JPH06194497A - Highly heat resistant soft x-ray multilayer film reflector employing bn - Google Patents

Abstract

PURPOSE:To provide a heat resistant soft X-ray multilayer reflector inevitable, as an optical system, for X-ray reduction projection aligner in the fabrication of next generation LSI. CONSTITUTION:The highly heat resistant soft X-ray multilayer film reflector is a laminate having repetitive unit of Mo/BN or W/BN. The reflective face of a reflector in an optical system employing a soft X-ray or laser light source is repetitively coated with Mo/BN or W/BN film having unit thickness of 30-60Angstrom . Number of repetition is set at 50-100 and the total film thickness is set at 4500-9000Angstrom .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant soft X-ray multilayer film reflecting mirror, which is indispensable as an optical system of an X-ray reduction projection exposure apparatus for the production of next-generation VLSI, and has a high heat-resistant soft X.
The present invention aims to provide a line reflection mirror, a soft X-ray multilayer film reflection mirror, and a narrow band soft X-ray reflection mirror.

[0002]

The industrial fields of application of the present invention are soft X-ray optical engineering, thin film multilayer coating, heat-resistant reflecting mirrors, and high heat-resistant soft X-ray multilayer reflecting mirrors used in the technology of utilizing synchrotron radiation.
Conventionally, as a multilayer film reflection mirror for soft X-rays that can withstand the irradiation of high-intensity synchrotron radiation, W (tungsten) / C (carbon), W / B ₄ C (boron carbide), etc., in which refractory materials are combined, are used. Is considered appropriate.

[0003]

However, these ideas are extremely difficult to test under the same harsh conditions as actual high-intensity synchrotron radiation, and their success has not been confirmed. Hard X-rays with a wavelength of 2 Å or less that can be transmitted through the atmosphere in X-rays have a large absorption coefficient of the atmosphere and cannot propagate in the atmosphere, so they are emitted in a vacuum and propagated in a wavelength of 500 Å
X-rays of about 2Å are called soft X-rays.

Conventionally, the reflecting surface of the reflecting mirror of the imaging optical system of the soft X-ray lithography using the high intensity light such as the synchrotron radiation soft X-ray or laser or the reflecting surface of the condenser mirror of the microscope is suitable. A high heat resistant coating has not been confirmed, and its development has been demanded.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to keep the multilayer film structure intact even when exposed to very strong light such as synchrotron radiation soft X-rays or lasers, and to maintain the original performance. (EN) It is possible to provide a new combination of multilayer films as a constituent material of a multilayer film mirror capable of stably reflecting emitted light, or a multilayer film mirror having a coating made of an excellent material suitable for the purpose.

In the present invention, the repeating unit is Mo / BN or W /
A laminated multilayer film of BN, having a repetition rate of 50 to 100 and a thickness of 30 to 60Å per layer, and a total film thickness of 4500 to 9000Å Mo / BN or W / A highly heat-resistant soft X-ray multilayer film reflecting mirror using BN, characterized in that a repeating laminated multilayer film of BN is coated on a reflecting surface of a reflecting mirror of an optical system using a soft X-ray or a laser as a light source. .

[0007]

The present inventors examined the stability of the multilayer film against the irradiation of high intensity radiant light such as soft X-rays or laser which has been a problem recently.

If such a high heat-resistant soft X-ray multilayer film is invented, it will be widely used as a high-efficiency soft X-ray reflecting mirror element in synchrotron radiation science that uses synchrotron radiation as a light source. Furthermore, X-ray reduction projection exposure lithography for the production of next-generation VLSI, which is currently under intense development, and soft X-ray CVD (vapor phase growth), which is promising for semiconductor processing
The method is based on the premise that synchrotron radiation is used as the light source, and the problem of heat resistance of the reflecting mirror of the optical system that uses high intensity radiation as the light source will be solved all at once.

