JPH0631721Y2 - Wafer number reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to an apparatus for reading the number of thin semiconductor substrates, liquid crystal glass substrates, etc. (hereinafter referred to as wafers) stored in a storage container. In particular, it relates to an apparatus for reading the number of wafers in a storage container at high speed without contacting the wafers.

<< Prior Art >> As a device for automatically counting the number of wafers stored in a storage container, for example, a device in which a sensor is moved in contact with the upper part of the wafers stored in the storage container to measure the number of wafers ( JP-A-59-151275), or the image sensor camera receives the reflected light from the end face of the wafer, and by moving the image sensor camera, the reflected light is converted into a time-series electric signal, and the peak number thereof is obtained. By counting the number of wafers without contacting the wafer (Japanese Patent Laid-Open No. 61-13383)
There is.

<Problems to be Solved> In the former conventional technology, the detection rod of the sensor is brought into contact with the end of the wafer, the physical impact caused by the contact is sensed by the detection rod, and the physical impact is converted into an electrical signal. As a result, contact with the wafer cannot be avoided, and there is a problem in that dust adheres to the surface of the wafer.

Further, in the latter conventional example, since the image sensor camera is moved to receive the reflected light from each wafer and the detection signal thereof is time-series, there is a problem that the time required for measurement is long. In addition, in the case of a wafer having an orientation flat, erroneous calculation may occur due to the nonuniform storage posture.

<< Means for Solving Problems >> The present invention has been proposed in view of the above problems, and reads the number of wafers that are arranged in parallel with each other at a predetermined interval and reads the number of wafers. In the apparatus, imaging means for imaging the wafers from a position tilted with respect to the main plane portion of a plurality of wafers and converting the wafers into a two-dimensional image signal, and light irradiation for illuminating the wafers from the same side as the imaging means. Means, binarizing means for binarizing the image signal into a signal indicating the edge of the wafer and a signal indicating the main plane portion, and an image showing the edge of the entire wafer for the binarized image signal. It is a wafer number reading device having a reading means for reading in a crossing direction and a counting means for counting the number of wafers by counting the read signals.

As for the image pickup means, either one-dimensional or two-dimensional image pickup means can be used.

<< Operation >> In the present invention, a plurality of wafers aligned in parallel with each other at a predetermined interval are imaged by the image pickup means from a position inclined with respect to the main plane portion of the wafers and converted into image signals. . At that time, the light irradiation means illuminates the wafer from the same side as the imaging means. The light emitted from the light irradiation means and specularly reflected by the main plane portion of the wafer does not enter the image pickup means, but the light diffusely reflected by the edge portion of the wafer enters the image pickup means. The image signal converted by the image pickup means is binarized by the binarization means into a signal indicating the end portion of the wafer and a signal indicating the main plane portion. It is possible to read the number of wafers by reading the binarized image signal by the reading means in a direction intersecting with the images showing the end portions of all the wafers and then counting the read signals by the counting means.

<< Embodiment >> FIG. 1 shows a schematic perspective view of the apparatus of the present invention.

A storage container (2) containing a large number of wafers (W) is placed on the storage container mounting table (1). In this storage container (2), a large number of wafer storage grooves (4) are formed vertically on both side walls (3) facing each other at a constant pitch and extend over the storage grooves (4) of both side walls (3). The plurality of wafers (W) are held parallel to each other by inserting and fitting the wafers (W) as shown in the figure.

An image sensor camera (5) that collectively captures images of the wafers (W) in the storage container (2) placed at a fixed position on the storage container mounting table (1), and the light source (6) is a control panel ( It is located above 7). That is, a plurality of wafers W arranged at a predetermined interval
The light source (6) illuminates the wafer W from the same side as the image sensor camera (5) when the image sensor camera (5) takes an image from a position tilted with respect to the main plane portion of the image sensor camera (5). This light source
The light emitted from (6) and specularly reflected by the main plane of the wafer W does not directly enter the image sensor camera (5), but the light diffusely reflected by the edge of the wafer W is reflected by the image sensor. It is designed to enter the camera (5).

The two-dimensional image sensor camera (5) is, for example, a CCD
It is composed of an image sensor in which elements are arranged in a matrix and a lens system for forming an image of an original image on the image sensor, and the image sensor outputs an image signal in pixel units.

In the control panel (7), as shown in FIG. 2, an interface (8) for connecting the output signal from the image sensor camera (5) to the data bus, an image memory (9) for storing the image signal, An image processing device (10) for binarizing the image signal stored in the image memory (9), a counter (11) for reading one of the binarized signals, and a display (for displaying each image ( 12) and a central processing unit (CPU) (13) for instructing a processing procedure according to a required flow.

Next, a flow of processing in the above-described sheet number reading device will be described.

A storage container (2) accommodating a plurality of wafers (W) is placed on the storage container mounting table (1) and wafer reading is started.

The light source (6) irradiates the wafer (W) with light, and the image sensor camera (5) images all the wafers (W) in the storage container (2) (step S1).

On the display 12 of the control panel 7, as shown in FIG. 4A, the images (15) of all wafers are displayed in the container image (14).

The image signal from the image sensor camera (5) is stored in the storage device (9) through the interface (8) (step S2).

