JPH10293103A - Method and equipment for optical measurement and optical measuring equipment for patterned substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the properties of an object to be measured with high sensitivity and accuracy by irradiating the object with a light principally comprising an S polarized component at an incident angle within a specified range and detecting the scattering light by a light receiving means. SOLUTION: An objective glass substrate 12 is irradiated with a coherent light 13 principally comprising an S polarized component from a light source 11 through an optical system 18 at an incident angle θ of 45-90 deg.. A part of the irradiating light 13 reflected on the surface serves as an indirect illumination light 19. Scattering light 15 from a defect 14 on the glass substrate 12 is detected by a light receiving means 17 for both the irradiating light 13 and the indirect illumination light 19 in order to obtain the information concerning to the state of the defect 14 on the glass substrate 12. Reflectance is higher constantly under S polarized state than under P polarized state or circularly polarized state and when the incident angle θ exceeds about 45 deg., the reflectance is doubled and it is increased drastically when the incident angle exceeds about 70 deg.. Consequently, the indirect illumination light 19 can be utilized effectively regardless of the position of the defect 14 resulting in the enhancement of the measurement accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical measuring method and apparatus and an optical measuring apparatus for a substrate with a pattern. The present invention particularly relates to the properties (objects) of an object (measurement object) such as a substrate having translucency, or an object (measurement object) such as a substrate having a pattern made of a material different from the material of the substrate. The present invention relates to an apparatus and a method suitable for measurement (including detection and inspection) of surface defects, states of foreign matter, and the like.

[0002]

2. Description of the Related Art Various methods are known for optically measuring and / or inspecting the properties of a measurement object by irradiating the measurement object with light and detecting scattered light from the measurement object with a light receiving means. Have been.

Japanese Patent Application Laid-Open No. 63-205775 discloses a method for inspecting the surface of a substrate (measurement object) composed of a substrate and a pattern formed of members having different optical characteristics from the substrate. An optical measurement method is disclosed.

According to this method, coherent light is irradiated to the substrate surface from a direction substantially perpendicular to the substrate surface, and reflected light and scattered light from the substrate surface are transmitted through a half mirror.
Through a spatial filter provided to selectively attenuate or remove scattered light and interference light components caused by the pattern, scattered light from foreign matter attached to the substrate is received, and defects due to foreign matter on the substrate, etc. Is detected and / or the size thereof is detected.

This conventional method has the following problems. That is, when the surface materials of the substrates are different, the intensity of scattered light from a defect such as a foreign substance attached to those surfaces is different. Therefore, this conventional optical measurement method includes:
There is a problem that the defect detection sensitivity varies depending on the material of the substrate.

Further, for example, a pattern made of one or more members having optical characteristics such as a refractive index, a reflectance, and an absorptivity different from that of a substrate is formed on a translucent substrate such as glass or translucent plastic. Substrate, the detection sensitivity differs between the surface of the pattern portion and the surface of the base portion, or between the surface of the pattern portion made of different members, and a problem in the accuracy of defect detection occurs. .

The basic causes of these problems will be described with reference to the drawings. 1 and 2 are schematic front views for explaining a conventional optical measurement method. The conventional optical measurement method shown in FIG.
Is irradiated, and scattered light 4 from a defect such as a foreign substance 3 existing on the substrate 1 is received by a light receiving unit (camera) 6 through a lens 5.
Is detected. Here, when the substrate 1 has a high light-transmitting property, the camera 6 receives only direct scattered light from the foreign matter 3 toward the camera 6 due to the light directly applied to the foreign matter 3.

On the other hand, the conventional optical measurement method shown in FIG. 2 is for the case of a substrate 7 having a high reflectance.
Defects such as the foreign substance 3 existing on the substrate 7 are irradiated with irradiation light (direct irradiation light) 2 irradiated toward the substrate 7 and indirect irradiation light 8 reflected on the surface of the substrate 7. The scattered light 9 from a defect such as the foreign substance 3 is detected by the light receiving means (camera) 6 via the lens 5. That is, the scattered light received by the camera 6 is both scattered light from the foreign matter 3 due to the direct irradiation light 2 and scattered light from the foreign matter 2 due to the indirect irradiation light 9.

