JPH09283603A - Semiconductor wafer detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor wafer detecting device with which the presence/absence of a semiconductor wafer housed in a casette, its height and inclination can be detected accurately. SOLUTION: A vertically moving arm, having a light emitting part and a light receiving part 5, is arranged in a vertically movable manner on both sides of a casette 1 where a semiconductor wafer W is housed. An LED 14, as a light emitting means, and a lens 15, with which the light emitted from the LED 14 is converted to a parallel light, are arranged on the light emitting part 4, and a lens 16, with which the parallel light is condensed, and a CCD line senser 17, as an image input device, are arranged on the light receiving part 5. The lenses 15 and 16, a semiconductor wafer W and the CCD line senser 17 are arranged on the optical axis of the light emitted from the LED 14, and the picture of the semiconductor wafer W is displayed on the CCD line senser 17 by the light emitted from the LED 14. The whole picture of the semiconductor wafer W is image inputted, and the position, etc., of the entire semiconductor wafer W is accurately detected by the vertically moving arm which performs a reciprocating movement from the lower end to the top end of the casette 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer detecting device for detecting the presence / absence of a semiconductor wafer stored in a cassette and detecting whether or not the semiconductor wafer is accurately stored at a predetermined position in the cassette.

[0002]

2. Description of the Related Art Generally, in the process of manufacturing a semiconductor wafer, various steps such as plate making, etching and cleaning must be performed on the wafer. Therefore, the wafer is
Each process is transported by a transport device (particularly a robot or the like). When the wafers are transferred, a storage cassette for storing the wafers together is prepared, and the presence / absence of the stored wafers is detected by the detection device. Conventionally, as this detection device, as shown in FIG.
A detection device as shown in Japanese Patent Laid-Open No. 4-44246 has been proposed.

A semiconductor wafer detecting device M1 shown in FIG.
Is a transmission type optical sensor having a set of a light emitting section 32 and a light receiving section 33 arranged in front of and behind the carrier case 31, and the sensor or the carrier case 31 is moved up and down by an elevating mechanism. In case 3
The presence or absence of the wafer W stored in each groove 1 is detected. In order to detect the presence / absence of the wafer W, the apparatus M1 is configured to widen the oblique light range of the light by inclining the optical axis with respect to the wafer W because the thickness of the wafer W to be detected is small. .

The semiconductor wafer detection device M2 shown in FIG. 6 is mounted on an elevator 42 in which a cassette 41 containing a semiconductor wafer W moves up and down. Two light emitting elements 44 arranged on the sensor fixing base 43 are arranged side by side, and two light receiving elements 45 corresponding to the two light emitting elements 44 are provided.
Are arranged in parallel on the transfer arm 46 of the transfer device with the cassette 41 interposed therebetween. Then, the elevator 42 is gradually lowered to output the light emitting element 44 in accordance with the height position of one wafer W, and the presence or absence of the semiconductor wafer W is confirmed by whether or not the light is blocked. When one semiconductor wafer W is confirmed, the transfer arm 45 operates to transfer the wafer W. Then, the upper semiconductor wafer W is sequentially confirmed and transported.

[0005]

However, in the semiconductor wafer detection apparatus M1 shown in FIG. 5, the light emitting section 32 and the light receiving section 3 are provided.
3 is displaced in the front-back direction, the arrangement pitches P′1, p′2, ... Of the wafers W to be detected are arranged with respect to the arrangement pitches P′1, P′2 ,.
... are not equal and an error occurs. Therefore, the height position of the wafer W is not accurately detected. Further, in the case of one set of transmissive sensors, if there is a lateral shift of the wafer W,
The tilt cannot be detected accurately.

Further, the semiconductor wafer detection device M2 shown in FIG. 6 detects the presence or absence of the semiconductor wafer W depending on whether or not the emitted light is blocked. Therefore, the position in the front-back direction with respect to the light emitting element 44 and the light receiving element 45 and , The height position of the semiconductor wafer W or the position with respect to the inclination is not accurately detected.

The present invention solves the above-mentioned problems, and the presence or absence of semiconductor wafers stored in a cassette,
Alternatively, it is another object of the present invention to provide a semiconductor wafer detection device capable of accurately detecting the height position and the inclination.

[0008]

In order to solve the above-mentioned problems, the semiconductor wafer detecting apparatus according to the present invention employs an image input device, and for that purpose, a light source means for generating parallel light is arranged. Specifically, there is provided a semiconductor wafer detection device comprising a light emitting means and a light receiving means for detecting at least the presence or the position of a semiconductor wafer housed in a cassette, and an image input to the light receiving means. A device is provided, and the light emitted from the light emitting means is projected onto the light receiving means to project the semiconductor wafer onto the image input device.

