KR20090104652A - Light source for illumination and pattern inspection apparatus using the same - Google Patents

Abstract

PURPOSE: A light source for illumination and a pattern inspection apparatus using the same are provided to determine whether is good or bad according to the difference of brightness using a light source as a dark field illuminating unit of the pattern inspection apparatus. CONSTITUTION: A light source for illumination comprises the followings. A surface light source irradiating light parallel to an irradiated area is arranged on the same plane in a plurality of ring shapes. The size of each surface light source is the size in which a light irradiating area from each surface light source irradiated on the irradiated area includes the whole irradiated area.

Description

Lighting source and pattern inspection device using the same {LIGHT SOURCE FOR ILLUMINATION AND PATTERN INSPECTION APPARATUS USING THE SAME}

In order to inspect the surface state of an object, this invention irradiates an illumination light to the light source for illumination and the pattern formed in the board | substrate which irradiate illumination light obliquely to this surface, acquires an illuminated pattern image, and performs inspection automatically. The pattern inspection apparatus to perform.

Background Art A pattern inspection apparatus is known that determines the quality of a pattern on the basis of an image obtained by irradiating illumination pattern onto a pattern formed on a light transmissive substrate.

In such a pattern inspection apparatus, illumination is made so as to obliquely enter the inspection region by the reflective illumination means from the side on which the pattern of the substrate is formed, and the image pickup means images the pattern of the substrate, and the luminance distribution pattern of the image to be photographed. From this, it is possible to detect the presence or absence of a pit (concave or missing) on the pattern. If there is a pit on the pattern, disconnection may occur, so it should be detected as a defective product.

Like the above lighting means, as the lighting means for irradiating the illumination light obliquely from all directions to the inspection object, the ring lighting means is well used. For example, Patent Document 1 discloses an inspection means using a ring illumination means.

According to the above publication, the conventional ring illumination is arranged concentrically with a large number of LEDs 103 in a thin cylindrical donut-shaped body container 102, as shown in Fig. 14A.

Moreover, each LED 103 is arrange | positioned with the angle in the center O direction of a circle, as shown to FIG. (B) which is the arrow figure of (a), and (c) which is the low arrow figure. The illuminating light can be irradiated obliquely to the workpiece | work which examines.

[Patent Document 1: Japanese Unexamined Patent Publication No. 2002-328094]

In the pattern inspection apparatus, the light of the same incidence angle is incident from all directions (360 ° direction) at any point of the region where the workpiece is inspected, and the intensity of light incident from each direction should be the same.

In addition, at any point in the inspection area, this condition (the light of the same incident angle from all directions is incident and the intensity of light incident from each direction should be the same) must be the same. The reason is explained below.

(1) In said pattern inspection apparatus, when a pit exists on a pattern, it will image as a bright (high brightness) part. If the brightness (luminance) is large, the size of the pit is large. If the brightness (luminance) is small, the pit is small.

If it is a small pit, it may not be necessary to make it defect, and in that case, quality is judged by the magnitude | size of the brightness (luminance) of a pit.

(2) At some point in the inspection area, if the intensity of the illumination light incident on the point differs in the direction, the brightness (luminance) changes depending on the direction in which the fall occurs, even if the size of the pit (dropout) is the same.

For example, as shown in FIG. 15, it is assumed that illumination light is irradiated with strong intensity from the right side and weak intensity from the left side. The pit on the right side of the pattern P is brightened because it reflects strong illumination light, and on the contrary, the pit on the left side of the pattern P darkens because it reflects light intensity weaker.

In other words, even if the size of the missing (feet) is the same, the brightness (luminance) is different and correct inspection (failure determination) cannot be performed. Thus, the illumination light should be illuminated at the same intensity from any direction (360 ° direction) at any point in the inspection area.

Moreover, a processus | protrusion may arise in the surface of a pattern. The projections do not need to be detected as defective because they are unlikely to cause disconnection. In order to detect and detect the pits and protrusions formed on the pattern surface, the illumination illumination light is illuminated, but it is difficult to detect the pits and the protrusions according to the angle. In order to detect the pits of the pattern surface separately from the projections, it is necessary to irradiate the illumination light in the optimum angle range. As described above, the pits and the projections cannot be distinguished by the direction in which the missing occurs. Thus, at some point in the inspection area, light of the same angle of incidence must be incident from all directions (360 ° direction).

