JP2011049369A

JP2011049369A - Optical characteristic measuring device and calibration method of the same, and exposure method and exposure device

Info

Publication number: JP2011049369A
Application number: JP2009196740A
Authority: JP
Inventors: Toru Fujii; 藤井　　透
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 2009-08-27
Filing date: 2009-08-27
Publication date: 2011-03-10

Abstract

<P>PROBLEM TO BE SOLVED: To high accurately perform a calibration of an optical characteristic measuring device by arranging a measurement system of the optical characteristic measuring device on an object surface side of an optical projection system. <P>SOLUTION: This invention relates to a wave front aberration measuring device 20 of the optical projection system PL, and is equipped with: a test reticle R1 having an opening 19 for measurement; a measurement system 21 which measures a wave front of the optical projection system PL by passing through the opening 19 for measurement and the optical projection system PL and by receiving illumination light returned from an image plane through the optical projection system PL; a reflective diffusion spherical surface 24 illuminating a region containing the opening 19 for measurement, which can be attachably and detachably arranged in an optical path of an illumination light IL and reflects the illumination light passing through the opening 19 for measurement; and a measuring section 17 seeking for a wave front of the measurement system 21 by receiving a measuring light passing through the opening 19 for measurement, with the measurement system 21. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、被検光学系の波面収差等の光学特性を計測する光学特性計測技術、その光学特性を計測する装置の校正技術、及びその光学特性計測技術を用いる露光技術に関する。 The present invention relates to an optical characteristic measurement technique for measuring optical characteristics such as wavefront aberration of a test optical system, a calibration technique for an apparatus for measuring the optical characteristic, and an exposure technique using the optical characteristic measurement technique.

例えば半導体デバイス等のマイクロデバイス（電子デバイス）を製造するためのリソグラフィ工程中で、レチクル（又はフォトマスク等）のパターンを投影光学系を介してウエハ（又はガラスプレート等）の各ショット領域に転写露光するために一括露光型又は走査露光型等の露光装置が使用されている。これらの露光装置においては、投影光学系の波面収差等の光学特性を所定の状態に維持するために、従来より様々な計測装置が使用されている。 For example, during a lithography process for manufacturing microdevices (electronic devices) such as semiconductor devices, the pattern of a reticle (or photomask) is transferred to each shot area on a wafer (or glass plate, etc.) via a projection optical system. For exposure, an exposure apparatus such as a batch exposure type or a scanning exposure type is used. In these exposure apparatuses, various measuring apparatuses have been conventionally used in order to maintain optical characteristics such as wavefront aberration of the projection optical system in a predetermined state.

例えば投影光学系の波面収差を計測するために、投影光学系を介して計測用開口の一次像を像面側に投影し、その一次像からの光束を複数に波面分割し、このように波面分割された複数の光束から形成された二次像の横シフト量等を求めるシャック・ハルトマン（Shack-Hartmann）方式の計測装置が知られている。この計測装置では、計測用開口の形成面（物体面）に計測用開口よりも大きい校正用開口を設けておき、例えば定期的に、その校正用開口の投影光学系による一次像を所定のピンホールを介して検出し、この検出結果より計測用の光学系（計測系）自体の波面収差の計測し、計測装置の校正を行っていた（例えば、特許文献１参照）。 For example, in order to measure the wavefront aberration of the projection optical system, the primary image of the measurement aperture is projected onto the image plane side via the projection optical system, and the light beam from the primary image is divided into a plurality of wavefronts, and thus the wavefront There is known a Shack-Hartmann type measuring device that obtains a lateral shift amount or the like of a secondary image formed from a plurality of divided light beams. In this measurement apparatus, a calibration aperture larger than the measurement aperture is provided on the measurement aperture forming surface (object surface), and, for example, a primary image by the projection optical system of the calibration aperture is periodically captured by a predetermined pin. Detection was made through a hole, and the wavefront aberration of the measurement optical system (measurement system) itself was measured from the detection result, and the measurement apparatus was calibrated (for example, see Patent Document 1).

特開２００２−７１５１４号公報JP 2002-71514 A

最近では、露光装置のウエハステージ側の構成を簡素化するために、投影光学系の光学特性の計測系を物体面側に配置することが検討されている。このように計測系を物体面側に配置する場合、単に投影光学系の物体面に計測用開口を設置し、像面に反射ミラーを設置し、反射ミラーからの反射光を投影光学系及び計測用開口を介して計測系で受光すると、原理的に反射ミラーからの反射光の像は計測用開口以上には広がらないため、投影光学系の光学特性の影響を抑制して、計測装置の校正を高精度に行うことが困難であった。 Recently, in order to simplify the configuration of the exposure apparatus on the wafer stage side, it has been studied to arrange an optical characteristic measurement system of the projection optical system on the object plane side. When the measurement system is arranged on the object plane side in this way, a measurement aperture is simply installed on the object plane of the projection optical system, a reflection mirror is installed on the image plane, and the reflected light from the reflection mirror is measured by the projection optical system and measurement. When the measurement system receives light through the aperture for measurement, the reflected light image from the reflecting mirror does not spread beyond the aperture for measurement in principle. Therefore, the influence of the optical characteristics of the projection optical system is suppressed, and the measurement device is calibrated. It was difficult to carry out with high accuracy.

また、その反射ミラーを像面からデフォーカスさせることで、その計測用開口を含む領域に照明光を照射することが可能である。しかしながら、この場合には、その計測用開口に戻される反射光の開口数が小さくなり、必要な計測精度を得られない恐れがあった。
本発明は、このような課題に鑑み、投影光学系の物体面側に光学特性計測装置の計測系を配置する場合に、その光学特性計測装置の校正を高精度に行うことを目的とする。 In addition, by defocusing the reflecting mirror from the image plane, it is possible to irradiate illumination light to a region including the measurement aperture. However, in this case, the numerical aperture of the reflected light returned to the measurement aperture becomes small, and there is a possibility that the required measurement accuracy cannot be obtained.
The present invention has been made in view of the above problems, and an object of the present invention is to calibrate an optical characteristic measuring device with high accuracy when the measuring system of the optical characteristic measuring device is arranged on the object plane side of the projection optical system.

本発明の第１の態様によれば、第１面のパターンの像を第２面に形成する投影光学系の光学特性を計測する装置において、その第１面側に配置され、計測用開口が形成された開口部材と、その第１面側に配置されたその開口部材を照明光で照明する照明系と、その計測用開口及びその投影光学系を通過し、その第２面から戻されたその照明光の少なくとも一部をその投影光学系及びその計測用開口を介して受光して、その投影光学系の光学特性を計測する計測系と、その照明光の光路中に挿入又は離脱可能に配置され、その計測用開口を通過したその照明光の少なくとも一部を反射し、該反射した光束でその計測用開口を含む領域を照明する第１反射光学系と、その計測用開口を通過した計測光をその計測系で受光して、その計測系の光学特性を計測する計測装置と、を備える光学特性計測装置が提供される。 According to the first aspect of the present invention, in the apparatus for measuring the optical characteristics of the projection optical system that forms the pattern image of the first surface on the second surface, the measurement aperture is disposed on the first surface side. The formed aperture member, the illumination system that illuminates the aperture member arranged on the first surface side with illumination light, the measurement aperture and the projection optical system, and returned from the second surface At least a part of the illumination light is received through the projection optical system and the measurement aperture, and a measurement system that measures the optical characteristics of the projection optical system, and can be inserted into or removed from the optical path of the illumination light A first reflective optical system that is disposed and reflects at least a part of the illumination light that has passed through the measurement aperture and illuminates a region including the measurement aperture with the reflected light beam, and has passed through the measurement aperture The measurement light is received by the measurement system, and the optical characteristics of the measurement system are received. Optical characteristic measuring apparatus and a measuring device for measuring a is provided.

また、本発明の第２の態様によれば、第１面のパターンの像を第２面に形成する投影光学系の光学特性を計測する装置の校正方法において、その第１面またはその近傍に計測用開口が形成された開口部材を配置する工程と、照明光でその計測用開口を照明する工程と、その照明光の光路中に、その計測用開口を通過したその照明光の少なくとも一部を反射する第１反射部材を挿入する工程と、その第１反射部材で反射したその照明光でその計測用開口を含む領域を照明する工程と、その反射した照明光のうちその計測用開口を通過した計測光を計測系で受光し、その計測系の光学特性を求める工程と、を含む光学特性計測装置の校正方法が提供される。 According to the second aspect of the present invention, in the calibration method of the apparatus for measuring the optical characteristics of the projection optical system for forming the pattern image of the first surface on the second surface, the first surface or the vicinity thereof is provided. A step of disposing an aperture member in which a measurement aperture is formed; a step of illuminating the measurement aperture with illumination light; and at least a part of the illumination light that has passed through the measurement aperture in the optical path of the illumination light A step of inserting a first reflecting member that reflects the light, a step of illuminating a region including the measurement aperture with the illumination light reflected by the first reflection member, and a measurement aperture of the reflected illumination light A method for calibrating an optical property measuring apparatus is provided, including the step of receiving the measurement light that has passed through the measurement system and obtaining the optical properties of the measurement system.

また、本発明の第３の態様によれば、照明光でパターンを照明し、その照明光でそのパターン及び投影光学系を介して物体を露光する露光装置において、その投影光学系の光学特性を計測するために本発明の第１の態様による光学特性計測装置を備える露光装置が提供される。
また、本発明の第４の態様によれば、照明光でパターンを照明し、その照明光でそのパターン及び投影光学系を介して物体を露光する露光方法において、本発明の第２の態様による光学特性計測装置の校正方法を用いて、その投影光学系の光学特性を計測する光学特性計測装置の校正を行う露光方法が提供される。 According to the third aspect of the present invention, in an exposure apparatus that illuminates a pattern with illumination light and exposes an object with the illumination light through the pattern and the projection optical system, the optical characteristics of the projection optical system are An exposure apparatus provided with the optical characteristic measurement apparatus according to the first aspect of the present invention for measurement is provided.
According to a fourth aspect of the present invention, in an exposure method of illuminating a pattern with illumination light and exposing an object with the illumination light through the pattern and the projection optical system, according to the second aspect of the present invention. An exposure method for calibrating an optical property measuring apparatus that measures the optical properties of the projection optical system using the optical property measuring device calibration method is provided.

本発明によれば、第１反射光学系からの反射光で計測用開口を含む領域を照明することができるため、投影光学系の光学特性の影響を抑制して、計測系の光学特性のみを高精度に計測できる。従って、投影光学系の物体面側に計測系を配置する場合に、その光学特性計測装置の校正を高精度に行うことができる。 According to the present invention, the area including the measurement aperture can be illuminated with the reflected light from the first reflective optical system, so that the influence of the optical characteristics of the projection optical system is suppressed, and only the optical characteristics of the measurement system are reduced. It can measure with high accuracy. Therefore, when the measurement system is arranged on the object plane side of the projection optical system, the optical property measurement apparatus can be calibrated with high accuracy.

