JPH06104520A - Narrow band oscillation laser system - Google Patents

Abstract

PURPOSE:To obtain an improved narrow band oscillation laser system being employed as a light source in reduction projection aligner. CONSTITUTION:In a narrow band laser comprising at least a grating 25 as a narrow band element, at least one mirror 3 is interposed between the grating 25 and a laser chamber 10 where the mirror 3 is applied with a coating for totally reflecting the output laser beam B but transmitting an alignment laser beam A and means for introducing the alignment laser beam A through the mirror 3 while substantially aligning with the optical axis of the output laser beam B is provided. The mirror 3 is provided with an angle adjusting mechanism for varying the wavelength being selected through the grating 25 or aligning the optical axis of laser.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in Japanese Patent Application No. 62-214396 and the like, since excimer laser light is ultraviolet light and is invisible, visible light alignment light is required for adjusting the optical axis. Therefore, in the case of normal natural oscillation or when only the etalon is used as the band-narrowing element, a dielectric film that reflects excimer light and transmits the alignment light 103 is coated as a reflective film of the rear mirror 101 and the etalon 102 to form a rear mirror. Alignment light 103 is introduced from the back surface of 101 to match the optical axis of the excimer light. (See Figure 4)

[0003]

However, when a grating is used as the band-narrowing element, visible light does not pass because the reflective film is aluminum. Therefore, there is a problem that the alignment light cannot be transmitted from the back surface of the grating and the alignment light cannot be emitted.

In view of the above-mentioned conventional problems, the present invention has an object to provide a narrow band oscillation laser device used as a light source for a reduction projection exposure apparatus, and in particular, an apparatus capable of adjusting an alignment optical axis.

[0005]

In order to achieve the above object, according to a first aspect of the present invention, in a narrow band laser in which at least a grating is arranged as a narrow band element, at least one sheet is provided between the grating and the laser chamber. The mirror is placed, the mirror is provided with a coating that totally reflects the output laser light and transmits the alignment laser light, and a means for introducing the alignment laser light through the mirror so as to approximately match the optical axis of the output laser light is provided. It is characterized by having.

In the second invention based on the first invention, the mirror is provided with an angle adjusting mechanism for changing the selected wavelength of the gouting or aligning the optical axes of the lasers.

In the third aspect of the invention, the band-narrowing element is surrounded by a case, and a window through which the alignment laser light is transmitted is provided on the back side of the mirror in the case.

[0008]

According to the above structure, the alignment laser light is transmitted between the laser chamber and the grating, and
A mirror for totally reflecting the output laser light is arranged, and the alignment laser light can be introduced through the mirror in alignment with the optical axis of the output laser light. The optical axis of can be adjusted easily and surely.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a narrow band oscillation laser device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall configuration diagram showing a first embodiment of a narrow band oscillation excimer laser device of the present invention. In FIG. 1, a narrow band oscillation excimer laser device includes a front mirror 1, a laser chamber 10 for oscillating a laser, visible light, and
A mirror 3 coated with a dielectric film that totally reflects the excimer light; a band-narrowing device 20 that band-narrows the laser;
An alignment laser device 30 for alignment, which is inserted between the laser chamber and the grating via a mirror so as to be substantially aligned with the optical axis of the output laser light.

The laser chamber 10 is filled with a laser gas containing KrF or the like so as to be able to circulate, and an electrode (not shown) and a window 1 for exciting the laser gas.
It consists of 1 and 12 and a chamber 13. The band-narrowing device 20 includes the first prism beam expander 2
1 and a grating 25. The first prism beam expander 21 is the first prism 21a.
And a second prism 21b. The band narrowing method is a method in which the prism beam expander 21 and the grating 25 are combined, and the grating 25 is arranged in a Littrow arrangement.

The alignment laser device 30 comprises an alignment laser oscillator 31 and mirrors 32 and 33. The alignment laser (A) outputs an output laser beam via the mirror 3 between the laser chamber 10 and the grating 25. Insert it so that it substantially coincides with the optical axis of (B). As an example of the visible light laser for alignment, a helium neon laser, a semiconductor laser, an argon laser, or the like is used.

Next, the operation of the above embodiment will be described. The excimer light discharge-excited in the laser chamber 10 is totally reflected by the mirror 3 of the band-narrowing device 20, and after the laser is band-narrowed by the first prism beam expander 21 and the grating 25, the mirror 3 is formed. Is totally reflected by and is output from the front mirror 1. At this time,
Via a mirror 3 which is arranged between the laser chamber 10 and the grating 25 and totally reflects the output laser light,
The alignment laser light output from the alignment laser oscillator 31 of the alignment laser device 30 passes through the mirrors 32 and 33 and is substantially aligned with the optical axis of the output laser light (B) from the mirror 3 that transmits the alignment laser light. To insert. Thus, even if a grating is used as the band narrowing element, the optical axis of the output laser light can be adjusted easily and surely.

FIG. 2 is an overall configuration diagram showing a second embodiment of the narrow band oscillation excimer laser device of the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Second
A band-narrowing device 40 for band-narrowing the laser of the embodiment includes a first prism beam expander 41, a second prism beam expander 42, a grating 25, and
It consists of First prism beam expander 4
Reference numeral 1 includes a first prism 41a and a second prism 41b. The band narrowing method is a method in which the prism beam expander 21 and the grating 25 are combined, and the grating 25 is arranged in a Littrow arrangement.

The mirror 3 is provided with an angle adjusting mechanism 50 for changing the selected wavelength of the grating or for matching the optical axis of the laser light. The angle adjusting mechanism 50 includes
A motor 51 for changing the angle of the mirror 3 is provided, and the motor 51 swings the mirror 3 in response to a command from a control device such as a controller (not shown). Also,
A handle or a drive mechanism such as a gear may be provided on the mirror 3 to adjust the angle manually.

In the above embodiment, the mirror for introducing the alignment laser beam changes the selected wavelength of the gouting or the optical axis of the laser is made to coincide with each other, so that it is very compact and the wavelength control of the laser is high. It becomes a device with high accuracy and high speed that can easily take the optical axis of the output laser light.

FIG. 3 is an overall configuration diagram showing a third embodiment of the narrow band oscillation excimer laser device of the present invention. The same parts as those in the first and second embodiments are designated by the same reference numerals and will be described. Omit it. In the third embodiment, the band narrowing device 40 that narrows the band of the laser is surrounded by the housing device 60. The housing device 60 is composed of a housing 61, a window 62 arranged behind the illustrated rear surface of the mirror 3, and a pipe 63 for supplying clean gas into the housing, and the housing on the window 12 side of the laser chamber 10 is provided. One end 61a of 61 is opened,
The housing 61 is in contact with and mounted on the laser chamber 10.

Next, in the above-mentioned embodiment, the inlet of the clean gas pipe 63 is arranged on the back side of the grating 25, and the groove surface of the grating 25 is provided with the inside of the housing and the optical path without causing gas flow. Filled with clean gas, the life of the band-narrowing element can be significantly extended. The alignment laser light output from the alignment laser oscillator 31 of the alignment laser device 30 is
The output laser light (B) is transmitted from the mirror 3 which passes through the mirrors 32 and 33 and enters the inside of the housing 61 from the window 62 arranged on the rear surface of the mirror 3 in the drawing, and transmits the alignment laser light. Insert so that it is almost aligned with the axis. Thus, even if a grating is used as the band narrowing element, the optical axis of the output laser light can be adjusted easily and surely.

[0018]

As described above, according to the present invention,
Even when a grating is used as a band-narrowing element, the alignment laser light can be introduced from the rear side, so the chamber position can be accurately determined when installing or replacing the laser chamber, and the alignment of the front mirror can be done very easily. . Further, the optical axis between the laser and the exposure device can be easily taken by the alignment laser light. The mirror for introducing the alignment laser light is extremely compact because it is equipped with an angle adjustment mechanism to change the selected wavelength of gouting or to match the optical axis of the laser, and the wavelength control of the laser is highly accurate and high-speed. ,
The device can easily take the optical axis of the output laser light. By enclosing the band-narrowing element in a housing and installing a window that allows the alignment laser light to pass through on the back side of the mirror and filling the housing with clean gas, the life of the band-narrowing element can be dramatically extended. It can emit alignment laser light.

[Brief description of drawings]

FIG. 1 shows a first narrow band oscillation excimer laser device of the present invention.
The whole block diagram which shows an Example.

FIG. 2 is a second narrow band oscillation excimer laser device of the present invention.
The whole block diagram which shows an Example.

FIG. 3 is a third example of the narrow band oscillation excimer laser device of the present invention.
The whole block diagram which shows an Example.

FIG. 4 is an overall configuration diagram of a conventional narrow band oscillation excimer laser device.

[Explanation of symbols]

1 Front Mirror 61 Housing 3 Mirror 62 Window 10 Laser Chamber 11, 12 Window 12 Chamber 20, 40 Narrowing Band 21, 41 Prism Beam Expander 25 Grating 30 Alignment Laser Device 31 Alignment Laser Oscillator 32, 33 Mirror 50 Angle Adjustment Mechanism 51 Motor 60 Enclosure device

Claims (3)

[Claims] 1. In a narrow band laser in which at least a grating is arranged as a narrow band element, at least one mirror is arranged between the grating and the laser chamber, and the mirror totally reflects the output laser light to generate the alignment laser light. A narrow-band oscillation laser device comprising means for introducing an alignment laser beam through a mirror so that the alignment laser beam is approximately aligned with the optical axis of the output laser beam through a mirror. 2. The narrow band oscillation laser device according to claim 1, wherein the mirror is provided with an angle adjusting mechanism for changing the selected wavelength of the gouting or matching the optical axis of the laser. 3. The narrow band oscillation laser device according to claim 1, wherein the narrow band element is surrounded by a housing, and a window through which alignment laser light is transmitted is provided on the back side of the mirror in the housing.