JPH0875661A - Defect detecting equipment - Google Patents

Abstract

PURPOSE: To realize a plurality of illumination methods by one optical system, and exact classification of defects and to realize a judging function similar to the human ability of inspection by visual observation. CONSTITUTION: In the equipment for detecting a defect by casting an illuminating light on the surface S of an object of inspection whereon a lattice pattern is formed, an illuminating optical system 2 which casts on the surface of the object of inspection the illuminating light in the direction intersecting the aforesaid pattern perpendicularly in a prescribed sphere of illumination of the surface from an oblique position and converges a diffracted light generated on the surface to a prescribed position is provided. This equipment has image input means 3 and 4 which pick up an image of the aforesaid sphere of illumination from a position being apart from the aforesaid surface of the object of inspection in such a degree as not to be illuminated by the illuminating light and excluding the position of convergence of the diffracted light and/or the point of convergence thereof, and a display means 7 which visualized image signals of a diffracted light zone outputted from the image input means 3 and 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass or silicon wafer on which a wiring of about 0.3 to 20 .mu.m is regularly engraved in a grid pattern, and scratches, stains, film thickness unevenness, and shot shift of a stepper on a liquid crystal substrate or IC wafer. , Defect detection device for visual inspection to inspect dust, etc.

[0002]

2. Description of the Related Art At present, in visual inspection of liquid crystal substrates and IC wafers, illumination light of various luminous fluxes is irradiated from various angles, and an observer observes a microscope image while rotating or rocking the subject. Often done by direct visual inspection.

The principle of defect detection often differs depending on its type. For detecting defects such as dust, protrusions, and scratches on the substrate surface, scattered light emitted from the defects on the substrate surface by light irradiation can be used.

The defect of the shot shift is detected by detecting the disturbance of the spectral fringes due to the pattern deformation of the subject by comparing with the spectral fringes generated by the diffracted light generated from the pattern edge by irradiating the regular pattern with the inspection light. Can be found. Shot misalignment is a phenomenon in which a newly created pattern is misaligned with the underlying pattern due to a stepper movement error. In addition, the spectral fringe of diffracted light is a spectral action of light by a diffraction grating, and is a phenomenon in which white light is dispersed into blue light from red light. Generally, in a panel with a diagonal of 10 ', one shot is completed by moving four shots that are 1/4 the size of the panel, but if there is one shot shift, 1/4 of the panel will be colored. Seems to change.

Defects in resist film thickness unevenness and scattering are
It is possible to detect by utilizing the disturbance of the equal-thickness interference fringes.
Further, a defect called a stain can be detected by utilizing the fact that it has a high light absorption property, which refers to a portion darker than the surrounding background color.

In a visual inspection by an observer, many of these various defects are rotated and rocked on the substrate under the above-mentioned illumination to change the eye positions as shown in FIGS. 13 (a) to 13 (c). It was detected once.

FIG. 13A shows eye positions suitable for detecting dust and protrusions on the substrate surface. The angle between the surface of the substrate and the inspection light is made small, and the eyes are at a position where the reflected light beam reflected by the inspection light from the substrate is slightly removed.

FIG. 13B shows eye positions suitable for observing diffracted light. Place your eyes facing the board,
It is preferable to increase the angle between the substrate surface and the inspection light.
FIG. 13C shows eye positions suitable for observing interference fringes. The inspection light has an angle close to a right angle with the substrate surface, and the eyes are placed in the reflected light flux.

By the way, recently, with the quantification of defects, labor saving of inspection, and speeding up of the inspection, there has been a strong demand for automating the appearance inspection, and several devices have been proposed in order to meet such demand. (JP-A-5-233202). Such a defect detection device has two types, one that focuses on detecting a defect that cannot be detected by the human eye and one that focuses on providing a detection capability equivalent to that of human visual observation. Classified into types. In particular, the latter type wants to apply the defect judgment based on the eyes to each manufacturing process from the background that the defect inspection so far has been done visually, and thus wants to manage the manufacturing process with an apparatus that can make the same defect judgment as the eyes. Development is proceeding from the viewpoint.

[0010]

However, as described above, many kinds of defects are detected by various illumination methods in the visual observation of human beings, but many defect detection devices at present have one defect.
Since it has only one illumination method, it cannot satisfy the detection principles of scattering, diffraction, and interference at the same time, and can detect only defects that can be detected by any one of the detection principles.
For this reason, it has not been possible to sufficiently cope with an application in which several types of defects are detected and the causes of generation of all types of defects are respectively fed back to the manufacturing process in which they occur.

