JP2013181779A - Measuring instrument, holding device, exposure device, and method for manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology advantageous to calculate the height of a holding surface for holding an original plate.SOLUTION: A measuring instrument for measuring the height of a holding surface while holding an original plate on the holding surface for holding an undersurface of the original plate is provided. The measuring instrument has an irradiation part for irradiating detection light to a place outside a pattern area on the undersurface of the original plate held on the holding surface, a detection part for detecting the detection light reflected at the place, and a processing part for calculating the height of the place from information of the detection light detected by the detection part.

Description

  The present invention relates to a measurement apparatus, a holding apparatus, an exposure apparatus, and a device manufacturing method.

  An exposure apparatus is used when a liquid crystal display device or a semiconductor device is manufactured using a so-called photolithography technique in which a pattern formed on a mask (original plate) is transferred to a substrate. The exposure apparatus includes a mask stage that moves while holding a mask, and a substrate stage that moves while holding a substrate. The mask pattern is moved through the projection optical system while sequentially moving the mask stage and the substrate stage. Is transferred to the substrate.

  The exposure apparatus includes a batch type exposure apparatus (stepper) that simultaneously transfers the entire mask pattern onto the substrate, and a scanning type that transfers the mask pattern onto the substrate continuously while synchronously scanning the mask stage and the substrate stage. It is roughly divided into an exposure device (scanner). When manufacturing a liquid crystal display device, a scanner is mainly used because of a demand for a large display area.

  Further, in recent years, the mask has been increased in size, and the mask has been bent due to its own weight. If the mask is bent, the mask pattern cannot be accurately transferred to the substrate (that is, the pattern transfer accuracy is reduced), and thus it is necessary to correct (correct) the mask deflection. . Therefore, in order to correct the deflection of the mask, a technique for measuring the shape (surface shape) of the mask has been proposed (see Patent Document 1).

JP 2003-264136 A

  In the exposure apparatus, when the mask is enlarged, the mask stage for holding the mask is also enlarged. Since the mask is generally held on the upper surface (holding surface) of the mask stage, it is difficult to measure the pattern surface (that is, the lower surface) of the mask held on the mask stage from the lower surface side of the mask. . Further, since the increase in size of the mask stage extends in the height direction in order to maintain rigidity, it is further difficult to measure the pattern surface of the mask from the lower surface side of the mask.

  In order to flatten the surface shape of the mask held on the mask stage, the holding surface for holding the mask must be flattened on the mask stage. When the mask becomes larger, the holding surface of the mask stage differs greatly between the state holding the mask and the state not holding the mask, so the mask stage can be held while holding the mask. It is necessary to measure the shape (height) of the surface.

  However, when the shape of the holding surface of the mask stage is measured from the upper surface side of the mask while holding the mask, an error corresponding to the thickness of the mask occurs. The shape cannot be measured with high accuracy.

  Further, in Patent Document 1, light is incident on the mask obliquely from the lower surface side of the mask, so that the vertical position (mask) of the light irradiation position on the mask (for example, the exposure light irradiation position) is disclosed. A technique for measuring (the shape of) is disclosed. In the technique of Patent Document 1, as the angle of light incident on the mask (incident angle) is increased, the shape of the mask can be measured without being affected by the presence or absence of the mask pattern. However, if the incident angle of light incident on the mask is increased, the mask stage enlarged in the height direction limits the incident range of such light to the central region of the mask, so the mask shape is measured over a wide range. I can't. In other words, the region in which the mask shape can be measured is limited to the central region of the mask, and the height (position) of the mask in the vicinity of the holding surface that can be regarded as the height (position) of the holding surface of the mask stage. Cannot be measured.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a technique advantageous for obtaining the height of the holding surface for holding the original.

  In order to achieve the above object, a measuring device according to one aspect of the present invention is a measuring device that measures the height of the holding surface in a state where the original is held on a holding surface for holding the lower surface of the original. An irradiating unit that irradiates detection light to a position outside the pattern area on the lower surface of the original plate held by the holding surface; a detection unit that detects the detection light reflected by the part; and the detection unit. And a processing unit that obtains the height of the portion from the detected information of the detection light.

