JP4663110B2 - Processing equipment - Google Patents

Description

【００３５】
まず、チャンバー１の側壁に設けられた図示しないゲートバルブを開いて搬送アームによりチャンバー１内にウエハＷを搬入し、リフトピン１６を載置台５から所定長さ突出するまで上昇させてウエハＷを受け取った後、搬送アームをチャンバー１から退出させ、ゲートバルブを閉じる。
【００３６】
この状態で、ガス供給機構６０およびパージガス供給装置５９からガスを供給せずに排気装置５８の排気バルブを全開にしてチャンバー内を急速に減圧し、チャンバー１内の圧力を到達圧力１００ｍＴｏｒｒの高真空状態とした後、リフトピン１６およびクランプリング７を下降させ、リフトピン１６を載置台５に没入させてウエハＷを載置台５上に載置するとともに、クランプリング７をウエハＷに当接して保持する位置まで下降させる（ＳＴＥＰ１）。このようにチャンバー内を高真空状態としてウエハＷの載置およびクランプリング７による保持を行うのは、ウエハＷが載置台５上で滑ることを防止するためである。また、加熱室２５内のランプ２６を点灯し、回転台２７を回転モータ２９により回転させながら熱線を放射させ、ウエハＷを所定の温度に加熱する。
【００３７】
次に、載置台５上に載置され、クランプリング７により保持されたウエハＷの表面にニュークリエーション膜を形成するため、排気装置５８の排気バルブの開度を下げるとともに、ガス供給機構６０のＮ_２ガス供給源６２、Ａｒガス供給源６４、ＳｉＨ_４ガス供給源６５およびＨ_２ガス供給源６６、ならびに、パージガス供給装置５９からそれぞれ所定の流量で処理ガスまたはパージガスの供給を開始し、処理空間１０内の圧力を５００Ｐａとする（ＳＴＥＰ２）。次いで、各ガスの流量を維持したままで、ＷＦ_６ガス供給源６３から分岐ライン７０を介して、高精度のマスフローコントローラー８４により厳密に流量を制御しつつ、後述する本成膜工程よりも少量のＷＦ_６ガスの供給を開始し（ＳＴＥＰ３）、この状態で下記式（１）に示すＳｉＨ_４還元反応を所定時間進行させ、ウエハＷ表面にニュークリエーション膜を形成する（ＳＴＥＰ４）。なお、前記ＳＴＥＰ３および前記ＳＴＥＰ４において、処理空間１０内の圧力は５００Ｐａを維持するようにする。
２ＷＦ_６＋３ＳｉＨ_４→２Ｗ＋３ＳｉＦ_４＋６Ｈ_２ ……… （１）
【００３８】
その後、ＷＦ_６ガスおよびＳｉＨ_４ガスの供給を停止し、その他のガスの供給量を維持した状態で、排気装置５８の排気バルブを全開にして処理空間１０内を急速に減圧し、ニュークリエーション膜を形成した後に残留した処理ガスを処理空間１０から一掃する（ＳＴＥＰ５）。
【００３９】
次に、以上のようにしてニュークリエーション膜の形成されたウエハＷの表面に、Ｗ成膜する本成膜工程を行う。まず、排気装置５８の排気バルブの開度を下げるとともに、キャリアガスとしてのＡｒガス、Ｈ_２ガス、Ｎ_２ガスおよびパージガスの流量をそれぞれ増大させ、処理空間１０内の圧力を１０６６６Ｐａに上昇させる（ＳＴＥＰ６）。次いで、ガス供給機構６０のＷＦ_６ガス供給源６３からメインデポ用のＷＦ_６ガスの供給を開始するとともに、Ａｒガス、Ｈ_２ガス、Ｎ_２ガスを減少させ、処理空間１０内をメインデポのための処理ガス雰囲気とし（ＳＴＥＰ７）、この状態で下記式（２）に示すＨ_２還元反応のＷ成膜を所定時間行う（ＳＴＥＰ８）。なお、前記ＳＴＥＰ７および前記ＳＴＥＰ８において、パージガスの流量および処理空間１０内の圧力は前記ＳＴＥＰ７と同様に維持するようにする。
ＷＦ_６＋３Ｈ_２→Ｗ＋６ＨＦ ……… （２）
【００４０】
本成膜を終了後、ウエハＷ取り出しに向けて、ＷＦ_６ガスおよびＳｉＨ_４ガスの供給を停止し、Ａｒガス、Ｈ_２ガス、Ｎ_２ガスおよびパージガスの供給を維持した状態で、排気装置５８の排気バルブを全開にしてチャンバー１内を急速に減圧し、本成膜終了後に残留した処理ガスを処理空間１０から一掃し（ＳＴＥＰ９）、その後全てのガスの供給を停止した状態で減圧を続けてチャンバー１内を高真空度状態とする（ＳＴＥＰ１０）。
【００４１】
この高真空度状態でリフトピン１６およびクランプリング７を上昇させ、クランプリング７によるウエハＷの保持を解除するとともに、リフトピン１６を載置台５から所定長さ突出させてウエハＷを搬送アームが受け取り可能な位置まで上昇させる。このようにチャンバー内を高真空状態としてウエハＷの保持を解除し、リフトピン１６で持ち上げるのは、ＳＴＥＰ１と同様にウエハＷが載置台５上で滑ることを防止するためである。
【００４２】
その後、パージガス、Ａｒガス等をチャンバー１内に導入し、ゲートバルブを開いてチャンバー１内に搬送アームを進入させ、リフトピン１６上のウエハＷを搬送アームで受け取り、搬送アームをチャンバー１から退出させることによりウエハＷを取り出して成膜動作を終了する。また、ウエハＷを取り出した後には、必要に応じてＣｌＦ_３ガスをチャンバー１内に供給する等してチャンバー１内のクリーニングを行う。
【００４３】
このようなプロセスでは、特に、上記ＳＴＥＰ５、上記ＳＴＥＰ９および上記ＳＴＥＰ１０において、排気装置５８のバルブを全開にして急速に減圧するため、処理空間１０および排気空間４６の圧力が急激に低下する。従来の装置ではこのような場合にバックサイド空間２３と処理空間１０との間に大きな圧力差が生じてクランプリング７のバタツキが発生していたが、本実施形態においては、この圧力差がクランプリング７のバタツキを発生させる大きさに達する前に、ガス放出機構３０がバックサイド空間２３からパージガスを排気空間４６に放出するので、クランプリング７のバタツキ等の不具合は生じない。また、ガス放出機構３０は、成膜時にパージガスが処理空間１０に流出することにより通常生じる圧力損失では動作しないので、上記ＳＴＥＰ２〜ＳＴＥＰ４のニュークリエーション工程、および、上記ＳＴＥＰ６〜ＳＴＥＰ８の本成膜工程においてパージガスは放出されず、処理ガスのウエハＷ周縁部および裏面への侵入はパージガスにより十分に防止される。
【００４４】
また、従来の装置では、装置が誤動作したり故障した場合には、処理空間１０および排気空間４６内の圧力がバックサイド空間２３の圧力よりも極めて大きくなって、その圧力差によりＣＶＤ成膜装置１００を構成する部材が破損するおそれがあったが、本実施形態においてはガス導入機構４０が排気空間４６の雰囲気をバックサイド空間２３に導入することにより圧力差を緩和することができるので、このような圧力差に起因した部材の破損を防止することができる。
【００４５】
次に、上記ガス放出機構３０におけるバルブ３５の設計例について説明する。
ここでは代表的な実機のデータに基づいてバルブ３５を構成した場合について示す。