When the multi-layered film receives strong radiant light, the temperature of the multi-layered film locally rises, and the substances constituting the multi-layered film mutually diffuse due to the physical action of high-energy light. However, it is usual that the original performance of the multilayer film is lost due to the material change. The high heat resistant multilayer film is required not only to be a substance having a high melting point, but also to be made of a physically stable substance. However, the data on this is currently very insufficient.

According to the present invention, BN (boron nitride) is actually used as a material for forming a multilayer film that can sufficiently withstand high intensity light such as soft X-rays or laser, through a high temperature annealing test and a radiation irradiation test. The present invention has been completed as a result of many experimental studies.

The wavelength of the maximum reflectance can be shifted by changing the period (sum of thicknesses of two layers of adjacent materials) of the multilayer film reflecting mirror. In other words, the multilayer film is designed / designed to extract the light of the most necessary wavelength according to the application of the multilayer film
It has the advantage of being manufactured. In the present invention, Mo / BN
Or, a multilayer film for soft X-rays, which is manufactured by using a W / BN repeated multilayer film according to its purpose, is used as a basic element of an optical system in basic scientific research using synchrotron radiation, and for the production of VLSI. High heat-resistant soft X that can maintain its original performance even with high intensity radiant light and can stably supply light of the target wavelength as an element of reduction projection exposure system and optical system of soft X-ray CVD method.
A linear multilayer mirror was found.

[0012]

EXAMPLES As a soft X-ray multilayer mirror of the present invention, Mo
The following basic experiments were conducted to find that / BN or W / BN is a desired high heat resistant material.

Test Example 1 Soft X-ray multilayer film Mo / X, W / X
Annealing test of (X = Si, C, BN, B ₄ C) The stability of the multilayer film against the irradiation of high-intensity synchrotron radiation and laser has recently become a problem. In the research of the present invention, in order to systematically proceed with the development of a soft X-ray multilayer mirror that can withstand the irradiation of such intense synchrotron radiation, Mo and W are used as high-density materials, and Si and C are used as low-density materials. , BN, B ₄ C were selected and the performance was evaluated from the change in the soft X-ray reflectance before and after annealing. In order to meet the conditions, each multilayer film was designed to have a reflection peak near 100 eV at an incident angle of 45 °.
The sample was created on a Si wafer by the magnetron sputtering method. Annealing is performed in a vacuum electric furnace at 200 ℃ to 700 ℃ until 100
Annealing was performed every 5 ° C. for 5 hours at each temperature.
The reflectance was measured with a soft X-ray reflectometer using laser plasma as a light source. The result is shown in FIG. In FIG. 1, the horizontal axis represents the annealing temperature and the vertical axis represents the reflectance.
As can be seen, the thermal stability is determined not by Mo or W but by the light element material, and BN is the best among the four materials, followed by B ₄ C.

Test Example 2 Soft X-ray multilayer film Mo / X, W / X
(X = BN, B ₄ C) Undulator Light Irradiation Test From the results of the annealing test of Test Example 1 above, the soft X-ray multilayer film using BN and B ₄ C as the light element substances has excellent thermal stability. I found out that In order to confirm what kind of stability these show with respect to actual strong synchrotron radiation, angling at the straight beam line of the PF (Photon Factory) BL-28 Synchrotron Radiation Experiment Facility (Photon Factory) The change in reflectance before and after the irradiation with the latrator light was evaluated by a soft X-ray reflectometer using a laser plasma as a light source.
Designed to have a reflectance peak near 100 eV at
A film was formed on a SiC substrate by magnetron sputtering. For irradiation, the undulator gap is 60 mm and the ring current is approximately
It was carried out for 10 minutes at 340 mA. It was confirmed by calorimetry that the power density at this time was about 2.3 W / mm ² . FIG. 2 shows the results of measurement of Mo / BN before and after irradiation at an incident angle of 45 °. As is clear from FIG. 2, it was found that Mo / BN is the most stable of the four and W / BN follows it. It was confirmed that this result agrees with the tendency of the annealing test.