And if the intensity and incidence angle of illumination light from each direction are disturbed in the whole inspection area | region, even if it is the same size pit, the magnitude | size of the brightness (luminance) will change or cannot be distinguished from projection, and it is correct | Acceptance judgment) cannot be made. Therefore, at any place (point) of the inspection area, light of the same incidence angle is incident from all directions (360 ° direction), and the intensity of light incident from each direction must also be the same.

In the said pattern inspection apparatus, the imaging means which is a CCD line sensor is scanned (scanned) in the direction orthogonal to the direction which a line sensor extends, and the whole inspection area is imaged.

FIG. 16 is a plan view of a thin region captured by a CCD line sensor (not shown) at one time. The size of the imaging area is, for example, 18 mm long and 2 μm wide.

Although schematically shown in the drawing, as described above, for example, the incident illumination light is also the same from all directions (360 ° direction) in the central portion A of the imaging area, and also in the left end portion B and the right end portion C. The angle of incidence and the intensity of light incident from each direction should be the same.

However, in the conventional ring illumination shown in FIG. 14, each LED 103 is disposed at an angle in the center O direction of the circle. Therefore, as shown in FIG. 17, the light from each LED is not flat light, and the illumination light is directed toward the center portion A of the imaging area.

Therefore, when the inspection region has a certain size as shown in Fig. 16, the central portion A is irradiated with light of uniform intensity and angle from all directions, but at other points, for example, both ends B and C, Depends on direction

In B and C of the imaging area in FIG. 17, for example, there is no illumination light (a, b) (indicated by dotted lines in the figure) incident from a direction orthogonal to the direction in which the CCD line sensor extends. For this reason, even if there is a pit in the direction of B and C in the direction of (a) or (b), the illumination light does not enter from the direction, so the pit cannot be detected.

That is, in the said pattern inspection apparatus, conventional ring illumination cannot be used as it is as a reflective illumination means.

This invention is made | formed in view of the said situation, The objective of this invention is the intensity | strength of the light which light of the same incidence angle injects from all directions (360 degree direction) in an arbitrary point of the area | region which image | photographs, and enters from each direction. In addition, in addition to obtaining the reflective illuminating means having the same conditions at any point in the imaging area, it is to provide a pattern inspecting apparatus capable of performing the correct inspection (confirmation of good or bad) of the pits using the reflective illuminating means. .

As a result of earnestly examining, the inventors found that light at the same incident angle is incident from all directions (360 ° direction) at any point in the region to be imaged, and the intensity of light incident from each direction is the same, and any of the inspection regions is the same. In terms of points, the conditions (the light of the same incident angle from all directions are incident and the intensity of light incident from each direction are the same) are the same as or larger than that of the size of the area to be imaged. Moreover, it was discovered that what is necessary is just to arrange the surface light source which emits parallel light as one unit, and to arrange this surface light source so that it may enclose an imaging area in plural rings on the same plane of the upper part of an imaging area.

The principle of the solution means will be described with reference to FIG.

FIG. 1 (a) is a plan view of the linear imaging area R viewed from above, and six linear light sources having the same length and width as the imaging area R (a, b, d, d, d) Bar) is prepared and the state arrange | positioned so that the imaging area | region R may be enclosed on the same plane above the imaging area | region R is shown. Moreover, FIG.1 (b) is a side view which looked at FIG.1 (a) from the side.

As shown in FIG. 1, illumination light is radiate | emitted in parallel state from a linear light source (a-bar), and it injects into each point BAC of the imaging area R at predetermined incidence angle. That is, the light emitted from the center part A 'of each light source enters the center part A of the imaging area R. As shown in FIG. In addition, light emitted from the left end B 'of each light source enters the left end B of the imaging area R. FIG. In addition, light emitted from the right end C 'of each light source enters the right end C of the imaging area R. As shown in FIG.

As shown in Fig. 1, A-A ', B-B', and C-C ', which are optical paths of illumination light, are parallel to each other, and their respective lengths (distance from the light source to the imaging area) are also the same. At each point of A, B, and C in R), light of the same incidence angle is incident from each direction (6 directions in FIG. 1), and the intensity of light incident from each direction is the same. In addition, at any point of the imaging area R, the light of the same incident angle from all directions enters, and the intensity of light incident from each direction is the same.

