JP5288672B2 - Surface defect inspection equipment - Google Patents

Description

  The present invention relates to a surface defect inspection apparatus for inspecting a surface defect of a semiconductor wafer or the like in a manufacturing process of a semiconductor wafer or the like represented by an IC chip or a liquid crystal display panel.

  IC chips and liquid crystal display panels are formed by stacking various different circuit patterns on the wafer surface in layers, and each circuit pattern is formed by stacking one layer on the wafer using a photolithography process or the like. . When there is a defect such as a scratch on the wafer surface during the formation of this circuit pattern, it will lead to malfunction of the IC chip or the like as the final product, so surface defect inspection in the manufacturing process is very important.

  Conventionally, surface defects such as semiconductor wafers are inspected by inspectors visually irradiating the wafer surface with various inspection illumination lights from various angles and rotating or swinging the wafer to be inspected. It was done by observation. However, recently, in order to reduce the variation in inspection quality and save labor and increase the efficiency of inspection, there is a strong demand for automating surface defect inspection. For this reason, for example, as disclosed in JP-A-10-339701, the surface of the wafer is irradiated with inspection illumination light at a large incident angle of 80 to 89 degrees, and scattered from the surface of the wafer. Devices for inspecting surface defects based on light are known.

Problems to be solved by the invention

  In the surface defect inspection using such scattered light, as described above, with respect to illumination light having a large incident angle of 80 degrees to 90 degrees, dust or dirt adhering to the wafer surface, or so as to protrude from the wafer surface. Since the scattered light is surely generated from the scratches, the detection is easy. However, in general, scratches formed on the wafer surface or the like are formed with a concave surface, and reflected light does not generate much with respect to illumination light with a large incident angle as described above. The conventional inspection used has a problem that it is difficult to detect surface defects such as concave scratches.

  In view of such problems, the present invention has an object to provide a surface defect inspection apparatus having a configuration capable of efficiently and reliably detecting the presence / absence of a concave shape formed on the surface of a test object. To do.

Means for solving the problem

[Means for Solving the Problems]
In order to achieve such an object, in the present invention, an illumination unit that irradiates an inspection illumination light onto a surface to be inspected, and an illumination unit that emits the illumination light for inspection emits from the surface to be inspected. The surface defect inspection apparatus is configured to include a light receiving unit that receives the scattered light. Then, the angle of the outgoing optical axis of the specularly reflected light that is reflected from the test surface upon receiving the illumination light for inspection by the illumination unit is the normal angle of the test surface, and the outgoing angle θo is the specular reflection. When the opening angle of light is δθo, the angle at which the optical axis of the light receiving unit is viewed from the outgoing optical axis of the regular reflection light is θr, and the opening angle of the light receiving unit is δθr, the following equations (1) and (2) , (3) is set so that each angle is established.

[Expression 1]
δθo <(θr−δθr) (1)
θr ≦ 10 degrees (2)
θo ≦ 60 degrees (3)

  If the surface defect inspection apparatus is configured in this way, the illumination light for inspection from the illumination unit is irradiated from above at a small incident angle with respect to the surface to be inspected, and is surely also from a concave scratch formed on the surface to be inspected. Scattered light is emitted. Here, if the light receiving unit is arranged at a position where the specularly reflected light of the inspection illumination light is not received and the scattered light is received most efficiently, the scattered light can be detected efficiently and the concave flaw can be detected with high accuracy. . The relationship of the above formulas (1), (2), and (3) defines the position of the light receiving unit required to efficiently receive scattered light without receiving the specularly reflected light of the inspection illumination light. In the present invention, each unit is arranged in a positional relationship satisfying the above formulas (1), (2), and (3) to constitute a surface defect inspection apparatus, whereby the concave surface of the test surface is formed. Scratches and the like can be reliably detected.

It should be noted that the angle θr at which the optical axis of the light receiving unit is viewed is as small as possible (that is, within the angle range that constitutes the dark field optical system with respect to the regular reflection light (that is, within the angle range in which the regular reflection light does not enter)) , An angle close to the outgoing optical axis of specularly reflected light), and the angle that forms the dark field optical system (that is, the angle at which diffracted light does not enter) with respect to the diffracted light emitted from the test surface. It is preferable to do this. Thus, scattered light can be received efficiently and is not affected by diffracted light.

