JP2004131777A

JP2004131777A - Method for formation of deposition film

Info

Publication number: JP2004131777A
Application number: JP2002296325A
Authority: JP
Inventors: Takahisa Taniguchi; 谷口　貴久; Kazuyoshi Akiyama; 秋山　和敬
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2002-10-09
Filing date: 2002-10-09
Publication date: 2004-04-30

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for formation of a deposition film for improving the utilization efficiency of an apparatus by detecting the phenomenon that defective deposition occurs by detecting the defective deposition in an early period, and by stopping the deposition in a step of formation of the deposition film by utilizing a plasma. <P>SOLUTION: The change in the electric power of the reflected waves of high-frequency power under plasma treatment and the pressure in a reaction vessel is measured in formation of the deposition film on a substrate to be treated by introducing treating gas into the reaction vessel and by making the treating gas to the plasma by the high-frequency power. When a synchronous change in the electric power of the reflected waves of the high-frequency power under the plasma treatment and the pressure in the reaction vessel arises, whether such change is due to the stop of the plasma discharge or not is judged by comparing the pressure in the reaction vessel and the pressure in the state of not impressing the high-frequency power. When the synchronous change in the electric power of the reflected waves of the high-frequency power under the plasma treatment and the pressure in the reaction vessel is judged to arise not from the stop of the plasma discharge, the plasma treatment is stopped according to the result of the measurement of the change in the electric power and the pressure. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、堆積膜形成方法に関し、特に、プラズマを利用して被処理基体に電子写真用感光体や光起電力デバイス、撮像デバイス等の機能性堆積膜を形成する際に、不良成膜を的確に検出することによって、装置の利用効率を向上させることができる堆積膜形成方法に関する。
【０００２】
【従来の技術】
従来、被処理気体にプラズマ処理を施す際には、プラズマの様子をモニタし、モニタの結果をプラズマの異常放電の検知や成膜状態の良否の判断等に利用してきた。例えば、特登録０３１３７８１０には、マイクロ波により被処理基体にプラズマ処理を施す際に、マイクロ波の反射波のパワー、放電圧力、放電電流の少なくとも一つを検出し、検出値の変化に応じて放電停止状態を検知する例が開示されている。また、特開平１０−０７４７３４には、高周波の反射波を検出することによってプラズマのインピーダンスの変化を検出し、その検出回数に応じて装置のメンテナンスを行い、プラズマ処理装置の停止時間を短縮可能とする例が開示されている。
【０００３】
これらの高周波の反射波の電力や放電圧力等によるプラズマの様子のモニタは、プラズマを利用した堆積膜の形成時には、プラズマ放電の停止や堆積膜の剥離の検知に利用することができる。例えば、プラズマＣＶＤによって水素または／およびハロゲンで補償されたアモルファスシリコン等のアモルファス材料からなる半導体用等の堆積膜を基体上に形成して電子写真感光体を製造する場合、処理中の被処理基体の温度や高周波電力、処理ガスの流量、反応容器内の圧力等が適切でないと、プラズマ放電の停止や堆積膜の剥離が発生することがある。堆積膜の形成中にプラズマ放電が停止すると、堆積膜の形成が途絶され、その後堆積膜の形成を再開してもプラズマ放電の停止前後で堆積膜中に界面が発生するため、電子写真感光体の電子写真特性が変化することが多い。また、堆積膜の形成中に被処理基体上で堆積膜が剥離すると、堆積膜の剥離を起こしたアモルファスシリコン電子写真感光体は、十分な電子写真特性を満足することができないために不良成膜となり、製造歩留まりを低下させる。また、一つの反応容器内で複数の被処理基体に同時に堆積膜を形成する際には、複数の被処理基体のうちの１つで堆積膜が剥離すると、剥離した膜片が塵埃として他の被処理基体に付着することがある。剥離した膜片が被処理基体に付着すると、そこが核となって堆積膜が異常成長を起こし、球状突起となることがある。この球状突起が多発すると、画像を出力したときに画像欠陥が発生しやすくなるため、電子写真感光体としての機能が著しく低下する。
【０００４】
【発明が解決しようとする課題】
以上のことから、堆積膜の剥離が発生したときには、速やかに成膜を停止して次の成膜を開始することによって装置の利用効率を向上させることができる。しかしながら、プラズマの様子の変化を検知したときに、その原因を正確に特定し、かつ不良成膜となるようなプラズマの様子の変化を的確に判別して堆積膜の形成を中止しなければ、却って装置の利用効率や歩留まりが低下する恐れがある。例えば、先述のように、プラズマＣＶＤによって被処理基体上にアモルファスシリコン堆積膜を形成する際には、プラズマの様子をモニタすることによってプラズマ放電の停止や堆積膜の剥離等によるプラズマの変化を検知することができる。ここで、プラズマ放電が一度でも停止したときには、堆積膜の形成が途絶されることによって電子写真感光体としての品質が低下してしまうため、すぐに堆積膜の形成を中止して次の堆積膜の形成を行うことで装置の利用効率を向上させることができる。一方、堆積膜の剥離が発生したときには、プラズマ放電は維持されている場合が多く、これをプラズマ放電の停止と誤判断して堆積膜の形成を中断すると、本来良品であったものが不良成膜と見なされ、却って歩留まりが低下してしまうことがある。すなわち、堆積膜の剥離が小規模なときには、その電子写真特性や画像欠陥等の品質に影響を及ぼさないことがある。そのため、小規模な堆積膜の剥離に対しては堆積膜の形成を中止せず、不良成膜となるような規模の堆積膜の剥離が発生したときのみ堆積膜の形成を中止することで歩留まりを向上させることができる。つまり、不良成膜となるような堆積膜の剥離の規模に対応する閾値を設け、閾値を超えるような堆積膜の剥離が発生したときのみ堆積膜の形成を中止することが歩留まりの向上には効果的である。
【０００５】
以上のように、プラズマ放電の停止や、堆積膜の剥離の発生の有無を監視し、プラズマ放電の停止や堆積膜の品質を著しく低下させるような規模の堆積膜の剥離を的確に検知して速やかに堆積膜の形成を中止し、すぐに次の堆積膜の形成を開始することで装置の利用効率や歩留まりを向上させることができる。しかし、プラズマの状態のモニタによって堆積膜の剥離の規模を的確に判断することができる手段はこれまでなかった。
【０００６】
［目的］
本発明は、以上のような従来技術における改善すべき点を解決するためになされたものである。本発明の目的は、プラズマを利用した堆積膜の形成中に堆積膜の剥離が発生したときに、放電停止と堆積膜の剥離とを正確に判別し、かつ不良成膜となる規模の堆積膜の剥離を正確に検知することのできる堆積膜形成方法を提供することにある。
【０００７】
【課題を解決するための手段】
上記の目的を達成するため、本発明は、堆積膜形成方法を次のように構成したものである。すなわち、反応容器内に処理ガスを導入し、高周波電力によって処理ガスをプラズマ化し、前記プラズマによって被処理基体に堆積膜を形成する堆積膜形成方法において、プラズマ処理中の高周波電力の反射波の電力および反応容器内の圧力の変化を測定し、プラズマ処理中の前記高周波電力の反射波の電力および反応容器内の圧力の同期的な変化が発生したときに、それがプラズマ放電の停止によるものか否かを反応容器内の圧力と高周波電力を印加しない状態の圧力を比較することによって判断し、プラズマ処理中の高周波電力の反射波の電力および反応容器内の圧力の同期的な変化がプラズマ放電の停止によるものでないと判断された場合、プラズマ処理中の高周波電力の反射波の電力と、反応容器内の圧力の変化の測定結果に応じてプラズマ処理を中止することを特徴とする。