Further, the light emitting means comprises a light emitting source and an optical element for converting light emitted from the light emitting source into parallel light, and the light receiving means includes an optical element for converging the parallel light. An image input device is preferably used as long as it is configured.

Further, it is more preferable that the image input device is a CCD line sensor.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall view of the semiconductor wafer detecting apparatus M. The cassette 1 is open in the front-rear direction, and a plurality of step portions 2 are formed in the up-down direction on both inner walls. . A semiconductor wafer (hereinafter, referred to as a wafer) W to be array-detected is housed in each step 2. The cassette 1 is placed on the stage 3, and an elevating arm 7 having a light emitting unit 4 and a light receiving unit 5 on both sides is movable in the vertical direction with respect to the direction in which the cassette 1 is released. It is arranged. A drive screw 6 is screwed into the central portion of the lifting arm 7, and the driving screw 6 is driven by a lifting drive motor 9 arranged below the lifting arm 7 via a belt 8.

An elevation position detection encoder 10 is attached to the lower part of the elevation drive motor 9 and is connected to a control device 11 which stores and analyzes the detected data. The control device 11 is provided with a communication port 12 to send information to an external device.

FIG. 2 shows the details of the light emitting section 4 and the light receiving section 5 which are the main parts of the present invention. The light emitting section 4 is provided with an LED 14 as a light source means, and a lens 15 which is disposed in front of the LED 14 (on the left side in the drawing) and which converts the light R emitted from the LED 14 into parallel light. Further, the light receiving section 5 is configured to include a lens 16 for converging parallel light on the light emitting section 4 side and a CCD line sensor 17 as an image input device arranged in front of the lens 16. A wafer W housed in the cassette 1 is arranged between the light emitting unit 4 and the light receiving unit 5, and the center lines of the lens 15, the wafer W, the lens 16, and the CCD line sensor 17 are the optical axes emitted from the LEDs 14. It is arranged to match. Therefore, the light R emitted from the light emitting unit 4 is
Light enters the CCD line sensor 17 through the lens 15. If there is a wafer W on the optical axis, CCD line sensor 17
Light is blocked. Therefore, the CCD line sensor 17
The signal of the CCD line sensor 17 is stored in the storage device while scanning the vertical direction, and the position and inclination of each wafer W stored in the cassette 1 can be detected from the contents of the storage device.

In the semiconductor wafer detection apparatus M having the above structure, the elevating arm 7 is moved upward by the elevating drive motor 9 so as to sandwich the cassette 1 placed on the stage 3. When the light emitting part 4 and the light receiving part 5 of the lifting arm 7 reach the position of the height of the wafer W1 housed in the lowermost stage of the cassette 1, the light emitted from the LED 14 of the light emitting part 4 is blocked by the wafer W1. Then, the image of the wafer W1 is captured by the CCD line sensor 17. Since the elevating arm 7 is continuously raised, the wafer W1 and the wafer W2 immediately above are captured in the image while being raised, and the images of the wafer W are sequentially captured in the CCD line sensor 17. When the uppermost position is reached, the elevating arm 7 is returned below the cassette 1.

Next, a more specific operation principle will be described with reference to the block diagram of FIG.

The driver 29 starts the UART 28 to receive an operation start command from an external device through the communication of RS-232C, and transmits it to the CPU 22. Upon receiving the operation start command, the CPU 22 sends a lifting / lowering operation start command to the I / O 21, and the command generates a pulse and drives the lifting / lowering drive motor 9 via the driver 27 to start the lifting / lowering operation of the lifting / lowering arm 7.

The ascending / descending operation of the ascending / descending arm 7 causes the ascending / descending position detection encoder 10 to output a pulse corresponding to the amount of movement,
The position of the lifting arm 7 is detected by counting the pulses with the up / down counter 20. On the other hand, the pulse of the ascending / descending position detection encoder 10 is connected to the interrupt generating logic 23. The interrupt generating logic 23 sends an interrupt signal to the CPU 22 for each predetermined movement amount, and at the same time, a CCD drive pulse generating means. Send the received light data acquisition command to.

The CCD drive pulse generating means receives the received light data fetching command, drives the CCD line sensor 17, and the CCD line sensor 17 samples the received light data.
The received light data is sent to the A / D converter 25 pixel by pixel via the hold 24. The A / D converter 25 converts the received light data of analog voltage into a digital value.

