JP2007227637A - Immersion aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an immersion aligner which exhibits a high resolution capability and is based on the principle of dual beam interference. <P>SOLUTION: The aligner is provided with an interference optical system which fractionates light from a light source into several beams of light, allows the several beams of light to interfere with one another for forming interference patterns on a photosensitive substrate, and exposes the photosensitive substrate to light through a liquid between the interference optical system and the photosensitive substrate. In this case, the interference optical system is so constructed that it has a prism which comes into contact with the liquid and the angle between the normal surface of the output surface of the prism from which the beams of light are outputted and the normal surface of the surface of the photosensitive substrate is larger than 0°. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to an immersion exposure apparatus, and more particularly to an immersion exposure apparatus that performs two-beam interference exposure that exposes a photosensitive substrate by forming an interference pattern on the photosensitive substrate by interfering a plurality of light beams.

  2. Description of the Related Art In the manufacture of semiconductor devices, liquid crystal display devices, and the like, a projection exposure apparatus that exposes a circuit pattern drawn on a reticle (photomask) onto a photosensitive substrate with a projection optical system has been conventionally used. In recent years, it has been desired to increase the resolution of an exposure apparatus in order to cope with higher integration of device patterns. Immersion exposure is attracting attention as a means for meeting the demand for higher resolution. In immersion exposure, the numerical aperture (NA) of the projection optical system is further increased by interposing a liquid layer between the final surface of the projection optical system and the photosensitive substrate. The NA of the projection optical system is NA = n · sin θ, where n is the refractive index of the medium and θ is the aperture angle. Therefore, by satisfying the medium having a refractive index higher than the refractive index of air (n> 1), NA is satisfied. Can be increased to n. As a result, the resolution R (R = k1 (λ / NA)) of the exposure apparatus expressed by the process constant k1 and the wavelength λ of the light source is to be reduced.

  On the other hand, an exposure method based on the principle of two-beam interference has been proposed as one of exposure methods for forming a fine pattern with a simple configuration. In the two-beam interference exposure, a coherent light beam is divided into two light beams by a half mirror and the divided two light beams are superimposed on a photosensitive substrate at a desired angle to form an interference pattern (interference fringes). An exposure method for exposing a photosensitive substrate. In this two-beam interference exposure, the apparatus configuration is simpler than the projection exposure method in which a reticle pattern is projected onto a photosensitive substrate by a projection optical system and exposed, so the apparatus cost is low, and periodic fine patterns are easily formed. There is a feature that it is possible.

As an exposure method for easily forming a fine pattern, an exposure method combining liquid immersion exposure and two-beam interference exposure has been proposed (see, for example, Patent Document 1).
JP 2005-129894 A

The resolution R in the two-beam interference exposure is expressed by the following equation (1).
R = λ / 4NA (1)
Here, the resolution R indicates the width of each line and space pattern, that is, the width of each of the bright and dark portions of the interference fringes. In the case of immersion exposure, the numerical aperture NA is expressed by the following equation (2), where n is the refractive index of the liquid and θ is the incident angle of the light beam with respect to the image plane.
NA = n · sin θ (2)
Here, in the conventional configuration disclosed in Patent Document 1, the final surface of the interference prism that faces through the liquid and the wafer surface coated with the photosensitive material are parallel to each other. Therefore, at the boundary surface between the interference prism and the liquid film and the boundary surface between the liquid film and the photosensitive material, the following relationship (3) is established according to Snell's law. However, the refractive indexes of the interference prism, the liquid, and the photosensitive material are n1, n2, and n3, the incident angle of the luminous flux with respect to the boundary surface between the interference prism and the liquid film, the incident angle with respect to the boundary surface between the liquid film and the photosensitive material, The emission angles with respect to the boundary surface with the photosensitive material are θ1, θ2, and θ3.
NA = n1 · sin θ1 = n2 · sin θ2 = n3 · sin θ3 (3)
Therefore, the maximum value of NA is limited by the medium having the smallest refractive index among the interference prism, the liquid film, and the photosensitive material. That is, the theoretical limit value of NA is the minimum value among n1, n2, and n3.