【０００８】
ここで、プラズマ放電が停止したか否かは、反応容器内の圧力の変化から知ることができる。すなわち、反応容器内の圧力が変化したときに高周波電力の印加前の圧力と比較し、高周波印加前の圧力付近にまで反応容器内の圧力が達していればプラズマ放電が停止したと判断することができ、そうでない場合は堆積膜の剥離等によるプラズマの乱れが発生したと判断することができる。また、高周波の反射波の電力または反応容器内の圧力のどちらかのみでもプラズマの状態の変化を知ることはできるが、本発明者らの検討の結果、小規模な膜剥がれが発生したときには、圧力の変化のみをモニタするだけでは、確実に堆積膜の剥離であると判断することが困難である。また、ノイズの発生等による誤判断を防止するためには、高周波の反射波の電力と反応容器内の圧力の両方の変化の様子を監視することによって、より正確にプラズマの状態の変化を知ることができる。
【０００９】
ここで、本発明においては、プラズマの放電停止や堆積膜の剥離を検知した時点で堆積膜の形成を中止することもできるが、堆積膜の剥離と判断されたときには、さらに高周波の反射波の電力と反応容器内の圧力の測定を続け、堆積膜の品質が著しく低下するような大規模な堆積膜の剥離が発生したときにのみ堆積膜の形成を中止することもできる。例えば、プラズマ処理中の高周波電力の反射波の電力および反応容器内の圧力の同期的な変化がプラズマ放電の停止によるものでないと判断された場合、反射波の電力と容器内の圧力の同期的な変化の発生回数の累計検出回数が、規定値を超えたときにプラズマ処理を中止することができる。これによって、堆積膜の剥離が多く発生して堆積膜の品質が著しく低下することが予測されるときに、早期に堆積膜の形成を中断してすぐに次の堆積膜の形成を行うことができ、装置の利用効率を向上させることができる。
【００１０】
また、反射波の電力と反応容器内の圧力の同期的な変化がプラズマ放電の停止によるものでないと判断された場合、反射波の電力と反応容器内の圧力の同期的な変化が発生したときに、一定の時間を遡って反射波の電力と前記容器内の圧力の変化が発生した回数を計測し、その回数が規定値を超えたときにプラズマ処理を中止することも可能である。これによって、堆積膜の剥離の頻度から不良成膜を予測することができるため、より早期に堆積膜の形成を中止してすぐに次の堆積膜の形成を行い、装置の利用効率をさらに向上させることができる。
【００１１】
【発明の実施の形態】
以下に、本発明における実施の形態と作用を、図を用いて説明する。
【００１２】
図１は、本発明に係るプラズマ処理装置の一例の模式図である。この装置は、プラズマＣＶＤによって基体上にアモルファスシリコン感光体を形成するために構成された装置の一例である。この装置は、大別して被処理基体にプラズマ処理を施すための反応装置１００と、反応容器を排気するための排気装置２００、プラズマ処理の処理ガスを供給するガス供給装置３００からなっている。反応容器は真空排気路６０１を介して排気装置２００と接続されており、ガス供給路６０２を介してガス供給装置３００に接続されている。
【００１３】
反応装置１００は、以下のように構成されている。セラミックス等の誘電体材料からなる反応容器１０１は、架台１０２の上に設置されている。反応容器付近には圧力計１０３が設けられている。圧力計１０３は反応容器１０１内の圧力を直接測定できるように設置しておくことが好ましいが、堆積膜の形成工程において圧力計にも堆積膜が形成されてしまうことが懸念されるときには、反応容器内の圧力を実質的に知ることができる範囲内で真空排気路６０１中の反応容器１０１の近傍に設けることもできる。また、反応容器内には被処理基体１０４を保持するための保持部材１０５が設けられており、その内側には、被処理基体を所望の温度に加熱するためのヒータ１０６が設けられている。被処理基体１０４の内部にあるヒータがプラズマにさらされないように、被処理基体１０４の上部にキャップ１０７が設けられている。反応容器１０１は上蓋１０８によって真空封止される。反応容器底部には排気口１０９が設けられ、真空排気路６０１が接続されている。真空排気路６０１には、排気コンダクタンスを調節するためのスロットル弁５０２が設けられている。また、ガス導入管１１０はガス供給路６０２を介してガス供給装置３００に接続され、処理ガスやパージ、大気開放するためのガスを反応容器１０１内に導入可能となっている。そして、処理ガスをプラズマ化するため、高周波電源４００からマッチングボックス４０１、分岐板４０２、そして反応容器１０１の周囲に設けられた複数の電極４０３を介して、反応容器１０１内に高周波電力を導入できるようになっている。電極４０３の周りには、周囲に高周波が漏洩するのを防止する金属製の高周波シールド１１１が設けられている。さらに、マッチングボックス４０１にはマッチングコントローラ４０４が接続され、プラズマ処理中のマッチングポイントが調節可能となっている。一方、ガス供給装置３００にはプラズマ処理に用いる処理ガスのボンベ３３１〜３３６の他に、ガス供給装置３００の配管のパージや被処理基体１０４の加熱時等に用いられるアルゴンやヘリウム等の不活性ガスのボンベ３３７が設けられており、夫々のボンベにはマスフローコントローラ３１１〜３１７やレギュレータ３２１〜３２７が設けられている。
【００１４】
また、本プラズマ処理装置には、高周波電力の入射波や反射波の電力と、反応容器内の圧力の経時変化を測定するためのレコーダ７０１が設けられている。高周波電源４００は、高周波電力の入射波と反射波の夫々の電力の大きさを表示する電力計を備え、入射電力および反射波の電力の大きさは電圧値等に変換され、レコーダ７０１に記録される。同様に、圧力計１０３によって測定された圧力の値は電圧値等に変換され、レコーダ７０１に記録される。
【００１５】
図２に、反応容器１０１を円筒形としたときに、反応装置１００の内部の水平方向の断面の一例を示す。複数の被処理基体１０４が排気口１０９を中心に同一円周上に設置され、その周囲の同心円上にガス導入管１１０が設けられている。さらに、反応容器１０１の外には電極４０３および高周波シールド１１１が同一円周上に設けられている。なお、ここでは６本の被処理基体が設置可能な反応容器内の構成の一例を示したが、被処理基体の設置本数は被処理基体の直径や設置間隔等によって決定され、電極４０３やガス導入管１１０は、被処理基体の設置本数にあわせて配置することが望ましい。
【００１６】
図１および図２に示されたプラズマ処理装置を用いた本発明に係る堆積膜形成方法は、以下のようにして行われる。まず、全ての弁が閉じられた状態で、被処理基体１０４を反応容器内の保持部材１０５に保持し、キャップ１０７を設置し、上蓋１０８で反応容器１０１を封止する。次に、排気装置２００を作動させ、弁５０１を開いて反応容器１０１内を真空排気する。所定の圧力に達するまで反応容器内の排気を行った後、ヒータ１０６を用いて被処理基体を加熱する。このとき、ヘリウムやアルゴン等の不活性ガスを加熱用ガスとして反応容器内に導入してもよい。その際、不活性ガスのボンベ３３７に接続されているマスフローコントローラ３１７によって流量を調節する。被処理基体の温度が所望の温度に達した後、処理ガスのボンベ３３１〜３３６のうち、堆積膜の機能に応じて処理ガスの種類を選択し、そのガスの流量をマスフローコントロー３１１〜３１６によって調節し、弁５０３，５０４を開いてガス導入管１１０から処理ガスを反応容器内に導入する。処理ガスの流量が安定した後、スロットルリング５０２によって排気コンダクタンスを調節する。反応容器内の圧力が安定した後、高周波電源４００からマッチングボックス４０１、分岐板４０２を介して電極４０３に高周波電力を印加し、処理ガスをプラズマ化して基体上に堆積膜を形成する。このとき、ヒータ１０６によって被処理基体１０４の温度を適宜調節することができる。堆積膜の層構成や膜厚、特性は、目的に応じて原料ガスの種類や流量や反応容器内の圧力、高周波電力の大きさ等によって任意に調節する。このとき、被処理基体１０４を図示しない回転機構によって一定の速さで回転させておくと、被処理基体１０４の周辺において、周方向のプラズマの分布にむらがあるときでも均一な膜質を得ることができる。
【００１７】
堆積膜の形成中には、プラズマ放電の停止や堆積膜の剥離の有無をモニタする。図３に、堆積膜の剥離をモニタする一例のフローチャートを示す。高周波電力によって処理ガスがプラズマ化され、堆積膜の形成が開始した時点で堆積膜の形成時間を計るタイマをスタートさせる。堆積膜の形成の開始時間は、以下のようにして知ることができる。すなわち、処理ガスがプラズマ化され、堆積膜の形成が開始されたときには、処理ガスが分解されたり、処理ガスが堆積膜の形成に費やされることによって反応容器１０１内の圧力が堆積膜の形成開始前に比べて変化する。このことから、レコーダ７０１によって反応容器内の圧力をモニタしながら高周波電力を印加し、反応容器内の圧力が高周波電力印加前の圧力に比べて変化した時点を堆積膜の形成タイマの開始時間とすることができる。なお、堆積膜の形成に用いる処理ガスの種類や、排気装置の種類等よって、プラズマ放電の生起に伴う反応容器内の圧力変化は、プラズマ放電の生起前に比べて上昇する場合と低下する場合があるが、以下ではプラズマ放電の生起に伴い反応容器内の圧力が低下する場合を例に説明する。
【００１８】
