles are generated at that time. This is thought to be due to temporary pressure fluctuations between the primary side and the secondary side of the particle trap, and a technical goal of reducing the total number of particles having a size of 0.2 μm or more to 50 or less. Is an obstacle to achieving
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a film forming apparatus capable of effectively performing a CVD method such as a MOCVD method without generating particles, and a method using the film forming apparatus. The purpose of the present invention is to provide an improved film forming method.
[0007]
[Means for Solving the Problems]
According to the film forming apparatus of claim 1, a film forming chamber which is a vacuum chamber provided with a stage on which a substrate is mounted, and a mixed gas of a source gas and a reaction gas connected to the film forming chamber In a film forming apparatus comprising a generation mixing chamber and a source gas vaporization chamber, and a gas head for introducing a mixed gas into the film formation chamber on the upper surface of the film formation chamber facing the stage, the vaporization chamber and A temperature-controllable particle trap is disposed between the mixing chamber and the downstream side of the mixing chamber, and a valve is provided between the primary side and the secondary side of the particle trap disposed downstream of the mixing chamber. And a bypass line provided with
According to claim 2, the valve is a variable valve.
[0008]
According to claim 3, in the film forming apparatus, when there are a plurality of particle traps disposed on the downstream side of the mixing chamber, the particle trap is located between the primary side and the secondary side of the particle trap closest to the film forming chamber. Alternatively, a bypass line provided with a valve connecting the secondary side of the particle trap closest to the film forming chamber and the primary side of the particle trap upstream is provided. In this case, it is not always necessary to provide a similar bypass line in the particle trap on the upstream side.
As described above, by providing the particle trap and providing the bypass line, the source gas and other gases introduced into the deposition chamber hardly contain particles, and the pressure fluctuation during the operation of the apparatus. Particles can be prevented from being wound up from the particle trap and flowing out downstream. Further, after the film formation, the residual gas can be simultaneously exhausted from the raw material pipe and the film formation chamber by evacuating the bypass line while the valve of the bypass line is closed. As a result, a film formation apparatus for forming a thin film having good film quality can be provided.
[0009]
According to the fourth aspect, in the film forming apparatus, the set temperature of the temperature-controllable particle trap provided between the vaporizing chamber and the mixing chamber is set to the vaporizing temperature and the raw material gas at the time of obtaining the raw material gas in the vaporizing chamber. Characterized in that the temperature is set to be lower by 5 to 80 ° C. than the temperature of the pipe through which the gas flows.
In this way, by setting the set temperature of the particle trap lower than the vaporization temperature or the pipe temperature, impurities or decomposed substances having a lower vapor pressure than the raw material compound, which may be mixed in the raw material or generated at the time of vaporization, are removed. can do. If the temperature is out of this range, it becomes difficult to remove impurities and decomposition products.
[0010]
According to claim 5, the particle trap disposed between the vaporizing chamber and the mixing chamber is composed of an inertial dust collecting screen, and the particle trap disposed downstream of the mixing chamber is composed of a porous filter. It is characterized by becoming. This porous filter is preferably a metal sintered filter.
According to the sixth aspect, the inertial dust collecting screen comprises a mesh-shaped dust collecting screen plate having a large number of through holes for introducing a gas at an inclination angle of about 45 degrees in the same direction. When the dust screen is formed by laminating a plurality of stitch-shaped dust collecting screen plates, it is required that the directions of the inclination angles of the through holes of the adjacent screen plates are alternately crossed by 90 degrees. Features.
[0011]
According to a seventh aspect of the present invention, the mesh-shaped dust collecting screen plate constituting the inertial dust collecting screen is characterized in that its space is filled with a filler selected from metal, ceramics and quartz.
By adopting the inertial dust collection screen and the porous filter as described above as a particle trap, it is possible to collect dry / wet particles with a small pressure loss, a large collection amount, and no clogging. Therefore, particles hardly exist in the source gas introduced into the mixing chamber, and eventually in the mixed gas introduced into the film formation chamber. Further, the life of a porous filter such as a metal sintered filter is extended.
[0012]
According to claim 8, in the film forming apparatus, in addition to disposing a particle trap and providing a bypass line, the mixing chamber includes a stirring chamber provided with a source gas introduction pipe and a reaction gas introduction pipe. A diffusion chamber for diffusing a mixed gas obtained by stirring and mixing the source gas and the reaction gas, and provided so that the respective gas inlets of the source gas introduction pipe and the reaction gas introduction pipe face each other. A partition plate is provided between the stirring chamber and the diffusion chamber so that the volume of the diffusion chamber is larger than the volume of the stirring chamber, and the partition plate has a convex shape with respect to the bottom of the mixing chamber. The partition plate is provided with one gas outlet at a predetermined position on the lower side in the vertical direction of a straight line connecting the respective gas inlets, and the gas outlet is provided with the gas outlet. Gas mixture is interrupted Characterized in that it is configured to be diffused into the diffusion chamber from the chamber.
[0013]
If the mixing chamber is used, the mixed gas obtained by stirring and mixing in the stirring chamber is diffused from one gas outlet provided at a predetermined position of the partition plate to the diffusion chamber, so that it is introduced. Even if the molecular weights of the gases differ greatly, a plurality of gases can be uniformly mixed without using a large-volume mixing chamber. Therefore, when mixing a plurality of gases having greatly different molecular weights, there is no need to change the volume of the mixing chamber depending on the flow rate and type. Therefore, the mixing chamber and the film forming chamber in the next step can be directly connected without waste, so that when the mixed gas is used in the next step, the uniformly mixed gas does not return to the turbulent flow again. Absent. Each gas introduced into the stirring chamber of the mixing chamber moves along the surface of the partition plate having a shape as described below, thereby causing convection. As a result, the mixed gas introduced into the stirring chamber is efficiently removed. It is possible to stir and mix uniformly and reliably. In addition, by adjusting the position and size of the gas outlet, each introduced gas can be stirred and mixed in an optimal state, and as a result, a uniform mixed gas can be introduced into the diffusion chamber. Will be possible.
[0014]
When the mixed gas stirred and mixed in the stirring chamber of the mixing chamber is introduced into the diffusion chamber, the gas is naturally diffused by a diffusion phenomenon caused by a difference in volume between the stirring chamber and the diffusion chamber. Since the mixed gas uniformly mixed from the diffusion chamber can be efficiently introduced into the film forming chamber, the mixed gas does not become turbulent. Therefore, in a mixing chamber whose volume is not affected by the flow rates and types of the source gas and the reaction gas, the gases are uniformly mixed at a low pressure, and the uniformly mixed gas is directly connected to the film forming chamber via a gas head. By introducing the mixed gas, turbulence of the mixed gas can be suppressed, and the film quality and the film thickness distribution of the thin film formed on the film formation target can be improved and stabilized.
