JP2012079968A

JP2012079968A - Plasma processing apparatus

Info

Publication number: JP2012079968A
Application number: JP2010224796A
Authority: JP
Inventors: Muneo Furuse; 宗雄古瀬; Ryoji Fukuyama; 良次福山; Satoyuki Tamura; 智行田村; Hiroyuki Kobayashi; 浩之小林
Original assignee: Hitachi High Technologies Corp; Hitachi High Tech Corp
Current assignee: Hitachi High Tech Corp
Priority date: 2010-10-04
Filing date: 2010-10-04
Publication date: 2012-04-19
Anticipated expiration: 2030-10-04
Also published as: JP5663259B2

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus which prevents fine foreign matters reflected by an inner wall of a vacuum vessel and a turbo molecular pump blade, etc on a flow of processing gas from being reached to a wafer on a sample holder again in order to prevent degradation of productivity of a semiconductor device caused by fine foreign matters generated in a plasma processing chamber.SOLUTION: An etching processing apparatus comprises a plasma generating device; a vacuum chamber 100 which can be depressurized; a gas supply apparatus for supplying gas into the vacuum chamber 100; a sample holder 113 for holding a wafer 128 to be plasma-processed; an apparatus for applying high frequency to the wafer 128 held on the sample holder 113; and a vacuum exhaust apparatus. The apparatus is provided with foreign matter blocking plates 201 for preventing fine foreign matters 203 generated in the apparatus from being bounced by a vacuum exhaust system and a vacuum chamber wall such as the turbo molecular pump positioned at a downstream side from the wafer 128 to be plasma-processed and from reaching to the surface of the wafer.

Description

本発明は、プラズマ処理室装置でエッチング等の加工を施す試料台上のウエハに、試料台より下流側に存在する、半導体デバイスの欠陥となり得る微小異物を、ウエハ表面まで飛散させないようにすることをその目的とし、特に微小異物起因の半導体デバイスの不良を低減することを可能とする、プラズマ処理装置に関する。 The present invention prevents the minute foreign matter existing on the downstream side of the sample table, which may be a defect of the semiconductor device, from being scattered on the wafer surface on the wafer on the sample table subjected to processing such as etching in the plasma processing chamber apparatus. In particular, the present invention relates to a plasma processing apparatus that can reduce defects in semiconductor devices caused by minute foreign matter.

従来から、半導体素子の表面にエッチング等の処理を行う手段として、半導体素子をプロセスプラズマ中で行うプラズマ処理装置が知られている。ここでは、ＥＣＲ（電子サイクロトロン共鳴）方式と呼ばれる装置を例に、従来技術を説明する。この方式では、プラズマ処理室外部より磁場を印加したプラズマ処理室中で、電磁波を利用してプラズマを発生する。磁場により電子はサイクロトロン運動し、この周波数と電磁波の周波数を共鳴させることで効率良くプラズマを発生することができる。このプラズマを用いて半導体デバイスを生産するウエハにエッチング等の処理を行う際は、半導体デバイス等の加工を施すウエハに、プロセスプラズマ中のイオンを加速して入射するために、ウエハには高周波電圧が印加される。また、ウエハにエッチング等の処理を施す際、エッチングプロセスで使用するプロセスガスには、塩素やフッ素などのハロゲン系のプロセスガスを使用することが多い。プラズマ処理装置では、プラズマ処理室の内部に導入されたプロセスガスを上記プラズマ発生手段によりプラズマ化し、ウエハ表面で反応させて微細な孔や溝などの加工、あるいは成膜などの処理を行うとともに、揮発性の反応生成物を効率良く排気することにより、所定の処理を行うものである。 2. Description of the Related Art Conventionally, as a means for performing a process such as etching on the surface of a semiconductor element, a plasma processing apparatus that performs the semiconductor element in process plasma is known. Here, the prior art will be described using an apparatus called an ECR (electron cyclotron resonance) system as an example. In this method, plasma is generated using electromagnetic waves in a plasma processing chamber to which a magnetic field is applied from the outside of the plasma processing chamber. Electrons perform cyclotron motion by a magnetic field, and plasma can be generated efficiently by resonating the frequency with the frequency of electromagnetic waves. When performing processing such as etching on wafers that produce semiconductor devices using this plasma, ions in the process plasma are accelerated and incident on the wafer to be processed, such as semiconductor devices. Is applied. In addition, when a process such as etching is performed on a wafer, a halogen-based process gas such as chlorine or fluorine is often used as a process gas used in the etching process. In the plasma processing apparatus, the process gas introduced into the plasma processing chamber is turned into plasma by the plasma generating means, and reacted on the wafer surface to perform processing such as processing of fine holes and grooves, or film formation, A predetermined treatment is performed by efficiently exhausting volatile reaction products.

