JPH02121347A - Positioning device for wafer - Google Patents

Abstract

PURPOSE:To make possible a high-precision positioning of a wafer by a method wherein the wafer is supported by at least 3 pieces or more of rotatably supporting balls to support the rear of the wafer and at the same time, rotationally driving means, which come into contact to the peripheral surface of the wafer and rotate the wafer, are provided and the orientation flat of the wafer is positioned. CONSTITUTION:A wafer is supported its rear by 4 pieces of supporting balls 7 being provided rotatably on a supporting board 4 and at the same time, the peripheral surface on the side of the lower part of the wafer is supported by a pair of driving rollers 8 and 8 and a plurality of guide rollers 9. If a motor 12 is made to drive and the rollers 8 and 8 are rotated in a prescribed direction interlocking to the drive of the motor 12, the wafer is rotated by the frictional contact of the peripheral surface of it itself with each roller 8. Moreover, the wafer is also rotated with the rotation of each roller 8 and the orientation flat of the wafer comes into contact to the rollers 8 and 8 in a state to run parallel to the rollers 8 and 8. Whereupon, at this point of time, a laser beam detecting means 15 detects accurately the central position of the orientation flat and at the same time, as the rotation of the rollers 8 is stopped, the wafer results in being positioned on the board 4.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is an improvement in a positioning device for positioning a semiconductor wafer in a predetermined orientation before supplying the wafer to an etching process, inspection process, etc. It is related to.

(Prior Art and its Problems) When a wafer is supplied to an etching process, an inspection process, etc., an orientation flat (hereinafter referred to as an orientation flat) is formed on the peripheral edge of a wafer before the wafer is supplied.

) is generally used as a reference to position the evaporator in a predetermined direction. This technology was developed in the 4th century
9-148854, Japanese Patent Publication No. 61-49817, Japanese Patent Publication No. 60-91640, and U.S. Patent No. 4376482
It is well known by the number etc.

However, in conventional positioning devices of this type, the wafer is placed directly on a smooth plate coated with Teflon, and the wafer is mechanically rotated on the plate to position it in a predetermined direction. Because of this, even if the disk surface is coated with Teflon, the coefficient of friction between the wafer and the disk surface becomes large when rotating the wafer, making it impossible to rotate the wafer smoothly, which is a major problem. was holding.

For this reason, there are devices that rotate the wafer while floating it with pressurized air, but such devices have technical difficulties in blowing out air uniformly from nozzles, etc.
The installation of the nozzle and its attached members increases the size of the device itself, resulting in an increase in cost.

In addition, all conventional devices are configured to use mechanical mechanisms to position the wafer with respect to the orientation flat, so there is a problem in that high precision cannot be achieved during positioning. It also had.

Structure of the Invention (Means for Solving the Problems) The present invention has been devised in view of the problems of the conventional positioning device. The wafer is supported by possible support balls and is provided with a rotation drive means for rotating the wafer in contact with the peripheral surface of the wafer.

The present invention is characterized by a device for positioning the orientation flat of the wafer.

(Function) Therefore, in the present invention, the back surface of the wafer is supported by the support balls rotatably provided on the support plate, and at the same time, the peripheral surface of the wafer on the placement side is rotated by the rotation driving means. Supported by

Therefore, when this rotation drive means is rotated, the wafer also rotates as the rotation drive means rotates, and the orientation flat of the wafer comes into contact with the rotation drive means, thereby detecting the center position of the orientation flat.

Moreover, in the present invention, when rotating the wafer,
Due to the rotation of the support ball that supports the back side of the wafer, the coefficient of friction with the underside of the wafer becomes extremely small, ensuring smooth rotation of the wafer, so that highly accurate positioning of the wafer is always possible without generating dust. becomes.

(Embodiment) Hereinafter, the present invention will be described in detail based on an illustrative embodiment. As shown in FIGS. 1 and 2, the wafer positioning device according to the embodiment A pair of guide rails 2, 2 are arranged at a predetermined interval on the side, and a pair of ultra-thin belts are provided to transfer the wafer W to the rear end side of the base 1 between the pair of guide rails 2, 2. While installing conveyor 3.3.

A U-shaped support plate 4 for supporting a wafer W is rotatably supported in the center of the base 1 via a pivot 5, and the support plate 4 and a cylinder 6 provided at the bottom of the base 1 are connected. When connected, the support plate 4 can be reciprocated between a horizontal position and an inclined position with respect to the base 1 by the operation of the cylinder 6.

In this embodiment, three support balls 7 for supporting the back surface of the wafer W are rotatably provided on each of the left and right side pieces 4a defining the U-shape of the support plate 4, and A pair of drive rollers 8 that contact the side peripheral surface of the wafer W to rotate the wafer are disposed on the side of the connecting lower piece 4b of the support plate 4, and a plurality of guides are arranged on the outside of each drive roller 8. The roller 9 is arranged rotatably.