[0015]
By making the partition plate have a quadratic curve shape convex to the bottom of the mixing chamber, only a partition plate having a predetermined curved surface shape is disposed in the mixing chamber, so that an extremely simple configuration is achieved. The desired mixing chamber is obtained. Further, with respect to the gas outlet, a pressure difference is provided between the stirring chamber and the diffusion chamber by appropriately setting the position and size of the gas outlet, thereby uniformly distributing different weight gases due to strong convection generated in the stirring chamber. The mixing is performed so that the mixed gas is diffused from the stirring chamber into a diffusion chamber having a wide space. For example, the partition plate is preferably provided at a position corresponding to a half of a vertical distance from a peripheral portion to a bottom portion thereof. Thereby, the uniformly mixed gas can be efficiently diffused from the stirring chamber to the diffusion chamber.
[0016]
According to the ninth aspect, in the film forming apparatus, in addition to providing a particle trap and providing a bypass line, the periphery of the stage is surrounded by a cylindrical sleeve member having a predetermined length. Exhaust gas is exhausted from the first space through a gap between the sleeve member and the wall surface of the film formation chamber without convection in the first space formed by the gas head and the stage. The height position of the stage is set at a position where the volume of the second space below the stage to which the exhaust means is connected is larger than the volume of the first space.
According to the tenth aspect, in the film forming apparatus according to the ninth aspect, a gas ring for uniformly introducing an inert gas into the film forming chamber along the inner wall surface of the film forming chamber is provided on the upper surface of the film forming chamber. It is characterized by having.
[0017]
It is preferable that the gap between the sleeve member and the wall surface of the film forming chamber is set to 10 mm or more (preferably, 10 to 17 mm), and the height of the sleeve member is set to 70 mm or more. By setting the gap and the height dimension in such ranges, the film thickness distribution can be maintained within a desired value.
According to the structure of the ninth and tenth aspects, the raw material gas introduced into the mixing chamber, and thus the mixed gas introduced into the film formation chamber hardly contains particles, and the mixed gas immediately above the substrate is not contained. A uniform flow distribution, a uniform concentration distribution, and a uniform temperature distribution can be achieved, and as a result, a thin film having uniform film quality and film thickness distribution can be formed on the substrate.
[0018]
A film forming method according to claim 11, which is a film forming method performed by using the film forming apparatus, wherein a gas such as a source gas, a reactive gas, and a carrier gas flows into a film forming chamber to form a film. After flowing the gases with the valve of the bypass line provided between the primary side and the secondary side of the particle trap disposed on the downstream side of the mixing chamber open, the valve is closed, and the film is formed. It is characterized by starting.
As described above, after the gases are flowed under predetermined conditions with the bypass line valve opened, by closing the valve, a temporary large pressure difference between the primary side and the secondary side of the particle trap is generated. It is possible to start the film formation without causing the problem. As a result, it is possible to prevent the particles from being wound up from the particle trap due to the pressure fluctuation during the operation of the apparatus and to flow downstream.
[0019]
The film forming method according to claim 12 is a film forming method performed by using the film forming apparatus, wherein a gas such as a source gas, a reaction gas, and a carrier gas is flowed into a film forming chamber to form a film. After flowing gases in a state where a variable valve of a bypass line provided between the primary side and the secondary side of the particle trap disposed downstream of the mixing chamber is opened, the variable valve is gradually opened. It is characterized in that the film formation is started while being closed.
As described above, the bypass line valve is a variable valve, and by flowing gases while adjusting the variable valve, a large temporary pressure fluctuation does not occur between the primary side and the secondary side of the particle trap. Film formation can be started. As a result, generation of particles can be further reduced.
[0020]
The film forming method according to claim 13 uses the film forming apparatus, and when a film is formed by flowing a gas such as a source gas, a reaction gas, and a carrier gas into a film forming chamber, and the film forming process is interrupted. With the valve of the bypass line provided between the primary side and the secondary side of the particle trap disposed downstream of the mixing chamber being opened, the gas other than the raw material gas is kept flowing. Then, a film is started by flowing a source gas when the film forming step is performed.
Accordingly, it is possible to start film formation without causing a large temporary pressure fluctuation between the primary side and the secondary side of the particle trap, and it is possible to further reduce the generation of particles.
In addition, the film forming method of the present invention can be used, for example, to smooth the surface morphology of a metal oxide thin film required for high integration of a semiconductor element, to improve the crystallinity, to make the film thin, and to be able to adhere to a fine three-dimensional structure. This is effective when trying to improve the quality, increase the area of the substrate, lower the film formation temperature, and the like.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a film forming apparatus according to the present invention will be described with reference to the drawings.
In the film forming apparatus of the present invention, for example, as shown in FIG. 3, the vaporizing chamber 1, the mesh-shaped dust collecting screen 2, and the mixing chamber 3 are kept at a predetermined temperature, for example, 180 to 260 ° C. One end of each of a raw gas pipe 4 and a reactive gas pipe 5 such as an oxygen gas is connected to the mixing chamber. The other end of the source gas pipe 4 is connected to the vaporization chamber 1, and the source gas obtained by vaporizing the organic metal diluted with the organic solvent can be introduced into the mixing chamber 3 through the dust collecting screen 2 which is a particle trap. It has become. The other end of the reaction gas pipe 5 is connected to a reaction gas cylinder and a carrier gas cylinder so that these gases can be introduced into the mixing chamber 3. The source gas pipe 4 and the reaction gas pipe 5 are preferably provided with a heating means such as a heater or a heat exchanger.
[0022]
The dust-collecting screen 2 may be provided between the vaporization chamber 1 and the mixing chamber 3 and may have a structure that functions as a particle trap capable of controlling the temperature for removing particles in the source gas. As the dust collecting screen, for example, Pyro Screen (registered trademark) manufactured by Nunobiki Seisakusho Co., Ltd. or the like can be used.
The arrangement and configuration of the dust collecting screen 2 are not particularly limited as long as they can collect particles. For example, it is a particle trap arranged and configured as shown in FIGS. 4A and 4B, and is configured such that a heating means H such as a heater can control the temperature independently of the piping.
[0023]
As shown in FIG. 4 (a), in the direction toward the outlet 41 for discharging from the inlet 40 for introducing the source gas from the vaporization chamber, that is, in the direction perpendicular to the flow direction of the source gas. A plurality of screen plates 42 are stacked in parallel. When the screen plate 42 is contaminated with the collected particles, it is preferable that the solvent 43 be flowed from above for cleaning and the solvent can be discharged (drain 44) from below for cleaning.
Further, as shown in FIG. 4B, a configuration may be adopted in which the raw material gas from the vaporization chamber is introduced from the lower inlet 40 and discharged from the upper outlet 41. In this case, a plurality of screen plates 42 are stacked in parallel to the direction perpendicular to the flow direction of the raw material gas. When the screen plate 42 is contaminated with the collected particles, it is preferable that the solvent 43 be flowed from above for cleaning and the solvent can be discharged (drain 44) from below for cleaning. Note that a filter 45 may be provided on the uppermost layer of the stacked screen plates and before the outlet 41.
[0024]
The material of the dust collecting screen is determined in consideration of the corrosion resistance to the raw material gas, mechanical properties, heat resistance (about 300 ° C.), and the like. For example, it may be selected from nickel and its alloys (for example, Hastelloy (registered trademark), Inconel (registered trademark), etc.), stainless steel (316, 316L, etc.), aluminum, titanium, ceramics, and the like.
