JP3827812B2 - Surface defect inspection apparatus and surface defect inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for detecting a surface defect of an etched product such as a shadow mask and a lead frame, and more particularly to a surface defect that lacks the edge of a hole in a shadow mask used in a color television or the like. It relates to the inspection method.
[0002]
[Prior art]
Conventionally, as a method for detecting a surface defect of a shadow mask, there has been known a method in which reflected light from a shadow mask is photographed and a surface defect is extracted by image processing. Since the surface roughness of the surface was rough, only a low detection sensitivity could be obtained.
In order to increase the detection sensitivity, the linear area photographing means and the light source are used, the linear area photographing means and the light source are arranged at a predetermined angle with respect to the shadow mask surface, and the shadow mask is transmitted through the shadow mask surface obliquely. There is also a method for photographing transmitted light. However, in this method, it is necessary to adjust the optimum shooting angle for each type of shadow mask, and there is a problem that operation and control become complicated, and defects in all directions cannot be detected in a single inspection. Therefore, in order to detect defects in all directions, it is necessary to inspect by changing the direction a plurality of times, which is a problem in terms of quality and workability.
In recent years, more and more shadow masks have been required to have higher definition and higher definition, and quality control has become important, and there is a need for a shadow mask inspection method with high detection sensitivity and easy workability. Has come to be.
[0003]
[Problems to be solved by the invention]
As described above, more and more shadow masks are required to have a larger size and higher definition. In the shadow mask surface inspection method, a surface inspection method and an inspection apparatus with high detection sensitivity and easy workability are provided. It has come to be required.
Under such circumstances, an object of the present invention is to provide a shadow mask surface inspection method and inspection apparatus with high detection sensitivity and easy workability.
[0004]
[Means for Solving the Problems]
The surface defect inspection apparatus of the present invention is an apparatus for detecting a surface defect of a shadow mask etching processed product, and has an XY stage that can hold an inspected sample on the XY stage and an inspection area of the sample. Between the specimen and the imaging means, a planar imaging means of a type that allows light to reach the imaging surface via a lens, a light source for imaging provided on the opposite side of the imaging means of the sample, Based on the image data obtained by photographing the inspection area of the sample, and a plurality of mirrors that are arranged so as to surround the inspection area of the sample, reflect the oblique light transmitted through the inspection area of the sample, and reach the imaging means. An image processing unit that performs image processing and extracts defects, and the imaging unit images the inspection area of the sample through a mirror, and an oblique light sample surface that passes through the inspection area of the sample to be imaged Change the angle to make As such, and it is characterized in that is provided to be continuously moved in order to vary the distance from the sample surface.
Then, the image processing unit obtains a pair of image data before and after the image pattern of the sample is shifted by the photographing unit at each photographing position at a plurality of photographing positions at different distances from the sample surface of the photographing unit, After obtaining difference image data obtained by taking the difference between the pair of image data, the obtained difference image data at each photographing position is binarized directly or indirectly to obtain binarized image data. Thus, the defect portion is extracted.
[0005]
The surface defect inspection method of the present invention is a method for detecting surface defects by photographing oblique light transmitted through an inspection region of a shadow mask etching processed product through a mirror and subjecting the obtained image data to image processing. A plurality of mirrors that reflect oblique light that has passed through the sample inspection area to reach the image pickup means are disposed so as to surround the sample inspection area between the sample and the image pickup means, and the image pickup means is moved. By shooting at different positions with different distances from the imaging means and the sample surface to be inspected, the angle between the sample surface of oblique light passing through the inspection area of the sample to be imaged is changed multiple times Thus, at each photographing position of the photographing means, a pair of image data before and after being shifted by the pitch of the pattern of the sample is photographed, and difference image data obtained by taking the difference between the pair of image data is obtained. After, by image processing obtained difference data, respectively, it is characterized in that for detecting the surface defects.
In the above, the direction of oblique light transmitted through the inspection region of the etched product of the shadow mask obtained from the mirror is set to all directions.
In the above image processing, the difference image data obtained at each position of the photographing means is binarized directly or indirectly to obtain binarized image data, and the defective portion is extracted. It is characterized by being.
