JP2019158431A - Inspection device, inspection method, and processing method for reflection type optical member - Google Patents

Abstract

An inspection apparatus, an inspection method, and a method of processing a reflection-type optical member capable of suppressing optical loss, improving uniformity of illumination light illuminating an inspection area, and improving inspection sensitivity. An inspection apparatus according to the present invention includes: a light source unit that generates illumination light by irradiating a predetermined material drop with laser light to generate plasma; and a reflection unit that reflects at least a part of the illumination light. An illumination optical system including a mold optical member 110 for illuminating the inspection target 111 with the illumination light, a condensing optical system for condensing light from the rectangular inspection region 120 in the inspection target 111 illuminated with the illumination light, A detector 119 that scans the emitted light with the direction in which one side of the inspection region 120 extends as a scanning direction, thereby acquiring an image of the inspection region 120. A plurality of grooves 20 are formed on the surface in a direction perpendicular to the scanning direction. [Selection diagram] FIG.

Description

  The present invention relates to an inspection apparatus, an inspection method, and a processing method for a reflective optical member. For example, in order to detect defects in an EUV mask used in EUV lithography (Extremely Ultraviolet Lithography) as a lithography process in a semiconductor manufacturing process. The present invention relates to an inspection apparatus, an inspection method, and a processing method for a reflective optical member. The EUV mask to be inspected is, for example, a patterned EUV mask in which a multilayer film and an absorber are provided on a substrate (called a substrate), and the absorber is patterned.

  With regard to lithography technology for miniaturization of semiconductors, ArF lithography using an ArF excimer laser with an exposure wavelength of 193 nm as an exposure light source is currently being mass-produced. An immersion technique (called ArF immersion lithography) that fills the space between the objective lens of the exposure apparatus and the wafer with water to increase the resolution is also used for mass production. Furthermore, in order to realize further miniaturization, various technical developments have been made for practical use of EUVL with an exposure wavelength of 13.5 nm.

  As shown in FIG. 14, the EUV mask 10 is provided with a multilayer film 12 for reflecting EUV light on a substrate 11 made of low thermal expansion glass as a laminated structure. The multilayer film 12 usually has a structure in which several tens of layers of molybdenum and silicon are alternately stacked. Thereby, the multilayer film 12 can reflect about 65% of EUV light having a wavelength of 13.5 nm vertically. An absorber 13 that absorbs EUV light is provided on the multilayer film 12. Blanks can be formed by patterning the absorber 13. However, a protective film 14 (a film called a buffer layer and a capping layer) is provided between the absorber 13 and the multilayer film 12. In order to actually use for exposure, the absorber 13 is patterned by a resist process. In this way, a patterned EUV mask is completed.

  The size of an unacceptable defect in the EUV mask 10 is significantly smaller than that of a conventional ArF mask, making it difficult to detect. Accordingly, an actinic inspection that uses EUV light, that is, illumination light having the same wavelength as that of exposure light having a wavelength of 13.5 nm, is indispensable for pattern inspection. Note that the actinic inspection apparatus for blanks of the EUV mask 10 is disclosed in Non-Patent Document 1 below, for example. A light source that generates EUV light having a wavelength of 13.5 nm is sometimes referred to as an actinic light source. Here, it is referred to as an EUV light source.

  As a general basic configuration of an inspection apparatus for the EUV mask 10, EUV light extracted from an EUV light source is guided to the EUV mask 10 by an illumination optical system including only a multilayer mirror for EUV. Illuminates a minute inspection area on the pattern surface. The pattern of the EUV mask 10 in this inspection region is projected (imaged) onto the surface of a two-dimensional image sensor of a CCD camera or a TDI (Time Delay Integration) camera by an magnifying optical system composed only of a multilayer mirror. Then, the observed pattern is analyzed to determine whether the pattern is correct. In this way, the pattern inspection of the EUV mask 10 is performed.

  In general, EUV light sources include DPP (Discharge Produced Plasma) light sources and LPP (Laser Produced Plasma) light sources. The DPP light source is a system that generates xenon (Xe) by discharge. The LPP light source is a system in which plasma is generated by condensing laser light with respect to drops of tin (Sn) or lithium (Li) ejected in the form of minute drops.

  The illumination optical system of the inspection apparatus for the EUV mask 10 is an optical system that condenses EUV light generated from a light source in a narrow area including the inspection area so that a minute inspection area in the EUV mask can be illuminated brightly. is necessary. As one of such optical systems, an optical system that projects the light emitting part of the light source onto the pattern surface of the EUV mask 10 is desirable. However, since only a mirror can be used for the optical system, for example, an optical system using one or two rotating ellipsoidal mirrors (hereinafter simply referred to as an ellipsoidal mirror) is used. This is because the ellipsoidal mirror has two condensing points, and the light generated from one condensing point has a property of condensing at the other condensing point.

  Two condensing points of the ellipsoidal mirror are defined as a first condensing point and a second condensing point. The EUV light source, the ellipsoidal mirror, and the EUV mask 10 are arranged so that the first condensing point matches the light emitting part of the light source and the second condensing point matches the minute inspection region in the EUV mask 10. Deploy. For example, when the light source is an LPP light source, the first condensing point is made to match the bright spot of the plasma. Thereby, it is possible to guide and illuminate EUV light up to a minute inspection region. The DPP light source in the EUV light source is shown, for example, in Non-Patent Document 2 below, and the LPP light source in the EUV light source is shown in Non-Patent Document 3, for example.

  The principle is the same when two ellipsoidal mirrors are used. That is, the light-emitting portion of the light source is aligned with the first condensing point of one ellipsoidal mirror, and the first condensing point of the other ellipsoidal mirror is aligned with the second condensing point. . Further, the second condensing point of the other ellipsoidal mirror is matched with the inspection region.

  On the other hand, when pattern inspection of the EUV mask 10 is performed using the inspection apparatus of the EUV mask 10, image data in the inspection region on the pattern surface of the EUV mask 10 is usually acquired by a TDI camera. Since the EUV mask 10 performs a reciprocating scan operation in one direction on the stage, the pattern surface imaged by the TDI camera always changes. That is, the reflected light of a specific location on the EUV mask 10 is accumulated by the number of pulses by illumination of pulsed illumination light that repeatedly operates. According to this, even if there is some unevenness in the illuminance distribution of the illumination light with respect to the scanning direction, the accumulated energy is made uniform by integrating the pulsed reflected light. Therefore, even if there is a portion with low illuminance in the scan direction, it is possible to suppress a decrease in inspection sensitivity. Since the mask scanning direction corresponds to the integration direction of the TDI operation, this direction is also referred to as the TDI integration direction.