  Further objects and other aspects of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, for example, a technique advantageous for obtaining the height of the holding surface for holding the original plate is provided.

It is a schematic perspective view which shows the structure of the exposure apparatus as 1 side surface of this invention. It is a schematic side view which shows the structure of the exposure apparatus as one side surface of this invention. It is a figure which shows the schematic structure of the measurement part of the exposure apparatus shown in FIG. It is a figure which shows the specific structure of the irradiation part and detection part of the measurement part shown in FIG. It is a figure which shows the specific structure of the irradiation part and detection part of the measurement part shown in FIG. It is a figure which shows the schematic structure of the measurement part of the exposure apparatus shown in FIG. It is a figure which shows the schematic structure of the measurement part of the exposure apparatus shown in FIG. It is a figure for demonstrating an example of a structure of the adjustment part of the exposure apparatus shown in FIG. It is a figure for demonstrating determination of the erroneous measurement of the to-be-measured position by the measurement part of the exposure apparatus shown in FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  1 and 2 are a schematic perspective view and a schematic side view, respectively, showing the configuration of an exposure apparatus 1 as one aspect of the present invention. The exposure apparatus 1 is a lithography apparatus that projects a mask (original plate) pattern onto a substrate (for example, a large substrate such as a liquid crystal display device) by a projection optical system, and transfers the mask pattern (circuit pattern) onto the substrate. In this embodiment, the exposure apparatus 1 is suitable as a lithographic apparatus for manufacturing a liquid crystal display device. However, the exposure apparatus 1 can also be applied to a lithography apparatus that manufactures semiconductor devices, thin film magnetic heads, and the like. In the exposure apparatus 1, the mask is illuminated with light (exposure light) from the illumination optical system when the pattern is transferred to the substrate. The exposure light that has passed through the mask forms an image of the mask pattern through the projection optical system. As a result, the mask pattern is transferred to the substrate disposed at the imaging position of the image of the mask pattern.

  Since using a large-diameter projection optical system capable of batch exposure of a large substrate has many disadvantages in terms of area, weight, stability, and cost of the exposure apparatus, in this embodiment, a partial image of the mask pattern is used. A projection optical system that forms an image in a slit shape is used. Then, by moving (scanning) the mask and the substrate in synchronization with the projection optical system, the illumination area of the exposure light on the mask and the exposure area on the substrate are scanned. This makes it possible to transfer a pattern to a large substrate even when a small projection optical system is used. Thus, in this embodiment, the exposure apparatus 1 is configured as a scanning exposure apparatus (scanner), specifically, a mirror scan exposure apparatus having a large concave mirror. In the following, the optical axis direction of the projection optical system is the Z-axis direction, the direction perpendicular to the Z-axis direction and the direction in which the mask and the substrate are moved (scanning direction) is the Y-axis direction, and the Z-axis direction and the Y-axis The direction orthogonal to the direction is taken as the X-axis direction. The directions around the X axis, the Y axis, and the Z axis are the θX direction, the θY direction, and the θZ direction.

  As shown in FIGS. 1 and 2, the exposure apparatus 1 includes a mask stage 102 that holds a mask 101 on which a pattern is formed, and a substrate stage 104 that holds a substrate 103. Further, the exposure apparatus 1 controls the illumination optical system 105 that illuminates the mask 101 with the exposure light EL, the projection optical system 106 that projects the pattern (image) of the mask 101 illuminated with the exposure light EL onto the substrate 103, and the control. Unit 115, measurement unit 120, and adjustment unit 130.

  The mask 101 held on the mask stage 102 and the substrate 103 held on the substrate stage 104 are arranged in an optically conjugate positional relationship via the projection optical system 106. The substrate 103 is a substrate onto which the pattern of the mask 101 is transferred, and includes, for example, a glass plate (glass substrate). A photoresist (photosensitive agent) is applied to the substrate 103.