（Ａ）は第１の実施形態の露光装置の概略構成を示す図、（Ｂ）はテストレチクルのパターンの一例を示す平面図である。(A) is a figure which shows schematic structure of the exposure apparatus of 1st Embodiment, (B) is a top view which shows an example of the pattern of a test reticle. （Ａ）は投影光学系ＰＬの波面収差を計測中の光学系の要部を示す断面図、（Ｂ）は図２（Ａ）中の計測用開口１９を示す拡大平面図である。(A) is sectional drawing which shows the principal part of the optical system which is measuring the wavefront aberration of projection optical system PL, (B) is an enlarged plan view which shows the measurement opening 19 in FIG. 2 (A). （Ａ）は波面収差計測装置２０を校正しているときの光学系の要部を示す断面図、（Ｂ）は図３（Ａ）中の計測用開口１９を示す拡大平面図、（Ｃ）は図３（Ａ）中の反射拡散球面２４を示す拡大断面図である。(A) is sectional drawing which shows the principal part of an optical system when calibrating the wavefront aberration measuring apparatus 20, (B) is an enlarged plan view which shows the measurement opening 19 in FIG. 3 (A), (C). FIG. 4 is an enlarged cross-sectional view showing a reflective diffusion spherical surface 24 in FIG. （Ａ）は波面収差計測装置２０の校正動作の一例を示すフローチャート、（Ｂ）は波面収差計測装置２０を用いた計測動作の一例を示すフローチャートである。(A) is a flowchart showing an example of a calibration operation of the wavefront aberration measuring apparatus 20, and (B) is a flowchart showing an example of a measuring operation using the wavefront aberration measuring apparatus 20. 反射拡散球面２４の代わりに使用できる拡散反射光学系５１を示す拡大図である。FIG. 3 is an enlarged view showing a diffuse reflection optical system 51 that can be used in place of the reflective diffuse spherical surface 24. 第２の実施形態の波面収差計測装置２０Ａを示す断面図である。It is sectional drawing which shows 20A of wavefront aberration measuring apparatuses of 2nd Embodiment.

［第１の実施形態］
以下、本発明の第１の実施形態につき図１〜図４を参照して説明する。
図１（Ａ）は本実施形態の露光装置ＥＸの概略構成を示す。図１（Ａ）において、露光装置ＥＸは、露光光源１と、露光光源１からの照明光ＩＬ（露光光）でレチクルＲ（マスク）のパターン面を照明する照明光学系ＩＬＳと、レチクルＲを保持するレチクルステージＲＳＴと、パターン面（物体面）のパターンの像をウエハＷの表面（像面）に投影する投影光学系ＰＬと、ウエハＷを保持して移動するウエハステージＷＳＴと、装置全体の動作を統括的に制御するコンピュータよりなる主制御系１１と、その他の計測装置及び駆動装置等とを備えている。露光光源１としては、ＡｒＦエキシマレーザ光源（波長１９３ｎｍ）が使用されているが、その他にＫｒＦエキシマレーザ光源（波長２４８ｎｍ）又は水銀ランプ等も使用できる。 [First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1A shows a schematic configuration of the exposure apparatus EX of the present embodiment. In FIG. 1A, an exposure apparatus EX includes an exposure light source 1, an illumination optical system ILS that illuminates a pattern surface of a reticle R (mask) with illumination light IL (exposure light) from the exposure light source 1, and a reticle R. Reticle stage RST to be held, projection optical system PL for projecting a pattern surface (object plane) pattern image onto the surface (image plane) of wafer W, wafer stage WST to hold and move wafer W, and the entire apparatus A main control system 11 composed of a computer for comprehensively controlling the operation of the apparatus, and other measuring devices and driving devices. As the exposure light source 1, an ArF excimer laser light source (wavelength 193 nm) is used, but a KrF excimer laser light source (wavelength 248 nm), a mercury lamp, or the like can also be used.

露光光源１から射出されるほぼ直線偏光の照明光ＩＬは、周知のビーム送光系２を介して、照明光ＩＬの偏光状態を異なる方向の直線偏光又は円偏光等に変換する偏光状態可変部３に入射する。偏光状態可変部３を通過した照明光ＩＬは、光束の断面形状を変化させるためのビーム形状可変部４を介して、マイクロフライアイレンズ（又はフライアイレンズ）５に入射する。マイクロフライアイレンズ５の射出面（照明光学系ＩＬＳの瞳面）に多数の二次光源からなる面光源が形成される。なお、さらに照明光ＩＬの光量分布を制御するための回折光学素子等を設けてもよい。また、マイクロフライアイレンズ５の代わりに、ロッドインテグレータ（内面反射型インテグレータ）等のオプティカルインテグレータを使用しても良い。また、照明光学系ＩＬＳの瞳面には、通常照明、輪帯照明、２極照明、変形照明等の種々の照明に切り替えるための可変開口絞り部（不図示）が設置されている。 A substantially linearly polarized illumination light IL emitted from the exposure light source 1 converts a polarization state of the illumination light IL into linearly polarized light or circularly polarized light in a different direction through a known beam transmission system 2. 3 is incident. The illumination light IL that has passed through the polarization state varying unit 3 is incident on a micro fly's eye lens (or fly eye lens) 5 through a beam shape varying unit 4 for changing the cross-sectional shape of the light beam. A surface light source including a large number of secondary light sources is formed on the exit surface of the micro fly's eye lens 5 (pupil surface of the illumination optical system ILS). Further, a diffractive optical element or the like for controlling the light amount distribution of the illumination light IL may be provided. Further, instead of the micro fly's eye lens 5, an optical integrator such as a rod integrator (an internal reflection type integrator) may be used. In addition, a variable aperture stop (not shown) for switching to various illuminations such as normal illumination, annular illumination, dipole illumination, and modified illumination is installed on the pupil plane of the illumination optical system ILS.

マイクロフライアイレンズ５から射出された照明光ＩＬは、第１リレー光学系６、レチクルブラインド７、第２リレー光学系８Ａ、コンデンサ光学系８Ｂ、及び光路折り曲げ用のミラー９を介して、レチクルＲのパターン面（下面）の照明領域を均一な照度分布で照明する。ビーム送光系２からコンデンサ光学系８Ｂ及びミラー９までの部材を含んで照明光学系ＩＬＳが構成されている。露光光源１、偏光状態可変部３、及びビーム形状可変部４の動作は、主制御系１１内の照明系制御部によって制御されている。 The illumination light IL emitted from the micro fly's eye lens 5 passes through the first relay optical system 6, the reticle blind 7, the second relay optical system 8A, the condenser optical system 8B, and the mirror 9 for bending the optical path, and the reticle R. The illumination area of the pattern surface (lower surface) is illuminated with a uniform illuminance distribution. The illumination optical system ILS includes members from the beam transmission system 2 to the condenser optical system 8B and the mirror 9. The operations of the exposure light source 1, the polarization state variable unit 3, and the beam shape variable unit 4 are controlled by an illumination system control unit in the main control system 11.

照明光ＩＬのもとで、レチクルＲの照明領域内のパターンは、投影光学系ＰＬを介して投影倍率β（例えば１／４，１／５等の縮小倍率）で、ウエハＷの一つのショット領域内の露光領域（照明領域と光学的に共役な領域）に転写露光される。ウエハＷは、シリコン又はＳＯＩ(silicon on insulator)等からなる直径が２００〜４５０ｍｍ程度の平板状の基材の上面にフォトレジスト（感光剤）を塗布したものである。投影光学系ＰＬは、一例として屈折系であるが、その外に反射屈折系等も使用可能である。以下、投影光学系ＰＬの光軸ＡＸに平行にＺ軸を取り、Ｚ軸に垂直な平面内で図１（Ａ）の紙面に平行な方向にＸ軸を、図１（Ａ）の紙面に垂直な方向にＹ軸を取って説明する。 Under the illumination light IL, the pattern in the illumination area of the reticle R is one shot of the wafer W at the projection magnification β (for example, a reduction magnification of 1/4, 1/5, etc.) via the projection optical system PL. Transfer exposure is performed on an exposure area within the area (an area optically conjugate with the illumination area). The wafer W is obtained by applying a photoresist (photosensitive agent) to the upper surface of a flat substrate having a diameter of about 200 to 450 mm made of silicon or SOI (silicon on insulator). The projection optical system PL is a refractive system as an example, but a catadioptric system or the like can also be used. Hereinafter, the Z-axis is taken in parallel to the optical axis AX of the projection optical system PL, the X-axis is set in the direction parallel to the paper surface of FIG. 1A in a plane perpendicular to the Z-axis, and the paper surface of FIG. A description will be given taking the Y axis in the vertical direction.

図１（Ａ）中に切り欠いて示すように、投影光学系ＰＬを構成する所定の光学部材、例えばレンズエレメント１４Ａ，１４Ｂは、不図示のレンズ枠及びＺ方向に伸縮可能な３箇所の駆動素子１３Ａ，１３Ｂを介して鏡筒に支持されている。主制御系１１内の結像特性制御部が、駆動系１２を介して駆動素子１３Ａ，１３Ｂを駆動することによって、レンズエレメント１４Ａ，１４ＢのＺ方向の位置、並びにＸ軸及びＹ軸に平行な軸の回り（θｘ方向及びθｙ方向）の傾斜角を制御できる。これによって、投影光学系ＰＬの所定の結像特性（例えば所定の波面収差等）を補正できる。なお、駆動可能なレンズエレメント１４Ａ，１４Ｂの位置及び個数は、制御対象の結像特性に応じて任意に設定可能である。 As shown in FIG. 1A, a predetermined optical member constituting the projection optical system PL, for example, the lens elements 14A and 14B, includes a lens frame (not shown) and three places that can be expanded and contracted in the Z direction. It is supported by the lens barrel via elements 13A and 13B. The imaging characteristic control unit in the main control system 11 drives the drive elements 13A and 13B via the drive system 12, whereby the lens elements 14A and 14B are positioned in the Z direction and parallel to the X axis and the Y axis. The tilt angle around the axis (θx direction and θy direction) can be controlled. This makes it possible to correct a predetermined imaging characteristic (for example, a predetermined wavefront aberration) of the projection optical system PL. Note that the position and the number of the lens elements 14A and 14B that can be driven can be arbitrarily set according to the imaging characteristics to be controlled.