JP 2006-033336 A JP 2010-007945 A

A. Tchikoulaeva, et.al., “EUV actinic blank inspection: from prototype to production”, Proceedings of SPIE Volume 8679, Extreme Ultraviolet (EUV) Lithography IV; 86790I (2013). P. A. Blackborow, et.al., “EUV Source development for AIMS and Blank Inspection”, Proceedings of SPIE Volume 7636, Extreme Ultraviolet (EUV) Lithography; 763609 (2010). S. Ellwi, et.al., “High-brightness LPP source for actinic mask inspection”, Proceedings of SPIE Volume 7969, Extreme Ultraviolet (EUV) Lithography II; 79690C (2011).

  The size of the light emitting part of the LPP light source as shown in Non-Patent Document 3 is almost equal to the size of the plasma bright spot. For example, the size of the light emitting portion of the LPP light source is generally about 50 to 60 [μm], and has a diameter of 100 [μm] or less. However, the inspection region on the inspection surface such as the pattern surface of the EUV mask 10 may be a rectangular region having a width of 100 [μm] or more in order to shorten the inspection time, for example.

  FIGS. 15A and 15B are diagrams exemplifying a simulation result of the inspection area 120 on the inspection surface of the EUV mask 10 and a light emitting unit projected onto the inspection area 120, and FIG. On the other hand, the case where the light emitting unit is projected at the same magnification is shown, and (b) shows the case where the light emitting unit is projected twice with respect to the inspection region 120. The inspection region 120 has a rectangular shape, the long side is 200 [μm], and the short side is 100 [μm].

  As shown in FIG. 15A, when the light emitting portion projected onto the inspection surface is assumed to have a diameter of 100 [μm], the inspection region 120 includes a portion where the light emitting portion is not projected. Therefore, as shown in FIG. 15B, it is necessary to use an illumination optical system that projects the light emitting unit projected onto the inspection surface by magnifying it twice or more so that it can be illuminated over the inspection region 120.

  However, if it does so, the light quantity of the illumination light which illuminates areas other than the test | inspection area | region 120 will increase. Therefore, a decrease in utilization efficiency of illumination light extracted from the light source becomes a problem. Therefore, in order to prevent the illuminance from decreasing when illuminating with double projection as compared with illuminating with equal magnification projection, it is necessary to increase the total power of EUV light extracted from the light source. For example, since the area of the light emitting part in the case of double projection is four times the area of the light emitting part in the case of equal magnification projection, it is necessary to increase the total power of EUV light extracted from the light source by four times. However, for that purpose, it is necessary to increase the power of the EUV light source itself.

  Further, in order to increase the power of the EUV light source itself, not only the light source is changed to a high output type but also another problem arises.

  FIG. 16 is a cross-sectional view illustrating the EUV mask 10 and the illumination light EUV 104 that illuminates the EUV mask 10. As shown in FIG. 16, an EUV pellicle 113 that protects a pattern is attached to the EUV mask 10 when performing exposure processing of the EUV mask 10. For this reason, when the pattern of the EUV mask 10 is inspected, the illumination light EUV 104 passes through the EUV pellicle 113 and illuminates the inspection surface.

  FIG. 17 is a diagram illustrating a simulation result of the light emitting unit projected onto the EUV pellicle 113. FIG. 17A illustrates a case where the light emitting unit is projected to the inspection region 120 at the same magnification, and FIG. The case where the light emitting unit is projected to be doubled with respect to the inspection region 120 is shown. As shown in FIGS. 17A and 17B, regarding the illuminance distribution on the EUV pellicle 113, the spot size is the same in both the case of equal magnification projection and the case of double projection. The reason for this is that the distance between the inspection surface of the EUV mask 10 and the EUV pellicle 113 (height of the EUV pellicle 113) is about 2 [mm] with respect to the inspection region 120 of 100 to 200 [μm]. And an order of magnitude larger. Thereby, if the NA of the illumination light on the inspection surface is the same, the illumination size on the EUV pellicle 113 is substantially equal.

  On the other hand, since the EUV pellicle 113 absorbs 10 to 20% of the passing illumination light EUV104, the temperature of the passing region rises. Therefore, when the total power of the illumination light EUV 104 is increased when the projection is greatly performed on the inspection surface of the EUV mask 10 as shown in FIG. 15B, the light intensity (that is, the illuminance) of the illumination light EUV 104 in the EUV pellicle 113 increases. The temperature will rise to a higher temperature. As a result, the deterioration of the EUV pellicle 113 is accelerated.

  Therefore, it is conceivable to expand the light emitting portion in the width direction on the inspection surface by using a fly-eye mirror in the middle of the illumination optical system without increasing the magnification of the light emitting portion projected onto the inspection surface of the EUV mask 10. However, a fly-eye mirror that can be used for EUV light has a problem that optical loss is significantly increased compared to a fly-eye lens that can be used for visible light or ultraviolet light. In a fly-eye lens for visible light or ultraviolet light, it is easy to suppress the insertion loss to about 1 [%] or less by applying a non-reflective coating on the surface. On the other hand, since the EUV fly-eye mirror is composed of a multilayer mirror for EUV, the reflectance is about 65 [%] at the highest. Moreover, two fly-eye mirrors are generally required. Therefore, the insertion loss reaches about 58 [%]. Note that the EUV fly-eye optical system is disclosed in, for example, Patent Documents 1 and 2.

  An object of the present invention is to solve such a problem. For example, even when the inspection area is rectangular, the optical loss is suppressed and the uniformity of illumination light that illuminates the inspection area is improved. Another object of the present invention is to provide an inspection apparatus, an inspection method, and a reflective optical member processing method capable of improving inspection sensitivity.

  An inspection apparatus according to the present invention includes: a light source unit that generates illumination light by irradiating laser light onto a drop of a predetermined material to generate plasma; and a reflective optical member that reflects at least part of the illumination light. An illumination optical system that illuminates the inspection object with the illumination light, a condensing optical system that condenses light from a rectangular inspection region in the inspection object illuminated by the illumination light, and the condensed light A detector that acquires an image of the inspection region by scanning the direction in which one side of the inspection region extends as a scan direction, and the reflective surface of the reflective optical member includes the detector A plurality of grooves arranged in a direction perpendicular to the scanning direction are formed. With such a configuration, optical loss can be suppressed, the uniformity of illumination light that illuminates the inspection area can be improved, and inspection sensitivity can be improved.