In the present invention, the surface defect inspection apparatus can be configured such that the optical axis of the light receiving unit is positioned within the illumination optical axis plane including the optical axis of the illumination unit and the outgoing optical axis of the regular reflection light. In this case, at least one of the test object, the illumination unit, and the light receiving unit is configured to be rotatable around a rotation axis that passes through the intersection of the test surface and the optical axis of the illumination unit and is perpendicular to the illumination optical axis plane, It is preferable that the setting of the outgoing angle θo of the specularly reflected light and the angle θr in which the optical axis of the light receiving unit is expected can be changed.

The surface defect inspection apparatus of the present invention, light having a predetermined angle θs with respect to the specular reflection light through an emission optical axis of the optical axis and specular light illumination optical axis plane including the emitting optical axis of the lighting unit The optical axis of the light receiving unit is positioned within the optical axis plane, and the angle θr at which the optical axis of the light receiving unit is viewed is changed from the outgoing optical axis of the specularly reflected light within the light receiving optical axis plane to the optical axis of the light receiving unit. It can also be configured to have an expected angle. In this case, the predetermined angle θs may be configured to be 90 degrees.

  In the surface defect inspection apparatus having the above-described configuration, at least one of the test object and the illumination unit rotates about the rotation axis that passes through the intersection of the test surface and the optical axis of the illumination unit and is perpendicular to the illumination optical axis surface. The output angle θo of specularly reflected light can be variably set so that the light receiving unit can be configured, and the light receiving unit passes through the intersection of the optical axis of the illumination unit and the test surface, and is a rotation axis perpendicular to the light receiving light axis surface. It is preferable that the angle θr for setting the optical axis of the light receiving unit to be set can be changed.

  In the surface defect inspection apparatus according to the present invention, it is preferable that the object to be inspected can be rotated about an axis perpendicular to the surface to be inspected. Furthermore, in the surface defect apparatus of the present invention, it is preferable that wavelength selection means is provided in at least one of the illumination unit and the light receiving unit.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a surface defect inspection apparatus according to the first embodiment of the present invention. This apparatus includes a wafer support table 1 on which a semiconductor wafer 5 (object to be tested) is placed in a chamber (not shown), and a test illumination on a test surface 5 a of the semiconductor wafer 5 placed on the wafer support table 1. An illumination unit 10 for irradiating light, and a light receiving unit 20 for receiving scattered light emitted from the wafer test surface 5a when the illumination light for inspection is irradiated from the illumination unit 10 onto the test surface 5a. Arranged and configured. Note that a display unit 31 and an image processing unit 32 connected to the light receiving unit 20 via a wiring 30 are disposed outside the chamber.

  The wafer support table 1 has a drive shaft 2 extending vertically downward, and the drive shaft 2 is rotationally driven by a drive mechanism (not shown) to rotate the wafer support table 1 in the horizontal plane around the central axis AX1 of the drive shaft 2. It is configured to be able to. On the wafer support table 1, the wafer 5 is fixed and held by vacuum suction or the like with the test surface 5 a (surface on which a circuit or the like is formed) on the upper surface positioned horizontally.

  The illumination unit 10 includes a light source 11 that emits inspection illumination light, a wavelength selection unit 12 that is placed in front of the light source 11, and a parallel light flux that is emitted from the light source 11 and passes through the wavelength selection unit 12. And an illumination lens 13 for irradiating the wafer test surface 5a of the wafer 5 held on the wafer support table 1. As the light source 11, a metal halide lamp, a mercury lamp, a halogen lamp, or the like is used. The wavelength selection unit 12 selects the wavelength of light to be irradiated on the wafer surface 5a by selecting and passing light outside the predetermined wavelength range from the illumination light emitted from the light source 11, The dichroic mirror, the interference filter, and the like are used for wavelength selection.

  Thus, the angle formed by the incident optical axis C1 of the inspection illumination light emitted from the light source 11 and irradiating the wafer test surface 5a with respect to the normal C2 of the test surface 5a, that is, the incident angle θi is 60 degrees or less. The lighting unit 10 is disposed so as to have an angle. For this reason, the emission angle θo (angle formed by the outgoing optical axis C3 with respect to the normal C2) of the specularly reflected light emitted from the inspection illumination light irradiated at the incident angle θi is reflected by the wafer test surface 5a. An angle equal to or smaller than 60 degrees and equal to the incident angle θi (θi = θo).

