JP2003243292A - Reflection mask, exposure apparatus and cleaning method thereof - Google Patents

Abstract

(57) [Problem] To provide a reflection mask capable of preventing a transfer failure due to adhesion of dust. SOLUTION: The reflection mask of the present invention comprises a substrate 1, an X-ray reflection multilayer film 2 formed on the substrate 1, and a substance having a low X-ray transmittance formed on the substrate 1 and having a predetermined X-ray transmittance. And an absorber layer 3 having a pattern. X-ray reflection multilayer film 2
A protective layer 4 made of a photocatalytic material is formed between the protective layer 4 and the absorber layer 3. According to the reflection mask of the present invention, contamination on the mask surface can be removed by light irradiation or the like in an oxygen-containing atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection mask used in a soft X-ray region, an exposure apparatus and a cleaning method therefor.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor integrated circuit devices, in order to improve the resolution of an optical system limited by the diffraction limit of light, reduction projection lithography technology (Extreme Ultra Violet Lithog
raphy; hereinafter referred to as EUVL. ) Is being developed.

Since the soft X-ray has a shorter wavelength than the ultraviolet ray used conventionally, a finer circuit pattern can be projected and exposed. However, in the wavelength range of soft X-rays, the refractive index of the substance is very close to the refractive index of vacuum (= 1), and therefore an optical element utilizing refraction that is generally used in the visible light region cannot be used. Therefore, an oblique incidence mirror, a multilayer film mirror, and the like that utilize total reflection are used.

The EUVL device is mainly composed of an X-ray source, an illumination optical system, a mask, a mask stage, an image forming optical system, a wafer stage and the like. A reflective mask is used as the mask. The reflection mask is a multilayer film mirror that reflects soft X-rays and is formed by processing a material having a relatively large absorption of soft X-rays into a desired pattern (for example, Katsuhiko Murakami, Surface Technology, Vol. .49 (1998) P849).

A multi-layered film mirror used for an optical element such as a reflection mask is formed by alternately stacking two kinds of substances having a different refractive index at a desired wavelength at a thickness of several tens on a thick substrate. It is a thing. The multi-layered film mirror obtains a high reflectance by aligning the phases of the light reflected by a large number of interfaces of these two kinds of substances. Assuming that the length of one cycle (cycle length) of the multilayer film is d, the incident angle of X-rays is θ, and the wavelength of X-rays is λ, Bragg's condition (2d · cos θ = n ·
It exhibits high reflectance when satisfying λ). As the two kinds of substances forming the multilayer film, materials that absorb as little as possible at a desired wavelength are used.

On the contrary, as the absorber formed on the multilayer film, it is said that a substance that absorbs as much as possible is preferable.
A material that can be easily processed is often selected by a pattern processing method such as dry etching, lift-off, or electrolytic plating.

[0007]

By the way, the thickness of the absorber layer of the reflection mask depends on the required mask contrast (multilayer film portion reflectance / absorber portion reflectance), the multilayer film reflectance and the absorber. Determined by the absorption coefficient of the substance used for. The mask contrast required for EUVL is estimated to be at least 100, ideally about 500 to 1000. The reflectance of the multilayer film has a wavelength of 13n.
Around 60 to 70% is obtained near m. At this time, when Cr is used for the absorber, the thickness of the absorber is about 70 nm to obtain the contrast 100, and the thickness of the absorber is about 100 nm to obtain the contrast 1000.
Will need the thickness of.

That is, in the conventional reflection mask, the minimum film thickness for obtaining the necessary contrast is determined by the material of the absorber used. Therefore, it is preferable to use a substance having a large absorption coefficient as the material of the absorber,
Absorbers made of materials currently being investigated require a thickness of at least 50 nm to 150 nm.

