JP2883100B2 - Half mirror or beam splitter for soft X-ray and vacuum ultraviolet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device, and more particularly to a half mirror and a beam splitter for light having a wavelength of 200 nm or less, which is called vacuum ultraviolet light from soft X-rays.

[Conventional technology]

Conventionally, for light with a wavelength shorter than the region called vacuum ultraviolet, there is no reflector having a high reflectance when incident on the surface at or near an angle perpendicular thereto, and the incident light near normal incidence At the corner, only a reflectance of 1% or less was obtained.

On the other hand, in a grazing incidence mirror having a relatively high reflectance,
It was necessary to adjust the angle of incidence to 1 ° or less or 2 to 3 ° from the mirror surface. Further, in order to make the light incident on the surface at a small angle, a very large shape is required even for a thin light beam, and its use has been difficult and limited. In addition, the oblique incidence mirror has a small degree of freedom in the optical system, and there are many difficulties in actual use, such as polishing and holding the reflective mirror so as to have a highly accurate flatness over a large area.

In order to eliminate such a drawback, there has been proposed a reflecting mirror having a multilayer structure using interference of multilayer thin films.

In the soft X-ray and vacuum ultraviolet region, the reflectivity of most substances is the complex index of refraction (n
+ Ik, hereinafter referred to as the refractive index), and the real part n is approximately 1.0 (n = 1−δ, δ is about 10 ⁻¹ to 10 ⁻³ ), so the Fresnel at the boundary between the vacuum and the material thin film Is very small, on the order of 0.1% or less. Further, even at the boundary between the laminated thin films of different materials, the reflectance does not exceed several% per single boundary.

However, by adopting a film thickness configuration in which different materials are alternately formed into a multilayer laminated structure and the reflected light from each layer boundary is strengthened by interference, and the reflectance of the multilayer film as a whole is maximized, thereby achieving a high reflectance. Is possible. Further, by selecting a combination of different kinds of materials so as to increase the difference in refractive index between adjacent layers, a reflecting mirror, a half mirror or a beam splitter which can obtain a high reflectance in combination with the above-mentioned film thickness configuration can be realized.

Known combinations of materials include:
There is a transition metal as a low refractive index material, and most of high refractive index materials use a semiconductor element such as carbon or silicon. Typical examples include a combination of tungsten (W) and carbon (C) and a combination of molybdenum (Mo) and silicon (Si).

For example, JP-A-63-106703 discloses a multilayer laminated structure in which heavy elements and light elements are alternately laminated.

[Problems to be solved by the invention]

However, reflecting mirrors and the like using these combinations use heavy elements or compounds of heavy elements for one or both substances, and because of their large absorption, are irradiated with high-intensity light such as synchrotron radiation. Temperature rise, and the resulting destruction of the multilayer structure has been a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a soft X-ray / vacuum ultraviolet multilayer film half which does not cause deterioration due to interlayer thermal diffusion or the like to high intensity soft X-rays or vacuum ultraviolet rays. It is to provide a mirror and a beam splitter, a half mirror having an arbitrary transmittance, and a beam splitter having an arbitrary separation angle.

[Means for solving the problem]

An object of the present invention is to provide a soft X-ray / vacuum ultraviolet multilayer film half mirror and a beam splitter having a multilayer structure composed of alternating layers of two substances having different refractive indices, both of which have atomic numbers. It is achieved by a soft X-ray / vacuum ultraviolet multilayer multilayer half mirror and a beam splitter, which are light elements of number 20 or less or a compound of these light elements.

