JPH0786465B2 - Foreign object detection method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for detecting minute foreign matter on a sample, and particularly to a foreign matter suitable for detecting foreign matter on a product (patterned) wafer. The present invention relates to a detection method and device.

[Conventional technology]

Taking the foreign matter inspection on a patterned wafer as an example, the conventional technique is, for example, as typified by JP-A-54-57126, a circuit pattern on a wafer and a foreign matter when irradiated with linearly polarized laser light, respectively. It focuses on the difference in polarization resolution of the reflected light. That is, as shown in FIG.
The S-polarized beam emitted from a and 70b obliquely illuminates the wafer 1. In general, since the circuit pattern 71 on the wafer is composed of a substantially regular linear step pattern, depolarization of the laser light is small, and reflection from the straight edge of the pattern 71 orthogonal to the optical axis of the laser beam 103 is performed. The S-polarized component is stored in the light 74 as it is. On the other hand, it is considered that the foreign matter has no regularity in its shape and is composed of minute surfaces having various incident angles with respect to the incident laser light, and the laser light is scattered. As a result, the polarized light is eliminated and the S-polarized light component and the P-polarized light component are mixed in the scattered light 75. Therefore, if a polarizing plate 76 is arranged above the objective lens 7 so as to block the S-polarized light component (shown by the solid line), the photoelectric conversion element 77 will allow foreign matter scattered light to be scattered.
Only the P deflection component in 75 is detected as in 79.

[Problems to be solved by the invention]

FIG. 6 (a) shows the above-mentioned conventional method before passing through the polarizing plate.
Further, FIG. 3B also shows the polarization states of the foreign substance scattered light after passing through. As is apparent from the appendix, in the conventional method, the P-polarized light component that can pass through the polarizing plate is a part of the total foreign matter scattered light, and the minimum detectable foreign matter is 3 to 5 μm.
The limit is about m. That is, in the conventional method, the polarizing plate is used to remove the reflected light from the pattern on the sample, and as a result, most of the foreign substance scattered light is also removed. Therefore, as shown in FIG. 7, in the case of a finer 1 to 2 μm foreign substance 84, the detection becomes extremely difficult due to the decrease in the total scattered light itself and the decrease in the light amount due to the polarizing plate. When the intensity of the laser light is increased to increase the amount of detected light, the scattered light at the pattern corners, which has not been shining so far, passes through the polarizing plate, which makes it difficult to discriminate from the foreign matter. In addition, depending on the material and shape of the foreign matter, depolarization may be small, and in that case, the P-polarized light component is hardly included in the scattered light of the foreign matter, which makes detection even more difficult.

In view of the above-mentioned problems of the prior art, an object of the present invention is to provide another straight line inclined at a predetermined angle with respect to each of the main straight line group and the substantially main straight line group which are substantially orthogonal to each other without depending on the polarization characteristics. Existing on a circuit pattern composed of a group 1
It is an object of the present invention to provide a foreign matter detection method and apparatus capable of detecting a minute foreign matter of ˜2 μm or less with high sensitivity.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention provides a main straight line group which is essentially the same on a sample and is substantially orthogonal to each other, and another straight line group inclined by a predetermined angle in a plane with respect to each of the main straight line groups In each chip formed with a circuit pattern composed of, the illumination light with high directivity is provided on the circuit pattern, and the optical axis of the illumination light is on the circuit pattern surface for each of the main straight line groups. Illuminate from a direction that forms a predetermined rotation angle with a direction inclined with respect to the vertical direction, and at this illumination point, scattered reflected light generated from the edge of the main straight line group is almost perpendicular to the circuit pattern surface. Scattered / reflected light generated from the edge of the other straight line group that enters the detection optical system by escaping from the detection optical system having the optical axis and a predetermined NA (numerical aperture) and scattered reflection from foreign matter existing on the circuit pattern. In the light The scattered reflected light generated from the edge of the other straight line group is shielded by the spatial filter arranged on the Fourier transform surface in the detection optical system, and the scattered reflected light passing through the spatial filter is received by the photoelectric conversion means to be a foreign substance. A foreign matter candidate signal detecting step of converting into a candidate signal and storing it in the memory, and a foreign matter candidate signal stored in the memory by the foreign matter candidate signal detecting step, the foreign matter candidate signal obtained from the photoelectric conversion means, and the same coordinate system in a chip unit. A true foreign matter information detecting step by chip comparison for detecting true foreign matter information by removing as circuit pattern information when detected in common by comparison.