プラズマ放電の生起に伴い反応容器内の圧力が低下し、堆積膜の形成タイマをスタートさせた後、レコーダ７０１によって高周波の反射波の電力および反応容器内の圧力をモニタしてプラズマ放電の停止や堆積膜の剥離の発生に伴うプラズマの様子の変化を監視する。ここで反応容器内の圧力や、高周波電力の反射波の電力のどちらか一方のみをモニタするだけでもプラズマの様子の変化を知ることはできるが、小規模な堆積膜の剥離が発生したときには、プラズマの変化も小さいため、堆積膜の剥離を確実に検知できないことがある。また、ノイズの発生等による誤判断を防止するためにも、反応容器内の圧力と高周波電力の反射波の電力の両方をモニタすることが望ましい。高周波の反射波の電力および反応容器１０１内の圧力が急激に変化したときには、それがプラズマ放電の停止によるものなのか、堆積膜の剥離によるものなのかを判別する。プラズマ放電の停止と堆積膜の剥離は、高周波の反射波の電力と反応容器内の圧力の挙動から、以下のようにして判別することができる。まず、堆積膜の形成中にプラズマ放電の停止や堆積膜の剥離が発生したときには、反射波の電力と反応容器内の圧力が急上昇する。ここで、その変化がプラズマ放電の停止によるものであるときには反射波の電力が増加し、また、反応容器内の圧力は高周波電力を印加していないときの圧力付近まで近づく。また、一度プラズマ放電が停止すると、復帰動作を施さない限りプラズマ放電は再び生起されにくく、プラズマ放電の停止後は反応容器内の圧力が上昇した状態が継続されることが多い。ただし、マッチングコントローラ４０４が自動的にマッチング調節を行う場合には、プラズマ放電の停止によって反射波の電力が増加した際に、マッチングが自動的に最適化されることでプラズマ放電が再び生起され、反射波の電力と反応容器内の圧力はプラズマ放電の停止前の状態に復帰することがある。また、プラズマ放電が不安定になったときに、プラズマ放電が停止と生起を繰り返すことがある。しかし、手動、自動のマッチング調節方法やプラズマ放電の停止の状態にかかわらず、プラズマ放電が停止したときの反応容器内の圧力は、高周波電力を印加していないときの圧力付近まで上昇するため、高周波の反射波の電力と反応容器内の圧力が急上昇したときに、反応容器内の圧力が高周波電力の印加前の圧力付近まで上昇していればプラズマ放電の停止と判断することができる。一方、堆積膜の形成中に堆積膜の剥離が発生したときには、剥がれて飛散する堆積膜の膜片によってプラズマに乱れが生じ、反射波の電力と反応容器内の圧力が定常状態よりも上昇する。ただし、このときプラズマ放電は維持されていることが多いため、反応容器内の圧力は、プラズマ放電が発生していないとき、すなわち高周波電力を印加していない状態の圧力よりも低い値までしか上昇しない。膜片の飛散が収まったときに、プラズマの乱れも収まるため、反射波の電力や反応容器内の圧力も堆積膜の剥離発生前の状態に元に戻る。このように、反射波の電力が増加すると共に反応容器内の圧力がプラズマ放電が生起していない状態の圧力付近にまで上昇したときにはプラズマ放電の停止と判断することができ、上昇した圧力の最大値がプラズマ放電が生起されていない圧力よりも低いときには、堆積膜の剥離が発生したと判断することができる。
【００１９】
プラズマ放電の停止と堆積膜の剥離を判別した後、堆積膜の形成を中止するか否かの判断を下す。プラズマ放電の停止が発生し、堆積膜の形成が途切れたときには、堆積膜の形成を再開してもプラズマ放電の停止前後で堆積膜中に界面が発生することによって、電子写真感光体の電子写真特性が著しく低下することから、不良成膜と判断して堆積膜の形成を中止するのが望ましい。一方、堆積膜の剥離を検知したときには、すぐに堆積膜の形成を中止するよりも、その後も高周波の反射波の電力と反応容器内の圧力の測定を続け、不良成膜となるような堆積膜の剥離が発生しているか否かを判断することによって、さらに製造歩留まりや装置の利用効率を向上させることができる。ここで、堆積膜の形成を中止する基準としては、堆積膜の剥離の発生回数や発生頻度等に閾値を設けることが考えられるが、堆積膜の剥離の規模によってこれらの基準を使い分けることができる。例えば、小規模な堆積膜の剥離が堆積膜の形成工程を通じて散発するような場合には、堆積膜の剥離の発生回数を基準とすることで不良成膜を特定することができる。一方、大規模な堆積膜の剥離が頻発する際には、堆積膜の剥離の発生頻度を基準とすることで、より早期に不良成膜の判断を下すことができる。図３には、堆積膜の剥離の発生回数を基準として不良成膜の判断を下すときのフローチャートが示されている。ここでは、反射波の電力および反応容器内の圧力の変化が発生したときに、それまでに発生した反射波の電力および反応容器内の圧力の変化の累計回数をその都度カウントし、それが規定値を超えたときに高周波電力の印加と処理ガスの導入を停止し、堆積膜の形成を中止する。これによって、堆積膜の剥離の発生回数を不良成膜の基準とすることができ、特に、小規模な堆積膜の剥離が散発するような場合でも不良成膜を正確に特定することができる。ここで、堆積膜の剥離の規定回数は、堆積膜の剥離の発生回数と不良成膜の発生率との関係を予め求めておき、その関係から決めることができる。堆積膜の剥離が発生しなかったり、堆積膜の剥離の発生回数が規定回数に達しないときには堆積膜の形成タイマが終了するまで堆積膜の形成が行われる。また、堆積膜の剥離が発生したときには、その発生頻度によってもその規模を知ることができる。図４に、堆積膜の剥離をモニタする他の例のフローチャートを示す。図４に示した例では、堆積膜の剥離の発生頻度を基準として不良成膜の判断を下すことができる。すなわち、反射波の電力および反応容器内の圧力の変化が発生した際に、そこからある一定の時間だけ遡って反射波の電力および反応容器内の圧力の変化の発生回数を計測し、その回数が規定回数を超えたときに堆積膜の形成を中止する。これによって、堆積膜の剥離の発生頻度を知ることができ、特に、大規模な堆積膜の剥離が頻発したときに、早期に電子写真感光体としての品質が著しく低下するような不良成膜を特定することができる。ここで、堆積膜の剥離の規定回数は、ある一定時間における堆積膜の剥離の発生回数と不良性膜の発生率との関係を予め求めておき、その関係から決めることができる。また、これらの２つの例を組み合わせ、反射波の電力および反応容器内の圧力の瞬時上昇の発生回数または一定時間遡って計測した反射波の電力および反応容器内の圧力の瞬時上昇の発生回数が規定回数に達した時点で堆積膜の形成を中止してもよい。なお、ここでは、プラズマ放電の生起に伴い反応容器内の圧力が低下する場合を例に説明したが、プラズマ放電の生起に伴い反応容器内の圧力が上昇するような反応系や装置形態の場合でも、堆積膜の剥離の発生と不良成膜の判断を以下のように下すことができる。すなわち、反射波の電力が急上昇するとともに反応容器内の圧力が急低下したときには、反応容器内の圧力が高周波電力印加前の圧力付近まで低下したか否かでプラズマ放電の停止と堆積膜の剥離を判断することができ、また、堆積膜の剥離の発生回数や頻度に閾値を設けて堆積膜の剥離の規模を特定することができる。
【００２０】
堆積膜の形成終了後、または中止された後、反応容器内およびガス供給装置内をアルゴンやヘリウム等の不活性ガスを用いてパージする。パージが終了した後、弁５０１を閉じて弁５０６を開き、反応容器内の圧力が大気圧になるまで窒素ガスを導入し、作製された電子写真感光体を取り出す。
【００２１】
以上のような方法によって、品質を著しく低下させるような規模の堆積膜の剥離を検知したときに、速やかに成膜を停止して次の成膜を開始することによって、装置の利用効率を向上させることができる。
【００２２】
【実施例】
以下に、本発明における実施例を、図を用いて説明する。ただし、本発明はこれらによってなんら限定されるものではない。
【００２３】
＜実験例１＞
図１および図２に示した装置を用いてアモルファスシリコン感光体を形成し、堆積膜の形成中に発生した堆積膜の剥離の回数や頻度と、堆積膜の剥離に起因すると思われる不良成膜の割合との関係を求めた。被処理基体としては、長さ３５８ｍｍ、直径８０ｍｍのアルミニウムシリンダーを反応容器中央に対して同心円上に６本配置した。また、感光体の層構成としては、導電性の被処理基体から電荷の注入を阻止する働きを有する電荷注入阻止層と、光導電性を有する光導電層と、耐湿性、繰り返し使用特性、電気的耐圧性、使用環境特性、耐久性向上を目的とする表面層を基体上に順次積層した。堆積膜の形成条件を表１に示す。
【００２４】
【表１】

なお、膜厚は目標値である。また、高周波電源は、周波数が１０５ＭＨｚのものを用いた。なお、本実験例においては、光導電層の温度を最適温度よりも高く設定することによって堆積膜の剥離が発生しやすい条件とした。堆積膜の形成は５０回行い、それぞれの堆積膜の形成中には、反射波の電力と反応容器内の圧力をモニタした。ただし、堆積膜の剥離の発生の有無やその規模にかかわらず最後まで堆積膜の形成を行い、夫々の処理ロットにおける堆積膜の剥離の発生回数を計測した。得られた電子写真感光体について、その電位特性と画像欠陥数を測定し、十分な電子写真特性を有する良品の収量と、堆積膜の剥離に起因するものと思われる不良成膜品の数を調査し、堆積膜の形成中に発生した堆積膜の剥離の回数毎に堆積膜の剥離に起因すると思われる不良成膜の本数の発生割合を求めた。
【００２５】
図５に堆積膜の剥離が多発したときの反射波の電力と反応容器内の圧力の時間変化の一例を示す。なお、破線は、各層におけるプラズマ放電が生起されていない状態の圧力である。この処理ロットにおいては、光導電層の形成途中で反射波の電力と反応容器内の圧力の瞬時上昇が同時に発生し、その後反射波の電力と反応容器内の圧力の瞬時上昇が頻発していることが分かる。また、反応容器内の圧力が上昇したときには、破線で示されたプラズマ放電が生起されていない状態の圧力よりも低いことから、プラズマ放電の停止ではなく、堆積膜の剥離が発生していることが分かる。図６に、堆積膜の剥離の発生回数毎の不良成膜の本数の割合を示す。図６から明らかなように、堆積膜の剥離の発生回数の累計が５回を超えると不良成膜が大幅に増加することが分かる。また、図７に、各ロットにおいて３０分の間に発生した堆積膜の剥離の回数の最大値と不良成膜の本数の割合の関係を示す。図７から明らかなように、本実験条件の下では、３０分間の間に最大で２回以上堆積膜の剥離が発生すると、不良成膜が大幅に増加することがわかる。
【００２６】
＜実施例１＞
