JPH1026589A - Inspection apparatus for foreign body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inspection apparatus by which a foreign body can be inspected with desired sensitivity over the whole of a large face, to be inspected, by a method wherein the face to be inspected is scanned by a plurality of optical spots formed via a plurality of condensing optical systems and the foreign body is detected on the basis of reflected and scattered light. SOLUTION: When a face, to be inspected, on a board 101 is situated in a solid-line position, a beam 5 which is condensed by a scanning lens 3 is reflected by a reflecting mirror 4, and a laser spot is formed in a point A on the face to be inspected. Scattered light 10 from a foreign body with reference to the laser spot reaches a photoelectric detector 15. When the face to be inspected is changed to a broken-line position from the solid-line position, a change amount δ is measured by a sensor 41, the scanning lens 3 is moved along its optical axis on the basis of the change amount δ, and a focusing operation is performed. Then, only when a light receiving lens 12 is moved along its optical axis, the conjugate relationship between the scanning track of a laser spot formed in a point A' on the face to be inspected and an opening part in a slit plate 13 is maintained, and it is possible to cut off nonessential light other than scattered light required for detecting the foreign body due to the action of the slit plate 13 even when the position of the face to be inspected is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign substance inspection apparatus for inspecting foreign substances adhering to a surface to be inspected, and more particularly to an apparatus for inspecting foreign substances on a large substrate used in a manufacturing process of a liquid crystal display device.

[0002]

2. Description of the Related Art For example, in a manufacturing process of a liquid crystal display element, a pattern formed on a mask is projected and exposed on a plate which is a photosensitive substrate. At the time of projection exposure, if foreign matter such as minute dust adheres to the mask, an image of the foreign matter is transferred onto the plate together with the pattern image, and a pattern defect occurs. Therefore, prior to projection exposure,
It is necessary to inspect the presence and position of foreign matter on the mask using a foreign matter inspection device.

In particular, with the recent increase in the size of liquid crystal substrates,
It is necessary to perform a foreign substance inspection over a wide area on a large substrate. Japanese Unexamined Patent Application Publication No. 8-2 filed by the present applicant
In the foreign matter inspection apparatus disclosed in Japanese Patent No. 9353, the beam spot is scanned in one direction on the surface to be inspected by using one scanning lens having a wide scanning area. Then, the foreign substance is detected based on scattered light from the foreign substance on the beam spot while moving the surface to be inspected in a direction orthogonal to the scanning direction of the beam spot.

[0004]

As described above, as the size of the substrate increases, the scanning area of the scanning lens becomes, for example, 500
mm, the required diameter of the scanning lens is 150 mm
About. As a result, the manufacturing cost of the scanning lens is greatly increased, and the size of the entire apparatus is increased. Further, if the flatness of the substrate is not good, it is difficult to focus the scanning lens over the entire wide scanning area, and the detection sensitivity of the foreign matter varies depending on the detection position.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a small foreign matter inspection apparatus capable of detecting foreign matter with a required detection sensitivity over a large inspection surface. Aim.

[0006]

In order to solve the above-mentioned problems, in the present invention, a plurality of condensing optics for condensing a light beam from a light source to form a minute light spot on a surface to be inspected are provided. System, scanning means for scanning the surface to be inspected with a plurality of light spots formed through the plurality of condensing optical systems, and reflection of the plurality of light spots from foreign matter on the surface to be inspected A detecting optical system for detecting the foreign matter based on the scattered light; and a surface shape measuring means for measuring a surface shape of the surface to be inspected, wherein the surface measured by the surface shape measuring device is provided. Provided is a foreign matter inspection apparatus characterized in that the focus of each light condensing optical system is individually adjusted based on the surface shape of an inspection surface.

According to a preferred aspect of the present invention, the scanning means includes a plurality of light sources for moving each of the plurality of light spots formed through the plurality of light-condensing optical systems in a first direction. A scanning optical system, and moving means for moving the surface to be inspected along a second direction orthogonal to the first direction on the surface to be inspected, wherein the detection optical system comprises: A plurality of light receiving optical systems for respectively receiving reflected scattered light from the foreign matter on the inspection surface with respect to each of the plurality of light spots, and obtained on the inspection surface through the plurality of scanning optical systems. The scanning trajectories of the plurality of light spots along the first direction are spaced apart from each other along the second direction. In this case, each of the scanning optical systems is preferably a vibrating mirror provided in an optical path between the corresponding light collecting optical system of the plurality of light collecting optical systems and the light source.