Therefore, in the conventional optical measuring method, if the surface material of the substrate itself is different, even if the defect has the same size and shape, the detection sensitivity differs for each substrate. In the case of a substrate in which a pattern is formed on a light-transmitting substrate, the detection sensitivity differs greatly between the surface of the pattern portion and the surface of the substrate portion even in the same substrate. In other words, as shown in FIG. 2, the scattered light by the direct irradiation light 2 and the indirect irradiation light 8 exists basically on the surface of the pattern portion, and basically, as shown in FIG. As described above, the scattered light by the direct irradiation light 2 exists. Therefore, such non-uniformity in detection sensitivity may cause a decrease in the accuracy of optical measurement because the range of defects such as foreign substances on the substrate that can be detected and the size of the defects to be measured vary depending on the location of the substrate. .

[0010]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a light receiving device which is caused by the material properties of the surface of a measuring object when the measuring object is a substrate having a light transmitting performance. It is an object of the present invention to provide an optical measurement method and apparatus capable of reducing the difference in intensity of scattered light and measuring (including inspection and detection) with high sensitivity and high accuracy the properties of a measurement object.

A second object of the present invention is that the object to be measured is
In the case of a substrate or the like having a pattern made of a material different from the material of the base, the intensity difference of the received scattered light between the pattern portion surface and the base portion surface is reduced, and the property of the measurement object is reduced. It is an object of the present invention to provide an optical measurement method and apparatus capable of performing highly sensitive and accurate measurement (including inspection and detection).

[0012]

According to the present invention, in order to attain the above object, an object to be measured has an incident angle of 45 degrees or more and 90 degrees or more.
Degrees of polarization and the state of polarization is guided to the measurement object with the S-polarized light component as the center, and the properties of the measurement object are detected by detecting scattered light from the measurement object by light receiving means. An optical measurement method for measuring and / or inspecting is provided.

According to a preferred aspect of the present invention, the object to be measured is characterized in that a pattern comprising one or more members having optical characteristics different from those of the substrate is formed on the substrate. An optical measurement method is provided.

According to a preferred aspect of the present invention, the light receiving means is a one-dimensional sensor or a two-dimensional sensor, and detects the scattered light from the measuring object by condensing the light on the light receiving means. An optical measurement method is provided.

According to a preferred aspect of the present invention, a scattered light component caused by the pattern is selectively attenuated or removed by a spatial filter in an optical path between the object to be measured and the light receiving means. An optical measurement method is provided.

According to a preferred aspect of the present invention, there is provided an optical measurement method, wherein an incident angle of the irradiation light is not less than 70 degrees and less than 90 degrees.

According to a preferred aspect of the present invention, there is provided an optical measuring method, wherein the object to be measured is a display panel substrate.

According to a preferred aspect of the present invention, there is provided an optical measurement method, wherein the property of the object to be measured and / or inspected is the presence or absence and / or size of a defect. Is done.

Further, according to a preferred aspect of the present invention, there is provided an optical measurement method, wherein the defect is a foreign substance attached to the object to be measured.

According to another aspect of the present invention, the light source of the irradiation light, the incident angle to the object to be measured is set to 45 degrees or more and less than 90 degrees, and the polarization state of the object to be measured is S-polarized light. There is provided an optical measuring device having an optical system for guiding the irradiation light so as to center on a component, and a light receiving means for detecting scattered light from the measurement object.

According to another aspect of the present invention, a light source of irradiation light, a table on which the object to be measured is mounted, and an incident angle with respect to the object to be measured mounted on the table of 45 degrees or more and 90 degrees or more.
An optical system that guides the irradiation light so that the polarization state is less than and the polarization state is centered on the S-polarized component with respect to the measurement target, and an optical system that includes a light receiving unit that detects scattered light from the measurement target. A measuring device is provided.

According to another aspect of the present invention, a light source for irradiating light and an object to be measured having a pattern formed of one or more members having optical characteristics different from those of the substrate are formed on the substrate. An optical system that guides the irradiation light so that the angle is 45 degrees or more and less than 90 degrees and the polarization state is centered on the S-polarized component with respect to the measurement target, and detects scattered light from the measurement target. An optical measuring device for a substrate with a pattern having a light receiving means is provided.

According to a preferred aspect of the present invention, the light receiving means is a one-dimensional sensor or a two-dimensional sensor,
An optical measuring device is provided, comprising a light collecting means for collecting scattered light from the measurement object on the light receiving means.

According to a preferred aspect of the present invention, there is provided an optical measuring apparatus, wherein the light-collecting means forms an image forming system.