In FIG. 1, although the number of the light sources arrange | positioned around the imaging area | region R was made into six so that a figure may not become complicated, the illumination light of uniform intensity | strength and an angle injects from all directions so that the number is large.

2 is an example in the case where the imaging area is rectangular in shape.

2 (a, b) is a plan view of the rectangular imaging area R as seen from above, as shown in FIG. 1 (a), and eight rectangular shape surface light sources having the same size as the imaging area R. A) is shown and the state arrange | positioned so that the imaging area | region R may be enclosed on the same plane above the imaging area | region R is shown. 3 is a side view which looked at FIG.2 (a) from the side.

Illumination light exits in parallel state from A 'B' C 'D' of a surface light source (A-A), and it injects into each ABCD point of the imaging area R at predetermined incidence angle. For example, as shown in Fig. 2A, light from the lower left D 'of each surface light source (indicated by a dotted line in the figure) is incident on the lower left D in the drawing of the imaging area R. As shown in Figs. As shown in Fig. 2B, light from the upper right B 'of each surface light source (indicated by a dashed-dotted line in the drawing) is incident on the upper right B of the imaging area R. As shown in Figs.

Similarly, the illumination light from the lower right C 'of the surface light source is incident on the lower right C of the imaging area R, and the illumination light from the upper left A' of the surface light source is incident on the upper left A of the imaging area R, respectively.

FIG. 3 shows a state in which illumination light is incident from D 'of the surface light source (a) and the surface light source (d) to D of the imaging area R, and from C' to C of the imaging area R. FIG. .

Since A-A ', B-B', C-C ', and D-D', which are optical paths of illumination light, are parallel to each other and their lengths (distance from the light source to the imaging area) are also the same, At each point of A, B, C, and D, light of the same incidence angle enters from each direction (8 directions in FIG. 2), and the intensity of light incident from each direction is the same. Further, at any point in the imaging area R, light at the same incident angle enters from all directions, and the intensity of light incident from each direction is the same.

As the number of surface light sources arranged around the imaging area R increases, illumination light of uniform intensity and angle is incident from all directions. However, as will be described later, increasing the number of surface light sources increases the diameter (size) of the lighting means by that amount, thereby increasing the size of the apparatus.

Based on the above, this invention solves the said subject as follows.

(1) In the illuminating light source, the surface light source irradiating light parallel to the irradiated area is arranged in a plurality of annular shapes on the same plane, and the size of each surface light source is irradiated onto the illuminated area. The irradiation area of the light from this is made into the size containing the whole to-be-lighted area | region.

(2) In the above (1), the plurality of surface light sources are configured by arranging a plurality of LEDs on the same plane. Then, the LEDs in the surface light sources are arranged inclined toward the inside of the annular shape in which the surface light sources are arranged so that parallel light from each surface light source is illuminated to the illuminated area.

(3) In the above (1), the plurality of surface light sources are configured by arranging a plurality of prism sheets that emit light emitted from the plurality of LEDs as parallel light on the light output side of the plurality of LEDs in parallel, The prism sheet which comprises each surface light source refracts the light radiate | emitted from each LED so that the parallel light from each prism sheet may be illuminated to a to-be-lighted area inside the annular | arrangement in which each surface light source is arrange | positioned.

(4) Dark-field illumination means which irradiates the reflected illumination light obliquely to the workpiece | work in which the pattern was formed, Imaging means which image | photographs the said pattern illuminated by the said dark field illumination means, Work holding means which hold | maintains a workpiece, The said imaging In the pattern inspection apparatus provided with the control part which determines the quality of a pattern based on the pattern image image picked up by a means, The light source for illumination of said (1)-(3) is used as said dark field illumination means.

In the present invention, the following effects can be obtained.

(1) Light at the same incidence angle enters from any direction (360 ° direction) at any point in the region to be imaged, and the intensity of light incident from each direction is the same, and at any point in the inspection region, In other words, light of the same incidence angle is incident from all directions and the intensity of light incident from each direction can be illuminated.

For this reason, the brightness (luminance) in the area | region to image does not change with a place, and imaging can be imaged on the same conditions also in any point of an inspection area.