Further, when the defect type is judged by image processing, it is generally estimated from four factors of large, small, bright, and dark of the defect, but only one illumination method provides sufficient information depending on the defect. There is a problem that you can not get.

The present invention has been made in view of the above circumstances, and a plurality of illumination methods can be realized by one optical system,
It is an object of the present invention to provide a defect detection apparatus capable of accurately classifying defect types and realizing a judgment function similar to the inspection ability by human visual observation.

[0013]

The present invention has taken the following means in order to achieve the above object. The present invention corresponding to claim 1 is a defect detection apparatus for irradiating the surface of a subject on which a regular grid pattern is formed with illumination light to detect a defect of the subject, which is oblique to the surface of the subject. An illumination optical system for irradiating a predetermined illumination range on the surface of the subject with illumination light in a direction orthogonal to the pattern from the position to converge the diffracted light generated on the surface of the subject to a predetermined position, and the illumination light is not turned off. Image input means for photographing the illumination range from a position other than the convergence surface of the diffracted light and a position other than the convergent position of the diffracted light, which is a position far from the surface of the subject, and is output from the image input means. A display means for visualizing an image signal in the diffracted light band is provided.

According to a second aspect of the present invention, the illumination optical system includes a light source, and a convex lens that converts light emitted from the light source into convergent light and irradiates the illumination range. The present invention corresponding to claim 3 provides the illumination optical system,
A light source and an irradiation lens that converts the light emitted from the light source into an afocal parallel light flux and irradiates the illumination range, and between the image input unit and the subject surface, An imaging lens having a diameter corresponding to the illumination range and converging a parallel light flux incident from the illumination range to the light receiving portion of the image input means is arranged at a position far from the surface of the subject so as not to block the illumination light. There is.

According to a fourth aspect of the present invention, the image input means includes a first image pickup means arranged at a convergent position of the diffracted light and a second image pickup means arranged near the convergent position of the diffracted light. And means.

According to a fifth aspect of the present invention, in a defect detection apparatus for illuminating an object surface having a plurality of straight lines continuous in at least one direction with illumination light to detect a defect of the object, a light source. And a convex lens that converges the light emitted from the light source, and irradiates a first illumination light in a direction orthogonal to the straight line to a predetermined illumination range on the subject surface from a position oblique to the subject surface. A first illumination optical system, a second illumination optical system for irradiating the illumination range with second illumination light obliquely intersecting the straight line from a position oblique to the surface of the subject, and the converging optical system. A configuration comprising image input means for photographing the illumination range from a position other than the convergent position of the diffracted light and a position other than the convergent position of the diffracted light, and a display means for visualizing an image of the illuminated range output from the image input means. did.

According to a sixth aspect of the present invention, there is provided a defect detection device for irradiating the surface of a subject, on which a regular grid pattern is formed, with illumination light to detect defects in the subject. On the other hand, a first illumination optical system for irradiating a predetermined illumination range on the surface of the subject with a first illumination light in a direction orthogonal to the pattern, and the illumination from a position oblique to the surface of the subject. A second illumination optical system that irradiates a second illumination light that obliquely intersects the pattern in a range, and is arranged at a position far from the subject surface to the extent that the first and second illumination lights are not cut off; A converging optical system for converging the diffracted light generated on the surface of the subject by the first illumination light and a converging position of the diffracted light by the converging optical system and / or a position other than the converging position of the diffracted light is imaged in the illumination range. Image input means and the image The image of the illumination range to be output from the input means is configured to include a display means for visualizing.

According to a seventh aspect of the present invention, the first illumination optical system includes a light source, and an illumination lens that converts the light emitted from the light source into an afocal parallel light flux and irradiates the illumination range. And the converging optical system is arranged between the image input means and the surface of the subject at a position distant from the subject surface to the extent that the first and second illumination lights are not blocked. The image forming lens has a diameter corresponding to the illumination range and converges the parallel light flux incident from the illumination range to the light receiving portion of the image input unit.

The present invention corresponding to claim 8 is characterized by comprising an interference illumination optical system for performing interference illumination on the illumination range of the sample surface. According to a ninth aspect of the present invention, in the interference illumination optical system, a half mirror provided between a light receiving portion of an image input unit and a sample surface, and the image formation on the optical axis bent by the half mirror. And a diffused light source provided at the focal position of the lens and satisfying the numerical aperture of the imaging lens.