The present invention also provides a circuit pattern which is essentially the same on the sample and is composed of main straight line groups that are substantially orthogonal to each other and other straight line groups that are inclined at a predetermined angle in the plane with respect to each of the main straight line groups. In each of the chips formed with, the illumination light with high directivity is formed on the circuit pattern, and the optical axis of the illumination light forms a predetermined rotation angle on the circuit pattern surface with respect to each of the main straight line groups. In an inclined direction with respect to the vertical direction, and escapes scattered reflected light generated from the edge of the main straight line group at the illumination point in each chip illuminated by the illumination optical system. Has an optical axis substantially perpendicular to the circuit pattern surface and a predetermined NA (numerical aperture) so that scattered reflected light generated from the edge of the straight line group and scattered reflected light from a foreign substance existing on the sample are incident. Objective lens A spatial filter that shields the scattered reflected light generated from the edge of the other straight line group and incident on the objective lens is arranged on the Fourier transform surface, and the scattered reflected light that has passed through the spatial filter is received to detect the foreign substance candidate signal. A foreign matter detection device provided with a detection optical system having a photoelectric conversion means for converting into a foreign matter, a memory for storing a foreign matter candidate signal obtained from the photoelectric conversion means of the detection optical system, and a foreign matter stored in the memory. If the candidate signal and the foreign matter candidate signal obtained from the photoelectric conversion means of the detection optical system are compared in the same coordinate system on a chip-by-chip basis and detected in common, the foreign matter information is removed as circuit pattern information and true foreign matter information is obtained. The foreign matter detecting device is characterized by further comprising a chip comparing means for detecting.

[Action]

With the above configuration, 1 to 2 μ existing on a circuit pattern formed by a main line group that is substantially orthogonal to each other and another line group that is inclined at a predetermined angle with respect to each of the substantially main line groups.
The scattered reflection light generated from the edges of both the main straight line group and the other straight line group is removed without reducing the light quantity of the scattered reflection light from a minute foreign matter of m or less, and the light is arranged on the Fourier transform plane. Erroneous detection due to scattered reflected light generated from the edge of the corner part of the circuit pattern that cannot be completely removed even with a spatial filter is erased as a common part by comparing two chips, and true minute foreign matter information of 1 to 2 μm or less is highly reliable. Can be inspected in degrees.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

First, the basic principle of the present invention will be described with reference to FIG. 2, taking a patterned wafer foreign matter inspection as an example. FIG. 2 (a) shows the principle of the foreign matter inspection optical system. Wafer 1
Is imaged on the photoelectric conversion element 13 by the objective lens 7 and the relay lenses 9 and 12. On the other hand, the spatial frequency region in the objective lens 7, that is, the Fourier transform plane (corresponding to the exit pupil) 8 is imaged at the position of 20 by the relay lens 9. According to the present invention, as shown in FIG. 2B, the circuit patterns formed on the wafer are substantially orthogonal to each other.
For a set of straight lines and the above-mentioned straight lines that exist in a small part
The focus is on the fact that it consists of a total of three groups of straight lines that form an angle of 45 °. Now, FIG. 2 (a)
As shown in FIG. 2, a laser 19 for obliquely illuminating a pattern 18 composed of straight edge portions parallel to the x-axis and the y-axis is assumed.
Let the beam 102 and the x-axis be the angle of rotation made in the plane of the wafer. Depending on the rotation angle, the reflected diffracted light from the linear edge portion of the pattern 18 in the y-axis direction, that is, the Fourier transform image, is at the 20th position, that is, the Fourier transform surface of the objective lens 7 (spatial frequency region = exit pupil). At the image forming position of 8 (21 is the image of the exit pupil), it changes like 22. That is, it can be seen that when the rotation angle becomes a certain value m or more, the reflected diffracted light from the straight edge portion of the pattern no longer enters the objective lens. For example, NA (Numerica1 Aper
ture: numerical aperture) 0.4, m = 20 °. Therefore, when an NA0.4 objective lens is used in the detection optical system, the rotation angle of the oblique illumination laser beam is set to the x-axis and y-axis.
By setting the value to exceed 20 ° with respect to the axis, it is possible to completely eliminate the reflected light from the straight edge portion parallel to the x axis and the Y axis. This rotation angle m has a different value depending on the NA of the objective lens. The larger the NA, the larger the value. At this time, the scattered light of foreign matter is not affected at all. Fig. 2 (b)
Shows the reflected light from the pattern and the foreign matter when the rotation angle is set to 45 ° with a margin. Since the reflected diffracted light from the straight edge portion of the pattern 2 parallel to the x-axis and the y-axis does not enter the objective lens 7, as shown in the detected image 26, these pattern information can be completely removed. On the other hand, in the pattern 2, the reflected diffracted light from the straight edge portion forming the 45 ° direction with respect to the x-axis and the y-axis is incident on the objective lens 7 and is condensed in a slender shape at the 20th position, that is, the Fourier transform plane. The converted image is obtained, and the pattern information 27 of the detected image 26 is obtained. Reference numeral 25 is a Fourier transform image of the foreign matter, which is greatly spread on the Fourier transform plane due to the irregularity of the shape. Therefore, paying attention to the difference in the shapes of the Fourier transform images of both, by installing the spatial filter 29 having the light shielding portion 31 at the position of 20, that is, the Fourier transform plane, the Fourier transform of the straight edge portion in the 45 ° direction is performed. The image can be shielded. As a result, only the foreign substance information 33 can be extracted as shown in the detected image 32. Incidentally, since the pattern in the 45 ° direction is slightly present on the wafer and the Fourier transform image 24 is extremely thin, the light shielding portion 31 of the spatial filter 29 can be made considerably thin. Therefore, the light blocking amount of the foreign substance scattered light by the light blocking unit 31 is extremely small.

