JP2001330565A - Surface inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface inspection device capable of preventing entering of unnecessary diffracted light from an inspection object into a light-receiving optical system by a simple formation, and detecting foreign matter or the like quickly, accurately and highly precisely. SOLUTION: This inspection device has an illumination optical system 3, 4, 5, 6 for illuminating the nearly whole surface of the inspection object 7 at a prescribed angle with the inspection object 7, and the light-receiving optical system 8, 9, 10, 11 for receiving scattered light from the foreign matter adhering on the surface of the inspection object 7. The illumination optical system 3, 4, 5, 6 comprises three or more groups of optical elements 3, 4, 5 having refracting power at least in a first plane including an optical axis of the illumination optical system, and an optical element 6 having refracting power in a second plane intersecting orthogonally at least with the first plane and including the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface inspection apparatus for detecting foreign matter adhering to the surface of an object to be inspected having a fine pattern formed on the surface, and more particularly to a surface inspection apparatus suitable for inspecting the surface of a semiconductor wafer or a liquid crystal substrate. The present invention relates to a surface inspection device.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor wafer or a liquid crystal display substrate, foreign matter such as dust is attached by etching or CVD.
(Chemical Vapor Deposition) is an obstacle to performing a process of forming a correct circuit pattern. Therefore, at the stage where the pattern is printed on the resist by an exposure device or the like and developed, it is general practice to inspect the printed pattern for abnormalities or foreign matter. Conventionally, this type of inspection has been performed by irradiating a light beam from an illumination optical system onto an object to be inspected and visually observing it by an inspector, as disclosed in, for example, Japanese Patent Application Laid-Open No. H5-232032. here,
Irradiation of light to a fine circuit pattern at the time of inspection of foreign matter generates diffracted light. For this reason, it has been difficult to distinguish scattered light from a foreign substance from diffracted light from a circuit pattern. In addition, to inspect pattern abnormalities using diffracted light,
Inspection standards were unstable due to the influence of inspector skill and fatigue. Japanese Patent Application Laid-Open No. Hei 7-27709 proposes that the illumination can be optimized between the time of detecting a foreign substance and the time of detecting a pattern abnormality, and that an inspection independent of individual differences among inspectors can be performed by applying image processing technology. A method for doing so is disclosed. Here, for detecting foreign matter on the surface of the test object, illumination light from a light source is introduced into a light guide fiber to form a linear secondary light source. Then, the light from the linear secondary light source is transmitted through the condenser lens, and the light flux in the plane direction where the illumination light is incident is made substantially parallel light flux. Thereafter, the entire surface of the wafer is irradiated at an incident angle close to 90 degrees. The scattered light from the foreign matter on the wafer is received by a light receiving optical system provided above the wafer, and the foreign matter is detected.

[0003]

In the above-described prior art apparatus configuration, the illumination light is reduced to approximately 90 in order to minimize the light entering the surface of the test object and to detect the scattered light from the foreign substance with the highest possible contrast. The object is illuminated at an incident angle of degrees. Therefore, when the wavelength of the illumination light is substantially equal to the pattern pitch of the test object, the diffracted light travels in a direction substantially perpendicular to the surface of the test object and enters the light receiving optical system. The amount of diffracted light from the circuit pattern is much larger than the amount of scattered light from foreign matter. For this reason, there is a problem that if the diffracted light enters the light receiving optical system of the surface inspection device, the foreign substance cannot be detected. In particular, JP-A-7-2
As disclosed in Japanese Patent No. 7709, when illumination light is irradiated from all around the object to be inspected, diffracted light is always incident on the light receiving optical system. Will be gone.

The present invention has been made in view of the above problems, and can prevent unnecessary diffracted light from a test object from being incident on a light receiving optical system with a simple configuration. It is an object of the present invention to provide a surface inspection device capable of detecting with high accuracy.

[0005]

In order to solve the above problems, the present invention provides an illumination optical system for illuminating substantially the entire surface of a test object at a predetermined angle with respect to the test object; A light receiving optical system for receiving scattered light from a foreign substance attached to the surface, wherein the illumination optical system has three or more groups having a refractive power in at least a first plane including an optical axis of the illumination optical system. There is provided a surface inspection apparatus comprising: an optical element; and an optical element having a refractive power in a second plane orthogonal to the first plane and including the optical axis. Here, the “refractive power” refers to a value including the reciprocal of the focal length of the reflection system in addition to the reciprocal of the focal length of the transmission (refraction) system such as a lens or a refracting surface. Further, the “optical element” also includes a transmission (refraction) optical element and a reflection type optical element.

