Rotary joint and shaft seal member

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a rotary joint preferably used for supplying abrasive liquid in a polishing apparatus, and a shaft seal member used for the rotary joint for supplying abrasive liquid.

【0002】

[Conventional technology]

A silicon wafer, which is a material for a semiconductor device, is cut out from a silicon single crystal, then wrapped, and further subjected to a polishing process called polishing. In this polishing process, the surfaces of the plurality of wafers held by the plurality of carriers are simultaneously polished by the plurality of carriers revolving between the upper and lower rotating surface plates or rotating at a fixed position.

【0003】

At this time, an abrasive liquid for polishing is supplied between the upper and lower rotary surface plates. Since this abrasive liquid is supplied through the rotating shaft of the rotating surface plate, a rotary joint is required. Fig. 4 shows a conventional example of a rotary joint used to supply abrasive liquid between rotary surface plates for polishing silicon wafers.

【0004】

In this conventional example, the cylindrical shaft body 2 connected to the rotating shaft of the rotating surface plate is rotatably fitted to the inside of the cylindrical cylindrical body 1 which is a fixed shaft via a bearing. The tubular body 1 is provided with a plurality of radial flow paths 3, 3, ... Which also serve as screw-in portions of pipes at predetermined intervals in the axial direction. The inner peripheral surface of the tubular body 1 is provided with circumferential flow paths 4, 4, ... Communicating with the radial flow paths 3, 3, ..., And a peripheral groove 6 into which the annular shaft seal member 5 is fitted. , It is provided on both sides of the radial flow path 4 in the axial direction.

【0005】

On the other hand, the shaft body 2 is provided with a plurality of axial flow paths 7, 7, ... At predetermined intervals in the circumferential direction. One end of the axial flow paths 7, 7, ... Is open to one end surface of the shaft body 2. The other ends of the axial flow paths 7, 7 ... Are opened at a plurality of axial directions on the outer peripheral surface of the shaft body 2 so as to correspond to the circumferential flow paths 4, 4, ... Of the tubular body 1. .. Then, the inner peripheral surface of the tubular body 1 and the outer peripheral surface of the shaft body 2 are sealed by the shaft sealing members 5, 5 ... Fitted in the peripheral grooves 6, 6 ...

【0006】

The abrasive liquid is supplied from the outside of the tubular body 1, which is a fixed shaft, to the circumferential flow paths 4, 4, ... Through the radial flow paths 3, 3, .... The abrasive liquid supplied to the circumferential flow paths 4, 4 ... passes through the corresponding axial flow paths 7, 7 ... Of the shaft body 2 connected to the rotation shaft of the rotary surface plate, and further in the rotation shaft. It is sent to the rotating surface plate through it. A so-called X-seal having an X-shaped cross section is used as the shaft seal members 5, 5 ... To seal between the inner peripheral surface of the tubular body 1 and the outer peripheral surface of the shaft body 2.

【0007】

[Problems to be Solved by the Invention]

By using such a rotary joint, the abrasive liquid for wafer polishing is supplied between the rotary surface plates through the rotary shaft of the rotary surface plate. However, the abrasive liquid for wafer polishing is a corrosive liquid containing a large amount of fine abrasive grains, and has an essential problem that the shaft seal member is easily corroded and worn. In addition, there is a strict restriction that lubricating oil cannot be used to prevent wafer contamination. For these reasons, there is a problem that the life of the shaft seal member is extremely shortened as compared with the case where other fluids are circulated.

【0008】

Further, it is required to use a corrosion resistant resin such as a fluororesin for the cylinder of the rotary joint. This is because it is recommended to refrain from using metal as much as possible in order to prevent metal contamination of the wafer. However, when resin is used for the tubular body of the rotary joint, there is a restriction that the pressing pressure (surface pressure) of the shaft sealing member against the outer peripheral surface of the shaft body cannot be sufficiently increased. This is because when this surface pressure is increased, the heat generated by the shaft seal member becomes remarkable and exceeds the operating limit temperature of the cylinder. Due to the limitation of the surface pressure due to the use of this resin, a so-called co-rotation in which the shaft seal member rotates together with the inner shaft body occurs, which causes a problem that the sealing function cannot be sufficiently exhibited.

【0009】

An object of the present invention is to provide a rotary joint capable of ensuring excellent sealing performance even when the shaft sealing member is used at a low surface pressure. Another object of the present invention is to provide a shaft seal member having a long service life even though it is used for a rotary joint of a polishing device.