次に、レチクルＲを吸着保持するレチクルステージＲＳＴは、レーザ干渉計（不図示）の計測値に基づいて、レチクルベース（不図示）上の光軸ＡＸに垂直な平面内でレチクルＲの移動又は位置決めを行う。一方、ウエハＷをウエハホルダ（不図示）を介して吸着保持するウエハステージＷＳＴは、レーザ干渉計（不図示）の計測値に基づいて、ウエハベースＷＢ上の光軸ＡＸに垂直な平面内で連続移動及びステップ移動を行う。また、ウエハステージＷＳＴには、不図示のオートフォーカスセンサの計測値に基づいて、ウエハＷの表面を投影光学系ＰＬの像面に合焦させるために、ウエハＷのフォーカス位置（光軸ＡＸ方向の位置）、及びθｘ方向、θｙ方向の傾斜角を制御するＺステージ機構も組み込まれている。 Next, the reticle stage RST that sucks and holds the reticle R moves or moves the reticle R in a plane perpendicular to the optical axis AX on the reticle base (not shown) based on the measurement value of the laser interferometer (not shown). Perform positioning. On the other hand, wafer stage WST for attracting and holding wafer W via a wafer holder (not shown) is continuous in a plane perpendicular to optical axis AX on wafer base WB based on the measurement value of a laser interferometer (not shown). Move and step move. Further, the wafer stage WST has a focus position (in the optical axis AX direction) of the wafer W in order to focus the surface of the wafer W on the image plane of the projection optical system PL based on a measurement value of an autofocus sensor (not shown). And a Z stage mechanism for controlling the inclination angle in the θx direction and the θy direction is also incorporated.

露光時には、主制御系１１内の露光制御部の制御のもとで不図示のアライメント系によってレチクルＲとウエハＷとのアライメントが行われた後、偏光状態可変部３によって照明光ＩＬの偏光状態が所定状態に設定される。その後、露光光源１の発光を開始して、レチクルＲのパターンを一括露光方式又は走査露光方式で投影光学系ＰＬを介してウエハＷ上の１つのショット領域に転写する動作と、露光光源１の発光を停止して、ウエハＷをステップ移動する動作とが繰り返される。これによって、ウエハＷ上の全部のショット領域にレチクルＲのパターン像が転写される。また、本実施形態の露光装置が米国特許出願公開第２００５／２５９２３４号明細書に示すような液浸型である場合には、投影光学系ＰＬとウエハＷとの間に不図示の液体供給機構から純水等の液体が供給される。 At the time of exposure, the alignment of the reticle R and the wafer W is performed by an alignment system (not shown) under the control of the exposure control unit in the main control system 11, and then the polarization state of the illumination light IL by the polarization state variable unit 3 Is set to a predetermined state. Thereafter, the light emission of the exposure light source 1 is started, and the operation of transferring the pattern of the reticle R to one shot area on the wafer W via the projection optical system PL by the batch exposure method or the scanning exposure method, The operation of stopping the light emission and moving the wafer W stepwise is repeated. As a result, the pattern image of the reticle R is transferred to all shot areas on the wafer W. In addition, when the exposure apparatus of the present embodiment is an immersion type as shown in US Patent Application Publication No. 2005/259234, a liquid supply mechanism (not shown) is provided between the projection optical system PL and the wafer W. From which liquid such as pure water is supplied.

さて、このような露光に際しては、投影光学系ＰＬの光学特性としての結像特性が所定の状態に調整されている必要がある。そのためには、その結像特性を高精度に計測する必要がある。本実施形態の露光装置ＥＸは、投影光学系ＰＬの結像特性としての波面収差を計測するための波面収差計測装置２０を備えている。波面収差計測装置２０は、レチクルステージＲＳＴの上方、すなわち、本実施形態では、照明光学系ＩＬＳとレチクルステージＲＳＴの間に移動可能に配置され、投影光学系ＰＬの波面収差情報を含む検出信号を得る計測系２１と、テストレチクルＲ１と、テストレチクルＲ１を照明光ＩＬで照明する照明系と、ウエハステージＷＳＴに設けられた反射部材２２と、計測系２１の検出信号を処理して投影光学系ＰＬの波面収差を求める計測部（演算制御部）１７とを備えている。 In such exposure, it is necessary that the imaging characteristics as the optical characteristics of the projection optical system PL are adjusted to a predetermined state. For this purpose, it is necessary to measure the imaging characteristics with high accuracy. The exposure apparatus EX of the present embodiment includes a wavefront aberration measuring apparatus 20 for measuring wavefront aberration as an imaging characteristic of the projection optical system PL. The wavefront aberration measuring device 20 is arranged so as to be movable above the reticle stage RST, that is, in this embodiment, between the illumination optical system ILS and the reticle stage RST, and receives a detection signal including wavefront aberration information of the projection optical system PL. A measurement system 21, a test reticle R1, an illumination system that illuminates the test reticle R1 with illumination light IL, a reflection member 22 provided on the wafer stage WST, and a detection signal of the measurement system 21 to process the projection optical system A measurement unit (calculation control unit) 17 for obtaining the wavefront aberration of PL is provided.

本実施形態では、その照明系として照明光学系ＩＬＳが兼用されているが、専用の照明系を設けてもよい。計測部１７は、求めた波面収差の情報を主制御系１１内の結像特性制御部に供給する。その結像特性制御部は、計測部１７から供給される波面収差が目標範囲内に維持されるように、駆動系１２を介してレンズエレメント１４Ａ，１４Ｂ等を駆動する。なお、反射部材２２は、ウエハステージＷＳＴとは独立にウエハベースＷＢ上を移動する計測ステージ等（不図示）に設けてもよい。 In this embodiment, the illumination optical system ILS is also used as the illumination system, but a dedicated illumination system may be provided. The measurement unit 17 supplies the obtained wavefront aberration information to the imaging characteristic control unit in the main control system 11. The imaging characteristic control unit drives the lens elements 14A, 14B and the like via the drive system 12 so that the wavefront aberration supplied from the measurement unit 17 is maintained within the target range. The reflecting member 22 may be provided on a measurement stage (not shown) that moves on the wafer base WB independently of the wafer stage WST.

投影光学系ＰＬの波面収差計測時には、レチクルステージＲＳＴにレチクルＲの代わりにテストレチクルＲ１がロードされ、計測系２１がレチクルステージＲＳＴ上に移動し、投影光学系ＰＬの露光領域にウエハステージＷＳＴの反射部材２２が移動する。図１（Ｂ）に示すように、テストレチクルＲ１のパターン領域の遮光膜中には、Ｘ方向、Ｙ方向に所定間隔で複数の波面収差計測用の円形の計測用開口１９が形成されている。計測用開口１９の直径は例えば４０μｍ程度である。なお、テストレチクルＲ１の代わりに、レチクルステージＲＳＴのレチクルＲの近傍に固定されるレチクルマーク板等（不図示）に、計測用開口１９を形成してもよい。 When measuring the wavefront aberration of the projection optical system PL, the test reticle R1 is loaded on the reticle stage RST instead of the reticle R, the measurement system 21 is moved onto the reticle stage RST, and the wafer stage WST is exposed to the exposure area of the projection optical system PL. The reflection member 22 moves. As shown in FIG. 1B, a plurality of circular measurement openings 19 for measuring wavefront aberration are formed at predetermined intervals in the X and Y directions in the light shielding film in the pattern region of the test reticle R1. . The diameter of the measurement opening 19 is, for example, about 40 μm. Instead of the test reticle R1, the measurement opening 19 may be formed on a reticle mark plate or the like (not shown) fixed in the vicinity of the reticle R of the reticle stage RST.

反射部材２２の上面はウエハＷの表面と同じ高さに設定されている。反射部材２２は例えば照明光ＩＬを透過するガラス板より形成され、その裏面には照明光ＩＬに対する反射率の低い吸収膜（又は遮光膜）が形成されている。そして、反射部材２２の上面に照明光ＩＬに対して高反射率の金属（例えばクロム等）の膜よりなる円形の微小ミラー２３と、反射拡散球面２４とが隣接して形成されている。微小ミラー２３の投影光学系ＰＬによる物体面側への像２３Ｒ（図２（Ｂ）参照）の直径は、計測用開口１９の直径よりも小さく、例えばその直径の１／２程度である。 The upper surface of the reflecting member 22 is set to the same height as the surface of the wafer W. The reflecting member 22 is formed of, for example, a glass plate that transmits the illumination light IL, and an absorption film (or a light shielding film) having a low reflectance with respect to the illumination light IL is formed on the back surface thereof. A circular micromirror 23 made of a film of a metal having a high reflectivity with respect to the illumination light IL (for example, chromium) and a reflection diffusing spherical surface 24 are formed adjacent to each other on the upper surface of the reflection member 22. The diameter of the image 23R on the object plane side by the projection optical system PL of the micromirror 23 (see FIG. 2B) is smaller than the diameter of the measurement aperture 19, and is, for example, about ½ of the diameter.

後述の図３（Ｃ）に示すように、反射拡散球面２４は、凹の半球面の表面をすりガラス面のように粗く表面加工し、その表面に照明光ＩＬに対して高反射率の金属膜を蒸着したものである。反射拡散球面２４は、入射する照明光をそれぞれほぼ所定の拡散角φｄｆ（ｒａｄ）で拡散する。反射拡散球面２４の半径をｒｄｆとすると、反射拡散球面２４の中心における反射拡散球面２４からの拡散光（反射光）の像２４Ｄの直径Ｄｄｆはほぼ２ｒｄｆ・φｄｆとなる。その像２４Ｄの直径Ｄｄｆは計測用開口１９の像１９Ｗの直径よりも大きく、例えば次のようにその直径の２倍程度である。反射拡散球面２４の半径ｒｄｆは例えば数ｍｍ程度である。 As shown in FIG. 3C described later, the reflection diffusing spherical surface 24 has a concave hemispherical surface roughened like a ground glass surface, and a metal film having a high reflectance with respect to the illumination light IL on the surface. Are vapor-deposited. The reflection diffusing spherical surface 24 diffuses incident illumination light at a substantially predetermined diffusion angle φdf (rad). When the radius of the reflection diffusion spherical surface 24 is rdf, the diameter Ddf of the diffused light (reflected light) image 24D from the reflection diffusion spherical surface 24 at the center of the reflection diffusion spherical surface 24 is approximately 2rdf · φdf. The diameter Ddf of the image 24D is larger than the diameter of the image 19W of the measurement opening 19, and is, for example, about twice the diameter as follows. The radius rdf of the reflective diffusion spherical surface 24 is, for example, about several mm.

Ｄｄｆ≒２×ｒｄｆ×φｄｆ≒像１９Ｗの直径の２倍 …（１）
また、像２４Ｄは、投影光学系ＰＬの開口数で定まる開き角の照明光ＩＬによって形成される像１９Ｗからの光束をさらに拡散した光束の像（一種の面光源）である。従って、像２４Ｄを形成する光束の開き角（開口数）は、投影光学系ＰＬの開口数で定まる開き角よりも大きくなっているため、その光束を用いて後述のように計測系２１の波面を高精度に計測できる。 Ddf≈2 × rdf × φdf≈twice the diameter of the image 19W (1)
The image 24D is a light beam image (a kind of surface light source) obtained by further diffusing a light beam from the image 19W formed by the illumination light IL having an opening angle determined by the numerical aperture of the projection optical system PL. Accordingly, the opening angle (numerical aperture) of the light beam forming the image 24D is larger than the opening angle determined by the numerical aperture of the projection optical system PL, so that the wavefront of the measurement system 21 is described below using the light beam. Can be measured with high accuracy.

