JPH08247957A - Defect detection method and apparatus for inspecting appearance of liquid crystal substrate or ic wafer - Google Patents

Abstract

PURPOSE: To provide a defect detection method and apparatus for inspecting the appearance of a liquid crystal substrate or an IC wafer which enable displaying of all defects on the same screen while accompanying no further complication of the structure of the apparatus nor increase in inspection time. CONSTITUTION: A diffraction light source 11 is arranged to irradiate the surface of a sample S with illumination light in the direction orthogonal to the straight line of the surface of the sample S from a slant position using multi-kinds of light sources and optical systems corresponding to a plurality of defects and scattered light sources 15 and 16 to irradiate the surface of the sample S with the illumination light in the direction diagonal to the straight line of the surface of the sample S from a slant position. The quantity of light of an interference light source 21 for irradiating the surface of the sample S with the illustration light in the direction vertical thereto is distributed properly to irradiate the surface of the sample S simultaneously through corresponding optical systems. Thus, defects intrinsic to various light sources from the surface of the sample S is detected by one CCD camera 26 and then, a defect image can be displayed on the same screen of a monitor 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal substrate or IC wafer formed by regularly engraving a wiring of about 0.3 to 20 .mu.m on a glass or silicon substrate in a grid pattern, scratches, dust, shot shift of a stepper, and film. The present invention relates to a defect detection method and a defect detection device for visual inspection of a liquid crystal substrate or an IC wafer for inspecting thickness unevenness and the like.

[0002]

2. Description of the Related Art In the conventional visual inspection of liquid crystal substrates, IC wafers, etc., inspection light is irradiated from various angles according to the type of the defect, and the reflected light including the defect image reflected on the substrate is visually or CCD. It was generally observed by an image pickup device such as. There are various types of defects, and it is necessary to make the inspection light different depending on the types of defects.

For example, when there is a shot shift or a focus shift on the substrate surface, the detection of these defects is performed by the spectral fringes produced by the diffracted light emitted from the pattern edge in the normal state and the diffraction fringes emitted from the pattern edge in the abnormal state. By comparing with the spectral fringes created by the light, it is possible to detect the disturbance of the spectral fringes due to the pattern deformation of the substrate that is the subject, so that it should be orthogonal to the lattice pattern on the substrate surface from an oblique position with respect to the substrate surface. The method of irradiating the inspection light is effective. Spectral fringes of diffracted light are generally a spectral action of light by a diffraction grating, and are a phenomenon in which white light is split into blue light and red light. The shot shift is a shift of the pattern generated due to a movement error of the stepper with respect to the underlying pattern on the substrate surface.

Generally, as shown in FIG.
Since the size of the shot is limited in the panel 1 of about 0 inch, one shot is created by moving four shots 2 each having a size of 1/4 of the panel 1.
However, as shown in FIG. 6B, if there is a deviation even in one of the four shots 2 ', the color of 1/4 of the panel 1 appears to change.

Defocusing means that when the pattern on the surface of the substrate is not in focus during exposure, blurred spectral fringes are formed on the surface of the substrate. In addition, when there are scratches, dust, protrusions, etc. on the substrate surface, in order to detect these defects, the scattered light emitted from the defective portion of the substrate surface is used to observe the defects. A method of irradiating the inspection light from a position so as to obliquely intersect the grid pattern on the substrate surface is effective.

In addition, since defects such as uneven film thickness and scattering of the resist can be detected by utilizing the disturbance of the equal film thickness interference fringes, an interference illumination optical system for interference illumination of the substrate surface is used. The method used is effective. Therefore, conventionally, defect detection in visual inspection of liquid crystal substrates, IC wafers and the like has been performed without omission by using an apparatus having the above-described optical system.

[0007]

However, when performing a visual inspection of a liquid crystal substrate, an IC wafer, or the like, the inspection time is generally limited, so that it is necessary to detect defects by all the optical systems without omission. There was a problem that the time limit for the inspection time was exceeded. The reason for this is that in the past, one optical system was used to extract one defect and determine the presence / absence of a defect for each substrate.

For this reason, if a plurality of different defect detections are attempted in order to detect leak-free defects,
Since it is necessary to extract defects and judge the presence / absence of defects for each optical system, the detection of defects without leaks leads to an increase in inspection time. In addition, even though it is possible to perform inspections individually using each optical system and detect defects without leakage, all detected defects are displayed on the same screen because the detected defect images are displayed separately for each optical system. There is also a problem in that it cannot be displayed above, and it is not possible to grasp the distribution status of defects as a whole at a glance.