However, when performing pattern exposure by EUVL, the light incident on the reflection mask is oblique incidence slightly deviated from the direct incidence (for example, the incident angle on the reflection mask = 2).
~ 5 °). Therefore, if the absorber layer is thick, the light incident near the edge of the absorber pattern is shielded by the shadow of the absorber pattern even though it is a reflection region. For example, when the incident angle on the reflection mask is 5 °, the thickness of the absorber is 50
When the thickness of the absorber is 4.4 nm, the shaded portion is 4.4 nm, when the thickness of the absorber is 100 nm, the shaded portion is 8.7 nm, and when the thickness of the absorber is 150 nm, the shaded portion is 13.1 nm. . These shades correspond to 0.2 to 0.7% of the line width of the pattern at 400 nm L & S when the 1/5 reduction projection exposure is performed on the wafer.
Similarly, the line width corresponds to 2.9 to 8.7%. Therefore, as the thickness of the absorber increases, the contrast between the reflective portion (multilayer film) and the non-reflective portion (absorber pattern) near the edge deteriorates, and the resolution decreases. In order not to reduce the resolution, it is desirable to make the absorber layer as thin as possible.

When using the above-mentioned reflection mask, contamination (hereinafter referred to as contamination) is a problem. In a stepper using an i-line or an excimer laser, a pellicle is attached to a reticle corresponding to a reflection mask. The pellicle covers the pattern portion of the reticle and has a function of preventing dust and the like from adhering to the pattern surface. Even if dust adheres to the pellicle, it is far from the depth of focus of the projection optical system because it is far from the pattern surface, so the shadow of dust is not transferred.

However, in the wavelength range of EUVL,
Since the absorption coefficient of the material is large, there is no good material for the pellicle. Therefore, methods for mask protection have been devised (eg Charles Gwyn, et al. Extreme Ultravi.
olet Lithography A White Paper 1999 p.131-133).
However, in such a method, it is necessary to differentially exhaust the mask as a separate chamber, to partially flow gas over the mask or to make a temperature difference, which complicates the structure of the apparatus.

The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a reflection mask, an exposure apparatus and a cleaning method therefor capable of preventing transfer defects.

[0013]

In order to solve the above-mentioned problems, a reflection mask according to the present invention is formed on a substrate, an X-ray reflection multilayer film formed on the substrate, and the X-ray reflection multilayer film. And a absorber layer made of a substance having a low X-ray transmittance and having a predetermined pattern, the mask being formed between the X-ray reflection multilayer film and the absorber layer. It is characterized by further comprising a protective layer made of a photocatalytic material.

According to the above reflection mask, since the protective mask is provided between the X-ray reflection multilayer film and the absorber layer, the protective layer is made of a photocatalyst material, that is, X without the absorber layer is formed. Since the surface of the X-ray reflective multilayer film is covered with the above-mentioned protective layer, when the light (mainly visible light or ultraviolet light) is applied to the reflective mask, carbon contamination adhered to the X-ray reflective multilayer film of the mask will not occur. Decomposed by photocatalytic reaction. As a result, it is possible to secure the same characteristics of the portion requiring the reflection characteristics on the reflection mask, and it is possible to accurately transfer the pattern on the mask onto the sensitive substrate (wafer or the like).

The reflection mask of the present invention preferably further comprises a protective layer made of a photocatalytic material formed on the absorber layer. As mentioned above, the reflection mask is 2
Often used at an incident angle of 5 ° to 5 °, but if the thickness of the absorber is increased in order to obtain the contrast between the reflection part and the non-reflection part, the shadow of the edge part of the absorber becomes large. , Which causes deterioration of the contrast at the edge portion. Originally, the absorber does not reflect soft X-rays, but the part with contaminants behaves as if the absorber had become thick, and the pattern contrast of the part with contaminants decreased, resulting in poor transfer. May occur. However, if a protective layer is also formed on the absorber layer, contamination on the protective layer can be reduced, so that transfer defects due to contrast deterioration can be prevented and the life of the reflective mask can be extended. .