クランプリング７は、クランプリング７の自重と、クランプリング７と３本のリフトピン１６それぞれとを連結する３本のスプリングの力とにより、載置台５上のウエハＷを保持している。実機におけるクランプリング７の自重は０．９Ｎ、前記スプリングの力は計１５Ｎ、クランプリング７の面積Ａ＝０．０１８５ｍ^２であり、クランプリング７は０．９Ｎ＋１５Ｎ＝１５．９ＮでウエハＷを押さえている。したがって、処理空間１０とバックサイド空間２３との圧力差により、この１５．９Ｎよりも大きい力がクランプリング７の上方向に作用するとクランプリング７が持ち上げられてバタツキはじめるものと考えられる。このことから、この実機でクランプリング７がバタツキはじめる処理空間１０とバックサイド空間２３との圧力差の大きさΔＰ_１は、ΔＰ_１＝１５．９／０．０１８５＝８５９．５Ｐａと求めることができる。
【００４６】
また、実機のデータからは、成膜時にパージガスがバックサイド空間２３から処理空間１０に流出することにより生じる圧力損失ΔＰ_２は、ΔＰ_２≒１１３Ｐａと算出された。したがって、排気空間４６とバックサイド空間２３との圧力差がΔＰ_２以下の場合にパージガスが放出されると、成膜時にパージガスを十分に流すことができなくなる。
【００４７】
以上より、この実機ではバルブ３５が動作する圧力差Ｐを、ΔＰ_１＜Ｐ＜ΔＰ_２、すなわち１１３Ｐａ＜Ｐ＜８５９．５Ｐａとすることが好ましく、これにより成膜時にはパージガスによりウエハＷの周縁部および裏面側への処理ガスの侵入を効果的に防止しつつ、急速減圧時にクランプリング７に生じるバタツキを防止することができることが求められた。
【００４８】
この好ましい範囲の圧力差Ｐで動作するように、バルブ３５を構成した。ここでは、ガス放出機構３０の設置スペースの関係から弁体３１ａの外径は１４ｍｍとし、肉厚は１．５ｍｍとした。このように構成された弁体３１ａが動作する圧力差は１枚あたり１４３Ｐａと算出されたので、３枚の弁体３１ａを１つのバルブ３５に用いることにより、バルブ３５の動作する圧力を上記の好ましい範囲内の４２９Ｐａとすることができる。弁体３１ａは肉厚４．５ｍｍのものを１枚用いてもよいが、ここでは調整を容易にするために１．５ｍｍの弁体３１ａを３枚用いることとした。このように構成したバルブ３５をガス放出機構３０に用いることにより、成膜時にはパージガスによりバックサイド空間２３への処理ガスの侵入を防止しつつ、処理空間１０を減圧する際には前記バックサイド空間２３からパージガスを適切に放出してクランプリング７のバタツキを防止することができた。なお、ここでは実機の代表的なデータに基づいて構成されたバルブ３５の設計例を示したものであり、バルブ３５の動作する圧力差の好ましい範囲、および、バルブ３５の構成はこれらに限られるものではない。
【００４９】
なお、本発明は上記実施形態に限定されることなく種々変形可能である。例えば、上記実施形態ではガス放出機構３０およびガス導入機構４０は、いずれもシールドベース３の内側に突出するように設けたが、図８に示すガス放出機構３０′のようにシールドベース３の外側に突出するように設けてもよい。この場合には、図９に示すガス放出機構３０″のように横向きにバルブ３５′を設けてもよい。ただし、横向きにした場合にはバルブ３５′は自重により放出孔３３′を密閉することはできないので、バネ等によりバルブ３５′を放出孔３３′に押し当てて密閉する構成とする必要がある。また、上記ではガス放出機構３０およびガス導入機構４０は、いずれも放出孔３３，４３とバルブ３５，４５との組み合わせを３組有する構成としたが、これに限られるものではない。さらに、ガス放出機構３０およびガス導入機構４０の数、配置についても変更可能である。
【００５０】
また、上記実施形態では本発明をＷのＣＶＤ成膜について示したが、これに限らず、他の材料、例えばＡｌ、ＷＳｉ、Ｔｉ、ＴｉＮ等のＣＶＤ成膜に適用することができるし、また、ＣＶＤ以外の他のガス処理にも適用することができる。また、被処理基板はウエハに限られるものではなく、他の基板であってもよい。
【００５１】
【発明の効果】
以上説明したように、本発明によれば、前記空間の圧力が処理容器内における前記空間の外側の圧力よりも所定値以上高くなった場合に、前記パージガスを前記空間から放出するガス放出機構を具備することにより、前記被処理基板を処理する際には前記パージガスにより前記空間への処理ガスの侵入を防止しつつ、前記処理容器内を減圧する際には前記ガス放出機構により前記パージガスを前記空間から放出することができ、前記処理容器内における前記空間内外に大きな圧力差が生じないので、前記基板保持部材のバタツキ等の不都合が防止される。これにより成膜行程の後等に前記処理空間を急速に減圧することができるようになり、プロセス時間を短縮してスループットを向上することが実現可能となる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係るＣＶＤ成膜装置を模式的に示す断面図であって、ウエハＷを載置台上に載置している状態を示す図面。
【図２】図１に示したＣＶＤ成膜装置において、ウエハＷをリフトピン上に支持している状態を示す図面。
【図３】図１に示したＣＶＤ成膜装置のクランプリング近傍におけるパージガスの流れを説明するための拡大図。
【図４】ガス放出機構およびガス導入機構の縦断面図。
【図５】図１に示したＣＶＤ成膜装置のＡ−Ａ部分断面図
【図６】ガス放出機構がパージガスを放出している状態の拡大断面図。
【図７】ガス導入機構が排気空間から雰囲気を導入している状態の拡大断面図。
【図８】ガス放出機構の変形例を示す図面。
【図９】ガス放出機構の他の変形例を示す図面。
【図１０】従来のＣＶＤ成膜装置を概略的に示す断面図。
【符号の説明】
１；チャンバー
２；蓋体
３；シールドベース
４；アタッチメント
５；載置台
６；バッフルプレート
７；クランプリング
１０；処理空間
１６；リフトピン
１７；リフレクタ
２０；支持部材
２３；バックサイド空間
２５；加熱室
３０；ガス放出機構
３１ａ；弁体
３１ｂ；軸部
３２；バルブボディー
３３；放出孔
３５；バルブ
３７；パージガス導入経路
４０；ガス導入機構
４１ａ；弁体
４１ｂ；軸部
４２；バルブボディー
４３；放出孔
４５；バルブ
４６；排気空間
５０；シャワーヘッド
５８；排気装置
５９；パージガス供給装置
６０；ガス供給機構
１００；ＣＶＤ成膜装置
Ｗ；半導体ウエハ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a processing apparatus for processing a substrate to be processed using a processing gas.