According to a preferred aspect of the present invention, a spatial filter for selectively attenuating or removing the scattered light caused by the pattern is provided in an optical path between the object to be measured and the light receiving means. An optical measuring device for a substrate with a pattern is provided.

According to a preferred aspect of the present invention, the optical system has an incident angle of the irradiation light to the object to be measured of 7 degrees.
An optical measurement device is provided which is configured to be at least 0 degree and less than 90 degrees.

According to a preferred aspect of the present invention, there is provided a detecting means for detecting presence / absence and / or size of a defect of the measuring object based on scattered light detected by the light receiving means. , An optical measuring device is provided.

Further, according to a preferred aspect of the present invention, there is provided an optical measurement apparatus, wherein the defect is a foreign substance attached to the inspection object.

In these inventions, the incident angle is defined by the angle (θ) between the perpendicular of the surface of the object to be measured and the optical axis of the irradiation light.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic front view illustrating an example of the configuration of the method and apparatus for optically measuring an object according to the present invention.

In FIG. 3, the optical system 1 emitted from the light source 11
8, the incident light (θ) with respect to the measurement target (substrate) 12 is 45 degrees or more and less than 90 degrees, and the irradiation light 13 having the S-polarized component as the center (main component) is applied to the substrate 12.
(Foreign matter, etc.) existing on the substrate 12
The scattered light 15 from 4 passes through the lens 16 and is detected by the light receiving means (camera) 17. As a result, information on the state of a defect (for example, a foreign substance) on the surface of the substrate 12 as the property of the object is detected. The incident angle (θ) is
The angle formed by the perpendicular PL on the surface of the substrate 12 and the optical axis OA of the irradiation light 13.

Next, a description will be given of a case where the object to be measured (substrate) 12 has translucency, for example, a glass substrate 12 in this detection.

The glass substrate 12 is irradiated with irradiation light 13 from a light source 11 via an optical system 18. This irradiation light 1
3 is preferably coherent light. The incident angle (θ) of the irradiation light 13 with respect to the glass substrate 12 is selected in a range of 45 degrees or more and less than 90 degrees. The polarization state of the irradiation light 13 is adjusted by the optical system 18 with respect to the glass substrate 12 so that the irradiation light 13 has an S-polarized component as a main component. Although the performance is slightly deteriorated, the P-polarized component may be mixed if it is up to about 30%. Such irradiation light 13 is obtained, for example, by using a laser light source as the light source 11 and using a lens, a mirror, a polarizing element, a wave plate, or the like as the optical system 18.

When, for example, a foreign substance 14 adheres to the glass substrate 12, a part of the irradiation light 13 scatters on the foreign substance 14. A part of the scattered light 15 is
The light is condensed via a lens 16 provided above the light source 2, and is detected by a light receiving unit (for example, a camera having a light receiving sensor) 17.

Another part of the irradiation light 13 reflected on the surface of the glass substrate 12 becomes indirect irradiation light 19,
4 is irradiated. Part of the scattered light by the indirect irradiation light 19 (indirect scattered light) is also detected by the light receiving means 17.

Here, a part of the irradiation light 13 applied to the surface of the glass substrate 12 is reflected in accordance with the reflectance of the surface of the glass substrate 12. The reflectance with respect to the glass surface has a relationship as shown in FIG. 4 depending on the incident angle (θ) and the polarization state of the irradiation light 13.

FIG. 4 is a graph showing the relationship between the polarization state and the change in reflectance with respect to the incident angle (θ). In this graph, the horizontal axis indicates the incident angle (θ) (degree), the vertical axis indicates the reflectance (R), curve P indicates the P polarization state, curve C indicates the circular polarization state, and curve S indicates the polarization state. , S-polarized state are shown, respectively.

From the graph of FIG. 4, the S-polarized state (S) is larger than the P-polarized state (P) and the circularly polarized state (C).
Regardless of the incident angle (θ), the reflectivity is always high, and the reflectivity doubles when the incident angle (θ) is 45 ° or more as compared with the vicinity of 0 °, and further, when 70 ° or more. It can be seen that is dramatically increased.

That is, even if a part of the irradiation light 13 applied to the surface of the glass substrate 12 is a glass surface having a low refractive index, the polarization state of the irradiation light 13 is changed to the S-polarized state with respect to the glass substrate 12. And a glass substrate 12
By setting the incident angle (θ) to 45 degrees or more and less than 90 degrees, the amount of reflected light can be increased. By setting the incident angle (θ) to 70 degrees or more and less than 90 degrees,
The amount of reflected light can be dramatically increased.