【0010】

[Means for solving problems]

In order to achieve the above object, the rotary joint of the present invention is formed by laminating a plurality of annular members in the axial direction, and each annular member is provided with a radial flow path, and the inside of the tubular body. A shaft body rotatably fitted to the shaft body provided with a plurality of axial flow paths that open at different positions in the axial direction of the outer peripheral surface so as to correspond to the plurality of annular members constituting the cylinder body, and the cylinder body. It is provided with a plurality of shaft sealing members that are held between adjacent annular members of the body and that seal between the shaft and the outer peripheral surface of the shaft.

【0011】

In the rotary joint of the present invention, the tubular body is composed of a plurality of annular members laminated in the axial direction, and a plurality of shaft sealing members for sealing between the tubular body and the outer peripheral surface of the shaft body are between adjacent annular members of the tubular body. It is sandwiched between. That is, the plurality of shaft seal members are held between the adjacent annular members by tightening the plurality of annular members constituting the tubular body in the axial direction. Therefore, even when the pressing pressure (surface pressure) of the shaft seal member against the outer peripheral surface of the shaft body is small, the shaft seal member is prevented from rotating together, and an excellent sealing function can be obtained.

【0012】

The tubular body has a peripheral groove that opens to the inner surface side between adjacent annular members, and it is preferable that the shaft seal member is held in the peripheral groove.

【0013】

As the shaft seal member, a rubber seal having a single lip structure in which an annular lip portion inclined in the axial direction is integrally provided on the inner surface side of the annular holding portion is preferable, and in particular, a set of rubber seals is provided for each. It is preferable to use the combination back to back so that the lip portions are inclined to the opposite sides.

【0014】

It is preferable that the shaft body has a smooth and hardened layer on the outer peripheral surface from the viewpoint of suppressing wear of the shaft seal member.

【0015】

The annular member is preferably made of a non-metal, particularly a resin. As described above, the shaft seal member is prevented from rotating together even when the surface pressure is lowered due to the use of the resin.

【0016】

Further, the shaft seal member of the present invention is a shaft seal member used for sealing between the cylinder and the shaft of the rotary joint used for supplying the abrasive liquid between the rotary surface plates of the polishing device, and is annular. This is a rubber seal having a single lip structure in which an annular lip portion inclined in the axial direction is integrally provided on the inner surface side of the holding portion.

【0017】

When the shaft seal member of the present invention is used, high sealing performance is ensured under low surface pressure contact due to the stress concentration at the tip of the lip portion and the autistic action. Further, since the high sealing property prevents the abrasive grains from entering the contact portion, the service life can be significantly extended.

【0018】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially broken elevation view of the rotary joint according to the embodiment of the present invention, FIG. 2 is a plan view of the rotary joint, and FIG. 3 is a vertical sectional view of a shaft seal member used in the rotary joint.

【0019】

The rotary joint according to this embodiment is used in a polishing apparatus for polishing semiconductor wafers. More specifically, it is used for supplying abrasive liquid between rotary surface plates for polishing a wafer, supplying washing water, and evacuating to attract and hold a wafer to the lower rotary surface plate side.

【0020】

As shown in FIGS. 1 and 2, the rotary joint is formed between a cylindrical cylinder 10 which is a fixed shaft and a cylindrical shaft 20 which is rotatably inserted into the cylinder 10. It is equipped with a plurality of shaft sealing members 30, 30 ... for sealing.

【0021】

The tubular body 10 is fixed by fastening the annular members 11, 12 as upper and lower end plates and a plurality of annular members 13, 13 ... Concentrically laminated between the annular members 11, 12 in the axial direction. It is a laminated structure with a plurality of bolts 14 to be used. As will be described in detail later, a fluid such as an abrasive liquid is supplied from the outside of the cylinder 10 to the shaft 20 inside the cylinder 10.

【0022】

The annular members 11, 12 and the annular members 13, 13 ... Are all made of fluororesin. A radial flow path 13a penetrating the annular member 13 in the radial direction is provided in a part of each annular member 13 in the circumferential direction. The inlet portion of the radial flow path 13a also serves as a screwing portion of the pipe. In order to avoid interference of the pipes connected to the plurality of annular members 13, 13 ..., the respective radial flow paths 13a, 13a ... are oriented to the opposite sides alternately.

