JPH10307011A - Method and apparatus for surface inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and an apparatus in which the existance and the shape of an uneven part can be measured with good accuracy and in which a wide range can be measured at one time by a method wherein reflected light in a region to be measured is image-formed by an object-side telecentric optical system, luminance data is acquired and processed and a bright part and a dark part are recognized. SOLUTION: A light irradiation means 110 is constituted of a light source 111, of an aperture 112, of a semitransparent mirror 113 and of a collimating lens 114. An object-side telecentric optical system 300 is provided with an image-formation lens system 320, with a light limitation means 310 such as an aperture diaphragm or an aperture and with an aperture-angle variable means 330. When illumination light is a nearly complete parallel luminous flux and when the aperture diameter of the light limitation means 310 is very small, an image which is formed by the object-side telecentric optical system 300 becomes a bright and dark two-gradation image according to an incidence angle in every point in a region to be measured. An imaging part 400 images the formed image, and luminance data on every point in every pixel, i.e., the region to be measured is acquired. A processing part 510 finds the existence of an uneven part and the shape of the uneven part in the region, to be measured, on the basis of the luminance data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface inspection method and a surface inspection apparatus for measuring the shape of an area to be measured.
In particular, the present invention relates to a surface inspection method and a surface inspection apparatus suitable for inspecting a surface property of a measurement target area.

[0002]

2. Description of the Related Art The measurement of the shape of the surface of an object is used for measuring the properties of the object and determining the quality of an article as a product. The measurement of the shape of the surface of an object is frequently used particularly for measuring the unevenness of the surface of a substantially planar object.

FIG. 14 is a configuration diagram of a typical example of a measuring device for measuring the uneven shape of the surface of a substantially planar object. As shown in FIG. 14, this device receives (a) a light source 910 that generates substantially parallel light, and (b) a light output from the light source 910 and outputs the light toward a measurement target area of the measurement target 990. Half mirror 920 to be measured, and (c) object 990 to be measured
(E) an imaging optical system 930 for inputting reflected light from the measurement target area to form an image, (d) an imaging device 940 having a light receiving surface 941 disposed on an imaging surface of the imaging optical system 930, and (e). A) a processor 950 that collects luminance data output from the imager 940 and performs image processing.

[0004] Using this apparatus, the shape of the measurement target area is measured as follows. The substantially parallel light output from the light source 910 is applied to the measurement target area of the measurement target 990 via the half mirror 920. The light reflected by the measurement target area is formed by the imaging optical system 930, and the formed image is captured by the imaging device 940. The imaging result is output from the imager 940 as luminance data, and collected by the processor 950. The processor 950 processes the collected luminance data to reconstruct an image of the measurement target area. By observing the image of the measurement target region reconstructed in this way, the presence or absence of the uneven portion and the position of the uneven portion in the measurement target region are measured from the blur of the image.

[0005]

Since the conventional shape measurement of an object is performed as described above, it is possible to roughly know the shape of the uneven portion, but when the shape of the uneven portion is a loose weight,
Since the blur gradually progresses from the peripheral portion toward the central portion, it is difficult to determine the outer edge of the uneven portion, and therefore, the shape of the uneven portion cannot be accurately determined.

Therefore, in order to measure the shape of the concave-convex portion with high accuracy, a large-scale, complicated, and expensive apparatus such as a scanning confocal microscope must be used.

The present invention has been made in view of the above, and has as its object to provide a surface inspection method capable of accurately measuring the presence or absence and shape of an uneven portion with a simple apparatus configuration and measuring a wide range at a time. Aim. Another object of the present invention is to provide a surface inspection apparatus having a simple configuration that suitably executes the surface inspection method of the present invention.

[0008]

According to a first aspect of the present invention, there is provided a surface inspection method for irradiating an area to be measured with illumination light composed of a parallel light beam and inspecting a surface state of the area to be measured. A first step of irradiating the measurement target area with the illumination light from an oblique direction of the measurement target area, and an optical axis that matches an incident direction of the illumination light on the measurement target area, A second step of forming an image of the reflected light in the measurement target area with the object-side telecentric optical system or the image-side telecentric optical system in which the object-side aperture angle with respect to one point is set to a predetermined angle; and A third step of capturing an image and collecting luminance data of each point in the measurement target area, and processing the luminance data to recognize a bright part and a dark part, thereby forming an uneven part in the measurement target area. Presence and unevenness Characterized in that it comprises a fourth step of obtaining of the shape. In this specification, the term “parallel light beam” includes not only a perfect parallel light beam but also a parallel light beam generated by a pseudo point light source.

