JP2519079B2 - Wafer cassette lifting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a wafer cassette lifting device.

(Prior Art) Generally, in a semiconductor manufacturing apparatus, a wafer cassette is used, and a semiconductor wafer is loaded into or unloaded from the wafer cassette.

Then, when the semiconductor wafer is transferred, for example, a wafer cassette is moved up and down to position the semiconductor wafer at a predetermined transfer position.

In this wafer cassette, for example, about 25 semiconductor wafers are stored in a multi-tiered manner at a predetermined interval. In order to reliably carry out the semiconductor wafers without damaging the semiconductor wafers, the wafer cassettes are accurately positioned. Need to stop.

For this reason, conventionally, the driving accuracy of the apparatus for raising and lowering the wafer cassette has been controlled to reduce the relative speed immediately before the predetermined position to improve the stopping accuracy.

Further, as a technique for changing the ascending / descending speed at a predetermined position, which is not for elevating the wafer cassette, for example, there is one disclosed in Japanese Patent Laid-Open No. 61-13640.

(Problems to be Solved by the Invention) However, the above-described conventional technique has the following problems.

In the former case, accurate control of the stop position is required, and in the latter case, the rotation shaft for lifting and lowering drive itself has a cam groove for obtaining a predetermined speed change. It is difficult to process and it is difficult to deal with changing the stop position.

The present invention has been made in response to the above conventional circumstances,
An object of the present invention is to provide a wafer cassette lifting / lowering device having a simple structure and high positioning accuracy.

[Structure of Invention]

(Means for Solving the Problems) That is, the present invention is a wafer cassette that moves and positions the wafer cassette holder by rotating a rotary shaft having a spiral groove that slides with a part of the wafer cassette holder. The lifting device is characterized in that it comprises means for axially moving the rotary shaft while the rotary shaft is rotating.

(Operation) The wafer cassette lifting / lowering device of the present invention is provided with means for moving the rotating shaft for lifting / lowering the wafer cassette holder in the axial direction during rotation. Can be changed.

(Embodiment) An embodiment in which the wafer cassette lifting device of the present invention is applied to a semiconductor wafer indexer will be described below with reference to the drawings.

For example, a rod-shaped support member A (2) is erected on the base (1) and the lower end thereof is attached, and a rubber belt (3) or the like is used at the upper end of the support member A (2). And a transfer mechanism A for mounting and transferring the semiconductor wafer (4) in parallel with the base (1).
(5) is provided.

Next, in the vicinity of the support material A (2), the support material A
A rotating shaft (6) is erected parallel to (2), and the upper end of the rotating shaft (6) is rotatably supported by the support member A (2) and the lower end thereof is rotatably supported by the base (1) so as to be vertically movable a predetermined distance. It is worn.

A spiral groove (7) having a predetermined size is formed on the surface of the rotary shaft (6). For example, it is formed so as to move up and down by the predetermined distance in 1/2 rotation. For example, on the side of the base (1) of the rotating shaft (6), the base (1)
The gear B (10) meshing with the gear A (9) attached to the shaft of the motor (8) is attached to the rotation driving means attached to the above, and the rotation is performed by rotating the motor (8). The shaft (6) is arranged to rotate.

Further, at the lower part of the gear B (10) of the rotary shaft (6), means for moving the rotary shaft (6) in the axial direction during rotation, for example, the rotary shaft (6) is attached, and the peripheral portion thereof is attached. The second
As shown in FIG. 3 and FIG. 3, two sets of three-dimensional cams (11) each having a predetermined concave-convex shape are formed every 90 degrees, and a peripheral portion of the three-dimensional cam (11) attached to the base (1) side. And a roller (12) for contacting and rotating with. Then, by rotating the rotating shaft (6), the three-dimensional cam (11) also rotates, and the rotating shaft (6) moves up and down in the axial direction corresponding to the unevenness of the peripheral portion of the three-dimensional cam (11).

In addition, for example, the gear B (10) has two sensor plates (1
3) is attached, and the sensor plate (13) is detected by the sensor (14) to stop the rotation of the motor (8).

Next, on the upper side of the gear B (10), the support member A (2) is slidably engaged with the spiral groove (7) formed in the rotary shaft (6).
There is provided a wafer cassette holder ( 17 ) comprising a vertically movable member (15) slidably attached to the table and a table (16) on which a wafer cassette (not shown) is placed. The wafer cassette holder ( 17 ) moves up and down in response to the rotation and vertical movement of the rotary shaft (6).

The table (16) is formed in an approximately H shape, and is attached to the elevating member (15) near the center.

On the other hand, on the rotary shaft (6) side of the base (1), for example, a rod-shaped support member B (18) is erected and the lower end is attached, and the upper end of this support member B (18) is attached. Is provided with a transfer mechanism B (19) for mounting and transferring the semiconductor wafer (4) in parallel with the base (1) similarly to the support material A (2). Then, the transport mechanism A (5) for the support material A (2) and the support material B (18)
A space is provided in the middle of the transfer mechanism B (19) so that a wafer cassette (not shown) placed on the table (16) can pass therethrough. Also, the above table (16)
Is configured to be able to pass in the vicinity of the periphery of the transport mechanisms A (5) and B (19).

 Next, the operation will be described.

First, the case where the semiconductor wafer (4) is stored in a wafer cassette (not shown) will be described.