According to a preferred aspect of the present invention, a bending mirror is provided in an optical path between each of the plurality of condensing optical systems and the surface to be inspected, and each of the plurality of light receiving optical systems is provided. The plurality of bending mirrors are respectively parallel so that the intersection of the optical axis and the surface to be inspected is located on the corresponding scanning trajectory of the scanning trajectories of the plurality of light spots obtained on the surface to be inspected. Move. The surface shape measuring means includes light receiving means for receiving specularly reflected light of at least one of the plurality of light spots, and the inspection target is inspected based on a light receiving position of the specularly reflected light. It is preferable to measure the surface position of the surface.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, in the present invention, a plurality of minute light spots are formed on a surface to be inspected via a plurality of condensing optical systems. Then, while scanning the surface to be inspected with the plurality of light spots, the foreign matter is detected based on the reflected and scattered light from the foreign matter. Further, based on the surface shape of the surface to be inspected measured through the surface shape measuring means, for example, by moving a scanning lens in each light condensing optical system along the optical axis, respectively, Adjust the focus.

As described above, according to the present invention, since a plurality of minute light spots are formed on the surface to be inspected via the plurality of light-collecting optical systems, each light-collecting optical system is required to have a large surface to be inspected. The scanning area becomes smaller. As a result, the required diameter of the scanning lens of each condensing optical system is reduced, and both a reduction in the manufacturing cost of the scanning lens and a reduction in the size of the apparatus can be realized. Further, in the present invention, even when the surface to be inspected has undulations or inclinations, that is, when the flatness is not very good, it is possible to individually adjust the focal point of each light collecting optical system according to the surface shape of the surface to be inspected. it can. As a result, foreign substances can be detected with a required detection sensitivity over the entire large inspection surface.

According to a specific mode, each of a plurality of light spots formed through a plurality of condensing optical systems is moved in a first direction by the action of a scanning optical system such as a vibrating mirror. Are moved along the first direction to form a plurality of scanning trajectories along the first direction. Then, the surface to be inspected is moved along the second direction orthogonal to the first direction on the surface to be inspected by the action of a moving means such as a moving stage. Thus, by forming a plurality of scanning trajectories and moving the surface to be inspected, the entire surface to be inspected can be two-dimensionally scanned with a plurality of light spots.

Further, the reflected and scattered light from the foreign matter on the inspection surface with respect to each of the plurality of light spots is received through a plurality of light receiving optical systems. Here, it is preferable that the scanning trajectories of the plurality of light spots obtained on the surface to be inspected along the first direction are spaced apart from each other along the second direction. With this configuration, the scattered light with respect to the light spot formed via each of the condensing optical systems is reliably received only by the corresponding light receiving optical system. In other words, it is possible to prevent each light receiving optical system from receiving scattered light with respect to a light spot other than the corresponding light spot.

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing a configuration of a foreign matter inspection apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged plan view showing the configuration of the light collecting optical system, the light receiving optical system, and the sensor of FIG. In FIG. 1, the z-axis is set along the normal direction of the inspection surface of the substrate 101, and the x-axis and y-axis are set along directions orthogonal to each other on the inspection surface of the substrate 101. Also, in FIG. 2, only one light-collecting optical system, one light-receiving optical system, and one sensor are representatively shown, and therefore, the suffixes (a to c) are omitted for the reference numbers of the respective components. Have been.

In FIG. 1, two mutually parallel beams 1a and 1b supplied from a laser light source not shown are incident on vibrating mirrors (scanning mirrors) 2a and 2b, respectively. The beam reflected by the oscillating mirror 2a is condensed via the scanning lens 3a,
Incident on. The beam reflected by the reflecting mirror 4a becomes a beam 5a, obliquely enters a surface to be inspected of the substrate 101 such as a large mask or a large plate, and forms a laser spot 6a. The laser spot 6a is scanned along the y direction on the surface to be inspected of the substrate 101 by the action of the vibration mirror 2a. As a result, a scanning trajectory 7a of the laser spot 6a is formed on the inspection surface of the substrate 101.

