JPWO2004068564A1 - Illumination optical system, illumination apparatus, projection exposure apparatus, and exposure method - Google Patents

Abstract

An object of the present invention is to provide an illumination optical system or the like with little light loss even when EUV light is used as a light source. In the illumination optical system of the present invention, a light source unit that emits extreme ultraviolet light, a collimator mirror, a fly-eye mirror, and a condenser mirror are sequentially arranged. It is characterized by comprising a plurality of unit mirrors arranged in an attitude where the incident angle is the total reflection angle.

Description

  The present invention relates to an illumination optical system and an illumination apparatus mounted on a projection exposure apparatus, and more particularly to an illumination optical system and an illumination apparatus suitable for extreme ultraviolet light (hereinafter referred to as EUV light). The present invention also relates to a projection exposure apparatus using the illumination optical system and the illumination apparatus. The present invention also relates to an exposure method for manufacturing an excellent microdevice (semiconductor device, imaging device, liquid crystal display device, thin film magnetic head, etc.) using these illumination optical system and illumination device.

In the projection exposure apparatus, the exposure wavelength tends to be shortened in order to improve the integration density of the semiconductor.
Examples of the light source applied thereto include mercury i-line (wavelength 365.015 nm), KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F ₂ excimer laser (wavelength 157 nm), and the like. Furthermore, the use of EUV light, particularly EUV light with a wavelength of 50 nm or less as a light source is also being studied.
If EUV light having a wavelength of 50 nm or less is used, it is necessary to configure the optical system to be a reflection type (for example, an illumination optical system described in Japanese Patent Laid-Open No. 2000-349209).
However, even with the illumination optical system described in Japanese Patent Application Laid-Open No. 2000-349209, EUV light, particularly EUV light with a wavelength of 50 nm or less cannot be reflected with a sufficient reflectivity, resulting in a large amount of light loss.
Although a certain degree of improvement can be achieved by using a multilayer film on each reflecting surface, this illumination optical system is still insufficient because only about 70% of the reflectance can be obtained for each reflecting surface.
Further, the fly-eye mirror disposed in the illumination optical system has a large amount of light loss, and the fly-eye mirror itself is required to be greatly improved.

Accordingly, an object of the present invention is to provide an illumination optical system and an illumination apparatus that have little light loss even when EUV light is used as a light source.
Another object of the present invention is to provide a high-performance projection exposure apparatus by using the illumination optical system and the illumination apparatus.
Furthermore, an object of the present invention is to provide an exposure method capable of producing a good microdevice (semiconductor device, imaging device, liquid crystal display device, thin film magnetic head, etc.) by using the illumination optical system and the illumination device. To do.
In the illumination optical system of the present invention, a light source unit that emits extreme ultraviolet light, a collimator mirror, a fly-eye mirror, and a condenser mirror are arranged in order, and each of the collimator mirror, the fly-eye mirror, and the condenser mirror is configured to tilt incident light. It is characterized by comprising a plurality of unit mirrors arranged in an attitude where the incident angle is the total reflection angle.
Preferably, the light source unit includes a laser plasma light source, a collector mirror that condenses the extreme ultraviolet light emitted from the laser plasma light source, and scattering disposed near the converging point of the extreme ultraviolet light by the collector mirror. And a partition wall for blocking objects.
Preferably, the light source unit includes a discharge plasma light source.
Further preferably, the light source unit is a collector mirror that condenses the extreme ultraviolet light emitted from the discharge plasma light source, and a scattered object blocking unit disposed near the converging point of the extreme ultraviolet light by the collector mirror. A partition wall.
Further preferably, the collector mirror is composed of a plurality of unit mirrors arranged in such a posture that an oblique incident angle of incident light is a total reflection angle.
Further, preferably, the collimator mirror is formed by arranging a plurality of skirt-shaped unit mirrors having different diameters and spread angles around the optical axis in a state where the spread portions are directed to the exit side.
Further preferably, the reflecting surfaces of the plurality of skirt-shaped unit mirrors have a conical partial side surface shape.
Preferably, the reflection surface of the unit mirror arranged on the outermost peripheral side of the unit mirrors has a parabolic shape, and the other reflection surfaces of the unit mirrors are conical partial side surfaces. It has the shape of
Further, preferably, a capillary array formed by arranging a plurality of hollow tubes in parallel is arranged between the collimator mirror and the fly-eye mirror.
Further preferably, a cooling mechanism for cooling the capillary array is provided.
Further preferably, the fly-eye mirror has an incident end where a plurality of unit mirrors having the same posture are arranged in parallel and an emission end where a plurality of unit mirrors having the same posture are arranged in parallel with each other. They are arranged at a sufficient interval in the traveling direction of the reflected light by the unit mirrors so that the oblique incident angle of light becomes the total reflection angle.
Further preferably, the reflecting surfaces of the plurality of unit mirrors arranged at the incident end have a Walter I shape.
Further preferably, the reflection surfaces of the plurality of unit mirrors arranged at the incident end and the emission end have a parabolic shape, respectively.
Further preferably, the plurality of unit mirrors constituting the incident end are arranged by being shifted by a sufficient distance in the traveling direction of the reflected light by the unit mirrors so as to reduce the vignetting of the reflected light between the unit mirrors. The plurality of unit mirrors constituting the emission end are arranged by being shifted by a sufficient distance in the traveling direction of the reflected light by the unit mirrors so that the vignetting of the reflected light between the unit mirrors is reduced.
Further preferably, the condenser mirror is formed by arranging a plurality of unit mirrors in series, and at least one of the reflecting surfaces is a toroidal aspherical surface.
Further, preferably, the extreme ultraviolet light emitted from the light source unit is extreme ultraviolet light having a wavelength of 50 nm or less, and a reflection surface of each unit mirror of the collimator mirror, fly-eye mirror, and condenser mirror is made of Ru or Mo. It is made of a material and is arranged in such a posture that the oblique incident angle is 15 ° or less.
The projection exposure apparatus of the present invention includes a reflective projection optical system and any one of the illumination optical systems of the present invention.
The exposure method of the present invention includes an illumination step of illuminating a reticle using any one of the illumination optical systems of the present invention, and an exposure step of exposing a pattern of the reticle onto a photosensitive substrate.
An illumination apparatus according to the present invention includes a light source unit that supplies extreme ultraviolet light, and an illumination optical system that guides light from the light source unit to an object to be illuminated. The illumination optical system includes a plurality of reflectors that reflect the extreme ultraviolet light. All of the reflection members constituting the illumination optical system are arranged in a posture in which the incident angle of incident light is the total reflection angle.
Preferably, the plurality of reflecting members include at least an array-shaped mirror having a plurality of reflecting elements, and the plurality of reflecting elements in the array-shaped mirror are arranged in an attitude in which an incident angle of incident light is a total reflection angle. .
More preferably, the multiple reflecting elements in the array-shaped mirror have predetermined optical powers in the meridional direction and the sagittal direction, respectively.
More preferably, the plurality of reflecting members include at least a first array-shaped mirror having a large number of first reflecting elements and a second array-shaped mirror having a large number of second reflecting elements, A large number of first reflective elements in one array-shaped mirror and a large number of second reflective elements in the second array-shaped mirror are respectively arranged in an attitude in which the incident angle of incident light is a total reflection angle.
The illumination device of the present invention includes a light source unit that supplies extreme ultraviolet light, and an illumination optical system that guides light from the light source unit to an object to be illuminated. The illumination optical system reflects the extreme ultraviolet light. A plurality of reflecting members, wherein the plurality of reflecting members include at least a first array-shaped mirror having a large number of first reflecting elements and a second array-shaped mirror having a large number of second reflecting elements. A plurality of first reflective elements in the first array-shaped mirror and a plurality of second reflective elements in the second array-shaped mirror are arranged in such a posture that the incident angle of incident light is a total reflection angle. It is characterized by being.
Preferably, the multiple first reflective elements in the first arrayed mirror and the multiple second reflective elements in the second arrayed mirror have a predetermined optical power in the meridional direction and the sagittal direction.
More preferably, the light passing through the first array mirror and the second array mirror is the second array mirror, the vicinity of the second array mirror, or the second array mirror. Many condensing points as secondary light sources are formed on the exit side of the mirror.
More preferably, at least one of the first reflecting element and the second reflecting element includes a rectangular parallelepiped reflecting surface.
More preferably, the plurality of first reflecting elements in the first array-shaped mirror are dense on a first reference plane inclined at a predetermined angle with respect to an incident optical path incident on the first array-shaped mirror. The plurality of second reflecting elements in the second array-shaped mirror are densely arranged on a second reference plane that is inclined at a predetermined angle with respect to an incident optical path incident on the second array-shaped mirror. It is characterized by being.
More preferably, the plurality of first reflective elements in the first array mirror are first inclined at a predetermined angle β1 with respect to the central light of the light incident on each of the multiple first reflective elements. The plurality of second reflecting elements in the second array mirror are arranged at a predetermined angle with respect to the central light of the light incident on each of the plurality of first reflecting elements. The second reference plane is inclined densely by β2, and the predetermined angle β1 and the predetermined angle β2 satisfy 0 ° <β1 ≦ 20 ° and 0 ° <β2 ≦ 20 °.
A projection exposure apparatus according to the present invention includes any one of the illumination apparatuses according to the present invention, and a projection optical system that projects a reticle pattern as the illuminated object illuminated by the illumination apparatus onto a photosensitive substrate. And
The exposure method of the present invention includes an illumination step of illuminating a reticle as the object to be illuminated using any one of the illumination devices of the present invention, and an exposure step of exposing a pattern of the reticle onto a photosensitive substrate. Features.
The exposure method of the present invention includes a step of supplying extreme ultraviolet light, a step of illuminating a reticle with the extreme ultraviolet light, and a step of exposing a pattern of the reticle onto a photosensitive substrate, wherein the illumination step includes incident light The method includes a step of guiding the extreme ultraviolet light to an object to be illuminated using only a plurality of reflecting members arranged in a posture in which the incident angle of light is a total reflection angle.
The exposure method of the present invention includes a step of supplying extreme ultraviolet light, a step of illuminating a reticle with the extreme ultraviolet light, and a step of exposing a pattern of the reticle onto a photosensitive substrate, wherein the illumination step includes incident light A first array of mirrors having a number of first reflecting elements arranged in a posture where the incident angle of light is a total reflection angle, and a number of members arranged in a posture where the incident angle of incident light is a total reflection angle A step of guiding the extreme ultraviolet light to an object to be illuminated using a second array of mirrors having a second reflecting element.