In particular, the two substances are both beryllium (Be),
Boron (B), carbon (C), aluminum (Al), silicon (Si), beryllium oxide (BeO), beryllium carbide (B
e ₂ C), boron carbide (B ₄ C), boron nitride (BN), boron silicide (B ₆ Si), magnesium fluoride (MgF ₂ ), magnesium oxide (MgO), magnesium silicide (Mg ₂ Si) , Aluminum fluoride (AlF ₃ ), aluminum boride (Al
B ₂ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), aluminum sulfide (Al ₂ S ₃ ), aluminum phosphide (AlP), aluminum carbide (Al ₄ C ₃ ), silicon sulfide (SiS ₂ ) , Silicon monoxide (SiO), silicon dioxide (Si
O ₂ ), silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), calcium nitride (Ca ₃ N ₂ ), calcium fluoride (CaF ₂ ), calcium oxide (CaO), calcium carbide (CaC ₂ ) The above-mentioned half mirror and beam splitter are preferably selected in combination so that the refractive indices are different from each other.

One of the two substances is beryllium (Be), aluminum (Al), silicon (Si), aluminum sulfide (Al ₂ S ₃ ), magnesium silicide (Mg ₂ Si), silicon sulfide (SiS ₂ ), Aluminum carbide (Al ₄ C ₃ ), boron silicide (B ₆ Si), silicon monoxide (SiO), silicon dioxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), aluminum phosphide (AlP), Silicon carbide (SiC), beryllium carbide (Be
₂ C), one of which is boron (B), carbon (C), aluminum fluoride (Al
F ₃ ), calcium nitride (Ca ₃ N ₂ ), calcium fluoride (C
aF ₂ ), magnesium fluoride (MgF ₂ ), aluminum boride (AlB ₂ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), boron carbide (B ₄ C), beryllium oxide (BeO), oxidation Calcium (CaO), calcium carbide (Ca
The above-mentioned half mirror and beam splitter, which are one kind selected from C ₂ ), magnesium oxide (MgO), and boron nitride (BN), are preferable.

Further, the above-mentioned half mirror or beam splitter having a layer made of a light element having an atomic number of 20 or less or a compound of these light elements as a reinforcing film under the multilayer structure is preferable.

According to the present invention, by using a light element having an atomic number of 20 or less or a compound of these light elements as a layer constituting material, absorption of each layer is reduced, sufficient transmittance is obtained, and generated heat is also reduced. Also, there is no possibility that the interface between the layers is blurred due to thermal diffusion and the characteristics are degraded.

FIG. 1 is a schematic cross-sectional view of one embodiment of a multilayer reflector for soft X-rays and vacuum ultraviolet rays which is a premise of the description of the present invention.

The multi-layer reflecting mirror for soft X-rays and vacuum ultraviolet rays which is the premise of the description of the present invention shown in FIG. 1 is a polished flat surface or a curved surface (for example, the surface roughness is rm) which is sufficiently smoother than the wavelength used.
a layer of a first material on a substrate 1 having an s value of 10 ° or less)
, And layers 3, 5,... Of the second substance are alternately stacked.

The reflectivity obtained from the soft X-ray / vacuum ultraviolet multilayer film reflecting mirror, which is the premise of the description of the present invention, is the difference between the refractive indices of two kinds of substances having different refractive indices forming the alternating layers, the absorptivity of each layer, Although it depends on the number of layers to be laminated, the wavelength of light to be irradiated, and the like, the difference in the refractive index is practically preferably at least 0.01 or more, for example, when the number of layers is 100 layers.

The thickness d ₁ , d ₂ ,... Of each layer is about / 4 of the wavelength used, and the layers are alternately laminated films of the same material. Either satisfy the condition of interference to reinforce each other, or satisfy the condition that the decrease in the reflectivity of the multilayer film as a whole is less when comparing the reflectivity loss and the absorption loss in each layer, Alternatively, it is determined by both. At this time, the film thickness may be the same for all the same material layers, or may not be the same so that the reflectance is maximized by changing the film thickness of each layer.

As a structure of the lamination, it is desirable to select a material that has a large difference between the refractive index of the final layer, which is a layer in contact with gas or vacuum, and the refractive index of gas or vacuum. Further, it is preferable that the difference in the refractive index between the substrate and the layer in contact with the substrate is also increased.

