JP2007113941A - Device and method for inspecting defect - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for inspecting defects that are suitable for defect inspection of a relatively large sample imposed with strict tolerance in the height direction. <P>SOLUTION: A sample surface is scanned by using a confocal microscope for generating a line-like scanning beam. A laser beam, generated from a laser light source 10, is converted into a non-coherent line-like light beam by a line-like light beam generator 15. The line-like light beam is converted into a line-like light beam that has converged in one direction by an objective lens 25, and the sample 27 is scanned. The reflected beam from the sample is made incident on a linear image sensor 29. By having the output signal from a linear image sensor 29 supplied to a defect detecting circuit 33 and compared with the reference image information, defect is detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention is a defect inspection apparatus using a confocal optical system, and particularly has a high detection sensitivity in the height direction and is suitable for detecting defects present on the surface of a relatively large sample of about several cm × several cm The present invention relates to a simple defect inspection apparatus.
The present invention also relates to a defect inspection method for inspecting a defect of a cutting edge of a press die used for punching or half-cutting various sheet materials.

  The confocal microscope is a microscope having high detection sensitivity in the Z-axis direction and capable of capturing a high-resolution image. In this confocal microscope, a laser beam emitted from a laser light source is deflected at high speed in the main scanning direction by an acousto-optic device, and deflected in a sub-scanning direction by a galvano mirror to scan the sample surface two-dimensionally. Then, two-dimensional scanning is performed while moving the sample stage in the Z-axis direction, the maximum luminance value is stored in a memory, and a two-dimensional image of the sample is captured (see, for example, Patent Document 1). Since this confocal microscope has high detection sensitivity in the Z-axis direction, it has high utility for defect inspection of integrated circuits and the like having minute irregularities on the surface.

  On the other hand, labels and plastic sheets that have been punched or half-cut along a predetermined cutting pattern are widely used. These products are processed by using a pressing die (flat die or rotary die) in which a pressing blade having a pattern shape corresponding to the cutting pattern is formed, and the pressing die is mounted on a flat plate pressing device or a rotary processing device. . This pressing die (blade plate) is manufactured by the following manufacturing process. For example, a photoresist film is formed on a steel plate having a thickness of about 0.5 mm and having elasticity, and a resist film having a predetermined pattern is formed through exposure and development processes. Thereafter, a protrusion having a predetermined pattern is formed by etching. Furthermore, using an NC processing machine, cutting is performed on both sides of the ridge pattern, a cutting edge having a predetermined dimension is formed, and a pressing blade is formed on a flexible die body.

  The press die is a relatively large sample of several centimeters × several centimeters. On the other hand, since the sharpness and cutting performance of the press cutting blade strongly depend on the dimensional accuracy of the cutting edge, a strict tolerance of several tens of μm is imposed on the cutting edge height, and the defect inspection increases the yield of the product. Very important.

Japanese Patent Laid-Open No. 62-18179

  The press die is a large sample of about several centimeters × several centimeters, but has a special characteristic that a strict tolerance of about several tens of μm is defined with respect to the height direction of the cutting edge. However, whether or not the cutting edge of the press cutting blade is finished to a predetermined size is determined by a skilled operator observing the cutting edge using a magnifying glass. In addition, whether or not a blade edge defect exists is inspected by an operator tracing the fingertip along the edge of the pressing blade. However, in the sensory determination of a skilled worker, it is difficult to complete the inspection, and there is a risk of missing a dimensional error or a defect.

  On the other hand, since the confocal microscope has a high resolution of about several μm in the Z-axis direction, it is suitable for defect inspection of the cutting edge of the pressing blade. However, in the conventional confocal microscope, the laser beam is scanned on the surface of the sample using a beam deflecting device such as an acousto-optic device. Therefore, in the case of a sample having a large surface area such as a press die, the entire sample is scanned. Since it takes a long time, a problem that it takes a long time to inspect one press die will occur.

An object of the present invention is to realize a defect inspection apparatus suitable for defect inspection of a sample that requires high detection sensitivity in the height direction.
Another object of the present invention is to provide a defect inspection apparatus capable of shortening the inspection time in defect inspection of a sample which is a relatively large sample and has a strict tolerance in the height direction.
Furthermore, another object of the present invention is to realize a defect inspection method capable of detecting a dimensional error and a defect of a cutting edge of a pressing blade formed in a pattern on a pressing die with high accuracy.

