JP2001223414A - Bearing structure of fan used for gas laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing structure wherein difference of dimension in the rotating shaft direction which is caused by expansion is absorbed and a rotation bearing is not rotated (slipped) in the rotating direction of a fan to a bearing holding part, in a bearing structure using the rotation bearing of the fan of a gas laser device. SOLUTION: This bearing structure is used for the fan of the gas laser device. In the bearing structure of one end, the rotation bearing (4) attached to a rotating shaft (3) is fixed so as not to move in both the rotating shaft direction and the rotating direction. In the bearing structure of the other end, the rotation bearing (4) attached to the rotating shaft (3) is held so as to be movable in the shaft direction of the rotating shaft (3) to the bearing holding part (5). In the structure of the other end, a rotation regulating member (6) to the bearing holding part (5) of the rotation bearing (4) is arranged between the rotation bearing (4) and the bearing holding part (5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for a fan used in a gas laser device. In particular, it relates to a bearing structure of a cross flow fan for circulating gas between electrodes of an ArF excimer laser device or a fluorine laser device.
Further, the present invention relates to a bearing structure of a cross flow fan used under conditions of high speed rotation and high pressure.

[0002]

2. Description of the Related Art With miniaturization and high integration of semiconductor integrated circuits, there is a demand for improvement in resolution of a projection exposure apparatus. For this reason, the wavelength of exposure light emitted from an exposure light source has been shortened, and an excimer laser device that emits light having a wavelength shorter than the wavelength of a conventional mercury lamp light has been adopted as a light source for semiconductor lithography. Has begun. In particular, an ArF excimer laser device and a fluorine laser device are expected.

[0003] In an excimer laser device, a laser gas such as fluorine (F ₂ ) or argon (Ar) is sealed in a laser chamber at several hundred kPa. A pair of main discharge electrodes are provided inside the laser chamber, the main discharge electrodes extending in the laser optical axis direction and facing each other at a predetermined interval. By generating a discharge by applying a fast rising high voltage pulse between the main discharge electrodes, a laser gas as a laser medium is excited.

In order to avoid the problem of chromatic aberration in the output mirror and the projection optical system of the exposure apparatus before and after the laser chamber, the spectral width of the laser beam is narrowed so as to realize the central wavelength stabilization. A narrowing optical system is arranged, and the output mirror and the narrowing optical system constitute a laser resonator. Light that is excited by the laser gas and emitted from the chamber is amplified by the laser resonator and extracted as laser light from the output mirror of the laser resonator.

In order to efficiently generate laser light, it is necessary to generate uniform discharge between the main discharge electrodes.
In order to generate a uniform discharge in a high-pressure gas atmosphere of several hundred kPa, the laser gas existing in the main discharge space between the main discharge electrodes before the start of the main discharge is usually set by the preliminary ionization means provided near the main discharge electrode. It is common to pre-ionize.

Here, in an excimer laser device used as a light source for exposure, high repetition operation at several kHz of discharge has been demanded in order to increase throughput. However, after the occurrence of the main discharge, thermal disturbance or acoustic disturbance (shock wave or the like) occurs in the main discharge space, and if this state is maintained, the next main discharge becomes unstable. Then, due to such unstable discharge, arc discharge occurs between the main electrodes,
The laser output also becomes unstable.

In order to avoid such a problem, after one discharge is completed, before the next discharge occurs, a so-called replacement operation for discharging the residual gas between the main discharge electrodes and disposing a new gas is required. become. Specifically, a fan is provided in the laser chamber to circulate the laser gas in the chamber at a high speed.

FIG. 3 is a schematic diagram showing the inside of a conventional laser chamber. The figure is for explaining the gas circulation,
Preliminary ionization means and heat exchange means for cooling the laser gas heated by the heat generated by the discharge are omitted. Chamber body 1 with upper and front and back openings
An upper plate 1A is hermetically attached to the upper part of the upper case, and a side plate A and a side plate B are hermetically attached to the front and rear of the chamber body 1.
Thus, a laser chamber is formed. The side plates A and B are provided with windows (not shown) through which laser light passes. A cross flow fan 2 (hereinafter also referred to as a fan) is provided inside the chamber as a means for circulating the laser gas at a high speed. Both ends of the cross flow fan 2 have protrusions substantially coincident with the central axis of the fan, and the protrusions are rotatably held as rotary shafts 20 by a rotary bearing 4 (hereinafter also referred to as bearings). Further, the rotary bearing 4 is held by a bearing holding portion 5 (hereinafter, also referred to as a housing). Note that a pair of main discharge electrodes 3 is provided in the upper space of the cross flow fan 2.