FIG. 1 is a schematic configuration diagram of an illumination optical system according to the first embodiment.
FIG. 2 is a diagram showing the relationship (with respect to Mo) between the oblique incidence angle of EUV light having a wavelength of 13.5 nm and the reflectance.
FIG. 3 is a diagram showing the relationship (with respect to Ru) between the oblique incidence angle of EUV light having a wavelength of 13.5 nm and the reflectance.
FIG. 4 is a diagram showing a relationship (with respect to MoSi ₂ ) between the oblique incident angle of EUV light having a wavelength of 13.5 nm and the reflectance.
FIG. 5 is a diagram illustrating the collimator mirror 12 according to the first embodiment.
FIG. 6 is a diagram illustrating the collimator mirror 12 ′ of the first embodiment.
7A is a view showing the incident end 13in of the fly-eye mirror 13 of the first embodiment, and FIG. 7B is a view showing the exit end 13out of the fly-eye mirror 13 of the first embodiment. is there.
FIG. 8 is a diagram for explaining the shapes of the reflecting surfaces of the unit mirrors 13in-1, 13in-2,... Arranged at the incident end 13in of the fly-eye mirror 13 of the first embodiment.
FIG. 9 is a diagram illustrating the collimator mirror 12 ″ according to the second embodiment.
FIG. 10 is a diagram illustrating the capillary array 12B.
FIG. 11 illustrates the shapes of the reflecting surfaces of the unit mirrors 13′in-1, 13′in-2,... Arranged at the incident end 13′in of the fly-eye mirror 13 ′ of the third embodiment. FIG.
FIG. 12 shows unit mirrors 13 ″ in−1, 13 ″ in−2,... Arranged at the incident end 13 ″ in of the fly-eye mirror 13 ″ of the fourth embodiment, and the output end 13 ″ out. It is a figure explaining the shape of the reflective surface of unit mirror 13 "out-1,13" out-2, ... arrange | positioned.
FIG. 13 is a diagram illustrating a schematic configuration of the light source unit 21 and the periphery thereof according to the fifth embodiment.
FIG. 14 is a diagram illustrating a schematic configuration of the light source unit 31 and the periphery thereof according to the sixth embodiment.
FIG. 15 is a diagram (perspective view) for explaining the collector mirror 31c of the sixth embodiment.
FIG. 16 is a diagram illustrating the arrangement relationship of the unit mirrors of the fly-eye mirror 33 according to the seventh embodiment.
FIG. 17 is a block diagram of a projection exposure apparatus according to the eighth embodiment.
FIG. 18 is a cross-sectional view showing the configuration of the collimator mirror 12 ′ of the first embodiment.
FIG. 19 is an optical path diagram showing the configuration of the fly-eye mirror 13 of the first embodiment.
FIG. 20 is an optical path diagram showing the configuration of the capacitor mirror 14 of the first embodiment.
FIG. 21 is a diagram showing the positional relationship between the reflecting surfaces of the collimator mirror 12 ″ of the second embodiment.
FIG. 22 is a diagram for explaining the shapes of the reflecting surfaces of the unit mirrors 13′in-1, 13′-2,... Arranged at the incident end 13′in of the fly-eye mirror 13 ′ of the third embodiment. is there.
FIG. 23 shows unit mirrors 13 ″ in−1, 13 ″ in−2,..., 13 ″ arranged at the entrance end 13 ″ in and the exit end 13 ″ out of the fly-eye mirror 13 ″ of the fourth embodiment. It is a figure explaining the shape of the reflective surface of out-1,13 "out-2, ....
FIG. 24 is an optical path diagram of the fly-eye mirror 33 of the fifth embodiment.
FIG. 25 is an optical path diagram showing the configuration of the condenser mirror 14 of the fifth embodiment.
FIG. 26 is a flowchart of a technique for obtaining a semiconductor device as a micro device.
FIG. 27 is a flowchart of a method for obtaining a liquid crystal display element as a micro device.

図１９は、本実施例のフライアイミラー１３の構成を示す光路図である。
図１９に示すように、フライアイミラー１３の入射端１３ｉｎは、１０個の単位ミラー１３ｉｎ−１，１３ｉｎ−２，・・・，１３ｉｎ−１０をＹ方向に３ｍｍずつずらして配置している。
また、フライアイミラー１３の出射端１３ｏｕｔは、１０個の単位ミラー１３ｏｕｔ−１，１３ｏｕｔ−２，・・・，１３ｏｕｔ−１０をＹ方向に３ｍｍずつずらして配置している。
表５は、フライアイミラー１３のデータである。

因みに、上述したコリメータミラー１２の出射端の径が１４０ｍｍであることから（表１〜表４参照）、本実施例のフライアイミラー１３の入射端１３ｉｎには、Ｙ方向に最大で４３枚程度、Ｘ方向に最大で１３枚、単位ミラーを配置することができる。
また、後述するコンデンサミラー１４の光学的特性に適合させるために、フライアイミラー１３の出射端１３ｏｕｔに配置された単位ミラー１３ｏｕｔ−１，１３ｏｕｔ−２，・・・，１３ｏｕｔ−１０において、後述するコンデンサミラー１４のＡ点，Ｂ点，Ｃ点，Ｄ点に対応する各領域（Ａ点，Ｂ点，Ｃ点，Ｄ点）には、それぞれ表６に示す角度だけ傾斜が設けられる。

図２０は、本実施例のコンデンサミラー１４の構成を示す光路図である。
コンデンサミラー１４は、フライアイミラー１３の側から順に、単位ミラー１４−１，１４−２，１４−３の合計３つの単位ミラーを配置している。
表７は、コンデンサミラー１４のデータである。
なお、表７において、光線追跡の方向（面の順序）は実際の光の進行方向とは反対（レチクル面Ｒからフライアイミラー１３の方向、単位ミラー１４−３，１４−２，１４−１の順）になっている。また、単位ミラー１４−１，１４−２，１４−３の各反射面は、光軸に対し１５°ずつ傾斜している。

また、単位ミラー１４−１，１４−２，１４−３の反射面は、それぞれトロイダル非球面からなる。
表８は、各反射面のトロイダル非球面係数である。なお、トロイダル非球面の定義式は、式（１）で表される。式（１）のＺは、光軸方向の非球面のＳａｇ量である。

［第２実施例］
図２１、表９、表１０、表１１、表１２、表１３、表１４、表１５に基づいて本発明の第２実施例について説明する。
本実施例は、第２実施の形態に対応した実施例である。
ここでは、第１実施例との相違点についてのみ説明する。相違点は、コリメータミラー１２に代えてコリメータ１２”が適用された点にある。
図２１は、本実施例のコリメータミラー１２”の各反射面の位置関係を示す図であり、表９、表１０、表１１、表１２、表１３、表１４、表１５は、コリメータミラー１２”のデータである。
図２１に示すように、本実施例のコリメータミラー１２”は、第２実施の形態で述べた単位ミラー１２Ａを最外周に配置している。
表９は、単位ミラー１２Ａのデータである。
なお、表において「Ｚ＝０」は、単位ミラー１２Ａの入射側の端部の光軸Ｚ方向の位置を示す。また、「光線の遮蔽角」とは、反射面上の各位置の接線とその位置に入射する光線とのなす角度の最大値である。また、「全長」は、光軸Ｚの方向の長さである。

また、コリメータミラー１２”には、単位ミラー１２Ａの内部に、径の大きい方から順に、単位ミラー１２−１（円錐１），１２−２（円錐２），・・・，１２−１２（円錐１２）の合計１２の単位ミラーが備えられる。
また、円錐１，円錐２，・・・，円錐１２はそれぞれ、入射側から射出側へ第１ブロック、第２ブロック、第３ブロック、第４ブロック、第５ブロック、第６ブロックの合計６つのブロックに複数化されている。
表１０、表１１、表１２、表１３、表１４、表１５には、各円錐の各ブロックのデータを、ブロック毎に示した。表１０は第１ブロックの各円錐のデータ、表１１は第２ブロックの各円錐のデータ、表１２は第３ブロックの各円錐のデータ、表１３は第４ブロックの各円錐のデータ、表１４は第５ブロックの各円錐のデータ、表１５は第６ブロックの各円錐のデータである。
なお、各表の表記方法については、表１、表２、表３、表４に適用したものと同じである。

因みに、以上説明した本実施例のコリメータミラー１２”によると、「規格化径高」１〜０．７５に相当する角度範囲で入射する光線については部分放物面の反射面（単位ミラー１２Ａ）によって反射され、「規格化径高」０．７５以下に相当する角度範囲で入射する光線については、円錐の部分側面の形状をした反射面（単位ミラー１２−１，１２−２，・・・）によって反射される。
［第３実施例］
図２２に基づいて本発明の第３実施例について説明する。
本実施例は、第３実施の形態に対応した実施例である。
ここでは、第１実施例又は第２実施例との相違点についてのみ説明する。相違点は、フライアイミラー１３に代えてフライアイミラー１３’が適用される点にある。
図２２は、本実施例のフライアイミラー１３’の入射端１３’ｉｎに配置された単位ミラー１３’ｉｎ−１，１３’ｉｎ−２，・・・の反射面の形状を説明する図である。
単位ミラー１３’ｉｎ−１，１３’ｉｎ−２，・・・の反射面の形状は、それぞれ第３実施の形態で述べたとおりのウォルターＩ型である。このウォルターＩ型の形状の各部の寸法は、以下のとおりである。
・反射面として切り取った部分の放物面又は双曲面の直径＝２０００ｍｍ
・焦点Ｆ２又はＦ１とそれに近接する方の双曲面の頂点との間隔＝５０ｍｍ
・焦点Ｆ１と放物面の頂点との間隔＝５０ｍｍ
なお、図２２の実施例に示すフライアイミラーの射出端１３’ｏｕｔに配置された単位ミラー１３’ｏｕｔ−１，１３’ｏｕｔ−２，・・・の反射面の形状は平面であるが、これに限ることなく、凹面形状やその他の形状としても良いことは言うまでもない。
［第４実施例］
図２３に基づいて本発明の第４実施例について説明する。
本実施例は、第４実施の形態に対応した実施例である。
ここでは、第１実施例、第２実施例、第３実施例との相違点についてのみ説明する。相違点は、フライアイミラー１３（又は１３’）に代えてフライアイミラー１３”が適用される点にある。
図２３は、本実施例のフライアイミラー１３”の入射端１３”ｉｎ及び出射端１３”ｏｕｔに配置された単位ミラー１３”ｉｎ−１，１３”ｉｎ−２，・・・，１３”ｏｕｔ−１，１３”ｏｕｔ−２，・・・の反射面の形状を説明する図である。
単位ミラー１３”ｉｎ−１，１３”ｉｎ−２，・・・，１３”ｏｕｔ−１，１３”ｏｕｔ−２，・・・の反射面の形状は、それぞれ第４実施の形態で述べたとおり部分放物面である。部分放物面の各部の寸法は、以下のとおりである。
・反射面として切り取った部分の放物面の直径＝２０００ｍｍ
・放物面の頂点と焦点Ｆとの間隔＝５０ｍｍ
［第５実施例］
図２４，図２５に基づいて本発明の第５実施例について説明する。
本実施例は、第７実施の形態に対応するフライアイミラー３３、及びそれに適応するコンデンサミラー１４の実施例である。
図２４は、本実施例のフライアイミラー３３の光路図である。
表１６、表１７は、フライアイミラー３３のデータである。なお、表１７には、中央の単位ミラー対（３３ｉｎ−２，３３ｏｕｔ−２）を基準とした、上部の単位ミラー対（３３ｉｎ−１，３３ｏｕｔ−１）のシフト量（ずれ量）、下部の単位ミラー対（３３ｉｎ−３，３３ｏｕｔ−３）のシフト量（ずれ量）を示した。ここで、Ｚ軸、Ｙ軸は、それぞれフライアイミラー３３に入射する光の進行方向、及びＺ軸に垂直な方向である。

