JP2019109302A - Illumination optical system, optical inspection device, and optical microscope - Google Patents

Abstract

To provide an illumination optical system that suppresses enables optimal illumination light for a dark field illumination, as suppressing a loss of an amount of light.SOLUTION: An illumination optical system 1, which irradiates an irradiated surface W with illumination light L from a light source 2, includes: a converging optical system 3 that causes the illumination light L from the light source 2 to be converged; an aperture stop 5 that includes a light shield region 5a shielding a center part of a pupil plane of the illumination light L converged by the converging optical system 3, and a light shield region 5b transmitting an exterior peripheral part thereof, and forms annular band-like illumination light L by a light beam transmitting the light shield region 5b; a condenser optical system 6 that irradiates the annular band-like illumination light L formed by the aperture stop 5 toward the irradiated surface W; and a light beam angle control optical system 7 that is arranged in an optical path between the converging optical system 3 and the aperture stop 5, and controls a light beam angle distribution of the illumination light L so that intensity of the light beam at an angle to be incident upon the light shield region 5b, of the illumination light L converged by the converging optical system 3, is maximum.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an illumination optical system, an optical inspection apparatus, and an optical microscope.

  For example, an optical inspection apparatus is generally used to inspect a semiconductor wafer (see, for example, Patent Document 1 below). In the optical inspection apparatus, a semiconductor wafer to be inspected is irradiated with illumination light, an image obtained by the light reflected on the surface of the semiconductor wafer is captured, and the presence or absence of a defect is inspected from this image. . Moreover, also in an optical microscope, illumination light may be irradiated to observation object and the image obtained by the transmitted light or reflected light may be imaged.

  By the way, with the miniaturization of semiconductor devices, the size of defects to be detected is becoming finer. For example, in an optical inspection apparatus, when the defect size is about 10 nm and greatly falls below the diffraction limit of light, the defect signal becomes very weak and detection of the defect becomes difficult.

  In the optical inspection apparatus, as a method of enhancing the detection sensitivity of a defect on a semiconductor wafer, it is effective to enhance the optical resolution to emphasize a defect signal. In general, the optical resolution is improved by increasing the luminance and shortening the wavelength of illumination light to be used, increasing the NA (numerical aperture) of the objective lens, and the like.

  On the other hand, focusing on the illumination method, a dark field illumination method using annular illumination that positively utilizes reflected light and scattered light from the surface to be illuminated is suitable for observation of fine structures. For example, in the dark field illumination method called OAI (Off Axis Illumination), it is put to practical use as an optical technique for improving the detection sensitivity.

  In the dark field illumination method, illumination light of NA larger than the NA of the objective lens to be used is not directly incident on the optical system on the detection side from the outside of the objective lens with respect to the sample to be inspected (surface to be illuminated). Illuminate obliquely and detect the scattered light and diffracted light. However, in the case of the dark field illumination method, using an aperture stop for annular illumination that shields the central portion of the pupil plane of the illumination light and transmits the light of the outer peripheral portion, It forms illumination light. In this case, the light beam (light flux) at the central portion of the illumination light is blocked by the aperture stop, so the loss of light utilization becomes large. For this reason, in the conventional optical inspection apparatus, there is a problem that the light amount necessary for the inspection is insufficient, and the inspection time is increased, thereby reducing the productivity.

JP, 2016-42124, A

One of the aspects of the present invention is proposed in view of such conventional circumstances, and an illumination optical system capable of obtaining illumination light optimum for dark field illumination while suppressing the loss of light quantity. An object of the present invention is to provide an optical inspection apparatus and an optical microscope which can further improve the optical resolution in dark field observation by providing such an illumination optical system.
Intended to provide.

In order to achieve the above object, the present invention provides the following means.
[1] The illumination optical system according to the first aspect of the present invention is an illumination optical system that illuminates illumination light from a light source on a surface to be illuminated, and is a condensing optical system that condenses illumination light from the light source And a light shielding area for shielding the central part of the pupil plane of the illumination light collected by the light collecting optical system, and a light transmitting area for transmitting light on the outer peripheral part, and the light transmitting area is transparent An aperture stop that forms a ring-shaped illumination light by the light beam; a condenser optical system that irradiates the ring-shaped illumination light formed by the aperture stop toward the light receiving surface; the focusing optical system; The illumination light is disposed in the light path between the aperture stop and the illumination light so as to maximize the intensity of the light beam having an angle incident on the light transmission region among the illumination light collected by the light collection optical system And a beam angle control optical system for controlling the beam angle distribution of the Ru.

