JP2006120985A - Illumination optical device, and exposure apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination optical device capable of stably maintaining a higher reflectance ratio and provided with a highly durable optical path bending means. <P>SOLUTION: The illumination optical device illuminates a face to be irradiated on the basis of a light flux supplied from a light source. The device is provided with a prism which is arranged in an optical path between the light source and the face to be irradiated and for bending the optical path by a prescribed angle. The prism has a first reflecting face (2b), which is for reflecting a beam entering the prism along the optical axis (AX1) of the illumination optical device inside the prism, and a second reflecting face (2c) for reflecting the beam reflected by the first reflecting face inside the prism. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination optical apparatus, an exposure apparatus, and an exposure method, and particularly to an illumination optical apparatus suitable for an exposure apparatus for manufacturing a microdevice such as a semiconductor element, an imaging element, a liquid crystal display element, and a thin film magnetic head in a lithography process. It is about.

  In a typical exposure apparatus of this type, a light beam emitted from a light source passes through a fly-eye lens (or micro fly-eye lens) as an optical integrator, and is used as a substantial surface light source composed of a number of light sources. The next light source is formed. The light beam from the secondary light source is condensed by the condenser lens and then illuminates the mask on which a predetermined pattern is formed in a superimposed manner.

  The light transmitted through the mask pattern forms an image on the wafer via the projection optical system. Thus, the mask pattern is projected and exposed (transferred) onto the wafer as the photosensitive substrate. As the circuit pattern provided on the mask is increased in density, the exposure light (illumination light) has a shorter wavelength, the projection optical system has a higher numerical aperture, and the development of a highly sensitive resist. Generally, maintaining a high throughput in an exposure apparatus is important from the viewpoint of productivity.

  In the prior art, for example, a 45-degree total reflection prism (right angle prism) is often used as an optical path bending means for bending the optical path of a light beam emitted from an ArF excimer laser light source by 90 degrees. However, in the total reflection 45-degree prism, the reflectivity tends to decrease due to adhesion of a substance to the reflection surface. In the total reflection 45 degree prism, the reflection surface is easily damaged by a photochemical reaction or the like due to incidence of a light beam having a high energy density.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an illumination optical apparatus provided with a highly durable optical path bending means capable of stably maintaining a high reflectance. . The present invention also provides an exposure apparatus capable of stably performing high-throughput exposure using an illumination optical apparatus having a highly durable optical path bending means capable of stably maintaining high reflectivity. And an exposure method.

In order to solve the above-mentioned problem, in the first embodiment of the present invention, in the illumination optical device that illuminates the illuminated surface based on the light beam supplied from the light source,
A prism disposed in the optical path between the light source and the irradiated surface for bending the optical path by a predetermined angle;
The prism includes a first reflecting surface for reflecting a light beam incident on the prism along the optical axis of the illumination optical device, and a light beam reflected by the first reflecting surface. An illumination optical device comprising a second reflecting surface for reflecting inside a prism is provided.

In the second embodiment of the present invention, in the illumination optical device that illuminates the irradiated surface based on the light flux supplied from the light source,
A prism disposed in the optical path between the light source and the irradiated surface for bending the optical path by a predetermined angle;
The prism includes an incident surface substantially tilted from a plane perpendicular to the optical axis of the illumination optical device, and an internal reflection surface for reflecting the light incident on the prism from the incident surface inside the prism. Have
The incident surface and the internal reflection surface are configured such that light incident on the incident surface along the optical axis is refracted by the incident surface and is incident on the internal reflection surface at an incident angle substantially greater than 45 degrees. The illumination optical device is characterized in that it is set as follows.

  According to a third aspect of the present invention, there is provided an exposure apparatus comprising the illumination optical apparatus according to the first or second aspect for illuminating a mask, and exposing the pattern of the mask onto a photosensitive substrate. .

