JPH04137776A - Excimer laser apparatus - Google Patents

Abstract

PURPOSE:To generate a steady repulsion force, cancel a thrust force of rotary bearing without giving any influence on a magnetic coupling ring and thereby realize expansion of operation life of the rotary bearing. CONSTITUTION:First permanent magnets 13a, 13b magnetized in multipolarity are attached to disks 12a, 12b provided opposed with each other sandwiching a non-magnetic separating wall 11 by rotary bearings 10a, 10b and second permanent magnets 15a, 15b magnetized in the direction of rotating axis are provided at the center shaft of the disks 12a, 12b with the same polarity provided opposed with each other. Since the permanent magnets 15a, 15b are magnetized in the direction of rotating axis, the same polarity is opposed steadily even when the disks 12a, 12b are rotated. Therefore, a steady repulsion force is generated between the permanent magnets 15a, 15b and a thrust force of the rotary bearings 10a, 10b by an attracting force generated between the disks 12a, 12b is cancelled or alleviated. Since a magnetic force between the second permanent magnets 15a, 15b does not depend on a rotating angle of the disks, any influence is not given to a coupling force of the magnetic coupling.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an excimer laser device for industrial and medical use.

BACKGROUND OF THE INVENTION In recent years, excimer lasers have attracted attention as a new industrial laser light source. By combining rare gases such as krypton and xenon and halogen gases such as fluorine and chlorine as the excimer laser laser medium, 353 nm
It is one of the ultraviolet lasers that can obtain oscillation lines at several wavelengths in the range from 193 nm to 193 nm. Since excimer lasers can provide greater output in a shorter wavelength range than conventional laser devices, they have come to be widely used as a new light source in fields such as microfabrication, surgery, and energy. Particularly in the semiconductor manufacturing process, demand is rapidly increasing for use as a light source for reduction projection devices for producing VLSIs.

FIG. 5 is a sectional view of a typical conventional excimer laser device. In such an excimer laser device, the main discharge electrode 2 is heated by the high voltage applied from the high voltage control circuit 1.
When a laser-excited discharge occurs between a and 2b, the laser medium gas in this region deteriorates and the discharge characteristics deteriorate (and repeated oscillations become impossible. For this reason, a cross-flow fan or the like is usually installed in the airtight container 3. By providing a blower fan 4, a method is adopted in which the laser medium gas is circulated at high speed within the airtight container 3 to perform laser oscillation without replacing the laser medium gas between the main discharge electrodes 2a and 2b.Excimer laser. Since the device uses highly corrosive halogen gas as the laser medium gas, the motor that drives the blower fan 4 cannot be installed inside the airtight container 3. Therefore, the drive shaft of the blower fan 4 is usually It is taken out of the airtight container 3 through a transmission device (hereinafter referred to as a feedthrough) 5 and connected to a motor 6 also placed outside the airtight container 3. In addition, 7 is a total reflection mirror, 8 is an output mirror,
9 is a gas circulation circuit. In recent years, a rotating introduction machine using a magnetic coupling has been increasingly used for the feedthrough 5 due to reliability issues.

FIG. 6 is a sectional view of a main part of a rotation introduction method using a magnetic coupling. Disks 1 are arranged to face each other with a non-magnetic partition 11 interposed between rotary bearings 10a and 10b.
Permanent magnets 13a, 13 magnetized with multiple poles at 2a, 12b
b is attached. Due to the attractive force acting between the permanent magnets 13a and 13b, the disks 12a and 12b are attached to the partition wall 1.
1 , and driving force can be transmitted from the motor 6 disposed outside the airtight container 3 to the blower fan 4 . Note that 14a and 14b are rotary bearing holders.

Problems to be Solved by the Invention However, in the above conventional configuration, the disks 12a, 1
2b, that is, between the permanent magnets 13a and 13b (attractive force) is transferred to the rotating bearing (for example, bearing) 1.
0a and 10b support it as a thrust force (force in the axial direction). In an excimer laser device for semiconductor lithography, a high repetition rate of operation is required, so the flow rate of the laser medium gas must be increased, and the blower fan 4 must also be rotated at high speed. Therefore, the permanent magnet 13a,
13b must be strengthened to increase the bonding force. In order to achieve the repetition rate of 400 pulses or more per second required for an excimer laser device for semiconductor lithography, the rotation speed of the blower fan 4 must be increased. 3,000 revolutions per minute or more and a power of 400 W or more are required, but the coupling force of the magnetic coupling device at this time, that is, the attractive force between the permanent magnets 13a and 13b exceeds 200 kgf.

In the excimer laser device, since highly corrosive fluorine, chlorine, etc.) is used as the laser medium gas, a general lubricant should be used for the rotating bearing 10b disposed inside the airtight container 3. I can't. Therefore, it is desirable that the rotary bearing 10b be a special self-lubricating type with high corrosion resistance. However, because this type of bearing has low rigidity, its load capacity is small (usually less than 5 kgf), and it is impossible to support the large thrust force mentioned above. This is dealt with by filling with fluorine-based grease.