  Further, the inspection method according to the present invention includes generating illumination light by irradiating laser light onto a drop of a predetermined material to generate plasma, illuminating an inspection object with the illumination light, and the illumination Condensing light from a rectangular inspection region in the inspection object illuminated by light, and scanning the condensed light with a direction in which one side of the inspection region extends as a scan direction Obtaining an image of the inspection area, and illuminating the inspection object through a reflective optical member that reflects at least a part of the illumination light in the step of illuminating the inspection object, A plurality of grooves arranged in a direction orthogonal to the scanning direction are formed on the reflective surface of the reflective optical member. With such a configuration, it is possible to suppress optical loss, improve the uniformity of illumination light that illuminates the inspection region, and improve inspection sensitivity.

  Furthermore, the processing method of the reflective optical member according to the present invention includes a light source unit that generates illumination light by irradiating laser light onto a drop of a predetermined material to generate plasma, and reflects at least a part of the illumination light. An illumination optical system that illuminates the inspection object with the illumination light, and a condensing optical system that collects light from a rectangular inspection region in the inspection object illuminated with the illumination light, A detector that acquires an image of the inspection region by scanning the condensed light with a direction in which one side of the inspection region extends as a scanning direction, and the reflection type of the inspection apparatus, comprising: A method of processing an optical member, wherein the reflective optical member includes a substrate and a metal film coated on the main surface of the substrate, and the polishing pad is moved in one direction to the main surface of the substrate. Polishing, forming a plurality of grooves arranged in a direction perpendicular to the one direction on the main surface, coating the metal film on the polished main surface, and the reflective optical member, And arranging the plurality of grooves in a direction orthogonal to the scanning direction. With such a configuration, it is possible to suppress optical loss, improve the uniformity of illumination light that illuminates the inspection region, and improve inspection sensitivity.

  The present invention provides an inspection apparatus, an inspection method, and a reflective optical member processing method that can suppress optical loss, improve the uniformity of illumination light that illuminates an inspection area, and improve inspection sensitivity. .

1 is a configuration diagram illustrating an inspection apparatus according to a first embodiment. 3 is a perspective view illustrating a reflective diffraction grating of the inspection apparatus according to Embodiment 1. FIG. 2 is a cross-sectional view illustrating a reflection type diffraction grating of the inspection apparatus according to Embodiment 1. FIG. 4 is a graph illustrating the relative intensity of diffracted light by the reflective diffraction grating according to Embodiment 1, where the horizontal axis indicates the order of the diffracted light and the vertical axis indicates the relative intensity of the diffracted light. (A) is the figure which illustrated the illumination intensity distribution of the illumination light which used the reflective diffraction grating in the inspection apparatus which concerns on Embodiment 1, (b) is a groove | channel not formed in the inspection apparatus which concerns on a comparative example. It is the figure which illustrated the illumination intensity distribution of the illumination light using a multilayer film mirror. 5 is a flowchart illustrating an inspection method using the inspection apparatus according to the first embodiment. FIG. FIG. 6 is a perspective view illustrating a wave type multilayer mirror of an inspection apparatus according to a second embodiment. FIG. 6 is a cross-sectional view illustrating a wave multilayer mirror of an inspection apparatus according to a second embodiment. In the inspection apparatus which concerns on Embodiment 2, it is the figure which illustrated the illumination intensity distribution of the illumination light using a wave type multilayer mirror. (A) is the figure which illustrated the relationship between the illumination light which injects into a waveform multilayer mirror, and the illumination light which reflects with a waveform multilayer mirror in the inspection apparatus which concerns on Embodiment 2. (b) It is the figure which illustrated the relationship between the illumination light which injects into a convex mirror, and the illumination light reflected by a convex mirror. (A)-(c) is the simulation result which illustrated the illumination intensity distribution in the test | inspection surface of a test object at the time of changing the shape of a light emission part in the test | inspection apparatus which concerns on Embodiment 2. FIG. FIG. 10 is a perspective view illustrating a grazing incidence mirror of an inspection apparatus according to a third embodiment. FIG. 10 is a plan view illustrating a method for processing an oblique incidence mirror of the inspection apparatus according to the third embodiment. It is sectional drawing which illustrated the EUV mask. It is the figure which illustrated the simulation result of the light emission part projected on the inspection area | region and inspection area | region in an inspection surface of an EUV mask, (a) shows the case where a light emission part is projected with an equal magnification with respect to an inspection area | region, ( b) shows a case where the light emitting unit is projected twice with respect to the inspection area. It is sectional drawing which illustrated the illumination light which illuminates an EUV mask and an EUV mask. It is the figure which illustrated the simulation result of the light emission part projected on an EUV pellicle, (a) shows the case where a light emission part is projected with an equal magnification with respect to a test | inspection area, (b) shows with respect to a test | inspection area | region. A case where the light emitting unit is projected twice is shown.

  Hereinafter, a specific configuration of the present embodiment will be described with reference to the drawings. The following description shows preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, the same reference numerals indicate substantially the same contents.

(Embodiment 1)
The inspection apparatus according to Embodiment 1 will be described with reference to the drawings. First, the configuration of the inspection apparatus will be described. Thereafter, an inspection method using the inspection apparatus will be described. FIG. 1 is a configuration diagram illustrating an inspection apparatus 100 according to the first embodiment. As shown in FIG. 1, the inspection apparatus 100 includes a light source unit 101, an oblique incidence mirror 108, an oblique incidence mirror 109, a reflective diffraction grating 110a, a stage 112, a Schwarzschild optical system 116, a plane mirror 117, a concave mirror 118, and a detector 119. It has. The Schwarzschild optical system 116 is a magnifying optical system including a concave mirror 116a and a convex mirror 116b. For example, an EUV mask is placed on the stage 112 as the inspection object 111.

  Here, for convenience of description of the inspection apparatus 100, an XYZ orthogonal coordinate system is introduced. The upper surface of the stage 112 is the XZ plane, and the direction orthogonal to the upper surface of the stage 112 is the Y-axis direction. In the figure, the direction perpendicular to the paper surface is taken as the X-axis direction.