このような従来のプラズマ処理装置においては、プラズマ処理に使用するプロセスプラズマで、プラズマ処理室内に配置されているアースが削られ、微小な異物が発生してしまう。また、エッチング等の処理を施す際、被エッチング材料とプロセスプラズマが反応した後に反応生成物が発生し、プラズマ処理室中に放出されることになる。反応生成物の一部は真空排気されるが、その他の反応生成物はプラズマ処理室内に堆積し、体積を増した後剥離し、プラズマ処理室内に放出される。プラズマ処理室内で発生した微小異物は、プラズマ処理室内に導入するガスの流れに沿ってプロセスガスと共に排気され、プラズマ処理室外へ取り除かれる。しかし、プラズマ処理室内で発生した微小異物の一部は、途中の真空容器壁に衝突することで方向が変わり、プロセスガスの流れに逆らい、ウエハ上まで飛散することがある。さらに、通常のプラズマ処理装置ではターボ分子ポンプを使用しているが、微小な異物はターボ分子ポンプの翼に衝突することで反射し、再びプラズマ処理室内に飛散することもある。例えば、特許文献１の特開平５−１６００７１記載の半導体製造装置では、真空ポンプの配管にポンプ側からプラズマ処理室側に微小異物が飛散しないように、壁から斜め下向きの形状で邪魔板を配置している。この実施例においては、エッチングによる反応生成物が逆流することを抑えるために、逆流防止弁やヒータを配置している。しかし、反応生成物の逆流を抑える逆流防止弁の角度等は規定されておらず、その効率等も確認できない。また、特許文献２の特開２００８−１８７０６２記載のプラズマ処理装置では、エッチングチャンバの構造自体を磁力線に対して平行とし、スパッタによる壁の削れを抑制している。さらに、エッチング等の処理を施すウエハを支持する試料台の横に邪魔板のようなアースが設置されており、アースとして作用する構造となっている。この特許の例では、試料台周りの邪魔板はアースとして作用すべく設計されており、試料台より下流側から反射する反応成生物や微小異物が、プラズマ処理室に入射することを防止することも考慮されているが、その圧力領域や微小異物の挙動に関しては考慮されていなかった。 In such a conventional plasma processing apparatus, the ground disposed in the plasma processing chamber is cut by the process plasma used for the plasma processing, and minute foreign matters are generated. Further, when a process such as etching is performed, a reaction product is generated after the material to be etched and the process plasma react with each other, and is released into the plasma processing chamber. A part of the reaction product is evacuated, but the other reaction product is deposited in the plasma processing chamber, is increased in volume, is separated, and is released into the plasma processing chamber. The minute foreign matter generated in the plasma processing chamber is exhausted together with the process gas along the flow of the gas introduced into the plasma processing chamber, and is removed outside the plasma processing chamber. However, a part of the minute foreign matter generated in the plasma processing chamber changes its direction by colliding with the vacuum vessel wall in the middle, and may be scattered on the wafer against the flow of the process gas. Further, although a turbo molecular pump is used in a normal plasma processing apparatus, a minute foreign matter is reflected by colliding with a blade of the turbo molecular pump and may be scattered again in the plasma processing chamber. For example, in the semiconductor manufacturing apparatus described in Japanese Patent Application Laid-Open No. 5-160071 of Patent Document 1, a baffle plate is arranged in a diagonally downward shape from the wall so that minute foreign matter is not scattered from the pump side to the plasma processing chamber side in the vacuum pump piping. is doing. In this embodiment, a backflow prevention valve and a heater are arranged in order to prevent the reaction product due to etching from flowing back. However, the angle or the like of the backflow prevention valve that suppresses the backflow of the reaction product is not defined, and the efficiency and the like cannot be confirmed. Further, in the plasma processing apparatus described in Japanese Patent Application Laid-Open No. 2008-187062 of Patent Document 2, the structure of the etching chamber itself is made parallel to the magnetic field lines to suppress the scraping of the wall due to sputtering. Further, an earth such as a baffle plate is installed beside the sample stage that supports the wafer to be processed such as etching, and the structure acts as an earth. In the example of this patent, the baffle plate around the sample stage is designed to act as a ground, preventing reaction products and minute foreign matter reflected from the downstream side of the sample stage from entering the plasma processing chamber. However, the pressure region and the behavior of minute foreign matter were not considered.

特開平５−１６００７１号公報JP-A-5-160071 特開２００８−１８７０６２号公報JP 2008-187062 A

プラズマ処理室内で、エッチング等の処理を行うことにより発生する反応生成物や、エッチング等のプロセスにおいて、プラズマ処理室の壁をスパッタすることにより発生する微小異物は、エッチング等で使用するプロセスガスの流れに乗って、プロセスガスと一緒に排気される。特に、エッチング等のプロセス処理時は、プラズマ処理室内の圧力が上昇し、粘性流もしくは中間流領域であるためプロセスガスと共に排気される。しかし、プラズマ処理室より排気される微小異物の一部は、真空容器内壁に衝突しプラズマ処理室内に戻ることもある。さらに、プラズマ処理室内で生成した微小異物の一部は、真空排気に用いるターボ分子ポンプの翼に衝突して反射し、プラズマ処理室内に戻ることもある。プラズマ処理室内で発生した微小異物の一部は、これらの挙動を伴うことで、プロセスガスの流れに逆行してプラズマ処理室内に戻ってしまう。その結果、プロセス処理中にプラズマ処理室内に存在する微小異物量が多くなり、エッチング等の処理を行うウエハ上にも到達してしまう。ウエハ上に飛来した微小異物は、半導体デバイスのパターン欠陥の原因となるため、製品の歩留まりが低下し、プラズマ処理装置の生産性も低下してしまう。この問題を解決するためには、スパッタ起因の壁材料を主成分とする微小異物や、ウエハにエッチング等のプラズマ処理を施すことにより発生する、反応生成物を低減させることが考えられる。しかし、プラズマ処理装置を用いて半導体デバイスを製作する上で、半導体デバイスを作成するウエハへのプラズマ処理は必須であり、プロセスプラズマを使用すればプラズマはプラズマ処理室の壁にも接触することで、壁材料は削れ微小異物が発生することになる。さらに、半導体デバイスを作成する際に、ウエハをエッチングすることにより発生する反応生成物もなくすことは困難である。 Reaction products generated by performing processing such as etching in the plasma processing chamber, and minute foreign matters generated by sputtering the walls of the plasma processing chamber in processes such as etching are the process gas used in etching and the like. Along with the flow, it is exhausted along with the process gas. In particular, during process processing such as etching, the pressure in the plasma processing chamber rises and is exhausted together with the process gas because it is a viscous flow or intermediate flow region. However, part of the minute foreign matter exhausted from the plasma processing chamber may collide with the inner wall of the vacuum chamber and return to the plasma processing chamber. Furthermore, a part of the minute foreign matter generated in the plasma processing chamber may collide with the blades of the turbo molecular pump used for evacuation and be reflected to return to the plasma processing chamber. A part of the minute foreign matter generated in the plasma processing chamber returns to the plasma processing chamber in reverse to the flow of the process gas due to these behaviors. As a result, the amount of minute foreign matter existing in the plasma processing chamber increases during the process, and reaches the wafer on which processing such as etching is performed. The minute foreign matter flying on the wafer causes a pattern defect of the semiconductor device, so that the yield of the product is lowered and the productivity of the plasma processing apparatus is also lowered. In order to solve this problem, it is conceivable to reduce the amount of reaction products that are generated by subjecting the wafer to fine foreign matters whose main component is a wall material caused by sputtering or plasma treatment such as etching on the wafer. However, when manufacturing a semiconductor device using a plasma processing apparatus, it is indispensable to perform plasma processing on the wafer on which the semiconductor device is to be created. If process plasma is used, the plasma will also contact the walls of the plasma processing chamber. As a result, the wall material is scraped and minute foreign matter is generated. Furthermore, it is difficult to eliminate reaction products generated by etching a wafer when manufacturing a semiconductor device.

