JPH0627053A - Refractive index measuring method for soft x-ray transmissive material - Google Patents

Abstract

PURPOSE:To determine refractive index of soft X-ray transmissive material highly accurately by making a pattern of a material to be measured on a soft X-ray transmissive thin film, transferring the pattern to a substrate to be exposed located closely to the thin film, determining the thickness of pattern having most conspicuous profile, and then calculating refractive index based on the thickness and the wavelength of irradiating light. CONSTITUTION:A soft X-ray transmissive thin film 2 is stretched over a substrate 1 and a first pattern 5 of a soft X-ray transmissive material is formed thereon in order to measure the refractive index. A substrate 7 to be exposed applied with resist 6 is disposed closely to the pattern 5 and irradiated with soft X-ray 8 of wavelength lambdathrough the pattern 5 in a vacuum or in helium gas of reduced pressure. Assuming the thickness of the pattern 5 is (t), refractive index thereof is (n), and refractive index of atmosphere is (n'), the soft X-ray 8 passed through the outside of the pattern 5 interferes with a soft X-ray 8 passed through the inside under a condition of 2(n'-n)t=lambda thus transferring conspicuous second pattern. When the pattern 5 is formed with different thicknesses and the thickness providing a most conspicuous second pattern is determined, refractive index can be determined according to a formula n=n'-lambda/2t.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft X-ray transparent material refractive index measuring method for an X-ray optical material used in a soft X-ray region having a wavelength of 1 to 200 Å.

[0002]

2. Description of the Related Art Soft X-rays having a wavelength of 0.1 to 20 nm are used for X-ray lithography and material analysis. But,
There are no solids or liquids that can easily transmit soft X-rays of the above wavelength, and even in the atmosphere, with a thickness of several mm to several tens mm,
The strength is attenuated to 1% or less.

Under these circumstances, light elements such as carbon, beryllium, silicon, etc., silicon dioxide,
A thin film of a light element compound such as silicon nitride, boron nitride, alumina, mylar, or polyimide having a thickness of several μm or less can obtain a soft X-ray transmittance of several tens% or more, and is therefore a soft X-ray transparent material. be called. And these thin films are
It is used as an X-ray mask membrane for X-ray lithography and as a vacuum barrier rib material that transmits soft X-rays.

Further, as disclosed in Japanese Patent Application No. 2-120552, an X-ray mask having a pattern for inverting the soft X-ray phase is manufactured, or the soft X-ray according to the inventor's prior application is inverted. These soft X-ray transparent materials are indispensable for repairing defects in X-ray mask light-shielding metal pattern lacking a light-shielding portion.

Further, when an optical system is made by using soft X-rays in the above wavelength band, in order to change the phase by a predetermined amount, 1 /
A two-wave plate and a quarter-wave plate are also required.

As described above, the soft X-ray transparent material for the soft X-rays in the above wavelength band has a very important application.
Nevertheless, there have been very few published examples of the results of measuring the refractive index of a soft X-ray transparent material with respect to soft X-rays in the above-mentioned wavelength band, and HJ Hagemann, W. Gudat, C. Kunz's DiE.・ S-Way Report, S-R-74 /
7 (DESY-Report, SR-74 / 7) (1974), the values for carbon, magnesium, aluminum, etc. are shown, which is extremely small.

As a name, even though it is a soft X-ray transparent material, it has such a transmittance that the transmittance becomes a few tens% to a few% with a thickness of only a few μm, and the refractive index to be measured. The rate is very close to 1. Therefore, it is very difficult to directly measure the refraction amount, and there has been no method for accurately and simply measuring the refractive index, which is an important optical constant of these soft X-ray transparent materials.

Conventionally, a method as shown in FIG. 7 has been used to measure the refractive index n of an optical material for light having a wavelength in the visible or far ultraviolet region. That is, the optical material 11 for which the refractive index n is to be measured is placed on the optical material 10 for which the refractive index n ₀ is known and is larger than n, and the incident light 12 is irradiated horizontally to the optical material 11 for which the refractive index is measured. , The angle i at which the emitted light 13 from the optical material 10 whose refractive index n ₀ is already known and larger than n is observed is measured, and the refraction to be measured is calculated from the relational expression n = √ (n ₀ ² −sin ² i) Find the rate n. This measures the refractive index by utilizing the critical angle of total internal reflection.

