JP2003133205A - Reflex mask, method of manufacturing the same, and method of cleaning the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clean and remove deposits by forming a film comprising a material having fluid cleaning resistance on a surface. SOLUTION: A reflex mask has a mask blank 20 comprising an underlying board 21 and a multilayer film 22 that includes a plurality of kinds of materials differing in reflective indices on exposure wavelengths formed on the substrate board 21, a mask pattern formed on the mask blank 20, and a protective film resistant to medical fluid cleaning which coats at least one surface of the mask blank 20 or mask pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type mask, a reflection type mask manufacturing method and a reflection type mask cleaning method.

[0002]

2. Description of the Related Art Conventionally, with the high integration of semiconductor elements,
There is an urgent need to establish a new process technology that enables ultrafine processing of 100 [nm] or less. Also in the lithography technology, in order to improve the optical resolution by shortening the wavelength of the light source, the wavelength is 10 to 15 as compared with the ultraviolet ray by the conventional mercury lamp or excimer laser.
EUV lithography that enables high resolution using EUV (Extreme Ultraviolet) light as a light source that is as short as [nm] and one digit (digits) or more is being vigorously developed.

In this case, EUV light is extremely absorbed by a substance, and the refractive index of the substance for EUV light is almost equal to the value of vacuum. Therefore, since it is difficult to collect EUV light with a lens, a reflection optical system that is a combination of a convex mirror and a concave mirror is used as an optical system for EUV lithography (Journal of Precision Optics, Vol. 64, No. 2, 282).
(See Item-286 (1998)). In the case of a transmissive mask such as an optical reticle, the intensity of EUV light is significantly reduced due to absorption. Therefore, a reflective mask is used.

FIG. 2 is a sectional view of a conventional reflective mask.

As shown in the figure, the reflective mask is S
A base substrate 11 made of glass or silicon (Si) containing iO ₂ as a main component, a multilayer film 12 coated on the entire surface of the base substrate 11, and a desired pattern formed on the multilayer film 12. It has a mask pattern 13 made of a metal thin film.

Here, the multi-layer film 12 is formed by laminating layers made of two or more kinds of materials to obtain a high reflectance for EUV light which is substantially vertically incident on the surface of the reflective mask. , Layers made of materials having greatly different refractive indexes at exposure wavelengths are combined so as to be adjacent to each other. And the combination of several layers is the basic period,
The multi-layered film 12 is formed by repeatedly stacking for about 30 to 40 cycles.

Further, since the mask pattern 13 is made of a metal thin film formed in a desired pattern shape and absorbs EUV light to become a non-reflecting portion, an exposure contrast is produced.

Generally, in the conventional reflection type mask,
As the multilayer film 12 coated on the base substrate 11, one having a fundamental period formed by stacking a molybdenum (Mo) layer 12a and a silicon (Si) layer 12b is widely used. Then, by stacking at a cycle of about half of the exposure wavelength, the wavelength E of about 13.5 [nm] is obtained.
A maximum reflectance of about 70% for UV light can be obtained.

[0009]

However, in the above-mentioned conventional reflection type mask, when particles or deposits are attached, they may not be washed and removed. In this case, the reflective mask becomes unusable.

FIG. 3 is a first diagram showing a conventional reflective mask manufacturing process, FIG. 4 is a second diagram showing a conventional reflective mask manufacturing process, and FIG. 5 is a conventional reflective mask manufacturing process. It is a 3rd figure which shows.

First, the base substrate 1 is formed by sputtering.
1 is coated with a multilayer film 12, and a metal thin film 14 for a mask pattern is deposited on the entire surface of the multilayer film 12 by sputtering. At this time, another film may be deposited as a buffer layer under the metal thin film 14 in order to facilitate the mask pattern processing.

Next, a resist is applied on the entire surface of the metal thin film 14, and a resist pattern 15 having a desired pattern shape is formed by exposure and development by scanning with an electron beam or a laser beam, as shown in FIG. Form.

Then, as shown in FIG. 4, plasma dry etching is performed using the resist pattern 15 as a mask to remove the metal thin film 14 not masked by the resist pattern 15. Then, the resist pattern 1
When 5 is removed, as shown in FIG. 5, a reflective mask having a mask pattern 13 formed in a desired pattern can be obtained.