図１に示した装置を用いて、高周波の反射波の電力と反応容器内の圧力をモニタしながらアモルファスシリコン感光体を形成した。被処理基体としては、実験例１と同様のものを用いた。また、感光体の層構成、堆積膜の形成条件も実験例１と同様とし、堆積膜の剥離が発生しやすい条件下でアモルファスシリコン感光体を形成した。堆積膜の形成中には、反射波の電力と反応容器内の圧力をモニタした。本実施例においては、光導電層の形成途中で反射波の電力と反応容器内の圧力が同時に上昇した時点で堆積膜の形成を中断し、すぐに次の堆積膜の形成を行った。実験例１において、堆積膜の形成を５０ロット分行うのに要した時間と同じ時間だけ堆積膜の形成を続け、得られた電子写真感光体について電位特性と画像欠陥数を測定し、電子写真感光体として十分な品質を有する良品の収量との実験例１に対する比を算出した。
【００２７】
＜実施例２＞
図１に示した装置を用いて、堆積膜の剥離の発生の有無をモニタしながらアモルファスシリコン感光体を形成した。被処理基体は実験例１で用いたものと同様のものを用い、堆積膜の形成条件も実験例１と同様とした。それぞれの堆積膜の形成中には、反射波の電力と反応容器内の圧力をモニタした。本実施例においては、反射波の電力と反応容器内の圧力が変化した累計回数が閾値を超えた時点で堆積膜の形成を中止し、すぐに次の堆積膜の形成を行った。堆積膜の形成を中止する閾値となる堆積膜の剥離の累計回数は、実験例１の結果に基づいて、５回とした。最後まで堆積膜を形成した処理ロットに対しては、得られた電子写真感光体についてその電位特性と球状突起数を測定し、実験例１で堆積膜の形成を５０ロット分行うのに要した時間と同じ時間だけ堆積膜の形成を続け、得られた電子写真感光体について電位特性と画像欠陥数を測定し、電子写真感光体として十分な品質を有する良品の収量の実験例１に対する比を算出した。
【００２８】
＜実施例３＞
図１に示した装置を用いて、堆積膜の剥離の発生の有無をモニタしながらアモルファスシリコン感光体を形成した。被処理基体は実験例１で用いたものと同様のものを用い、堆積膜の形成条件も実験例１と同様とした。それぞれの堆積膜の形成中には、反射波の電力と反応容器内の圧力をモニタした。反射波の電力と反応容器内の圧力の瞬時変化が発生した際に、そこから３０分間遡って反射波の電力と反応容器内の圧力の瞬時変化の回数を計測し、その回数が閾値を超えた処理ロットに対しては堆積膜の形成を中止し、すぐに次の堆積膜の形成を行った。堆積膜の形成を中止する閾値となる堆積膜の剥離の頻度は、実験例１の結果に基づいて、３０分の間に２回とした。最後まで堆積膜を形成した処理ロットに対しては、得られた電子写真感光体についてその電位特性と球状突起数を測定し、実験例１で堆積膜の形成を５０ロット分行うのに要した時間と同じ時間だけ堆積膜の形成を続け、得られた電子写真感光体について電位特性と画像欠陥数を測定し、電子写真感光体として十分な品質を有する良品の収量の実験例１に対する比を算出した。
【００２９】
実施例１、２、３において算出された、十分な電子写真特性を有する良品の収量の実験例１に対する比を表２に示す。
【００３０】
【表２】

表２から明らかなように、高周波の反射波の電力と反応容器内の圧力の変化が発生した時点で堆積膜の形成を中止し、すぐに次の堆積膜の形成を行うことで、同じ時間内での収量を向上させることができるが、堆積膜の剥離が発生した時点ですぐに堆積膜の形成を中止せず、反射波の電力と反応容器内の圧力の瞬時上昇の累計回数が規定値に達した時点で堆積膜の形成を中断したときには、品質に影響を及ぼさない小規模な堆積膜の剥離によって堆積膜の形成を中止してしまうことを防ぐことによって、収量がより増加しており、装置の利用効率を高めて堆積膜を形成できていることがわかる。また、反射波の電力と反応容器内の圧力の瞬時変化が発生した際に、そこから一定時間遡って反射波の電力と反応容器内の圧力の瞬時変化の回数を計測し、その回数が規定回数を超えた時点で堆積膜の形成を中止し、すぐに次の堆積膜の形成を行ったときには、電子写真感光体の品質を著しく低下させる規模の堆積膜の剥離をより早期に検知することによって同じ時間内における収量をさらに向上させることができる。
【００３１】
【発明の効果】
以上のように、本発明においては、高周波の反射波の電力と反応容器内の圧力をモニタすることによって、プラズマ放電の停止や堆積膜の剥離を正確に判断し、不良成膜が予測されるときには堆積膜の形成を中止し、すぐに次の堆積膜の形成を行うことによって、装置の利用効率を向上させることができる。また、堆積膜の剥離が発生したときに、堆積膜の剥離の発生回数の累計に閾値を設け、閾値を越えた時点で堆積膜の形成を中止し、すぐに次の堆積膜の形成を行うことによって、装置の利用効率をより向上させることができる。さらに、堆積膜の剥離が発生したときに、堆積膜の剥離の頻度に閾値を設け、閾値を越えた時点で堆積膜の形成を中止し、すぐに次の堆積膜の形成を行うことによって、さらに装置の利用効率をあげて堆積膜の形成を行うことができる。
【図面の簡単な説明】
【図１】本発明に係る塵埃の除去方法を行うために構成された処理装置の一例の模式図である。
【図２】反応容器を円筒形としたときに、反応容器の内部の水平方向の断面の一例である。
【図３】本発明に係る堆積膜形成方法によって、プラズマ放電の停止や堆積膜の剥離をモニタする一例のフローチャートである。
【図４】本発明に係る堆積膜形成方法によって、プラズマ放電の停止や堆積膜の剥離をモニタする他の例のフローチャートである。
【図５】堆積膜の形成工程において、堆積膜の剥離が多発したときの反射波の電力と反応容器内の圧力の時間変化の一例である。
【図６】堆積膜の剥離の発生回数とロット毎の収率の関係を示したものである。
【図７】堆積膜の形成中に、３０分の間に発生した堆積膜の剥離の回数の最大値と、ロット毎の収率との関係を示したものである。
【符号の説明】
１００　反応装置
１０１　反応容器
１０２　架台
１０３　圧力計
１０４　被処理基体
１０５　保持部材
１０６　ヒータ
１０７　キャップ
１０８　上蓋
１０９　排気口
１１０　ガス導入管
１１１　高周波シールド
２００　排気装置
３００　ガス供給装置
３１１〜３１７　マスフローコントローラ
３２１〜３２７　レギュレータ
３３１〜３３６　処理ガスのボンベ
３３７　不活性ガスのボンベ
４００　高周波電源
４０１　マッチングボックス
４０２　分岐板
４０３　電極
４０４　マッチングコントローラ
５０１　弁
５０２　スロットル弁
５０３〜５０６　弁
５１１〜５１７　弁
５２１〜５２７　弁
５３１〜５３７　弁
６０１　真空排気路
６０２　ガス供給路
７０１　レコーダ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a deposited film, and in particular, when forming a functional deposited film such as an electrophotographic photosensitive member, a photovoltaic device, or an imaging device on a substrate to be processed by using plasma, a defective film is formed. The present invention relates to a deposited film forming method capable of improving the utilization efficiency of an apparatus by accurately detecting the deposited film.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when performing plasma processing on a gas to be processed, the state of the plasma has been monitored, and the result of the monitoring has been used for detecting abnormal discharge of the plasma, determining the quality of the film formation, and the like. For example, in the special registration 03137810, at least one of the power of the reflected wave of microwave, the discharge pressure, and the discharge current is detected when performing the plasma processing on the substrate to be processed by the microwave, and according to a change in the detected value. An example of detecting a discharge stop state is disclosed. Japanese Patent Application Laid-Open No. 10-074734 discloses that the change in plasma impedance can be detected by detecting a high-frequency reflected wave, the apparatus can be maintained according to the number of times of detection, and the downtime of the plasma processing apparatus can be reduced. Examples have been disclosed.
