JP4666744B2 - Measuring apparatus, exposure apparatus, and device manufacturing method - Google Patents

Description

【００４３】
【数２】

【００４４】
Ｓの求め方は、例えば、信号ＳＲＹ１からＲＹ１マークの中心位置をラフに検出しＲＹ１Ｃを求め、その位置からＲＹ１Ｃ−Ｎ／２画素移動した位置をＳとする。
【００４５】
次に、ｅｖｅｎ画素とｏｄｄ画素の照度補正を説明する。ｅｖｅｎ画素とｏｄｄ画素の照度補正は、暗いほうの画素を明るいほうの画素に合わせる、または逆に明るいほうの画素を暗いほうに合わせる、もしくは平均値に合わせてもよい。ここでは、明るいほうに合わせる例を示す。上の式で求まっているＥｓとＯｓを用いて
【００４６】
【数３】

【００４７】
上の演算を行うと、ｅｖｅｎ画素が明るい場合ｏｄｄ画素を明るくし、その係数をＫｏとする。全てのｏｄｄ画素にＫｏを乗じ明るさの補正を行う。また、ｏｄｄ画素が明るい場合、全てのｅｖｅｎ画素にＫｅを乗じ明るさの補正を行う。こうして、補正された信号が図１（ｃ）に示される信号ＳＲＹ１’である。図１（ｂ）に比べるとなめらかな信号となる。
【００４８】
上記係数Ｋｏ、Ｋｅは、ウインドウＷＷＹおよびＷＲＹ２を投影処理して作製された信号に対しても用いることが可能で、それぞれの信号でｅｖｅｎ／ｏｄｄ画素の明るさ補正が行われる。
【００４９】
このようにしてｅｖｅｎ／ｏｄｄ画素の照度差が補正された信号を用いて、レチクルプレートのマーク位置、ステージプレートのマーク位置を求めると、照度に左右されない計測結果が得られる。また、光量の計測および信号コントラストの計測においても、同じように処理を行ってから例えばＳＲＹ１’信号の最大値からマークの光量を、ＳＲＹ１’の微分値からコントラストを求める。
【００５０】
本実施例では本発明の特徴とする補正を投影された信号に対して行ったが、取込まれた画像全体に対して行っても構わない。その場合、式４は以下のように拡張される。
【００５１】
【数４】

【００５２】
式４では、上の演算を行うと、ｅｖｅｎフィールドが明るい場合ｏｄｄフィールドを明るくし、その係数をＫｏとする。全てのｏｄｄフィールドの画素にＫｏを乗じ明るさの補正を行う。また、ｏｄｄフィールドが明るい場合、全てのｅｖｅｎフィールドの画素にＫｅを乗じ明るさの補正を行う。
【００５３】
本実施例ではｅｖｅｎ／ｏｄｄフィールドの明るさの測定に計測マークを用いて行ったが、図１（ａ）のＬＭに示される均一な反射面で構成される専用マークを撮像してｅｖｅｎ／ｏｄｄフィールドの明るさを測定しても構わない。専用マークは視野内でマーク計測に影響しない範囲に存在していればよい。専用マークの配置は、ステージ基準マーク３の側でも、レチクル側マーク１０上でも構わない。専用マークにするとマーク位置を求める必要が無くなる。専用マークでのｅｖｅｎ／ｏｄｄフィールドの明るさの測定は次式で行う。
【００５４】
【数５】

【００５５】
式５と６で求められたＥｓとＯｓならびに式３および式４を用いて１次元信号または２次元画像の補正を行う。
【００５６】
なお、本実施例は照明装置としてパルス状の光を発生する装置を用いた例について説明した。それは、時間的な照度変化が大きいからである。しかし、連続発光している照明装置でも時間的な照度変化が発生している場合、本補正方法および計測方法は有効である。例えば、放電型のランプ等では時間的な照度変化は発生する。
【００５７】
＜半導体生産システムの実施例＞
次に、半導体デバイス（ＩＣやＬＳＩ等の半導体チップ、液晶パネル、ＣＣＤ、薄膜磁気ヘッド、マイクロマシン等）の生産システムの例を説明する。これは半導体製造工場に設置された製造装置のトラブル対応や定期メンテナンス、あるいはソフトウェア提供などの保守サービスを、製造工場外のコンピュータネットワークを利用して行うものである。
【００５８】
図６は全体システムをある角度から切り出して表現したものである。図中、１０１は半導体デバイスの製造装置を提供するベンダー（装置供給メーカー）の事業所である。製造装置の実例として、半導体製造工場で使用する各種プロセス用の半導体製造装置、例えば、前工程用機器（露光装置、レジスト処理装置、エッチング装置等のリソグラフィ装置、熱処理装置、成膜装置、平坦化装置等）や後工程用機器（組立て装置、検査装置等）を想定している。事業所１０１内には、製造装置の保守データベースを提供するホスト管理システム１０８、複数の操作端末コンピュータ１１０、これらを結んでイントラネットを構築するローカルエリアネットワーク（ＬＡＮ）１０９を備える。ホスト管理システム１０８は、ＬＡＮ１０９を事業所の外部ネットワークであるインターネット１０５に接続するためのゲートウェイと、外部からのアクセスを制限するセキュリティ機能を備える。
【００５９】
一方、１０２〜１０４は、製造装置のユーザーとしての半導体装置メーカーの製造工場である。製造工場１０２〜１０４は、互いに異なるメーカーに属する工場であっても良いし、同一のメーカーに属する工場（例えば、前工程用の工場、後工程用の工場等）であっても良い。各工場１０２〜１０４内には、夫々、複数の製造装置１０６と、それらを結んでイントラネットを構築するローカルエリアネットワーク（ＬＡＮ）１１１と、各製造装置１０６の稼動状況を監視する監視装置としてホスト管理システム１０７とが設けられている。各工場１０２〜１０４に設けられたホスト管理システム１０７は、各工場内のＬＡＮ１１１を工場の外部ネットワークであるインターネット１０５に接続するためのゲートウェイを備える。これにより各工場のＬＡＮ１１１からインターネット１０５を介してベンダー１０１側のホスト管理システム１０８にアクセスが可能となり、ホスト管理システム１０８のセキュリティ機能によって限られたユーザーだけがアクセスが許可となっている。具体的には、インターネット１０５を介して、各製造装置１０６の稼動状況を示すステータス情報（例えば、トラブルが発生した製造装置の症状）を工場側からベンダー側に通知する他、その通知に対応する応答情報（例えば、トラブルに対する対処方法を指示する情報、対処用のソフトウェアやデータ）や、最新のソフトウェア、ヘルプ情報などの保守情報をベンダー側から受け取ることができる。各工場１０２〜１０４とベンダー１０１との間のデータ通信および各工場内のＬＡＮ１１１でのデータ通信には、インターネットで一般的に使用されている通信プロトコル（ＴＣＰ／ＩＰ）が使用される。なお、工場外の外部ネットワークとしてインターネットを利用する代わりに、第三者からのアクセスができずにセキュリティの高い専用線ネットワーク（ＩＳＤＮなど）を利用することもできる。また、ホスト管理システムはベンダーが提供するものに限らずユーザーがデータベースを構築して外部ネットワーク上に置き、ユーザーの複数の工場から該データベースへのアクセスを許可するようにしてもよい。
【００６０】