A defect inspection apparatus according to the present invention includes a laser light source that generates a laser beam,
A line light beam generator for converting a laser beam emitted from a laser light source into a non-coherent line light beam extending in a first direction;
An objective lens that projects the line-shaped light beam toward the sample to be inspected as a line-shaped scanning beam;
A sample stage that supports the sample and moves in the X direction corresponding to the first direction and the Y direction orthogonal to the X direction;
Means for changing the relative distance between the focused line of the scanning beam and the sample;
A linear image sensor having a plurality of light receiving elements arranged along a direction corresponding to the first direction and receiving reflected light from a sample;
It comprises defect detection means for comparing the image information of the sample output from the linear image sensor with the reference image information to perform defect determination.

  In the present invention, by using a confocal optical system using a linear scanning beam, high resolution is obtained in the height direction and inspection time is shortened. That is, a high-resolution confocal optical system is configured by scanning the sample surface with a line-shaped scanning beam having convergence and receiving a reflected beam from the sample with a linear image sensor. In addition, by scanning the sample surface using a line-shaped scanning beam, the scanning time can be significantly reduced as compared with an apparatus that scans using an acousto-optic element or a galvanometer mirror. As a result, even a sample having a large surface area and a high detection sensitivity in the height direction can perform a highly accurate defect inspection in a short time. In particular, since the confocal optical system has a detection sensitivity of several μm in the height direction (Z-axis direction), a minute dimensional error or defect of about several μm can be detected. As a result, it is suitable for defect inspection of a comparatively large sample such as a press die, which requires high detection sensitivity in the height direction.

  In a preferred embodiment of the defect inspection apparatus according to the present invention, the line-shaped light beam generator has a light incident surface, and has a plurality of micromirror elements arranged in a two-dimensional matrix in the light incident surface. The mirror surface of each micromirror element rotates or tilts at high speed according to the drive signal, and the incident laser beam is converted into a non-coherent line light beam by the high-speed rotation or tilting of each mirror surface. It is characterized by that. What is important here is that a combination of a mercury lamp or a laser light source and a cylindrical lens is not used as a means for generating a linear scanning beam. That is, when a mercury lamp is used, since the mercury lamp itself is large, there is not only a disadvantage that the inspection apparatus becomes large, but also a disadvantage that the manufacturing cost is high. In addition, when a linear scanning beam is formed using a combination of a laser light source and a cylindrical lens, since the laser beam is coherent, glare and the like occur frequently, resulting in a distorted image with a lot of noise and high accuracy. There are limits to performing defect inspection. In contrast, in the present invention, a micromirror device having a plurality of micromirror elements arranged in a two-dimensional matrix is used, and a coherent laser beam is converted into an incoherent light beam by high-speed rotation of each micromirror. Therefore, a small and inexpensive defect inspection apparatus can be realized. That is, each micromirror element of the micromirror device is reciprocally rotated or reciprocally tilted within an angle range of about ± 10 °. Therefore, when each micromirror element is individually driven based on an image signal, the micromirror element rotates according to the drive signal. A switching operation is performed to display an image corresponding to the video signal. On the other hand, instead of individually driving each micromirror element, when the micromirror element is driven at a high speed as a whole, the mirror surface of each micromirror element can vibrate the incident laser beam in one direction at a high speed. Therefore, a light beam equivalent to a divergent line beam is emitted from the micromirror device. The divergent line light beam is converted into a parallel line light beam expanded in one direction by passing through a focusing lens. Furthermore, even if the same drive signal is supplied to each micromirror element, each micromirror element rotates at random because the micromirror elements have different masses and the like. As a result, each beam portion incident on each micromirror is in a random phase state, and a non-coherent light beam can be emitted from the micromirror device. More importantly, an apparatus for generating a line-shaped light beam using a micromirror device has an advantage that an expanded line-shaped light beam having a line width of about 1 cm can be easily formed. As a result, since scanning can be performed with a wide line-shaped scanning beam, the time required for defect inspection of the sample can be greatly shortened. The inventor has proved that the coherent laser beam is converted into a non-coherent light beam by the micromirror device.

