JPH04138303A - Edge detection for light transmitting material - Google Patents

Abstract

PURPOSE:To improve the detecting accuracy of an edge by casting light on the surface of a light transmitting material at an acute angle, comparing the light with light which is cast at a vertical angle and detecting the edge of the light transmitting material based on the attenuation of the amount of the received light in a photodetector due to the increase in the light path. CONSTITUTION:The incident light 7 from a light source 6 is incident on the surface of quartz glass 5 at the incident angle of 45 degrees. The light passes through the glass 5 and reaches a photodetector 11. The light path is deviated by 0.7 mm by the refractive index of the glass 5, and the light is emitted from the glass 5. At this time, 2% of the incident light 7 is reflected from the surface of the glass 5, and the reflected light 8 is formed. In the glass 5, 6% is absorbed, and 92% of the incident light 7 becomes the transmitted light 9. Therefore, the amount of the transmitted light 9 is decreased by the amount corresponding to the increased length of the light path passing the glass 5 by about 40% in comparison with the case of the vertical incident light. The transmitted light 9 is refracted in the glass 5 and deviated downward by 0.7 mm. Therefore, an aperture 10 which restricts the light receiving plane to the minute area of 0.5 phi is provided on the entier surface of the photodetector 11. Then, the transmitted light through the glass 5 does not reach the photodetector 11 at all, and the output of a detecting device becomes zero. Thus the edge can be detected accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method for detecting an end face of a light-transmitting material such as a glass mask.

The purpose is to obtain a method that can easily and accurately detect end faces.

■The light emitted from the light source is incident on the surface of the light-transmitting material,
In an end face detection method in which light transmitted through the light transmitting material is received by a light receiving element and the position of the end face of the light transmitting material is determined based on the magnitude of change in the amount of received light, the light that is incident on the surface of the light transmitting material is The incident surface of the dazzling light is incident at an angle from a plane perpendicular to the surface of the light-transmitting material, and the optical path of the dazzling light is increased compared to when the dazzling light is incident perpendicularly to the light-transmitting material. by. The end face of the light-transmitting material is detected by attenuation of the amount of light received by the light-receiving element.

(2) Due to the optical path of glare due to the refractive index of the glare-transmitting material. Depending on the presence or absence of the amount of light received by the light receiving element.

The end face of the light-transmitting material is configured to be detected.

[Industrial application field]

The present invention relates to a method for detecting an end face of a light-transmitting material such as a glass substrate used in a mask.

In recent years, as semiconductor devices have become more highly integrated and finer, the mechanisms of semiconductor devices have become more precise, and clean rooms have become ultra-clean, the automation of semiconductor manufacturing equipment has progressed, and semiconductor manufacturing methods that are compatible with this have become necessary. It has become to.

[Conventional technology]

FIG. 3 is an explanatory diagram of a conventional example.

In the figure, 13 is quartz glass, 14 is photocube element 1
5 is a light source, 16 is a light, and 17 is a light receiving element.

As the automation of semiconductor manufacturing equipment progresses, in the process of handling masks, as shown in Figure 3 (a), in order to check the presence or absence of a mask glass substrate such as quartz glass 13, or to adjust the position, it has been necessary to A photocoupler 14 is used.

However, since glass is transparent, it has secondary problems.

FIG. 3(b) shows a conventional glass substrate edge detection device showing the surface of 2 quartz glass 3 and the photocoupler 14.
are arranged in a vertically intersecting manner. When moving the quartz glass 13 and detecting the end face of the quartz glass 13, the actual quartz glass 13 has various surface conditions and end face cross-sectional shapes, so the end face position cannot be detected. The reproducibility is only about ±0.5mm, which is ±0.2mm, which is required in the LSI process.
The following detection accuracy requirements could not be met.

This is because a substrate such as quartz glass 13 with high transmittance is used, so even if one quartz glass 13 is subdivided at the end face part as shown in FIG. 3(c) and the light 16 is transmitted through it, (d
), this is because the output change in the amount of light transmitted is too small to make a determination, and the variation is large, making it impossible to obtain accuracy.

[Problem to be solved by the invention]

This is because a very transparent material is used as the glass substrate, such as the quartz glass mentioned above, and even if some light is blocked, the amount of light is different from when it is not blocked, that is, when there is no glass substrate. Again, there is almost no change. This is because the detection accuracy of the end face detection circuit of the photocoupler with respect to a light-transmitting material such as a glass substrate is low.

The present invention is provided for the purpose of increasing the amount of light attenuation by the glass substrate for transmitted light and improving the end face detection accuracy of a photocoupler with respect to the glass substrate.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

In the figure, 1 is a light-transmitting material, 2 is a light source, 3 is a light, and 4
is a light receiving element.

The present invention increases the amount of attenuation of light 3 passing through a light-transmitting material 1 such as a transparent glass substrate, thereby increasing the difference in signal magnitude between the presence and absence of an end face of the light-transmitting material 1. The arrangement of the light source 2 and the light receiving element 4 of the photocoupler, which is an end face detection device, is changed from the direction perpendicular to the conventional light-transmitting material 1 to the first direction.
As shown in Figure (a), the light-transmissive material IG is placed at an angle from a perpendicular surface, that is, in an oblique direction.

As a result, as shown in FIG. 5, an increase in the amount of light attenuation occurs due to an increase (extension) of the optical path of the light 3 that passes through the light-transmitting material 1.