According to a second aspect of the present invention, there is provided a surface inspection method for irradiating an area to be measured with illumination light composed of a parallel light beam and inspecting a surface state of the area to be measured. A first step of irradiating the measurement target area with the illumination light from an oblique direction of the measurement target area;
An object-side telecentric optical system or an image-object-side telecentric optical system having an optical axis that coincides with the direction of incidence of the illumination light on the measurement target region and having an object-side opening angle set at a predetermined angle with respect to one point of the measurement target region. A second step of forming an image of the reflected light in the measurement target area at a luminance corresponding to the angle of incidence at each point of the measurement target area, and capturing the formed image to form each of the measurement target areas. A third step of collecting the luminance data of the points, and processing the luminance data;
A regression curve obtained from integral data of the luminance data with respect to the tilt direction, while obtaining a tilt distribution of the measurement target area in a tilt direction of the measurement target object based on a first differential result of the distribution of the luminance data. And a fourth step of obtaining the presence or absence of an uneven portion in the measurement target area and the shape of the uneven portion based on a difference between the integrated data and the integrated data.

According to a third aspect of the present invention, there is provided a surface inspection apparatus for irradiating an area to be measured and inspecting a surface state of the area to be measured, and irradiating the area to be measured with illumination light composed of a parallel light beam. Light irradiating means, an angle setting means for inclining a measurement target so that the measurement target area can be irradiated with the illumination light from an oblique direction of the measurement target area, and an incident direction of the illumination light to the measurement target area. An object-side telecentric optical system or an image-object-side telecentric optical system that has an optical axis that matches with, and the object-side aperture angle with respect to one point of the measurement target area is set to a predetermined angle and images reflected light in the measurement target area. An imaging unit that captures the formed image and collects luminance data of each point in the measurement target area; and processes the luminance data to recognize a bright part and a dark part, thereby recognizing a bright part and a dark part. Characterized in that it comprises a processing unit for determining the shape of the presence and the concave-convex portion of the uneven portion of the inner.

According to a fourth aspect of the present invention, there is provided a surface inspection apparatus for irradiating an area to be measured and measuring a shape of an uneven portion of the area to be measured. Light irradiation means for irradiating, the angle setting means for inclining the measurement target so that the measurement target area can be irradiated with the illumination light from the oblique direction of the measurement target area,
An object-side opening angle with respect to one point of the measurement target area having an optical axis that matches the incident direction of the illumination light to the measurement target area is set to a predetermined angle, and the object-side opening angle is set according to the incident angle at each point of the measurement target area. An object-side telecentric optical system or an image-object telecentric optical system that forms an image with luminance, an imaging unit that captures the formed image and collects luminance data of each point in the measurement target area, and the luminance data Processing, based on the primary differential result of the distribution of the luminance data, obtains the inclination distribution of the measurement target area in the inclination direction of the measurement target object, and obtains the luminance data from integral data of the luminance data in the inclination direction. And a processing unit for obtaining the presence or absence of the uneven portion and the shape of the uneven portion in the measurement target region based on the difference between the obtained regression curve and the integral data.

According to a fifth aspect of the present invention, there is provided a surface inspection apparatus according to the third aspect.
Alternatively, the surface inspection apparatus according to claim 4, further comprising an opening angle changing unit that changes the object side opening angle.

According to a sixth aspect of the present invention, there is provided a surface inspection apparatus.
In the surface inspection device described above, the light irradiation unit is configured to include a light source and an aperture stop, and further includes an aperture diameter variable unit that changes an opening diameter of the aperture stop according to a change in the object-side opening angle. It is characterized by.

According to a seventh aspect of the present invention, there is provided a surface inspection apparatus according to the third aspect.
6. The surface inspection apparatus according to any one of to 6, wherein the processing unit is configured to tilt the measurement target object by a predetermined angle in one direction with respect to an axis in a reference plane orthogonal to the incident direction of the illumination light. First luminance data of each point of the measurement target area, and second luminance data of each point of the measurement target area when the measurement target is inclined by the same angle in the opposite direction with respect to the axis. And の of the maximum value obtained by the addition is set as an intermediate gradation, and at least one of the first and second luminance data is set as processing target luminance data. I do.