The defect inspection method according to the present invention is used for punching or half-cutting various sheet-like members, and detects defects in a pressing die in which a predetermined pattern of pressing blades are formed on the die body. A method,
Preparing a confocal microscope and attaching a pressing die to be inspected to the sample stage of the confocal microscope;
A step of setting the focal point or focal line of the scanning beam emitted from the confocal microscope so as to be positioned at the tip of the cutting edge of the pressing blade;
In a state where the focal point or focal line of the scanning beam is coincident with the tip of the blade edge, the scanning die is two-dimensionally scanned with the scanning beam to capture a linear pattern image of the blade edge of the cutting edge;
And a defect determination step of performing defect determination by comparing the pattern image of the cutting edge with reference information.

  In the present invention, the focal point or line of the scanning beam is set to be positioned at the tip of the cutting edge of the pressing blade, and the cutting die is two-dimensionally scanned by the scanning beam, so that the image of the cutting edge of the pressing blade is continuous. Captured as a pattern image. Therefore, the edge defect can be easily detected by comparing the captured pattern image with the reference image information. In addition, only the image of the vertex of the cutting edge of the same height is clearly captured, and when the tip of the cutting edge is lower than the standard value or when the cutting edge is spilled, the cutting edge portion is captured as a missing image, so the cutting edge By comparing this image with the reference image information, a more accurate defect inspection can be performed. In particular, since the confocal optical system has a detection sensitivity of about several μm in the height direction (Z-axis direction), the cutting edge of the pressing blade can be inspected more strictly.

  In the present invention, since a confocal optical system that scans a sample with a line-shaped scanning beam is used, defect inspection can be performed in a short time even for a large sample that requires high detection sensitivity in the height direction. It can be carried out.

  In this embodiment, a pressing die is used as a sample to be detected, and the defect inspection of the cutting edge of the pressing die will be described as an example. FIG. 1 is a diagram showing an example of a stamping die subjected to defect inspection according to the present invention, FIG. 1A is a plan view, and FIGS. 1B and 1C are diagrams showing the cross-sectional shape of a stamping blade. Using the press die, punching or half-cutting is performed on various sheet-like members such as labels. The pressing die 1 has a die body (main base) 2 having a size of, for example, 10 cm × 6 cm, and a pressing blade 3 having a pattern corresponding to the cutting pattern is formed on the die body 2. The blade height d of the pressing blade 3 is set to, for example, 0.60 to 1.20 mm in the case of a flat cutting die, and is set to 0.40 to 0.60 mm in the case of a rotary cutting die. Since the blade height d strongly affects the cutting accuracy of the press die, its tolerance is set to ± 30 μm. Moreover, the blade angle α of the blade edge 4 is set to 40 to 80 °, for example.

  The press die 1 is manufactured by etching and grinding using a steel plate or stainless steel plate having elasticity. That is, for example, a steel plate or stainless steel plate having a thickness of 0.5 mm is prepared, and a photoresist film is formed on the surface thereof. Next, exposure is performed using a photomask on which a predetermined pattern is formed, and development processing is performed to form a photoresist film having a predetermined pattern. Thereafter, an etching process is performed to form a protruding pattern. Then, after removing the resist film, the cutting edge is formed by grinding processing by NC processing, and the pressing blade 3 is formed on the die body. In the present invention, the shape of the cutting edge 4 of the pressing blade is imaged using a confocal microscope and the defect inspection is performed based on the obtained image of the cutting edge.

  FIG. 2 is a diagram showing an example of a defect inspection apparatus according to the present invention. In the confocal microscope of this example, all the optical elements are arranged on the same plane, thereby eliminating the troublesome adjustment of the optical system. A laser light source 10 is used as an illumination light source. An expander optical system 11 is disposed in front of the laser light source 10 to convert it into an expanded parallel light beam. The laser beam converted into the expanded parallel light beam enters the first polarization beam splitter 13 through the first cylindrical lens 12. The first cylindrical lens 12 has a lens action that converges the incident light beam only in the second direction (a direction orthogonal to the first direction, which is an expansion direction of the linear light beam described later).

