JPH0621192A - Rolling bearing for semiconductor manufacturing equipment - Google Patents

Abstract

PURPOSE:To provide a rolling bearing for semiconductor manufacturing equipment which is suitable to be used in a corrosive atmosphere. CONSTITUTION:Inner and outer rings 1 and 2 and a rolling element 3 are made of iron-base alloy composed of 30-35% of Ni, 19-23% of Cr and the rest of Fe. Matrix-strengthening is applied to the base material surface layers 1b, 2b and 3b of the above mentioned bearing components by the implantation of Mo or B ions. Lubricating films 1a, 2a and 3a made of crystalline PTFE are formed on the surface layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing used in semiconductor manufacturing equipment, and more particularly to a bearing suitable for use in a corrosive atmosphere.

[0002]

2. Description of the Related Art Since bearings used in semiconductor manufacturing equipment are operated under a sealed vacuum which requires high cleanliness, generally, a layered material such as molybdenum disulfide is used for lubrication thereof.
Solid lubricants such as soft metals such as gold, silver and lead, and polymer materials such as PTFE and polyimide are used.

By the way, in recent years, in the field of semiconductor manufacturing, the line width of circuit patterns has become finer as the degree of integration of semiconductors has increased, and if the abrasion powder of the solid lubricant discharged from the bearing adheres to the pattern, various adverse effects are caused. Because of the possibility of causing it, solid lubricants are required to have particularly low dusting property in addition to the original lubricity and durability.

In view of the above situation, the applicant of the present invention has found that low-molecular-weight polytetrafluoroethylene (hereinafter, for the sake of simplicity, low-molecular weight) is present on at least the surface of rolling bearings that causes rolling friction or sliding friction. Abbreviated as PTFE) to form a lubricating film,
It was shown in Japanese Patent Application No. 3-190150 and the like that a lubricating film excellent in lubricity, durability and low dust generation can be obtained. These effects are due to the fact that low molecular weight PTFE is a high molecular weight PTFE that has been conventionally used as a solid lubricant.
This is due to the fact that the shear strength is remarkably smaller than that of No. 1, and the transferability is excellent. Further, the present applicant has applied for a rolling bearing for a semiconductor manufacturing facility on which a solid lubricating coating having a continuous island-like distribution is formed (Japanese Patent Application No. 3-49946).
In this application, it has been shown that the low particle generation of the bearing is further improved by making the solid lubricating coating of PTFE in an island distribution.

[0005]

By the way, in the semiconductor etching process and the CVD (chemical vapor deposition) film processing process,
Since a silane-based, fluorine-based, or chlorine-based reaction gas is used, the bearing incorporated in the processing apparatus may come into contact with these corrosive reaction gases. For example, in a CVD apparatus, bearings are rarely used in reaction tanks and are mainly used in buffer tanks, so they do not come into direct contact with reaction gas, but when transferring wafers between tanks. The reaction gas may flow from the reaction tank into the buffer tank and come into contact with the bearing. Therefore, the bearings used in such an atmosphere are required to have particularly high corrosion resistance.

Originally, low molecular weight PTFE itself was chemically stable, but the film thickness sometimes decreased when the lubricating film was repeatedly peeled and transferred, and in such a case, it became thin. Corrosive gas and the like may penetrate from the film portion to attack the base material. Further, when the lubricating coating is distributed in an island shape, the coating portion between the islands is originally thin, and corrosive gas or the like easily penetrates from this portion.

Therefore, an object of the present invention is to provide a rolling bearing suitable for use in a semiconductor manufacturing facility, particularly in a corrosive atmosphere.

[0008]

In the present invention, at least the inner ring and the outer ring of the parts constituting the rolling bearing are made of Ni3.
0 to 35%, Cr 19 to 23%, Fe balance iron-based alloy, and at least the surface of the rolling bearing that causes rolling friction or sliding friction is made of crystalline polytetrafluoroethylene. Formed a lubricating film.

Further, among the parts formed of the iron-based alloy, at least the surface layer of the base material which causes rolling friction or sliding friction is matrix-reinforced with Mo or B.

