JPH0312605A - Multi-layered film mirror reflecting two-wavelength of ultraviolet-light and visible-light - Google Patents

Abstract

PURPOSE:To reflect ultraviolet rays and a visible light beam with waveform for alignment efficiently and transmit heat rays by reflecting light in the ultraviolet wavelength range and transmitting light from the visible wavelength range to the infrared wavelength range by a 2nd thin layer group, and reflecting light in the visible-light wavelength range and transmitting light in the infrared wavelength range by a 1st thin layer group. CONSTITUTION:The 2nd thin layer group 2 reflects the light in the infrared wavelength range including wavelength lambda0 for working as UV light and transmits the light from the visible wavelength range to the infrared wavelength range by the spectral characteristics of a low-pass filter having center wavelength lambda0 of its nontransmission band. The light transmitted through the 2nd thin layer group 2 is made incident on the 1st thin group 1, which reflects the light the visible wavelength range including the wavelength for alignment as VIS light and transmits the light in the infrared wavelength range including heat rays by the spectral characteristics of a low-pass filter having center wavelength lambdae' of its nontransmission band. Consequently, heat rays are not reflected and the ultraviolet rays with the wavelength for working and the visible light beam with the wavelength for alignment can be reflected efficiently.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an ultraviolet light beam that reflects a beam in the ultraviolet wavelength range and a beam in the visible wavelength range, but transmits heat rays without reflecting them.
This invention relates to a visible dual-wavelength reflective multilayer mirror.

(Prior art and its problems) Currently, IJ lithography, X-ray phosphorography, electron beam phosphorography, etc. are used for processing VLSI devices. In particular, the deep ultraviolet exposure method is a technology that is an extension of conventional photolithography. According to this technology, a photoresist is exposed to deep ultraviolet light with a wavelength of 200 to 300 nm, and a pattern of 1 μm or less on a reticle is formed on a silicon wafer. can be transferred onto. A mirror optical system using an X;e-Hg lamp as a light source is used to bake the photoresist. The mirror used in this illumination system has a protective film of aluminum and magnesium fluoride deposited on it, and its spectral reflection characteristics are shown in FIG.

As shown, the A1 mirror with MgF2 protective film is
It has a reflectance of about 90% in the ultraviolet region and about 80% in the visible near-infrared region.

Therefore, there is a problem in that the heat rays contained in the beam reflected by this mirror cause an increase in the temperature of the silicon wafer, resulting in a decrease in the accuracy of the transferred pattern. Furthermore, metal films such as aluminum used in such mirrors have a disadvantage in that they have lower resistance to ultraviolet rays contained in radar light than dielectric films.

Therefore, various cold mirror-type ultraviolet reflecting mirrors made of dielectric multilayer films have been proposed as mirrors that do not reflect such heat rays and are highly resistant to ultraviolet irradiation.

For example, in Patent Application Publication No. 60-38681,
In an ultraviolet multilayer film consisting of a high refractive index dielectric layer that absorbs in the ultraviolet region, and a high refractive index dielectric layer and a low refractive index dielectric layer that do not absorb in the ultraviolet region, the width of the reflection band that appears in the ultraviolet wavelength region It is effective to use a high refractive index dielectric material that absorbs in the ultraviolet region in order to expand the
It has been pointed out that it is effective to provide on the substrate side a thin layer group consisting of the above-mentioned high refractive index dielectric layer that absorbs in the ultraviolet region and a low refractive index 17<Ti body layer that does not absorb in the ultraviolet region. There is.

Further, the spectral characteristics of a cold mirror consisting of alternating layers of high refractive index AM layers and low refractive index dielectric layers that do not absorb in the ultraviolet region are illustrated in FIGS. 6 and 7.

FIG. 6 is a spectral reflectance curve of a cold mirror designed to reflect the 365r++nO1 line.

Figure 7 shows the 24 oscillated from the KrF excimerode.
This is a spectral reflectance curve of a cold mirror designed to reflect 9 nm ultraviolet light. These reflectance curves were created by calculating the reflectance of each dielectric multilayer mirror having the following configuration. In addition,
The angle of incidence on the mirror was 45@, and the reflectance was the average of the P and S components of the reflected light.

The cold mirror shown in FIG. 6 has a basic periodic layer of ((H/2)L (H/2)),
A long-pass filter type periodic multilayer film with a periodicity of 12 is laminated on a substrate.

