JPH11326224A - Inspection method and inspection device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To precisely inspect fine defects and the like existing on the surface and inside of a non-opaque substance. An object is irradiated with coaxial incident light from a coaxial incident light source to obtain an image of a surface defect. The scattered light source 31 is turned on to irradiate the object with the scattered light to obtain an image including images of surface defects and internal defects. When the image due to the scattered light is compared with the image due to the coaxial incident light, and the image of the same defect is removed from the image due to the scattered light, an image of only the internal defect is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an inspection method and an inspection apparatus. For example, the present invention relates to an inspection method and an inspection apparatus capable of inspecting a surface and an internal defect of a non-opaque substance using coaxial reflected light (coaxial incident light) and scattered light.

[0002]

2. Description of the Related Art In a glass substrate used for a liquid crystal display panel, a lens layer is provided inside a glass substrate, and an ITO layer is provided on the surface.
Some have a transparent electrode such as a film. For example, FIG.
1 shows a glass substrate 1 with a microlens array for a projector, in which a cover glass 2 and a base glass 3 constitute a glass substrate, and two layers of transparent resin having different refractive indices between the cover glass 2 and the base glass 3. Layer 4,
A lens layer (microlens array pattern) 6 is formed at the interface by sandwiching the transparent electrode 5 and a transparent electrode (IT) made of a thin film of metal and metal oxide is formed on the surface of the cover glass 2.
O film) 7 is formed.

In such a glass substrate manufacturing process, product inspection of the manufactured glass substrate is required.
In the case of a glass substrate having a surface inspection object (transparent electrode) and an internal inspection object (lens layer), such as a glass substrate with a microlens array for a projector, it is difficult to find defects by product inspection. The reason why such a defect inspection is difficult is that the required specifications are 5 μm or less for a defect occurring on the surface of the transparent electrode and 15 μm or less for a defect occurring on the internal lens layer, and a minute defect must be inspected. In addition, there is a great difference between the specifications of surface and internal defects. That is, the difficulty is a defect that separates a minute defect (it is very difficult to recognize the minute defect first) into a surface and an inside, and exists in either the surface or the inside. Must be specified (in fact, it is difficult to specify).

Incidentally, a glass substrate for a liquid crystal display panel is provided with a transparent electrode and a color filter on the surface. However, in a display device such as a notebook personal computer, which is a main application, a screen is directly viewed with the naked eye. The spec of the defect is a level determined at around 0.1 mm (things that are not visible to the human eye are not defects), but in a liquid crystal display panel for a projector, since the image is enlarged and displayed on a screen, the glass in contact with the liquid crystal Even fine defects with a diameter of about 5 μm are not allowed on the surface (transparent electrode) of the substrate. In other words, it is difficult to manufacture a product free from defects in a product requiring such strict specifications, but it is also difficult to inspect the product.

(Conventional inspection method) FIG.
A conventional inspection apparatus 9 using a CD camera 8 illuminates the surface of an inspection object 11 with a reflected light source 10 and illuminates the inspection object 11 from the back side with a transmitted light source 12, and The CCD camera 8 receives the light from the reflected light source diffusely reflected by the above and the light from the transmitted light source transmitted through the inspection object 11, and finds a defective portion having a different shape from the peripheral portion.

FIG. 3 shows an inspection method using a laser beam, which is mainly used for inspection of a silicon wafer.
This is to inspect a defect by irradiating a laser beam output from a laser oscillator 13 to an inspection object 11 and receiving a laser beam specularly or diffusely reflected on a surface of the inspection object 11 by a light receiving unit 14. It is.

The inspection apparatus or inspection method shown in FIGS. 2 and 3 is, for example, an LCD (Liquid Crystal Display) or a PD.
For finding defects such as color filters and circuit electrodes on the surface of glass substrates and plastic substrates such as P (plasma display panels), and defects in circuit patterns laminated on the surface of silicon wafers. Is valid.

However, as shown in FIG. 2 or FIG. 3, in the inspection method using transmitted light or reflected light, for example, a glass substrate in which a lens layer formed by a resin layer interface is formed as an object to be inspected. In this case, there is a disadvantage that the internal inspection cannot be performed. In the inspection of glass substrates with microlens arrays for projectors,
Not only can fine defects not be found, but also the focus adjustment becomes strict even when the magnification is increased, so that it is difficult to find relatively large defects depending on the type of defect.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to remove fine defects and the like existing on the surface and inside of a non-opaque substance. An object of the present invention is to provide an inspection apparatus and an inspection method capable of performing an inspection with high accuracy. Another object of the present invention is to provide an inspection method that can be efficiently performed when inspecting a plurality of inspection objects.

[0010]

According to a first aspect of the present invention, there is provided an inspection method, wherein the same area of an inspection object is irradiated a plurality of times by irradiating illumination light with different illumination methods, and these observation results are compared. The inspection object is inspected by performing the inspection.

According to a second aspect of the present invention, in the inspection method according to the first aspect, the illumination system includes at least a coaxial incident illumination and a scattered light illumination.

