JP2001050907A - Method for inspecting substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate a substrate defect from a substrate deposit by inspecting the defect by a substrate defect-inspecting device, before washing for recording the result, and inspecting the defect again after the washing, and then comparing substrate defect inspection information before and after a cleaning process. SOLUTION: A substrate defect-inspecting device 4 comprises a light source 5 and a light reception part 6 arranged with a gap to a substrate 1, a data- processing part, a substrate table traveling in the X and Y directions of a horizontal position where the substrate 1 is placed, and the like. In this configuration, a light beam is applied from the light source 5 before cleaning. Then, when a defect 2 exists at a position before inspection, the inspection information is stored at the information storage part of a substrate defect-inspecting machine 4, the substrate table is moved in X and Y directions, and the entire surface of the substrate is inspected and stored at the information storage part. Then, after the substrate 1 is cleaned, the inspection information on the entire surface of the substrate 1 is stored by the similar means again. Then, inspection information before and after cleaning the substrate 1 is incorporated into the substrate defect-inspecting machine 4 or it is compared by an external computer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a substrate before and after a substrate cleaning step, and more particularly, to a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a glass substrate for a photomask, a glass substrate for a magnetic disk, and the like. The present invention relates to a method of inspecting a substrate before and after a substrate cleaning process such as a glass substrate used for a semiconductor device, an aluminum substrate for a magnetic disk, a substrate for a semiconductor represented by silicon, and a substrate for a compound semiconductor.

[0002]

2. Description of the Related Art Conventionally, various methods have been adopted as a method for inspecting defects of a substrate. Among them, an automatic defect inspection method using an inspection apparatus typically uses an optical detection mechanism. For example, a substrate is irradiated with laser light, and light reflected on the surface of the substrate or light transmitted through the substrate is detected by a light receiving sensor, and recorded and displayed as defect information by information processing means.

However, in the automatic defect inspection method using these inspection devices, defects, defects, irregularities on the substrate surface,
Pinholes, substrate surface or internal impurities, heterogeneous parts,
The inspection apparatus could not determine the discrimination between the substrate defect such as color unevenness and the attached matter on the substrate.

For this reason, visual inspection is used to supplement the automatic defect inspection method using such an inspection apparatus. However, visual inspection is a sensory inspection, and individual differences are likely to occur.
There are many inconveniences such as the judgment being varied depending on experience, skill level and the like. In addition, the reliability is low due to the low repeatability and the limit of the ability to detect minute defects, and the limit of the guaranteed accuracy is caused.

On the other hand, when only the automatic defect inspection method by the inspection apparatus is used, in addition to the inability to discriminate between the substrate defect and the adhered substance on the substrate, the adhered substance which was not originally a defect is also determined to be a defect. So-called overkill occurs. In other words, deposits that are not originally defects can be commercialized by re-cleaning, simple rework, rework, etc., but if this is judged to be a defect, disposal or severe rework is performed, resulting in loss of material and burden on the process. Invite increase.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has an automatic defect inspection.
Using a conventional inspection device that could not distinguish between defects on the substrate such as defects, defects, irregularities on the surface of the substrate, pinholes, impurities on the surface or inside the substrate, inhomogeneous parts, uneven color, etc. and those adhering to the substrate. Another object of the present invention is to provide a method that enables inspection of a substrate.

[0007]

SUMMARY OF THE INVENTION According to the present invention, before a step of cleaning a substrate which is continuously conveyed, the substrate is inspected for defects by a substrate defect inspection machine, the defect inspection information is recorded, and the substrate is cleaned. After the process, the substrate is inspected again by the substrate defect inspection machine, and the substrate defect inspection information performed before the cleaning process is compared with the substrate defect inspection information performed after the cleaning process, so that the defect is detected. A method for inspecting a substrate, characterized in that it is determined whether the defect is a defect or a substance attached to the substrate. According to this method, it is possible to discriminate between the defect of the substrate and the adhering substance even when using a conventional inspection apparatus in which the discrimination between the substrate defect and the adhering substance on the substrate cannot be performed. In particular, in this method, inspection can be performed at the same time as the continuous substrate is transported, and the inspection time can be reduced.