[2] In the illumination optical system of the above-mentioned [1], the light beam angle control optical system has an opening at the center and a concave first reflecting surface around the opening, A first mirror disposed with the reflection surface of 1 facing the side on which the illumination light is incident, and a convex second reflection surface, and the second reflection surface is opposed to the opening And a second mirror arranged toward the side, and of the illumination light condensed by the condensing optical system, the light ray of the central part is blocked by the second mirror, and the light ray of the outer peripheral part The light reflected by the first reflection surface may be reflected by the second reflection surface to pass the light beam reflected by the second reflection surface from the opening.

[3] In the illumination optical system described in [2], at least one of the first reflection surface and the second reflection surface may be aspheric.

[4] In the illumination optical system according to the above [2] or [3], a holder for accommodating the first mirror and the second mirror, and a translucent support member for supporting the second mirror And may be configured.

[5] In the illumination optical system described in [1], the light beam angle control optical system has a first lens having positive refractive power and negative refractive power in order from the condensing optical system side. It may be configured to include a second lens.

[6] In the illumination optical system according to [5], at least one of the first lens and the second lens may be an aspheric lens.

[7] The illumination optical system according to any one of the above [1] to [6], which is disposed in an optical path between the condensing optical system and the light beam angle control optical system, A collimator lens may be provided to collimate the illumination light collected by the optical system.

[8] The illumination optical system according to any one of the above [1] to [7], which is disposed in the optical path between the light beam angle control optical system and the aperture stop, It may be configured to include an integrator optical system that homogenizes the light that has passed through the system.

[9] An optical inspection apparatus according to a second aspect of the present invention includes the illumination optical system according to any one of the above [1] to [8].

[10] An optical inspection apparatus according to a third aspect of the present invention includes the illumination optical system according to any one of the above [1] to [8].

  As described above, according to the present invention, by providing an illumination optical system capable of obtaining illumination light optimum for dark field illumination while suppressing the loss of light quantity, and by providing such an illumination optical system, It is possible to provide an optical inspection apparatus and an optical microscope which can further improve the optical resolution in dark field observation.

It is a schematic diagram which shows the structure of an optical inspection apparatus provided with the illumination optical system which concerns on one Embodiment of this invention. It is a schematic diagram which shows one structural example of the light ray angle control optical system with which the illumination optical system shown in FIG. 1 is provided. It is sectional drawing which shows the state in which the light beam angle control optical system shown in FIG. 2 was accommodated in the holder. It is a perspective view which shows the structure of the supporting member which supports a 2nd mirror in the holder shown in FIG. It is a graph which shows ray angle distribution in the pupil plane of the illumination light by the presence or absence of a ray angle control optical system. It is a graph which shows the luminance distribution of the illumination light by the presence or absence of a ray angle control optical system. It is sectional drawing which shows another structural example of the light ray angle control optical system with which the illumination optical system shown in FIG. 1 is provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the following description, in order to make each component easy to see, the scale of dimensions may be shown differently depending on the component in the drawings.

As an embodiment of the present invention, an optical inspection apparatus 100 provided with the illumination optical system 1 shown in, for example, FIGS. 1 to 4 will be described.
FIG. 1 is a schematic view showing a configuration of an optical inspection apparatus 100 provided with the illumination optical system 1. FIG. 2 is a schematic view showing a configuration example of a light beam angle control optical system provided in the illumination optical system 1. FIG. 3 is a cross-sectional view showing a state in which the light beam angle control optical system is accommodated in the holder. FIG. 4 is a perspective view showing the configuration of a support member for supporting the second mirror in the holder.

  As shown in FIG. 1, the optical inspection apparatus 100 according to the present embodiment is, for example, a dark field illumination method for detecting the presence or absence of a defect on the surface (irradiated surface) of a semiconductor wafer (hereinafter simply referred to as a wafer) W to be inspected. Is detected by

  In the dark field illumination method, the illumination light L having a larger NA than the NA of the objective lens (not shown) used on the surface of the wafer W is an optical system (not shown) on the detection side from the outside of the objective lens. Illuminate obliquely so as not to be directly incident on the) and detect its scattered light and diffracted light.