さて、図７は本実施例の全体システムを図６とは別の角度から切り出して表現した概念図である。先の例ではそれぞれが製造装置を備えた複数のユーザー工場と、該製造装置のベンダーの管理システムとを外部ネットワークで接続して、該外部ネットワークを介して各工場の生産管理や少なくとも１台の製造装置の情報をデータ通信するものであった。これに対し本例は、複数のベンダーの製造装置を備えた工場と、該複数の製造装置のそれぞれのベンダーの管理システムとを工場外の外部ネットワークで接続して、各製造装置の保守情報をデータ通信するものである。図中、２０１は製造装置ユーザー（半導体デバイス製造メーカー）の製造工場であり、工場の製造ラインには各種プロセスを行う製造装置、ここでは例として露光装置２０２、レジスト処理装置２０３、成膜処理装置２０４が導入されている。なお図７では製造工場２０１は１つだけ描いているが、実際は複数の工場が同様にネットワーク化されている。工場内の各装置はＬＡＮ２０６で接続されてイントラネットを構成し、ホスト管理システム２０５で製造ラインの稼動管理がされている。一方、露光装置メーカー２１０、レジスト処理装置メーカー２２０、成膜装置メーカー２３０などベンダー（装置供給メーカー）の各事業所には、それぞれ供給した機器の遠隔保守を行うためのホスト管理システム２１１、２２１、２３１を備え、これらは上述したように保守データベースと外部ネットワークのゲートウェイを備える。ユーザーの製造工場内の各装置を管理するホスト管理システム２０５と、各装置のベンダーの管理システム２１１、２２１、２３１とは、外部ネットワーク２００であるインターネットもしくは専用線ネットワークによって接続されている。このシステムにおいて、製造ラインの一連の製造機器の中のどれかにトラブルが起きると、製造ラインの稼動が休止してしまうが、トラブルが起きた機器のベンダーからインターネット２００を介した遠隔保守を受けることで迅速な対応が可能で、製造ラインの休止を最小限に抑えることができる。
【００６１】
半導体製造工場に設置された各製造装置はそれぞれ、ディスプレイと、ネットワークインターフェースと、記憶装置にストアされたネットワークアクセス用ソフトウェアならびに装置動作用のソフトウェアを実行するコンピュータを備える。記憶装置としては内蔵メモリやハードディスク、あるいはネットワークファイルサーバーなどである。上記ネットワークアクセス用ソフトウェアは、専用または汎用のウェブブラウザを含み、例えば図８に一例を示す様な画面のユーザーインターフェースをディスプレイ上に提供する。各工場で製造装置を管理するオペレータは、画面を参照しながら、製造装置の機種（４０１）、シリアルナンバー（４０２）、トラブルの件名（４０３）、発生日（４０４）、緊急度（４０５）、症状（４０６）、対処法（４０７）、経過（４０８）等の情報を画面上の入力項目に入力する。入力された情報はインターネットを介して保守データベースに送信され、その結果の適切な保守情報が保守データベースから返信されディスプレイ上に提示される。またウェブブラウザが提供するユーザーインターフェースはさらに図示のごとくハイパーリンク機能（４１０〜４１２）を実現し、オペレータは各項目の更に詳細な情報にアクセスしたり、ベンダーが提供するソフトウェアライブラリから製造装置に使用する最新バージョンのソフトウェアを引出したり、工場のオペレータの参考に供する操作ガイド（ヘルプ情報）を引出したりすることができる。ここで、保守データベースが提供する保守情報には、上記説明したマーク画像データのｅｖｅｎフィールド（または画素）とｏｄｄフィールド（または画素）の照度偏差の補正に関する情報も含まれ、また前記ソフトウェアライブラリはその補正を含むマーク計測を実現するための最新のソフトウェアも提供する。
【００６２】
次に上記説明した生産システムを利用した半導体デバイスの製造プロセスを説明する。図９は半導体デバイスの全体的な製造プロセスのフローを示す。ステップ１（回路設計）では半導体デバイスの回路設計を行う。ステップ２（マスク製作）では設計した回路パターンを形成したマスクを製作する。一方、ステップ３（ウエハ製造）ではシリコン等の材料を用いてウエハを製造する。ステップ４（ウエハプロセス）は前工程と呼ばれ、上記用意したマスクとウエハを用いて、リソグラフィ技術によってウエハ上に実際の回路を形成する。次のステップ５（組立て）は後工程と呼ばれ、ステップ４によって作製されたウエハを用いて半導体チップ化する工程であり、アッセンブリ工程（ダイシング、ボンディング）、パッケージング工程（チップ封入）等の組立て工程を含む。ステップ６（検査）ではステップ５で作製された半導体デバイスの動作確認テスト、耐久性テスト等の検査を行う。こうした工程を経て半導体デバイスが完成し、これを出荷（ステップ７）する。前工程と後工程はそれぞれ専用の別の工場で行い、これらの工場毎に上記説明した遠隔保守システムによって保守がなされる。また前工程工場と後工程工場との間でも、インターネットまたは専用線ネットワークを介して生産管理や装置保守のための情報がデータ通信される。
【００６３】
図１０は上記ウエハプロセスの詳細なフローを示す。ステップ１１（酸化）ではウエハの表面を酸化させる。ステップ１２（ＣＶＤ）ではウエハ表面に絶縁膜を成膜する。ステップ１３（電極形成）ではウエハ上に電極を蒸着によって形成する。ステップ１４（イオン打込み）ではウエハにイオンを打ち込む。ステップ１５（レジスト処理）ではウエハに感光剤を塗布する。ステップ１６（露光）では上記説明した露光装置によってマスクの回路パターンをウエハに焼付露光する。ステップ１７（現像）では露光したウエハを現像する。ステップ１８（エッチング）では現像したレジスト像以外の部分を削り取る。ステップ１９（レジスト剥離）ではエッチングが済んで不要となったレジストを取り除く。これらのステップを繰り返し行うことによって、ウエハ上に多重に回路パターンを形成する。各工程で使用する製造機器は上記説明した遠隔保守システムによって保守がなされているので、トラブルを未然に防ぐと共に、もしトラブルが発生しても迅速な復旧が可能で、従来に比べて半導体デバイスの生産性を向上させることができる。
【００６４】
【発明の効果】
本発明によると、インターレース方式の蓄積型エリアセンサで撮像したマークの位置を計測する精度の点で有利な計測装置を提供することができる。
【図面の簡単な説明】
【図１】 本発明の一実施例を説明する図である。
【図２】 本発明の適用対象の一例である半導体製造装置の構成図である。
【図３】 揺動手段とレーザ発光および画像蓄積のタイミングを説明する図である。
【図４】 インターレース方式の画像取り込みを示す図である。
【図５】 レーザのパルスエネルギーのバラツキを示す図である。
【図６】 半導体デバイスの生産システムをある角度から見た概念図である。
【図７】 半導体デバイスの生産システムを別の角度から見た概念図である。
【図８】 ユーザーインターフェースの具体例である。
【図９】 デバイスの製造プロセスのフローを説明する図である。
【図１０】 ウエハプロセスを説明する図である。
【符号の説明】
１：レチクル（レチクル基準プレート）、２：投影レンズ、３：ステージ基準プレート、７：揺動手段、８：ＣＣＤカメラ、１２：画像加算装置、１３：同期信号発生器、１４：画像処理装置、１５：エキシマレーザ（パルスレーザ）、１６：露光装置制御装置、１７：揺動制御装置、１８：ステージ制御装置、１９：干渉計。[0001]
BACKGROUND OF THE INVENTION
  The present invention captures images with an interlaced storage area sensor.ThemarkPosition ofMeasureAbout measuring equipment.