According to a third aspect of the present invention, in the inspection method of the first aspect, images of the inspection object observed by different illumination methods are stored in a storage device, and these images are compared. In this case, only a specific type of defect is separated.

[0013] The embodiment described in claim 4 is claim 1.
In the inspection method described in 2 or 3, when a defect is detected in the inspection object, an inspection from a position where the defect exists to a predetermined position is not performed.

An embodiment according to claim 5 is a device according to claim 1,
In the inspection method described in 2 or 3, when inspecting a plurality of inspection objects having a plurality of product areas, if a defect is detected at substantially the same location on different inspection objects, the defect information is recorded. When inspecting the inspection object, in the product area where the defect is recorded in the defect information,
The defect position recorded in the defect information is inspected first.

[0015] The embodiment described in claim 6 is the first embodiment.
In the inspection method according to 2 or 3, when inspecting a plurality of inspection objects having a plurality of product areas, a defect is detected at almost the same location of a different inspection object, and a defect detected at the approximately same location is detected. When the number of product areas has reached a predetermined number or more, a notification is given.

According to a seventh aspect of the present invention, there is provided an inspection apparatus for irradiating an inspection object with light for inspection, a plurality of illumination units of different illumination systems, and an image of the inspection object illuminated by the illumination unit. And an imaging device for obtaining.

[0017]

The inspection method according to claims 1, 2 and 3 of the present invention or the inspection apparatus according to claim 7 compares images of an inspection object illuminated by different illumination systems. If the illumination method is different, a defect specific to the illumination method can be detected, but an image obtained by one illumination method may include a plurality of defects. However, comparing images obtained by a plurality of illumination methods makes it possible to detect only a specific type of defect.

In particular, when coaxial epi-illumination and scattered illumination are used as illumination methods, scattered illumination can observe internal defects as well as surface defects of the inspection object, but coaxial epi-illumination can observe only surface defects. By comparing images obtained by the two illumination methods, it becomes possible to detect an internal defect. That is, it is possible to easily perform the inspection of the internal defect, which has been difficult to inspect conventionally.

In the inspection method according to the fourth aspect, when performing a defect inspection of the inspection object by the inspection method of the first, second, or third aspect, if a defect is detected in the inspection object, the defect is detected. The inspection from the existing location to the predetermined location is not performed.

When a defect is detected in the inspection object,
Since the whole or a part of the inspection object becomes a defective product, if a defect is detected, the inspection is not performed up to a predetermined position, so that a useless inspection time can be reduced and the inspection process can be made more efficient. can do.

The inspection object may be a single product as a whole or may be divided into a plurality of products. In the former case, the case where the inspection is not performed up to the predetermined location includes the case where the inspection is not performed after the location where the defect is detected. In the latter case, it is usually desirable to skip the inspection until the end of the product area where the defect is detected.

In the inspection method according to the fifth aspect, when inspecting a plurality of inspection objects having a plurality of product areas by the inspection method according to the first, second, or third aspect, substantially the same portions of different inspection objects are inspected. When a defect is detected in the, the defect information is recorded. When a defect is repeatedly detected at substantially the same location, it is highly probable that a defect will be detected at the same location in a subsequent inspection object. In the case of an article reproduced by a mold such as a stamper, the probability is particularly high.

Therefore, when inspecting the inspection object, in the product area where the defect recorded in the defect information exists, the defect position recorded in the defect information is inspected first. If a defect is detected there, the inspection of the product area is not performed, so that useless inspection can be omitted.

It should be noted that the number of times of defect detection for performing this process can be predetermined such as two or three or more predetermined times.

In the inspection method according to the sixth aspect, when performing the defect inspection of the inspection object by the inspection method according to the first, second, or third aspect, the number of defective product areas including defects becomes a predetermined number. When it is notified, it is notified.If notified, the inspection process of the inspection object is inspected and maintained, and the place where abnormality occurs is cleaned or cleaned, defective parts of manufacturing equipment, etc. By exchanging the components, it is possible to reduce repetitive defects.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to an embodiment. In the inspection method of the present invention, for inspecting an inspection object such as a glass substrate with a microlens array for a projector, a CCD camera is first employed as an inspection means, and coaxial incident illumination is used for surface inspection. For the internal inspection, an inspection method using scattered light illumination as a light source was used. Here, the coaxial epi-illumination is used for a microscope or the like, and irradiates a substantially parallel light beam. The coaxial incident light is transmitted through a pinhole (ITO) of the ITO film.
Even when there is no defect, as in the case where the film is not attached, and the defect is not delicate, it can be seen well. The scattered light illumination irradiates the observation position with scattered light from the surroundings, and is close to uniform illumination.

That is, for inspection of severe surface defects,
The light source is a coaxial epi-illumination that allows only surface defects to be seen and fine defects of about 3 to 5 μm to be seen well. On the other hand, for inspection of an internal defect having a comparatively gentle reference as compared with the surface, scattered light is used as a light source. Since surface defects can be seen with scattered light illumination, when using scattered light illumination, the magnification of surface defects is adjusted to be smaller than that of internal defects, but surface defects that can still be seen are coaxial in advance (or simultaneously). Surface defects are separated by performing image processing and comparing with an inspection image (image taken by a CCD camera) inspected by epi-illumination.