[0002]
[Prior art]
In a semiconductor manufacturing process, W (tungsten) or WSi (tungsten silicide) is used to form a wiring pattern on a semiconductor wafer (hereinafter simply referred to as a wafer) as an object to be processed or to fill a hole between wirings. , Ti (titanium), TiN (titanium nitride), TiSi (titanium silicide) or the like is deposited to form a thin film.
[0003]
Among these, the blanket W film is a processing gas such as WF. ₆ (Tungsten hexafluoride) and SiH ₄ (Silane) or SiH ₂ Cl ₂ It is formed by a CVD film forming method using (dichlorosilane) or the like.
[0004]
FIG. 10 shows an example of a CVD film forming apparatus for forming the W film. This CVD film forming apparatus is mainly provided with a chamber 101, a mounting table 102 provided in the chamber 101, and a processing space formed on the surface side of the wafer mounted on the mounting table 102. Shower head 104 for supplying a processing gas to 103, a heat ray irradiation mechanism 105 provided below the mounting table 102 for irradiating and heating a wafer mounted on the mounting table 102, and the wafer on the mounting table And a clamp ring 106 which is pressed and held. In such an apparatus, the wafer is mounted on the mounting table 102, and the wafer is heated by the heat ray irradiation mechanism 105 while the wafer is held on the mounting table 102 by the clamp ring 106. The above-described processing gas is supplied from the shower head 104 to the space 103 to perform a W film formation process. At this time, as indicated by an arrow in the figure, by supplying a purge gas from the back side of the wafer, the processing gas enters from between the clamp ring 106 and the wafer and the like, and the film is formed on the periphery and back side of the wafer. It is preventing.
[0005]
[Problems to be solved by the invention]
However, in the above-described CVD film forming apparatus, if the pressure in the processing space 103 is rapidly reduced after the film forming process or the like in order to shorten the process time and improve the throughput, the pressure in the processing space 103 and the supply from the back side of the wafer are supplied. The pressure difference with the purge gas to be rapidly increased, and this pressure difference causes a strong flow of the purge gas from between the wafer and the clamp ring 106 toward the processing space 103, and the members such as the clamp ring 106 are fluctuated. There is. As described above, when the members such as the clamp ring 106 are fluttered, there is a possibility that the particles or the members are damaged. Further, in the above CVD film forming apparatus, the processing space 103 cannot be rapidly depressurized, and it has to be depressurized step by step, resulting in a problem of poor throughput.
[0006]
The present invention has been made in view of such circumstances, can sufficiently prevent the processing gas from entering the back side of the substrate to be processed, and is less likely to cause inconvenience when the processing space is rapidly decompressed. An object is to provide a processing apparatus.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, according to a first aspect of the present invention, a processing container for processing a substrate to be processed using a processing gas, and the processing substrate disposed in the processing container are mounted. A mounting table, a processing gas supply means for supplying a processing gas to the surface side of the substrate to be processed in the processing container, and an annular shape that holds the periphery of the substrate to be processed from above and holds it on the mounting table. A substrate holding member; purge gas supply means for supplying purge gas to a space formed on the back side of the substrate to be processed; and a purge gas flow path defined by the substrate holding member for guiding the purge gas from the space to the upper side thereof. A gas discharge mechanism for discharging the purge gas from the space when the pressure in the space becomes higher than a pressure outside the space in the processing container by a predetermined value or more. The gas release mechanism releases the purge gas before the pressure difference inside and outside the space in the processing container reaches a value where the substrate holding member is lifted by the purge gas flowing through the purge gas flow path. A processing apparatus is provided.
[0008]
Further, according to the second aspect of the present invention, a processing container that performs processing on a processing substrate using a processing gas, a mounting table that is disposed in the processing container and on which the processing substrate is mounted, A processing gas supply means for supplying a processing gas to a first space formed on the surface side of the substrate to be processed, an annular substrate holding member that holds the periphery of the substrate to be processed from above, and the processing target Purge gas supply means for supplying a purge gas to a second space formed on the back side of the substrate, and a purge gas flow path for guiding the purge gas from the second space to the first space, defined by the substrate holding member Exhaust means for exhausting the first space through a third space formed below the first space and outside the second space, and the pressure in the second space is the first space. Higher than the pressure in space 1 When Tsu, and a gas release mechanism for releasing the purge gas into said third space The gas release mechanism releases the purge gas before the pressure difference between the second space and the first space reaches a value at which the substrate holding member is lifted by the purge gas flowing through the purge gas flow path. A processing apparatus is provided.
[0009]
In the present invention, when the pressure in the space becomes higher than the pressure outside the space in the processing container by a predetermined value or more, the gas discharge mechanism for discharging the purge gas from the space is provided. The purge gas can be discharged from the space by the gas release mechanism when the inside of the processing container is decompressed while the purge gas prevents the processing gas from entering the space when processing the processing substrate. Since a large pressure difference does not occur inside and outside the space in the processing container, inconveniences such as fluttering of the substrate holding member can be prevented.
[0010]
The processing apparatus according to the first and second aspects further includes a support member that holds the outer peripheral side of the substrate holding member, and the purge gas flow path passes between the substrate holding member and the substrate to be processed. It is preferable to have a first flow path and a second flow path that passes between the substrate holding member and the support member. This makes it possible to reliably prevent the processing gas from entering the peripheral edge and the back surface of the substrate to be processed during film formation.