  That is, when the final surface of the interference prism is a plane, even if a liquid is interposed between the photosensitive substrate and the interference prism, if the refractive index of the interference prism is lower than the refractive index of the liquid, the NA theoretical limit will interfere. It is limited by the refractive index of the prism. Therefore, there is a problem that the refractive index characteristic of the liquid cannot be utilized to the maximum with respect to the resolution performance of the exposure apparatus.

  An exposure apparatus according to one aspect of the present invention includes an interference optical system that divides light from a light source into a plurality of light beams and interferes the plurality of light beams to form an interference pattern on a photosensitive substrate. In the exposure apparatus that exposes the photosensitive substrate through the liquid between the photosensitive substrate and the photosensitive substrate, the interference optical system includes a prism that contacts the liquid, and an emission surface (transmission surface) from which the luminous flux of the prism is emitted. ) And the surface normal of the surface of the photosensitive substrate is larger than 0 degree.

  Further objects and other features of the present invention will be made clear by the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, a periodic fine pattern can be formed with a simple configuration. Especially in two-beam interference exposure, even if the refractive index of the interference prism is lower than the refractive index of the liquid, the interference pattern can be miniaturized without being limited by the refractive index of the interference prism, and exposure with high resolution performance. An apparatus can be provided.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view of the essential part of an exposure apparatus according to Embodiment 1 of the present invention. The configuration of the exposure apparatus according to the present embodiment will be described with reference to FIG.

  In FIG. 1, reference numeral 101 denotes an exposure light source such as a mercury lamp, a semiconductor laser, a solid-state laser, a gas laser, or an excimer laser. Reference numeral 102 denotes a shaping optical system that includes a plurality of optical elements and shapes light emitted from the light source 101 into light having a desired cross-sectional shape. An interference optical system 103 includes at least one light beam splitting element and a plurality of mirrors and prisms. A wafer 106 is coated with a photosensitive material as a photosensitive substrate, and is held on a wafer stage 107. Wafer stage 107 is relative to wafer 106 in a two-dimensional direction (x-axis and y-axis direction), a vertical direction (z-axis direction), and a rotation direction (θx, θy, and θz directions) with respect to each axis. ).

  In this embodiment, a liquid immersion method is used. Therefore, the liquid supply port 112 and the liquid recovery port 113 are arranged around the final surface of the interference optical system 103, and the liquid film 105 is formed by supplying liquid between the final surface of the interference optical system 103 and the wafer 106. The liquid supply device 108 controls the amount of liquid supplied between the final surface of the interference optical system 103 and the wafer 106. The liquid supply device 108 and the liquid supply port 112 are connected by a supply pipe 110. The liquid recovery device 109 controls the amount of liquid recovered from between the final surface of the interference optical system 103 and the wafer 106. The liquid recovery device 109 and the liquid recovery port 113 are connected by a recovery pipe 111.

  The light beam emitted from the light source 101 is shaped into a light beam having a desired cross-sectional shape by the shaping optical system 102 and enters the interference optical system 103 via the mirror 104. The light beam incident on the interference optical system 103 is split into two light beams by the light beam splitting element. Then, the split two light beams are incident on the liquid film 105 filled between the final surface of the interference optical system 103 and the wafer 106 via a plurality of mirrors and prisms constituting the interference optical system 103. On the surface of the wafer 106, the two light beams are superimposed at a desired angle to form an interference fringe. The light intensity distribution of the interference fringes is obtained by exposing and exposing the photosensitive substrate with the light intensity distribution of the interference fringes. A corresponding periodic fine pattern is formed on the photosensitive substrate.

  2 and 3 are cross-sectional views of the interference optical system 103 in FIG. The configuration and effect of the interference optical system according to the present embodiment will be described with reference to FIG. In the following description, parts common to those in the figure will be denoted by the same reference numerals, and detailed description thereof will be omitted, and parts different from those in the figure will be mainly described.