  Specifically, the optical inspection apparatus 100 generally includes an illumination optical system 1 that irradiates the illumination light L from the light source 2 on the surface of the wafer W. In the optical inspection apparatus 100 of the present embodiment, an electrodeless lamp having a peak wavelength in the deep ultraviolet region (for example, around 240 nm) is used as the light source 2, but the light source 2 used is adjusted according to the inspection target. It is possible to change suitably.

  In addition to the illumination optical system 1 which is a feature of the present invention, the optical inspection apparatus 100 according to the present embodiment includes a scanning stage scanned in a state in which the wafer W is mounted, and scattering from the surface of the wafer W An objective lens for condensing light and diffracted light, an imaging optical system for forming an image focused by the objective lens, and an imaging device for imaging an image formed by the imaging optical system; Although this is not a feature of the present invention, the description thereof is omitted.

  The illumination optical system 1 of the present embodiment generally includes a condensing optical system 3, an integrator optical system 4, an aperture stop 5, a condenser optical system 6, and a light beam angle control optical system 7. Although the illumination optical system 1 of the present embodiment is configured to include various filters, a field stop, and the like in addition to the above-described configuration, it is not a characteristic part of the present invention, and thus the description thereof is omitted. I assume.

  The condensing optical system 3 includes a reflector 8 that reflects the light L emitted from the light source 2 while reflecting it, and a flat mirror 9 that reflects the light L collected by the reflector 8 at a substantially right angle (90 °) and reflects it. And.

  The reflector 8 is disposed so as to surround the periphery on the back side of the light source 2 and has an inner reflection surface 8 a whose radial cross-sectional shape is formed to draw an elliptical line. The reflector 8 condenses the illumination light L reflected by the inner reflection surface 8 a toward the incident surface 10 a of the rod integrator 10 described later.

  The flat mirror 9 is disposed in front of the light source 2 and reflects the light L collected by the reflector 8 toward the incident surface 10 a of the rod integrator 10. The plane mirror 9 is not necessarily a necessary configuration, and the arrangement of the light source 2 and the reflector 8 is changed, and the light L collected by the reflector 8 is directly incident on the incident surface 10 a of the rod integrator 10 Can be omitted.

  The integrator optical system 4 has a rod integrator 10 that makes the illumination light L collected by the light collection optical system 3 uniform. The rod integrator 10 is formed of a rectangular parallelepiped light guide (rod lens), and one end in the longitudinal direction is the incident surface 10a, and the other end in the longitudinal direction is the emission surface 10b. The rod integrator 10 receives the illumination light L condensed by the condensing optical system 3 from the incident surface 10a, guides the illumination light L while repeating reflection internally, and then emits the illumination light L from the emission surface 10b.

  The aperture stop 5 includes a first light shielding area 5a for shielding the central portion of the pupil plane of the illumination light L emitted from the emission surface 10b of the rod integrator 10, and a light transmitting area 5b for transmitting the outer peripheral portion. And a second light shielding region 5c that shields the outer peripheral portion thereof, and a light beam transmitted through the light transmitting region 5b forms illumination light L in the shape of a ring (ring).

  The condenser optical system 6 has a first condenser lens group 6 a and a second condenser lens group 6 b arranged in the optical axis direction. The aperture stop 5 is disposed between the first condenser lens group 6a and the second condenser lens group 6b. The condenser optical system 6 irradiates the ring-shaped illumination light L formed by the aperture stop 5 toward the surface of the wafer W while condensing the light.

  More specifically, the light beam angle control optical system 7 includes the flat mirror 9 (the light collecting optical system 3) and the rod integrator 10 (the integrator optical system 4) in the light path between the light collecting optical system 3 and the aperture stop 5. In the light path between The light beam angle control optical system 7 controls the illumination light L so that the intensity of the light beam of the angle incident on the light transmitting area 5 b of the aperture stop 5 is the largest among the illumination light L condensed by the condensing optical system 3. Control the ray angle distribution of

  Specifically, as shown in FIG. 2, the light beam angle control optical system 7 includes a collimator lens 11, a first mirror 12, and a second mirror 13. In the light beam angle control optical system 7, the collimator lens 11, the second mirror 13 and the first mirror 12 are arranged side by side on the optical axis in order from the side of the condensing optical system 3.