  On the other hand, the light receiving unit 20 includes first and second light receiving lenses 21 and 22 and a CCD image sensor 23. As shown in detail in FIG. 2, the light receiving optical axis C4 of the light receiving unit 20 is a surface perpendicular to the wafer test surface 5a including the above-described incident optical axis C1 and outgoing optical axis C3 (this is referred to as the illumination optical axis plane P1). The light receiving unit 20 is disposed so that the light receiving optical axis C4 extends at a predetermined prospective angle (shift angle) θr with respect to the outgoing optical axis C3 in the illumination optical axis plane P1. Yes. That is, the optical axes C1, C3, and C4 are all located on the illumination optical axis plane P1.

  Here, with respect to the opening angle δθo of the regular reflection light and the opening angle δθr of the light receiving unit 20, the prospective angle θr is set to have the relationship of the following equation (4). With this setting, as can be seen from FIG. 2, the light beam of specularly reflected light having a conical expanse with an opening angle δθo centered on the output optical axis C3 has a conical shape with an opening angle δθr centered on the light receiving optical axis C4. The light receiving unit 20 becomes a dark field optical system with respect to specularly reflected light.

[Expression 2]
δθo <(θr−δθr) (4)

  In such a configuration, the inspection illumination light emitted from the light source 11 is wavelength-selected by the wavelength selection filter 12, and then converted into a parallel light beam by the illumination lens 13 and held on the wafer support table 1. 5 is irradiated at an incident angle θi. Since the wafer test surface 5a is a smooth flat surface and is held horizontally by the wafer support table 1, the inspection illumination light irradiated on the wafer test surface 5a as described above is normally used as the wafer test surface. The light is regularly reflected on the surface 5a and emitted with an emission angle θo (= θi) in the direction indicated by the optical axis C3. Here, since the light receiving unit 20 is disposed so as to have the relationship of the above formula (4), the regular reflected light is not received by the light receiving unit 20. Specifically, the specularly reflected light is condensed outside the light receiving surface of the CCD image sensor 23 by the first condenser lens 21.

  However, if dust or debris adheres to the wafer test surface 5a or a flaw occurs, the inspection illumination light radiated to the wafer test surface 5a as described above causes the dust or debris adhering to the wafer test surface 5a to adhere. Etc., and is irregularly reflected (scattered) upon hitting a scratch or the like. Of the irregularly reflected light (scattered light), light traveling toward the light receiving optical axis C4 of the light receiving unit 20 (more specifically, light traveling within the range of the opening angle δθr centered on the light receiving optical axis C4) is the first and The light is condensed by the second condenser lenses 21 and 22 and enters the light receiving surface of the CCD image sensor 23. As a result, images of the dust, dust, scratches and the like are taken by the CCD image pickup device 23 by scattered light generated by dust, dust, scratches, etc. on the wafer test surface 5a.

  Here, as described above, the incident angle θi and the outgoing angle θo of the inspection illumination light are set to be 60 degrees or less, and the inspection illumination light is irradiated to the wafer test surface 5a from a relatively upper position. Is done. For this reason, even when the wafer test surface 5a has a concavely scratched surface, scattered light can be reliably generated, and an image of the concave surface can be well captured by the CCD image sensor 23. .

  Image information captured by the CCD image sensor 23 is sent to the display unit 31 and the image processing unit 32 via the wiring 30. The display unit 31 includes a CRT monitor, a liquid crystal display, and the like, and images of dust, dust, scratches and the like photographed by the CCD image pickup device 23 are displayed on the screen of the display unit 31, and the inspector views the screen display. Thus, the presence or absence of a surface defect on the wafer can be determined. Further, the image processing unit 32 performs image processing on the image information sent from the CCD image pickup device 23 as described above, and surface defects due to dust, dust, scratches, etc. exist in portions where the luminance on the shooting screen exceeds a predetermined threshold. Judge that. As a result, the presence or absence of surface defects on the wafer 5 can be automatically inspected.

  In general, a large number of circuit patterns are formed on the upper surface of the wafer 5, and these circuit patterns have a repetitive pattern composed of wirings arranged at a predetermined pitch. For this reason, when the illumination light for inspection is irradiated onto the wafer surface 5a as described above, diffracted light is also generated according to the pitch of the repeated pattern. The emission direction of the diffracted light is deviated from the specularly reflected light by a predetermined angle. When this deviation angle is close to the expected angle θr of the optical axis C4 of the light receiving unit 20, the diffracted light is received by the light receiving unit 20. There is a problem that the detection accuracy of the surface defect is lowered.