In addition, since the reflectance increases as the number of alternating layers increases, the number of layers is preferably 5 or more. However, when the number of layers is too large, the influence of absorption becomes significant. It is good to have a layer pair. Further, as shown in FIG. 1, a protective layer 6 made of a stable material with little absorption may be provided on the final layer.

Further, as a film forming method for producing a multilayer reflector for soft X-rays and vacuum ultraviolet rays which is a premise of the description of the present invention, an RF magnetron sputtering method, an electron vapor deposition method in an ultra-high vacuum, or the like is preferably used. But ion beam sputtering
DC magnetron sputtering, metal organic chemical vapor deposition (MOCV
It goes without saying that the multilayer film may be formed by using the D method) or the ion plating method.

FIG. 2 is a sectional view of an embodiment of the soft X-ray / vacuum ultraviolet half mirror or beam splitter according to the present invention. The half mirror and the beam splitter are considered separately because of their functions and applications, but there is no difference in the configuration.

〔Example〕

Hereinafter, a reflecting mirror which is a premise of the description of the present invention will be described with reference to a reference example.

Reference Example 1 Carbon (C) 27.1 ° as a low refractive index material 2 and silicon (Si) as a high refractive index material 3 on a fused silica substrate 1 polished to a surface accuracy of λ / 20 (λ = 6328 °) and a surface roughness of 3.5 ° rms ) 35.2
Å were laminated by RF magnetron sputtering in a total of 71 layers, each including 36 layers and 35 layers. Argon gas pressure during film formation is 1.0 × 1
0 ^-3 Torr, and the deposition rate is 0.2 to 0.3 for both carbon and silicon.
As Å / sec, the film thickness of each layer was controlled by a quartz oscillator film thickness meter.

When soft X-rays having a wavelength of 124.0 ° were incident on the multilayer film thus obtained at an angle of 10 ° from a direction perpendicular to the reflecting surface, a reflectance of 65.3% was obtained.

 At this time, the absorptivity was 24.8%.

Similarly, the thickness of carbon and silicon was 26.8
A total of 71 layers of {38.3} were stacked, and soft X-rays having a wavelength of 124.0 ° were incident on the reflecting surface at an angle of 20 ° from the perpendicular direction. As a result, a reflectance of 66.5% was obtained.

Comparative Example 1 The absorptance was measured in the same manner as in Example 1 except that a multilayer film composed of tungsten and carbon (tungsten 22.1%, carbon 43.3%) was obtained, and it was 84.6%.

Reference Example 2 Boron (B) 33.0% as a low refractive index material 2 and silicon carbide as a high refractive index material 3 on a silicon single crystal substrate 1 polished to a surface accuracy of λ / 20 (λ = 6328 °) and a surface roughness of 4.2 ° rms (SiC) 31.6% were laminated by electron beam evaporation in ultra-high vacuum in total of 81 layers each of 41 layers and 40 layers. The degree of vacuum in the chamber during film formation is 3.0 × 10 ^-9 Torr,
The film formation rate was set to 0.1 to 0.2 Å / sec for both boron and silicon carbide, and the film thickness of each layer was controlled by a quartz oscillator type film thickness meter.

When soft X-rays having a wavelength of 124.0 ° were incident on the multilayer film thus obtained at an angle of 15 ° from the direction perpendicular to the reflecting surface, a reflectance of 52.3% was obtained. The absorption rate at this time is
37.2%.

In the same manner, a total of 81 layers were stacked with the film thicknesses of boron and silicon carbide being 36.4 ° and 35.7 °, respectively, and soft X-rays having a wavelength of 124.0 ° were incident on the reflecting surface at an angle of 30 ° from the perpendicular direction. , 54.5% reflectivity.

Comparative Example 2 The absorptance was measured in the same manner as in Reference Example 2 except that a multilayer film composed of tungsten and carbon (tungsten 22.2%, carbon 44.6%) was obtained, and it was 85.4%.