However, regarding soft X-rays in the above wavelength band,
The refractive index n of the soft X-ray transparent material to be measured is a value slightly smaller than 1 and very close to 1, and the refractive index of a medium in which soft X-rays are not easily attenuated, such as in a vacuum or in a gas of a light element. Since it is only slightly smaller, the critical angle at which total internal reflection occurs is close to 90 degrees. Further, there is no block of solid material that transmits soft X-rays in the above wavelength band, such as visible light to far ultraviolet light. Therefore, the refractive index cannot be measured by the conventional method for light having a wavelength of visible light to far-ultraviolet light as described above.

As described above, since it is very difficult to directly measure the refractive index of a soft X-ray transparent material with respect to soft X-rays, in the above-mentioned published paper, it is easy to measure the measured values of transmittance and reflectance. Therefore, the value of the refractive index is calculated using the Kramers-Kronig relational expression.

[0011]

However, the conventional technique is an indirect measurement by the method of calculating the refractive index from the values of the transmittance and the reflectance as described in the above paper, and the refractive index is subjected to a complicated calculation process. The accuracy and precision are low as well.
For example, according to the above paper, for carbon, energy is 50
0 eV to 800 eV (wavelength 2.41 to 1.55 nm)
Soft X-ray with a refractive index of 0.999 and energy from 1 KeV to 3 KeV (wavelength 1.24 to 0.413 nm)
The linear refractive index is 1.000. Japanese Patent Application No. 2-120552
In the case of making an X-ray mask having a pattern for inverting the phase of the soft X-ray, as described in US Pat. ), It is necessary to obtain the thickness d of the soft X-ray transparent material, and the value of (1-n) required for the wavelength of the soft X-ray is
As described above, the thickness d of the soft X-ray transparent material cannot be determined unless it is known with a precision of one significant digit or less.

The present invention determines the refractive index of a soft X-ray transparent material as
An object of the present invention is to obtain a method for measuring the refractive index of a soft X-ray transparent material, which is required directly and simply and with high accuracy.

[0013]

The above-mentioned object is to form a first pattern of a soft X-ray transparent material whose refractive index is to be measured on a thin film of a soft X-ray transparent material, and bring it into close proximity or close contact with the thin film. When arranging an exposed substrate to which a material having photosensitivity to soft X-rays is attached and exposing and then developing the exposed substrate, a position corresponding to a contour boundary of the first pattern,
The thickness or depth of the first pattern is obtained by finding the thickness or depth of the first pattern in which the second pattern formed most prominently because the material having photosensitivity to the soft X-rays is hard to be exposed. It is achieved by calculating the refractive index from the depth or depth and the irradiation X-ray wavelength.

[0014]

In the present invention, the X used in X-ray lithography is used.
A pattern is formed on a soft X-ray transparent thin film such as a line mask membrane using a soft X-ray transparent material whose refractive index is to be measured.
Or the soft X-ray transparent material itself whose refractive index you want to measure,
A soft X-ray transparent thin film such as the X-ray mask membrane is formed, and a step pattern of the soft X-ray transparent material is formed on the soft X-ray transparent thin film. Next, soft X on a substrate such as a wafer.
A material having photosensitivity to rays is attached, and the substrate and the soft X-ray transparent thin film or the thin film of the soft X-ray transparent material itself whose refractive index is to be measured are brought into close proximity or in close contact with each other to obtain a monochromatic or nearly monochromatic color. Irradiate with a soft X-ray of a specific wavelength.