[0006]
In addition, as shown in FIG. 4, when inspecting a surface defect in which a hole edge of an etched product such as a shadow mask is missing (this is also referred to as an “egre defect”), light is blocked at a normal hole for photographing. In this case, an image is taken with light passing through only a portion having an egre defect. Here, the angle θ formed with the shadow mask surface of the light shown in FIG. In this case, the maximum photographing angle θo among the light angles θ that are shown in FIG.
Actually, since the photographing is performed at the photographing suitable angle θ that is very close to the optimum photographing angle θo, the optimum photographing angle θo including the photographing suitable angle θ is also referred to here.
In defect detection according to the present invention, oblique light that has passed through an inspection area substantially equal to the optimum photographing angle θo is used for defect detection.
In the shadow mask, as shown in FIG. 5, the optimum shooting angle θo is generally different for each position in the shadow mask, but the oblique light transmitted through the inspection area used for this defect detection is different. This can be accommodated by varying the angle.
[0007]
[Action]
By adopting such a configuration, the surface defect inspection apparatus of the present invention can provide a surface inspection apparatus for etching processed products such as a shadow mask with high detection sensitivity and simple workability.
More specifically, an XY stage that can hold the sample to be inspected and move in an XY manner, and a planar imaging unit that uses a lens to image the inspection area of the sample and that allows light to reach the imaging surface via a lens And a light source for photographing provided on the opposite side of the sample photographing means, and the sample and the photographing means are disposed so as to surround the sample inspection area and reflect oblique light transmitted through the sample inspection area. A plurality of mirrors that allow light to reach the imaging unit; and an image processing unit that extracts a defect by performing image processing based on image data obtained by imaging the inspection region of the sample, the imaging unit passing through the mirror In order to change the distance from the sample surface so as to change the angle with the sample surface of oblique light that passes through the inspection region of the sample to be imaged To achieve this There.
[0008]
Specifically, in the shadow mask, as shown in FIG. 5, the optimum shooting angle θo is generally different for each position in the shadow mask, and the range of the shooting suitable angle that can detect the Eggle defect is Although different, in the inspection apparatus of the present invention, the distance between the imaging means and the sample is changed by moving the imaging means, so that imaging can be performed at an angle close to the optimum imaging angle θo at the angular position.
When photographing is performed at the photographing suitable angle necessary for detecting the defect shown in FIG. 4 close to the optimum photographing angle θo, image data obtained by photographing varies depending on the presence or absence of the defective portion.
Therefore, when shooting at an angle close to the optimum shooting angle θo, a pair of shots taken before and after the pitch shift is usually taken when the pattern of the sample to be inspected is shifted in pitch so that defective portions do not overlap. If the difference image data of the image data is taken, only the defective part is extracted.
[0009]
Also, a plurality of mirrors are provided between the sample and the imaging means so as to surround the inspection area of the sample and reflect the oblique light transmitted through the inspection area of the sample and reach the imaging means. Thus, the direction of oblique light transmitted through the inspection area of the shadow mask obtained from the mirror can be set to all directions, and as a result, any direction of the egre defect can be detected.
[0010]
By adopting such a configuration, the surface defect inspection method of the present invention enables photographing at an angle at which an Eggle defect at each position of a sample to be inspected can be easily detected. For example, in the shadow mask, as described above, the optimum shooting angle θo is different for each position in the shadow mask, and the range of the shooting suitable angle at which the Eggle defect can be detected is different. By photographing a plurality of times in a state in which the angle formed by the oblique light passing through the shadow mask surface is different, it is possible to perform photographing at an angle at which the Eggle defect at each position of the shadow mask can be easily detected.
Furthermore, by setting the direction of oblique light transmitted through the inspection region of the sample to be inspected obtained from the mirror to be almost all directions, it is possible to detect the Aegle defect in any direction of the through hole of the sample.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
First, the surface defect inspection apparatus according to the present invention will be described with reference to the drawings.
FIG. 1A is a schematic sectional view of an example of the surface defect inspection apparatus of the present invention, FIG. 1B is a schematic view of an imaging means, and FIG. 2 is viewed from A1-A2 of FIG. FIG.
1 and 2, 100 is an inspection device, 110 is an imaging unit, 113 is a lens, 115 is an imaging surface, 117 is a cable, 120 is a light source, 130 is an XY stage, 140 is a mirror, 150 is an image processing unit, Reference numeral 160 is a television monitor, 170 is oblique light, 171 is reflected light, 180 is a sample, and 180A is an inspection area.