[0020]

The present invention has the following effects by taking the above measures. According to the present invention corresponding to claim 1, the illumination optical system irradiates the illumination light in the direction orthogonal to the pattern from a position oblique to the subject surface to a predetermined illumination range on the subject surface. The diffracted light generated on the surface of the subject is converged at a predetermined position to form a band of spectral fringes of the diffracted light. By arranging the lens pupil of the camera that constitutes the image input means in the band of diffracted light thus formed, the generation of diffracted light at each part of the subject can be visualized and displayed. Further, if the illumination range on the sample surface is photographed at a point other than the convergent point of the diffracted light, scattered light generated by dust, scratches, etc. on the sample surface appears in the photographing screen. This is the same principle as dark field observation. Therefore, two illumination methods of diffracted light and scattered light can be realized with one illumination optical system.

According to the second aspect of the present invention, since the illumination optical system generates the convergent light by the convex lens and irradiates it to the illumination range on the sample surface, the diffracted light generated on the sample surface condenses the illumination light. A band of spectral fringes is formed in a direction orthogonal to the subject through the position.

According to the present invention corresponding to claim 3, the light emitted from the light source is converted into an afocal parallel light flux by the irradiation lens and is irradiated onto the illumination range of the sample, and the diffracted light generated on the sample surface is combined. It is converged by the image lens on the light receiving portion of the image input means. Diffracted light does not converge by irradiation with a parallel light flux. Since the diffracted light is generated at different angles for each wavelength within the plane of the irradiation light, it is necessary to converge these by the imaging lens.

According to the present invention corresponding to claim 4, an image of an illumination range including a band of diffracted light is photographed by the first imaging means arranged at the converged position of diffracted light, and the converged position of diffracted light is obtained. An image of the illumination range including the scattered light information is taken by the second image pickup means arranged in the vicinity.

According to the present invention corresponding to claim 5, the convergent illumination light in the direction orthogonal to the straight line from the position oblique to the surface of the subject to the predetermined illumination range of the subject surface is the first illumination optical system. Is illuminated by. The diffracted light generated on the surface of the subject is converged by itself to form a band of diffracted light at a predetermined position. The generation state of the diffracted light of the subject is visualized and displayed by the image input means arranged in the band of the diffracted light thus formed.

Further, the second illumination optical system irradiates the second illumination light which obliquely intersects the pattern from the position oblique to the surface of the subject to the illumination range. When the sample surface is illuminated from the direction oblique to the pattern, dust on the sample surface, as compared with the case of illuminating from the orthogonal direction (when using the first illumination light),
The efficiency of detecting defects such as protrusions is increased. Further, by alternately driving the first illumination optical system and the second illumination optical system, it is possible to acquire both the image by the diffracted light and the image by the scattered light at the converging position of the diffracted light.

According to the present invention corresponding to claim 6, illumination light in a direction orthogonal to the pattern from a position oblique to the surface of the subject to a predetermined illumination range of the subject surface is emitted by the first illumination optical system. Is irradiated. The diffracted light generated on the surface of the subject is converged at a predetermined position by the converging optical system to form a band of diffracted light. The generation state of the diffracted light on the surface of the subject is visualized and displayed by the image input means arranged in the band of the diffracted light thus formed.

Further, the second illumination optical system irradiates the second illumination light obliquely intersecting the pattern from the position oblique to the surface of the subject to the illumination range. When the sample surface is illuminated from the direction oblique to the pattern, dust on the sample surface, as compared with the case of illuminating from the orthogonal direction (when using the first illumination light),
The efficiency of detecting defects such as protrusions is increased. Further, by alternately driving the first illumination optical system and the second illumination optical system, it is possible to acquire both the image by the diffracted light and the image by the scattered light at the converging position of the diffracted light.

According to the present invention corresponding to claim 7, the first
1st parallel light flux was formed by the illumination lens of the illumination optical system of
Is irradiated onto the illumination range of the sample, and the diffracted light generated on the sample surface is converged on the light receiving section of the image input means by the imaging lens forming the converging optical system.

According to the present invention corresponding to claim 8, the illumination range on the sample surface is illuminated by the interference illumination optical system. If the subject has a two-layer structure of, for example, a glass substrate and a thin film formed on the glass substrate, interference fringes are formed due to the phase difference between the front surface reflection and the back surface reflection of the thin film. This interference fringe is photographed by the image input means. Therefore, by switching between the illumination optical system or the first illumination optical system and the interference illumination optical system and capturing the image by each illumination method, each inspection by diffraction, scattering, and interference becomes possible.