Here, the cross flow fan 2 expands and contracts in the rotation axis direction due to a temperature change in the chamber. Therefore, in a bearing structure using the rotating bearing 4, it is necessary to adopt a structure capable of absorbing a dimensional change in the rotating shaft direction due to such expansion and contraction. In general, the structure is such that the outer ring of the rotary bearing can slide in the axial direction on the inner surface of the bearing holding portion with which the rotating bearing abuts.

A bearing at one end (right side in the drawing) of the fan ends is fixed to the bearing holder 5 so that the rotary bearing 4 does not move in the axial direction. This is called a fixed end. The other end, that is, the other end (the left side in the figure) of the bearing portion is held only by fitting the rotary bearing 4 to the bearing holding portion 5. This is called the free end. FIG. 4 is an enlarged view of the structure of the free end. The rotary bearing 4 has a bearing structure in which an outer ring 41 and an inner ring 42 rotate relatively through a plurality of balls 43.

As shown in FIG. 3, the structure of the fixed end is such that the bearing 4 is fitted to the rotating shaft 20 and the inner ring 42 of the bearing is pushed in until it hits the portion 30 where the system of the rotating shaft 20 is thick. Although two bearings 4 are used in the figure, the number can be appropriately selected in consideration of the force applied to the bearing 4 from the rotating shaft 20 during rotation. A screw portion 32 is provided in a portion of the rotating shaft 20 that does not fit with the bearing 4, and a holding screw 31 screwed into the screw portion 32 is tightened. The inner ring of the bearing 4 is sandwiched between a holding screw 31 and a portion 30 having a thicker rotating shaft system, and is fixed to the rotating shaft 20. On the other hand, the outer ring 41 of the bearing is fitted into the bearing holding portion 5 and pushed until it hits a portion where the diameter of the housing 5 is small (a portion 30 where the diameter of the rotating shaft is large). A screw portion 32 is provided on a part of both surfaces of the housing 5 (a portion that does not fit with the bearing 4 when the bearing 4 is pushed in), and like the inner ring, the housing 5 is fixed to the housing 5 by a holding screw 31 screwed into this screw portion. Fixed.

On the other hand, the structure of the free end is shown in an enlarged scale in FIG. 4, but the inner ring 42 of the bearing 4 is fixed to the rotating shaft 20 by a screw holder 31 and a screw portion 32, similarly to the fixed end.
The outer ring 41 is merely fitted into the housing 5 and is not completely fixed. No thread is provided on both sides of the housing 5 at the free end. When the fan 2 rotates, the inner ring 42 of the rotary bearing 4 rotates, but the outer ring 41 of the rotary bearing 4 is held by the frictional force with the inner surface of the bearing holding portion 5. When the rotating shaft 20 expands in the rotating shaft direction, the outer ring 41 of the rotating bearing 4 slides on the inner surface of the bearing holding portion 5 in the axial direction to absorb a dimensional change due to the expansion.

Here, the outer ring 41 of the rotary bearing 4 on the free end side.
However, there is a case where the bearing slips with respect to the bearing holding portion 5 in the rotational direction. The reasons are as follows. First, to circulate the laser gas in the chamber at a high speed, the fan 2 must be rotated at a high speed. The number of discharges requested k
In order to perform high repetition at Hz, the fan 2 must rotate at 2000 to 4000 rpm, depending on the gas flow path to be formed. On the other hand, as mentioned above,
The laser gas is sealed in the chamber at a pressure of several hundred kPa. Further, since the interval between the discharge electrodes for flowing the wind is narrow, the fan 2 operates under the condition of high head and low flow rate. Therefore, when the fan rotates twice, the fluid action causes
An extremely large load is applied to the rotating shaft 20. Further, since the shaft load applied to this shaft is always applied to the shaft in one direction, the rotating bearing 4 is also always pressed in one direction, and the inner ring 42 of the bearing 4 via the rotating body (ball) 43. And the outer ring 41 has a large frictional force.