In actual circuit elements and liquid crystal display elements, the elements to be manufactured are arranged in an orderly manner, so that the direction in which diffracted light is generated is limited. That is, when the test object is rotated in the horizontal plane, the direction of the diffracted light changes, so that a condition under which the diffracted light does not enter the light receiving optical system can be selected. According to the above configuration of the present invention, since the incident angle range of the light beam illuminating the test object can be limited to a narrow range, the incident azimuth of the light beam illuminating the surface of the test object and the pattern of the pattern formed on the test object are determined. It is possible to easily find a condition in which the repeated azimuth is not relatively matched, that is, an azimuth condition in which the diffracted light does not enter the light receiving optical system.

[0007] Further, since the image due to the scattered light from the surface of the test object is collectively converted into an image signal by the image sensor, diffracted light from the surface of the test object is prevented from entering the entire test object as described above. It is necessary to satisfy various conditions.
Therefore, in the present invention, the so-called telecentric illumination method is used so that the light flux illuminating each point on the test object is substantially parallel with the above-described configuration. Illuminating the point.

In a preferred aspect, the light receiving optical system has an image pickup device, and a wavelength selection element for selecting light having a specific wavelength is provided on the illumination optical system side of the image pickup device. Is desirable.

If the wavelength of the illumination light is different, the diffraction angle from the pattern is different. Therefore, by selecting or limiting the wavelength of the illumination light, it is possible to prevent the diffracted light from being mixed into the image pickup device of the light receiving optical system. . In other words, even when diffracted light at a certain wavelength Anm enters the light receiving optical system, another wavelength Bn
In the case of m, it is possible to prevent diffracted light from entering the image pickup device of the light receiving optical system. According to the present invention, by providing the wavelength selection element, it is possible to prevent the diffracted light from entering the image pickup element of the light receiving optical system. It is desirable to provide a member for selecting the wavelength of the received light, such as a filter, between the light source unit that supplies the illumination light and the image sensor.

In the present invention, an illumination optical system for illuminating substantially the entire surface of the test object at a predetermined angle with respect to the test object, and receiving scattered light from a foreign substance attached to the surface of the test object. A light receiving optical system, the light receiving optical system further includes a light receiving element unit, and a wavelength selection element for selecting light of a specific wavelength is provided closer to the illumination optical system than the image pickup element unit. And a surface inspection apparatus characterized by the following.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, by using an optical element such as a cylindrical lens which is not rotated with respect to the optical axis, an optical system for illuminating an object to be inspected in a longitudinal direction and a lateral direction of an illuminating light beam is used. The structure is changed. In order to illuminate the longitudinal direction of the illumination light beam, the light beam from the light source or the secondary light source needs to be approximately the length of the illumination light beam in the longitudinal direction. I need. In contrast,
In the short direction of the illumination light beam, the condenser lens or the condenser mirror does not need to have a long focal length. Rather, it is better to have a short focal length in order to effectively irradiate the light from the light source to the test object. Therefore, a short-side relay optical system is constituted by a cylindrical lens or a cylindrical mirror having no refractive power in the longitudinal direction of the illumination. Then, the light source or the secondary light source is arranged so as to be near the pupil plane or the pupil conjugate plane of the illumination optical system in both the longitudinal direction and the lateral direction of the illumination light beam. With this configuration, the center of the light beam to be illuminated at any point on the surface of the test object such as a wafer has a constant incident angle, and the angle range in which the illumination light beam enters can fall within the constant angle range. The mechanism for switching the wavelength of light has a configuration in which a color glass filter, an interference filter, or the like can be inserted into or removed from the illumination optical system or the light receiving optical system. With this configuration, the wavelength to be received may be limited, or a light source unit may include a dispersive element such as a diffraction grating to illuminate at a specific wavelength. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a diagram showing a configuration of a surface inspection apparatus according to a first embodiment. Light from an incandescent light bulb such as a halogen lamp, or a discharge light source 1 such as a mercury lamp or a metal halide lamp is collected and introduced into the light guide fiber 2. The light guide fiber 2 is a bundle of optical fibers randomly bundled, and the output end serves as a secondary light source having a relatively uniform luminous intensity. The illumination light emitted from the emission end of the fiber 2 is
A first cylindrical lens 3, a second cylindrical lens 4, a third cylindrical lens 5, and the first to third cylindrical lenses 3, 4,
A test object 7 such as a wafer or a liquid crystal substrate is illuminated at a predetermined angle via a fourth cylindrical lens 6 having a refractive power in a direction orthogonal to 5. At this time, the first to third cylindrical lenses 3 to 5
Are arranged so as to have a refracting power in a plane where the illumination light beam is obliquely incident. On the other hand, the fourth cylindrical lens 6 has a refractive power in a plane perpendicular to the plane on which the illumination light beam obliquely enters, and is arranged so as to illuminate the entire surface of the test object 7. FIG.
2A is a top view of the illumination optical system, and FIG. 2B is a side view. Returning to FIG. 1, the object to be inspected 7 has its surface normal set to the axis AX.
The holder 13 is rotatable. Then, foreign substances or scratches attached to the surface of the test object 7 scatter the illumination light. A part of the scattered light is condensed by a light receiving optical system 8 provided substantially vertically above the object 7 to be inspected, and is passed through an aperture stop 9 and an imaging optical system 10 onto an image sensor 11. 7 is formed by the scattered light. Image sensor 1
1 photoelectrically converts the scattered light to obtain a foreign substance signal. The signal processing system 12 determines whether there is a foreign substance on the test object 7.