As described above, the basic principle of the present invention is that most of the circuit pattern on the wafer is obtained by obliquely illuminating the wafer at a certain rotation angle such that the reflected diffracted light in the x-axis and y-axis directions does not enter the objective lens. By removing the pattern information in the x-axis and y-axis directions occupying, and removing the remaining pattern information in the other direction by a spatial filter provided on the Fourier transform surface of the objective lens or the detection optical system. Only the foreign substance information is extracted without greatly impairing the foreign substance scattered light.

The first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a diagram showing a foreign matter detection optical system in the first and the examples. This optical system includes an xy stage (not shown), laser oblique illumination optical systems 200a and 200b, an objective lens 7, a relay lens 9, a spatial filter 10, a relay lens 12, and a two-dimensional solid-state image sensor 90. In the figure, the sample is a product wafer on which a circuit pattern is formed. The laser illuminating illumination optical systems 200a and 200b are semiconductor lasers 4a and 4b, beam correction optical systems 5a and 5b, and condensing lenses 6a and 6b, respectively.The elliptical beams emitted from the semiconductor lasers 4a and 4b are beam beams. After being shaped into a circular beam by the correction optical systems 5a and 5b, irradiation is performed on the wafer from two directions by the condenser lenses 6a and 6b with an inclination angle of 3 ° and a rotation angle of 45 ° from the x-axis and the y-axis. The wafer 1 is 2 by the objective lens 7 and the relay lenses 9 and 12.
An image is formed on the three-dimensional solid-state image sensor 90. On the other hand, the Fourier transform plane (spatial frequency domain = exit pupil) 8 of the objective lens 7
Is imaged at the position 11 by the relay lens 9. In the present embodiment, the two main sets of straight line edge groups forming the circuit pattern 2 on the wafer 1 are respectively the x-axis and the y-axis.
The wafer is arranged so that it is parallel to the axis. Therefore,
By obliquely illuminating the x-axis and y-axis at a rotation angle of 45 °, the reflected diffracted light from the straight edge group parallel to the x-axis and y-axis does not enter the objective lens. Can be removed. On the other hand, pattern 2
Among them, since the linear edge group forming the 45 ° direction with respect to the x-axis and the y-axis is orthogonal to the laser beam, its reflected diffracted light is shown on the Fourier transform plane 11 as shown in FIG. 2 (b). It becomes a fine and long Fourier-transformed image. Therefore, the pattern information can be removed by providing the spatial filter 10 having the light-shielding portion 15 at the position of 11. In this case, the reflected diffracted light from the 45 ° direction parallel to the laser beam 102 is the objective lens. It does not enter 7. As described above, all the circuit pattern information on the wafer can be removed, and as a result, the detected image of the two-dimensional solid-state imaging device 90 can be removed.
As shown in 16, only the foreign substance information 17 can be extracted.