As the base substrate 11 of the reflective mask, a glass substrate which is widely used as a mask blank (mask material) is generally used. As the metal thin film 14, tantalum (Ta) and an alloy film containing tantalum as a main component (for example, TaGe, TaB, TaN).
Etc.) can be used. In this case, the tantalum film is a material suitable for the metal thin film 14 of the reflective mask because it has a high absorptance of EUV light and the mask pattern processing is easy. Further, the alloy film containing tantalum as a main component has an amorphous structure, so that it has a feature that it is possible to suppress a temporal change in film stress in the atmosphere. Furthermore, the tantalum nitride (TaN) film is a DUV
(Deep Ultraviolet) Due to the large reflectance difference between the multilayer film 12 and the light, the DUV
It is possible to enable mask pattern inspection using light (see Japanese Patent Application No. 2000-0486654).

By the way, generally, in a mask used in lithography, since particles and deposits adhere to the mask during use, wet cleaning is performed to remove them. In most cases, physically attached particles and the like are removed by pure water cleaning or cleaning in which pure water cleaning is subjected to physical impact (typically ultrasonic cleaning).

On the other hand, particles or the like that are chemically bonded on the surface of the mask cannot be removed completely by the above-mentioned cleaning method. Therefore, a cleaning method that removes by applying a chemical action using a chemical is required.

However, in the cleaning method using a chemical, it must be avoided that the chemical acts on the multilayer film 12 and the mask pattern 13 to change its characteristics. Therefore, it is necessary to select a chemical that can remove particles and the like without affecting the multilayer film 12 and the mask pattern 13.

When considering a method of removing particles and the like by using a chemical, LSI (Large S)
The cleaning method used in the case integrated circuit manufacturing technology is helpful. Here, as a cleaning method using a chemical well known as the cleaning method as a cleaning agent, a sulfuric acid / hydrogen peroxide cleaning (SP
M), ammonia perhydrogen cleaning (APM), hydrochloric acid perhydrogen cleaning (HPM), hydrofluoric acid cleaning (DHF), and the like.

First, in washing with sulfuric acid / hydrogen peroxide, sulfuric acid (H
₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ) are used as a cleaning agent having a strong oxidizing action. The cleaning with sulfuric acid / hydrogen peroxide is used to remove inorganic foreign substances such as metals and metal oxides, and also organic foreign substances such as resists are oxidatively decomposed.

In addition, a cleaning agent obtained by mixing ammonia (NH ₄ OH), hydrogen peroxide and water is used in the ammonia-hydrogen cleaning. Then, the foreign matter adhering to the surface of the substrate such as the semiconductor substrate is removed by the lift-off phenomenon caused by etching the substrate.

Further, in the washing with hydrochloric acid-hydrogenated water, hydrochloric acid is used.
Used as a cleaning agent that mixes (HCl), hydrogen peroxide, and water
To be done. Then, the heavy metal and the alkali metal are HCl-
H₂O ₂Elutes the complex as it forms a kind of complex in
To remove.

In the hydrofluoric acid cleaning, hydrofluoric acid (HF) is used as a cleaning agent, and is used for removing the natural oxide film and cleaning for finishing.

FIG. 6 is a sectional view of another conventional reflective mask,
FIG. 7 is a diagram showing a change in sheet resistance of a conventional tantalum nitride film by a chemical treatment in another reflective mask, and FIG. 8 is a diagram showing a change in film thickness by a chemical treatment of a silicon oxide film in another conventional reflection mask. It is a figure. In FIG. 7, the vertical axis represents the rate of change in sheet resistance [%] on the surface of the tantalum nitride film, and the vertical axis in FIG. 8 represents the rate of decrease [%] in the silicon oxide film.

When the reflective mask is cleaned by the cleaning method as described above, it is necessary to consider the influence of the cleaning agent on the material facing the surface of the mask. In the reflective mask shown in FIG. 6, the material of the base substrate 11 is glass (silicon oxide (SiO ₂ ) is the main component), and the uppermost layer of the multilayer film 12 is amorphous silicon (α−).
Si) and the mask pattern 13 is tantalum nitride (T
aN) film 17 and the buffer layer is the silicon oxide film 1
It is 6.

FIG. 7 shows the degree of change in sheet resistance of the tantalum nitride film 17 before and after being immersed in four types of chemical solutions of sulfuric acid, ammonia, hydrochloric acid and hydrofluoric acid, that is, before and after chemical solution treatment. ing. here,
The sheet resistance is the resistance of the film surface measured by the four-end probe method. In addition, since the sheet resistance value of the film surface does not change before and after the chemical solution treatment unless it is etched or altered by the chemical solution, the resistance to each chemical solution can be evaluated by the change of the sheet resistance of the film surface.

Further, in FIG. 8, the silicon oxide film 1
6 shows the amount of film loss as the amount of change in film thickness before and after the four types of chemical liquid treatments of sulfuric acid, ammonia, hydrochloric acid, and hydrofluoric acid for the material of No. 6.