On the downstream side in the mixing chamber 3 for mixing gases such as the introduced source gas and reaction gas, porous filters 6a and 6b (hereinafter, metal sintered filters) which can control the temperature as a particle trap will be described. ) Is provided so that the mixed gas can be further filtered and introduced into the film forming chamber 7. The introduction of the mixed gas into the film forming chamber 7 is performed via a gas head 8 such as a shower plate disposed on the upper surface of the film forming chamber directly connected to the mixing chamber 3.
[0025]
This metal sintering filter removes particles present in the mixed gas introduced toward the substrate 9 in the film forming chamber 7 in addition to removing particles from the raw material gas by the dust collecting screen 2. It is intended to form a thin film having excellent film quality. The metal sintering filter may be a filter made of a porous material such as ceramics, quartz, and fluorocarbon (resin) in addition to the metal sintering filter, depending on the operating temperature range and the type of gas used. In addition, the temperature of the metal sintered filter is controlled by external heating or heating of the filter support, and it is possible to set the temperature higher than the pipe temperature.
The number of the metal sintered filters may be one, or two or more as shown in FIG. In the case of a plurality of filters, a plurality of filters having different mesh sizes may be used directly or stacked with a spacer interposed therebetween.
[0026]
The metal sintered filter is mounted as follows. For example, in the mixing chamber shown in FIG. 5, a source gas pipe 52 from a vaporization chamber (not shown) and a reaction gas source are provided above a stirring chamber 51a of a mixing chamber 51 provided to be connected to a film forming chamber 50. The mixed gas obtained in the stirring chamber is diffused into the diffusion chamber 51b, and the mixed gas is diffused from the diffusion chamber 51b into the film forming chamber through the plate-shaped metal sintering filter 54 and the gas head 55. It is configured to be introduced. The metal sintering filter 54 is mounted on a support member 56 mounted by a fixing jig on the downstream side in the mixing chamber 51. Although not shown, the filter 54 may be heated by a heating means such as a heater. The filter shape may be a cylindrical shape other than the illustrated plate shape, or may be a pleated (wavy) shape to increase the filtration area of the filter. Further, a combination of a plurality of filters having different mesh sizes may be used.
[0027]
The material of the metal sintering filter is determined in consideration of corrosion resistance to a raw material gas and a reaction gas, mechanical characteristics, and heat resistance. For example, it may be selected from nickel and its alloys (for example, Hastelloy (registered trademark), Inconel (registered trademark) and the like), and thin metal wire sintered bodies such as stainless steel (316 and 316L). For example, a filter made of stainless steel fiber manufactured by Nippon Seisen Co., Ltd. can be used.
According to the present invention, by arranging the particle trap composed of the dust collecting screen and the metal sintering filter as described above, the pressure loss is small, the trapping amount is large, the clogging is not performed, and the dry / wet particles are removed. Since particles can be efficiently collected, particles are hardly present in the mixed gas introduced into the film formation chamber. Further, the life of the metal sintered filter is extended as compared with the case where only the filter is provided.
[0028]
Further, in the film forming apparatus, as shown in FIG. 3, a valve (V3) is provided between the primary side and the secondary side of the metal sintering filters 6a and 6b disposed on the downstream side in the mixing chamber 3. A provided bypass line 10 is provided. When a plurality of filters are provided, a bypass line having a valve may be provided between the primary side and the secondary side of the filter closest to the film forming chamber 7.
[0029]
As shown in FIG. 3, four kinds of raw material supply systems 1a, 1b, 1c and 1d are connected to the vaporization chamber 1, and the respective supply systems are controlled by adjusting valve elements (V20 to V27). Is sent from the raw material container through a flow controller (FMC7 to 10) by He gas or the like, and N ₂ It is configured to be transported to a vaporization chamber by gas or the like. The raw material gas obtained in the vaporization chamber 1 is conveyed to the mixing chamber 3 via the dust collecting screen 2 by the pipe 4. In the mixing chamber 3, a reaction gas (O ₂ ) And an inert gas such as a carrier gas (N ₂ ) Is connected, and each supply system mixes a reaction gas or a carrier gas from a gas cylinder through a flow controller (MFC1-4) and a heat exchanger by adjusting a valve element (V10-13). It is configured to be transported to the chamber 3 by the pipe 5. An exhaust gas treatment system 11 is connected to the film forming chamber 7 and the bypass line 10 between the vaporization chamber 1 and the dust collecting screen 2 via a cold trap 12 and a vacuum pump 13 such as a dry pump. An exhaust system 14 is connected to the film forming chamber 7 so that the degree of vacuum in the chamber can be adjusted, and a vacuum pump 15 such as a dry pump may be connected to the exhaust system. In FIG. 3, P1 to P6 indicate pressure gauges, V1 to V29 indicate valve elements, and MFC1 to MFC10 indicate flow controllers.
[0030]
Next, an embodiment of a mixing chamber that can be used in the film forming apparatus of the present invention will be described with reference to FIGS.
FIG. 6 is a cross-sectional view schematically illustrating the internal configuration of the mixing chamber, and FIG. 7A is a cross-sectional view schematically illustrating the internal configuration of the stirring chamber in the mixing chamber of FIG. 7) is a schematic top view of FIG. 6 and 7, the same components are denoted by the same reference numerals. In FIGS. 7A and 7B, solid lines and dotted lines, and alternate long and short dash lines indicate the tendency of the fluid analysis results by the computer simulation of the reaction gas flow and the raw material gas flow, respectively. FIG. 3 illustrates the gas flow and gas distribution.
[0031]
As shown in FIG. 6, the mixing chamber 61 has a hollow cylindrical shape of a predetermined size, and includes a stirring chamber 62, a diffusion chamber 63, and a partition plate 64 for separating between the stirring chamber and the diffusion chamber. It is directly connected to a film formation chamber (reaction chamber) for performing the next process using the obtained film formation gas. A source gas introduction pipe 65 for introducing at least one type of source gas and a reaction gas introduction pipe 66 are attached to an upper portion of the stirring chamber 62, and the gas introduction ports 65a and 66a are arranged so as to face each other. Have been. In order to efficiently introduce the film forming gas composed of the mixed source gas and the reaction gas from the stirring chamber 62 to the diffusion chamber 63, the partition plate 64 is provided below the straight line connecting the gas introduction ports 65a and 66a in the vertical direction. On the side, one gas outlet 67 having a predetermined size is provided at a position corresponding to about の of the vertical distance from the peripheral portion of the partition plate 64 to the bottom thereof.
[0032]
As shown in FIGS. 6, 7A and 7B, the raw material gas introduction pipe 65 and the reaction gas introduction pipe 66 are provided on the upper wall surface of the mixing chamber 61 at the center of the partition plate 64 (in a variable state). (In the vicinity of a curved point), and is mounted at a point-symmetric position with respect to the center point of the partition plate 64, and the gas introduction ports 65a and 66a are disposed so that the gas introduction directions thereof are opposed to each other as described above. You.