(2) By using the illumination light source of the present invention as the dark field illumination means of the pattern inspection apparatus, the pit and the projection are distinguished from the image picked up in all the regions to be inspected, and the difference is caused by the difference in the brightness (luminance) of the pit. Can be determined.

EMBODIMENT OF THE INVENTION Hereinafter, the specific structural example of the light source part of the illuminating means which is embodiment of this invention is demonstrated. Fig. 4 is a view showing the configuration of the surface light source constituting the lighting means of the first embodiment of the present invention, which is arranged in such a manner that the directions of the plurality of LEDs are parallel to each other, and are emitted in a state where the illumination light is in parallel, and predetermined in the imaging area. An embodiment of a surface light source incident at an incident angle of is shown.

4A is a plan view of the surface light source for illumination viewed from below (the imaging region side), FIG. 4B is a side view of the light source of FIG. 4A seen from the A direction, and FIG. 4C is It is a front view which looked at the light source of FIG. 4A from the B direction. In addition, these figures are schematic diagrams for easy description, and actual LEDs are listed by filling a several space | interval.

In the present embodiment, as shown in the figure, the surface light source 1 is emitted so that the main light rays of the illumination light from the respective LEDs 2 are in parallel, and are incident on the imaging area R at a predetermined incidence angle θ. Configure In addition, the diffusion plate 4 may be provided between the LED 2 and the imaging region R as shown by the dotted line in the figure.

As shown in Fig. 4A, a plurality of LEDs 2 are arranged on the LED support member 3 so that, among the light emitted from each LED 2, the components of the strongest light (primary rays) are parallel to each other. . In addition, since parallel light must enter the imaging area R from this surface light source 1, the size of the area | region which arranges LED2 is made larger than the size of the imaging area R. As shown in FIG.

The surface light source 1 comprised in this way is arrange | positioned in annular shape so that the imaging area may be enclosed in the plane on the imaging area in plurality and block. For this reason, it is convenient if the support member 3 is formed in fan shape.

As shown in FIG.4 (b), LED2 is arrange | positioned inclined toward the imaging area | region R so that the incident angle of illumination light into the imaging area | region R may become desired angle (theta).

Since the light emitted from the LED 2 has high directivity, the light from each LED 2 enters the imaging area R in a substantially parallel state.

The surface light source 1 comprised in this way is arrange | positioned in annular shape so that the imaging area | region R may be enclosed in several in the same plane on the imaging area | region R. FIG.

5 and 6 are diagrams schematically showing a state in which the eight surface light sources of FIG. 4 are evenly arranged at 45 °. 5A and 6 are plan views, and FIG. 5B is a side view. In addition, a diffusion plate 4 may be provided between the LED 2 and the imaging region R as shown in the dotted line of the same figure as in FIG. 4.

FIG. 5 shows a state in which illumination light is irradiated from each of the eight surface light sources 1-1 to 1-a to the linear imaging area R. As shown in FIG. 1 to 3, the size of the imaging area R and the surface light source 1 are described as the same, but in this drawing, the area of the surface light source 1 is larger than the area of the imaging area R.

In practice, it is difficult to match the size of the imaging area R with the size of the surface light source 1, and in order to inject light parallel to the entire imaging area R with uniform illuminance, the area of the surface light source 1 This is because it is advantageous to make the size slightly larger than the area of the imaging area.

In FIG. 5, the eight light sources emit light in parallel with each other, and are incident on the entire imaging area R at a predetermined angle θ. Therefore, at any point on the BAC of the imaging area R, illumination light of the same angle is incident at the same irradiation intensity from all directions (360 ° direction), and the conditions (all directions (360 °) at any point of the imaging area. Direction), the illumination light of the same angle is incident at the same irradiation intensity).

FIG. 6 shows a state in which illumination light is irradiated from each of the eight surface light sources A to A on the rectangular imaging region R. As shown in FIG. As in the case of FIG. 5, from eight surface light sources, illumination light exits in a parallel state and enters the whole imaging area R at predetermined angle (theta).

Therefore, at any point in the area surrounded by ABCD of the imaging area R, illumination light at the same angle is incident at the same irradiation intensity from all directions (360 ° direction), and at any point of the imaging area R It is the same as condition. That is, illumination light of the same angle is incident at the same irradiation intensity from all directions (360 ° directions).

Next, the lighting means of the second embodiment of the present invention will be described.

In this embodiment, a combination of an LED and a prism sheet is used.