  The collimator lens 11 is a spherical lens that is concave on both sides, and collimates the illumination light L collected by the light collection optical system 3. The first mirror 12 has a circular opening 12a at the center and a concave first reflecting surface 12b around the opening 12a, and the illumination light L is irradiated to the first reflecting surface 12b. It is arranged toward the incident side. The second mirror 13 has a convex second reflecting surface 13a having an outer diameter smaller than that of the first reflecting surface 12b, and directs the second reflecting surface 13a to the side facing the opening 12a. It is arranged.

  In the present embodiment, the first reflecting surface 12b and the second reflecting surface 13a are aspheric. Thereby, the illumination light L condensed by the condensing optical system 3 can be efficiently incident on the incident surface 10 a of the rod integrator 10. In addition, about the 1st reflective surface 12b and the 2nd reflective surface 13a, at least one should just be an aspherical surface, and it is also possible to make either one a spherical surface.

  The light beam angle control optical system 7 constitutes one optical unit 15 by accommodating the collimator lens 11, the first mirror 12 and the second mirror 13 inside the holder 14 as shown in FIG. doing.

  The holder 14 is made of, for example, a metal member excellent in heat dissipation, such as stainless steel (SUS), and is formed in a substantially cylindrical shape as a whole. Inside the holder 14, a lens holding unit 14 a holding the collimator lens 11, a first mirror holding unit 14 b holding the first mirror 12, and a second mirror holding unit holding the second mirror 13 14c are provided. Among these, the second mirror 13 is held inside the holder 14 via a support member 16 that supports the outer peripheral portion of the second mirror 13.

  As shown in FIG. 4, the support member 16 is made of a translucent base material such as synthetic quartz, for example, and from the inner side of the outer peripheral ring portion 16a held by the second mirror holding portion 14c and the outer peripheral ring portion 16a. And a plurality of (three in the present embodiment) spoke portions 16b extending radially.

  The plurality of spokes 16b are arranged at equal intervals in the circumferential direction of the outer peripheral ring 16a, and the tips of the plurality of spokes 16b are brought into contact with the outer periphery of the second mirror 13 It supports the outer periphery.

  In the optical unit 15, the second mirror 13 is placed on the central portion in the holder 14 by the plurality of spokes 16 b arranged radially between the outer periphery of the second mirror 13 and the inner periphery of the holder 14. It is possible to hold it in a floating state.

  Further, in the optical unit 15, since the plurality of spokes 16 b have translucency, it is possible to guide the light beam passing through the outside of the second mirror 13 toward the first mirror 12 without blocking it. It is. Thereby, it is possible to suppress the occurrence of unevenness in the ray angle distribution of the illumination light L.

  Furthermore, in the optical unit 15, by supporting the plurality of spokes 16 b in contact with the outer circumferential portion of the second mirror 13, the influence of heat applied to the second mirror 13 can be reduced. As a result, it is possible to suppress the deterioration of the light beam angle distribution and the like accompanying the thermal deformation of the second mirror 13 of the illumination light L reflected by the second reflection surface 13a.

  The support member 16 is not necessarily limited to the configuration in which the outer peripheral portion of the second mirror 13 is supported by the plurality of spokes 16 b described above, and the configuration can be appropriately changed. For example, the second mirror 13 is a holder by the inner peripheral ring holding the outer peripheral part of the second mirror 13 and at least one or more spokes connecting the inner peripheral ring and the outer peripheral ring. It is also possible to hold it in a floating state in the central part in 14.

  In the light beam angle control optical system 7, as shown in FIG. 2 and FIG. 3, of the illumination light L collected by the light collection optical system 3, a light ray at the central portion thereof (a light ray angle Light) is blocked by the second mirror 13, and the light beam of the outer peripheral portion (light of light beam angle which becomes high NA of the illumination light L) is transmitted from the outside of the second mirror 13 toward the first mirror 12 Let The light beam that has passed through the outside of the second mirror 13 is reflected by the first reflection surface 12 b and then reflected by the second reflection surface 13 a, thereby passing through the opening 12 a, while It will inject into the entrance plane 10a.

  In the illumination optical system 1 of the present embodiment, of the illumination light L condensed by the light collection optical system 3 by such a light beam angle control optical system 7, the angle of incidence to the light transmitting region 5 b of the aperture stop 5 The ray angle distribution of the illumination light L is controlled so as to maximize the light ray intensity.