On the other hand, the beam reflected by the oscillating mirror 2b is condensed via the scanning lens 3b, reflected by the reflecting mirror 4b, and becomes a beam 5b obliquely incident on the inspection surface of the substrate 101. And a laser spot 6b. The laser spot 6b is formed on the substrate 1 by the action of the vibrating mirror 2b.
The object is scanned along the y direction on the inspection surface 01.
As a result, a scanning trajectory 7b of the laser spot 6b is formed on the inspection surface of the substrate 101.

As described above, the scanning lens 3a and the reflecting mirror 4a
Constitutes a first condensing optical system for forming a minute laser spot 6a on the surface to be inspected, and the scanning lens 3b and the reflecting mirror 4b form a minute laser spot 6b on the surface to be inspected. A second condensing optical system for this purpose. The vibrating mirror 2a is a first scanning optical system for moving the laser spot 6a formed via the first condensing optical system along the y direction, and the vibrating mirror 2b is a second condensing optical system. A second scanning optical system for moving the laser spot 6b formed through the system along the y direction is configured.

As shown in FIG. 1, the scanning trajectory 7a and the scanning trajectory 7b slightly overlap in the y direction and are separated by a predetermined distance in the x direction. Also, substrate 1
Numeral 01 is held on a stage 102 movable along the x direction so that the surface to be inspected is parallel to the xy plane. Therefore, while scanning the two laser spots 6a and 6b along the y direction by the action of the vibrating mirrors 2a and 2b, the stage 102 and the substrate 101 are moved.
Are moved along the x-direction, so that the entire surface to be inspected of the substrate 101 is divided into two laser spots 6a and 6b.
Can be scanned two-dimensionally.

When foreign matter such as minute dust is present on the upper area of the surface to be inspected of the substrate 101 in the figure, the reflected and scattered light 10a, 20a and 30a from the foreign matter to the laser spot 6a are reflected by the reflecting mirrors 11a and 21a. After being respectively reflected by the light receiving lenses 12a, 22a and 32a, the light enters the light receiving lenses 12a, 22a and 32a. Light receiving lenses 12a, 22a
The scattered lights 10a, 20a and 30a passing through the slits 13a, 23a and 3a respectively have slit-shaped openings optically conjugate with the scanning trajectory 7a.
3a. Scattered light 10a that has passed through the openings of slit plates 13a, 23a and 33a, respectively.
20a and 30a are lenses 14a, 24a and 3
After passing through 4a, the light receiving lenses 12a, 22a and 32
Light is received by the photoelectric detectors 15a, 25a, and 35a arranged at positions conjugate to the aperture position (pupil position) of a. Thus, by the slit plates 13a, 23a and 33a,
Unnecessary light (stray light) other than the scattered light from the foreign matter is blocked, and does not reach the photoelectric detectors 15a, 25a, and 35a.

Similarly, when a foreign matter such as minute dust is present on the lower surface of the surface to be inspected of the substrate 101 in the figure, the reflected and scattered light 10b to the laser spot 6b from the foreign matter is reflected on the laser spot 6b.
30b is a reflecting mirror 11b to 31b, a light receiving lens 12b to
32b, slit plates 13b to 33b, lenses 14b to 3
After passing through each of the photodetectors 4b, the photodetectors 15b to 35b respectively receive light. Also, the slit plates 13b to 33b
Accordingly, unnecessary light (stray light) other than the scattered light from the foreign matter is blocked, and does not reach the photoelectric detectors 15b to 35b.

Thus, the reflecting mirrors 11a to 31a, the light receiving lenses 12a to 32a, the slit plates 13a to 33a, the lenses 14a to 34a, and the photoelectric detectors 15a to 35a
Constitute first to third light receiving optical systems for receiving the scattered light 10a from the foreign matter to the laser spot 6a formed via the first condensing optical system. Further, the reflecting mirrors 11b to 31b, the light receiving lenses 12b to 32b, the slit plates 13b to 33b, the lenses 14b to 34b, and the photoelectric detectors 15b to 35b form a laser spot 6b formed via a second focusing optical system. 4th to 6th light receiving optical systems for receiving the scattered light 10b from the foreign matter to the light.