The center wavelength of the stop band (opaque band) of this long-pass filter is λ. Then, (H/2') is λ. It is a thin film of ZrO2, which is one of the high refractive index dielectrics with no absorption in the ultraviolet region, and has a film thickness of λc/8. L is λ
. It is a thin film of SlO□, which is one of the low refractive index dielectrics with no absorption in the ultraviolet region, and has a film thickness of λc/4.

Note that the center wavelength λ6 is selected to be 400 nm.

The cold mirror shown in FIG. 7 has a basic periodic layer of ((H/2)L (H/2)),
A long-pass filter type periodic multilayer film with a periodicity of 15 is laminated on a substrate.

The center wavelength of the stop band of this long-pass filter is λ. Then, (H/2) is λ. A high refractive index dielectric material with no absorption in the ultraviolet region and having a film thickness of λc/8 in
It is a thin film of Y2O, which is L is λ. to the right of λc
This is a thin film of MgF, which is one of the low refractive index dielectrics that does not absorb in the ultraviolet region, and has a film thickness of 1/4. In addition, the above-mentioned center wavelength λ. is selected to be 275 nm.

As mentioned above, photoresist is exposed using ultraviolet light when processing VLSI devices, but it is convenient to use visible light to align the optical system for this purpose, and in fact, it is convenient to use visible light for optical system alignment. I often do this.

However, the multilayer film described in the cited patent publication and the cold mirror with the configuration shown in Figures 6 and 7 do not reflect visible light, so visible light cannot be used as alignment light. There were drawbacks.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and its purpose is to efficiently reflect ultraviolet rays at the wavelength for processing and visible light at the wavelength for alignment, and to have an effect on the processing. Ultraviolet light that transmits heat rays without reflecting them.
An object of the present invention is to provide a visible dual-wavelength reflective multilayer mirror.

Another object is to make it possible to manufacture an ultraviolet/visible dual-wavelength reflective multilayer mirror with a dielectric multilayer film that has higher resistance to ultraviolet rays of laser light than an Aβ mirror and has high reflection efficiency.

Another objective is to create an ultraviolet/visible dual-wavelength multilayer mirror that has a high reflection efficiency for light in the visible wavelength range, including alignment wavelengths, by laminating a relatively small number of multilayer films on a substrate. It is to do so.

(Means for Solving the Problems) In order to achieve the above object, in the ultraviolet/visible dual-wavelength reflective multilayer mirror of the present invention, a high refractive index dielectric layer that absorbs in the ultraviolet wavelength region and a high refractive index dielectric layer that absorbs in the ultraviolet wavelength region and A first thin layer group in which low refractive index dielectric layers with no absorption are arranged alternately; A second thin layer group in which body layers are alternately arranged is provided in contact with the medium (air), and the second thin layer group reflects light in the ultraviolet wavelength range including the processing wavelength, and reflects light in the visible wavelength range. The first thin layer group transmits light in the infrared wavelength range, and reflects light in the visible wavelength range including the alignment wavelength,
It may be configured to transmit light in the infrared wavelength range.

In addition, in order to realize an ultraviolet/visible dual-wavelength reflective multilayer mirror that consists of a relatively small number of layers and has high reflection efficiency for light in the visible wavelength range including the alignment wavelength, the above-mentioned first
interposing a third thin layer group between the thin layer group and the second thin layer group;
The third thin layer group is composed of alternating high refractive index dielectric materials having absorption in the ultraviolet wavelength region and low refractive index dielectric materials having no absorption in the ultraviolet wavelength region, and furthermore, the third thin layer group is formed in the ultraviolet wavelength range including the processing wavelength. It is configured to reflect light in a wavelength range and transmit light ranging from a visible wavelength range to an infrared wavelength range.

(Principle of the Invention) As shown in FIG. 1, the basic configuration of the ultraviolet/visible dual-wavelength reflective multilayer mirror of the present invention is that a first thin layer group 1 is provided on the substrate S side, and the first thin layer group A second group of thin layers 2 is provided on the substrate 1 in contact with the medium (air).

The second thin layer group 2 has a film structure of C(H/2) L(H/
2)] ” and I: (H/2)L (H/2)]
It is a long-pass filter type periodic multilayer film in which the basic periodic layer is n' and the number of periods is n'.

The center wavelength of the passband (opaque band) of this long-pass filter is λ. Then, (H/2) is λ.

