JPH04295704A - Apparatus for detecting central position of wafer - Google Patents

Abstract

PURPOSE:To shorten the time when the central position of a wafer is detected, to achieve the compact configuration of an apparatus and to eliminate the directivity in the detection. CONSTITUTION:A linear image sensor 15 is provided on the halfway of conveying path of a wafer 3 which is conveyed with a wafer conveying device 13. A wafer-center-position operator 16 obtains the maximum detecting length and the deviation from a reference position at the maximum detecting length based on the picked-up image from the linear image sensor and operates the central position of the wafer. There parts 15 and 16 are provided. The central position of the wafer can be immediately detected only by passing the wafer with respect to the linear image sensor.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer center position detecting device provided in a semiconductor manufacturing device or a semiconductor testing device.

0002

2. Description of the Related Art Generally, semiconductor manufacturing equipment and semiconductor inspection equipment that process wafers on a wafer basis often use a wafer storage jig called a wafer carrier when transporting wafers. In this case, since the posture of the wafer within the wafer carrier is uncertain, the center position of the wafer is detected during the wafer transport path of semiconductor manufacturing equipment, etc., and the posture of the wafer is corrected and positioned.

3 and 4, one example of a wafer center position detecting device that detects the wafer center position using an optical sensor will be described.

In FIGS. 3 and 4, 1 is an optical sensor unit;
2 is an arm of a wafer transfer device, and 3 is a wafer.

The optical sensor unit 1 includes light projecting elements 6 provided on blocks 4 and 5, which are provided facing each other.
, four pairs of sensors 8, 9, 10, 11 each consisting of a light receiving element 7
The four pairs of sensors 8, 9, 10, and 11 are provided on the circumference having the same radius as the radius of the wafer 3, and the peripheral edge of the wafer 3 is detected by these sensors 8, 9, 10, and 11. do.

In order to detect the center position of the wafer 3 using the conventional wafer center position detection device described above, four pairs of sensors 8, 9, 10, 11 are arranged in groups 8, 9 on the left side and groups 10, 11 on the right side. , into groups 9 and 10 on the tip side, and the movement of the conveying device and the sensors 8, 9,
The wafer center position is detected based on the wafer detection timings 10 and 11. Further, this will be explained in detail with reference to FIG.

First, the wafer 3 is moved straight toward the optical sensor unit 1 (A). If the sensor 11 senses the periphery of the wafer 3 at this time, the position of the wafer 3 at this time is stored. Next, move wafer 3 to the left (
B), it is stopped at the position detected by the sensor 8, and further moved to the right by half the amount of movement to the left (C). Further, the wafer 3 is advanced and it is confirmed whether the sensors 8, 9, 10, and 11 simultaneously detect the peripheral edge of the wafer 3 (D). If there is a difference in detection timing between sensors 8, 9, 10, and 11, the steps up to now are repeated and sensors 8, 9, 10, and 1
1 converges to a state where the peripheral edge of the wafer 3 is detected at the same time. The position of the wafer 3 in the converged state is stored, and detection of the center position of the wafer 3 is completed.

[0008]

As described above, in the conventional apparatus, the center position of the wafer is detected by repeatedly moving the wafer left and right, moving it forward, and moving it backward alternately, which takes time. Since the center position detection has directionality, there are restrictions on the installation location of the center position detection device. In addition, since the sensor is provided in an arc shape, the optical sensor unit 1 cannot be miniaturized.
There were other problems.

In view of the above circumstances, the present invention aims to shorten the time required to detect the center position of a wafer, and to eliminate the directivity of the detection device in detecting the center position of the wafer.

0010

[Means for Solving the Problems] The present invention provides a linear image sensor provided in the middle of a wafer transport path to be transported by a wafer transport device, and a maximum detection length and a maximum detection length based on the imaging output from the linear image sensor. The present invention is characterized by comprising a wafer center position calculator that calculates the wafer center position by determining the deviation from the reference position at any time.

[0011]

[Operation] The maximum length detected by the image sensor is nothing but the diameter of the wafer, and the midpoint of the detected length at this time is the center of the wafer. Therefore, the center position of the wafer can be detected by finding the deviation between the midpoint position of the maximum detection length and the reference position.

0012

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

1 and 2, reference numeral 13 indicates a wafer transfer device;
4 indicates a wafer loading section, and the wafer transport device 13
A linear image sensor 15 having a detection range sufficiently longer than the wafer diameter is provided between the wafer loading section 14 and the wafer loading section 14 . The detection results from the linear image sensor 15 are input to a wafer center position calculator 16 .

The output from the center position calculator 16 is input to a control section 17 of the semiconductor manufacturing apparatus, and the detected position is displayed on a display 18.

The wafer transfer device 13 includes a drive section 19
a rotatable first arm 20 provided in the first arm 20;
a second arm 21 rotatably provided in the second arm 21;
It has a third arm 22 rotatably provided in the first and second arms.
By the cooperation of the third arms 20, 21, and 22, the wafer 3 placed on the tip of the third arm is moved to a desired state, such as straight forward movement or rotation.

The wafer loading section 14 is configured to load the wafer 3
The wafer carrier 23 loaded in multiple stages is mounted on the wafer carrier 23, and the wafer carrier 23 is
It is designed to raise and lower.

Next, the operation will be explained.

The wafer 3 is taken out from the wafer carrier 23 by the wafer transfer device 13, and is passed below the linear image sensor 15 while being placed on the third arm 22. The linear image sensor 15 detects the linear image sensor 1 of the wafer 3 during passing.
The length of the chord at the position corresponding to 5 is detected every moment, and the detection result is output to the wafer center position calculator 16.

The wafer center position calculator 16 calculates the maximum value of the chord, that is, the diameter of the wafer 3, and calculates the distance from the center of the apparatus (reference position) at the maximum chord value to the chord end, C in FIG.
, D.

Thus, the deviation of the wafer center position from the reference position, that is, the center position of the wafer 3 can be determined by (C-D)/2. The determined center position of the wafer 3 will be used as data for handling and transporting the wafer, and will be displayed on the display 18 if necessary.

[0021]

Effects of the Invention As described above, according to the present invention, the center position of the wafer can be detected during the normal transport operation without requiring any special operation for detecting the wafer position, thereby reducing processing time. can be achieved. Furthermore, since the wafer only needs to pass through the detection range of the linear image sensor, there is no directionality, and there are fewer restrictions on the installation of the linear image sensor. Since it is only necessary to provide a linear image sensor, the sensor can be made compact and the device can be downsized.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention.

FIG. 2 is a side view of the embodiment.

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

FIG. 4 is a view taken along arrow A in FIG. 3;

FIG. 5 is an explanatory diagram showing grouping of sensors in the conventional example.

FIG. 6 is an explanatory diagram showing grouping of sensors in the conventional example.

FIG. 7 is an explanatory diagram showing a wafer center position detection operation in the conventional example.

[Explanation of symbols]

3 Wafer 13 Wafer transport device 15 Linear image sensor 16 Wafer center position calculator

Claims (1)

[Claims] Claim 1: The maximum detection length and the deviation from the reference position at the time of the maximum detection length are determined from a linear image sensor installed in the middle of the wafer transport path carried by the wafer transport device and the imaging output from the linear image sensor. 1. A wafer center position detecting device, comprising: a wafer center position calculator that calculates the wafer center position by determining the wafer center position.