According to the present invention corresponding to claim 9, the image of the diffused light source is reflected by the half mirror and projected onto the illumination range of the sample surface. Here, the theory of converging the diffracted light generated by irradiating the specimen surface with the illumination light into a band will be described. When the illumination light is applied to the surface of the substrate on which the grid-like wiring is engraved at a right angle to the wiring from obliquely above, 0th to n
The next diffracted light is generated in the direction shown in FIG. At this time, the diffraction angle of the diffracted light is changed according to the pitch and the wavelength of the wiring according to the formula shown in FIG.

If the incident light is white light, a white paper is arranged with respect to the diffracted light as shown in FIG. 8A, and red to blue diffracted light is placed on the white paper as shown in FIG. 8B. Lines are formed.

Further, as shown in FIG. 9A, when incident light forming an angle of 45 degrees with the wiring on the surface of the substrate is irradiated obliquely from above, the 0th-order reflected light falls within a plane formed by the incident light and the substrate. However, the diffracted light is bent like a to c rather than the incident light plane.

Next, let us consider a case where the convergent light beam is made incident obliquely from above at a right angle to the wiring direction of the substrate. At this time, since the diffracted light and the 0th-order reflected light are close to the same plane until the convergence angle is about 15 degrees, the difference between the diffracted light and the 0th-order reflected light is neglected and shown in FIGS. 10 and 11. As shown in FIG. 11, a knife-edge-shaped light beam is formed by the diffracted light through the converging point of the 0th-order reflected light. The knife-edge-shaped luminous flux (spectral fringe band-shaped luminous flux) includes diffracted light from the entire illumination field.
If a TV camera is arranged in this band-shaped light flux, information on the substrate surface can be obtained.

[0034]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a defect detection device according to a first embodiment of the present invention. Reference numeral 1 shown in the figure is a stage, and the sample S is placed on the stage 1. Stage 1 is orthogonal 2
It consists of an XY stage that can move in any direction. Sample S is
It is a liquid crystal substrate or an IC wafer in which innumerable wirings are regularly engraved in a grid pattern on a glass or silicon substrate.

The defect detecting apparatus of this embodiment includes a first illumination optical system 2 for irradiating a first illumination light which converges from an obliquely upper side of the surface of the sample S to an illumination range of the surface of the sample S from a direction orthogonal to the wiring. I have it.

The position above the sample S, which is distant from the sample surface to the extent that the first illumination light is not blocked, and the diffracted light generated on the sample surface converges in a band shape (the focal position of the irradiation lens 13). ) Is provided with a first TV camera 3 and a second TV camera 3 is provided near the band-shaped convergence position and outside the convergence point of the diffracted light.
The TV camera 4 of is arranged. Actually, it is arranged at a position near the vertical direction of the paper surface.

An image processing device 5 is connected to the video output terminals of each of the TV cameras 3 and 4, and a computer 6 and a monitor 7 as a display means are connected to the image processing device 5.

The first illumination optical system 2 has a light source 11 which emits first illumination light having high emission intensity and various wavelengths,
A condenser lens 12 that converts the first illumination light emitted from the light source 11 into an afocal light flux, and a parallel light flux that is emitted from the condenser lens 12 is converted into convergent light, which is applied to a predetermined irradiation range of the sample S. The irradiation lens 13 is included.

It is assumed that a metal lamp, which is a kind of mercury lamp, is used as the light source 11. Also,
The larger the irradiation range of the irradiation lens 13, the more preferable. However, if the irradiation range is large, the lens diameter becomes large or the amount of light reduction increases, so if the sample S is a substrate of 360 mm × 460 mm, it is divided into four. Range (180mm
The diameters of the condenser lens 12 and the irradiation lens 13 are set so as to be (230 mm). Specifically, the condenser lens 12,
The diameter of the irradiation lens 13 is set to about 400 mm, and the focal length of the irradiation lens 13 is set to 1000 mm to 1300 mm.
These lenses may be either glass or acrylic, and Fresnel lenses can be substituted.

When the sample S is divided into four and inspected, the drive control section of the stage 1 is set in advance so that the four inspection positions of the sample S are automatically moved to the irradiation range. The camera lens provided in the first and second TV cameras 3 and 4 is a zoom lens having a focal length of about 20 mm to 50 mm,
It is used to adjust the camera field of view to the size of the sample S, and to eliminate moire fringes caused by the sample S having a lattice pattern.

