JPH0476405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pattern detection method, and particularly to a method for inspecting a wiring pattern of a printed wiring board in which a wiring pattern is formed on an electrically insulating substrate.

In printed wiring boards, wiring patterns made of Cu, etc. are selectively formed on substrates made of polyimide, epoxy resin, ceramics, etc., but as these wiring patterns become finer and denser, the design margins tend to be reduced. Therefore, if there is a defect or bulge in a part of the wiring pattern, or if there is unnecessary conductor residue, the desired circuit characteristics cannot be secured and reliability will be reduced, so it is necessary to inspect for such defects in advance. be.

Therefore, various pattern detection methods have been developed so far, but they are not sufficiently adaptable to the miniaturization and high density, and various methods are also being used for surface treatment of conductor patterns. At the same time, a protective layer made of resin is sometimes applied to the surface of the conductive pattern, and the reality is that there is room for improvement in these areas.

[Conventional technology]

Conventional pattern detection methods generally involve irradiating the circuit board under test with illumination light and using the reflected light to distinguish between the surface of the board and the surface of the conductor.One type of automatic detection device is a laser spot. A scanning method was used.

[Problems to be solved by the invention] As explained above, the conventional device utilizes reflection of irradiated light, so it is fine when the intensity of reflected light between the substrate and the adhered conductor is significantly different, but S/N when the intensity of reflected light from the conductor is the same or similar
The reliability of conductor pattern discrimination is low, and there has been a strong demand for improvement.

[Means for solving problems]

The above problem was solved by focusing on the fact that the light diffusion of the conductor layer made of metal can be ignored compared to the light diffusion of the substrate.
When inspecting defects such as conductive patterns formed on the top surface of a substrate with light diffusing properties, an illumination spot whose at least the center is dark field (non-illumination) is irradiated onto the top surface of the substrate, and the top surface of the substrate is illuminated. A pattern detection method characterized by detecting diffused light in a dark field of a spot irradiation area from the illumination spot irradiation side (top side of a substrate) and detecting whether the projection area is the substrate or a conductor; When inspecting defects such as conductor patterns formed on a diffusive substrate, there is provided an illumination unit that irradiates the substrate with an illumination spot where at least the center part is a dark field, and the reflected light of the irradiation is formed into an image. optical system,
and a detection section provided with a light detection element facing at least the center section at substantially the imaging plane of the reflected light, further comprising a conductor pattern formed on a substrate having light diffusing properties. When inspecting defects such as, for example, an illumination unit that irradiates the substrate with an illumination spot whose center is a dark field, an optical system that forms an image of the reflected light of the irradiation, and an optical system that forms an image of the reflected light, and an optical system that forms an image of the reflected light at approximately the imaging plane of the reflected light. a detection section provided with a photodetection element facing at least the central portion; a circuit for converting the detection signal of the detection section into a binary signal; a memory for recording a logical binary signal of the detection signal; The problem is solved by a pattern detection device characterized by comprising a defect identification circuit that compares a binary signal with the logical binary signal and detects a difference therebetween.

[Effect]

In the above means, the illumination spot is, for example, the first
As shown in Figure A, the central area (dark area) 1b is dark and the surrounding area (clear visual area) 1a is bright.

Therefore, as shown in FIG. When the clear vision periphery 1a illuminates the conductor pattern 3 or a part thereof onto the substrate 2, the projection area of the spot center 1b is dark as shown in FIG. 1D, while the spot periphery 1a ( When a part of the spot periphery 1b) and the center part 1b illuminate the substrate 2, the light in the clear vision periphery 1a of the spot 1 is diffused by the substrate 2, as shown in FIG.
Brighten the projection area of b.

Therefore, if the dark field projection area of the illumination spot is dark, it can be determined that the projection area is on the conductor, and if the dark field projection area is bright, it can be determined that the projection area is on the substrate. The discrimination is not affected by the color tone or surface condition of the substrate 2 and the conductor 3.

〔Example〕

Hereinafter, a plurality of embodiments of the present invention will be sequentially described using the drawings.

