JPH1041372A - Wafer positioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely set wafers for a short time on a wafer stage having wafer drop-in steps slightly larger than the wafer, by operating monitors to detect the wafer positions and wafer drop-in positions, and image position correcting processor to compute the wafer travel distances. SOLUTION: Monitors 61 -63 detect the wafer positions and wafer drop-in positions on a wafer stage 1, an image position correcting processor 7 connected to the monitors computes the position correcting values, and a wafer conveyer 5 cooperates with the up-down motion of a pusher up-down mechanism 3 having hands to mount wafers 2 on the stage 1 having wafer drop-in steps 1a slightly larger than the wafers. Three monitors 61 -63 e.g. are disposed with equal spacings along the circumference of the wafer stage 1 to correct so that the differences between the edges of the steps 1a and wafers 2 are equal at the three equal divisions of the wafer circumference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer positioning apparatus used for positioning a wafer on a wafer stage having a wafer dropping step slightly larger than the wafer.

[0002]

2. Description of the Related Art Conventionally, there are the following methods for positioning a wafer, for example. 1) A method in which the edge of the wafer is pressed against positioning pins provided on a stage.

2) A method of recognizing the outer peripheral coordinates of a wafer with a pair or a plurality of sensors on a positioning stage whose absolute coordinates are known in advance, and obtaining and correcting the center coordinates. 3) A method of monitoring the positioning mark on the wafer with a plurality of sensors and correcting the position.

[0004]

However, according to the prior art, when there is no positioning pin, positioning stage, or positioning mark for wafer ±, a wafer stage having a wafer dropping step slightly larger than the wafer is required. It is difficult to reliably set the wafer. Further, since the wafer stage is movable, it stops at a wafer transfer position with a certain variation. Further, it is difficult to carry out and position the wafer in a short time.

The present invention has been made in view of the above circumstances, and provides a wafer positioning apparatus which can surely set a wafer in a short time on a wafer stage having a wafer dropping step slightly larger than the wafer. The purpose is to do.

[0006]

According to the present invention, there is provided a wafer stage having a step of dropping a wafer slightly larger than a wafer, a wafer moving mechanism having an arm function for placing the wafer on the wafer stage and a position correcting function, Wafer position, a plurality of monitors for detecting a wafer dropping position on a wafer stage, an image position correction value calculation device electrically connected to these monitors, and a pusher vertical mechanism for raising and lowering the wafer. This is a wafer positioning device.

In the present invention, the monitor measures the distance between the inner wall surface of the opening of the wafer stage and the edge of the wafer, and calculates the amount of movement of the wafer by the image position correction value calculation device based on the distance. is there. Therefore, at least two monitors are required. However, when the plurality of monitors are three monitors arranged at equal intervals along the circumferential direction of the wafer stage, the difference between the edge of the step of the wafer stage and the edge of the wafer is determined by the outer periphery of the wafer at three equal intervals. Since the correction is made to be equal, even if the wafer stage fluctuates within a certain range (monitor field of view) with respect to the absolute value, the wafer positioning correction can be reliably performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wafer positioning apparatus according to one embodiment of the present invention will be described below with reference to FIGS. Here, FIG. 1 is an overall view of the wafer positioning apparatus, and FIG. 2 is a schematic plan view of a wafer stage and a monitor, which are one configuration of the apparatus.

Reference numeral 1 in the figure denotes a movable wafer stage having a wafer drop step 1a slightly larger than the wafer 2 and having an opening 1b in the center. The wafer stage 1 stops at a wafer transfer position with a certain variation. A pusher up / down mechanism 3 for moving the wafer 2 up and down is arranged near the wafer stage opening 1b. In the vicinity of the wafer stage 1, the wafer 2 is placed on the wafer stage 1.
A wafer moving mechanism 5 having an arm 4 to be mounted thereon is arranged. The wafer moving mechanism 5 has a function of not only placing the wafer 2 on the wafer stage 1 but also correcting the position of the wafer 2.

[0010] above the wafer stage 1, the monitor 6 _and 62, 6 ₃ of 3 recognizes the edge portion of the wafer 2 are arranged at equal intervals of 120 degrees in the circumferential direction of the wafer stage 1 . These monitor ₆₁ through _3, the image position correction value calculation unit 7 is electrically connected. The arithmetic unit 7 is electrically connected to the wafer moving mechanism 5. By the arithmetic unit 7, the gap between the wafer edge and the stepped edge of each monitor ₆₁ through ₃ is equal wafer 2
Is calculated, and the wafer 2 is moved. After the wafer 2 is lifted from the arm 4 by the pusher up / down mechanism 3 and the arm is retracted, the wafer 2 is lowered and dropped into the step.

