JPH04190200A - Multiple layer film mirror for vacuum ultra-violet region and its fabrication - Google Patents

Abstract

PURPOSE:To enable realization of high reflection rate and easy fabrication by repeating overlay of optical crystal films transparent for vacuum ultra-violet light and dispersed reflection layers where evaporation particles of metal with high reflection rate is dispersed very thin one by one. CONSTITUTION:A multi-layered mirror 14 with the thickness of 1/2lambda is constituted of optical crystal films 11 transparent for vacuum ultra-violet light and dispersed reflection layers 13 where evaporation particles 12 of metal with high reflection rate is dispersed very thin and multiple layers are formed by repeating overlaying the crystal film 11 and the reflection layer 13 one by one like the mirrors 15, 16.... When an ultra-violet light with the wavelength lambda of below 200nm comes in the multiple layers mirror, the light having penetrated the first layer crystal film 11 and reached the particles in the reflection layer 13, almost reflects and partly penetrates the particles 12. As the particles 12 are dispersed very thin, very little light penetrates because of very thin particles 12 layer. When light penetrates in between particles 12 the light wave the comes uniform due to minimum gaps d. The light having penetrated the first layer repeats reflection and operation below the second layer in the same phase. As the light reflected by each mirror layer gathers to be reflection light, the reflection rate is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multilayer mirror for use in the vacuum ultraviolet region with a wavelength shorter than 2000 rA, and a method for manufacturing the same, which cannot be manufactured by the conventional method using two transparent optical crystals. We have realized a multilayer mirror in this wavelength range, which was previously unavailable, and made it possible to easily manufacture it.

[Conventional technology]

In recent years, synchrotrons have been developed as relatively small particle accelerators with a diameter of 10ff1 or less, and synchrotron radiation (SOR light) can be used in a wide range of fields, from infrared and visible to X-rays. There is spectroscopic research in the vacuum ultraviolet light region that uses SOR light with a continuous spectrum over a wide range, which has solved the problem of not being able to obtain a stable continuous light source and is making dramatic progress.

Since this vacuum ultraviolet light region is more strongly absorbed by air than the visible and ultraviolet light regions, the optical system including the light source must be placed in a vacuum, and a window that transmits vacuum ultraviolet light of 1100 nm or less must be installed. Because of the lack of materials, the optical system often has to be constructed with a reflective optical system rather than a transmissive one.

In order to make this reflective optical system highly efficient, a mirror with high reflectance is required, and a multilayer mirror is well known as a mirror with high reflectance.

Currently, multilayer mirrors for use outside of this vacuum ultraviolet light region are
Different types of optical crystals are repeatedly stacked to form multiple layers, and the light that passes through the upper layer without being reflected is reflected by the next layer, increasing the reflectance.

[Problem to be solved by the invention]

However, in the vacuum ultraviolet region, the same 2
There is a problem in that a multilayer mirror with high reflectance cannot be manufactured using a method in which different types of optical crystal films are repeatedly stacked to form a multilayer film.

On the other hand, some mirrors that are said to have a high reflectance in the vacuum ultraviolet region use a metal film such as aluminum, but even if you try to make a uniform film of aluminum by vapor deposition, the thickness is at least 10 nm. However, with a metal film of this thickness, most of the light that passes through the upper layer is absorbed, and even with a multilayer mirror, there is a problem that it is not possible to improve the reflection efficiency by reflecting from the next layer. be.

The second invention solves the problems in the prior art,
The present invention aims to provide a multilayer mirror for the vacuum ultraviolet region that can be easily produced, and a method for manufacturing the same.

[Means to solve the problem]

The multilayer mirror for use in the vacuum ultraviolet light region of the second invention consists of alternately repeating an optical crystal film transparent to vacuum ultraviolet light and a dispersed reflection layer in which vapor-deposited particles of a highly reflective metal material are dispersed extremely thinly. It is characterized by having multiple layers.

In addition, in the method for manufacturing a multilayer mirror for use in the vacuum ultraviolet light region of the present invention, when manufacturing a multilayer film mirror for use in the vacuum ultraviolet light region, vapor-deposited particles of a metal material with high reflectance are extremely applied to the surface of a transparent optical crystal film. The present invention is characterized in that after the optical crystal film is thinly dispersed to form a dispersed reflective layer, the optical crystal film and the dispersed reflective layer are repeatedly formed to form a multilayer.