The intersection between the optical axes of the first to third light receiving optical systems and the surface to be inspected of the substrate 101 is located on the scanning locus 7a formed via the first light condensing optical system. Is configured. Further, the intersections of the optical axes of the fourth to sixth light receiving optical systems and the surface to be inspected of the substrate 101 are configured to be located on the scanning trajectory 7b formed via the second condensing optical system. ing. As described above, the scanning trajectory 7a and the scanning trajectory 7b
Are formed at predetermined intervals along the x direction. Therefore, the scattered light with respect to the laser spot 6a formed via the first condensing optical system is changed to the fourth to sixth light spots.
Scattered light to the laser spot 6b mixed into the light receiving optical system or formed through the second focusing optical system.
It is possible to avoid mixing in the third light receiving optical system.

By the way, the scattered light from the foreign matter to the laser spot has weak directivity, so that it is detected in all light receiving optical systems. On the other hand, the diffracted light from the pattern formed on the surface to be inspected with respect to the laser spot has strong directivity, and is not detected by all the light receiving optical systems. In this way, the signal processing according to the known technique allows each of the photoelectric detectors 15a to 35a and 15b to 35b
Foreign matter can be detected based on the output signal of.

The foreign matter inspection apparatus shown in FIG.
And a surface shape measuring system for measuring the surface shape of the surface to be inspected, that is, the surface position along the z direction. In this embodiment, as shown, two laser spots 6a and 6
A surface shape measurement system is configured by four sensors 41a, 42a, 41b, and 42b arranged in the y direction in the vicinity of the formation position of b. Each sensor is, for example, an oblique incidence type surface position detection sensor. Thus, based on the outputs of the sensors 41a, 42a, 41b and 42b, it is possible to measure the surface shape (the state of undulation or inclination) of the inspection surface of the substrate 101. Then, as described later, it is possible to adjust the focus of each condensing optical system based on the measured surface shape of the surface to be inspected.

Next, with reference to FIG. 2, the operation of adjusting the focal point of each condensing optical system and the operation of adjusting the formation position of the laser spot in the foreign matter inspection apparatus of FIG. 1 will be described. In FIG. 2, when the surface to be inspected of the substrate 101 is at the position indicated by the solid line, the beam condensed via the scanning lens 3 is reflected by the reflecting mirror 4 to become a beam 5 and becomes the beam 5 A laser spot is formed at point A above. As described above, the point A on the surface to be inspected corresponds to the light receiving optical system (11 to 1).
This is the point of intersection of the optical axis of 5) and the surface to be inspected. Therefore, the scattered light 10 from the foreign substance with respect to the laser spot formed at the point A on the inspection surface of the substrate 101 is reflected along the optical axis of the light receiving optical system by the reflecting mirror 11, the light receiving lens 12, and the slit plate 1.
The photoelectric detection 15 is reached via 3 and the lens 14.

When the surface to be inspected fluctuates from the position indicated by the solid line to the position indicated by the broken line in the vicinity of the laser spot forming position due to the undulation or inclination of the surface to be inspected of the substrate 101, the variation δ is determined by the sensor 41 Is measured by
In this way, by moving the scanning lens 3 along the optical axis by a predetermined distance based on the measured variation amount δ, it is possible to adjust the focus of the scanning lens 3 and, consequently, the focus adjustment of the condensing optical system. In addition, a laser spot is formed at the intersection A 'between the optical axis of the light receiving optical system and the inspected surface that has fluctuated by moving the reflecting mirror 4 in parallel to the position indicated by the broken line in the figure based on the measured fluctuation amount δ. can do. In this way, without moving the optical axis of the light receiving optical system, only by moving the light receiving lens 12 along the optical axis,
The conjugate relationship between the scanning trajectory of the laser spot formed at the point A ′ on the inspection surface of the substrate 101 and the opening of the slit plate 13 can be maintained. That is, even if the position of the surface to be inspected fluctuates, unnecessary light other than the scattered light required for foreign substance detection can be reliably blocked by the action of the slit plate 13.

FIG. 3 is a block diagram showing a process for adjusting the focal point of each condensing optical system and adjusting the position at which a laser spot is formed, based on the output of the surface shape measuring system of FIG.
As shown in FIG. 3, each sensor (41a, 42a, 41b)
And the outputs of 42b) are supplied to the arithmetic unit 51, respectively. The computing unit 51 measures the surface shape near the position where the scanning trajectory 7a is formed on the inspection surface of the substrate 101 based on the outputs from the sensors 41a and 42a. Thus, the drive amount of the scanning lens 3a necessary for adjusting the focal point of the first condensing optical system is obtained based on the information on the surface shape near the position where the scanning trajectory 7a is formed. In addition, the driving amount of the reflecting mirror 4a required for adjusting the formation position of the laser spot 6a is obtained.