The test object 7 has a radius R like a semiconductor wafer.
When the incident angle of the illumination light is θ, the illumination light flux has an elliptical shape having a diameter of 2R in the longitudinal direction and 2Rcos θ in the lateral direction. For example, when illuminating a 200 mmφ semiconductor wafer at an incident angle of 85 °, the longitudinal direction is 2 mm.
It becomes an elliptical light beam of about 17.4 mm in the short direction of 00 mm. When the incident angle is large as described above, a necessary light beam becomes a very flat ellipse. In order to illuminate so that the incident angle of the illumination light beam is within a predetermined range at any point in such a flat elliptical region, it is necessary to arrange a light source or a secondary light source near the front focal position of the condenser lens. There is. However, in the case of a condenser lens that is made to have a normal rotational symmetry, when illuminating the flat illumination area as described above, light is also emitted to the outside of the illumination area, and the illumination is not effectively performed.

Therefore, the light beam in the short side direction is transmitted through the cylindrical lenses 3 to 3.
By using the relay 5, the emission end from the fiber 2 as the secondary light source is configured to coincide with the front focal position of the combined optical system. At this time, the focal lengths of the cylindrical lenses 3 to 5 are f ₁ , f ₂ , and f ₃ , respectively, the distance between the light source and the principal plane of the cylindrical lens 3 is e ₀ , the distance between the principal planes of the cylindrical lenses 3 and 4 is e ₁ , The distance between the principal planes of the cylindrical lenses 4 and 5 is e ₂ , the distance between the principal plane of the cylindrical lens 5 and the center of the test object 7 is e ₃ , and the composite focal length of the cylindrical lenses 3 to 5 is F.
Then, the following equation must be satisfied.

[0015]

(Equation 1)

Further, since the fourth cylindrical lens 6 has a refracting power in the longitudinal direction of the illumination light beam, a relatively long focal length is required. If the focal length is f ₀ , the exit end of the fiber 2 and the fourth cylindrical lens 6 The distance between the principal planes of the lens is equal to f ₀ ,
It is also desirable that the distance between the main plane of the fourth cylindrical lens 6 and the center of the test object 7 is equal to f ₀ . Therefore, the distance between the emission end of the fiber 2 and the test object 7 is approximately 2f ₀ . That is, in the short-side optical systems 3 to 5, it is necessary to further satisfy the following expression. 2f ₀ = e ₁ + e ₂ + e ₃

Since the object 7 is illuminated obliquely, the working distance between the center of the object 7 and the optical systems 3 to 6 needs to be large enough. Table 1 shows examples of these numerical values. However, since the combined focal length F is converged after the image is formed once and the light source image is inverted, the sign is inverted and takes a negative value.