Further, the present invention provides a method for inspecting a defect of a substrate by a substrate defect inspector before a substrate cleaning step, recording the defect inspection information, and recording the defect by the substrate defect inspector after the substrate cleaning step. The defect inspection is performed again, and the substrate defect inspection information performed before the cleaning process is compared with the substrate defect inspection information performed after the cleaning process, so that the defect is a defect of the substrate or a substance adhering to the substrate. And a method for inspecting a substrate, characterized in that the method comprises: According to this method, it is also possible to discriminate between the defect of the substrate and the adhering substance using a conventional inspection apparatus which could not discriminate between the substrate defect and the adhering substance on the substrate.

In the present invention, it is preferable that the substrate is a sheet glass. Plate glass is a transparent body, and it is particularly difficult to distinguish between a substrate defect and a substance attached to the substrate, and the effect of the present invention is remarkable.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is a conceptual diagram illustrating the principle of defect inspection by a substrate defect inspection machine used in the present invention. The board defect inspection machine 4 places the light source 5 and the light receiving section 6 arranged at a predetermined distance from the board 1, other data processing sections (not shown), and the board 1, and moves in the horizontal X and Y directions. It is composed of a substrate table and the like.

A light beam is emitted from the light source 5 to the inspected position of the substrate 1, and if the inspected position has no defect,
The irradiation light is specularly reflected or transmitted by the surface of the substrate 1,
It does not reach the light receiving section 6. On the other hand, if there is a defect 2 at the position to be inspected, the irradiation light is irregularly reflected at the position of the defect 2 and a part of the light reaches the light receiving unit 6. Thus, the presence or absence of a defect is determined based on the intensity level of the scattered light. However, as described above, the principle of this defect inspection is that defects, defects, irregularities on the substrate surface, pinholes, impurities on the substrate surface or inside,
It is not possible to judge the discrimination between a substrate defect such as an inhomogeneous portion and color unevenness and a substance attached to the substrate.

The inspection information of the inspected position by the above-described inspection is stored in an information storage section (memory) of the substrate defect inspection machine 4, and the substrate table is moved in the horizontal X and Y directions to move the entire surface of the substrate 1 inspect. In this manner, the inspection information of the entire surface of the substrate 1 is recorded in the information storage unit of the substrate defect inspection machine 4. Note that an inspection method in which irradiation light from a light source is scanned without moving the substrate table in the horizontal X and Y directions may be used. Such a board defect inspection machine is sold by each maker, and is used for inspection of various boards. In the present invention, for example, a board defect inspection machine (product name, G1-4600) manufactured by Hitachi Electronics Engineering Co., Ltd.
Can be used.

The mechanism for detecting a substrate defect is not limited to the above-described optical detection mechanism, but may employ a mechanism utilizing ultrasonic waves or X-rays, or a combination thereof.
Further, the position of the light source, the position of the ultrasonic wave transmitting source, the position of the light receiving unit, the position of the receiving unit, etc. need not be located above the inspected position of the substrate. You can also choose a light source, ultrasonic transmission source, light receiving unit,
A plurality of receiving units may be provided.

First, the substrate 1 is inspected by the above-described substrate defect inspection machine 4.
Inspection of defects. Next, the substrate 1 is washed by a washing machine. After the cleaning, the defect inspection of the substrate 1 is performed again in the same procedure. Also by this inspection, the inspection information of the entire surface of the substrate 1 is recorded in the information storage unit of the substrate defect inspection machine 4. afterwards,
The inspection information before cleaning of the substrate 1 and the inspection information after cleaning recorded in the information storage unit of the substrate defect inspection machine 4 are compared using a computer built in the substrate defect inspection device 4 or an external computer.

Specifically, the inspection information before cleaning and the inspection information after cleaning at the same position (the same coordinates) on the substrate 1 are compared, and an AND operation is performed using a computer. As a result, the substrate 1 is also determined as a defect before cleaning, and only the position determined as a defect after cleaning is determined as a defect on the substrate.

FIG. 2 illustrates the above flow. In FIG. 2, the position information of the defect before cleaning is shown on the upper substrate. That is, there are two defects (○) and two deposits (▽). However, at this point, a defect (○)
And attached matter (▽) is not identified. In FIG. 2, the position information of the defect after cleaning is shown on the middle substrate. That is, there are two defects (○) and two deposits (×). At this point, no discrimination was made between the defect (と) and the adhering matter (×).