図２５は、本実施例のコンデンサミラー１４の構成を示す光路図である。
表１８は、コンデンサミラー１４のデータである。
なお、表１８において、光線追跡の方向（面の順序）は実際の光の進行方向とは反対（レチクル面Ｒからフライアイミラー３３の方向、単位ミラー１４−３，１４−２，１４−１の順）になっている。
また、単位ミラー１４−１，１４−２，１４−３の各反射面は、光軸に対し１４°ずつ傾斜している。
また、レチクル面Ｒへの入射光は面の法線に対して各像高の主光線が６°の角度をなす。
また、フライアイミラー３３の出射端３３ｏｕｔ側における二次光源群の形成面は、光軸と２０°の角度をなす。

また、単位ミラー１４−１，１４−２，１４−３の反射面は、それぞれトロイダル非球面からなる。
表１９は、各反射面のトロイダル非球面係数である。なお、トロイダル非球面の定義式は、式（１）で表される。

以上の各実施の形態及び各実施例においては、照明光学系の結像に寄与する全ての光学部材を全反射させる反射部材で構成するということに着目して、照明光学系の照明効率を格段に向上させることを可能としているが、以下にて、高照明効率と均一照明とを両立させ得る反射型オプティカルインテグレータとしてのフライアイミラー（１３，１３’，１３”，３３）について簡単に説明する。
以上の各実施の形態及び各実施例における反射型オプティカルインテグレータとしてのフライアイミラー（１３，１３’，１３”，３３）は、入射側に配置されて多数の単位ミラー（第１の反射素子）を持つ第１のアレイ状ミラー（１３ｉｎ，１３’ｉｎ，１３”ｉｎ，３３ｉｎ）と、射出側に配置されて多数の単位ミラー（第２の反射素子）を持つ第２のアレイ状ミラー（１３ｏｕｔ，１３’ｏｕｔ，１３”ｏｕｔ，３３ｏｕｔ）とを有している。このため、このフライアイミラーに入射する光は各アレイ状ミラーの多数の単位ミラーにて多数の光に波面分割され、この波面分割された光はレチクル（マスク）やウエハ（感光性基板）に形成される照明領域を重畳的に照明するため、レチクル（マスク）やウエハ（感光性基板）はフライアイミラー（１３，１３’，１３”，３３）の作用によって均一に照明される。
また、以上の各実施の形態及び各実施例における反射型オプティカルインテグレータとしてのフライアイミラー（１３，１３’，１３”，３３）を構成する第１のアレイ状ミラー（１３ｉｎ，１３’ｉｎ，１３”ｉｎ，３３ｉｎ）及び第２のアレイ状ミラー（１３ｏｕｔ，１３’ｏｕｔ，１３”ｏｕｔ，３３ｏｕｔ）は、メリジオナル方向及びサジタル方向において所定の光学パワーを有する多数の単位ミラー（第１の反射素子及び第２の反射素子）を有している。このため、フライアイミラー（１３，１３’，１３”，３３）に入射する光は波面分割されて、このフライアイミラー（１３，１３’，１３”，３３）の射出側または射出側近傍において２次光源としての多数の集光点が形成される。この結果、例えば図１７に示す反射型の投影光学系の瞳（入射瞳）の位置にはフライアイミラー（１３，１３’，１３”，３３）による２次光源の像が形成されるため、レチクル（マスク）やウエハ（感光性基板）は、均一照明としてのケーラー照明が達成される。
以上のように、各実施の形態及び各実施例における全反射フライアイミラーの関与によって、フライアイミラーにおける光量損失を抑えながら、レチクル（マスク）やウエハ（感光性基板）はより一層均一に照明される。
なお、フライアイミラー（１３，１３’，１３”，３３）の入射側、すなわち第１のアレイ状ミラー（１３ｉｎ，１３’ｉｎ，１３”ｉｎ，３３ｉｎ）の入射側はレチクル（マスク）やウエハ（感光性基板）と実質的に光学的に共役な位置にあり、フライアイミラーを入射側から見た場合、第１のアレイ状ミラー（１３ｉｎ，１３’ｉｎ，１３”ｉｎ，３３ｉｎ）を構成する多数の単位ミラー（第１の反射素子）の形状は、レチクル（マスク）やウエハ（感光性基板）に形成される照明領域の形状と相似である。また、フライアイミラー（１３，１３’，１３”，３３）の射出側、すなわち第２のアレイ状ミラー（１３ｏｕｔ，１３’ｏｕｔ，１３”ｏｕｔ，３３ｏｕｔ）は、例えば図１７に示す投影光学系の瞳（入射瞳）と実質的に光学的に共役な位置にある。
また、図１６に示す第７の実施の形態及び図２４に示す第５実施例においては、第１のアレイ状ミラー３３ｉｎにおける多数の第１の反射素子（３３ｉｎ−１，３３ｉｎ−２，・・・）は、第１の反射素子（３３ｉｎ−１，３３ｉｎ−２，・・・）の各々の中心に入射する入射光（入射光の中心の光またはレチクルの照明視野中心を通過する光）に対して所定の角度β１で傾斜した第１の基準面Ｐ１にて稠密に配置されている。同様に、第２のアレイ状ミラー３３ｏｕｔにおける多数の第２の反射素子（３３ｏｕｔ−１，３３ｏｕｔ−２，・・・）は、第２の反射素子（３３ｏｕｔ−１，３３ｏｕｔ−２，・・・）の各々の中心に入射する入射光（入射光の中心の光またはレチクルの照明視野中心を通過する光）に対して所定の角度β２で傾斜した第２の基準面Ｐ２にて稠密に配置されている。
このとき、上記所定の角度β１及び所定の角度β２は、
０°＜β１≦２０°，０°＜β２≦２０°
を満たすことが好ましい。ここで、上記条件を満たすことにより、第１のアレイ状ミラー３３ｉｎ及び第２のアレイ状ミラー３３ｏｕｔを構成する多数の単位ミラー（反射素子）による配列による光量損失を招くことなく全反射を達成することが可能となるため、格段に反射効率の高いフライアイミラー３３を実現することができる。
なお、以上の各実施の形態及び各実施例においては、反射型オプティカルインテグレータとしてのフライアイミラー（１３，１３’，１３”，３３）は、２つのアレイ状ミラー（ラスター状ミラー）で構成される例を示したが、このフライアイミラー（１３，１３’，１３”，３３）は１つのアレイ状ミラー（ラスター状ミラー）で構成することも可能である。
また、以上の第１実施の形態〜第８実施の形態及び第１〜５実施例においては、レチクル（マスク）に対して光を効率良く導くための照明光学系の結像に寄与する部材を全て全反射させる反射部材で構成した例を示したが、照明光学系の結像への寄与度の小さい部材を必要に応じて用いることは可能である。この場合には、照明光学系の結像への寄与度の小さい部材は、透過性部材、適宜全反射の条件から外れた反射部材であっても良く、これらの部材を本発明において適用可能なことは言うまでもない。
ところで、上述の実施の形態にかかる露光装置では、照明光学系や照明光学装置によってマスク（レチクル）を照明し（照明工程）、投影光学系を用いてマスクに形成された転写用のパターンを感光性基板に露光する（露光工程）ことにより、マイクロデバイス（半導体素子、撮像素子、液晶表示素子、薄膜磁気ヘッド等）を製造することができる。以下、上述の実施の形態の露光装置を用いて感光性基板としてのウェハ等に所定の回路パターンを形成することによって、マイクロデバイスとしての半導体デバイスを得る際の手法の一例につき図２６のフローチャートを参照して説明する。
先ず、図２６のステップ３０１において、１ロットのウェハ上に金属膜が蒸着される。次のステップ３０２において、その１ロットのウェハ上の金属膜上にフォトレジストが塗布される。その後、ステップ３０３において、上述の実施の形態の露光装置を用いて、マスク上のパターンの像がその投影光学系を介して、その１ロットのウェハ上の各ショット領域に順次露光転写される。その後、ステップ３０４において、その１ロットのウェハ上のフォトレジストの現像が行われた後、ステップ３０５において、その１ロットのウェハ上でレジストパターンをマスクとしてエッチングを行うことによって、マスク上のパターンに対応する回路パターンが、各ウェハ上の各ショット領域に形成される。その後、更に上のレイヤの回路パターンの形成等を行うことによって、半導体素子等のデバイスが製造される。上述の半導体デバイス製造方法によれば、極めて微細な回路パターンを有する半導体デバイスをスループット良く得ることができる。
また、上述の実施の形態の露光装置では、プレート（ガラス基板）上に所定のパターン（回路パターン、電極パターン等）を形成することによって、マイクロデバイスとしての液晶表示素子を得ることもできる。
以下、図２７のフローチャートを参照して、このときの手法の一例につき説明する。
図２７において、パターン形成工程４０１では、上述の実施の形態の露光装置を用いてマスクのパターンを感光性基板（レジストが塗布されたガラス基板等）に転写露光する、所謂光リソグラフィー工程が実行される。この光リソグラフィー工程によって、感光性基板上には多数の電極等を含む所定パターンが形成される。その後、露光された基板は、現像工程、エッチング工程、レジスト剥離工程等の各工程を経ることによって、基板上に所定のパターンが形成され、次のカラーフィルター形成工程４０２へ移行する。
次に、カラーフィルター形成工程４０２では、Ｒ（Ｒｅｄ）、Ｇ（Ｇｒｅｅｎ）、Ｂ（Ｂｌｕｅ）に対応した３つのドットの組がマトリックス状に多数配列されたり、またはＲ、Ｇ、Ｂの３本のストライプのフィルターの組を複数水平走査線方向に配列したカラーフィルターを形成する。そして、カラーフィルター形成工程４０２の後に、セル組み立て工程４０３が実行される。セル組み立て工程４０３では、パターン形成工程４０１にて得られた所定パターンを有する基板、及びカラーフィルター形成工程４０２にて得られたカラーフィルター等を用いて液晶パネル（液晶セル）を組み立てる。
セル組み立て工程４０３では、例えば、パターン形成工程４０１にて得られた所定パターンを有する基板とカラーフィルター形成工程４０２にて得られたカラーフィルターとの間に液晶を注入して、液晶パネル（液晶セル）を製造する。その後、モジュール組み立て工程４０４にて、組み立てられた液晶パネル（液晶セル）の表示動作を行わせる電気回路、バックライト等の各部品を取り付けて液晶表示素子として完成させる。上述の液晶表示素子の製造方法によれば、極めて微細な回路パターンを有する液晶表示素子をスループット良く得ることができる。Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, 4, 4, 5, 6, 7, and 8. FIG. This embodiment is an embodiment of an illumination optical system.
FIG. 1 is a schematic configuration diagram of an illumination optical system according to the present embodiment. In FIG. 1, the reference numerals 12A, 12B, 12C, 13 ′, and 13 ″ are added to the constituent elements of the embodiments described later, and will not be described here.
This illumination optical system is mainly applied to a projection exposure apparatus provided with a reflection type projection optical system, and performs Koehler illumination on a reticle surface R of the projection exposure apparatus.
The light source unit 11 of the illumination optical system is a light source unit that emits EUV light (hereinafter referred to as EUV light having a wavelength of 50 nm or less).
A laser plasma light source using an efficient Xe as a target, a discharge plasma light source, or the like can be applied to the light source unit 11.
In particular, since the discharge plasma light source has a relatively high energy efficiency, it is advantageous in realizing a high throughput.
In the illumination optical system, a collimator mirror 12, a fly-eye mirror 13, and a condenser mirror 14 are sequentially arranged on the emission side of the light source unit 11.
The collimator mirror 12 has a plurality of unit mirrors 12-1, 12-2,.
The fly-eye mirror 13 includes an incident end 13in in which a plurality of unit mirrors 13in-1, 13in-2,... Are arranged in parallel, and an exit end in which a plurality of unit mirrors 13out-1, 13out-2,. 13 out.
The condenser mirror 14 has a plurality of unit mirrors 14-1, 14-2,.
Here, the parallel arrangement is an arrangement that individually acts on different partial light fluxes of the incident light flux, and the serial arrangement is an arrangement that sequentially acts on the entire incident light flux.
These unit mirrors 12-1, 12-2, ..., 13in-1, 13in-2, ..., 13out-1, 13out-2, ..., 14-1, 14-2, Are set so that the oblique incident angle (angle formed with the reflecting surface) of incident light (here, EUV light having a wavelength of 50 nm or less) with respect to the reflecting surfaces becomes the total reflection angle.
The ideal total reflection is a reflection with a reflectance of 100%, but in actuality, a slight loss of light quantity must be allowed. The oblique incident angle at which the incident light is totally reflected is referred to as “total reflection angle”.
Further, these unit mirrors 12-1, 12-2, ..., 13in-1, 13in-2, ..., 13out-1, 13out-2, ..., 14-1, 14-2, .. Are made of Mo or Ru, respectively.
2, 3 and 4 are diagrams showing the relationship between the oblique incidence angle of EUV light having a wavelength of 13.5 nm and the reflectance.
2 shows Mo reflectivity, FIG. 3 shows Ru reflectivity, and FIG. 4 shows MoSi. ₂ Is the reflectance.
These are all typical materials used for the reflecting surface, but in any case, the smaller the oblique incident angle of incident light, the higher the reflectance.
2, 3 and 4, the total reflection angle of Mo is about 15 ° or less, the total reflection angle of Ru is about 15 ° or less, MoSi ₂ The total reflection angle is about 10 ° or less.
In particular, the total reflection angle at which the reflectivity is 90% or more is about 10 ° or less for Mo, about 8 ° or less for Ru, MoSi ₂ Is about 5 ° or less.
In other words, the total reflection angle when Mo or Ru material is used is MoSi. ₂ This is larger than the total reflection angle when the material is used.
In the present embodiment, unit mirrors 12-1, 12-2,..., 13in-1, 13-in-2,..., 13out-1, 13out-2,. Since a Mo or Ru material is used for each of the reflecting surfaces 14-2,..., The total reflection angle is a relatively large 15 ° or less.
Therefore, the degree of freedom in the layout design of each reflecting surface is higher than when other materials are used.
However, if a difference in intensity due to the difference in reflectance between sp-polarized light becomes a problem, MoSi is partially or entirely on each reflecting surface. ₂ These materials may be used.
FIG. 5 is a diagram illustrating the collimator mirror 12 according to the present embodiment.
FIG. 5A is a cross-sectional view of the collimator mirror 12 taken along a plane including the optical axis Z, and FIG. 5B is a perspective view of the collimator mirror 12.
As shown in FIG. 5 (a), the collimator mirror 12 has a plurality of skirt-shaped unit mirrors 12-1, 12-2,. They are arranged around the optical axis Z in a state of being directed to the emission side (the number of unit mirrors is 3 in the figure).
Each of the unit mirrors 12-1, 12-2,... Has a reflecting surface inside.
In converting the incident light beam into a parallel light beam, the unit mirror that deflects the peripheral light beam (that is, the unit mirror having a large diameter and disposed outside) has a larger spread angle.
Further, the reflecting surfaces of the unit mirrors 12-1, 12-2,... Are each formed in the shape of a partial side surface of a cone, as shown in FIGS.
The collimator mirror 12 including such unit mirrors 12-1, 12-2,... Individually converts the light beams emitted from the light source unit 11 at different emission angles into parallel light beams.
Here, in this collimator mirror 12, as described above, the oblique incident angle θ (see FIG. 5A) of the incident light with respect to the reflecting surfaces of the unit mirrors 12-1, 12-2,. It must be suppressed to a reflection angle (here, 15 ° or less).
However, with this configuration, there is a possibility that the oblique incident angle of all incident light on the collimator mirror 12 cannot be made the total reflection angle (here, 15 ° or less). In particular, the oblique incident angle of incident light on the unit mirror having a large diameter (unit mirror disposed outside) may be larger than the total reflection angle (here, 15 ° or less).
In that case, the collimator mirror 12 may be modified like a collimator mirror 12 ′ shown in FIG.
FIG. 6 is a diagram illustrating the collimator mirror 12 ′.
6A is a cross-sectional view of the collimator mirror 12 ′ cut along a plane including the optical axis Z, and FIG. 6B is a perspective view of the collimator mirror 12 ′.
The unit mirror 12-1 arranged on the outermost periphery of the collimator mirror 12 ′ has a plurality of unit mirrors 12-1-1, 12-1-2,... Arranged in series (in FIG. 6, in series arrangement). The number of unit mirrors to be used is 3.)
Each of the unit mirrors 12-1-1, 12-1-2,... Has a skirt shape like the unit mirror 12-1 of the collimator mirror 12 shown in FIG. The shape of the partial side.
The unit mirrors 12-1-1, 12-1-2, 12-1-3,... Sequentially reflect the incident light from the light source unit 11, thereby making the incident light parallel to the optical axis Z. Convert to light and emit.
Similarly, a plurality of unit mirrors may be arranged in series for each of the unit mirrors 12-2, 12-3,... Other than the outermost periphery (12-2-1, 12-2-2). 12-2-3, 12-3-1, 12-3-2, 12-3-3).
Next, the fly-eye mirror 13 (see FIG. 1) will be described.
As described above, the postures of the unit mirrors 13in-1, 13in-2,..., 13out-1, 13out-2,. (Here, 15 ° or less).
For this reason, the entrance end 13in and the exit end 13out of the fly-eye mirror 13 are arranged at a sufficient interval in the traveling direction of the reflected light by the unit mirrors.
FIG. 7 is a diagram for explaining the fly-eye mirror 13.
FIG. 7A shows the incident end 13 in of the fly-eye mirror 13, and FIG. 7B shows the emission end 13 out of the fly-eye mirror 13. 7A is a view from the collimator mirror 12 side, and FIG. 7B is a view from the condenser mirror 14 side.
FIG. 8 is a diagram for explaining the shape of the reflecting surfaces of the unit mirrors 13in-1, 13in-2,... Arranged at the incident end 13in of the fly-eye mirror 13. As shown in FIG.
The reflecting surfaces of the unit mirrors 13in-1, 13in-2,... Form secondary light sources on the unit mirrors 13out-1, 13out-2,. Each has a partial paraboloid shape.
Moreover, the external shape of the reflecting surface of the unit mirrors 13in-1, 13in-2,... Is similar to the exposure area of the projection exposure apparatus. Here, it is assumed that the exposure area is an arc field.
Next, the capacitor mirror 14 (see FIG. 1) will be described.
The condenser mirror 14 sequentially reflects the light beam emitted from the emission end 13out by the unit mirrors 14-1, 14-2,..., And the secondary light source group formed at the emission end 13out is reflected on the reticle surface R. Project by superimposing on the arc field.
The shape of at least one reflecting surface of these unit mirrors 14-1, 14-2,... Is a “toroidal aspheric surface” defined by the equation (1) described later.
The illumination optical system according to the present embodiment including the light source unit 11, the collimator mirror 12 (or 12 ′), the fly-eye mirror 13, and the condenser mirror 14 described above includes each mirror composed of a plurality of unit mirrors, Since the total reflection action of the reflecting surface is used, the light quantity loss of the EUV light can be reduced.