In addition, since the optical path of the transmitted light 2 is shifted due to the refraction of the light 3 corresponding to the refractive index of the light-transmitting material 1, if the incident surface of the light-receiving element 4 is made into a minute area smaller than the range of shift, the light transmittance can be improved. The amount of light received by the light receiving element 4 through the material can be reduced to zero.

That is, one object of the present invention is to make light 3 emitted from a light source 2 enter the surface of a light-transmitting material 1 as shown in FIG. Depending on the magnitude of the change in the amount of light received by receiver 1.

In an end face detection method for determining the position of an end face of the light-transmitting material 1.

The plane of incidence of the linear light 3 incident on the surface of the light-transmitting material 1 is
The optical path of the line light 3 is smaller than that in the case where the line light (3) is incident at an angle from a plane perpendicular to the surface of the light transmitting material 1, and the line light (3) is incident perpendicularly to the light transmitting material 1. Due to increase. Also, by detecting the end face of the light-transmitting material 1 due to the attenuation of the amount of light received by the light-receiving element 4. This is due to the deviation of the optical path of the linear beam 3 due to the refractive index of the light-transmitting material 1. This is achieved by detecting the end face of the light-transmitting material 1 based on the presence or absence of the amount of light received by the light-receiving element 4.

[4? l:...] In this way, by adopting an edge detection method in which transmitted light is incident on the surface of a light-transmitting material such as a glass substrate at an inclined angle, the refraction of light by the light-transmitting material As the optical path length increases9, the amount of attenuation of transmitted light increases accordingly.
In addition, a shift in the optical path occurs, eliminating the transmission of light from the light source to the light-receiving element in a straight line, and compared to conventional methods for detecting the presence or absence of the amount of light received, the accuracy of detecting the end face of transparent materials is greatly improved. do.

〔Example〕

FIG. 2 is an explanatory diagram of one embodiment of the present invention.

In the figure, 7 is incident light, 8 is reflected light, 9 is transmitted light, 1
0 is an aperture, 11 is a light receiving element, and 12 is a photocoupler.

As an embodiment of the present invention, the end face of 1 quartz glass 5 is detected using a photocoupler 12.

This will be explained using FIG.

1 quartz glass 5 as shown in FIG. 2(b).

A glass with a refractive index n=1.46 and a glass thickness of 2.31 is used.

An LED light emitting element is used as the light source 6 of the photocoupler 12, and a silicon (Si) photodiode is used as the light receiving element 11.

The photocoupler 12 is adjusted to be at a position of 30 degrees or more, for example, 45 degrees, with respect to the surface of the quartz glass 5.

Incident light 7 from the light source 6 enters the surface of the quartz glass 5 at an incident angle of 45 degrees, passes through the quartz glass 5, and reaches the light receiving element 1.
1, but in this case, due to the refractive index of 2 quartz glass, the optical path exits the quartz glass with a deviation of 0.7 mm.

2% of the incident light 7 from the light source 6 is reflected on the surface of the quartz glass 5 to become reflected light 8 2 6% is absorbed in the quartz glass 5 , and 92% of the incident light is transmitted to the quartz glass 5 as transmitted light 9 Transmit.

For this reason, the optical path of the transmitted light 9 through the quartz glass 5 is approximately 40% longer, and the amount of light is reduced compared to when the light is incident perpendicularly.

Further, the transmitted light 9 is refracted by the quartz glass 5, and 0
．． Since the light-receiving element 11 is shifted downward by 7 mm, an aperture 10. Or if you make a slit.

As shown in FIG. 2(c), the light transmitted through the quartz glass 5 does not reach the light receiving element at all, and the output of the detection device becomes zero, making it possible to easily and precisely reveal the end face.

〔Effect of the invention〕

As explained above, 1. With the detection method according to the present invention, 2. Even in a highly transparent light-transmitting material such as quartz glass, detection of the end face is not based on the amount of attenuation of incident light.

By using the deviation of the optical path, false detections are eliminated.

The conventional detection accuracy of ±0.5n+m has been dramatically improved to ±0.2mm.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention. FIG. 2 is an explanatory diagram of one embodiment of the present invention. Figure 3 is an explanatory diagram of the conventional example. It is. In fig. 1 is a light-transmitting material. 3 is light. 5 is quartz glass. 7 is incident light 9 is transmitted light. 11 is a light receiving element. 2 is the light source 4 is a light receiving element 6 is a light source. 8 is reflected light 10 is the aperture. 12 is a photocoupler 13 is quartz glass. 14 is a photocoupler 15 is a light source. 16 is light 17 is a light receiving element ■ Ko←1-

Claims (1)

[Claims] 1) Light (3) emitted from a light source (2) is transmitted through a light-transmitting material (
The light (3) that is incident on the surface of the light-transmitting material (1) and transmitted through the light-transmitting material (1) is received by the light-receiving element (4). In an end face detection method for determining the position of an end face, the incident plane of the light (3) incident on the surface of the light transmitting material (1) is angled from a plane perpendicular to the surface of the light transmitting material (1). and the light (3) is incident on the light-transmitting material (1).
Detecting the end face of the light-transmitting material (1) by attenuating the amount of light received by the light-receiving element (4) due to an increase in the optical path of the light (3) compared to when the light is incident perpendicularly to the light-transmitting material (1). A method for detecting an end face of a light-transmitting material, characterized by: 2) Depending on the presence or absence of the amount of light received by the light receiving element (4) due to the deviation of the optical path of the light (3) due to the refractive index of the light transmitting material (1), the end face of the light transmitting material (1) may be 2. The method for detecting an end face of a light-transmitting material according to claim 1, further comprising detecting an end face of a light-transmitting material.