[0011]
In the processing apparatus of the first aspect, the gas release mechanism opens the discharge hole when the pressure in the space becomes higher than a pressure outside the space in the processing container by a predetermined value or more. It is possible to adopt a configuration having a valve to perform.
[0012]
In the processing apparatus according to the second aspect, the gas release mechanism is provided so as to communicate with the third space and the second space, the discharge hole for discharging the purge gas, and the second And a valve that opens the discharge hole when the pressure in the space becomes higher than the pressure in the third space by the predetermined value or more. Since the third space is depressurized in preference to the first space, the pressure in the second space becomes higher than the pressure in the first space by a predetermined value or more during depressurization. Is reliably prevented.
[0013]
In these cases, the gas release mechanism causes the pressure difference between the inside and outside of the space in the processing container or the pressure difference between the second space and the third space to flow through the purge gas flow path. Preferably, the purge gas is released before reaching a value at which the substrate holding member is lifted by the purge gas. Accordingly, the purge gas can be surely released during the pressure reduction immediately before the substrate holding member is lifted and starts to flutter.
[0014]
Further, the gas release mechanism is configured such that when a pressure difference between the inside and outside of the space in the processing container or a pressure difference between the second space and the third space is processed on the substrate to be processed. It is preferable that the purge gas is released after exceeding a pressure loss caused by the purge gas flowing out of the space or the second space. This can prevent the purge gas from being released from the space or the second space when processing the substrate to be processed.
[0015]
In the processing apparatus according to the first and second aspects, the atmosphere outside the space in the processing container when the pressure outside the space in the processing container is higher than the pressure in the space by a predetermined value or more. Is introduced into the space, or when the pressure in the third space is higher than the pressure in the second space by a predetermined value or more, the atmosphere in the third space is changed to the second space. A gas introduction mechanism to be introduced may be further provided. As a result, it is possible to prevent a member of the processing apparatus from being damaged due to an abnormally high pressure difference generated in the processing container due to a malfunction or failure of the processing apparatus.
[0016]
In this case, the gas introduction mechanism includes an introduction hole for introducing an atmosphere outside the space in the processing container into the space, and the pressure in the space in the processing container is higher than the predetermined pressure in the space. A valve that opens the introduction hole when the value is larger than the value, or the introduction hole that introduces the atmosphere of the third space into the second space, and the pressure of the third space is The valve may be configured to open the introduction hole when the pressure in the second space is greater than the predetermined value.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.
1 and 2 are sectional views schematically showing a CVD film forming apparatus according to an embodiment of the present invention. FIG. 1 shows a semiconductor wafer W (hereinafter simply referred to as a wafer W) which is a substrate to be processed. FIG. 2 shows a state where the wafer W is supported on the lift pins. This CVD film forming apparatus forms a W film.
[0018]
As shown in FIGS. 1 and 2, the CVD film forming apparatus 100 has a chamber 1 formed in a cylindrical shape with, for example, aluminum, and a lid 2 is provided thereon. In the chamber 1, a covered cylindrical shield base 3 having an opening in the ceiling is erected from the bottom of the chamber 1. An annular attachment 4 is disposed in an opening provided in the ceiling portion of the shield base 3, and a mounting table 5 on which the wafer W is placed is supported by the attachment 4. A gap 11 is provided between the attachment 4 and the mounting table 5, and a clamp ring 7 to be described later is provided above the gap 11. The attachment 4 also functions as a support member that holds the outer peripheral side of the clamp ring 7. A baffle plate 6 having a large number of holes is provided between the top wall of the shield base 3 and the inner wall of the chamber 1. A processing space (first space) 10 to which a processing gas is supplied from a shower head 50 to be described later is provided on the surface side of the wafer W mounted on the mounting table 5 in the chamber 1 configured as described above. Is formed. A backside space (second space) 23 surrounded by the shield base 3, the attachment 4, and the mounting table 5 is formed below the processing space 10, and the chamber 1 and the shield are formed outside the backside space 23. An exhaust space (third space) 46 surrounded by the base 3 and the baffle plate 6 is formed.
[0019]
Below the mounting table 5 in the backside space 23, for example, three lift pins 16 (two of which are shown in FIG. 1) for lifting the wafer W from the mounting table 5 are provided. The push-up bar 18 is supported via the holding member 22, and the push-up bar 18 is connected to the actuator 19. The lift pins 16 are made of a material that transmits heat rays, for example, quartz.
[0020]
Further, a support member 20 is provided integrally with the lift pin 16, and this support member 20 passes through the hole 12 of the attachment 4 and is attached to an annular clamp ring 7 provided above the mounting table 5. It is connected via a spring (not shown). The clamp ring 7 is provided with a taper on the inner peripheral portion of the lower surface so that the thickness thereof becomes thinner toward the inner peripheral direction. The inner periphery of the clamp ring 7 is moved to the outer periphery of the surface of the wafer W by being lowered onto the wafer W. The wafer W abuts and is held down on the mounting table 5 by pressing the wafer W downward by its own weight and spring force.
[0021]
With such a configuration, the lift pin 16 and the clamp ring 7 are moved up and down integrally by the actuator 19 moving the push-up rod 18 up and down. When delivering the wafer W, the lift pins 16 and the clamp ring 7 rise until the lift pins 16 protrude from the mounting table 5 by a predetermined length (see FIG. 2), and the wafer W supported on the lift pins 16 is mounted on the mounting table. When placing on the wafer 5, the lift pins 16 are immersed in the placing table 5 and lowered to a position where the clamp ring 7 contacts and holds the wafer W (see FIG. 1).
[0022]
A transmission window 24 made of a heat ray transmission material such as quartz is airtightly provided at the bottom of the chamber 1 immediately below the mounting table 5, and a box-shaped heating chamber 25 is provided below the transmission window 24 so as to surround the transmission window 24. Is provided. In this heating chamber 25, a lamp 26 is attached to a rotary table 27 that also serves as a reflecting mirror, and this rotary table 27 is driven by a rotary motor 29 provided at the bottom of the heating chamber 25 via a rotary shaft 28. It is designed to be rotated. Therefore, the heat rays emitted from the lamp 26 can pass through the transmission window 24 and irradiate the lower surface of the mounting table 5 to heat it. A cylindrical reflector 17 is provided above the transmission window 24 along the outer periphery of the transmission window 24 so that the heat rays from the lamp 26 are efficiently guided to the mounting table 5.