[0015] The surface inspection apparatus according to the eighth aspect is the third aspect.
8. The surface inspection apparatus according to any one of claims 7 to 7, wherein the processing unit includes: brightness data when the measurement target is tilted with respect to one axis in a reference plane orthogonal to the incident direction of the illumination light; Both the luminance data when the measurement object is inclined with respect to the other axis orthogonal to the one axis in the plane and the luminance data to be processed are processed, and the two luminance data to be processed are synthesized. The apparatus is characterized in that it is configured to determine the presence or absence of an uneven portion and the shape of the uneven portion of the measurement object.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a surface inspection method and a surface inspection apparatus according to the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

(First Embodiment) FIG. 1 is a configuration diagram of a first embodiment of a surface inspection apparatus according to the present invention. As shown in FIG. 1, the apparatus includes a light irradiating unit 110 that irradiates a measurement target area with illumination light in the form of a parallel light beam, and a measurement unit that irradiates the measurement target area with illumination light from an oblique direction of the measurement target area. An angle setting unit 200 that can incline the target area;
An object-side telecentric optical system 300 in which the direction of incidence of the illumination light on the measurement target area matches the optical axis, has a predetermined object-side opening angle with respect to one point of the measurement target area, and forms an image of reflected light in the measurement target area. And an imaging unit 40 that captures the formed image and collects luminance data for each pixel (each point in the measurement target area).
0, and a processing unit 510 that obtains the presence or absence of an uneven portion and the shape of the uneven portion in the measurement target area from the luminance data.

Here, the light irradiating means 110 includes the light source 11
1, an aperture 112, a half mirror 113, and a collimating lens 114. The collimating lens 114 also forms a part of the image forming system. The object side telecentric optical system 300 includes an imaging lens system 320 including a collimating lens 114,
Light limiting means 310 such as an aperture stop or an aperture provided at the stop position of the object side telecentric optical system 300
And an aperture angle changing unit 330 that changes the aperture diameter of the light limiting unit 310 to change the object-side opening angle of the object-side telecentric optical system 300.

In the surface inspection apparatus of the present embodiment, the illumination light is a substantially perfect parallel light beam, and the light restricting means 3
When the aperture diameter of the aperture 10 is very small, the image formed by the object-side telecentric optical system 300 is a two-tone image of light and dark corresponding to the incident angle at each point of the measurement target area. .

That is, as shown in FIG. 2, when a measurement object 900 having a flat measurement area is irradiated with illumination light from its normal direction (that is, at an incident angle = 0), the illumination light becomes According to the law of reflection, light is reflected in the normal direction (incident direction) of the measurement target area (that is, at a reflection angle = 0).
In this case, in the surface inspection apparatus of the present embodiment, the reflected light enters the opening of the light restricting means 310 of the object-side telecentric optical system 300 and reaches the imaging unit 400. As a result, the image formed by the object-side telecentric optical system 300 is an image having a luminance of 100%. On the other hand, as shown in FIG. 3, when the measurement target area is tilted with respect to a plane (reference plane) orthogonal to the direction of incidence of the illumination light, the illumination light becomes normal to the measurement target area (incident direction). Does not reflect to Therefore,
The reflected light does not enter the opening of the light restricting means 310 of the object side telecentric optical system 300 and does not reach the imaging unit 400. As a result, the image formed by the object side telecentric optical system 300 is an image having a luminance of 0%.

As described above, in the surface inspection apparatus of the present embodiment, only when a point in the measurement target area is irradiated with illumination light from its normal direction (that is, at an incident angle = 0), the point of the point is measured. The image is a bright image with a luminance of 100%, and the images at other points (for example, points on the slope of the concave portion) are dark images with a luminance of 0%.

In the present embodiment, the surface properties of the measurement target area of the measurement target 900 are inspected using such characteristics.

Now, the object-side aperture angle θ of the object-side telecentric optical system 300 is almost 0, and as shown in FIG. Exists and the inclination angle of the slope of the concave portion =
d = (L / 2) between θ ′ / 2, diameter = L, and depth = d
Consider a case where there is a relationship of tan (θ ′ / 2).

In this case, when the illumination light is irradiated from the normal direction of the object 900 to be measured, the illumination light does not reflect in the incident direction in the concave portion, and the reflected light is the light of the object side telecentric optical system 300. It does not enter the opening of the restricting means 310 and does not reach the imaging unit 400. As a result, the image of the concave portion formed by the object-side telecentric optical system 300 is an image having a luminance of 0%. This state is shown in FIG.