  Here, FIG. 5 shows a ray angle distribution on the pupil plane of the illumination light L incident on the incident surface 10 a of the rod integrator 10. In the graph shown in FIG. 5, the ray angle distribution on the pupil plane of the illumination light L in the absence of the ray angle control optical system 7 is indicated by an alternate long and short dashed line, and the pupil of the illumination light L in the presence of the ray angle control optical system 7 The ray angle distribution in the plane is shown by a solid line. Further, the range of the angle of the light beam incident on the light transmitting region 5b of the aperture stop 5 is indicated by a broken line.

  As shown in FIG. 5, when the ray angle control optical system 7 is not provided, in the ray angle distribution of the illumination light L on the pupil plane, the light amount at the central portion to be the shadow of the light source 2 becomes the smallest, The light quantity on the circumferential side is the highest, and the light intensity gradually decreases from there toward the outer circumferential side. In this case, the light beam intensity is maximum at an angle smaller than the angle of incidence on the light-transmissive area 5 b of the aperture stop 5.

  On the other hand, in the case of the light beam angle control optical system 7, in the light beam angle distribution on the pupil plane of the illumination light L, the light beam intensity of the angle incident on the light transmitting region 5b of the aperture stop 5 is maximum. That is, in the illumination optical system 1 of the present embodiment, by providing the light beam angle control optical system 7, the intensity of the light beam of the angle incident on the light transmitting region 5b of the aperture stop 5 is maximized. It is possible to control the ray angle distribution of the illumination light L incident on the incident surface 10a.

  Further, the luminance distribution of the illumination light L which has passed through the aperture stop 5 is shown in FIG. In the graph shown in FIG. 6, the luminance distribution of the illumination light L without the light beam angle control optical system 7 is indicated by a dashed dotted line, and the luminance distribution of the illumination light L with the light beam angle control optical system 7 is indicated by a solid line. It shows.

  As shown in FIG. 6, when the light beam angle control optical system 7 is provided, the light amount of the illumination light L passing through the aperture stop 5 is increased by about 1.4 times as compared with the case where the light beam angle control optical system 7 is not provided. You can see that Therefore, in the illumination optical system 1 of the present embodiment, by providing the light beam angle control optical system 7, it is possible to improve the luminance of the illumination light L irradiated to the wafer W.

  As described above, in the illumination optical system 1 of the present embodiment, the above-described light beam angle control optical system 7 suppresses the light amount loss of the illumination light L irradiated to the wafer W, and the illumination light L optimum for dark field illumination It is possible to get

  In the present embodiment, it is also possible to use a light beam angle control optical system 7A as shown in FIG. 7, for example, instead of the light beam angle control optical system 7. Specifically, the light beam angle control optical system 7A includes, in order from the side of the condensing optical system 3, the collimator lens 11, the first lens 17 having a positive refractive power, and the second lens having a negative refractive power. 18 is arranged.

  In the present embodiment, the first lens 17 and the second lens 18 are aspheric lenses. Thereby, the illumination light L condensed by the condensing optical system 3 can be efficiently incident on the incident surface 10 a of the rod integrator 10.

  The first lens 17 and the second lens 18 may be at least one aspheric lens, and one of them may be a spherical lens. In that case, the light beam angle control optical system 7A is not limited to the configuration including the two lens groups of the first and second lenses 17 and 18 described above, and may be configured to include three or more lens groups.

  The light beam angle control optical system 7A constitutes one optical unit 15A by accommodating the first lens 17 and the second lens 18 inside the holder 14A. Inside the holder 14A, a first lens holding portion 14d for holding the first lens 17 and a second lens holding portion 14e for holding the second lens 18 are provided.

  In the illumination optical system 1 of the present embodiment, by providing such a light beam angle control optical system 7A, it is possible to obtain the same effect as the case where the light beam angle control optical system 7 is provided. That is, in the illumination optical system 1 of the present embodiment, it is possible to obtain the illumination light L optimum for dark field illumination while suppressing the light amount loss of the illumination light L irradiated to the wafer W by the light beam angle control optical system 7A. It is possible.

