JPH04328413A - Visual inspection apparatus - Google Patents

Abstract

PURPOSE:To detect the two-dimensional pattern of the surface of a sample accurately by scanning the surface of the sample by a beam with an optical scanning means, detecting the intensities of both regular reflected light and scattered light at the illuminated point, and combining and operating both data. CONSTITUTION:The light emitted from a light source 14 passes through an optical scanning system 15 and an ftheta lens 16. The incident light L2 is obliquely cast on a sample 10 so as to scan the surface. The image of the reflected light is formed on the light receiving surface of a photodetector 21A through an image forming lens 20A. The image of the scattered light is formed on the light receiving surface of a photo-detector 21B through an image forming lens 20B. The outputs A and B of the photodetectors are supplied into a correcting circuit 19, and the primary combination difference muA-alphaB is computed. At mu=1, alpha is the constant close to 1. The output of the correcting circuit 19 is stored in a image memory 23. The content is supplied into a pattern inspecting circuit 24, and a good or bad state (a) is judged. The incident light L2 is cast on a substrate 10b and a lower-layer printed wiring pattern 10b2. Since the scattered light on the pattern 10b2 has the weak optical directivity, the scattered light component of the output A becomes approximately equal to the output B. The scattered light component is canceled in A-alphaB.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to a sample in which an object to be inspected is placed on a substrate, which has a part that reflects incident light only on the surface and a part that reflects on the surface and scatters on the lower layer. The present invention relates to an apparatus for visually inspecting a multilayer printed wiring pattern formed on a base material.

0002

2. Description of the Related Art FIG. 12A shows the measurement principle of a conventional visual inspection device.

Sample 10 is a printed wiring board, and substrate 1
For example, a printed wiring pattern 10 with a thickness of 5 μm is placed on 0a.
b is formed. The board 10a is a multilayer wiring board, and a lower printed wiring pattern 10b is formed on the base material layer 10a2.
2 is formed, and a base material layer 10a1 is laminated thereon. The base layers 10a1 and 10a2 have a thickness of 30 μm, for example.
It is a translucent material that is close to transparent, such as polyimide resin.

In order to measure the two-dimensional shape and thickness of the printed wiring pattern 10b, a light beam is irradiated onto the sample 10, and the light from the irradiation point is passed through the imaging lens 20 to the PSD 22.
image on top. The sum of a pair of outputs A and B of PSD22 (
A+B) represents the brightness of the light irradiation point, and the ratio (A-B)/(A+B) of the difference and sum of this pair of outputs represents the height of the light irradiation point.

In the following cases, the light irradiation point is on the substrate 10a.
It is possible to accurately determine whether the object is above the object.

(1) When the light irradiation point is on the substrate 10a and the lower layer printed wiring pattern 10b2 does not exist directly below the light irradiation point, or (3) As shown in FIG. 8(B),
Even if the lower printed wiring pattern 10b2 is located directly below the light irradiation point, the light reflected by the lower printed wiring pattern 10b2 is blocked by the printed wiring pattern 10b above the lower printed wiring pattern 10b2.

[0007]

[Problem to be solved by the invention] However, FIG.
), when the lower layer printed wiring pattern 10b2 exists directly below the light irradiation point, the light from the light irradiation point on the substrate 10a and the light irradiation point on the lower layer printed wiring pattern 10b2 is transmitted to the imaging lens 20. Therefore, it may not be possible to accurately determine whether the printed wiring pattern 10b on the board 10a is the printed wiring pattern 10b on the board 10a based on the brightness (a+b). For this reason, the substrate 10
It is not possible to accurately detect the printed wiring two-dimensional pattern on a.

[0008] In view of these problems, an object of the present invention is to provide an object to be inspected that is placed on a substrate having a portion that reflects incident light only on the surface and a portion that reflects the incident light on the surface and scatters on the underlying layer. Even if the sample is
An object of the present invention is to provide an appearance inspection device that can accurately detect dimensional patterns.