When the bearing holding portion 5 is mounted so as to be offset from the rotary shaft 20, the frictional force between the inner ring 42 and the outer ring 41 of the bearing 4 increases as described above. It is difficult to attach the bearing holding portion 5 so that there is no axis deviation with respect to the rotating shaft 20 in terms of assembly accuracy. Further, since the grease sealed between the inner ring 42 and the outer ring 41 of the bearing 4 is filled with a gas containing fluorine in the chamber, fluorine-based grease having a high molecular weight is used to impart corrosion resistance. used. Such grease has a high viscosity, and the outer ring 41 is easily taken by the rotation of the inner ring 42. When the frictional force between the inner ring 42 and the outer ring 41 of the bearing 4 and the force due to the high viscosity of the grease are greater than the frictional force between the bearing outer ring 41 and the inner surface of the bearing holding portion 5 (housing), the bearing outer ring 41 becomes It slips in the rotational direction with respect to the bearing holding portion 5 (housing).

When such a slip occurs, vibration occurs between the bearing outer race 41 and the housing 5.
The vibration is transmitted to the entire chamber, causing a shift of the optical axis of the oscillating laser light and a fluctuation of the wavelength. Further, heat is generated between the bearing outer ring 41 and the housing 5. Moreover,
The life of the bearing 4 is shortened.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bearing structure using a rotary bearing of a fan of a gas laser device, which absorbs a dimensional difference in a rotary shaft direction due to expansion and has a rotary bearing. An object of the present invention is to provide a bearing structure that does not rotate (slip) in the rotation direction of a fan for a bearing holding portion.

[0017]

In order to solve the above problems, a bearing structure of a fan used in a gas laser device according to the present invention is characterized in that a bearing structure at one end includes an outer ring of a rotating bearing mounted on a rotating shaft in a rotating shaft direction. The bearing structure at the other end is a structure in which the rotating bearing attached to the rotating shaft is held movably in the axial direction of the rotating shaft with respect to the bearing holding portion. . The structure of the other end is further characterized in that a rotation regulating member for the bearing holding portion of the rotating bearing outer ring is provided between the rotating bearing and the bearing holding portion. Here, one end is the above-mentioned fixed end, and the other end is the above-mentioned free end.

Further, the bearing structure at the other end is not held by a bearing holding portion, but is held by a frame member for housing the rotary bearing, and has a bearing holding portion for housing the frame member.
A rotation regulating member for the bearing holding portion of the frame member is provided between the frame member and the bearing holding portion. further,
The rotation restricting member may be structured to have a relationship between a key and a key groove. Furthermore, an elastic body is provided on the other end structure for applying a pressure to a rotary bearing attached to a rotary shaft in an axial direction.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a bearing structure according to the present invention.
FIG. 2 is a schematic configuration diagram of the entire laser chamber for explaining the first embodiment, and FIG. 2 is a cross-sectional view along AA ′ of FIG. One end (hereinafter also referred to as a fixed end) side is similar to the structure shown in the conventional example, and has a structure for fixing the rotary bearing 4. The bearing outer ring 41 is shown in FIG.
However, the outer ring fixing member 44 is fixed to the bearing holding portion 5 (housing) so as not to move in both the rotation axis direction and the rotation direction. The bearing inner ring 42 is provided with a screw portion at a portion of the inner ring fixing member 45, for example, a portion of the rotating shaft that does not fit with the bearing inner ring 42, and the screw portion is fixed to the rotating shaft 20 with a screw. In addition, this fixing method is not particularly limited.

At the other end (hereinafter, also referred to as a free end), the inner ring 42 of the bearing 4 is fixed to the rotating shaft 20 similarly to the fixed end. Between the outer ring 41 of the bearing and the housing 5, a rotation restricting member 6 for restricting only the movement of the bearing 4 in the rotational direction is provided. The rotation restricting member (hereinafter, also simply referred to as a restricting member) is formed by, for example, fitting a rectangular parallelepiped projection to an outer ring 41 of a bearing, and
Is provided with a groove 60 having the same width as the protrusion and extending in the rotation axis direction, and is formed by a structure in which the groove and the protrusion are fitted.