Further, based on the outputs from the sensors 41b and 42b, the surface shape near the position where the scanning trajectory 7b is formed on the inspection surface of the substrate 101 is measured.
In this way, the driving amount of the scanning lens 3b necessary for adjusting the focal point of the second condensing optical system is obtained based on the information on the surface shape near the position where the scanning trajectory 7b is formed. Further, a driving amount of the reflecting mirror 4b required for adjusting the formation position of the laser spot 6b is obtained. Information on the required driving amount of the scanning lens 3a and the reflecting mirror 4a obtained by the arithmetic unit 51 is transmitted to a driving system 52a (not shown in FIG. 1).
And information on the required driving amount of the reflecting mirror 4b is stored in the driving system 52b.
(Not shown in FIG. 1). Drive system 52
a drives the scanning lens 3a and the reflecting mirror 4a in accordance with the supplied driving amount information. Also, the driving system 52b
Is the scanning lens 3 according to the supplied driving amount information.
b and the reflecting mirror 4b.

As described above, in the present embodiment, two laser spots 6a and 6b are formed on the surface to be inspected via the two condensing optical systems, respectively, and these two laser spots 6a and 6b are connected to the vibrating mirror 2a. And 2b are scanned to form two scanning trajectories 7a and 7b extending along the y direction. Then, the surface to be inspected is x
While moving along the direction, two laser spots 6
The entire surface to be inspected can be two-dimensionally scanned by a and 6b. Therefore, the scanning area of the scanning lens 3 of each focusing optical system is smaller than that of a conventional apparatus that scans a surface to be inspected with one laser spot formed via one focusing optical system. As a result, the required diameter of each scanning lens 3 is reduced, so that the manufacturing cost of the scanning lens 3 can be reduced and the size of the apparatus can be reduced.

In this embodiment, two scanning trajectories 7a are used.
And 4 arranged along the y direction in the vicinity of 7b
The surface shape of the surface to be inspected is measured by a surface shape measurement system including two sensors, and the focal points of the scanning lenses 3a and 3b of each of the condensing optical systems can be adjusted based on the measured surface shape information. Therefore, even when the surface to be inspected has undulation or inclination, foreign matter can be detected with a required detection sensitivity over the entire large surface to be inspected.

Further, by moving the reflecting mirrors 4a and 4b in parallel based on the surface shape information measured by the surface shape measuring system, each of the mirrors 4a and 4b is moved to the intersection between the optical axis of each light receiving optical system and the fluctuated inspection surface. The positions of the laser spots 6a and 6b can be adjusted so that a laser spot is formed. In this way, the scanning locus of the laser spot and the slit plates (13, 23, 33) are moved only by moving the light receiving lens (12, 22, 32) along the optical axis without moving the optical axis of each light receiving optical system. Can maintain a conjugate relationship with the opening. That is, even if the surface to be inspected fluctuates, unnecessary light other than the scattered light required for foreign substance detection can be reliably blocked. As a result, foreign substances can be accurately detected with a required detection sensitivity over the entire large inspection surface.

FIG. 4 is a view corresponding to FIG.
13 is a diagram showing a modification of the surface shape measurement system 41 in FIG. FIG. 5 is a partially enlarged view of the laser spot forming position in FIG. In FIG. 4, elements having the same functions as those in FIG. 2 are denoted by the same reference numerals as in FIG. In FIG. 4, when the substrate 101 is at a position shown by a solid line in the drawing, a beam 5 incident on the inspection surface at an incident angle θ via the scanning lens 3 and the reflecting mirror 4 is a point A on the inspection surface.
To form a laser spot. The scattered light reflected from the foreign matter with respect to the laser spot is received by a light receiving optical system (11 to 15) having an optical axis that forms an angle φ with the normal to the surface to be inspected. On the other hand, the regular reflection beam of the laser spot enters the aperture stop 62 disposed at the rear focal point via the lens 61. The beam passing through the aperture stop 62 forms an image of a laser spot at a point A ″ on the image sensor 63. Thus, the point A on the inspection surface and the point A ″ on the image sensor 63 are conjugate via the lens 61.