According to such an illumination optical system, the reticle surface R is illuminated with a sufficient amount of EUV light.
In the illumination optical system according to the present embodiment, the oblique incident angle with respect to each reflecting surface is positively set to the total reflection angle (15 ° in this case), so that it is not necessary to form a multilayer film on each reflecting surface.
In the illumination optical system of the present embodiment, the reflecting surfaces of the unit mirrors 12-1, 12-2,... Of the collimator mirror 12 have a relatively simple conical partial side shape. The side is not only similar to a partial paraboloid (part of the paraboloid), which is an ideal shape for converting a divergent light beam into a parallel light beam, but also simpler than that partial paraboloid It is a curved surface.
Therefore, the unit mirrors 12-1, 12-2,... Can be thinned while performing a desired function.
If the unit mirrors 12-1, 12-2,... Are thinned, vignetting of light rays at the incident end of the collimator mirror 12 is reduced, so that the light amount loss is further reduced.
Further, if the collimator mirror 12 ′ shown in FIG. 6 is applied, it is assigned to each of the unit mirrors 12-1-1, 12-1-2,. Since the deflection angle of the light beam is smaller than when the unit mirrors arranged in series are single (see FIG. 5), the oblique incident angle of the incident light is set as the total reflection angle (here, 15 ° or less), Light loss can be reliably suppressed.
In this collimator mirror 12 ′, the oblique incident angle of each reflection is reduced by an amount corresponding to the increase in the number of unit mirrors arranged in series (for example, about 6 °. In that case, the reflectance is 90% or more). it can. In this way, total reflection can be achieved with a higher reflectance.
In the fly-eye mirror 13, the postures of the unit mirrors 13in-1, 13in-2,..., 13out-1, 13out-2,. If it is set so as to be further reduced (for example, about 6 °, the reflectance in that case is 90% or more), the light quantity loss can be further suppressed.
In addition, since the “toroidal aspheric surface” (see Expression (1)) is used for the reflecting surfaces of the unit mirrors 14-1, 14-2,. Is effectively removed.
Further, in the condenser mirror 14, the unit mirrors 14-1, 14-2,... Are arranged so that the oblique incident angle of incident light with respect to their reflecting surfaces is further reduced (for example, about 6 °. If the reflectance is set to 90% or more), the light quantity loss can be further suppressed.
In the above description, it is desirable to make the oblique incident angle of incident light with respect to the reflecting surface as small as possible. However, when the number of unit mirrors arranged in series with each other is increased, the light amount loss due to the increase in the number of reflections. In consideration of this increase, it is necessary to design so that the light amount loss in the whole of the plurality of unit mirrors is reduced.
[Second Embodiment]
A second embodiment of the present invention will be described based on FIG. 1, FIG. 9, and FIG. This embodiment is an embodiment of an illumination optical system.
Here, only differences from the illumination optical system of the first embodiment will be described. The difference is that a collimator mirror 12 ″ is applied instead of the collimator mirror 12 (or 12 ′) shown in FIG. 1, and a capillary array 12B and a cooling device 12C are added.
FIG. 9 is a diagram illustrating the collimator mirror 12 ″ according to the present embodiment.
FIG. 9A is a cross-sectional view of the collimator mirror 12 ″ cut along a plane including the optical axis Z, and FIG. 9B is a perspective view of the collimator mirror 12 ″.
As shown in FIG. 9A, the collimator mirror 12 ″ is configured by disposing a skirt-shaped unit mirror 12A having a reflective surface on the outer peripheral side of the collimator mirror 12 ′.
The shape of the reflection surface of the unit mirror 12 </ b> A is a part of a paraboloid (partial paraboloid) having a center line on the optical axis Z and having a focal point at the position of the light source unit 11.
A Mo or Ru material is also used for the reflecting surface of the unit mirror 12A. However, when the difference in intensity due to the difference in reflectance between sp-polarized light becomes a problem, MoSi is applied to the reflecting surface. ₂ These materials are used.
The oblique incident angle of incident light (here, EUV light having a wavelength of 50 nm or less) with respect to the reflecting surface of the unit mirror 12A is the total reflection angle (here 15 ° or less, provided that MoSi is used). ₂ 10 ° or less when used).
Next, the capillary array 12B will be described.
The capillary array 12B is disposed on the emission side of the collimator mirror 12 ″.
The capillary array 12B is cooled by the cooling device 12C.
FIG. 10 is a diagram illustrating the capillary array 12B.
10A is a cross-sectional view of the capillary array 12B cut along a plane including the optical axis Z, and FIG. 10B is a perspective view of the capillary array 12B.
As shown in FIGS. 10A and 10B, the capillary array 12B has a plurality of hollow glass tubes 12B-1, 12B-2,.
The hollow glass tubes 12B-1, 12B-2,... Are bundled so that the entrance end 12Bin and the exit end 12Bout of the capillary array 12B have the same circular shape.
As described above, the collimator mirror 12 ″ of the embodiment shown in FIG. 9 has a high numerical aperture in order to convert light having a high numerical aperture (large divergence angle) into collimated light with high efficiency without incurring light loss. Reflector for high numerical aperture (outer unit mirror: 12A) that reflects light rays with a large divergence angle and light rays with a smaller numerical aperture (large divergence angle) than a high numerical aperture (large divergence angle) And a non-high numerical aperture reflecting portion (inner unit mirrors: 12A-1, 12A-2,...).
As described above, in the illumination optical system of the present embodiment, the reflecting surface of the unit mirror 12A arranged on the outer peripheral side of the collimator mirror 12 ″ has a partial paraboloid shape.
Since the paraboloid has an ideal shape for converting a divergent light beam into a parallel light beam, according to the unit mirror 12A, the peripheral light beam (light beam having a large divergence angle) emitted from the light source unit 11 is reliably parallel. It is converted into luminous flux.
Therefore, the light quantity loss of EUV light can be suppressed to a smaller extent.
Although the unit mirror 12A is difficult to thin because it uses a paraboloid, the necessity for thinning is low because the arrangement location is the outermost periphery, and there is no problem.
In particular, when the discharge plasma light source is applied to the light source unit 11 and this collimator mirror 12 ″ is used in combination, the light beam emitted from the light source unit 11 is efficiently converted into a parallel light beam.
In the above embodiment, the reflecting surface of the unit mirror 12A on the outer periphery of the collimator mirror 12 ″ has a rectangular shape. However, in the present invention, the shape is not limited to this shape. Needless to say, the mirror can be configured by combining a mirror-like reflecting surface and a hyperboloid-like reflecting surface.
Further, since the capillary array 12B is arranged in the illumination optical system of the present embodiment, the non-parallel light beam included in the light beam emitted from the collimator mirror 12 ″ (the collimator mirror 12 ″ has failed to be collimated). Is removed).
Further, the capillary array 12B also removes scattered matters (generated in the light source unit 11) included in the emitted light flux.
Further, since the capillary array 12B is cooled by the cooling device 12C, the effect of removing them can be obtained to the maximum.
In the illumination optical system of the present embodiment, the collimator mirror 12 ″, the capillary array 12B, and the cooling device 12C are combined. However, in the illumination optical system of the present embodiment, the capillary array 12B, the cooling device 12C, and An illumination optical system in which the cooling device 12C is omitted in the illumination optical system of the present embodiment can be realized.
Further, an illumination optical system to which the capillary array 12B and the cooling device 12C are applied in the illumination optical system of the first embodiment and an illumination optical system to which the capillary array 12B is applied in the first embodiment can be realized.
[Third Embodiment]
A third embodiment of the present invention will be described with reference to FIGS. This embodiment is an embodiment of an illumination optical system.
Here, only differences from the illumination optical system of the first embodiment or the second embodiment will be described. The difference is that a fly-eye mirror 13 ′ is applied instead of the fly-eye mirror 13 shown in FIG.
FIG. 11 is a diagram for explaining the shape of the reflecting surface of the unit mirrors 13′in-1, 13′in-2,... Arranged at the incident end 13′in of the fly-eye mirror 13 ′ of the present embodiment. It is.
Each of these reflecting surfaces has a Walter I shape.
The Walter I shape is composed of a first surface that is a partial paraboloid and a second surface that is a partial hyperboloid.
The center line of the paraboloid and the hyperboloid is on the same straight line, and the focal point of the paraboloid coincides with one of the two focal points F1 and F2 of the hyperboloid.
The first surface and the second surface are surfaces that can be obtained by partially cutting a paraboloid and a hyperboloid in the vicinity of the line of intersection of the two.
Such a unit mirror 13′in-i is arranged in such a posture that the center line is parallel to the optical axis Z.
The condensing position of the light beam by the unit mirror 13′in-i is a focal point F2.
A unit mirror 13′out-i corresponding to the unit mirror 13′in-i (a unit mirror disposed at the emission end 13′out) is disposed at the focal point F2.
The reflecting surfaces of these unit mirrors 13′in-1, 13′in-2,..., 13′out-1, 13′out-2,. used. However, when the difference in intensity due to the difference in reflectance between sp-polarized light becomes a problem, MoSi is applied to the reflecting surface. ₂ These materials are used.
In addition, incident light on the reflecting surfaces of these unit mirrors 13′in-1, 13′in-2,..., 13′out-1, 13′out-2,. The oblique incident angle of EUV light is the total reflection angle (here, 15 ° or less, but MoSi ₂ 10 ° or less when used).
As described above, in the illumination optical system according to the present embodiment, since each reflecting surface of the entrance end 13′in of the fly-eye mirror 13 ′ has a Walter I shape, the Abbe sine condition can be satisfied. The outer shapes of the reflecting surfaces can be made to be an exact similar shape (here, an arc field) of the exposure area.
As a result, since EUV light is guided to a necessary area without waste, the light quantity loss is further suppressed.
[Fourth embodiment]
A fourth embodiment of the present invention will be described with reference to FIGS. This embodiment is an embodiment of an illumination optical system.
Here, only differences from the first embodiment, the second embodiment, and the third embodiment will be described. The difference is that a fly-eye mirror 13 ″ is applied instead of the fly-eye mirror 13 (or 13 ′) shown in FIG.
FIG. 12 shows unit mirrors 13 ″ in−1, 13 ″ in−2,... Arranged at the input end 13 ″ in of the fly-eye mirror 13 ″ of the present embodiment, and the output end 13 ″ out. It is a figure explaining the shape of the reflective surface of unit mirror 13 "out-1,13" out-2, ... used.
The reflection surface of the unit mirror 13 ″ in-i has a partial paraboloid shape.
The reflection surface of the unit mirror 13 ″ out-i also has a partial paraboloid shape.
The former paraboloid and the latter paraboloid have the same shape, center line, and focal point F, and are opposite to each other only in the direction of the apex.
Note that the parabolas of the former and the latter may be slightly shifted as necessary.
The reflecting surface of the unit mirror 13 ″ in-i and the reflecting surface of the unit mirror 13 ″ out-i can be obtained by cutting off the two paraboloids from each other with respect to the focal point F.
The unit mirror 13 ″ in-i and the unit mirror 13 ″ out-i are arranged in such a posture that the center line is parallel to the optical axis Z.
The light beam incident on the unit mirror 13 ″ in-i is once condensed at the focal point F, and then enters the unit mirror 13 ″ out-i while diverging.
These unit mirrors 13 "in-1, 13" in-2,..., 13 "out-1, 13" out-2,... Is done. However, when the difference in intensity due to the difference in reflectance between sp-polarized light becomes a problem, MoSi is applied to the reflecting surface. ₂ These materials are used.