[For production]

According to the multilayer mirror for vacuum ultraviolet light region of this invention,
A transparent optical crystal film made of a compound of MgF, CaF2, etc., and a dispersed reflection film made by depositing and dispersing ultrathin vapor-deposited particles of a metal material such as aluminum with a particle size of, for example, lnlIi degrees. This is repeated alternately to form a multilayer mirror, and even in the vacuum ultraviolet light region, light is directly reflected by the dispersed reflection layer, and light is transmitted between and inside the vapor deposited particles to form the next layer of the dispersed reflection layer. By utilizing the light reflected by the vapor deposited particles, the light that is not reflected is transmitted between the vapor deposited particles, thereby suppressing light absorption as much as possible and improving the reflection efficiency.

Further, according to the method of manufacturing a multilayer mirror for use in the vacuum ultraviolet region of the present invention, a transparent optical crystal film such as a compound such as MgF2 or CaF2 is coated with a metal material such as aluminum having a particle size of, for example, about 1 nm. By depositing and dispersing vapor-deposited particles extremely thinly to form a dispersed reflective film, and by alternately repeating this transparent optical crystal film and a dispersed reflective film made of a metal material to form a multilayer mirror, it is possible to achieve even in the vacuum ultraviolet light region. The absorption of light transmitted through the dispersed reflection layer is suppressed as much as possible to improve reflection efficiency.

Therefore, these multilayer mirrors can be used for spectroscopic research in the vacuum ultraviolet region and as a highly efficient reflection system for free electron lasers.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of a multilayer mirror for use in the vacuum ultraviolet region of the present invention.

This multilayer mirror for vacuum ultraviolet light region] 0 is made of a metal material with high reflectance such as aluminum, but its thickness is l
Based on the idea that if the thickness could be reduced to about nanometers, it would become a reflective film that could minimize the absorption of light in the vacuum ultraviolet region during transmission, and could be applied to multilayer mirrors. Instead of forming a uniform film, we use a dispersed reflective film that is dispersed into islands.

As shown in FIG. 1, this multilayer mirror 10 for use in the vacuum ultraviolet light region includes an optical crystal film 1 that is transparent to vacuum ultraviolet light with a wavelength shorter than 200 nm and vapor-deposited particles 12 of a highly reflective metal material. One layer of the mirror 14 is composed of the dispersed reflection layer 13 in which the optical crystal film 11 and the dispersed reflection layer 13 are dispersed in an extremely thin layer, and the optical crystal film 11 and the dispersed reflection layer 13 are alternately repeated to form a multilayer, and the mirrors 15, 16, and so on of each subsequent layer are formed. ...is configured.

This optical crystal film 11 may be made of, for example, MgF2 or Ca.
It includes a compound such as F2, and is formed by forming a film using a C, VD method, or the like.

The thickness of this transparent optical crystal film 11 is the same as that of the multilayer mirror 10.
The thickness of the optical crystal film 11 constituting one layer of the dispersion reflection layer 1
The total thickness of 3 is approximately 1/2 (-λ/2) of the wavelength λ of the vacuum ultraviolet light region to be reflected, and the phase of the light transmitted and reflected by the next layer, the dispersive reflection layer 13, is Make sure it fits.

Therefore, when the target is vacuum ultraviolet light having a wavelength λ of 170 nrn, the total thickness may be about 85 nm.

The dispersed reflection layer 13 is made of vapor-deposited particles 12 of aluminum, for example.
It is formed by vapor-depositing on the optical crystal film 11 to a thickness of about 1 nm, and this thickness is approximately equivalent to the diameter of the vapor-deposited aluminum particles 12, and the particles are vapor-deposited in an island shape or dispersed. In this state, the distance d between the deposited particles 12
is approximately 1 nm.

When vacuum ultraviolet light with a wavelength λ of 200 nm or less is incident on such a vacuum ultraviolet light region multilayer mirror 10, 1
Most of the light that passes through the optical crystal film 11 of the mirror 14 and hits the vapor deposited particles 2 of the dispersed reflection layer 13 is directly reflected, and a part of the light passes through the vapor deposited particles 12. Further, light between the vapor deposited particles 12 of the first layer mirror 14 is transmitted as is.