Next, the area to be measured is changed from the state of FIG.
Considering the case of tilting only, as shown in FIG. 5, the inclination of one slope of the recess with respect to a plane (reference plane) orthogonal to the incident direction of the illumination light is ((θ ′ / 2) −θ ″). ,
The slope of the other slope with respect to the reference plane is ((θ ′ / 2) +
θ ″). In this case, the slope is ((θ ′ / 2) −
θ ″) = 0, that is, (θ ′ / 2) = θ ″,
The reflected light of the slope having the slope of ((θ ′ / 2) −θ ″) is
Light limiting means 310 of object side telecentric optical system 300
And the reflected light from other portions is
Does not enter the opening of 0. Therefore, on the imaging surface of the imaging unit 400, an image in which a slope having a slope of ((θ ′ / 2) −θ ″) is a bright portion having a luminance of 100%, and the other portion is a dark portion having a luminance of 0%. This means that an uneven portion having an arbitrary inclination angle can be detected by changing the inclination angle θ ″. That is, when detecting various uneven portions, it is only necessary to detect the uneven portions by changing the inclination of the measurement target region in various ways.

As is clear from the above description, by adjusting the inclination angle θ ″ of the illumination light to the measurement target area by the angle setting unit 200, it is possible to measure the presence / absence and shape of a desired concave or convex portion. If the object-side opening angle of the light restricting means 310 is changed by the opening angle changing means 330, it is possible to change the detection sensitivity of the uneven portion.

(Second Embodiment) FIG. 6 is a block diagram of a surface inspection apparatus according to a second embodiment of the present invention. As shown in the figure, this apparatus is a light irradiating means 1 for irradiating a measurement target area with illumination light composed of a parallel light beam generated using a pseudo point light source.
20, angle setting means 200 that can incline the measurement target 900 so that the measurement target region can be irradiated with the illumination light from the oblique direction of the measurement target region, and the incident direction and light of the illumination light to the measurement target region. Object-side telecentric, whose axes match, have a predetermined object-side opening angle with respect to one point of the measurement target area, and form reflected light in the measurement target area at a luminance according to the incident angle at each point of the measurement target area. An optical system 300, an imaging unit 400 that captures the formed image and collects luminance data for each pixel (each point in the measurement target area), processes the luminance data, and generates one of the distributions of the luminance data. Based on the next differential result, the inclination distribution of the measurement target area in the inclination direction of the measurement object is obtained, and the difference between the regression curve obtained from the integral data of the luminance data in the inclination direction and the integral data is calculated. Zui by comprising a processing unit 520 for determining the shape of the presence and the concave-convex portion of the concavo-convex portion of the measurement target region.

Here, the light irradiating means 120 is connected to the light source 12.
1, an aperture stop 122, a half mirror 123, and a collimating lens 124. The collimator lens 124 also forms a part of the image forming system. Also, the object side telecentric optical system 300 has a first
As in the embodiment, the imaging lens system 320 including the collimating lens 124 and the object side telecentric optical system 3
Aperture stop (light limiting means) 3 provided at stop position 00
10 and an aperture angle changing unit 330 that changes the aperture diameter of the aperture stop 310 to change the object side aperture angle of the object side telecentric optical system 300.

In the surface inspection apparatus of the present embodiment, the object side telecentric optical system 300 uses the object side telecentric optical system 300 to make the incident light (average incidence) at each point in the measurement target area due to the irradiation of the illumination light. The surface property of the measurement target area of the measurement target 900 is inspected by utilizing the fact that an image is formed at a luminance corresponding to the angle.

Here, the reason why the luminance of each point of the formed image becomes the luminance corresponding to the incident angle at the corresponding point of the measurement target area is as follows.

Normally, when a parallel light beam is formed by the collimating lens 124, the light source 121 and the aperture or the aperture stop 1 are used.
22 is used to make a point light source. However, since the aperture and the aperture of the aperture stop 122 have a certain size, they are not completely a point light source. Therefore, the parallel light beam generated by the collimating lens 124 is not a perfect parallel light beam, and each point in the measurement target area is irradiated with light beams having various angle components corresponding to the aperture or the aperture diameter of the aperture stop 122. That is, the illumination light is applied to the measurement target area at a certain illumination aperture angle. As a result, even if the measurement target region is a flat portion, reflected light is generated at each point in a predetermined angle range in accordance with the law of reflection. In this case, the object-side aperture angle θ is set such that all reflected light on a plane parallel to a plane (reference plane) orthogonal to the incident direction (average incident direction) of the illumination light just enters the aperture of the aperture stop 310. Considering the case where the irradiation opening angle is equal to the object-side opening angle θ, the incident illumination light is reflected by the measurement target area as shown in FIG. 7A, and the reflected light is as shown in FIG. Then, the light is reflected so as to spread over the entire range of the object side opening angle θ. In this case, all the reflected light is taken into the opening of the aperture stop 310 and reaches the imaging unit 400, so that the image on the surface becomes a bright image with a luminance of 100%.