図２（Ａ）は、波面収差計測時の図１の投影光学系ＰＬと波面収差計測装置２０の各部材との位置関係の一例を示す。図２（Ａ）において、投影光学系ＰＬの上方に順次テストレチクルＲ１及び計測系２１のビームスプリッタ３２が配置され、図１の照明光学系ＩＬＳからの照明光ＩＬで、ビームスプリッタ３２を介してテストレチクルＲ１が照明される。一例としてテストレチクルＲ１の光軸ＡＸ上にある計測用開口１９の投影光学系ＰＬによる像が反射部材２２上に投影される。そして、計測用開口１９の像内にウエハステージＷＳＴに設けた反射部材２２の微小ミラー２３が設置される。微小ミラー２３からの反射光ＩＬＲは、投影光学系ＰＬを介して、図２（Ｂ）に示すように、計測用開口１９内に微小ミラー２３の像２３Ｒ（一次像）を形成する。 FIG. 2A shows an example of the positional relationship between the projection optical system PL of FIG. 1 and each member of the wavefront aberration measuring apparatus 20 at the time of wavefront aberration measurement. 2A, a test reticle R1 and a beam splitter 32 of the measurement system 21 are sequentially disposed above the projection optical system PL. The illumination light IL from the illumination optical system ILS of FIG. The test reticle R1 is illuminated. As an example, an image by the projection optical system PL of the measurement aperture 19 on the optical axis AX of the test reticle R1 is projected onto the reflecting member 22. Then, a minute mirror 23 of the reflecting member 22 provided on the wafer stage WST is installed in the image of the measurement opening 19. The reflected light ILR from the micromirror 23 forms an image 23R (primary image) of the micromirror 23 in the measurement aperture 19 as shown in FIG. 2B via the projection optical system PL.

図２（Ａ）において、計測用開口１９を通過した反射光ＩＬＲがビームスプリッタ３２に向かう。計測系２１は、ビームスプリッタ３２と、投影光学系ＰＬを介して計測用開口１９を通過した反射光ＩＬＲのうち、ビームスプリッタ３２で反射された光束（これも反射光ＩＬＲと呼ぶ）をほぼ平行光束に変換する対物レンズ３３とを有する。さらに、計測系２１は、対物レンズ３３からの光束の波面を分割するように多数の微小レンズ３４ａがＹ方向及びＺ方向（投影光学系ＰＬの瞳面におけるＸ方向に対応する方向）に密着して配置されたマイクロレンズアレイ３４と、多数の微小レンズ３４ａによって形成される多数のスポット光（微小ミラー２３の二次像）を受光するＣＣＤ型又はＣＭＯＳ型等の２次元の撮像素子３５とを有する。さらに、計測系２１は、ビームスプリッタ３２、対物レンズ３３、マイクロレンズアレイ３４、及び撮像素子３５を保持する移動可能な保持部材３１を有する。対物レンズ３３の前側焦点に計測用開口１９の中心が配置され、撮像素子３５の検出信号が計測部１７に供給されている。 In FIG. 2A, the reflected light ILR that has passed through the measurement opening 19 is directed to the beam splitter 32. The measurement system 21 substantially parallels the light beam reflected by the beam splitter 32 (also referred to as reflected light ILR) among the reflected light ILR that has passed through the measurement aperture 19 via the beam splitter 32 and the projection optical system PL. And an objective lens 33 that converts light into a light beam. Further, in the measurement system 21, a large number of microlenses 34a are in close contact with each other in the Y direction and the Z direction (the direction corresponding to the X direction on the pupil plane of the projection optical system PL) so as to divide the wavefront of the light beam from the objective lens 33. And a two-dimensional imaging element 35 such as a CCD type or a CMOS type that receives a large number of spot lights (secondary images of the minute mirror 23) formed by a large number of minute lenses 34a. Have. Further, the measurement system 21 includes a movable holding member 31 that holds the beam splitter 32, the objective lens 33, the microlens array 34, and the imaging element 35. The center of the measurement aperture 19 is disposed at the front focal point of the objective lens 33, and the detection signal of the image sensor 35 is supplied to the measurement unit 17.

保持部材３１のビームスプリッタ３２の上下の面に対向する位置には、照明光ＩＬを通過させる開口が形成されている。保持部材３１は、駆動部３６を介してガイド部材３７に沿ってＸ方向に移動可能である。さらにガイド部材３７は、全体として不図示のガイド部材に沿ってＹ方向に移動可能である。従って、計測系２１（保持部材３１）を駆動部３６を介してＸ方向、Ｙ方向に移動することによって、ビームスプリッタ３２をテストレチクルＲ１の任意の計測対象の計測用開口１９の上方に設置可能である。 An opening through which the illumination light IL passes is formed at a position facing the upper and lower surfaces of the beam splitter 32 of the holding member 31. The holding member 31 is movable in the X direction along the guide member 37 via the drive unit 36. Further, the guide member 37 is movable in the Y direction along a guide member (not shown) as a whole. Accordingly, by moving the measurement system 21 (holding member 31) in the X direction and the Y direction via the drive unit 36, the beam splitter 32 can be installed above the measurement opening 19 of an arbitrary measurement target of the test reticle R1. It is.

上述のように、計測系２１において、対物レンズ３３及びマイクロレンズアレイ３４によって撮像素子３５上に微小ミラー２３の多数の二次像が形成される。その多数の二次像の位置は、投影光学系ＰＬの瞳面における波面が点線で示す波面Ａ１又は実線で示す波面Ａ２等のいずれであるかに応じて変化する。従って、その多数の二次像の方向及び横ずれ量から反射光ＩＬＲの波面を求めることができる。このように波面収差を求める方法は、例えば特開２００２−７１５１４号公報にも開示されている。 As described above, in the measurement system 21, a large number of secondary images of the micromirror 23 are formed on the image sensor 35 by the objective lens 33 and the microlens array 34. The positions of the multiple secondary images vary depending on whether the wavefront on the pupil plane of the projection optical system PL is a wavefront A1 indicated by a dotted line, a wavefront A2 indicated by a solid line, or the like. Therefore, the wavefront of the reflected light ILR can be obtained from the directions and lateral shift amounts of the many secondary images. Such a method for obtaining wavefront aberration is also disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-71514.

なお、計測系２１自体の波面収差が無視できる場合には、計測系２１を介して計測される波面（波面収差）がそのまま投影光学系ＰＬの波面（波面収差）となる。しかしながら、実際には、計測系２１のビームスプリッタ３２、対物レンズ３４、及びマイクロレンズアレイ３４等にも僅かではあるが波面収差がある。従って、波面収差計測装置２０を用いて投影光学系ＰＬの波面収差を計測する場合には、予め計測系２１のみの波面収差（又は計測系２１のみに起因する反射光ＩＬＲの波面の状態）を計測しておく必要がある。このように計測系２１のみの波面収差（又は波面）を計測することが、波面収差計測装置２０の校正（キャリブレーション）である。 If the wavefront aberration of the measurement system 21 itself can be ignored, the wavefront (wavefront aberration) measured via the measurement system 21 becomes the wavefront (wavefront aberration) of the projection optical system PL as it is. However, actually, the beam splitter 32, the objective lens 34, the microlens array 34, and the like of the measurement system 21 have a slight wavefront aberration. Therefore, when the wavefront aberration of the projection optical system PL is measured using the wavefront aberration measuring apparatus 20, the wavefront aberration of only the measurement system 21 (or the state of the wavefront of the reflected light ILR caused by only the measurement system 21) is previously measured. It is necessary to measure. Measuring the wavefront aberration (or wavefront) of only the measurement system 21 in this way is calibration of the wavefront aberration measuring apparatus 20.

本実施形態では、波面収差計測装置２０の校正時には、図３（Ａ）に示すように、投影光学系ＰＬの像面において、計測用開口１９の中心と投影光学系ＰＬに関して共役な位置に反射部材２２の反射拡散球面２４の中心が設置される。この状態で、計測系２１によって反射光ＩＬＲの波面が計測される。
以下、波面収差計測装置２０の校正時の動作の一例につき図４（Ａ）のフローチャートを参照して説明する。この動作は主制御系１１及び計測部１７によって制御されるとともに、例えば露光工程中に定期的に実行される。 In the present embodiment, at the time of calibration of the wavefront aberration measuring apparatus 20, as shown in FIG. 3A, reflection is performed at a conjugate position with respect to the center of the measurement aperture 19 and the projection optical system PL on the image plane of the projection optical system PL. The center of the reflection diffusion spherical surface 24 of the member 22 is set. In this state, the wavefront of the reflected light ILR is measured by the measurement system 21.
Hereinafter, an example of the operation at the time of calibration of the wavefront aberration measuring apparatus 20 will be described with reference to the flowchart of FIG. This operation is controlled by the main control system 11 and the measurement unit 17 and is periodically executed, for example, during the exposure process.

まず、図４（Ａ）のステップ１０１において、図１（Ａ）のレチクルステージＲＳＴ上にテストレチクルＲ１をロードし、図３（Ａ）に示すように、投影光学系ＰＬの物体面の照明領域内の例えば光軸ＡＸ上（光軸ＡＸ外でもよい）の計測用開口１９を照明対象とする。次のステップ１０２において、駆動部３６を介して、計測用開口１９の上方に計測系２１のビームスプリッタ３２を配置し、照明光学系ＩＬＳからの照明光ＩＬでビームスプリッタ３２を介して計測用開口１９を照明する。照明光学系ＩＬＳは通常の照明条件で、コヒーレンスファクタ（σ値）が例えば最大に設定される。これによって、計測用開口１９の投影光学系ＰＬによる像１９Ｗが、投影光学系ＰＬの像面の露光領域内に形成される。 First, in step 101 of FIG. 4A, the test reticle R1 is loaded on the reticle stage RST of FIG. 1A, and as shown in FIG. 3A, the illumination area of the object plane of the projection optical system PL is loaded. For example, the measurement opening 19 on the optical axis AX (may be outside the optical axis AX) is an illumination target. In the next step 102, the beam splitter 32 of the measurement system 21 is disposed above the measurement aperture 19 via the driving unit 36, and the measurement aperture is transmitted via the beam splitter 32 with the illumination light IL from the illumination optical system ILS. 19 is illuminated. The illumination optical system ILS is set to a maximum coherence factor (σ value), for example, under normal illumination conditions. Thereby, an image 19W of the measurement aperture 19 by the projection optical system PL is formed in the exposure area of the image plane of the projection optical system PL.

