JPH0475361A - Wafer cassette detection device - Google Patents

Abstract

PURPOSE:To make it possible to eliminate error detection of the presence of a wafer cassette by installing a sensor means which detects if said wafer cassette is placed in a specified position with accuracy based on one detection standard and checks for the present of the wafer cassette based on another detection standard. CONSTITUTION:The detection area 12 of a sensor is smaller than the detection area of a sensor 4. Therefore, the sensor 3 will be turned off if a wafer cassette 1 is slightly deviated or lifted up while the sensor 4 will be turned off only when the wafer cassette 1 completely disappears. When the wafer cassette 1 is deviated from a right position or vibrated or lifted up, the sensor 4 will keep its ON state in either case. Therefore, when the wafer cassette 1 is not found on a cassette mount nearby, both the sensors 3 and 4 are turned off, which makes it possible to determine that the wafer cassette 1 is not on the cassette mount 2. When the wafer cassette 1 is placed on the cassette mount 2, but deviated from the right position, the sensor 3 is OFF while the sensor 4 is ON. This construction makes it possible to determine that the wafer cassette 1 is present but deviated from the right position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for detecting the presence or absence of a wafer cassette that stores a plurality of wafers.

[Prior Art] Conventionally, the presence or absence of a wafer cassette for storing wafers has been detected using one sensor, depending on whether the sensor is turned on or off.

For example, as shown in FIG. 6, if the wafer cassette 1 is within the detection area 11 of one sensor 10 and the output of the sensor 10 is on, it is assumed that the wafer cassette 1 exists and is placed correctly. , wafer cassette 1 is sensor 1
If the wafer cassette 1 is outside the detection area 11 of 0 and the output of the sensor 10 is off, it is assumed that the wafer cassette 1 does not exist.

[Problems to be Solved by the Invention] However, in the conventional example described above, the presence or absence of a wafer cassette and whether it is placed correctly is detected by the binary values of on and off of the sensor. If the wafer cassette is present even though it is not placed in the position, the sensor will turn off and falsely detect the presence or absence of the wafer cassette. The sensor may turn off and falsely detect the presence of a wafer cassette. Even if the operator has no intention of removing the wafer cassette, the operator may turn off the sensor and falsely detect the presence of a wafer cassette. There are some drawbacks, such as the fact that it can cause problems.

In view of the problems of the prior art, an object of the present invention is to
To prevent a wafer cassette detection device from erroneously detecting the presence or absence of a wafer cassette.

[Means for Solving the Problems] In order to achieve the above object, the wafer cassette detection device of the present invention detects whether the wafer cassette is correctly placed at a predetermined position and detects whether the wafer cassette is present. (a sensor means for performing detection based on different detection criteria). The sensor means may be one sensor that detects whether the uni cassette is correctly placed in the predetermined position and whether the wafer cassette is present, or two sensors. It may be something.

[Operation] According to this configuration, it is possible to check whether the wafer cassette is placed correctly and whether the wafer cassette exists.
Since detection is performed by setting different detection criteria, for example, different detection areas, the presence or absence of a wafer cassette and whether or not the wafer cassette is in the correct position are detected separately. Therefore, even if the wafer cassette is not in the correct position, The presence or absence of a wafer cassette is detected without false detection.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

Figure 1 shows a wafer cassette detection device according to the first embodiment of the present invention, and is the drawing that best represents the features of the present invention. In the figure, 1 is a wafer cassette, and 2 is a A cassette stand for mounting a wafer cassette, 3 a sensor for detecting whether the wafer cassette is placed correctly, and 4 a sensor for detecting whether a sea urchin cassette is present.

Reference numeral 12 denotes a detection area when the sensor 3 detects whether the wafer cassette 1 is placed correctly.The sensor 3 is turned on when the wafer cassette 1 is present in the detection area 12, and the detection area is 1 wafer cassette in 12
is turned off if it does not exist. That is, the detection area 12
This detects whether or not the wafer cassette 1 is placed correctly, based on whether or not the wafer cassette 1 is present in the wafer cassette.

Reference numeral 13 denotes a detection area when the sensor 4 detects whether or not the wafer cassette 1 exists, and the sensor 4 is turned on when the wafer cassette 1 exists within the detection area 13. It is turned off when cassette 1 is not present.

That is, the presence or absence of the wafer cassette 1 is detected using the presence or absence of the wafer cassette 1 within the detection area 13 as a detection criterion.