[0009]

Means for Solving the Problems and Their Effects The appearance inspection apparatus according to the present invention will be explained with reference to the drawings.

In the first invention, as shown in FIG.
and a portion that reflects incident light only on the surface, and a portion that reflects the incident light on the surface and a lower layer, for example, the lower layer printed wiring pattern 10b2.
A light scanning means, for example, components 12 and 1, scans a light beam emitted from a light source 14 with respect to a sample 10 in which an object to be inspected is placed on a substrate 10a having a scattering portion.
5 to 18, specular reflection light detection means for detecting the intensity of the specularly reflected light from the light irradiation point, such as an imaging lens 20A and a photodetector 21A, and a scattering device for detecting the intensity of the scattered light from the light irradiation point. The linear coupling difference μA−αB between the light detecting means, for example, the imaging lens 20B and the photodetector 21B, and the detected intensity A of the specularly reflected light and the detected light intensity B of the scattered light (μ and α are positive constants; in FIG. 1, μ= 1), such as a brightness correction circuit 19, and inspection means, such as a brightness image memory 23, for visually inspecting the two-dimensional pattern of the object based on the linear combination difference μA-αB. The pattern inspection circuit 24 is also provided.

[0011] With only the specular reflection light detection intensity A, Fig. 2(A)
In some cases, it may not be possible to distinguish whether the incident light L1 is irradiating onto the printed wiring pattern 10b, or the incident light L2 is irradiating onto the substrate 10a and the lower printed wiring pattern 10b2. However, since the scattered light on the lower printed wiring pattern 10b2 has weak directivity, the scattered light component included in the specular reflection light detection intensity A and the scattered light detection light intensity B are almost the same, and μA−αB is Scattered light components are canceled.

Therefore, even if the sample to be inspected 10b is placed on the substrate 10a, which has a portion where incident light is reflected only on the surface and a portion where it is reflected on the surface and scattered on the lower layer, the specimen 10b is placed on the substrate 10a. It is possible to accurately detect the two-dimensional pattern of the object to be inspected 10b. Note that the effects of the present invention can be obtained even if the constants μ and α are simply set to μ=1 and α=1, for example.

In one aspect of the first invention, as shown in FIG. 3, the scattered light detection means 21B reflects the light scattered in the opposite direction to the light beam directed toward the sample 10 with the half mirror 25, and detects the scattered light. Detect light intensity.

In this configuration, the scattered light detection means 20B,
By configuring 21B integrally with the optical scanning optical system 15 of the optical scanning means, the optical system of the visual inspection apparatus can be made compact.

The second invention includes the light source 14, the light scanning means 12, 15 to 18, the specular reflection light detection means 20A, 21A, and the inspection means 23, 24, and furthermore, as shown in FIG. A first height detection means for detecting the height of the light irradiation point by condensing the reflected light of the light, for example, an imaging lens 20A,
The PSD 22B and the height calculation circuit 28B are arranged to condense the reflected light from the light irradiation point and pass through parts with different transmittance depending on the height of the light irradiation point, for example, in one direction as shown in FIG. A density filter 26 whose transmittance monotonically increases along
A second height detection means for detecting the height of the light irradiation point, such as an imaging lens 20A, a half mirror 25, a density filter 26A, a PSD 22A, and a height calculation circuit 28A.
, the height detected by the first height detection means 20A, 22B, 28B and the second height detection means 20A, 25, 26A, 22
Based on the difference between the height detected by A and 28A, a determining means, such as a subtracter 29 and a comparator 30, determines whether the light is scattered from the lower layer, and based on the result of the determination, the specular reflection It is provided with brightness correction means for correcting the light detection intensity, for example, a selector 31, and the inspection means 23 and 24 visually inspect the two-dimensional pattern of the inspection object 10b based on the corrected detection intensity.