For this reason, it is necessary to prevent the diffracted light from entering the light receiving unit 20. The optical axis C4 of the light receiving unit 20 satisfies the above equation (4), and is shifted from the direction of emission of the diffracted light. On the other hand, the arrangement position of the light receiving unit 20 is set so as to constitute a dark field optical system. To avoid reception of the thus diffracted light, the entire surface of the wafer surface to be inspected 5a (entire range of inspection illumination light is irradiated), the incident light θi becomes constant, the direction of the diffracted light is constant It is preferable to set as follows. Therefore, both the illumination unit 10 and the light receiving unit 20 are preferably configured as an optical system in which the wafer test surface 5a side is telecentric.

  The optical axis of the diffracted light has a predetermined angle with respect to the outgoing optical axis of the specularly reflected light, and the optical axis C4 of the light receiving unit 20 is closer to the outgoing optical axis C3 of the specularly reflected light as much as possible. Of the diffracted light can be prevented. For this reason, the prospective angle θr is set to an angle of 10 degrees or less. In particular, when the object to be inspected is a semiconductor wafer, the diffraction angle of the diffracted light, that is, the expected angle of the diffracted light with respect to the specularly reflected light is generally large. Therefore, the light receiving unit 20 is set by setting the expected angle θr to 10 degrees or less. Receiving diffracted light can be prevented.

  Such an arrangement position is set by rotating the light receiving unit 20 around an axis AX2 that passes through the surface 5a to be measured of the wafer 5 and is perpendicular to the illumination optical axis plane P1. For this reason, a mechanism that can rotate the light receiving unit 20 around the axis AX2 may be provided. Furthermore, a mechanism for rotating the wafer support table 1 around the axis AX2 and a mechanism for rotating the illumination unit 10 around the axis AX2 may be provided. This makes it possible to arbitrarily adjust the incident angle θi and the outgoing angle θo of the illumination light, and the expected angle (shift angle) θr of the optical axis C4 of the light receiving unit 20 with respect to the outgoing optical axis C3 of the regular reflection light.

  In order to prevent the diffracted light from being received in the light receiving unit 20, the incident angle θi and the outgoing angle θo of the illumination light and the expected angle θr of the light receiving unit 20 may be adjusted as described above. Since the light is determined according to the pitch of the repeated pattern formed on the test surface 5a of the wafer 5 and the wavelength of the illumination light, the wavelength of the illumination light is changed so that the diffracted light is not received in the light receiving unit 20. It is also possible. Therefore, a wavelength selection unit 12 is provided. The wavelength selection unit 12 selects and sets the wavelength of the illumination light, adjusts the diffraction angle so that the diffracted light does not enter the light receiving unit 20, or Only illumination light having a wavelength that does not occur is irradiated.

  Furthermore, if the direction of the repetitive pattern formed on the test surface 5a of the wafer 5 is different from the direction of the illumination light, the direction in which the diffracted light is emitted, that is, the diffraction angle changes, so the drive shaft 2 of the wafer support table 1 is moved. The wafer support table 1 may be rotated in a horizontal plane by being rotationally driven by a driving mechanism. As a result, the wafer 5 is rotated about the central axis AX1 extending vertically, and the diffraction angle can be changed.

  In the surface defect inspection apparatus described above, the light receiving unit 20 is disposed so that the light receiving optical axis C4 is positioned in the illumination optical axis plane P1 including the incident optical axis C1 and the outgoing optical axis C3. The arrangement position of 20 is not limited to this. For example, as shown in FIG. 3 showing an arrow III in FIGS. 1 and 2, the light passes through the outgoing optical axis C3 of the specularly reflected light and enters the light receiving optical axis P2 having a predetermined angle θS1 with respect to the illumination optical axis P1. The light receiving optical axis C4 may be positioned. In this case, the prospective angle θr is set so as to satisfy the above-described formula (4) in the light receiving optical axis plane P2.

  Note that the arrangement position of the light receiving unit 20 may be set such that the light receiving optical axis C4 is positioned within the light receiving optical axis plane P3 having a predetermined angle θS2 that is 90 degrees with respect to the illumination optical axis plane P1. In this way, it is easy to change the incident angle θi and the outgoing angle θo while keeping the prospective angle θr constant.

  A second embodiment of the surface defect inspection apparatus according to the present invention will be described with reference to FIG. In this embodiment, the same components as those in the apparatus shown in FIG. This apparatus is configured by disposing a wafer support table 1, an illumination unit 110, and a light receiving unit 120 in a chamber (not shown), and a display unit 31 and an image processing unit 32 disposed outside the chamber are wired. It is connected to the light receiving unit 120 through 30.