  The light source unit 101 includes a bottle 102, a catcher 104, a lens 105, a mirror 106, an oblique incidence mirror 107, and a near infrared laser (not shown). The bottle 102 stores a predetermined material that generates plasma. The bottle 102 stores, for example, liquid tin (Sn) as a predetermined material.

  Drop-shaped tin (tin drop 103) is ejected from the bottle 102 at high speed. A near-infrared laser (not shown) emits a near-infrared laser beam L100. Near-infrared laser light L100 emitted from the near-infrared laser enters the lens 105 and is condensed. The near-infrared laser beam L100 collected by the lens 105 is reflected by the mirror 106 and then irradiates the tin drop 103. Thereby, plasma is generated and illumination light EUV100 is generated.

  The illumination light EUV100 includes, for example, EUV light. The tin drop 103 is received by the catcher 104 and stored. As described above, the light source unit 101 generates the illumination light EUV 100 by generating plasma by irradiating laser light onto a drop of a predetermined material. The light emitting unit that generates the illumination light EUV100 is, for example, a round optical image having a diameter of approximately 60 [μm].

  The illumination light EUV 100 generated together with the plasma enters the oblique incidence mirror 107. The oblique incidence mirror 107 is a metal mirror that is used by making a light ray incident at an incident angle of the illumination light EUV 100 as large as 70 [°] or more. Since the incident angle is as large as 70 [°] or more, it can be said that the angle from the reflecting surface is a shallow angle. That is, the oblique incident angle is 90 [°] −incident angle. Such a grazing incidence mirror 107 can reflect light of a short wavelength such as X-rays that hardly reflect at normal incidence to some extent. For example, in order to reflect EUV light having a wavelength of 13.5 [nm], a multilayer mirror composed of a multilayer film of molybdenum (Mo) and silicon (Si) is generally used. However, if the incident light is incident at an oblique incident angle, the EUV light can be reflected even by a metal mirror.

  The oblique incidence mirror 107 includes, for example, a substrate containing quartz and a metal film coated on the main surface of the substrate. The quartz of the substrate is, for example, synthetic quartz. The metal film is, for example, a ruthenium film. Therefore, in this case, the oblique incidence mirror 107 contains ruthenium as a material. The main surface coated with the ruthenium film is the reflecting surface. The oblique incidence mirror 107 is a kind of metal mirror because the reflection surface contains metal. The oblique incidence mirror 107 is planar. The oblique incidence mirror 107 is not limited to a ruthenium film formed on a quartz substrate as long as it can reflect the illumination light EUV100.

  The illumination light EUV101 reflected by the oblique incident mirror 107 is incident on the oblique incident mirror. The oblique incidence mirror 108 is, for example, an ellipsoidal mirror. The oblique incidence mirror 108 includes, for example, a substrate containing quartz and a metal film coated on the main surface of the substrate, similarly to the oblique incidence mirror 107. The metal film is, for example, a ruthenium film. The surface coated with the ruthenium film is the reflecting surface. The oblique incidence mirror 108 is also a kind of metal mirror because the reflecting surface contains metal. Further, since the grazing incidence mirror 108 is an ellipsoidal mirror, the first focusing point of the two focusing points is arranged so as to be positioned at the plasma bright spot via the oblique incident mirror 107. Yes.

  The illumination light EUV102 reflected by the oblique incidence mirror 108 proceeds while being narrowed down and is collected at the condensing point IF. The condensing point IF is a second condensing point of the oblique incidence mirror 108. The illumination light EUV102 condensed at the condensing point IF spreads after the condensing point IF. Thereafter, the illumination light EUV 102 is reflected by the oblique incidence mirror 109.

  As in the case of the oblique incidence mirror 108, the oblique incidence mirror 109 includes, for example, a substrate containing quartz and a metal film coated on the main surface of the substrate. The metal film is, for example, a ruthenium film. The surface coated with the ruthenium film is the reflecting surface. Since the oblique incidence mirror 109 is an ellipsoidal mirror, the first condensing point of the two condensing points is arranged so as to be positioned at the condensing point IF of the illumination light EUV102. The second condensing point of the oblique incidence mirror 109 is arranged so as to be located in the inspection area of the inspection object 111.

  The illumination light EUV 103 reflected by the oblique incidence mirror 109 proceeds while being narrowed down and enters the reflection type diffraction grating 110a. The illumination light EUV103 incident on the reflective diffraction grating 110a is diffracted and reflected by the reflective diffraction grating 110a. Therefore, the illumination light EUV104 from the reflective diffraction grating 110a includes diffracted light and reflected light. From this, it can be said that the reflective diffraction grating 110a is a reflective optical member 110 that reflects at least a part of the incident illumination light EUV103. A surface on which the illumination light EUV 103 is incident on the reflective optical member 110 is defined as a reflective surface. The illumination light EUV 104 diffracted or reflected from the reflective diffraction grating 110a illuminates the inspection area of the inspection object 111. Therefore, the inspection apparatus 100 includes an illumination optical system that illuminates the inspection object 111 with the illumination light EUV104. The illumination optical system includes, for example, an oblique incidence mirror 108, an oblique incidence mirror 109, and a reflective diffraction grating 110a.

  The oblique incidence mirror 108 has an elliptical surface for projecting the image of the first condensing point to 1/2. Therefore, a round optical image with a diameter of about 60 [μm] is projected onto a round space image with a diameter of about 30 [μm] at the condensing point IF in the light emitting unit. On the other hand, the oblique incidence mirror 109 has an ellipsoidal surface that enlarges and projects the image of the first focal point twice. Therefore, if there is no reflective diffraction grating 110a, a round space image having a diameter of approximately 60 [μm] is projected at a condensing point on the inspection object 111.

  The light EUV 105 from the inspection object 111 illuminated by the illumination light EUV 104 includes the reflected light and diffracted light of the illumination light EUV 104, and includes pattern information in the inspection region. The light EUV 105 from the inspection object 111 is magnified by the Schwarzschild optical system 116 including the concave mirror 116a and the convex mirror 116b. The expanded light EUV 106 is folded back by the plane mirror 117, further expanded by the concave mirror 118, and enters the detector 119. As described above, the inspection apparatus 100 includes a condensing optical system that condenses the light EUV 105 from the inspection region illuminated by the illumination light EUV 104.