FIG. 4 is a schematic diagram showing the configuration of an inspection apparatus 21 that uses both coaxial incident illumination and scattered light illumination. In the inspection device 21, an imaging device 23 such as a CCD camera is provided in an upper part in a lens barrel 22. This imaging device 2
3 forms an enlarged image of the inspection object 25 on the CCD element 26 through the lens system 24 and outputs an image signal through the electric circuit 27, as shown in FIG. A half mirror 28 and an objective lens 29 are arranged below the imaging device 23. A coaxial incident light source 30 is provided on the side of the half mirror 28. When the coaxial incident light source 30 is turned on, the coaxial incident light emitted from the coaxial incident light source 30 is:
After being reflected by the half mirror 28 and passing through the objective lens 29, it is irradiated on the surface of the inspection object 25 almost perpendicularly.
Further, a scattered light source 31 having a ring shape surrounding the optical axis of the imaging device 23 is provided at a position below the objective lens 29 and close to the inspection object 25. Since the scattered light source 31 has a ring shape, the inspection point of the inspection target 25 is irradiated with light obliquely.

In such an inspection apparatus 21, the coaxial incident light source 30 is turned on, and the inspection object 25 is irradiated with coaxial incident light.
FIG. 6 shows a state in which coaxial reflected light reflected on the surface of the inspection object 25 is captured by the imaging device 23. In the inspection using the coaxial incident light, almost the surface (the thin film I
(To the bottom of the TO film 7), and surface defects 32 such as adhesion of foreign substances on the surface and pinholes of the ITO film can be detected. However, internal defects 33 such as a lens layer and scratches on a glass substrate can be detected. No back surface defect 34 is detected. FIG. 8 shows an example of an inspection image using coaxial incident light. In the coaxial incident image, the defect 35 appears as a black dot. In the case of pinhole 42,
The scattered light cannot be detected because the reflected light is scattered and radiated as shown in FIG. 16B, but the coaxial reflected light cannot be detected as shown in FIG.
It is detected because it is reflected straight like.

On the other hand, in an inspection in which the scattered light source is turned on, the inspection object 25 is irradiated with the scattered light, and the scattered light reflected by the inspection object 25 is photographed by the imaging device 23, as shown in FIG. In addition, surface defects 32 such as adhesion of foreign substances on the surface and pinholes of the ITO film, internal defects 33 such as a lens layer, and back surface defects 34 such as scratches on a glass substrate are all detected.
FIG. 9 shows an example of an inspection image using scattered light. In the inspection image using the scattered light, both the surface defect and the internal defect are defects 36.
Can be seen as bright spots. The scattered light cannot detect a pinhole as shown in FIG.
Is detected by scattered light.

When an inspection image using coaxial incident light and an inspection image using scattered light are thus obtained, surface defects and internal defects are separated therefrom. Figure 1 shows a method for separating surface defects and internal defects.
0 schematically. In the scattered light illumination, all defects are visible as shown in FIG. 10 (a). Therefore, the same area is captured by the coaxial incident light image, and the same shape is obtained at the same position. (FIG. 10B) is a surface defect, and is removed from the image due to the scattered light. The image 37 with the surface defects removed is shown in FIG.
(C), which shows only internal defects.

In order to determine whether the defect in the image obtained by the coaxial epi-illumination and the defect in the image obtained by the scattered light illumination are the same, as described above, it is necessary to determine whether the defect is at the same position. Judgment is made based on whether they have the same shape. For example, FIG.
As shown in FIG. 1, if the X-direction coordinates of the edge of the defect in the X-axis direction are X1 and X2, the center of the defect can be obtained by XC = (X1 + X2) / 2,
Assuming that the Y-direction coordinates of the edge of the defect are Y1 and Y2,
The center can be obtained by YC = (Y1 + Y2) / 2. Therefore, if the centers (XC, YC) match, it is determined that they are at the same position. However, since the defect is minute, a shift amount of, for example, about 50% of the center (XC, YC) may be determined to be the same coordinate.

When the shape of the defect is as shown in FIG. 12A, the X axis is moved from the X1 axis to the X2 axis, and the area of the defect between the X axis and the X1 axis is plotted on the horizontal axis. ,
Move the Y axis from the Y1 axis to the Y2 axis, and
When the area of the defect between the axes is plotted on the ordinate, FIG.
It is assumed that a curve as shown in FIG. When the curves substantially match, it is determined that the two defects have the same shape.
However, the divided area element (matrix) needs to be reduced to an appropriate size according to the accuracy.

In addition to the above, according to the required accuracy,
Various image discrimination methods generally used in image processing can be used. For example, it may be determined whether or not the two images are the same by superimposing images of two defects.

FIG. 13 is a diagram showing a way of displaying on the monitor 38. In this example, the image of the scattered light illumination and the image of the coaxial incident light illumination in the same region of the inspection object are displayed side by side on the same monitor, but the image of only the internal defect can be displayed on the monitor 38, or An image of only a surface defect and an image of only an internal defect can be displayed side by side on the same monitor, which can assist visual judgment.