Upon receiving the interrupt signal, the CPU 22 stores the received light data converted into a digital value in the memory 26 while reading the number of pixels of the CCD line sensor 17. The data stored in the memory 26 is taken in as the image shown in FIG.

From the image data, the wafer W
The height position and inclination of can be calculated. Since the size of one pixel G is predetermined, the pitch of the wafers W arranged vertically is represented by P1, P2, .... Further, the inclination θ of the wafer can be obtained by θ = atan (H1−H2) / T, where T is the width of the data image, H1 is the height on the left side of the target wafer W, and H2 is the height on the right side. it can.

In this way, after the height position, inclination, and presence / absence of each wafer W are calculated in the CPU, U
It is output to the ART 28, and the communication port 1 is output from the driver 29.
2 is transmitted to an external device.

The height position of the elevating arm 7 is the CPU 2
After being calculated by 2, it is sent to the pulse generation driver 27 via the I / O 21 and is instructed to the drive motor 9. Then, the elevating arm 7 is driven upward again, and the height position, inclination, and presence / absence of the wafer W are sequentially detected.

Therefore, information about the height position, inclination, and presence / absence of the wafer W stored in the cassette 1 can be transmitted to the work performed in the next step in advance, and the information can be transmitted to the robot arranged in the next step. Orders can be prepared.
For example, if the work content of the next step is to take out the wafer W and carry it to the orientation flat alignment device in order to correct the orientation flat position of the wafer, all the wafers W already stored in the cassette 2 will be stored. Since the position is detected, the robot can perform its work efficiently according to the command.

In the present embodiment, the elevating arm 7 is moved up and down, but the present invention is not limited to this, and the cassette 1 in which the wafer W is stored may be moved up and down. .

Further, the image input device is not limited to the CCD line sensor, but may be any device capable of inputting an image. Further, the optical element may be any one capable of converting divergent light into parallel light.

[0027]

According to the present invention, the semiconductor wafer detecting apparatus is provided with the light emitting means and the light receiving means for detecting at least the presence or the position of the semiconductor wafer housed in the cassette, and the image receiving means receives the image. The device is installed,
The light emitted from the light emitting means is projected onto the light receiving means in a range wider than the thickness of the semiconductor wafer. Then, the image is detected by projecting the semiconductor wafer onto the image input device. Therefore, the presence or absence of the semiconductor wafer, the position of the height of the semiconductor wafer, or the tilted state can be accurately detected.

Further, the light emitting means comprises a light emitting source and an optical element for converting light emitted from the light emitting source into parallel light, and the light receiving means includes an optical element for converging the parallel light and the optical element. A CCD line sensor as an image input device is provided. Therefore, unlike the conventional case, it is not necessary to obliquely project the light from the light emitting portion on the thin semiconductor wafer, and the presence / absence of the semiconductor wafer, the position in the height direction, and the inclination can be accurately detected.

[Brief description of drawings]

FIG. 1 is an overall view showing a semiconductor wafer detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship among a light emitting portion, a light receiving portion, and a semiconductor wafer in FIG.

FIG. 3 is a block diagram of a control device in FIG.

FIG. 4 is a diagram showing a data image of a semiconductor wafer.

FIG. 5 is a diagram showing a positional relationship between a light emitting portion, a light receiving portion, and a semiconductor wafer in a conventional semiconductor wafer detection device.

FIG. 6 is a view showing another conventional semiconductor wafer detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cassette 4 ... Light emitting part 5 ... Light receiving part 7 ... Elevating arm 14 ... LED (light emitting source) 15, 16 ... Lens (optical element) 17 ... CCD line sensor (image input device) M ... Semiconductor wafer detection device W ... Semiconductor Wafer

Claims (3)

[Claims] 1. A semiconductor wafer detecting device comprising a light emitting means and a light receiving means for detecting the presence or absence of a semiconductor wafer or its position contained in at least a cassette, wherein an image input device is arranged in the light receiving means. A semiconductor wafer detecting device, which is arranged so that light emitted from the light emitting means is projected onto the light receiving means to project the semiconductor wafer onto the image input device. 2. The light emitting means comprises a light emitting source and an optical element for converting light emitted from the light emitting source into parallel light, and the light receiving means collects the parallel light and the optical element. 2. The semiconductor wafer detecting device according to claim 1, wherein the semiconductor wafer detecting device comprises an image input device. 3. The semiconductor wafer detection device according to claim 1, wherein the image input device is a CCD line sensor.