A high refractive index dielectric having a film thickness of λc/8 and having no absorption in the ultraviolet region (for example, 8A, 03, Th[]□,
Y2O3, 1ife, Sc, 03, etc.) thin layer n8. L is a low refractive index dielectric with no absorption in the ultraviolet region (for example, MgF, 5
n1.in2, LiF, ThF, etc.). It is. Processing wavelength λ in the ultraviolet wavelength range. The wavelength close to is the center wavelength λ above.

The selection will be made as follows.

The first thin layer group 1 has a film structure of ((H'/2)L'
(H'/2)・]0, and C(H'/2)L'
It is a long-pass filter type periodic multilayer film in which the fundamental periodic layer is (H'/2)) and the number of periods is n. The center wavelength of the stop band (opaque band) of this long-pass filter is λ. ', then (H'/2) is λ. λ at ′. '/8 high refractive index dielectric that absorbs in the ultraviolet region (e.g. Tie, Ta205, Zn
S, etc.) thin film nH'. L' is λ. λ at ′
. '/4 low refractive index dielectric with no absorption in the ultraviolet region (e.g. MgF2, slo, LiF 5Th
F, etc.) is a thin layer nL.

Alignment wavelength λ in the visible wavelength range. ' is the center wavelength λ above. ’.

Here, the center wavelength λ of the second thin layer group. The machining frequency λ is
. and the center wavelength λ of the second thin layer group. The alignment wavelength λ is Let M be the ratio with '.

The second thin layer group 2 is λ. Due to the spectral characteristics of a long-pass filter having λ as the center wavelength of the opaque band, the center wavelength λ of the incident light from the light source.

The processing wavelength λ is selected to be close to . As shown in FIG. 1, the light in the ultraviolet wavelength range, including , is reflected as UV light, and the light ranging from the visible wavelength range to the infrared wavelength range is transmitted. The light transmitted through the second thin layer group 2 enters the first thin layer group 1. The first thin layer group 1 is λ. Due to the spectral characteristics of a long-pass filter having ` as the center wavelength of the opaque band, the center wavelength λ of the incident light is determined by the spectral characteristics of the long-pass filter. The alignment wavelength λ is selected as the wavelength that matches ′. As shown in FIG. 1, light in the visible wavelength range including ' is reflected as VIS light, and light in the infrared wavelength range including heat rays is transmitted. Therefore, the multilayer mirror shown in FIG. 1 has a processing wavelength λ. and alignment wavelength λ. ′ is reflected, but light in the infrared wavelength range, including heat rays, is transmitted without being reflected.

Referring to FIG. 1, since the ultraviolet rays contained in the incident light from the light source are sufficiently reflected at the interface between the second thin layer group 2 and the medium (air), Almost no ultraviolet rays penetrate, and the radiation resistance to ultraviolet rays is high. By the way, as already mentioned, the laser resistance of metal films such as AI is inferior to that of dielectric films.

Therefore, the multilayer mirror shown in FIG. 1 has superior laser resistance compared to metal mirrors such as L.

Based on the two facts mentioned above, the dielectric multilayer film with the basic configuration shown in Figure 1 has higher resistance to ultraviolet rays from laser light than the F2 mirror, and a dual-wavelength reflective multilayer mirror for ultraviolet and visible wavelengths with high reflection efficiency. It turns out that it is possible to realize.

(Example) FIG. 3 shows S/M [: (H'/2)L' (H
' /2))8 [()! /2)L (H/2> )”
FIG. 3 is a diagram showing a spectral reflectance curve of an ultraviolet/visible dual-wavelength reflective multilayer mirror having a configuration of /I. Here, H: Tl
O2, H: ZrO2, L' = L: 5iO7, M; Processing wavelength λ. and the alignment wavelength λ = 1.73.

This curve was drawn by calculating the average of the P component and S component of the reflected light as the reflectance, assuming that the angle of human incidence on the mirror is 45 degrees. In the above configuration, S represents the substrate, ■ represents the medium (air), and 1.73 [(H'/2)L' (
H'/2))' represents the film structure of the first thin layer group 1, and ((H/2)L (H/2)) 12 represents the film structure of the second thin layer group 2.