  FIG. 2 is a cross-sectional view of the interference optical system 103 of FIG. In FIG. 2, reference numeral 201 denotes a light beam emitted from the shaping optical system 102 in FIG. 1 and incident on the interference optical system 103 via the mirror 104. The arrow in the figure indicates the traveling direction of the light beam. A light beam 201 is incident on a light beam splitting element 203 through an aperture 202 having an opening having a desired shape, and is split into two light beams by the light beam splitting element 203. The two light beams divided by the light beam splitting element 203 are incident on the light beam control unit 205 via the mirror 204 and the like, and each light beam is controlled to a desired light amount and polarization state, and then incident on the interference prism 206. . Here, an antireflection film 207 is preferably added to the incident surface. The interference prism 206 is made of a material having high transmission characteristics and high refractive index characteristics with respect to the wavelength of the light source, such as quartz glass. The two light beams incident on the interference prism 206 are reflected (totally reflected) on the reflection surface 208 in the interference prism 206, pass through the transmission surface (outgoing surface) 209, and between the final surface of the interference prism 206 and the wafer 106. It enters the filled liquid film 105. The two light beams incident on the liquid film 105 are refracted by the liquid film 105 and are incident on the wafer 106 coated with a photosensitive material as a photosensitive substrate at a desired angle. The two light fluxes incident at a desired angle are superimposed on the surface of the wafer 106 to form interference fringes. The light intensity distribution of the interference fringes is obtained by exposing and exposing the photosensitive substrate with the light intensity distribution of the interference fringes. A periodic fine pattern corresponding to the above is formed on the photosensitive substrate.

  In FIG. 2, an example in which there is one each of the light beam splitting element, the mirror, and the interference prism constituting the interference optical system 103 is described, but a plurality of each may be configured. In FIG. 2, the light beam control unit 205 is disposed in the optical paths of both light beams divided by the light beam splitting element 203, but may be disposed only in one of the light paths.

  FIG. 3 is an enlarged view of the right side portion of the interference prism 206 of FIG. In FIG. 3, reference numeral 301 denotes a light beam that is controlled to have a desired light amount and a polarization state by the light beam control unit 205 in FIG. 2 and is incident on the interference prism 206. The arrows in the figure indicate the traveling direction. The surface normal on the transmission surface 209 of the light beam 301 in the interference prism 206 is Lp, and the surface normal on the surface of the wafer 106 is Lw. Further, the incident angle of the light beam 301 with respect to the boundary surface (transmission surface 209) between the interference prism 206 and the liquid film 105 is θ1, and the refraction angle is θ2. Further, the incident angle of the light beam 301 with respect to the wafer 106 surface is θIN. Further, the refractive index of the interference prism 206 is n1, the refractive index of the liquid film 105 is n2, the refractive index of the photosensitive material applied on the wafer 106 is n3, and the refractive angle θ3 of the light beam inside the photosensitive material.

In the interference optical system 103 according to the exposure apparatus of the present embodiment, the angle formed by the surface normal Lp of the final surface of the interference prism 206 and the surface normal Lw of the wafer 106 surface (exposure surface) is larger than 0 degrees. It is characterized by being set to. In other words, the final surface of the interference prism 206 and the surface of the wafer 106 facing through the liquid film 105 are set non-parallel. Here, when the angle formed by the surface normals Lp and Lw is θp, the following relationship (4) is established.
θIN = θ2 + θp (4)
Therefore, according to the configuration of FIG. 3, even when the refractive index n1 of the interference prism 206 is smaller than the refractive index n2 of the liquid film 105, the angle formed by the surface normals Lp and Lw is θp (θp> 0). The final surface of the prism 206 and the surface of the wafer 106 are set non-parallel. With this setting, a plurality of light beams can be incident on the wafer 106 at a larger angle than in the conventional configuration (θp = 0), and the interference pattern formed on the photosensitive substrate can be increased. Resolution can be achieved. The resolution R of the exposure apparatus according to the present embodiment is expressed by the following equation (5).
R = λ / 4 (n2 · sin θIN) = λ / 4 (n2 · sin (θ2 + θp)) (5)
In the exposure apparatus of this embodiment, the interference prism 206 is detachably held, and is designed to form a desired interference fringe pitch P (a width obtained by combining the bright and dark portions of the interference fringes). It is possible to control the pitch of interference fringes by exchanging with an interference prism.