Even after being evacuated, halogen gases such as fluorine and chlorine are adsorbed on the inner surface of the airtight container 3, and when this reacts with moisture in the air, hydrogen fluoride and hydrogen chloride are generated, causing electricity in the components of the laser device. Insulating Characteristics 2 It is necessary to avoid exposing the inside of the airtight container 3 to air as much as possible, since this will deteriorate the mechanical strength and shorten the service life. However, since the airtight container 3 is evacuated each time the laser medium gas is exchanged, the grease filled in the rotating bearing 10b evaporates, and the rotating bearing 10b is evacuated.
b becomes exposed to corrosive gases. In addition, as mentioned above, a large thrust force is applied, so the rotating bearing 1
The lifespan of 0b is significantly shortened and it becomes necessary to replace it frequently. Therefore, not only does the frequency of maintenance increase, but the life of the device as a whole is shortened, and its reliability becomes poor.

Furthermore, since the laser medium gas is contaminated by impure gas released from the grease and dust (metal particles) generated as the rotary bearing 10b deteriorates, the consumption of the laser medium gas increases and running costs increase.

The present invention solves the above-mentioned conventional problems.By reducing the thrust force of the disk type magnetic coupling, it is possible to use a rotary bearing with excellent corrosion resistance, which requires less maintenance, has a long life, and is highly reliable. The purpose of the present invention is to provide an excimer laser device that is highly economical.

Means for Solving the Problems To achieve this object, the excimer laser device of the present invention includes an airtight container, a pair of discharge electrodes in the airtight container, a laser medium gas, and a system for blowing the laser medium gas between the discharge electrodes. The drive means for driving the blower fan is arranged outside the airtight container, and the power is transmitted from the drive means to the blower fan by two disks facing each other with a partition wall in between. In an excimer laser device using a disk-type magnetic coupling in which at least one of the two disks includes a first permanent magnet and generates a coupling force between the two disks by the magnetic force of the first permanent magnet, at least one of the two disks A second permanent magnet is provided at the center of one of the disks.

Effect: This configuration makes it possible to reduce the thrust force exerted on the rotary bearing supporting the disk-type magnetic coupling. As a result, a rotary bearing with excellent corrosion resistance can be used, and an excimer laser device that requires less maintenance, has a long life, is highly reliable, and is highly economical can be realized.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the same parts as in the conventional example shown in FIGS. 5 and 6 are given the same reference numerals.

FIG. 1 is a sectional view of a main part of a rotating introduction machine of an excimer laser apparatus in a first embodiment of the present invention, and only the parts related to the present invention are shown. In this embodiment, rotation bearings 10a and 10b
The disks 12a are arranged to face each other with the non-magnetic partition wall 11 in between.

12b is a first permanent magnet 13a magnetized with multiple poles.

13b is attached, and this disk 12a.

Second permanent magnets 15a and 15b magnetized in the direction of the rotation axis are attached to the central axis of the magnet 12b so that the same magnetic poles face each other. Second permanent magnet 15a.

Since 15b is magnetized in the direction of the rotation axis, the disk 12
Even when a and 12b rotate, the same magnetic poles always face each other. Therefore, the second permanent magnet 15a.

A steady repulsive force is generated between the disks 12 and 15b.
Rotation bearings 10a and 10 due to suction force acting between a and 12b
This will cancel out or alleviate the thrust force of b. In a magnetic coupling device, the coupling force is obtained by differentiating the magnetic energy with respect to the rotation angle, but in this embodiment, the magnetic force between the second permanent magnets 15a and 15b is steady and depends on the rotation angle of the disk. Therefore, it has no effect on the coupling force of the magnetic coupling device. Normally, the gap d1 between the first permanent magnets 13a, 1, 3b
is approximately 1 cWl due to accuracy issues.

Further, since the thickness d of the partition wall 11 is about 31w1, the second
The gap d2 between the permanent magnets 15a and 15b is 511II.
It can be set to 11 or less. Since the force acting between permanent magnets is inversely proportional to the square of the distance between the magnets, if the same type of magnets are used, it is the first magnet 12a.

The ratio of the attractive force acting between magnets 12b and the repulsive force acting between second magnets 15a and 15b is four times or more per unit magnetic charge.

Normally, since there are restrictions on the size of the disks 12a, 12b, the second permanent magnets 15a, 15b cannot be made unnecessarily large, and are 1/16 of the size of the first magnets 13a, 13b.
However, even in this case, the rotating bearing 10
The thrust force applied to a and 10b can be reduced to about three quarters.

FIG. 2 is a sectional view of a main part of a rotary introduction machine of an excimer laser apparatus according to a second embodiment of the present invention, and only the parts related to the present invention are shown in this figure.

This embodiment has the same structure as the first embodiment of the present invention shown in FIG. 1, except that the magnetic body 16 is attached only to the portion of the partition wall 11 sandwiched between the second permanent magnets 15a and 15b. Both effects are the same. In this example,
Second permanent magnet 15a.