FIG. 2 is a side view schematically showing the main structure of the apparatus according to the first embodiment of the method of the present invention, FIG. 3 is a perspective view of the light shielding plate shown in FIG. 2, and FIG. 4 is the same as that shown in FIG. FIG. 5 is a side view for explaining the state in which the illumination spot shown in FIG. An example of the mode of the laser beam used is shown in FIG. 7, which shows an example of the circuit configuration of the defect detection section in the embodiment.

In Fig. 2, 11 is a laser light source that oscillates a TEM ₁₀ mode laser beam, 12 is a laser beam expander, 13 is a photodetector, 14 is a light shielding plate, 15 is a rotating polygon mirror, and 16 is a laser beam splitter. , 17 and 18 are lenses, 19 and 20 are reflecting mirrors, 21 is a TEM ₁₀ mode laser beam, 21a
21b is the bright field part of the laser beam 11, and 21b is the laser beam 2.
1 is a dark field area, 22 is a printed wiring board, 23 is a wiring board having light diffusing properties, and 24 is a metal conductor layer (conductor pattern) patterned on the upper surface of the printed wiring board 23.

In this configuration device, a laser beam 21 oscillated by a laser light source 11 is expanded by an expander 12, reflected by a reflecting mirror 20, transmitted through a beam splitter 16, reflected by a polygonal mirror 15, and reflected by a lens 17 and a reflecting mirror 19. Therefore, the light is focused on a spot and irradiated onto the wiring board 22. Then, the reflected light of the irradiation passes through the opposite direction of the irradiation light, is reflected by the beam splitter 16, and enters the photodetector 13.

However, in the front of the photodetector 13, as shown in FIG.
A light shielding plate 14 of 4a is provided,
When the spot is irradiated on the upper surface of the conductor layer 24 as shown in FIG. , when the spot illuminates the upper surface of the substrate 23 as shown in FIG. The signal is input to the device 13.

In Figure 6, A is the laser beam in TEM ₁₀ mode, B is the laser beam in TEM 01 mode, and C is the laser beam in TEM ₀₁ mode.
The laser beam is in TEM ₁₁ mode, and in each mode, the shaded area is the dark field area, and the unshaded area is the bright field area. It can be used as 21.

In FIG. 5, A is an enlarged cross-sectional view of a part of the printed wiring board 22, B is a detection signal of the photodetector 13 obtained from the cross section, C is a binary signal of the detection signal, and D is the above-mentioned signal. A reading pulse for reading the binarized signal, E is a detection pattern recorded by reading the binarized signal, and F is a reference pattern for determining whether the detection pattern is correct or not. It is configured as shown in the figure.

In FIG. 7, 31 is a circuit that binarizes the detection signal of the photodetector 13, 32 is a reference level for the binarization, 33 is a pulse counter, 34 is a pulse generator, and 35 is a reading pattern 36 and a reference pattern. This is a memory for recording 37.

An example of detecting defects in the conductor layer 24 will be described below with reference to FIGS. 5 and 7.

As shown in FIG. 5, the printed wiring board 22 shown in FIG.
a, 24b, 24c are formed, and the conductor layer 24
conductor layer 24 while a and 24c have the desired width.
In b, a part (defective part) 24d has fallen off.

Therefore, when the spot of the laser beam 21 is scanned across the conductor layers 24a, 24b, and 24c, the detection signal of the photodetector 13 corresponds to the conductor layers 24a, 24b, and 24c, as shown in FIG. It is close to the "0" level, and a large signal characteristic can be obtained at the exposed portion of the substrate 23. However, compared to a signal in which the conductor layers 24a, 24b, and 24c are normal, this signal has a characteristic in which a portion corresponding to the defective portion 24d (the shaded portion in the figure) has fallen off.