As can be seen from FIGS. 7 and 8, the tantalum nitride film 17 has chemical solution cleaning resistance only in the case of sulfuric acid. Here, what is judged to have chemical solution cleaning resistance means that the changed value of the sheet resistance is within 1 [%].

Similarly, the silicon oxide film 16 has chemical solution cleaning resistance only in the case of sulfuric acid and hydrochloric acid. Further, in the case of amorphous silicon, the same result as that of the silicon oxide film 16 could be obtained.

Therefore, in the mask blank in which the multilayer film 12 having the silicon layer 12b as the uppermost layer is formed on the base substrate 11, when particles or the like which can be removed only by ammonia and hydrofluoric acid are attached, Since the particles and the like cannot be removed without affecting the silicon layer 12b, the mask blank cannot be used.

Further, in the reflection type mask as shown in FIG. 6 in which the mask pattern 13 is formed on the mask blank, only cleaning with sulfuric acid is possible, and it is removed only with ammonia, hydrochloric acid and hydrofluoric acid. If particles that cannot be adhered are attached, the particles cannot be removed without affecting the silicon oxide film 16 and the tantalum nitride film 17.
The reflective mask cannot be used.

The present invention solves the above-mentioned problems of the conventional reflective mask, and by forming a film made of a material having chemical solution cleaning resistance on the surface, a reflective mask capable of cleaning and removing adhered matters. The purpose is to provide.

[0032]

To this end, the reflective mask of the present invention comprises a base substrate and a multilayer film formed on the base substrate and made of a plurality of types of materials having different refractive indices at the exposure wavelength. It has a mask blank, a mask pattern formed on the mask blank, and a chemical-resistant cleaning protective film for coating at least one surface of the mask blank or the mask pattern.

In another reflective mask of the present invention, the multilayer film further comprises silicon or beryllium and molybdenum, and the uppermost layer is a silicon layer or beryllium layer.

In yet another reflective mask of the present invention, the chemical-resistant cleaning protective film is made of ruthenium and coats at least one surface other than the incident light reflecting surface.

In still another reflective mask of the present invention, the mask pattern further includes a tantalum nitride film, and the chemical-resistant cleaning protective film includes a mask pattern protective film that coats the mask pattern.

In still another reflective mask of the present invention, the mask pattern protective film is made of tantalum.

In still another reflective mask of the present invention, the mask pattern protective film is a tantalum oxide film formed by oxidizing a tantalum film coating the mask pattern.

In still another reflective mask of the present invention, the mask pattern protective film is a tantalum oxide film formed by a sputtering method, a CVD method or the like.

In still another reflective mask of the present invention, the mask pattern further comprises a tantalum film or a tantalum alloy film.

In still another reflective mask according to the present invention, the chemical-resistant cleaning protective film further includes a mask pattern protective film made of tantalum oxide for coating the mask pattern.

In yet another reflective mask of the present invention, it is used for forming a fine pattern on a semiconductor device.

In the reflective mask manufacturing method of the present invention, the mask pattern of the reflective mask is removed by chemical cleaning to form another mask pattern on the mask blank.

In the reflective mask cleaning method of the present invention, the reflective mask is cleaned with a chemical solution.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a mask blank of a reflective mask according to the first embodiment of the present invention.

As shown in the drawing, a mask blank 20 as a mask material is provided with a base substrate 21 made of glass or silicon (Si) containing silicon oxide (SiO ₂ ) as a main component, and the base substrate 21. Molybdenum (M
o) It has a multilayer film 22 formed by laminating a layer 22a and a silicon layer 22b. The uppermost layer of the multilayer film 22 is the silicon layer 22b. Then, the mask blank 20 transfers the pattern on the mask onto the multilayer film 22 in the same manner as the mask blanks described in "Prior Art" to enable ultrafine processing of a semiconductor device of 100 nm or less. It is suitable for a reflection type mask used in EUV lithography for the purpose.

EUV is electromagnetic radiation in a wavelength band of 3 to 50 [nm] called extreme ultraviolet or far ultraviolet,
Also called soft X-ray. In addition, in the EUV lithography, generally, an EU light having a wavelength of about 10 to 15 [nm] is used.
UV light is used.