[0023]
The transmission window 24 and the reflector 17 are provided in the backside space 23 surrounded by the shield ring 3 described above. In addition, a purge gas introduction path 37 having one end connected to the purge gas supply device 59 and the other end communicating with the backside space 23 is provided at the base of the reflector 17. Through this purge gas introduction path 37, in a predetermined film forming process, a purge gas made of an inert gas such as Ar or nitrogen gas that does not react with the processing gas is supplied from the purge gas supply device 59 to the backside space 23. . At this time, the purge gas supplied to the backside space 23 has a gap 11 provided between the mounting table 5 and the attachment 4 as shown by arrows in FIG. 1 and FIG. 3 in which the vicinity of the clamp ring 7 is enlarged, and The flow from the hole 12 of the attachment 4 toward the lower surface of the clamp ring 7, the flow flowing out to the processing space 10 via the first flow path 15 formed between the clamp ring 7 and the attachment 4, and the clamp ring 7 And a flow flowing out into the processing space 10 via the second flow path 14 formed between the wafers W. By forming such a flow of the purge gas, it is possible to prevent the processing gas from flowing into the peripheral portion and the back surface of the wafer W and the back side space 23 and exerting an excessive film forming action.
[0024]
A gas release mechanism 30 and a gas introduction mechanism 40 are provided inside the side wall of the shield base 3. FIG. 4A is a longitudinal sectional view of the gas release mechanism 30, and FIG. 4B is a longitudinal sectional view of the gas introduction mechanism 40.
[0025]
The gas release mechanism 30 includes an opening 34 provided on the side wall of the shield base 3, a valve body 32 that forms a chamber communicating with the exhaust space 46 through the opening 34, and the valve body 32. There are provided discharge holes 33 provided at three places on the bottom surface, and a valve body 31a having a diameter larger than the discharge hole 33 and a shaft portion 31b, and a valve 35 inserted through each discharge hole 33. . As shown in FIGS. 1 and 2, the valve 35 normally seals the discharge hole 33 by the valve body 31 a by its own weight, and prevents the processing gas from entering the backside space 23. . However, when the pressure of the exhaust space 46 decompressed together with the processing space 10 becomes lower than the pressure of the backside space 23 when the processing space 10 is decompressed via the exhaust space 46 by the exhaust device 58 described later, the pressure difference As a result, the valve body 31a receives an upward force, and when the pressure difference exceeds a predetermined value, the valve 35 is lifted to open the discharge hole 33, and the purge gas in the backside space 23 as shown in FIG. Is discharged into the exhaust space 46. Thus, in the type of valve 35 that operates based on the balance between the force received by the pressure difference and its own weight, the magnitude of the pressure difference that operates can be controlled by adjusting the own weight and area of the valve body 31a.
[0026]
At this time, it is preferable that the valve 35 is operated before the pressure difference between the processing space 10 and the backside space 23 reaches a value that lifts the clamp ring 7. As a result, when the processing space 10 is rapidly decompressed, the purge gas is discharged to the exhaust space 46 before the pressure difference between the processing space 10 and the backside space 23 reaches the value for lifting the clamp ring 7. It is possible to reliably prevent inconvenience such as fluttering.
[0027]
Further, in order to sufficiently prevent the processing gas from entering the peripheral edge and the back surface of the wafer W during film formation, the purge gas flows through the first flow path 14 and the second flow path 15 during the film formation. It is preferable to prevent the valve 35 from operating due to a pressure loss that normally occurs due to outflow. When the valve 35 is operated with such a pressure difference, a sufficient amount of purge gas cannot be discharged from the backside space 23 to the processing space 10 during film formation, and the processing gas flows into the backside space 23. There is a possibility that intrusion occurs frequently, and problems such as generation of particles due to undesired film formation on the peripheral edge and back surface of the wafer W may increase.
[0028]
On the other hand, the gas introduction mechanism 40 includes an opening 44 provided on the side wall of the shield base 3, a valve body 42 that forms a chamber communicating with the exhaust space 46 through the opening 44 inside the shield base 3, and the valve body 42, a discharge hole 43 provided at three locations on the top wall, and a valve body 41a having a diameter larger than the discharge hole 43 and a shaft portion 41b, and a valve 45 inserted through each discharge hole 43. is doing. As shown in FIGS. 1 and 2, the valve 45 normally has the valve body 41 a that seals the discharge hole 43 by its own weight and prevents the processing gas from entering the backside space 23. Yes. However, when the pressure in the exhaust space 46 becomes higher than the pressure in the backside space 23, the valve element 41a receives an upward force due to the pressure difference. When the pressure difference exceeds a predetermined value, the valve body 41a is lifted and discharged. The holes 43 are opened, and the atmosphere of the exhaust space 46 is introduced into the backside space 23 as shown in FIG.
[0029]
FIG. 5 is a cross-sectional view taken along the line AA in FIG. 1 and shows the arrangement of the gas release mechanism 30 and the gas introduction mechanism 40 in the shield base 3. Thus, in the present embodiment, a pair of the gas release mechanism 30 and the gas introduction mechanism 40 are provided adjacent to one side of the shield base 3, and the gas release mechanism 30 and the gas introduction are provided on the opposite side of the shield base 3. Another pair of mechanisms 40 are provided. By arranging in this way, it is possible to prevent the pressure in the chamber 1 from becoming uneven due to the operation of the gas release mechanism 30 and the gas introduction mechanism 40.
[0030]
An exhaust device 58 is connected to the exhaust space 46 through exhaust ports 36 provided at the four corners of the bottom of the chamber 1. The exhaust device 58 has a valve (not shown) for adjusting the exhaust amount thereof, and the processing space 10 can be maintained at a predetermined degree of vacuum by exhausting the processing space 10 through the exhaust space 46. ing. Further, since the baffle plate 6 having a large number of holes is provided between the exhaust space 46 and the processing space 10, when the processing space 10 is depressurized in this way, the processing space 10 becomes the exhaust space 46. The pressure is reduced more slowly.
[0031]
A shower head 50 for introducing a processing gas or the like is provided on the ceiling of the chamber 1. The shower head 50 has a shower base 51 formed by being fitted to the lid 2, and a gas inlet 55 is provided at the upper center of the shower base 51. Further, two stages of diffusion plates 52 and 53 are provided below the gas inlet 55, and a shower plate 54 is provided below the diffusion plates 52 and 53. A gas supply mechanism 60 that supplies a processing gas or the like to the processing space 10 in the chamber 1 is connected to the gas inlet 55.
