JPH0664748A - Magnetic levitation vacuum conveyer - Google Patents

Abstract

PURPOSE:To provide magnetic levitation vacuum conveyer wherein a conveyed object of wafer or the like conveyed in a vacuum can be prevented from being contaminated by dropping down particles. CONSTITUTION:In a magnetic levitation vacuum conveyer of comprising a vacuum tunnel 1 formed of a partition 2 to hold the inside in a vacuum condition, conveying base 3 arranged in the vacuum tunnel 1, plurality of levitating electromagnets 4 for supporting the conveying base 3 levitated in a noncontact condition and a linear motor 6 for moving the conveying base 3 to run, a dustproof part 12 for covering a conveyed object is provided in the conveying base 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation vacuum transfer apparatus, and more particularly to a transfer table on which an object to be transferred such as a wafer is placed in a vacuum and floated by magnetic force so that the track can be moved in a non-contact state with a track. Regarding the improvement of.

[0002]

2. Description of the Related Art In a vacuum, even if there is no air flow, it is very small, and it is not possible to peel off particles adhering to the wall of a vacuum container or to lift up particles on the floor. Not really. Therefore, since there is a possibility that a class 0 space can be created in a vacuum, in recent years, not only the semiconductor manufacturing process, but also the transfer system for transporting a wafer to a process apparatus and the storage of the wafer have tended to be performed in a vacuum. In this case, when the wafer is transferred in a vacuum, most of the wafers are transferred in a vacuum tunnel by placing the wafer on a transfer table (cart) for transferring the wafer, floating the wafer by magnetic force, and applying a magnetic force from the outside.

Initially, the vacuum tunnel is clean, but the particles applied when the resist applied to the front surface of the wafer or the resist attached to the back surface of the wafer peels off and falls, particles that flow in from the process equipment, and valves. Particles generated due to dust generated by opening and closing of will adhere to the wall of the vacuum tunnel and become contaminated as it is used for a long time. Contamination particles have a large particle size, and as the number of particles increases, the balance between the van der Waals force, which is an adhesive force, and the gravity, that is, the self-weight of the particles is broken, and the particles separate from the wall and fall. In this case, the particles fall vertically because there is no air flow in the vacuum or there is very little air flow. Then, the falling particles adhere to and contaminate the wafer if the wafer being conveyed is directly below.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to prevent an object to be transferred such as a wafer transferred in a vacuum from being contaminated by falling particles. An object of the present invention is to provide a magnetic levitation vacuum transfer device that can be used.

[0005]

In order to achieve the above-mentioned object, a magnetic levitation vacuum transfer apparatus of the present invention is provided with a vacuum tunnel which is formed by a partition wall and whose inside is maintained in a vacuum state, and which is arranged in the vacuum tunnel. In a magnetic levitation vacuum transfer device including a transfer table, a plurality of levitation electromagnets for floating and supporting the transfer table in a non-contact state, and a linear motor for moving the transfer table, an object to be transferred to the transfer table It is characterized in that a dustproof portion for covering an object is provided.

[0006]

According to the present invention having the above-described structure, since the transfer table is provided with the dustproof portion for covering the object to be transferred such as the wafer, the object to be transferred can be prevented from being contaminated by the particles falling.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the magnetic levitation vacuum transfer apparatus according to the present invention will be described below with reference to FIGS. In FIG. 1, the magnetic levitation vacuum transfer device includes a vacuum tunnel 1 which is formed by a partition wall 2 and whose inside is kept in a vacuum state, and a transfer table 3 which is arranged in the vacuum tunnel 1. Above the vacuum tunnel 1, levitation electromagnets 4, 4 for levitation-supporting the carrier 3 in a non-contact state are arranged on the left and right.

On the other hand, below the vacuum tunnel 2, a linear motor 6 for moving and moving the carrier 3, a displacement sensor 8,
8 are arranged. Although not shown, the levitation electromagnet 4, the linear motor 6, and the displacement sensor 8 are installed at equal intervals in the traveling direction of the carrier (direction perpendicular to the plane of FIG. 1). Then, an electromagnetic brake (not shown) is installed on the carrier table 3
Is provided at a position where it should be stopped.

The operation of the magnetic levitation vacuum transfer apparatus configured as described above will be briefly described. The displacement sensor 8 detects the vertical distance from the sensor to the transfer table 3 and the detection result is not shown in the floating control apparatus. Output to. This levitation control device responds to the output from the displacement sensor 8 to increase or decrease the current supplied to the levitation electromagnet 4 to control the magnetic attraction force acting on the carrier table 3. As a result, the carrier 3 can be stably floated vertically without contact. Then, the linear motor 6 urges the carrier table 3 in the traveling direction (direction perpendicular to the paper surface of FIG. 1) to drive the carrier table 3.

Next, the detailed structure of the carrier 3 will be described with reference to FIG. The transfer table 3 shown in FIG. 2A is formed in a box shape, and a mounting table 11 for mounting the wafer 10 is provided on a lower portion 3a thereof, and an upper portion 3b thereof protects the wafer from falling particles. It is a dustproof part. Also, reference numeral 3
Reference numeral c is an opening for loading and unloading the wafer 10.