As shown in FIG. 1, the surface defect inspection apparatus 100 of the present invention is an apparatus for detecting a surface defect (eggle defect) of an etching processed product such as a shadow mask, and holds a sample 180 to be inspected thereon, An XY stage 130 that can move in the XY direction, a planar imaging unit 110 that allows light to reach the imaging surface 115 via the lens 113 for imaging the inspection region 181 of the sample 180, and an imaging unit 110 for the sample 180 The light source 120 for imaging provided on the opposite side and the sample 180 and the imaging means 110 are arranged so as to surround the sample inspection area 180A, and the oblique light 170 transmitted through the sample inspection area 180A is reflected and imaged. Image processing is performed based on a plurality of mirrors 140 that allow the reflected light 171 to reach the means 110 and image data obtained by imaging the inspection region 180A of the sample. And an image processing unit 150 for extracting Recessed.
[0012]
The planar photosensor part of the photographing unit 110, that is, the element on the imaging surface includes a CCD element, but is not particularly limited thereto. Any device may be used as long as it allows light to reach the planar optical sensor unit via the lens 113.
The imaging unit 110 images the inspection area 180A of the sample 180 via the mirror 140, and is provided so as to be continuously movable so as to change the distance from the surface of the sample 180. Thereby, when imaging | photography, the angle which the sample surface of the oblique light 170 which permeate | transmits a sample surface makes can be adjusted. In other words, oblique light transmitted through the sample surface at various angles can be photographed.
[0013]
A plurality of flat mirrors 140 may be provided in accordance with the pattern of the sample 180.
In the case of the apparatus 100 shown in FIG. 1A, the sample is placed so as to surround the sample inspection region 180A between the sample 180 and the imaging means 110, and the direction of the oblique light 170 that passes through the sample 180 inspection region 180A The direction.
In the apparatus 100 shown in FIG. 1A, the light source 120 has a planar shape capable of irradiating the entire shadow mask. The XY stage 130 is for placing the sample 180 on the XY stage.
[0014]
The image processing unit 150 processes the image data obtained by the photographing unit 110 and extracts defective portions.
[0015]
Next, an example of the surface defect inspection method of the present invention will be described with reference to the flowchart of FIG.
The flow shown in FIG. 3 uses the surface defect inspection apparatus 100 of the present invention shown in FIGS. 1 and 2, and the operation of the surface defect inspection apparatus 100 will be described below at the same time.
First, the sample 180 is placed on the XY stage 120, and the XY stage 120 is moved along the inspection area 180A so that all the mirrors 140 surround the inspection area 180A as shown in FIG. (S11)
After moving the XY stage 120 to a predetermined position, the photographing unit 110 moves to the first position. (S12)
Here, after inspecting the sample inspection area 180A through the mirror 140 and obtaining the image data D11 (S13), the XY stage 120 is moved to the pitch of the pattern of the sample while the imaging means 110 is kept at the first position. The sample is inspected 180A through the mirror 140 again, and image data D12 is obtained. (S14)
Next, image data D1, which is the difference between the image data D11 and D12, is obtained (S15).
Next, the obtained image data D1 is binarized at a predetermined slice level to obtain binarized image data, and a defective portion is extracted therefrom. (S16)
Similarly, the image pickup means 110 is moved, and the image data Dn1 and Dn2 (n = 2 to N) before and after the image pickup means 110 is shifted by the pitch of the pattern of the sample at the second position to the nth position, respectively. Are obtained, respectively. (S15)
Each Dn (n = 2 to N) is binarized at a predetermined slice level, binarized image data is obtained, and a defective portion is extracted. (S16)
In this way, all of the obtained defect portions are defects in the inspection region of the inspection region 180A of the sample 180.
When there are a plurality of inspection areas, defects are extracted as described above for each inspection area.
Although the inspection method of the present invention depends on the sample, even if the inspection region 180A shown in FIG. 2 is divided into a plurality of portions, the entire inspection region of the sample is not divided and the mirror is surrounded by this region. Defect extraction may be performed.