[0032]
The gas supply mechanism 60 is ClF ₃ Gas supply source 61, N ₂ Gas supply source 62, WF ₆ Gas supply source 63, Ar gas supply source 64, SiH ₄ Gas supply source 65, H ₂ A gas supply source 66 is provided. ClF ₃ A gas line 67 is connected to the gas supply source 61, and a mass flow controller 81 and front and rear opening / closing valves 74 and 88 are provided in the gas line 67. N ₂ A gas line 68 is connected to the gas supply source 62, and the gas line 68 is provided with a mass flow controller 82 and opening / closing valves 75 and 89 before and after the mass flow controller 82. WF ₆ A gas line 69 is connected to the gas supply source 63, and a branch line 70 branches from the middle of the gas line 69. The gas line 69 is provided with a mass flow controller 83 and front and rear opening / closing valves 76, 90, and the branch line 70 is provided with a mass flow controller 84 and front and rear opening / closing valves 77, 91. This branch line 70 is used in a nucleation process to be described later, and its flow rate is more strictly controlled. A gas line 71 is connected to the Ar gas supply source 64, and the gas line 71 is provided with a mass flow controller 85 and opening / closing valves 78 and 92 before and after the mass flow controller 85. The gas line 69 and the branch line 70 merge with the gas line 71, and Ar gas is WF. ₆ It functions as a gas carrier gas. SiH ₄ A gas line 72 is connected to the gas supply source 65. The gas line 72 is provided with a mass flow controller 86 and opening / closing valves 79 and 93 before and after the mass flow controller 86. H ₂ A gas line 73 is connected to the gas supply source 66, and the gas line 73 is provided with a mass flow controller 87 and opening / closing valves 80 and 94 before and after the mass flow controller 87. The gas lines 67, 68, 71, 72, 73 are connected to the gas line 95, and the gas line 95 is connected to the gas inlet 55.
[0033]
Hereinafter, an example of an operation for forming a W film on the surface of the wafer W by the CVD film forming apparatus 100 configured as described above will be described. Table 1 is a table showing changes in the pressure of the processing space and the purge gas flow rate in STEP 1 to STEP 10 from the loading to unloading of the wafer W in this example.
[0034]
[Table 1]

[0035]
First, a gate valve (not shown) provided on the side wall of the chamber 1 is opened, the wafer W is loaded into the chamber 1 by the transfer arm, and the lift pins 16 are raised from the mounting table 5 until a predetermined length protrudes to receive the wafer W. After that, the transfer arm is retracted from the chamber 1 and the gate valve is closed.
[0036]
In this state, without supplying the gas from the gas supply mechanism 60 and the purge gas supply device 59, the exhaust valve of the exhaust device 58 is fully opened to rapidly depressurize the chamber, and the pressure in the chamber 1 is increased to a high vacuum of an ultimate pressure of 100 mTorr. After the state, the lift pins 16 and the clamp ring 7 are lowered, the lift pins 16 are immersed in the mounting table 5 to place the wafer W on the mounting table 5, and the clamp ring 7 is held in contact with the wafer W and held. Lower to position (STEP 1). The reason why the wafer W is placed in a high vacuum state and held by the clamp ring 7 in this way is to prevent the wafer W from sliding on the placing table 5. Further, the lamp 26 in the heating chamber 25 is turned on, and heat rays are radiated while the turntable 27 is rotated by the rotary motor 29 to heat the wafer W to a predetermined temperature.
[0037]
Next, in order to form a nucleation film on the surface of the wafer W mounted on the mounting table 5 and held by the clamp ring 7, the opening of the exhaust valve of the exhaust device 58 is lowered and the gas supply mechanism 60 N ₂ Gas supply source 62, Ar gas supply source 64, SiH ₄ Gas supply 65 and H ₂ Supply of processing gas or purge gas from the gas supply source 66 and the purge gas supply device 59 is started at a predetermined flow rate, respectively, and the pressure in the processing space 10 is set to 500 Pa (STEP 2). Next, while maintaining the flow rate of each gas, WF ₆ While the flow rate is strictly controlled from the gas supply source 63 via the branch line 70 by the high-precision mass flow controller 84, a smaller amount of WF is used than in the main film forming process described later. ₆ Gas supply is started (STEP 3), and in this state, SiH shown in the following formula (1) ₄ The reduction reaction is allowed to proceed for a predetermined time, and a nucleation film is formed on the surface of the wafer W (STEP 4). In STEP 3 and STEP 4, the pressure in the processing space 10 is maintained at 500 Pa.
2WF ₆ + 3SiH ₄ → 2W + 3SiF ₄ + 6H ₂ ……… (1)
[0038]
Then WF ₆ Gas and SiH ₄ With the gas supply stopped and the supply amount of other gases maintained, the exhaust valve of the exhaust device 58 is fully opened to rapidly depressurize the inside of the processing space 10 and form a nucleation film, thereby remaining the processing gas. Is cleared from the processing space 10 (STEP 5).
[0039]
Next, a main film forming step of forming a W film on the surface of the wafer W on which the nucleation film is formed as described above is performed. First, while lowering the opening degree of the exhaust valve of the exhaust device 58, Ar gas as a carrier gas, H ₂ Gas, N ₂ The flow rates of the gas and purge gas are increased, and the pressure in the processing space 10 is increased to 10666 Pa (STEP 6). Next, the WF of the gas supply mechanism 60 ₆ WF for main depot from gas supply source 63 ₆ Gas supply started, Ar gas, H ₂ Gas, N ₂ The gas is reduced, and the inside of the processing space 10 is set as a processing gas atmosphere for the main deposit (STEP 7). In this state, H shown in the following formula (2) ₂ Reduction film W film formation is performed for a predetermined time (STEP 8). In STEP 7 and STEP 8, the flow rate of the purge gas and the pressure in the processing space 10 are maintained in the same manner as in STEP 7.
WF ₆ + 3H ₂ → W + 6HF ………… (2)
[0040]
After the completion of the film formation, the WF is ready for the removal of the wafer W. ₆ Gas and SiH ₄ Stop gas supply, Ar gas, H ₂ Gas, N ₂ With the supply of the gas and purge gas maintained, the exhaust valve of the exhaust device 58 is fully opened to rapidly depressurize the inside of the chamber 1, and the processing gas remaining after the completion of the film formation is cleared from the processing space 10 (STEP 9). Thereafter, the pressure reduction is continued in a state where supply of all gases is stopped, and the inside of the chamber 1 is brought into a high vacuum state (STEP 10).
[0041]
In this high vacuum state, the lift pins 16 and the clamp ring 7 are raised, the holding of the wafer W by the clamp ring 7 is released, and the lift pins 16 protrude from the mounting table 5 by a predetermined length so that the transfer arm can receive the wafer W. Raise to the correct position. The reason why the wafer W is released from being held in a high vacuum state and lifted by the lift pins 16 is to prevent the wafer W from sliding on the mounting table 5 as in STEP 1.