Next, the operation of the wafer positioning apparatus having such a configuration will be described. First, the wafer 2 is placed on the arm 4 by the wafer moving mechanism 5 and is moved toward the wafer stage 1. When the arm 4 carrying the wafer 2 is conveyed substantially above the wafer stage 1, the image processing by the arithmetic unit 7 A dimension of the monitor 6 _1, B dimension of the monitor 6 _2, the dimension C of the monitor 6 ₃ in FIG. 2 Then, the position is corrected by the arm 4 so that the dimensions A, B, and C become equal. When the position correction is completed, the pusher up / down mechanism 3 is moved upward, and the wafer 2 is moved onto the pusher up / down mechanism 3. After this,
The arm 4 is moved away from above the wafer stage 1. Further, the pusher up / down mechanism 3 is lowered to drop the wafer 2 into the step 1 a of the wafer stage 1. When the wafer 2 overlaps with the step edge, the position correction cannot be calculated. Therefore, it is necessary to recognize the step edge before transferring the wafer.

As shown in FIGS. 1 and 2, the wafer positioning apparatus having the above-described configuration has a wafer stage 1 having a wafer drop step 1a slightly larger than the wafer 2.
When a wafer moving mechanism 5 having a position correction function of the wafer includes an arm 4 for placing a wafer 2 on the wafer stage 1, the wafer position, a plurality of monitor 6 ₁ for detecting the wafer darken position on the wafer stage 1 6 _3, has these monitors ₆₁ through ₃ electrically connected to the image position correction value calculation unit 7, a structure having a pusher elevator mechanism 3 for raising and lowering the wafer 2. According to such a positioning device, the following effects can be obtained.

1) In order to correct the difference between the edge of the step 1a for dropping the wafer and the edge of the wafer 2 so as to be equal at the outer periphery of the three equally arranged wafers, the wafer stage 1 has a wafer transfer position with respect to the absolute value. Range (monitor field of view)
Even if there is variation within the range, the wafer positioning can be corrected reliably.

2) Even if the outer shape of the wafer 2 and the outer shape of the wafer and the step 1a for dropping are varied, the difference between their edges is corrected and controlled, so that the wafer 2 can be reliably set in the step 1a.

3) There is no need to position the wafer using a positioning stage or the like before transferring the wafer, so that the wafer transfer processing time can be reduced. 4) Unlike the conventional positioning by pin contact,
Since the position correction is performed by the wafer moving mechanism 5, the front surface and the edge portion of the wafer are not in contact with each other, and the back surface of the wafer is not rubbed with other components, so that no particles are generated.

Although the above embodiment has described the case where the three monitors are arranged at equal intervals of 120 degrees in the circumferential direction of the wafer stage, the present invention is not limited to this. In addition, the number of monitors need not be three but may be two or more.

[0017]

As described above in detail, according to the present invention, the wafer can be reliably set in a short time on a wafer stage having a wafer dropping step slightly larger than the wafer, and a wafer free from particles is generated. A positioning device can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a wafer positioning device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a wafer stage and a monitor, which are components of the wafer positioning device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer stage, 1a ... Step, 1b ... Opening, 2 ... Wafer, 3 ... Pusher up-and-down mechanism, 4 ... Arm, 5 ... Wafer moving mechanism, 6 _{1 to} 6 ₃ ... Monitor, 7 ... Image position correction arithmetic unit.

Claims (2)

[Claims] 1. A wafer stage having a step of dropping a wafer slightly larger than a wafer, a wafer moving mechanism having both an arm function and a position correction function for mounting the wafer on the wafer stage, a wafer position, and a wafer on the wafer stage. A wafer positioning apparatus comprising: a plurality of monitors for detecting a drop position; an image position correction value calculating device electrically connected to the monitors; and a pusher up / down mechanism for vertically moving the wafer. 2. The wafer positioning apparatus according to claim 1, wherein the plurality of monitors are three monitors arranged at equal intervals along a circumferential direction of the wafer stage.