Then, the light that has passed through the vapor deposition particles 12 through the mirror 4 of the first layer and the light that has passed between the vapor deposition particles 12 or the light that has passed through the mirror 1 of the second layer.
5, and here, most of the light that hits the vapor deposited particles 12 of the dispersed reflection layer 1B is directly reflected, and a part of it passes through the vapor deposited particles 12.

Further, light between the vapor deposited particles 12 of the second layer mirror 15 is transmitted as is.

Then, the light transmitted through the second-layer mirror 15 enters the third-layer mirror 16, and the process is repeated through the subsequent mirrors 17°, and so on.

In this distributed reflection layer 13, since the interval d between the vapor deposited particles 12 is extremely small for light of wavelength λ, the waves of light transmitted between these island-shaped vapor deposited particles 12 are not disturbed and remain in a uniform state. At the same time, since the thickness of the vapor-deposited particles 12 is extremely thin, the amount of light that passes through the vapor-deposited particles 12 is extremely small, and absorption can be suppressed as much as possible.

And each mirror 14, 15 . The light reflected by the mountain is added to the reflected light, which improves the reflection rate.

As a result, even in the vacuum ultraviolet region, the optical crystal film 1 and the distributed reflection layer 3 can realize a highly efficient multilayer mirror 10.

Next, an example of a method for manufacturing a multilayer mirror for use in the vacuum ultraviolet region will be described with reference to the process diagram shown in FIG.

(2) First, a transparent optical crystal film 11 made of fluoride such as M g F 2 or Ca F 2 is formed by CVD or the like.

The thickness of this transparent optical crystal film 11 is the same as that of the multilayer mirror 10.
The thickness of the optical crystal film 11 constituting one layer of the dispersion reflection layer 1
The total thickness of 3 is about 1/2 of the wavelength λ of the vacuum ultraviolet light region to be reflected, so that the phase of the light transmitted and reflected by the next reflective layer 2 matches.

Therefore, when the target is vacuum ultraviolet light having a wavelength λ of 170 ns, the total thickness may be about 85 ng.

■ A metal material such as aluminum laminate is vapor-deposited on the surface of the optical crystal film 11, and the metal is adhered to the surface of the optical crystal film 11 in an island shape with a thickness of about 1 nm, so that the distributed reflection is achieved. Let it be film 13.

This vapor deposition of aluminum is performed by depositing aluminum particles 1
Since the diameter of 2 is approximately 1r+a, the evaporation particles 12 are deposited one by one so as to be lined up on the surface of the optical crystal film 11. In evaporation of this thickness, the evaporation particles] 2 The particles are not uniform, but are dispersed in an island-like manner, and the distance d between each deposited particle 12 is approximately 1 nm.

■ A dispersed reflection layer 13 in which vapor-deposited particles 12 dispersed in the form of islands of approximately 10I8 are vapor-deposited on the transparent optical crystal film 11.
The first layer of mirror 14 is formed by forming a film.

■ After such a first layer mirror 14 is made, the above ■: Deposition of a transparent optical crystal film 11 by CVD, ■:
Repeating the steps of forming a dispersed reflection layer 13 on which vapor-deposited particles 12 are vapor-deposited dispersed in an island shape, ①, and completing the second layer mirror 15,
The multilayer mirror 10 is formed by forming the third and subsequent mirror layers 16, . . . .

The number of layers of this multilayer mirror 10 is 14.1 mirrors in each layer.
It is determined by the degree of absorption during reflection and transmission of light in the vacuum ultraviolet region by the dispersed reflection layer 13 in 5.16, and determines the extent to which the light reflected by the lowermost dispersed reflection layer 13 contributes to improving the reflectance. It is determined by the degree of light absorption.

For example, a dispersed reflective layer 1 made of vapor-deposited particles of aluminum]2
3, each mirror]4, 15.16.・・・
Since the reflectance of the dispersed reflective layer 13 is relatively small when forming a uniform reflective layer, it is necessary to increase the number of layers compared to a normal multilayer mirror.