By utilizing the condition in which the amount of reflected light increases in this manner, a mode similar to the mode of indirect irradiation described with reference to FIG. 2 can be formed. As a result, the light receiving intensity of the scattered light from the foreign substance 14 received by the light receiving unit 17 is improved, and it is possible to receive light having an intensity close to the received light intensity of the scattered light from the substrate having high reflectance. In order to further increase the received light intensity of the scattered light, the incident angle (θ) of the irradiation light 13 is selected in a range of 70 degrees or more and less than 90 degrees.

FIG. 5 shows a case where the measurement object (substrate) 22 is a patterned substrate 22 composed of a light-transmitting base 22a and a pattern 22b formed of a non-light-transmitting member formed on the surface thereof. Show the situation.

In this substrate 22, the foreign matter 14
When present on the surface of 2a, the scattered light 15 is basically detected by the light receiving means 17 in a state similar to that described with reference to FIG.

On the other hand, when the foreign matter 14 exists on the surface of the pattern 22b, the scattered light 15 is basically detected by the light receiving means 17 in the same state as described with reference to FIG.

Therefore, irrespective of the position where the foreign matter 14 exists, the scattered light by the indirect irradiation light 19 is effectively detected. That is, the scattered light by the indirect irradiation light 19 is detected together with the scattered light by the direct irradiation light 13.
As a result, the intensity of the scattered light 15 detected by the light receiving means 17 is increased, and the measurement (detection) sensitivity is improved. In addition, no matter where the foreign matter 14 exists,
9 is effectively used, the difference between the intensity of the scattered light 15 detected by the light receiving means 17 and the position of the foreign matter 14 is small, and the difference between the sensitivity on the pattern 22b and the sensitivity on the base 22a is reduced. It is significantly reduced. By reducing the sensitivity difference, the measurement accuracy is also improved.

[0046]

Next, an apparatus for carrying out an optical measurement method according to the present invention will be described using three embodiments with reference to the drawings.

[Embodiment 1] FIG. 6 is a schematic perspective view of an embodiment of an optical measuring device for the properties of an object according to the present invention.

In FIG. 6, the irradiation light source 31
This is an Ar laser having 0 mW, 1 / e ² diameter of 0.8 mm, and wavelength of 488 nm. The coherent light from the light source 31 is
Polygon mirror 32 and fθ lens (or
It is adjusted as irradiation light 35 by an optical system 34 including a cylindrical lens 33), and the properties are measured and / or
Alternatively, the light is focused on the surface of the object (measurement object) 36 to be inspected. The incident angle (θ) of the irradiation light 35 on the surface of the measurement target 36 is 80 degrees. By the optical system 34, the coherent light becomes the irradiation light 35 in a polarization state mainly composed of S-polarized light with respect to the measurement target 36. The polarization state is an elliptically polarized light in which the mixing ratio of the P-polarized light component to the linearly-polarized light component or the S-polarized light component is close to the linearly-polarized light within 10%, and the polarization angle is within ± 5 degrees around the S-polarized light. It is.

The polygon mirror 32 and the fθ lens 33
The beam of the irradiation light 35 is scanned in the Y direction. Optical system 3
The cylindrical lens 4 incorporates a cylindrical lens, whereby the shape of the beam spot of the coherent light incident obliquely is kept circular, so that a light condensing effect is obtained only in the X direction.

At this time, the spot diameter at the focal point on the surface of the measuring object 36 is 1 / e ² through the optical system 34.
The diameter was about 1.2 mm. The scanning of the beam spot is performed by scanning in the Y direction by the polygon mirror 32 and by scanning the table (stage) 37 on which the measurement target 36 is placed.
This is performed by a combination of the movement in the direction and the X direction orthogonal thereto.

That is, the beam spot is scanned by the polygon mirror 32 in a width of about 100 to 250 mm in the Y direction. On the other hand, each time the scanning is completed, the stage 37 is moved in the X direction by half the beam spot diameter. By moving by a scan step width of about (approximately 0.6 mm), the measurement target 36 is moved. This movement is repeated over the length of the measurement target area of the measurement target 36 in the X direction. Note that the scanning in the X direction may be performed continuously if the scanning line may be inclined.