Further, the reflection mask according to the present invention comprises a substrate, an X-ray reflection multilayer film formed on the substrate, and a substance having a low X-ray transmittance formed on the X-ray reflection multilayer film. And a protective layer made of a photocatalyst material formed so as to cover the X-ray reflection multilayer film and the absorber layer. It is characterized by doing.

According to the above reflective mask, since the protective mask is provided with a protective layer made of a photocatalytic material formed so as to cover the X-ray reflective multilayer film and the absorber layer, the mask is exposed to light in an oxygen-containing atmosphere. Surface contaminants can be removed.
Therefore, there are the same actions and effects as described above.

The exposure apparatus according to the present invention comprises an X-ray light source for generating X-rays, an illumination optical system for guiding the X-rays from the X-ray light source to a reflection mask, and an X-ray from the reflection mask on a sensitive substrate. An exposure apparatus having a projection optical system for guiding the pattern of the reflection mask to the sensitive substrate, wherein the reflection mask comprises a substrate, an X-ray reflection multilayer film formed on the substrate, An absorber layer formed on the X-ray reflection multilayer film and made of a substance having a low X-ray transmittance and having a predetermined pattern, and formed between the X-ray reflection multilayer film and the absorber layer. And a protective layer made of a photocatalytic material. Alternatively, it is characterized by comprising a protective layer formed of a photocatalytic material so as to cover the X-ray reflective multilayer film and the absorber layer.

According to the above-mentioned exposure apparatus, since the protective layer made of a photocatalyst is formed between the X-ray reflection multilayer film of the reflection mask and the absorber layer, it is possible to irradiate the reflection mask with light. The carbon contamination attached to the reflection mask can be decomposed and removed, and transfer defects can be prevented. Further, since a complicated mechanism for preventing contamination of the reflection mask is not required, the cost of the apparatus is reduced, and the life of the reflection mask itself is extended, which contributes to the reduction of exposure cost.

The method for cleaning an exposure apparatus of the present invention is the method for cleaning an exposure apparatus, wherein the reflection mask of the present invention is used as a reflection mask, and ultraviolet rays are irradiated in an oxygen atmosphere to remove dust on the pattern surface. It is characterized by doing.

The method of cleaning the exposure apparatus according to the present invention is X
The reflection mask includes an X-ray light source that generates a line, an illumination optical system that guides the X-ray from the X-ray light source to a reflective mask, and a projection optical system that guides the X-ray from the reflective mask to a sensitive substrate. In a method of cleaning an exposure apparatus for transferring the pattern of (1) to a sensitive substrate, the substrate serving as the reflection mask, an X-ray reflective multilayer film formed on the substrate, and an X-ray reflective multilayer film formed on the X-ray reflective multilayer film. An absorber layer made of a substance having a low light transmittance and having a predetermined pattern, and a protective layer made of a photocatalytic material formed so as to cover the X-ray reflection multilayer film and the absorber layer. The reflective mask is characterized in that the reflective mask is irradiated with ultraviolet rays in an oxygen atmosphere to remove dust on the pattern surface.

According to the cleaning method of the exposure apparatus, since the protective layer made of the photocatalytic material is formed so as to cover the X-ray reflective multilayer film and the absorber layer, the reflective mask is used in the oxygen atmosphere. Since the carbon contamination adhering to the pattern surface can be decomposed and removed by irradiating with ultraviolet rays, the mask can be easily cleaned.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a reflection mask according to the first embodiment of the present invention.

As shown in FIG. 1, the reflection mask according to the first embodiment of the present invention has a substrate 1 made of silicon, and an X-ray reflection multilayer film 2 is provided on the substrate 1. Has been. As a material for forming the X-ray reflective multilayer film 2, EUVL is used to ensure high mask contrast.
High reflectance is obtained near the wavelength of 13 nm used in
Mo / Si, Ru / Si, Mo compound / Si, Ru compound / Si, Mo / Si compound, Ru / Si compound, Mo compound / Si compound or Ru compound / Si
Preference is given to using compounds. As the substrate 1, other materials may be used as long as the material has a surface roughness and a flatness satisfying desired values, and for example, glass or metal can be used.