[0018]

Table 1 e ₀ 18 mm f ₁ 18 mm e ₁ 3.6 mm f ₂ 72 mm e ₂ 192 mm f ₃ 120 mm e ₃ 360 mm F- ₃₀ mm Total length 573.6 mm f ₀ 286.8 mm

Next, as a modification of the first embodiment, an example in which the third cylindrical lens and the fourth cylindrical lens are collectively replaced by one spherical lens 20 will be described. FIG. 3 is a perspective view of this modification. FIG. 4A is a top view of the illumination optical system of the present modified example, and FIG. 4B is a side view. In the case of this modification, the focal length f ₃ of the _third cylindrical lens is equal to the focal length f ₀ of the fourth cylindrical lens, and the distance e ₃ between the principal plane of the spherical lens 20 and the test object 7 is also the fourth. Is equal to the focal length f ₀ of the cylindrical lens of For this reason, the following conditions are added. f ₀ = f ₃ = e ₃ Table 2 shows a numerical example of this modification.

[0020]

TABLE 2 _{e 0 22mm f 1 19.6mm e 1} 110mm f 2 101.5385mm e 2 240mm f 3 360mm e 3 360mm F -30mm total length 720 mm f ₀ 360 mm

Further, as another modified example of the first embodiment, an example in which a reflecting mirror 30 is used instead of the third cylindrical lens and the fourth cylindrical lens will be described. FIG. 5A is a schematic diagram viewed from the side, and FIG. 5B is a diagram illustrating the reflecting mirror 30 viewed from above the apparatus. In the case of a reflecting mirror, it can be processed relatively freely by grinding a curved surface. For this reason, it is relatively easy to change the curvature of the curved surface in the orthogonal direction, and the distance e ₃ between the main plane of the reflecting mirror 30 and the test object 7 is set equal to the focal length f _{0 in} the longitudinal direction of the illumination area. ₀ = it is possible to design with the proviso that e ₃ increases the degree of freedom.

[0022]

TABLE 3 _{e 0 22.5mm f 1 19.15385mm e 1} 207.5mm f 2 276.6667mm e 2 130mm f 3 240mm e 3 360mm F -30mm total length 720 mm f ₀ 360 mm

Since the radius of curvature of the spherical concave mirror can be determined from being twice the focal length, the radius of curvature of the concave mirror in the longitudinal direction of the illumination light beam is 720 mm, and the radius of curvature of the concave mirror in the short direction of the illumination light beam is That is, 360 mm. Further, in the case of a reflecting mirror, the concave surface can be a parabolic surface instead of a spherical surface, so that it is possible to further optimize the concave surface. In particular, since a wide range is illuminated in the longitudinal direction, the peripheral light beam is excessively bent in the optical axis direction under the influence of the spherical aberration in the spherical reflecting mirror, and it is difficult to produce a parallel light beam. Therefore, by making the reflecting surface a parabolic surface, the luminous flux can be made parallel even in the periphery. Taking the z-axis in the optical axis direction of the paraboloid with the center of the paraboloid as the origin and taking the x-axis and the y-axis orthogonal to the direction perpendicular thereto, the rotating paraboloid is given by the following equation. Indicated by z = a (x ² + y ² )

The focal length of this paraboloid of revolution is 1 / (4
a). In the above numerical examples (Tables 2 and 3), since the focal length in the longitudinal direction of the illumination light beam is 360 mm, the coefficient a of the reflection surface in the longitudinal direction of the illumination light beam is 1/1440 (≒
0.00694). However, since a reflecting surface is used, the optical axis cannot be formed as a straight line, and the mounting accuracy may be stricter than that of a lens. Such a configuration may use not only a reflecting mirror but also a so-called toric lens having a curved surface that is not a rotation object with respect to the optical axis. By using the illumination as described above, each point on the test object can be illuminated with illumination light that is substantially parallel and has a constant incident angle range. Therefore, even when there is a pattern on the test object 7 with a pitch such that the diffracted light enters the light receiving optical system, the test object 7 is rotated to change the traveling direction of the diffracted light to a direction in which the light receiving optical system does not exist. Thus, a foreign substance inspection can be performed. Thus, by receiving the scattered light from the scratch, the scratch attached to the test object 7 can be easily detected.