On the other hand, considering a surface inclined with respect to the reference plane, as shown in FIG. 8 or FIG. 9, the incident illumination light is reflected by the measurement target area, and all or a part of the reflected light is an aperture stop. Since the light is not captured by the aperture of the aperture stop 310, that part becomes a dark image with a luminance of 0% or the aperture stop 31
An image having a luminance corresponding to the amount of light passing through the opening 0 is obtained. Next, a conical concave portion exists in the measurement target region (substantially flat surface) of the measurement target 900, and the inclination angle of the slope of the concave portion =
d = (L / 2) between θ ′ / 2, diameter = L, and depth = d
Consider a case where there is a relationship of tan (θ ′ / 2).

In this case, the object-side aperture angle θ is set so that all the reflected light on the plane parallel to the reference plane just enters the aperture of the aperture stop 310, and the illumination light is directed from the normal direction of the measurement target area. Considering the case where light is irradiated, as shown in FIG. 10, when the inclination angle (θ ′ / 2) of the slope is larger than (θ / 2), all the light reflected on the slope is the aperture stop 310. , The luminance of the image of the concave portion is 0%, and the luminance of the image of the other portion (flat portion) of the measurement target region is 100%.

On the other hand, consider the case where the measurement target area is inclined from the state of FIG. 10 by an inclination angle θ ″ (= θ / 4).
As shown in FIG. 5, the inclination angle of one inclined surface (A surface) of the concave portion with respect to the reference plane is ((θ ′ / 2) − (θ / 4)), and the other inclined surface (B surface) with respect to the reference plane. The tilt angle is ((θ ′ / 2) + (θ / 4)). In this case, assuming that the inclination angle of the slope (θ ′ / 2) = (θ / 4), one of the slopes (A-side) is parallel to the reference plane, and all the reflected light in this portion is the aperture stop 310. Enter the opening. Therefore, the brightness of the image at that portion is 100%. Also, the other slope (Surface B) has an inclination of (θ / 2) with respect to the reference plane, and all the reflected light on the slope does not pass through the aperture of the aperture stop 310, so that the image of the slope (Surface B) Has a brightness of 0
%. Further, in this case, the inclination of the flat portion with respect to the reference plane is (θ / 4), and the reflected light at the flat portion passes through only about half of the aperture of the aperture stop 310, so that the brightness of the image of the flat portion is about It becomes 50%. Fig. 12
This is shown in (b).

On the other hand, when the object-side opening angle θ is set to be twice the spread angle range of the reflected light on the flat portion of the measurement target area (twice the illumination opening angle is the object-side opening angle θ). ), The measurement target area is shifted from the state of FIG.
When tilted by (= θ / 4), the flat portion becomes an image with 50% brightness, and the inclination angle (θ ′ / 2) of the slope is (θ / 4).
One of the slopes (C-plane) of the concave portion is an image with 100% luminance, and the other slope (D-plane) is an image with 0% luminance.

As described above, in the surface inspection apparatus according to the present embodiment, an image is formed with a luminance corresponding to the incident angle of the measurement target area. It is clear that the detection sensitivity of the concave portion can be freely adjusted by changing the opening angle or changing the object side opening angle θ. Therefore, in the present embodiment, the aperture stop 3
Ten opening angle variable means 330 are provided so that the object side opening angle θ can be freely changed. It should be noted that if the aperture diameter changing means 125 for changing the aperture diameter of the aperture stop 122 is also provided so that they are linked to each other, the sensitivity can be adjusted very easily.

In the surface inspection apparatus according to the present embodiment, the image pickup section 400 includes the object side telecentric optical system 30.
The processing unit 520 collects luminance data for each pixel (each point of the measurement target area). In collecting the luminance data, for example, 256 pixels are collected.
Collect luminance data in gray scale.