As a method for solving the above problems, a method of synthesizing the images detected by the respective optical systems is conceivable. However, this method requires an image processing device and the like, which makes the entire device complicated. There's a problem. An object of the present invention is to be able to display all defects on the same screen, and to provide a defect detection method and defect detection for appearance inspection of a liquid crystal substrate or an IC wafer without complicating the device structure and increasing the inspection time. A device is provided.

[0010]

According to a first aspect of the present invention, there is provided a liquid crystal substrate for illuminating a surface of a subject having a plurality of straight lines continuous in at least one direction with illumination light to detect a defect of the subject. In a defect detection method for appearance inspection of an IC wafer, a plurality of types of light sources corresponding to a plurality of defects and an optical system are used to move from a position oblique to the surface of the object to a direction orthogonal to a straight line on the surface of the object. Diffraction light source for illuminating light, scattering light source for illuminating light in a direction oblique to the straight line of the subject surface from a position oblique to the subject surface, and illuminating light for vertical direction to the subject surface The light amount of the interference light source that irradiates the light is appropriately distributed, and the illumination light is simultaneously applied to the surface of the subject through the corresponding optical system, and the defects specific to various light sources from the surface of the subject are detected by one detection means. Then, the defect image by various light sources To be displayed on the same screen of the image display device.

The invention of claim 2 corresponds to a plurality of defects for detecting defects in the subject by irradiating the surface of the subject in which a plurality of straight lines continuous in at least one direction are formed with illumination light. In a defect detection apparatus for visual inspection of a liquid crystal substrate or an IC wafer including a plurality of types of light sources and an optical system, illumination light is emitted from a position oblique to the surface of the object and in a direction orthogonal to a straight line on the surface of the object. Diffraction light source, scattering light source that emits illumination light in a direction oblique to a straight line of the subject surface from a position oblique to the subject surface, and interference light source that emits illumination light in a direction perpendicular to the subject surface. And one detecting means for picking up an image of a defect on the surface of the subject by the plural kinds of light sources, and an image display device for displaying an image from the detecting means.

A third aspect of the present invention is characterized by comprising light amount control means for adjusting the respective light amounts of the plurality of types of light sources according to the type of the subject.

[0013]

According to the first aspect of the present invention, a plurality of types of light sources corresponding to a plurality of defects and an optical system are used, and the surface of the object is inspected through an optical system corresponding to each of the light sources in which the light amount is appropriately distributed. Simultaneously irradiating the same with the above, the defects specific to various light sources from the surface of the subject are detected by one detecting means, and then the defect images by the various light sources are displayed on the same screen of the image display device.

According to the second aspect of the invention, the surface of the subject is irradiated with illumination light from a plurality of types of light sources, and the defect imaged by one detecting means is displayed on the image display device. According to the invention of claim 3, the light amount control means adjusts the light amount of each light source according to the type of the subject.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a block diagram of a defect detecting apparatus for carrying out the present invention, and FIG. 2 shows a plan view of an illumination portion of FIG.

The stage 10 on which the sample S is placed is composed of an XY stage which can move in a direction orthogonal to each other. As the sample S, a liquid crystal substrate or an IC wafer in which a large number of grid-like wirings are regularly marked on a glass or silicon substrate is used. The light source A is a diffractive light source 11 that is effective for detecting a shot shift, a focus shift, or the like on the surface of the sample S. The diffraction light source 11 is a convex lens 1 for illumination.
It is arranged so that the afocal illumination light 14 can be emitted from a position obliquely above to the illumination field 13 on the surface of the sample S via 2 via a line 2 in a direction orthogonal to the wiring on the surface of the sample S.

The light source B is the scattered light sources 15 and 16 effective for detecting scratches, dust, protrusions, etc. on the surface of the sample S. The pair of scattered light sources 15 and 16 includes convex lenses 17 and 1 for illumination.
Afocal illumination light 19 and 20 can be applied to the same illumination field 13 as the diffractive light source 11 from a diagonally upper position, in this case, an angle near 45 degrees, in a direction diagonally intersecting the wiring on the surface of the sample S via 8. Are arranged as follows.

The above-mentioned convex lenses 12, 17, and 18 make the illumination light 14, 19, and 20 emitted from each light source into an afocal state, and have a diameter corresponding to the irradiation range on the surface of the sample S, that is, the inspection range. A material having a sufficiently large diameter is used. The light source C is an interference light source 21 that is effective for detecting unevenness in film thickness of the resist of the sample S, scattering, and the like. The interference light source 21 is arranged so as to be able to irradiate the same illumination field 13 on the surface of the sample S with the afocal illumination light 22 from an upper position via an interference optical system described later.

The interference optical system will be described in detail. First, the illumination light 22 'of the interference light source 21 is guided to the half mirror 24 through the slit 23 of the opening having a diameter of about 1 cm, and then the half mirror 24. The image forming lens 25 is arranged so that the illumination light 22 ′ reflected by can be irradiated to the illumination field 13 on the surface of the sample S in an afocal state. In addition,
The imaging lens 25 includes a diffraction light source 11 and scattering light sources 15 and 16
It is arranged at a position where the illumination lights 14, 19, and 20 from are not blocked.