In addition, incident light (in this case, EUV light having a wavelength of 50 nm or less) with respect to the reflecting surfaces of these unit mirrors 13 "in-1, 13" in-2, ..., 13 "out-1, 13" out-2 The oblique incident angle is the total reflection angle (here 15 ° or less, but MoSi ₂ 10 ° or less when used).
As described above, in the illumination optical system according to the present embodiment, the reflection surfaces of the entrance end 13 ″ in and the exit end 13 ″ out of the fly-eye mirror 13 ″ have a paraboloid shape, so that the Abbe sine The conditions can be satisfied, and the external shape of the reflecting surfaces can be made to be an exact similarity (here, an arc field) of the exposure area.
As a result, since EUV light is guided to a necessary area without waste, the light quantity loss is further suppressed.
In the fly-eye mirror 13 ″ according to the present embodiment, the unit mirrors 13 ″ out-1, 13 ″ out-2,... Are displaced from the light beam condensing position. The damage of the reflective surface of 13 ″ out-1, 13 ″ out-2,.
[Fifth Embodiment]
A fifth embodiment of the present invention will be described with reference to FIG. The present embodiment is an embodiment of another light source unit that can be applied to each of the illumination optical systems described above.
FIG. 13 is a diagram illustrating a schematic configuration of the light source unit 21 and the periphery thereof according to the present embodiment.
Air around the illumination optical system including the light source unit 21 is exhausted by the vacuum chamber 21e, the exhaust pipe 21f, and the vacuum pump 21g (note that the illumination optical systems in the above embodiments are also exhausted in the same manner. However, the explanation was omitted.)
A laser plasma light source that emits EUV light is applied to the light source unit 21 of the present embodiment.
The light source unit 21 includes a laser light source 21a, a plasma supply source 21b that supplies plasma to laser light emitted from the laser light source 21a, and a collector mirror that collects EUV light generated by the reaction of the laser light and plasma ( In FIG. 1, an elliptical mirror) 21c and a vacuum chamber 21d are provided.
The reflective surface of the collector mirror 21c, which is an elliptical mirror, is provided with a multilayer film for improving the reflectance of EUV light.
The vacuum chamber 21d accommodates a laser light source 21a, a plasma supply source 21b, and a collector mirror 21c inside the vacuum chamber 21e.
One of the side walls of the vacuum chamber 21d is disposed so as to cross the optical axis in the vicinity of the EUV light condensing point by the collector mirror 21c, and an opening is provided in the vicinity of the condensing point of the side wall. A pinhole plate P whose pinhole center coincides with the optical axis is provided in the opening. Therefore, the substantial opening of the vacuum chamber 21d becomes the pinhole.
The air in the vacuum chamber 21d is exhausted by the exhaust pipe 21f and the vacuum pump 21g.
For this reason, the air pressure inside the vacuum chamber 21d is kept low compared with the air pressure of the other part of the illumination optical system.
Here, generally, a large amount of scattered matter is generated in the light source unit 21 that generates EUV light.
However, in the present embodiment, the scattered matter is shielded by the shielding portion (portion other than the pinhole) of the pinhole plate P described above.
Moreover, the air pressure inside the vacuum chamber 21d is lower than the air pressure of other parts.
Therefore, the scattered matter is exhausted to the outside through the exhaust pipe 21f and the vacuum pump 21g provided in the vacuum chamber 21d without going from the pinhole of the pinhole plate P to the collimator mirror 12 side.
Therefore, according to the light source unit 21 of the present embodiment, the influence of the scattered matter generated in the light source unit 21 on the optical system after the collimator mirror 12 is eliminated.
The positional relationship between the pinhole plate P and the condensing point in the optical axis direction is preferably selected based on experiments or the like so that scattered objects are removed most efficiently.
Further, the pinhole of the pinhole plate P does not need to be a complete opening, and may be covered with a film made of beryllium or the like as long as it can transmit EUV light.
[Sixth Embodiment]
A sixth embodiment of the present invention will be described with reference to FIGS. The present embodiment is an embodiment of another light source unit that can be applied to each of the illumination optical systems described above. Here, only differences from the light source unit of the fifth embodiment will be described.
FIG. 14 is a diagram showing a schematic configuration of the light source unit 31 and the periphery thereof according to the present embodiment.
Air around the illumination optical system including the light source 31 is exhausted by the vacuum chamber 21e, the exhaust pipe 21f, and the vacuum pump 21g (note that each illumination optical system in the above embodiments is also exhausted in the same manner. , Explanation was omitted.)
A discharge plasma light source that emits EUV light is applied to the light source unit 31 of the present embodiment.
The light source unit 31 includes a discharge plasma light source 31a, a collector mirror 31c that collects EUV light (diverged light) emitted from the discharge plasma light source 31a, and a vacuum chamber 31d.
The vacuum chamber 31d accommodates the discharge plasma light source 31a and the collector mirror 31c inside the vacuum chamber 21e.
The vacuum chamber 31d is also provided with a pinhole plate (a pinhole plate in which pinholes are arranged in the vicinity of the condensing point) P similar to the vacuum chamber 21d of the first embodiment. It is a pinhole of the pinhole plate P.
The air in the vacuum chamber 31d is exhausted by the exhaust pipe 21f and the vacuum pump 21g.
Therefore, according to the light source unit 31 of the present embodiment, the influence of scattered objects given to the optical system after the collimator mirror 12 is removed, as in the light source unit 21 of the fifth embodiment.
FIG. 15 is a diagram (perspective view) for explaining the collector mirror 31c of the present embodiment.
As shown in FIG. 15, the collector mirror 31c of this embodiment has an oblique incident angle θ with respect to each reflecting surface, similar to the collimator mirror 12 (see FIG. 5) and the collimator mirror 12 ′ (see FIG. 6) described above. It is composed of a plurality of unit mirrors that are suppressed to a total reflection angle.
The shape of the reflection surface of each unit mirror is a predetermined shape necessary for the collector mirror, such as the shape of a part of the reflection surface of the elliptical mirror or the shape of the side surface of the cone, or an approximate shape thereof.
According to the light source unit 31 of the present embodiment in which such a collector mirror 31c is used, the light amount loss of the EUV light can be suppressed to a low level.
In addition, like the collector mirror 31c in the light source unit 31 of the present embodiment, the collector mirror 21c of the light source unit 21 of the fifth embodiment is made plural (a plurality of unit mirrors whose oblique incident angles are suppressed to the total reflection angle). Configuration).
Further, like the collector mirror 21c in the light source unit 21 of the fifth embodiment, the collector mirror 31c of the light source unit 31 of the present embodiment may be an elliptical mirror.
However, in view of the divergence angle of the light emitted from the light source, an elliptical mirror is suitable for the laser plasma light source, and a plurality of mirrors are suitable for the discharge plasma.
[Seventh embodiment]
A seventh embodiment of the present invention will be described with reference to FIG. This embodiment is an embodiment of another fly-eye mirror that can be applied to each illumination optical system. Here, only differences from the fly-eye mirrors of the above embodiments will be described.
FIG. 16 is a diagram for explaining the arrangement relationship of the unit mirrors of the fly-eye mirror 33 according to the present embodiment.
The plurality of unit mirrors 33in-1, 33in-2,... Constituting the incident end 33in of the fly-eye mirror 33 are not only in the direction (XY direction) perpendicular to the incident light but also in the traveling direction of the incident light (Z direction). ) Are also shifted by a sufficient distance.
Similarly, the plurality of unit mirrors 33out-1, 33out-2,... Constituting the emission end 33out of the fly-eye mirror 33 are also shifted by a sufficient distance not only in the XY direction but also in the Z direction.
Here, the sufficient distance is a distance that reduces the amount of vignetting by the other unit mirrors of reflected light in each unit mirror (preferably eliminates vignetting).
That is, in the fly-eye mirror 33 according to the present embodiment, when the incident end 33in of the fly-eye mirror 33 is viewed from the collimator mirror 12, the unit mirrors 33in-1, 33in-2,. The overlap is reduced (preferably 0), and each unit mirror 33out-1, 33out-2,... When the emission end 33out of the fly-eye mirror 33 is viewed from the condenser mirror 14 side. Is reduced (preferably zero).
According to the fly eye mirror 33 of the present embodiment as described above, the light amount loss is reduced.
[Eighth Embodiment]
The eighth embodiment of the present invention will be described with reference to FIG. This embodiment is an embodiment of a projection exposure apparatus.
FIG. 17 is a block diagram of the projection exposure apparatus of the present embodiment.
The projection exposure apparatus of the present embodiment is a reduction projection type projection exposure apparatus that uses EUV light (for example, EUV light with a wavelength of 50 nm or less) as an exposure beam and performs a scanning exposure operation by a step-and-scan method.
A projection optical system 200 and an illumination optical system 100 are mounted on the projection exposure apparatus. The illumination optical system 100 is the illumination optical system according to any of the embodiments described above.
The illumination optical system 100 illuminates the surface (reticle surface) R of the reticle 102 disposed on the object plane of the projection optical system 200.
The projection optical system 200 projects the principal ray of the reflected light beam on the reticle surface R substantially vertically onto the wafer 10 disposed on the image plane side.
The projection optical system 200 is non-telecentric on the object plane side and telecentric on the image plane side, and includes a plurality of (for example, about 2 to 8, four in FIG. 17) reflecting mirrors 106, 107, 108, 109. (A projection magnification of 1/4, 1/5, 1/6, etc.).
In addition, the projection exposure apparatus includes a reticle stage 103 that holds the reticle 102, a wafer stage 110 that holds the wafer 10, and the like.
As described in the first embodiment, according to the illumination optical system 100, only the necessary area of the reticle 102 is uniformly illuminated with a sufficient amount of EUV light.
Therefore, even if the projection optical system 200 has the same configuration as the conventional one, the performance of the projection exposure apparatus is improved.
[First embodiment]
A first embodiment of the present invention will be described based on FIGS. 18, 19, 20, Table 1, Table 2, Table 3, Table 4, Table 5, Table 6, Table 7, Table 8.
This example is an example corresponding to the first embodiment (using the collimator mirror 12 ′).
FIG. 18 is a cross-sectional view showing the configuration of the collimator mirror 12 ′ of this embodiment, and Tables 1, 2, 3, and 4 show data of the collimator mirror 12 ′. The unit of numerical values in the table is [mm] unless otherwise specified (the same applies to other tables).
As shown in FIG. 18, the collimator mirror 12 ′ of this embodiment includes unit mirrors 12-1 (cone 1), 12-2 (cone 2),. It consists of a total of 17 unit mirrors of a cone 17).
Further, the cone 1, the cone 2,..., And the cone 17 are each divided into a total of four blocks from the entrance side to the exit side, that is, a first block, a second block, a third block, and a fourth block.
In Table 1, Table 2, Table 3, and Table 4, the data of each block of each cone are shown for each block. Table 1 shows data for each cone in the first block, Table 2 shows data for each cone in the second block, Table 3 shows data for each cone in the third block, and Table 4 shows data for each cone in the fourth block.
In each table, the shape of each cone of each block is indicated by two coordinates (Z1, Radius 1) and (Z2, Radius 2).
The coordinates of the two points (Z1, Radius1), (Z2, Radius2) are the coordinates of the ends of the cross section formed by cutting the cone on the plane including the optical axis Z (YZ plane) as shown in the circle in FIG. It is.
In each table, the “normalized diameter height” of each cone means the radius of each cone (height in the direction perpendicular to the optical axis Z), which is the largest opening angle in the same block (the optical axis and the cone form). The value obtained by dividing the opening angle of the angle cone by this maximum opening angle is 1.