  This apparatus differs from the apparatus shown in FIG. 1 only in the configuration of the illumination unit and the light receiving unit. The illumination unit 110 of this apparatus replaces the illumination lens 13 in the illumination unit 10 of the apparatus shown in FIG. The light receiving unit 120 of this apparatus is configured by replacing the first light receiving lens 21 of the light receiving unit 20 of the apparatus shown in FIG. That is, in the apparatus of FIG. 1, the illumination and light receiving units are configured by lens optical systems, but in the apparatus of FIG. 4, these are replaced by reflective optical systems.

  In this way, the apparatus shown in FIG. 4 only replaces the lens with a reflecting mirror, and the positional relationship between the optical axes C1, C2, and C4 viewed from the wafer 5 placed and held on the wafer support table 1 is shown in FIG. Identical to the device. That is, the incident angle θi and the outgoing angle θo are set to 60 degrees or less, and the opening angle δθo of the regular reflection light, the opening angle δθr of the light receiving unit 120, and the expected angle θr are set to have the relationship of the above formula (4). The prospective angle θr is set to an angle of 10 degrees or less.

  For this reason, the illumination unit 110 irradiates the wafer test surface 5a with the inspection illumination light from the light source 11, and the scattered light from the light is received by the light receiving unit 120 so that dust, dust, scratches on the wafer test surface 5a are received. Etc. can be inspected satisfactorily. The method for performing this inspection is the same as that of the apparatus shown in FIG.

  A third embodiment of the surface defect inspection apparatus according to the present invention is shown in FIG. Also in this embodiment, the same components as those in the apparatus shown in FIG. This apparatus is configured by disposing a wafer support table 1, an illumination unit 210, and a light receiving unit 220 in a chamber (not shown), and a display unit 31 and an image processing unit 32 disposed outside the chamber are wired. 30 is connected to the light receiving unit 220.

  This apparatus differs from the apparatus shown in FIG. 1 only in the configuration of the illumination unit and the light receiving unit, and has a large diameter that serves as the illumination lens 13 of the illumination unit 10 and the first light receiving lens 21 of the light receiving unit 20 in the apparatus shown in FIG. The lens 200 is provided in this apparatus. That is, in the apparatus shown in FIG. 5, the lens 200 serves both as the illumination lens of the illumination unit 210 and as the light reception lens of the light receiving unit 220.

  Thus, in the apparatus shown in FIG. 5, since the illumination unit 210 and the light receiving unit 220 share the lens 200, the apparatus configuration can be simplified. However, both units 210 and 220 need to be arranged close to each other, and the incident and reflection angles θi and θo of the inspection illumination light are small angles. Also in this apparatus, the incident angle θi and the emission angle θo are set to 60 degrees or less, and the opening angle δθo of the specularly reflected light, the opening angle δθr of the light receiving unit 220, and the expected angle θr have the relationship of the above formula (4). The prospective angle θr is set to an angle of 10 degrees or less.

  Therefore, the illumination unit 210 irradiates the wafer test surface 5a with the inspection illumination light from the light source 11, and the scattered light from the light is received by the light receiving unit 220 so that dust, dust, scratches on the wafer test surface 5a are received. Etc. can be inspected satisfactorily. The method for performing this inspection is the same as that of the apparatus shown in FIG.

  FIG. 6 shows a fourth embodiment of the surface defect inspection apparatus according to the present invention. The apparatus according to this embodiment has a configuration in which the lens 200 of the apparatus shown in FIG. 5 is replaced with a reflecting mirror 300, and other configurations are the same as those of the apparatus of FIG. That is, the apparatus shown in FIG. 6 is configured by replacing the lens optical system composed of the lens 200 shown in FIG. By using the reflecting mirror 300 in this way, the apparatus can be made smaller and more compact than the apparatus of FIG. Thus, since it is the structure of the same principle as the apparatus of FIG. 5, the description beyond this is abbreviate | omitted.

Effect of the invention

【Effect of the invention】
As described above, according to the present invention, the outgoing angle of specularly reflected light that is reflected from the surface to be inspected upon irradiation of the inspection illumination light by the illumination unit is θo, and the opening angle of the specularly reflected light is δθo. When the angle at which the optical axis of the light receiving unit is viewed from the outgoing optical axis of the regular reflected light is θr, and the opening angle of the light receiving unit is δθr, the relations of the above-described equations (1), (2), and (3) are obtained. Each angle is set so as to hold, and the illumination light for inspection from the illumination unit is irradiated from above with a small incident angle with respect to the surface to be inspected, and also reliably from concave scratches etc. formed on the surface to be inspected Scattered light is emitted, and the scattered light can be received and detected satisfactorily by the light receiving unit, and a concave flaw or the like on the test surface can be reliably detected.