  The detector 119 is, for example, a TDI camera. The light EUV 106 from the inspection region is projected onto the sensor surface disposed below the detector 119. Thereby, the detector 119 inputs the pattern of the inspection area as an optical image and acquires an image of the inspection area. Then, the pattern is analyzed and a defect is detected.

  FIG. 2 is a perspective view illustrating the reflective diffraction grating 110a of the inspection apparatus 100 according to the first embodiment. FIG. 3 is a cross-sectional view illustrating the reflective diffraction grating 110a of the inspection apparatus 100 according to the first embodiment. As shown in FIGS. 2 and 3, the inspection apparatus 100 of this embodiment includes a reflective diffraction grating 110 a as the reflective optical member 110. A plurality of linear grooves 20 constituting the diffraction grating are arranged in the X-axis direction on the reflection surface 114 of the reflection type diffraction grating 110a. The groove 20 extends on the reflecting surface 114 in a direction orthogonal to the X-axis direction. When the reflection surface 114 of the reflective diffraction grating 110a is inclined with respect to the Y-axis direction and the Z-axis direction, the groove 20 extends in a plane including the Y-axis direction and the Z-axis direction.

  As shown in FIG. 3, the reflective surface 114 of the reflective diffraction grating 110a is provided with a multilayer film 22 on the substrate 21 in order to reflect EUV light. Further, the reflection surface 114 of the reflection type diffraction grating 110a is provided with a step forming the groove 20. For this reason, the reflective diffraction grating 110a functions as a diffraction grating. For example, the pitch P of the grooves 20 is 7 [μm], and the width W of the grooves 20 is 5 [μm].

  FIG. 4 is a graph illustrating the relative intensity of diffracted light by the reflective diffraction grating 110a according to the first embodiment, where the horizontal axis indicates the order of the diffracted light and the vertical axis indicates the relative intensity of the diffracted light. As shown in FIG. 4, the relative intensity of ± primary light is the highest. Next, the relative intensity of the 0th order light is large, and in the following order: ± 2nd order light, ± 5th order light, ± 3rd order light, and ± 4th order light. The diffraction grating parameters such as the groove pitch P, the groove width W, and the groove depth of the reflection type diffraction grating 110a are incident on the reflection type diffraction grating 110a and the distance between the reflection type diffraction grating 110a and the inspection object 111. It is necessary to optimize depending on the NA (numerical aperture) of the illumination light EUV 103 and the size of the inspection area in the inspection object 111.

  The illumination light EUV104 reflected and diffracted by the reflective diffraction grating 110a has a component that travels in the X-axis direction. Therefore, a part of the illumination light EUV 104 travels obliquely with respect to the YZ plane.

  FIG. 5A is a diagram illustrating an illuminance distribution of the illumination light EUV 104 using the reflective diffraction grating 110a in the inspection apparatus 100 according to the first embodiment, and FIG. 5B is an inspection according to a comparative example. It is the figure which illustrated the illumination intensity distribution of the illumination light using the multilayer film mirror in which the groove | channel 20 is not formed in an apparatus. As shown in FIG. 5A, for example, the inspection area 120 on the inspection surface of the inspection object 111 is a rectangle of 200 [μm] × 100 [μm]. The side of 200 [μm] is the long side, and the side of 100 [μm] is the short side. The extending direction of the long side is, for example, the X-axis direction. The inspection object 111 is placed on the stage 112 and can move in the XZ plane. Specifically, a scanning operation is performed in the Z-axis direction, and a step operation is performed in the X-axis direction.

  Since the plurality of grooves 20 arranged in the X-axis direction are formed on the reflective surface 114 of the reflective diffraction grating 110a, the illumination light EUV104 from the reflective diffraction grating 110a includes diffracted light. Therefore, the illuminance distribution on the inspection surface of the inspection object 111 is a distribution that expands in the X-axis direction. That is, the inspection area 120 is illuminated with a width of about 60 [μm] in the Z-axis direction. On the other hand, the inspection area 120 is illuminated with an intensity that is spread almost uniformly in the X-axis direction. In order to improve uniformity over the inspection region 120, the total number of mirrors used in the illumination optical system is not increased. Therefore, the amount of light that irradiates the inspection object does not change as a whole.

  On the other hand, as shown in FIG. 5B, when a multilayer mirror in which the groove 20 is not formed is used, the illuminance distribution in the inspection region 120 becomes non-uniform in the X-axis direction. Specifically, the illuminance is high in the central portion of the inspection region 120 having a width of about 60 [μm] in the X-axis direction. On the other hand, the illuminance at the end of the inspection region 120 in the X-axis direction is extremely low. Therefore, the inspection sensitivity at the end of the inspection region 120 in the X-axis direction is significantly reduced.

  In the present embodiment, the detector 119 scans the collected light EUV 106 with the direction in which one side of the inspection region 120 extends as the scan direction. One side is, for example, a short side extending in the Z-axis direction. Thereby, the detector 119 acquires an image of the inspection region 120. In such a case, a plurality of grooves 20 arranged in a direction orthogonal to the scanning direction are formed on the reflective surface 114 of the reflective diffraction grating 110a. The direction orthogonal to the scan direction is, for example, the X-axis direction. In other words, a plurality of grooves 20 extending in a direction perpendicular to the other side orthogonal to the scanning direction are formed on the reflective surface 114 of the reflective diffraction grating 110a. The other side of the inspection region 120 is, for example, a long side extending in the X-axis direction. Specifically, a plurality of grooves 20 extending in a direction perpendicular to the long side of the inspection region 120 are formed on the reflective surface 114 of the reflective diffraction grating 110a.

  When the detector 119 is a TDI camera, the detector 119 acquires an image of the inspection region 120 by performing a TDI operation for scanning in the Z-axis direction. Therefore, the detector 119 integrates signals in the Z-axis direction of the scan direction. Therefore, at both ends in the Z-axis direction in the inspection region 120, even if the illuminance is relatively low, a decrease in inspection sensitivity can be suppressed by integration. However, if the illuminance is relatively low at both ends in the X-axis direction in the inspection region 120, the inspection sensitivity cannot be improved even if the signals are integrated.

  A plurality of grooves 20 arranged in a direction orthogonal to the scanning direction are formed on the reflective surface 114 of the reflective diffraction grating 110a of the present embodiment. Thereby, the illuminance distribution can be expanded in the X-axis direction in the inspection region 120, and the uniformity of the illumination light that illuminates the inspection region can be improved.