Generally, a wafer cassette (not shown) is provided with grooves for accommodating semiconductor wafers (4) at a predetermined pitch for accommodating and holding the semiconductor wafers (4). For example, a wafer cassette (not shown) is raised by the predetermined pitch distance so that the semiconductor wafer (4) can be stored.

That is, in FIG. 1, the motor (8) is operated to rotate the rotary shaft (6) to raise the wafer cassette holder ( 17 ), that is, the wafer cassette (not shown). At this time, if only the rotating shaft (6) is used for lifting, as shown in FIG. 4, a wafer cassette (not shown) is used.
The ascending process is the same as the height change due to the spiral groove (7), and the rotating shaft (6) rotates 180 degrees, that is, 1/2 turn increases the height by 1 pitch to 4, for example, and rotates 360 degrees. That is, the height increases by 2 pitches to 8 with one rotation, and changes linearly.

On the other hand, the rotating shaft (6) by the rotation of the solid cam (11)
Changes in the height of the wafer cassette (not shown), that is, the position at which the three-dimensional cam (11) is stopped in contact with the roller (12), for example, the unevenness of the peripheral edge of the three-dimensional cam (11). When it is set at the center of the height difference H (31), it changes corresponding to the rotation as shown in FIG. When the height at the time of stop is 0 as a reference, for example, it moves up and down corresponding to the rotation within a height range of ± 0.5, in other words, the rotation shaft (6) is moved up and down.

Therefore, the actual ascending process of the wafer cassette holder ( 17 ), that is, the wafer cassette (not shown), is a combination of the vertical movement by the rotary shaft (6) and the solid cam (11).

That is, as shown in FIG. 6, with respect to the linear height change (61) due to only the rotation axis (6) indicated by the broken line,
The solid cam (1
Since 1) acts to lower the rotating shaft (6), it makes a downward bending change, and the solid cam (11) acts to raise the rotating shaft (6) between the rotation angles of 90 degrees and 180 degrees. As it does, it exhibits an upward curve.

Particularly, the semiconductor wafer (4) is placed before and after the position near the rotation angle of 0 ° and 180 °, that is, in the wafer cassette (not shown).
In the vicinity of a predetermined stop 1 pitch position for housing the, the change in the rising height is gentle with respect to the change in the rotation angle of the rotating shaft (6). Therefore, even if the accuracy of stopping the rotation operation of the motor (8) and the rotation shaft (6) by detecting the sensor plate (13) by the sensor (14) varies, the wafer cassette (not shown) ) Can be positioned with high accuracy. The pitch interval between adjacent grooves for storing semiconductor wafers provided in a wafer cassette (not shown) is narrow, for example, about 3/16 inch (about 4.76 mm), so high-precision positioning is required. As compared with the case where the height changes linearly as shown in FIG.

The above operation is performed 1/2 rotation of the rotation axis (6), that is, 1 pitch 1
The semiconductor wafer (4), which is repeatedly carried out every 80 ° rotation and carried by the carrying mechanisms A (5) and B (19), is housed in a wafer cassette (not shown).

Next, when the semiconductor wafer (4) stored in the wafer cassette (not shown) is unloaded, for example, the rotation shaft (6) is rotated in the opposite direction to the rotation direction at the time of storage and the wafer cassette (see FIG. (Not shown) is lowered by a predetermined distance,
The semiconductor wafer (4) is placed on the transfer mechanisms A (5) and B (19) and unloaded.

Even in this case, since the height of the wafer cassette (not shown) changes as shown in FIG. 6, the stop positioning accuracy is high.

In the above-described embodiment, the spiral groove (7) of the rotary shaft (6) corresponds to the groove pitch interval of the wafer cassette (not shown), and the pitch is 1/2 pitch of the rotary shaft (6) for one pitch. Although the distance is changed, the present invention is not limited to such an embodiment, and the distance may be changed by one pitch for one rotation of the rotary shaft (6).

Further, the solid cam (11) that vertically moves the rotating shaft (6) may also be configured to vertically move by using, for example, a heart-shaped flat plate cam.

Since the spiral grooves (7) of the rotary shaft (6) are formed at the same pitch, the manufacturing is simpler and less costly than the conventional case of variable pitch, and the height changes. Can be variously changed by changing the shape of the three-dimensional cam (11).

As can be seen from the above description, since the mechanism of the wafer cassette lifting / lowering device of the present invention can obtain excellent positioning accuracy, it can be applied to the indexer for semiconductor wafer as described above.
For example, it is effective when applied to a positioning device such as an XY stage.

〔The invention's effect〕

As described above, according to the wafer cassette lifting / lowering device of the present invention, highly accurate positioning is possible with a simple structure.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment in which the wafer cassette lifting / lowering device of the present invention is applied to an indexer for semiconductor wafers, and FIGS. 2 and 3 are explanatory views of one component of FIG. 1, FIG.
5 and 6 are explanatory views of the operation of FIG. 6 ... Rotary axis, 7 ... Helix groove, 11 ... Solid cam, 12 ... Roller, 17 ... Wafer cassette holder.

Claims (1)

(57) [Claims] 1. A wafer cassette lifting device for moving and positioning the wafer cassette holder by rotating a rotary shaft having a spiral groove that slides with a part of the wafer cassette holder. A wafer cassette lifting / lowering device, characterized in that it is provided with means for axially moving the rotary shaft.