半導体製造装置でプラズマを利用してエッチング等の処理を行う場合、プラズマ処理室は粘性流領域であるが、試料台とプラズマ処理室の間に異物の遮蔽板を設けると、異物の遮蔽板からターボ分子ポンプまでの間は分子流領域となる。本発明の、プラズマ処理室内のウエハを支持する試料台の下流側で、真空容器内の圧力が分子流（クヌーセン数＞１）の領域において、プラズマ処理室内で発生した微小異物の挙動に対応した異物の遮蔽板を設けることで、プラズマ処理室内で発生した微小異物が、プロセスガスのガス流れに沿って試料台より下流側に排気された後は、真空容器内壁やターボ分子ポンプの翼に衝突し、飛散することにより再びプラズマ処理室に戻ることはなくなる。その結果、エッチング等の処理を行う半導体デバイスにおいて、微小異物起因によるデバイス不良は低減する。これにより、本発明の異物の遮蔽板を設けたプラズマ処理装置を用いることで、半導体デバイスの生産性を向上するという目的を達成することが可能となる。 When processing such as etching using plasma in a semiconductor manufacturing apparatus, the plasma processing chamber is a viscous flow region, but if a foreign material shielding plate is provided between the sample stage and the plasma processing chamber, the foreign material shielding plate The region up to the turbo molecular pump is a molecular flow region. Corresponding to the behavior of minute foreign matter generated in the plasma processing chamber in the region where the pressure in the vacuum vessel is a molecular flow (Knusen number> 1) on the downstream side of the sample stage supporting the wafer in the plasma processing chamber of the present invention. By providing a shielding plate for foreign matter, after the fine foreign matter generated in the plasma processing chamber is exhausted downstream from the sample stage along the gas flow of the process gas, it collides with the inner wall of the vacuum vessel or the blades of the turbo molecular pump. However, the scattering does not return to the plasma processing chamber again. As a result, in a semiconductor device that performs processing such as etching, device defects due to minute foreign matters are reduced. Thus, the use of the plasma processing apparatus provided with the foreign material shielding plate of the present invention makes it possible to achieve the object of improving the productivity of semiconductor devices.

本発明の目的は、特にプラズマ処理室内で発生する微小異物起因による、半導体デバイスの生産性低下を防止するために、ウエハを支持する試料台より下流側の、真空容器内の圧力が分子流である領域に対応した、異物の遮蔽板を設けたものである。これにより、プロセスガスの流れに乗って異物の遮蔽板より下流側に至った微小異物は、真空容器内壁やターボ分子ポンプ翼等で反射しても、再び試料台上のウエハまで到達することはなくなる。すなわち、プラズマ処理装置のスループット向上という目的を達成するための、異物の遮蔽板を提供することが可能となる。 An object of the present invention is to prevent the pressure in the vacuum vessel on the downstream side of the sample stage supporting the wafer from being a molecular flow, in order to prevent a decrease in the productivity of the semiconductor device due to micro foreign matters generated particularly in the plasma processing chamber. A foreign material shielding plate corresponding to a certain region is provided. As a result, even if the minute foreign material that has reached the downstream side of the foreign material shielding plate in the process gas flow is reflected by the inner wall of the vacuum vessel or the turbo molecular pump blade, it will not reach the wafer on the sample table again. Disappear. That is, it is possible to provide a foreign matter shielding plate for achieving the purpose of improving the throughput of the plasma processing apparatus.

上記課題を解決するために、プラズマ処理装置で発生した微小異物が、プラズマ処理を施すウエハより下流側に位置する、真空排気装置であるターボ分子ポンプの翼や真空容器内壁で跳ね返ることで、試料台上のウエハ表面に至ることを防止する異物の遮蔽板を設置する。 In order to solve the above-mentioned problem, the minute foreign matter generated in the plasma processing apparatus rebounds from the blades of the turbo molecular pump, which is a vacuum exhaust device, or the inner wall of the vacuum vessel, which is located downstream of the wafer to be subjected to the plasma processing. A foreign material shielding plate is installed to prevent the wafer from reaching the wafer surface on the table.