【0023】

An annular protrusion for positioning is provided on the lower surface of the inner edge portion of the uppermost annular member 11. Further, a notch having an inverted L-shaped cross section is provided on the inner peripheral surface of the lower end portion of the annular member 11 over the entire circumference. This notch is closed from the lower side by the upper surface of the lower annular member 13, so that a peripheral groove 11a for accommodating a set of shaft seal members 30, 30 is provided on the inner peripheral surface of the lower end portion of the annular member 11. Form.

【0024】

As shown in FIG. 3, an annular protrusion 13d for positioning is provided on the lower surface of the inner edge portion of each annular member 13. An annular recess 13e into which an upper positioning annular projection is fitted is provided on the upper surface of the inner edge portion of each annular member 13. A circumferential flow path 13b (see FIG. 1) communicating with the radial flow path 13a is provided on the inner peripheral surface of each annular member 13. The inner peripheral surface of the lower end of each annular member 13 is provided with a notch having an inverted L-shaped cross section over the entire circumference. This notch is closed from the lower side by the lower annular member 13 or the upper surface of the annular member 12, so that the peripheral groove 13c for accommodating one set of shaft seal members 30, 30 is formed at the lower end of the annular member 13. It is formed on the inner peripheral surface of the part.

【0025】

On the upper surface of the inner edge portion of the lowermost annular member 12, an annular recess into which an annular protrusion for positioning formed on the lower surface of the inner edge portion of the upper annular member 13 is fitted is provided.

【0026】

The shaft body 20 is rotatable by bearings 51 and 52 provided inside the upper and lower annular members 11 and 12 in a state where an annular gap is formed inside the tubular body 10 and the inner peripheral surface thereof. It is supported.

【0027】

A plurality of axial flow paths 21, 21 ... Corresponding to the radial flow paths 13a, 13a ... Of the plurality of annular members 13, 13 ... Are provided on the shaft body 20 at predetermined intervals in the circumferential direction. Has been done. The upper ends of the axial flow paths 21, 21 ... Are open to the upper end surfaces of the shaft body 20. The lower ends of the axial flow paths 21, 21 ... Are located at different axial portions of the outer peripheral surface of the shaft body 20 so as to communicate with the annular gap formed inside the plurality of annular members 13, 13 ... It is open.

【0028】

A smooth and hardened layer made of a high alloy such as Hastelloy (trade name) or Stellite (trade name) is formed on the outer peripheral surface of the shaft body 20 excluding the support portions at both ends by thermal spraying or overlay welding.

【0029】

As shown in FIG. 3, the shaft seal member 30 is a rubber seal having a single lip structure in which an annular lip portion 32 is integrally provided on the inner surface side of an annular holding portion 31 having a square cross section. The annular lip portion 32 is inclined in the central axis direction of the holding portion 31. More specifically, in order to improve the sealing property, the holding portion 31 is greatly inclined at an angle of 45 degrees or more, preferably 60 to 80 degrees or more, starting from one end in the axial direction and toward the other end. Moreover, the thickness gradually decreases toward the tip.

【0030】

Two shaft seal members 30 are housed in the peripheral grooves 11a of the annular member 11 and the peripheral grooves 13c, 13c ... Of the annular members 13, 13 ... More specifically, the two shaft seal members 30, 30 are inserted into each peripheral groove in a so-called back-to-back posture in which the respective lip portions 32, 32 are inclined up and down, which are opposite to each other. A backup ring 40 is arranged between the two shaft seal members 30, 30 to prevent deformation of the holding portions 31, 31.

【0031】

Here, the widths of the peripheral grooves 11a and 13c are designed so that the holding portions 31, 31 of the shaft seal members 30, 30 are sufficiently pressurized in the axial direction by tightening the tubular body 10 in the axial direction. On the other hand, the depths of the peripheral grooves 11a and 13c are low enough that only the relatively thin tips of the lip portions 32 and 32 of the shaft seal members 30 and 30 come into surface contact with the outer peripheral surface of the shaft body 20. The portion 32 is designed to be pressed against the outer peripheral surface of the shaft body 20.

【0032】

The functions of the rotary joint according to the present embodiment configured as described above are as follows.