  According to a fourth aspect of the present invention, the method includes an illumination step of illuminating a mask using the illumination optical apparatus of the first or second aspect, and an exposure step of exposing the pattern of the mask onto a photosensitive substrate. An exposure method is provided.

  In the illumination optical apparatus according to the typical aspect of the present invention, the prism as the optical path bending means has two internal reflection surfaces, so that the light incident on the inside of the prism from the incident surface along the incident optical axis is reflected on the reflection surface. The incident angle can be set substantially larger than 45 degrees on both reflecting surfaces. As a result, even if a light beam having a high energy density is incident, the reflecting surface is less likely to be damaged by a photochemical reaction or the like than the prior art, and the durability against light irradiation is improved. In addition, it is easier than the conventional technology to make total reflection on both reflection surfaces, and as a result, high reflectance can be stably maintained. Further, even if a substance such as dust adheres to the outer surface of the reflecting surface, the reflectance of the reflecting surface is less likely to be lower than that of the prior art, and as a result, a high reflectance can be stably maintained.

  Thus, according to the present invention, an illumination optical apparatus including a highly durable optical path bending prism (optical path bending means) that can stably maintain a high reflectance can be realized. Therefore, in the exposure apparatus and the exposure method of the present invention, high-throughput exposure can be stably performed using an illumination optical apparatus including a highly durable optical path bending prism that can stably maintain high reflectance. And thus good microdevices can be manufactured with high throughput.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. Referring to FIG. 1, the exposure apparatus of this embodiment includes an ArF excimer laser light source that supplies light having a wavelength of about 193 nm, for example, as a light source 1 for supplying exposure light (illumination light).

  The substantially parallel light beam emitted from the light source 1 is deflected by 90 degrees by the optical path bending prism 2 and then enters the beam transmission system 3 having a known configuration. The detailed configuration and operation of the optical path bending prism 2 will be described later. The light beam incident on the beam transmission system 3 is shaped into a light beam having a predetermined rectangular cross section, and then enters the micro fly's eye lens (or fly eye lens) 5 via the beam shape variable unit 4.

  The beam transmission system 3 guides the incident light beam to the beam shape variable unit 4 while converting the incident light beam into a light beam having a cross section of an appropriate size and shape, and changes the position and angle of the light beam incident on the subsequent beam shape variable unit 4. It has a function of actively correcting fluctuations. The beam shape variable unit 4 includes, for example, a diffractive optical element, a variable power optical system, and the like. It has a function of changing the size and shape of the surface light source formed on the focal plane (illumination pupil plane).

  On the other hand, the micro fly's eye lens 5 is an optical element composed of a large number of microlenses having positive refractive power arranged densely and vertically, for example, and forms a microlens group by performing an etching process on a plane-parallel plate. Consists of. Here, each micro lens constituting the micro fly's eye lens is smaller than each lens element constituting the fly eye lens.

  Further, unlike a fly-eye lens composed of lens elements isolated from each other, a micro fly-eye lens is formed integrally with a large number of micro lenses (micro refractive surfaces) without being isolated from each other. However, the micro fly's eye lens is the same wavefront division type optical integrator as the fly's eye lens in that the lens elements are arranged vertically and horizontally. Instead of the micro fly's eye lens 5, an optical integrator such as a diffractive optical element or a prismatic rod type integrator can be used.

  The light beam incident on the micro fly's eye lens 5 is two-dimensionally divided by a large number of minute lenses, and a light source is formed on the rear focal plane of each minute lens on which the light beam is incident. Thus, a substantial surface light source (hereinafter referred to as “secondary light source”) composed of a large number of light sources is formed on the rear focal plane of the micro fly's eye lens 5. The light beam from the secondary light source formed on the rear focal plane of the micro fly's eye lens 5 passes through the condenser optical system 6 and illuminates the mask blind 7 in a superimposed manner.