FIG. 15 is a flowchart showing a procedure of a processing method by the inspection apparatus. First, a scattered light source is turned on to irradiate the inspection object with the scattered light, and an image using the scattered light as a light source is captured (S1). This image is called an image P1. Then
The coaxial incident light source is turned on, and an image using the coaxial incident light as a light source is captured (S2). This image is called an image P2. Thereafter, the image P1 due to the scattered light is inspected to determine whether or not a defect having the same coordinates exists in the image P2 (S3). If there is no defect having the same coordinates in the image P2, it is determined that the defect is an internal defect (S4).

On the other hand, if a defect having the same coordinates exists in the image P2, it is further checked whether the defect has the same shape (S5). If the shapes are not the same, it is also determined to be an internal defect. If they have the same shape,
Since the defects are the same, it is determined that the defect is a surface defect (S6). If it is determined that the defect being inspected is a surface defect, the image of the defect is deleted from the image P1 due to the scattered light (S7).

In this way, the defects contained in the image P1 due to the scattered light are sequentially examined, and those determined as surface defects are deleted from the image P1 (S1 to S5).
Repeat step 7). When all the defects of the image P1 are processed in this way (S8), only the internal defects remain in the image P1. Therefore, the image P1 is displayed on the monitor as an image of the internal defect, and the image P2 is displayed on the monitor as an image of the surface defect (S9).

Although back side defects have not been considered so far, back side defects can be detected by inspecting the inspection object from the back side with coaxial incident light. Therefore, as shown in FIG. 14, an inspection image 36 using scattered light illumination [FIG. 14 (a)] is converted into a surface defect image 35 [FIG. 14 (b)] obtained by coaxial irradiation on the front side and the back side, respectively. ] And the image 39 of the back surface defect [FIG. 14 (c)], an image 40 [FIG. 14 (d)] of only the internal defect which does not include the surface defect and the back surface defect can be obtained.

(Effects of the present invention) In the embodiment described above, the same surface of a non-opaque substance is viewed twice by using coaxial incident light and scattered light by using coaxial incident light and scattered light illumination. The surface and inside defects could be inspected and observed accurately and favorably. In particular, this inspection method is effective when there is a layer having a different refractive index inside the transparent body, or when there is a transparent thin film of a metal compound such as a metal oxide on the surface. Hereinafter, the principles and effects of the present invention will be described in detail.

First, the present invention is effective for inspection of a non-opaque substance, particularly a foreign substance (defect) when there is a layer having a different refractive index inside. If there is a layer having a different refractive index inside, it often becomes a lens layer in general, depending on the shape.
If there is a lens layer, transmitted light is collected, and there are layers that cannot be seen depending on the focusing method. Even if there is a defect in the lens layer (defective formation of the lens layer), if the lens layer is formed to some extent, the transmitted light is condensed. Therefore, the transmitted light is not suitable for inspection of whether the lens is formed well. . By the way, if you mix the transmitted light with the reflected light, some of the internal defects can be seen,
Most of the internal defects cannot be seen with transmitted light, reflected light or a combination of transmitted light and reflected light.

In the present invention, if scattered light illumination or the like, which is generally called ring illumination, is used, light irradiated from all directions in the inspection area hits a foreign substance or defect, and is irregularly reflected on the surface of the foreign substance or defect. The presence of foreign matter and defects can be known from the irregular reflection. Actually, the foreign matter and the defect appear as large as about one to two circumferences (as bright spots) due to the irregularly reflected light. Therefore, the scattered light is effective for inspecting a substrate having a multilayer structure.

However, the scattered light is visible even to surface defects. When inspecting a surface defect and an internal defect with the same reference (for example, the same size as a criterion), only the scattered light may be used, but it is troublesome when the reference of the surface defect and the internal defect is different. Although the reflected light is generally effective as a light source for inspection for observing the surface, it is not suitable for minute defects such as the inspection object of the present invention, and some of the minute defects are hardly visible depending on the type. . Specifically, the foreign matter can be seen relatively well, but a circular defect, generally called a pinhole, in which a part of the film is missing, was not well seen. Thus, we have found that a light source, commonly referred to as coaxial incident light, allows the pit (hollow) to look good. This coaxial incident light is suitable only for surface inspection of a glass substrate (multilayer glass substrate) because it can be seen only below a thin film (for example, an lTO film) formed on the surface.

Next, in the present invention, the internal defect and the surface defect can be separated by comparing the "image by scattered light" and the "image by coaxial incident light". Inspection using scattered light allows both internal defects and surface defects to be seen, but by comparing the image with coaxial incident light, which only shows surface defects, it is possible to identify only internal defects. In the comparison, the same area can be sufficiently observed visually, for example, by dividing the monitor into two parts.

Therefore, if an inspection apparatus based on the principle of the above inspection method is used, it is effective as an inspection apparatus for a multilayer glass substrate. In order to make it a device, the same area is scattered light
What is necessary is just to image by seeing with two kinds of light sources, and "coaxial incident light". In order to determine the same area or the same coordinates, a standard is set in advance for the inspection object, and based on the standard,
What is necessary is just to synchronize the captured image.