Next, the operation of this embodiment configured as described above will be described. The first illumination light emitted from the light source 11 is converted into a parallel light flux by the condenser lens 12, further converted into convergent light by the irradiation lens 13, and is incident on a predetermined irradiation range of the sample S.

When the first illumination optical system 2 illuminates the sample S with the first illumination light composed of the converged light in this way, as shown in FIG.
The diffracted light generated by the wiring pattern engraved in a lattice shape on the sample surface as shown in 0 (a) and (b) passes through the focal position of the irradiation lens 13 and converges in a band shape. An image of the surface of the subject is captured by the first TV camera 3 arranged at the band-shaped convergence position of the diffracted light. This image contains the generation status of the diffracted light at each part on the surface of the subject and is converted into an electric signal and input to the processing device 5.

If dust, scratches, etc. are present in the irradiation area of the sample S, scattered light is generated at that portion. An image including scattered light is acquired by photographing the illumination range with the second TV camera 4 arranged so as to be displaced from the band-shaped converging position of the diffracted light.

Although the image from the spectral fringe band also contains scattered light from scratches and the like, the detection efficiency decreases because the diffracted light and the scattered light overlap. The electric signal including the information on the scattered light detected by the second TV camera 4 is input to the image processing device 5.

The image processing apparatus 5 has a plurality of filtering processing functions suitable for detecting various defects and a defect position detecting function. The image processing device 5 is the first TV
When the output signal of the camera 3 is fetched, the filtering process corresponding to the diffracted light inspection is performed to detect the defect. When a defect is detected, the size and brightness of the defect are obtained by image processing, and the type of defect is discriminated from the four factors. If a defect is detected only by a certain process, the content of the process and the illumination method are added as new factors for the determination to the above four factors, and then the type of the defect is determined. Further, when the output signal of the second TV camera 4 is taken in, the filtering process corresponding to the scattered light inspection is performed to detect the defect. In particular, if the size and defect of the defect can be detected by image-processing the output of the second TV camera 4, it can be determined that "large" is a scratch and "small" is dust. The image processing result is output to the computer 6 and the monitor 7.

On the monitor 7, original images and processed images of the first and second TV cameras 3 and 4 are displayed. Further, the position coordinates of the defect found by the observer on the screen can be directly input to the image displayed on the monitor 7 by using a pointing device such as a mouse.

The computer 6 saves the image processing result thus obtained in a predetermined storage unit and transfers it to an external device that manages the manufacturing process in order to feed back the defect factor to the manufacturing process.

As described above, according to this embodiment, the first illumination light which converges from the direction orthogonal to the wiring is irradiated onto the illumination range of the sample S from diagonally above the surface of the sample S, and the first illumination light is emitted above the sample S. The first TV camera 3 is arranged at a position far away from the sample surface to the extent that the illumination light of No. 1 is not converged, and the diffracted light generated on the sample surface converges in a band shape. There is a second TV outside the convergence point of the diffracted light.
Since the camera 4 is arranged, the defect inspection can be performed from the diffracted light of the entire irradiation range of the sample surface according to the output of the first TV camera 3, and the scattered light according to the output of the second TV camera 4. Defect inspection becomes possible. Therefore, only one illumination optical system 2 can inspect two defects by diffracted light and scattered light.

According to this embodiment, since the first TV camera 3 and the second TV camera 4 are arranged close to each other, the sample images captured by the two TV cameras are similar to each other, and the defect coordinates It has the advantage of being easy to recognize.

Although two TV cameras are provided in the above embodiment, if one TV camera is configured to be movable between the band-shaped converging position of diffracted light and the outside of the converging point of diffracted light, one TV camera is provided. With this TV camera, the same inspection as in the above embodiment can be performed.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the first illumination light emitted from the light source 11 is brought into an afocal state by the convex lens 21 having a diameter corresponding to the irradiation range, and is obliquely above the sample surface and is reflected on the sample surface at an angle orthogonal to the wiring. Make it incident. Further, the imaging lens 22 having a diameter sufficiently larger than the inspection range is arranged at a position directly above the sample S and not blocking the first illumination light, and the first lens is provided near the focus of the imaging lens 22. TV
The eyes of the camera 3 are coming. Also, the first TV
The second TV camera 4 is arranged at a position orthogonal to the paper surface close to the camera 3. The image processing device 5, the computer 6 and the monitor 7 are connected to the video output terminals of the first and second TV cameras 3 and 4 as in the first embodiment.