According to such a configuration, as shown in FIG. 6, the peak positions of the light intensity distribution on the PSD 22A and the light intensity distribution on the PSD 22B are shifted according to the peak width, that is, the spread of the light intensity distribution. become. The spread of the light intensity distribution is the largest in the case of scattered light in the same figure (B), so
In this case, the deviation ΔPD is the largest. therefore,
Based on the light detection intensity corrected according to this shift, it becomes possible to accurately detect the two-dimensional pattern of the object to be inspected 10b.

In one aspect of the second invention, as shown in FIG. 7, the first height detecting means 20A, 26B, 22B, 28B
is a density filter 26B that collects the reflected light from the light irradiation point, and is arranged so that the higher the height of the light irradiation point, the lower the transmittance part, and whose transmittance increases monotonically in one direction.
The density filter 26A of the second height detection means 20A, 25, 26A, 22A, 28A passes through a portion with higher transmittance as the height of the light irradiation point increases. It is arranged like this.

In the case of this configuration, the above-mentioned deviation ΔPD shown in FIG. 6 becomes larger (approximately twice) than when one density filter is used, making it easier to determine whether the light irradiation point is on the lower layer 10b2 of the substrate 10a. It becomes possible to discriminate accurately. As a result, the object to be inspected 10b formed on the substrate 10a
can be detected more accurately.

In another aspect of the second invention, as shown in FIG.
, 22B, 28B and the second height detection means 2
Lower layer 1
It is determined whether the scattered light is from 0b2.

In the case of this configuration, it is determined whether the light is scattered from the lower layer 10b2 based not only on the difference in detection height but also on the intensity of specularly reflected light that includes the characteristics of the scattered light from the lower layer 10b2. Since the board 10 is determined more accurately,
It becomes possible to detect the object to be inspected 10b on the surface a.

The third aspect of the present invention includes the light source 14, the light scanning means 12, 15 to 18, and the inspection means 23, 24, and furthermore, as shown in FIG. 9 or 10, specularly reflected light from the light irradiation point is collected. The first light emits light and detects the intensity of the specularly reflected light through a density filter 26B, which is arranged so as to pass through a portion with a lower transmittance as the height of the light irradiation point is lower, and whose transmittance increases monotonically along one direction. It includes detection means 20A, 26B, and 21B, and inspection means 23 and 24 visually inspect the two-dimensional pattern of the object to be inspected based on the detected intensity of the specularly reflected light.

In this configuration, the intensity of the light reflected on the lower layer 10b2 is reduced to a greater extent than the intensity of the light reflected on the substrate 10a or the object to be inspected 10b, so the detected intensity of the specularly reflected light Based on this, it becomes possible to accurately detect the two-dimensional pattern of the object to be inspected.

In the fourth invention, the light source 14, the light scanning means 12, 15 to 18, and the first light detection means 20A, 26B, 2
1B and inspection means 23 and 24, and as shown in FIG. 11, the specularly reflected light from the light irradiation point is collected, and the higher the height of the light irradiation point is, the lower the transmittance is. Density filter 26 whose transmittance monotonically increases along one direction
second light detection means 20A, 25, 26A, 21A that detect the intensity of the specularly reflected light through A; and first light detection means 2;
A dividing means, for example, a divider 36, for calculating a value B/A obtained by dividing the detection intensity B by the second light detection means 20A, 25, 26A, 21A by the detection intensity A by the second light detection means 20A, 25, 26A, 21A, and the inspection means 23, 24 visually inspects the two-dimensional pattern of the inspection object 10b based on the division result of the division means 36.

In this configuration, the lower the light irradiation point is, the smaller the rate of reduction in detected intensity A becomes, and the greater the rate of reduction in detected intensity B becomes. Therefore, B/A is better than detection strength B alone.
In this case, the brightness near the surface of the sample 10 is emphasized, and by using this B/A, it becomes possible to detect the object 10b on the substrate 10a more accurately.

[0025]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

(1) First Embodiment FIG. 1 is a block diagram of a visual inspection apparatus according to a first embodiment of the present invention. The sample 10 is the same as that shown in FIG. 12, and its description will be omitted.