When an image of the scattered light and an image of the coaxial incident light are processed in the same region, an automatic inspection apparatus capable of separating a surface defect from an internal defect is obtained. In order to perform processing by the automatic inspection apparatus, for example, as shown in the above-described flowchart (FIG. 15), it is determined whether defects in two images of the same area viewed by two types of light sources are the same coordinates or the same shape. , Can isolate defects. Since the defect image of the scattered light looks larger than it actually is, the image of the scattered light may be reduced at a fixed rate, or the image of the coaxial incident light may be increased at a fixed rate, or may be subjected to one of the processes and superimposed. In addition, it is possible to ignore the size and determine only the shape.

In the inspection method of the present invention, a back surface defect can be separated. For the back surface, if the same processing as that for the front surface (the inspection object is viewed from both sides with coaxial incident light and three images are compared), the back surface defect can also be separated.

In the above embodiment, the coaxial epi-illumination and the scattered light illumination are used as the illumination method. However, other than this, the transmitted illumination by the surface light source (suitable when only the outer shape of the object is required). , Oblique illumination (suitable for those having metal irregularities), indirect illumination (transmission type or reflection type), illumination by radiant light, and the like. good.

(Continuous Inspection Step) Next, a processing method for continuously and efficiently inspecting an inspection object in a manufacturing process will be described. First, before this description, a manufacturing process of a glass substrate with a microlens array to be inspected will be described with reference to FIGS. When manufacturing a glass substrate with a microlens array, FIG.
As shown in (a), a transparent base glass 5 having a size of a plurality of glass substrates with a microlens array is provided.
An uncured UV-curable resin (UV-curable lens resin) 53 is dropped on the base 2, and a stamper (mold) 54 is lowered from above the base glass 52 so that the UV-curable resin is between the stamper 54 and the base glass 52. The resin 53 is sandwiched, and the stamper 54 is pressed against the base glass 52 to spread the ultraviolet curable resin 53 between the stamper 54 and the base glass 52. On the lower surface of the stamper 54, an inversion mold 55 of a lens layer (microlens array pattern) is formed. Next, as shown in FIG. 17B, ultraviolet rays are applied to the ultraviolet curing resin 53 through the base glass 52,
The ultraviolet curing resin 53 is cured. When the stamper 54 is peeled off, a lens layer pattern 56 is formed on the upper surface of the cured ultraviolet curable resin 53 as shown in FIG.

Further, as shown in FIG. 17D, an uncured UV-curable resin 57 having a different refractive index from the UV-curable resin 53 is dropped on the UV-curable resin 53, Cover glass 58 from above resin 57
Is lowered to sandwich the uncured UV-curable resin 57 between the lower UV-curable resin 53 and the cover glass 58, and the cover glass 58 is pressed against the UV-curable resin 57 so that the UV-curable resin 57 is UV curable resin 5
3. Spread between 3 and cover glass 58. Next, FIG.
As shown in FIG. 8E, the ultraviolet-curable resin 57 is irradiated with ultraviolet light through the base glass 52 and the ultraviolet-curable resin 53 to cure the ultraviolet-curable resin 57. As a result, a microlens array wafer (hereinafter, referred to as an MLA wafer) 59 of a plurality of glass substrates with a microlens array is manufactured, and a lens layer 60 is provided at the interface between two ultraviolet curable resins 53 and 57 having different refractive indexes. It is formed.

When the MLA wafer 59 is manufactured, FIG.
As shown in FIG.
Is ground and the upper surface of the cover glass 58 is polished to smooth the surface, and the parallelism between the front and back of the MLA wafer 59 is obtained.
Thereafter, as shown in FIG.
A transparent electrode (ITO film) 62 is formed on the upper surface of the substrate by an evaporation method.

When the inspection is completed in this way, as shown in FIG. 19, the MLA wafer 59 is positioned by the alignment mark 63, and then the MLA wafer 59 is cut along the cut line C, and the individual glass substrates 51a and 51b with microlens arrays are cut. , 51c,... (FIG. 19 shows a case of taking 14 sheets).

However, the MLA wafer 5 is
9 to a glass substrate 51a with a microlens array,
.. Are manufactured, foreign matter 64 such as dust or dust adheres to the lower surface (pattern surface) of the stamper 54 or the pattern surface has a defect 6 as shown in FIG.
20B, the foreign matter 64 and the defect 65 are transferred to the ultraviolet-curing resin 53 as shown in FIGS. 20B and 20C. As a result, the manufactured MLA wafer 59 has the structure shown in FIG.
Fixed point defects 66a and 66b as shown in FIG.

Therefore, conventionally, the MLA wafer 59 is cut and divided into glass substrates 51a, 51b, 51c,... With microlens arrays, and then the glass substrates 51a, 51b, 51 with microlens arrays are cut.
c,... each time a defect inspection was performed. Further, glass substrates 51a, 51b, 51c with microlens array,
.. Are minute, one glass substrate 51a, 51b, 51c,... With a microlens array is virtually divided into a plurality of (for example, 12) inspection areas (that is, enlarged). A defect inspection was being performed.