At this time, when the phase of the transmitted soft X-rays is just reversed between the place where there is a pattern formed of the above-mentioned soft X-ray transparent material and the place where there is no pattern, the above-mentioned soft X-ray transparent material. At the boundary of the pattern formed in step 2, the phases inside and outside the pattern are always opposite, so the soft X-rays on both sides cancel each other out, and the transmitted soft X-ray intensity becomes extremely low. Even when a step pattern is formed on the thin film of the soft X-ray transparent material whose refractive index is to be measured, if the phase of the transmitted soft X-ray is just inverted by the depth of the step pattern, the step pattern will be changed. At the boundary of, the phases are always opposite between the inside and outside of the pattern, so the soft X-rays on both sides cancel each other out, and the transmitted soft X-ray intensity becomes extremely low. Therefore, at the boundary of the pattern formed of the soft X-ray transparent material whose refractive index is to be measured, or at the boundary of the step pattern on the thin film of the soft X-ray transparent material itself whose refractive index is to be measured, the soft X-ray is used. When exposed to, some parts are less likely to be exposed to light.

Thickness of a pattern formed of a soft X-ray transparent material whose refractive index n is to be measured, or soft X whose refractive index is to be measured
Assuming that the depth of the step pattern on the thin film of the radiation transparent material itself is t and the wavelength of the soft X-rays irradiated in the atmosphere of the refractive index n'is λ, the above-mentioned refractive index n is measured for the soft X-ray transparency. The phase change φ of the soft X-ray caused by the thickness of the pattern formed of the material or the depth of the step pattern on the thin film of the soft X-ray transparent material itself whose refractive index is to be measured is φ = 2π (n′−n ) T / λ.

Therefore, the condition for φ = π is 2 (n′−n) t = λ. Therefore, soft X-rays are less likely to be attenuated, for example, in a vacuum (n ′ = 1) or in a light element gas such as helium or hydrogen,
Experiments are performed for soft X-rays having an arbitrary wavelength λ while changing the above t, and the boundary of the pattern formed of the soft X-ray transparent material whose refractive index is to be measured, or the soft X-ray transparent material whose refractive index is to be measured. At the position corresponding to the boundary of the step pattern on the thin film of its own, the value of t that most prominently exposes the portion that is difficult to be exposed when the soft X-ray is irradiated is obtained, and the refractive index n to be measured is obtained from the above equation. be able to.

That is, as for the refractive index n, the thickness of the pattern formed by the soft X-ray transparent material measured, or the refractive index n Can be easily calculated as described above from the characteristic value t of the depth of the step pattern on the thin film of the soft X-ray transparent material itself to be measured and the wavelength λ of the irradiated soft X-ray.

[0019]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a principle explanatory view showing an embodiment of a method for measuring the refractive index of a soft X-ray transparent material according to the present invention, and FIG. 2 is a condition for changing the soft X-ray phase by π for the purpose of measuring the refractive index in the above embodiment. FIG. 3 is a partial enlarged view of a sample having a pattern of a soft X-ray transparent material formed on an X-ray transparent thin film with a different thickness for the above refractive index measurement, FIG. 4 is a partially enlarged view of a sample in which a step pattern of a soft X-ray transparent material is formed on an X-ray transparent thin film for the above refractive index measurement, and FIG. 5 shows the refractive index for the above refractive index measurement. FIG. 6 is a partially enlarged view of a sample in which a step pattern is provided on a self-supporting thin film formed of a soft X-ray transparent material to be measured.
FIG. 7 is a partially enlarged view of a sample in which a step pattern is provided on a thin film of a soft X-ray transparent material.

As shown in FIG. 1, a soft X-ray transparent thin film 2 is formed on a substrate 1 in the same manner as an X-ray mask used for X-ray lithography. To form the above structure, the soft X-ray transparent thin film 2 and the thin film 3 serving as a protective film when the substrate 1 is etched are deposited on each surface of the substrate 1, and then a part of the thin film 3 is etched. Then, a part of the substrate 1 is removed by etching using the remaining thin film 3 as an etching mask to leave only the soft X-ray transparent thin film 2. Reference numeral 4 is a frame attached to the substrate 1.

On the soft X-ray transparent thin film 2, a pattern 5 of a soft X-ray transparent material whose refractive index is to be measured is formed as a first pattern. In order to form the pattern 5 of the soft X-ray transparent material, the soft X-ray transparent material is deposited on the entire surface of the soft X-ray transparent thin film 2 in advance, and a pattern is formed on the soft X-ray transparent thin film 2 with a resist by a lithographic means. The soft X-ray transparent material deposited on the entire surface may be etched using the pattern as an etching mask. When the soft X-ray transparent material whose refractive index is to be measured is a resist, the pattern of the resist can be directly formed by a lithographic means.

The exposed substrate 7 coated with the resist 6 is placed close to or in close contact with the pattern 5 of the soft X-ray transmitting material formed as described above, and the wavelength is set in a vacuum or a depressurized gas such as helium. A soft X-ray 8 of λ is irradiated through the pattern 5.

Assuming that the thickness of the pattern 5 of the soft X-ray transparent material is t and the refractive index is n, the soft X-ray transparent material has a thickness of 2 under the condition of 2 (n'-n) t = λ as described above. In the portion corresponding to the boundary of the pattern 5, the soft X-rays passing through the outside of the pattern 5 of the soft X-ray transmitting material and the soft X-rays passing through the inside of the pattern have an intensity ratio corresponding to the soft X-ray transmittance and a phase. Since they overlap and cancel each other in the inverted state, the intensity is always reduced despite the irradiation of the soft X-rays 8, and the resist 6 forms a second pattern of a portion that is less likely to be exposed to light than other portions. . That is, under the condition that the above relational expression is satisfied, the soft X-ray intensity reaching the resist 6 is as shown in FIG. Therefore, when the resist 6 is a positive resist when exposed and developed for an appropriate exposure time, a second pattern having a cross-sectional shape as shown in FIG. 1C is transferred.

As the thickness of the pattern 5 of the soft X-ray transmitting material deviates from the above condition, the soft X-ray intensity at the position corresponding to the contour boundary approaches the same value as at other places, and the resist 6
The cross-sectional shape of the second pattern transferred to is typically shown in FIG.
As shown in (c), they change like a-e.
Therefore, samples having different thicknesses of the soft X-ray transparent material pattern 5 are prepared, exposed and developed respectively, and correspond to the boundaries of the soft X-ray transparent material pattern 5 corresponding to C in FIG. Then, by searching for the condition that the most prominent soft X-ray shielding portion is generated, the above formula can be modified to obtain the refractive index n from n = n'-λ / (2t).

If exposure is performed in a vacuum atmosphere, n '= 1. Therefore, the refractive index n may be obtained from n = 1-λ / (2t).

Only the thickness t of the pattern 5 of the soft X-ray transparent material whose refractive index n is to be measured is directly measured. The measurement accuracy of the refractive index n is the thickness of the pattern 5 of the above soft X-ray transparent material. The measurement accuracy of the thickness t depends on the limit at which the difference in the thickness t can be detected as the difference in the pattern shape transferred to the resist 6. The thickness t of the pattern 5 of the soft X-ray transmitting material is determined by an optical microscope or an electron microscope to determine whether the most prominent X-ray shielding portion is generated at a position corresponding to the contour boundary of the resist 6. If the pattern transferred to is observed from above, it can be identified relatively easily. In addition, an elongated soft X-ray transmissive material pattern 5 is formed, and an exposed substrate 7 having a pattern to which the contour boundary is transferred is formed at a position corresponding to the contour boundary of the resist 6 in the longitudinal direction of the pattern. It is possible to make a more detailed and accurate determination by dividing it vertically with respect to and observing the cross-sectional shape with an electron microscope or the like. As shown in FIG. 3, if a sample having a pattern 5 of a soft X-ray transmitting material having various thicknesses is used, it is possible to find the phase inversion condition by exposing and developing a small number of times.

Since the size of the second pattern transferred to the resist 6 differs depending on the proximity gap between the sample and the substrate 7 to be exposed, the pattern of the soft X-ray transmitting material that produces the most noticeable soft X-ray shielding portion. In order to find the thickness condition of No. 5, it is necessary to guarantee the same proximity interval for each sample in which the thickness of the pattern 5 of the soft X-ray transmitting material is changed, but the thickness on the same sample should be guaranteed. If the pattern 5 of the soft X-ray transmitting material changed to each type is provided, it is easy to guarantee that the adjacent gaps are the same.