FIG. 19 is an optical path diagram showing the configuration of the fly-eye mirror 13 of the present embodiment.
As shown in FIG. 19, at the incident end 13in of the fly-eye mirror 13, ten unit mirrors 13in-1, 13in-2,..., 13in-10 are shifted by 3 mm in the Y direction.
Further, at the exit end 13out of the fly-eye mirror 13, ten unit mirrors 13out-1, 13out-2,..., 13out-10 are arranged by shifting by 3 mm in the Y direction.
Table 5 shows data of the fly-eye mirror 13.

Incidentally, since the diameter of the exit end of the collimator mirror 12 is 140 mm (see Tables 1 to 4), the entrance end 13in of the fly-eye mirror 13 of this embodiment has about 43 sheets in the Y direction at the maximum. A maximum of 13 unit mirrors can be arranged in the X direction.
Further, in order to adapt to the optical characteristics of the condenser mirror 14 described later, unit mirrors 13out-1, 13out-2,..., 13out-10 arranged at the exit end 13out of the fly-eye mirror 13 will be described later. Each region (point A, point B, point C, point D) corresponding to point A, point B, point C, point D of the condenser mirror 14 is provided with an inclination corresponding to the angle shown in Table 6.

FIG. 20 is an optical path diagram showing the configuration of the condenser mirror 14 of the present embodiment.
The condenser mirror 14 has a total of three unit mirrors, unit mirrors 14-1, 14-2, and 14-3, arranged in order from the fly-eye mirror 13 side.
Table 7 shows data of the capacitor mirror 14.
In Table 7, the ray tracing direction (surface order) is opposite to the actual light traveling direction (direction from the reticle surface R to the fly-eye mirror 13, unit mirrors 14-3, 14-2, 14-1). In the order). The reflecting surfaces of the unit mirrors 14-1, 14-2, 14-3 are inclined by 15 ° with respect to the optical axis.

The reflecting surfaces of the unit mirrors 14-1, 14-2, and 14-3 are each formed of a toroidal aspheric surface.
Table 8 shows the toroidal aspheric coefficient of each reflecting surface. In addition, the definition formula of a toroidal aspherical surface is represented by Formula (1). Z in the formula (1) is the Sag amount of the aspheric surface in the optical axis direction.