In the mixing chamber 61, the partition plate 64 is formed in a hemispherical shape having a concave partition surface having a quadratic curve shape, and serves as a mixing chamber to which the raw material gas introduction pipe 65 and the reaction gas introduction pipe 66 are attached. The peripheral edge is attached to the upper wall surface side without any gap.
[0033]
As described above, the inside of the mixing chamber 61 is partitioned into the stirring chamber 62 and the diffusion chamber 63 by the partition plate 64, so that the volume of the diffusion chamber is larger than the volume of the stirring chamber. In the case of the mixing chamber, the ratio between the volume of the stirring chamber 62 and the volume of the diffusion chamber 63 is not particularly limited. However, from the viewpoint of satisfactorily performing stirring / mixing and diffusion, it is usually 1: 5 to 1: 2. It is preferable to set the degree.
[0034]
In the mixing chamber configured as described above, in a state where the film forming chamber directly connected to the mixing chamber is evacuated, the raw material gas introduction pipe 65 and the reaction gas introduction pipe 66 are supplied through the gas introduction ports 65a and 66a, respectively. Then, at least one kind of source gas and reaction gas are introduced into the stirring chamber 62 of the mixing chamber 61. As a result, as shown in FIGS. 7A and 7B, the raw material gas flow is divided by the reaction gas flow in the stirring chamber 62, and both gases flow along the plate 64 on the surface of the partition plate 64. As a result, convection is generated, and the source gas and the reaction gas are stirred and mixed. Next, as shown in FIG. 6, the film forming gas composed of the mixed source gas and the reaction gas is smoothly introduced into the diffusion chamber 63 through the gas outlet 67 and diffused. As described above, since the volume of the diffusion chamber 63 is larger than the volume of the stirring chamber 62, when the film forming gas is introduced from the stirring chamber into the diffusion chamber, a diffusion phenomenon occurs due to a difference in the volume, and the uniformity of the film formation gas is increased. It is introduced as a mixed gas stream and diffused.
[0035]
The film formation apparatus provided with the mixing chamber has a film formation chamber connected to a vacuum evacuation system, and a wafer stage for supporting a substrate which is a film formation target is provided in the film formation chamber. ing. A gas head is provided on the upper surface of the film forming chamber, and the gas head is directly connected to a mixing chamber mounted on the upper part of the film forming chamber. The mixing chamber is connected to a source gas vaporization system via a dust collecting screen as a particle trap, and is also connected to a reaction gas source. The film-forming gas uniformly mixed as described above is disposed adjacent to the mixing chamber, introduced at the shortest distance to the directly connected gas head, and is placed on the wafer stage without being turbulent in the film-forming chamber. It is supplied to the surface of the placed film formation target.
[0036]
According to the mixing chamber, after the raw material gas and the reaction gas are stirred and mixed in the stirring chamber 62, the film forming gas obtained by stirring and mixing is diffused in the diffusion chamber 63. Even when the molecular weights of the gas and the reaction gas are significantly different, the raw material gas and the reaction gas can be uniformly mixed, and it is not necessary to use a mixing chamber having a large volume as in the conventional case. Therefore, the volume of the mixing chamber is not affected by the flow rate and type of the film forming gas, and the mixing chamber and the film forming chamber can be directly connected, so that the uniformly mixed film forming gas becomes turbulent again. It will not be.
[0037]
When the mixing chamber is used, the gas outlet 67 provided in the partition plate 64 is provided near the raw material gas introduction pipe 65 as shown in FIGS. 6, 7A and 7B. The film forming gas that violently convects at this portion is smoothly introduced into the diffusion chamber 63 through the gas outlet 67. Note that the gas outlet 67 provided in the partition plate 64 may be provided near the reaction gas introduction pipe 66. And, as described above, since the volume of the diffusion chamber 63 is larger than the volume of the stirring chamber 62, when the film forming gas is introduced from the stirring chamber into the diffusion chamber, a diffusion phenomenon occurs due to the difference in the volumes, Evenly mixed. The uniformly mixed film-forming gas is introduced into the gas head, which is disposed adjacent to and directly connected thereto, at the shortest distance, and is supplied to the substrate without turbulence in the film-forming chamber.
[0038]
According to the present invention, in the case of the mixing chamber 61, though not shown in FIG. 6, a metal sintering filter is provided downstream of the mixing chamber as shown in FIG. A bypass line having a valve, which may be a variable valve, is provided between the primary side and the secondary side of the filter.
Next, another embodiment of the film forming apparatus of the present invention will be described with reference to FIGS. 8, 9A and 9B.
[0039]
8, a film forming apparatus 80 has a cylindrical film forming chamber 81. A cylindrical stage 82 on which a substrate such as a silicon wafer is placed is provided inside the film forming chamber. The stage incorporates a heating means (not shown) for heating the substrate. Further, there is provided means for configuring the stage 82 so as to be able to move up and down between a film formation position of the film formation chamber 81 and a substrate transfer position below the film formation chamber.
Two evacuation ports 83 are provided below the film forming chamber 81, and evacuation means 84 composed of a vacuum pump such as a turbo-molecular pump or a rotary pump is connected to the evacuation ports via an evacuation pipe 85. Have been. A gas head 86 is provided in the center of the upper part of the film forming chamber 81 so as to face the stage 82.
[0040]
A mixing chamber 87 is provided on the upstream side of the gas head 86. The mixing chamber 87 has a source gas pipe 89 having one end connected to the vaporization chamber 88 and another end for a reaction gas connected to a gas source. The other ends of the pipes 90 are respectively connected. In the film forming apparatus shown in FIG. 8, a dust collecting screen 91 which is a dust collecting screen shown in FIG. 4 is provided between the mixing chamber 87 and the vaporizing chamber 88, and the metal sintering shown in FIG. A metal sintered filter 92 as a filter is provided downstream of the mixing chamber 87 and near the gas head 86. With such a configuration, the raw material gas and the reaction gas are supplied to the mixing chamber 87 at a controlled flow rate by a mass flow controller (not shown), and are uniformly mixed at a predetermined mixing ratio in the mixing chamber 87. Is removed from the gas head 86 toward the center of the substrate. That is, the raw material gas is introduced from the vaporizing chamber 88 through the dust collecting screen 91 to the mixing chamber 87, and the mixed gas passes through the metal sintering filter 92, and from the mixing chamber 87 via the gas head 86 to the film forming chamber. It is introduced into 81.
[0041]
According to the present invention, although not shown in FIG. 8 in the case of the mixing chamber 87, as shown in FIG. A bypass line having a valve which may be a variable valve is provided between the bypass line and the next side.
By the way, when a thin film is formed on a substrate by the MOCVD method, when the raw material gas falls below the vaporization temperature, the raw material gas is deposited as particles and causes film deposition dust in the film formation chamber 81. For this reason, a heat exchanger (not shown) as a temperature adjusting means may be provided in the source gas pipe 89. Further, in order to prevent deposition of the source gas, a heating means such as a heater may be provided on the outer wall of the film forming chamber 81 or on the stage 82.