  It is also possible to limit the luminous flux by arranging an aperture stop at the rear side or the front side of the micro fly's eye lens 5. Thus, a rectangular illumination field corresponding to the shape and focal length of each microlens constituting the micro fly's eye lens 5 is formed on the mask blind 7 as an illumination field stop. The light beam that has passed through the rectangular opening (light transmitting portion) of the mask blind 7 is subjected to the light condensing action of the imaging optical system 8 and then superimposed on the mask (reticle) M on which a predetermined pattern is formed. Illuminate.

  That is, the imaging optical system 8 forms an image of the rectangular opening of the mask blind 7 on the mask M. The light beam that has passed through the pattern of the mask M forms an image of the mask pattern on the wafer W, which is a photosensitive substrate, via the projection optical system PL. In this way, the pattern of the mask M is formed in each exposure region of the wafer W by performing batch exposure or scan exposure while two-dimensionally driving and controlling the wafer W in a plane orthogonal to the optical axis AX of the projection optical system PL. Sequential exposure is performed.

  As described above, in the illumination optical apparatus (1-8) that illuminates the mask M as the irradiated surface based on the light flux supplied from the light source 1, the beam transmission system 3, the beam shape variable unit 4, and the micro fly's eye The lens 5 constitutes an averaging means for averaging the light intensity distribution of the light flux from the light source 1. The optical path bending prism 2 is disposed in the optical path between the light source 1 and the averaging means 10.

  FIG. 2 is a diagram illustrating the configuration and operation of the optical path bending prism in the present embodiment. Referring to FIG. 2, the optical path bending prism 2 of the present embodiment includes an incident surface 2a perpendicular to the incident optical axis AX1, and a light beam incident on the prism from the incident surface 2a along the incident optical axis AX1. A first reflecting surface 2b for reflecting inside, a second reflecting surface 2c for reflecting the light beam reflected by the first reflecting surface 2b inside the prism, and an exit surface 2d perpendicular to the exit optical axis AX2. And have. The incident optical axis AX1 and the outgoing optical axis AX2 are set to form 90 degrees. The optical path bending prism 2 is formed of, for example, fluorite (calcium fluoride) as an optical material having a required transmittance with respect to use light (ArF excimer laser light).

  In the optical path bending prism 2 of the present embodiment, the light beam perpendicularly incident on the incident surface 2a along the incident optical axis AX1 travels straight inside the prism without being refracted by the incident surface 2a, and is substantially more than 45 degrees. Incidently incident on the first reflecting surface 2b. The light beam incident on the first reflecting surface 2b is reflected by the first reflecting surface 2b, propagates through the prism, and then enters the second reflecting surface 2c at an incident angle substantially larger than 45 degrees. The light beam incident on the second reflecting surface 2c is reflected by the second reflecting surface 2c, propagates through the prism, and then exits from the exit surface 2d along the exit optical axis AX2 without being refracted by the exit surface 2d. Is done. Thus, the optical path bending prism 2 has a function of bending the optical path by an angle formed by the incident optical axis AX1 and the outgoing optical axis AX2, that is, 90 degrees.

  Incidentally, the total reflection 45 degree prism (right angle prism) used as the optical path bending means in the prior art also has a function of bending the optical path by 90 degrees, like the optical path bending prism 2 of the present embodiment. However, the total reflection 45 degree prism has only one internal reflection surface, whereas the optical path bending prism 2 has two internal reflection surfaces (2b, 2c). Therefore, the incident angle of the light beam incident from the incident surface into the prism along the incident optical axis is 45 degrees in the total reflection 45 degree prism, but in the optical path bending prism 2, both reflection surfaces (2b, 2b, In 2c), it can be set substantially larger than 45 degrees.

  As described above, in the optical path bending prism 2 of the present embodiment, the incident angle of the light beam with respect to the reflecting surfaces (2b, 2c) is larger than that in the conventional technique. The cross-sectional area of the light beam on the surfaces (2b, 2c) is larger than that in the conventional technique. As a result, in the optical path bending prism 2 of the present embodiment, if the energy per unit area of the light beam incident on the prism is the same, the energy per unit area of the light beam incident on the reflecting surface (2b, 2c) is the prior art. Therefore, even if a light beam having a high energy density is incident on the prism, the reflecting surfaces (2b, 2c) are less likely to be damaged by a photochemical reaction or the like than in the prior art, and the durability against light irradiation is improved.