  In this embodiment, the illumination optical system 105 is configured as a Koehler illumination system, and expands and collimates the elliptical mirror that collects the light (exposure light EL) emitted from the light source and the light collected by the elliptical mirror. It includes a condenser lens that converts light and a slit plate. The slit plate has a function of defining an illumination area having a predetermined area by cutting a portion of the parallel light from the condenser lens that is not used as light for illuminating the mask 101, and is positioned optically conjugate with the mask 101. Be placed. The illumination optical system 105 also includes a mirror that reflects light from the slit plate and illuminates the mask 101 with slit-like light.

As the light from the illumination optical system 105, that is, the exposure light EL, for example, bright lines (g-line, h-line, i-line) emitted from an external high-pressure mercury lamp are used. Further, far ultraviolet light (DUV light) such as KrF excimer laser light (wavelength 248 nm), vacuum ultraviolet light (VUV light) such as ArF excimer laser light (wavelength 193 nm) and F ₂ laser light (wavelength 157 nm), etc. are used as exposure light. It may be used as EL.

  The mask stage 102 is a stage device (holding device) that holds and moves the mask 101, and is configured to scan the mask 101 with respect to the illumination optical system 105. In this embodiment, the mask stage 102 has a long stroke in the Y-axis direction (scanning direction) and an appropriate stroke in the X-axis direction orthogonal to the scanning direction.

  The mask stage 102 has a chuck 107 including a holding surface 107a for holding the peripheral area of the lower surface of the mask 101 (see FIG. 3). The holding surface 107a of the chuck 107 is connected to a vacuum device (not shown), and the mask 101 is vacuum-sucked and held on the holding surface 107a. The mask stage drive unit 108 is controlled by the control unit 115 and drives the mask stage 102 in the X-axis direction and the Y-axis direction.

  As shown in FIG. 1, movable mirrors 109 a and 109 b are arranged in directions orthogonal to each end of the mask stage 102 in the X-axis direction and the Y-axis direction. In addition, the laser interferometer 110x1 is disposed so as to face the moving mirror 109a, and a plurality (two in this embodiment) of laser interferometers 110y1 and 110y2 are disposed so as to face the moving mirror 109b.

  The laser interferometer 110x1 irradiates the moving mirror 109a with laser light, and measures the distance between the laser interferometer 110x1 and the moving mirror 109a. The measurement result of the laser interferometer 110x1 is output to the control unit 115, and the control unit 115 obtains the position of the mask stage 102 in the X-axis direction based on the measurement result of the laser interferometer 110x1. Similarly, the measurement results of the laser interferometers 110y1 and 110y2 are output to the control unit 115, and the control unit 115 determines the position of the mask stage 102 in the Y-axis direction and the Z-axis based on the measurement results of the laser interferometers 110y1 and 110y2. Find the amount of rotation around. The control unit 115 controls the mask stage driving unit 108 while monitoring (monitoring) the position (posture) of the mask stage 102 from the outputs of the laser interferometers 110x1, 110y1, and 110y2, thereby controlling the mask stage 102 at a desired position ( Control).

  The exposure light EL that has passed through the mask 101 enters the projection optical system 106. The projection optical system 106 forms an image of a pattern existing in the illumination area of the mask 101 on the substrate 103. As shown in FIG. 2, the projection optical system 106 includes a trapezoidal mirror 106a, a convex mirror 106b, and a concave mirror 106c. In the substrate 103, the projection area of the projection optical system 106 is set to a predetermined shape (for example, an arc shape). Further, the projection optical system 106 can use an equal magnification system, a reduction system, or an enlargement system. When the exposure light EL is DUV light, the projection optical system 106 is made of a glass material that transmits DUV light such as quartz or fluorite. When the exposure light EL is VUV light, the projection optical system 106 is composed of a catadioptric system or a refractive optical system.

  The substrate stage 104 has a substrate holder for holding the substrate 103. Similar to the mask stage 102, the substrate stage 104 has a scanning stroke in the Y-axis direction (scanning direction) and a stroke for step movement in the X-axis direction orthogonal to the scanning direction. Further, the substrate stage 104 is configured to be movable in the Z-axis direction, the θX direction, the θY direction, and the θZ direction. The substrate stage drive unit 111 is controlled by the control unit 115 to drive the substrate stage 104.

  As shown in FIG. 1, movable mirrors 112 a and 112 b are arranged in directions orthogonal to each end of the substrate stage 104 in the X-axis direction and the Y-axis direction. A plurality of (for example, three) laser interferometers 113x1, 113x2, and 113x3 are arranged so as to face the moving mirror 112a extending in the Y-axis direction. The laser interferometers 113x1, 113x2, and 113x3 are arranged at equal intervals along the Y-axis direction. A plurality of (for example, two) laser interferometers 113y1 and 113y2 are arranged so as to face the moving mirror 112b extending in the X-axis direction.

  Each of the laser interferometers 113y1 and 113y2 irradiates the moving mirror 112b with laser light, and measures the distance between the laser interferometer 113y1 and the moving mirror 112b and the distance between the laser interferometer 113y2 and the moving mirror 112b. To do. The measurement results of the laser interferometers 113y1 and 113y2 are output to the control unit 115, and the control unit 115 rotates the position of the substrate stage 104 in the Y-axis direction and around the Z-axis based on the measurement results of the laser interferometers 113y1 and 113y2. Find the amount. Each of the laser interferometers 113x1 to 113x3 irradiates the moving mirror 112a with laser light, and measures the distance between each of the laser interferometers 113x1 to 113x3 and the moving mirror 112a. Since the substrate stage 104 has a long scanning stroke in the Y-axis direction, it is necessary to switch the laser interferometers 113x1 to 113x3 in accordance with the position of the substrate stage 104. The measurement results of the laser interferometers 113x1 to 113x3 are output to the control unit 115, and the control unit 115 obtains the position of the substrate stage 104 in the X-axis direction based on the measurement results of the laser interferometers 113x1 to 113x3. The control unit 115 controls the substrate stage driving unit 111 while monitoring (monitoring) the position (posture) of the substrate stage 104 from the outputs of the laser interferometers 113x1 to 113x3, 113y1, and 113y2, thereby controlling the substrate stage 104 in a desired manner. Control to position (posture).

  Each of the mask stage 102 and the substrate stage 104 is driven by a mask stage driving unit 108 and a substrate stage driving unit 111. The control unit 115 controls each of the mask stage driving unit 108 and the substrate stage driving unit 111 while monitoring the position of the mask stage 102 and the position of the substrate stage 104. Thereby, the mask 101 and the substrate 103 can be scanned with respect to the projection optical system 106 at an arbitrary scanning speed (synchronous movement speed).

  When linear motors are used as the mask stage driving unit 108 and the substrate stage driving unit 111, for example, an air levitation type using an air bearing or a magnetic levitation type using Lorentz force or reactance force can be employed. In this case, the mask stage 102 and the substrate stage 104 may be a type that moves along a guide, or may be a guideless type that does not use a guide.

  When a planar motor is used as the mask stage driving unit 108 and the substrate stage driving unit 111, either the magnet unit or the electric unit is arranged on the stage side, and the other is arranged on the surface plate (base) side of the stage. To do. The reaction force generated by the movement of the substrate stage 104 can be mechanically released to the floor (ground) using a frame member as disclosed in Japanese Patent Laid-Open No. 8-166475. The reaction force generated by the movement of the mask stage 102 can be released mechanically to the floor (ground) using a frame member as disclosed in Japanese Patent Laid-Open No. 8-330224.

  The control unit 115 includes a CPU, a memory, and the like, and controls the entire exposure apparatus 1 (operation). For example, the control unit 115 controls the correction mechanism that corrects the shape of the mask 101 based on the measurement result of the measurement unit 120 so that the shape of the mask 101 held on the mask stage 102 becomes a predetermined shape.

  The measuring unit (measuring device) 120 has a function of measuring the displacement of the mask 101 in the Z-axis direction, that is, the shape (amount of deflection) of the mask 101. The measuring unit 120 also has a function of measuring the height of the holding surface 107a of the chuck 107 when the mask stage 102 holds the mask 101.