[0002]
[Prior art]
In a semiconductor manufacturing apparatus that manufactures a high-density memory or a high-spec CPU, a required exposure resolution is 0.20 μm or less. Therefore, in order to transfer a finer pattern, KrF laser (248 nm), ArF laser (193 nm), and further F2 laser (157 nm) are used as exposure light sources. On the other hand, as a part of the alignment method of the semiconductor manufacturing apparatus, it is necessary to precisely measure the position of the reticle or the position of the reticle stage on which the reticle is set and the positional relationship of the wafer stage. The most advantageous method for measuring the positional relationship between the reticle stage and the wafer stage is TTR measurement in which the reticle stage and the wafer stage are measured simultaneously. In the TTR measurement, a mark on the reticle stage and a mark position on the wafer stage are measured via a projection lens existing between the reticle stage and the wafer stage. The illumination light source used for TTR measurement is optimally exposure light. The reason is that the aberration (chromatic aberration, etc.) of the projection lens is matched to the exposure light. As a result, the mark on the reticle stage and the mark on the wafer stage existing at conjugate positions can be measured simultaneously.
[0003]
By the way, excimer lasers or the like are mainly used as illumination devices for semiconductor manufacturing apparatuses that can emit light having a short wavelength with high energy. The light generation method of the excimer laser is pulse emission.
[0004]
An apparatus for capturing images of a mark on a reticle and a wafer stage that is illuminated by pulsed laser light is devised as disclosed in Japanese Patent Application Laid-Open Nos. 3-226187 and 4-26011. The outline is shown below.
[0005]
1) Suppress the unevenness of the laser illuminance by the swinging means in the lighting device.
2) The laser is synchronized with the video synchronization signal input to the image capturing device, and the laser is controlled so that the number of pulses during light accumulation is the same.
3) Accumulate the captured electrical signals to reduce uneven illumination.
4) Synchronize the period of the rocking means with the period of image capture.
Using these methods, an image with little illuminance unevenness was created.
[0006]
FIG. 2 shows a configuration of a semiconductor manufacturing apparatus which is a conventional example and is an example of an application target of the present invention. In the apparatus shown in the figure, the light of the pulse laser 15 is averaged by a swinging means 7 such as a wedge, the mark 3 on the stage is illuminated through the projection lens 2, and the reflected light from the mark is passed through the projection lens 2 to the CCD camera 8. Take an image with. The synchronization signal of the CCD camera 8 is output from the synchronization signal generator 13. The synchronization signal is also sent to the rocking means 7 and the laser 15 at the same time, and the CCD camera 8, the rocking means 7 and the laser 15 are synchronized.