[0042]
Here, in order to make the film thickness distribution and composition distribution of the thin film on the substrate uniform and to improve the reproducibility in the MOCVD process, exhaust gas containing a mixed gas or the like which does not contribute to the process is isotropically exhausted from the periphery of the substrate. Therefore, it is important to make the gas flow from the gas head 86 to the evacuation means 84 uniform. Therefore, it is particularly necessary to prevent convection and turbulence from occurring in the first space 81a below the gas head 86 and above the stage 82.
Therefore, the periphery of the stage 82 is surrounded by a sleeve member 93 having a predetermined height L. In this case, the volume of the second space 81b below the stage is reduced to the first space so that exhaust gas is isotropically exhausted through an annular gap (r) formed by the sleeve member 93 and the inner wall surface of the film forming chamber 81. Set it larger than 81a. The exhaust pipe 85 may be provided with a pressure regulating valve 85a so that the pressure condition can be changed according to the MOCVD process.
[0043]
As described above, when the heating means is incorporated in the stage 82 to heat the substrate to a predetermined temperature, heat convection may occur above the substrate. Therefore, a gas ring 94 for uniformly introducing an inert gas into the film forming chamber 81 along the inner wall surface of the film forming chamber 81 is provided above the film forming chamber 81 so as to surround the gas head 86. The exhaust gas exhausted to the second space 81b through the gap between the sleeve member 93 and the inner wall surface of the film forming chamber 81 by the forced rectifying action of the inert gas injected from the gas ring 94 is transferred to the sleeve 81. It is possible to more reliably perform isotropic exhaust from around the member 93. Thereby, turbulence, convection and thermal convection in the first space can be prevented. The volume of the first space at the film forming position of the stage 82 can be set to, for example, 2.8 L, and the volume of the second space can be set to 13 L.
[0044]
By the way, as shown in FIG. 9A, when the distance from the gas head 86 to the stage 82 is long, exhaust gas is not exhausted and the height position of the stage 82 in the film forming chamber 81 is higher than the film forming chamber 81. Convection C may be generated at the corners of. On the other hand, as shown in FIG. 9B, when the distance from the gas head 86 to the stage 82 is short, the mixed gas ejected from the gas head 86 is reflected by the substrate, and the upper corner of the film forming chamber 81 is formed. Then, convection C may be generated. For this reason, the distance between the gas head 86 and the stage 82 at the film forming position is set to such a distance that the convection C hardly occurs.
[0045]
In addition, if the substrate transfer port for transferring the substrate to the stage 82 is provided at a position facing the first space 81a, turbulence may occur around the substrate transfer port. For this reason, an elevating means (not shown) is attached to the stage so that the stage can be moved up and down between the film forming position on the upper side of the film forming chamber 81 and the substrate transfer position on the lower side. Then, a substrate transfer port 96 (FIG. 8) is provided in the film forming chamber 81 corresponding to the substrate transfer position.
In the case of the film forming apparatus shown in FIG. 8, a gas pipe 95 leading to the gas ring 94 is provided so that the temperature of the inert gas ejected from the gas ring 94 can be adjusted so that the source gas does not precipitate as particles in the MOCVD method. A heat exchanger 95a serving as a temperature adjusting means may be provided.
[0046]
As described above, the film forming apparatus of the present invention is provided with a particle trap and a bypass line, and preferably includes a mixing chamber in which a partition plate having a specific shape is provided. When the film-forming gas obtained by stirring and mixing is introduced into the diffusion chamber, it is naturally diffused by a diffusion phenomenon caused by a difference in volume between the stirring chamber and the diffusion chamber. Further, preferably, a sleeve member and a gas ring are provided. Therefore, with these film forming apparatuses, a thin film having good film quality can be formed with a very simple configuration. That is, since a film-forming gas having no particles and being uniformly mixed can be directly introduced into the film-forming chamber, the film-forming gas does not become turbulent, and the quality and the quality of the formed thin film are reduced. The thickness distribution can be improved and stabilized.
[0047]
In the present invention, various changes can be made without being limited to the above embodiment. For example, in the above description, a hemispherical partition plate was used for the partition plate, but the curvature, shape (for example, columnar shape, cubic shape, and conical shape), size, and the like of the partition plate depend on the type of gas used. It is possible to change the design appropriately according to the process. Also, the position and shape of the gas outlet provided in the partition plate may be appropriately determined according to the process, as long as the raw material gas and the reaction gas are stirred and mixed so as to be uniformly introduced into the diffusion chamber. The design can be changed. As described above, if the gas outlet is provided near the portion where the gas in the stirring chamber violently convects, the film forming gas can be smoothly introduced into the diffusion chamber. For example, if a gas outlet is provided within a range of 45 degrees or less in the vertical direction from the center of a straight line connecting the inlet of the raw material gas and the inlet of the reaction gas, both gases are uniformly mixed, It can be smoothly introduced into the diffusion chamber.
[0048]
In the above embodiment, the partition plate is provided so as not to form a gap with respect to the gas introduction side wall surface of the mixing chamber. However, as long as the film forming gas is sufficiently stirred and mixed, the partition plate is mixed with the peripheral edge of the partition plate. It is also possible to provide a gap between the chamber and the gas introduction side wall.
In the above embodiment, the mixing chamber provided with one stirring chamber and one diffusion chamber has been described as an example. However, two or more stirring chambers and diffusion chambers are provided to mix the film forming gas. It is also possible.
Further, depending on the degree of the mixing state, it is also possible to cause the reaction by introducing a film forming gas directly from the stirring chamber into the film forming chamber without providing the diffusion chamber.
[0049]
The above-described mixing chamber has a special effect when a raw material that is liquid at normal temperature is used in the MOCVD method. This is because raw materials that are liquid at room temperature are heavy even if they are vaporized.
With the above-described film forming apparatus, an electrode film is formed using Pt, Ir, Ru, or the like as a raw material source, and a barrier film made of a nitride film or an oxide film is formed using a raw material such as Ti, Ta, Al, or the like. Can be formed. Further, in order to further improve the film characteristics of the formed thin film, La (thd) is used as an additive (raw material source). ₃ , Sr (thd) ₃ , Ca (thd) ₂ , Al (thd) ₃ Etc. may be used.
[0050]
【Example】
Hereinafter, examples and comparative examples of a method of forming a metal oxide thin film by the MOCVD method using the film forming apparatus of the present invention will be described with reference to the drawings.
(Example 1)
In this example, a metal oxide thin film was continuously formed using the film forming apparatus shown in FIG. 3 under the following conditions. That is, a bypass line 10 is provided between the primary side and the secondary side of the particle traps 6a and 6b provided to prevent the particles from flowing into the film formation chamber 7, and the film formation is performed using this apparatus. When starting to flow gases such as raw material gas, reaction gas and carrier gas into the chamber, the gases are flowed under predetermined conditions with the valve V3 of the bypass line open, and then the valve is closed to thereby obtain a particle trap. Film formation was started without causing a large temporary pressure fluctuation between the primary side and the secondary side of 6a and 6b, and the film was continuously formed.