An absorber layer 3 made of a substance having a low transmittance for soft X-rays is formed on the X-ray reflection multilayer film 2, and the absorber layer 3 is processed into a desired pattern shape. In order to suppress the reduction in the contrast of the absorber edge portion caused by the oblique incidence of the illumination light, it is desirable that the absorber layer 3 be formed as thin as possible. Therefore, it is desirable that the material used for forming the absorber layer has a large absorption coefficient in the used wavelength range. Wavelength 13 used in EUVL
near nm, Ag, Al, Au, Cd, Co, Cu, Fe, Cr, Ge,
In, Ir, Mn, Ni, Os, Pb, Pd, Pt, Re, Te, Ta, Sn, Z
n, or the absorption coefficient of these compounds is high, the absorber layer 3
This is preferable because the thickness of can be reduced.

In the reflection mask of FIG. 1, the absorber layer 3
Between the X-ray reflection multilayer film 2 and the X-ray reflection multilayer film, protection made of a photocatalytic material
Layer 4 has been formed. Also, the light is not touched on the absorber layer 3.
A protective layer 4 made of a medium layer is formed. Reflection of the invention
A material having a photocatalytic function for forming the protective tank 4 on the mask
Then, for example, TiO₂, Fe₂O₃, Cu₂O, In₂O₃, WO₃, Fe₂
TiO₃, PbO, V₂O_Five, FeTiO₃, Bi₂O₃, Nb₂O₃, SrTiO₃, Zn
O, BaTiO₃, CaTiO₃, KTaO ₃, SnO₂And ZrO₂Etc.
It

Next, a reflective mask according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a sectional view showing a reflection mask according to the second embodiment of the present invention.

As shown in FIG. 2, the reflection mask according to the second embodiment of the present invention has a substrate 1 made of silicon, and an X-ray reflection multilayer film 2 is provided on the substrate 1. Has been. The material forming the X-ray reflective multilayer film 2 is the same as that of the reflective mask of the first embodiment.
An absorber layer 3 is formed on the X-ray reflective multilayer film 2, and the absorber layer 3 is processed into a desired pattern shape. As the material used for forming the absorber layer 3, the same material as the reflection mask in the first embodiment is used. As the substrate 1, other materials may be used as long as they are materials whose surface roughness and flatness satisfy desired values, and for example, glass or metal can be used.

As shown in FIG. 2, in the reflection mask according to the second embodiment of the present invention, the protective layer 4 made of a photocatalytic material is formed so as to cover the X-ray reflection multilayer film 2 and the absorber layer 3.
Are formed. That is, the protective layer 4 made of a photocatalytic material covers the upper surface and side surfaces of the absorber layer 3 and the upper surface of the reflective multilayer film 2 without the absorber layer 3. There is no protective layer 4 between the absorber layer 3 and the reflective multilayer film 2. As for the material having a photocatalytic function for forming this protective layer, the same material as the reflective mask in the first embodiment is used.

Next, a method of manufacturing the reflection mask according to the first embodiment of the present invention shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a diagram showing a manufacturing process of the reflection mask shown in FIG. As shown in FIG. 3, a substrate 1 made of silicon is used as a substrate to form a Mo / Si multilayer film 2 and a protective layer 4 made of a photocatalytic material by an ion beam sputtering method (hereinafter referred to as IBS method) (see FIG. 1)). Then
A Ta layer is formed as the absorber layer 3, and a TiO ₂ layer is formed as the protective layer 4 made of a photocatalytic material (FIG. 3 (2)). Then, a positive resist 5 for electron beam is applied (FIG. 3 (3)), and the resist mask pattern 5a is exposed and developed by an electron beam drawing apparatus (FIG. 3 (4)). Using the resist pattern as a mask, the protective layer 4 and the absorber layer 3 are patterned by dry etching (FIG. 3 (5)). The resist is peeled off and washed to obtain a reflection mask having the patterns of the protective layer 4 and the absorber layer 3 (FIG. 3 (6)).

