JPH06232047A - Wafer rotating device - Google Patents

Abstract

PURPOSE:To rotate a work table at a high speed without generating any dust by supporting a rotating shaft against a housing by means of magnetic bearings and supplying electric power to an electrical load on the rotating shaft side from the housing side in a non-contacting state. CONSTITUTION:A rotating shaft 12 is rotatably supported against a housing 11 in a non-contacting state by means of radial magnetic bearings 13 and 14 and a thrust magnetic bearing 16. When electric power is supplied to a stator 18b from a power source, the shaft 12 rotates against the housing 11 together with a work table 17, but no dust is generated, because the shaft 12 itself is supported in a non-contacting state by means of the bearings 13, 14, and 16. Therefore, the rotating shaft 12 can be rotated at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer rotating device incorporating a non-contact power feeding mechanism.

[0002]

2. Description of the Related Art When a semiconductor wafer is subjected to various surface treatments, the semiconductor wafer is usually heated uniformly while rotating, and various surface treatments are performed by a chemical method.

FIG. 4 shows an example of a conventional wafer rotating apparatus for the purpose of such work.

That is, a work table for mounting a semiconductor wafer (not shown) on the upper end of a rotary shaft 104 which is rotatably supported in a vertical state with respect to the housing 103 via two sets of upper and lower ball bearings 101 and 102. 105 is fixed coaxially. Between the two pairs of upper and lower ball bearings 101, 102, there is provided a rotor 106a integrally fitted to the rotary shaft 104, and a stator 106b held by the housing 103 so as to surround the rotor 106a. A shaft drive motor 106 is incorporated, and a power source (not shown) is connected to the stator 106b.

On the other hand, a heater 107 is incorporated in the work table 105 as an electric load for heating and holding a semiconductor wafer at several hundreds of degrees Celsius, and a cable 108 connected to this heater 107 is connected to the lower end portion of the rotary shaft 104. It has been pulled out to. A power feeding brush 110 connected to a power source (not shown) outside the housing 103 via a cable 109 is attached to the lower end portion of the housing 103, and a cable 108 at the lower end portion of the rotating shaft 104 is attached to the power feeding brush 110. It is in sliding contact.

That is, the electric power is supplied to the heater 107 embedded in the rotating work table 105 through the power feeding brush 110.

[0007]

In recent years, as the degree of integration of semiconductor elements has been improved, an even cleaner semiconductor manufacturing environment has been demanded. However, from the viewpoint of improving the productivity, the rotation speed of the work table 105 in the wafer rotating apparatus as shown in FIG. 4 tends to increase, and dust generation from the ball bearings 101 and 102 and the power feeding brush 110.
There is a problem that the dust generated from the sliding contact portion with the cable 108 pulled out to the lower end of the rotary shaft 104 has a significant adverse effect on the yield of semiconductor wafers.

Further, since the electric power is supplied to the heater 107 in the rotating work table 105 by using the power feeding brush 110, there is a limit to the high speed rotation of the work table 105,
As a result, there is a problem in that the performance of a CVD apparatus or the like for forming various thin films on the surface of a semiconductor wafer is limited to a certain degree.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wafer rotating device capable of rotating a work table at high speed without any fear of dust generation.

[0010]

SUMMARY OF THE INVENTION A wafer rotating apparatus according to the present invention includes a table on which a work is placed and an electric load for the work is incorporated, and a rotation unit which is coaxially and integrally provided with the table. A shaft, a magnetic bearing interposed between the rotary shaft and the housing to rotatably support the rotary shaft in a non-contact state with the housing; and a magnetic bearing incorporated between the housing and the rotary shaft. Driving means for driving the rotating shaft, a primary coil fixed to the housing so as to surround the rotating shaft and connected to an AC power supply, and fitted to the rotating shaft so as to face the primary coil. In addition, a secondary coil connected to the electric load is provided.