[0003]
Monitoring of the state of the plasma by the power of these high-frequency reflected waves, discharge pressure, and the like can be used to stop plasma discharge and detect peeling of the deposited film when the deposited film is formed using the plasma. For example, when an electrophotographic photosensitive member is manufactured by forming a deposited film for a semiconductor or the like made of an amorphous material such as amorphous silicon compensated by hydrogen or / and halogen by plasma CVD on a substrate, the substrate to be processed during processing If the temperature, the high-frequency power, the flow rate of the processing gas, the pressure in the reaction vessel, and the like are not appropriate, the plasma discharge may stop and the deposited film may be peeled off. If the plasma discharge is stopped during the formation of the deposited film, the formation of the deposited film is interrupted, and even after the formation of the deposited film is restarted, an interface occurs in the deposited film before and after the stop of the plasma discharge. Often changes its electrophotographic characteristics. Also, if the deposited film is peeled off on the substrate to be processed during the formation of the deposited film, the amorphous silicon electrophotographic photoreceptor from which the deposited film has been peeled cannot have satisfactory electrophotographic characteristics, and thus has poor film formation. And lower the production yield. In addition, when simultaneously forming a deposited film on a plurality of substrates to be processed in one reaction vessel, if the deposited film is peeled off on one of the plurality of substrates to be processed, the peeled film pieces become dust as other particles. It may adhere to the substrate to be processed. When the peeled film piece adheres to the substrate to be processed, it becomes a nucleus, which causes abnormal growth of the deposited film, sometimes resulting in spherical projections. If such spherical projections occur frequently, image defects are likely to occur when an image is output, so that the function as an electrophotographic photosensitive member is significantly reduced.
[0004]
[Problems to be solved by the invention]
As described above, when peeling of the deposited film occurs, the use efficiency of the apparatus can be improved by immediately stopping the film formation and starting the next film formation. However, when a change in the state of the plasma is detected, if the cause is accurately specified, and the change in the state of the plasma that results in defective film formation is accurately determined and the formation of the deposited film is not stopped, On the contrary, there is a possibility that the utilization efficiency and the yield of the device are reduced. For example, as described above, when an amorphous silicon deposition film is formed on a substrate to be processed by plasma CVD, changes in plasma due to stopping of plasma discharge or peeling of the deposited film are detected by monitoring the state of the plasma. can do. Here, if the plasma discharge is stopped even once, the quality of the electrophotographic photoreceptor is deteriorated due to the interruption of the formation of the deposited film. The use efficiency of the apparatus can be improved by performing the formation. On the other hand, when the deposited film is peeled off, the plasma discharge is often maintained, and if this is erroneously determined to be the stop of the plasma discharge and the formation of the deposited film is interrupted, the originally good product becomes defective. It may be regarded as a film, which may lower the yield. That is, when the detachment of the deposited film is small, the quality such as the electrophotographic characteristics and image defects may not be affected. For this reason, the yield of the deposited film is not stopped when the deposited film is removed in a small scale, but is stopped only when the deposited film is detached on the scale that causes the defective film formation. Can be improved. In other words, to improve the yield, it is necessary to provide a threshold value corresponding to the scale of the peeling of the deposited film that results in defective film formation, and to stop the formation of the deposited film only when the peeling of the deposited film exceeds the threshold value. It is effective.
[0005]
As described above, the stop of the plasma discharge and the occurrence of peeling of the deposited film are monitored, and the stop of the plasma discharge and the peeling of the deposited film of a scale that significantly reduces the quality of the deposited film are accurately detected. By immediately stopping the formation of the deposited film and immediately starting the formation of the next deposited film, the utilization efficiency and the yield of the apparatus can be improved. However, there has been no means by which the scale of peeling of the deposited film can be accurately determined by monitoring the state of the plasma.
[0006]
[Purpose]
The present invention has been made in order to solve the above points in the prior art that need to be improved. SUMMARY OF THE INVENTION It is an object of the present invention to accurately determine a stop of discharge and peeling of a deposited film when peeling of the deposited film occurs during formation of the deposited film using plasma, and to provide a deposited film having a scale that results in defective film formation. It is an object of the present invention to provide a method for forming a deposited film capable of accurately detecting the separation of a film.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a method for forming a deposited film as follows. That is, in a deposition film forming method in which a processing gas is introduced into a reaction vessel, the processing gas is turned into plasma by high-frequency power, and a deposition film is formed on the substrate to be processed by the plasma, the power of a reflected wave of high-frequency power during plasma processing is increased. And measuring the change in the pressure in the reaction vessel, and when a synchronous change occurs in the power of the reflected wave of the high-frequency power and the pressure in the reaction vessel during the plasma processing, whether the change is due to the stop of the plasma discharge. It is determined by comparing the pressure in the reaction vessel with the pressure in the state where no high-frequency power is applied, and the synchronous change in the power of the reflected wave of the high-frequency power and the pressure in the reaction vessel during the plasma processing is the plasma discharge. If it is determined not to be due to the stoppage, the reflected wave power of the high-frequency power during the plasma processing and the measurement result of the pressure change in the reaction vessel Characterized in that to stop the plasma process.
[0008]
Here, whether or not the plasma discharge has stopped can be known from a change in the pressure in the reaction vessel. That is, when the pressure in the reaction vessel changes, it is compared with the pressure before the application of the high-frequency power, and it is determined that the plasma discharge has stopped if the pressure in the reaction vessel has reached near the pressure before the application of the high-frequency power. If not, it can be determined that the turbulence of the plasma due to the separation of the deposited film or the like has occurred. Further, it is possible to know the change in the state of the plasma only by either the power of the high-frequency reflected wave or the pressure in the reaction vessel, but as a result of the study of the present inventors, when a small-scale film peeling occurs, It is difficult to reliably determine that the deposited film is peeled off only by monitoring the change in pressure. Further, in order to prevent erroneous determination due to generation of noise, etc., it is possible to more accurately know the change in the state of the plasma by monitoring both changes in the power of the high-frequency reflected wave and the pressure in the reaction vessel. be able to.
[0009]
Here, in the present invention, the formation of the deposited film can be stopped at the time when the discharge stop of the plasma or the peeling of the deposited film is detected, but when it is determined that the deposited film is peeled, the reflected wave of a higher frequency is further reflected. The measurement of the power and the pressure in the reaction vessel may be continued, and the formation of the deposited film may be stopped only when a large-scale detachment of the deposited film occurs so that the quality of the deposited film is significantly reduced. For example, when it is determined that the synchronous change in the power of the reflected wave of the high-frequency power and the pressure in the reaction vessel during the plasma processing is not due to the stop of the plasma discharge, the synchronous change of the power of the reflected wave and the pressure in the vessel is performed. The plasma processing can be stopped when the total number of times of occurrence of a significant change exceeds a specified value. As a result, when it is predicted that a large amount of peeling of the deposited film will occur and the quality of the deposited film is significantly reduced, it is possible to interrupt the formation of the deposited film at an early stage and immediately form the next deposited film. It is possible to improve the utilization efficiency of the device.
[0010]
When it is determined that the synchronous change between the power of the reflected wave and the pressure in the reaction vessel is not due to the stop of the plasma discharge, the synchronous change in the power of the reflected wave and the pressure in the reaction vessel occurs. In addition, it is also possible to measure the number of times the change in the power of the reflected wave and the pressure in the container has occurred by going back a predetermined time, and stop the plasma processing when the number of times has exceeded a specified value. This makes it possible to predict defective film formation from the frequency of peeling of the deposited film, so that the formation of the deposited film is stopped earlier and the next deposited film is formed immediately, further improving the utilization efficiency of the apparatus. Can be done.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments and operations of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 is a schematic diagram of an example of the plasma processing apparatus according to the present invention. This apparatus is an example of an apparatus configured to form an amorphous silicon photoconductor on a substrate by plasma CVD. This apparatus is roughly divided into a reaction apparatus 100 for performing plasma processing on a substrate to be processed, an exhaust apparatus 200 for exhausting a reaction vessel, and a gas supply apparatus 300 for supplying a processing gas for plasma processing. The reaction vessel is connected to the exhaust device 200 via a vacuum exhaust channel 601 and connected to the gas supply device 300 via a gas supply channel 602.