[0007]
Since the CCD camera 8 is an NTSC system, as shown in FIG. 4, the CCD camera 8 accumulates light by being divided in time at even / odd timing. The output image is composed of an even scanning line image and an odd scanning line image, and the even / odd images are captured with a time lag.
[0008]
FIG. 3 shows the relationship between image capture and laser pulse emission. The oscillation period is adjusted to be a period that is an integral multiple of the even / odd field. In the conventional example, the accumulated image data is integrated by the image adder 12 in FIG. 2, and in the case of FIG. 3, the images of 3 to 6 frames are synthesized to produce a measurement image.
[0009]
[Problems to be solved by the invention]
Since the scanning exposure by the pulse laser has been performed, it has become necessary for the swinging means to synchronize with the scanning speed. That is, in the scanning exposure, the resist of the wafer is irradiated with the light of the pulse laser as if the slit is scanning the wafer. In order to perform exposure without illuminance unevenness in the scan area, pulse light of one period or n periods (n: natural number) of the swinging means must be exposed while a point on the wafer moves the slit width. Don't be. For this reason, it is necessary to increase the oscillation frequency of the oscillation means as the scanning speed increases. On the other hand, the scan speed is inversely proportional to the amount of energy for exposing the resist on the wafer. To increase the amount of energy, more laser pulses are required. Since the oscillation frequency of the laser is fixed (usually the maximum value), increasing the exposure energy amount is achieved by reducing the scanning speed. As described above, the oscillation frequency of the oscillation means must be changed depending on the scan speed (exposure amount).
[0010]
On the other hand, when pulse light is accumulated with an NTSC CCD camera, the exposure time is limited to 1/60 seconds. In order to ensure that there is no uneven illuminance and an even / odd difference does not occur in an interlaced imaging that is time-divided into even / odd unique to NTSC and has a limited accumulation time, the swinging means 1 / Must be an integer multiple of 60 seconds.
[0011]
Although there is an optimal oscillation frequency depending on the scan speed, the oscillation frequency is adjusted for measurement every time measurement of the oscillation means is controlled. To change the speed of an object moving at high speed, a control time of about several seconds is usually required. In order to reduce this time to a few milliseconds, a high-performance control means must be used. On the other hand, if there is a measurement-specific oscillation means, it is not necessary to change the oscillation frequency. However, in this case, the problem is that the illuminating device is enlarged and the optical member is required twice. In addition, a part of the light must be guided to the measurement-dedicated optical system, and in the worst case, the illuminance for pattern exposure may be reduced. Therefore, it is most suitable to use a part of the illumination system of the scan exposure system without making a dedicated optical system.
[0012]
TTR measurement is used for stage position and reticle position calibration, projection lens calibration, and the like. Measurement is performed during wafer exchange. This is because if the measurement is completed in parallel with the wafer exchange, the wafer processing time is not increased. However, in recent exposure apparatuses, the wafer exchange time is minimized and the throughput (wafer processing capacity per unit time) is increased. Due to the measurement performed at the time of wafer exchange, the time until the swinging unit is stabilized is wasted time of the apparatus.
[0013]
In the conventional system, the swinging means has to be controlled to capture an image for measurement, which has a problem of affecting the throughput of the apparatus.
[0014]
As an image capturing device, if the camera of the type that performs even / odd field light accumulation at different times and synthesizes the even / odd field images to create one image, as in the NTSC system, between the even / odd fields is used. A difference in brightness (illuminance difference) may occur. The cause of the difference in illuminance is
1) Error in laser energy between the even field accumulation period and odd field accumulation period (particularly, the amount of laser energy at the first pulse of light emission start is higher).
2) Unevenness of rocking means
Is mentioned.
[0015]
The above 1) will be supplemented with reference to FIG. FIG. 5 shows time on the horizontal axis and the amount of laser energy on the vertical axis. The section surrounded by the arrow at the top of the graph indicates the light accumulation period of the even / odd field. The even / odd capture time is switched every 16.6 msec. The amount of laser energy is high in the initial four pulses at the start of laser emission, and gradually stabilizes. In the case of FIG. 5, the amount of light entering the even field is higher than the amount of light entering the odd field. Accordingly, the even field image is brighter than the odd field. This phenomenon does not pose a problem when light is emitted continuously, but becomes prominent when it oscillates intermittently after several seconds. As described above, TTR measurement is performed at a timing at which the wafer is not directly exposed, such as during wafer replacement. Usually the laser stops for a few seconds. Therefore, this phenomenon must be taken into account in measurement using laser light.
[0016]
An adverse effect due to the difference in illuminance is that the measurement accuracy of the captured image is deteriorated. For example, in the measurement in which the defocus amount is quantified based on the contrast of the captured signal, the measurement cannot be accurately performed unless the light amount is constant. This is because the contrast value is shaken with brightness. When the laser oscillation energy changes as shown in FIG. 5, the light amount accumulated in the even field is larger than the light amount accumulated in the odd field. In that case, if a window called WRY1 is set to the RY1 mark of the mark shown in FIG. 1, and projection (integration) processing is performed in the direction of dx, a signal as shown in FIG. 1B is obtained. That is, the even pixels and odd pixels have different brightness due to the influence of the illumination intensity, resulting in a jagged signal. Note that there is no even / odd effect on the X mark (RX1, RX2, WX mark). This is because, since the projection direction is the dy direction orthogonal to the scanning line, the illuminance difference between the scanning lines acts uniformly on all pixels.