[0011]

[Function] The rotating shaft is supported by the housing through a magnetic bearing, and the magnetic bearing itself is a non-contact supporting type.
No dust is generated due to friction. When an alternating current is supplied from the alternating current power source to the primary side coil, the alternating current is induced in the secondary side coil by the principle of the transformer, and this is supplied to the electric load incorporated in the table. That is, electric power is supplied from the housing side to the electric load on the rotating shaft side in a non-contact manner.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, which shows a schematic structure of an embodiment of a wafer rotating device according to the present invention, a space between a housing 11 and an upper portion of a rotary shaft 12 held in a state perpendicular to the housing 11. Includes two sets of radial magnetic bearings 13,
14 are respectively interposed, and between the housing 11 and a thrust disk 15 formed at the lower end of the rotary shaft 12, an annular thrust magnetic bearing 16 arranged along the outer peripheral edge of the thrust disk 15 is interposed. , These radial magnetic bearings 13 and 14 and thrust magnetic bearing 16
The rotary shaft 12 is in a state of being rotatably supported in the housing 11 in a non-contact manner.

A work table 17 for mounting a semiconductor wafer (not shown) is coaxially fixed to the upper end of the rotary shaft 12. Further, between the two sets of upper and lower radial magnetic bearings 13 and 14, a rotor 18a integrally fitted to the rotary shaft 12 and a stator held in the housing 11 so as to surround the rotor 18a. 18b and a rotary shaft drive motor 18 are incorporated therein, and a power source (not shown) is connected to the stator 18b.

Therefore, from the power source (not shown) to the stator 18b.
The rotating shaft 12 is driven and rotated with respect to the housing 11 together with the work table 17 by energizing the rotating shaft 12, but the rotating shaft 12 itself is supported in a non-contact manner via the radial magnetic bearings 13 and 14 and the thrust magnetic bearing 16. Therefore, no dust is generated by these rotations.

On the other hand, a secondary side iron core 19 is integrally fitted to a portion of the rotary shaft 12 between the lower radial magnetic bearing 14 and the thrust disk 15, and an outer peripheral side of the secondary side iron core 19 is fitted. A secondary coil 20 is wound around. Further, a heater 21 is incorporated in the work table 17 as an electric load for heating and holding the semiconductor wafer at several hundreds of degrees Celsius, and the heater 21 and the secondary coil 20 are connected via a cable 22. There is continuity. A primary coil 24 is wound around the inner circumference of an annular primary iron core 23 mounted on the housing 11 so as to surround the secondary iron core 19 with a minute gap therebetween. An AC power supply 26 is connected via a cable 25.

Therefore, since the transformer is constituted by the secondary side iron core 19 and the secondary side coil 20 and the primary side iron core 23 and the primary side coil 24, as shown in FIG. From the AC power supply 26 to the cable 25
When the primary coil 24 is energized via the magnetic flux, a magnetic flux indicated by an arrow is formed between the primary iron core 23 and the secondary iron core 19, and accordingly an alternating current is induced in the secondary coil 20. The induced current is supplied to the heater 21 via the cable 22.

Therefore, as the material of the iron cores 19 and 23, a material having a high magnetic permeability and a low electric conductivity is desirable. The low electrical conductivity of the iron cores 19 and 23 has an effect of minimizing a decrease in efficiency due to an eddy current generated as the work table 17 rotates.

In the above embodiment, the coil 20,
24 is made to face in the radial direction of the rotary shaft 12,
Obviously, it is also possible to make the two face to face each other in the longitudinal direction.

As shown in FIG. 3, which shows a schematic structure of another embodiment of the wafer rotating apparatus according to the present invention, two sets of radial magnetic bearings 13, are provided between the housing 11 and the rotating shaft 12. 14 are respectively interposed, and an annular thrust magnetic bearing 16 is interposed between the housing 11 and the thrust disk 15, and these radial magnetic bearings 1
3, 14 and the thrust magnetic bearing 16 allow the rotating shaft 12
Is in a state of being rotatably supported in a non-contact manner with respect to the housing 11.