Like the first embodiment, a plurality of LEDs are arranged in an annular shape on a flat support member and placed on the imaging area. However, the LEDs should be placed directly below each without giving an angle. Therefore, among the light emitted from each LED, the components (main chief ray) of the strongest light become mutually parallel.

Fig. 7A is a plan view of the light source arranged in this way as seen from below, and Fig. 7B is a cross-sectional view at the A-A side of Fig. 7. In addition, the figure is a schematic diagram for demonstrating easily, and actually, LED is lined up by filling a plurality of space | intervals.

As shown in FIG. 7B, in the present embodiment, the LED 2 is provided with respect to the support member 3 such that the chief ray of light emitted from the LED 2 is orthogonal to the plane including the imaging area.

The prism sheet is divided and provided on the light output side of this light source. As will be described later, the prism sheet to be divided is larger than the imaging area, and the light emitting portion is divided into equal angles.

A prism sheet is one in which a prism having a triangular cross section is arranged so as to be parallel to a plurality of long axis directions on one side of a transparent sheet, so-called mountains and valleys are continuously formed in a straight line shape. The prism sheet is provided between the backlight and the liquid crystal panel to make the brightness of the liquid crystal panel uniform, for example in a liquid crystal display screen.

As shown in FIG. 8, such a prism sheet is cut out to the magnitude | size of the surface light source to form, and a plurality is prepared. As shown in FIG. 8, the prism sheet is cut | disconnected in the direction which the long-axis direction of the prism formed from the prism sheet 5 is substantially orthogonal to the central axis r-r of the fan-shaped surface light source.

That is, when the prism sheet is installed in the light source, parallel light emitted from the prism sheet is cut out so as to enter the imaging area R at approximately the same incidence angle.

9, it is provided in the light output side of the light source shown in FIG. In Fig. 9, eight prism sheets 5 are provided, and the illumination means is in a state where eight surface light sources are equally arranged at 45 degrees, similarly to the first embodiment.

FIG. 10 is an enlarged view of a portion of a light source on which one prism sheet is mounted. Fig. 10A is a plan view of the illumination light source seen from below, Fig. 10B is a side view of the light source of Fig. 10A seen from the A direction, and Fig. 10C is Fig. 10A. It is the front view which looked at the light source of from the B direction.

As shown in Fig. 10 (b, c), the prism sheet 5 is provided through the support 6 with respect to the LED support member 3. Further, as shown in the dotted line in the figure, a diffusion plate 4 may be provided between the prism sheet 5 and the LED 2.

As shown in FIG. 10 (b), the illumination light in which the chief rays emitted from the respective LEDs 2 are parallel is incident on the slopes of the prism of the prism sheet 5 and refracted, while maintaining the parallel state. Branch in two directions. The component of one branched light illuminates the imaging area R at the incident angle [theta]. The component of the other branched light is not used. The angle of the prism of the prism sheet 5 is designed so that the incident angle θ becomes a desired value.

FIG. 11 is a modification of the prism sheet used in FIG. 10. In the case of FIG. 10, since light incident on the prism sheet 5 is divided into two directions, half of the light emitted from the LED 2 is not used. Therefore, the utilization efficiency of light is bad.

In order to solve this problem, the cross-sectional shape of the prism of the prism sheet 5 is made into a right triangle. As a result, the light incident on the prism is refracted only in one direction, and all the light emitted from the LED 2 can be used.

In FIG. 12, the experiment result which observed the pit which arose on the pattern using the illumination means of 2nd Example shown in FIG. 10 is shown. In addition, in this experimental example, as shown in FIG.12 (c), the number of illumination light sources divided | segmented using the prism sheet 5 is 12, ie, 12 surface light sources are equally arrange | positioned 30 degrees.

Fig. 12A shows the pit (observation object) generated in a pattern on the left side (corresponding to the position of B in the imaging region R) of the imaging unit (CCD line sensor), and the center of the visual field (the imaging region ( Change in the luminance of the pit received by the image pickup means when rotated 360 degrees from each position on the right side of the field of view (equivalent to the position of C in the imaging region R). Is a graph.

In the figure, the vertical axis is luminance (relative value) and the horizontal axis is rotation angle of pit (observation object).