As described above, in order to form the pattern 5 of the soft X-ray transmitting material having various thicknesses on the same sample, for example, the soft X-ray is used.
A resist is applied on a film of a line-transmissive material, and a pattern in which the line width is sequentially changed is formed by photolithography or the like so that the residual film thickness of the resist changes according to the line width of the pattern. The soft X-ray transparent material film is etched under the condition that the selection ratio is relatively small by using the resist having the thickness sequentially changed as an etching mask, and the finished soft X-ray transparent material pattern 5 is formed.
The thickness may be sequentially changed depending on the remaining film thickness of the resist used as the etching mask.

Further, when a resist is applied on a film of a soft X-ray transparent material and a pattern is formed by reducing projection exposure with an ultraviolet lens, even if the focus position is changed variously to form the pattern, The remaining film thickness can be changed. Using the resist having the remaining film thickness sequentially changed as an etching mask, the film of the soft X-ray transparent material is etched under the condition that the selection ratio is relatively small, and the pattern 5 of the finished soft X-ray transparent material is obtained.
It is obvious that the thickness of the film can be changed sequentially depending on the remaining film thickness of the resist used as the etching mask.

When the soft X-ray transparent material for which the refractive index is to be measured is a resist, the resist pattern in which the residual film thickness is sequentially changed may be used as it is as the pattern 5 of the soft X-ray transparent material. The pattern 5 of the soft X-ray transparent material whose refractive index n is to be measured is not the remaining pattern as shown in FIGS. 1 to 3 but the removal pattern as shown in FIG. 4A or the pattern as shown in FIG. 4B. A step pattern as shown in FIG.

By changing the thickness or depth of the pattern 5 at very fine intervals, it is not necessary to search for a condition which is considered to have produced the most prominent soft X-ray shielding portion at the position corresponding to the boundary of the pattern 5. Even if the thickness or depth of the pattern 5 is appropriately changed, the exposure is performed, and the thickness or depth of the pattern formed at that time is measured to determine the thickness of the pattern 5 and the thickness of the pattern formed by exposure or development. A pattern 5 that seems to produce the most prominent soft X-ray shielding part when the relationship with the depth is examined.
It is also possible to infer the thickness or depth of.

By the way, in the above method, it is not possible to form a free-standing thin film on the substrate 1 with the soft X-ray transparent material itself whose refractive index n is to be measured, unlike the soft X-ray transparent thin film 2 in FIG. Applicable to any material. On the other hand, for the soft X-ray transparent material itself for which the refractive index n is desired to be measured, for the material capable of forming a free-standing thin film on the substrate 1 like the soft X-ray transparent thin film 2 shown in FIG. 5 (a) and 5 (b) on the thin film 9 stretched on the substrate 1 with the desired soft X-ray transparent material.
Alternatively, a step pattern as shown in FIGS. 6A and 6B may be formed. In addition, in the case of FIGS. 6A and 6B, soft X
It is also possible to provide a pattern that penetrates the thin film stretched on the substrate 1 with a linearly transparent material. In the cases shown in FIGS. 5 and 6, as in the embodiment shown in FIGS. 1 to 4, soft X-rays are shielded when the depth t of the step satisfies the relationship described above at the step boundary portion. , The resist 6 has a second portion corresponding to the step boundary portion.
It is clear that the above pattern is produced.

The thickness or depth of the step pattern formed on the thin film 9 of the soft X-ray transparent material whose refractive index n is to be measured is changed at very fine intervals so that the step pattern is located at a position corresponding to the boundary of the step pattern. By searching for the condition that the most prominent soft X-ray shielding portion is generated, the refractive index n can be obtained from the thickness or depth of the step pattern and the wavelength of the soft X-ray at that time.