The sensing area 12 is narrower than the sensing area 13, so that the sensor 3 will turn off if the wafer cassette 1 is even slightly displaced or lifted from its normal position, but the sensor 4 will only turn off when the wafer cassette 1 is completely gone. It remains on even if the wafer cassette 1 is moved from its correct position, vibrates, or is lifted.

Therefore, as shown in FIG. 2, when the wafer cassette 1 is not above the cassette stand 2, both the sensor 3 and the sensor 4 are off, and it can be determined that the uni cassette 1 is not present. Further, as shown in FIG. 3, if the wafer cassette 1 is on the cassette stand 2 but not in the correct position, the sensor 3 is off and the sensor 4 is on, indicating that the wafer cassette 1 is not present. However, it can be determined that it is not placed in the correct position.

Even if the device in which the wafer cassette 1 is installed vibrates and the sensor 3 turns off, the output of the sensor 4 remains on and stable, so there is no possibility of falsely detecting the presence or absence of the wafer cassette 1. . Furthermore, even if the operator touches the wafer cassette 1, the output of the sensor 4 remains on and stable unless the wafer cassette is completely removed, so there will be no false detection of the presence or absence of the wafer cassette 1. As shown, when the wafer cassette 1 is in the correct position, both sensor 3 and sensor 4 are on, indicating that the wafer cassette 1 is present and in the correct position. Therefore, it can be determined that the wafer cassette 1 can be accessed.

Figure 4 shows a wafer cassette detection device according to another embodiment of the present invention.

In the figure, 1 is a wafer cassette, 2 is a cassette stand for mounting the wafer cassette, and 5 is a sensor for measuring the distance from the cassette stand 2 to the wafer cassette 1.

Regarding the sensor 5, two slice levels, slice 1 and slice 2, are set for the distance from the cassette table 2 to the wafer cassette 1, and 51 and 32 in the figure are the corresponding lower end positions of the wafer cassette 1. This is the line that shows. Slice 1 and slice 2 are the detection criteria for whether or not the wafer cassette 1 is in the correct position, and the detection criteria for the presence or absence of the Univac cassette 1, respectively.
If the distance from to wafer cassette 1 is slice 2 or more, it can be determined that wafer cassette 1 does not exist;
If the distance from the cassette table 2 to the wafer cassette 1 is greater than or equal to slice 1 and less than slice 2, the unit cassette 1
is on the cassette stand 2, but it is determined that it is not placed in the correct position, and if the distance from the cassette stand 2 to the wafer cassette 1 is less than 1 slice, the wafer cassette 1 is placed in the correct position. It can be determined that it is accessible.

FIG. 5 shows a wafer cassette detection device according to a third embodiment of the present invention. In the figure, 1 is a wafer cassette, 2
6 is a light source; 7 is a photodetector for detecting the light emitted by the light source 6 to determine whether the wafer cassette 1 is placed correctly; 8 is a light source; 9 is a cassette stand for mounting the wafer cassette; This is a photodetector for detecting the light emitted by the light source 8 and detecting whether or not the Evercassette 1 is present. When the photodetectors 7 and 9 are detecting light, the rice grains are off, and when they are not detecting light, they are on.

In this configuration, when the photodetector 9 is off, it can be determined that the wafer cassette 1 is not present. When the photodetector 9 is on and the photodetector 7 is off, it can be determined that the wafer cassette 1 is on the cassette stand 2 but not in the correct position. When the photodetector 7 is on, the wafer cassette 1 is placed in the correct position,
It can be determined that it is accessible.

[Effects of the Invention] As explained above, a sensor means is provided which detects whether or not the uni cassette is correctly placed at a predetermined position and detects whether or not a wafer cassette is present based on different detection criteria. This eliminates the possibility of erroneously detecting the presence or absence of a wafer cassette, thereby improving safety, reliability, and operability.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a sea urchin cassette detection device according to the first embodiment of the present invention, FIG. 2 is a schematic diagram showing a state in which the sea urchin cassette is not present in the device of FIG. 1, and FIG. FIG. 4 is a schematic diagram showing a state in which the wafer cassette is not placed in the correct position in the apparatus shown in FIG. 1. FIG. FIG. 6 is a schematic diagram showing a wafer cassette detection mechanism according to a third embodiment of the present invention, and FIG. 6 is a schematic diagram showing a wafer cassette detection mechanism according to a conventional example. Wafer cassette, 2: Cassette stand, 4°10: Sensor, 6.8 Light source, 7. 9: Photodetector, : Detection area.

Claims (1)

[Claims] (1) A wafer characterized by comprising sensor means for detecting whether the wafer cassette is correctly placed at a predetermined position and detecting whether the wafer cassette is present based on different detection criteria. Cassette detection device.