JP2000088705A - Device for monitoring light of excimer laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light monitoring device in which damage to optical parts is almost prevented and maintainability is improved. SOLUTION: A light monitoring device is provided with a beam splitter 3 to sample a part of the laser light 2 of a narrow-band excimer laser, a light monitor to measure the output characteristics of sample light, and a monitor box 8 to house and approximately shield the light monitor so as to prevent outer air from mixing into the vicinity of the light monitor. In this case, the light monitoring device is provided with a mounting unit 10 with both a flange part 12 provided at the peripheral part on one end side of a hollow tubular cabinet 11 for mounting the beam splitter 3 and a beam splitter mounting surface 16 inclined by a predetermined degree θ with respect to the axis on the other end side of the tubular cabinet 11, and the no-coat beam splitter 3 is mounted to the beam splitter mounting surface 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical monitor for measuring the characteristics of laser light of an excimer laser having a narrow band.

[0002]

2. Description of the Related Art Conventionally, in a narrow-band excimer laser whose wavelength is narrowed, a part of the laser light is sampled outside the optical axis as a sample light, and characteristics such as power and center wavelength of the laser light are sampled. There is known an optical monitoring device for measuring the following. 3 and 4 are configuration diagrams of an optical monitoring device according to the related art, and the related art will be described below with reference to the drawings.

First, FIG. 3 shows an example of an optical monitor device according to the prior art. In FIG. 1, a part of a laser beam 2 oscillated from a narrow-band excimer laser 1 is reflected downward by a beam splitter 3 in the figure to become a sample beam 4 for measuring the characteristics of the laser beam 2. There is known a technique in which the sample light 4 is distributed by a second beam splitter 27 and input to detectors such as a power detector 6 and a wavelength detector 7 to measure the characteristics.

However, in the optical monitoring device shown in FIG. 3, the optical components such as the second beam splitter 27 disposed on the optical path of the sample light 4 and the optical components used for the detector are exposed to the outside air. Therefore, dust may adhere to these optical components. Then, when the optical component is irradiated with the sample light 4, the attached dust is burned and may damage the optical component.

[0005] Therefore, as shown in FIG. 4, these optical components are housed in a monitor box 8 so as to be substantially shielded from the outside air, and a clean inert gas such as nitrogen is purged into the monitor box 8. A technique for preventing dust from adhering to components is known.

In FIG. 1, a monitor box 8 is connected to a narrow-band excimer laser 1 by a duct 9. Then, the monitor box 8 includes the beam splitter 3
The laser beam 2 passes through the window 25 and exits outside the monitor box 8. The window 25 forms a part of the wall surface of the monitor box 8 and plays a role of substantially shielding outside air from entering the inside of the monitor box 8. Further, a purge pipe 26 is connected to the monitor box 8 to purge clean nitrogen into the monitor box 8.

[0007]

However, the prior art shown in FIG. 4 has the following problems.

The window 25 in the prior art is provided with an anti-reflection coating for increasing the transmittance to the laser beam 2. If the anti-reflection coating is not applied, a part of the laser beam 2 is reflected when entering the window 25, and the power of the laser beam 2 passing through the window 25 is reduced by several percent. Further, the light reflected by the window 25 is irregularly reflected inside the monitor box 8 and causes a measurement error of the characteristics, or returns to the narrow-band excimer laser 1 and adversely affects laser oscillation. . Therefore, window 2
When the laser beam 5 is arranged in the optical path of the laser beam 2, it is necessary to apply an antireflection coating.

However, the coating film of the antireflection coating has a low resistance to the laser beam 2, which is ultraviolet rays, and deteriorates when the laser beam 2 is irradiated for a long time. Therefore, not only does the transmittance of the window 25 decrease, but if the irradiation is continued, the laser beam 2 concentrates on the deteriorated coating film, and the window 25 is damaged. For this reason, conventionally, the window 25 has to be replaced frequently, and there is a problem that much time is required for the maintenance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical monitor for an excimer laser, in which damage to an optical component is less likely to occur and maintenance is improved. And

[0011]

Means for Solving the Problems, Functions and Effects In order to achieve the above object, the invention of the first configuration is provided on an optical path of a laser beam output from a narrow-band excimer laser, and includes a laser beam. A beam splitter for sampling the section,
An excimer laser optical monitor device including an optical monitor that measures the characteristics of the sampled sample light and a monitor box that houses the optical monitor and substantially shields outside air from entering near the optical monitor. The beam splitter forms a part of the wall surface of the monitor box, and the inside of the monitor box is substantially shielded by the beam splitter.