  Further, in the optical path bending prism 2 of the present embodiment, since the incident angle of the light beam with respect to the reflecting surfaces (2b, 2c) is larger than that in the prior art, the prism is formed using an optical material having a relatively low refractive index. Also, it becomes easy to satisfy the total reflection condition on the reflecting surfaces (2b, 2c). As a result, in the optical path bending prism 2 of the present embodiment, all effective rays incident on the first reflecting surface 2b and the second reflecting surface 2c are totally reflected by the first reflecting surface 2b and the second reflecting surface 2c, respectively. Such a configuration is easier than in the prior art, and as a result, it is possible to avoid a light loss in the first reflecting surface 2b and the second reflecting surface 2c and stably maintain a high reflectance. In other words, in the optical path bending prism 2 of the present embodiment, the range of selection of usable optical materials is increased as compared with the prior art.

  Further, in the optical path bending prism 2 of the present embodiment, the incident angle of the light beam with respect to the reflecting surface is larger than that in the conventional technique, so that even if a substance such as dust adheres to the outer surface of the reflecting surface (2b, 2c). The reflectivity of the reflective surfaces (2b, 2c) is less likely to be lower than that of the prior art, and as a result, high reflectivity can be stably maintained. This is because the maximum refractive index of the adhering substance that allows all effective rays incident on the first reflecting surface 2b and the second reflecting surface 2c to be totally reflected by the first reflecting surface 2b and the second reflecting surface 2c, respectively. This is because the value is higher than that of the prior art.

  Thus, in the present embodiment, it is possible to realize the illumination optical devices (1 to 8) including the highly durable optical path bending prism 2 that can stably maintain a high reflectance. Therefore, in the exposure apparatus of this embodiment, high-throughput exposure is performed using the illumination optical apparatus (1 to 8) including the highly durable optical path bending prism 2 that can stably maintain high reflectance. Can be performed stably.

  In the above-described embodiment, the incident surface 2a is set perpendicular to the incident optical axis AX1, and the exit surface 2d is set perpendicular to the exit optical axis AX2. However, the present invention is not limited to this, and the incident surface 2a can be substantially tilted from the surface perpendicular to the incident optical axis AX1, and the exit surface 2d can be substantially tilted from the surface perpendicular to the emergent optical axis AX2.

  In the above-described embodiment, the example in which the optical path bending prism has two internal reflection surfaces has been described. However, the present invention is not limited to this. For example, a configuration having only one internal reflection surface as shown in FIG. Is also possible. FIG. 3 is a diagram for explaining the configuration and operation of an optical path bending prism according to a modification of the present embodiment. The optical path bending prism 20 according to the modification of FIG. 3 includes an incident surface 20a substantially tilted from a plane perpendicular to the incident optical axis AX1, and light rays that have entered the prism from the incident surface 20a along the incident optical axis AX1. It has an internal reflection surface 20b for reflecting inside the prism, and an exit surface 20c substantially tilted from a plane perpendicular to the exit optical axis AX2. Further, in the modification of FIG. 3, as in the embodiment of FIG. 2, the incident optical axis AX1 and the outgoing optical axis AX2 are set to form 90 degrees, and the optical path bending prism 20 is formed of, for example, fluorite. Yes.

  In the optical path bending prism 20 according to the modification, the light beam incident on the incident surface 20a along the incident optical axis AX1 is refracted by the incident surface 2a and travels straight inside the prism, and is substantially more than 45 degrees. The light enters the internal reflection surface 20b at a large incident angle. The light beam reflected by the internal reflection surface 20b is propagated through the prism, is refracted by the exit surface 20c, and exits from the exit surface 20c along the exit optical axis AX2. Thus, the optical path bending prism 20 according to the modification also has a function of bending the optical path by an angle formed by the incident optical axis AX1 and the outgoing optical axis AX2, that is, 90 degrees.