Reference Example 3 On a fused quartz substrate 1 polished to a surface accuracy of λ / 20 (λ = 6328 °) and a surface roughness of 2.9 ° rms, 26.6% of boron nitride (BN) as a low refractive index material 2 and silicon as a high refractive index material 3 Si)
A total of 61 layers of 35.6% each having 31 layers and 30 layers were laminated by ion beam sputtering. The argon gas pressure during film formation is 2.
0 × 10 ^-4 Torr, the ion acceleration voltage is 1000 V,
The deposition rate was 0.3 ホ ウ 素 / sec for both boron nitride and silicon.
The thickness of each layer was controlled by a quartz oscillator type thickness meter.

When soft X-rays having a wavelength of 124.0 ° were incident on the multilayer film thus obtained at an angle of 10 ° from a direction perpendicular to the reflecting surface, a reflectance of 57.6% was obtained. The absorption rate at this time is
It was 28.7%.

Similarly, a total of 61 layers were stacked with the thicknesses of boron nitride and silicon being 27.0 ° and 38.1 °, respectively, and soft X-rays having a wavelength of 124.0 ° were incident at an angle of 20 ° from the perpendicular to the reflecting surface. , 59.2% reflectance.

Comparative Example 3 The absorption was measured in the same manner as in Reference Example 3 except that a multilayer film composed of tungsten and carbon (tungsten 22.5%, carbon 42.9%) was obtained, and it was 83.5%.

Reference Example 4 Boron carbide (B ₄ C) 31.5% as a low refractive index material and silicon carbide as a high refractive index material on a fused quartz substrate 1 polished to a surface accuracy of λ / 5 (λ = 6328 °) and a surface roughness of 1.1 ° rms (SiC)
A total of 71 layers each consisting of 36 layers and 35 layers each of 31.8% were laminated by RF magnetron sputtering. The argon gas pressure during film formation is 1.
0 × 10 ⁻³ Torr, the film formation rate was set to 0.2 to 0.3 ° / sec for both boron carbide and silicon carbide, and the film thickness of each layer was controlled by a quartz oscillator type film thickness meter.

When soft X-rays having a wavelength of 124.0 ° were incident on the multilayer film thus obtained at an angle of 10 ° from a direction perpendicular to the reflecting surface, a reflectance of 51.4% was obtained. The absorption rate at this time is
37.6%.

Similarly, a total of 71 layers of boron carbide and silicon carbide having a thickness of 34.6Å and 34.3Å, respectively, were laminated, and a wavelength of 124.0
When a soft X-ray of 入射 was incident on the reflecting surface at an angle of 25 ° from the perpendicular direction, a reflectance of 53.8% was obtained.

Comparative Example 4 The absorptance was measured in the same manner as in Reference Example 4 except that a multilayer film composed of tungsten and carbon (tungsten 22.1%, carbon 43.3%) was obtained, and it was 84.6%.

Reference Example 5 Aluminum oxide (Al ₂ O ₃ ) 9.5Å as a low refractive index material 2 and a high refractive index material 3 on a fused quartz substrate 1 polished to a surface accuracy of λ / 5 (λ = 6328Å) and a surface roughness of 1.0Årms 13.9% of carbon (C) were deposited by RF magnetron sputtering in a total of 151 layers each of 76 layers and 75 layers. The argon gas pressure at the time of film formation was 1.0 × 10 ⁻³ Torr, the film formation rate was 0.2 to 0.3 ° / sec for both aluminum oxide and carbon, and the film thickness of each layer was controlled by a quartz oscillator type film thickness meter.

A soft X at a wavelength of 44.0 ° is applied to the multilayer film thus obtained.
When the line was incident on the reflecting surface at an angle of 20 ° from the perpendicular direction, a reflectance of 25.6% was obtained. The absorption rate at this time is 3
2.4%.

Similarly, a total of 151 layers were formed with aluminum oxide and carbon having a film thickness of 12.7 ° and 18.5 °, respectively, and a wavelength of 44.
When 0 ° soft X-rays were incident on the reflecting surface at an angle of 45 ° from the perpendicular direction, a reflectance of 40.2% was obtained.