Here, as described above, since the light specularly reflected by the main plane portion of the wafer (W) does not directly enter the image sensor camera (5), the reflected light from the wafer (W) is due to the main plane portion. Rather, the diffuse reflection light at the edge portion becomes stronger and is detected as an image signal.

In this way, the image signal stored in the storage device (9) is read (step S3), and the bright and dark portions of the bright portion and the dark portion in the reflected light from the main plane (20) and the edge portion (21) of the wafer (W) are read. An appropriate threshold value for the difference is set (step S8), the image signal is binarized by this threshold value (step S4), and as shown in FIG. 4B, the main plane (20) of the wafer (W) and the edge thereof are bordered. The binarized image (17) with the end (21) is displayed.

At this time, if necessary, the bright portion of the wafer (W) is subjected to line segmentation processing such as line segment joining processing or smoothing processing commonly used in image processing, and the binarized wafer image shown in FIG. 4B. It can be converted to (17) and displayed.

The binarized wafer image (17) is stored in the storage device (9) (step S5), and the image signal of the preset reading direction (MM ′) is read (step S6). This reading direction is set as a direction defined with respect to the wafer arrangement direction, for example, as a direction intersecting each end portion of the entire wafer image, but normally, it is substantially orthogonal to the end portion image as shown in FIG. 4B. It is desirable to set the direction (MM '). FIG. 4C shows a read signal at this time, where H in the drawing corresponds to the wafer end portion, and the counter counts the number of H (step S7). And, the count value is the control panel
It is displayed on the counter display section (20) of (7).

By the way, when there is an orientation flat (21) like a semiconductor wafer, if the wafer is randomly inserted, the reflection direction and the reflectance of the reflected light may be slightly different, so that the storage container (2 It is desirable to align the orientation flats of the wafers (W) housed in) in a fixed direction. By doing so, the accuracy can be maintained. In this case, for example, the count value having the largest number of appearances can be adopted as the count value to be obtained, or the operator can determine the count value by looking at the display (12).

Incidentally, since the storage container (2) and the wafer (W) are usually placed on the storage container mounting table (1) in a constant state and at a constant position, the above-mentioned threshold value does not fluctuate much. No
Further, since image signals other than the wafer in the reading direction can be obtained at a substantially constant position, it is easy to count them without counting them.

Here, it will be described that the present invention can be easily implemented even when the above solid-state image sensor is a one-dimensional CCD line sensor.

In this case, for example, if a line sensor in one direction of the wafer is detected by a line sensor and the line sensor is moved in a direction perpendicular to the line direction to obtain a two-dimensional image signal of the wafer, Similar to the above, the wafer counting process can be performed by the image signal.

Further, the imaging direction is set as the above-mentioned reading direction, and the contained wafers are collectively imaged in that direction. A storage device is not always necessary for the binarization process, and the read signal from the CCD sensor may be directly binarized at the above-mentioned appropriate level value and simultaneously counted.

This counting method can be carried out in the same manner as in the above-described embodiment, except for displaying the image.

In addition, the analog image scanning signal output of a conventional TV camera using a vidicon or the like instead of the image sensor camera is
/ D conversion and input to the above-mentioned storage device (9) (step 2)
However, the same processing may be performed thereafter.

<Effect> In the present invention, since the image capturing means captures an image from a position tilted with respect to the main plane portion of the wafer, and the light irradiation means illuminates the wafer from the same side as the image capturing means, the main plane portion of the wafer is not affected. The light is specularly reflected and the reflected light does not enter the imaging means. On the other hand, only the light diffusely reflected by the edge portion of the wafer enters the image pickup means, and the image signal thus obtained is divided into the signal indicating the edge portion of the wafer and the main plane portion by the binarizing means. It can be easily binarized with the signal shown and the number of wafers can be read. This also allows
In the present invention, the number of wafers can be read very easily by reading out the two-dimensional image signal in the direction crossing the image showing the edge of all the wafers and counting it. As a result, in the present invention, the measurement time can be shortened as compared with the conventional one in which the camera is run in a fixed direction to count the number of wafers, and erroneous calculation due to the change of the substrate shape can be eliminated. Even if some defective wafers are removed in the pretreatment process, it is possible to obtain an apparatus capable of accurately reading the number of wafers.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a schematic perspective view, FIG. 2 is a schematic configuration diagram of a control panel, FIG. 3 is a flow chart showing a processing procedure, and FIG. 4B is a diagram showing a binarized image, and FIG. 4C is a diagram showing a read signal. 2 ... storage container, 5 ... imaging means (image sensor camera), 6 ... light irradiation means (light source), 10 ... binarization means,
11: Counting means, W: Thin plate substrate (wafer).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G06M 7/00 Z 9302-2F H01L 21/68 L 8418-4M

Claims (1)

[Scope of utility model registration request] 1. A wafer number reading apparatus for reading the number of a plurality of wafers arranged in parallel with each other at a predetermined interval, wherein the wafers are placed from a position inclined with respect to a main plane portion of the plurality of wafers. An image pickup means for picking up the image and converting it into a two-dimensional image signal, a light irradiating means for illuminating the wafer from the same side as the image pickup means, the image signal for indicating the end portion of the wafer and a signal for indicating the main plane portion. And binarizing means for binarizing, and reading means for reading the binarized image signal in a direction intersecting with the image showing the edge of all wafers, and counting the read signals to count the number of wafers. A counting device for counting the number of wafers.