In the exposure apparatus of the present embodiment, the pitch P of the interference fringes can be controlled by controlling the rotation of the wafer stage 107 in the θx direction and relatively changing the incident angles of the two light beams with respect to the photosensitive substrate. It is. Here, when the rotation angle in the θx direction is θw, the angle formed by the two light beams in the liquid film 105 is 2 · θIN, and the refractive index of the liquid film 105 is n2, the two light beams and the surface normal Lw are formed. The angles are expressed as θIN + θw and θIN−θw, respectively. Further, the pitch P of the interference fringes is expressed by the following equation (6).
P = λ / 2 (n2 · sin θIN · cos θw) (6)
In the exposure apparatus of the present embodiment, the incident direction of the two light beams on the wafer may be changed by controlling the rotation of the wafer stage 107 in the θz direction. For example, it is also possible to form a periodic hole pattern by rotating the wafer stage 107 by 90 ° in the θz direction and double-exposing periodic fine patterns orthogonal to each other on the photosensitive substrate.

  FIG. 4 is a cross-sectional view of the light flux control unit 205 of FIG. The configuration and effects of the light beam control unit 205 according to the present embodiment will be described with reference to FIG. In the following description, parts common to those in the figure will be denoted by the same reference numerals, and detailed description thereof will be omitted, and parts different from those in the figure will be mainly described.

  In FIG. 4, reference numeral 401 denotes a light beam that is split by the light beam splitting element 203 in FIG. 2 and is incident on the light beam control unit 205. The arrows in the figure indicate the traveling direction. Reference numeral 402 denotes a light amount control means for controlling the light amount of the light beam 401. It is desirable to variably control (reduce) the light amount of the light beam 401. For example, an optical attenuator, ND filter, liquid crystal, acousto-optic modulator, etc. Use it. The light beam controlled to have a desired light amount by the light amount control unit 402 is incident on the interference optical system 206. In addition, the light beam control unit 205 includes a light detector 404 for detecting the light amount of the light beam 401. A light beam branched by a beam splitter 403 disposed so as to be detachable with respect to the optical path of the light beam 401 is received by a photodetector 404, and the light amount of the light beam 401 controlled by the light amount control means 402 is detected. Since the beam splitter 403 is arranged to be detachable from the optical path, the beam splitter 403 can be removed from the optical path during exposure. Reference numeral 405 denotes polarization control means for controlling the polarization state of the light beam 401, and includes a plurality of polarization elements for variably controlling the polarization state of the light beam 401. For example, in the case where the light 401 incident on the polarization control means 405 is linearly polarized light, it may be constituted by a phase difference plate (λ / 4 plate) 406 and a linearly polarizing plate 407 that transmits specific polarized light. Each polarization element is held by a holder having a rotation control mechanism, and the light beam 401 is controlled to a desired polarization state by controlling the rotation of each polarization element with respect to the optical axis of the light beam 401. In addition, the polarization elements (for example, the phase difference plate 406 and the linearly polarizing plate 407) constituting the polarization control means 405 are arranged to be detachable with respect to the optical path of the light beam 401, and the insertion / removal control is performed in the optical path as necessary. Is done. In addition, a polarizing element (for example, a linear polarizing plate 408) having a rotation control mechanism may be detachably disposed in the optical path between the beam splitter 403 and the photodetector 404. By arranging the linearly polarizing plate 408, the light beam controlled by the polarization control means 405 is received by the photodetector 404 via the beam splitter 403 and the linearly polarizing plate 408, thereby detecting the polarization state of the light beam 401. It is also possible to do.

  FIG. 5 is a schematic view of a main part to which a control device 501 for controlling the exposure apparatus of the present embodiment is added. The configuration of the control device according to this embodiment will be described with reference to FIG. In the following description, parts common to those in the figure will be denoted by the same reference numerals, and detailed description thereof will be omitted, and parts different from those in the figure will be mainly described.

  In FIG. 5, reference numeral 501 denotes a control device that controls the exposure apparatus of the present embodiment. The control device 501 includes a light source control unit 502 that controls the light source 101, an interferometer control unit 503 that controls the interference optical system 103, a liquid control unit 504 that controls the liquid supply device 108 and the liquid recovery device 109, and a wafer stage 107. A stage control unit 505 for controlling is provided.

  The light source control unit 502 performs feedback control of the light source 101 by transmitting and receiving control signals from the respective control units. In particular, the exposure amount for the photosensitive substrate is controlled.