[0017]
In order to improve measurement accuracy, it is necessary to reduce the illuminance difference. Conventionally, there are a method of increasing the time (number of times) of integrating the captured electric signals, and a method of discarding the first image captured by the camera. However, the problem with these measures is that the time required for image capture becomes longer.
[0018]
As another countermeasure, there is a method of synchronizing the start of capturing and the origin of the swinging means for each even / odd field. The problem with this method is that not only the time for image capture is lengthened, but also the control of the swinging means and the capture control are complicated.
[0019]
In summary
1: The swinging unit cannot be adjusted to the image capturing cycle in a short time. When combined for a long time, it affects the throughput.
2: When capturing an image by the NTSC system, unevenness in the amount of illumination light occurs between even / odd fields, which affects measurement accuracy.
[0021]
  The present inventionInterlacedStorage type area sensorTaken withmarkofPositionmeasurementAdvantageous in terms of accuracyIt aims at providing a measuring device.
[0022]
[Means for Solving the Problems]
  BookInventionmeasurementThe deviceHas an interlaced storage area sensor,From the lighting deviceofMark illuminated with lightThe aboveThe mark is captured by a storage area sensor.Position ofMeasuremeasurementIn the device
  The mark includes a first mark whose position in a direction perpendicular to the direction of the scanning line of the storage area sensor is detected, and a second mark whose position in the direction of the scanning line is detected,
  Setting the first window to include at least a partial region of the first mark with respect to the image data obtained by the imaging;
  Setting a second window to include at least a partial area of the second mark with respect to the image data;
  Based on data obtained by performing projection processing on the image data in the first window in the direction of the scanning line.Even fieldandOdd fieldAt least one ofBrightnessCoefficient to correctSeekingRegarding the data obtained by the projection process,At least one brightnessPerson in chargeCorrect by number, Obtaining the position of the first mark based on the data obtained by the correction,
  Based on data obtained by performing projection processing in a direction orthogonal to the direction of the scanning line on the image data in the second window without correcting the brightness of at least one of the even field and the odd field. To determine the position of the second mark,
It is characterized byIt is a measuring device.
[0023]
  Furthermore, the present inventionexposureThe deviceIn an exposure apparatus that projects a mask pattern onto a wafer to expose the wafer,
  A mask stage, a wafer stage, and the measuring device,
  At least one of the mask stage and the wafer stage includes the first mark and the second mark,
An exposure apparatus characterized by that.
[0024]
  Furthermore, the present inventionDevice manufacturing methodIsExposing the substrate using the above exposure apparatus;
  Developing the substrate exposed in the step;
It is a device manufacturing method characterized by including.
[0026]
Preferred Embodiment of the Invention
In a first preferred embodiment of the present invention, in an apparatus for imaging reflected light from a mark illuminated with light output from an illuminating device with an interlaced accumulation type area sensor and measuring the mark, The brightness of the odd field is obtained, a constant for correcting the brightness of at least one of the even and odd fields is obtained, and the mark is measured using the image corrected with the constants on the left.
[0027]
In the second preferred embodiment of the present invention, the reflected light from the mark illuminated with the light output from the illuminating device is imaged by an interlaced storage type area sensor, and the image is measured by the device that measures the mark. A processing window is set for the image, one-dimensional information integrated in the scanning line direction is created, the brightness of the even pixel and odd pixel in the one-dimensional information is obtained, and the brightness of at least one of the even pixel and odd pixel is determined. A constant for correcting the thickness is obtained, and the mark is measured using the one-dimensional information corrected with the constant described on the left.
[0028]
Here, a pulse generator such as an excimer laser can be used as the illumination device. A CCD camera can be used as the storage type area sensor.
[0029]
In a third preferred embodiment of the present invention, in a semiconductor manufacturing apparatus that projects a mask pattern on a mask stage onto a wafer on a wafer stage via a projection lens, an alignment mark on the mask stage and an alignment on the wafer stage One or both of the marks are position-measured using the mark measuring apparatus according to the first or second embodiment.
[0030]
In a fourth preferred embodiment of the present invention, in a semiconductor manufacturing apparatus that projects a mask pattern on a mask stage onto a wafer on a wafer stage via a projection lens, a contrast measurement mark on the mask stage and a contrast measurement on the wafer stage Both or one of the marks is measured using the mark measuring apparatus according to the first or second embodiment.
[0031]
According to the second embodiment, the mark detection in the direction orthogonal to the scanning line is performed on an image in which the illuminance difference in the even / odd field is generated without matching the swing frequency of the swing means with the image capture. After integration in the scan line direction, the illuminance difference in the even / odd field is measured from the image before detection, and the signal or image is multiplied by a constant for correcting the even / odd difference to the even field pixel or odd field pixel. to correct. A highly accurate mark detection is performed by the corrected signal on the left.
[0032]
Originally, the reflectance on the substrate cannot change every 1/60 sec. Only the amount of illumination changes. Therefore, the illuminance at the time of even field accumulation and the illuminance at the time of odd field accumulation are measured from the part of the uniform reflectance in the image, the illuminance correction value is obtained from the illuminance on the left, and the illuminance correction value is obtained from the pixels in the even field Even field pixels and odd field pixels in the image can be corrected by multiplying the pixels in the field.
[0033]
Therefore, it is possible to perform an accurate calculation on the captured image without synchronizing the swinging means with the image capturing time and without discarding the first captured image data. Therefore, it is possible to detect a mark by acquiring an image at high speed with an NTSC camera without using a complicated illumination system.
[0034]
【Example】
FIG. 2 is a configuration diagram of a semiconductor manufacturing apparatus according to an embodiment of the present invention, and shows a case where a mark on a reticle stage and a mark on a wafer stage are observed by the TTR method and both or one of them is measured. The measured values are mark brightness, mark contrast (defocus amount), mark position, and the like. The details of the measurement method of brightness, contrast, and mark position are not important in the present invention. The subject is a illuminance difference correction method that enables measurement of mark brightness, contrast, and mark position without error even when an illuminance difference in the even / odd field occurs in the captured image. Therefore, in this embodiment, detailed description of the mark measurement method is omitted.