Next, an appropriate slice level at which the reference level 32 is generated is input to the binarization circuit 31 and the detection signal is binarized. As shown in FIG. ) is obtained, and the binarized signal is read with the reading pulse shown in FIG. 5D, and the detection pattern 36 of the reading pulse shown in FIG.
A pattern 36 in which the portions corresponding to a, 24b, and 24c are “1” and the portion directly corresponding to the substrate 23 is “0” is recorded in the memory 35, and the reference pattern 37 recorded in advance in the memory 35, that is, the fifth As shown in the figure, by comparison with a reference pattern 37 in which the portions corresponding to the conductor layers 24a, 24b, and 24c are "1" and the directly corresponding portions of the substrate 23 are "0", it is found that there is a defective portion 24d.

FIGS. 8 to 11 are diagrams showing other configuration examples for creating illumination spots applicable to the method of the present invention.

In FIG. 8, reference numeral 41 indicates an all-picture laser beam from a light source (not shown), and 42 indicates a phase structure in which an upper half 42a transmits the laser beam 41 and a lower half 42b shifts the phase of the laser beam 41 by a half wavelength. When the phase plate 42 is irradiated with a laser beam 41 as shown in A, the light transmitted through the phase plate 42 produces a laser beam 41a similar to the TEM ₀₁ mode, as shown in cross section in B.

In FIG. 9, 43 is a light beam from a light source (not shown), 44 is a transparent plate (glass plate) with a black dot 45 adhered to its center, and as shown in A, the transparent plate 4
When the light beam 43 is irradiated onto the light beam 43, the light that has passed through the transparent plate 44 produces a light beam 43a whose center is dark and its surroundings are bright, as shown in the cross section in B.

In FIG. 10, 46 is a light beam from a light source (not shown), and 47 is a rectangular light-shielding layer (black line) in the center.
When the light beam 46 is irradiated onto the light transmitting plate 47 as shown in A, the light passing through the light transmitting plate 47 becomes light with a dark part crossing the center as shown in the cross section in B. A beam 46a is obtained.

In FIG. 11, 92 is a plurality of LEDs supported in two rows by a holder (not shown), and 93 is each LED.
A fly-eye lens (or a fly-eye lens for condensing the illumination lights 96 of the LEDs 92 in two rows on the same predetermined plane)
A cylindrical lens facing the column), and on a plane parallel to the above-mentioned plane, there is a substantially linear dark area 95 sandwiched between a pair of bright field areas 94 formed by the light-condensing column, as shown by a dashed line in the figure. Made.

12 and 13 show examples of the arrangement of photodetecting elements. In the apparatus shown in FIG. 2, the detector 13 may include one photodetecting element facing the through hole 14a; There is also a method of eliminating the light plate 14 and arranging a plurality of photodetecting elements.

In Figure 12, A is a side view, B is a front view,
Reference numeral 97 indicates reflected light from an illumination spot irradiated onto a wiring board (not shown); 98a and 98b indicate light detection elements;
One photodetector element 98b faces the central dark part 97b of the reflected light 97, and two photodetectors 98a face the bright part 97a of the reflected light 97.

Therefore, the output of element 98b is always the same as that of element 98a.
Since the output of the photodetector can be used as a reference for detection, the photodetection element is more accurate than a single detector.

In FIG. 13, reference numeral 99 denotes a photodetecting element configuration in which a plurality of photodetecting elements 99a are arranged in a matrix, and a bright part 97a and a dark part 99 of reflected light 97 are arranged.
A plurality of elements 99a are opposed to each element 7b.

Therefore, in configuration 99, the integrated output, average output, and output distribution of the reflected light bright portion 97a and dark portion 97b can be detected, and has the advantage of contributing to higher functionality of the device.

FIG. 14 is a perspective view schematically showing the main structure of a device according to a second embodiment of the method of the present invention, and FIG. 15 is an enlarged perspective view of a portion of the printed wiring board irradiated by an illumination spot of the device. .

In FIG. 14, which schematically shows an example of the main configuration of a pattern detection device using an illumination spot as shown in FIG. ), 54 is a projection lens, 55 is an imaging lens, 56 is a photodetector having a plurality of photodetecting elements 57 arranged in a straight line, 5
8 is a printed wiring board in which a plurality of metal conductor layers (conductor patterns) 60 are patterned on the upper surface of a light-diffusing substrate 59.