Further, the reflected light having various defect images reflected by the illumination field 13 on the surface of the sample S is again formed by the imaging lens 2.
After passing through 5, the reflected light is imaged on the detection means arranged for imaging. An image sensor is mainly used as the detecting means. In this embodiment, the CCD camera 2 is used as the image sensor.
6 was used. The CCD camera 26 is arranged at the pupil position near the focal position of the imaging lens 25.

Further, in order to display the defect image picked up by the CCD camera 26, a monitor 27 is connected to the CCD camera 26 as an image display device. Further, the control system for controlling these configurations, together with the sample data input unit 28 for inputting data such as the type and division of the sample to be measured, and the sample data input by the sample data input unit 28,
A data storage unit 29 that stores the light intensity of each of the light sources 11, 15, 16, and 21, a light intensity control unit 30 that outputs a digital value according to each light intensity data, and a light intensity control unit 30 are connected,
It is composed of a D / A converter 31 for converting the digital value output from the light quantity control unit 30 into an analog signal.

FIG. 3 shows an example of the light quantity data format of each light source input to the data storage unit 29. For example, 1A- ○○○○ shown in FIG. 3 is the diffracted light. This is an example used as a sample name when setting the diffracted light to 34 of 256 gradations and the interference light to the level of 11 when a large amount of light is generated and the interference light may be small. As described above, each light amount data is labeled by the name of the sample to be used, and the contents in the data are expressed by the light amount of each light source in the order of diffraction, scattering, and interference in 256 gradations of 8 bits.

The reason for this is that, for example, in the case of defect detection of a sample in which a metal thin film is coated on the entire surface, since the sample surface is like a mirror, illumination from an interference light source reflected by the sample surface is performed. This is because the light becomes very strong, and the illumination light from the diffracted light source and scattered light source from other light sources is buried in the reflected light and cannot detect defects. Therefore, in such a sample, Since it is necessary to reduce the setting of the light amount of the interference light source, the combination of the light amount of each light source needs to be set for each sample.

Therefore, when the inspection is performed by the light source controlled by the preset light quantity data for each sample situation, the detected defects include all the defects that can be detected by the respective inspection lights, and the defect is not detected. Can be prevented. The operation of the above-described first embodiment will be described below. When the defect of the sample S is detected, first, the sample S is placed on the stage 10 and the name of the sample S shown in FIG. 3 is input from the sample data input unit 28 to the data storage unit 29. Light amount data corresponding to the name is sent from the data storage unit 29 to the light amount control unit 30, and the light amount control unit 30 outputs a digital value according to the value. The output digital value is converted into an analog signal by the D / A converter 31 and controls the light amount of each of the light sources 11, 15, 16 and 21.

The illumination light 14 from the diffractive light source 11 is made afocal by the convex lens 12 and is irradiated onto the surface of the sample S. Most of the illuminated illumination light 14 is reflected on the sample S at a reflection angle corresponding to the incident angle, but if there is a shot shift or a focus shift on the sample S, diffraction at the edge portion of the grid pattern The light diffracted by the phenomenon has a different wavelength from the normal part. This diffracted light is used as the sample S
4 is converged by the imaging lens 25 disposed above, and the diffracted light (a) at the edge portion of the lattice pattern of the sample S as shown in FIG. By doing so, a defect image can be obtained.

Illumination lights 19 and 20 from the pair of scattering light sources 15 and 16 are illuminated by the convex lenses 17 and 18 in the same size into the illumination field 13 that is substantially the same as the diffraction light source 11. When the specimen S has scratches, dust, protrusions, or the like, the irradiated illumination lights 17 and 18 generate scattered light and pass through the imaging lens 25 as in the case of the diffracted light described above, and the CC
Scattered light due to scratches (b) and dust (c) on the sample S as shown in FIG. 4B is converged on the image forming surface of the D camera 26.

Illumination light 22 'from the interference light source 21
Is the slit 23 placed at the focal position of the imaging lens 25.
The illumination light 22 ′ is reflected by the half mirror 24 toward the imaging lens 25 side through the opening of the above, and becomes the afocal illumination light 22 by the imaging lens 25, and the sample S is irradiated perpendicularly. When the sample S has uneven film thickness or the like, the irradiated illumination light 22 causes an interference pattern, and through the imaging lens 25, as in the case of diffracted light, an imaging surface on the CCD camera 26. The interference light (d) on the surface of the sample S as shown in FIG.