  In the optical path bending prism 20 according to the modified example, the incident surface 20a is such that the light beam incident on the incident surface 20a along the incident optical axis AX1 enters the internal reflection surface 20b at an incident angle substantially larger than 45 degrees. Is set to be substantially tilted from a plane perpendicular to the incident optical axis AX1. As described above, also in the optical path bending prism 20 according to the modified example, since the incident angle of the light beam with respect to the reflecting surface 20b is larger than that in the prior art as in the embodiment of FIG. 2, a light beam having a high energy density is incident on the prism. Even so, the reflecting surface 20b is less susceptible to damage due to photochemical reaction or the like than the prior art, and as a result, durability against light irradiation is improved.

  Further, in the optical path bending prism 20 according to the modified example, as in the embodiment of FIG. 2, it is configured that all effective rays incident on the internal reflection surface 20b are totally reflected by the internal reflection surface 20b. As a result, light loss in the internal reflection surface 20b can be avoided and high reflectivity can be stably maintained. Further, in the optical path bending prism 20 according to the modified example, as in the embodiment of FIG. 2, even if a substance such as dust adheres to the outer surface of the internal reflection surface 20b, the reflectance of the reflection surface 20b is higher than that of the related art. It becomes difficult to decrease, and as a result, high reflectance can be stably maintained.

  In the above-described modification, the exit surface 20c is set so as to be substantially inclined from the surface perpendicular to the exit optical axis AX2. However, the present invention is not limited to this, and the exit surface 20c can be set substantially perpendicular to the exit optical axis AX2.

  In the above-described embodiment and modification, the incident optical axis AX1 and the outgoing optical axis AX2 are set to form 90 degrees, and the optical path bending prism (2, 20) is configured to bend the optical path by 90 degrees. is doing. However, the present invention is not limited to this, and the optical path bending prism (2, 20) may be configured to bend the optical path by a predetermined angle substantially different from 90 degrees. Moreover, in the above-mentioned embodiment and modification, the part where an effective light beam does not pass can also be cut off in the optical path bending prism (2, 20).

  In the above-described embodiment and modification, the optical path bending prism (2, 2) is included in the optical path between the light source 1 and the averaging means 10 (3-5) for averaging the light intensity distribution of the light flux from the light source 1. 20). However, the present invention is not limited to this, and the optical path bending prism (2, 20) may be disposed in the optical path between the light source 1 and the mask M that is the irradiated surface. However, when the optical path bending prism (2, 20) is disposed in the optical path between the light source 1 and the averaging means 10, the energy density of the incident light beam becomes relatively high. The effect of 20) can be used effectively.

  By the way, in the above-mentioned embodiment and modification, the internal reflection surface (2b, 2c; 20b) is incident at an incident angle where the light beam incident on the incident surface (2a, 20a) along the incident optical axis AX1 is substantially larger than 45 degrees. ). Specifically, from the viewpoint of durability of the reflecting surface (2b, 2c; 20b) with respect to light irradiation, an incident angle at which a light beam incident on the incident surface (2a, 20a) along the incident optical axis AX1 is, for example, 60 degrees or more. It is preferable that the light beam is incident on the internal reflection surfaces (2b, 2c; 20b).