  The interferometer control unit 503 transmits and receives control signals from the respective control units, and performs feedback control of the interference optical system 103. In particular, the light beam control unit 205 is controlled based on a control signal from the light source control unit 502, the light amount and polarization state of the light beam irradiated on the wafer surface are controlled, and the optical contrast is controlled.

  The liquid control unit 504 transmits and receives control signals from the respective control units, and performs feedback control of the liquid supply device 108 and the liquid recovery device 109. In particular, the liquid supply amount and the recovery amount are controlled in accordance with the moving direction and speed of the wafer 106.

  The stage control unit 505 transmits and receives control signals from each control unit, and performs feedback control of the wafer stage 107. The wafer stage 107 can be driven in a two-dimensional direction (x-axis and y-axis direction), a vertical direction (z-axis direction), and a rotation direction (θx, θy, and θz directions) with respect to each axis. A suitable driving means. The position information of the wafer stage 107 is measured by a measuring means such as a distance measuring laser interferometer, and the stage controller 505 controls the position of the wafer 106 based on the measurement result.

  FIG. 6 is a block diagram showing a part of an immersion exposure apparatus according to Embodiment 2 of the present invention. The configuration in FIG. 6 is the same as the configuration in FIG. 2 except that the mirror 601 and the mirror 602 are arranged in the optical path of the transmitted light beam among the two light beams divided by the light beam splitting element 203. 2 has the same configuration. Therefore, in the following description, common parts will be denoted by the same reference numerals, and detailed description thereof will be omitted, and parts different from the configuration of FIG. 2 will be mainly described.

  FIG. 6 is a cross-sectional view of the interference optical system 103 in FIG. The configuration and effects of the interference optical system according to the present embodiment will be described with reference to FIG. In FIG. 6, an incident light beam (light beam 201) is divided into a reflected light beam and a transmitted light beam by a light beam splitting element 203. The reflected light beam is reflected by the mirror 204 and the reflecting surface 208 of the interference prism 206 and enters the wafer 106 at a desired angle. Similarly, the transmitted light beam is reflected by the mirror 601, the mirror 602, and the reflection surface 208 of the interference prism 206, and enters the wafer 106 at a desired angle. In this embodiment, the mirror 601 and the mirror 602 are disposed in the optical path of the transmitted light beam divided by the light beam splitting element. With such a configuration, the number of reflections of the two light beams superimposed on the wafer surface with respect to the reflecting surfaces of the light beam splitting element, the mirror, and the interference prism is controlled to be the same, and the two light beams The optical path length is also controlled to be the same. By making the number of reflections of the two light beams the same, the light quantity ratio between the two light beams can be easily controlled. Further, by making the optical path lengths of the two light beams the same, the coherence of the two light beams is improved. Therefore, the optical contrast of the interference fringes formed by superimposing the two light beams on the surface of the wafer 106 is improved, and a periodic fine pattern can be exposed with a high contrast.

  FIG. 7 is a block diagram showing a part of an immersion exposure apparatus according to Embodiment 3 of the present invention. The configuration of FIG. 7 has the same configuration as the configuration of FIG. 6 except that in the configuration of FIG. 6 described above, a measurement unit is added to measure the refractive index characteristics of the liquid film 105. Therefore, in the following description, common parts will be denoted by the same reference numerals, and detailed description thereof will be omitted, and parts different from the configuration of FIG. 6 will be mainly described.