[0051]
Equipment conditions:
Evaporation chamber temperature: 250 ° C
Particle trap 2:
Dust collecting screen: 5 screen plates
Set temperature: 230 ° C
Particle trap 6a:
Sintered stainless steel fiber filter (absolute filtration diameter 1μm)
Set temperature: 240 ° C
Particle trap 6b:
Sintered stainless steel fiber filter (absolute filtration diameter 0.3μm)
Set temperature: 240 ° C
[0052]
Film formation conditions for 100 runs:
Substrate temperature: 600 ° C
Film formation pressure: 1000 Pa
material:
Pb (thd) ₂ / Cyclohexane: 0.36 ml / min (thd is 2,2,6,6-tetramethylhexanedionato, C ₁₁ H ₁₉ O ₂ It is. )
Zr (dmhd) ₄ / Cyclohexane: 0.20 ml / min (dmhd is 2,6-dimethylheptadionate, C ₇ H _Thirteen O ₂ It is. )
Ti (iso-PrO) ₂ (Thd) ₂ / Cyclohexane: 0.22 ml / min
Reaction gas flow rate
O ₂ : 1500sccm
Film formation time: 330 sec
[0053]
As a result, a metal oxide thin film having a thickness of 100 nm, a composition of Pb / (Zr + Ti) = 1.15, and a Zr / (Zr + Ti) = 0.40 was formed. Since the film formation was started without causing a large temporary pressure fluctuation between the primary side and the secondary side of the particle traps 6a and 6b, the particles were wound up from the particle traps, and the particles were moved downstream from the traps. No outflow of particles occurred, and as a result, as shown in FIG. 10, the total number of particles having a particle size of 0.2 μm or more during continuous operation could be reduced to 50 or less.
Further, in the obtained thin film, the surface morphology was smooth, the crystallinity was good, and the throwing power to the fine three-dimensional structure was good.
[0054]
(Example 2)
In the present embodiment, as shown in FIG. 3, a variable valve is used as the valve V3 of the bypass line 10 installed between the primary side and the secondary side of the particle traps 6a and 6b. When starting to flow gases such as a reaction gas and a carrier gas, the gases are allowed to flow under a predetermined condition with the valve opened, and then the variable valves are gradually closed, so that the primary of the particle traps 6a and 6b is reduced. The film formation was started without causing a large temporary pressure fluctuation between the side and the secondary side, and the film was continuously formed.
[0055]
Equipment conditions:
Evaporation chamber temperature: 220 ° C
Particle trap 2:
Dust collecting screen: 5 screen plates (filling material: felt-like stainless steel fiber)
Set temperature: 230 ° C
Particle trap 6a:
Sintered stainless steel fiber filter (absolute filtration diameter 1μm)
Set temperature: 240 ° C
Particle trap 6b:
Sintered stainless steel fiber filter (absolute filtration diameter 0.3μm)
Set temperature: 240 ° C
[0056]
Film formation conditions for 100 runs:
Substrate temperature: 600 ° C
Film formation pressure: 1000 Pa
material
Pb (thd) ₂ / Cyclohexane: 0.36 ml / min
Zr (dmhd) ₄ / Cyclohexane: 0.20 ml / min
Ti (iso-PrO) ₂ (Thd) ₂ / Cyclohexane: 0.22 ml / min
Reaction gas flow rate
O ₂ : 1500sccm
Film formation time: 330 sec
[0057]
As a result, a metal oxide thin film having a thickness of 100 nm, a composition of Pb / (Zr + Ti) = 1.15, and a Zr / (Zr + Ti) = 0.40 was formed. Since the film formation was started without a large temporary pressure fluctuation between the primary side and the secondary side of the particle traps 6a and 6b, the particles were wound up from the particle traps or moved downstream from the traps. As a result, the total number of particles having a particle size of 0.2 μm or more during continuous operation could be reduced to 30 or less, as shown in FIG.
Further, in the obtained thin film, the surface morphology was smooth, the crystallinity was good, and the throwing power to the fine three-dimensional structure was good.
[0058]
(Comparative Example 1)
Using a conventional film forming apparatus without a bypass line shown in FIG. 1, a metal oxide thin film was continuously formed under the same apparatus conditions and film forming conditions as in Example 1 or 2.
As a result, a metal oxide thin film having a thickness of 100 nm, composition: Pb / (Zr + Ti) = 1.15, and Zr / (Zr + Ti) = 0.40 was formed. However, since a large pressure difference is temporarily generated between the primary side and the secondary side of the particle traps 6a and 6b, the particles are wound up from the particle trap and the particles flow out from the trap to the downstream side. As a result, as shown in FIG. 2, an increase in particles in the intended wafer of the production lot was observed, and the total number of particles having a particle size of 0.2 μm or more could not be reduced to 50 or less. The surface morphology of the obtained thin film was not smooth.
[0059]
(Example 3)
In this embodiment, similarly to the first embodiment, the film forming apparatus shown in FIG. 3 is used, and a raw material gas of PZT as a ferroelectric and an oxygen gas (O ₂ ) To form a PZT thin film. The one shown in FIG. 6 was used as the mixing chamber at that time.

[0060]
The pressure in the film forming chamber was adjusted to 6 Torr. At this time, the pressure in the diffusion chamber of the mixing chamber was 13 Torr, and the pressure in the vaporization section of the source gas was 20 Torr. In general, stable vaporization of a liquid raw material is desirably 30 Torr or less, so that the requirement is sufficiently satisfied.
First, the raw material gas and the reaction gas are introduced into the mixing chamber from the gas introduction ports 65a and 66a via the gas introduction pipes 65 and 66, respectively, in the mixing chamber 61 provided with the hemispherical partition plate 64 shown in FIG. The mixture was stirred, mixed, and diffused, and a film-forming gas was introduced from the mixing chamber 61 into the film-forming chamber. In this film-forming chamber, a PZT thin film was formed on the substrate by MOCVD under ordinary conditions. No particles were contained in the film formation gas introduced into the film formation chamber. Observation of the film thickness distribution of the thin film thus formed showed that when a film provided with a partition plate 64 in the mixing chamber was used, the film formed on the substrate had a uniform thickness and had good film quality. The film could be formed continuously. At this time, the film thickness distribution was about ± 1.2%, which sufficiently satisfied ± 3% or less necessary for increasing the yield of semiconductor chips from the viewpoint of device fabrication. The result is that the convection, stirring, mixing, and diffusion in the stirring chamber 62 and the diffusion chamber 63 are efficiently performed by providing the predetermined partition plate 64, and the raw material gas and the reaction gas are uniformly mixed, This indicates that a thin film having an appropriate thickness was formed.
[0061]
Using a conventional mixing chamber provided with the particle trap but without the partition plate, the same source gas and reaction gas as described above were introduced into the mixing chamber, mixed and diffused, and a thin film was formed by the MOCVD method. Observing the film thickness distribution of the thin film thus formed, the thick portion of the film formed on the substrate was biased toward the reaction gas inlet, and the thin portion was biased toward the source gas inlet. . In addition, in the space in the mixing chamber (the space where the stirring chamber and the diffusion chamber are combined when a partition plate is provided), at the bottom of the space, the reversal phenomenon of the region where each gas concentration is relatively high with respect to the position of each inlet port. It is presumed that laminar flow occurs while the reversal phenomenon is dragged from the film forming gas outlet to the gas head, and the concentration distribution is transferred to the substrate. At this time, the film thickness distribution was about ± 3.0%.