With such a structure, with respect to expansion in the direction of the rotation axis, the regulating member 6 moves along the groove 60 so that the dimensional difference can be favorably absorbed. Further, the bearing outer ring 41 does not rotate with respect to the housing 5 due to the regulating member 6. Therefore, the slip rotation of the bearing outer ring 41 shown in the above problem can be favorably prevented.

Next, a second embodiment of the present invention will be described with reference to FIG. The figure shows only the free end side of the cross flow fan for convenience, and the structure at the fixed end side is the same as the structure described in the first embodiment. Frame member 5 at the free end
0 and a bearing holder 5 are provided. The bearing 4 is housed in the frame member 50. The bearing inner ring 42 is fixed to the rotating shaft 20 by the inner ring fixing member 31, and the bearing outer ring 41 is fixed to the frame member 50 by the outer ring fixing member 44.
, So as not to move in both the rotation axis direction and the rotation direction.

The frame member 50 is housed in the bearing holder 5. Between the frame member 50 and the bearing holding portion 5, a regulating member 6 for regulating only the rotational movement of the frame member 50 is provided as in the first embodiment. That is, a rectangular parallelepiped projection is provided on the frame member 50, and a groove 60 having the same width as the projection and extending in the rotation axis direction is provided on the bearing holder 5. The structure in which the groove 60 and the projection are fitted together constitutes the regulating member 6. In this structure, the frame member 5 is prevented from expanding in the rotation axis direction.
0 moves with respect to the bearing holding part 5 to absorb the dimensional difference. However, the frame member 50 does not rotate with respect to the bearing holder 5 due to the restriction member 6. Therefore, the bearing outer ring 4
1 can be prevented from slipping.

That is, the relationship between the rotary bearing and the bearing holding portion in the first embodiment is provided in the frame member and the bearing holding portion in the second embodiment, and the rotary bearing and the frame member are also arranged in the direction of the rotary shaft. It does not move in the rotation direction.
With such a configuration, it is not necessary to perform keyway processing on the outer ring of the bearing, and a commercially available bearing can be used. For this reason, there is an advantage in that it is easier and lower cost to form a groove in the housing, which is a machined product, as compared with processing of a bearing.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 also shows only the free end side of the cross flow fan similarly to FIG. 5, and the fixed end side is the same as the structure shown in the first embodiment. The free end side is basically the same as in the second embodiment. However, the structure for restricting the rotation of the frame member 50 is different. That is, the groove 6 extending in the rotation axis direction is formed in the frame member 50.
0 is provided, and a pin 23 is hit from the outside of the bearing holding portion 5 so as to fit into the groove 60. Even with such a structure, the frame member 50 moves with respect to the bearing holder 5 with respect to expansion in the rotation axis direction, and the frame member 50 does not rotate with respect to the bearing holder 5. Therefore, slip rotation of the bearing outer ring 41 can be prevented. However, it is different in that the member that regulates rotation is a pin, and receives a force in the rotational direction by point contact.

Next, a fourth embodiment of the present invention will be described with reference to FIG. This structure is characterized in that a wave washer 24 is provided on the free end side to apply a pressure to the bearing. If the bearing 4 is not pre-pressed, the balls 43 meander or slide between the inner ring 42 and the outer ring 41 of the bearing 4. Vibration is generated by meandering, and the vibration is transmitted, and the entire chamber vibrates. The vibration of the chamber causes a shift of the optical axis of the oscillating laser light and a fluctuation of the wavelength. In addition, the sliding causes the bearing to generate heat and wear, resulting in a short life. FIG. 7 shows an elastic body between the frame member 50 and the bearing support plate 70 in the free end side structure shown in FIG. 5 so that a force in the left direction (arrow shown) is always applied to the frame member 50. 24 (in this case, a wave washer). Since the frame member 50 is pushed leftward, the bearing outer ring 41 on the free end side is also pushed leftward, and the bearing inner ring 42 is also pushed leftward via the ball 43. When the bearing inner ring 42 is pushed to the left, the rotating shaft 20 of the fan is pulled to the left. When the rotation shaft 20 of the fan is pulled to the left, the bearing inner ring 42 at the fixed end is pulled to the left, and the bearing outer ring 41 is also pulled to the left via the ball 43. Since the movement of the bearing outer ring 41 is restricted by the stopper of the housing, the bearing outer ring 41 maintains the preload. In this way, uniform pressurization can be applied to both the free end side and the fixed end side bearings. However, when the rotating shaft 20 expands in the axial direction, the expansion and contraction force is greater than the elastic force of the wave washer 24, so that the free end moves in the axial direction and absorbs the dimensional difference. However, the wave washer 24
Is designed and selected so that pressure can be applied to the bearing 4 even when the rotation shaft expands and the distance between the frame member 50 and the bearing support plate 70 is widened.