  FIG. 7 is a cross-sectional view of the interference optical system 103 in FIG. The configuration of the refractive index measuring means and the measuring method according to this embodiment will be described with reference to FIG. In FIG. 7, reference numeral 701 denotes a pinhole mask having a minute pinhole of about 0.3 mm with respect to the shape of the light beam 201 shaped by the aperture 202, and is arranged so as to be detachable from the optical path. In the refractive index measuring means according to the present embodiment, the light beam 201 shaped into a minute shape by the mask 701 is used as the test light beam. A light beam 201 as a test light beam is split by a light beam splitting element 203 into a test light beam 702 (reflected light beam) and a test light beam 703 (transmitted light beam). The test light beam 702 is reflected by the mirror 204 and the reflection surface 208 of the interference prism 206, passes through the transmission surface 209, and enters the reflection substrate 704 through the liquid film 105 at a desired angle. Similarly, the test light beam 703 is reflected by the mirror 601, the mirror 602, and the reflection surface 208 of the interference prism 206, passes through the transmission surface 209, and is desired to the reflection substrate 704 via the liquid film 105. Incident at an angle of. Here, the reflective substrate 704 is held on the wafer stage 107, and the reflective surface of the reflective substrate 704 is set to be in the same plane as the exposure surface on the wafer 106 surface. The test light beam 702 reflected by the reflective substrate 704 passes through the transmission surface 209 of the interference prism 206 through the liquid film 105. Further, the light is reflected by the reflecting surface 208, reflected by the reflecting surfaces of the mirror 602, the mirror 601, and the light beam splitting element 203, and received by the photodetector 705. The test light beam 703 reflected by the reflective substrate 704 passes through the transmission surface 209 of the interference prism 206 through the liquid film 105, is reflected by the reflection surface 208, is reflected by the mirror 204, and is divided into light beams. The light passes through the element 203 and is received by the photodetector 705. It is desirable that the output of the light detector 705 is sensitively changed according to the incident position of the light beam. For example, a position sensitive detector may be used. Furthermore, the function of the split detector may be equivalently realized by combining a light beam splitting element such as a beam splitter and a plurality of photodetectors. Moreover, it is also possible to monitor the amount of change in the transmittance of the liquid film 105 by using a light amount detector as one of the plurality of photodetectors.

  Next, a measuring method of the refractive index measuring unit according to the present embodiment will be described. When the refractive index of the liquid film 105 changes, the optical paths of the test light beam 702 and the test light beam 703 in the liquid film 105 change. In other words, the test light beam 702 and the test light beam 703 transmitted through the transmission surface 209 of the interference prism 206 change the angle at which they are refracted by the liquid film 105 due to the change in the refractive index of the liquid film 105, and are incident on the reflection substrate 704. The angle to be reflected (reflected angle) changes. Accordingly, since the incident position of the test light beam 702 and the test light beam 703 with respect to the photodetector changes due to the change in the refractive index of the liquid film 105, the output of the light detector 705 changes. In FIG. 7, the position of the reflecting surface 704 is controlled by a stage driving means (not shown), and the position of the reflecting surface is controlled so that the output of the photodetector 705 matches the output before the refractive index change. The amount of change in the refractive index of the liquid film 105 can be measured from information on the shift amount of the position of the reflecting surface 704 obtained by such control. Further, a pinhole mask 706 provided with pinholes may be disposed in the optical path between the light beam splitting element 203 and the photodetector 705. By setting the center of the pinhole of the pinhole mask 706 to the center of the optical axis of the test light beam 702 and the test light beam 703 before the refractive index change, from the information on the light amount change obtained from the output of the photodetector 705, It is also possible to measure the amount of change in the refractive index of the liquid film 105.

  In this embodiment, the refractive index information of the liquid film 105 measured by the above-described refractive index measuring unit is fed back to the control device 501. The exposure apparatus according to the present embodiment is controlled by controlling the control conditions in the light source control unit 502, the interferometer control unit 503, the liquid control unit 504, and the stage control unit 505 in accordance with the amount of change in the refractive index of the liquid film 105. It is possible to optimize the exposure conditions. Specifically, for example, the stage is driven in the z-axis direction according to the amount of change in the refractive index of the liquid film 105.

  FIG. 8 is a block diagram showing a part of an immersion exposure apparatus according to Embodiment 4 of the present invention. In the configuration of FIG. 8, a beam splitter 801 and a beam splitter 802 are further arranged in the optical path of the transmitted beam among the two beams split by the beam splitter 203 in the configuration of FIG. 6. Further, in the configuration of FIG. 6, an interference prism 806 and a plurality of mirrors for guiding the light beam to the interference prism 806 are arranged. Other configurations are the same as those in FIG. Therefore, in the following description, common parts will be denoted by the same reference numerals, and detailed description thereof will be omitted, and parts different from the configuration of FIG. 6 will be mainly described.