In such a configuration device, the irradiation light 6 of the light source 51
1 forms a projected image of the black line 53 written on the transparent plate 52 on the upper surface of the wiring board 58. At this time, black line 53
Although the image of the black line 53 is dark on the upper surface of the conductor layer 60, in the portion projected onto the upper surface of the substrate 59, light from the bright field portion of the black line 53 is reflected as shown in FIG. diffuses into the substrate 59, the black line 53
The image becomes unclear. Therefore, the imaging light 62 passing through the imaging lens 55 is detected by the photodetector 56, and the detection signal is processed in the same manner as in the embodiment shown in FIG. 2, thereby making it possible to detect defects in the conductor layer 60.

In the embodiment shown in FIG. 14, the black line 53
is used, but it is also possible to use the aforementioned TEM ₁₀ mode laser beam, TEM ₀₁ mode laser beam, or laser beam using the phase plate 42, and the method of the present invention can also be used. As a third embodiment of the present invention, there is an apparatus configuration using a hologram lens as shown in FIG. 16, and as a fourth embodiment of the method of the present invention there is an apparatus configuration using a cylindrical lens as shown in FIG.

The first figure uses the same symbols for the same parts as in Figure 14.
In Figure 6, 65 is a laser light source, 66 is a laser beam expander, 67 is a laser beam splitter, 68 is a reflecting mirror, 69 and 70 are hologram lenses, 71 is an imaging lens, and 72 is a plurality of laser beams. This is a photodetector in which detection elements 73 are arranged in a straight line.

In such a device, an oscillated laser beam 74 from a laser light source 65 is expanded by an expander 66 and transmitted through a splitter 67 into a laser beam 74a.
is formed into a linear shape by the hologram lens 69 and illuminates the wiring board 58, and the splitter 67 and the reflecting mirror 68
The laser beam 74b reflected by the hologram lens 70 becomes linear and is irradiated onto the wiring board 58.

However, the laser beams 74a and 74b are irradiated in parallel on the wiring board 58 with an interval corresponding to the projected image of the black line 53, and the light diffusion into the dark area created by the interval is caused by the imaging lens 71. It is detected by a photodetector 72. Therefore, the detection signal is
Defects in the conductor layer 60 formed on the wiring board 58 can be detected by processing in the same manner as in the illustrated embodiment.

In addition, in FIG. 16, the laser beams 74a, 74
b are arranged to intersect above the wiring board 58, but this is done in consideration of the fact that the sharpness of the image will be impaired by the linearly reflected light of the laser beams 74a and 74b.

The first part uses the same reference numerals for the same parts as in Fig. 16.
In FIG. 7, 75 and 76 are cylindrical lenses, and a laser beam 74 emitted from a laser light source 65 is expanded by an expander 66. The laser beam 74d transmitted through the splitter 67 and reflected by the pair of reflecting mirrors 68 is transmitted through the cylindrical lens 74.
6, the light becomes linear and is irradiated onto the wiring board 58. On the other hand, the laser beam 74c reflected by the splitter 67 and reflected by the reflecting mirror 68 is converted into a linear shape by the cylindrical lens 77 and irradiated onto the wiring board 58.
The irradiation of the laser beams 74c and 74d is applied to the wiring board 5.
8 are parallel to each other at a distance corresponding to the projected image of the black line 53, and the light diffusion in the dark area created by the distance is detected by the photodetector 72 via the imaging lens 71. Therefore, the detection signal is processed in the same manner as in the embodiment shown in FIG.
defects can be detected.

Figure 18 is Figure 2, Figure 14, Figure 16, Figure 1.
8 is a system diagram showing a configuration example of an automatic inspection system for the device shown in FIG. 7. FIG.

The 18th figure uses the same reference numerals for parts common to the previous figure.
In the figure, 78 is an inspection logic circuit, 79 is a defect determination circuit, 80 is a defect information output, and 81 is a wiring board 22.
Or a stage equipped with 58 and capable of X-Y movement,
82 is a driver for operating the stage 81; 83;
is the controller.