Here, the processing section 520 processes the collected luminance data for each pixel in the inclination direction of the measurement object to obtain the shape of the measurement object area. A method of processing the luminance data in this case will be described by taking as an example a case where the measurement target region 900 having the same shape as that of FIG. 10 is tilted.

FIG. 13 is an explanatory diagram of processing of luminance data. Luminance data of pixels arranged in the inclination direction (FIG. 13A)
), The difference between the luminance data of the adjacent pixels (I _{i + 1} −I _i )
, The first derivative of the distribution of the luminance data is obtained for one line (scanning line in the data processing) along the inclination direction (see FIG. 13B). This one
Since the data obtained by the second differentiation reflects the amount of inclination of the measurement target area, the inclination distribution along the scanning line is obtained from the first differentiation result.

In the scanning line direction, the luminance data from the pixel at the initial position of the luminance data (usually the end pixel) to each pixel is integrated (I ₁ +... + I _i ), and the integrated data at each position is calculated. (See FIG. 13C).

Then, based on the difference between the regression curve obtained from the integrated data and the integrated data, the unevenness of the measurement target area is obtained.

Each regression curve (including a linear regression line)
The result obtained based on the difference between the data and the integral data is displayed in a predetermined gradation (for example, 8-gradation display or 16-gradation display).
Thus, it is also possible to display only the concavo-convex portion of an arbitrary frequency on the display.

As is clear from the above description, any irregularities can be easily found from the luminance data. For example, in the case of a silicon wafer, a low-order component such as undulation or warpage can be extracted from the difference between the integral data and the first-order regression line. Further, mounds, dimples, and slip lines can be extracted from differences from higher-order regression curves such as third-order, fifth-order, and seventh-order.

In the case of the second embodiment, the luminance data when the measurement target region is inclined in one direction (X direction) and the luminance data when the measurement target region is inclined in a direction (Y direction) intersecting it. It is desirable to collect them.

In general, when the measurement target area is inclined with respect to the reference plane, as described above, the brightness of each point changes according to the inclination of each point from the reference plane. Using the change in luminance, the presence or absence and the shape of the uneven portion were determined.
In the surface inspection apparatus of the present embodiment, in this case, simply inclining the measurement target region with respect to one axis along the reference plane causes unevenness (unevenness or slip) in which peaks and valleys extend along the axis. In some cases, it cannot be accurately grasped.

Therefore, the measurement area is inclined (preferably inclined by the same angle) with respect to each of the axes (X, Y) along two directions intersecting each other in the reference plane, and luminance data is collected for each. In addition, the presence or absence and the shape of the concave and convex portions are obtained by using the two luminance data. In this manner, the presence or absence and the shape of the concave and convex portions in which the peaks and valleys extend along the axis can be accurately grasped.

Also, the first luminance data of each point of the measurement target area when the measurement target is inclined by a predetermined angle in one direction with respect to an axis in a reference plane orthogonal to the direction of incidence of the illumination light and , And the second luminance data of each point in the measurement target area when the measurement target is tilted by the same angle in the opposite direction with respect to the axis, and 1 / 輝 度 of the maximum value obtained by the addition. Preferably, 2 is an intermediate gradation, and at least one of the first and second luminance data is luminance data to be processed by the processing section 520.

This will be described with reference to FIGS. 12 (a) and 12 (b). The measurement target area is shifted from the state shown in FIG.
(= Θ / 4) to the right, FIG.
As shown in (a), the luminance is 50% in the flat part, 0% in the left inclined part, and 100% in the right inclined part. On the other hand, considering the case where the measurement target area is tilted leftward by the tilt angle θ ″ (= θ / 4) from the state of FIG.
%, 100% for the left slope, and 0% for the right slope. Then, the luminance data obtained therefrom are added together, and 1/2 of the obtained maximum value is set as an intermediate gradation.
And at least one of the luminance data obtained from the state shown in FIG. 12B and the state shown in FIG. In this way, referring to FIGS. 12A and 12B, a portion where the luminance is 50% (flat portion) has an intermediate gradation. This makes it possible to process the luminance data on the basis of the flat portion, so that the processing of the luminance data is facilitated. Further, when the intermediate gradation is determined, the processing target luminance is set such that the minimum to maximum luminance data among the luminance data set as the processing target luminance data fall within a predetermined gradation (for example, 256 gradations). It is preferable to process the data. In this case, the detection sensitivity of the uneven portion is further improved.