[0062]
Zr (thd) is used as the source gas for PZT. ₄ / Zr (dmhd) instead of THF ₄ The above method was repeated using / THF and a BST source gas and a reaction gas. In both cases, the same tendency is obtained in both the film quality and the film thickness distribution of the formed thin film, and it is possible to efficiently produce a thin film having a uniform film thickness distribution efficiently using a film-forming gas without particles. did it. The film thickness distribution sufficiently satisfied ± 3% or less.
[0063]
(Example 4)
In this embodiment, similarly to the first embodiment, the film forming apparatus shown in FIG. 3 is used, and a raw material gas of PZT as a ferroelectric and an oxygen gas (O ₂ ) To form a PZT thin film. The one shown in FIG. 8 was used as a film forming chamber at that time. The pressure in the film forming chamber was maintained at 5 Torr by a pressure adjusting valve.

[0064]
The obtained result will be described below.
By changing the dimension r (exhaust clearance r: mm) of the gap (size of the exhaust port) between the inner wall surface of the film forming chamber 81 and the sleeve member 93 in FIG. 8 and the height dimension L of the sleeve member, the film thickness is changed. FIG. 12 shows the film thickness distribution (%) when a 100 nm PZT film was formed. FIG. 13 shows the film formation rate (Rate) (nm / min) at the center of the substrate when the PZT film is formed with the gap r and the height L changed.
[0065]
Here, in order to maintain the film thickness distribution within 2%, when the height L is 70 mm or more, the gap r needs to be set to 10 mm or more. In consideration of mass productivity, the deposition time is desirably 3 minutes or less. Therefore, when depositing a thin film having a thickness of 100 nm, the deposition rate must be 35 nm / min or more. Therefore, as is apparent from FIG. 13, if the dimension r of the gap is set to 10 mm or more, preferably from 10 mm to 17 mm, and the height L is set to 70 mm or more, a good film thickness distribution and a composition suitable for mass production can be obtained. The film rate is obtained.
[0066]
Next, under the above conditions, the gap r is set to 15 mm and the height L is set to 70 mm. ₂ Was introduced into the film forming chamber 81, and the film thickness distribution and the film forming dust were measured. FIG. 14 shows a film thickness distribution and film dust (particle Total) when a PZT film is formed on an 8-inch electrode substrate by changing an inert gas around a gas (Gas) head in a flow rate range of 0 to 4000 sccm. Shows the relationship. As is clear from FIG. 14, when the inert gas was flowed from the gas ring 94 in the range of 1000 to 2000 sccm, the number of particles became the smallest. For this reason, it is superior to the case where no inert gas is flowed.
[0067]
FIG. 15 shows that the gap r is set to 15 mm, the height L is set to 70 mm, and the inert gas N ₂ Is changed in the flow rate range of 0 to 4000 sccm and introduced into the film forming chamber 81, and the composition ratio (line a) and the film thickness distribution (line b) when the PZT film is formed on the 8-inch electrode substrate. And According to FIG. 15, although the film thickness distribution does not change even when the flow rate of the inert gas is changed, the composition ratio is disturbed when the flow rate of the inert gas is around 2000 sccm. The composition ratio means the ratio of Zr / (Zr + Ti).
[0068]
As apparent from FIGS. 12 to 15, in the film forming apparatus shown in FIG. 8, the gap r is 10 mm or more, preferably 10 to 17 mm, the height L of the sleeve member 93 is 70 mm or more, and When the flow rate of the inert gas introduced into the gas supply 81 is in the range of 1000 to 1500 sccm, the inert gas itself from the gas ring 94 does not become a source of turbulence and convection, and maximizes its rectifying action. be able to. As a result, the film thickness distribution (2% or less), the composition ratio, the composition distribution, and the film forming rate are good and stable, and the film forming dust is small (20 or less particles of 0.2 μm or more). And a continuous film formation.
When a BST film is formed instead of the PZT film, the same result as described above is obtained.
In addition, even if the stage 82 is not provided with the elevating means, the gas flow of the mixed gas can be made uniform by arranging the anti-adhesion plate to perform isotropic exhaust without convection, turbulence and thermal convection.
[0069]
【The invention's effect】
According to the present invention, by providing a particle trap, and by providing a bypass line between the primary side and the secondary side of the particle trap disposed in the mixing chamber, the raw material introduced into the film formation chamber Gas and other gases, and eventually the film forming gas, contain almost no particles, and can suppress the lifting of particles from the particle trap due to pressure fluctuations during the operation of the apparatus and the outflow to the downstream. A film forming apparatus capable of forming a thin film having an excellent film quality can be provided.
[0070]
In the case of forming a film using the above-described apparatus, gases such as source gas are supplied to a bypass line valve provided between a primary side and a secondary side of a particle trap disposed downstream of the mixing chamber. After flowing in an open state, the valve is closed and the film formation is started, thereby starting the film formation without causing a temporary large pressure difference between the primary side and the secondary side of the particle trap. It becomes possible. Thus, by this method, it is possible to prevent the particles from being wound up from the particle trap due to the pressure fluctuation during the operation of the apparatus and flowing out downstream. In addition, this valve is a variable valve, and gas is flowed with the valve first opened, and then gas is flowed while adjusting the variable valve, so that the particle trap is temporarily moved between the primary side and the secondary side. It is possible to start film formation without causing significant pressure fluctuation, and it is possible to further reduce the generation of particles.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing the outline of the configuration of a conventional film forming apparatus having a particle trap.
FIG. 2 is a graph showing particle behavior when 100 films are continuously formed by using the film forming apparatus of FIG.
FIG. 3 is a configuration diagram schematically showing an example of a configuration of a film forming apparatus of the present invention.
4A and 4B are diagrams schematically illustrating an example of the configuration and arrangement of a dust collecting screen used in the present invention, wherein FIG. 4A is a cross-sectional view schematically illustrating an example of the configuration and arrangement, and FIG. Sectional drawing which shows another example of a structure and arrangement | positioning typically.
FIG. 5 is a cross-sectional view schematically showing an example of the arrangement and configuration of a plate-shaped sintered metal filter used in the present invention.
FIG. 6 is a cross-sectional view schematically illustrating an example of a mixing chamber used in the film forming apparatus of the present invention.
7A and 7B are diagrams schematically showing an internal configuration of a stirring chamber of the mixing chamber shown in FIG. 6, wherein FIG. 7A is a cross-sectional view and FIG.
FIG. 8 is a configuration diagram schematically showing the outline of another configuration of the film forming apparatus of the present invention.
9A and 9B are diagrams illustrating a flow of a mixed gas in a film forming chamber in the apparatus shown in FIG. 8, wherein FIG. 9A shows a case where a space between a stage and a gas head is wide, and FIG. FIG. 3 is a cross-sectional view of a film forming chamber when a distance from a head is small.