1. Outline of experiment: The soft X-ray multilayer mirror is a soft X-ray optical element that has been attracting attention because it exhibits not only high direct incidence reflectance but also better polarization and filtering characteristics.
Various applications of the soft X-ray multilayer mirror have been studied in many fields, and are expected to be applied particularly to the beamline optical system for the next-generation synchrotron radiation (SR).

Recent advances in the technology of intercalating light sources such as undulators and wigglers have succeeded in delivering extremely intense and focused synchrotron radiation (SR) beams. It is widely expected that this high-intensity beam will contribute to the development of a new field of synchrotron radiation (SR) science.
However, an optical element that can freely handle such a high-performance beam has not been developed yet. Organic crystals such as KAP and TAP are widely used as a dispersive element of a double crystal soft X-ray monochromator. However, it is absolutely impossible for these crystals to withstand intense synchrotron radiation. From the viewpoint of the heat load problem, a soft X-ray multilayer mirror has recently been drawing attention. Some groups have adopted a combination of soft X-ray multilayer mirrors for the first crystal and organic crystals for the second crystal,
The performance such as resolution was evaluated.

So far, the development of a high heat load soft X-ray multilayer film has not been successful. Several research groups recently obtained interesting preliminary research results as the first step in developing such a soft X-ray multilayer film. Twigler, etc., is radiated with a white beam from a hard X-ray wiggler in Hadjirab (Hamburg) to Pt / C, W / C, W / Si and Si-W-Si / C.
The stability of the multilayer film was investigated. The power density on the surface of the sample was about 0.42 W / mm ² . The stability of the multilayer film is CuKα
It was evaluated by measuring the reflectance before and after the irradiation test using X-ray. The results showed only a reduction of about 15% Si-
Except for the W-Si / C sample, it showed various damages ranging from complete destruction of the laminated structure to 40-60% reduction in reflectance. Coat Light et al. Investigated the stability of W / C and W / Si multilayer films actively cooled using a hard X-ray wiggler in Hajiirab. The irradiation test is about 0.25 on the sample surface.
It was run for 40 hours at a power density of W / mm ² . Although the decrease in reflectance for X-rays of CuKα irradiation was a few percent, all irradiated samples showed surface contamination. Irradiation effect in a vacuum furnace
It was found to be less than the effect of thermal annealing at 400 ° C for 2 hours. It was also found that the irradiation effect depends on the number of repeated laminated layers and the constituent materials.

The present inventors have found that the stability of Mo / BN, Mo / B ₄ C, W / BN and W / B ₄ C repeatedly laminated multilayer films irradiated with white radiation from a multipolar wiggler against soft X-rays. Examined. The combination of these materials is Mo / X and W /
The X multilayer film (X = C, Si, BN and B ₄ C) was selected from the results of the thermal annealing test. After briefly describing the result of the thermal annealing test, the result of the irradiation test is shown.

2. Thermal Annealing Test In order to select a sample for the synchrotron radiation irradiation test, we have Mo / X and W / X (X = C,
An annealing test was performed on a multilayer film of Si, BN, and B ₄ C). The sample was prepared according to the design criteria such that the reflectance has a peak at around 100 eV at an incident angle of 45 °. The sample was deposited on a smooth silicon wafer by magnetron sputtering. After that, it was annealed in a high vacuum furnace at a constant temperature between 200 and 700 ° C. for 5 hours. The effect of thermal annealing was investigated by measuring soft X-ray reflectivity and period spacing after and before annealing. Silicon (Si) and carbon (C) from 8 sets of samples
It was found that the samples containing Pd became unstable at temperatures above 300 ° C. FIG. 3 shows changes in the reflectance of the multilayer film at an incident angle of 45 ° at the annealing temperature. This data is Mo / BN, W / B
N, Mo / B ₄ C and W / B ₄ C multilayer films, and the reflectance is normalized by the value before annealing.