Referring to FIGS. 4 and 5, when the surface to be inspected fluctuates by the distance δ at the position where the laser spot is formed, the beam 5 enters the point C on the surface to be inspected at an incident angle θ. The beam specularly reflected at the point C on the surface to be inspected passes through the lens 61 and the aperture stop 62 to the image sensor 63.
A point C ″ separated from the point A ″ by a distance Δ1 above
To form an image of a laser spot. Thus, based on the movement amount Δ1 of the image of the laser spot, the variation amount δ of the inspection surface at the position where the laser spot is formed, and the surface shape of the inspection surface, can be measured. In this case, the scanning lens 3 is preferably telecentric on the image side (substrate 101 side). The feature of the surface shape measurement system (61 to 63) shown in the modification of FIG. 4 is that the surface shape can be continuously measured along the scanning locus of the laser spot within the effective visual field of the lens 61. Is a point.

As described with reference to FIG. 2, if the position of the laser spot is adjusted by moving the reflecting mirror 4 in parallel, when the surface to be inspected fluctuates by the distance δ, the beam 5
At a point B on the surface to be inspected at an incident angle θ. The beam that is specularly reflected at point B on the surface to be inspected passes through a lens 61 and an aperture stop 62 to a laser spot at point B ″ at a distance Δ2 from point A ″ on image sensor 63. Form an image. That is, the movement amount of the image of the laser spot changes due to the influence of the adjustment of the formation position of the laser spot. Hereinafter, a change in the movement amount of the image of the laser spot due to the adjustment of the formation position of the laser spot will be considered.

In FIG. 5, the surface shape measuring system (61) shown in FIG.
63) and the point C on the inspected surface when the inspected surface of the substrate 101 fluctuates downward by a distance δ in the figure. The distance DE between the beam and the path CE of the beam regularly reflected by the following equation is expressed by the following equation (1).

## EQU00001 ## Also, in FIG. 4, if the magnification of the light receiving optical system (11 to 15) is .beta. In FIG. 4, the movement amount of the image of the laser spot due to the fluctuation of the surface to be inspected. Δ1 is represented by the following equation (2).

Δ1 = DEβ = 2βδ tanθ cosθ (2)

Next, when the reflecting mirror 4 is translated and a beam is incident on the point B on the surface to be inspected at an incident angle θ, the path BF of the beam regularly reflected at the point B and the surface shape measurement system (61) ~ 6
The distance DF from the optical axis AD in 3) is expressed by the following equation (3).

DF = δ (tan θ + tan φ) cos θ (3) Similarly, the movement amount Δ2 of the image of the laser spot due to the change of the inspection surface and the change of the formation position of the laser spot is given by the following equation (4). expressed.

Δ2 = DFβ = βδ (tanθ + tanφ) cosθ (4)

From the above equations (2) and (4), the change Δ1-Δ2 in the movement amount of the image of the laser spot due to the change in the formation position of the laser spot is expressed by the following equation (5). You.

Δ1−Δ2 = βδ cosθ (tanθ−tanφ) (5)

As described above, the surface shape measuring system (61 to 63)
The variation amount δ of the surface to be inspected based on the above equation (2)
And the reflection mirror 4 is determined based on the obtained variation amount δ of the inspection surface.
And the amount of movement of the scanning lens 3 can be obtained. In this way, the laser spot forming position can be adjusted by the parallel movement of the reflecting mirror 4 and the focal point of the condensing optical system can be adjusted by the movement of the scanning lens 3. In addition, the movement amount of the reflecting mirror 4 can be controlled by the surface shape measurement system (61 to 63) based on the above equation (5).

As a specific numerical example, the incident angle θ of the beam on the surface to be inspected (that is, the angle between the optical axis of the condensing optical system and the normal to the surface to be inspected) is 45 °, and the light receiving optical system If the angle φ between the optical axis and the normal to the surface to be inspected is 35 °, the above equations (2) and (5) can be rewritten as the following equations (6) and (7).

