JPS61184841A - Method and device for positioning of wafer - Google Patents

Abstract

PURPOSE:To simplify the next process by positioning a wafer by bringing the wafer in accordance with the reference position and direction in the course of transportation and utilizing a function of straight movement and rotation of a wafer transporting handler effectively. CONSTITUTION:The position of a center point O' of a wafer 3 and a direction O'R of an orientation flat 15 are detected by revolving the wafer 3 around a rotation shaft 13 and measuring a position of the periphery of the wafer 3 by a sensor 16. A point of intersection P of the extended line of a line OQ in a reference direction and the extended line of a line O'R in an actual direction is worked out and a distance OP is calculated. Then a pantograph mechanism 9 moves a supporting member 8 of a handler 4 straightly only by the moving quantity corresponding to the resultant value so as to bring the point P in accordance with the point O. The new center point position O'' of the wafer is present on the line OR'. The handler 4 is rotated together with the wafer 3 only by theta to bring the direction OR' in accordance with the reference direction OQ. The center point position moves to a point O''' on the line OQ. As the handler 4 has been slipped in reverse direction by theta, a rotary unit 12 rotates only the handler 4 reversely only by angle theta.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a method and apparatus for positioning a wafer, and more specifically, the present invention relates to a method and apparatus for positioning a wafer. The present invention relates to a positioning method and apparatus for determining the orientation and position of a semiconductor wafer with a national flat in a predetermined direction and position when setting the wafer.

[Prior Art] In semiconductor manufacturing equipment, etc., it is necessary to process a plurality of wafers one after another, so a wafer cassette storing a plurality of wafers in the form of a shelf is arranged, and the wafers are removed from the shelves in the cassette. The wafers are taken out one by one and placed on a wafer chuck, etc., and after the necessary processing steps are completed, the wafers are stored from the wafer chuck into separate wafer cassettes. However, recently, processed wafers have been returned to their original cassettes, making the wafer cassette on the storage side unnecessary and making the equipment more compact. Therefore, it has been proposed that wafers be transferred between a wafer cassette and a wafer chuck using a wafer transfer handler that can reciprocate and rotate in a horizontal plane, such as a pantograph robot hand. .

However, the position of the center point of the wafer and the orientation of the wafer's orientation flat within the cassette are not constant, and the handler only receives and transports the wafer in the cassette. Since there is no function to correct variations in wafer position and orientation, the center point position and orientation of the wafer on the handler will vary from wafer to wafer, making it necessary to position the wafer after transferring it to the wafer chuck. Therefore, there are unavoidable problems such as having to provide a positioning mechanism on the wafer chuck or the like, and reducing throughput.

[Summary of the Invention] The present invention solves the problems of the prior art described above, and provides a method for aligning the center point position of the wafer and the direction of its orientation flat on a wafer transfer handler to a constant reference position and direction. The present invention aims to provide a method and apparatus for positioning a wafer.

That is, in the positioning method according to the present invention, for transporting the wafer between the wafer cassette and the wafer chuck,
A wafer transport handler capable of reciprocating and rotating in a horizontal plane is used to position the wafers on the handler while transferring the wafers from the cassette to a wafer chuck or the like.

The positioning method according to the present invention includes a detection step, a movement step, and a single rotation step as its main steps, and the wafer is positioned on the handler by a combination of these steps.

In the detection step, the handler that has received the wafer is positioned at a predetermined detection position, and then the outer circumferential position of the wafer is measured at this detection position, thereby determining the position of the center point of the wafer and the direction of its orientational flat. Detect.

In the moving step, the handler is linearly moved or rotated along with the wafer in a horizontal plane based on the detection result in the detection step, so that the orientation of the wafer's orientation flat is aligned with the reference direction, and the center point of the wafer is moved to the reference position. Match.

In the independent rotation step, before or after the rotation of the handler during the movement step, the wafer is temporarily held in the same orientation without shifting the central point position, and only the handler is rotated by a predetermined angle before the rotation of the handler is performed. The temporary hold is released and the handler is made linearly movable or rotatable together with the wafer again.

The handler is rotatable around a rotation axis set at a predetermined position near the detection position, and a reference position at which the wafer center point should be aligned is preferably set on this rotation axis. .

The handler is also capable of reciprocating along a straight line passing on the rotational axis, and the direction of linear movement is directed in multiple directions as the handler rotates around the rotational axis, one of which is directed toward the wafer. One direction is toward the cassette, and another direction is toward a processing system such as a wafer chuck. One of these linear movement directions is selected as the reference direction. For example, the orientation flat of the wafer is Orientation is performed so that it is perpendicular to the direction from the rotation axis toward the wafer cassette.