[0013]
The reaction device 100 is configured as follows. A reaction vessel 101 made of a dielectric material such as ceramics is set on a gantry 102. A pressure gauge 103 is provided near the reaction vessel. The pressure gauge 103 is preferably installed so that the pressure in the reaction vessel 101 can be directly measured. However, when there is a concern that a deposited film may be formed on the pressure gauge in the deposition film forming process, It may be provided near the reaction vessel 101 in the vacuum exhaust path 601 as long as the pressure in the vessel can be substantially known. A holding member 105 for holding the substrate to be processed 104 is provided in the reaction vessel, and a heater 106 for heating the substrate to be processed to a desired temperature is provided inside the holding member 105. A cap 107 is provided above the substrate 104 so that the heater inside the substrate 104 is not exposed to the plasma. The reaction vessel 101 is vacuum-sealed by the upper lid 108. An exhaust port 109 is provided at the bottom of the reaction vessel, and a vacuum exhaust path 601 is connected. The vacuum exhaust path 601 is provided with a throttle valve 502 for adjusting the exhaust conductance. The gas introduction pipe 110 is connected to the gas supply device 300 via a gas supply path 602 so that a processing gas, a gas for purging, and a gas for opening to the atmosphere can be introduced into the reaction vessel 101. Then, in order to convert the processing gas into plasma, high-frequency power can be introduced into the reaction vessel 101 from the high-frequency power supply 400 via the matching box 401, the branch plate 402, and the plurality of electrodes 403 provided around the reaction vessel 101. It has become. A metal high-frequency shield 111 is provided around the electrode 403 to prevent high-frequency leakage to the surroundings. Further, a matching controller 404 is connected to the matching box 401 so that a matching point during the plasma processing can be adjusted. On the other hand, the gas supply device 300 includes, in addition to the cylinders 331 to 336 for the processing gas used for the plasma processing, inert gas such as argon and helium used for purging the piping of the gas supply device 300 or heating the substrate 104 to be processed. A gas cylinder 337 is provided, and each cylinder is provided with a mass flow controller 311 to 317 and a regulator 321 to 327.
[0014]
In addition, the present plasma processing apparatus is provided with a recorder 701 for measuring changes in the power of the incident wave and the reflected wave of the high-frequency power and the pressure in the reaction vessel with time. The high-frequency power supply 400 includes a wattmeter for displaying the magnitude of each of the incident wave and the reflected wave of the high-frequency power. The magnitude of the incident power and the reflected wave is converted into a voltage value or the like, and recorded in the recorder 701. Is done. Similarly, the pressure value measured by the pressure gauge 103 is converted into a voltage value or the like, and recorded on the recorder 701.
[0015]
FIG. 2 shows an example of a horizontal cross section of the inside of the reaction apparatus 100 when the reaction vessel 101 has a cylindrical shape. A plurality of substrates to be processed 104 are installed on the same circumference centering on the exhaust port 109, and a gas introduction pipe 110 is provided on a concentric circle around the same. Further, outside the reaction vessel 101, an electrode 403 and a high-frequency shield 111 are provided on the same circumference. Here, an example of the configuration inside the reaction vessel in which six substrates to be processed can be installed is shown. However, the number of substrates to be processed is determined by the diameter of the substrate to be processed, the installation interval, and the like. It is desirable to arrange the introduction pipes 110 in accordance with the number of substrates to be processed.
[0016]
The method for forming a deposited film according to the present invention using the plasma processing apparatus shown in FIGS. 1 and 2 is performed as follows. First, with all valves closed, the substrate to be processed 104 is held by the holding member 105 in the reaction vessel, a cap 107 is installed, and the reaction vessel 101 is sealed with the upper lid 108. Next, the exhaust device 200 is operated, the valve 501 is opened, and the inside of the reaction vessel 101 is evacuated. After exhausting the inside of the reaction vessel until the pressure reaches a predetermined pressure, the substrate to be processed is heated using the heater 106. At this time, an inert gas such as helium or argon may be introduced into the reaction vessel as a heating gas. At that time, the flow rate is adjusted by the mass flow controller 317 connected to the inert gas cylinder 337. After the temperature of the substrate to be processed reaches a desired temperature, a type of the processing gas is selected from the cylinders 331 to 336 of the processing gas according to the function of the deposited film, and the flow rate of the gas is controlled by the mass flow controllers 311 to 316. After the adjustment, the valves 503 and 504 are opened, and the processing gas is introduced from the gas introduction pipe 110 into the reaction vessel. After the flow rate of the processing gas is stabilized, the exhaust conductance is adjusted by the throttle ring 502. After the pressure in the reaction vessel is stabilized, high-frequency power is applied to the electrode 403 from the high-frequency power supply 400 via the matching box 401 and the branch plate 402, and the processing gas is turned into plasma to form a deposited film on the substrate. At this time, the temperature of the substrate to be processed 104 can be appropriately adjusted by the heater 106. The layer structure, film thickness, and characteristics of the deposited film are arbitrarily adjusted according to the purpose, the type and flow rate of the raw material gas, the pressure in the reaction vessel, the magnitude of the high-frequency power, and the like. At this time, if the substrate to be processed 104 is rotated at a constant speed by a rotating mechanism (not shown), uniform film quality can be obtained around the substrate to be processed 104 even when the distribution of plasma in the circumferential direction is uneven. Can be.
[0017]
During the formation of the deposited film, it is monitored whether the plasma discharge is stopped or the deposited film is separated. FIG. 3 shows a flowchart of an example of monitoring the separation of the deposited film. When the processing gas is turned into plasma by the high-frequency power and the formation of the deposited film is started, a timer for measuring the formation time of the deposited film is started. The start time of the formation of the deposited film can be known as follows. That is, when the processing gas is turned into plasma and the formation of the deposited film is started, the pressure in the reaction vessel 101 is reduced due to the decomposition of the processing gas or the consumption of the processing gas for forming the deposited film. It changes compared to before. From this, high-frequency power is applied while monitoring the pressure in the reaction vessel by the recorder 701, and the point in time when the pressure in the reaction vessel changes compared to the pressure before the high-frequency power is applied is defined as the start time of the deposition film formation timer. can do. Depending on the type of the processing gas used for forming the deposited film, the type of the exhaust device, and the like, the pressure change in the reaction vessel due to the occurrence of the plasma discharge increases and decreases compared to before the occurrence of the plasma discharge. However, an example in which the pressure in the reaction vessel is reduced due to the occurrence of plasma discharge will be described below.
[0018]
After the occurrence of the plasma discharge, the pressure in the reaction vessel decreases, and a timer for forming a deposited film is started. After that, the recorder 701 monitors the power of the high-frequency reflected wave and the pressure in the reaction vessel to stop the plasma discharge. The change in the state of the plasma accompanying the occurrence of peeling of the deposited film is monitored. Here, it is possible to know the change in the state of the plasma only by monitoring either the pressure in the reaction vessel or the power of the reflected wave of the high-frequency power, but when a small-scale deposition film peels off, Since the change in plasma is small, peeling of the deposited film may not be reliably detected. It is also desirable to monitor both the pressure in the reaction vessel and the power of the reflected high-frequency power in order to prevent erroneous determinations due to noise or the like. When the power of the high-frequency reflected wave and the pressure in the reaction vessel 101 suddenly change, it is determined whether the change is due to the stop of the plasma discharge or the separation of the deposited film. The termination of the plasma discharge and the separation of the deposited film can be determined as follows from the behavior of the power of the high-frequency reflected wave and the pressure in the reaction vessel. First, when the plasma discharge is stopped or the deposited film is peeled off during the formation of the deposited film, the power of the reflected wave and the pressure in the reaction vessel rise rapidly. Here, when the change is due to the stoppage of the plasma discharge, the power of the reflected wave increases, and the pressure in the reaction vessel approaches the pressure when no high-frequency power is applied. Further, once the plasma discharge is stopped, the plasma discharge is unlikely to be generated again unless a return operation is performed, and after the plasma discharge is stopped, the state in which the pressure in the reaction vessel has increased often continues. However, when the matching controller 404 automatically performs the matching adjustment, when the power of the reflected wave is increased by stopping the plasma discharge, the matching is automatically optimized to generate the plasma discharge again, The power of the reflected wave and the pressure in the reaction vessel may return to the state before the plasma discharge was stopped. When the plasma discharge becomes unstable, the plasma discharge may repeatedly stop and occur. However, regardless of the manual or automatic matching adjustment method and the state of stopping the plasma discharge, the pressure in the reaction vessel when the plasma discharge is stopped rises to near the pressure when no high-frequency power is applied, When the power of the high-frequency reflected wave and the pressure in the reaction vessel suddenly increase, if the pressure in the reaction vessel has increased to near the pressure before the application of the high-frequency power, it can be determined that the plasma discharge has stopped. On the other hand, when the deposited film is separated during the formation of the deposited film, the plasma is disturbed by the pieces of the deposited film that are peeled off and scattered, and the power of the reflected wave and the pressure in the reaction vessel rise from the steady state. . However, since the plasma discharge is often maintained at this time, the pressure in the reaction vessel rises only to a value lower than the pressure when no plasma discharge occurs, that is, when no high-frequency power is applied. do not do. When the scattering of the film pieces is stopped, the turbulence of the plasma is also stopped, so that the power of the reflected wave and the pressure in the reaction vessel return to the state before the separation of the deposited film. In this way, when the power of the reflected wave increases and the pressure in the reaction vessel rises to near the pressure where plasma discharge does not occur, it can be determined that plasma discharge has stopped, and the maximum of the increased pressure can be determined. When the value is lower than the pressure at which no plasma discharge is generated, it can be determined that peeling of the deposited film has occurred.