In addition, this invention is not necessarily limited to the thing of the said embodiment, It is possible to add a various change in the range which does not deviate from the meaning of this invention.
For example, in the illumination optical system 1, the collimator lens 11 is integrally disposed in the above-described light beam angle control optical system 7 or 7A (optical unit 15 or 15A). The angle control optical systems 7 and 7A (optical units 15 and 15A) may be separately provided. When the illumination light L incident on the light beam angle control optical systems 7 and 7A is collimated on the side of the above-described light collecting optical system 3, the collimator lens 11 can be omitted.

  In the above embodiment, the case where the wafer W is inspected in the optical inspection apparatus 100 including the illumination optical system 1 has been illustrated, but it is sufficient that the inspection can be performed by the optical inspection apparatus 100. Is not particularly limited.

  In addition to the optical inspection apparatus 100, the illumination optical system 1 according to the present embodiment irradiates the illumination light L to the observation target, and picks up (observes) an image obtained by the transmitted light or the reflected light. It is possible to apply to And, with an optical microscope equipped with such an illumination optical system 1, it is possible to obtain the illumination light L optimum for dark-field illumination while suppressing the light quantity loss of the illumination light L, so observation with high resolution is possible. It becomes possible.

  DESCRIPTION OF SYMBOLS 1 ... illumination optical system 2 ... light source 3 ... condensing optical system 4 ... integrator optical system 5 ... aperture stop 5a ... 1st light-shielding area 5b ... light transmission area 5c ... 2nd light-shielding area 6 ... condenser optical system 7, 7A ... Beam angle control optical system 8 ... Reflector 9 ... Planar mirror 10 ... Rod integrator 11 ... Collimator lens 12 ... First mirror 12a ... Opening 12b ... First reflection surface 13 ... Second mirror 13a ... Second reflection Surface 14, 14A: Holder 15, 15A: Optical unit 16: Support member 16a: Outer peripheral ring 16b: Spoke 17: First lens 18: Second lens 100: Optical inspection device L: Illumination light

Claims (10)

An illumination optical system for illuminating illumination light from a light source onto a surface to be illuminated,
A condensing optical system that condenses illumination light from the light source;
Of the pupil plane of the illumination light collected by the light collection optical system, it includes a light shielding region that shields the central portion of the illumination light and a light transmitting region that transmits the outer peripheral portion, and transmits the light transmitting region An aperture stop that forms a ring-shaped illumination light by a light beam;
A condenser optical system which irradiates the ring-shaped illumination light formed by the aperture stop toward the light receiving surface;
In the light path between the condensing optical system and the aperture stop, among the illumination light condensed by the condensing optical system, the intensity of the light beam at an angle incident on the light transmitting region is maximized. And a light beam angle control optical system for controlling a light beam angle distribution of the illumination light. The light beam angle control optical system has an opening at the center and a concave first reflecting surface around the opening, and the first reflecting surface is on the side where the illumination light is incident. A first mirror placed facing the
And a second mirror having a convex second reflecting surface, the second mirror being disposed to face the opening.
Of the illumination light condensed by the condensing optical system, the light ray of the central portion is blocked by the second mirror, and the light ray of the outer peripheral portion is reflected by the first reflection surface, and then the second light is reflected. The illumination optical system according to claim 1, wherein the light beam reflected by the second reflection surface from the opening is transmitted by being reflected by the reflection surface.   The illumination optical system according to claim 2, wherein at least one of the first reflection surface and the second reflection surface is an aspheric surface. A holder for housing the first mirror and the second mirror;
4. The illumination optical system according to claim 2, further comprising: a translucent support member for supporting the second mirror.   The light beam angle control optical system includes a first lens having positive refractive power and a second lens having negative refractive power in order from the condensing optical system side. The illumination optical system described in.   The illumination optical system according to claim 5, wherein at least one of the first lens and the second lens is an aspheric lens.   A collimator lens is disposed in an optical path between the condensing optical system and the light beam angle control optical system, and is provided with a collimator lens for collimating the illumination light condensed by the condensing optical system. The illumination optical system as described in any one of 1-6.   The optical system according to any one of claims 1 to 7, further comprising: an integrator optical system disposed in a light path between the light beam angle control optical system and the aperture stop to make the light passing through the light beam angle control optical system uniform. The illumination optical system according to any one of the above.   An optical inspection apparatus comprising the illumination optical system according to any one of claims 1 to 8.   An optical microscope comprising the illumination optical system according to any one of claims 1 to 8.

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