  The measurement unit 120 has the same configuration as that of a grazing incidence type focus sensor used for aligning the surface (exposure surface) of the substrate 103 with the imaging surface of the projection optical system 106. For example, the measurement unit 120 includes an irradiation unit 121, a detection unit 122, and a calculation unit (processing unit) 123 as illustrated in FIG. However, the measurement unit 120 may have a configuration similar to that of the interferometer instead of the oblique incidence type focus sensor. Here, FIG. 3 is a diagram illustrating a schematic configuration of the measurement unit 120 that measures the shape of the mask 101 held on the mask stage 102 (the holding surface 107a of the chuck 107).

  As shown in FIG. 4, the irradiation unit 121 includes a light source 121 a such as a light emitting diode, a projection mark slit 121 b, and a projection lens 121 c, and is provided on the lower surface 101 a of the mask 101 held on the holding surface 107 a of the chuck 107. Irradiate detection light. As shown in FIG. 4, the detection unit 122 includes a light receiving lens 122a and a CCD sensor 122b, and detects detection light reflected by the lower surface 101a of the mask 101. The calculation unit 123 calculates the shape of the mask 101 (the surface shape of the lower surface 101 a of the mask 101) and the height of the holding surface 107 a of the chuck 107 with respect to the mask 101 from the detection light information detected by the detection unit 122. Note that the detection light information includes at least one of the intensity change and the intensity distribution of the detection light detected by the detection unit 122.

  In the measurement unit 120, the measurement position (that is, the irradiation position where the detection light from the irradiation unit 121 is irradiated) MP on the lower surface 101a of the mask 101 is set to a position different from the exposure position in the scanning direction. In order to improve the exposure performance of the exposure apparatus 1, the shape of the lower surface 101a of the mask 101 at the exposure position may be directly measured. However, if the amount of deviation of the mask stage 102 in the Z-axis direction when the mask stage 102 moves in the scanning direction is an amount that does not affect the exposure performance, there is no problem even if the measured position MP is different from the exposure position. By setting the measurement position MP to a position different from the exposure position, the layout of the measurement unit 120 can be freely determined without being restricted in the Z-axis direction (that is, because the projection optical system 106 does not exist). It becomes possible.

  In addition, by setting the measurement position MP to a position different from the exposure position, the angle (incident angle) of the detection light incident on the lower surface 101a of the mask 101 can be further reduced. At this time, as shown in FIG. 5, reflection mirrors 121 d and 122 c are arranged in the irradiation unit 121 and the detection unit 122, respectively, and the detection light is irradiated to the lower surface 101 a of the mask 101 in the vicinity of the holding surface 107 a of the chuck 107. It is also possible. Generally, the exposure apparatus is designed so that exposure light is not shielded by a mask stage. Therefore, if the angle (incident angle) of the detection light incident on the lower surface 101a of the mask 101 is made smaller than the angle corresponding to the numerical aperture (NA) on the object surface side of the projection optical system 106, the entire area of the lower surface 101a of the mask 101 will be increased. Measurement can be performed by the measurement unit 120. Therefore, in the present embodiment, the irradiation unit 121 can irradiate the detection light so that the angle of the detection light incident on the lower surface 101a of the mask 101 is smaller than the angle corresponding to the NA of the projection optical system 106. It is configured. If the thickness of the mask stage 102 in the Z-axis direction is 300 mm, the measurement unit 120 can measure the inner edge of the mask stage 102, that is, the region from the peripheral region CE of the mask 101 to 30 mm.

  In addition, as shown in FIG. 6, the angle of the detection light incident on the lower surface 101 a of the mask 101 can be set to 0 degree by configuring the measurement unit 120 to have the same configuration as the interferometer. In this case, the measurement unit 120 detects the interference light formed by the interference between the detection light reflected by the lower surface 101a of the mask 101 and the reference light (light reflected by the reference surface), so that the Z-axis direction of the mask 101 is detected. , That is, the shape of the lower surface 101a of the mask 101 is measured. In order to improve the degree of freedom of the layout of the measurement unit 120, a reflection mirror 129 may be arranged between the measurement unit 120 and the measurement position MP as shown in FIG.