However, since the intensity of the scattered light due to the scratch varies depending on the illuminating direction, the holder 13 on which the test object 7 is mounted is rotated so that the diffracted light from the pattern does not enter the light receiving optical system 8 as much as possible. It is desirable to receive and inspect in many directions. The present invention is not limited to this, and instead of rotating the test object 7, the illumination optical systems 3 to 6 may be rotated to change the illumination direction. Further, in the above-described embodiment, an example in which a lens (refractive optical system) is used for the light receiving optical system 8 has been described, but it goes without saying that a reflecting mirror (reflective optical system) may be used.

(Second Embodiment) Next, a second embodiment of the present invention will be described. It is assumed that the test object having the pattern of the pitch p is irradiated with the illumination light in the incident angle range of θ1 to θ2, and the light receiving optical system having the light receiving angle of the scattered light from the foreign matter of φ1 to φ2 is received. At this time, in order for the diffracted light from the pattern not to enter the light receiving optical system, the following conditional expression must be satisfied.

[0027]

(Equation 2)

Here, λ is the illumination wavelength, and n is an integer.
Further, in the case of θ1 <θ2 and φ1 <φ2, the incident angle and the light receiving angle are indicated by the angle of deflection from the normal direction of the surface of the test object as 0 degree. That is, by selecting the illumination wavelength λ in accordance with the pattern pitch p, it is possible to satisfy the condition that the light diffracted light from the pattern does not enter the light receiving optical system.

FIG. 6 is a diagram showing a configuration near the light source unit of the surface inspection apparatus according to the present embodiment. In this embodiment,
The difference from the first embodiment is that a wavelength switching mechanism is provided in the light source unit. The other configuration is the same as that of the first embodiment, and the description is omitted. The luminous flux from the light source 1 such as a halogen lamp is applied to a converging lens 102 and a wavelength limiting filter 10 mounted on a turret 103.
4. The light is introduced into the light guide fiber 2 via the input lens 105. Then, the illumination light is applied to the test object 7 via the above-described illumination optical systems 3 to 6, and the inspection using the scattered light is performed in the above-described procedure. Turret 103
Has a plurality of filters having different limiting wavelengths.
Then, according to a signal from a control system (not shown), the motor M
Is driven to rotate the turret 103. Thereby, a wavelength limiting filter to be inserted into the optical path of the light beam from the light source 1 can be selected. As the wavelength limiting filter, an interference filter, a color glass filter, or the like can be used.

As a modification of the second embodiment, if the wavelength is selected in the light source section, the wavelength can be selected by using a spectral element 106 such as a diffraction grating or a prism as shown in FIG. Good.

Next, another modified example of the second embodiment will be described. The test object 7 having the pattern of the pitch p can be regarded as a diffraction grating. For this reason, the diffraction angle φn of the n-th order diffracted light according to the wavelength λ of the illumination light can be expressed by the following equation, where θ is the incident angle of the illumination light. sinφn = sin θ−nλ / p When the light receiving angle of the light receiving optical system 8 matches the diffraction angle of the pattern, a filter 107 that does not transmit light of that wavelength is inserted into the optical path as shown in FIG. Thereby, the diffracted light from the pattern does not enter the image sensor 11. On the other hand, the scattered light transmitted through the filter enters the light receiving optical system 8 and is detected by the image pickup device 11 because the disturbing light from the foreign matter and the scratches spreads almost isotropically. Filter 10
7 is a turret 1 which can be rotated similarly to the one shown in FIG.
08, and can be selected as necessary, as described above.

The present invention is not limited to the configurations of the above embodiments. An actual circuit pattern formed on a substrate such as a wafer has a complicated shape, and circuit elements are not always formed at a uniform pitch over the entire surface. Therefore, by using the illumination optical system capable of performing telecentric flat illumination as shown in the first embodiment and the wavelength selection filter shown in the second embodiment in combination, it is possible to further effectively eliminate unnecessary illumination. It is possible to prevent the diffracted light from entering the image sensor. In addition, an example has been described in which the rotation amount of the test object in the first embodiment and the illumination wavelength band in the second embodiment are set and used in advance so as not to enter the light receiving optical system. However, the present invention is not limited to this. When a periodic signal corresponding to the repetition period of the exposure pattern exists in the scattered light image of the test object obtained by the imaging device, the control system (not shown) By rotating the test object and narrowing the illumination wavelength band as described above, a condition under which the diffracted light from the pattern does not enter the light receiving optical system may be automatically searched.