プラズマ処理室内の異物の遮蔽板は、真空容器内の圧力が分子流の領域に設置し、遮蔽板を通過する磁力線に垂直となるような角度に配置されており、重力方向に対して一定の角度を持つように設計されている。異物の遮蔽板より下流側では真空容器内の圧力が分子流領域であるため、微小異物は荷電粒子と同様な挙動を示す。すなわち、分子流の領域に存在する微小異物は、磁力線の方向に沿って運動するため、異物の遮蔽板を磁力線と垂直に配置することで、真空容器内の壁やターボ分子ポンプの翼に衝突し反射する微小異物を、この異物の遮蔽板により効率的に排除することが出来る。 The shielding plate for foreign matter in the plasma processing chamber is installed in an area where the pressure in the vacuum vessel is in the molecular flow region and perpendicular to the magnetic field lines passing through the shielding plate, and is constant with respect to the direction of gravity. Designed to have an angle. Since the pressure in the vacuum vessel is in the molecular flow region on the downstream side of the foreign substance shielding plate, the minute foreign substance shows the same behavior as the charged particle. In other words, since the minute foreign matter existing in the region of the molecular flow moves along the direction of the magnetic lines of force, the foreign substance shielding plate is arranged perpendicular to the magnetic lines of force to collide with the wall inside the vacuum vessel or the blade of the turbo molecular pump. Then, the minute foreign matter that is reflected can be efficiently eliminated by the shielding plate for the foreign matter.

真空容器内の、異物の遮蔽板を通過する磁力線を制御するためには、磁場コイルに流す電流を制御することにより磁力線の方向を補正する手法や、磁場コイルで発生する磁力線を終端する磁場コイルのヨーク形状及び配置を最適に設計する手法を採用する。これらの手法を採用した結果、プラズマ処理室内で発生した微小異物が異物の遮蔽板より下流側領域に排気された場合、真空容器内壁やターボ分子ポンプ翼に衝突して真空容器上流側の方向に飛散する際も、異物の遮蔽板に進路を阻まれることで、エッチング等の処理を行うウエハ上に再び入射することはなくなる。 In order to control the magnetic lines of force that pass through the shielding plate of the foreign matter in the vacuum vessel, a method of correcting the direction of the magnetic lines of force by controlling the current flowing through the magnetic field coil, or a magnetic field coil that terminates the magnetic lines generated by the magnetic field coil A method of optimally designing the yoke shape and arrangement is adopted. As a result of adopting these methods, when the minute foreign matter generated in the plasma processing chamber is exhausted to the downstream area from the shielding plate of the foreign matter, it collides with the inner wall of the vacuum vessel or the turbo molecular pump blade and moves in the upstream direction of the vacuum vessel. Even when scattered, the path is blocked by the shielding plate for foreign matter, so that it does not enter the wafer again for processing such as etching.

プラズマ処理室内のプロセスガスを効率良く排気するためには、真空排気経路の断面積を広くすることが必要である。プロセス処理中のプラズマ処理室内では粘性流もしくは中間流の領域であり、発生した微小異物はプロセスガスの流れに沿って、異物の遮蔽板より下流側に排気されている。これまでに設置されている異物の遮蔽板は、プロセスガスの排気を効率よく行いながら、微小異物がプラズマ処理室内に入ることを防止するように設計されている。すなわち、異物の遮蔽板も含めて、真空容器全体が粘性流の領域で設計されていた。その結果、異物の遮蔽板より下流側の真空雰囲気は分子流領域であることが考慮されておらず、微小異物も荷電粒子と同様の挙動を示すことに配慮されていなかった。異物の遮蔽板とターボ分子ポンプの間との領域に存在する微小異物が、真空容器側壁やターボ分子ポンプ翼に衝突し、試料台より上流側へ飛散することを防止する場合、分子流領域の荷電粒子の動きを考慮した異物の遮蔽板としなくてはならない。 In order to efficiently exhaust the process gas in the plasma processing chamber, it is necessary to increase the cross-sectional area of the vacuum exhaust path. In the plasma processing chamber during the process processing, the region is a viscous flow or an intermediate flow, and the generated fine foreign matter is exhausted downstream of the foreign matter shielding plate along the flow of the process gas. The foreign matter shielding plates installed so far are designed to prevent minute foreign matter from entering the plasma processing chamber while efficiently exhausting the process gas. That is, the entire vacuum container including the shielding plate for foreign matter is designed in a viscous flow region. As a result, it was not considered that the vacuum atmosphere on the downstream side of the shielding plate for foreign matter is a molecular flow region, and it was not considered that minute foreign matter behaved similarly to charged particles. In order to prevent the minute foreign matter existing in the region between the foreign material shielding plate and the turbo molecular pump from colliding with the side wall of the vacuum vessel or the turbo molecular pump blade and scattering to the upstream side of the sample stage, It must be a shielding plate for foreign matter considering the movement of charged particles.