At any point in the imaging area R, if light of the same incidence angle is incident from all directions (360 ° direction), and the intensity of light incident from each direction is the same, the brightness of the pit will not change even if rotated. .

When illuminated by the illumination means of the conventional example shown in FIG. 14, when the pit was rotated at the center A of the field of view, the change in luminance was approximately ± 8%. In contrast, in the present invention, as shown in Fig. 12 (a), even when the pit is rotated, the luminance change is small in any place on the left side of the visual field B, the center of the visual field A, and the right side of the visual field C. The change in luminance is approximately ± 3% at any position and is reduced to less than half as compared with the conventional example.

FIG. 12 (b) is a graph showing a change in luminance when the pit (observation) formed in a pattern is replaced with the left side of the field of view (B), the center of view of the field of view, and the right side of the field of view (C) of the imaging unit. to be. In the figure, the vertical axis represents luminance (relative value), and the horizontal axis represents position in the image pickup means. From the left side of the plotted point, it is the visual field left side (B), the visual field center (A), and the visual field right side (C). That is, it is the difference of the brightness | luminance when it sees the same pit from the visual field left side B, the visual field center A, and the visual field right side C.

If the entire inspection area is illuminated under the same conditions, even if the position of placing the pit (observation object) is changed (at any position in the field of view of the imaging means), the brightness will remain the same because the same pit is viewed.

))의 그래프는, 도 14에 나타낸 종래예의 조명 수단에 의해. 조명한 경우의 실험 결과이다.In addition, the dashed dashed line shown in the figure indicates the "

The graph of)) is made by the lighting means of the conventional example shown in FIG. Experimental results in the case of illumination.

As shown in Fig. 12B, in the conventional example, when the position of the pit is moved, the luminance greatly changes. In particular, the luminance increases in the center of view A, and the luminance decreases when the edge of the field of view (the imaging area) is obtained, such as the left side of the field of view B and the right side of the field of view. The change in brightness is approximately ± 8%.

In contrast, in the present invention, although the luminance increases in the visual field center A and tends to decrease in the visual field left B and the visual field right C, the change is approximately ± 4.5%, which is half that of the conventional example. It is reduced to an extent.

In addition, as the number of dividing the illumination light source into the prism sheet, that is, the number of the surface light sources, the more, the uniform illumination light can be irradiated to the imaging area from all directions.

However, as described above, since light parallel to the entire imaging area must be irradiated, the size of the surface light source must be equal to or larger than the size of the imaging area.

Therefore, when the number of surface light sources is increased, the diameter (size) of the illumination means becomes large by that amount, and the apparatus becomes large. Therefore, the number of dividing the lighting means (the number of surface light sources) has a limitation in terms of preventing the enlargement of the apparatus, and it is considered that the 12 divisions (12 surface light sources) shown in the above experimental example are appropriate.

The illumination light source of this invention can be applied to the inspection apparatus for inspecting the surface state of an object, and demonstrates the case where the illumination light source of this invention is applied to the pattern inspection apparatus below.

It is a figure which shows the Example at the time of applying the illumination means of this invention to the pattern inspection apparatus, and FIG. Is the figure which looked at the inspection apparatus of this embodiment from the side.

In FIG. 13, the dark field illumination means (reflective illumination means) 10 which irradiates reflected illumination light is provided in the ring shape around the imaging unit 11 as an illumination light source shown in the said 1st or 2nd Example, and is imaged. Illuminate the workpiece W from all 360 ° orientations of the unit.

The imaging unit 11 is comprised from the lens line 11b which has the CCD line sensor 11a which is an imaging element, and the optical element which forms the pattern on the workpiece | work W on this CCD line sensor 11a. It is.

The imaging unit 11 is provided with the imaging unit drive mechanism 12, and the imaging unit 11 scans in the direction of an arrow by driving the imaging unit drive mechanism 12 by the scanning means 13 ( Scan).

The workpiece | work W in which the patterns, such as wiring to be tested, was provided is mounted on the workpiece | work holding means (work stage) 14, and the imaging unit 11 scans on the workpiece | work W, and thus the image of the workpiece | work W is carried out. A pattern such as a wiring formed in the image is captured.

The scanning means 13, the imaging unit 11, the dark field illumination means 10, and the like are controlled by the controller 15.

In FIG. 13, when the work W is placed on the work holding means (work stage) 14, the dark field illuminating means (reflecting illuminating means) 10 lights up.