[0035]
In FIG. 2, 1 is a reticle (reticle reference plate), 2 is a projection lens, 3 is a stage reference plate, 4 is a wafer stage, 5 is a mirror, 6 is a half mirror, 7 is a swing means, 8 is a CCD camera, 10 Is a reticle mark (reticle side mark), 11 is an AD converter, 12 is an image adder, 13 is a synchronization signal generator, 14 is an image processing device, 15 is an excimer laser (pulse laser), 16 is an exposure device controller, 17 Is a swing control device, 18 is a stage control device, and 19 is an interferometer.
[0036]
The excimer laser 15 is a gas laser in which KrF, ArF, F2, etc. are sealed, and is a light source that generates pulsed laser light. The pulsed light generated here enters the rocking means 7. The oscillating means 7 is an optical system for oscillating an incident beam circumferentially at the output, and is realized by rotating a wedge by a motor, for example. The beam oscillated by the oscillating means 7 passes through the half mirror 6, is reflected by the mirror 5, and reaches the reticle side mark 10 on the reticle stage. Further, the light passes through the projection lens 2 and irradiates the reference mark 3 on the wafer stage 4.
[0037]
The pulsed light emitted from the excimer laser generally has a large uneven illuminance in the beam compared to continuous light such as a mercury lamp. If exposure is performed while the beam is fixed, the illuminance unevenness on the wafer cannot be suppressed within an allowable range even if exposure is performed with a plurality of pulses. Therefore, in this embodiment, the excimer laser is caused to emit light while the beam is oscillated circumferentially by the oscillating means 7.
[0038]
On the other hand, in FIG. 2, the beam reflected by the reference mark 3 is the projection lens 2 and the reticle side mark 1.0Is reflected by the mirror 5, Through half mirror 6Then, the light enters the imaging surface of the CCD camera (Cam) 8. Therefore, the CCD camera 8 can observe the stage reference mark 3 and the reticle side mark 10 simultaneously, and by processing this image, the relative position of the wafer stage and the reticle stage or the brightness and contrast of each mark can be known. .
[0039]
Image capture will be described with reference to FIG. As shown in Japanese Patent Application Laid-Open No. 3-226187 and Japanese Patent Application Laid-Open No. 4-26011, the swinging means is rotated while being synchronized with an image capture synchronization signal (Sync). In the case of the NTSC system, the image is stored in the even / odd field every 1/60 sec. The lasers are controlled so that the same number of laser pulses always enters each field. FIG. 3 shows that three frames of images are captured when the swinging means rotates once. The image of the first frame constituted by the even / odd field is converted from voltage (analog signal) to digital data by the AD converter 11 of FIG. The images of the second and third frames are added and synthesized with the image stored in the adder 12 while being converted into digital data by the AD converter 11. In the case of FIG. 3, the swinging means rotates twice and 6 frames are added. Increasing the number of additional frames reduces illuminance unevenness, but increases the capture time. The number of additions is preferably the maximum number allowed for the system.
[0040]
Next, a method for measuring the brightness of the even / odd field from the captured image will be described.
[0041]
FIG. 1 shows a state in which the mark 1 on the reticle plate and the mark 3 on the stage plate captured by the CCD camera 8 are imaged simultaneously. A window WRY1 is set for the reticle mark RY1, and projection processing is performed in the direction of dx. The projection-processed signal is as shown in FIG. The obtained even field pixels are projected to the even pixels in the signal, and the odd field pixels are projected to the odd pixels in the signal. Since there is an illuminance difference in the even / odd field, the odd pixel is brighter than the even pixel. The reticle mark is produced by vapor-depositing chromium or the like on the glass surface. And the reflectance is managed and manufactured so that it may become uniform. Therefore, the projection data at the top (peak and valley) of the signal SRY1 all indicate the brightness of the reflected light on the reticle chrome surface. For example, the peak is the brightness of the even pixel, and the valley is the brightness of the odd pixel. Therefore, the brightness of the even pixel and odd pixel at the top of SRY1 is taken out, and the brightness Es of the even pixel and the brightness Os of the odd pixel are obtained by the following equations. N is a predetermined number of pixels, and S is obtained from the mark center position.
[0042]
[Expression 1]

[0043]
[Expression 2]

[0044]
For example, S can be obtained by roughly detecting the center position of the RY1 mark from the signal SRY1 to obtain RY1C, and let S be the position moved by RY1C-N / 2 pixels from that position.
[0045]
Next, the illuminance correction for the even and odd pixels will be described. The illuminance correction of the even and odd pixels may be performed by adjusting the darker pixel to the brighter pixel, or conversely adjusting the brighter pixel to the darker pixel, or the average value. Here, an example of matching to the brighter side is shown. Using Es and Os found in the above formula
[0046]
[Equation 3]

[0047]
When the above calculation is performed, if the even pixel is bright, the odd pixel is brightened and its coefficient is set to Ko. Brightness correction is performed by multiplying all odd pixels by Ko. When the odd pixel is bright, the brightness is corrected by multiplying all even pixels by Ke. Thus, the corrected signal is a signal SRY1 'shown in FIG. Compared to FIG. 1B, the signal is smoother.
[0048]
The coefficients Ko and Ke can also be used for signals produced by projecting the windows WWY and WRY2, and the brightness correction of even / odd pixels is performed with the respective signals.
[0049]
If the mark position of the reticle plate and the mark position of the stage plate are obtained using the signal in which the illuminance difference between even / odd pixels is corrected in this way, a measurement result independent of the illuminance is obtained. Further, in the measurement of the light amount and the signal contrast, after performing the same processing, for example, the light amount of the mark is obtained from the maximum value of the SRY1 'signal, and the contrast is obtained from the differential value of SRY1'.