Next, a method of manufacturing the reflection mask according to the second embodiment of the present invention shown in FIG. 2 will be described with reference to FIG. FIG. 4 is a diagram showing a manufacturing process of the reflection mask shown in FIG. As shown in FIG. 4, a Mo / Si multilayer film 2 and a protective layer 4 made of a photocatalytic material are formed by the IBS method using a substrate 1 made of silicon as a substrate (FIG. 4 (1)). Then, a positive resist 5 for electron beam is applied (see FIG.
(2)), a resist mask pattern 5a by an electron beam drawing apparatus
Is exposed and developed (FIG. 4C). The absorber layer 3 is patterned by dry etching using the resist pattern as a mask (FIG. 4 (4)). The resist is stripped and washed to obtain a reflection mask having the absorber layer pattern (see FIG. 4).
(5)). After confirming that the obtained reflection mask pattern has no defects, a protective layer 4 made of a photocatalytic material is formed (FIG. 4 (6)).

Next, an exposure apparatus according to the present invention will be described with reference to the drawings. FIG. 5 is a configuration diagram showing an example of an X-ray exposure apparatus provided with the reflection mask according to the embodiment of the present invention.

The X-ray exposure apparatus mainly comprises an X-ray light source S, a condenser C, an illumination optical system IR, a mask M stage MST,
The projection optical system PR and the stage WST of the wafer W are included. The soft X-ray light source S is also provided with a laser L for plasma excitation, and a tube T for supplying a target material such as xenon. Laser light is focused on the xenon emitted from the tip of the tube T, and the target material in that portion is turned into plasma and emits soft X-rays. The condenser C collects the generated soft X-rays. In addition to the laser plasma light source, a discharge plasma light source or synchrotron radiation can be used. Illumination optics (IR1, IR2, IR3 and I
R4, etc.) is composed of an oblique incidence mirror that reflects X-rays obliquely incident on the reflection surface, a multilayer mirror whose reflection surface is formed of a multilayer film, a filter that transmits only X-rays of a predetermined wavelength, and the like. Has been done. The illumination optical system illuminates the mask M with X-rays having a desired wavelength.

Since no transparent substance exists in the X-ray wavelength range, a reflective mask is used as the mask M instead of the conventional transmissive mask. The projection imaging optical system is composed of a plurality of multilayer mirrors (PR1, PR2, PR3 and PR4) and the like. The circuit pattern formed on the mask M is imaged by the projection imaging optical system on the wafer W coated with the resist and transferred onto the resist. Since the X-rays are absorbed by the atmosphere and attenuated, all the optical paths thereof are maintained at a predetermined vacuum degree (for example, 1 × 10 ⁻⁵ Torr or less).

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications. For example,
In the above-described embodiment, the Mo / Si multilayer film having a wavelength of around 13 nm used in EUV lithography has been described, but the present invention is not limited to this, and other wavelength regions and other multilayer film materials can be used. However, the present invention can be applied.

[0036] Example Hereinafter, further detailed explanation of the present invention embodiment. Needless to say, the scope of the present invention is not limited to such examples. Example 1 The reflective mask shown in FIG. 1 was manufactured according to the manufacturing process shown in FIG. First, width 100 mm x length 100 mm x thickness 5
A substrate 1 made of silicon having a thickness of mm is used as a substrate, and a Mo / Si multilayer film 2 and a protective layer 4 made of a photocatalytic material are formed on the surface of the substrate 1 (see FIG. 3A). Mo / Si multilayer film 2
Is 40 layers, the cycle length is 6.9 nm, the film thickness ratio (= Mo layer thickness / cycle length) is 0.35, TiO ₂ is used as the photocatalyst material, and the thickness of the protective layer 4 is 2 nm. .