  The laser beam passes through the first polarizing beam splitter 13, passes through the λ / 4 plate 14, and enters perpendicularly in a state where it converges on the light incident surface of the line-shaped light beam generator 15. This line-shaped light beam generator is arranged in a two-dimensional matrix, and is composed of, for example, a micromirror device having a plurality of micromirror elements having a rectangular aluminum reflecting surface of 14 μm × 14 μm on the light incident surface. The mirror surface of each micromirror element is reciprocally rotated or reciprocated at high speed by a drive pulse supplied from the drive circuit, and the incident laser beam is vibrated at high speed in the first direction. Accordingly, when viewed as the entire laser beam, the micromirror device 12 emits a linear light beam that diverges in the first direction. Further, since the mirror surface of each micromirror element of the micromirror device is rotated or tilted in a random state, a minute beam portion incident on each micromirror element of the incident laser beam is reflected in a random state. . As a result, the light beam emitted from the micromirror device has a random phase relationship when viewed as a whole beam, and the coherence is no longer maintained and is converted into a divergent non-coherent light beam. As a result, the occurrence of glare or the like can be prevented, and a clear sample image can be taken.

  The non-coherent divergent light beam emitted from the line-shaped light beam generator 15 passes through the λ / 4 plate 14, is reflected by the polarization plane of the first polarization beam splitter 13, and enters the convergent spherical lens 16. Then, the light is converted into a parallel light beam expanded in the first direction by the convergent spherical lens. The line-shaped parallel light beam is converged in the second direction by the second cylindrical lens 17 and enters the second polarization beam splitter 19 through the relay lens 18. Therefore, at the image forming position of the second cylindrical lens 17, a parallel line-shaped light beam that is enlarged in the first direction and converged in the second direction orthogonal to the first direction is formed.

  The thin line-shaped light beam incident on the second polarization beam splitter 19 is reflected by the polarization plane, and enters the galvano mirror 21 through the imaging lens 20. The line-shaped light beam reflected by the galvanometer mirror 21 enters the objective lens 25 through the relay lenses 22 and 23 and the λ / 4 plate 24. The objective lens converts the incident linear light beam into a converging scanning beam that is substantially parallel to the first direction and focused in a second direction orthogonal to the first direction, and is placed on the stage 26. It projects toward the pressing die 27 to be inspected. The galvanometer mirror 21 is stationary and used as a fixed mirror when scanning the entire sample, and performs beam scanning in a direction orthogonal to the first direction when a part of the sample is captured as an enlarged confocal image.

  The stage 26 is a three-axis direction moving stage, that is, an X, Y, and Z axis moving type stage. Here, the X-axis direction is set to a direction corresponding to the first direction that is the extending direction of the linear light beam. Therefore, as shown in FIG. 3, by moving the stage 26 in the order of the Y direction, the X direction, and the Y direction, almost the entire surface of the pressing die 27 to be inspected is scanned by the converging scanning beam. Become. In scanning, the stage 26 is moved in the Z-axis direction so that the focal point or line of the scanning beam projected from the objective lens 25 is adjusted to coincide with the position of the top of the cutting edge of the pressing blade of the pressing die 27. Of course, it is also possible to adjust the position of the focal point by fixing the sample stage 26 in the Z-axis direction and moving the objective lens 25 in the optical axis direction. The stage 26 is driven and controlled by a drive signal from the stage drive circuit 28. Note that control such as stage drive control and linear image sensor drive control, which will be described later, is performed based on a control signal from the controller 40.

  The reflected beam reflected by the top of the cutting edge of the pressing blade is collected by the objective lens 25, and again passes through the λ / 4 wavelength plate 24, the relay lenses 23 and 22, the galvanometer mirror 21 and the imaging lens 20, and is then subjected to the second polarization. The light enters the beam splitter 19. Since the reflected beam from the pressing blade passes through the λ / 4 plate 24 twice, it passes through the second polarizing beam splitter 19 and is separated from the illumination beam directed from the light source toward the sample. Incident. The linear image sensor 29 has a plurality of light receiving elements arranged along a direction corresponding to the first direction which is the extending direction of the line-shaped light beam. Accordingly, the image of the cutting edge of the pressing blade is formed on the plurality of light receiving element arrays by the imaging lens 20. The electric charge accumulated in each light receiving element is sequentially read by the drive signal supplied from the drive circuit 30.

  The output signal read from the linear image sensor 29 is amplified by the amplifier 31 and then supplied to the signal processing circuit 32. The signal processing circuit 32 performs signal processing using the control signal supplied from the controller 40, and outputs a video signal representing a two-dimensional image of the press die.