In general, in a multilayer mirror, the thickness of each layer is set to approximately 1/4 of the wavelength to be reflected to satisfy the interference condition in which the reflected light from the interface of each layer on the mirror surface is enhanced. The above setting also has a film thickness of about 10 ° for a wavelength of 44.0.

However, if the target wavelength of reflection is short and it is difficult to stack a 1/4 wavelength film, the film thickness is set to 3/4 wavelength to reduce the interference conditions where reflected light from each layer interface strengthens on the mirror surface. Can be satisfied. Next, an example of such a setting will be described.

In the same manner as above, a total of 151 layers were laminated with aluminum oxide and carbon film thicknesses of 35.03 and 35.5Å, respectively, and a wavelength of 44.0Å.
軟 soft X-rays were incident on the reflecting surface at an angle of 20 ° from the perpendicular, and an absorptance of 82.0% was obtained.

Comparative Example 5 Example 5 (Al ₂ O ₃ :
9.5 吸収, C: 13.9Å), the absorption rate was 58.7%.

Reference Example 5 (Al ₂ O ₃ : except that a multilayer film composed of tungsten and carbon (tungsten 33.8%, carbon 36.7%) was used)
When the absorption was measured in the same manner as in the case of 35.0%, C: 35.5%), it was 97.8%.

Reference Example 6 Regarding combinations of substances other than Reference Examples 1 to 5,
Table 1 shows the reflectivity when the incident wavelength is constant at 124.0 ° and the reflectivity when the incident wavelength is constant at 43.97 °.

The basic configuration of the half mirror and the beam splitter is as shown in FIG.
21 and a first substance and a second substance (11, 13 ...
12, 14...), And a part of the substrate is deleted (deletion part 23). Hereinafter, a half mirror and a beam splitter will be described with reference to embodiments.

Example 1 A monovalent boron ion (B ⁺ ) was formed on a polished surface of a silicon substrate doped with phosphorus (P) using an ion implantation apparatus.
Was implanted at an acceleration voltage of 30 KV at 1 × 10 ¹⁵ / cm ² . Thereafter, the substrate was subjected to rapid thermal annealing (RTA) at about 900 ° C. for 2 minutes. Next, a total of 41 layers (B: 21 layers, Si: 20 layers) of boron (B) 31 ホ ウ 素 and silicon (Si) 31Å were alternately laminated on the substrate surface by a high-frequency magnetron sputtering method.

Next, the multilayer film was masked from the back surface of the substrate, and a substrate of 3 mmφ was subjected to back etching using a dry etching apparatus. At this time, carbon tetrachloride (CCl ₄ ) and carbon were used as reaction gases. At this time, the etching rate of the phosphorous (P) -doped one is about 2.5 to 3 times as large as that of the non-phosphorous (P) -doped one, so that the etching progresses in the vicinity of the boron (B) -implanted region. In this embodiment, the thickness of the silicon substrate after the back etching was about 1000 °.

The portion obtained in this way has a wavelength of 124 ° S
When polarized soft X-rays were incident on the film surface in the vertical direction, a half mirror having a reflectance of 52.2% and a transmittance of 20.3% was obtained.

Embodiment 2 Reference is made to FIGS. 3 (a) to 3 (e).

A silicon wafer 31 (substrate) having both sides polished is cleaned, and a silicon nitride (Si ₃ N ₄ ) film 32 (reinforcing film) is formed on one side A.
Was formed to a thickness of 1000Å by chemical vapor deposition (CVD). Source gases include silane (SiH ₄ ) and ammonia (NH
_The substrate temperature was set to about 800 ° C. using ₃ ). Similarly, the silicon nitride film 33 (substrate protection film) is applied to the surface B by about 3 μm.
The film was formed by the mCVD method. At this time, the source gas substrate temperature was the same as above, and a 5 mmφ mask was placed at a desired position to provide a non-deposition portion.

Next, on the silicon nitride film on the surface A, boron carbide (B ₄ C) 34
Å and silicon nitride (Si ₃ N ₄ ) 29 交互 alternately for a total of 61 layers (B ₄ C: 3
One layer, 30 layers of Si ₃ N ₄ ) were laminated by a high-frequency magnetron sputtering method. Further, using the silicon nitride film on the surface B as a mask, the non-deposited portion was subjected to anisotropic etching to remove the silicon substrate. At this time, a 30% solution of potassium hydroxide (KOH) was used as an etching solution, and the solution temperature was 70 ° C.

When S-polarized soft X-rays having a wavelength of 124 ° were incident on the portion of the multilayer film obtained through the above steps from which the substrate was removed from a direction perpendicular to the film, the reflectance was 29.4% and the transmittance was 8.5.
%.

Example 3 In the same process as in Example 2, the thickness of the silicon nitride film on the surface A was 500 mm, and the area of the non-deposited portion on the surface B was 35 mm.
φ, and a soft X of S-polarized light having a wavelength of 124 ° was applied to a multilayer half mirror obtained in the same manner as in Example 8 except for these conditions.
When a line is incident perpendicularly to the film surface, the reflectance
28.0% and a transmittance of 12.3% were obtained.

Example 4 In the same process as in Example 2, a total of 21 layers of boron carbide (32) and silicon nitride (31) were alternately formed on the 1000-nm-thick silicon nitride film on the side A (B ₄ C: 11 layers, Si ₃ N ₄ : 10 layers) It was produced by a high frequency magnetron sputtering method.

With respect to the sample thus obtained, the area of the non-deposited portion on the surface B was set to 2.5 mmφ, and the substrate in this portion was used in Example 2.
Through the same process as above, and remove the wavelength 124
When the S-polarized soft X-ray of Å was incident on the film surface in a direction perpendicular to the film surface, a reflectance of 9.5% and a transmittance of 32.7% were obtained.

Example 5 A silicon wafer having both sides polished was cleaned, and a silicon nitride (Si ₃ N ₄ ) film was formed on one side A by chemical vapor deposition (CVD).
Method). Silane (SiH ₄ ) and ammonia (NH ₃ ) are used as source gases, and the substrate temperature is about 800
° C. After placing a mask of 4 mmφ at a desired position on the surface B, a silicon nitride film was formed in a thickness of about 3 μm by the same method as described above.

Next, aluminum oxide (Al
₂ O ₃ ) 10Å and carbon (C) 12Å alternately in a total of 101 layers (Al ₂ O ₃ : 51
Layers, C: 50 layers) were laminated by a high frequency magnetron sputtering method. Further, anisotropic etching was performed on the non-deposited portion of the surface B on the obtained multilayer film, and the silicon substrate was removed. At this time, potassium hydroxide (KO
The solution temperature was 70 ° C. using a 30% solution of H).

When an S-polarized soft X-ray having a wavelength of 44 ° was incident on this portion in a direction perpendicular to the film, a reflectance of 14.7% and a transmittance of 28.2% were obtained.

Example 6 A silicon wafer having both sides polished was cleaned, a 3 mmφ mask was placed at a desired position on one side B, and a silicon nitride (Si ₃ N ₄ ) film was formed by chemical vapor deposition (CVD). About 3μ
m was formed. At this time, the source gas is silane (SiH ₄ )
And ammonia (NH ₃ ), and the substrate temperature was set to about 800 ° C.

Next, carbon (C) 36 ° and silicon (Si) 47 ° were alternately laminated on the surface A by a high-frequency magnetron sputtering method in total of 41 layers (C: 21 layers, Si: 20 layers).

Next, anisotropic etching was performed on the non-evaporated portion of the surface B with a 30% potassium hydroxide solution at a liquid temperature of about 70 ° C. to remove the silicon substrate. At this time, a device was devised so that the etching solution did not reach the multilayer film on the surface A.

With respect to the part obtained in this manner, S at a wavelength of 124 °
When polarized soft X-rays were incident on the film at an angle of incidence of 45 ° from the vertical direction, the reflectance was 25.3% and the transmittance was 26.1%. The reflected light: transmitted light = 1: 1.03, exhibiting characteristics as a beam splitter. .