[Second Embodiment]
A second embodiment of the present invention will be described based on FIG. 21, Table 9, Table 10, Table 11, Table 12, Table 13, Table 14, and Table 15.
This example is an example corresponding to the second embodiment.
Here, only differences from the first embodiment will be described. The difference is that a collimator 12 ″ is applied in place of the collimator mirror 12.
FIG. 21 is a diagram showing the positional relationship between the reflecting surfaces of the collimator mirror 12 ″ of this embodiment. Table 9, Table 10, Table 11, Table 12, Table 13, Table 14, and Table 15 show the collimator mirror 12. Data.
As shown in FIG. 21, in the collimator mirror 12 ″ of this example, the unit mirror 12A described in the second embodiment is arranged on the outermost periphery.
Table 9 shows data of the unit mirror 12A.
In the table, “Z = 0” indicates the position in the optical axis Z direction of the incident side end of the unit mirror 12A. The “light shielding angle” is the maximum value of the angle formed between the tangent line at each position on the reflecting surface and the light beam incident on the position. The “full length” is the length in the direction of the optical axis Z.

Further, the collimator mirror 12 ″ has unit mirrors 12-1 (cone 1), 12-2 (cone 2),..., 12-12 (cone in order from the larger diameter inside the unit mirror 12A. 12) a total of 12 unit mirrors are provided.
Further, the cone 1, the cone 2,..., And the cone 12 are each a total of six blocks including the first block, the second block, the third block, the fourth block, the fifth block, and the sixth block from the entrance side to the exit side. Multiple blocks.
Table 10, Table 11, Table 12, Table 13, Table 14, and Table 15 show the data of each block of each cone for each block. Table 10 is data for each cone of the first block, Table 11 is data for each cone of the second block, Table 12 is data for each cone of the third block, Table 13 is data for each cone of the fourth block, Table 14 Is the data for each cone in the fifth block, and Table 15 is the data for each cone in the sixth block.
The notation method of each table is the same as that applied to Table 1, Table 2, Table 3, and Table 4.

Incidentally, according to the collimator mirror 12 ″ of the present embodiment described above, a partial paraboloidal reflecting surface (unit mirror 12A) for light rays incident in an angle range corresponding to “normalized diameter height” 1 to 0.75. For the light rays that are reflected by the light beam and incident in an angle range corresponding to “normalized diameter height” of 0.75 or less, the reflecting surface having the shape of a partial side surface of the cone (unit mirrors 12-1, 12-2,... ) Is reflected.
[Third embodiment]
A third embodiment of the present invention will be described with reference to FIG.
This example is an example corresponding to the third embodiment.
Here, only differences from the first embodiment or the second embodiment will be described. The difference is that a fly eye mirror 13 ′ is applied instead of the fly eye mirror 13.
FIG. 22 is a diagram for explaining the shapes of the reflecting surfaces of the unit mirrors 13′in-1, 13′in-2,... Arranged at the incident end 13′in of the fly-eye mirror 13 ′ of the present embodiment. is there.
The shape of the reflecting surfaces of the unit mirrors 13′in-1, 13′in-2,... Is the Walter I type as described in the third embodiment. The dimensions of each part of the Walter I shape are as follows.
・ Diameter of paraboloid or hyperboloid cut out as a reflecting surface = 2000 mm
-The distance between the focal point F2 or F1 and the apex of the hyperboloid surface closer to it is 50 mm
-Distance between the focal point F1 and the apex of the paraboloid = 50 mm
In addition, although the shape of the reflective surface of unit mirror 13'out-1, 13'out-2, ... arrange | positioned at the exit end 13'out of the fly-eye mirror shown in the Example of FIG. 22 is a plane, Needless to say, the shape is not limited to this, and may be a concave shape or other shapes.
[Fourth embodiment]
A fourth embodiment of the present invention will be described with reference to FIG.
This example is an example corresponding to the fourth embodiment.
Here, only differences from the first embodiment, the second embodiment, and the third embodiment will be described. The difference is that a fly-eye mirror 13 ″ is applied instead of the fly-eye mirror 13 (or 13 ′).
FIG. 23 shows unit mirrors 13 ″ in-1, 13 ″ in-2,..., 13 ″ out arranged at the input end 13 ″ in and the output end 13 ″ out of the fly-eye mirror 13 ″ of this embodiment. It is a figure explaining the shape of the reflective surface of -1,13 "out-2, ....
The shape of the reflecting surfaces of the unit mirrors 13 "in-1, 13" in-2, ..., 13 "out-1, 13" out-2, ... are as described in the fourth embodiment. It is a partial paraboloid. The dimensions of each part of the partial paraboloid are as follows.
-Diameter of the paraboloid of the part cut out as the reflecting surface = 2000 mm
-Distance between the apex of the paraboloid and the focal point F = 50 mm
[Fifth embodiment]
A fifth embodiment of the present invention will be described with reference to FIGS.
This example is an example of the fly-eye mirror 33 corresponding to the seventh embodiment and the condenser mirror 14 adapted thereto.
FIG. 24 is an optical path diagram of the fly-eye mirror 33 of the present embodiment.
Tables 16 and 17 are data of the fly-eye mirror 33. Table 17 shows the shift amount (deviation amount) of the upper unit mirror pair (33in-1, 33out-1) with respect to the center unit mirror pair (33in-2, 33out-2), and the lower part. The shift amount (deviation amount) of the unit mirror pair (33in-3, 33out-3) is shown. Here, the Z axis and the Y axis are the traveling direction of light incident on the fly-eye mirror 33 and the direction perpendicular to the Z axis, respectively.

FIG. 25 is an optical path diagram showing the configuration of the condenser mirror 14 of the present embodiment.
Table 18 shows data of the capacitor mirror 14.
In Table 18, the ray tracing direction (surface order) is opposite to the actual light traveling direction (direction from reticle surface R to fly-eye mirror 33, unit mirrors 14-3, 14-2, 14-1). In the order).
The reflecting surfaces of the unit mirrors 14-1, 14-2, and 14-3 are inclined by 14 ° with respect to the optical axis.
Further, the incident light on the reticle surface R has an angle of 6 ° with the principal ray of each image height with respect to the normal of the surface.
The formation surface of the secondary light source group on the emission end 33out side of the fly-eye mirror 33 forms an angle of 20 ° with the optical axis.

The reflecting surfaces of the unit mirrors 14-1, 14-2, and 14-3 are each formed of a toroidal aspheric surface.
Table 19 shows the toroidal aspheric coefficient of each reflecting surface. In addition, the definition formula of a toroidal aspherical surface is represented by Formula (1).

In each of the above embodiments and examples, paying attention to the fact that all the optical members that contribute to the image formation of the illumination optical system are made of reflection members that totally reflect, the illumination efficiency of the illumination optical system is remarkably improved. The fly-eye mirror (13, 13 ′, 13 ″, 33) as a reflective optical integrator that can achieve both high illumination efficiency and uniform illumination will be briefly described below. .
The fly-eye mirrors (13, 13 ′, 13 ″, 33) as reflective optical integrators in the respective embodiments and examples described above are arranged on the incident side and have a large number of unit mirrors (first reflective elements). A first array mirror (13in, 13′in, 13 ″ in, 33in) having a plurality of unit mirrors (second reflection elements) disposed on the exit side , 13′out, 13 ″ out, 33out). For this reason, the light incident on the fly-eye mirror is wavefront-divided into a large number of lights by a large number of unit mirrors of each array-shaped mirror. Since the wavefront-divided light illuminates the illumination area formed on the reticle (mask) or wafer (photosensitive substrate) in a superimposed manner, the reticle (mask) or wafer (photosensitive substrate) Chromatography (13, 13 ', 13 ", 33) is uniformly illuminated by the action of.
The first array mirrors (13in, 13′in, 13) constituting the fly-eye mirrors (13, 13 ′, 13 ″, 33) as the reflection type optical integrator in each of the above embodiments and examples. "In, 33in) and the second array of mirrors (13out, 13'out, 13" out, 33out) include a plurality of unit mirrors (first reflective element and first reflective element) having a predetermined optical power in the meridional and sagittal directions. Therefore, the light incident on the fly-eye mirror (13, 13 ′, 13 ″, 33) is divided into wavefronts, and the fly-eye mirror (13, 13 ′, 13). ”, 33), a large number of condensing points as secondary light sources are formed on the exit side or in the vicinity of the exit side. As a result, for example, the reflective projection optics shown in FIG. Since the image of the secondary light source is formed by the fly-eye mirror (13, 13 ′, 13 ″, 33) at the position of the pupil (incidence pupil), the reticle (mask) and wafer (photosensitive substrate) are uniform. Koehler illumination as illumination is achieved.
As described above, the reticle (mask) and wafer (photosensitive substrate) are more uniformly illuminated while suppressing the loss of light quantity in the fly-eye mirror due to the involvement of the total reflection fly-eye mirror in each embodiment and each example. Is done.
The incident side of the fly-eye mirror (13, 13 ′, 13 ″, 33), that is, the incident side of the first array mirror (13in, 13′in, 13 ″ in, 33in) is a reticle (mask) or wafer. When the fly-eye mirror is viewed from the incident side, the first array-shaped mirror (13 in, 13 ′ in, 13 ″ in, 33 in) is formed. The shape of a large number of unit mirrors (first reflective elements) is similar to the shape of an illumination area formed on a reticle (mask) or wafer (photosensitive substrate), and fly-eye mirrors (13, 13 ′). , 13 ″, 33), that is, the second array-like mirror (13out, 13′out, 13 ″ out, 33out) is substantially the same as the pupil (incidence pupil) of the projection optical system shown in FIG. Optically conjugate It is in the position.
Further, in the seventh embodiment shown in FIG. 16 and the fifth example shown in FIG. 24, a large number of first reflecting elements (33in-1, 33in-2,...) In the first array-like mirror 33in. .) Is incident light incident on the center of each of the first reflecting elements (33in-1, 33in-2,...) (Light at the center of the incident light or light that passes through the center of the illumination field of the reticle). On the other hand, the first reference plane P1 is inclined densely at a predetermined angle β1. Similarly, many second reflective elements (33out-1, 33out-2,...) In the second array mirror 33out are second reflective elements (33out-1, 33out-2,...). ) Are densely arranged on the second reference plane P2 inclined at a predetermined angle β2 with respect to the incident light (light at the center of the incident light or light passing through the center of the illumination field of the reticle) incident on each center. ing.
At this time, the predetermined angle β1 and the predetermined angle β2 are
0 ° <β1 ≦ 20 °, 0 ° <β2 ≦ 20 °
It is preferable to satisfy. Here, by satisfying the above conditions, total reflection is achieved without incurring light quantity loss due to the arrangement of a large number of unit mirrors (reflection elements) constituting the first array mirror 33in and the second array mirror 33out. Therefore, the fly-eye mirror 33 with extremely high reflection efficiency can be realized.
In each of the above-described embodiments and examples, the fly-eye mirror (13, 13 ′, 13 ″, 33) as a reflection type optical integrator is configured by two array-like mirrors (raster-like mirrors). In this example, the fly-eye mirrors (13, 13 ′, 13 ″, 33) can be constituted by one array-like mirror (raster-like mirror).
In the first to eighth embodiments and the first to fifth examples, a member that contributes to the imaging of the illumination optical system for efficiently guiding light to the reticle (mask) is provided. Although an example in which all of the reflection members are configured to be totally reflected is shown, a member having a small contribution to the imaging of the illumination optical system can be used as necessary. In this case, the member having a small contribution to the image formation of the illumination optical system may be a transmissive member or a reflection member that is appropriately out of total reflection conditions, and these members can be applied in the present invention. Needless to say.
Incidentally, in the exposure apparatus according to the above-described embodiment, the illumination optical system or the illumination optical apparatus illuminates the mask (reticle) (illumination process), and the transfer optical pattern formed on the mask is exposed using the projection optical system. Microdevices (semiconductor elements, imaging elements, liquid crystal display elements, thin film magnetic heads, etc.) can be manufactured by exposing the conductive substrate (exposure process). FIG. 26 is a flowchart of an example of a technique for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the above-described embodiment. The description will be given with reference.
First, in step 301 in FIG. 26, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the one lot of wafers. Thereafter, in step 303, the pattern image on the mask is sequentially exposed and transferred to each shot area on the wafer of one lot via the projection optical system using the exposure apparatus of the above-described embodiment. Thereafter, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist pattern is etched on the one lot of wafers to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each wafer. Thereafter, a device pattern such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer. According to the semiconductor device manufacturing method described above, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput.
In the exposure apparatus of the above-described embodiment, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate).
Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG.
In FIG. 27, in the pattern formation process 401, a so-called photolithography process is performed in which the exposure pattern of the above-described embodiment is used to transfer and expose a mask pattern onto a photosensitive substrate (such as a glass substrate coated with a resist). The By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate undergoes steps such as a developing step, an etching step, and a resist stripping step, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming step 402.
Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three of R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembly step 403 is executed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like.
In the cell assembly step 403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step 401 and the color filter obtained in the color filter formation step 402, and a liquid crystal panel (liquid crystal cell) is obtained. ). Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