15b is the magnetic material 16, so the second
The magnetic distance d2 between the permanent magnets 15a and 15b is the distance d3 between the permanent magnet 15a and the magnetic body 16, and the magnetic distance d2 is the distance between the permanent magnet 15a and the magnetic body 16.
Assuming the distance between the permanent magnet 1.5b and the permanent magnet 1.5b as d4, d2=d
It can be set as 3+d4. Therefore, it is possible to make d2 smaller than the thickness of the partition wall 11, and when the configuration is similar to that of the first embodiment of the present invention, the distance d2 between the second permanent magnets 15a and 15b can be equivalently approximately 2 m+. narrowed down to At this time, the thrust force of the rotary bearings 10a and 10b is almost canceled out, so a corrosion-resistant self-lubricating rotary bearing can be used.
As a result, the life of the rotary bearing 10b can be significantly extended. According to the inventor's experiments, a lifespan 20 times longer than when a normal stainless steel bearing was used as the rotary bearing 10b and filled with fluorine-based grease was obtained.

FIG. 3 is a sectional view of a main part of a rotating introduction machine of an excimer laser apparatus according to a third embodiment of the present invention, and only the parts related to the present invention are shown in this figure.

In this embodiment, a permanent magnet 15a is placed at the center of the disk 12a, a third permanent magnet 17 is placed on the partition wall 11, and a magnet 15b is placed on the disk 12b, facing each other in the above-mentioned order with the direction of the rotational axis being the direction of magnetization. This embodiment is the same in structure and operation as the first embodiment of the present invention shown in FIG. 1, except that the magnetic poles of the surfaces are arranged to have the same polarity. With such a configuration, there is a gap between the permanent magnet 15a and the permanent magnet 17, and between the permanent magnet 15b and the permanent magnet 17.
As a result, a repulsive force is generated between the rotating bearings 10a,
The thrust force applied to 10b can be reduced. In this example, the distance between the permanent magnets is the same as the second one of the present invention shown in FIG.
Since the thrust force is smaller than that of the embodiment, it is possible to cancel out a larger thrust force.

FIG. 4 is a sectional view of a main part of a rotary introduction machine of an excimer laser apparatus according to a fourth embodiment of the present invention, and only the parts related to the present invention are shown in this figure.

In this embodiment, the magnet attached to the partition wall 11 is an electromagnet 18, and the third embodiment of the present invention shown in FIG.
The structure and operation are the same as those of the embodiment. In this embodiment, since the magnet is an electromagnet 18, the thrust force applied to the rotary bearings 10a, 10b can be adjusted to completely O by changing the excitation current. Furthermore, when assembling the magnetic coupling device, no repulsive force is generated between the partition wall 11 and the permanent magnets 15a or 15b, making the work easier.

Effects of the Invention As described above, the present invention generates a steady repulsion force by providing a permanent magnet in the center of a disk-type magnetic coupling device used in a rotation introduction machine, which affects the coupling force of the magnetic coupling. This cancels out the thrust force of the rotating bearing that supports the disk without giving any damage, making it possible to use a rotating bearing with excellent corrosion resistance. As a result, an excimer laser device that requires less maintenance, has a long life, is highly reliable, and is highly economical can be realized.

[Brief explanation of drawings]

FIGS. 1 to 4 are sectional views of main parts of the rotary introduction machine of the excimer laser device in the first to fourth embodiments of the present invention, FIG. 5 is a sectional view of the conventional excimer laser device, and FIG. 6 1 is a sectional view of a main part of a rotation introduction machine using a magnetic coupling. 3...Airtight container, 4...Blower fan,
6...Motor (driving means), 11...
Partition wall, 12a, 12b...Disk, 13a,
13b...First permanent magnet, 15a, 15b.
...Second permanent magnet. Name of agent: Patent attorney Haruaki Ogata et al. 22 Figure 3 - Ki! B unit 12aJ2b 41. -Yu ML-y Ann 13a, 13b Daysuge 1st permanent magnet diagram diagram diagram diagram diagram diagram! Figure ρ ノ

Claims (5)

[Claims] (1) An airtight container, a pair of discharge electrodes in the airtight container, a laser medium gas, and a blower fan for blowing the laser medium gas between the discharge electrodes, and a driving means for driving the blower fan is provided in the airtight container. placed outside the container;
For transmitting power from the drive means to the blower fan, two disks face each other with a partition wall in between, at least one of the two disks is provided with a first permanent magnet, and the first
In an excimer laser device using a disk-type magnetic coupling that generates a coupling force between the two disks by the magnetic force of a permanent magnet, a second permanent magnet is provided at the center of at least one of the two disks. An excimer laser device equipped with (2) The excimer laser device according to claim 1, wherein the second permanent magnets are attached to both of the two disks with their magnetic poles facing each other in directions that repel each other. (3) The excimer laser device according to claim 1, further comprising a magnetic material provided at a central portion of the partition wall and at a position corresponding to the center of rotation of the disk. (4) A permanent magnet is installed at the center of the partition wall and at a position corresponding to the center of rotation of the disk, and the magnetic pole of the permanent magnet is oriented in a direction that repels a second permanent magnet installed on the disk. The excimer laser device described. (5) The excimer laser device according to claim 4, wherein an electromagnet is used in place of the permanent magnet installed at a position corresponding to the center of rotation of the disk.