In FIG. 2, the result of the AND operation of the defect position information before cleaning and the defect position information after cleaning is shown on the lower substrate. The defect (○) shown on this substrate is the true defect of the substrate 1. That is, if a substance is recognized as a defect before cleaning and is removed by cleaning (▽), and a substance newly adhered by cleaning and recognized as a defect (X) is a dirt, it should not be recognized as a defect. Such an operation is performed. Only those that are recognized as defects without change before and after cleaning are regarded as true defects.

Next, processing of position information of a detected defect will be described. The substrate defect inspection apparatus used in the present invention is required for each substrate in consideration of the beam diameter of the irradiation light and the element size of the light receiving unit, based on the position information obtained by moving the substrate or scanning the irradiation light. It is often output (output) as a matrix with accuracy.

The single position range at this time is called a pixel. If necessary, the range of one pixel is, for example, 0.5
Designation in an arbitrary range such as an mm square or a 3 mm square can be easily performed by current computer technology.
If this is used, defects detected in a single pixel are fine defects such as pinholes and dust, and defects detected in a plurality of pixels at arbitrary consecutive points are defects or deposits (for example, drying unevenness). As a drawback of the stain)
It can be used to roughly sort defects.

However, since the range of pixels required in the above-described rough selection differs from the accuracy of the substrate stop position (or the accuracy of the light beam irradiation position) at which reproducibility can be guaranteed in the substrate defect inspection apparatus, an erroneous determination is made. May be. That is, if a defect is detected in the center pixel among the nine pixels shown in the upper substrate of FIG. 3 before the substrate cleaning,
If a defect can be detected at exactly the same place as shown in the lower substrate of FIG.

On the other hand, the mechanical accuracy of the device, the optical accuracy of the detecting mechanism, the dimensional accuracy of the detecting body of the light receiving section or the device,
If the same location cannot be detected before and after the substrate cleaning due to vibrations from the environment or the like, that is, if the pixel selected after the substrate cleaning deviates from the pixel selected before the substrate cleaning, it is not determined that the same location is defective.

For example, the sensitivity of the detection mechanism is 10 μm
When detecting a defect with a size of 2 mm using a device capable of detecting an object with a size of 2 mm, the detection sensitivity is sufficient. For example, one pixel is set to a 1 mm square, and the defect is detected with two consecutive pixels. Can be programmed to determine if a defect is found. However, when the mechanical accuracy of the apparatus is not high and the reproducibility of the substrate stop position is only about 1 mm, the probability of determining the defect at the same place before and after the substrate cleaning is extremely low when using the same algorithm as above. The following problems occur.

In order to solve the above problem, an arbitrary number of pixels, for example, 9 pixels shown in FIG. 4 (in addition, 4 pixels, 25 pixels, etc. are possible) are set, and the defects detected therein are set at the same position. Take the method to judge.
That is, as shown in FIG. 4, the substrate at the same position is not detected as a defect of the pixel at the same position between the substrate before the substrate cleaning, which is the upper substrate in FIG. 4, and the substrate after the substrate cleaning, which is the lower substrate in the same drawing. However, if a defect is detected at any position within the set 9 pixels, it is determined as a defect at the same location.

In this case, the above-mentioned algorithm can be performed by performing the calculation while making the specified pixel range adjacent to each other, but it is more preferable to perform the AND operation while shifting the range by one pixel.

[0025]

FIG. 5 shows a continuous substrate (specifically, a glass ribbon after slow cooling manufactured by a float process), which is a continuous object and a long object, according to an embodiment of the present invention. The determination method will be described. The substrate 1 is transported from left to right in the figure. The substrate 1 first enters the substrate defect inspection machine 4a on the left side, where a substrate defect inspection is performed and defect position information is recorded. Next, the substrate 1 enters the cleaning machine 7 and is cleaned, and then enters the substrate defect inspection device 4b on the right side to inspect the substrate for defects. At this time, the position information of the defect before the substrate cleaning is transferred from the left substrate defect inspection device 4a to the right substrate defect inspection device 4b. This makes it possible to compare defect information before and after substrate cleaning.