上記の問題を解決するために、分子流領域の微小異物が荷電粒子と同様の挙動であることに着目し、真空中の荷電粒子は磁力線に沿った方向に動く特性を利用した。すなわち、真空室内に設置する異物の遮蔽板で、プラズマ処理室内に微小異物の流入を防止するためには、異物の遮蔽板を、遮蔽面を通過する磁力線に対して垂直にすることが最も効果的である。また、異物の遮蔽板に磁力線を垂直に入射させるためには、磁場コイルに流す電流値の制御を行うことも重要である。さらに、磁力線の終端となるヨークの形状も制御する必要がある。異物の遮蔽板に磁力線を垂直に入射することにより、異物の遮蔽板からターボ分子ポンプに至る領域に存在する微小異物が、真空容器の壁に衝突することにより、プラズマ処理室内に至ることはなくなる。 In order to solve the above problem, attention was paid to the fact that the minute foreign matter in the molecular flow region behaved in the same manner as the charged particle, and the property that the charged particle in the vacuum moves in the direction along the magnetic field lines was used. That is, in order to prevent the entry of minute foreign matter into the plasma processing chamber by the foreign matter shielding plate installed in the vacuum chamber, it is most effective to make the foreign matter shielding plate perpendicular to the magnetic field lines passing through the shielding surface. Is. It is also important to control the value of the current flowing through the magnetic field coil so that the magnetic field lines are perpendicularly incident on the shielding plate for the foreign matter. Furthermore, it is necessary to control the shape of the yoke that is the end of the magnetic field lines. By entering the magnetic field lines perpendicularly to the foreign material shielding plate, the minute foreign material existing in the region from the foreign material shielding plate to the turbo molecular pump does not reach the plasma processing chamber by colliding with the wall of the vacuum vessel. .

本発明によれば、プラズマ処理室内で発生した微小異物が、プロセスガスによって半導体デバイスを製作するウエハを保持する試料台より下流側に配置された、異物の遮蔽板より下流側に排出された後、真空容器内壁やターボ分子ポンプ翼に反射し、再びプラズマ処理室内に侵入し、半導体デバイスを作成中の試料台上のウエハに至り、半導体デバイスの生産性を低下するようなことはなくなる。また、異物の遮蔽板の遮蔽面は、プラズマ処理室内の磁力線に垂直となるように配置するため、異物の遮蔽板からターボ分子ポンプに至る領域に存在する微小異物は、確実に異物の遮蔽板に捕捉されることが出来る。 According to the present invention, after the minute foreign matter generated in the plasma processing chamber is discharged downstream from the foreign matter shielding plate, which is arranged downstream from the sample stage holding the wafer for manufacturing the semiconductor device by the process gas. Then, it is reflected on the inner wall of the vacuum vessel and the turbo molecular pump blade, and enters the plasma processing chamber again to reach the wafer on the sample table on which the semiconductor device is being produced, and the productivity of the semiconductor device is not lowered. In addition, since the shielding surface of the foreign substance shielding plate is arranged so as to be perpendicular to the magnetic field lines in the plasma processing chamber, the minute foreign substance existing in the region from the foreign substance shielding plate to the turbo molecular pump is surely secured. Can be captured.

プラズマエッチング装置の構成図の例である。It is an example of the block diagram of a plasma etching apparatus. 異物の遮蔽板の詳細図である。It is detail drawing of the shielding plate of a foreign material. 異物の遮蔽板に入射する微小粒子のモデルである。It is a model of the microparticle which injects into the shielding plate of a foreign material.

以下、本発明の実施例を図により説明する。 Embodiments of the present invention will be described below with reference to the drawings.

本実施例では、プロセスプラズマを利用して半導体デバイスを製作する、異物の遮蔽板を有するプラズマエッチング装置の使用例を用いて説明する。 In this embodiment, a description will be given using an example of use of a plasma etching apparatus having a foreign material shielding plate for manufacturing a semiconductor device using process plasma.

図１は、本発明の実施に係るプラズマ処理装置の、構成の概略を示す縦断面図である。図中の高周波電源１１１、直流電源１１４、ＲＦ（ＲａｄｉｏＦｒｅｑｕｅｎｃｙ）バイアス電源１１７、排気ゲートプレート１１８、コンダクタンス可変バルブ１１９、排気ポンプ１２０は、それぞれ図示しないコントローラによって動作を制御されている。真空容器１００の内部には、プラズマ処理室１０１が配置され、その上部にはプラズマ処理室１０１内に電磁波を放射して電解を供給する高周波アンテナ１０８が、下部にはウエハなどの非処理対象である基板状の試料がその上面に載置される試料台１１３が備えられている。さらに真空容器１００は、プラズマ処理室１０１と、ウエハ１２８を真空容器１００内に搬送する搬送用ロボットを有する搬送室とを開放あるいは閉鎖して、両者間を連通、遮断するゲートバルブを備えている。 FIG. 1 is a longitudinal sectional view showing a schematic configuration of a plasma processing apparatus according to an embodiment of the present invention. The operation of the high-frequency power supply 111, the DC power supply 114, the RF (Radio Frequency) bias power supply 117, the exhaust gate plate 118, the conductance variable valve 119, and the exhaust pump 120 in the figure is controlled by a controller (not shown). A plasma processing chamber 101 is disposed inside the vacuum vessel 100, a high-frequency antenna 108 that radiates electromagnetic waves into the plasma processing chamber 101 and supplies electrolysis to the upper portion thereof, and a lower portion of a non-processing object such as a wafer. A sample stage 113 on which a certain substrate-like sample is placed is provided. Further, the vacuum vessel 100 is provided with a gate valve that opens or closes the plasma processing chamber 101 and a transfer chamber having a transfer robot for transferring the wafer 128 into the vacuum vessel 100 so as to communicate or block between the two. .