これとほぼ並行して、ステップ１０３において、ウエハステージＷＳＴを駆動し、反射部材２２の反射拡散球面２４（反射拡散面）の中心を投影光学系ＰＬの像面の像１９Ｗの位置に設置する。このとき、図３（Ｃ）に拡大して示すように、その像１９Ｗからの照明光ＩＬは、反射拡散球面２４で拡散され、像１９Ｗを覆うように拡散光の像２４Ｄを形成する。従って、反射拡散球面２４からの反射光ＩＬＲは、投影光学系ＰＬを介して、図３（Ｂ）に示すように、テストレチクルＲ１の計測用開口１９を覆うように像２４Ｒを形成する。像２４Ｒを形成する光束は投影光学系ＰＬの物体面側の開口数で定まる広い開き角をほぼ有している。また、像２４Ｒの一部の領域（計測用開口１９内の領域）は、実質的に投影光学系ＰＬの波面収差情報を含まない面光源とみなすことができる。 In parallel with this, in step 103, wafer stage WST is driven, and the center of reflection diffusing spherical surface 24 (reflection diffusing surface) of reflecting member 22 is set at the position of image 19W on the image plane of projection optical system PL. At this time, as shown in an enlarged view in FIG. 3C, the illumination light IL from the image 19W is diffused by the reflection diffusion spherical surface 24 to form an image 24D of diffused light so as to cover the image 19W. Accordingly, the reflected light ILR from the reflection diffusing spherical surface 24 forms an image 24R through the projection optical system PL so as to cover the measurement opening 19 of the test reticle R1, as shown in FIG. 3B. The light beam forming the image 24R has a wide opening angle determined by the numerical aperture on the object plane side of the projection optical system PL. Further, a partial region of the image 24R (region in the measurement aperture 19) can be regarded as a surface light source that substantially does not include wavefront aberration information of the projection optical system PL.

そして、ステップ１０４において、図３（Ａ）の反射拡散球面２４で反射され、投影光学系ＰＬを介して計測用開口１９上に像２４Ｒを形成する反射光ＩＬＲのうち、計測用開口１９を通過した光束の一部を、計測系２１のビームスプリッタ３２、対物レンズ３３、及びマイクロレンズアレイ３４を介して撮像素子３５で受光する。次のステップ１０５において、計測部１７は、撮像素子３５の検出信号を処理して投影光学系ＰＬの波面収差に影響されない計測系２１の波面収差のみに起因する波面ＷＡ１を求め、この波面（位相分布）ＷＡ１を内部の記憶部に記憶する。 In step 104, the reflected light ILR reflected by the reflection diffusing spherical surface 24 of FIG. 3A and forming the image 24R on the measurement aperture 19 through the projection optical system PL passes through the measurement aperture 19. A part of the luminous flux is received by the image sensor 35 through the beam splitter 32, the objective lens 33, and the microlens array 34 of the measurement system 21. In the next step 105, the measurement unit 17 processes the detection signal of the image sensor 35 to obtain the wavefront WA1 caused only by the wavefront aberration of the measurement system 21 that is not affected by the wavefront aberration of the projection optical system PL, and this wavefront (phase Distribution) WA1 is stored in the internal storage unit.

その後、ステップ１０６において、照明光ＩＬの照射を停止させ、反射部材２２（反射拡散球面２４）を照明光ＩＬの光路から退避させることで、波面収差計測装置２０の校正が終了する。
その後、図１（Ａ）の露光装置ＥＸを用いた露光工程中で投影光学系ＰＬの波面収差を計測する場合の動作の一例につき、図４（Ｂ）のフローチャートを参照して説明する。まず、ステップ１１１において、ステップ１０１と同様に、レチクルステージＲＳＴ上にテストレチクルＲ１をロードし、図２（Ａ）に示すように、投影光学系ＰＬの物体面の計測用開口１９を照明対象とする。次のステップ１１２において、ステップ１０２と同様に、照明光ＩＬでビームスプリッタ３２を介して計測用開口１９を照明し、投影光学系ＰＬの像面に計測用開口１９の像を形成する。 Thereafter, in step 106, the irradiation of the illumination light IL is stopped, and the reflection member 22 (the reflection diffusing spherical surface 24) is retracted from the optical path of the illumination light IL, thereby completing the calibration of the wavefront aberration measuring apparatus 20.
Thereafter, an example of the operation when measuring the wavefront aberration of the projection optical system PL during the exposure process using the exposure apparatus EX of FIG. 1A will be described with reference to the flowchart of FIG. First, in step 111, as in step 101, the test reticle R1 is loaded on the reticle stage RST, and as shown in FIG. 2A, the measurement aperture 19 on the object plane of the projection optical system PL is set as an illumination target. To do. In the next step 112, as in step 102, the measurement aperture 19 is illuminated with the illumination light IL via the beam splitter 32, and an image of the measurement aperture 19 is formed on the image plane of the projection optical system PL.

これとほぼ並行して、ステップ１１３において、ウエハステージＷＳＴを駆動し、反射部材２２の微小ミラー２３の中心を計測用開口１９の像の中心に配置する。このとき、微小ミラー２３は計測用開口１９の像よりも小さいため、微小ミラー２３の全面が照明光ＩＬで照明される。そして、微小ミラー２３からの反射光ＩＬＲは、投影光学系ＰＬを介して、図２（Ｂ）に示すように、テストレチクルＲ１の計測用開口１９内に像２３Ｒを形成する。この像２３Ｒを形成する光束は投影光学系ＰＬの波面収差情報を含んでいる。 In parallel with this, in step 113, wafer stage WST is driven, and the center of micromirror 23 of reflecting member 22 is placed at the center of the image of measurement opening 19. At this time, since the micromirror 23 is smaller than the image of the measurement opening 19, the entire surface of the micromirror 23 is illuminated with the illumination light IL. Then, the reflected light ILR from the minute mirror 23 forms an image 23R in the measurement opening 19 of the test reticle R1, as shown in FIG. 2B, via the projection optical system PL. The light beam forming this image 23R includes the wavefront aberration information of the projection optical system PL.

そして、ステップ１１４において、図２（Ａ）の微小ミラー２３で反射され、投影光学系ＰＬを介して計測用開口１９中に像２３Ｒを形成する反射光ＩＬＲは、計測用開口１９を通過する。そして、計測用開口１９を通過した光束の一部を、計測系２１のビームスプリッタ３２、対物レンズ３３、及びマイクロレンズアレイ３４を介して撮像素子３５で受光する。次のステップ１１５において、計測部１７は、撮像素子３５の検出信号を処理して、投影光学系ＰＬ及び計測系２１の波面収差を含む波面ＷＡ２を求める。この後、照明光ＩＬの照射が停止され、計測系２１及び反射部材２２（微小ミラー２３）を照明光ＩＬの光路から退避させる。 Then, in step 114, the reflected light ILR reflected by the micro mirror 23 in FIG. 2A and forming the image 23R in the measurement aperture 19 through the projection optical system PL passes through the measurement aperture 19. Then, a part of the light beam that has passed through the measurement opening 19 is received by the imaging device 35 via the beam splitter 32, the objective lens 33, and the microlens array 34 of the measurement system 21. In the next step 115, the measurement unit 17 processes the detection signal of the image sensor 35 to obtain the wavefront WA <b> 2 including the wavefront aberration of the projection optical system PL and the measurement system 21. Thereafter, the irradiation of the illumination light IL is stopped, and the measurement system 21 and the reflection member 22 (micromirror 23) are retracted from the optical path of the illumination light IL.

次のステップ１１６において、計測部１７は、ステップ１１５で求めた波面ＷＡ２からステップ１０５で記憶した計測系２１の波面ＷＡ１を差し引いて、次のように投影光学系ＰＬの波面収差のみに起因する波面ＷＡ３を求める。波面ＷＡ３は記憶部に記憶される。
ＷＡ３＝ＷＡ２−ＷＡ１ …（２）
次のステップ１１７において、計測部１７は、波面ＷＡ３から例えばゼルニケ多項式の係数の形で投影光学系ＰＬの波面収差を求める。この波面収差の情報は主制御系１１に供給される。次のステップ１１８において、主制御系１１の結像特性制御部は、駆動系１２を介して投影光学系ＰＬの波面収差を補正する。その後、レチクルステージＲＳＴにレチクルＲがロードされ、ウエハステージＷＳＴに順次ロードされる複数のウエハの各ショット領域にレチクルＲのパターンの像が露光される。この際に、投影光学系ＰＬの波面収差が補正されているため、常に高精度にレチクルＲのパターンの像を投影光学系ＰＬを介してウエハ上に露光できる。 In the next step 116, the measurement unit 17 subtracts the wavefront WA1 of the measurement system 21 stored in step 105 from the wavefront WA2 obtained in step 115, and the wavefront caused only by the wavefront aberration of the projection optical system PL as follows. Find WA3. The wavefront WA3 is stored in the storage unit.
WA3 = WA2-WA1 (2)
In the next step 117, the measurement unit 17 obtains the wavefront aberration of the projection optical system PL from the wavefront WA3, for example, in the form of a coefficient of the Zernike polynomial. Information on the wavefront aberration is supplied to the main control system 11. In the next step 118, the imaging characteristic control unit of the main control system 11 corrects the wavefront aberration of the projection optical system PL via the drive system 12. Thereafter, reticle R is loaded onto reticle stage RST, and an image of the pattern of reticle R is exposed on each shot area of a plurality of wafers sequentially loaded onto wafer stage WST. At this time, since the wavefront aberration of the projection optical system PL is corrected, the pattern image of the reticle R can always be exposed onto the wafer via the projection optical system PL with high accuracy.

本実施形態の効果等は次の通りである。
（１）本実施形態の投影光学系ＰＬの波面収差（光学特性）を計測するための波面収差計測装置２０は、投影光学系ＰＬの物体面（第１面）に配置される計測用開口１９が形成されたテストレチクルＲ１（開口部材）と、テストレチクルＲ１を照明光ＩＬで照明する照明光学系ＩＬＳと、計測用開口１９及び投影光学系ＰＬを通過し、投影光学系ＰＬの像面（第２面）から戻された照明光ＩＬの少なくとも一部を投影光学系ＰＬ及び計測用開口１９を介して受光して、投影光学系ＰＬの波面収差情報を計測する計測系２１とを備えている。さらに、波面収差計測装置２０は、照明光ＩＬの光路中に挿入又は離脱可能に配置され、かつ計測用開口１９を通過した照明光ＩＬの少なくとも一部を反射し、さらに該反射した光束で計測用開口１９を含む領域（像２４Ｒ）を照明する反射部材２２に形成された反射拡散球面２４（第１反射光学系）と、計測用開口１９を通過した光束（計測光）を計測系２１で受光し、計測系２１の波面ＷＡ１を求める計測部１７（計測装置）と、を備えている。 The effects and the like of this embodiment are as follows.
(1) The wavefront aberration measuring apparatus 20 for measuring the wavefront aberration (optical characteristics) of the projection optical system PL of the present embodiment is a measurement aperture 19 disposed on the object plane (first surface) of the projection optical system PL. Pass through the test reticle R1 (opening member), the illumination optical system ILS that illuminates the test reticle R1 with the illumination light IL, the measurement aperture 19 and the projection optical system PL, and the image plane of the projection optical system PL ( A measurement system 21 that receives at least a part of the illumination light IL returned from the second surface) via the projection optical system PL and the measurement aperture 19 and measures the wavefront aberration information of the projection optical system PL. Yes. Further, the wavefront aberration measuring device 20 is disposed so as to be inserted into or removed from the optical path of the illumination light IL, reflects at least a part of the illumination light IL that has passed through the measurement aperture 19, and further measures with the reflected light beam. The reflection system 22 (first reflection optical system) formed on the reflection member 22 that illuminates the region (image 24R) including the measurement aperture 19 and the light beam (measurement light) that has passed through the measurement aperture 19 are measured by the measurement system 21. A measuring unit 17 (measuring device) that receives the light and obtains the wavefront WA1 of the measuring system 21.