Next, the stage 37 moves 90 to 90 in the Y direction.
The measuring object 36 is moved by about 220 mm (about 0.8 to 0.95 times the scanning width by the polygon mirror 32). By repeating these series of operations, the irradiation light 35 is irradiated even over the length of the detection target area of the measurement target 36 in the Y direction. It should be noted that the scanning step in the X direction by the stage 37 is performed when the beam spot diameter is 0.4 to 0.1 mm.
About 6 times is preferable. In this way, the scanning lines of the beam spot can be overlapped in the X direction, and the entire surface of the measurement object (substrate) 36 can be detected without any omission.

Defects (foreign matter) on the measuring object (substrate) 36
The scattered light is guided by a light receiving optical system 38 composed of, for example, an optical fiber and detected by a single element light receiving means 39 such as a photomultiplier. The light receiving optical system 38 may be constituted by a lens.

The signal from the light receiving means 39 is sent to the signal processing means 40. Signal processing means (defect detection means) 4
At 0, information on the detected scattered light is processed, and information on a defect (foreign matter) on the measurement target 36 is obtained.

Specifically, after the scattered light amount is converted into an electric signal, a signal exceeding a desired threshold value is detected as a defect (foreign matter).
The signal is recognized as The position of the defect (foreign matter) is specified by calculating the position irradiated by the laser at that time from the time when the signal exceeding the threshold value is received, the laser scanning speed and the moving speed of the stage 37. You.

The size of the defect (foreign matter) is estimated from the magnitude of the electric signal amount. Calibration of the size of the estimated defect (foreign matter) is performed based on a measured value of scattered light from standard particles on a substrate on which standard particles of a known size are dispersed. This calibration method is used in any of the following embodiments.

The spatial resolution of the apparatus of this embodiment is determined by the scanning step of the stage 37 in the X direction, and determined by the sampling frequency of measurement in the Y direction.

Embodiment 2 FIG. 7 is a schematic perspective view of another embodiment of the optical measuring device according to the present invention.

In FIG. 7, the light source 31 of the irradiation light is 10
This is an Ar laser having 0 mW, 1 / e ² diameter of 0.8 mm, and wavelength of 488 nm. The coherent light from the light source 31 is
An object (measurement object) 36 which is adjusted as irradiation light 35 by an optical system 41 including a lens, a wave plate, a polarizing element, a mirror, and the like, and whose properties are to be measured and / or inspected.
It is collected on the surface of. The incident angle (θ) of the irradiation light 35 on the surface of the measurement target 36 is 80 degrees. By the optical system 41, the coherent light becomes the irradiation light 35 in a polarization state having the S-polarized light as a main component with respect to the measurement target 36. This polarization state is elliptically polarized light in which the mixing ratio of the P-polarized light component to the linearly-polarized light or the S-polarized light component is close to linearly-polarized light within 10%.
In addition, the polarization angle is within ± 5 degrees around the S-polarized light.

The optical system 41 of this embodiment uses a cylindrical lens as in the first embodiment. However, in order to expand the coherent light beam in the Y direction and form a line beam parallel to this direction. Used.

The width of the line beam in the Y direction is about 90 to 350 mm in 1 / e ² width, and only the area of about 20 to 80 mm where the light amount is about 90% or more of the center is used for measurement. Is done. Note that this ratio is preferably selected to be about 70% or more.

On the other hand, the width of the line beam in the X direction should be as narrow as possible from the viewpoint of detection sensitivity.
It is preferably about 1 mm or less. Since the optical system 41 condenses the coherent light and irradiates the coherent light onto the measurement target 36, the focusing can be easily performed.

The scanning of the measurement area with the line beam of the irradiation light is performed by the movement of the measurement target 36 in the X direction and the Y direction by the stage 37. That is, the stage 37 continuously moves the measurement target 36 in the X direction. This movement is continued by the size of the measurement target area in the X direction.

Next, the stage 37 is moved from 18 to 18 in the Y direction.
The measuring object 36 is moved by about 70 mm (about 0.8 to 0.95 times the width of the area used for measuring the line beam). By repeating this operation, the measurement target 36
Irradiation light 35 is also applied over the length of the detection area in the Y direction.

The optical system 41 can be of a type that scans the laser light composed of the polygon mirror, fθ lens, and the like described in the first embodiment.