In the embodiment thus constructed, the light source 1
The first illumination light emitted from No. 1 is made afocal by the convex lens 21 and is irradiated on the sample surface. Further, the diffracted light generated on the surface of the sample becomes a parallel light flux, and the imaging lens 22
Incident on the lens 2 and undergoes a converging action on the imaging lens 22.
A band of diffracted light is condensed at the focal position of 2.

As described above, according to the present embodiment, the angle between the first irradiation light and the sample S is constant and the unevenness of the light amount is reduced, so that the defect of the sample image acquired under such illumination is reduced. The defect detection capability can be improved by performing the detection.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a view of the state of the optical system of the present embodiment seen from above the sample S, and FIG. 4 is a view of the same optical system seen from the side. The parts having the same functions as those of the optical element shown in FIG. 2 are designated by the same reference numerals.

In this embodiment, a pair of second illumination lights A and B having substantially the same illumination field as the first illumination light which is an afocal light.
A pair of second illumination optical systems 25A and 25B which are incident from above the sample S to the same illumination field at an angle of about 45 degrees with respect to the wiring engraved on the sample surface. The second illumination optical systems 25A and 25B include light sources 23a and 2B, respectively.
3b and lenses 24a, 24b for projecting the light emitted from the light sources 23a, 23b onto the substantially same region as the first illumination light.

Further, in this embodiment, the first illumination light from the first illumination optical system and the second illumination optical systems 25A and 25B are used.
A shutter mechanism that can independently shield each of the second illumination lights is provided.

It should be noted that the first position is at the focal position of the imaging lens 22.
The second TV camera 3 is arranged (the second TV camera 4 is not provided), and the image processing device or the like is connected to the video output terminal of the first TV camera 3 as in the first embodiment. .

In the present embodiment having such a configuration, the first
By illuminating the sample only with the first illumination light from the illumination optical system, the defect inspection by the diffracted light illumination can be performed as in the second embodiment. In addition, the second illumination optical system 25A, 25
When the sample S is irradiated with only the second illumination light from B, the second illumination light having an angle of about 45 degrees with respect to the wiring on the sample surface is emitted obliquely from above. The angle (45 degrees) of the second illumination optical system is the angle determined from the position having the highest detection ability as a result of the experiment.

Here, dust and projections on the surface of the sample can be detected more efficiently by illuminating the illumination light substantially parallel to the wiring of the sample. The reason for this is that dust and projections on the surface of the sample protrude from the surface of the sample. However, a defect that is recessed from the sample surface can be detected efficiently if the angle is 45 ° to 60 ° rather than parallel illumination with respect to the wiring, and the detection efficiency of dust and protrusions on the sample surface is somewhat reduced. Is at a detectable level.

Therefore, the scattered light illumination by the second illumination light is performed at an angle near 45 degrees with respect to the wiring having the highest detection efficiency. The scattered light generated by such scattered light illumination is converged on the first TV camera 3 fixed by the imaging lens 22, and a defect inspection corresponding to the scattered light illumination is performed in the image processing device. Note that both the second illumination optical systems 25A and 25B may simultaneously illuminate the scattered light, or may alternately illuminate the scattered light.

As described above, according to the present embodiment, the second illumination optical systems 25A and 25B provide 45 for the wiring which has the highest detection efficiency for the defect recessed from the sample surface.
Since the second illumination lights A and B are emitted at an angle close to 60 degrees, high detection efficiency can be realized even for a defect that is recessed from the sample surface.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The parts having the same functions as those of the optical element shown in FIG. 2 are designated by the same reference numerals. The present embodiment includes a first illumination optical system 20 shown in FIG. 2 and a second illumination optical system 30 for interference illumination of the sample S. Second
The illumination optical system 30 of the half mirror 31 is disposed between the imaging lens 22 and the first TV camera 3 at a predetermined angle.
An opening 32 having an opening with a diameter of 10 mm arranged at the confocal position of the imaging lens 22 on the optical axis bent by the half mirror 31, and an interference light source 33 arranged behind the opening 32. Is equipped with. The light source 11 of the first illumination optical system 20 and the light source 33 of the second illumination optical system 30 can be independently turned on and controlled. The other structure is similar to that of the second embodiment shown in FIG. Further, the subject to be examined in the present embodiment has a thin film formed on the upper surface of the glass substrate.