また、波面収差計測装置２０の校正方法は、テストレチクルＲ１の計測用開口１９を投影光学系ＰＬの物体面に配置するステップ１０１と、照明光ＩＬで計測用開口１９を照明するステップ１０２と、照明光ＩＬの光路中に計測用開口１９を通過した照明光ＩＬの大部分（一部でもよい）を反射する反射拡散球面２４を挿入するステップ１０３と、反射拡散球面２４からの反射光ＩＬＲで投影光学系ＰＬを介して計測用開口１９を含む領域を照明する工程（ステップ１０４の前半部）と、計測用開口１９を通過した光束を計測系２１で受光し、計測系２１の波面ＷＡ１を求める工程（ステップ１０４の後半部及びステップ１０５）とを含んでいる。 The calibration method of the wavefront aberration measuring apparatus 20 includes a step 101 in which the measurement aperture 19 of the test reticle R1 is disposed on the object plane of the projection optical system PL, a step 102 in which the measurement aperture 19 is illuminated with the illumination light IL, Step 103 for inserting a reflection diffusion spherical surface 24 that reflects most (or part of) the illumination light IL that has passed through the measurement aperture 19 in the optical path of the illumination light IL, and reflected light ILR from the reflection diffusion spherical surface 24 A step of illuminating a region including the measurement aperture 19 via the projection optical system PL (the first half of the step 104), a light beam that has passed through the measurement aperture 19 is received by the measurement system 21, and a wavefront WA1 of the measurement system 21 is obtained. The process to obtain (the latter half part of step 104 and step 105) is included.

本実施形態によれば、反射拡散球面２４からの反射光で計測用開口１９を含む領域（像２４Ｒ）を照明することができる。この場合、計測用開口１９を通過する光束は投影光学系ＰＬの波面収差情報を殆ど含まないため、その光束によって計測系２１で求められる波面ＷＡ１は、ほぼ計測系２１のみの波面収差情報を正確に含んでいる。従って、投影光学系ＰＬの物体面側に計測系２１を配置することと、波面収差計測装置２０の校正を高精度に行うこととを両立できる。 According to the present embodiment, it is possible to illuminate the region (image 24R) including the measurement opening 19 with the reflected light from the reflection diffusing spherical surface 24. In this case, since the light beam passing through the measurement aperture 19 contains almost no wavefront aberration information of the projection optical system PL, the wavefront WA1 obtained by the measurement system 21 with the light beam is almost exactly the wavefront aberration information of only the measurement system 21. Is included. Therefore, it is possible to achieve both the arrangement of the measurement system 21 on the object plane side of the projection optical system PL and the calibration of the wavefront aberration measuring apparatus 20 with high accuracy.

なお、計測用開口１９を投影光学系ＰＬの物体面の近傍に配置することも可能である。この場合には、例えば計測用開口１９の像の位置又はこの近傍に反射拡散球面２４の中心を配置することで、計測系２１内の光束の波面を高精度に計測できる。
（２）また、反射部材２２には、投影光学系ＰＬの像面に配置され、計測用開口１９及び投影光学系ＰＬを通過した照明光ＩＬの少なくとも一部を反射し、該反射した照明光で投影光学系ＰＬを介して計測用開口１９の内側の領域（像２３Ｒ）を照明する微小ミラー２３（第２反射光学系）が形成されている。 It is also possible to arrange the measurement aperture 19 in the vicinity of the object plane of the projection optical system PL. In this case, for example, the wavefront of the light beam in the measurement system 21 can be measured with high accuracy by disposing the center of the reflection diffusing spherical surface 24 at or near the position of the image of the measurement aperture 19.
(2) The reflecting member 22 is disposed on the image plane of the projection optical system PL, reflects at least part of the illumination light IL that has passed through the measurement aperture 19 and the projection optical system PL, and reflects the reflected illumination light. Thus, a minute mirror 23 (second reflection optical system) that illuminates a region (image 23R) inside the measurement opening 19 through the projection optical system PL is formed.

そして、波面収差計測装置２０を用いた計測方法（校正方法の一部とみなす）は、反射拡散球面２４を照明光ＩＬの光路から離脱するステップ１０６と、計測用開口１９を通過した照明光ＩＬを投影光学系ＰＬに入射させるステップ１１２と、投影光学系ＰＬを通過した照明光ＩＬの一部を微小ミラー２３で反射し、この反射光ＩＬＲで投影光学系ＰＬを介して計測用開口１９の内側の領域（像２３Ｒ）を照明するステップ１１３と、計測用開口１９の内側の領域を通過した光束（計測光）を計測系２１で受光し、計測部１７が計測系２１の検出信号からその光束の波面ＷＡ２を求め、波面ＷＡ２から波面ＷＡ１を差し引いて投影光学系ＰＬの波面ＷＡ３及び波面収差を求めるステップ１１５〜１１７とを含んでいる。 Then, the measurement method using the wavefront aberration measuring apparatus 20 (considered as a part of the calibration method) includes step 106 in which the reflection diffusion spherical surface 24 is separated from the optical path of the illumination light IL, and the illumination light IL that has passed through the measurement aperture 19. Is incident on the projection optical system PL, and a part of the illumination light IL that has passed through the projection optical system PL is reflected by the micromirror 23, and the reflected light ILR passes through the projection optical system PL and passes through the measurement aperture 19. The step 113 for illuminating the inner region (image 23R) and the light beam (measurement light) that has passed through the inner region of the measurement aperture 19 are received by the measurement system 21, and the measurement unit 17 detects the detection signal from the detection signal of the measurement system 21. And steps 115 to 117 for obtaining the wavefront WA2 of the light beam and subtracting the wavefront WA1 from the wavefront WA2 to obtain the wavefront WA3 and wavefront aberration of the projection optical system PL.

従って、波面収差計測装置２０の校正結果（計測系２１のみの波面ＷＡ１）を用いて計測結果（波面ＷＡ２）を補正することによって、投影光学系ＰＬのみの波面収差を高精度に求めることができる。
（３）また、本実施形態の露光装置ＥＸは、照明光ＩＬでレチクルＲのパターンを照明し、照明光ＩＬでそのパターン及び投影光学系ＰＬを介してウエハステージＷＳＴで保持されたウエハＷ（物体）を露光する露光装置において、投影光学系ＰＬの波面収差を計測するために波面収差計測装置２０を備えている。この際に、波面収差計測装置２０の校正を高精度に行うことができるため、この校正結果を用いて投影光学系ＰＬの波面収差を高精度に計測でき、レチクルＲのパターンの像を高精度にウエハＷ上に露光できる。 Therefore, by correcting the measurement result (wavefront WA2) using the calibration result of the wavefront aberration measuring apparatus 20 (the wavefront WA1 of only the measurement system 21), the wavefront aberration of only the projection optical system PL can be obtained with high accuracy. .
(3) In addition, the exposure apparatus EX of the present embodiment illuminates the pattern of the reticle R with the illumination light IL, and the wafer W (held on the wafer stage WST via the pattern and the projection optical system PL with the illumination light IL. An exposure apparatus that exposes an object) includes a wavefront aberration measuring device 20 for measuring the wavefront aberration of the projection optical system PL. At this time, since the wavefront aberration measuring apparatus 20 can be calibrated with high accuracy, the wavefront aberration of the projection optical system PL can be measured with high accuracy by using the calibration result, and the pattern image of the reticle R can be highly accurate. The wafer W can be exposed.

さらに、波面収差計測装置２０のうちでウエハステージＷＳＴ側にあるのは反射部材２２のみであるため、ウエハステージＷＳＴの構成を簡素できる。従って、ウエハステージＷＳＴには例えば照明光ＩＬの露光量モニタ、及びレチクルＲのアライメントマークの計測系（空間像計測系）等を余裕を持って配置可能である。
また、露光装置ＥＸによる露光方法は、本実施形態の波面収差計測装置２０の校正方法を用いて、投影光学系ＰＬの光学特性を計測する波面収差計測装置２０の校正を行うものである。この場合にも、校正後の波面収差計測装置２０を用いて、投影光学系ＰＬの波面収差を高精度に計測できる。 Furthermore, since only the reflecting member 22 is on the wafer stage WST side in the wavefront aberration measuring apparatus 20, the configuration of the wafer stage WST can be simplified. Therefore, for example, an exposure amount monitor of the illumination light IL and an alignment mark measurement system (aerial image measurement system) of the reticle R can be disposed with sufficient margin on the wafer stage WST.
Moreover, the exposure method by the exposure apparatus EX calibrates the wavefront aberration measuring apparatus 20 that measures the optical characteristics of the projection optical system PL using the calibration method of the wavefront aberration measuring apparatus 20 of the present embodiment. Also in this case, the wavefront aberration of the projection optical system PL can be measured with high accuracy using the wavefront aberration measuring apparatus 20 after calibration.

なお、上記の実施形態では、次のような変形が可能である。
（１）上記の実施形態では、反射部材２２はウエハステージＷＳＴに設けられ、校正用の反射拡散球面２４は投影光学系ＰＬの像面又はこの近傍に配置される。しかしながら、図３（Ａ）に２点鎖線で示すように、テストレチクルＲ１のパターン面の下方近傍に反射拡散球面２４０が形成された反射部材２２０を移動可能に設置してもよい。反射拡散球面２４０は、反射拡散球面２４を投影光学系ＰＬの投影倍率βの逆数倍で大きくしたものである。波面収差計測装置２０の校正時には、計測用開口１９の直下に反射拡散球面２４０を配置することで、ビームスプリッタ３２を介して計測用開口１９を通過した照明光ＩＬは、反射拡散球面２４０で反射されて計測用開口１９を含む領域（計測用開口１９に対して直径がほぼ２倍の領域）を照明する。従って、反射拡散球面２４０で反射され、計測用開口１９を通過した光束の波面を計測系２１で計測することによって、上記の実施形態と同様に計測系２１のみの波面を高精度に求めることができる。 In the above embodiment, the following modifications are possible.
(1) In the above embodiment, the reflecting member 22 is provided on the wafer stage WST, and the calibration reflection diffusing spherical surface 24 is disposed on the image plane of the projection optical system PL or in the vicinity thereof. However, as indicated by a two-dot chain line in FIG. 3A, a reflecting member 220 having a reflecting diffusion spherical surface 240 formed in the vicinity of the lower side of the pattern surface of the test reticle R1 may be movably installed. The reflection diffusing spherical surface 240 is obtained by increasing the reflection diffusing spherical surface 24 by a reciprocal number times the projection magnification β of the projection optical system PL. When the wavefront aberration measuring apparatus 20 is calibrated, the illumination light IL that has passed through the measurement aperture 19 via the beam splitter 32 is reflected by the reflection diffusion spherical surface 240 by disposing the reflection diffusion spherical surface 240 directly below the measurement aperture 19. Then, an area including the measurement opening 19 (an area having a diameter approximately twice that of the measurement opening 19) is illuminated. Therefore, by measuring the wavefront of the light beam reflected by the reflection diffusing spherical surface 240 and passing through the measurement opening 19 with the measurement system 21, the wavefront of only the measurement system 21 can be obtained with high accuracy as in the above embodiment. it can.

