JPH04355944A - Wafer rotating device - Google Patents

Abstract

PURPOSE:To detect the speed of rotation of a placing stage support pillar in a closed vessel in a state that the sealing performance of the closed vessel is held. CONSTITUTION:A placing stage 3 placed with a wafer 2 and a placing stage support pillar 4 bonded firmly to this placing stage 3 are respectively housed in a closed vessel 1. A magnetic fluid seal 6 couples a motor 7 with the pillar 4 in a noncontact state in a state that the sealing performance of the vessel 1 is held. A through hole 8 is perforated in the pillar 4 and a luminous flux from a light-emitting device 14 passes through the hole 8 via a window 14, transmits a window 12 and is made incicident to a photodetector 15. A detection output of the photodetector 15 shows the speed of rotation of the pillar 4. A control device 16 controls the speed of rotation of the motor 7 on the basis of the detection output so that the speed of rotation of the pillar 4 reaches a desired value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer rotation device for rotationally driving a semiconductor wafer, and in particular, a mounting table on which a wafer is placed and a mounting table support column for supporting this mounting table are each accommodated in a sealed container. The present invention also relates to a wafer rotation device that rotationally drives this mounting table support column from outside the closed container.

0002

2. Description of the Related Art FIG. 2 shows a conventional wafer rotation apparatus, in which a closed container 1 includes a mounting table 3 on which a wafer 2 is placed, and a mounting table support column 4 that integrally supports this mounting table 3. are accommodated respectively. This mounting table support column 4 is rotatably supported by a bearing 5 within the closed container 1. A magnetic fluid seal 6 is fixed to the lower end of the closed container 1, and the closed container 1 is completely shielded from the outside. A motor 7 is installed outside the closed container 1, and the magnetic fluid seal 6 connects the motor 7 and the mounting table support column 4 in a non-contact state while maintaining the airtightness of the closed container 1. Since the rotational speed of the wafer 2 needs to be controlled with high precision, the motor 7 is controlled with high precision by a control device (not shown), rotates at a predetermined rotational speed, and supports the mounting table via the magnetic fluid seal 6. The pillar 4 is driven to rotate the wafer 2.

0003

However, in the conventional wafer rotation apparatus described above, the mounting table support column 4 and the motor 7 are connected in a non-contact manner by the magnetic fluid seal 6, so that the rotation speed of the motor 7 is The rotation speed of the mounting table support column 4 may not always match. Therefore, even though the motor 7 is controlled to a predetermined rotation speed with high precision, the wafer does not rotate at the predetermined rotation speed.

[0004] In particular, the power transmission force of the magnetic fluid seal 6 decreases over time, so regular maintenance and inspection must be performed. In this maintenance inspection, the closed container 1 is opened and a measuring device such as a tachometer is inserted to measure the rotation speed of the mounting table support column 4, so there is the problem that dust may enter the closed container 1. be. Furthermore, if the inside of the closed container 1 is vacuumed or filled with toxic gas, maintenance and inspection become even more complicated and require much time and effort.

Furthermore, if, for example, a sudden accident occurs in the magnetic fluid seal 6 and the rotational speed of the wafer changes from a predetermined value, the actual rotational speed of the wafer cannot be determined using conventional wafer rotation devices. There was also the problem that people were not aware of this abnormality and ended up producing defective products for unknown reasons. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a wafer rotation device that can detect the rotational speed of a mounting table support column while maintaining the airtightness of a closed container.

[0006]

[Means for Solving the Problems] In order to achieve this object, a wafer rotation apparatus according to the present invention includes a mounting table on which a wafer is placed, a mounting table support column that supports this mounting table, and a mounting table that supports the mounting table. An airtight container that houses the mounting table support column therein, a motor installed outside the airtight container, and a connection between the placement table support column and the motor while maintaining the airtightness of the airtight container. A wafer rotation apparatus comprising: a light transmitting part formed on an outer wall of the sealed container; and a light transmitting part installed outside the sealed container in a position corresponding to the light transmitting part and connecting the light transmitting part through the light transmitting part. The apparatus includes a photoelectric sensor means for detecting the rotation of the mounting table support column, and a control device for controlling the motor based on the detection output of the photoelectric sensor means. In addition, among the above configurations,
Desirable embodiments are as follows.

A pair of the light transmitting parts are formed on the outer wall of the sealed container where a straight line extending through the mounting table support column intersects, and a through hole is formed in the mounting table support column at a position where the straight line passes through. is perforated, and the photoelectric sensor means includes a light emitter that emits a light beam traveling along the straight line and a light receiver that receives the light beam that has passed through the through hole of the mounting table support column.

[0008]

[Operation] The motor rotates the mounting table support column in the closed container via the connecting means, thereby rotating the wafer on the mounting table. The photoelectric sensor means detects the rotation of the mounting table support column through the light transmitting part of the outer wall of the closed container. The control device controls the rotational speed of the motor based on the detection output of the photoelectric sensor means so that the rotational speed of the mounting table support column reaches a desired value. In this way, the rotation speed of the mounting table support column inside the hermetic container is controlled by the motor based on the detection output of the photoelectric sensor means outside the hermetic container.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a wafer rotating apparatus according to the present invention will be described with reference to FIG. 1, in which the same parts as in FIG. 2 are denoted by the same reference numerals. In FIG. 1, a closed container 1 houses a mounting table 3 on which a wafer 2 is placed and a cylindrical or cylindrical mounting table support column 4 that integrally supports the mounting table 3. This mounting table support column 4 is rotatably supported by a bearing 5 within the closed container 1. A magnetic fluid seal 6 is fixed to the lower end of the closed container 1, and the closed container 1 is completely shielded from the outside. A motor 7 is installed outside the closed container 1, and the magnetic fluid seal 6 connects the motor 7 and the mounting table support column 4 in a non-contact state while maintaining the airtightness of the closed container 1.