Each of the light sources 11, 15, 16, 21 whose light amount is controlled as described above illuminates the surface of the sample S at the same time and is reflected on the sample S.
The defect image corresponding to 21 is simultaneously focused on the CCD camera 26. For each defect image of the sample S, all the defect images on the surface of the sample S as shown in FIG. 4D are displayed on the monitor 27 from the CCD camera 26.

In the image formed on the image forming surface of the CCD camera 26, the light amount of each light source is appropriately adjusted, and therefore, the image of the sample S by each light source 11, 15, 16, 21 is obtained. Defect images due to diffracted light, scattered light, and interference light are all detected and displayed. Therefore, according to this embodiment, in the defect detection of the liquid crystal substrate or the IC wafer, the defect detection by a large number of light sources can be performed within the same time as the inspection by the single light source which has been conventionally performed. It is possible to detect and display the peculiar defects obtained by the light source at the same time.

Further, for example, by providing a shutter in the illumination optical path of each light source,
It is also possible to detect only the required defect image. further,
The present invention is not limited to the one described in the embodiment, and as shown in FIG. 5, the interference light source 21 ′ and the illumination light emitted from the interference light source 21 ′ are converted into a parallel light flux in an afocal state. Convex lens 32, sample S, and imaging lens 2
5 may be provided with a half mirror 24 'at a position for reflecting the illumination light 22 "from the interference light source incident from the convex lens 32 toward the sample S side in parallel to the optical axis.

With this structure, the illumination light of the interference light source is not reflected on the surface of the imaging lens, so that the contrast of the defect image is improved.

[0032]

As described above, according to the present invention, in the defect detection of a liquid crystal substrate or an IC wafer, it is possible to inspect with various light sources within the same time as an inspection with a single light source,
It is possible to simultaneously detect and display the specific defects obtained by each light source.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a defect detection device according to a first embodiment.

FIG. 2 shows a plan view of the illumination portion of FIG.

FIG. 3 shows an example of a light quantity data format of each light source.

FIG. 4A shows a defect image that can be detected by a diffraction light source. (B) shows a defect image that can be detected by a scattered light source. (C) shows a defect image that can be detected by an interference light source. (D) shows a defect image which can be displayed by this embodiment.

FIG. 5 is a diagram showing a configuration of another embodiment.

FIG. 6 (a) shows an image printed on a panel. (B) It shows the print of the panel.

[Explanation of symbols]

 1 panel 2, 2'shot 10 stage 11 diffractive light source 12, 17, 18 convex lens 13 Teruno 14, 14, 19, 20, 22, 22 ', 22 "illumination light 15,16 scattered light source 21,21' interference light source 23 slit 24 , 24 'Half mirror 25 Imaging lens 26 CCD camera 27 Monitor 28 Sample data input section 29 Data storage section 30 Light quantity control section 31 D / A converter 32 Convex lens

Claims (3)

[Claims] 1. A defect detection method for visual inspection of a liquid crystal substrate or an IC wafer, which comprises illuminating a surface of a subject having a plurality of straight lines continuous in at least one direction to detect defects in the subject. , A plurality of types of light sources corresponding to a plurality of defects and an optical system are used, and a diffractive light source that illuminates illumination light in a direction orthogonal to a straight line on the surface of the subject from a position oblique to the surface of the subject, and the subject Appropriate distribution of the light amount of the scattering light source that illuminates the illumination light in a direction that intersects the straight line of the subject surface from the position oblique to the surface and the interference light source that illuminates the illumination light in the direction perpendicular to the subject surface. Then, illuminating the subject surface simultaneously with illumination light through the corresponding optical system, detect defects specific to various light sources from the subject surface with one detection means, and then display the defect image by various light sources. Display on the same screen of the device LCD substrate or IC, characterized in that the wear way
Defect detection method for wafer visual inspection. 2. A plurality of types of light sources corresponding to a plurality of defects for illuminating the surface of the subject on which a plurality of straight lines continuous in at least one direction are formed to detect a defect of the subject. In a defect detection apparatus for visual inspection of a liquid crystal substrate or an IC wafer including an optical system, a diffractive light source that irradiates illumination light in a direction orthogonal to a straight line of the subject surface from a position oblique to the subject surface, A scattered light source that emits illumination light in a direction oblique to a straight line of the subject surface from a position oblique to the subject surface, an interference light source that emits illumination light in a direction perpendicular to the subject surface, and Defect for visual inspection of a liquid crystal substrate or an IC wafer, which comprises one detecting means for picking up an image of a defect on the surface of a subject by the light source of 1. and an image display device for displaying an image from the detecting means. Detection device. 3. The liquid crystal substrate or I according to claim 1, further comprising a light amount control means for adjusting the light amount of each of the plurality of types of light sources according to the type of the subject.
C Wafer defect detection device for visual inspection.