[0016]
Furthermore, the reason why the defect can be easily extracted will be described.
As described above, when shooting is performed at an imaging suitable angle capable of detecting the Egre defect shown in FIG. 4, only the defective portion is captured and the normal portion is not captured. Therefore, the Egre defective portion is different from the normal portion. An image is obtained.
For this reason, when the patterns (through holes) are regularly arranged at a predetermined pitch as in a shadow mask, the defect is obtained by taking the difference between a pair of image data taken before and after shifting only the sample by the pitch. A defect portion can be extracted by binarizing the differenced image data at a predetermined slice level.
[0017]
【The invention's effect】
As described above, the present invention makes it possible to provide a surface inspection apparatus and method for etching products such as shadow masks that have high detection sensitivity and are easy to work with.
[Brief description of the drawings]
FIG. 1A is a schematic cross-sectional view of an example of a surface defect inspection apparatus according to the present invention, and FIG. 1B is a schematic view of an imaging unit.
FIG. 2 is a diagram for explaining a mirror arrangement of an example of a surface defect inspection apparatus of the present invention. FIG. 3 is a flowchart showing an example of a surface defect inspection method of the present invention. FIG. 5 is a diagram for explaining the optimum photographing angle. FIG. 5 is a diagram for explaining the difference in the optimum photographing angle at each position of the shadow mask.
DESCRIPTION OF SYMBOLS 100 Inspection apparatus 110 Image | photographing means 113 Lens 115 Image pick-up surface 117 Cable 120 Light source 130 XY stage 140 Mirror 150 Image processing part 160 Television monitor 170 Oblique light 171 Reflected light 180 Sample 180A Inspection area 410 Through-hole 411 Taper part 420 Egret defect part 430 Corner light 480 Shadow mask 510 Through-hole portion 511 Taper portion 580 Shadow mask θ1 to θ5 Optimal shooting angle

Claims (5)

An apparatus for detecting surface defects of shadow mask etching products, through an XY stage that can hold an inspected sample and move in an XY manner, and a lens for photographing an inspection area of the sample Arranged so as to surround the inspection area of the sample between the sample and the imaging means, a planar imaging means of the type that allows light to reach the imaging surface, a light source for imaging provided on the opposite side of the imaging means of the sample An image for extracting defects by performing image processing based on a plurality of mirrors that reflect oblique light that has passed through the inspection area of the sample to reach the imaging means and image data obtained by imaging the inspection area of the sample The imaging means for imaging the inspection area of the sample through a mirror, and changing the angle between the sample surface of the oblique light passing through the inspection area of the sample to be imaged and the sample surface Distance from It is provided to be continuously moved in order to obtain a surface defect inspection apparatus according to claim.   The image processing unit according to claim 1 obtains a pair of image data before and after the pattern of the sample is shifted by the photographing unit at each photographing position of a plurality of photographing positions having different distances from the sample surface of the photographing unit, After obtaining difference image data obtained by taking the difference between the pair of image data, the obtained difference image data at each photographing position is binarized directly or indirectly to obtain binarized image data. A surface defect inspection apparatus for extracting a defect portion. By the oblique transmitted through the inspection area of etched products of the shadow mask taken through the mirror, and image processing the image data obtained, a method of detecting surface defects, between the sample and the imaging means A plurality of mirrors that reflect oblique light that has passed through the sample inspection area and that allows light to reach the imaging means, and move the imaging means to inspect the imaging means and the sample surface to be inspected. By photographing at different positions with different distances, the angle formed with the sample surface of the oblique light passing through the inspection area of the sample to be photographed is changed several times, and at each photographing position of the photographing means Then, after obtaining a pair of image data before and after shifting by the pitch of the pattern of the sample, obtaining difference image data obtained by taking a difference between the pair of image data, the obtained difference data is obtained. By image processing, respectively, the surface defect inspection method characterized by detecting a surface defect.   4. The surface defect inspection method according to claim 3, wherein the direction of oblique light transmitted through the inspection region of the etched product of the shadow mask obtained from the mirror is omnidirectional.   In the image processing according to claims 3 to 4, the difference image data obtained at each position of the photographing means is binarized directly or indirectly to obtain binarized image data, and a defective portion is extracted. A method for inspecting a surface defect, characterized in that:

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