Glass substrate 51 with microlens array
a, 51b, 51c,... have been inspected as described above. However, since such an inspection object has a fine optical pattern, it takes a long time to inspect, and improvement in inspection efficiency is expected. It is rare. In particular, in a glass substrate with a microlens array replicated by a stamper, if a foreign matter or the like adheres to the stamper or the pattern surface is lost and a defect occurs, a defect of the same shape at a same place, that is, a fixed point defect, continues. Therefore, in order to reduce the defective product occurrence rate, it is desired that such a fixed point defect can be found and dealt with at an early stage.

The inspection method of the present invention described here is devised from such a point of view, and is used in the appearance inspection of an inspection object such as a glass substrate with microlens array 51a, 51b, 51c,. A fixed-point defect that repeatedly occurs in the inspection object due to the defect of the stamper 54 is detected early, and the inspection object having the fixed-point defect is skipped after that, thereby shortening the inspection time, and If the number of inspection objects exceeds a certain level, maintenance (cleaning,
Exchange, etc.).

FIGS. 21 and 22 are flowcharts for explaining an inspection method for efficiently executing an inspection. Also,
FIG. 23 is a schematic diagram illustrating this inspection system. The MLA wafer 59 to be inspected is placed on the inspection table 67 and kept stationary. The inspection device (image pickup device, light source, etc.) 68 of the present invention is
9, and the movable table 69 can travel along a rail (not shown) in parallel with the inspection table 67. The moving table 69 is driven by the driving device 70, and the moving direction and the moving distance of the inspection device 68 are precisely numerically controlled by the table drive control unit 71.
The data obtained by the inspection device 68 is processed by the determination processing section 72 to determine the position and type of the defect. Data such as the position and type of the defect detected by the determination processing unit 72 is stored in a storage device 73 composed of a writable memory. Further, the determination output section 74 comprehensively determines the detection results of the determination processing section 72 to determine which of the glass substrates with microlens arrays 51a, 51b, 51c,... Has a defect, and outputs the result. I do. In addition, on the contrary,
The MLA wafer 59 is placed on the inspection table 67, and the ML on the inspection table 67 is
The inspection may be performed by moving the A wafer 59.

Hereinafter, a method of inspecting the MLA wafer 59 will be described with reference to the above flow chart. First, the MLA shown in FIG.
A case where the inspection of the MLA wafer 59 having no defect like the wafer 59 is performed will be described. One MLA wafer 59 with a transparent electrode is made up of 14 glass substrates with microlens arrays (hereinafter referred to as chips) 51a, 51b,
, Each chip 51a, 51b, 51c,
Are divided into twelve inspection areas 75a, 75b, 75c, and are inspected. When the inspection of the MLA wafer 59 is started, the inspection device 68
1 is sent to the first chip 51a (S33). Next, the determination processing section 72 reads out fixed-point defect information of the MLA wafer 59 (hereinafter, sometimes referred to as a “previous wafer”) inspected earlier from the storage device 73 (S12), and fixes the fixed-point defect to the chip 51a at that position. It is checked whether or not is recorded (S13).

As a result, if the fixed point defect is not recorded on the chip 51a at the position, the inspection device 68 is moved to the inspection area 75a at the head of the chip 51a (S20), and the defect is detected in the inspection area 75a. An inspection is performed (S21), and the presence or absence of a defect is checked (S22). As a result of the inspection, if there is no defect in the inspection area 75a, the inspection device 6
8 is sent to the next inspection area 75b (S29, S30), and a defect inspection is similarly performed on the inspection area 75b (S29).
21), the presence or absence of a defect is checked (S22).

Until the inspection of one chip 51a is completed (S30, S31), steps S21, S22, S
When the process of step 29 is repeated and the defect inspection of one chip 51a is completed, the inspection device 68 is moved to the next chip 51b (S11). Then, similarly to the case of the first chip 51a, it is checked whether or not a fixed point defect is recorded (S12,
S13) If there is no fixed point defect recorded in the chip 51b at that position, all the inspection areas 75a, 75 of the chip 51b
b, 75c,... are sequentially inspected (S20 to S22, S2
9-S31).

Such an inspection process for each chip is repeated until the process is completed for one MLA wafer 59 (S3).
1). As a result, one MLA wafer 59 is placed in all inspection areas 75a, 75a in the order shown by the dashed arrow in FIG.
, 75c,... will be inspected. Thus ML
When the inspection of the A wafer 59 is completed, the determination output unit 74 outputs a signal indicating that there is no abnormality.
Exchange the LA wafer 59 for the next MLA wafer 59 (S3
2) Similarly, the next MLA wafer 59 is inspected.

Next, as shown in FIG.
The case of the MLA wafer 59 having a defect 76 (one not yet a fixed point defect) will be described. The inspection process of the chips 51a, 51b, 51d,... Having no defect is omitted, and the inspection process of the chip 51c having the defect 76 will be described.
When the inspection device 68 moves to the chip 51c having the defect 76 (S11), the determination processing unit 72 reads out the fixed point defect information of the "previous wafer" from the storage device 73 (S12), and the fixed point defect is recorded on the chip 51c at the position. It is checked whether or not it has been performed (S13).

