JPH01275914A - Driving mechanism in vacuum - Google Patents

Abstract

PURPOSE:To reduce an amount of dust generation by composing a bearing with balls and rollers made of ceramics and inner and outer rings made of stainless steel. CONSTITUTION:Inner and outer rings 2, 3 of a bearing are made of stainless steel sus440c or the like and balls 1 are made of ceramics Si3N4 or the like. The ceramics is excellent in high temperature stability and abrasion resistance. An amount of dust generation in the bearing in a vacuum environment can then be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vacuum drive mechanism, and particularly to a vacuum drive mechanism using a bearing that generates little dust.

[Conventional technology] In the field of semiconductor device manufacturing using vacuum technology,
A vacuum drive mechanism is used as a means of transporting devices, etc., and the bearings used in conventional vacuum drive systems are made of 5us440c, 5us3
Made of stainless steel such as 04.5us316 or these stainless steels with Ni ion brating, Ag plating, A
Those with surface treatments such as U coating were used. Solid lubricants such as Mo 32 are also often used in these bearings.

In these bearings, the inner and outer rings are made of stainless steel, and the balls and rollers are often surface-treated.

In this way, oil cannot be used as a lubricant for bearings used in vacuum drive systems, so surface treatment is applied to the component balls, inner rings, and outer rings to improve lubricity and
Improved palm abrasion resistance and durability. Apart from this, solid lubricants were also often used. - [Problems to be Solved by the Invention] Bearings used in conventional vacuum drive systems have the problem of generating a large amount of dust during drive, contaminating the inside of the vacuum device.

The present invention aims to solve the above-mentioned problems with conventional devices by significantly reducing the amount of dust generated during operation in a vacuum, thereby minimizing contamination within the vacuum device. be.

In other words, the vacuum drive mechanism using conventional bearings is
However, with the present invention,
By partially or completely adopting bearings that generate less dust in the vacuum drive mechanism, the total amount of dust generated can be significantly reduced.

[Means for Solving the Problems] The vacuum drive R1f8 of the present invention has ceramic ball bearings that generate less dust attached to some or all of the sliding parts. The material of the ceramic ball is S.
They are i3N4, Si3N4+, and Ml 203, and the material of the inner and outer rings is 5us440c.

[Function] Ceramic (S13N4), which is the material of the ball, is a type of nitride ceramic that has excellent chemical stability at high temperatures, and is suitable as a material for vacuum parts. Also 51
3N4 has a high hardness of 9 or higher and has excellent wear resistance.

Also, unlike Ag-metsuki balls, it does not seize at high temperatures.

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a ceramic ball bearing used in a vacuum drive mechanism according to the present invention. The material of ball 1 of this bearing is Si3N4 or Si N +AJ!
The materials of the inner ring 2 and outer ring 3 of this bearing, which are made of ceramic such as 203, are 5us440c and 5us30.
It is made of stainless steel such as 4.5us316.

First, a method for measuring the amount of dust generated from a single bearing will be explained with reference to FIGS. 2 and 3. Figure 2 shows
A vacuum component 6 is shown in which a ceramic ball bearing 4 to be tested is incorporated into a cylindrical gauging 5. This component is configured to support the ball bearing 4 via the bellows 7 and to apply a load in the radial direction to the outer ring 8 of the bearing. The ball bearing 4 has a cylindrical shape, and an inner ring 11 of the bearing is rotated by a rotation introduction terminal 10 which is rotated by a motor 9 arranged on the upper part of the gauging 5.

The vacuum component 6 is mounted in the vacuum chamber 13 with the opening 12 of its cylindrical gauging 5 facing downward, as shown in FIG. Monitoring window 14 and pressure sensor 15
A vacuum chamber 13 having a vacuum chamber 13 is continuously evacuated via a partition pulp 16 by a turbomolecular pump 17 and a rotary pump 18. A vent valve 19 is installed in this vacuum chamber via a filter 20 to bring the inside to atmospheric pressure.

Inside the vacuum chamber 13, three 6-inch diameter wafers are arranged horizontally to receive dust. The wafer placed directly below the X space component 1 is C1, and the wafers placed on both sides thereof are S1 and S2.