FIG. 4 shows changes in the cycle length of the above sample, with the horizontal axis representing the annealing temperature. FIG. 4 shows the change in the cycle interval with the annealing temperature. Both Mo / BN and W / B
The repeating multilayer of N expands by annealing, while Mo /
B ₄ C and W / B ₄ C shrink upon annealing. (However,
The cycle interval is normalized by the value of annealing. )

1. As is clear from FIGS. 3 and 4, thermal stability is mainly due to low density materials (BN, C, B ₄ C, S).
It is influenced by i) and does not depend on the type of metal (Mo, W). 2. 700 / ℃ for both Mo / BN and W / BN repeating multilayer film
It is thermally stable up to. Based on these results, the present inventors have found that BN and B ₄ C
Was selected as the low density material.

3. Samples Multilayer films of Mo / BN, Mo / B ₄ C, W / BN and W / B ₄ C were prepared by the magnetron sputtering method in the study by the present inventors. Each multilayer film consists of 51 repeating layers with a periodic spacing of 84Å. The above-mentioned repeated laminated multilayer film repeats the same combination such as Mo / BN-Mo / BN-Mo / BN, and does not mean that Mo / BN and W / BN are alternately laminated. . This structure causes a peak of reflectance near 105 eV at an incident angle of 45 °. The magnetron sputtering apparatus has a vertical type vertically placed target and sample substrate. The system has a 4-inch target for DC sputter and a 6-inch target for RF sputter. Molybdenum (Mo) and tungsten (W) were DC sputtered at 100 W input, while BN and B ₄ C were sputtered at 400 W input. Argon pressure was 2.0 mTorr. Multilayer film is 30 × 30 × 10 mm ³
Was deposited on a super-polished SiC substrate. The distance between the substrate and the target was about 15 cm. The rotating plate equipped with the substrate was rotated at 10 rpm. During the sputtering of one material, the other material was blocked using a shutter. For example,
For the Mo / BN multilayer film sample, the BN layer was deposited during all 77 revolutions of the substrate. The film obtained has a thickness of approximately 56Å and approximately 1.
The average deposition rate was 2Å / sec. The vapor deposition rates of the B ₄ C, Mo and W layers were 0.90, 2.5 and 1.9 Å / sec, respectively. The degree of vacuum was about 2 × 10 ^-6 Torr. The SiC substrate is first washed with gauze soaked in a neutral detergent, and then about 40 ° C.
It was completely washed with running water. The wet SiC substrate was dipped in ethanol and then dried in a propanol vapor bath for 40-60 minutes before being transferred to the sputter device.

In addition to the multilayer film prepared by magnetron sputtering, the present inventors also prepared an Rh / Si multilayer film by ion beam sputtering. Argon atmosphere is about 3
It was × 10 ^-4 Torr. This multilayer film has an incident angle of about 45 °
It was designed to have a peak reflectance around 97 eV. The soft X-ray reflectivity of the prepared sample was evaluated using a soft X-ray reflectometer using laser plasma as a light source. The data is Table 1
In summary.

[0024]

[Table 1]

4. Irradiation test The irradiation test was carried out by exposing the sample to a white beam emitted from the 23-pole wiggler on the beam line BL-28 of the Photon Factory ring operated at 2.5 GeV. This beamline had no filters such as beryllium or graphite and no front mirror. For the irradiation test, an ultra-high vacuum test tank installed about 16.5 m from the light source was used. The present inventors have previously measured the power density distribution of the incident beam by a calorimetric method using a copper light absorber.

The four samples placed close to each other were tightly mounted in a water-cooled copper holder with an aluminum foil as a heat conductor sandwiched between them. The sample surface temperature was monitored with an infrared camera through a sapphire window during irradiation. In addition, the temperature was monitored with an alumel-chromel thermocouple (0.3 mm diameter) attached to one of the samples.