Next, the imaging unit 11 is scanned by the scanning means 13 in the width direction of the workpiece | work W from one side to the other (FIG. Right to left). The wiring pattern image on the workpiece W illuminated by the dark field illumination means 10 is received by the CCD line sensor 11a of the imaging unit 11 and stored in the control unit 15.

After the imaging of the wiring pattern is completed, the dark field illumination means 10 is turned off.

The control part 15 performs an image process on the image pattern picked up by the imaging unit 11, and detects the presence or absence of the defect on a pattern. If there is an error, an alarm or the like is output.

After the inspection of the pattern is finished, the workpiece W to be inspected next is placed on the workpiece holding means 14, and the above-described operation is repeated.

In addition, although the pattern inspection of the board | substrate was demonstrated above, even in the case of the pattern inspection of a film-form workpiece, although the transfer mechanism of a film-form workpiece differs in the point provided, it can implement | achieve with the same apparatus.

1 is a view for explaining the principle of the present invention (when the imaging area is linear).

2 is a view for explaining the principle of the present invention (when the imaging area is a rectangular shape).

3 is a side view of FIG. 2A.

4 is a diagram showing the configuration of a surface light source constituting the lighting means of the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a case where eight surface light sources of FIG. 4 are evenly arranged.

FIG. 6: is a figure explaining the case where illumination light is irradiated from eight surface light sources with respect to the rectangular imaging area | region R. FIG.

7 is a view for explaining the configuration of a light source constituting the lighting means which is the second embodiment of the present invention.

It is a figure explaining cutting out a prism sheet.

It is a figure explaining installation of the prism sheet to the light source shown in FIG.

10 is an enlarged view of the surface light source constituting the lighting means of the second embodiment.

It is a figure which shows the modification of the prism sheet used in FIG.

FIG. 12 is a view showing experimental results of observing pits using the lighting means of the second embodiment. FIG.

It is a figure which shows the Example at the time of applying the lighting means of this invention to the pattern inspection apparatus.

It is a figure explaining the conventional ring illumination means.

FIG. 15 is a view for explaining the case where the brightness (luminance) changes depending on the direction in which the deletion occurs, even if the size of the pits (dropout) is the same.

Fig. 16 is a plan view of a thin area captured by a CCD line sensor at one time.

It is a figure explaining that illumination light is directed toward the center part of an imaging area with respect to the conventional ring illumination means.

[Description of Symbols for Main Parts of Drawing]

1 surface light source 2 LED

3 support member 4 diffuser plate

5 prism sheets 6 holding

10 Dark field lighting means (reflective lighting means) 11 imaging unit

11a CCD line sensor 11b lens unit

12 imaging unit drive mechanism 13 scanning means

14 Work holding means (work stage) 15 control unit

R Imaging Area W Work

A ~ A surface light source

Claims (4)

The surface light source which irradiates the light parallel to a to-be-irradiated area is arrange | positioned in multiple annular shape on the same plane, The size of each surface light source is an illumination light source characterized in that the irradiation area of light from each surface light source irradiated on the surface of the area to be illuminated includes the entire area to be illuminated. The method according to claim 1, The plurality of surface light sources are configured by arranging a plurality of LEDs on the same plane. The LED in each surface light source is arranged inclined toward the inside of the annular shape in which each surface light source is arrange | positioned so that parallel light from each surface light source may be illuminated to a to-be-lighted area | region. The method according to claim 1, The plurality of surface light sources are configured by arranging a prism sheet for emitting light emitted from the plurality of LEDs as parallel light on the light output side of the plurality of LEDs in a plurality of annular shapes, The prism sheet constituting each surface light source refracts the light emitted from each LED to the inside of the annular shape in which the surface light source is arranged so that parallel light from each prism sheet is illuminated to the illuminated area. Illumination light source. Darkfield illumination means for irradiating the reflected illumination light at an angle to the workpiece on which the pattern is formed, imaging means for imaging the pattern illuminated by the darkfield illumination means, Work holding means for holding the work, In the pattern inspection apparatus provided with the control part which determines the quality of a pattern based on the pattern image image | photographed by the said imaging means, The dark field illumination means is a light source for illumination of Claim 1, 2 or 3, The pattern inspection apparatus characterized by the above-mentioned.

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