It should be noted that a detachable dustproof plate 12 may be provided inside the carrier table 3 shown in FIG. In this case, in addition to the upper portion 3b forming the dustproof portion, the dustproof plate 12 prevents particle contamination of the wafer 10. Figure 2
The transfer table 3 of the type shown in (a) is effective for particles falling vertically because the wafer is covered by the dustproof portion above the transfer table 3. However, if it is used for a long time, the carrier itself may become dirty. in this case,
Since the carrier itself becomes a source of contamination, it is irrational to wash the carrier as a whole. At this time, as shown by the phantom line in FIG. 2A, since the dustproof plate 12 attached to the carrier 3 can be removed, it is only necessary to remove it from the carrier 3 and wash only the dustproof plate 12. After all, the carrier 3 of the type shown in FIG.
Also, by providing the removable dustproof plate 12, the wafer can be prevented from particle contamination by simple cleaning.

The transfer table 3 shown in FIG. 2 (b) is formed in a flat plate shape, and a mounting table 11 for mounting the wafer 10 is provided on the upper surface thereof and a removable dustproof plate 12 is provided. There is. A carrier table 3 of the type shown in FIG.
The presence or absence of the dustproof plate 12 directly affects the degree of particle contamination of the wafer.

The material of the dustproof plate may be metal, Teflon, propylene or the like. As a metal material, a light alloy such as an Al alloy or a Ti alloy is preferable in order to float the carrier. If the thickness of the dustproof plate is too thick, it will be too heavy, and if it is too thin, it will bend without strength, so 0.5 mm to 3 mm is preferable.

The larger the size of the dustproof plate is, the more effective it is. However, the size of the dustproof plate is usually 20 times larger than the diameter of the wafer.
A large percentage is sufficient. The distance between the dustproof plate and the wafer is as narrow as possible so long as the clearance between the dustproof plate and the wafer placed on the arm of the vacuum robot when the wafer is mounted on the carrier is satisfied, but it may be about 3 mm to 20 mm. .

3 to 5 are explanatory views showing various methods for fixing the dustproof plate to the carrier. FIG. 3 shows an example in which the dustproof plate is fixed to the carrier with bolts. FIG. 3A shows an example in which a support base 14 is provided on the carrier base 3 and a flat dustproof plate 12 is fixed to the support base 14 with bolts 15. Figure 3
FIG. 3B shows an example in which the dustproof plate 12 is fixed to the upper surface of the carrier 3 with bolts 15, and FIG. 3C shows an example in which the dustproof plate 12 is fixed to the side surface of the carrier 3 with bolts 15.

FIG. 4 shows an example in which the dustproof plate is fixed to the carrier by a slide holder. That is, a pair of leaf spring-shaped slide holders 16, 16 are fixed to the carrier table 3 by the bolts 15. Then, the dustproof plate 12 has both side edge portions 1
It is fixed to the carrier table 3 by inserting the slide holders 16 and 16 into the slide holders 16 and 16.

FIG. 5 shows an example in which the dustproof plate is fixed to the carrier by engaging the groove and the protrusion. That is, the grooves 3a, 3
a, the projections 12b, 12b are formed on the dustproof plate 12, and the dustproof plate 12 is formed by the engagement of the groove 3a with the projection 12a.
Is fixed to the carrier 3. 5A shows an example in which the groove 3a is provided on the upper surface of the carrier table 3 and the projection 12b is provided on the lower end of the dustproof plate 12, and FIG. 5B shows the groove 3a on the side surface of the carrier table 3 and the projecting portion 12b. This is an example in which the portions 12b are provided on the inner surface of the lower portion of the dustproof plate 12, respectively.

[0018]

As described above, according to the present invention, since the transfer table is provided with the dustproof portion for covering the object to be transferred such as the wafer, the object to be transferred can be prevented from being contaminated by the falling particles. . Further, since the dustproof portion is attachable / detachable to / from the carrier, only the dustproof portion can be cleaned, and it is not necessary to clean the entire carrier.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a magnetic levitation vacuum transfer device according to the present invention.

FIG. 2 is an explanatory view showing a structure of a dustproof portion in the magnetic levitation vacuum transfer device according to the present invention.

FIG. 3 is an explanatory view showing a method of attaching a dustproof plate in the magnetic levitation vacuum transfer device according to the present invention.

FIG. 4 is an explanatory view showing a method of attaching a dustproof plate in the magnetic levitation vacuum transfer device according to the present invention.

FIG. 5 is an explanatory view showing a method of attaching a dustproof plate in the magnetic levitation vacuum transfer device according to the present invention.

[Explanation of symbols]

 1 Vacuum Tunnel 2 Partition 3 Transfer Platform 4 Levitation Electromagnet 6 Linear Motor 8 Displacement Sensor 10 Wafer 11 Placement Table 12 Dustproof Plate 15 Bolt 16 Slide Holder

Claims (2)

[Claims] 1. A vacuum tunnel formed of a partition wall, the inside of which is kept in a vacuum state, a carrier arranged in the vacuum tunnel, and a plurality of levitation electromagnets for levitationally supporting the carrier in a non-contact state. A magnetic levitation vacuum transfer apparatus comprising: a linear motor for moving the transfer table; and a dustproof portion for covering an object to be transferred provided on the transfer table. 2. The magnetic levitation vacuum transfer apparatus according to claim 1, wherein the dustproof portion is formed of a dustproof plate detachably provided on the carrier.