  8A is a cross-sectional view (yz plane) of the interference optical system 103 in FIG. 1, and FIG. 8B is a perspective view thereof. The configuration and effect of the interference optical system according to the present embodiment will be described with reference to FIG. In FIG. 8, a light beam 201 is divided into a reflected light beam (light beam L1) and a transmitted light beam by a light beam splitting element 203. By arranging the light beam splitting element 801, the light beam splitting element 802, and the mirror 803 in the optical path of the transmitted light beam, the light beam is split into the light beam L2, the light beam L3, and the light beam L4. The light beam splitting element 801 reflects the transmitted light beam in the −y direction and transmits the reflected light beam in the −z direction. The beam splitting element 802 reflects the reflected light beam in the + x direction and transmits the transmitted light beam in the −z direction. The mirror 803 reflects the transmitted light flux in the −x direction. The divided four light beams L1, L2, L3, and L4 are reflected by the mirror 204, the mirror 602, the mirror 804, and the mirror 805, respectively, and enter the light beam control unit 205. The light beam control unit 205 controls the light amount and polarization state of the light beam L1, the light beam L2, the light beam L3, and the light beam L4. The light beam L1, the light beam L2, the light beam L3, and the light beam L4, which are controlled to have a desired light amount and polarization state by the light beam control unit 205, are incident on the interference prism 806. Here, the interference prism 806 in the drawing is a cross-sectional view on the yz plane, and has a reflection surface 807 and a transmission surface 809. Further, the xz cross section (not shown) similarly has a reflection surface 807 and a transmission surface 808. The light beam L 1, the light beam L 2, the light beam L 3, and the light beam L 4 incident on the interference prism 806 are reflected (totally reflected) by the reflection surface 807 in the interference prism 806, pass through the transmission surface 808, and reach the final surface of the interference prism 806. And the liquid film 105 filled between the wafer 106 and the wafer 106. The four light beams incident on the liquid film 105 are refracted by the liquid film 105 and enter the wafer 106 coated with a photosensitive material as a photosensitive substrate at a desired angle. The light beams L1 and L2 and the light beams L3 and L4 incident at a desired angle are superimposed on the surface of the wafer 106 to form periodic interference fringes orthogonal to each other. By exposing and exposing the photosensitive substrate with the light intensity distribution of the orthogonal periodic fringes, it is possible to form a periodic fine hole pattern corresponding to the light intensity distribution of the interference fringes on the photosensitive substrate. .

  In the exposure apparatus of the present embodiment, a shutter that blocks the light beam may be disposed in each of the optical paths of the light beam L1, the light beam L2, the light beam L3, and the light beam L4. It is possible to mix a periodic line-and-space pattern and a hole pattern on the photosensitive substrate by shielding the light flux with a shutter as necessary.

  Further, the example of four-beam interference has been described in the exposure apparatus of the present embodiment, but the present invention is not limited to four-beam interference and can be applied as long as there are a plurality of beams.

  Next, an embodiment of a device manufacturing method using the exposure apparatus of Embodiments 1 to 4 will be described.

  FIG. 9 shows a flow of a method for manufacturing a device (semiconductor device, liquid crystal display device, etc.). In step 1 (circuit design), a device circuit pattern is designed. In step 2 (wafer process), a circuit pattern is formed on the wafer by lithography. In step 3 (assembly process), individual circuit patterns are separated from the wafer and formed into devices by operations such as wiring and packaging.

  FIG. 10 shows the details of the wafer process. In step 11 (film formation), various films are formed on the wafer by methods such as thermal oxidation, chemical vapor deposition, and physical vapor deposition. In step 12 (resist application), a resist and an antireflection coating are applied on the wafer. In step 13 (exposure), the wafer is exposed with the circuit pattern by any of the exposure apparatuses according to the first to fourth embodiments. In step 14 (development), the wafer is developed. In step 15 (etching), the wafer is etched. In step 16 (ion implantation), ion implantation is performed on the wafer. In step 17 (resist stripping), the resist is removed from the wafer. By repeating these steps, multiple circuit patterns are formed on the wafer.