As a result, when the fixed point defect is not recorded on the chip 51c at the position, the inspection device 68 is moved to the head inspection area 75a of the chip 51c (S20), and the defect is detected in the inspection area 75a. An inspection is performed (S21), and the presence or absence of a defect is checked (S22). As a result of the inspection, if no defect is detected in the inspection area 75a, the inspection device 68 is sent to the next inspection area 75b (S29, S3
0) Similarly, a defect inspection is performed on the inspection area 75b there (S21), and the presence or absence of a defect is checked (S22).

Thus, each inspection area 75a, 75b, 75
When the defect 76 is detected in a certain inspection area 75g during the inspection by c,... (in the case of YES in S22), the determination processing unit 72 reads the defect information of “all wafers” from the storage device 73 (S23). And) comparing the detected defect with the defect information of the "previous wafer". Then, the detected defect 76 is at the same position as the defect of the “previous wafer” (S24), the detected defect 76 is an internal defect or a surface defect (S25), and the detected defect 76 is the same as the defect of the “previous wafer”. Then, it is checked whether the shapes are similar (S26). Then, when the conditions (1) to (4) are satisfied, the defect 76 is determined to be a fixed point defect, and the defect information is recorded in the storage device 73 as the fixed point defect (S17). Here, when the same defect is detected twice, it is recognized as a fixed-point defect. However, it may be recognized as a fixed-point defect by performing detection three or more times.

After newly recording as a fixed point defect, FIG.
As shown by the dashed arrow in FIG. 5, the remaining inspection of the chip 51c having the fixed point defect is skipped, and the next chip 51d is skipped.
Then, the chip 51d is moved to the inspection area 75a and inspected (S17 → S18 → S11).

After the fixed point defect is recorded, the number of chips where the fixed point defect is detected is checked. If the number of chips having the fixed point defect reaches a predetermined number or more, the inspection is performed as shown in FIG. Step 79 to the lens replication step 77 which is the previous step
[FIG. 17 (a), (b) and (c)], and at the same time, outputs a production stop and maintenance request to the lens duplication step 77 (S19). The lens sealing step 78 shown in FIG.
Means the steps shown in FIGS. 17D and 18E. The notification means is not particularly limited, such as turning on a lamp, sounding a buzzer, and displaying on a display.

When the notification is received from the inspection step 79, the lens duplication step 77 is stopped, and the stamper 54 and the like are inspected. If the fixed point defect is caused by a foreign substance attached to the stamper 54 or the like, the stamper 54 is cleaned. If the pattern surface of the stamper 54 has a defect such as chipping or crushing, the stamper 54 is replaced.

On the other hand, if any of the conditions is not satisfied, it is determined that the defect 76 is not a fixed point defect (that is, a defect different from the defect of the "previous wafer"), and the storage device 73 The defect information is recorded as a defect (a defect that is not recognized as a fixed point defect) (S27). After recording the defect, the chip moves to the next inspection area 75h (S28), and the inspection of the chip 51c is continued (S21 to S21).

Next, as shown in FIG.
The case of the MLA wafer 59 having the fixed point defect 80 will be described. The inspection process for the chips 51a, 51b, 51d,... Having no defect is omitted, and the chip 51c having the fixed point defect 80 is omitted.
The inspection process will be described. When the inspection device 68 moves to the chip 51c having the fixed point defect 80 (S11), the determination processing section 72 reads out fixed point defect information (presence or absence of a fixed point) of the "previous wafer" from the storage device 73 (S12), It is checked whether a fixed point defect is recorded in 51c (S13).

If a fixed point defect is recorded in the chip 51c at the position, the determination processing section 72 reads defect information (detailed defect information) of the "previous wafer" from the storage device 73 (S14). Next, the inspection device 68 is moved to the inspection area 75g at the position recorded in the defect information, and an inspection is performed to determine whether or not a defect (fixed point defect) exists (S1).
5) It is checked whether a fixed point defect exists at the same position as the recording (S16).

If a fixed point defect cannot be detected at the recorded position, the chip 51
Defects are sequentially inspected from the first inspection area 75a of c (S
20-).

On the other hand, if the fixed point defect 80 exists at the same position, it is recorded in the defect information of the storage device 73. When the fixed point defect is recorded in this manner, as shown by the broken line arrow in FIG. 26, the chip 51c is moved to the inspection area 75a of the next chip 51d without being inspected for a defect, and the chip 51d is inspected (S17 → S18). → S1
1).

In the replication method using a stamper, the productivity of an MLA wafer, a glass substrate provided with a microlens array, and the like is remarkably superior to a production method using etching. However, because of the duplication method, a fixed point defect may easily occur due to a foreign substance or the like.

According to the inspection method of the present invention, as described above, if a defect that can be regarded as having the same shape at the same location of the inspection object in the same lot is duplicated, For the corresponding chip, first check the fixed-point defect location, and if it is confirmed that there is a defect, the inspection of that chip can be terminated and the inspection of the next chip can be started. It can be omitted to shorten the inspection time.