8 mm (length) x 9 mm located upstream of the sample
The white wiggler beam was vertically incident on the sample surface through the (horizontal) opening. X-ray energy is not reflected in this arrangement. First, the lower half of each sample was irradiated with a Wiggler gap at 100 mm (K value: 3.15) for about 45 minutes. The ring current is about 315 mA, and the average power density is about 0.9 at the irradiation center.
It was W / mm ² . Then gap 60 the upper half of each sample.
mm (K value 7.66) for about 10 minutes. The ring current at this time was 345 mA, and the power density was about 2.3 W / mm ² . During the lower half irradiation of each sample, the thermocouple showed a maximum temperature increase of about 5 ° C. The increase during the upper half irradiation was 13 ° C.
The surface temperature estimated from the infrared image is approximately 34 in each case.
℃ and 60 ℃. The vacuum was kept better than 4 × 10 ^-8 Torr during irradiation.

The Rh / Si multilayer film was irradiated with a wiggler beam through an opening of 8 mm × 20 mm. The upper and lower halves were irradiated at power densities of 1.7 and 2.2 W / mm ² for 15 and 10 minutes, respectively. The temperature rise of the substrate was approximately 170 ° C and 220 ° C in each case measured by thermocouple.

5. Results and Discussion The effect of irradiation of the wiggler light on the multilayer film sample was evaluated by measuring the reflectance at an incident angle of 45 °. The reflectance was measured with a soft X-ray reflectometer using laser plasma as a light source. 5 to 9
Are Mo / BN, W / BN, Mo / B ₄ C, W / respectively
The peak reflectance measured for B ₄ C and Rh / Si is shown. The solid line (A) shows the reflectance of the sample before irradiation, and the broken line (B) with white circles shows the reflectance after irradiation with radiant light at a power density of 0.9 W / mm ² . The dotted line (C) with a black circle is
The reflectance after irradiation with synchrotron radiation at a power density of 2.3 W / mm ² is shown. The Mo / BN sample has a peak reflectance of about 20% reduced,
The peak moved from 102 eV to 96 eV. However, the effect due to the difference between the two power densities cannot be observed. The W / BN sample shows the same effect as the Mo / BN sample, but the peak reflectance is reduced by about 65%. Mo / B ₄ C sample is 0.9 W
Almost all of them were destroyed by the reflectance of irradiation of / mm ² .
In fact, it was visible that the multilayer film was destroyed by the irradiation. In the W / B ₄ C sample, the decrease in reflectance is 0.9 W
/ Mm is about 50% at an irradiation of ^2, whereas was about 98% or more of 2.3 W / mm ² irradiation.

FIG. 5 shows Mo on a SiC substrate before irradiation with synchrotron radiation.
/ BN multilayer film reflectance peak measurement value (solid line A), same M
After irradiating 0.9 W / mm ² of radiant light on the upper half of the o / BN multilayer film (white circled broken line B), 2.3 W on the lower half of the Mo / BN multilayer film.
FIG. 4 is a characteristic diagram showing reflectance peak values measured after irradiation with radiant light of / mm ² (dotted circle C).

FIG. 6 shows W / on a SiC substrate before irradiation with radiant light.
Measured value of reflectance peak of BN multilayer film (solid line A), W / B
The upper half of the N multilayer film was irradiated with 0.9 W / mm ² of radiant light (white circle dashed line B), and the lower half of the W / BN multilayer film was irradiated with 2.3 W / mm ² of radiant light (black circle dotted line C). It is a characteristic view which shows each reflectance peak value.

FIG. 7 shows Mo on a SiC substrate before irradiation with synchrotron radiation.
/ B ₄ C multilayer film reflectance peak measurement value (solid line A), M
After irradiating 0.9 W / mm ² of radiant light on the upper half of the o / B ₄ C multilayer film (broken line B with white circles), on the lower half of the Mo / B ₄ C multilayer film
FIG. 3 is a characteristic diagram showing reflectance peak values measured after irradiation with 2.3 W / mm ² of radiant light (dotted line C).

FIG. 8 shows W / on a SiC substrate before irradiation with radiant light.
Measured value of reflectance peak of B ₄ C multilayer film (solid line A), W
After irradiation of 0.9 W / mm ² of radiant light on the upper half of the / B ₄ C multilayer film (white circled broken line B), 2.3 W / on the lower half of the W / B ₄ C multilayer film.
It is a characteristic view which respectively shows the reflectance peak value measured after irradiating a radiant light of mm ² (black dotted line C).