Next, the absorber layer 3 is formed with Ta as a material to a thickness of 50 nm. Next, the protective layer 4 made of a photocatalytic material is formed on the absorber layer 3. Ti as a photocatalytic material
O ₂ is used and the thickness of the protective layer 4 is set to 7 nm (FIG. 3 (2)).
reference). Then, a positive resist 5 for electron beam is applied on the protective layer 4 to a film thickness of about 1 μm (see FIG. 3C), and a resist mask pattern 5a (0.2
5-1 μmL & S) is exposed and developed (see FIG. 3 (4)). After the development, the protective layer 4 and the absorber layer 3 are patterned by dry etching using the resist pattern as a mask (see FIG. 3 (5)). Next, the resist is stripped and washed to obtain a reflection mask having the patterns of the protective layer 4 and the absorber layer 3 (see FIG. 3 (6)).

The reflection portion (multilayer film portion) of the reflection mask obtained as described above has a reflectance of about 65%, and the protective layer 4
The reflectivity of a normal multilayer mirror without
%) Is the same. The reflectance of the absorber layer portion is about 0.6%, and a pattern contrast of about 110 is obtained. Further, by intentionally adhering carbon contaminants to the obtained reflection mask and then irradiating it with ultraviolet rays in an oxygen atmosphere, carbon contaminants can be removed.

Example 2 The reflective mask shown in FIG. 2 was manufactured according to the manufacturing process shown in FIG. First, width 100 mm x length 100 mm x thickness 5
A substrate made of mm silicon is used as a substrate, and the Mo / Si multilayer film 2 and the absorber layer 3 are formed on the surface thereof by the IBS method (see FIG. 4 (1)). The Mo / Si multilayer film 2 has 40 layers, a cycle length of 6.9 nm, and a film thickness ratio (= Mo layer thickness / cycle length).
The absorber layer 3 is made of Ta and has a thickness of 7
0 nm.

Then, a positive type resist 5 for electron beam is applied on the absorber layer 3 to a film thickness of about 1 μm (see FIG. 4 (2)), and a resist mask pattern 5a is formed by an electron beam drawing apparatus.
(0.25 to 1 μmL & S) is exposed and developed (FIG. 4).
(3)). After the development, the absorber layer 3 is patterned by dry etching using the resist pattern as a mask (see FIG. 4 (4)). Then, the resist is stripped and washed to obtain a reflection mask having the pattern of the absorber layer 3 (see FIG. 4 (5)). After confirming that the obtained reflection mask pattern has no defects, the protective layer 4 made of a photocatalytic material is used.
To form a film. TiO ₂ is used as the photocatalyst material, and the protective layer 4
Has a thickness of 2 nm (see FIG. 4 (6)).

The reflectance of the reflection portion (multilayer film portion) of the reflection mask obtained as described above was about 65%, and the protective layer 4
The reflectivity of a normal multilayer mirror without
%) Is the same. The reflectance of the absorber layer portion is about 0.6%, and a pattern contrast of about 110 is obtained. Further, by intentionally adhering carbon contaminants to the obtained reflection mask and then irradiating it with ultraviolet rays in an oxygen atmosphere, carbon contaminants can be removed.

Example 3 The multilayer film 2 was a MoRu / Si multilayer film, the film thickness ratio (MoRu / Si layer thickness / period length) was 0.35, the absorber layer 3 was a Cr layer, and the absorber layer 3 was formed on the absorber layer 3. A reflective mask is obtained in the same manner as in Example 1, except that ZnO is used as the photocatalyst for forming the protective layer 4 and the thickness of the protective layer 4 is set to 7 nm.