Further, according to the inspection method of the present invention, when the number of chips having a fixed point defect reaches a predetermined number, it is notified to the lens duplication process to urge production stop and maintenance, and promptly to clean or replace the stamper. In addition, the defective rate of occurrence of the glass substrate with the microlens array can be reduced.

Further, since the inspection step is performed immediately after the sealing step, the feedback time from the inspection step to the lens duplication step can be shortened, and the production of a glass substrate with a microlens array including fixed point defects can be achieved. Can be stopped in a minimum time, and the defective product incidence rate of the glass substrate with the microlens array can be further reduced.

Further, the criterion of the notification is not the number of fixed point defects but
Since the number of fixed point defects is concentrated on some chips, the number of fixed point defects is not notified even if the number of fixed point defects is large. Defect management can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a defect generated in a glass substrate.

FIG. 2 is a schematic view showing a conventional inspection method.

FIG. 3 is a schematic view showing another conventional inspection method.

FIG. 4 is a schematic diagram showing an inspection device according to one embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of an imaging device.

FIG. 6 is a diagram illustrating an inspection state using coaxial incident light.

FIG. 7 is a diagram illustrating an inspection state using scattered light.

FIG. 8 is a diagram illustrating an example of an image using coaxial incident light.

FIG. 9 is a diagram illustrating an example of an image due to scattered light.

FIG. 10 is a diagram schematically illustrating a process of removing an image of a surface defect from an image including all defects to obtain an image of an internal defect.

FIG. 11 is a diagram illustrating a method of determining whether or not the positions of defects match;

FIGS. 12A and 12B are diagrams illustrating a method of determining whether or not the shapes of defects match;

FIG. 13 is a diagram illustrating a display example of a monitor.

FIG. 14 is a diagram schematically illustrating a process of removing an image of a front surface defect and a back surface defect from an image including all defects to obtain an image of an internal defect.

FIG. 15 is a flowchart illustrating a processing method for separating internal defects and surface defects.

FIGS. 16 (a), (b), and (c) are views showing reflection of coaxial incident light and scattered light.

17 (a), (b), (c) and (d) are process diagrams showing a method for manufacturing a glass substrate with a microlens array.

18 (e), (f) and (g) are continuation diagrams of FIG.

FIG. 19 is a plan view showing how a glass substrate with a microlens array is obtained from an MLA wafer.

FIGS. 20 (a), (b), (c), (d), and (e) are diagrams illustrating a state in which fixed point defects occur in an MLA wafer or a glass substrate with a microlens array.

FIG. 21 is a flowchart showing an MLA wafer inspection procedure.

FIG. 22 is a flowchart showing an MLA wafer inspection procedure as in FIG. 21;

FIG. 23 is a schematic diagram showing an MLA wafer inspection system.

FIG. 24 is a plan view illustrating a state in which an MLA wafer having no defect is inspected.

FIG. 25 is a plan view illustrating a state in which a MLA wafer having a defect is inspected.

FIG. 26 is a plan view illustrating a state in which an MLA wafer having a fixed point defect is inspected.

FIG. 27 is a schematic diagram illustrating a state in which an MLA wafer is notified from an inspection process to a manufacturing process.

[Explanation of symbols]

Reference Signs List 23 imaging device 30 coaxial incident light source 31 scattered light source 51a, 51b, ... glass substrate (chip) with micro lens array 54 stamper 59 MLA wafer 64 foreign matter 65 defect of pattern surface of stamper 66a, 66b defect 68 inspection device 75a, 75b, … Inspection area 76 defect 80 fixed point defect

Claims (7)

[Claims] 1. An inspection object is inspected by irradiating the same region of the inspection object with illumination light by different illumination methods and performing a plurality of observations, and comparing these observation results. Inspection methods. 2. The illumination system according to claim 1, wherein the illumination system includes at least coaxial incident illumination and scattered light illumination.
Inspection method described in 1. 3. The method according to claim 1, wherein images of the inspection object observed by different illumination methods are stored in a storage device, and only those defects of a specific type are separated by comparing these images. Inspection method. 4. The inspection method according to claim 1, wherein, when a defect is detected in the inspection object, inspection from a position where the defect is detected to a predetermined position is not performed. 5. When inspecting an inspection object having a plurality of product areas, if a defect is detected at substantially the same portion of a different inspection object, the defect information is recorded and the inspection object is inspected. 4. The inspection according to claim 1, wherein, in the product area where the defect recorded in the defect information exists, the defect position recorded in the defect information is first inspected. Method. 6. When inspecting an inspection object having a plurality of product areas, a defect is detected at almost the same location of different inspection objects, and the number of product areas having the defect detected at the almost same location is equal to or more than a predetermined number. The inspection method according to claim 1, wherein the notification is made when the number of times reaches the maximum. 7. An inspection system comprising: a plurality of illumination means of different illumination systems for irradiating inspection light to an inspection object; and an imaging device for obtaining an image of the inspection object illuminated by the illumination means. Inspection equipment.