  It is the schematic which shows the structure of the surface defect inspection apparatus which concerns on 1st Embodiment of this invention.   It is explanatory drawing which shows the direction of each optical axis with respect to the wafer test surface in the said surface defect inspection apparatus, and the relationship of each opening.   It is explanatory drawing which shows the relationship of each said optical axis seeing from the direction of arrow III in FIG. 1 and FIG.   It is the schematic which shows the structure of the surface defect inspection apparatus which concerns on 2nd Embodiment of this invention.   It is the schematic which shows the structure of the surface defect inspection apparatus which concerns on 3rd Embodiment of this invention.   It is the schematic which shows the structure of the surface defect inspection apparatus which concerns on 4th Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Wafer support table 5 Wafer 5a Wafer to-be-tested surface 10 Illumination unit 11 Light source 12 Wavelength selection unit 20 Light reception unit 21, 22 1st and 2nd light reception lens 23 CCD image pick-up element 31 Display unit 32 Image processing unit

Claims (9)

An illumination unit that irradiates a surface to be inspected with inspection illumination light; and a light receiving unit that receives the scattered light emitted from the surface to be inspected by irradiation with the inspection illumination light from the illumination unit. Configured with
The outgoing optical axis of the specularly reflected light that is reflected from the test surface upon receiving the illumination light for inspection by the lighting unit is defined as an outgoing angle θo that is an angle formed with respect to the normal of the test surface, When the opening angle of the regular reflection light is δθo, the angle at which the optical axis of the light receiving unit is viewed from the emission optical axis of the regular reflection light is θr, and the opening angle of the light reception unit is δθr,
δθo <(θr−δθr)
θr ≦ 10 degrees θo ≦ 60 degrees, a surface defect inspection apparatus for an object to be inspected.
The angle θr at which the optical axis of the light receiving unit is viewed is set to be as small as possible within the angle range constituting the dark field optical system with respect to the specularly reflected light, and the diffracted light emitted from the test surface 2. The surface defect inspection apparatus according to claim 1, wherein the surface defect inspection apparatus is set at an angle that constitutes a dark field optical system.
The surface defect inspection apparatus according to claim 1, wherein an optical axis of the light receiving unit is located in an illumination optical axis plane including an optical axis of the illumination unit and an outgoing optical axis of the regular reflection light.
At least one of the object to be inspected, the illumination unit, and the light receiving unit can rotate about an axis of rotation that passes through the intersection of the surface to be inspected and the optical axis of the illumination unit and is perpendicular to the surface of the illumination optical axis. 4. The surface defect inspection apparatus according to claim 3, wherein the surface defect inspection apparatus is configured to change the setting of the outgoing angle [theta] o of the regular reflection light and the angle [theta] r that allows an optical axis of the light receiving unit.
The light receiving light passes through the outgoing optical axis of the specularly reflected light and is received in a light receiving optical axis plane having a predetermined angle θs with respect to an illumination optical axis plane including the optical axis of the illumination unit and the outgoing optical axis of the regular reflected light. The optical axis of the unit is located
The angle θr for viewing the optical axis of the light receiving unit is an angle for viewing the optical axis of the light receiving unit from the outgoing optical axis of the specularly reflected light in the surface of the light receiving optical axis. The surface defect inspection apparatus described.
The surface defect inspection apparatus according to claim 5, wherein the predetermined angle θs is 90 degrees.
At least one of the object to be examined and the illumination unit is configured to be rotatable around a rotation axis that passes through the intersection of the surface to be examined and the optical axis of the illumination unit and is perpendicular to the illumination optical axis plane, The emission angle θo of regular reflection light can be variably set.
The light receiving unit is configured to be rotatable about a rotation axis that passes through the intersection between the optical axis of the illumination unit and the test surface and is perpendicular to the light receiving optical axis surface, and an angle θr for viewing the optical axis of the light receiving unit. The surface defect inspection apparatus according to claim 5, wherein the setting of the surface defect can be changed.
The surface defect inspection apparatus according to claim 1, wherein the test object is configured to be rotatable about an axis perpendicular to the test surface.
  The surface defect inspection apparatus according to claim 1, further comprising a wavelength selection unit in at least one of the illumination unit and the light receiving unit.

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