プラズマ処理室１０１の上部にはプロセスプラズマ１０２が形成される。また、プラズマ処理室１０１の上方には、シャワープレート１０３、石英プレート１０６、さらには高周波アンテナ１０８が配置され、高周波アンテナ１０８、プラズマ処理室１０１の側方および上方で前記プラズマ処理室１０１を囲むように配置したソレノイドコイル１１０、ソレノイドコイル１１０を囲むように設置したヨーク１０９およびアンテナ１０８の下方に配置した天井部材を備える。ソレノイドコイル１１０の上方には、アンテナ１０８に高周波を供給する、高周波電源１１１が配置されている。シャワープレート１０３の下方には、放電室内側壁部材１１２が備えられる。放電室内側壁部材１１２は、シャワープレート１０３の下面に接して配置され、真空容器１００内に生成するプラズマに面してプラズマ処理質１０１をプロセスプラズマ１０２から保護する材料で構成されている。 A process plasma 102 is formed in the upper part of the plasma processing chamber 101. A shower plate 103, a quartz plate 106, and a high-frequency antenna 108 are disposed above the plasma processing chamber 101, and surround the plasma processing chamber 101 on the side and above the high-frequency antenna 108 and the plasma processing chamber 101. The solenoid coil 110 disposed in the above, a yoke 109 installed so as to surround the solenoid coil 110, and a ceiling member disposed below the antenna 108. Above the solenoid coil 110, a high frequency power source 111 that supplies a high frequency to the antenna 108 is disposed. A discharge chamber side wall member 112 is provided below the shower plate 103. The discharge chamber side wall member 112 is disposed in contact with the lower surface of the shower plate 103 and is made of a material that faces the plasma generated in the vacuum vessel 100 and protects the plasma processing material 101 from the process plasma 102.

プラズマ処理室１０１下方にある試料台１１３は円筒形状であり、試料台１１３上面は誘電体膜に被覆されている。試料台１１３内部には、同心円状もしくは螺旋状に図示しない流路が配置されており、この流路に温調ユニット１１５により温度または流量を調節された冷媒が導入され、試料台１１３温度が調節されている。ウエハ１２８は試料台１１３上面に載置された状態で、プラズマからの入熱を受けるが、試料台１１３の温度を調節することで、試料台１１３に載置されたウエハ１２８の温度を調節する。また、試料台１１３は、ウエハ１２８を試料台１１３に静電気にて吸着させるための直流電源１１４および処理中に試料台１１３に載置されたウエハ１２８表面にイオンを加速させるためのＲＦバイアス電源１１７を備えている。 The sample stage 113 below the plasma processing chamber 101 has a cylindrical shape, and the upper surface of the sample stage 113 is covered with a dielectric film. A flow path (not shown) is concentrically or spirally arranged inside the sample stage 113, and a refrigerant whose temperature or flow rate is adjusted by the temperature control unit 115 is introduced into the flow path, and the temperature of the sample stage 113 is adjusted. Has been. While the wafer 128 is placed on the upper surface of the sample stage 113, it receives heat from the plasma. By adjusting the temperature of the sample stage 113, the temperature of the wafer 128 placed on the sample stage 113 is adjusted. . The sample stage 113 includes a DC power source 114 for adsorbing the wafer 128 to the sample stage 113 by static electricity and an RF bias power source 117 for accelerating ions on the surface of the wafer 128 placed on the sample stage 113 during processing. It has.

試料台１１３の下方には、プラズマ処理室１０１内のガスやプラズマ、反応性生成物を排気するための空間と開口部を備えている。この排出は、前記開口を開閉する排気ゲートプレート１１８、開口に連通する通路上のコンダクタンス可変バルブ１１９および排気ポンプ１２０の動作により調整される。このような、プラズマ処理装置に対して、所定の処理を施される対象のウエハ１２８は、プラズマ処理室１０１と搬送室の間の、ゲートバルブ開の状態で搬送用ロボットに載せられてプラズマ処理室１０１内に搬送され、試料台１１３上面に載置される。ウエハ１２８搬送用のロボットが、プラズマ処理室１０１の外に移動した後、プラズマ処理室１０１と搬送室の間のゲートバルブを閉鎖し、次に、直流電源１１４からの直流電圧により、試料台１１３上面の載置面上に載置されているウエハ１２８を静電気で吸着し、保持しウエハ１２８を所定の温度に制御する。 Below the sample stage 113, a space and an opening for exhausting the gas, plasma, and reactive products in the plasma processing chamber 101 are provided. This discharge is adjusted by the operation of the exhaust gate plate 118 that opens and closes the opening, the conductance variable valve 119 and the exhaust pump 120 on the passage communicating with the opening. In such a plasma processing apparatus, a wafer 128 to be subjected to predetermined processing is placed on a transfer robot with the gate valve opened between the plasma processing chamber 101 and the transfer chamber, and plasma processing is performed. The sample is transferred into the chamber 101 and placed on the upper surface of the sample stage 113. After the robot for transferring the wafer 128 moves out of the plasma processing chamber 101, the gate valve between the plasma processing chamber 101 and the transfer chamber is closed, and then the sample stage 113 is driven by the DC voltage from the DC power supply 114. The wafer 128 mounted on the upper mounting surface is attracted and held by static electricity, and the wafer 128 is controlled to a predetermined temperature.