また、投影光学系ＰＬの像面側の反射部材２２には微小ミラー２３のみを形成すればよいため、反射部材２２を小型化でき、ウエハステージＷＳＴをより簡素化できる。
（２）上記の実施形態では、波面収差計測装置２０の校正時に計測用開口１９の像の位置に反射拡散球面２４を配置している。しかしながら、反射拡散球面２４の代わりに、図５に示す反射系５１を用いてもよい。反射系５１は、図３（Ａ）の投影光学系ＰＬからの照明光ＩＬを集光する集光レンズ５２と、集光レンズ５２で集光された照明光ＩＬの少なくとも一部を拡散して反射光ＩＬＲとして集光レンズ５２に戻す反射拡散板５３とを有する。この場合、反射拡散板５３における拡散角をφｄｆ、集光レンズ５２の焦点距離をｒｄｆとすると、反射光ＩＬＲの集光レンズ５２による像５１Ｄの大きさは、図３（Ｃ）の反射拡散球面２４からの反射光ＩＬＲの像２４Ｄと同じ大きさに拡大される。 Further, since only the minute mirror 23 needs to be formed on the reflecting member 22 on the image plane side of the projection optical system PL, the reflecting member 22 can be reduced in size, and the wafer stage WST can be further simplified.
(2) In the above embodiment, the reflection diffusing spherical surface 24 is disposed at the position of the image of the measurement aperture 19 when the wavefront aberration measuring apparatus 20 is calibrated. However, instead of the reflective diffusing spherical surface 24, a reflective system 51 shown in FIG. The reflection system 51 diffuses at least a part of the condensing lens 52 that condenses the illumination light IL from the projection optical system PL in FIG. A reflection diffusing plate 53 that returns to the condenser lens 52 as reflected light ILR. In this case, if the diffusion angle in the reflection diffusion plate 53 is φdf and the focal length of the condensing lens 52 is rdf, the size of the image 51D of the reflected light ILR by the condensing lens 52 is the reflection diffusion spherical surface of FIG. 24 is enlarged to the same size as the image 24D of the reflected light ILR.

従って、反射拡散球面２４の代わりに反射系５１を用いても、波面収差計測装置２０の校正を高精度に行うことができる。
［第２の実施形態］
次に、本実施形態の第２の実施形態につき図６を参照して説明する。本実施形態でも図１（Ａ）の露光装置ＥＸと同様の露光装置を使用するが、波面収差計測装置２０のうちの計測系２１及び計測部１７の構成が異なっている。以下、図６において、図２（Ａ）に対応する部分には同一符号を付してその詳細な説明を省略する。 Therefore, even if the reflection system 51 is used instead of the reflection diffusing spherical surface 24, the wavefront aberration measuring apparatus 20 can be calibrated with high accuracy.
[Second Embodiment]
Next, a second embodiment of the present embodiment will be described with reference to FIG. In this embodiment, an exposure apparatus similar to the exposure apparatus EX in FIG. 1A is used, but the configurations of the measurement system 21 and the measurement unit 17 in the wavefront aberration measurement apparatus 20 are different. Hereinafter, in FIG. 6, parts corresponding to those in FIG.

図６は、本実施形態において投影光学系ＰＬの波面収差を計測する波面収差計測装置２０Ａの概略構成を示す。図６において、波面収差計測装置２０Ａは、投影光学系ＰＬの物体面に配置されるテストレチクルＲ１と、テストレチクルＲ１を照明光ＩＬで照明する照明光学系（不図示）と、テストレチクルＲ１の上方に配置される計測系２１Ａと、投影光学系ＰＬの像面側でウエハステージＷＳＴに設けられる反射部材２２と、計測系２１Ａの検出信号を処理して投影光学系ＰＬの波面収差を求める計測部１７Ａと、を備えている。 FIG. 6 shows a schematic configuration of a wavefront aberration measuring apparatus 20A that measures the wavefront aberration of the projection optical system PL in the present embodiment. In FIG. 6, the wavefront aberration measuring apparatus 20A includes a test reticle R1 disposed on the object plane of the projection optical system PL, an illumination optical system (not shown) that illuminates the test reticle R1 with illumination light IL, and the test reticle R1. Measurement system 21A disposed above, reflection member 22 provided on wafer stage WST on the image plane side of projection optical system PL, and measurement signal 21A for processing the detection signal of measurement system 21A to determine the wavefront aberration of projection optical system PL 17A.

また、計測系２１Ａは、照明光ＩＬをテストレチクルＲ１の計測用開口１９に照射し、投影光学系ＰＬから計測用開口１９を介して戻される反射光ＩＬＲの一部を反射するビームスプリッタ３２と、ビームスプリッタ３２で反射された反射光ＩＬＲの光路上に配置され、Ｚ方向に周期Ｐｇで形成された回折格子４１と、回折格子４１から発生する０次光４２、＋１次回折光４２Ａ、及び−１次回折光４２Ｂ（波面分割された光束）の干渉縞（シアリング干渉縞）を受光する撮像素子３５とを有する。 The measurement system 21A irradiates the measurement light 19 of the test reticle R1 with the illumination light IL, and reflects a part of the reflected light ILR returned from the projection optical system PL through the measurement opening 19. , A diffraction grating 41 arranged on the optical path of the reflected light ILR reflected by the beam splitter 32 and formed with a period Pg in the Z direction, a 0th-order light 42 generated from the diffraction grating 41, a + 1st-order diffracted light 42A, and − And an image sensor 35 that receives interference fringes (shearing interference fringes) of the first-order diffracted light 42B (light beams divided in wavefront).

回折格子４１と計測用開口１９の形成面との間隔（光路長）をＬｇ、撮像素子３５の受光面と計測用開口１９の形成面との間隔（光路長）をＬｃ、照明光ＩＬの波長をλ、所定の整数又は半整数をｎとすると、間隔Ｌｇ，Ｌｃ、周期Ｐｇ、及び波長λは次のいわゆるトールボット(Talbot)条件を満たす。
１／Ｌｇ＋１／（Ｌｃ−Ｌｇ）＝λ／（２・ｎ・Ｐｇ²) …（３）
ｎ（トールボット次数）＝０，１／２，１，３／２，２，… …（４）
なお、トールボット条件の詳細は、「応用光学１（鶴田著）」（p. 178-181，培風館，1990年）に記載されている。トールボット条件は、撮像素子３５の受光面に回折格子４１によるシアリング干渉の干渉縞が高いコントラストで形成されるための条件である。言い換えると、計測系２１Ａはトールボット干渉計を構成している。計測部１７Ａは、撮像素子３５の検出信号からその干渉縞の強度分布を求め、この強度分布からシアリング波面（位相分布）を求め、このシアリング波面から反射光ＩＬＲの波面（波面収差）を求める。 The distance (optical path length) between the diffraction grating 41 and the formation surface of the measurement opening 19 is Lg, the interval (optical path length) between the light receiving surface of the image sensor 35 and the formation surface of the measurement opening 19 is Lc, and the wavelength of the illumination light IL. Is λ, and a predetermined integer or half integer is n, the intervals Lg, Lc, the period Pg, and the wavelength λ satisfy the following so-called Talbot condition.
1 / Lg + 1 / (Lc−Lg) = λ / (2 · n · Pg ² ) (3)
n (Talbot order) = 0, 1/2, 1, 3/2, 2,... (4)
The details of the Talbot conditions are described in “Applied Optics 1 (by Tsuruta)” (p. 178-181, Baifukan, 1990). The Talbot condition is a condition for forming interference fringes of shearing interference by the diffraction grating 41 on the light receiving surface of the image sensor 35 with high contrast. In other words, the measurement system 21A constitutes a Talbot interferometer. The measurement unit 17A obtains the intensity distribution of the interference fringes from the detection signal of the image sensor 35, obtains the shearing wavefront (phase distribution) from the intensity distribution, and obtains the wavefront (wavefront aberration) of the reflected light ILR from the shearing wavefront.

従って、計測系２１Ａのみの波面を求める場合には、計測用開口１９の像の位置に反射拡散球面２４を設置することで、第１の実施形態と同様に、波面収差計測装置２０Ａの校正を高精度に行うことができる。そして、投影光学系ＰＬのみの波面を求める場合には、計測用開口１９の像の位置に微小ミラー２３を設置し、計測された波面から計測系２１Ａのみの波面を差し引けばよい。 Therefore, when obtaining the wavefront of only the measurement system 21A, the wavefront aberration measuring apparatus 20A is calibrated by installing the reflection diffusion spherical surface 24 at the position of the image of the measurement aperture 19 as in the first embodiment. It can be performed with high accuracy. Then, when obtaining the wavefront of only the projection optical system PL, a minute mirror 23 is installed at the position of the image of the measurement aperture 19, and the wavefront of only the measurement system 21A is subtracted from the measured wavefront.

なお、計測系２１Ａにおいて、回折格子４１の代わりにＹ方向に周期的に形成された回折格子、又はＹ方向及びＺ方向に周期的に形成された２次元の回折格子を使用してもよい。
なお、上記の各実施形態において、図１（Ａ）の偏光状態可変部３によって照明光ＩＬをＸ方向又はＹ方向の直線偏光に設定し、各偏光成分毎の投影光学系ＰＬの波面収差である偏光特性を求めてもよい。 In the measurement system 21A, instead of the diffraction grating 41, a diffraction grating periodically formed in the Y direction or a two-dimensional diffraction grating periodically formed in the Y direction and the Z direction may be used.
In each of the above embodiments, the illumination light IL is set to X-direction or Y-direction linearly polarized light by the polarization state variable unit 3 in FIG. 1A, and the wavefront aberration of the projection optical system PL for each polarization component. A certain polarization characteristic may be obtained.

また、計測系２１，２１Ａの代わりに、投影光学系ＰＬの波面収差以外の光学特性を計測する計測系を配置してもよい。
また、本発明は、半導体デバイス製造用の露光装置への適用に限定されることなく、例えば、角型のガラスプレートに形成される液晶表示素子、若しくはプラズマディスプレイ等のディスプレイ装置用の露光装置や、撮像素子（ＣＣＤ等）、マイクロマシーン、薄膜磁気ヘッド、及びＤＮＡチップ等の各種デバイスやマスク自体を製造するための露光装置にも広く適用できる。 Further, instead of the measurement systems 21 and 21A, a measurement system that measures optical characteristics other than the wavefront aberration of the projection optical system PL may be arranged.
In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, The present invention can also be widely applied to various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip, and an exposure apparatus for manufacturing a mask itself.