The reflectance of the reflection portion (multilayer film portion) of the reflection mask obtained as described above was about 66%, and the protective layer 4
The reflectivity of a normal multi-layered film reflecting mirror (about 66
%) Is the same. The reflectance of the absorber layer is about 0.4%, and a pattern contrast of about 160 is obtained. Further, by intentionally adhering carbon contaminants to the obtained reflection mask and then irradiating it with ultraviolet rays in an oxygen atmosphere, carbon contaminants can be removed.

Example 4 The multilayer film 2 is a MoRu / Si multilayer film, the film thickness ratio (MoRu / Si layer thickness / period length) is 0.35, the absorber layer 3 is a Cr layer, and the protective layer 4 is formed. A reflective mask is obtained in the same manner as in Example 1 except that ZnO is used as the photocatalytic material and the thickness of the protective layer 4 is set to 2 nm.

The reflectance of the reflection portion (multilayer film portion) of the reflection mask obtained as described above is about 65%, and the protective layer 4
The reflectivity of a normal multi-layered film reflecting mirror (about 66
%) Is the same. The reflectance of the absorber layer portion is about 0.5%, and a pattern contrast of about 130 can be obtained. Further, by intentionally adhering carbon contaminants to the obtained reflection mask and then irradiating it with ultraviolet rays in an oxygen atmosphere, carbon contaminants can be removed.

Example 5 Sn as a photocatalytic material for forming the protective layer 4 on the absorber layer 3
A reflective mask is obtained in the same manner as in Example 1 except that O ₂ is used and the thickness of the protective layer 4 is set to 7 nm.

The reflectance of the reflection portion (multilayer film portion) of the reflection mask obtained as described above was about 66%, and the protective layer 4
The reflectivity of a normal multi-layered film reflecting mirror (about 66
%) Is the same. The reflectance of the absorber layer portion is about 0.2%, and a pattern contrast of about 330 can be obtained. Further, by intentionally adhering carbon contaminants to the obtained reflection mask and then irradiating it with ultraviolet rays in an oxygen atmosphere, carbon contaminants can be removed.

[0048]

As described above, according to the reflection mask of the present invention, the reflection mask further comprises the protective layer made of the photocatalytic material formed between the X-ray reflection multilayer film and the absorber layer. When the reflection mask is irradiated with light (mainly visible light or ultraviolet light), carbon contamination attached to the reflection mask is decomposed. Further, since the reflection mask according to the present invention has less contamination, it is possible to prevent such a transfer failure, prevent deterioration of contrast, and extend the life of the reflection mask. As described above, according to the reflection mask of the present invention, since the protective mask made of the photocatalytic material is formed between the X-ray reflection multilayer film and the absorber layer, that is, the absorber layer is formed. Since the surface of the X-ray reflective multilayer film that has not been formed is covered with the protective layer, when the light (mainly visible light or ultraviolet light) is applied to the reflection mask, the X
The carbon contamination adhering to the line reflection multilayer film is decomposed by a photocatalytic reaction. As a result, it is possible to secure the same characteristics of the portion requiring the reflection characteristics on the reflection mask, and it is possible to accurately transfer the pattern on the mask onto the sensitive substrate (wafer or the like).

In the reflective mask of the present invention, by forming the protective layer also on the absorber layer, contamination on the protective layer can be reduced, so that transfer defects due to contrast deterioration can be prevented, and the reflective mask can be prevented. The life of can be extended.

Since the exposure apparatus of the present invention includes the protective layer made of a photocatalyst formed between the X-ray reflection multilayer film of the reflection mask and the absorber layer, the reflection mask is irradiated with light. As a result, carbon contamination attached to the reflection mask can be decomposed and removed, and transfer defects can be prevented. Further, since a complicated mechanism for preventing contamination of the reflection mask is not required, the cost of the apparatus is reduced, and the life of the reflection mask itself is extended, which contributes to the reduction of exposure cost.

According to the cleaning method of the present invention, since the protective layer made of a photocatalytic material is formed so as to cover the X-ray reflection multilayer film and the absorber layer, the reflection mask is exposed to ultraviolet rays in an oxygen atmosphere. Since the carbon contamination adhering to the pattern surface can be decomposed and removed by irradiating with, the mask can be easily cleaned.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a reflection mask according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a reflection mask according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the reflection mask according to the first embodiment of the invention.

FIG. 4 is a diagram showing a manufacturing process of a reflection mask according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing an example of an X-ray exposure apparatus provided with a reflection mask according to an embodiment of the present invention.

[Explanation of symbols]

1 substrate 2 X-ray reflective multilayer film 3 absorber layers 4 protective layer 5 Positive resist S X-ray light source C capacitor IR illumination optical system MST mask stage WST Wafer stage T tube IR illumination optical system

Claims (7)

[Claims] 1. A substrate, an X-ray reflective multilayer film formed on the substrate, and a substance having a low X-ray transmittance formed on the X-ray reflective multilayer film and having a predetermined pattern. A reflection mask comprising an absorber layer, further comprising a protective layer made of a photocatalytic material formed between the X-ray reflection multilayer film and the absorber layer. 2. The reflection mask according to claim 1, further comprising a protective layer made of a photocatalytic material formed on the absorber layer. 3. A substrate, an X-ray reflective multilayer film formed on the substrate, and a substance having a low X-ray transmittance formed on the X-ray reflective multilayer film and having a predetermined pattern. A reflection mask comprising an absorber layer, the reflection mask further comprising a protective layer made of a photocatalytic material formed so as to cover the X-ray reflection multilayer film and the absorber layer. . 4. An X-ray light source for generating X-rays, an illumination optical system for guiding the X-rays from the X-ray light source to a reflective mask, and a projection optical system for guiding the X-rays from the reflective mask to a sensitive substrate.
And an X-ray reflection multilayer film formed on the substrate, the X-ray reflection multilayer film being formed on the substrate. Protective layer formed on the absorber layer made of a substance having a low X-ray transmittance and having a predetermined pattern, and a photocatalytic material formed between the X-ray reflective multilayer film and the absorber layer. An exposure apparatus comprising: a layer. 5. The exposure apparatus according to claim 4, wherein the reflection mask further includes a protective layer formed of a photocatalytic material on the absorber layer. 6. An X-ray light source for generating X-rays, an illumination optical system for guiding the X-rays from the X-ray light source to a reflection mask, and a projection optical system for guiding the X-rays from the reflection mask to a sensitive substrate. An exposure apparatus for transferring the pattern of the reflection mask onto a sensitive substrate, wherein the reflection mask includes a substrate, an X-ray reflection multilayer film formed on the substrate, and an X-ray reflection multilayer film on the X-ray reflection multilayer film. An absorber layer formed of a substance having a low X-ray transmittance and having a predetermined pattern, and a protective layer made of a photocatalytic material formed so as to cover the X-ray reflection multilayer film and the absorber layer. An exposure apparatus comprising: 7. An X-ray light source for generating X-rays, an illumination optical system for guiding the X-rays from the X-ray light source to a reflection mask, and a projection optical system for guiding the X-rays from the reflection mask to a sensitive substrate. A method of cleaning an exposure apparatus, comprising: transferring a pattern of the reflection mask to a sensitive substrate, wherein the reflection mask includes a substrate, an X-ray reflection multilayer film formed on the substrate, and an X-ray reflection multilayer film on the substrate. An absorber layer formed of a substance having a low X-ray transmittance and having a predetermined pattern, and a protection formed of a photocatalyst material formed so as to cover the X-ray reflection multilayer film and the absorber layer. A method for cleaning an exposure apparatus, comprising: using a reflective mask having a layer, and irradiating the reflective mask with ultraviolet rays in an oxygen atmosphere to remove dust on a pattern surface.