  As the size of the mask 101 increases, as described above, the deformation of the holding surface 107a of the chuck 107 between the state where the mask stage 102 holds the mask 101 and the state where the mask 101 is not held cannot be ignored. Therefore, it is necessary to obtain the shape of the holding surface 107 a of the chuck 107 in a state where the mask stage 102 holds the mask 101. However, when the shape of the holding surface 107 with the mask stage 102 holding the mask 101 is obtained by irradiating the upper surface 101 b of the mask 101 with light, the thickness of the mask 101 is affected. Therefore, the shape of the holding surface 107 in a state where the mask stage 102 holds the mask 101 cannot be obtained with high accuracy. When the shape of the holding surface 107 in a state where the mask stage 102 holds the mask 101 is obtained by irradiating the lower surface 101a of the mask 101 with light, the angle of the light incident on the lower surface 101a of the mask 101 is If it is large, the incident range of such light is limited. Therefore, since the shape of the lower surface 101a of the mask 101 in the vicinity of the holding surface 107 of the mask stage 102 cannot be measured (specified), the shape of the holding surface 107 cannot be obtained (estimated).

  On the other hand, in the present embodiment, as described above, the angle of the detection light incident on the lower surface 101a of the mask 101 can be reduced. Therefore, the shape of the holding surface 107 can be obtained by measuring the shape of the lower surface 101 a of the mask 101 in the vicinity of the holding surface 107 of the mask stage 102.

  Specifically, first, the irradiation unit 121 irradiates the detection light onto the region RR (the outside of the pattern region) RR of the lower surface 101a of the mask 101 that is a predetermined width from the peripheral region CE of the mask 101. At this time, the detection light is irradiated to at least three positions (three places) in the region RR of the lower surface 101a of the mask 101. Further, the detection unit 122 detects the detection light reflected by the region RR of the lower surface 101a of the mask 101, that is, the detection light reflected by each of at least three positions of the region RR. Then, the calculation unit 123 specifies the shape of the region RR of the lower surface 101a of the mask 101 based on the information on the detection light detected by the detection unit 122. Further, the calculation unit 123 calculates the shape (height) of the holding surface 107 in a state where the mask stage 102 holds the mask 101 based on the specified shape of the region RR. In other words, the calculation unit 123 obtains a difference in height between portions of the holding surface 107 corresponding to at least three positions of the region RR. Note that when calculating the shape of the holding surface 107 of the mask stage 102, for example, a table that represents the relationship between the shape of the lower surface 101a of the mask 101 and the shape of the holding surface 107 of the mask stage 102 may be used.

  The adjustment unit 130 adjusts the height of the holding surface 107 based on the shape of the holding surface 107 of the mask stage 102 obtained by the measurement unit 120 so that the flatness of the holding surface 107 is within an allowable range. For example, as shown in FIGS. 8A and 8B, the adjustment unit 130 includes an insertion / removal mechanism that inserts / removes the adjustment foil 132 between the chuck 107 and the mask stage 102. In this case, as shown in FIG. 8A, the chuck 107 may be divided into a plurality of chuck portions 107c. Then, the adjustment foil 132 is inserted between each chuck portion 107c and the mask stage 102, or the adjustment foil 132 is taken out between each chuck portion 107c and the mask stage 102, whereby the flatness of the holding surface 107 is obtained. Can be within an acceptable range. The adjustment unit 130 may be configured by a drive mechanism that drives the holding surface 107 of the mask stage 102 along the Z-axis direction or tilts the holding surface 107 with respect to the Z-axis direction. A deformation mechanism including a piezoelectric element for deforming 107 may be used.

  On the lower surface 101a of the mask 101, a pattern made of chromium is formed. Therefore, the information of the detection light detected by the detection unit 122 differs between the case where the pattern is formed at the measurement position MP (the irradiation position where the detection light is irradiated) and the case where the pattern is not formed (that is, Detection value shifts). For example, consider a case where detection light is irradiated to a region including both a position where a pattern is formed and a position where a pattern is not formed. In this case, the intensity distribution (waveform) of the detection light reflected by the lower surface 101a of the mask 101 and detected by the detector 122 due to the difference between the reflectance of the mask material constituting the mask 101 and the reflectance of chromium constituting the pattern. ) Will collapse. Such a collapse of the intensity distribution of the detection light becomes a cause of erroneous measurement of the measurement position MP.