The first thin layer group 1 has a film structure of C(H'/2)L'
(H'/2):l'', and ((H'/2)L'
(H'/2)] is a basic periodic layer, and the number of periods is 8. It is a long-pass filter type periodic multilayer film. The center wavelength of the stop band (opaque band) of this long-pass filter is λ. ', then (H'/2) is λ. '/8
It is a high refractive index dielectric layer TiO□ which has a film thickness of , and has absorption in the ultraviolet wavelength region, and L is λ. λ at ′. '/4 low refractive index dielectric layer S with no absorption in the ultraviolet region
It is lO□. Alignment wavelength λ in the visible wavelength range
.

=633nm is the center wavelength λ. ’.

The second thin layer group 2 has a film structure of C(H/2) L(H/
2>)", and ((H/ 2) L (H/ 2')
] is a basic periodic layer, and the number of periods is 12. It is a long-pass filter type periodic multilayer film. The center wavelength of the stop band (opaque band) of this long-pass filter is λ. Then, (H/2) is λ. A high refractive index dielectric layer 2r having a film thickness of λc/8 and having no absorption in the ultraviolet region.
O, and L is λ. This is a low refractive index dielectric layer S10□ having a film thickness of λc/4 and having no absorption in the ultraviolet region. λ. = wavelength λ close to 365 nm. =400 nm is selected as the center wavelength.

As is clear from FIG. 6, the film structure of the second thin layer group 2 of the embodiment shown in FIG. 3 is the same as that of the cold mirror shown in FIG. Therefore, in the ultraviolet/visible dual-wavelength reflective multilayer mirror of this example, after first laminating the first thin layer group 1 and [(H'/2)L'(H'/2)) 8 on the substrate S, , the second thin layer group 2 having the same film structure as the cold mirror shown in FIG. 6, ((H/2)L (H
/2) It can be seen that it was obtained by laminating E'2.

The second thin layer group 2 having such a film configuration C (H/2) The light is reflected as UV light, and the light ranging from the visible wavelength band to the infrared wavelength band is transmitted.The light that has passed through the second thin layer group 2 has a film structure of C(H'/2)L'(H'/2))", which has an alignment wavelength λ. It reflects light in the visible wavelength range including =633 nm as VIS light, and transmits light in the infrared wavelength range including heat rays. Therefore, the multilayer mirror of this embodiment, which is composed of the first thin layer group 1 and the second thin layer group 2 laminated on the substrate S, has the processing wavelength λ. = 365 nm and alignment wavelength λ. = 633 nm, but light in the infrared wavelength range including heat rays is transmitted without being reflected.

Figure 4 shows S/2.54 ((H' /2) L'
(H'/2) ] 8 ((H/2) L (H/2) ]
FIG. 3 is a diagram showing a spectral reflectance curve of an ultraviolet/visible dual-wavelength reflective multilayer mirror having a configuration of +5/I. This curve assumes that the angle of incidence on the mirror is 45°, and the P component and S component of the reflected light are
The average of the components is calculated and drawn as the reflectance. In the above configuration, S represents the substrate, I represents the medium (air), and 2
．． 54 ((H' /2) L'(H'/2))'' is the film configuration of the first thin layer group 1, and [: (H/2)L
(H/2)]” represents the film configuration of the second thin group 2.

The first thin layer group 1 has a film structure of ((H'/2)L'
(H'/2))" and ((H'/2)L'(H
It is a long-pass filter type periodic multilayer film in which the basic periodic layer is '/2)) and the number of periods is 8. If the center wavelength of the stop band (opaque band) of this long-pass filter is λ,', then (H'/2) is λ. It is a high refractive index dielectric layer TlO2 having a film thickness of '/8 and absorbing in the ultraviolet wavelength region, and L' is λ. λ at ′. '/4 low refractive index dielectric layer S with no absorption in the ultraviolet region
It is lO□. Alignment wavelength λ in visible wavelengths.

' = 633 nm is the center wavelength λ. ’.

The second thin layer group 2 has a film structure of C(H/2) L(H/
2) 〕” and C(H/2)L (H/2)〕
It is a long-pass filter type periodic multilayer film with 15 as a basic periodic layer and 15 periods.

The center wavelength of the stop band (opaque band) of this long-pass filter is λ. Then, (H/2) is λ. is a high refractive index dielectric layer Y2O3 having a film thickness of λc/8 and having no absorption in the ultraviolet region, and L is λ. λc at
This is a low refractive index dielectric layer MgF2 having a film thickness of /4 and having no absorption in the ultraviolet region. Wavelength λ close to λ0=249r++n. =275 nm is selected as the center wavelength.

As is clear from FIG. 7, the film structure of the second thin layer group 2 of the embodiment shown in FIG. 4 is the same as that of the cold mirror shown in FIG. Therefore, in the ultraviolet/visible three-wavelength multilayer mirror of this embodiment, first the first thin layer group 1 is placed on the substrate S.
．． 2.54 C(H'/2)L'(H'/2)
) 8, the second thin layer group 2, ((H/2
)L (H/2)] 15 was laminated.

Such a film configuration [: (H/2)L(H/2)) 1
The second thin layer group 2 having a
Processing wavelength λ. = U light in the ultraviolet wavelength range including 2491 m
It is reflected as V light and transmits light ranging from the visible wavelength range to the infrared wavelength range. The light transmitted through the second thin layer group 2 has a film structure ((H'/2)L'(H'/2))'
The first thin layer group 1 reflects light in the visible wavelength range including the alignment wavelength λ, ' = 633 nm as vIS light, and also reflects light in the infrared wavelength range including heat rays. Allows light to pass through the area. Therefore, the multilayer mirror of this embodiment, which is composed of the first thin layer group 1 and the second thin layer group 2 laminated on the substrate S, has a processing wavelength λ. = 249 nm and alignment wavelength λ. '=633 nm is reflected, but light in the infrared wavelength region including heat rays is transmitted without being reflected.

Next, regarding the second embodiment, which is a modification of the first embodiment, the second embodiment will be described.
This will be explained with reference to FIGS. 8, 8, and 9.

A modified configuration of the ultraviolet/visible dual-wavelength reflective multilayer mirror of the present invention is as shown in FIG.
A third thin layer group 3 is interposed between them.

The second example has the film configuration S/M ((
H'/2)L'(H'/2))" ((H/2)
L(H/2)] ” /I, the second thin layer group [(H/2
) L(H/2)) ” as the third thin layer group [(H′/
2) L'/2))' and C(H/2) L (H/2) which has the same structure as the second thin layer group shown in the first example but has a smaller number of layers.
)". In other words, the film structure is S/M
I: (H'/2)L'(H' /2)] ”((
)('/2)L'/2>) 1 [(H/2)L
(H/2)L'(H'
/2):l” is ((H'/2)L'(H' /
2): This is a periodic long-pass filter having the basic configuration of 1. Here, (H'/2) is the center wavelength λ of the bandpass. A high refractive index dielectric material having a film thickness of λc/8 and absorbing in the ultraviolet region (e.g., TiO2, Ta, Os, ZnS
etc.), and L is λ as before. λ at ′.

It is a low refractive index dielectric with no absorption in the ultraviolet region and has a film thickness of /4.

With this configuration, for example, (H'/2),
By replacing TiO2 (n = 2.35) with Y2O3 (n = 1.90), which is a typical example of (H'/2), a large refractive index difference can be achieved in the third thin layer group, resulting in similar ultraviolet reflection. The number of thin layers required in the first embodiment can be smaller than that required in the first embodiment to obtain the desired ratio.

FIG. 8 is a modification of the first embodiment shown in FIG.
/1.73 [(H'/2)L'(H' /2))
'(H'/2)L'(H'/2))' ((
H/2)L (H/2)]
FIG. 3 is a diagram showing a spectral reflectance curve of a visible two-wavelength reflective multilayer mirror. This curve was drawn by setting the incident angle to the reflecting mirror at 45 degrees and calculating the average of the P component and S component of the reflected light as the reflectance. Processing wavelength λ.

shall be 400 nm.

FIG. 9 relates to a modification of the first embodiment shown in FIG.
)'C(H'/2)L'(H' /2)] '
((H/2>L (H/2))' is a diagram showing a spectral reflectance curve of an ultraviolet/visible dual-wavelength reflective multilayer mirror having the configuration. This reflectance curve was obtained under the same conditions as in FIG. The processing wavelength λ is 275 nm.

In the embodiment detailed above, the basic configuration, S/M ((H
'/2. )L'(H'/2>' ((H/2
)L (H/2))” /I, or modified configuration, S /
MC(H'/2)L'(H'/2)" [(
H' /2) L'(H'/2)]' C (H/2)
L (H/2))”/■, each thin layer group is C(H/2)”/■.
2) Although it was designed to be a long-pass filter type multilayer mirror with a fundamental periodic layer of L (H/2)], each thin layer group has a fundamental period of C(H/2)L (H/2)). Alternatively, each thin layer group may be a λ/4 type alternating layer multilayer mirror with a fundamental periodic layer of (HL). It is also possible to

In addition, to improve laser resistance, we added (
2L) dielectric thin films may be laminated.