  The detector 119 may use the X-axis direction in which the long side of the inspection region 120 extends as the scan direction. In that case, a plurality of grooves 20 arranged in the Z direction perpendicular to the scanning direction are formed on the reflective surface 114 of the reflective diffraction grating 110a. That is, a plurality of grooves 20 extending in a direction perpendicular to the long side of the inspection region 120 are formed on the reflective surface 114 of the reflective diffraction grating 110a.

  Next, an inspection method using the inspection apparatus 100 according to the present embodiment will be described. FIG. 6 is a flowchart illustrating an inspection method using the inspection apparatus 100 according to the first embodiment.

  As shown in step S11 of FIG. 6, first, illumination light EUV100 is generated by irradiating a drop of a predetermined material with laser light to generate plasma. Specifically, plasma is generated by irradiating the tin drop 103 with the near-infrared laser light L100, and the illumination light EUV100 is generated. The illumination light EUV100 is, for example, EUV light.

  Next, as shown in step S12, the inspection object 111 is illuminated with the illumination light EUV104. Specifically, the inspection object 111 is illuminated with the illumination light EUV 104 generated by the light source unit 101 via the illumination optical system. When illuminating the inspection object 111, the inspection object 111 is illuminated via the reflective optical member 110 that reflects at least a part of the illumination light EUV103. The reflective optical member 110 is, for example, a reflective diffraction grating 110a that directly illuminates the inspection target 111 with the illumination light EUV104. A plurality of grooves 20 arranged in a direction orthogonal to the scanning direction are formed on the reflective surface 114 of the reflective diffraction grating 110a.

  Next, as shown in step S13, the light from the inspection region 120 in the inspection object 111 illuminated by the illumination light EUV 104 is collected. Specifically, the diffracted light and reflected light from the rectangular inspection region 120 are collected.

  Next, as shown in step S <b> 14, the image of the inspection object 111 is acquired by scanning the collected light EUV 106 with the direction in which one side of the inspection region 120 extends as the scanning direction.

  Next, the inspection object 111 is inspected based on the acquired image of the inspection object 111. In this way, the inspection object 111 can be inspected using the inspection apparatus 100.

Next, the effect of this embodiment will be described.
In the inspection apparatus 100 of the present embodiment, a reflective diffraction grating 110a is used as the reflective optical member 110 that illuminates the inspection object 111. Thereby, the uniformity of the illumination distribution in the X-axis direction of the inspection region 120 can be improved without adding a mirror used in the illumination optical system. Therefore, inspection sensitivity can be improved.

  Note that the Z-axis direction in the inspection region 120 is a scan direction, and is an integration direction of the TDI operation. For this reason, even if it becomes an illumination intensity distribution with high intensity | strength of a center part, the influence of a sensitivity nonuniformity can be suppressed. In addition, the rate at which the illumination light EUV 104 protrudes from the inspection region 120 can be reduced. Therefore, the utilization efficiency of the illumination light EUV104 can be improved.

  Further, since the total number of mirrors constituting the illumination optical system does not change, an increase in optical loss can be suppressed. Furthermore, since it is not necessary to increase the power of the light source in order to increase the size of the light emitting unit projected onto the inspection surface, an increase in the thermal load on the EUV pellicle 113 can be suppressed.

(Embodiment 2)
Next, an inspection apparatus according to the second embodiment will be described. The inspection apparatus of this embodiment includes a wave multilayer mirror 110b as the reflective optical member 110 instead of the reflective diffraction grating 110a. FIG. 7 is a perspective view illustrating the wave type multilayer mirror 110b of the inspection apparatus according to the second embodiment. As shown in FIG. 7, in the corrugated multilayer mirror 110b, a large number of cylindrical surfaces having a corrugated cross-sectional shape are formed on the reflecting surface 114. Specifically, a cylindrical surface having a curvature of approximately 20 [mm] is arranged in a large number with a pitch of approximately 0.1 [mm] in the X-axis direction. Therefore, the corrugated multilayer mirror 110b is a corrugated multilayer mirror whose cross-sectional shape of the groove 20 is corrugated.

  FIG. 8 is a cross-sectional view illustrating the wave type multilayer mirror 110b of the inspection apparatus according to the second embodiment. As shown in FIG. 8, the wave multilayer mirror 110 b includes a substrate 21 and a multilayer film 22 formed on the substrate 21. The processing method of the corrugated multilayer mirror 110b is as follows. That is, a plurality of cylindrical surfaces arranged in a direction orthogonal to the scanning direction are formed on the main surface of the substrate 21. Thereafter, a multilayer film 22 is formed on the substrate 21. The specularly reflected light of the illumination light EUV103 incident on the wave type multilayer mirror 110b is spread and reflected in a direction orthogonal to the scan direction, for example, the X-axis direction.

  FIG. 9 is a diagram illustrating an illuminance distribution of the illumination light EUV104 using the wave multilayer mirror 110b in the inspection apparatus according to the second embodiment. As shown in FIG. 9, in the inspection region 120 on the inspection surface of the inspection object 111, the illumination distribution of the illumination light EUV 104 is a distribution that spreads in the X-axis direction.

  FIG. 10A illustrates the relationship between the illumination light EUV 103 incident on the wave multilayer mirror 110b and the illumination light EUV 104 reflected by the wave multilayer mirror 110b in the inspection apparatus according to the second embodiment. FIG. 10B illustrates the relationship between the illumination light EUV 103 incident on the convex mirror 25 and the illumination light EUV 104 reflected by the convex mirror 25.

  As shown in FIG. 10 (a), in the inspection apparatus of the present embodiment, by using the wave-type multilayer mirror 110b having a plurality of projections and depressions in the X-axis direction, the inspection surface of the inspection object 111 is aligned in the X-axis direction. An expanded illumination distribution is formed. Therefore, the outer edge of the reflected illumination light EUV 104 spreads and advances, but NA also spreads.

  On the other hand, as shown in FIG. 10B, even if the convex mirror 25 is used, the outer edge portion of the reflected illumination light EUV 104 is expanded, but the reflected and traveling direction is macroscopically in the X-axis direction. It becomes dependent. That is, the NA of the reflected light cannot be expanded even if it is expanded in this way.

  Therefore, in the present embodiment, an illuminance distribution spreading in the X-axis direction can be formed on the inspection surface of the inspection object 111, but the NA distribution is not biased depending on the X-axis coordinates, and a uniform NA distribution is obtained. be able to.

11A to 11C are simulation results illustrating the illuminance distribution on the inspection surface of the inspection object 111 when the shape of the light emitting unit is changed in the inspection apparatus according to the second embodiment.
As shown in FIGS. 11 (a) to 11 (c), the shape of the light-emitting portion was changed in three shapes: a circle (a), a square (b), and a rhombus (c). The illuminance distribution in the region 120 is constant and hardly changes. As described above, in this embodiment, even if the shape of the light emitting unit is slightly changed, the illuminance distribution on the inspection surface does not change and can be made uniform.

  In addition, regarding the Z-axis direction, the illuminance distribution is integrated by the TDI operation. For this reason, even if the illuminance distribution is not uniform, the influence on the inspection sensitivity can be reduced. Therefore, in the present invention, even if the shape of the light emitting part of the EUV light source is unstable, the influence on the inspection sensitivity can be reduced. Also, in this embodiment, since no mirror is added, an increase in optical loss can be suppressed. Other configurations and effects in the second embodiment are included in the description of the first embodiment.

(Embodiment 3)
Next, Embodiment 3 will be described. In the inspection apparatus of the present embodiment, the reflective optical member 110 is a grazing incidence mirror having a corrugated cross-sectional shape of the groove 20. Instead of the oblique incidence mirror 108 of the inspection apparatus 100, an oblique incidence mirror 108b is used. FIG. 12 is a perspective view illustrating an oblique incidence mirror 108b of the inspection apparatus according to the third embodiment.

  As shown in FIG. 12, the oblique incidence mirror 108 b has a plurality of grooves 20 formed in the reflection surface 114. Specifically, the oblique incidence mirror 108 b has a linear unevenness on the reflection surface 114. The plurality of grooves 20 on the reflecting surface 114 of the oblique incidence mirror 108 b are arranged in a direction orthogonal to the scanning direction of the inspection region 120. Thereby, the illuminance distribution on the inspection surface of the inspection object 111 can be expanded in the X-axis direction.

  In this embodiment, the plurality of grooves 20 are formed on the reflecting surface 114 of the oblique incidence mirror 108b on which the illumination light EUV101 is incident. However, the plurality of grooves 20 are formed on the oblique incidence mirror 109b on which the illumination light EUV102 is incident. Also good. Further, a plurality of grooves 20 may be formed in both oblique incidence mirrors 108b and 109b.

  In addition, a multilayer mirror without a groove is used on the reflecting surface of the drop mirror that illuminates the inspection object 111. Note that the reflective optical member 110 of Embodiment 1 or 2 may be used as the drop mirror.

  The oblique incidence mirror 108b and / or 109b includes a substrate and a metal film coated on the main surface of the substrate. The substrate is, for example, quartz, and the metal film is, for example, a ruthenium film. The materials for the substrate and the metal film are not limited to this. The reflection surface 114 of the oblique incidence mirror 108b and / or 109b is a surface coated with a metal film. As a processing method for processing the oblique incidence mirror 108b and / or 109b, for example, the following method can be used.

  FIG. 13 is a plan view illustrating a processing method of the oblique incidence mirror 108b and / or 109b of the inspection apparatus according to the third embodiment. As shown in FIG. 13, first, the main surface of the substrate 21 of the oblique incidence mirror 108 b and / or 109 b is polished using a small-diameter polishing pad 301. When polishing, the polishing is performed while moving the polishing pad 301 in one direction on the main surface of the substrate 21 to form a plurality of grooves arranged in a direction perpendicular to the one direction on the main surface. Specifically, the polishing pad 301 is scanned in the Z-axis direction and stepped in the X-axis direction in small steps. Thereby, it becomes a shape which hits a wave in the X-axis direction.

  Next, a metal film such as Ru is coated on the surface of the polished substrate 21. The surface coated with the metal film becomes the reflecting surface 114. Thereby, a plurality of grooves arranged in the X-axis direction can be formed on the reflecting surface 114.

  Next, the oblique incidence mirrors 108b and / or 109b are arranged so that the formed grooves 20 are arranged in a direction perpendicular to the scanning direction. In other words, the oblique incidence mirror 108b and / or the oblique incidence mirror 109b are arranged so that the plurality of grooves 20 extend in a direction perpendicular to the other side orthogonal to the scanning direction. The other side of the inspection region 120 is, for example, a long side extending in the X-axis direction. Specifically, the oblique incidence mirror 108b and / or the oblique incidence mirror 109b are arranged so that the plurality of grooves 20 extend in a direction perpendicular to the long side of the inspection region 120. In this way, the oblique incidence mirror 108b and / or 109b can be processed. The detector 119 may use the X-axis direction in which the long side of the inspection region 120 extends as the scanning direction, and the extending direction of the plurality of grooves 20 in that case is the same as in the first embodiment.

  According to the oblique incidence mirror 108b and / or 109b of the present embodiment, the illuminance distribution extending in the X-axis direction can be obtained on the inspection surface. The uniformity of the illumination light that illuminates the inspection area can be improved, and the inspection sensitivity can be improved. Further, unlike the case of the second embodiment, by providing the oblique incident mirror 108b with a plurality of grooves 20, even if there are slight uneven steps due to the plurality of grooves 20, the distance to the inspection surface of the inspection object 111 is long. The effect of expanding the distribution in the X-axis direction can be increased. Other configurations and effects are included in the descriptions of the first and second embodiments.

  As mentioned above, although embodiment of this invention was described, this invention contains the appropriate deformation | transformation which does not impair the objective and advantage, Furthermore, it does not receive the restriction | limiting by said embodiment. Moreover, you may combine the structure in Embodiments 1-3 suitably.