The second embodiment is most different from the first embodiment in that the light receiving means 42 in the second embodiment receives the scattered light which is focused and imaged. The scattered light from a defect (foreign matter) on the measurement target 36 passes through an imaging optical system 43 configured by a combination of lenses onto a light receiving unit 42 having a one-dimensional sensor or a two-dimensional sensor.
The light is condensed and formed as an image, and is detected by the light receiving unit 42.

The output signal from the light receiving means 42 is processed by a signal processing means (defect detecting means) 40 to obtain information on a defect (foreign matter) on the object 36 to be measured.

Specifically, after the scattered light amount is converted into an electric signal, a signal exceeding a desired threshold value is detected as a defect (foreign matter).
The signal is recognized as Further, the size of the foreign matter is estimated based on the magnitude of the electric signal amount.

The spatial resolution of the apparatus of this embodiment is determined by the magnification of the imaging optical system 43 and a one-dimensional or two-dimensional array sensor. Therefore, the spatial resolution does not depend on the scanning step, unlike the first embodiment.

The apparatus according to this embodiment includes an imaging optical system 43
And light receiving means 4 having one-dimensional sensor or two-dimensional sensor
The use of 2 makes it possible to detect defects (foreign matter) in a short distance with a simple structure, and to provide excellent position detection accuracy for defects (foreign matter).
It has the advantages of being able to accurately separate and detect each other, avoiding double counting of defects (foreign matter), and having high reliability in detecting the number of defects (foreign matter).

[Embodiment 3] FIG. 8 is a schematic perspective view of still another embodiment of the optical detection apparatus for detecting the properties of an object according to the present invention. FIG. 9 is a schematic front view for explaining the function of the spatial filter in the device shown in FIG.

In FIG. 8, the light source 31 of the irradiation light is a laser. The coherent light from the light source 31 is a lens,
The light is collimated by an optical system 44 including a wave plate, a polarizing element, a mirror, and the like.
Is irradiated. The incident angle (θ) of the irradiation light 35 on the surface of the measurement target 36 is 80 degrees. By the optical system 44, the coherent light becomes the irradiation light 35 in a polarization state mainly composed of S-polarized light with respect to the measurement target 36. The polarization state is an elliptically polarized light in which the mixing ratio of the P-polarized light component to the linearly-polarized light component or the S-polarized light component is close to the linearly-polarized light within 10%, and the polarization angle is within ± 5 degrees around the S-polarized light. It is.

In this embodiment, the optical system 44 is the same as that of the second embodiment.
Similarly, a cylindrical lens is used to extend a coherent light beam in the Y direction and form a line beam parallel to this direction.

The width of the line beam in the Y direction is about 90 to 350 mm in 1 / e ² width, and only the area of about 20 to 80 mm where the light amount is about 90% or more of the center is used for detection. Is done. Note that this ratio is preferably selected to be about 70% or more.

On the other hand, the width of the line beam in the X direction is preferably as narrow as possible from the viewpoint of detection sensitivity, but the maximum period of the periodic pattern (the When the measurement object 36 is a display panel substrate such as a liquid crystal substrate, the line beam width (X direction) is at least several times, preferably 10 times or more as large as that of the liquid crystal substrate.

In this embodiment, since the parallel light composed of coherent light is used as the irradiation light 35, narrowing down the width of the line beam in the X direction is not as easy as in the second embodiment. Scanning of the measurement area is performed in the same manner as in the second embodiment.

The optical system 44 can be configured to scan the laser beam composed of the polygon mirror, the fθ lens, and the like described in the first embodiment. The beam spot diameter should be at least about several times the maximum period of the target pattern (about 300 μm in the case where the measurement object 36 is a display panel substrate such as a liquid crystal substrate), preferably at least 10 times. Good.

In this embodiment, the measuring object 36 is a glass substrate 36 for a liquid crystal display device in which a periodic pattern 36b is formed on the surface of a base 36a.

The scattered light from the periodic pattern 36b and the defect (foreign matter) 14 on the measuring object 36 is guided to the surface of the spatial filter 46 via the Fourier transform lens 45.
After only the component of the scattered light by the pattern 36b is removed by the spatial filter 46, the light is condensed on the light receiving means 48 having a one-dimensional sensor or a two-dimensional sensor via the inverse Fourier transform lens 47. Light receiving means 48
Thus, only the scattered light from the defect (foreign matter) 14 is detected.