また、本発明は、露光装置の投影光学系の光学特性の計測のみならず、各種の光学装置、例えば、天体望遠鏡、眼科的検査装置、又は携帯カメラ若しくは携帯電話に備えられる小型カメラの波面収差等の光学特性を計測する際にも同様に適用することができる。
このように本発明は上述の実施形態に限定されず、本発明の要旨を逸脱しない範囲で種々の構成を取り得る。 Further, the present invention is not limited to the measurement of the optical characteristics of the projection optical system of the exposure apparatus, but also the wavefront aberration of various optical devices, for example, astronomical telescopes, ophthalmic inspection devices, or small cameras provided in portable cameras or mobile phones. The present invention can be similarly applied when measuring optical characteristics such as the above.
As described above, the present invention is not limited to the above-described embodiment, and various configurations can be taken without departing from the gist of the present invention.

ＥＸ…露光装置、ＩＬＳ…照明光学系、ＰＬ…投影光学系、Ｒ…レチクル、Ｗ…ウエハ、１７，１７Ａ…計測部、１９…計測用開口、２０，２０Ａ…波面収差計測装置、２１，２１Ａ…計測系、２２…反射部材、２３…微小ミラー、２４…反射拡散球面、３４…マイクロレンズアレイ、３５…撮像素子 EX ... exposure apparatus, ILS ... illumination optical system, PL ... projection optical system, R ... reticle, W ... wafer, 17, 17A ... measuring unit, 19 ... measuring aperture, 20,20A ... wavefront aberration measuring device, 21,21A ... Measuring system, 22 ... Reflecting member, 23 ... Micro mirror, 24 ... Reflective diffusing spherical surface, 34 ... Micro lens array, 35 ... Image sensor

Claims

第１面のパターンの像を第２面に形成する投影光学系の光学特性を計測する装置において、
前記第１面側に配置され、計測用開口が形成された開口部材と、
前記第１面側に配置された前記開口部材を照明光で照明する照明系と、
前記計測用開口及び前記投影光学系を通過し、前記第２面から戻された前記照明光の少なくとも一部を前記投影光学系及び前記計測用開口を介して受光して、前記投影光学系の光学特性を計測する計測系と、
前記照明光の光路中に挿入又は離脱可能に配置され、前記計測用開口を通過した前記照明光の少なくとも一部を反射し、該反射した光束で前記計測用開口を含む領域を照明する第１反射光学系と、
前記計測用開口を通過した計測光を前記計測系で受光して、前記計測系の光学特性を計測する計測装置と、
を備えることを特徴とする光学特性計測装置。 In an apparatus for measuring optical characteristics of a projection optical system that forms an image of a pattern of a first surface on a second surface,
An opening member disposed on the first surface side and formed with an opening for measurement;
An illumination system that illuminates the opening member disposed on the first surface side with illumination light;
At least part of the illumination light that has passed through the measurement aperture and the projection optical system and returned from the second surface is received via the projection optical system and the measurement aperture, and the projection optical system A measurement system for measuring optical characteristics;
First arranged to be inserted into or removed from the optical path of the illumination light, reflecting at least a part of the illumination light that has passed through the measurement aperture, and illuminating a region including the measurement aperture with the reflected light beam A reflective optical system;
A measurement device that receives the measurement light that has passed through the measurement aperture by the measurement system and measures optical characteristics of the measurement system;
An optical property measuring device comprising:

前記第２面側に配置され、前記計測用開口及び前記投影光学系を通過した前記照明光の少なくとも一部を反射し、該反射した前記照明光で前記投影光学系を介して前記計測用開口の内側の領域を照明する第２反射光学系を備え、
前記計測装置は、前記投影光学系を介して前記計測用開口の内側の領域を通過した前記照明光を前記計測系で受光して、前記投影光学系の光学特性を計測することを特徴とする請求項１に記載の光学特性計測装置。 The measurement aperture is disposed on the second surface side, reflects at least part of the illumination light that has passed through the measurement aperture and the projection optical system, and is reflected by the reflected illumination light through the projection optical system. A second reflective optical system for illuminating the inner region of
The measuring apparatus receives the illumination light that has passed through the region inside the measurement aperture via the projection optical system, and measures the optical characteristics of the projection optical system. The optical characteristic measuring device according to claim 1.

前記第１反射光学系は、前記第２面側に配置されるとともに、前記計測用開口及び前記投影光学系を通過した前記照明光の少なくとも一部を前記投影光学系を介して前記計測用開口を含む領域に戻すことを特徴とする請求項１または請求項２に記載の光学特性計測装置。 The first reflective optical system is disposed on the second surface side, and at least a part of the illumination light that has passed through the measurement aperture and the projection optical system is passed through the projection optical system to the measurement aperture. The optical characteristic measuring device according to claim 1, wherein the optical characteristic measuring device is returned to a region including

前記第１反射光学系は、前記第１面側に配置されるとともに、前記計測用開口を通過した前記照明光の少なくとも一部を前記計測用開口を含む領域に戻すことを特徴とする請求項１または請求項２に記載の光学特性計測装置。 The first reflective optical system is disposed on the first surface side and returns at least a part of the illumination light that has passed through the measurement aperture to a region including the measurement aperture. The optical characteristic measuring device according to claim 1 or 2.

前記第１反射光学系は、前記照明光を拡散して反射する球面を有する反射球面部材を含むことを特徴とする請求項１から請求項４のいずれか一項に記載の光学特性計測装置。 5. The optical characteristic measuring apparatus according to claim 1, wherein the first reflective optical system includes a reflective spherical member having a spherical surface that diffuses and reflects the illumination light. 6.

前記第１反射光学系は、前記照明光を集光するレンズと、前記レンズで集光された前記照明光の少なくとも一部を拡散して前記レンズに戻す反射拡散板とを含むことを特徴とする請求項１から請求項４のいずれか一項に記載の光学特性計測装置。 The first reflective optical system includes a lens that collects the illumination light, and a reflection diffusion plate that diffuses at least a part of the illumination light collected by the lens and returns the diffused light to the lens. The optical characteristic measuring device according to any one of claims 1 to 4.

前記計測系は、前記計測光を波面分割するレンズアレイと、前記レンズアレイで波面分割された前記計測光を受光する撮像素子とを含むことを特徴とする請求項１から請求項６のいずれか一項に記載の光学特性計測装置。 7. The measurement system according to claim 1, further comprising: a lens array that divides the measurement light into a wavefront; and an image sensor that receives the measurement light that has been wavefront-divided by the lens array. The optical property measuring device according to one item.

前記計測系は、前記計測光を波面分割する回折格子と、前記回折格子で波面分割された前記計測光を受光する撮像素子とを含むことを特徴とする請求項１から請求項６のいずれか一項に記載の光学特性計測装置。 7. The measurement system according to claim 1, further comprising: a diffraction grating that divides the measurement light into a wavefront; and an image sensor that receives the measurement light that has been wavefront divided by the diffraction grating. The optical property measuring device according to one item.

第１面のパターンの像を第２面に形成する投影光学系の光学特性を計測する装置の校正方法において、
前記第１面またはその近傍に計測用開口が形成された開口部材を配置する工程と、
照明光で前記計測用開口を照明する工程と、
前記照明光の光路中に、前記計測用開口を通過した前記照明光の少なくとも一部を反射する第１反射部材を挿入する工程と、
前記第１反射部材で反射した前記照明光で前記計測用開口を含む領域を照明する工程と、
前記反射した照明光のうち前記計測用開口を通過した計測光を計測系で受光し、前記計測系の光学特性を求める工程と、
を含むことを特徴とする光学特性計測装置の校正方法。 In a calibration method of an apparatus for measuring optical characteristics of a projection optical system that forms an image of a pattern of a first surface on a second surface,
Placing an opening member having a measurement opening formed on or near the first surface; and
Illuminating the measurement aperture with illumination light;
Inserting a first reflecting member that reflects at least a part of the illumination light that has passed through the measurement opening into the optical path of the illumination light;
Illuminating a region including the measurement aperture with the illumination light reflected by the first reflecting member;
Receiving measurement light that has passed through the measurement aperture among the reflected illumination light by a measurement system, and obtaining optical characteristics of the measurement system;
A method for calibrating an optical property measuring apparatus, comprising:

前記第１反射部材を前記照明光の光路から離脱する工程と、
前記計測用開口を通過した前記照明光を前記投影光学系に入射させる工程と、
前記投影光学系を通過した前記照明光の少なくとも一部を反射し、該反射した照明光で前記投影光学系を介して前記計測用開口の内側の領域を照明する工程と、
前記計測用開口の内側の領域を通過した計測光を前記計測系で受光し、前記投影光学系の光学特性を求める工程と、を含むことを特徴とする請求項９に記載の光学特性計測装置の校正方法。 Detaching the first reflecting member from the optical path of the illumination light;
Allowing the illumination light that has passed through the measurement aperture to enter the projection optical system;
Reflecting at least a portion of the illumination light that has passed through the projection optical system, and illuminating a region inside the measurement aperture through the projection optical system with the reflected illumination light; and
The optical characteristic measuring apparatus according to claim 9, further comprising: a step of receiving measurement light that has passed through a region inside the measurement aperture by the measurement system and obtaining optical characteristics of the projection optical system. Calibration method.

前記計測用開口を含む領域を照明する工程は、前記計測用開口を通過した前記照明光の少なくとも一部を前記投影光学系を介して前記計測用開口に戻すことを特徴とする請求項９または請求項１０に記載の光学特性計測装置の校正方法。 The step of illuminating the region including the measurement aperture returns at least a part of the illumination light that has passed through the measurement aperture to the measurement aperture via the projection optical system. The method for calibrating an optical property measuring apparatus according to claim 10.

前記計測用開口を含む領域を照明する工程は、前記計測用開口を通過した前記照明光の少なくとも一部を直接に前記計測用開口に戻すことを特徴とする請求項９または請求項１０に記載の光学特性計測装置の校正方法。 11. The step of illuminating a region including the measurement opening directly returns at least a part of the illumination light that has passed through the measurement opening to the measurement opening. Calibration method for optical property measuring apparatus.

照明光でパターンを照明し、前記照明光で前記パターン及び投影光学系を介して物体を露光する露光装置において、
前記投影光学系の光学特性を計測するために請求項１から請求項８のいずれか一項に記載の光学特性計測装置を備えることを特徴とする露光装置。 In an exposure apparatus that illuminates a pattern with illumination light and exposes an object with the illumination light via the pattern and a projection optical system,
An exposure apparatus comprising the optical property measurement apparatus according to claim 1 to measure an optical property of the projection optical system.

照明光でパターンを照明し、前記照明光で前記パターン及び投影光学系を介して物体を露光する露光方法において、
請求項９から請求項１２のいずれか一項に記載の光学特性計測装置の校正方法を用いて、前記投影光学系の光学特性を計測する前記光学特性計測装置の校正を行うことを特徴とする露光方法。 In an exposure method of illuminating a pattern with illumination light and exposing an object with the illumination light via the pattern and a projection optical system,
13. The optical property measuring device for measuring the optical property of the projection optical system is calibrated using the optical property measuring device calibration method according to claim 9. Exposure method.