In this embodiment, as described in the description of the principle, the 45 ° rotation oblique illumination occupies most of the circuit pattern on the wafer without affecting the scattered light of foreign matter.
A spatial filter for removing pattern information in the axial and y-axis directions and for removing pattern information in the remaining other directions
Since the width of the light shielding unit 15 of 10 can be made considerably small, only the foreign substance information can be extracted without greatly impairing the foreign substance scattered light.

The second embodiment of the present invention will be described below with reference to FIG.

FIG. 3 is a diagram showing a foreign matter detection optical system in the second embodiment. This optical system is a laser oblique illumination optical system 200c, 2 newly added in the direction orthogonal to the existing laser oblique illumination optical system in the foreign matter detection optical system of the first embodiment shown in FIG.
00d (not shown) is added to obliquely illuminate from four directions in total, and correspondingly, the spatial filter 40 having the light shielding portions 42 and 43 is arranged on the Fourier transform surface 11,
All have the same configuration and function as the foreign matter detection optical system of the first embodiment. Even when obliquely illuminated from four directions at a rotation angle of 45 ° with respect to the x-axis and the y-axis, the reflected diffracted light from the linear edge group parallel to the x-axis and the y-axis in the pattern 2 is incident on the objective lens. Since it does not, this information can be removed. On the other hand, in pattern 2, for the x-axis and the y-axis
Since the linear edge group forming the 45 ° direction is orthogonal to the laser beams from the four directions, the reflected diffracted light becomes a cross-shaped Fourier transform image condensed on the Fourier transform plane 11. Therefore, this pattern information can be removed by providing the spatial filter 40 having the light shielding portions 42 and 43 at the position of 11. As described above, all the circuit pattern information on the wafer can be removed,
As a result, as shown in the detected image 44 of the two-dimensional solid-state image sensor 90, only the foreign substance information 45 can be extracted.

The present embodiment has not only the same effects as the first embodiment, but also the following effects. That is, some foreign matter has a directivity in its shape, and when illuminated from a limited direction, the directivity of the scattered light becomes high, and in the worst case, the scattered light may not enter the objective lens. Come on. In the present embodiment, since the oblique illumination is performed from four directions, even in the above case, it is possible to reduce the directivity of the foreign substance scattering and prevent the reduction of the foreign substance detection light amount. In addition, even for foreign matter that is attached to the pattern step portion and is difficult to detect due to the shadow of the step in the two-direction illumination, a sufficient illumination light amount can be obtained by the four-way illumination, and it is possible to prevent the foreign matter from being overlooked.

The third embodiment of the present invention will be described below with reference to FIG.

FIG. 4 is a diagram showing a foreign matter detection optical system in the third embodiment. This optical system includes an xy stage (not shown), laser oblique illumination optical systems 200a, 200b, 200c, 200d (not shown),
Objective lens 7, relay lens 9, wavelength separation mirror 50, spatial filters 51a and 51b, mirrors 52a and 52b, wavelength combining mirror 5
3, a relay lens 54, a two-dimensional solid-state image sensor 54, a memory 60 as a signal processing system, and a comparison circuit 150. In the figure, the sample is the same as in the previous two examples.
It is a product wafer on which a circuit pattern is formed. The four laser oblique illumination optical systems 200a, 200b, 200c, 200d are exactly the same in configuration, arrangement, and function as in the second embodiment, or the semiconductor lasers 4a, 4b have a wavelength of 840 nm, and 4c, 4d are The wavelengths of 780 nm are used respectively. The wafer 1'is imaged on the two-dimensional solid-state imaging device 90 by the objective lens 7 and the relay lenses 9 and 54. On the other hand, the Fourier transform plane (spatial frequency domain = exit pupil) 8 of the objective lens 7 is imaged at positions 55 and 56 by the relay lens 9. Wavelength separation mirror 50
And the wavelength synthesizing mirror 53 transmits light having a wavelength of 840 nm,
Reflects light with a wavelength of 780 nm.