The sample 10 is placed on an XY stage 12 for sub-scanning. The light beam emitted from the light source 14 is passed through a light scanning optical system 15 using a polygon mirror or the like.
The light passes through the fθ lens 16 and is irradiated obliquely onto the sample 10, and is main-scanned in the direction perpendicular to the plane of the paper. The end of one main scan is detected by the photodetector 17, and the detection signal is supplied to the stage control circuit 18. In response to this, the stage control circuit 18 drives the XY stage 12 in steps perpendicular to the optical scanning direction by one line.

A photodetector 21A is disposed diagonally above the sample 10 via an imaging lens 20A in order to detect specularly reflected light from the light irradiation point, and the reflected light is detected by the imaging lens 20A. through which an image is formed on the light receiving surface of the photodetector 21A. Directly above the sample 10, a photodetector 21B is installed via an imaging lens 20B to detect scattered light from the light irradiation point.
is arranged, and the scattered light is imaged on the light receiving surface of the photodetector 21B through the imaging lens 20B. Photodetector 2
1A and 21B are, for example, photomultiplier tubes.

Outputs A and B of photodetectors 21A and 21B
is supplied to the brightness correction circuit 19, and (A-αB) is calculated. α is a constant close to 1, and may be set variable, or may simply be set to α=1 and the brightness correction circuit 19 may be configured with a subtracter. The output of the brightness correction circuit 19 is
The brightness image is supplied to the image memory 23 and stored therein. The storage address is determined by a clock synchronized with the optical scanning by the optical scanning optical system 15 and the position coordinates of the XY stage 12. The contents of the brightness image memory 23 are supplied to a pattern inspection circuit 24 and compared with a reference pattern to determine whether the pattern is acceptable or not.

Next, the operation of the visual inspection apparatus constructed as described above will be explained based on FIG. 2.

As shown in FIG. 5A, when the incident light L1 is reflected on the printed wiring pattern 10b, the light intensity distribution curve connecting the tips of the light intensity vector of the reflected light is P.
It will be like 1. Similarly, when the incident light L2 is reflected on the substrate 10a, the light intensity distribution curve of the reflected light becomes P2, which is smaller than P1. The incident light L2 enters the base material layer 10a1 and is transmitted to the lower layer printed wiring pattern 10b.
2, the base material layer 10a1 becomes the lower layer printed wiring pattern 10b2 at the micro level as shown in the exaggerated diagram.
Since the substrate layer 10a1 is not in complete contact with the base material layer 10a1 and has a diffusive property, the light intensity distribution curve of the scattered light on the lower printed wiring pattern 10b2 becomes as shown in P4.

FIG. 3B shows the range of the output A of the photodetector 21A in each case, where PU is the case where the incident light L1 is reflected on the printed wiring pattern 10b, and S is the case where the incident light is reflected on the printed wiring pattern 10b. In this case, PD is reflected on the substrate 10a like L2 or L3 (assuming that there is no scattered light from above the lower printed wiring pattern 10b2), and PD is reflected on the lower printed wiring pattern 10b2 like incident light L2. (However, it is assumed that there is no reflected light from above the substrate 10a), and S+PD is reflected from the substrate 10a like the incident light L2.
This is a case where the light is reflected on the upper and lower printed wiring patterns 10b2. (C) of the same figure shows the range of the output of the photodetector 21B in each of the above cases, and (D) of the same figure shows the output of the brightness correction circuit 19.

As is clear from FIG. 2, the photodetector 21A
If only the output A of
In some cases, it may not be possible to distinguish whether the upper part is being irradiated or not. However, since the scattered light on the lower printed wiring pattern 10b2 has weak directivity, the scattered light component included in the output A and the output B are almost the same. Therefore, the scattered light component is canceled in the output (A-αB) of the brightness correction circuit 19,
Using this output, it becomes possible to reliably identify whether the light irradiation point is on the printed wiring pattern 10b.