Temporary holding of the wafer in the single rotation step is performed for relative rotation between the handler and the wafer, at which point the wafer is removed from the support of the handler and held in place by another fixed member, such as a fixed mounting table. During this time, only the handler is rotated by the same angle in the direction opposite to the rotation direction in the movement step, so that the orientation of the handler and the orientation of the wafer match. In this case, the rotation angle of the handler in the movement step is given by the detection result in the detection step, so the handler is rotated individually before the rotation together with the wafer in the movement step to offset the handler in advance. It is possible to provide an angle, or to absorb the relative angular deviation by rotating the handler alone after the rotation together with the wafer in the moving step.

The positioning device of the present invention for carrying out such a method includes a wafer transport handler that can carry a wafer and move back and forth in a horizontal plane, and a position of the center point of the wafer on the handler at a preset detection position. a detection device that detects the orientation of the handler and the direction of its oriented flat; a rotation device that rotates the handler around a rotation axis at a predetermined position; A wafer can be transferred between the handler and a control device that controls the rotation device to adjust the position of the center point of the wafer and the direction of the orientational flat to a predetermined reference position and direction, respectively. The basic element is a holding means for holding the received wafer in the same position and attitude.

In this case, preferably, the reference position is set on the rotation axis in the vicinity of the first row of detection positions, and the control device performs a control operation to align the wafer center point with the handler rotation axis. do.

The detection device includes, for example, a non-contact sensor for measuring the wafer outer circumferential position placed near the detection position.In this case, one sensor may be used, but it is possible to use multiple sensors to measure the wafer outer circumferential position at multiple locations. , the amount of rotation of the wafer during detection can be reduced or not required at all. As this non-contact sensor, it is preferable to use a capacitance type proximity sensor from the viewpoint of measurement accuracy, but it is of course possible to use other sensors such as a photoelectric type.

The holding means is necessary for the above-mentioned independent rotation of the handler, and preferably includes an elevating device for elevating and lowering the handler, and by lowering the handler, the wafer is placed in contact with the lower surface of the wafer on the handler. It consists of a fixed mounting table to hold the device.

There are various types of handlers for carrying wafers, but the one suitable for carrying out the present invention is one that reciprocates a support member that supports the wafer horizontally in a horizontal plane using a uniaxial reciprocating system such as a pantograph mechanism, and This is a robot hand that has a uniaxial reciprocating system and the ability to rotate the support member around a vertical rotation wheel to the bare minimum.

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment] Figs. 1 to 3 show a wafer positioning apparatus according to an embodiment of the present invention, and Figs. 4 to 5 show a wafer positioning operation.

1 to 3, a wafer cassette 2 is set on one side of the upper surface of a support stand 1, and wafers 3 are stored in a plurality of shelves within the cassette. On the other side of the upper surface of the support 1, a wafer transfer handler 4 is supported by an elevating pedestal 5 and is located on the upper surface of the support. It is supported so that it can be raised and lowered. The handler 4 includes a fork-shaped horizontal support member 8 on which the wafer 3 is placed and transported;
It has a pantograph mechanism 9 for linearly reciprocating the support member 8, and the pantograph mechanism 9 has both rotating wheels 1.
The support member 8 is linearly reciprocated by opening and closing with a rotation of 0.10 degrees, and the support member 8 is moved into the cassette 2 in the direction shown in the figure or withdrawn therefrom in the opposite direction.
The wafers are transferred between the support member 8 and the shelves in the cassette 2 through the cooperation of this linear reciprocating movement and the vertical movement of the lifting frame 5. This pantograph mechanism 9
is supported by a pantograph opening/closing drive unit 11 via its rotation wheel 10.10, which unit 11 is further supported by a rotation shaft 13 of a handler rotation unit 12, and this rotation unit 12 is The elevating frame 5
installed on. Therefore, the handler 4 can move up and down in the direction of the axis of the rotating shaft 13, and can also rotate around the axis to change the direction of linear movement of the support member 8. For example, the handler 4 can move the wafer received from the cassette 2, The wafer is transferred to a wafer chuck (not shown) placed in a direction other than the cassette 2, or vice versa.

The axial center position of the rotation shaft 13 is determined so as not to be outside the tip of the support member 8 when the handler 4 is at its retracted limit position from the wafer cassette. Preferably, as shown in FIG. It is on the line connecting both axes of the rotating shaft 10.10.

In the illustrated example, the position of the axis O of the rotating shaft 13 is the reference position for aligning the center point of the wafer, and the retraction limit position of the handler is the detection position described later.