In such an automatic inspection system, the arrows in the figure indicate the transmission directions of information signals and control signals, and the controller 83 controls the detection pattern 36, the reference pattern 37, the inspection logic circuit 78, and the defect determination circuit based on information from the defect determination circuit 79. 79, controlling the operation of defect information output 80 and stage driver 82;
By moving the stage 81, the irradiation light scans over the entire surface of the wiring boards 58 and 22, and the presence or absence of a defect, its position, and size are detected.

FIG. 19 is a perspective view schematically showing the main configuration of a device that uses two light sources with different wavelength bands as a fifth embodiment of the method of the present invention to detect the defect and also detect surface information of the detected portion; Figure 20 is 19th
21 is a diagram showing various signals to explain an example of defect detection in the device shown in FIG. 19, and FIG. 22 is a configuration example of an automatic inspection system for the device shown in FIG. 19. FIG.

No. 19 using the same reference numerals for parts common to the previous figure
In the figure, 85, 86, and 87 are optical filters, and the filters 85 to 87 are filters in which the transmittance characteristics of the filters 85 and 86 and the transmittance characteristics of the filter 87 do not overlap, as shown in FIG. 20, for example. . Then, the filter 86, the lens 54, the first
Laser light made into a linear shape by a cylindrical lens 73 is irradiated diagonally from above to the black line image of the transparent plate 52 that passes through the splitter 67 and is projected onto the wiring board 58 from almost directly above so as to overlap.

Then, the reflected image of the irradiated light is reflected by the first splitter 67, passes through the reflecting mirror 68 and lens 71, and is reflected by the second splitter 67.The white light component transmitted through the filter 87 is transmitted to the photodetector. 56
The laser beam component of the reflected image that has passed through the second splitter 67 and passed through the filter 85 having the same characteristics as the filter 86 is input to the photodetector 72 .

In the device having such a configuration, the black line image is formed by the conductor layer 6.
The part projected onto the substrate 59 becomes brighter due to the diffused light, and this situation is detected by the photodetector 56, and the obliquely irradiated linear laser light becomes clear in the part projected onto the conductor layer 60. The area projected onto the substrate 59 becomes brighter due to the diffused light, and the unevenness of the irradiated surface becomes a shadow that is detected by the photodetector 72.

In FIG. 21, A is an enlarged cross-sectional view of a part of the printed wiring board 58 on which the conductive layer 60 is formed and a plurality of metal particles 88 have adhered to the board 59, and B is a photodetector obtained from the cross section. C is the detection signal of the photodetector 72 obtained from the cross section, D is the binary signal of the detection signal of the photodetector 56, E is the detection signal of the photodetector 72 The digitized signal, F, is a logical product that is a noise-free surface information signal by using the binary signal (D) as a strobe signal and the binary signal (E) as a strobe signal. As shown in the figure.

The second figure uses the same symbols for the same parts as in Figure 18.
In Figure 2, 89 is a binarization circuit, and 90 is an AND
The circuit 91 is a surface information pattern.

In such an automatic inspection system, the arrows in the figure indicate the transmission direction of signal information and control signals, and the controller 83 controls the inspection logic circuit 78, the defect judgment circuit 79, the defect information output 80, and the stage based on information from the defect judgment circuit 79. By controlling the operation of the driver 82 and moving the stage 81, the wiring board 2
The irradiated light is scanned over the entire surface of 2, 58, and the surface condition including the presence or absence of defects, their position, size, and presence of dust is determined from the binarized signals and AND signals shown in Figure 21 D, E, and F. It will be detected.

FIG. 23 is a side view schematically showing the main structure of an apparatus according to a sixth embodiment of the method of the present invention.

In FIG. 23, in which the same reference numerals are used for parts common to FIGS. The wiring board 5
8 on the top surface. Then, while the projected image is dark on the top surface of the conductor layer 60, the portion projected onto the top surface of the substrate 59 becomes bright and the image becomes unclear.