Thereby, the pattern inspection circuit 24 can accurately inspect the printed wiring pattern 10b formed on the substrate 10a.

(2) Second Embodiment FIG. 3 is a block diagram of a visual inspection apparatus according to a second embodiment of the present invention. Components that are the same as those in FIG. 1 are given the same reference numerals and their explanations will be omitted.

In this visual inspection apparatus, the light scanning optical system 15
A half mirror 25 is arranged between and the fθ lens 16,
The light scattered on the sample 10 is focused by the fθ lens 16,
The half mirror 25 reflects this light, and the photodetector 21B detects the light intensity.

According to this visual inspection apparatus, the imaging lens 20B shown in FIG. 1 is not required, and the half mirror 25
By configuring the photodetector 21B integrally with the light scanning optical system 15 and the fθ lens 16, the optical system of the visual inspection apparatus can be made compact.

(3) Third Embodiment FIG. 4 is a diagram showing the main part of a visual inspection apparatus according to a third embodiment of the present invention. Components that are the same as those in FIG. 1 are given the same reference numerals and their explanations will be omitted.

This visual inspection apparatus forms an image of the light irradiation point on the sample 10 onto the PSD 22B using the imaging lens 20A, and a half mirror 2 is installed between the imaging lens 20A and the PSD 22B.
5 is arranged, and the light reflected by the half mirror 25 is imaged on the PSD 22A through the density filter 26A. A pair of outputs A1 and A2 of the PSD 22A are supplied to a height calculation circuit 28A, and the height calculation circuit 28A outputs the height of the light irradiation point (A1-A2)/(A1+A2). P
A pair of outputs B1 and B2 of the SD22B are supplied to a brightness calculation circuit 27 and a height calculation circuit 28B, the brightness calculation circuit 27 outputs the brightness (B1+B2) of the light irradiation point, and the height calculation circuit 28B outputs the brightness of the light irradiation point. Height of irradiation point (B1-B2)/(
B1+B2) is output. The brightness (B1+B2) is supplied to the a-side terminal of the selector 31, and the value 0 is supplied to the b-side terminal of the selector 31.

The transmittance distribution of the density filter 26A increases monotonically from the upper end to the lower end in the figure, for example, as shown in FIG.
As shown in (A) to (C), the transmittance increases linearly, curved, or increases linearly from 0 to the center position. If such a density filter 26A is used, P
The peak positions of both the light intensity distribution on the SD 22A and the light intensity distribution on the PSD 22B are shifted according to the peak width.

In FIG. 6, the upper row shows the light intensity distribution on the PSD 22B, and the lower row shows the light intensity distribution on the PSD 22A. In addition, the same figure (A) shows the printed wiring pattern 10b.
The same figure (B) shows the case where there is a light irradiation point on the lower layer printed wiring pattern 10b2, and the same figure (C) shows the case where there is a light irradiation point only on the substrate 10a. shows. ΔPU, ΔPD and ΔS are the peak position of the light intensity distribution on the PSD 22B and P in each of these cases.
The difference from the peak position of the light intensity distribution on SD22A is shown. Since the spread of the light intensity distribution is the largest in the case shown in FIG. 3B, which corresponds to scattered light, the deviation ΔPD is the largest among the deviations ΔBU, ΔPD, and ΔS. Utilizing this fact, it is possible to identify whether the light irradiation point is on the lower printed wiring pattern 10b2.

Therefore, in FIG. 4, the height calculation circuit 28
The outputs of A and 28B are supplied to the subtractor 29 to calculate the difference between the two, and the result is supplied to the comparator 30 and compared with the given reference value E. If it is greater than or equal to E, the light irradiation point is in the lower layer. It is determined that it is on the printed wiring pattern 10b2, and only at this time, the selector 31 is switched to the b side, and the brightness at this time is set to 0. When the light irradiation point is only on the wiring pattern 10b or the substrate 10a, the deviation amount ΔPU is small and the output of the subtractor 29 is also smaller than E, so the selector 31 is switched to the a side, and the brightness output is B1+B2. becomes. 6 (
As shown in A) and (C), the brightness B1+B2 is sufficiently different between the two, so they can be easily distinguished.

The brightness thus obtained makes it possible to accurately detect the printed wiring pattern 10b formed on the substrate 10a.

(4) Fourth Embodiment FIG. 7 is a diagram showing the main part of an external appearance inspection apparatus according to a fourth embodiment of the present invention. Components that are the same as those in FIG. 4 are given the same reference numerals and their explanations will be omitted.

In this appearance inspection device, the half mirror 25
A density filter 26B similar to the density filter 26A is also arranged between the PSD 22B and the PSD 22B. Brightness calculation circuit 2
7 calculates the brightness (B1+B2) of the light irradiation point and supplies this to the A side terminal of the selector 31. The value 0 is supplied to the B side terminal of the selector 31.

As shown in the figure, the density filter 26A is arranged so that the lower the light irradiation point is, the higher the transmittance (lower the density) is.
The lower the light irradiation point is, the more it passes through a portion with lower transmittance (higher concentration). As a result, the deviations ΔPU, ΔPD, and ΔS shown in FIG. 6 become larger (approximately twice) than in the third embodiment, and it is determined whether the light irradiation point is on the lower printed wiring pattern 10b2 in the third embodiment. It becomes possible to make a more accurate determination than in the case of

Output of brightness calculation circuit 27 (B1+B2)
is supplied to the binarization circuit 32, compared with a reference value and binarized, and then supplied to one input terminal of the AND gate 33. The output of the comparator 30 is supplied to the other input terminal of the AND gate 33, and when the light irradiation point is on the lower printed wiring pattern 10b2, the output of the comparator 30 becomes a low level and the AND gate 33 is closed. .

[0048] This makes it possible to accurately detect the printed wiring pattern 10b formed on the substrate 10a.

(5) Fifth Embodiment FIG. 8 is a diagram showing the main part of an external appearance inspection apparatus according to a fifth embodiment of the present invention. Components that are the same as those in FIG. 4 are given the same reference numerals and their explanations will be omitted.

In this visual inspection apparatus, a lower layer discrimination circuit 34 is used in place of the comparator 30 shown in FIG. The lower layer discrimination circuit 34 determines that the output of the subtracter 29 is E.
1 or more, and the output of the brightness calculation circuit 27 is as shown in FIG.
Range E2≦B1+B2≦E corresponding to S+PD in (B)
3, the light irradiation point is the lower printed wiring pattern 10
It is determined that it is on b2.

According to this visual inspection apparatus, it is possible to detect the printed wiring pattern 10b on the board 10a more accurately than in the case of the third embodiment.

(6) Sixth Embodiment FIG. 9 is a diagram showing the main part of an external appearance inspection apparatus according to a sixth embodiment of the present invention. Components that are the same as those in FIG. 1 are given the same reference numerals and their explanations will be omitted.

In this visual inspection device, the imaging lens 20A
A density filter 26B is arranged between the photodetector 21B and the photodetector 21B. The density filter 26B is arranged so that the lower the light irradiation point, the higher the density passes through the part. Therefore, the intensity of the light reflected on the lower printed wiring pattern 10b2 is different from that on the substrate 10a or on the printed wiring pattern 10b2.
b is reduced to a greater extent than the intensity of the light reflected on b. This makes it possible to accurately detect the printed wiring pattern 10b on the board 10a using only the output of the photodetector 21B.

The output of the photodetector 21B is sent to the binarization circuit 32.
and a floating reference voltage generator 35. The floating reference voltage generator 35 includes, for example, a CR integration circuit, and supplies the DC component of the output of the photodetector 21B plus a bias DC voltage to the binarization circuit 32 as a binarization reference value. . This makes it possible to detect the printed wiring pattern 10b on the board 10a even more accurately.

(7) Seventh Embodiment FIG. 10 is a diagram illustrating the main part of a visual inspection apparatus according to a seventh embodiment of the present invention. Components that are the same as those in FIG. 9 are given the same reference numerals and their explanations will be omitted.

In this visual inspection device, the imaging lens 20A
A half mirror 25 is arranged between the half mirror 25 and the density filter 26B, and the light reflected by the half mirror 25 is sent to the photodetector 21A.
The image is formed on top. The outputs A and B of the photodetectors 21A and 21B are supplied to a divider 36, and the height B/A is calculated. The other points are the same as the sixth embodiment.

According to this visual inspection apparatus, the density filter 26B can be used both for height detection and for detecting the printed wiring pattern 10b on the substrate 10a.

(8) Eighth Embodiment FIG. 11 is a diagram illustrating the main part of a visual inspection apparatus according to an eighth embodiment of the present invention. Components that are the same as those in FIG. 10 are given the same reference numerals and their explanations will be omitted.

In this appearance inspection device, the half mirror 25
A density filter 26A is arranged between the photodetector 21A and the photodetector 21A. Contrary to the case of the density filter 26B, the density filter 26A is arranged so that the lower the light irradiation point is, the lower the density is. In this way, the lower the light irradiation point is, the smaller the reduction rate of the output A of the photodetector 21A becomes, and the larger the reduction rate of the output B of the photodetector 21B becomes. Therefore, the brightness near the surface of the sample 10 is emphasized by the output B/A of the divider 36 than by B alone, and this B/A
By using this, it becomes possible to detect the printed wiring pattern 10b on the board 10a more accurately.

The output of the divider 36 is supplied to the binarization circuit 32 and the floating reference voltage generator 35, and the same processing as in the seventh embodiment is performed.

[0061]

As explained above, according to the appearance inspection apparatus according to the present invention, a substrate to be inspected which has a part that reflects incident light only on the surface and a part that reflects on the surface and scatters on the lower layer. It has the excellent effect of being able to accurately detect the two-dimensional pattern of the object to be inspected on the surface of the board, even for samples with objects arranged, contributing to the accuracy of visual inspection of multilayer printed wiring patterns, etc. There's a lot to do.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a visual inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the device in FIG. 1;

FIG. 3 is a configuration diagram of an external appearance inspection apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a main part of an appearance inspection apparatus according to a third embodiment of the present invention.

FIG. 5 is a diagram showing the transmittance of a density filter.

FIG. 6 is a light intensity distribution diagram on the light receiving surfaces of PSD22A and PSD22B.

FIG. 7 is a diagram illustrating a main part of an external appearance inspection apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating a main part of an appearance inspection apparatus according to a fifth embodiment of the present invention.

FIG. 9 is a diagram illustrating a main part of an external appearance inspection apparatus according to a sixth embodiment of the present invention.

FIG. 10 is a configuration diagram of main parts of an appearance inspection apparatus according to a seventh embodiment of the present invention.

FIG. 11 is a diagram illustrating a main part of an appearance inspection apparatus according to an eighth embodiment of the present invention.

FIG. 12 is a diagram illustrating problems in the prior art, in which (A) shows a case where there is a problem, and (B) shows a case where there is no problem.

[Explanation of symbols]

10 Sample 10a Substrate 10b Printed wiring patterns 10a1, 10a2 Base layer 10b2 Lower printed wiring pattern 16 fθ lenses 17, 21A, 21B Photodetector 19 Brightness correction circuits 20A, 20B Imaging lenses 22, 22A, 22B PSD 25 Half mirror 26A, 26B Density filter 31 Selector

Claims (7)

[Claims] Claim 1: A light source (14), a part that reflects incident light only on the surface, and a lower layer (10b2) that reflects on the surface.
an optical scanning means (12,
15 to 18), specularly reflected light detection means (20A, 21A) for detecting the intensity of specularly reflected light from the light irradiation point, and scattered light detection means (20) for detecting the intensity of scattered light from the light irradiation point.
B, 21B), a brightness correction means (19) for calculating the linear coupling difference μA−αB (μ and α are positive constants) between the specularly reflected light detected intensity A and the scattered light detected light intensity B, and the linear coupling Difference μA
- an inspection device (23, 24) for inspecting the appearance of a two-dimensional pattern of the object to be inspected based on αB. 2. The scattered light detection means (21B) reflects the light scattered in the opposite direction to the light beam directed toward the sample (10) with a half mirror (25), and detects the intensity of the scattered light. The appearance inspection device according to claim 1, characterized in that: 3. A light source (14), a portion that reflects incident light only on the surface, and a lower layer (10b2) that reflects the incident light on the surface.
an optical scanning means (12,
15 to 18), specular reflection light detection means (20A, 22B, 27) that detects the intensity of specularly reflected light from the light irradiation point, and a specular reflection light detection means (20A, 22B, 27) that collects the reflected light from the light irradiation point and detects the light irradiation point. first height detection means (20A, 22B, 28B) for detecting the height of the light irradiation point; second height detection means (20A, 25, 26A, 22A, 28A) for detecting the height of the light irradiation point through a density filter (26A) arranged at The first
Discrimination means (29, 30) for discriminating whether the light is scattered from the lower layer based on the difference between the height detected by the height detection means and the height detected by the second height detection means; a brightness correction means (31) for correcting the detected intensity of the specular reflection light based on the results; and an inspection means (23) for visually inspecting the two-dimensional pattern of the object based on the corrected detected intensity 24) An appearance inspection device comprising: 4. The first height detection means (20A, 26
B, 22B, and 28B) are arranged so that the reflected light from the light irradiation point is focused, and the higher the height of the light irradiation point is, the lower the transmittance is. The height of the light irradiation point is detected through the increased density filter (26B), and the second height detection means (20A, 25, 26
4. The visual inspection apparatus according to claim 3, wherein the density filter (26A) of each of A, 22A, and 28A) is arranged so that the higher the height of the light irradiation point, the higher the transmittance. 5. The discrimination means (29, 34) includes the first height detection means (20A, 26B, 22B, 28B).
and the second height detection means (20A, 25
, 26A, 22A, 28A) and the detection intensity of the specularly reflected light, it is determined whether the light is scattered from the lower layer or not. Appearance inspection equipment. 6. A light source (14), a part that reflects incident light only on the surface, and a lower layer (10b2) that reflects on the surface.
an optical scanning means (12,
15 to 18), the specularly reflected light from the light irradiation point is focused, and the lower the height of the light irradiation point, the lower the transmittance area, and the concentration increases monotonically in one direction. A first light detection means (20A, 26B, 21B) detects the intensity of the specularly reflected light through a filter (26B), and visually inspects the two-dimensional pattern of the object based on the detected intensity of the specularly reflected light. An appearance inspection device characterized by having inspection means (23, 24). 7. A light source (14), a part that reflects incident light only on the surface, and a lower layer (10b2) that reflects the incident light only on the surface.
an optical scanning means (12,
15 to 18), the specularly reflected light from the light irradiation point is focused, and the lower the height of the light irradiation point, the lower the transmittance area, and the concentration increases monotonically in one direction. A first light detection means (20A, 26B, 21B) that detects the intensity of the specularly reflected light through a filter (26B), and a first light detection means (20A, 26B, 21B) that collects the specularly reflected light from the light irradiation point so that the height of the light irradiation point is Through a density filter (26A), which is arranged so that the higher the transmittance, the lower the transmittance is, the transmittance increases monotonically along one direction.
A second light detection means (20A,
25, 26A, 21A), a division means (36) for calculating a value obtained by dividing the detection intensity by the first light detection means by the detection intensity by the second light detection means, and based on the division result of the division means, A visual inspection device comprising: inspection means (23, 24) for visually inspecting a two-dimensional pattern of the object to be inspected.