[0034] Figure 9 is reflectance measurements of Rh / Si multilayer film before synchrotron radiation (solid line A) and after irradiation of 1.7 W / mm ² (open circles dashed B) and 2.2 W / mm ² after irradiation (black circle dotted line It is a characteristic view which shows the reflectance peak value of each measured Rh / Si multilayer film in C).

It is mainly BN and B ₄ C that characterize the above results, not molybdenum (Mo) or tungsten (W). That is, Mo / BN and W / BN
The sample can withstand irradiation of 2.3 W / mm ² , but the reflectance peak shifts to longer wavelengths. On the other hand, Mo / B ₄ C and W
The / B ₄ C sample cannot withstand 2.3 W / mm ² soft X-ray and X-ray beam irradiation. However, the peak position is at least
It is stable to irradiation of 0.9 W / mm ² . This tendency qualitatively agrees with the result of the annealing test described in the second section.
This result suggests that the annealing test is an effective means for selecting the combination of materials when performing the synchrotron irradiation test.

For the Mo / BN and W / BN multilayer film samples, the surface temperature during irradiation at 2.3 W / mm ² was 0.9 W / mm ^2.
It is very remarkable that the decrease in reflectance is almost the same regardless of the power density, though it is considerably higher than that at. However, the X-ray dose during irradiation at 0.9 W / mm ²
It is only slightly higher than the dose during irradiation at 2.3 W / mm ² . It is believed that the reason for the decrease in the soft X-ray reflectance observed in Mo / BN and W / BN is not the thermal effect but the BN layer radiant light induced effect.

Finally, for comparison purposes, the inventors
The test result of the / Si multilayer film is shown. FIG. 9 shows changes in the soft X-ray reflectance of Rh / Si irradiated with wiggler light. The solid curve A shows the reflectance of the sample immediately after preparation. The white circles (B curve) are the results of irradiation tests with a power density of 1.7 W / mm ² , and the black circles (C curve) are with a power density of 2.2 W / mm ² . The peak reflectance of 26% is 1.7 W / mm ²
The power density was decreased to 1.7% and the power density to 2.2 W / mm ² was decreased to 1.5%. The peak positions shifted from 92.5 eV to 95.5 eV and 96.5 eV, respectively.
Substrate temperature is Rh / Si and Mo / BN because of different irradiation conditions.
Although different among the samples, the Rh / Si multilayer film has Mo /
It was confirmed to be less stable than the BN multilayer film.

6. Experimental Conclusions Mo / X and W / X (X = C, Si, BN and B ₄ C)
Based on the multilayer film anneal test, the inventors have selected Mo / BN, W / BN, Mo / B ₄ C and W / B ₄ C multilayer films for irradiation testing. These samples are SiC
It was created on the substrate by the magnetron sputtering method. The effect of irradiation with white wiggler light having a power density of 2.3 W / mm ² for 10 minutes was evaluated by comparing the soft X-ray reflectance at an incident angle of 45 °. As a result, the following conclusions were obtained. 1. Mo / BN is the most stable under the above conditions. 2. The decrease in reflectance observed in the Mo / BN and W / BN multilayers is considered to be due to the radiation-induced effect in the BN layer. 3. The annealing test is effective in selecting a sample for irradiation test.

[0039]

According to the present invention, it can be expected that light having a wavelength suitable for the purpose can be supplied with high intensity and stably. Therefore, in the field of basic science utilizing synchrotron radiation, a very high-quality spectroscopic spectrum can be shortened. It will be possible to measure in time, and it can be expected to open the way to spectroscopic experiments, which have been difficult to achieve due to the light intensity. On the other hand, in X-ray reduction projection exposure lithography and soft X-ray CVD processing, transfer of LSI patterns and semiconductor processing can be made uniform in a short time by a high-intensity stable beam. It

[Brief description of drawings]

FIG. 1 is a plot of changes in peak reflectance at various incident angles of 45 ° after annealing of various multilayer films, with the horizontal axis representing the annealing temperature and the vertical axis representing the reflectance.