Therefore, through the projection lens 17, the rotating polygon mirror 15, and the light shielding plate 14 with a transparent hole 14a in the center,
The projected image is detected by a photodetector 13, and a second
As explained in connection with the illustrated embodiment, defects in the conductor layer 60 can be detected by processing the detection signal.

The above embodiment is a method and apparatus for detecting defects in a pattern by comparing a detection pattern with a standard pattern, but other comparison means include a mutual comparison method in which multiple patterns are simultaneously detected and mutually compared; It should be noted that feature extraction methods that utilize pattern features (for example, conductor width and airspace width) and combination methods thereof can be used in the present invention to detect defects in patterns.

〔Effect of the invention〕

As explained above, the method and apparatus of the present invention take advantage of the fact that the light diffusivity of the conductor formed on the substrate is negligibly weak compared to the light diffusivity of the substrate, and eliminates dimensional defects in the conductor layer. Furthermore, it has a remarkable effect in making it possible to accurately detect defects in the surface shapes of substrates and conductor layers, and has greatly contributed to higher density and higher reliability of wiring on wiring boards.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the light diffusion of an illumination spot irradiated onto a wiring board, FIG. 2 is a side view schematically showing the main structure of the apparatus according to the first embodiment of the method of the present invention, The figures are a perspective view of the light-shielding plate shown in Fig. 2, Fig. 4 is a side view for explaining the state in which the illumination spot shown in Fig. 2 illuminates the test board, and Fig. 5 is a side view of the light shielding plate shown in Fig. 2.
The figure is a diagram showing various signals etc. for explaining an example of defect detection in the embodiment, FIG. 6 is a diagram showing an example of a laser beam mode used in the embodiment, and FIG. 7 is a defect detection section in the embodiment. Figures 8 to 11 are diagrams showing other configuration examples for creating illumination spots that can be applied to the method of the present invention, and Figures 12 and 13 are examples of arrangement of photodetecting elements. figure,
FIG. 14 is a perspective view schematically showing the main structure of an apparatus according to a second embodiment of the method of the present invention, FIG. FIG. 16 is a side view of an apparatus using a hologram lens as a third embodiment of the method of the present invention, FIG. 17 is a side view of an apparatus using a cylindrical lens as a fourth embodiment of the method of the present invention, and FIG. 18 Figure 2, Figure 14, Figure 16
17 is a system diagram showing an example of the configuration of an automatic inspection system for the device shown in FIG. A perspective view schematically showing the main configuration of a device that also detects surface information of a part, FIG. 20 is a characteristic diagram of the filter shown in FIG. 19, and FIG. 21 explains an example of defect detection in the device shown in FIG. 19. Diagram showing various signals etc. for
The figure is a system diagram showing an example of the configuration of an automatic inspection system for the device shown in FIG. 19, and FIG. 23 is a side view schematically showing the main configuration of the device according to the sixth embodiment of the method of the present invention. In the figure, 1, 21, 41, 41a, 4
3, 43a, 46, 46a, 61, 62, 74,
74a, 74b, 74c, 74d, 96 are luminous fluxes,
1a, 21a, 97a are clear vision parts, 1b, 21b,
97b is the dark part, 2, 23, 59 is the substrate, 3, 2
4, 24a, 24b, 24c, 60 are conductor layers;
4, 22, 58 are wiring boards, 11, 51, 57, 6
5 is a light source, 12, 66 is a light beam expander, 13, 56, 72 is a photodetector, 14 is a light shielding plate, 14a is a through hole, 16, 67 is a light beam splitter, 24d is a defect, 31, 89 is a binarization circuit, 42 is a phase plate, 47, 52 is a transparent plate, 48,
53 is a black line, 69 and 70 are hologram lenses, 7
9, 98a, 98b, 99a are photodetecting elements; 7
6, 77 are cylindrical lenses, 85, 86,
87 is a filter, 92 is an LED, and 93 is a fly's eye lens.