[0042]
Thereafter, purge gas, Ar gas, or the like is introduced into the chamber 1, the gate valve is opened, the transfer arm enters the chamber 1, the wafer W on the lift pins 16 is received by the transfer arm, and the transfer arm is withdrawn from the chamber 1. Thus, the wafer W is taken out and the film forming operation is completed. Further, after the wafer W is taken out, ClF is used as necessary. ₃ The inside of the chamber 1 is cleaned by supplying gas into the chamber 1 or the like.
[0043]
In such a process, in particular, in STEP 5, STEP 9, and STEP 10, since the valve of the exhaust device 58 is fully opened and the pressure is rapidly reduced, the pressure in the processing space 10 and the exhaust space 46 is rapidly reduced. In the conventional apparatus, in such a case, a large pressure difference is generated between the backside space 23 and the processing space 10 and the clamp ring 7 is fluttered. In the present embodiment, this pressure difference is clamped. Since the gas discharge mechanism 30 discharges the purge gas from the backside space 23 to the exhaust space 46 before reaching the size that causes the ring 7 to flutter, problems such as the flutter of the clamp ring 7 do not occur. Further, since the gas release mechanism 30 does not operate with the pressure loss that normally occurs when the purge gas flows out into the processing space 10 during film formation, the nucleation process in STEP 2 to STEP 4 and the film formation process in STEP 6 to STEP 8 are performed. In FIG. 2, the purge gas is not released, and the penetration of the processing gas into the peripheral edge and the back surface of the wafer W is sufficiently prevented by the purge gas.
[0044]
Further, in the conventional apparatus, when the apparatus malfunctions or fails, the pressure in the processing space 10 and the exhaust space 46 becomes extremely higher than the pressure in the backside space 23, and the CVD film forming apparatus is caused by the pressure difference. There is a possibility that the members constituting 100 are damaged, but in this embodiment, the gas introduction mechanism 40 can reduce the pressure difference by introducing the atmosphere of the exhaust space 46 into the backside space 23. It is possible to prevent the member from being damaged due to such a pressure difference.
[0045]
Next, a design example of the valve 35 in the gas release mechanism 30 will be described.
Here, a case where the valve 35 is configured based on data of a typical actual machine will be described.
The clamp ring 7 holds the wafer W on the mounting table 5 by the weight of the clamp ring 7 and the force of three springs connecting the clamp ring 7 and the three lift pins 16. The actual weight of the clamp ring 7 in the actual machine is 0.9 N, the total spring force is 15 N, and the area A of the clamp ring 7 is 0.0185 m. ² The clamp ring 7 holds the wafer W at 0.9N + 15N = 15.9N. Therefore, it is considered that when the force greater than 15.9 N acts upward of the clamp ring 7 due to the pressure difference between the processing space 10 and the backside space 23, the clamp ring 7 is lifted and starts to flutter. From this, the magnitude ΔP of the pressure difference between the processing space 10 and the backside space 23 where the clamp ring 7 starts fluttering in this actual machine. ₁ Is ΔP ₁ = 15.9 / 0.0185 = 859.5 Pa.
[0046]
Further, from the data of the actual machine, the pressure loss ΔP caused by the purge gas flowing out from the backside space 23 to the processing space 10 during film formation. ₂ Is ΔP ₂ ≈113 Pa was calculated. Therefore, the pressure difference between the exhaust space 46 and the backside space 23 is ΔP. ₂ If the purge gas is released in the following cases, the purge gas cannot sufficiently flow during film formation.
[0047]
From the above, in this actual machine, the pressure difference P at which the valve 35 operates is expressed as ΔP ₁ <P <ΔP ₂ That is, it is preferable that 113 Pa <P <859.5 Pa, so that the purge gas can effectively prevent the processing gas from entering the peripheral portion and the back side of the wafer W during film formation, and the clamp ring 7 can be used during rapid decompression. It was required to be able to prevent the fluttering that occurs in
[0048]
The valve 35 was configured to operate with the pressure difference P within this preferable range. Here, due to the installation space of the gas release mechanism 30, the outer diameter of the valve body 31a is 14 mm, and the wall thickness is 1.5 mm. Since the pressure difference at which the valve body 31a configured in this way operates was calculated to be 143 Pa per sheet, by using the three valve bodies 31a for one valve 35, the pressure at which the valve 35 operates can be set as described above. It can be set to 429 Pa within the preferred range. One valve element 31a having a thickness of 4.5 mm may be used, but here, three 1.5 mm valve elements 31a are used in order to facilitate adjustment. By using the valve 35 configured as described above for the gas release mechanism 30, the backside space is reduced when the processing space 10 is decompressed while preventing the processing gas from entering the backside space 23 by the purge gas during film formation. The purge gas was appropriately discharged from the nozzle 23 to prevent the clamp ring 7 from flickering. Here, a design example of the valve 35 configured based on typical data of an actual machine is shown, and the preferable range of the pressure difference at which the valve 35 operates and the configuration of the valve 35 are limited to these. It is not a thing.
[0049]
The present invention can be variously modified without being limited to the above embodiment. For example, in the above embodiment, the gas release mechanism 30 and the gas introduction mechanism 40 are both provided so as to protrude inside the shield base 3, but the outside of the shield base 3 as in the gas release mechanism 30 ′ shown in FIG. 8. You may provide so that it may protrude. In this case, a valve 35 'may be provided sideways as in the gas release mechanism 30 "shown in Fig. 9. However, when the valve 35' is set sideways, the valve 35 'seals the discharge hole 33' by its own weight. Therefore, it is necessary to seal the valve 35 ′ against the discharge hole 33 ′ with a spring or the like, and in the above, the gas discharge mechanism 30 and the gas introduction mechanism 40 are both the discharge holes 33 and 43. However, the present invention is not limited to this, and the number and arrangement of the gas discharge mechanism 30 and the gas introduction mechanism 40 can be changed.
[0050]
In the above embodiment, the present invention has been described with respect to the CVD deposition of W. However, the present invention is not limited to this, and can be applied to CVD deposition of other materials such as Al, WSi, Ti, and TiN. The present invention can also be applied to gas processing other than CVD. Further, the substrate to be processed is not limited to a wafer, and may be another substrate.