A work table 17 is coaxially fixed to the upper end of the rotary shaft 12. Further, between the two sets of upper and lower radial magnetic bearings 13 and 14, a rotor 18a integrally fitted to the rotary shaft 12 and the rotor 18a are provided.
The stator 18 held by the housing 11 so as to surround a
The rotary shaft drive motor 18 having a drive angle b is incorporated, and a power source (not shown) is connected to the stator 18b.

On the other hand, a secondary side iron core 27 is integrally fitted to a portion of the rotary shaft 12 between the lower radial magnetic bearing 14 and the thrust disk 15, and the lower side of the secondary side iron core 27 is fitted. A secondary coil 28 is wound around. Further, a heater 21 is incorporated in the work table 17, and the heater 21 and the secondary coil 28 are electrically connected via a cable 22. A primary coil 30 is wound around the upper surface side of an annular primary iron core 29 mounted on the housing 11 so as to face the secondary iron core 27 vertically with a minute gap therebetween. An AC power supply 26 is connected to the via a cable 25.

Therefore, also in this embodiment, as in the previous case,
Primary coil 3 from AC power supply 26 via cable 25
When 0 is energized, the magnetic flux is generated on the primary side iron core 29 and the secondary side iron core 2
7, and an AC current is induced in the secondary coil 28 accordingly, and this induced current is supplied to the heater 21 via the cable 22.

[0023]

According to the wafer rotating apparatus of the present invention, since the rotary shaft is rotatably attached to the housing via the magnetic bearing, the rotary shaft is in a non-contact state with the housing, and the rotary shaft rotates. As a result of no wear of the bearing, it is possible to prevent dust generation of the bearing itself. Therefore, the rotation axis can be rotated at a high speed, and a semiconductor manufacturing apparatus with good productivity can be realized without impairing the performance of a CVD apparatus or the like for forming various thin films on the surface of a semiconductor wafer.

Similarly, since the electric power is induced from the primary coil mounted on the housing to the secondary coil mounted on the rotary shaft by utilizing the principle of the transformer, the alternating current is not contacted from the housing side. It is possible to supply to the electric load of the disk by using the.Because it is possible to prevent the dust generation due to the electric contact by eliminating the conventional power feeding brush, this contributes to the non-contact support of the rotating shaft by the bearing. Therefore, the manufacturing yield of semiconductor devices can be significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic structure of an embodiment of a wafer rotating device according to the present invention.

FIG. 2 is a functional conceptual diagram showing a relationship between a primary side coil and a secondary side coil attached to a rotating shaft in the present embodiment.

FIG. 3 is a sectional view showing a schematic structure of another embodiment of the wafer rotating device according to the present invention.

FIG. 4 is a sectional view showing a schematic structure of an example of a conventional wafer rotation device.

[Explanation of symbols]

11 is a housing, 12 is a rotating shaft, 13 and 14 are radial magnetic bearings, 15 is a thrust disk, 16 is a thrust magnetic bearing, 17 is a work table, 18a is a rotor, 1
8b is a stator, 18 is a rotary shaft drive motor, 19 is a secondary side iron core, 20 is a secondary side coil, 21 is a heater, 22 is a cable, 23 is a primary side iron core, 24 is a primary side coil, 25 is a cable, 26 is an AC power supply, 27 is a secondary side iron core, 28 is a secondary side coil, 29 is a primary side iron core, and 30 is a primary side coil.

Claims (1)

[Claims] 1. A table on which a work is placed and an electric load on the work is incorporated, a rotary shaft which is provided coaxially and integrally with the table, and between the rotary shaft and a housing. A magnetic bearing that is interposed and rotatably supports the rotating shaft in a non-contact state with the housing; drive means that is installed between the housing and the rotating shaft to drive the rotating shaft; A primary coil fixed to the housing so as to surround the rotary shaft and connected to an AC power source, and a secondary coil fitted to the rotary shaft so as to face the primary coil and connected to the electrical load. A wafer rotating device comprising: