JPH05167136A - Excimer laser device - Google Patents

Abstract

PURPOSE:To arrange optical elements in clean environments so as to elongate their service lives by respectively surrounding an optical element used as a laser resonator and another optical element used as an output laser beam detector with enclosure means and providing a purging means which purges the insides of enclosures with a clean gas. CONSTITUTION:The title device is provided with enclosure means 7 and 20 which respectively surround an optical element used as a laser resonator and another optical element used as an output laser beam detector and a purging means 24 for purging the insides of enclosures 15 and 22 with a clean gas. In addition, in order to make the surfaces of the enclosures 15 and 22 and optical element holders stable against an excimer laser beam, aluminum is used for manufacturing the enclosures 15 and 22 and holders of various kinds of optical elements and white anodic oxidation is performed on their surfaces by using an inorganic pigment. Therefore, the service lives of the optical elements are elongated, because the amounts of dust and harmful chemical substances are reduced from the periphery of the optical elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excimer laser device, and more particularly to improvement of an excimer laser device used as a light source for a reduction projection exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, an excimer laser oscillates a laser through a laser chamber 61 by forming a resonator with a front mirror 62 and a rear mirror 63. FIG. 3A shows an external mirror, which includes windows 65 and 66 of the laser chamber 61, a front mirror 62, and a rear mirror 6.
3 and a beam splitter 67 for output monitoring. Further, FIG. 3 (b) is based on an internal mirror,
It includes a front mirror 71, a rear mirror 72, and a beam splitter 67. Neither the external mirror nor the internal mirror described above is placed in a clean environment.

[0003]

However, since the excimer laser beam is an ultraviolet laser beam, the optical element is damaged by a very small amount of dust or an organic substance or a chemical substance such as oxygen, and the life of the optical element is short. There is a problem of becoming. Further, even if the optical element is placed in a clean environment, the surface of the optical element holder or the laser housing is irradiated with scattered light of the laser to cause abrasion or evaporation, and dust or chemical substances are generated to generate the optical element. Is damaged.

The present invention focuses on the above-mentioned conventional problems, and relates to an excimer laser device, and particularly an object thereof is to provide an excimer laser device used as a light source for a reduction projection exposure apparatus.

[0005]

In order to achieve the above object, in the present invention, a housing means surrounding an optical element used as a resonator of a laser and an optical element used as a detector of output laser light. And a purging means for purging the inside of the housing with clean gas. Further, the surfaces of the housing and the optical element holder are stably surface-treated with respect to the excimer laser light.

[0006]

According to the above construction, the inside of the housing is purged with a clean gas, and the surfaces of the housing and the optical element holder are stably surface-treated with respect to the excimer laser light, so that no dust or chemical substance is generated. Therefore, the optical element is placed in a clean environment, and the life of the optical element is dramatically extended.

[0007]

Embodiments of the excimer laser device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the excimer laser device of the present invention, showing an embodiment of spontaneous oscillation of an external mirror. In FIG. 1, the excimer laser device 1 includes a laser chamber part 3, a front side housing part 7, a rear side housing part 20, and a clean gas supply part 24. The laser chamber section 3 includes a laser chamber 4, a front side window 5 and a rear side window 6. The front housing 7 includes a front mirror 8, a beam splitter 9 for an output light sample, a condenser lens 10, a diffuser plate 11, a cone 12, a photodiode 13, and a window 1.
4 and a front side housing 15 fixed to the laser chamber 4. The rear side housing 20 is a rear mirror 21.
And a rear housing 22 fixed to the laser chamber 4.

Further, the optical elements such as the splitter 9, the mirrors 8 and 21 and the lens 10 are supported by an optical element holder (not shown).

The clean gas supply unit 24 includes pipes 25 and 26,
It comprises a clean gas supply device 28. Further, the front housing 7 and the rear housing 22 are connected to a clean gas supply device 28 by pipes 25 and 26. In the front-side housing part 7, the front-side window 5, the front mirror 8, the beam splitter 9 for the output light sample, and the condenser lens 1
0, the diffusion plate 11, the cone 12, the photodiode 13, and the window 14 are purged with clean gas. Similarly, in the rear housing 20, the rear window 6 and the rear mirror 21 are purged with clean gas.

Next, the operation of the above structure will be described. The laser light spontaneously oscillated in the laser chamber 4 is resonated by the front mirror 8 and the rear mirror 21 that are purged with clean gas, and the output light is output via the window 14 that is purged with clean gas. The detection of the output is performed by the beam splitter 9 for the output light sample, which is purged with the clean gas similarly to the above, is collected on the diffuser plate 11 via the condenser lens 10, and is diffused by the diffuser plate 11. The light is reflected by the cone 12 and collected by the photodiode 13, and the light intensity is detected by the photodiode 13.

In this embodiment, the above example is shown as the power monitor, but the present invention is not limited to this embodiment, and the optical element of the power monitor is arranged in the front side housing part 7 or the rear side housing part 20. You may. Further, in the case of the internal mirror, when the optical element of the power monitor is on the front side, the front mirror and the optical element of the power monitor are surrounded by a housing through the laser chamber, and even if the inside of the housing is purged with clean gas. good.

FIG. 2 is a block diagram showing an embodiment of a narrow band excimer laser device of the present invention. The same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted. In FIG. 2, the narrow band excimer laser device 30 includes a laser chamber part 3, a front side housing part 35, and a rear side housing part 45. A beam splitter 36 for wavelength detection, a condenser lens 37, and a diffusion plate 38 are provided in the front-side housing section 35.
A monitor etalon 39, a condenser lens 40, a line sensor or an area sensor 41, and a window 1
4, a front side housing 42 fixed to the laser chamber 4, and a photodiode or the like as described above. The rear side housing part 45 includes frisms 46 and 47, a grating 48, and a rear side housing 49 fixedly installed in the chamber 4.
Consists of. Further, the front housing 42 and the rear housing 49 are connected to the clean gas supply device 28 by the pipes 25 and 26. In the front-side housing portion 35, the front-side window 5, the front mirror 8, the beam splitter 9 for the output light sample, the condenser lens 10, and the diffuser plate 1
1, a cone 12, a photodiode 13, a window 14, a beam splitter 36 for wavelength detection,
Condensing lens 37, diffusion plate 38 and monitor etalon 3
9 and the condenser lens 40 and the line sensor or the area sensor 41 are purged with clean gas. Also,
Similarly, in the rear-side housing portion 45, the rear-side window 6, the prisms 46 and 47, and the grating 48 are purged with clean gas.

Further, optical elements such as a splitter, a mirror, a lens, a prism, and a grating are supported by an optical element holder (not shown) as in the above embodiment.

Next, the operation of the above structure will be described. The laser oscillated in the laser chamber 4 expands the beam by the prisms 46 and 47, oscillates the light by the narrow band method of the Littrow arrangement in which the light is reflected by the grading 48, and is output from the front mirror 8. The laser light is sampled by the beam splitter 9 and collected on the diffuser plate 11 via the condenser lens 10, and the laser light diffused by the diffuser plate 11 is reflected by the cone 12
Is reflected by the photo diode 13 and collected by the photo diode 13, and the light intensity thereof is detected by the photo diode 13.

Further, the light sampled by the beam splitter 36 passes through the monitor etalon 39 through the condenser lens 37 and the diffusion plate 38, and the line sensor or area sensor 41 arranged at the focal point of the condenser lens 40. The interference fringes are detected to detect the wavelength.

In this embodiment, the prism and the grating are used as the band narrowing element, but
Without being limited to this embodiment, for example, an etalon and a rear mirror or prism, an etalon and a grating may be combined. Further, although the monitor etron system is shown as the wavelength detector, another wavelength detection system such as a diffraction grating type spectroscope may be used.

Furthermore, the casings 15 and 2 shown in the above embodiment
When plating 2, 42, 49 and the holder of the optical element, a metal that does not deteriorate due to oxidation such as nickel, cobalt, chromium, gold or white metal may be plated as a surface treatment. When the material of the housing and the holder of the optical element is aluminum, no organic dye is filled. For example, white alumite treatment is good. The black alumite treatment is not suitable because it emits a harmful organic substance to an optical element by being irradiated with laser light. Further, the material of the housing and the holder of the optical element may be stainless steel.

As an example of the clean gas, an inert gas such as nitrogen or helium, or a gas such as air that does not react and absorb laser light may be passed through a filter such as HEPA to be used as the clean gas. Further, the degree of airtightness inside the housing may be such that the inside thereof is filled with clean gas. If the degree of airtightness inside the housing is increased, a discharge port with a small amount of clean gas may be provided.

[0020]

As described above, according to the present invention,
The optical element used as the resonator of the laser and the optical element used for the detector of the output laser light are surrounded by a housing, and the inside of the housing is purged with clean gas. Chemicals that are harmful to the device are reduced and the life of the optical device is extended. Further, by making the surfaces of the housing and the optical element holder stable against the laser light, dust or chemical substances harmful to the optical element are not generated due to the scattering of the laser light, and the life of the optical element is extended. .. As means for enclosing the optical element in the housing, the rear-side optical element is enclosed in the first enclosure via the laser chamber, and the front-side optical element is enclosed in the second enclosure in the laser chamber. By purging the casing and the second casing with clean gas, respectively, an excellent effect that efficient purging can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an excimer laser device of the present invention.

FIG. 2 is a configuration diagram showing one embodiment of a narrow band oscillation excimer laser device of the present invention.

FIG. 3 is a configuration diagram showing an embodiment of a conventional excimer laser device.

[Explanation of symbols]

 1 Excimer Laser Device 3 Laser Chamber Section 4 Laser Chamber 5 Front Side Window 6 Rear Side Window 7, 35 Front Side Housing Section 8 Front Mirror 9, 36 Beam Splitter 10 Condensing Lens 12 Chamber 15, 42 Front Side Housing 20, 40 Rear Side casing part 22, 49 Rear side casing 24 Clean gas supply part 28 Clean gas supply device 30 Zone excimer laser device 46, 47 Prism 48 Grating

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 8934-4M H01S 3/08 Z

Claims (7)

[Claims] 1. A housing means for enclosing an optical element used as a resonator of a laser and an optical element used for a detector of output laser light, and a purging means for purging the inside of the housing with a clean gas. An excimer laser device characterized in that 2. The narrow-band oscillation excimer laser device according to claim 1, wherein aluminum is used as a material of the housing and a holder of various optical elements, and white alumite treatment of an organic dye is performed as a surface treatment. 3. The narrow band oscillation excimer laser device according to claim 1, wherein stainless steel is used as a material for the housing and the holder for various optical elements. 4. The narrow band oscillation excimer laser device according to claim 1, wherein nickel, chromium, cobalt, gold, or a metal of white metal is used for plating of the housing and the holders of various optical elements. 5. A housing means for surrounding the optical element, wherein a rear side optical element is surrounded by a first housing via a laser chamber, and a front side optical element is surrounded by a second housing via a laser chamber, 5. The excimer laser device according to claim 1, wherein the first casing and the second casing are each provided with a purging means for purging the inside of the casing with a clean gas. 6. The optical element in the first housing is a window and a rear mirror, and the optical element in the second housing is a front window and a front mirror, and an optical element of an output monitor. Excimer laser device. 7. A window and a band-narrowing element as an optical element in the first housing, and an optical element of a front side window and front mirror, an output monitor and a wavelength detector as an optical element in the second housing. Claim 5
The excimer laser device described.