The thickness or depth of the second pattern formed on the thin film 9 can be changed to a position corresponding to the boundary after exposure and development by changing the thickness or depth of the step pattern at appropriate intervals. Is measured and the relationship between the thickness or depth of the step pattern and the thickness or depth of the second pattern formed by exposure / development is investigated, the step pattern that seems to cause the most noticeable soft X-ray shielding part is obtained. The thickness or depth of can also be inferred.

In each of the above embodiments, the pattern 5 of the soft X-ray transparent material whose refractive index n is to be measured or the step pattern provided on the thin film 9 of the soft X-ray transparent material is the X-ray transparent thin film. It is needless to say that it may be formed on the opposite surface of the thin film 9 stretched on the substrate 1 with 2 or the soft X-ray transparent material.

The pattern 5 of the soft X-ray transparent material whose refractive index n is to be measured or the step pattern provided on the thin film 9 of the soft X-ray transparent material whose refractive index n is to be measured may be of any size.
In FIG. 1, the size of the pattern 5 of the soft X-ray transparent material whose refractive index n is to be measured is drawn to be a fraction to one tenth of the size of the portion of the soft X-ray transparent thin film 2. However, the size of the pattern 5 of the soft X-ray transparent material may be arbitrary, merely considering the ease of viewing as an explanatory diagram.

Further, in FIGS. 3, 4 (b), 5 (b), and 6 (b), patterns having different thicknesses or depths are arranged at substantially equal intervals and at intervals similar to the size of the patterns. However, it is clear that these pattern intervals may be arbitrary and are not necessarily equal intervals.

[0038]

As described above, the method of measuring the refractive index of the soft X-ray transparent material according to the present invention comprises:
A first pattern of a soft X-ray transparent material whose refractive index is to be measured is formed, and it is placed in proximity to or in close contact with the above thin film, and an exposed substrate to which a material having photosensitivity to soft X-rays is attached,
When the exposed substrate is exposed and then developed, the first
The second pattern formed because the material having photosensitivity to the soft X-rays is hard to be exposed at the position corresponding to the contour boundary of the pattern is formed most remarkably in the thickness or depth of the first pattern. The refractive index is calculated from the thickness or depth of the first pattern and the irradiation X-ray wavelength, and the thickness of an arbitrary pattern made of a soft X-ray transparent material whose refractive index is to be measured. By investigating at what time the transfer pattern of the photosensitive material can be most noticeable,
Regardless of the type of the soft X-ray transparent material, the refractive index of the soft X-ray transparent material can be directly obtained with high precision by a simple method, instead of indirectly obtaining from the transmittance or the reflectance.

Further, according to the present invention, the above-mentioned Japanese Patent Application No. 2-1
A defect repairing pattern of the X-ray transparent material for repairing an X-ray mask pattern shown in 20552 in which the contour boundary of the X-ray transparent material serves as a light-shielding portion or a defective defect of the X-ray mask light-shielding weight metal pattern. It is possible to optimally adjust the thickness and depth, and it is possible to manufacture a phase control component such as a quarter-wave plate or a half-wave plate for X-ray optics.

[Brief description of drawings]

1A and 1B are explanatory views showing an embodiment of a method for measuring a refractive index of a soft X-ray transparent material according to the present invention, wherein FIG. Contour boundary soft X
FIG. 4C is a diagram showing the line strength, and FIG. 6C is a diagram showing the cross-sectional shape of the transfer pattern.

FIG. 2 is an explanatory view of a method for obtaining a condition for changing a soft X-ray phase by π for measuring a refractive index, and FIG. 2A is a diagram showing a state where the pattern thickness of a soft X-ray transparent material is different; 10A is a diagram showing the soft X-ray intensity at the corresponding position of the contour boundary according to the pattern thickness, and FIG. 13C is a diagram showing a cross-sectional shape of the pattern transferred to the resist.

FIG. 3 is a partially enlarged view of a sample having a pattern of a soft X-ray transparent material formed on a soft X-ray transparent thin film with varying thickness.

4A and 4B are partially enlarged views of a sample in which a step pattern of a soft X-ray transparent material on a soft X-ray transparent thin film is formed, in which FIG. 4A is a drawing pattern and FIG. 4B is a step pattern. It is a figure.