The function of the foreign matter detection optical system will be described below. x-axis and y
When oblique illumination is performed from four directions at a rotation angle of 45 ° with respect to the axis, the reflected diffracted light from the linear edge group parallel to the x-axis and the y-axis of the pattern 140 is the same as in the second embodiment. Since the lens is not inclined, this information can be removed. On the other hand, in the pattern 140, straight edge groups forming a 45 ° direction with respect to the x-axis and the y-axis are orthogonal to the laser beams in the four directions. The reflected diffracted light from the linear edge group in the 45 ° direction orthogonal to the beam emitted from the semiconductor lasers 4a and 4b having the wavelength of 840 nm is
After passing through the wavelength separation mirror 50, a Fourier transform image is formed on the Fourier transform surface 55 as shown in FIG. Therefore, by providing the spatial filter 51a having the light shielding portion 58a at the position of 55,
This pattern information can be removed. On the other hand, wavelength
The reflected diffracted light from the linear edge group in the 45 ° direction orthogonal to the beam emitted from the semiconductor lasers 4c and 4d of 780 nm and orthogonal to the beam is reflected by the wavelength separation mirror 50, and at the Fourier transform surface 56, As shown in FIG. 2 (b), a Fourier transform image is obtained in which the beam is elongated and elongated in parallel with the beam. Therefore, similar to the above, by providing the spatial filter 51b having the light shielding portion 58b at the position of 56, this pattern information can be removed. As described above, the reflected lights from the wafer 1 ′ having the two wavelengths from which the information of the circuit pattern is removed are combined by the wavelength combining mirror 53, and then the two-dimensional solid-state image pickup device by the relay switch 54.
Image on 90. On the other hand, the wafer 1'has a larger pattern step than the wafer 1 in the above two embodiments (Al.
In the subsequent step of the semiconductor manufacturing process such as the wiring step, the pattern step becomes larger than in the previous step), so the light scattering state at the corner portion of the pattern 140 becomes close to that of the foreign matter, and the spatial filters 51a and 51b are removed. I will pass.
As a result, the detected image 61 of the two-dimensional solid-state image pickup device 90 contains the foreign substance information 63 and the pattern corner information 62. Therefore, the detected image 61 and the stored image 64 at the same location of the adjacent chip stored in the prediction memory 60 are compared in the comparison circuit 150, and the information of the corner portion of the pattern which is the common portion is removed. Then, as shown in the difference image 66, only the foreign substance information 63 can be extracted.

As described above, the present embodiment has not only the same effects as those of the first and second embodiments, but also the following effects. That is, in the present embodiment, by separating the reflected light from the wafer into two wavelength components, one cross-shaped Fourier transform image as originally shown in the second embodiment is obtained. The linear Fourier transform image of ## EQU1 ## is used so that the area of the light-shielding portion of the spatial filter can be small. As a result, the light blocking amount of the foreign substance scattered light decreases, and the foreign substance detection light amount increases. Further, the combined use of the adjacent chip comparison method improves the foreign matter detection ability on a wafer having a large pattern step, which performance has been conventionally reduced.

In the above embodiments, whether a semiconductor wafer is used as the sample, the present invention is applicable to the detection of foreign matter on a reticle, a mask, or some other regular pattern, or even on a sample without any pattern. Is also applicable.

Further, in the third embodiment, the reflected light from the wafer is separated into two wavelengths by using the wavelength separation mirror. However, this is replaced with the deflection beam splitter, and it is separated into two deflection components orthogonal to each other. Of course, it is possible. At that time, obliquely illuminating with linearly polarized lasers orthogonal to each other.

Further, although the rotation angle of the laser beam is 45 ° in the above embodiments, the rotation angle may be another value as long as it is an angle at which the reflected diffraction light of the pattern edge portion does not enter the objective lens. The angle is determined by the NA of the objective lens.