[0019]
After determining the stop of the plasma discharge and the separation of the deposited film, it is determined whether or not the formation of the deposited film is stopped. When the plasma discharge is stopped and the formation of the deposited film is interrupted, an interface occurs in the deposited film before and after the plasma discharge is stopped even if the formation of the deposited film is restarted. Since the characteristics are remarkably deteriorated, it is desirable that the formation of the deposited film is stopped by judging that the film formation is defective. On the other hand, when the separation of the deposited film is detected, the measurement of the power of the high-frequency reflected wave and the pressure in the reaction vessel is continued after that, rather than immediately stopping the formation of the deposited film, and the deposition such that a defective film is formed. By judging whether or not film peeling has occurred, it is possible to further improve the production yield and the utilization efficiency of the apparatus. Here, as a criterion for stopping the formation of the deposited film, it is conceivable to set a threshold value for the number of occurrences and the frequency of occurrence of the detachment of the deposited film. . For example, in the case where small-scale peeling of a deposited film occurs sporadically throughout the deposited film forming process, defective film formation can be specified by using the number of times of peeling of the deposited film as a reference. On the other hand, when peeling of a large-scale deposited film frequently occurs, a defective film formation can be determined earlier by using the frequency of occurrence of peeling of the deposited film as a reference. FIG. 3 shows a flowchart for determining a defective film formation on the basis of the number of occurrences of peeling of the deposited film. Here, when a change in the power of the reflected wave and the pressure in the reaction vessel occurs, the cumulative number of changes in the power of the reflected wave and the pressure in the reaction vessel generated up to that time are counted each time, and this is defined. When the value exceeds the value, the application of the high frequency power and the introduction of the processing gas are stopped, and the formation of the deposited film is stopped. Thus, the number of occurrences of peeling of the deposited film can be used as a criterion for defective film formation. In particular, even when small-scale peeling of the deposited film occurs sporadically, defective film formation can be accurately specified. Here, the prescribed number of times of deposition film peeling can be determined from the relationship between the number of times of deposition film peeling occurrence and the incidence rate of defective film formation in advance, and from that relationship. When the separation of the deposited film does not occur or the number of times of occurrence of the separation of the deposited film does not reach the specified number, the formation of the deposited film is performed until the timer for forming the deposited film expires. Further, when the peeling of the deposited film occurs, its scale can be known from the frequency of occurrence. FIG. 4 shows a flowchart of another example of monitoring the separation of the deposited film. In the example shown in FIG. 4, it is possible to determine a defective film formation on the basis of the frequency of occurrence of peeling of the deposited film. In other words, when a change in the power of the reflected wave and the pressure in the reaction vessel occurs, the number of occurrences of the change in the power of the reflected wave and the pressure in the reaction vessel is measured retroactively for a certain period of time. When the number of times exceeds a specified number, the formation of the deposited film is stopped. As a result, it is possible to know the frequency of occurrence of peeling of the deposited film. Can be identified. Here, the prescribed number of times of separation of the deposited film can be determined from a relationship between the number of occurrences of separation of the deposited film in a certain period of time and the occurrence rate of defective films in advance. Further, by combining these two examples, the number of occurrences of the instantaneous rise in the power of the reflected wave and the pressure in the reaction vessel or the number of occurrences of the instantaneous increase in the power of the reflected wave and the pressure in the reaction vessel measured retroactively for a certain period of time are determined. The formation of the deposited film may be stopped when the specified number of times is reached. Here, the case where the pressure in the reaction vessel is reduced due to the occurrence of the plasma discharge has been described as an example.However, in the case of a reaction system or an apparatus configuration in which the pressure inside the reaction vessel increases due to the occurrence of the plasma discharge. However, the occurrence of peeling of the deposited film and the determination of defective film formation can be determined as follows. That is, when the power of the reflected wave sharply rises and the pressure in the reaction vessel suddenly drops, the plasma discharge is stopped and the deposited film is peeled off depending on whether the pressure in the reaction vessel has decreased to near the pressure before the application of the high-frequency power. Can be determined, and a threshold value is set for the number of times and frequency of occurrence of separation of the deposited film, and the scale of separation of the deposited film can be specified.
[0020]
After the formation of the deposited film is completed or stopped, the inside of the reaction container and the inside of the gas supply device are purged using an inert gas such as argon or helium. After the purging is completed, the valve 501 is closed and the valve 506 is opened, nitrogen gas is introduced until the pressure in the reaction vessel becomes atmospheric pressure, and the produced electrophotographic photosensitive member is taken out.
[0021]
With the above-mentioned method, when the separation of a deposited film of a scale that significantly deteriorates the quality is detected, the film formation is stopped immediately and the next film formation is started, thereby improving the utilization efficiency of the apparatus. Can be done.
[0022]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited by these.
[0023]
<Experimental example 1>
An amorphous silicon photoreceptor is formed using the apparatus shown in FIGS. 1 and 2, and the number and frequency of peeling of the deposited film generated during the formation of the deposited film, and the defective film formation that is considered to be caused by the peeling of the deposited film The relationship with the percentage was determined. As the substrate to be treated, six aluminum cylinders having a length of 358 mm and a diameter of 80 mm were arranged concentrically with respect to the center of the reaction vessel. Further, the layer configuration of the photoreceptor includes a charge injection blocking layer having a function of preventing charge injection from a conductive substrate to be processed, a photoconductive layer having photoconductivity, moisture resistance, repeated use characteristics, A surface layer for the purpose of improving the pressure resistance, operating environment characteristics, and durability was sequentially laminated on the substrate. Table 1 shows the conditions for forming the deposited film.
[0024]
[Table 1]

Note that the film thickness is a target value. The high-frequency power source used had a frequency of 105 MHz. In this experimental example, the temperature of the photoconductive layer was set higher than the optimum temperature so that the deposited film was easily peeled. The formation of the deposited film was performed 50 times, and during the formation of each deposited film, the power of the reflected wave and the pressure in the reaction vessel were monitored. However, the deposited film was formed to the end irrespective of the presence or absence of the deposited film peeling and its scale, and the number of times the deposited film was peeled in each processing lot was measured. The potential characteristics and the number of image defects of the obtained electrophotographic photosensitive member were measured, and the yield of non-defective products having sufficient electrophotographic characteristics and the number of defective film-forming products considered to be caused by peeling of the deposited film were determined. Investigation was performed, and the occurrence ratio of the number of defective films considered to be caused by the peeling of the deposited film was obtained for each number of times of peeling of the deposited film generated during the formation of the deposited film.
[0025]
FIG. 5 shows an example of a temporal change in the power of the reflected wave and the pressure in the reaction vessel when the peeling of the deposited film occurs frequently. The broken line indicates the pressure in a state where no plasma discharge is generated in each layer. In this processing lot, during the formation of the photoconductive layer, the power of the reflected wave and the instantaneous rise of the pressure in the reaction vessel occur simultaneously, and thereafter, the instantaneous rise of the power of the reflected wave and the pressure in the reaction vessel occur frequently. You can see that. Further, when the pressure in the reaction vessel is increased, the pressure is lower than the pressure in a state where no plasma discharge is generated as indicated by a broken line. I understand. FIG. 6 shows the ratio of the number of defective films for each occurrence of peeling of the deposited film. As is apparent from FIG. 6, when the total number of times of occurrence of peeling of the deposited film exceeds 5, the number of defective films increases significantly. FIG. 7 shows the relationship between the maximum value of the number of times of peeling of the deposited film occurring in 30 minutes in each lot and the ratio of the number of defective films. As is clear from FIG. 7, under the conditions of the present experiment, if the deposited film is peeled off at least twice within a period of 30 minutes, the number of defective films increases significantly.