FIG. 10 is a graph showing particle behavior at the time of continuous film formation of 100 sheets obtained in Example 1.
FIG. 11 is a graph showing particle behavior during continuous film formation of 100 sheets obtained in Example 2.
12 is a graph showing a film thickness distribution when a PZT film is formed by changing a gap r and a height L in the film forming chamber shown in FIG.
FIG. 13 is a graph showing a film formation rate at the center of the substrate when a PZT film is formed in the film formation chamber shown in FIG. 8 while changing the gap r and the height L.
14 is a graph showing a relationship between a film thickness distribution and film forming dust when a PZT film is formed on a substrate by changing a flow rate of an inert gas via a gas ring in the film forming chamber shown in FIG.
FIG. 15 shows a composition distribution and a film thickness distribution when a PZT film is formed on a substrate by changing the flow rate of an inert gas from a gas ring in the film formation chamber shown in FIG. Graph shown.
[Explanation of symbols]
1 vaporization chamber 2 dust collection screen
3 mixing chamber 4 source gas piping
5 Reaction gas piping 6a, 6b Metal sintered filter
7 Deposition chamber 8 Gas head
9 Substrate 10 Bypass line
42 Screen board 45 Filter
50 Deposition chamber 51 Mixing chamber
51a Stirring chamber 51b Diffusion chamber
52 Piping for source gas 53 Piping for reaction gas
54 gas head 56 plate filter
61 Mixing room 62 Stirring room
63 Diffusion chamber 64 Partition plate
65 Source gas inlet pipe 65a Source gas inlet
66 Reaction gas inlet pipe 66a Reaction gas inlet
67 Gas outlet 80 Deposition equipment
81 Deposition chamber 81a First space
81b Second space 82 Stage
86 gas head 87 mixing chamber
88 Vaporization chamber 91 Dust collection screen 92 Metal sintering filter 93 Sleeve member
94 Gas ring 96 Substrate transfer port

Claims (13)

A film forming chamber which is a vacuum chamber having a stage on which a substrate is mounted, a mixing chamber connected to the film forming chamber for generating a mixed gas of a source gas and a reaction gas, and a vaporizing chamber for the source gas A film head provided with a gas head for introducing a mixed gas into the film formation chamber on the upper surface of the film formation chamber opposite to the stage; and between the vaporization chamber and the mixture chamber. A temperature-controllable particle trap is disposed on each of the downstream sides of the mixing chamber, and a bypass having a valve is provided between the primary side and the secondary side of the particle trap disposed on the downstream side of the mixing chamber. A film forming apparatus comprising a line. 2. The film forming apparatus according to claim 1, wherein said valve is a variable valve. 3. The film forming apparatus according to claim 1, wherein when the number of the particle traps disposed on the downstream side in the mixing chamber is plural, the primary side and the secondary side of the particle trap closest to the film forming chamber are disposed. Or a bypass line provided with a valve connecting between the secondary side of the particle trap closest to the film formation chamber and the primary side of the particle trap located upstream. apparatus. The film forming apparatus according to any one of claims 1 to 3, wherein a set temperature of a temperature-controllable particle trap provided between the vaporization chamber and the mixing chamber is set to a value corresponding to a temperature at which a source gas is obtained in the vaporization chamber. A film formation apparatus characterized in that the temperature is set to be lower by 5 to 80 ° C. than the vaporization temperature and the temperature of the pipe through which the raw material gas flows. 5. The film forming apparatus according to claim 1, wherein the particle trap disposed between the vaporization chamber and the mixing chamber comprises an inertial dust-collecting screen, and is provided downstream of the mixing chamber. A film forming apparatus, wherein the disposed particle trap comprises a porous filter. 6. The film-forming apparatus according to claim 5, wherein the inertial dust-collecting screen comprises a mesh-like dust-collecting screen plate in which a large number of through-holes for introducing gas at an inclination angle of about 45 degrees are perforated in the same direction. When the dust collecting screen is formed by stacking a plurality of the dust collecting screen plates, the directions of the inclination angles of the through holes of the adjacent screen plates are alternately crossed by 90 degrees. A film forming apparatus characterized by the above-mentioned. 7. The film forming apparatus according to claim 5, wherein the dust collecting screen plate constituting the inertial dust collecting screen has a space filled with a filler selected from metal, ceramics and quartz. Film forming apparatus. The film forming apparatus according to claim 1, wherein the mixing chamber is obtained by stirring and mixing the raw material gas and the reaction gas with a stirring chamber provided with a raw material gas introduction pipe and a reaction gas introduction pipe. A diffusion chamber for diffusing the mixed gas, wherein the gas inlets of the source gas introduction pipe and the reaction gas introduction pipe are provided so as to face each other. In between, a partition plate is provided such that the volume of the diffusion chamber is larger than the volume of the stirring chamber, and the partition plate has a quadratic curve shape convex to the bottom of the mixing chamber. The partition plate is provided with one gas outlet at a predetermined position on the lower side in the vertical direction of a straight line connecting the respective gas inlets, and the mixed gas is stirred through the gas outlet. Is configured to be diffused from the chamber to the diffusion chamber Film-forming apparatus according to claim. The film forming apparatus according to any one of claims 1 to 7, wherein a periphery of the stage is surrounded by a cylindrical sleeve member having a predetermined length, and a gap is provided between the sleeve member and a wall surface of the film forming chamber. The exhaust gas is exhausted from the first space without convection in the first space formed by the gas head and the stage, and the second space below the stage to which vacuum exhaust means is connected. Wherein the height of the stage is set at a position where the volume of the stage becomes larger than the volume of the first space. 10. The film forming apparatus according to claim 9, wherein a gas ring for uniformly introducing an inert gas into the film forming chamber along an inner wall surface of the film forming chamber is provided on an upper surface of the film forming chamber. . A film forming method performed by using the film forming apparatus according to claim 1, wherein a source gas, a reactive gas, and a carrier gas are flowed into the film forming chamber to form a film. After flowing the gases with the valve of the bypass line provided between the primary side and the secondary side of the particle trap disposed on the downstream side of the mixing chamber being opened, the valve is closed to form a film. A film formation method characterized by starting the following. A film forming method performed by using the film forming apparatus according to claim 1, wherein a source gas, a reactive gas, and a carrier gas are flowed into the film forming chamber to form a film. After flowing the gases while the variable valve of the bypass line provided between the primary side and the secondary side of the particle trap disposed downstream of the mixing chamber is opened, the variable valve is A film formation method characterized by starting film formation while gradually closing. A film forming method performed by using the film forming apparatus according to claim 1, wherein a source gas, a reactive gas, and a carrier gas are flowed into the film forming chamber to form a film. When the film forming process is suspended, the valve of the bypass line provided between the primary side and the secondary side of the particle trap disposed on the downstream side of the mixing chamber is opened, and other than the source gas, A film forming method characterized by keeping a gas flowing state, and then starting film formation by flowing the source gas when performing a film forming step.

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