次に、エッチング等の処理を行うためのガスがプロセスガス供給元より処理ガス供給配管を介して、シャワープレート１０３に形成された多数の孔を通してプラズマ処理室１０１内へ供給され、アンテナ１０８およびソレノイドコイル１１０から供給される電界、磁界により処理ガスがプラズマ化し、プロセスプラズマ１０２としてウエハ１２８上方に形成される。さらに、ＲＦバイアス電源１１７により、試料台１１３に高周波電力が印加され、ウエハ１２８上面上方に形成されたＲＦバイアスによるバイアス電位とプラズマ電位との電位差によりプラズマ中のイオンをウエハ１２８上に引き込み、エッチング等の反応をアシストしつつ、エッチング等のプラズマ処理が開始される。プラズマ処理の終了後、プラズマおよびＲＦバイアスの供給電源が停止され、直流電源１１４からの直流電圧の供給も停止され、静電気力が低下し、ウエハ１２８は除去される。その後、プラズマ処理室１０１と搬送室の間のゲートバルブを開き、搬送用ロボットにより処理済のウエハ１２８をプラズマ処理室１０１外に搬出し、搬出終了後、ゲートバルブを再び閉鎖する。 Next, a gas for performing processing such as etching is supplied into the plasma processing chamber 101 from a process gas supply source through a processing gas supply pipe through a large number of holes formed in the shower plate 103, and the antenna 108 and solenoid The processing gas is turned into plasma by the electric field and magnetic field supplied from the coil 110 and formed as process plasma 102 above the wafer 128. Further, RF power is applied to the sample stage 113 by the RF bias power source 117, and ions in the plasma are drawn onto the wafer 128 due to the potential difference between the bias potential due to the RF bias formed above the upper surface of the wafer 128 and the plasma potential, and etching is performed. The plasma processing such as etching is started while assisting the reaction. After the plasma processing is completed, the plasma and RF bias supply power is stopped, the DC voltage supply from the DC power supply 114 is also stopped, the electrostatic force is reduced, and the wafer 128 is removed. Thereafter, the gate valve between the plasma processing chamber 101 and the transfer chamber is opened, the processed wafer 128 is unloaded from the plasma processing chamber 101 by the transfer robot, and after the unloading is completed, the gate valve is closed again.

次に、本実施例の要部である、試料台１１３とプラズマ処理室１０１の間に配置する、プラズマ処理室１０１内で発生した微小異物を低減するための、異物の遮蔽板２０１について説明する。本実施例では、異物の遮蔽板２０１の傾きは、ソレノイドコイル１１０およびヨーク１０９により、プラズマ処理室１０１内に形成される磁力線２０２にほぼ垂直（微小異物の入射角度が１０度以下）な向きとなるように設計されている。プラズマ処理室１０１内は粘性流もしくは中間流領域であるため、プラズマ処理室１０１内の微小異物は、ソレノイドコイル１１０およびヨーク１０９により形成される磁力線２０２が、真空容器１００内にある異物の遮蔽板２０１に垂直であっても並行であっても、プロセスガスの流れに沿って移動し、異物の遮蔽板２０１より下流側に排気される。 Next, a foreign matter shielding plate 201, which is a main part of the present embodiment and is arranged between the sample stage 113 and the plasma processing chamber 101 to reduce minute foreign matters generated in the plasma processing chamber 101, will be described. . In this embodiment, the inclination of the foreign matter shielding plate 201 is oriented substantially perpendicular to the magnetic lines of force 202 formed in the plasma processing chamber 101 by the solenoid coil 110 and the yoke 109 (the incident angle of minute foreign matters is 10 degrees or less). Designed to be Since the inside of the plasma processing chamber 101 is a viscous flow or intermediate flow region, a minute foreign matter in the plasma processing chamber 101 is a foreign matter shielding plate in which the magnetic lines of force 202 formed by the solenoid coil 110 and the yoke 109 are in the vacuum vessel 100. It moves along the flow of the process gas whether it is perpendicular or parallel to 201 and is exhausted downstream from the shielding plate 201 for foreign matter.

プラズマ処理室１０１から真空容器１００側に移動した微小異物は、異物の遮蔽板２０１より下流では分子流領域であり、微小異物は荷電粒子と同じ挙動を示すため、壁やターボ分子ポンプの翼に衝突した場合、上流側のプラズマ処理室１０１に向かうものも存在するが、この分子流領域では処理室内を通る磁力線２０２に拘束される。微小異物は磁力線２０２に拘束されて移動するため、異物の遮蔽板２０１の表面を、この遮蔽面を通る磁力線２０２が垂直となるように配置すれば、異物の遮蔽板２０１とターボ分子ポンプの間に存在する微小異物を効率良く捕集し、プラズマ処理室１０１内に入らないようにすることが出来る。異物の遮蔽板２０１に磁力線２０２が直行して入射しない場合は、ソレノイドコイル１１０の電流値を制御することや、ソレノイドコイルの周りに設けられているヨーク１０９の形状を変更することで対応することが可能である。 The minute foreign matter moved from the plasma processing chamber 101 to the vacuum vessel 100 side is a molecular flow region downstream of the foreign matter shielding plate 201, and the minute foreign matter exhibits the same behavior as a charged particle. In the case of a collision, there are those that go to the plasma processing chamber 101 on the upstream side, but in this molecular flow region, they are restrained by the lines of magnetic force 202 passing through the processing chamber. Since the minute foreign matter moves while being restrained by the magnetic force line 202, if the surface of the foreign matter shielding plate 201 is arranged so that the magnetic force line 202 passing through the shielding surface is vertical, the foreign matter shielding plate 201 and the turbo molecular pump are disposed. It is possible to efficiently collect the minute foreign substances existing in the plasma processing chamber 101 so as not to enter the plasma processing chamber 101. When the magnetic force line 202 does not enter the foreign matter shielding plate 201 directly, it can be dealt with by controlling the current value of the solenoid coil 110 or changing the shape of the yoke 109 provided around the solenoid coil. Is possible.

図２は、図１の実施例において、異物の遮蔽板２０１を磁力線２０２に垂直となるように配置した例を拡大した断面図である。分子流領域で微小異物を捕獲するためには、異物の遮蔽板２０１の表面を荒れた状態にすることや、表面を冷却することで、一旦入射した微小異物が再び放出されることを防止することが可能となる。異物の遮蔽板２０１の表面に凹凸を付けて荒らす場合、溶射処理等を行うことで対応が出来る。上記手法を用いて半導体エッチング装置の、異物の遮蔽板２０１の表面を処理することで、一旦捕捉された微小異物が再び脱離することは無いと考えられる FIG. 2 is an enlarged cross-sectional view of an example in which the foreign substance shielding plate 201 is arranged so as to be perpendicular to the magnetic force lines 202 in the embodiment of FIG. In order to capture minute foreign matters in the molecular flow region, the surface of the foreign matter shielding plate 201 is roughened or the surface is cooled to prevent the once entered fine foreign matter from being released again. It becomes possible. When the surface of the foreign material shielding plate 201 is roughened and roughened, it can be dealt with by performing a thermal spraying process or the like. By treating the surface of the foreign matter shielding plate 201 of the semiconductor etching apparatus using the above method, it is considered that the fine foreign matter once captured will not be detached again.

図３は、図２の異物の遮蔽板２０１に入射する微小粒子のモデルである。分子流領域では、微小異物２０３が荷電粒子と同様の挙動を示すため、異物の遮蔽板２０１をその場の磁力線２０２の向きに対して垂直に配置することで、微小異物２０３の捕集を効率良く行うことが出来る。また、異物の遮蔽板２０１より上流側では、微小異物２０３は磁力線２０２に拘束されることはなく、ガス流れに沿って下流側に排気されることになる。 FIG. 3 is a model of fine particles incident on the foreign material shielding plate 201 of FIG. In the molecular flow region, the minute foreign matter 203 behaves in the same manner as a charged particle. Therefore, the foreign matter 203 can be efficiently collected by arranging the foreign matter shielding plate 201 perpendicular to the direction of the magnetic field lines 202 in the field. Can be done well. Further, on the upstream side of the foreign matter shielding plate 201, the minute foreign matter 203 is not restrained by the magnetic lines of force 202 and is exhausted downstream along the gas flow.

１００真空容器
１０１プラズマ処理室
１０２プロセスプラズマ
１０３シャワープレート
１０６石英プレート
１０８高周波アンテナ
１０９ヨーク
１１０ソレノイドコイル
１１１高周波電源
１１２放電室内側壁
１１３試料台
１１４直流電源
１１５温調ユニット
１１７ＲＦバイアス電源
１１８排気ゲートプレート
１１９コンダクタンス可変バルブ
１２０排気ポンプ
１２８ウエハ
１２９処理室底面
２０１異物の遮蔽板
２０２磁力線
２０３微小異物 100 Vacuum vessel 101 Plasma processing chamber 102 Process plasma 103 Shower plate 106 Quartz plate 108 High frequency antenna 109 Yoke 110 Solenoid coil 111 High frequency power source 112 Discharge chamber side wall 113 Sample stage 114 DC power source 115 Temperature control unit 117 RF bias power source 118 Exhaust gate plate 119 Conductance variable valve 120 Exhaust pump 128 Wafer 129 Processing chamber bottom surface 201 Foreign matter shielding plate 202 Magnetic field line 203 Small foreign matter

Claims

A plasma generator, a depressurizable vacuum vessel, a gas supply device for supplying gas to the vacuum vessel, a sample stage for holding a wafer to be subjected to plasma processing, and an apparatus for applying a high frequency to the wafer supported on the sample stage And, in the etching processing apparatus consisting of a vacuum exhaust device, the minute foreign matter generated in the apparatus bounces off in the vacuum exhaust system such as a turbo molecular pump or the plasma processing chamber wall located downstream from the wafer to be subjected to plasma processing, A plasma processing apparatus, comprising a shielding plate for foreign matter to prevent reaching the wafer surface.

2. The plasma processing apparatus according to claim 1, wherein a foreign substance shielding plate is installed downstream of the sample stage, a molecular flow region is formed downstream of the shielding plate, and an incident angle of the foreign matter existing in the molecular flow region is 10 degrees. The plasma processing apparatus characterized in that the direction of the surface of the shielding plate is perpendicular to the direction of the lines of magnetic force so as to satisfy the following conditions.

3. The plasma processing apparatus according to claim 2, wherein an angle of the shielding plate for the foreign matter is perpendicular to a direction of a magnetic force line at a central position of the shielding plate for the foreign matter, and shields at least two foreign matters. A plasma processing apparatus comprising a plate.

4. The plasma processing apparatus according to claim 3, wherein the foreign material shielding plate is made of a material resistant to a halogen-based process plasma.

5. The plasma processing apparatus according to claim 4, wherein the foreign material shielding plate is made of quartz such as SiO2 (quartz), Al2O3 (alumina ceramics), SiC (silicon carbide), Y2O3 (yttria), Gd2O3, Yb2O3, or the like. A plasma processing apparatus comprising a sintered body.

5. The plasma processing apparatus according to claim 4, wherein when a material such as stainless steel, an aluminum alloy, or a titanium alloy is used as the material used for the shielding plate for the foreign matter, the surface is plasma resistant such as a sprayed coating or an anodized coating. A plasma processing apparatus which is coated with a material having properties.

4. The plasma processing apparatus according to claim 3, wherein a magnetic field coil for correcting the direction of the magnetic force lines is provided in the foreign matter shielding plate, and the direction of the magnetic force lines is controlled to change the direction of the surface of the foreign matter shielding plate to the direction of the magnetic force lines. A plasma processing apparatus characterized by being perpendicular to the surface.

4. The plasma processing apparatus according to claim 3, wherein the foreign matter shielding plate is provided with a yoke for correcting the direction of magnetic force lines, and the direction of the magnetic force lines is controlled so that the direction of the surface of the foreign matter shielding plate is relative to the direction of the magnetic force lines. A plasma processing apparatus characterized by being vertical.