Example 7 A silicon wafer having both sides polished was cleaned, and a silicon nitride (Si ₃ N ₄ ) film was formed on the surface A by 1500 ° C. and approximately 3 μm on the surface B by chemical vapor deposition (CVD). Filmed.
At this time, silane (SiH ₄ ) and ammonia (NH ₃ ) are used as source gases, the substrate temperature is set to about 800 ° C., and the surface B
A mask of 2.5 mmφ was placed on the upper surface when forming a silicon nitride film.

Next, a boron nitride (BN) 40.5
15 and silicon carbide (SiC) 41Å alternately for a total of 15 layers (BN: 8 layers,
(SiC: 7 layers) Laminated by high frequency magnetron sputtering. After that, the liquid temperature of 70 ° C.
Anisotropic etching was performed using a 30% potassium hydroxide (KOH) solution to remove the silicon substrate.

When an S-polarized soft X-ray having a wavelength of 124 ° was incident on the film at an incident angle of 45 ° from the perpendicular direction to the film thus obtained, the reflectance was 10.8% and the transmittance was 11.1%.
When the transmitted light was 1: 1.03, the characteristics as a beam splitter were exhibited.

Example 8 A silicon wafer having both surfaces polished was cleaned, and a silicon nitride (Si ₃ N ₄ ) film was formed on the surface A by 1200 ° C. and approximately 3 μm on the surface B by chemical vapor deposition (CVD). Filmed.
At this time, silane (SiH ₄ ) and ammonia (NH ₃ ) were used as source gases, the substrate temperature was set to about 800 ° C., and a mask of 3 mmφ was used on the surface B when forming a silicon nitride film.

Next, aluminum oxide (Al
₂ O ₃ ) 14Å and carbon (C) 17Å alternately for a total of 61 layers (Al ₂ O ₃ : 31
Layers, C: 30 layers) were laminated by a high frequency magnetron sputtering method. After that, the water temperature of 70 ° C.
Anisotropic etching was performed using a 30% potassium hydroxide (KOH) solution to remove the silicon substrate.

With respect to the portion obtained in this way, S at a wavelength of 43.97 °
When polarized soft X-rays were incident on the film at an incident angle of 45 ° from the vertical direction, the reflectance was 14.2% and the transmittance was 14.3%.
Reflected light: transmitted light = 1: 1.01 exhibited characteristics as a beam splitter.

In the above embodiments, silicon or silicon nitride is used as the reinforcing film below the multilayer film, but other materials such as beryllium and silicon oxide may be used. Also, the constituent materials of the multilayer film may be those that satisfy the claims other than those described in the present embodiment. Although a silicon nitride film formed by a CVD method is used as a mask material on the back surface in the embodiment, other materials and a film forming method may be used. In addition, high-frequency magnetron sputtering was used when producing multilayer films, but film forming methods such as DC magnetron sputtering, ion beam sputtering, EB evaporation in ultra-high vacuum, and MOCVD (metal organic chemical vapor deposition) were used. May be used. Also, the shape and size of the substrate removal portion (back-etch portion) may be arbitrary as long as the strength of the film is not affected, and the type of the etchant and the back-etching method may be used without any problem. .

〔The invention's effect〕

As described above, the soft X-ray / vacuum ultraviolet half mirror and beam splitter of the present invention have high reflectance and high transmittance even for light in the soft X-ray / vacuum ultraviolet region, There is no diffusion between layers, and durability for a sufficiently long time can be obtained even under irradiation of strong light such as synchrotron radiation.