According to the invention described in the first configuration, the monitor box is shielded by the beam splitter. This eliminates the need for a monitor box window,
The number of optical components is reduced, and the configuration of the optical monitoring device is simplified.

According to a second aspect of the present invention, in the optical monitoring device according to the first aspect, the beam splitter is an uncoated beam splitter that is not coated with an anti-reflection coating.

According to the invention described in the second configuration, the beam splitter is uncoated. As a result, since there is no antireflection coating, the coating film does not deteriorate, the beam splitter is less likely to be damaged, and its life is extended.

Further, the invention of the third configuration provides a beam splitter provided on the optical path of the laser light output from the narrow-band excimer laser and sampling a part of the laser light, and a characteristic of the sampled light sampled. A hollow cylindrical housing in an excimer laser optical monitoring device including an optical monitor to be measured and a monitor box that houses the optical monitor and substantially shields outside air from entering near the optical monitor; A flange portion provided on an outer peripheral portion at one end side of the cylindrical housing for attaching the cylindrical housing to a monitor box, and a predetermined angle θ with respect to the axial direction at the other end side of the cylindrical housing. A mounting unit having a beam splitter mounting surface for mounting the beam splitter, the mounting unit being provided at an angle, and an uncoated beam splitter mounted on the beam splitter mounting surface. It is mounting.

According to the invention described in the third configuration, the beam splitter is mounted on the beam splitter mounting unit having the mounting surface at a predetermined angle, and this is mounted on the monitor box. This facilitates positioning because the beam splitter is previously mounted at a predetermined angle. In addition, since the beam splitter can be easily removed at the time of replacement or cleaning, the maintainability is improved.

According to a fourth aspect of the present invention, in the optical monitoring device according to the third aspect, the monitor box is provided with positioning pins for mounting the mounting unit.

According to the invention described in the fourth configuration, the positioning pins are provided on the monitor box. Thus, the mounting unit 10 on which the beam splitter is mounted can be easily positioned on the monitor box 8, and labor for mounting can be saved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. Note that the same elements as those in FIGS. 3 and 4 are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a configuration diagram of an optical monitor device according to the present embodiment. In FIG. 1, an optical monitoring device includes a beam splitter 3 for sampling a part of a laser beam 2 oscillated from a narrow-band excimer laser 1, a mounting unit 10 for mounting the beam splitter 3, and a sample beam sampled by the beam splitter 3. An optical monitor 5 for measuring the characteristics of the optical monitor 4, a monitor box 8 accommodating the optical monitor 5, a hollow cylindrical duct 9 protruding from the monitor box 8, and an optical monitor controller 28 for controlling the optical monitor 5 are provided. Further, a purge pipe 26 is connected to the monitor box 8, and a clean inert gas such as nitrogen is introduced from here, so that the inside of the monitor box 8 is kept in a clean environment.

First, the optical monitor 5 includes a power detector 6 for measuring the power of the sample light 4, a wavelength detector 7 for measuring the center wavelength and the line width of the sample light 4, and the power detector 6. A second beam splitter 27 for distributing to the wavelength detector 7 is provided.

The power detector 6 has a light-voltage conversion mechanism and outputs a voltage corresponding to the power of the sample light 4. The wavelength detector 7 includes a frosted glass 21 for diffusing the sample light 4, a monitor etalon 22 for forming interference fringes corresponding to the wavelength of the incident light, and a condenser lens 23 for converging the interference fringes to the optical position detector 24. And an optical position detector 24 that detects the interval and the stripe width of the interference fringes and outputs a voltage corresponding to the interval and the stripe width. The power detector 6 and the wavelength detector 7 are both connected to the optical monitor controller 28 and can transmit and receive signals to and from each other.

Next, FIG. 2 shows a detailed sectional view of the mounting unit 10 for mounting the beam splitter 3. As shown in FIG. 1, the mounting unit 10 includes a hollow cylindrical housing 11.
Has a flange portion 12 on one end side thereof, and the flange portion 12 is detachably attached to the monitor box 8 by screws 13. A pin hole 14 is provided in the flange portion 12 so as to be fitted to a positioning pin 15 attached to the monitor box 8, and the positioning of the mounting unit 10 relative to the monitor box 8, that is, the positioning of the beam splitter 3. ing.