In addition, as shown in FIG. 3(a) in particular, each of the above-mentioned support balls 7 is rotatably held within a holding body 10 having a threaded portion 10a with a number of ball bearings 11 interposed therebetween. The body 10 is attached to the support plate 4 via the screw portion 10a, and each of the pair of drive rollers 8 is provided with a pulley (not shown) below each pulley, and the drive pulley 13 on the motor 12 side is connected to the pair of drive rollers 8. By hanging a belt 14 between them and transmitting the rotational force of the motor 12 via the belt 14, both 8 and 8 are rotated in a predetermined direction in conjunction with each other.

The arrangement of the support balls 7 is, for example, as shown in FIGS. 3(b), (c),
As shown in (d), the wafer W is
This is an arrangement that supports evenly.

Further, in this embodiment, an optical detecting means such as a laser beam detecting means 15 or an optical device consisting of a light emitting element and a light receiving element is mounted on the base 1 near the drive roller 8 provided on the support plate 4. A configuration is adopted in which a center position of the orientation flat of the wafer is optically detected by providing a target detection means.

Next, to explain the operation of this embodiment, when a wafer (not shown) is transferred onto the support plate 4 by the belt conveyor 3 while being regulated by the pair of guide rails 2, 2,
The support plate 4 is rotated from a horizontal position to an inclined position by the action of the cylinder 6, and the wafer W is supported on the support plate 4 in an inclined state.

As a result, the back surface of the wafer is supported by the four support balls 7 rotatably provided on the support plate 4, and at the same time, the lower surface of the wafer is supported by the pair of drive rollers 8 and the plurality of drive rollers 8. It is supported by guide rollers 9.

For example, the four supporting balls 7 are arranged so that the center of the wafer W is 4
It coincides with the center of the rectangle connecting the positions of the support balls 7. In the above-mentioned rectangle, support balls 7 are arranged at each corner of the square. The number of supporting balls 7 may be 3 or 5 or more as long as the supporting surface is formed. Therefore, by driving the motor 12, the pair of driving rollers 8
8 in a predetermined direction, the wafer rotates due to frictional contact between its circumferential surface and each drive roller 8, but at this point, the orientation flat of the wafer has not yet been detected by the laser beam detection means 15. Therefore, the rotation of the drive roller 8 continues.

As the drive roller 8 rotates, the wafer also rotates, and when the orientation flat of the wafer comes into contact with the pair of drive rollers 8 in parallel, at this point the laser beam detection means 15 accurately detects the center position of the orientation flat. At the same time as detecting
Since the drive roller 8 stops rotating, the wafer is thereby positioned on the support plate 4.

When the wafer is rotated, the four support balls 7 that support the back surface of the wafer rotate with high precision via a large number of ball bearings 11, so the coefficient of friction with the bottom surface of the wafer becomes extremely small, and the wafer Smooth rotation is always guaranteed.

Therefore, once the support plate 4 is returned to the horizontal position by the action of the cylinder 6, the positioned wafer is again placed on the belt conveyor 3 in the same position, and is oriented in the correct direction for the etching process, inspection process, etc. They will be transferred.

As described above, the present invention supports a support plate that supports a wafer so as to be rotatable between a horizontal position and an inclined position with respect to the base, and a support plate that supports a wafer at a suitable location on the bottom surface of the wafer. At least two or more support balls for supporting the wafer are rotatably provided, and rotation driving means for rotating the wafer by contacting the circumferential surface of the wafer is provided, and a wafer orientation flat is provided at an appropriate position on the base. Since the wafer is characterized by being equipped with an optical detection means for detecting the center position of the wafer, the presence of the support ball makes it possible to minimize the coefficient of friction with the lower surface of the wafer and ensure smooth rotation of the wafer. Since the positioning of the wafer is carried out solely by optical detection means, it has become possible for the first time to consistently position the wafer with high precision.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a positioning device according to an embodiment of the present invention, FIG. 2 is a side view of the same, FIG. 3(a) is a cross-sectional view showing a support ball holding structure, and FIG. 3(b) c) and (d) are plan views showing examples of arrangement of wafers and support balls. laser beam detection means (optical detection means), w... wafer. Patent applicant Tokyo Electron Ltd. 1... Base, 4... Support plate, 5... Axis.

Claims (1)

[Claims] At least three or more support balls supporting the back surface of the wafer are rotatably provided, and rotation driving means for contacting the circumferential surface of the wafer to rotate the wafer is provided, and the wafer is positioned on an orientation flat. A wafer positioning device characterized by comprising means.