[0050]
In this embodiment, the correction characteristic of the present invention is performed on the projected signal, but it may be performed on the entire captured image. In that case, Equation 4 is expanded as follows.
[0051]
[Expression 4]

[0052]
In Equation 4, when the above calculation is performed, if the even field is bright, the odd field is brightened and its coefficient is Ko. Brightness correction is performed by multiplying the pixels of all odd fields by Ko. When the odd field is bright, the brightness is corrected by multiplying all the even field pixels by Ke.
[0053]
In this embodiment, the measurement mark is used to measure the brightness of the even / odd field. However, an even / odd image is formed by imaging a dedicated mark composed of a uniform reflecting surface shown by LM in FIG. You may measure the brightness of the field. The dedicated mark only needs to exist within a range that does not affect the mark measurement within the visual field. The arrangement of the dedicated mark may be on the stage reference mark 3 side or on the reticle side mark 10. When the dedicated mark is used, it is not necessary to obtain the mark position. The brightness of the even / odd field at the dedicated mark is measured by the following equation.
[0054]
[Equation 5]

[0055]
A one-dimensional signal or a two-dimensional image is corrected using Es and Os obtained by Expressions 5 and 6, and Expressions 3 and 4.
[0056]
In addition, the present Example demonstrated the example using the apparatus which generate | occur | produces pulsed light as an illuminating device. This is because the temporal illuminance change is large. However, this correction method and measurement method are effective when a temporal illuminance change occurs even in a lighting device that emits light continuously. For example, a temporal change in illuminance occurs in a discharge lamp or the like.
[0057]
<Example of semiconductor production system>
Next, an example of a production system for semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, micromachines, etc.) will be described. In this method, maintenance services such as troubleshooting, periodic maintenance, and software provision for manufacturing apparatuses installed in a semiconductor manufacturing factory are performed using a computer network outside the manufacturing factory.
[0058]
FIG. 6 shows the entire system cut out from a certain angle. In the figure, reference numeral 101 denotes a business office of a vendor (apparatus supply manufacturer) that provides a semiconductor device manufacturing apparatus. As an example of a manufacturing apparatus, a semiconductor manufacturing apparatus for various processes used in a semiconductor manufacturing factory, for example, equipment for a pre-process (lithography apparatus such as an exposure apparatus, a resist processing apparatus, an etching apparatus, a heat treatment apparatus, a film forming apparatus, and a planarization Equipment) and post-process equipment (assembly equipment, inspection equipment, etc.). The office 101 includes a host management system 108 that provides a maintenance database for manufacturing apparatuses, a plurality of operation terminal computers 110, and a local area network (LAN) 109 that connects these to construct an intranet. The host management system 108 includes a gateway for connecting the LAN 109 to the Internet 105, which is an external network of the office, and a security function for restricting access from the outside.
[0059]
On the other hand, reference numerals 102 to 104 denote manufacturing factories of semiconductor device manufacturers as users of manufacturing apparatuses. The manufacturing factories 102 to 104 may be factories belonging to different manufacturers, or may belong to the same manufacturer (for example, a factory for a pre-process, a factory for a post-process, etc.). In each of the factories 102 to 104, a plurality of manufacturing apparatuses 106, a local area network (LAN) 111 that connects them to construct an intranet, and host management as a monitoring apparatus that monitors the operating status of each manufacturing apparatus 106 are provided. A system 107 is provided. The host management system 107 provided in each factory 102 to 104 includes a gateway for connecting the LAN 111 in each factory to the Internet 105 which is an external network of the factory. As a result, it becomes possible to access the host management system 108 on the vendor 101 side from the LAN 111 of each factory via the Internet 105, and only a limited user is permitted to access by the security function of the host management system 108. Specifically, status information (for example, a symptom of a manufacturing apparatus in which a trouble has occurred) indicating the operating status of each manufacturing apparatus 106 is notified from the factory side to the vendor side via the Internet 105, and corresponding to the notification. Maintenance information such as response information (for example, information for instructing a coping method for trouble, coping software or data), latest software, help information, etc. can be received from the vendor side. A communication protocol (TCP / IP) generally used on the Internet is used for data communication between the factories 102 to 104 and the vendor 101 and data communication on the LAN 111 in each factory. Instead of using the Internet as an external network outside the factory, it is also possible to use a high-security dedicated line network (such as ISDN) without being accessible from a third party. The host management system is not limited to the one provided by the vendor, and the user may construct a database and place it on an external network, and allow access to the database from a plurality of factories of the user.
[0060]
FIG. 7 is a conceptual diagram showing the overall system of this embodiment cut out from an angle different from that in FIG. In the previous example, a plurality of user factories each equipped with a manufacturing apparatus and a management system of a vendor of the manufacturing apparatus are connected via an external network, and production management of each factory or at least one unit is performed via the external network. Data communication of manufacturing equipment was performed. On the other hand, in this example, a factory equipped with a plurality of vendors' manufacturing devices and a management system of each vendor of the plurality of manufacturing devices are connected via an external network outside the plant, and maintenance information for each manufacturing device is obtained. Data communication. In the figure, reference numeral 201 denotes a manufacturing factory of a manufacturing apparatus user (semiconductor device manufacturer), and a manufacturing apparatus that performs various processes on the manufacturing line of the factory. 204 has been introduced. In FIG. 7, only one manufacturing factory 201 is depicted, but actually, a plurality of factories are similarly networked. Each device in the factory is connected by a LAN 206 to form an intranet, and the host management system 205 manages the operation of the production line. On the other hand, vendors (apparatus supply manufacturers) such as an exposure apparatus manufacturer 210, a resist processing apparatus manufacturer 220, and a film formation apparatus manufacturer 230 have host management systems 211 and 221 for remote maintenance of supplied devices. 231 and these comprise a maintenance database and an external network gateway as described above. The host management system 205 that manages each device in the user's manufacturing factory and the vendor management systems 211, 221, and 231 of each device are connected by the external network 200, which is the Internet or a dedicated line network. In this system, if a trouble occurs in any of a series of production equipment on the production line, the operation of the production line is suspended, but remote maintenance via the Internet 200 is received from the vendor of the troubled equipment. This enables quick response and minimizes production line outages.