Further, the rolling element is made of ceramic.

[0011]

The iron-based alloy containing 30 to 35% Ni has good corrosion resistance. Therefore, the base material is unlikely to be corroded even in a corrosive atmosphere.

By matrix-strengthening the surface layer of the base material with Mo, the effect of suppressing pitting corrosion is obtained, and the corrosion resistance is further improved.

By matrix-strengthening the surface layer of the base material with B, the effect of suppressing cavitation erosion is obtained, and the corrosion resistance is further improved.

Here, the matrix strengthening means a state in which Mo or B element has entered the matrix structure of the base material surface layer.

[0015]

EXAMPLES Examples of the present invention will be described below.

The embodiment shown in FIG. 1 is an application of the present invention to a deep groove ball bearing. This rolling bearing is composed of bearing components such as an inner ring 1, an outer ring 2, a plurality of rolling elements 3 interposed between the inner and outer rings 1, 2 and a cage 4 for holding the rolling elements 3 at equal intervals around the circumference. The inner and outer rings 1 and 2 and the rolling element 3 are each formed of an iron-based alloy containing Ni of 30 to 35%, Cr of 19 to 23%, and the balance of Fe.
Lubricating films 1a, 2a and 3a made of TFE are formed. These lubricating coatings 1a, 2a, 3a are, for example,
25 low molecular weight PTFE (ARC7 etc. made by Nippon Acheson)
It was sprayed and attached to the film-forming surface from a position distant by cm, and the average film heat is about 0.6 μm.
Unlike the so-called sputtered film, the lubricating film made of crystalline PTFE does not have the PTFE molecules subdivided more than necessary, so that the characteristics such as the original lubricating performance of PTFE are maintained. As a method for coating the crystalline PTFE film, there is an immersion method in addition to the above-mentioned spray method.

In this rolling bearing, the inner / outer rings 1 and 2 and the rolling element 3 have Ni of 30 to 35%, Cr of 19 to 23%, and Fe.
Since it is made up of the rest of the iron-based alloy, it has good corrosion resistance, does not corrode even in an atmosphere using a reactive gas such as silane, and has its original properties such as durability and low dust generation for a long time. Exerts over. In addition, as PTFE, by Dux AR (manufactured by DuPont), MP1200, MP130
The same effect can be obtained by using 0 (both manufactured by Mitsui Fluorochemical Co., Ltd.).

By the way, in an atmosphere using chlorine gas, fluorine gas, or a mixed gas thereof, which is more reactive than silane, stronger corrosion resistance may be required. The rolling bearing shown in FIG. 2 has further improved corrosion resistance in consideration of such a case.
This rolling bearing has M on the inner and outer rings 1 and 2 and the base material surface layers 1b, 2b and 3b of the rolling element 3 which are formed of the iron-based alloy.
This is the result of ion implantation of o or B element. The base material surface layers 1b, 2b, 3b are matrix-reinforced with Mo or B element to form a mixed layer of the base material element and Mo or B element. However, the matrix-reinforced base material surface layer and the base material do not have a clear interface as shown in the figure. As is well known, the ion implantation method is a method of accelerating to a constant energy by implanting an element to be implanted and implanting it on the surface of the base material, but unlike the CVD method or the like, it is essentially a non-thermal equilibrium process and is low temperature. It is characterized in that it can be treated and that the implanted ions enter the matrix structure of the base material to obtain strong adhesion. For example, when Mo is ion-implanted, the effect of suppressing pitting corrosion is obtained, and the corrosion resistance is further improved. When B is ion-implanted, the effect of suppressing cavitation erosion is obtained, and the corrosion resistance is further improved. Mo or B is used as the base material surface layer 1b, 2b, 3
When ion-implanted into b and modified to a depth of 0.3 μm, the rusting time is 2
It has been confirmed by experiments that the delay is more than double. The means for strengthening the matrix is not limited to the ion implantation method, and for example, Mo or B may be contained at the time of steelmaking of the base material.