A through hole 8 is bored in the mounting table support column 4.
This through hole 8 is bored perpendicularly to the rotation center axis of the mounting table support column 4 and deviated from the rotation center axis by a predetermined amount. Through holes 9 and 10 are also formed in the outer wall of the closed container 1 and are opposed to each other, and the positions of these through holes 9 and 10 are determined to be in the same plane as the through hole 8. Each through hole 9, 1
0 has windows 11 and 12 made of a light-transmitting material in the 0 ring 1.
These O-rings 13 seal between the light-transmitting windows 11 and 12 and the closed container 1, and maintain the airtightness of the closed container 1.

A light emitter 14 and a light receiver 15 are disposed in the light transmitting windows 11 and 12, facing each other. Light emitter 14
is the mounting table support column 4 via the light-transmitting window 11 and the through hole 9.
The light receiver 15 receives the light beam that has passed through the through hole 8 of the mounting table support column 4. The light receiver 15 sends a detection output to a control device 16, and the control device 16 controls the rotational speed of the motor 7 based on this detection output.

Next, the operation of this embodiment will be explained. The motor 7 rotates the mounting table support column 4 via the magnetic fluid seal 6, thereby rotating the mounting table 3 fixed to the mounting table support column 4 and rotating the wafer 2 as well. The light beam from the light emitter 14 enters the mounting table support column 4 through the light-transmitting window 11 and the through hole 9, and the through hole 8 of the rotating mounting table support column 4 enters the through holes 9 and 10. When the positions match, the light passes through the through hole 8 of the mounting table support column 4 and enters the light receiver 15 via the through hole 10 and the light-transmitting window 12. The light receiver 15 generates an ON signal when the light beam from the light emitter 14 is incident thereon. Therefore, since the light receiver 14 generates one ON signal for each rotation of the mounting table support column 4, the frequency or period of this ON signal represents the rotation speed of the mounting table support column 4, that is, the wafer 2. .

The control device 16 receives the detection output of the light receiver 14, that is, the ON signal, and controls the rotation speed of the motor 7 based on the frequency of the ON signal so that the rotation speed of the mounting table support column 4 matches a desired value. do. In this way, even if a rotational speed difference due to the magnetic fluid seal 6 exists between the motor 7 and the mounting table support column 4, the motor 7 is always connected to the wafer 2.
The rotation speed of can be controlled to a desired value. In the above embodiment, the output shaft of the motor 7 was directly connected to the magnetic fluid seal 6. However, it is also possible to connect the output of the motor 7 to the magnetic fluid seal 6 via a belt or the like.

The function of the magnetic fluid seal 6 is to transmit the rotation of the motor 7 to the mounting table support column 4 while maintaining the airtightness of the closed container 1. Therefore, in the present invention, other seal structures other than the magnetic fluid seal 6 can be used as long as they have such a function. For example, permanent magnets are attached to the tip of the output shaft of the motor 7 and the tip of the platform support column 4, which face the bottom of the airtight container, and the rotation of the motor 7 is transmitted to the platform support column 4 by the magnetic force of these permanent magnets. You can also.

Furthermore, the ON signal of the light receiver 15 per rotation of the mounting table support column 4 can be doubled. For example, if the through hole 8 is drilled so as to pass through the rotation center axis of the mounting table support column 4, the frequency of the on signal will be doubled, and if two such through holes 8 are drilled, it will be quadrupled. The sensor that measures the rotational speed of the mounting table support column 4 is a reflective type photoelectric sensor that receives reflected light from a reflective section attached to the mounting table support column 4 instead of the transmission type photoelectric sensor shown in the above embodiment. Sensors can also be used. Furthermore, a proximity switch or the like can also be used.

[0016]

As is clear from the above description, the present invention detects the rotation speed of the wafer support column using a photoelectric sensor means and controls the rotation speed of the motor based on this detection output. The rotation speed can be controlled with high precision at all times, and therefore the occurrence of defective wafers can be significantly reduced. Furthermore, since the photoelectric sensor means is installed outside the closed container, maintenance is very easy, and even if the closed container is filled with active gas, it will not be affected by the gas.

[Brief explanation of drawings]

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

FIG. 2 is a sectional view showing a conventional wafer rotation device.

[Explanation of symbols]

1　Airtight container 2 Wafer 3　Placement stand 4 Mounting table support pillar 6 Connecting means (magnetic fluid seal) 7 Motor 9 Light transmission part 11 Light transmission part 10 Light transmission part 12 Light transmission part 14 Photoelectric sensor means 15 Photoelectric sensor means

Claims (2)

[Claims] Claims 1: A mounting table on which a wafer is placed, a mounting table support column that supports the mounting table, a sealed container that accommodates the mounting table and the mounting table support column inside, and an exterior of the sealed container. A wafer rotation apparatus comprising: a motor installed in the airtight container; and a connecting means for connecting the mounting table support column and the motor while maintaining the airtightness of the airtight container, the connecting means being formed on the outer wall of the airtight container. a light transmitting part; a photoelectric sensor means installed outside the closed container corresponding to the light transmitting part positionally and detecting rotation of the mounting table support column through the light transmitting part; A wafer rotation device comprising: a control device that controls the motor based on a detection output. 2. A pair of the light transmitting parts are formed on the outer wall of the sealed container where a straight line extending through the mounting table support pillar intersects, and the light transmitting part is penetrated through the mounting table support pillar at a position where the straight line penetrates. A hole is bored, and the photoelectric sensor means includes a light emitter that emits a light beam traveling along the straight line and a light receiver that receives the light beam that has passed through the through hole of the mounting table support column. The wafer rotation device according to claim 1.