As shown in FIG. 1, the multilayer mirror 10 for the vacuum ultraviolet region made as described in 2 has an optical crystal film 11 disposed on the top layer, followed by a dispersive reflection layer 13. The vapor-deposited particles 12 used for reflection are arranged on one plane.

When light in the vacuum ultraviolet region is incident, it is reflected by the distributed reflection layer 13 of the uppermost mirror 14, and at the same time, the transmitted light is reflected by the distributed reflection layer 13 of the next mirror 15.
Further, the transmitted light is reflected by the dispersive reflection layer 13 of the next mirror 16,17.

Therefore, for the incident light, the distributed reflection layer 1 of each layer
All of the reflected light reflected by the mirror 3 contributes to the reflection efficiency, resulting in a multilayer mirror 10 with a high passivity in the vacuum ultraviolet region, which has not been seen in the past.

In addition, in the above example, MgF is used as the transparent optical crystal.
Although the explanation is given using a fluoride such as fluoride and CaF 2 as an example, other fluorides and transparent crystals other than fluorides may be used, and the film forming method is not limited to the CVD method, but other methods may be used.

Furthermore, since the reflectance of the metal material for the dispersed reflection layer varies depending on the wavelength of the light to be reflected, the metal material may be changed depending on the wavelength, and gold or the like can be used in addition to aluminum.

Furthermore, changes may be made to each component without changing the gist of the invention.

C. Effects of the Invention] As specifically explained above in conjunction with the embodiments, the multilayer mirror for the vacuum ultraviolet region of the present invention has a transparent optical crystal film and vapor-deposited particles of a metal material that are extremely thinly vapor-deposited. Since the dispersed reflective films are alternately repeated to form a multilayer film mirror, even in the vacuum ultraviolet light region, light that is directly reflected by the dispersed reflective layer and light that is transmitted between and inside the vapor deposited particles are separated. A multilayer mirror can be formed by utilizing the light reflected by the next dispersive reflection layer.

In this multilayer structure, light that is not reflected by the dispersed reflection layer does not pass through the deposited particles, so light absorption can be suppressed as much as possible and a high reflectance can be achieved.

In addition, according to the method for manufacturing a multilayer mirror for use in the vacuum ultraviolet light region of the second invention, vapor-deposited particles of a metal material are deposited and dispersed extremely thinly on a transparent optical crystal film to form a dispersed reflection film. Since a multilayer mirror is made by alternately repeating a transparent optical crystal film and a distributed reflection film made of a metal material, a multilayer mirror in the vacuum ultraviolet region can be easily made.

In the multilayer mirror made in this manner, light that is not reflected by the dispersed reflection layer does not pass through the vapor deposited particles, so light absorption can be suppressed as much as possible and high reflectance can be achieved.

Therefore, these multilayer mirrors can be used for spectroscopic research in the vacuum ultraviolet region and as a highly efficient reflection system for free electron lasers and the like.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of a multilayer mirror for use in the vacuum ultraviolet region of the present invention. FIG. 2 is a process diagram of an embodiment of the method for manufacturing a multilayer mirror for vacuum ultraviolet light region according to the present invention. 10. Multilayer mirror in vacuum ultraviolet region, 11. Transparent optical crystal film, ]2. Vapor deposited particles, 13. Dispersed reflection layer of metal material, 14.15, 16.1.7 Mirror of each layer. Applicant: Ishikawajima Harima Heavy Industries Co., Ltd./Diagram 1

Claims (2)

[Claims] (1) Vacuum ultraviolet light region characterized by a multilayered structure consisting of an optical crystal film transparent to vacuum ultraviolet light and a dispersed reflection layer in which vapor-deposited particles of a highly reflective metal material are dispersed in an extremely thin layer. Multilayer mirror for use. (2) When manufacturing a multilayer mirror for use in the vacuum ultraviolet region, vapor-deposited particles of a highly reflective metal material are dispersed extremely thinly on the surface of a transparent optical crystal film to form a dispersed reflection layer, and then the optical crystal film is A method for manufacturing a multilayer mirror for use in a vacuum ultraviolet light region, characterized in that the above-mentioned dispersed reflection layer is repeatedly formed to form a multilayer film.