5A and 5B are partially enlarged views of a sample in which a step pattern is provided on a thin film of a soft X-ray transparent material whose refractive index is to be measured, FIG. 5A shows an independent pattern, and FIG. 5B shows a step pattern. It is a figure.

6A and 6B are partially enlarged views of a sample in which a step pattern is provided on a thin film of a soft X-ray transparent material whose refractive index is to be measured, FIG. 6A is an independent pattern, and FIG. 6B is a step pattern. Is.

FIG. 7 is an explanatory diagram showing a conventional method for obtaining a refractive index that has been used for visible light to far ultraviolet rays.

[Explanation of symbols]

 2 Soft X-ray transparent material thin film 5 First pattern 6 Resist 7 Substrate to be exposed 8 Soft X-ray 9 Free-standing thin film of soft X-ray transparent material whose refractive index is to be measured

Claims (4)

[Claims] 1. A thin film of a soft X-ray transparent material is formed with a first pattern of a soft X-ray transparent material whose refractive index is to be measured, and the first pattern is brought into close proximity to or in close contact with the thin film to expose it to a soft X-ray. When a substrate to be exposed to which a material having properties is adhered is arranged, and the substrate to be exposed is exposed and then developed, the substrate has photosensitivity to the soft X-rays at a position corresponding to the contour boundary of the first pattern. The second pattern, which is formed because the material is not easily exposed to light, finds the thickness or depth of the first pattern that is most prominently formed, and determines the thickness or depth of the first pattern and the irradiation X.
A method for measuring the refractive index of a soft X-ray transparent material, which calculates the refractive index from the line wavelength. 2. A soft X-ray transparent material thin film is formed with a first pattern of a soft X-ray transparent material whose refractive index is to be measured, and the soft X-ray transparent material is brought close to or in close contact with the thin film and is exposed to soft X-rays. The exposed substrate to which a material having a property of adhering is arranged, and the exposed substrate is exposed and developed by irradiating the exposed substrate with soft X-rays through the thin film and the first pattern, and a position corresponding to the contour boundary of the first pattern. In addition, the first step for obtaining the second pattern, which is possible because the material having photosensitivity to the soft X-rays is difficult to be exposed, and the second step for obtaining the depth or height of the second pattern are different. The height or depth of the second pattern corresponding to the first pattern of film thickness is obtained, and the relationship between the thickness or depth of the first pattern and the height or depth of the second pattern, and the irradiation. Refractive index of soft X-ray transparent material for calculating refractive index from X-ray wavelength Constant method. 3. A light-transmitting material having a step pattern formed on a thin film of a soft X-ray transparent material whose refractive index is to be measured, and a step pattern is formed close to or in close contact with the thin film to which a material having photosensitivity to soft X-rays is attached. When a substrate is placed, and the substrate to be exposed is exposed and then developed, a pattern formed because the material having photosensitivity to the soft X-rays is hard to be exposed at a position corresponding to the contour boundary of the step pattern. The refractive index of the soft X-ray transparent material is obtained by calculating the thickness or depth of the step pattern formed most remarkably and calculating the refractive index from the thickness or depth of the step pattern and the irradiation X-ray wavelength. Method. 4. An exposure subject to which a step pattern is formed on a thin film of a soft X-ray transparent material whose refractive index is to be measured, and which is brought close to or in close contact with the thin film to which a material sensitive to soft X-rays is attached. A substrate is placed, soft X-rays are irradiated through the step pattern, the exposed substrate is exposed and developed, and a material having photosensitivity to the soft X-ray is provided at a position corresponding to the contour boundary of the step pattern. The pattern height or depth corresponding to the step pattern having different film thickness is determined by the first step for obtaining a pattern that is difficult to be exposed to light and the second step for determining the depth or height of the pattern. A method for measuring the refractive index of a soft X-ray transparent material, which is obtained and the refractive index is calculated from the relationship between the thickness or depth of the step pattern and the height or depth of the pattern, and the irradiation X-ray wavelength.