Further, as described above, the measurement target area is inclined (preferably inclined by the same angle) with respect to each of the axes (X, Y) along two directions intersecting each other in the reference plane. In order to collect luminance data for each of them and to determine the presence or absence and shape of the uneven portion using the two luminance data, two directions intersecting each other in a reference plane orthogonal to the incident direction of the illumination light are used. Axis along (X, Y),
Preferably, luminance data of the measurement target area when the measurement target area is inclined by the same angle in the opposite direction to each of two axes orthogonal to each other is collected, and the sum of the two pieces of luminance data for each axis is collected. Is preferably set to an intermediate gradation.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the invention. .

For example, in the second embodiment, a case where a point light source is formed by a light source and an aperture has been described as an example. However, the present invention is also applicable to a case where the light source itself is a point light source such as an LED without using an aperture. it can.

When the area to be measured has a warp with a constant curvature, the measurement may be performed with reference to the back surface of the object 900 by vacuum suction, or the aperture 112 or the aperture stop. 122 is moved toward or away from the half mirrors 113 and 123 to irradiate each point of the measurement target area with light from its normal direction, and the reflected light is used as the object side telecentric optical system 30.
An image may be formed at 0. In the former case, when a first-order regression line is obtained, irregularities based on the back surface are obtained. In the latter case, when a first-order regression line is obtained, unevenness based on a surface having a sled is obtained.

Further, in the second embodiment, similarly to the first embodiment, the inclination angle θ ″ of the measurement target area with respect to the reference plane is set to (θ / 4). The detection sensitivity of the convex portion can be changed.

In the above embodiment, the object side telecentric optical system 300 is used, but both the image side and the object side are telecentric optical systems (image object side telecentric optical system).
May be configured. The point is that at least the object side is a telecentric optical system.

[0055]

As described in detail above, according to the surface inspection method of the present invention, the measurement can be easily and accurately performed by combining the telecentric optical system and the illumination optical system. Further, according to the surface inspection apparatus of the present invention, the reflected light in the measurement target area of the illumination light output from the light source is imaged and imaged by the object-side telecentric optical system or the image-object-side telecentric optical system. The surface inspection method of the present invention can be suitably performed, and the shape of the measurement target region can be measured with high accuracy. Further, by further comprising an aperture angle variable means for changing the aperture diameter of the aperture stop,
Surface inspection can be performed with sensitivity according to the object side opening angle.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of an imaging operation of the surface inspection device of the first embodiment.

FIG. 3 is an explanatory diagram of an imaging operation of the surface inspection device of the first embodiment.

FIG. 4 is an explanatory diagram of an imaging operation of the surface inspection device of the first embodiment.

FIG. 5 is an explanatory diagram of an imaging operation of the surface inspection device of the first embodiment.

FIG. 6 is a configuration diagram of a surface inspection apparatus according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of an imaging operation of the surface inspection device of the second embodiment.

FIG. 8 is an explanatory diagram of an imaging operation of the surface inspection device of the second embodiment.

FIG. 9 is an explanatory diagram of an imaging operation of the surface inspection device of the second embodiment.

FIG. 10 is an explanatory diagram of an imaging operation of the surface inspection device of the second embodiment.

FIG. 11 is an explanatory diagram of an imaging operation of the surface inspection device of the second embodiment.

FIG. 12 is an explanatory diagram of an imaging operation of the surface inspection device of the second embodiment.

FIG. 13 is an explanatory diagram of luminance data processing of the surface inspection device of the second embodiment.

FIG. 14 is a configuration diagram of a conventional surface inspection apparatus.

[Explanation of symbols]

 110, 120 light source 200 angle setting unit 300 object side telecentric optical system 310 aperture stop 320 object side telecentric lens 400 imaging unit 510, 520 processing unit 610 position setting unit 620 measurement area moving unit

Claims (8)