When the handler 4 at the backward limit position is lowered, it comes into contact with the lower surface of the wafer 3 above it, and the handler 4 can leave the wafer 3 and move down further. A fixed mounting table 14 is provided.

In addition, a non-contact sensor 16 such as a capacitive type is used to measure the outer circumferential position of the wafer 3 on the handler 4 at the retract limit position with high precision and detect the center point position of the wafer and the direction of the orientational flat 15. is supported and arranged on a mounting base 17.

FIG. 4(a) shows a completed positioning state in which the center point of the wafer 3 coincides with the reference position O (axis center of the rotating shaft 13) and the orientation flat 15 is oriented in the cassette direction (OQ force direction). Furthermore, FIG. 4(b) shows a state in which the center point of the wafer 3 received from the cassette 2 onto the handler is shifted and the direction of the orientation flat is also different. In (b), 0' is the actual center point position of the wafer, and O'R is the direction of its oriented flat.

An example of operation when positioning a wafer using the apparatus shown in FIGS. 1 to 3 will be described below.

First, the handler 4 takes out one wafer 3 from the cassette 2. This is done by opening and closing the pantograph mechanism 9 by rotating the support member 8 facing the OQ force direction by rotating the shaft 10, 10 of the unit 11. When the handler 4 is loaded with the wafer 3 and stopped at the backward limit position, the center point position 0' of the wafer 3 does not coincide with the reference position O in most cases, and the orientation of the orientational flat 15 is also in the OQ force direction. It is facing the shifted 0'R direction, and this is shown in Figure 4 (b
). The target positioning state for this will be described below as shown in FIG. 4(a).

First, in the state shown in FIG. 4(b), the wafer is detected by the sensor 16.
The position of the center point O' and the orientational flat 1
Here, the sensor 16
is located at the top of the fixed mount 17, so the motor 6 and the feed mechanism 7 raise the elevating pedestal 5 to bring the wafer 3 on the handler 4 close to within the working distance of the sensor 16.

The mounting height of the sensor 16 is such that the handler 4 is
sensor 16 when transferring wafers on the top shelf.
Needless to say, this is predetermined to a level that does not interfere with the handler 4 or the wafer 3 placed thereon.

The above-mentioned O' and O'R can be detected by rotating the handler 4 on which the wafer 3 is placed once around the rotation axis 13 by the rotation unit 12, and measuring the outer peripheral position of the wafer 3 with the sensor 16 during this period. Let's do it.

By calculating the coordinates of this measurement result, the actual wafer 3
The center imaginary position 120 of Positioning to the target position is performed.

To do this, first, as shown in Figure 5(a), find the position of the intersection P between the extension of the straight line OQ in the reference direction and the extension of the straight line 0'R in the actual direction, and calculate the distance OP. The support member 8 of the handler 4 is moved linearly by the pantograph mechanism 9 by the amount of movement corresponding to this, and thereby the point P
Match point 0. At this time, the center point 0' of the wafer 3 is at the position o'' in FIG. It will be located in

In this state, the reference direction OR and the actual direction OR' intersect on the axis 0 of the rotating shaft 13 of the handler 4, and the angle between them is determined as θ. In the next step, the handler 4 is rotated by θ together with the wafer 3 in the direction OR'
is aligned with the reference direction OQ. This state is shown in Figure 5(b).
The center point position of the wafer 3 moves to the point O on the straight line OQ. Here, the linear movement direction of the handler 4 is deviated from the reference direction OQ by θ in the opposite direction due to the θ rotation. In order to restore this deviation, the handler 4 is lowered, and the wafer 3 is fixed on the mounting table 14 with the same orientation.
The handler 4 is placed and held on top, and then only the handler is lowered to remove contact with the wafer, and then only the handler 4 is rotated in the opposite direction by an angle θ by the rotation unit 12. After this, the handler 4 is raised again and the 3 wafers on the fixed mounting table 14 are lifted.
on top of it, and as shown in Figure 5(C), O'/
The support member 8 is moved linearly by the pantograph t[9 so as to eliminate the difference between and O, and the center point of the wafer 3 is aligned with the reference position 0. Thereafter, the orientation of the handler 4 is changed by rotation toward a wafer chuck or the like in a direction other than the cassette direction, and the pantograph mechanism 9 is extended to send out the positioned wafer.

In this example, the case was described in which the direction of the wafer was first aligned with the reference direction and then the direction of the handler was returned; It may also be possible to allow it to align with the reference direction after that. Further, the reference direction of the wafer is not the OQ force direction shown in FIG. 4(a), but may be any direction within 360°.