The output signal from the light receiving means 48 is processed by the signal processing means 40, the signal of the detected scattered light is processed, and information on the defect (foreign matter) 14 on the measuring object 36 is obtained.

Specifically, after the scattered light amount is converted into an electric signal, a signal exceeding a desired threshold value is detected as a defect (foreign matter).
14 is recognized. Further, the size of the defect (foreign matter) 14 is estimated from the magnitude of the electric signal amount.

As shown in FIG. 9, the spatial filter 46
This has the function of selectively attenuating or removing only the component of the scattered light from the pattern 36b by the light-shielding pattern 46b preset on the spatial filter 46.

The light-shielding pattern 46b corresponding to the pattern 36b on the measuring object 36 is formed, for example, by setting a non-exposed photographic dry plate in this optical system, exposing it, and developing it. .

By using the optical system using the spatial filter 46, the pattern 36b having a periodic shape
Scattered light components can be efficiently removed, and defects (foreign matter) 1
Only the scattered light component 4 is accurately detected by the light receiving means 48.

Note that according to this embodiment, the spatial filter 4
In the embodiment of the present invention, the image detected by the light receiving means 48 is processed by an image processing method without using the spatial filter 46 to scatter light from the periodic shape pattern. It is also possible to remove components, and such a device configuration may be adopted.

The apparatus according to this embodiment includes an imaging optical system 43
And light receiving means 4 having one-dimensional sensor or two-dimensional sensor
The use of No. 8 makes it possible to detect the defect (foreign matter) 14 at a short distance, to accurately detect and detect defects (foreign matter) at short distances, and to double-count the defect (foreign matter) with a simple configuration. And the reliability of detecting the number of defects (foreign matter) is high.

Further, since the S-polarized irradiation light 35 is obliquely incident, that is, the incident angle (θ) is 45 degrees or more and less than 90 degrees, the material of the pattern portion and the non-pattern portion on the patterned substrate 36 is The difference in reflectance due to the difference is small. Thereby, the difference in measurement sensitivity caused by the difference in the position where the defect (foreign matter) 14 exists can be extremely reduced.

This is combined with the effect of the selective removal of the scattered light component caused by the normal pattern due to the adoption of the spatial filter system, and the apparatus according to the third embodiment measures the defect (foreign matter) of the patterned substrate 36. And / or superior in testing or detection.

The glass substrate used for the LCD substrate and the chromium film formed on the glass substrate have an incident angle (θ) of 8
When irradiated with irradiation light composed of 0-degree circularly-polarized coherent light, the difference in detection sensitivity between defects (foreign matter) present on these substrates was about 5.6 times. The use of illuminating light reduces the sensitivity difference by a factor of 1.4.

From the viewpoint of improving the sensitivity, in the second and third embodiments, the light receiving means 42 and 48 have an integration direction in the X direction, and the integration clock timing is shifted by the stage 37 in the X direction. TDI synchronized with
It is preferable to use a (Time Delay Integration) type light receiving sensor.

In this sensor, in a specific direction (integration direction) of the two-dimensional array sensor, charges proportional to the light amount of the pixel are sequentially sent to downstream pixels, and data obtained by integrating all of the charges is obtained. With this,
By sending an electric charge at a speed corresponding to the moving speed of the image, the image moving in the integration direction can be detected while accumulating light from the moving object.

In the above three embodiments, the defect (foreign matter) detecting device has been described. However, in the present invention, for example, line width detection (measurement), protrusion detection (inspection), and the like are used as properties of the object to be measured. It applies to any device to detect, measure or inspect.

[0093]

According to the method and apparatus for optically detecting the properties of an object according to the present invention, the sensitivity for detecting scattered light from a defect (foreign matter) on an object to be measured (a substrate, a substrate with a pattern, a liquid crystal display panel substrate, etc.) can be improved. , Greatly improved over conventional methods and apparatus.

In particular, when a spatial filter is provided in the optical path between the object to be measured and the light receiving means, defects (foreign matter) on the surface of the substrate with the pattern and the liquid crystal display panel substrate have high sensitivity and high sensitivity. It is measured and / or inspected or detected with accuracy.

Therefore, the method and apparatus for optically detecting the properties of an object according to the present invention can be effectively used for detecting, inspecting, and measuring defects in the manufacture of substrates, patterned substrates, liquid crystal display panel substrates, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic front view illustrating a configuration of a conventional optical measurement method of a defect of a measurement object.