In this embodiment, the first illumination optical system 2
When the light source 11 of 0 is turned off and illumination is performed only by the second illumination optical system 30, the second illumination light emitted by the interference light source 33 causes the opening of the opening 33 placed at the confocal position of the imaging lens 22. It is reflected by the half mirror 31 toward the imaging lens 22 side. Then, the second illumination light is made into a parallel light flux by the image forming lens 22 and is applied to the sample S. On the sample surface, a front surface reflection component reflected on the surface of the thin film and a back surface reflection component reflected on the back surface of the thin film (front surface of the glass substrate) are generated. The two components form an interference fringe according to the phase difference between the two components. As a result, the interference pattern of the sample surface is projected on the first TV camera 3. The interference pattern is captured by the first TV camera 3 and input to the image processing apparatus. As described above, since the film thickness unevenness of the thin film can be detected by using the interference pattern, the image processing apparatus performs image processing corresponding to the film thickness unevenness detection to detect the film thickness unevenness.

Further, if the light source 33 of the second illumination optical system 30 is turned off and illumination is performed only by the first illumination optical system 20, the diffracted light inspection can be carried out as in the second embodiment described above. As described above, according to the present embodiment, the defect inspection by the diffracted light and the scattered light can be performed by the illumination by the first illumination optical system 20, and the defect inspection by the interference can be performed by the illumination by the second illumination optical system 30. . Therefore, it is possible to perform highly accurate defect classification based on the result of the surface inspection due to diffraction, interference, and scattering and the illumination method used, and it is possible to realize a judgment function closer to human visual observation.

FIG. 6 shows a modification of the fourth embodiment. In this modified example, the second illumination optical system 40 includes an interference light source 41, a convex lens 42 for converting the second illumination light emitted from the interference light source 41 into a parallel light flux in an afocal state, a sample S and an image. A half mirror 43 is provided between the lens 22 and the half mirror 43 that reflects the second illumination light incident from the convex lens 42 toward the sample S side in parallel with the optical axis.

According to such a modification, there is an advantage that the surface reflection of the second illumination light on the imaging lens 22 does not enter the first TV camera 3. In the third embodiment of FIG. 3 described above, the first illumination optical system irradiates the first illumination light in an afocal state, but unlike the first illumination optical system 2 shown in FIG. In addition, the light flux that converges at a certain angle can be used as the first illumination light.

FIG. 12 is a view showing the arrangement of the optical system of the defect detecting apparatus according to the fifth embodiment of the present invention. In this example,
It has a configuration in which the first illumination optical system 2 described in the first example and the second illumination optical system 25 described in the third example of FIG. 3 are combined. When such first and second illumination optical systems are provided, the converging optical system (imaging lens 22) is unnecessary. According to this embodiment, the same effect as that of the third embodiment can be obtained without providing the converging optical system.

In the above explanation, the wiring pattern imprinted on the surface of the subject has been described as a grid pattern.
Since the present invention only needs to generate diffracted light, it may be a pattern in which a plurality of straight lines are continuous in one direction. The present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

[0069]

As described in detail above, according to the present invention, a plurality of illumination methods can be realized by one optical system, defect types can be accurately classified, and the inspection ability is the same as that of human visual observation. It is possible to provide a defect detection device that can realize the above judgment function.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram of an optical system of a defect detection device according to a second embodiment of the present invention.

FIG. 3 is a top view of an optical system of a defect detection device according to a third exemplary embodiment of the present invention.

FIG. 4 is a side view of an optical system of a defect detecting device according to a third embodiment of the present invention.

FIG. 5 is a side view of an optical system of a defect detecting device according to a fourth embodiment of the present invention.

FIG. 6 is a side view of an optical system of a modified example of the defect detection apparatus according to the fourth example.

FIG. 7 is a diagram showing generation directions of 0th-order reflected light and n-th order diffracted light when light is incident on the surface of a substrate on which grid-like wiring is engraved.

FIG. 8 is a diagram showing line formation by diffracted light.

FIG. 9 is a diagram showing a diffracted light generation direction with respect to incident light obliquely intersecting the wiring on the substrate surface.

FIG. 10 is a diagram showing a relationship between an irradiation lens, a lens illumination field, and a converging point of zero-order reflected light.

11 is a diagram showing a state of the optical arrangement of FIG. 10 as viewed from the side.

FIG. 12 is a top view of an optical system of a defect detection device according to a fifth exemplary embodiment of the present invention.

FIG. 13 is a diagram showing various illumination methods and positions of eyes of an observer.

[Explanation of symbols]

1 ... Stage, 2, 20 ... First illumination optical system, 3 ... First
TV camera, 4 ... Second TV camera, 5 ... Image processing device, 6 ... Computer, 7 ... Monitor, 11, 23 ... Light source, 12 ... Convex lens, 13 ... Irradiation lens, 22 ... Imaging lens, 25 ... 2 illumination optical system, 30 ... Interference illumination optical system.

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Claims (9)

[Claims] 1. A defect detection device for illuminating an object surface on which a plurality of straight lines continuous in at least one direction are formed to detect a defect of the object, the position being oblique to the object surface. From a predetermined illumination range on the surface of the subject from which the illumination light in the direction orthogonal to the straight line is irradiated,
An illumination optical system that converges the diffracted light generated on the subject surface to a predetermined position, and is a position that is far from the subject surface to the extent that the illumination light is not offset, and the convergent position of the diffracted light and / or the diffracted light. A defect detecting apparatus comprising: an image input unit that captures the illumination range from a position other than a convergence point; and a display unit that visualizes an image of the illumination range output from the image input unit. 2. The defect according to claim 1, wherein the illumination optical system includes a light source and a convex lens that converts the light emitted from the light source into convergent light and irradiates the converged light to the illumination range. Detection device. 3. The illumination optical system comprises: a light source; and an illumination lens for converting light emitted from the light source into an afocal parallel light flux and irradiating the illumination range with the image input means. A parallel light flux having a diameter corresponding to the illumination range and incident from the illumination range at a position apart from the subject surface and far from the subject surface so as not to block the illumination light is received by the image input means. The defect detecting apparatus according to claim 1, further comprising an image forming lens for converging the light on said portion. 4. The image input means includes a first image pickup means arranged at a convergent position of the diffracted light and a second image pickup means arranged near the convergent position of the diffracted light. The defect detection device according to claim 1. 5. A defect detection apparatus for illuminating a surface of a subject, on which a plurality of straight lines continuous in at least one direction are formed, to detect a defect in the subject, comprising: a light source; and light emitted from the light source. A first illuminating optical system for irradiating first illumination light in a direction orthogonal to the straight line to a predetermined illumination range on the subject surface from a position oblique to the subject surface, A second illumination optical system for irradiating the illumination range with a second illumination light obliquely intersecting the straight line from a position oblique to the surface of the subject; and a convergent position and / or diffraction of the diffracted light by the converging optical system. A defect detecting apparatus comprising: an image input unit that captures the illumination range from a position other than a light convergence position; and a display unit that visualizes an image of the illumination range output from the image input unit. 6. A defect detection apparatus for illuminating an object surface on which a plurality of straight lines continuous in at least one direction are formed to detect a defect of the object, the position being oblique to the object surface. A first illumination optical system for irradiating a predetermined illumination range on the surface of the subject with a first illumination light in a direction orthogonal to the straight line; and a straight line for the illumination range from a position oblique to the surface of the subject. A second illumination optical system that emits obliquely intersecting second illumination light; and a first illumination that is arranged at a position far from the subject surface to the extent that the first and second illumination lights are not obstructed. Converging optical system for converging the diffracted light generated on the subject surface by light, image input means for photographing the illumination range from a position other than the converging position of the diffracted light by the converging optical system and the converging position of the diffracted light, Output from the image input means An image of the bright range defect detection apparatus characterized by comprising a display means for visualizing. 7. The first illumination optical system comprises a light source and an irradiation lens for converting light emitted from the light source into an afocal parallel light flux and irradiating the light to the illumination range. An optical system is arranged between the image input means and the surface of the subject and at a position far from the subject surface to the extent that the first and second illumination lights are not blocked, and corresponds to the illumination range. 7. The defect detecting apparatus according to claim 6, further comprising an image forming lens having a diameter and converging a parallel light flux incident from an illumination range to a light receiving portion of the image input unit. 8. The defect detection apparatus according to claim 3, further comprising an interference illumination optical system for performing interference illumination on the illumination range on the sample surface. 9. The interference illumination optical system includes a half mirror provided between a light receiving section of an image input unit and a sample surface,
9. The defect detection according to claim 8, further comprising a diffused light source provided at a focal position of the imaging lens on an optical axis bent by the half mirror and satisfying a numerical aperture of the imaging lens. apparatus.