[Claims] 1. A surface inspection method for irradiating a measurement target region with illumination light composed of a parallel light beam and inspecting a surface state of the measurement target region, wherein the measurement target region is obliquely oblique to the measurement target region. A first step of irradiating with illumination light;
An object-side telecentric optical system or an image-object-side telecentric optical system having an optical axis that coincides with the direction of incidence of the illumination light on the measurement target region and having an object-side opening angle set at a predetermined angle with respect to one point of the measurement target region. A second step of imaging reflected light in the measurement target area, a third step of capturing the formed image and collecting luminance data of each point of the measurement target area, Process the data,
A fourth step of recognizing a bright portion and a dark portion to obtain the presence / absence of an uneven portion and the shape of the uneven portion in the measurement target region. 2. A surface inspection method for irradiating a measurement target region with illumination light composed of a parallel light beam and inspecting a surface condition of the measurement target region, wherein the measurement target is inclined to obliquely measure the measurement target region. A first step of irradiating the measurement target area with the illumination light from; and an object-side opening angle with respect to one point of the measurement target area having an optical axis that coincides with an incident direction of the illumination light on the measurement target area. A second step of forming an image of the reflected light in the measurement target area by the object-side telecentric optical system or the image-object-side telecentric optical system set at a predetermined angle at a luminance corresponding to the incident angle at each point of the measurement target area; And a third step of capturing the formed image and collecting luminance data of each point of the measurement object, processing the luminance data, and based on a primary differential result of the distribution of the luminance data. Said Along with obtaining the slope distribution of the measurement target area, the presence / absence of a concavo-convex part and the shape of the concavo-convex part in the measurement target area are obtained based on a difference between a regression curve obtained from integral data of the luminance data and the integral data. And a fourth step. 3. A surface inspection apparatus for irradiating an area to be measured and inspecting a surface state of the area to be measured, comprising: a light irradiating unit for irradiating the area to be measured with illumination light composed of a parallel light beam; Angle setting means for inclining the measurement target so that the measurement target region can be irradiated with the illumination light from the oblique direction of the target region, and an optical axis that matches the incident direction of the illumination light to the measurement target region. An object side telecentric optical system or an image object side telecentric optical system that forms an object side aperture angle with respect to one point of the measurement target area at a predetermined angle and forms an image of reflected light in the measurement target area, and forms the formed image. An imaging unit that captures and collects luminance data of each point of the measurement target area, and processes the luminance data to recognize a bright part and a dark part, thereby determining whether or not there is a concave part and a concave part in the measurement target area. Part of A surface inspection apparatus comprising: a processing unit that obtains a shape. 4. A surface inspection apparatus that irradiates a measurement target area and measures the shape of the uneven portion of the measurement target area, wherein a light irradiation unit that irradiates the measurement target area with illumination light composed of a parallel light beam; Angle setting means for inclining the measurement target so that the measurement target region can be irradiated with the illumination light from the oblique direction of the measurement target region, and an optical axis that matches the incident direction of the illumination light to the measurement target region. An object-side telecentric optical system or an image-object-side telecentric optical system that has an object-side opening angle with respect to one point of the measurement target region and is formed at a predetermined angle and forms an image at a luminance corresponding to an incident angle at each point of the measurement target region. An imaging unit that captures the formed image and collects luminance data of each point in the measurement target area, processes the luminance data, and performs the measurement based on a first differential result of the distribution of the luminance data. The slope distribution of the measurement target area is obtained, and the presence / absence of the unevenness and the shape of the unevenness in the measurement target area are obtained based on the difference between the regression curve obtained from the integrated data of the luminance data and the integrated data. A surface inspection apparatus comprising: a processing unit. 5. The surface inspection apparatus according to claim 3, further comprising an opening angle changing unit that changes the object side opening angle. 6. The light irradiating means includes a light source and an aperture stop, and further includes an aperture diameter varying means for changing an aperture diameter of the aperture stop according to a change in the object-side opening angle.
The surface inspection apparatus according to claim 5, wherein: 7. The processing unit according to claim 1, wherein the measuring object is tilted by a predetermined angle in one direction with respect to an axis in a reference plane orthogonal to the incident direction of the illumination light. The first luminance data of a point and the second luminance data of each point in the measurement target area when the measurement target is tilted by the same angle in the opposite direction with respect to the axis are summed up, and this summation is performed. The half value of the maximum value obtained as a result is set as an intermediate gradation, and at least one of the first and second luminance data is set as processing target luminance data. The surface inspection device according to any one of the above. 8. The processing unit may include: luminance data when the measurement object is tilted with respect to one axis in a reference plane orthogonal to the incident direction of the illumination light; The luminance data when the measurement target is tilted with respect to another axis orthogonal to the axis is processed as the luminance data to be processed, and the two processing target luminance data are combined to obtain the unevenness of the measurement target. The surface inspection apparatus according to any one of claims 3 to 7, wherein the surface inspection apparatus is configured to obtain the presence or absence of a part and the shape of the uneven part.