Δ1 = 1.4βδ (6) Δ1−Δ2 = 0.2βδ (7)

Referring to the above equations (6) and (7), the change Δ1-Δ2 in the amount of movement of the image of the laser spot due to the parallel movement of the reflecting mirror 4 is represented by the variation of the laser spot due to the fluctuation of the surface to be inspected. This is about 1/7 of the image movement amount Δ1. As described above, in the normal configuration, the change amount Δ1−Δ2 of the movement amount of the image of the laser spot due to the change of the formation position of the laser spot is equal to the movement amount Δ1 of the image of the laser spot due to the change of the inspection surface. Since it is sufficiently small in comparison, the influence of the change in the formation position of the laser spot can be ignored in the measurement of the surface system of the surface to be inspected. In the above-described embodiment, an example in which two laser spots are formed using two condensing optical systems has been described. However, a predetermined number of condensing optical systems are used according to the size of the surface to be inspected. It is also possible to form a number of laser spots.

[0040]

As described above, in the present invention, since a plurality of minute light spots are formed on the surface to be inspected via a plurality of condensing optical systems, the required diameter of the scanning lens of each condensing optical system is reduced. As a result, the manufacturing cost of the scanning lens can be reduced and the size of the apparatus can be reduced. Further, according to the present invention, since the focal point of each light condensing optical system can be individually adjusted according to the surface shape of the inspection surface, foreign matter can be detected with a required detection sensitivity over the entire large inspection surface. be able to.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a configuration of a foreign matter inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a focus adjusting operation of each condensing optical system and an adjusting operation of a laser spot forming position in the foreign matter inspection apparatus of FIG.

FIG. 3 is a block diagram showing a process for adjusting a focal point of each light condensing optical system and adjusting a forming position of a laser spot based on an output of the surface shape measuring system of FIG. 1;

4 is a diagram corresponding to FIG. 2, and is a diagram showing a modification of the surface shape measurement system 41 in FIG. 2;

FIG. 5 is a partially enlarged view of a laser spot forming position in FIG. 4;

[Description of Signs] 2 Vibration mirror 3 Scanning lens 4 Reflecting mirror 5 Incident beam 6 Laser spot 7 Scanning locus 8 Fiber bundle 10 Reflected scattered light 11 Reflecting mirror 12 Light receiving lens 13 Slit plate 14 Lens 15 Photoelectric detector 41 Sensor 51 Computing unit 52 drive system 61 lens 62 aperture stop 63 image sensor 101 substrate 102 stage

Claims (5)

[Claims] 1. A plurality of condensing optical systems for condensing a light beam from a light source to form a minute light spot on a surface to be inspected, and a plurality of condensing optical systems formed via the plurality of condensing optical systems. Scanning means for scanning the surface to be inspected with the light spot, and a detection optical system for detecting the foreign matter based on reflected and scattered light from the foreign matter on the surface to be inspected with respect to the plurality of light spots, Surface shape measuring means for measuring the surface shape of the surface to be inspected, based on the surface shape of the surface to be inspected measured via the surface shape measuring unit, the focal point of each condensing optical system A foreign matter inspection device characterized by being adjusted individually. A plurality of scanning optical systems configured to move each of a plurality of light spots formed through the plurality of condensing optical systems along a first direction; Moving means for moving the surface to be inspected along a second direction orthogonal to the first direction on the surface to be inspected, wherein the detection optical system is provided for each of the plurality of light spots. It has a plurality of light receiving optical systems for respectively receiving reflected scattered light from foreign matter on the inspection surface, and a plurality of light spots obtained on the inspection surface via the plurality of scanning optical systems. The foreign matter inspection device according to claim 1, wherein the scanning trajectories along the first direction are spaced from each other along the second direction. 3. Each of the scanning optical systems is a vibrating mirror provided in an optical path between a corresponding light collecting optical system of the plurality of light collecting optical systems and the light source. 3. The foreign matter inspection device according to claim 2, wherein: 4. An optical path between each of the plurality of condensing optical systems and the surface to be inspected is provided with a bending mirror, and each optical axis of the plurality of light receiving optical systems, the surface to be inspected, and The plurality of bending mirrors are respectively translated in such a manner that an intersection point of the plurality of bending mirrors is located on a corresponding scanning trajectory of the scanning trajectories of the plurality of light spots obtained on the inspection surface. 4. The foreign matter inspection device according to 2 or 3. 5. The surface shape measuring means includes a light receiving means for receiving specularly reflected light of at least one of the plurality of light spots, based on a light receiving position of the specularly reflected light. The foreign matter inspection apparatus according to any one of claims 1 to 4, wherein a surface position of the inspection surface is measured.