FIG. 6 shows a board discriminating method and a board selecting method according to another embodiment of the present invention. The substrate 1 is transported from left to right in the figure. The substrate 1 first enters the substrate defect inspection machine 4a on the left side, where a substrate defect inspection is performed and defect position information is recorded. Next, the substrate 1 enters the cleaning device 7 and is cleaned, and then enters the substrate defect inspection device 4b on the right side.
A board defect inspection is performed.

At this time, the position information of the defect before the substrate cleaning is transferred from the substrate defect inspecting machine 4a on the left side to the computer 9, and the positional information of the defect after the substrate cleaning is transmitted from the substrate defect inspecting machine 4b on the right side to the computer 9. Is transferred. This makes it possible for the computer 9 to compare defect information before and after cleaning the substrate. Further, the determination result is transferred from the computer 9 to the sorting machine 8, and the sorting machine 8 sorts the substrates 1. That is, it is sorted into non-defective products, semi-defective products, defective products, and the like.

FIG. 7 shows a method of determining a substrate according to still another embodiment of the present invention. The substrate 1 is transported from left to right in the figure. The substrate 1 first enters a substrate defect inspection machine 4, where a substrate defect inspection is performed and defect position information (first position information) is recorded. Next, the substrate 1 enters the cleaning device 7 and is cleaned, and then enters the same substrate defect inspection device 4, where the substrate defect inspection is performed and defect position information (second position information) is recorded. Then, a computer built in the substrate defect inspection machine 4 compares defect information before and after substrate cleaning.
This method does not result in a continuous flow and is somewhat inferior in processing capacity, but has the advantage that only one substrate defect inspection machine 4 is required.

[0029]

According to the present invention, it is possible to provide a method of inspecting a substrate which can discriminate between a substrate defect and a substance adhering to the substrate even using a conventional inspection apparatus. In particular, the effect of the present invention is great for a sheet glass which is a transparent body in which it is difficult to distinguish a substrate defect from a substance attached to the substrate.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the principle of defect inspection by a substrate defect inspection machine used in the present invention.

FIGS. 2A and 2B are conceptual diagrams illustrating the principle of a substrate inspection method according to the present invention, wherein FIG. 2A shows substrate defect inspection information performed before a cleaning step, and FIG. Defect inspection information, (c) is common substrate defect inspection information among substrate defect inspection information performed before and after the cleaning process.

FIG. 3 is a conceptual diagram illustrating a method of collating substrate defect inspection information performed before and after a cleaning step according to the present invention.

FIG. 4 is a conceptual diagram illustrating another method of collating substrate defect inspection information performed before and after the cleaning step of the present invention.

FIG. 5 is a conceptual diagram showing a flow of a procedure according to the embodiment of the present invention.

FIG. 6 is a conceptual diagram showing a flow of a procedure according to another embodiment of the present invention.

FIG. 7 is a conceptual diagram showing a flow of a procedure according to still another embodiment of the present invention.

[Explanation of symbols]

 1: substrate 2: defect 3: attached matter 4: substrate defect inspection machine 5: light source 6: light receiving unit 7: washing machine 8: sorting machine 9: computer

Claims (3)

[Claims] 1. A substrate defect inspection machine performs defect inspection of a substrate which is continuously transported before the substrate cleaning process, records the defect inspection information, and records the defect inspection information after the substrate cleaning process. The defect inspection of the substrate is performed again, and by comparing the substrate defect inspection information performed before the cleaning process with the substrate defect inspection information performed after the cleaning process, the defect is a defect of the substrate or a defect on the substrate. A method for inspecting a substrate, comprising determining whether the substance is an adhering substance. 2. A substrate defect inspection apparatus performs a defect inspection of the substrate before the substrate cleaning step, records the defect inspection information,
By performing a defect inspection of the substrate again by the substrate defect inspection machine after the substrate cleaning step, by comparing the substrate defect inspection information performed before the cleaning step and the substrate defect inspection information performed after the cleaning step, A method for inspecting a substrate, comprising determining whether the defect is a defect of the substrate or a substance attached to the substrate. 3. The inspection method according to claim 1, wherein the substrate is a sheet glass.