FIG. 2 is a schematic front view illustrating the configuration of another conventional optical measurement method for a defect of a measurement object.

FIG. 3 is a schematic front view illustrating an example of a configuration of an optical property measuring method of an object property according to the present invention.

FIG. 4 is a graph showing a relationship between a polarization state and a change in reflectance with respect to an incident angle.

FIG. 5 is a schematic front view illustrating another example of the configuration of the method for optically measuring the property of an object according to the present invention.

FIG. 6 is a schematic perspective view of an embodiment of an optical property measuring device for properties of an object according to the present invention.

FIG. 7 is a schematic perspective view of another embodiment of the optical measurement device for the property of an object according to the present invention.

FIG. 8 is a schematic perspective view of still another embodiment of the optical property measuring apparatus for the properties of an object according to the present invention.

FIG. 9 is a schematic front view illustrating the function of a spatial filter in the device shown in FIG.

Claims (17)

[Claims] 1. An irradiation light having an incident angle of 45 degrees or more and less than 90 degrees and a polarization state centered on an S-polarized component with respect to the measurement object is guided to the measurement object, and An optical measurement method for measuring and / or inspecting properties of the measurement object by detecting scattered light with a light receiving unit. 2. The optical measuring method according to claim 1, wherein the object to be measured has a pattern formed of one or more members having optical characteristics different from those of the substrate on the substrate. . 3. The light receiving device according to claim 1, wherein the light receiving means is a one-dimensional sensor or a two-dimensional sensor, and detects the scattered light from the object by condensing the light on the light receiving means. The optical measurement method according to 1. 4. A scattered light component caused by the pattern is selectively attenuated or removed by a spatial filter in an optical path between the measuring object and the light receiving means. 4. The optical measurement method according to 3. 5. The optical measuring method according to claim 1, wherein an incident angle of the irradiation light is not less than 70 degrees and less than 90 degrees. 6. The optical measuring method according to claim 1, wherein the object to be measured is a display panel substrate. 7. The optical measurement method according to claim 1, wherein the property of the measurement object to be measured and / or inspected is presence / absence and / or size of a defect. . 8. The optical measuring method according to claim 7, wherein the defect is a foreign substance attached to the object to be measured. 9. A light source for irradiating light and an incident angle of 45 degrees with respect to an object to be measured.
An optical system that guides the irradiation light so that the polarization state is centered on the S-polarized component with respect to the measurement target, and a light receiving unit that detects scattered light from the measurement target. An optical measuring device having: 10. A light source of irradiation light, a table on which the object to be measured is mounted, an incident angle with respect to the object to be measured mounted on the table being 45 degrees or more and less than 90 degrees, and a polarization state of the object to be measured. An optical measurement apparatus comprising: an optical system that guides the irradiation light so that an S-polarized component is centered on an object; and a light receiving unit that detects scattered light from the measurement object. 11. An incident angle of 45 ° or more and less than 90 ° on a light source of irradiation light and an object to be measured in which a pattern formed of one or more members having different optical characteristics from the substrate is formed on the substrate. An optical system that guides the irradiation light so that the polarization state is centered on the S-polarized component with respect to the measurement target, and a light receiving unit that detects scattered light from the measurement target for a patterned substrate. Optical measuring device. 12. The light receiving means is a one-dimensional sensor or a two-dimensional sensor, and further comprises a light collecting means for collecting scattered light from the object to be measured on the light receiving means. 12. The optical measuring device according to any one of 9 to 11. 13. An optical measuring apparatus according to claim 12, wherein said light converging means forms an image forming system. 14. A spatial filter for selectively attenuating or removing said scattered light caused by said pattern is provided in an optical path between said object to be measured and said light receiving means. 14. The optical measuring device for a substrate with a pattern according to any one of 11 to 13. 15. The optical system according to claim 9, wherein the optical system is configured such that an incident angle of the irradiation light with respect to the object to be measured is 70 degrees or more and less than 90 degrees. Optical measuring device. 16. The apparatus according to claim 9, further comprising detecting means for detecting presence / absence and / or size of a defect of said measuring object based on scattered light detected by said light receiving means.
16. The optical measuring device according to any one of items 15 to 15. 17. The optical measuring apparatus according to claim 16, wherein said defect is a foreign substance attached to said inspection object.