The other end of the cylindrical housing 11 has a beam splitter mounting surface 16 inclined at a predetermined angle θ with respect to the optical axis 2A of the laser beam 2, and further has a beam splitter mounting surface 16 Is provided on the bottom surface of the circular recess 19 into which the beam splitter 3 is almost fitted. The beam splitter 3 is fitted into the recess 19 and pressed against the beam splitter mounting surface 16 by a screw 18 via a leaf spring 17 from the lower left direction in the figure, and is at a predetermined angle with respect to the optical axis 2A of the laser beam 2. θ is tilted and fixed. Also,
The flange portion 12 has an emission port 20 through which the laser light 2 passes.
Has been opened. As described above, the mounting unit 10 and the beam splitter 3 constitute a part of the wall surface of the monitor box 8 and play a role of substantially shielding the optical monitor 5 inside the monitor box 8 from the outside air.

Hereinafter, the operation of the optical monitoring device according to the present embodiment will be described in detail with reference to FIG. The laser light 2 oscillated from the narrow band excimer laser 1 passes through the inside of the duct 9, travels rightward in the figure, and enters the beam splitter 3. Most of the laser light 2 passes through the beam splitter 3, passes through the inside of the cylindrical housing 11, and is emitted to the outside of the monitor box 8 from the emission port 20 opened in the flange 12.

A part of the laser beam 2 is reflected by the beam splitter 3 in the downward direction in the figure, becomes a sample beam 4 and is incident on the optical monitor 5, and its characteristics are measured. A part of the sample light 4 incident on the optical monitor 5 is reflected rightward by the second beam splitter 27 and is incident on the power detector 6, and the rest is transmitted through the second beam splitter 27 and passed through the wavelength detector 7. Incident on.

When the sample light 4 enters the power detector 6, the power detector 6 outputs a voltage corresponding to the power of the incident sample light 4. The output voltage is calculated by the optical monitor controller 28 connected to the power detector 6, and the beam splitter 3 and the second beam splitter 2 are calculated.
7 based on the reflectance of the laser light 2
Power can be measured.

The sample light 4 incident on the wavelength detector 7 is diffused by the frosted glass 21 and the monitor etalon 22
Incident on. The monitor etalon 22 forms an interference fringe having an interval corresponding to the center wavelength of the incident sample light 4 and a stripe width corresponding to the line width.
3 forms an image on the light position detector 24. The optical position detector 24 measures the interval and the fringe width of the interference fringes, and outputs them to the optical monitor controller 28 connected to the wavelength detector 7. The optical monitor controller 28 calculates the center wavelength and the line width of the laser light 2 by calculating the interval and the stripe width.

At this time, the beam splitter 3 is a non-coated one without an anti-reflection coating. This is because, in the beam splitter 3 provided with the antireflection coating, the coating film is damaged by the long-time irradiation of the laser beam 2 as in the case of the window 25, and the beam splitter 3 must be replaced frequently. On the other hand, no damage occurs in the uncoated beam splitter 3, and the life of the beam splitter 3 can be extended. Then, even if the anti-reflection coating is not applied, all the laser light 2 reflected by the beam splitter 3 is reflected downward in the drawing to become a sample light 4. Therefore, as in the prior art, the reflected light is irregularly reflected inside the monitor box 8,
There is no problem of returning to the narrow band excimer laser 1. Further, as a material of the beam splitter 3,
SiO2 and fluoride crystals, particularly CaF2, are desirable.
This is because these materials have particularly high durability against ultraviolet light, and are particularly effective for an ArF excimer laser.

In the present embodiment, the optical monitor 5 includes the power detector 6 for measuring the power of the laser beam 2 and the wavelength detector 7 for measuring the center wavelength and the line width.
In addition to or in place of these detectors, a beam profile detector that measures the cross-sectional shape and position of the laser light 2 and a beam divergence detector that measures the divergence angle and traveling direction of the laser light 2 Alternatively, a detector such as a pulse duration detector for measuring the time width of the pulse oscillation of the laser light 2 may be provided. In this case, a new beam splitter for distributing the sample light 4 is required.

As described above, in the optical monitor device according to the present embodiment, the beam splitter 3 that guides the laser light 2 to the optical monitor 5 forms a part of the wall surface of the monitor box 8 that houses the optical monitor 5. The optical monitor 5 is substantially shielded from outside air. This eliminates the need for the window 25 on the emission side of the monitor box 8, which is required in the prior art, and reduces the number of optical components.

In addition, the uncoated beam splitter 3
Is shielded by the window splitter 3 compared with the prior art in which the monitor box 8 is shielded by the window 25 coated with an anti-reflection coating.
Very little damage.