Industrial applicability

As described above, according to the present invention, it is possible to realize an illumination optical system and an illumination device with little light loss even when EUV light is used as a light source.
In addition, according to the present invention, a high-performance projection exposure apparatus that can achieve high throughput and a good microdevice (semiconductor device, imaging device, liquid crystal display device, thin film magnetic head, etc.) by dramatically improving illumination efficiency. It is possible to realize an exposure method that can manufacture the above.
In particular, the fly-eye mirror configured to satisfy the conditions of total reflection according to the present invention can achieve both improved illumination efficiency and uniform illumination, and greatly improves the performance of the illumination optical system, illumination apparatus, and projection exposure apparatus. It becomes possible. As a result, an exposure method that can manufacture even finer microdevices with high throughput can be achieved.

Claims (32)

Arrange the light source unit that emits extreme ultraviolet light, collimator mirror, fly-eye mirror, and condenser mirror in order,
Each of the collimator mirror, the fly-eye mirror, and the condenser mirror is composed of a plurality of unit mirrors arranged so that the oblique incident angle of incident light is a total reflection angle. The illumination optical system according to claim 1,
The light source unit is
A laser plasma light source;
A collector mirror that collects extreme ultraviolet light emitted from the laser plasma light source;
An illumination optical system comprising: a partition wall for blocking scattered matter disposed in the vicinity of a condensing point of the extreme ultraviolet light by the collector mirror. The illumination optical system according to claim 1,
The light source unit is
An illumination optical system comprising a discharge plasma light source. The illumination optical system according to claim 3,
The light source unit is
A collector mirror that collects extreme ultraviolet light emitted from the discharge plasma light source;
An illumination optical system comprising: a partition wall for blocking scattered objects disposed near a condensing point of extreme ultraviolet light by the collector mirror. The illumination optical system according to claim 4, wherein
The collector mirror is
An illumination optical system comprising a plurality of unit mirrors arranged so that an oblique incident angle of incident light is a total reflection angle. In the illumination optical system according to any one of claims 1 to 5,
The collimator mirror is
An illumination optical system comprising: a plurality of skirt-shaped unit mirrors having different diameters and spread angles, and arranged around the optical axis in a state where the spread portion faces the exit side. The illumination optical system according to claim 6, wherein
The reflective surfaces of the plurality of skirt-shaped unit mirrors are:
An illumination optical system characterized by having a shape of a side surface of a cone. The illumination optical system according to claim 6, wherein
The reflecting surface of the unit mirror arranged on the outermost peripheral side of the unit mirrors is
It has a parabolic shape,
The other reflecting surfaces of the unit mirror are
An illumination optical system characterized by having a shape of a side surface of a cone. In the illumination optical system according to any one of claims 1 to 8,
Between the collimator mirror and the fly eye mirror,
An illumination optical system comprising a capillary array in which a plurality of hollow tubes are arranged in parallel. The illumination optical system according to claim 9,
An illumination optical system comprising a cooling mechanism for cooling the capillary array. In the illumination optical system according to any one of claims 1 to 10,
The fly-eye mirror is
An incident end where a plurality of unit mirrors of the same posture are arranged in parallel and an emission end where a plurality of unit mirrors of the same posture are arranged in parallel are the oblique incidence angle of incident light with respect to each unit mirror is the total reflection angle As described above, an illumination optical system characterized in that the unit mirror is arranged with a sufficient interval in the traveling direction of the reflected light. The illumination optical system according to claim 11, wherein
The reflecting surfaces of the plurality of unit mirrors arranged at the incident end are:
An illumination optical system characterized by a Walter I shape. The illumination optical system according to claim 11, wherein
The reflection surfaces of the plurality of unit mirrors arranged at the incident end and the emission end are:
An illumination optical system characterized by a paraboloid shape. The illumination optical system according to any one of claims 11 to 13,
The plurality of unit mirrors constituting the incident end are:
In order to reduce the vignetting of the reflected light between the unit mirrors, the unit mirrors are arranged at a sufficient distance in the traveling direction of the reflected light by the unit mirrors,
The plurality of unit mirrors constituting the emission end are:
An illumination optical system, wherein the illumination optical system is arranged by being shifted by a sufficient distance in the traveling direction of the reflected light by the unit mirrors so that vignetting of the reflected light between the unit mirrors is reduced. In the illumination optical system according to any one of claims 1 to 14,
The condenser mirror is
An illumination optical system comprising a plurality of unit mirrors arranged in series, and at least one reflection surface of which is a toroidal aspherical surface. In the illumination optical system according to any one of claims 1 to 15,
The extreme ultraviolet light emitted from the light source unit is extreme ultraviolet light having a wavelength of 50 nm or less,
Reflective surfaces of the unit mirrors of the collimator mirror, fly-eye mirror, and condenser mirror are made of Ru or Mo material, and are arranged in an attitude in which the oblique incident angle is 15 ° or less. system. A reflective projection optical system;
A projection exposure apparatus comprising: the illumination optical system according to any one of claims 1 to 16. An illumination step of illuminating a reticle using the illumination optical system according to any one of claims 1 to 16,
And an exposure step of exposing the reticle pattern onto a photosensitive substrate. A light source unit that supplies extreme ultraviolet light, and an illumination optical system that guides light from the light source unit to an object to be illuminated;
The illumination optical system includes a plurality of reflecting members that reflect the extreme ultraviolet light,
All of the reflecting members constituting the illumination optical system are arranged in a posture in which an incident angle of incident light is a total reflection angle. The lighting device according to claim 19.
The plurality of reflecting members include at least an arrayed mirror having a plurality of reflecting elements,
The illuminating device, wherein the plurality of reflective elements in the arrayed mirror are arranged in a posture in which an incident angle of incident light is a total reflection angle. The lighting device according to claim 20,
A number of reflective elements in the array-shaped mirror each have a predetermined optical power in the meridional direction and the sagittal direction. The lighting device according to claim 19.
The plurality of reflecting members include at least a first array-shaped mirror having a large number of first reflecting elements, and a second array-shaped mirror having a large number of second reflecting elements,
A number of first reflecting elements in the first array-shaped mirror and a number of second reflecting elements in the second array-shaped mirror are respectively arranged in an attitude in which the incident angle of incident light is a total reflection angle. A lighting device characterized by that. A light source unit that supplies extreme ultraviolet light, and an illumination optical system that guides light from the light source unit to an object to be illuminated;
The illumination optical system includes a plurality of reflecting members that reflect the extreme ultraviolet light,
The plurality of reflecting members include at least a first array-shaped mirror having a large number of first reflecting elements, and a second array-shaped mirror having a large number of second reflecting elements,
A number of first reflecting elements in the first array-shaped mirror and a number of second reflecting elements in the second array-shaped mirror are respectively arranged in an attitude in which the incident angle of incident light is a total reflection angle. A lighting device characterized by that. 24. A lighting device according to claim 22 or claim 23.
The multiple first reflective elements in the first array-shaped mirror and the multiple second reflective elements in the second array-shaped mirror have predetermined optical powers in the meridional direction and the sagittal direction. Lighting device. The lighting device according to claim 24.
The light passing through the first array mirror and the second array mirror is the second array mirror, the vicinity of the second array mirror, or the exit side of the second array mirror. A plurality of condensing points as secondary light sources are formed on the lighting device. In the illuminating device as described in any one of Claims 22-24,
At least one of the first reflective element and the second reflective element includes a rectangular plane-shaped reflective surface. In the illuminating device as described in any one of Claims 22-26,
A number of first reflective elements in the first array mirror are densely arranged on a first reference plane inclined at a predetermined angle with respect to an incident optical path incident on the first array mirror,
A number of second reflecting elements in the second array mirror are densely arranged on a second reference plane inclined at a predetermined angle with respect to an incident optical path incident on the second array mirror. A lighting device. In the illuminating device as described in any one of Claims 22-26,
The plurality of first reflecting elements in the first array-shaped mirror are arranged on a first reference plane that is inclined at a predetermined angle β1 with respect to the central light of the light incident on each of the plurality of first reflecting elements. And densely arranged,
The plurality of second reflecting elements in the second array mirror are arranged on a second reference plane that is inclined at a predetermined angle β2 with respect to the central light of the light incident on each of the plurality of first reflecting elements. And densely arranged,
The predetermined angle β1 and the predetermined angle β2 are:
0 ° <β1 ≦ 20 ° and 0 ° <β2 ≦ 20 ° are satisfied. The lighting device according to any one of claims 19 to 28,
A projection exposure system, comprising: a projection optical system that projects a reticle pattern as the illuminated object illuminated by the illumination device onto a photosensitive substrate. An illumination step of illuminating a reticle as the object to be illuminated using the illumination device according to any one of claims 19 to 28;
And an exposure step of exposing the reticle pattern onto a photosensitive substrate. Supplying extreme ultraviolet light, illuminating a reticle with the extreme ultraviolet light, and exposing a pattern of the reticle onto a photosensitive substrate,
The illuminating step includes a step of guiding the extreme ultraviolet light to an object to be illuminated using only a plurality of reflecting members arranged in a posture in which the incident angle of incident light is a total reflection angle. Supplying extreme ultraviolet light, illuminating a reticle with the extreme ultraviolet light, and exposing a pattern of the reticle onto a photosensitive substrate,
The illumination step includes a first array-like mirror having a large number of first reflecting elements arranged in a posture where the incident angle of incident light is a total reflection angle, and a posture in which the incident angle of incident light is a total reflection angle. And a step of guiding the extreme ultraviolet light to an object to be illuminated using a second array of mirrors having a number of second reflecting elements arranged in the above.

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