  Moreover, in the above-mentioned embodiment and modification, the protective film for preventing adhesion of harmful substances (dust etc.) to the reflective surface (2b, 2c; 20b) is provided on the outer surface of the reflective surface (2b, 2c; 20b). It is preferable to form. With this configuration, it is possible to avoid a decrease in reflectivity due to the adhesion of a substance to the reflecting surface (2b, 2c; 20b). In addition, in order to avoid the optical loss in the reflecting surface (2b, 2c; 20b) and stably maintain a high reflectance, the required refractive index satisfying the total reflection condition in the reflecting surface (2b, 2c; 20b) is satisfied. It is preferable to form a protective film with a substance having

  Further, in the above-described embodiment and modification, in order to avoid light loss at the entrance surface (2a, 20a) and the exit surface (2d, 20c), the entrance surface (2a, 20a) and the exit surface (2d, 20c). It is preferable to form an antireflection coating on the surface. Moreover, in the above-described embodiment and modification, in order to prevent adhesion of harmful substances (dust etc.) to the reflective surface (2b, 2c; 20b), the space in contact with the reflective surface (2b, 2c; 20b) is sealed. Is preferred.

  Moreover, in the above-mentioned embodiment and modification, in order to prevent adhesion of harmful substances (dust etc.) to the reflective surface (2b, 2c; 20b), the space in contact with the reflective surface (2b, 2c; 20b) is an inert gas. It is preferable that the gas is replaced at any time by a clean gas (for example, nitrogen gas) or clean gas such as clean dry air (for example, by circulation of gas). Furthermore, in order to prevent harmful substances (dust etc.) from adhering to the reflecting surface (2b, 2c; 20b), the air pressure in the space in contact with the reflecting surface (2b, 2c; 20b) is set to be substantially smaller than the atmospheric pressure. It is preferable.

  In the exposure apparatus according to the above-described embodiment, the illumination optical device illuminates the mask (reticle) (illumination process), and the projection optical system is used to expose the transfer pattern formed on the mask onto the photosensitive substrate (exposure). Step), a micro device (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Refer to the flowchart of FIG. 4 for an example of a method 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. To explain.

  First, in step 301 of FIG. 4, 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 image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of one lot through 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. 5, in the pattern forming process 401, a so-called photolithography process is performed in which the mask pattern is transferred and exposed to a photosensitive substrate (such as a glass substrate coated with a resist) using the exposure apparatus of the above-described embodiment. . 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.

In the above-described embodiment, an ArF excimer laser light source is used as the light source. However, the present invention is not limited to this, and the present invention is not limited to this, for example, other appropriate light sources such as a KrF excimer laser light source and an F ₂ laser light source. The invention can also be applied.

  In the above-described embodiment, the present invention has been described by taking an exposure apparatus including an illumination optical apparatus as an example. However, a general illumination optical apparatus for illuminating a surface to be irradiated other than a mask, such as a laser processing apparatus or a laser. It is clear that the present invention can be applied to an annealing apparatus or the like.

  In the above-described embodiment, a so-called immersion method is applied in which the optical path between the projection optical system and the photosensitive substrate is filled with a medium (typically liquid) having a refractive index larger than 1.1. You may do it. In this case, as a method of filling the liquid in the optical path between the projection optical system and the photosensitive substrate, a method of locally filling the liquid as disclosed in International Publication No. WO99 / 49504, A method of moving a stage holding a substrate to be exposed as disclosed in Japanese Patent Application Laid-Open No. 6-124873 in a liquid bath, or a predetermined depth on a stage as disclosed in Japanese Patent Application Laid-Open No. 10-303114. A technique of forming a liquid tank and holding the substrate in the liquid tank can be employed.

As the liquid, it is preferable to use a liquid that is transmissive to exposure light and has a refractive index as high as possible, and is stable with respect to a photoresist applied to the projection optical system and the substrate surface, for example, KrF excimer laser light. When ArF excimer laser light is used as exposure light, pure water or deionized water can be used as the liquid. When F ₂ laser light is used as exposure light, a fluorine-based liquid such as fluorine oil or perfluorinated polyether (PFPE) that can transmit the F ₂ laser light may be used as the liquid.

