JP3021923B2 - Rolling bearings for semiconductor manufacturing equipment - Google Patents

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 rolling bearing suitable for use in a corrosive atmosphere.

[0002]

2. Description of the Related Art Bearings used in semiconductor manufacturing equipment are operated under a sealed vacuum where high cleanliness is required. Therefore, lubrication is generally performed by using a layered material such as molybdenum disulfide or the like.
Solid lubricants such as soft metals such as gold, silver and lead, and polymer materials such as PTFE and polyimide are used.

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. Because of the possibility of causing solid lubricants, solid lubricants are required to have particularly low dusting properties in addition to the inherent lubricity and durability.

[0004] In view of the above situation, the present applicant has proposed that at least the surface of a rolling bearing that generates rolling friction or sliding friction has a polytetrafluoroethylene having an average molecular weight of 5000 or less (hereinafter simply referred to as "polytetrafluoroethylene"). , Low molecular weight PTFE). A solid lubricated rolling bearing having a lubricating film formed thereon has already been filed (Japanese Patent Application No. 3-190150). Conventionally, PTFE used as a solid lubricant for bearings has an average molecular weight of 1 ×.
10 ⁵ or more, mainly 1 × 10 ⁶ to 1 × 10 ⁷ , but by forming a lubricating film using low molecular weight PTFE, excellent lubricity, durability, low dust generation, etc. It has been shown in the above application that a lubricating film can be obtained. These effects are due to the fact that low-molecular-weight PTFE is higher than high-molecular-weight PTFE conventionally used as a solid lubricant.
This was due to the extremely low shear strength and excellent transferability. Further, the present applicant filed an application for a rolling bearing for semiconductor manufacturing equipment having a continuous island-shaped solid lubricating film formed thereon. It was shown that dustiness was further improved.

[0005]

By the way, in a semiconductor etching process and a CVD (chemical vapor deposition) coating process,
Since a fluorine-based or chlorine-based reaction gas is used, there is a possibility that a bearing incorporated in the processing apparatus may come into contact with the corrosive reaction gas. For example, in a CVD apparatus, bearings are rarely used in a reaction tank and are mainly used in a buffer tank, so they do not come into direct contact with the reaction gas, but when exchanging wafers between the tanks, In some cases, the reaction gas flows from the reaction tank into the buffer tank and comes into contact with the bearing. Therefore, bearings used in such an atmosphere are required to have particularly high corrosion resistance.

Originally, low-molecular-weight PTFE itself is chemically stable. However, when the lubricating film is repeatedly peeled and transferred, the film thickness sometimes decreases. Corrosive gas and the like may penetrate the coating material and attack the base material. When the lubricating film is distributed in an island shape, the film portion between the islands is originally thin, and corrosive gas or the like easily penetrates from this portion.

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

[0008]

According to the rolling bearing for semiconductor manufacturing equipment of the present invention, at least the surface of the rolling bearing which generates rolling friction or sliding friction is made of polytetrafluoroethylene having an average molecular weight of 5,000 or less. A lubricating film having a base layer made of a titanium-based material below the lubricating film.

[0009]

The titanium-based material has corrosion resistance. Therefore,
The base layer made of a titanium-based material formed under the lubricating film protects the bearing base material from corrosive substances, so that the base material is less likely to be corroded.

[0010]

Embodiments of the present invention will be described below.

FIG. 1 illustrates an embodiment in which the present invention is applied to a deep groove ball bearing. This bearing has inner ring 1, outer ring 2,
Plural rolling elements 3 and rolling elements 3 interposed between inner and outer rings 1 and 2
Are held by bearing parts such as a cage 4 for holding the cylinder at equal intervals. The rolling surfaces of the inner and outer rings 1 and 2 and the surface of the rolling element 3 are respectively provided on the underlayer 1 made of a titanium-based material.
b, 2b, 3b are formed, and a lubricating film 1a, 2a, 3a made of PTFE (low molecular weight PTFE) having an average molecular weight of 5000 or less is formed on the upper layer. Underlayer 1
b, 2b and 3b are Ti or Ti compound
The surface is coated with N, TiC, or the like by ion plating, and has a thickness of 0.5 to 1.0 μm.
m. The underlayers 1b, 2b, 3b formed using these titanium-based materials have corrosion resistance and effectively protect the base material from corrosive substances such as corrosive gases. In FIG. 2A, the underlayers 1b and 2b are formed on the entire outer surfaces of the inner and outer rings 1 and 2, however, as shown in FIG. It may be formed on the surface and the surface of the rolling element 3. In this case, the coating process is not applied to the portions other than the surface by masking. Further, by forming the rolling elements 3 of Si ₃ N ₄ ,
The underlayer 3b of the rolling element 3 can be made unnecessary.

The lubricating films 1a, 2a and 3a are made of a low molecular weight P
TFE (for example, ARC7 manufactured by Acheson Japan)
The film is sprayed and adhered to the film-forming surface from a remote position, and has an average film thickness of about 0.6 μm. Examples of the low molecular weight PTFE film coating method include a dipping method in addition to the above-mentioned spray method. In this embodiment, 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 may be formed on at least the surface of the rolling element 3. Also, in FIG.
The lubricating films 1a and 2a are formed on the entire outer surface of the device, but as shown in FIG. 2b, the portion of the lubricating film, such as the fitting surface, which is not originally required, is not subjected to film treatment by masking, or It is good to remove it before it becomes the final product.

Although the above description has been made with respect to a deep groove ball bearing, the present invention can be widely applied to rolling bearings regardless of the bearing type.

[0014]

As described above, the average molecular weight is 50
By forming an underlayer made of a titanium-based material under the lubricating film made of PTFE of 00 or less, the underlayer effectively protects the bearing base material from corrosive substances, so that the bearing hardly corrodes. . Therefore, the rolling bearing of the present invention has excellent low dust generation, air / vacuum compatibility, and low torque (molybdenum disulfide) without lowering its durability even when used in a corrosive atmosphere. Heat resistance (softening point of lubricating film is 32)
0 ° C. or higher).

The rolling bearing according to the present invention exhibits the same low dust generation as that without the underlayer, but has a slightly improved durability. This is because the surface area substantially increases due to the undulating shape of the underlayer surface, so that the amount and adhesion of the lubricating film are improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a deep groove ball bearing according to an embodiment of the present invention.

[Description of Signs] 1 Inner ring 1a Lubricating film 1b Underlayer 2 Outer ring 2a Lubricating film 2b Underlayer 3 Rolling element 3a Lubricating film 3b Underlayer 4 Cage

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16C 33/62 F16C 33/32 F16C 33/34

Claims (1)

(57) [Claims] A lubricating film made of polytetrafluoroethylene having an average molecular weight of 5,000 or less is formed on at least a surface of a rolling bearing that generates rolling friction or sliding friction. A rolling bearing for semiconductor manufacturing equipment, comprising a base layer made of a titanium-based material as a lower layer.