Claims (1)

[Scope of Claims] 1. When inspecting a defect such as a conductor pattern formed on the upper surface of a substrate having light diffusing properties, an illumination spot having a dark field at least in the center is irradiated onto the upper surface of the substrate, In the illumination spot irradiation area on the top surface, the diffused light is directed to the dark field projection area at the center, and the light passing through the light shielding plate is provided with a through hole corresponding to the dark field projection area at the center, and the light passing through the through hole in the light shielding plate is 1. A pattern detection method, comprising: detecting with a photodetector, and detecting whether the dark field projection area is the substrate or the conductor depending on whether the diffused light is detected. 2. The pattern detection method according to claim 1, wherein the dark field of the illumination spot is in the form of a black dot at the center of the spot. 3. The pattern detection method according to claim 1, wherein the dark field of the illumination spot is a linear shape having a length in one direction passing through the center of the spot. 4. When inspecting defects in a conductive pattern, etc. formed on the top surface of a substrate having light diffusing properties, an illumination unit that irradiates the top surface of the substrate with an illumination spot whose center portion is a dark field, and reflected light of the irradiation. an optical system for forming an image of the reflected light, and a detection unit provided with a photodetection element that detects an image of at least a dark field projection area at the center of the illumination spot on substantially the imaging plane of the reflected light. Pattern detection device. 5 A circuit for converting the detection signal of the detection unit into a multi-value signal, a memory for recording a logical multi-value signal of the detection signal, and comparing the detected multi-value signal with the logical multi-value signal and detecting the difference. 5. The pattern detection device according to claim 4, further comprising a defect identification circuit for detecting a defect. 6. The above-mentioned claim 6, characterized in that the light detection element is arranged to face the reflected light through a light-shielding plate with a transparent hole corresponding to the central dark field projection area of the illumination spot. The pattern detection device according to item 4 or 5. 7. The pattern according to claim 4 or 5, characterized in that at least two of the photodetecting elements are arranged to face each other in a clear vision area and a dark vision area of the reflected light. Detection device. 8. The pattern detection device according to claim 4 or 5, wherein a plurality of the photodetecting elements are arranged in a matrix to face the reflected light. 9. The pattern detection device according to claim 4 or 5, wherein the irradiation light spot is a laser beam in a dark field mode at least in the center thereof. 10 The above-mentioned claim is characterized in that the irradiation light is a laser beam, and the irradiation spot is created by inserting a phase plate in the middle of the optical path to change the phase of a half region of the irradiation laser beam by half a wavelength. The pattern detection device according to the range 4 or 5. 11 The dark field of the irradiation spot is linear with a length in one direction passing through the center, and the linear dark field is created by the irradiation light passing through a transparent plate coated with a black line. The pattern detection device according to claim 4 or 5, characterized in that: 12. The dark field of the irradiation spot is linear with a length in one direction passing through the center, and the linear dark field is defined by the interval between two parallel and substantially linear illumination lights. Claim 4
6. The pattern detection device according to item 5. 13. The dark field of the irradiation spot is in the form of a dot in the center, and the dot-like dark field is created by the irradiation light passing through a transparent plate covered with a sunspot. The pattern detection device according to scope 4 or 5. 14. The pattern detection device according to claim 4 or 5, characterized in that a plurality of the detection elements are arranged opposite to the linear dark field. 15 forming a first illumination spot having the linear dark field with light in a first wavelength band; forming a second linear illumination spot with light in a second wavelength band; The spot illuminates a dark field projection area of the first illumination spot, and strobes the detection signal detected at the second illumination spot by using the detection signal detected at the first illumination spot as a strobe signal. A pattern detection device according to claim 4 or 5. 16. Claim 4, wherein the illumination spot having the linear dark field is two parallel linear laser beams spaced apart by an appropriate distance, and the distance is defined as the dark field. The pattern detection device according to item 5. 17. Claim 5, wherein the multi-level signal, the logical multi-level signal, and the detected multi-level signal are respectively a binary signal, a logical binary signal, and a detected binary signal. The pattern detection device described in Section.