[Effects of the Invention] As described above, according to the present invention, the wafer is aligned with the reference position and direction while being transferred from the wafer cassette to the wafer chuck, etc., and the linear movement and rotation of the wafer transfer handler are controlled. Since positioning can be performed by effectively utilizing the functions, it is possible to simplify the mechanism for the next process without providing a positioning mechanism for wafer pre-alignment on the wafer chuck side, and also contributes to improving throughput. .

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the overall configuration of a positioning device according to an embodiment of the present invention, FIG. 2 is a partially cutaway front view, and FIG.
The figures are also a plan view 9, Fig. 4 (a> is a partial plan view showing the wafer situation after positioning, Fig. 4 (b) is a plan view showing the wafer situation before positioning, and Fig. 5 (a) (b) (c
) is an explanatory diagram showing the movement of the wafer and handler in the positioning process. 2: Wafer cassette, 3: Wafer, 4: Wafer transport handler, 5: Elevating frame, 6: Motor, 7: Feeding mechanism, 8: Wafer support member, 9: Pantograph mechanism, 11: Pantograph opening/closing drive unit, 12: Handler rotation unit, 13: rotation axis, 14: fixed mounting base, 15: orientation flat, 16: non-contact sensor, 11: mounting base, 0: reference position, OQ: reference direction. Procedural amendment (voluntary) March 14, 1985 Manabu Shiga, Commissioner of the Patent Office 7, Indication of the case 1985 Patent Application No. 24517 2, Name of invention Wafer positioning method and device 3, Make amendments Relation to the Patent Case Patent Applicant Residence 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (1)
00) Canon Co., Ltd. Representative Ryu Kaku 3, Agent 105 Address 2-8-1 Toranomon, Minato-ku, Tokyo "Drawings"

Claims (1)

[Claims] 1. A wafer transfer handler capable of reciprocating and rotating in a horizontal plane receives a wafer, and the position of the center point of the wafer and the direction of the orientation flat are determined in advance. A method of determining a reference position and a reference direction on the handler, in which the handler that receives the wafer is positioned at a predetermined detection position, and then the outer peripheral position of the wafer at the detection position is measured. A detection step for detecting the position of the center point and the orientation of the oriented flat of the wafer; and a step of detecting the oriented flat of the wafer by linearly moving or rotating the handler along with the wafer in a horizontal plane based on the detection results. A moving step for aligning the orientation of the wafer with the reference direction and aligning the center point of the wafer with the reference position, and temporarily holding the wafer in the same orientation without shifting the center point position before or after rotating the handler in the moving step. , an independent rotation step of rotating only the handler by a predetermined angle and then allowing the handler to linearly move or rotate the wafer together again. 2. Wafer positioning according to claim 1, wherein the rotational axis of the handler is located at a predetermined location near the detection position, and the reference position is set on this rotational axis. Method. 3. The wafer according to claim 1, wherein the reference direction is set as one of the linear movement directions of the handler, and in the moving step, the handler is rotated so that the oriented flat of the wafer is orthogonal to the reference direction. Positioning method. 4. The wafer positioning method according to claim 1, wherein the wafer is transferred to and temporarily held by the fixing member by the vertical movement of the handler in the single rotation step. 5. A wafer transport handler that can carry a wafer and move back and forth in a horizontal plane; a detection device that detects the position of the center point of the wafer on the handler and the orientation of its oriented flat at a predetermined detection position; a rotation device that rotates the handler around a rotation axis at a predetermined position; and a rotation device that controls the handler and the rotation device based on the detection result of the detection device to determine the position and orientation of the center point of the wafer. A control device that adjusts the orientation of the null flat to a predetermined reference position and reference direction, respectively, and the handler can transfer wafers, and maintain the received wafers in the same position and attitude. A wafer positioning device comprising: a holding means; 6. The wafer positioning device according to claim 5, wherein the reference position is determined on the rotation axis of the handler near the detection position. 7. The wafer positioning device according to claim 5, wherein the detection device includes a non-contact sensor that measures the outer peripheral position of the wafer. 8. The wafer positioning device according to claim 7, wherein the non-contact sensor comprises a plurality of sensors that measure the outer peripheral position of the wafer at a plurality of locations. 9. The wafer positioning device according to claim 7 or 8, which uses a capacitive sensor as the non-contact sensor. 10. Claim 5, wherein the holding means includes an elevating device that raises and lowers the handler, and a fixed mounting table that places and holds the wafer by coming into contact with the lower surface of the wafer on the handler when the handler is lowered. wafer positioning device. 11. The wafer positioning device according to claim 5, wherein the handler includes a wafer support member that supports the wafer horizontally, and a pantograph mechanism that reciprocates the wafer support member in a horizontal plane.