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a figure explaining the structure and effect | action of an optical path bending prism in this embodiment. It is a figure explaining the structure and effect | action of the optical path bending prism concerning the modification of this embodiment. It is a flowchart of the method at the time of obtaining the semiconductor device as a microdevice. It is a flowchart of the method at the time of obtaining the liquid crystal display element as a microdevice.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2, 20 Optical path bending prism 2a, 20a Incident surface 2b, 2c;
6 Condenser optics 7 Mask blind (illumination field stop)
8 Imaging optical system 10 Averaging means M Mask PL Projection optical system W Wafer

Claims (17)

In the illumination optical device that illuminates the illuminated surface based on the light flux supplied from the light source,
A prism disposed in the optical path between the light source and the irradiated surface for bending the optical path by a predetermined angle;
The prism includes a first reflecting surface for reflecting a light beam incident on the prism along the optical axis of the illumination optical device, and a light beam reflected by the first reflecting surface. An illumination optical apparatus, comprising: a second reflecting surface for reflecting inside the prism. The first reflecting surface and the second reflecting surface are respectively incident on the first reflecting surface and the second reflecting surface at an incident angle at which a light beam incident on the prism along the optical axis is substantially larger than 45 degrees. The illumination optical apparatus according to claim 1, wherein the illumination optical apparatus is set to be incident. 2. The system according to claim 1, wherein all effective rays incident on the first reflecting surface and the second reflecting surface are totally reflected by the first reflecting surface and the second reflecting surface, respectively. Or the illumination optical apparatus of 2. In the illumination optical device that illuminates the illuminated surface based on the light flux supplied from the light source,
A prism disposed in the optical path between the light source and the irradiated surface for bending the optical path by a predetermined angle;
The prism includes an incident surface substantially tilted from a plane perpendicular to the optical axis of the illumination optical device, and an internal reflection surface for reflecting the light incident on the prism from the incident surface inside the prism. Have
The incident surface and the internal reflection surface are configured such that light incident on the incident surface along the optical axis is refracted by the incident surface and is incident on the internal reflection surface at an incident angle substantially greater than 45 degrees. An illumination optical apparatus, characterized in that The prism has an exit surface substantially inclined from a plane perpendicular to the optical axis;
The exit surface is set such that a light beam incident on the entrance surface along the optical axis is refracted by the exit surface and guided to the outside of the prism along the optical axis. The illumination optical apparatus according to claim 4. 6. The illumination optical device according to claim 4, wherein all effective rays incident on the internal reflection surface are totally reflected by the internal reflection surface. The illumination optical apparatus according to claim 1, wherein the predetermined angle is 90 degrees. Further comprising an averaging means for averaging the light intensity distribution of the luminous flux from the light source,
The illumination optical apparatus according to claim 1, wherein the prism is disposed in an optical path between the light source and the averaging unit. The illumination optical apparatus according to claim 1, wherein the light source includes a laser light source. A protective film is formed on at least one of the first reflecting surface, the second reflecting surface, and the internal reflecting surface to prevent adhesion of harmful substances to the reflecting surface. The illumination optical apparatus according to any one of claims 1 to 9. The illumination optical apparatus according to claim 10, wherein the protective film is made of a material having a required refractive index that satisfies a total reflection condition on the reflection surface. 12. The space in contact with at least one of the first reflection surface, the second reflection surface, and the internal reflection surface is hermetically sealed. Illumination optical device. The space in contact with at least one of the first reflection surface, the second reflection surface, and the internal reflection surface is configured to be replaced with clean gas as needed. The illumination optical apparatus according to any one of 1 to 12. The illumination optical apparatus according to claim 13, wherein the gas includes an inert gas or clean dry air. The illumination optical apparatus according to any one of claims 12 to 14, wherein a pressure of the space is set to be substantially smaller than an atmospheric pressure. An exposure apparatus comprising the illumination optical apparatus according to any one of claims 1 to 15 for illuminating a mask and exposing a pattern of the mask onto a photosensitive substrate. An exposure process comprising: an illumination process for illuminating a mask using the illumination optical apparatus according to claim 1; and an exposure process for exposing a pattern of the mask onto a photosensitive substrate. Method.

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