3, 4, and 5 show the results of a dusting test conducted on the bearing having the structure shown in FIG. Figure 3 is AR
C7 (average molecular weight 3000), Fig. 4 shows Bidax AR
(Average molecular weight 5000), FIG. 5 shows the results when a lubricating coating was formed using MP1200 (average molecular weight 200,000). The test conditions are: rotation speed: 50 rpm, thrust load: 1 kgf, and vacuum degree: 10 ⁻⁷ Torr. All show good low dust generation. When a lubricating coating was formed using MP1300 (average molecular weight 300,000), the same low dusting property as that of MP1200 shown in FIG. 5 was exhibited.

In the embodiment described above, the lubricating film is formed on the rolling surfaces of the inner and outer races 1 and 2 and the surface of the rolling element 3, but the lubricating film is formed on at least the surface of the rolling element 3. Good. Further, in FIGS. 1a and 2a, the lubricating coatings 1a and 2a are formed on the entire outer surfaces of the inner and outer races 1 and 2. However, as shown in FIGS. 1b and 2b, the lubricating coatings such as the mating surfaces are originally formed. Unnecessary portions should not be subjected to a film treatment by masking, or may be removed before the final product. Further, the matrix reinforcement of the base material surface layer may be performed at least on the rolling surfaces of the inner and outer races 1, 2. Further, when the rolling elements 3 are made of ceramic, the corrosion resistance of the bearing is further improved. Further, the type of bearing is not limited to the deep groove ball bearing as shown in FIGS. 1 and 2, but can be widely applied to rolling bearings in general.

[0021]

As described above, in the rolling bearing of the present invention, at least the inner ring and the outer ring of the components constituting the bearing are made of an iron-based alloy of Ni 30 to 35%, Cr 19 to 23%, and the balance of Fe. In addition, since a lubricating film made of crystalline polytetrafluoroethylene was formed on at least the surface that causes rolling friction or sliding friction among the components constituting this bearing, it was used in a corrosive atmosphere. Corrosion hardly occurs, excellent low dust generation, compatibility with atmosphere and vacuum, low torque (similar to sputtering film of molybdenum disulfide), heat resistance (lubrication film has softening point of 320 ^° C or more) And so on.

[Brief description of drawings]

FIG. 1 is a cross-sectional view (a) showing a deep groove ball bearing according to an embodiment of the present invention, and a cross-sectional view (FIG. B) showing a state in which a lubricating film such as a fitting surface is removed.

FIG. 2 is a cross-sectional view (a) showing a deep groove ball bearing according to another embodiment of the present invention, and a cross-sectional view (FIG. B) showing a state in which a lubricating film on the fitting surface and the like has been removed.

FIG. 3 is a diagram showing a result of a dusting test.

FIG. 4 is a diagram showing a result of a dusting test.

FIG. 5 is a diagram showing a result of a dusting test.

[Explanation of symbols]

 1 Inner ring 1a Lubrication film 1b Base material surface layer 2 Outer ring 2a Lubrication film 2b Base material surface layer 3 Rolling element 3a Lubrication film 3b Base material surface layer 4 Cage

Claims (4)

[Claims] 1. At least an inner ring and an outer ring of a component constituting a rolling bearing have Ni of 30 to 35% and Cr of 19 to 23.
%, The balance of Fe is formed of an iron-based alloy, and a lubricating film made of crystalline polytetrafluoroethylene is formed on the surface of at least rolling friction or sliding friction of the components constituting the rolling bearing. A characteristic rolling bearing for semiconductor manufacturing equipment. 2. A base material surface layer which causes at least rolling friction or sliding friction among the parts formed of the iron-based alloy,
The rolling bearing for semiconductor manufacturing equipment according to claim 1, which is matrix-reinforced with Mo. 3. A base material surface layer which causes at least rolling friction or sliding friction among the parts formed of the iron-based alloy,
The rolling bearing for semiconductor manufacturing equipment according to claim 1, which is matrix-reinforced by B. 4. The rolling bearing for semiconductor manufacturing equipment according to claim 1, 2, 3 or 4, wherein the rolling elements are formed of ceramics.