  By using the device manufacturing method of this embodiment, it is possible to easily manufacture a highly integrated device that has been difficult to manufacture.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

It is a principal part schematic diagram of the immersion exposure apparatus by Example 1 of this invention. 2 is an explanatory diagram of an interference optical system according to Example 1. FIG. 3 is an explanatory diagram of an interference prism according to Embodiment 1. FIG. FIG. 3 is an explanatory diagram of a light flux control unit according to the first embodiment. It is explanatory drawing of the control apparatus of Example 1. FIG. It is a block diagram which shows a part of immersion exposure apparatus by Example 2 of this invention. It is a block diagram which shows a part of immersion exposure apparatus by Example 3 of this invention. It is a block diagram which shows a part of immersion exposure apparatus by Example 4 of this invention. It is a flowchart of the manufacturing method of the device by Example 5 of this invention. 10 is a flowchart of a device manufacturing method of Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Exposure light source 102 Shaping optical system 103 Interference optical system 104 Projection optical system 105 Liquid film (liquid)
106 Wafer 107 Wafer Stage 108 Liquid Supply Device 109 Liquid Recovery Device 110 Supply Tube 111 Recovery Tube 112 Liquid Supply Port 113 Liquid Recovery Port 201 Light Beam 202 Aperture 203 Beam Splitting Element 204 Mirror 205 Beam Control Unit 206 Interference Prism 207 Antireflection Film 208 Reflection Surface 209 Transmission surface 301 Light beam 401 Light beam 402 Light amount control means 403 Beam splitter 404 Photo detector 405 Polarization control means 406 Phase difference plate 407 Linear polarizing plate 408 Linear polarizing plate 501 Control device 502 Light source control unit 503 Interferometer control unit 504 Liquid control Section 505 Stage control section 601 Mirror 602 Mirror 701 Pinhole mask 702 Test light beam (reflected light beam)
703 Inspection beam (transmitted beam)
704 Reflective substrate 705 Photodetector 706 Pinhole mask 801 Beam splitting element 802 Beam splitting element 803 Mirror 804 Mirror 805 Mirror 806 Interference prism 807 Reflecting surface 808 Transmitting surface

Claims (9)

An interference optical system that divides the light from the light source into a plurality of light beams and causes the plurality of light beams to interfere with each other to form an interference pattern on the photosensitive substrate; and via a liquid between the interference optical system and the photosensitive substrate In an exposure apparatus for exposing the photosensitive substrate,
The interference optical system has a prism in contact with the liquid,
An exposure apparatus, wherein an angle formed by a surface normal of an exit surface from which the light flux of the prism exits and a surface normal of a surface of the photosensitive substrate is greater than 0 degrees. The interference optical system further includes a light beam splitting element that splits light from the light source into the plurality of light beams,
2. The exposure apparatus according to claim 1, wherein the prism superimposes the plurality of light beams divided by the light beam splitting element on the photosensitive substrate through the emission surface and the liquid. When the refractive index of the prism is n1, the refractive index of the liquid is n2, and the refractive index of the photosensitive agent applied to the photosensitive substrate is n3,
n1 <n2 <n3
The exposure apparatus according to claim 1, wherein: The angle between the surface normal of the exit surface and the surface normal of the surface of the photosensitive substrate is θp, the angle between the surface normal of the exit surface and the optical axis of the light flux in the liquid is θ2, and the photosensitive When the angle between the surface normal of the surface of the substrate and the optical axis of the luminous flux in the liquid is θIN,
θIN = θ2 + θp
The exposure apparatus according to claim 1, wherein:   The interference optical system further includes a light amount control unit for controlling the light amount and a light amount detection unit for detecting the light amount in each optical path of the plurality of light beams divided by the light beam dividing element. The exposure apparatus according to claim 2.   3. The exposure apparatus according to claim 2, wherein the interference optical system further includes polarization control means for controlling a polarization state in each optical path of the plurality of light beams divided by the light beam splitting element. . A stage for holding the photosensitive substrate;
The control unit for driving the stage to change the interference pattern by changing an incident angle or an incident direction of the plurality of light beams with respect to the surface of the photosensitive substrate. Exposure equipment. The interference optical system has a measuring means for measuring the refractive index of the liquid,
The exposure apparatus according to claim 1, wherein the measurement unit includes a mask provided with a pinhole, and a position detector that detects an incident position of light through the mask and the liquid. Using the exposure apparatus according to claim 1 to expose a photosensitive substrate;
And developing the exposed photosensitive substrate.

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