FIG. 2 shows reflection peaks of Mo / BN measured before and after the irradiation test (solid line) and after (dotted line: 2.3 W / mm ² , −dot chain line: 0.9 W / mm ² ) at an incident angle of 45 °.

FIG. 3 is a plot of changes in peak reflectance at an incident angle of 45 ° after annealing of various multilayer films, with the horizontal axis representing the annealing temperature and the vertical axis representing the reflectance.

FIG. 4 is a plot of changes in cycle intervals after annealing of various multilayer films with respect to annealing temperature.

FIG. 5 shows Mo / B on a SiC substrate before irradiation with synchrotron radiation.
Measured value of reflectance peak of N multilayer film (solid line A), Mo /
After irradiating 0.9 W / mm ² of radiant light on the upper half of the BN multilayer film (white circled broken line B), 2.3 W / mm on the lower half of the Mo / BN multilayer film.
It is a characteristic view which respectively shows the reflectance peak value measured after irradiating the radiant light of ² (black circle dotted line C).

FIG. 6 shows W / BN on a SiC substrate before irradiation with synchrotron radiation.
Measurement value of the reflectance peak of the multilayer film (solid line A), after irradiation with 0.9 W / mm ² of radiant light on the upper half of the W / BN multilayer film (white circle broken line B), 2.3 W on the lower half of the W / BN multilayer film FIG. 4 is a characteristic diagram showing reflectance peak values measured after irradiation with radiant light of / mm ² (dotted circle C).

FIG. 7 shows Mo / B on a SiC substrate before irradiation with synchrotron radiation.
Measured value of reflectance peak of ₄ C multilayer film (solid line A), Mo /
After irradiating 0.9 W / mm ² of radiant light on the upper half of the B ₄ C multilayer film (broken line B with white circles), 2. on the lower half of the Mo / B ₄ C multilayer film.
FIG. 3 is a characteristic diagram showing reflectance peak values measured after irradiation with radiant light of 3 W / mm ² (dotted circles C).

FIG. 8 shows W / B ₄ on a SiC substrate before irradiation with synchrotron light.
Measurement value of the reflectance peak of the multilayer film of C (solid line A), W / B
After irradiating 0.9 W / mm ² of radiant light on the upper half of the ₄ C multilayer film (white circled broken line B), 2.3 W / mm ² on the lower half of the W / B ₄ C multilayer film.
FIG. 5 is a characteristic diagram showing reflectance peak values measured after irradiation with the radiant light (dotted circle C).

Figure 9 is reflectance measurements of Rh / Si multilayer film before synchrotron radiation (solid line A) and after irradiation of 1.7 W / mm ² (open circles dashed B) and 2.2 W / mm ² after irradiation (black circles It is a characteristic view which shows the reflectance peak value of the Rh / Si multilayer film which was measured in each of dotted lines C).

Claims (2)

[Claims] 1. A laminated multilayer film having a repeating unit of Mo / BN or W / BN and having a repeating number of 50 to 100 and a thickness of 30 to 60Å per layer, and a total film thereof. 4500 thickness
A highly heat-resistant soft X-ray characterized by coating a repeating laminated multilayer film of Mo / BN or W / BN of up to 9000Å on the reflecting surface of a reflecting mirror of an optical system using a soft X-ray or a laser as a light source. Multi-layered film mirror. 2. A microscope which uses a soft X-ray such as synchrotron radiation or a reflection surface of a reflection mirror of a focusing mirror of an imaging optical system of soft X-ray lithography which uses high intensity light such as laser as a light source or a microscope which is used as a soft X-ray microscope. The highly heat-resistant soft X-ray multilayer mirror according to claim 1, wherein the reflective surface of the condenser mirror is coated.