Further, the object to be inspected is rotated so that the diffracted light from the pattern is made incident on the light receiving optical system to the light receiving optical system, and the object to be inspected is disclosed in Japanese Patent Application Laid-Open No. 11-51874. An inspection of a pattern on an object may be performed, and inspection of a foreign substance and a flaw may be performed by changing the illumination direction and the direction of the pattern on the test object so that diffracted light does not enter the light receiving optical system.

[0034]

As described above, according to the present invention, the angle range of the illuminating light for illuminating each point of the object to be inspected can be limited narrowly and is almost parallel. The illumination conditions can be made uniform at any point of. Then, by rotating the test object and the illumination light relatively, when scattered light is received, harmful (unnecessary) diffracted light from the pattern on the test object is prevented from entering the light receiving optical system. be able to. This makes it possible to quickly, accurately and highly sensitively detect a foreign substance or the like on the test object. Further, according to the present invention, it is possible to select an illumination wavelength condition under which the diffracted light from the pattern does not enter the light receiving optical system. This makes it possible to detect scattered light from foreign substances and scratches on the test object with high sensitivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a surface inspection apparatus according to a first embodiment.

FIGS. 2A and 2B are diagrams illustrating a lens configuration of an illumination optical system of the surface inspection apparatus according to the first embodiment.

FIG. 3 is a diagram illustrating a configuration of a surface inspection apparatus according to a modification of the first embodiment.

FIGS. 4A and 4B are diagrams showing a lens configuration of an illumination optical system of a surface inspection device according to a modification of the first embodiment.

FIGS. 5A and 5B are diagrams showing a configuration of a surface inspection apparatus according to still another modification of the first embodiment.

FIG. 6 is a diagram showing a configuration near a light source unit of a surface inspection apparatus according to a second embodiment.

FIG. 7 is a diagram showing a configuration near a light source unit of a surface inspection device according to a modification of the second embodiment.

FIG. 8 is a diagram illustrating a configuration of a surface inspection apparatus according to still another modified example of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Light guide fiber 3, 4, 5, 6 Cylindrical lens 7 Object to be inspected 8 Light receiving optical system 9 Aperture stop 10 Imaging optical system 11 Image sensor 12 Signal processing system 13 Holder 20 Spherical lens 30 Reflecting mirror 102 Condensing lens 103,108 Turret 104,107 Filter 105 Input lens 106 Spectral element

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/1333 500 G02F 1/1333 500 H01L 21/66 H01L 21/66 J F-term (Reference) 2F065 AA49 BB02 CC19 CC21 DD04 DD06 FF41 FF48 GG02 GG03 GG23 HH03 HH12 JJ03 JJ26 LL02 LL08 LL19 LL22 MM04 NN06 PP13 UU01 2G051 AA51 AA90 AB01 AB07 BB07 BB09 BB11 BB17 BC07 CA03 CA04 CB01 CC01 DA08 DB15 DB16 DB19

Claims (3)

[Claims] An illumination optical system for illuminating substantially the entire surface of the test object at a predetermined angle with respect to the test object; and a light receiving optical system for receiving scattered light from a foreign substance attached to the surface of the test object. The illumination optical system has three or more groups of optical elements having a refractive power in at least a first plane including an optical axis of the illumination optical system, and the optical axis orthogonal to at least the first plane. A surface inspection apparatus, comprising: an optical element having a refractive power in a second plane including: 2. The light receiving optical system has an image pickup device section, and a wavelength selection element for selecting light of a specific wavelength is provided on the illumination optical system side of the image pickup device section. The surface inspection apparatus according to claim 1. 3. An illumination optical system for illuminating substantially the entire surface of the test object at a predetermined angle to the test object, and a light receiving optical system for receiving scattered light from a foreign substance attached to the surface of the test object. Wherein the light receiving optical system further includes a light receiving element unit, and a wavelength selection element for selecting light of a specific wavelength is provided on the illumination optical system side with respect to the imaging element unit. Surface inspection equipment.