[0026]
<Example 1>
Using the apparatus shown in FIG. 1, an amorphous silicon photoreceptor was formed while monitoring the power of the high-frequency reflected wave and the pressure in the reaction vessel. The same substrate as that of Experimental Example 1 was used as the substrate to be processed. The layer configuration of the photoconductor and the conditions for forming the deposited film were the same as those in Experimental Example 1, and an amorphous silicon photoconductor was formed under conditions in which the deposited film was easily peeled off. During the formation of the deposited film, the power of the reflected wave and the pressure in the reaction vessel were monitored. In this embodiment, the formation of the deposited film was interrupted when the power of the reflected wave and the pressure in the reaction vessel simultaneously increased during the formation of the photoconductive layer, and the next deposited film was formed immediately. In Experimental Example 1, the formation of the deposited film was continued for the same time as the time required for forming the deposited film for 50 lots, and the potential characteristics and the number of image defects were measured for the obtained electrophotographic photosensitive member. The ratio of the yield of a non-defective product having sufficient quality as a photoreceptor to Experimental Example 1 was calculated.
[0027]
<Example 2>
An amorphous silicon photoreceptor was formed using the apparatus shown in FIG. 1 while monitoring the occurrence of peeling of the deposited film. The substrate to be processed was the same as that used in Experimental Example 1, and the conditions for forming the deposited film were the same as those in Experimental Example 1. During the formation of each deposited film, the power of the reflected wave and the pressure in the reaction vessel were monitored. In this example, the formation of the deposited film was stopped when the total number of times the power of the reflected wave and the pressure in the reaction vessel changed exceeded the threshold, and the next deposited film was formed immediately. The cumulative number of times of peeling of the deposited film, which is a threshold value for stopping the formation of the deposited film, was set to 5 based on the result of Experimental Example 1. With respect to the processing lot in which the deposited film was formed to the end, the potential characteristics and the number of spherical projections of the obtained electrophotographic photosensitive member were measured, and it was necessary to form the deposited film for 50 lots in Experimental Example 1. The formation of the deposited film was continued for the same time as the time, and the potential characteristics and the number of image defects were measured for the obtained electrophotographic photosensitive member, and the ratio of the yield of non-defective products having sufficient quality as the electrophotographic photosensitive member to Experimental Example 1 was determined. Calculated.
[0028]
<Example 3>
An amorphous silicon photoreceptor was formed using the apparatus shown in FIG. 1 while monitoring the occurrence of peeling of the deposited film. The substrate to be processed was the same as that used in Experimental Example 1, and the conditions for forming the deposited film were the same as those in Experimental Example 1. During the formation of each deposited film, the power of the reflected wave and the pressure in the reaction vessel were monitored. When the instantaneous change in the power of the reflected wave and the pressure in the reaction vessel occurs, the number of times of the instantaneous change in the power of the reflected wave and the pressure in the reaction vessel is measured 30 minutes from there, and the number exceeds the threshold. For the processed lot, the formation of the deposited film was stopped, and immediately the next deposited film was formed. The frequency of peeling of the deposited film, which is a threshold value for stopping the formation of the deposited film, was set to twice within 30 minutes based on the result of Experimental Example 1. With respect to the processing lot in which the deposited film was formed to the end, the potential characteristics and the number of spherical projections of the obtained electrophotographic photosensitive member were measured, and it was necessary to form the deposited film for 50 lots in Experimental Example 1. The formation of the deposited film was continued for the same time as the time, and the potential characteristics and the number of image defects were measured for the obtained electrophotographic photosensitive member, and the ratio of the yield of non-defective products having sufficient quality as the electrophotographic photosensitive member to Experimental Example 1 was determined. Calculated.
[0029]
Table 2 shows the ratio of the yield of non-defective products having sufficient electrophotographic properties, calculated in Examples 1, 2, and 3, to Experimental Example 1.
[0030]
[Table 2]

As is clear from Table 2, when the power of the high-frequency reflected wave and the pressure in the reaction vessel change, the formation of the deposited film is stopped, and immediately the next deposited film is formed. Although the yield in the reactor can be improved, the formation of the deposited film is not stopped immediately when the deposited film peels off, and the total number of times of the reflected wave power and the instantaneous rise of the pressure in the reaction vessel is regulated. When the deposition is stopped when the value is reached, the yield is further increased by preventing the deposition from being stopped due to small-scale peeling of the deposition that does not affect the quality. It can be seen that the deposited film was formed by increasing the utilization efficiency of the apparatus. When the instantaneous change in the power of the reflected wave and the pressure in the reaction vessel occurs, the number of times of the instantaneous change in the power of the reflected wave and the pressure in the reaction vessel are measured retroactively for a certain period of time, and the number is specified. When the deposition film formation is stopped after the number of times is exceeded and the next deposition film is formed immediately, the separation of the deposition film of a scale that significantly reduces the quality of the electrophotographic photosensitive member should be detected earlier. Thus, the yield in the same time can be further improved.
[0031]
【The invention's effect】
As described above, in the present invention, by monitoring the power of the high-frequency reflected wave and the pressure in the reaction vessel, it is possible to accurately determine the stop of the plasma discharge and the separation of the deposited film, and to predict the defective film formation. In some cases, the formation efficiency of the apparatus can be improved by stopping the formation of the deposited film and immediately forming the next deposited film. Further, when the deposited film peels off, a threshold value is set for the total number of times the deposited film peels off, and when the threshold value is exceeded, the formation of the deposited film is stopped and the next deposited film is formed immediately. Thereby, the utilization efficiency of the device can be further improved. Furthermore, by setting a threshold value for the frequency of separation of the deposited film when the separation of the deposited film occurs, stopping the formation of the deposited film when the threshold value is exceeded, and immediately forming the next deposited film, Further, the deposited film can be formed with an increased utilization efficiency of the apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic view of an example of a processing apparatus configured to perform a dust removing method according to the present invention.
FIG. 2 is an example of a horizontal cross-section inside a reaction vessel when the reaction vessel has a cylindrical shape.
FIG. 3 is a flowchart of an example of monitoring a stop of a plasma discharge and a peeling of a deposited film by the deposited film forming method according to the present invention.
FIG. 4 is a flowchart of another example of monitoring a stop of a plasma discharge and a separation of a deposited film by the deposited film forming method according to the present invention.
FIG. 5 is an example of a change over time in the power of the reflected wave and the pressure in the reaction vessel when the deposition film is frequently peeled off in the deposition film forming process.
FIG. 6 shows the relationship between the number of occurrences of peeling of a deposited film and the yield for each lot.
FIG. 7 shows the relationship between the maximum value of the number of times of peeling of the deposited film occurred during 30 minutes during the formation of the deposited film and the yield for each lot.
[Explanation of symbols]
100 reactor
101 reaction vessel
102 stand
103 pressure gauge
104 Substrate to be processed
105 holding member
106 heater
107 cap
108 top lid
109 exhaust port
110 gas inlet pipe
111 High frequency shield
200 exhaust system
300 gas supply device
311 to 317 Mass flow controller
321-327 Regulator
331-336 Processing gas cylinder
337 Inert gas cylinder
400 High frequency power supply
401 Matching Box
402 branch plate
403 electrode
404 Matching controller
501 valve
502 Throttle valve
503-506 valve
511-517 valves
521 to 527 valves
531-537 valves
601 Vacuum exhaust path
602 gas supply path
701 Recorder

Claims

In a deposition film forming method of introducing a processing gas into a reaction vessel, converting the processing gas into plasma by high-frequency power, and forming a deposition film on the substrate to be processed by the plasma,
Measure the change in pressure in the reaction vessel and the power of the reflected wave of the high-frequency power during the plasma processing,
When a synchronous change occurs in the power of the reflected wave of the high-frequency power and the pressure in the reaction vessel during the plasma processing, the pressure in the reaction vessel and the pressure in the reaction vessel determine whether or not this is due to the stoppage of plasma discharge. Judge by comparing the pressure without applying high frequency power,
When it is determined that the synchronous change in the power of the reflected wave of the high-frequency power and the pressure in the reaction vessel during the plasma processing is not due to the stop of the plasma discharge, the reflected wave of the high-frequency power during the plasma processing is A method for forming a deposited film, comprising: stopping plasma processing in accordance with a measurement result of power and a change in pressure in a reaction vessel.

When it is determined that the change in the power of the reflected wave of the high-frequency power and the synchronous pressure in the reaction vessel during the plasma processing is not due to the stop of the plasma discharge, the power of the reflected wave and the pressure in the reaction vessel are determined. 2. The method according to claim 1, wherein the plasma processing is stopped when the total number of occurrences of the synchronous change exceeds a specified value.

When it is determined that the synchronous change in the power of the reflected wave of the high-frequency power and the pressure in the reaction vessel during the plasma processing is not due to the stop of the plasma discharge, the power of the reflected wave and the pressure in the reaction vessel are determined. When the synchronous change occurs, the number of times the synchronous change of the reflected wave power and the pressure in the reaction vessel occurs by going back a predetermined time, and when the number exceeds a specified value. 2. The method according to claim 1, wherein the plasma treatment is stopped.