  Therefore, in the present embodiment, the calculation unit 123 determines whether or not the measurement target position MP is erroneously measured based on the intensity distribution of the detection light detected by the detection unit 122. As shown in FIG. 9A, the intensity distribution of the detection light detected by the detection unit 122 when the detection light is irradiated to a position (area) where the pattern PT is not formed is used as a reference. In this case, the position (measurement value) of the mask 101 obtained from the intensity distribution of the detection light coincides with the actual position of the mask 101. On the other hand, as shown in FIG. 9C, when the detection light is applied to the position (region) where the pattern PT is formed, the detection unit 122 detects it as compared with the case of FIG. 9A. The intensity of the detection light increases, and the intensity distribution deviates from the reference. In such a case, since the position (measurement value) of the mask 101 obtained from the intensity distribution of the detection light does not match the actual position of the mask 101, the calculation unit 123 determines that an erroneous measurement is performed. Further, as shown in FIG. 9B, consider a case where detection light is irradiated to a region including both a position where the pattern PT is formed and a position where the pattern PT is not formed. In such a case, compared with the case of FIG. 9A, the intensity distribution of the detection light detected by the detection unit 122 is deviated from the reference (the intensity distribution is broken). In such a case, since the position (measurement value) of the mask 101 obtained from the intensity distribution of the detection light does not match the actual position of the mask 101, the calculation unit 123 determines that an erroneous measurement is performed.

  When it is determined that the calculation unit 123 has made an erroneous measurement, it is only necessary to search for a position where the measurement unit 120 can normally perform measurement while moving (finely moving) the mask stage 102 in the scanning direction. When the flatness of the mask 101 (the lower surface 101a of the mask 101) needs to be controlled (followed up) to tens of μm or less, the mask is measured even if the measurement position MP (irradiation position for irradiating the detection light) changes by several tens of mm. It is possible to sufficiently control the flatness of 101.

  As described above, the measurement unit 120 determines whether the measurement position MP is erroneously measured by using the irradiation unit 121, the detection unit 122, and the calculation unit 123 included in the measurement unit 120. However, a dedicated unit for determining whether the measurement unit 120 erroneously measures the measurement position MP may be provided.

  Further, as shown in FIG. 3, the measurement unit 120 includes a storage unit 127 that stores position information indicating the position of the pattern formed on the lower surface 101a of the mask 101, and a determination unit 128 that determines the irradiation position of the detection light. May further be included. Specifically, the determination unit 128 determines the irradiation position of the detection light so that the detection light is irradiated to the position where the pattern is not formed on the lower surface 101a of the mask 101. Thereby, it is possible to avoid the measurement unit 120 from erroneously measuring the measurement position MP. In addition, when the detection light is irradiated to the irradiation position determined by the determination unit 128, it may be confirmed whether the measurement unit 120 has not erroneously measured. At this time, if the measurement unit 120 makes an erroneous measurement, the irradiation position information indicating the irradiation position is stored in the storage unit 127, and the irradiation position of the detection light is determined from the next time excluding the irradiation position. do it. Furthermore, while the mask stage 102 is moved (finely moved) in the scanning direction, a position where the measurement unit 120 can perform measurement normally is searched for, and information representing the position may be stored in the storage unit 127.

  Consider a case in which the measurement unit 120 is fixed in the exposure apparatus 1. In this case, in order to measure the shape of the mask 101, that is, to detect the detection light reflected at each of at least three positions on the lower surface 101a of the mask 101, it is necessary to provide at least three measurement units 120. is there.