Furthermore, instead of configuring the dielectric multilayer mirror as a two-wavelength reflecting mirror as in this embodiment, a dielectric multilayer mirror configured by appropriately adjusting the number of periods n', m, and m' of the basic periodic layer may be used. The multilayer mirror works as a normal mirror in the ultraviolet wavelength range, and as a half mirror in the visible wavelength range.
It is also possible to make it work as

(Effects of the Invention) Since the present invention is configured as described in detail above, it is possible to efficiently reflect ultraviolet rays having a processing wavelength and visible light rays having an alignment wavelength without reflecting heat rays. Therefore, it can be effectively used in the processing of ultra-LSI and LSI devices where the processing accuracy of samples may be impaired by thermal effects, and in applications such as biochemical reactions and ophthalmic surgery where cells may be destroyed by thermal effects. is possible.

Further, according to the present invention, it is possible to manufacture an ultraviolet/visible dual-wavelength reflective multilayer mirror that has higher resistance to ultraviolet rays of laser light than a metal mirror such as Al, and has high reflection efficiency.

Further, according to the present invention, by laminating a relatively small number of dielectric multilayer films on a substrate, the ultraviolet/visible dual-wavelength reflective multilayer film has a high reflectance of light in the visible wavelength range including the alignment wavelength. It becomes possible to realize a mirror.

[Brief explanation of drawings]

Fig. 1 shows the basic structure of the multilayer mirror of the present invention, Fig. 2 shows a modified structure, and Fig. 3 shows i-line (365 nm).
and He-Ne gas L/-day oscillation light (633r+n+
), Figure 4 shows the spectral characteristics of a two-wavelength cold mirror that reflects KrF excimer laser oscillation light (249
nm) and He-Ne gas radar oscillation light (633 nm)
), Figure 5 is a diagram showing the spectral characteristics of an Al mirror with a protective film conventionally used as an ultraviolet mirror, and Figure 6 is a diagram showing the spectral characteristics of a conventional i-line (365 nm) mirror. ), and FIG. 7 is a diagram showing the spectral characteristics of a conventional cold mirror for KrF excimer radiation (249 nm).
FIG. 8 is a diagram showing the spectral characteristics of a modified example of the one shown in FIG. 3, and FIG. 9 is a diagram showing the spectral characteristics of a modified example of the first embodiment shown in FIG. 4. ■...First thin layer group 2...Second thin layer group 3...Third thin layer group S...Substrate T
...Medium nH'...High refractive index dielectric layer nL that has absorption in the ultraviolet region...Low refractive index dielectric layer n that has no absorption in the ultraviolet region,... ...High refractive index dielectric layer λ with no absorption in the ultraviolet region.・・・・・・Processing wavelength λ.・・・・・・Engraving of the wavelength diagram for alignment (no changes to the content) Figure 1 Figure 2 Date of Heisei

Claims (2)

[Claims] (1) On the substrate side, a first thin layer group in which high refractive index dielectric layers having absorption in the ultraviolet wavelength range and low refractive index dielectric layers without absorption are arranged alternately, and the first thin layer group A second thin layer group in which high refractive index dielectric layers and low refractive index dielectric layers, both of which have no absorption in the ultraviolet wavelength range, are arranged alternately is provided on top in contact with the medium, and the second thin film group is used for processing. The first thin layer group reflects light in the visible wavelength range including the alignment wavelength and transmits light in the visible wavelength range to the infrared wavelength range. An ultraviolet/visible dual-wavelength reflective multilayer mirror configured to transmit light in an outside wavelength range. (2) A third thin layer group is interposed between the first thin film group and the second thin film group, and the third thin layer group includes a high refractive index dielectric layer having absorption in the ultraviolet wavelength region and a high refractive index dielectric layer having absorption in the ultraviolet wavelength region. and low refractive index dielectric layers, and the third thin layer group reflects light in the ultraviolet wavelength range including the processing wavelength, and reflects light ranging from the visible wavelength range to the infrared wavelength range. The ultraviolet/visible dual-wavelength reflective multilayer mirror according to claim 1, which is configured to transmit.