The bearing structure of the fan used in the gas laser of the present invention has the following effects. . For the rotating bearing structure that holds one end as the fixed end and the other as the free end and holds both ends of the fan, a regulating member that regulates the rotation of the rotating bearing outer ring is provided between the rotating bearing and the bearing holding portion on the free end side. Provided. Therefore, even if high-speed rotation is performed in a state where a very large axial load is applied by the fluid action, the rotary bearing does not rotate with respect to the bearing holding portion. . On the free end side, a frame member for housing the rotary bearing and a bearing holding portion for housing the frame member are provided, and a rotation regulating member for restricting rotation of the frame member is provided between the frame member and the bearing holding portion. Provide. In addition to preventing the rotational movement of the rotary bearing with respect to the bearing holding portion, a commercially available rotary bearing can be used, and processing of the regulating member is facilitated, thereby reducing costs. . The restricting member has a key-keyway relationship. Since a rotational force against the bearing holding portion of the rotary bearing is received by surface contact, it is structurally strong. . On the free end side, an elastic body that applies preload to the rotating bearing attached to the rotating shaft is provided, so that the meandering of the ball of the rotating bearing,
Slip can be prevented. Accordingly, it is possible to prevent the vibration of the chamber caused by the vibration of the rotating bearing due to the meandering of the ball, and the shortening of the service life of the rotating bearing caused by the heat generation and wear caused by the sliding of the ball.

[Brief description of the drawings]

FIG. 1 shows the overall schematic structure of a laser device.

FIG. 2 shows an enlarged view of the bearing structure of the present invention.

FIG. 3 shows an overall schematic view of a conventional laser device.

FIG. 4 shows a conventional bearing structure.

FIG. 5 shows a second embodiment of the bearing structure of the present invention.

FIG. 6 shows a third embodiment of the bearing structure of the present invention.

FIG. 7 shows a fourth embodiment of the bearing structure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chamber main body 2 Cross flow fan 3 Electrode 4 Rotation bearing (bearing) 5 Bearing holding part (housing) 6 Rotation restriction member 20 Rotation shaft 23 Pin 24 Wave washer 31 Inner ring fixing member 41 Bearing outer ring 42 Bearing inner ring 43 Rotating body (ball) 44 Outer ring fixing member 50 Frame member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F071 AA06 DD08 EE04 JJ03 JJ08 JJ10

Claims (4)

[Claims] 1. A bearing structure for rotatably holding both ends of a gas circulation fan of a gas laser device, wherein one end of the fan has a structure in which a rotating bearing attached to a rotating shaft is fixed to a bearing holding portion, and the other end thereof. Is a structure in which a rotating bearing attached to the rotating shaft is held movably in the axial direction of the rotating shaft with respect to the bearing holding portion, and the other end structure includes a rotating bearing between the rotating bearing and the bearing holding portion. A bearing structure for a fan used in a gas laser device, wherein a rotation restricting member is provided for the bearing holding portion. 2. The bearing structure at the other end, wherein a frame member is attached to the rotating bearing, and the frame member is held by the bearing holding portion instead of the rotating bearing being held directly by the bearing holding portion. The bearing structure for a fan used in a gas laser device according to claim 1, wherein a rotation restricting member for the bearing holding portion of the frame member is provided between the frame member and the bearing holding portion. 3. A bearing structure for a fan used in a gas laser device according to claim 1, wherein said rotation regulating member has a structure of a key and a key groove. 4. The gas laser device according to claim 1, wherein the bearing structure at the other end is provided with an elastic body for applying a pressure in an axial direction to a rotary bearing attached to the rotary shaft. Fan bearing structure.