The pressure during sampling was approximately 0°I so that the dust would fall straight down without being affected by Brownian motion.
It was set to Torr. 0. At a pressure of ITorr, 0
．． The horizontal migration speed due to Brownian motion of a 3 μm particle is:
This is several tenths of the gravitational sedimentation rate.

Therefore, almost all of the dust of 0.3 μm or more falls onto the wafer C directly below. That is, Sl ,3
The difference between 2 and C can approximate the net amount of dust generated by component 1.

This invention is a bearing for introducing rotation into a vacuum chamber.
It is also possible to use it as a rotational drive bearing in a vacuum chamber.

Furthermore, as a modified embodiment, various roller bearings can be used in addition to various ball bearings. Furthermore, the drive direction is not limited to the rotational direction, but can also be applied in a linear direction.

In addition, there is a wide possibility that this invention can be used as a component in a certain vacuum-utilizing equipment 9 For example, in cases where dust contamination does not affect the product yield, such as in a vacuum chamber or a semiconductor device (or wafer) 1. Dust can be significantly reduced by using a vacuum drive mechanism that partially or fully employs the bearing according to the present invention. Specific applications include rotation introduction terminals, planetary jigs for deposition, belt conveyance systems, and vacuum robots.

Furthermore, in the case of an analyzer that uses a vacuum, dust generated from sliding parts may adhere to the analyzer, making it difficult to obtain accurate results. However, even in such a case, by utilizing the present invention, the amount of dust generated can be suppressed, and therefore improvements can be made.

FIG. 4 shows an embodiment using a belt conveyance system. There are roughly three sliding parts of this component in vacuum: a bearing, a bevel gear 22 driven by a motor 21, and between a pulley 23 and a belt 24. Particularly in such components, since bearings are frequently used, the effects of the present invention are considered to be significant.

In addition to 5us440c, the materials used for the inner and outer rings and retainer of the ceramic ball bearings include 5us3.
04 or 5us316 may also be used. Furthermore, by coating SUS, which is the constituent material of the inner and outer rings, with TiN or CrN to increase the hardness, it is possible to lower the palm abrasion rate and reduce the amount of dust generated.

[Effects of the invention] Ceramic ball bearings in vacuum (10 Pa),
For comparison, Figure 5 shows the amount of dust generated when a conventional vacuum ball bearing, Ag-coated ball bearing, is rotated. In this figure, the horizontal axis represents the total number of rotations (time x rotation speed). , and the vertical axis is the increase in the number of dust particles with a diameter of 0.3 μm or more generated from rotating bearings.

The load on the bearing is 4°6 kof in the radial direction. In addition, the rotation speed of the ceramic ball is 43rpl.
There are two types of Ag balls: 43 rpH and 129 rpI.

It can be seen that the amount of death generated from the bearing is proportional to the total number of rotations. It can be seen that ceramic ball bearings generate about 1/4 the amount of dust at the same total rotation speed.

Therefore, vacuum drive mechanisms that make extensive use of bearings can exhibit the dust reduction effect of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a ceramic ball bearing used in a vacuum drive a-ellipse according to the present invention, and Fig. 2 shows a vacuum component used to measure the amount of dust generated by the ceramic ball bearing according to the present invention and a conventional ball bearing. 3 is a schematic diagram of a dust measuring device equipped with the components shown in FIG. 2, and FIG. 4 is a schematic diagram showing an embodiment using a belt conveying system as the vacuum drive R of the present invention. , and Figure 5 shows a ceramic ball bearing and a conventional vacuum ball bearing A for comparison.
It is a graph showing the amount of dust generated when rotating the G ball bearing. In the diagram, 1...Ball, 2...Inner ring, 3...Outer ring 2nd
Figure 3 Figure 4 Figure 5 Total rotation speed

Claims (1)

[Claims] 1. A bearing used in a vacuum drive mechanism of a vacuum device, in which the balls or rollers of the bearing are made of ceramic, and the inner and outer rings of the bearing are made of stainless steel. 2. The ceramic material is Si_3N_4 or Si_3N
A vacuum drive mechanism using the bearing according to claim 1, which is _4+Al_2O_3. 3. TiN or C on the surfaces of the stainless steel inner and outer rings
A vacuum drive mechanism using the bearing according to claim 1 or 2, which is coated with rN to increase hardness.