  The output signal from the linear image sensor 29 is also supplied to the defect detection circuit 33. The defect detection circuit 33 compares the reference image information with the video output from the linear image sensor, and outputs the presence of the defect and its address information. This defect determination can be performed by, for example, a die-to-database method or a die-to-die method. Therefore, as the reference image information, the reference data storing the pattern of the cutting edge of the press cutting blade can be used, or the image information measured last time is stored in the memory, and the image information stored in the memory is used as the reference image information. Can do.

  FIG. 4 is a diagram for explaining an imaging method for imaging the cutting edge of the pressing blade. In the present invention, the focusing line of the converging scanning beam emitted from the objective lens is set at the position of the cutting edge 4 of the pressing blade 3, and a two-dimensional image of the pressing die is picked up by two-dimensional movement of the stage. 4A to 4C, the press cutting blade 3 is assumed to extend in a direction perpendicular to the paper surface, and has a top portion 4a constituting the blade edge, and two inclined surfaces 3a and 3b facing each other across the top portion. The convergent scanning beam extends in a direction perpendicular to the paper surface and enters the pressing blade 3 from above. The scanning beam is indicated by two limit rays, and the focusing line is indicated by a black circle. In this example, beam scanning is performed by moving the stage. In FIG. 4, the scanning beam is fixed, and the pressing blade moves to the right in the drawing.

  As shown in FIG. 4A, first, the scanning beam is incident on the slope 3b on the right side of the pressing blade. At this time, the scanning beam is reflected downward by the inclined surface 3b, and the reflected light does not enter the objective lens. Therefore, no image is formed.

  Next, as shown in FIG. 4B, the focused line of the scanning beam is located on the top 4a via the top edge of the cutting edge. At this time, the scanning beam is reflected by the top 4a of the blade edge, is condensed by the objective lens, and enters the linear image sensor. Accordingly, an image of the top of the blade edge is taken.

  As it moves further, the focusing line of the scanning beam passes through the opposite edge of the top 4a and enters the opposite inclined surface 3a. The reflected light from the inclined surface 3a travels downward and does not enter the objective lens.

  Thus, only when the focused line of the scanning beam is located at the top of the blade edge, the reflected light from the pressing blade is collected by the objective lens and enters the linear image sensor, and otherwise the linear image sensor is input. Since the reflected light hardly enters, only the image of the top of the blade edge is clearly captured, and the width of the top of the blade edge is captured very accurately. From this characteristic, it is possible to determine whether or not the cutting edge is set to a normal value by comparing the line width of the pattern image of the pressing blade with a reference value.

  Next, a case where the blade edge 4 has a defect such as blade spillage or a case where the blade height is lower than the reference value will be described. FIG. 5A shows a cutting edge having defects such as blade spills at the tip. In FIG. 5A, a solid line shows the external appearance of a blade edge, and a broken line shows the dimension of a regular blade edge. When the scanning beam is incident on the first slope, the reflected light from the slope travels downward. Next, when the focused line is located at the normal top of the cutting edge, the top of the cutting edge is located below the reference position, so that the scanning beam changes into a divergent beam and enters the top. At this time, since the scanning beam incident on the top is divergent, it is reflected at the top and diverges widely from side to side. As a result, the reflected light from the blade edge does not enter the objective lens, or even if it is incident, it is out of the optical path while propagating to the linear image sensor, and a frame (pinhole) arranged in front of the linear image sensor. The light is not incident on each light receiving element or only a small amount of reflected light is incident. As a result, even when the scanning beam is positioned on the top of the blade edge, an image of the top of the blade edge is not formed. Such a state is also applied when the blade height is lower than the reference value, and similarly, a missing image state in which an image of the top of the blade edge is not formed. Therefore, when a discontinuous part occurs in the pattern image of the cutting edge, it can be determined that the part is a defect.

  FIG. 5B shows a reflection state when the blade height is larger than the reference value. A broken line indicates a case where the blade height is a reference value. When the blade light is larger than the reference value, it enters the top of the blade edge before the scanning beam is focused, so the scanning beam does not propagate through the normal optical path and is shielded by a frame arranged in front of the linear image sensor, The light is not incident on each light receiving element, and the image of the blade edge is not formed or a low luminance image with extremely low luminance is obtained.

  FIG. 6 shows a state where the extending direction of the line-shaped scanning beam and the extending direction of the pattern of the pressing blade are orthogonal to each other. In FIG. 6, it is assumed that the pressing blade extends in a direction orthogonal to the paper surface, and the line-shaped scanning beam extends in the paper surface. In this example, the pressing blade is scanned with a scanning beam that is parallel to the X direction and has focusing properties in the Y direction. In this case, the beam portion incident on the slope of the pressing blade is reflected downward, and the beam portion incident on the top of the blade tip is reflected substantially vertically. Accordingly, since only the reflected light of the beam portion incident on the top of the blade edge is incident on the linear image sensor, a blade edge image having a width accurately corresponding to the width of the blade edge can be clearly captured.

  Next, an image obtained by actually capturing the image of the press die shown in FIG. 1 using the defect inspection apparatus according to the present invention shown in FIG. 2 will be described. 7 is an enlarged image of a region indicated by a broken line of the pressing die shown in FIG. 1, FIG. 7A shows a pattern image of a normal pressing blade, and FIG. 7B shows a pattern image of a pressing die having poor cutting performance. A pressing die was mounted on the stage, and the scanning beam focusing line was set to the position of the top of the cutting edge of the pressing blade to perform two-dimensional scanning. As shown in FIG. 7A, the image of the press cutting die processed into a regular dimension having no defect was obtained by capturing an image of the edge of a continuous linear pattern that matched the pattern of the press cutting blade. In the obtained image, the images of the slopes constituting the cutting edge and the lower die body were not taken at all, and only the top image of the cutting edge was taken. When the dimensions of the top image were measured from the image of the blade edge projected on the monitor, it was exactly the same as the design value.

  On the other hand, when the cutting performance or poorly-cutting die was imaged in the same manner, an image shown in FIG. 7B was obtained, and defects were recognized at two places. A normal blade edge image is an image having a uniform line width along the pattern of the pressing blade. On the other hand, in the case of a pressing die having poor cutting performance, it was found that the corners of the pressing blade were insufficiently ground and were not finished to the specified dimensions. In addition, there was a partial spilled area, and no image was formed in that area, and it was displayed as a missing image on the monitor.

  From this experimental result, as a defect determination method, the presence or absence of a defect and a manufacturing error can be measured by comparing the line width of the captured pattern image with a reference value. Further, it is possible to determine a defect based on the presence or absence of a defect image in the pattern image on the top, that is, the presence or absence of an image at a site where an image is formed.

  As a defect inspection method, it is possible to first scan the entire sample and then capture an enlarged confocal image of the detected defect portion. That is, when the entire sample is scanned, the galvanometer mirror 21 is stopped and the entire sample is scanned by moving the stage. Next, it is also possible to move the stage using the address information in which the defect is detected, set the magnification to high, and drive the galvanometer mirror 21 to capture an enlarged confocal image of the defective portion. As described above, by capturing an enlarged confocal image of a defect, it is possible to confirm the generation factor of the defect.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can be made. For example, in the above-described embodiment, the defect inspection of the stamping die has been described. However, the stamping die is described as an example, and can be applied to defect inspection of semiconductor wafers, various sheet materials for image display, and the like. .

It is a diagram which shows an example of a pressing die. It is a diagram which shows an example of the confocal microscope for enforcing the defect inspection method by this invention. It is a diagram which shows an example of the scanning locus | trajectory of a scanning beam. It is a diagram which shows typically the reflective state of the scanning beam which injects into a pressing blade. It is a diagram which shows the reflection state of the scanning beam at the time of scanning the press cutting blade from which the blade height shifted | deviated from the reference value. It is a diagram which shows a scanning state in case the extension direction of a pressing blade and the extension direction of a scanning beam are orthogonal. It is a diagram which shows the image obtained by imaging a pressing die using the defect inspection apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stamping die 2 Die body 3 Pressing blade 4 Cutting edge 10 Laser light source 11 Expander optical system 12, 17 Cylindrical lens 13, 19 Beam splitter 14, 24 λ / 4 plate 15 Line-shaped light beam generator 16 Spherical lens 18, 22, 23 relay lens 20 imaging lens 21 galvanometer mirror 24 λ / 4 plate 25 objective lens 26 stage 27 pressing die 28 stage drive circuit 29 linear image sensor 30 drive circuit 31 amplifier 32 signal processing circuit 33 defect detection circuit

Claims (11)

A laser light source for generating a laser beam;
A line light beam generator for converting a laser beam emitted from a laser light source into a non-coherent line light beam extending in a first direction;
An objective lens that projects the line-shaped light beam toward the sample to be inspected as a line-shaped scanning beam;
A sample stage that supports the sample and moves in the X direction corresponding to the first direction and the Y direction orthogonal to the X direction;
Means for changing the relative distance between the focused line of the scanning beam and the sample;
A linear image sensor having a plurality of light receiving elements arranged along a direction corresponding to the first direction and receiving reflected light from a sample;
A defect inspection apparatus comprising defect detection means for performing defect determination by comparing image information of a sample output from a linear image sensor with reference image information.   The defect inspection apparatus according to claim 1, wherein the line-shaped scanning beam emitted from the objective lens is substantially parallel along the X direction and has convergence in the Y direction.   3. The defect inspection apparatus according to claim 1, wherein the line-shaped light beam generator has a light incident surface, and includes a plurality of micromirror elements arranged in a two-dimensional matrix in the light incident surface. A mirror device is provided, and the mirror surface of each micromirror element is rotated or tilted at a high speed according to a drive signal, and the laser beam incident by the high-speed rotation or tilt of each mirror surface is converted into a non-coherent line light beam. A defect inspection apparatus characterized by converting.   4. The defect inspection apparatus according to claim 3, wherein a first beam splitter is disposed between the laser light source and the line-shaped light beam generator, and a laser beam emitted from the laser light source is passed through the first beam splitter. The first laser beam is incident perpendicularly to the light incident surface of the micromirror device, and the laser beam directed from the laser light source to the line-shaped light beam generator and the non-coherent line-shaped light beam emitted from the line-shaped light beam generator are A defect inspection apparatus characterized by being separated by a beam splitter.   5. The defect inspection apparatus according to claim 4, wherein a second beam splitter is disposed between the first beam splitter and the objective lens, and a light beam directed from the laser light source toward the sample by the second beam splitter. And a reflected beam traveling from the sample toward the linear image sensor.   A cylindrical lens for focusing the laser beam emitted from the laser light source in a second direction orthogonal to the first direction is disposed between the laser light source and the first beam splitter, and light incidence of the micromirror device is performed. 6. The defect inspection apparatus according to claim 4, wherein a line-shaped laser beam is incident on the surface.   7. The defect inspection apparatus according to claim 1, further comprising: a signal processing circuit that receives an output signal read from each light receiving element of the linear image sensor and outputs a video signal of the sample. A defect inspection apparatus that outputs two-dimensional image information of a sample together with defect detection information.   The defect inspection apparatus according to any one of claims 1 to 7, wherein the sample is a pressing die having a predetermined pattern of pressing blades formed on a die body, and the Z-axis direction defect detection means uses the pressing blade. A defect inspection apparatus that performs defect determination by comparing a pattern image of a blade edge with reference image information. A defect inspection method for detecting defects in a pressing die in which a stamping blade of a predetermined pattern is formed on a die body, which is used when performing punching processing or half-cutting processing on various sheet-like materials,
Preparing a confocal microscope and attaching a pressing die to be inspected to the sample stage of the confocal microscope;
A step of setting the focal point or focal line of the scanning beam emitted from the confocal microscope so as to be positioned at the tip of the cutting edge of the pressing blade;
In a state where the focal point or focal line of the scanning beam is coincident with the tip of the blade edge, the scanning die is two-dimensionally scanned with the scanning beam to capture a linear pattern image of the blade edge of the cutting edge;
A defect inspection method comprising: a defect determination step of performing defect determination by comparing a pattern image of a blade edge with reference image information.   From the confocal microscope toward the pressing die on the stage, project a line-shaped scanning beam having a focusing property in the first direction and substantially parallel to the second direction orthogonal to the first direction, A defect inspection method, characterized in that the pressing die is two-dimensionally scanned using the converging line-shaped scanning beam. The defect inspection method according to claim 10, wherein the defect determination is performed based on the line width of the imaged linear pattern of the cutting edge or the presence or absence of a missing image of the linear pattern.