10 EUV mask 11 Substrate 12 Multilayer film 13 Absorber 14 Protective film 20 Groove 21 Substrate 22 Multilayer film 25 Convex mirror 100 Inspection device 101 Light source unit 102 Bottle 103 Tin drop 104 Catcher 105 Lens 106 Mirrors 107, 108, 108b, 109, 109b Oblique Incident mirror 110 Reflective optical member 110a Reflective diffraction grating 110b Wave multilayer mirror 111 Inspection target 112 Stage 113 EUV pellicle 114 Reflecting surface 116 Schwarzschild optical system 116a Concave mirror 116b Convex mirror 117 Plane mirror 118 Concave mirror 119 Detector 120 Inspection region 301 Polishing Pad EUV100, EUV101, EUV102, EUV103, EUV104 Illumination light IF Focusing point L100 Near infrared laser light

Claims (15)

A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the condensed light with a direction in which one side of the inspection region extends as a scanning direction;
With
On the reflective surface of the reflective optical member, a plurality of grooves arranged in a direction perpendicular to the scan direction are formed.
Inspection device. A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the condensed light with a direction in which one side of the inspection region extends as a scanning direction;
With
A plurality of grooves extending in a direction perpendicular to the other side orthogonal to the scan direction is formed on the reflective surface of the reflective optical member.
Inspection device. A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the collected light with a direction in which a short side of the inspection region extends as a scanning direction;
With
A plurality of grooves extending in a direction perpendicular to the long side of the inspection region are formed on the reflection surface of the reflective optical member.
Inspection device. A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the collected light as a scan direction in a direction in which a long side of the inspection region extends;
With
A plurality of grooves extending in a direction perpendicular to the short side of the inspection region are formed on the reflection surface of the reflective optical member.
Inspection device. The reflective optical member is a reflective diffraction grating,
The inspection apparatus according to any one of claims 1 to 4. The reflective optical member is a multilayer mirror having a corrugated cross-sectional shape.
The inspection apparatus according to any one of claims 1 to 4. The reflective optical member is an oblique incidence mirror having a corrugated cross-sectional shape.
The inspection apparatus according to any one of claims 1 to 4. Generating illumination light by irradiating laser light onto a drop of a predetermined material to generate plasma; and
Illuminating the inspection object with the illumination light; and
Condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
Scanning the collected light with the direction in which one side of the inspection region extends as a scanning direction, and obtaining an image of the inspection region; and
Inspecting the inspection object using the acquired image;
With
In the step of illuminating the inspection object,
Illuminating the inspection object through a reflective optical member that reflects at least a part of the illumination light,
On the reflective surface of the reflective optical member, a plurality of grooves arranged in a direction perpendicular to the scan direction are formed.
Inspection method. Generating illumination light by irradiating laser light onto a drop of a predetermined material to generate plasma; and
Illuminating the inspection object with the illumination light; and
Condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
Scanning the collected light with the direction in which one side of the inspection region extends as a scanning direction, and obtaining an image of the inspection region; and
Inspecting the inspection object using the acquired image;
With
In the step of illuminating the inspection object,
Illuminating the inspection object through a reflective optical member that reflects at least a part of the illumination light,
A plurality of grooves extending in a direction perpendicular to the other side orthogonal to the scan direction is formed on the reflective surface of the reflective optical member.
Inspection method. Generating illumination light by irradiating laser light onto a drop of a predetermined material to generate plasma; and
Illuminating the inspection object with the illumination light; and
Condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
Acquiring the image of the inspection area by scanning the collected light with a direction in which a short side of the inspection area extends as a scan direction; and
Inspecting the inspection object using the acquired image;
With
In the step of illuminating the inspection object,
Illuminating the inspection object through a reflective optical member that reflects at least a part of the illumination light,
A plurality of grooves extending in a direction perpendicular to the long side of the inspection region are formed on the reflection surface of the reflective optical member.
Inspection method. Generating illumination light by irradiating laser light onto a drop of a predetermined material to generate plasma; and
Illuminating the inspection object with the illumination light; and
Condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
Scanning the collected light with the direction in which the long side of the inspection region extends as a scan direction, and obtaining an image of the inspection region; and
Inspecting the inspection object using the acquired image;
With
In the step of illuminating the inspection object,
Illuminating the inspection object through a reflective optical member that reflects at least a part of the illumination light,
A plurality of grooves extending in a direction perpendicular to the short side of the inspection region are formed on the reflection surface of the reflective optical member.
Inspection method. A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the condensed light with a direction in which one side of the inspection region extends as a scanning direction;
A processing method for the reflective optical member of an inspection apparatus comprising:
The reflective optical member includes a substrate and a metal film coated on the main surface of the substrate,
Polishing while moving a polishing pad in one direction on the main surface of the substrate, and forming a plurality of grooves arranged in a direction perpendicular to the one direction on the main surface;
Coating the metal film on the polished major surface;
Arranging the reflective optical member such that the plurality of grooves are arranged in a direction perpendicular to the scanning direction;
Of processing a reflective optical member including A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the condensed light with a direction in which one side of the inspection region extends as a scanning direction;
A processing method for the reflective optical member of an inspection apparatus comprising:
The reflective optical member includes a substrate and a metal film coated on the main surface of the substrate,
Polishing while moving a polishing pad in one direction on the main surface of the substrate, and forming a plurality of grooves arranged in a direction perpendicular to the one direction on the main surface;
Coating the metal film on the polished major surface;
Disposing the reflective optical member such that the plurality of grooves extend in a direction perpendicular to the other side perpendicular to the scanning direction;
Of processing a reflective optical member including A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the collected light with a direction in which a short side of the inspection region extends as a scanning direction;
A processing method for the reflective optical member of an inspection apparatus comprising:
The reflective optical member includes a substrate and a metal film coated on the main surface of the substrate,
Polishing while moving a polishing pad in one direction on the main surface of the substrate, and forming a plurality of grooves arranged in a direction perpendicular to the one direction on the main surface;
Coating the metal film on the polished major surface;
Disposing the reflective optical member such that the plurality of grooves extend in a direction perpendicular to the long side of the inspection region;
Of processing a reflective optical member including A light source unit that generates illumination light by irradiating a drop of a predetermined material with laser light to generate plasma;
An illumination optical system that includes a reflective optical member that reflects at least a part of the illumination light, and illuminates the inspection object with the illumination light;
A condensing optical system for condensing light from a rectangular inspection region in the inspection object illuminated by the illumination light;
A detector that acquires an image of the inspection region by scanning the collected light as a scan direction in a direction in which a long side of the inspection region extends;
A processing method for the reflective optical member of an inspection apparatus comprising:
The reflective optical member includes a substrate and a metal film coated on the main surface of the substrate,
Polishing while moving a polishing pad in one direction on the main surface of the substrate, and forming a plurality of grooves arranged in a direction perpendicular to the one direction on the main surface;
Coating the metal film on the polished major surface;
Disposing the reflective optical member such that the plurality of grooves extend in a direction perpendicular to a short side of the inspection region;
Of processing a reflective optical member including