In particular, by combining the reflector, the half mirror of the present invention and the beam splitter with each other, X
Conventional applications include reduction / magnification in the x-ray region, reflection type dispersive elements having a grating mirror structure, reflection mirrors for laser resonators, and applications to X-ray interferometers and X-ray laser resonators. As a new optical component in the area of X-ray optics, which has not been developed, it greatly contributes to expanding the area of application of optical components.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a layer structure of an example of a multilayer film reflecting mirror for X-ray and vacuum ultraviolet rays which is a premise of the description of the present invention, and FIG. 2 is a multilayer half mirror for X-ray and vacuum ultraviolet rays of the present invention. Alternatively, FIG. 3 is a schematic cross-sectional view of one embodiment of a beam splitter, and FIG. 3 is a diagram schematically illustrating an example of a manufacturing process of a half mirror. 1: Substrate, 2, 4: First material layer 3, 5: Second material layer 6: Protective layer 11, 13: First material layer 12, 14: Second material layer 21: Reinforcement film, 22: Substrate 23: Substrate removed 31: Silicon wafer (substrate) 32: Silicon nitride film (reinforcement film) 33: Silicon nitride film (substrate protection film) 34: Multilayer film (B ₄ C / SiN ₄ : 61 layers) d ₁ , d ₂ , d ₃ : thickness of layers.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshiaki Fukuda 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-63-161403 (JP, A) JP-A Sho 64-81904 (JP, A) JP-A-64-81906 (JP, A) JP-A-1-94300 (JP, A) JP-A-63-106703 (JP, A) (58) Fields studied (Int. Cl ^6, DB name) G21K 1/00 -. 7/00 H05H 13/04 G02B 5/00 - 5/32

Claims (4)

(57) [Claims] 1. A soft X-ray / vacuum ultraviolet half mirror or beam splitter having a multilayer structure comprising alternating layers of two kinds of substances having different refractive indices from each other. A soft X-ray / vacuum ultraviolet half mirror or beam splitter, which is a light element or a compound of the light elements. 2. An atomic number as a reinforcing film under the multilayer structure.
The half mirror or beam splitter according to claim 1, further comprising a layer made of a light element of No. 20 or less or a compound of the light elements. 3. The method of claim 2, wherein the two substances are both beryllium (B
e), boron (B), carbon (C), aluminum (A
l), silicon (Si), beryllium oxide (BeO), beryllium carbide (Be ₂ C), boron carbide (B ₄ C), boron nitride (B
N), boron silicide (B ₆ Si), magnesium fluoride (MgF
₂ ), magnesium oxide (MgO), magnesium silicide (Mg ₂ Si), aluminum fluoride (AlF ₃ ), aluminum boride (AlB ₂ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), sulfide Aluminum (Al ₂ S ₃ ), aluminum phosphide (AlP), aluminum carbide (Al
₄ C _3), silicon sulfide (SiS _2), silicon monoxide (SiO), silicon dioxide (SiO _2), silicon nitride (Si ₃ N _4), silicon carbide (SiC), calcium nitride (Ca ₃ N _2), The half mirror or beam splitter according to claim 1, wherein the half mirror or the beam splitter is selected from calcium fluoride (CaF ₂ ), calcium oxide (CaO), and calcium carbide (CaC ₂ ) in combination so as to have mutually different refractive indexes. 4. One of the two substances is beryllium (Be), aluminum (Al), silicon (Si), aluminum sulfide (Al ₂ S ₃ ), magnesium silicide (Mg ₂ S).
i), silicon sulfide (SiS ₂ ), aluminum carbide (Al
₄ C ₃ ), boron silicide (B ₆ Si), silicon monoxide (SiO),
One type selected from silicon dioxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), aluminum phosphide (AlP), silicon carbide (SiC), and beryllium carbide (Be ₂ C). The substance is boron (B), carbon (C), aluminum fluoride (AlF ₃ ), calcium nitride (Ca ₃ N ₂ ), calcium fluoride (CaF ₂ ), magnesium fluoride (MgF ₂ ), aluminum boride (AlB ₂ ), aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), boron carbide (B ₄ C), beryllium oxide (BeO), calcium oxide (CaO), calcium carbide (CaC ₂ ), magnesium oxide (MgO) , Boron nitride (B
The half mirror or the beam splitter according to claim 1, wherein the half mirror or the beam splitter is one type selected from N).