[0061]
Each manufacturing apparatus installed in the semiconductor manufacturing factory includes a display, a network interface, a computer for executing network access software stored in a storage device and software for operating the apparatus. The storage device is a built-in memory, a hard disk, or a network file server. The network access software includes a dedicated or general-purpose web browser, and provides, for example, a user interface having a screen as shown in FIG. 8 on the display. The operator who manages the manufacturing apparatus in each factory refers to the screen while referring to the screen of the manufacturing apparatus (401), serial number (402), trouble subject (403), date of occurrence (404), urgency (405), Information such as symptom (406), coping method (407), progress (408), etc. is input to the input items on the screen. The input information is transmitted to the maintenance database via the Internet, and appropriate maintenance information as a result is returned from the maintenance database and presented on the display. The user interface provided by the web browser further realizes a hyperlink function (410 to 412) as shown in the figure, and the operator can access more detailed information on each item or use the software library provided by the vendor for the manufacturing apparatus. The latest version of software can be pulled out, and operation guides (help information) can be pulled out for reference by factory operators. Here, the maintenance information provided by the maintenance database includes information on correction of illuminance deviation of the even field (or pixel) and odd field (or pixel) of the mark image data described above, and the software library includes the software library. The latest software to realize mark measurement including correction is also provided.
[0062]
Next, a semiconductor device manufacturing process using the production system described above will be described. FIG. 9 shows the flow of the entire manufacturing process of the semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and is an assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7). The pre-process and post-process are performed in separate dedicated factories, and maintenance is performed for each of these factories by the remote maintenance system described above. In addition, information for production management and apparatus maintenance is communicated between the pre-process factory and the post-process factory via the Internet or a dedicated network.
[0063]
FIG. 10 shows a detailed flow of the wafer process. In step 11 (oxidation), the wafer surface is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed onto the wafer by exposure using the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. Since the manufacturing equipment used in each process is maintained by the remote maintenance system described above, it is possible to prevent problems before they occur, and to recover quickly if a problem occurs. Productivity can be improved.
[0064]
【The invention's effect】
  BookAccording to the invention, an interlaced storage type area sensorIt is possible to provide a measuring device that is advantageous in terms of accuracy in measuring the position of the mark imaged in.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment of the present invention.
FIG. 2 is a configuration diagram of a semiconductor manufacturing apparatus which is an example to which the present invention is applied.
FIG. 3 is a diagram illustrating timings of swinging means, laser emission, and image accumulation.
FIG. 4 is a diagram illustrating interlaced image capture.
FIG. 5 is a diagram showing variations in laser pulse energy.
FIG. 6 is a conceptual diagram of a semiconductor device production system viewed from a certain angle.
FIG. 7 is a conceptual diagram of a semiconductor device production system viewed from another angle.
FIG. 8 is a specific example of a user interface.
FIG. 9 illustrates a flow of a device manufacturing process.
FIG. 10 is a diagram illustrating a wafer process.
[Explanation of symbols]
1: reticle (reticle reference plate), 2: projection lens, 3: stage reference plate, 7: swinging means, 8: CCD camera, 12: image adder, 13: synchronization signal generator, 14: image processor, 15: excimer laser (pulse laser), 16: exposure device control device, 17: swing control device, 18: stage control device, 19: interferometer.

Claims (8)

Has a storage area sensor interlaced, in the measuring device for measuring the position of the mark marks illuminated by the light captured by the storage area sensor from the lighting device,
The mark includes a first mark whose position in a direction perpendicular to the direction of the scanning line of the storage area sensor is detected, and a second mark whose position in the direction of the scanning line is detected,
Setting the first window to include at least a partial region of the first mark with respect to the image data obtained by the imaging;
Setting a second window to include at least a partial area of the second mark with respect to the image data;
Obtains a coefficient for correcting at least one of the brightness of the even and odd fields based on data obtained by performing projection processing in the direction of the scanning lines for the image data in said first window, said projection the at least one of brightness with respect to data obtained by the processing is corrected by the coefficient, it obtains the position of the first mark based on data obtained by the correction,
Based on data obtained by performing projection processing in a direction orthogonal to the direction of the scanning line on the image data in the second window without correcting the brightness of at least one of the even field and the odd field. To determine the position of the second mark,
It shall be the said measuring device. The measuring apparatus according to claim 1, further comprising obtaining a contrast of data for obtaining the position of the first mark and further obtaining a contrast of data for obtaining the position of the second mark. The lighting device, measuring device according to claim 1 or 2 including an optical system for injecting, it is characterized as a light swings circumferentially light incident at a predetermined period. The lighting device includes a light source for generating pulsed light, measuring device according to any one of claims 1 to 3, wherein the. The measuring apparatus according to claim 4 , wherein the light source is an excimer laser light source . The storage area-sensor is a CCD camera, measurement apparatus according to any one of claims 1 to 5, wherein the. The exposure apparatus comprising the wafer by projecting the mask pattern onto a wafer,
A mask stage, a wafer stage, and the measuring device according to any one of claims 1 to 6,
At least one of the mask stage and the wafer stage includes the first mark and the second mark,
An exposure apparatus characterized by that. Exposing the substrate using the exposure apparatus according to claim 7;
Developing the substrate exposed in the step;
A device manufacturing method comprising:

Images