  As described above, by reducing the angle of the detection light incident on the lower surface 101a of the mask 101, the shape of the lower surface 101a of the mask 101 in the vicinity of the holding surface 107 of the mask stage 102 can be measured. As a result, the shape of the holding surface 107 in a state where the mask stage 102 holds the mask 101 can be obtained with high accuracy. On the other hand, when measuring the shape in the vicinity of the center of the lower surface 101a of the mask 101, the angle of the detection light incident on the lower surface 101a of the mask 101 is not limited, so that the angle can be increased. Therefore, an angle changing unit that changes the angle of the detection light incident on the lower surface 101 a of the mask 101 may be provided in the irradiation unit 121. Thereby, the measurement unit 120 can maintain the measurement accuracy while being able to measure the entire area of the lower surface 101a of the mask 101.

  Focusing on the exposure performance of the exposure apparatus 1, the surface shape of the mask 101 in the exposure region affects the exposure performance, but the surface shape of the mask 101 outside the exposure region and the shape of the holding surface 107 of the mask stage 102 are the exposure performance. Does not affect. However, in order to flatten the surface shape of the mask 101 in the exposure region, it is necessary to obtain the surface shape of the mask 101 outside the exposure region and the shape of the holding surface 107 of the mask stage 102 when the apparatus is started up. is there. Therefore, it is effective to provide an angle changing unit that changes the angle of the detection light incident on the lower surface 101 a of the mask 101.

  In the exposure apparatus 1 of the present embodiment, the shape of the lower surface 101a of the mask 101 in the vicinity of the holding surface 107 of the mask stage 102 can be measured by the measuring unit 120, and the shape of the holding surface 107 of the mask stage 102 is changed. It can be obtained with high accuracy. Then, based on the shape of the holding surface 107 of the mask stage 102 obtained by the measurement unit 120, the height of the holding surface 107 of the mask stage 102 is adjusted so that the flatness of the holding surface 107 is within an allowable range. Can do. Therefore, the exposure apparatus 1 controls the surface shape of the mask 101 held on the mask stage 102 with high accuracy to provide a high-quality device (semiconductor element, LCD element, imaging element (CCD, etc.), thin film magnetic head, etc.). Can be provided. Such a device includes a step of exposing a substrate (wafer, glass plate, etc.) coated with a photoresist (photosensitive agent) using the exposure apparatus 1, a step of developing the exposed substrate, and other known steps. , Manufactured by going through.

  As mentioned above, although preferable embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

Claims (9)

A measuring device that measures the height of the holding surface in a state where the original plate is held on a holding surface for holding the lower surface of the original plate,
An irradiating unit that irradiates detection light to a location outside the pattern area on the lower surface of the original plate held by the holding surface;
A detection unit for detecting the detection light reflected at the location;
A processing unit for obtaining the height of the portion from the information of the detection light detected by the detection unit;
A measuring apparatus comprising: The irradiation unit irradiates each of at least three places with the detection light,
2. The processing unit obtains a difference in height of portions corresponding to the at least three portions of the holding surface based on information of the detection light reflected at each of the at least three portions. The measuring device described in 1.   The measuring apparatus according to claim 1, wherein the irradiation unit includes a changing unit that changes an incident angle of the detection light with respect to a lower surface of the original plate. A storage unit that stores information representing an area where the pattern area exists on the lower surface of the original;
A determination unit that determines the location based on the information stored in the storage unit;
The measuring device according to claim 1, further comprising:   5. The measurement apparatus according to claim 1, wherein the information on the detection light includes information on at least one of an intensity change of the detection light and an intensity distribution of the detection light. A holding device for holding an original plate,
A chuck having a holding surface for holding the lower surface of the original plate;
A measuring device according to any one of claims 1 to 5,
An adjustment unit that adjusts the height of the holding surface based on the height measured by the measurement device;
A holding device comprising: The holding device according to claim 6, which holds an original plate;
A projection optical system that projects the pattern of the original onto a substrate;
An exposure apparatus comprising:   The exposure apparatus according to claim 7, wherein an incident angle of the detection light with respect to a lower surface of the original plate is smaller than an angle corresponding to a numerical aperture on an object surface side of the projection optical system. Exposing the substrate using the exposure apparatus according to claim 7 or 8,
Developing the substrate exposed in the step;
A device manufacturing method characterized by comprising:

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