Further, in the prior art, since the window 25 is disposed substantially perpendicular to the optical axis of the laser light 2, the reflected light returns into the narrow band excimer laser 1 to prevent laser oscillation, The irregular reflection in the box 8 causes a measurement error. On the other hand, in the present embodiment, all the light reflected by the beam splitter 3 becomes the sample light 4, and does not cause the above-described problem, and is effectively used for measuring the characteristics of the laser light 2.

Further, since the beam splitter 3 is mounted on the mounting unit 10 having the flange portion 12, when the beam splitter 3 is replaced, it can be easily mounted and removed. Further, since the beam splitter 3 is mounted on the beam splitter mounting surface 16 having a predetermined angle θ with respect to the optical axis 2A of the laser beam 2, there is no need to finely adjust the mounting angle of the beam splitter 3. And
Since the positioning pins 15 are provided on the monitor box 8 and the mounting unit 10 is mounted in accordance with the positioning pins 15, complicated positioning is not required at the time of mounting. Thus, the attachment and detachment of the beam splitter 3 are easy, and the maintainability is very good.

[Brief description of the drawings]

FIG. 1 is a diagram related to an embodiment of the present invention.

FIG. 2 is a detailed sectional view of a beam splitter mounting portion.

FIG. 3 is an explanatory diagram of an optical monitoring device according to a conventional technique.

FIG. 4 is an explanatory diagram of an optical monitoring device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Excimer laser narrowing, 2 ... Laser light, 2A ... Optical axis, 3 ... Beam splitter, 4 ... Sample light, 5 ... Optical monitor, 6 ... Power detector, 7 ... Wavelength detector, 8 ... Monitor box, 9: duct, 10: mounting unit, 11: cylindrical housing, 12: flange, 13: screw, 14: pin hole, 15: positioning pin, 16: beam splitter mounting surface, 17: leaf spring, 18: screw , 19 ... recess, 20 ... exit, 21 ... ground glass, 22 ... monitor etalon, 23
... Condenser lens, 24 ... Optical position detector, 25 ... Window, 26 ... Piping, 27 ... Second beam splitter, 28 ...
Optical monitor controller.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryo Buddha Rata 400 Yokokura Nitta, Koyama City, Tochigi Prefecture Inside the Komatsu Manufacturing Techno Center (72) Inventor Koji Shio 400 Yokokura Nitta 400, Oyama City, Tochigi Prefecture Komatsu Manufacturing Techno Co., Ltd. F term in the center (reference) 2G086 EE03 EE12 5F071 AA06 HH02 JJ03 JJ10 5F072 AA06 HH02 JJ03 JJ20 KK15 YY11

Claims (4)

[Claims] 1. A beam splitter (3) provided on an optical path of a laser beam (2) output from a narrow-band excimer laser (1) and sampling a part of the laser beam (2). An optical monitor (5) that measures the characteristics of the sample light (4), and a monitor box (8) that houses the optical monitor (5) and substantially shields the outside of the optical monitor (5) so that outside air does not enter. In the excimer laser optical monitoring device provided with the above, the beam splitter (3) constitutes a part of the wall surface of the monitor box (8), and the inside of the monitor box (8) is substantially formed by the beam splitter (3). An optical monitoring device characterized by being shielded. 2. The optical monitoring device according to claim 1, wherein the beam splitter is a non-coated anti-reflection coated beam splitter. 3. A beam splitter (3) provided on an optical path of a laser beam (2) output from a narrow-band excimer laser (1) and sampling a part of the laser beam (2). An optical monitor (5) that measures the characteristics of the sample light (4), and a monitor box (8) that houses the optical monitor (5) and substantially shields the outside of the optical monitor (5) so that outside air does not enter. An optical monitoring device for an excimer laser comprising: a hollow cylindrical housing (11); and a cylindrical housing (11) provided on an outer peripheral portion on one end side of the cylindrical housing (11). A flange portion (12) for mounting to the monitor box (8) and a beam splitter (3) provided at the other end of the cylindrical housing (11) at a predetermined angle θ with respect to the axial direction. And a mounting unit (10) having a beam splitter mounting surface (16) for mounting, the beam splitter mounting surface (16) An optical monitoring device characterized in that an uncoated beam splitter (3) is mounted on the optical monitor. 4. The optical monitoring device according to claim 3, wherein the monitor box (8) is provided with a positioning pin (15) for mounting the mounting unit (10).