〔The invention's effect〕

According to the present invention, 1 to 2 μ existing on a circuit pattern composed of a main line group that is substantially orthogonal to each other and another line group that is inclined at a predetermined angle with respect to each of the main line groups.
The aperture (field of view) of the objective lens of the detection optical system detects scattered reflected light generated from the main straight line group edgeon without reducing the light amount of scattered reflected light from a minute foreign matter of m or less.
Corners of the circuit pattern that cannot be completely removed even by the spatial filter disposed on the Fourier transform surface while shielding and removing scattered reflection light generated from the edges of other straight line groups. False detection due to scattered reflected light generated from the edge of is also erased as a common part by two-chip comparison, and there is an effect that true minute foreign substance information of 1 to 2 μm or less can be inspected with high reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a foreign matter inspection optical system according to the first embodiment of the present invention, FIG. 2 is a diagram showing the principle of the present invention, and FIG. 3 is a foreign matter detection optical system according to the second embodiment of the present invention. FIG. 4 is a perspective view showing a system, FIG. 4 is a perspective view showing a foreign matter detection optical system in a third embodiment of the present invention, FIG. 5 is a view showing a conventional detection method, and FIG. 6 is a polarization state of foreign matter scattered light. FIG. 7 and FIG. 7 are diagrams showing the state of detection of minute foreign matter by the conventional method. 1,1 ′ …… Wafer 2,18,17,140 …… Pattern 3,72,84 …… Foreign matter 4a, 4b, 4c, 4d …… Semiconductor laser 19,70a, 70b …… Laser 7 …… Objective lens 8,11 , 20,55,56 …… Fourier transform plane 10,29,40,51a, 51b …… Spatial filter 22,24 …… Fourier transform image of straight edge part 25 …… Fourier transform image of foreign material 90 …… Two-dimensional solid Image sensor

Claims (2)

[Claims] 1. A circuit pattern composed of a main straight line group, which is essentially the same on a sample and is substantially orthogonal to each other, and another straight line group inclined by a predetermined angle in a plane with respect to each of the main straight line groups. In each of the chips formed with, the illumination light with high directivity is formed on the circuit pattern, and the optical axis of the illumination light forms a predetermined rotation angle on the circuit pattern surface with respect to each of the main straight line groups. In this direction, and from a direction inclined with respect to the vertical, the scattered reflection light generated from the edge of the main straight line group at this illumination point is almost perpendicular to the circuit pattern surface and a predetermined NA ( (Numerical aperture) and scattered reflection light generated from an edge of the other straight line group which is released from the detection optical system having a numerical aperture) and incident on the detection optical system and scattered reflection light from a foreign substance existing on a circuit pattern, Edge of line group The scattered reflected light generated from the light is blocked by the spatial filter arranged on the Fourier transform surface in the detection optical system, and the scattered reflected light passing through the spatial filter is received by the photoelectric conversion means to be converted into a foreign object candidate signal and stored in the memory. And the foreign matter candidate signal stored in the memory by the foreign matter candidate signal detection step and the foreign matter candidate signal obtained from the photoelectric conversion means are compared in the same coordinate system on a chip-by-chip basis. A true foreign matter information detecting step by chip comparison for detecting true foreign matter information by removing as circuit pattern information when detected, a foreign matter detecting method. 2. A circuit pattern composed of a main straight line group which is essentially the same on the sample and is substantially orthogonal to each other, and another straight line group which is inclined at a predetermined angle in a plane with respect to each of the main straight line groups. In each of the chips formed with, the illumination light with high directivity is formed on the circuit pattern, and the optical axis of the illumination light forms a predetermined rotation angle on the circuit pattern surface with respect to each of the main straight line groups. In an inclined direction with respect to the vertical direction, and escapes scattered reflected light generated from the edge of the main straight line group at the illumination point in each chip illuminated by the illumination optical system. Has an optical axis substantially perpendicular to the circuit pattern surface and a predetermined NA (numerical aperture) so that scattered reflected light generated from the edge of the straight line group and scattered reflected light from a foreign substance existing on the sample are incident. Objective lens A spatial filter that blocks scattered reflected light generated from the edge of the other straight line group and incident on the objective lens is arranged on the Fourier transform surface, and the scattered reflected light that has passed through the spatial filter is received to detect a foreign substance candidate signal. A foreign matter detection device provided with a detection optical system having a photoelectric conversion means for converting into a foreign matter, a memory for storing a foreign matter candidate signal obtained from the photoelectric conversion means of the detection optical system, and a foreign matter stored in the memory. If the candidate signal and the foreign matter candidate signal obtained from the photoelectric conversion means of the detection optical system are compared in the same coordinate system on a chip-by-chip basis and detected in common, the foreign matter information is removed as circuit pattern information and true foreign matter information is obtained. A foreign matter detection device comprising a chip comparison means for detecting