【0033】

The cylinder 10 is a fixed shaft. On the other hand, the shaft body 20 rotates and is connected to the rotating shaft of the lower rotating surface plate arranged above. When polishing a semiconductor wafer between the upper and lower rotating surface plates, the radial flow paths 13a, 13a ... From the plurality of annular members 13, 13 ... Then, the abrasive liquid is supplied to each annular gap between the shaft body 20 and the outer peripheral surface. Each annular gap is sealed on both sides by two shaft sealing members 30, 30 arranged on both sides in the axial direction to form an annular sealed space. As a result, the abrasive liquid supplied to each annular gap flows into the corresponding axial flow paths 21, 21 ... Of the shaft body 20 and rises in the rotating shaft connected above the shaft body 20. It is supplied between the upper and lower rotating surface plates.

【0034】

At this time, the shaft seal members 30 and 30 have a surface seal form in which the tips of the lip portions 32 and 32 elastically come into surface contact with the outer peripheral surface of the shaft body 20 at a low surface pressure, but stress is concentrated on the tip portions. Moreover, when the lip portions 32, 32 receive the supply pressure of the abrasive liquid, the tip portions of the lip portions 32, 32 exhibit a self-closing action on the outer peripheral surface of the shaft body 20. On the other hand, since the holding portions 31, 31 of the shaft seal members 30, 30 are firmly fixed by the axial tightening of the tubular body 10, the shaft seal members 30, 30 have a low surface pressure contact. Co-rotation is prevented. For these reasons, high sealing performance is ensured despite the low surface pressure.

【0035】

Further, in addition to this high sealing property, the smooth hardening layer is formed on the outer peripheral surface of the shaft body 20 to prevent the abrasive grains contained in the abrasive liquid from entering the contact portion. Therefore, the wear of the lip portions 32 and 32 is also remarkably suppressed.

【0036】

Further, since the shaft seal members 30 and 30 are in low surface pressure contact, heat generation is suppressed. Therefore, even though the tubular body 10 is made of resin, thermal deterioration is prevented. By making the cylinder 10 made of a non-metal resin, metal contamination of the wafer is suppressed.

【0037】

When the wafer polishing between the upper and lower rotary surface plates is completed, cleaning water is supplied between the rotary surface plates via the rotary joint. In addition, the upper rotary surface plate is raised to take out the wafer, but at this time, the wafer is attracted and held to the lower rotary surface plate side in order to prevent the wafer from being lifted together with the upper rotary surface plate. To do. In order to hold the suction, the wafer between the rotary surface plates is sucked to the lower rotary surface plate side by performing vacuum exhaust through the rotary joint.

【0038】

Since the two shaft seal members 30, 30 are combined back to back, not only is it effective for pressurization from both sides in the axial direction, but it is also effective for this vacuum suction. Shown.

【0039】

The tubular body 10 formed by laminating a plurality of annular members 11, 12, 13, 13 ... Not only prevents the shaft seal members 30 and 30 from rotating together under low surface pressure contact, but also shaft seals. It has the advantage of simplifying the assembly work of the members 30 and 30, and also facilitating design changes such as changing the number of ports.

【0040】

[Effect of the invention]

As described above, the rotary joint of the present invention comprises a plurality of annular members laminated in the axial direction to form an outer cylinder, and a plurality of shaft seal members for sealing between the outer cylinder and the outer peripheral surface of the inner shaft. By sandwiching the shaft between adjacent annular members of the cylinder, even when the pressing pressure (surface pressure) of the shaft seal member is small, the shaft seal member can be prevented from rotating together, and excellent sealing performance can be ensured.

【0041】

Further, the shaft seal member of the present invention adopts a single lip structure in which an annular lip portion inclined in the axial direction is integrally provided on the inner surface side of the annular holding portion, so that the abrasive liquid for polishing can be used. Despite being used for the rotary joint to be supplied, a long service life can be ensured.

[Simple explanation of drawings]

[Figure 1]

It is a partially broken elevation view of the rotary joint which concerns on embodiment of this invention.

[Figure 2]

It is a plan view of the rotary joint.

[Fig. 3]

It is a vertical sectional view of the shaft seal member used for the rotary joint.

[Fig. 4]

It is a partially broken elevation view of a conventional rotary joint.

[Explanation of symbols]

10 cylinder 11,12,13 Ring member 13a radial flow path 13b Circumferential flow path 13c Circumferential groove 14 bolts 20-axis body 21 Axial flow path 30-axis seal member 31 Reservoir 32 lip part 40 backup ring 51,52 bearings