[0051]
【The invention's effect】
As described above, according to the present invention, when the pressure in the space is higher than the pressure outside the space in the processing container by a predetermined value or more, the gas release mechanism that releases the purge gas from the space is provided. By providing, when the substrate to be processed is processed, the purge gas prevents the processing gas from entering the space, and when the inside of the processing container is decompressed, the purge gas is supplied by the gas release mechanism. Since it can be discharged from the space and a large pressure difference does not occur inside and outside the space in the processing container, inconvenience such as fluttering of the substrate holding member is prevented. This makes it possible to rapidly depressurize the processing space after, for example, a film forming process, and it is possible to reduce the process time and improve the throughput.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a CVD film forming apparatus according to an embodiment of the present invention, showing a state in which a wafer W is mounted on a mounting table.
2 is a view showing a state in which a wafer W is supported on lift pins in the CVD film forming apparatus shown in FIG. 1;
3 is an enlarged view for explaining the purge gas flow in the vicinity of the clamp ring of the CVD film forming apparatus shown in FIG. 1; FIG.
FIG. 4 is a longitudinal sectional view of a gas release mechanism and a gas introduction mechanism.
FIG. 5 is a partial cross-sectional view of the CVD film forming apparatus shown in FIG.
FIG. 6 is an enlarged cross-sectional view of a state in which the gas release mechanism is discharging purge gas.
FIG. 7 is an enlarged cross-sectional view in a state where the gas introduction mechanism introduces an atmosphere from the exhaust space.
FIG. 8 is a view showing a modified example of the gas release mechanism.
FIG. 9 is a view showing another modification of the gas release mechanism.
FIG. 10 is a cross-sectional view schematically showing a conventional CVD film forming apparatus.
[Explanation of symbols]
1; chamber
2; Lid
3; Shield base
4; Attachment
5: Mounting table
6; Baffle plate
7; Clamp ring
10: Processing space
16; Lift pin
17; reflector
20: Support member
23: Backside space
25; heating chamber
30; Gas release mechanism
31a; valve body
31b; shaft portion
32; Valve body
33; discharge hole
35; valve
37: Purge gas introduction route
40; Gas introduction mechanism
41a; valve body
41b; shaft portion
42; valve body
43; discharge hole
45; Valve
46; exhaust space
50; shower head
58; exhaust system
59; Purge gas supply device
60; gas supply mechanism
100: CVD film forming apparatus
W: Semiconductor wafer

Claims (12)

A processing container for processing a substrate to be processed using a processing gas;
A mounting table disposed in the processing container on which the substrate to be processed is mounted;
A processing gas supply means for supplying a processing gas to the surface side of the substrate to be processed in the processing container;
An annular substrate holding member for holding the periphery of the substrate to be processed from above and holding it on the mounting table;
A purge gas supply means for supplying a purge gas to a space formed on the back side of the substrate to be processed;
A purge gas channel defined by the substrate holding member for guiding the purge gas from the space to the upper side thereof;
A gas release mechanism for releasing the purge gas from the space when the pressure in the space is higher than a pressure outside the space inside the processing container by a predetermined value or more ;
The gas release mechanism discharges the purge gas before a pressure difference inside and outside the space in the processing container reaches a value where the substrate holding member is lifted by the purge gas flowing through the purge gas flow path. A processing device.   A support member for holding an outer peripheral side of the substrate holding member; and the purge gas flow path includes a first flow path passing between the substrate holding member and the substrate to be processed, the substrate holding member, and the support member. The processing apparatus according to claim 1, further comprising a second flow path that passes between the two.   The gas discharge mechanism includes a discharge hole for discharging the purge gas, and a valve for opening the discharge hole when a pressure difference inside and outside the space in the processing container becomes higher than a predetermined value. The processing apparatus according to claim 1 or 2. The gas release mechanism is configured so that the purge gas after the pressure difference inside and outside the space in the processing container exceeds the value of pressure loss caused by the purge gas flowing out of the space when the substrate to be processed is processed. The processing apparatus according to any one of claims 1 to 3 , wherein the processing apparatus is discharged. A gas introduction mechanism for introducing an atmosphere outside the space in the processing container into the space when the pressure outside the space in the processing container becomes higher than the pressure in the space by a predetermined value or more; The processing apparatus according to any one of claims 1 to 4 , further comprising: The gas introduction mechanism includes an introduction hole for introducing an atmosphere outside the space in the processing container into the space, and a pressure outside the space in the processing container is higher than the pressure in the space by the predetermined value or more. The processing apparatus according to claim 5 , further comprising a valve that opens the introduction hole when it becomes. A processing container for processing a substrate to be processed using a processing gas;
A mounting table disposed in the processing container on which the substrate to be processed is mounted;
A processing gas supply means for supplying a processing gas to a first space formed on the surface side of the substrate to be processed;
An annular substrate holding member that holds and holds the periphery of the substrate to be processed from above;
A purge gas supply means for supplying a purge gas to a second space formed on the back side of the substrate to be processed;
A purge gas flow path defined by the substrate holding member for guiding the purge gas from the second space to the first space;
Exhaust means for exhausting the first space through a third space formed below the first space and outside the second space;
A gas release mechanism for releasing the purge gas into the third space when the pressure in the second space is higher than the pressure in the first space by a predetermined value or more ;
The gas release mechanism releases the purge gas before the pressure difference between the second space and the first space reaches a value where the substrate holding member is lifted by the purge gas flowing through the purge gas flow path. A processing apparatus characterized by the above. A support member for holding an outer peripheral side of the substrate holding member; and the purge gas flow path includes a first flow path passing between the substrate holding member and the substrate to be processed, the substrate holding member, and the support member. The processing apparatus according to claim 7 , further comprising a second flow path that passes between the two. The gas release mechanism is provided so as to communicate with the third space and the second space, the discharge hole for discharging the purge gas, and the pressure of the second space is higher than the pressure of the third space. also processing apparatus according to claim 7 or claim 8 characterized in that it has a valve for the discharge hole in an open state when the higher the predetermined value or more. In the gas release mechanism, when a pressure difference between the second space and the first space is used to process a substrate to be processed using a processing gas, a purge gas is discharged from the second space to the first space. The processing apparatus according to any one of claims 7 to 9 , wherein the purge gas is released after exceeding a pressure loss caused by flowing into the gas. And a gas introduction mechanism for introducing the atmosphere of the third space into the second space when the pressure in the third space is higher than the pressure in the second space by a predetermined value or more. The processing apparatus according to claim 7, wherein: The gas introduction mechanism is provided so as to communicate the third space and the second space, and an introduction hole for introducing the atmosphere of the third space into the second space; The processing apparatus according to claim 11 , further comprising: a valve that opens the introduction hole when the pressure in the space is higher than the pressure in the second space by the predetermined value or more.

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