The multilayer film 22 is for reflecting EUV light, has the same structure as the multilayer film 12 of the reflection type mask described in "Prior Art", and has a surface of the reflection type mask. In order to obtain a high reflectance with respect to EUV light that is incident almost perpendicularly to the layers, layers made of materials having greatly different refractive indices at the exposure wavelength are combined so as to be adjacent to each other. The combination of a plurality of layers is used as a basic cycle, and the multilayer film 22 is formed by repeatedly stacking for about 30 to 40 cycles. For example,
A maximum reflectance of about 70% is obtained for EUV light having a wavelength near 13.5 nm.

In the present embodiment, the periphery of the mask blank 20, that is, the multilayer film 22 and the base substrate 21.
A ruthenium (Ru) film 23 as a chemical-resistant cleaning protective film is coated on the front and back surfaces and the entire side wall of the. The ruthenium film 23 is formed by vapor deposition, sputtering, CV
It is coated by method D or the like. Further, before forming the multilayer film 22, a ruthenium film 23 may be formed on the front and back surfaces or the entire sidewalls of the base substrate 21.

Then, a metal thin film for a mask pattern is deposited on the entire surface of the ruthenium film 23 on the surface of the base substrate 21 (upper surface in the drawing) by sputtering. In order to facilitate the mask pattern processing, another film may be deposited as a buffer layer under the metal thin film. Next, a resist is applied on the entire surface of the metal thin film, and a resist pattern having a desired pattern shape is formed by exposure and development by scanning with an electron beam or laser light. Subsequently, plasma dry etching is performed using the resist pattern as a mask to remove the metal thin film that is not masked by the resist pattern, and then the resist pattern is removed to obtain a reflective mask having a mask pattern formed in a desired pattern. Obtainable.

The mask blanks 20 in which the periphery of the multilayer film 22 and the base substrate 21 thus formed are coated with the ruthenium film 23, the chemicals generally used in the semiconductor manufacturing process such as the LSI manufacturing process are used as a cleaning agent. The cleaning method used, that is, the chemical cleaning has very excellent chemical cleaning resistance.

FIG. 9 is a diagram showing changes in sheet resistance due to chemical treatment of the ruthenium film in the first embodiment of the present invention. In the figure, the vertical axis represents the rate of change [%] in sheet resistance on the surface of the ruthenium film.

In the present embodiment, as described in "Problems to be Solved by the Invention", sulfuric acid / hydrogen peroxide cleaning (SPM), ammonia, which is well known as a cleaning method used in LSI manufacturing technology, is used. Washing with excess water (AP
M), hydrochloric acid / hydrogen peroxide cleaning (HPM) and hydrofluoric acid cleaning (DHF)
Sulfuric acid (H ₂ S
Tests were carried out on chemical liquid treatment with four kinds of chemicals, O ₄ ), ammonia (NH ₄ OH), hydrochloric acid (HCl) and hydrofluoric acid (HF). Then, the degree of change in sheet resistance on the surface of the ruthenium film 23 was measured before and after the chemical treatment with the four types of chemicals. Here, the sheet resistance is the resistance of the film surface measured by the four-end probe method.

Then, the sheet resistance of the surface of the ruthenium film 23 after the chemical treatment was changed as shown in FIG. 9 with respect to the sheet resistance of the surface of the ruthenium film 23 before the chemical treatment with the four kinds of chemicals. In this case, unless the ruthenium film 23 is etched or altered by the chemical solution treatment, the sheet resistance value of the film surface does not change before and after the chemical solution treatment. Therefore, the chemical solution cleaning resistance is evaluated by the change of the sheet resistance of the film surface. be able to. Here, when the rate of change in sheet resistance is within 1 [%], it can be determined that the sheet has chemical cleaning resistance.

As shown in FIG. 9, in the ruthenium film 23 formed around the mask blanks 20 in this embodiment, the sheet resistance value of the film surface does not change before and after the chemical treatment with all chemicals, that is, , The change rate is within 1 [%], it can be seen that it has chemical solution cleaning resistance. Therefore, the reflective mask formed by using the mask blanks 20 is subjected to chemical treatment to remove the particles and the like even if particles or deposits are chemically bonded and attached to the surface. be able to. In this case, since the periphery of the mask blank 20 is coated with the ruthenium film 23, the multilayer film 22
Etc. will not be altered or damaged by chemical treatment.

In the present embodiment, the multilayer film 2
Although the surface of No. 2 is the silicon layer 22b, even if the surface is the molybdenum layer 22a, the same characteristics can be obtained by coating with the ruthenium film 23. Further, when molybdenum has chemical solution cleaning resistance equivalent to that of ruthenium, particles or the like can be removed by performing the chemical solution treatment as described above without coating the surface of the molybdenum layer 22a with the ruthenium film 23. . Further, the silicon layer 22b may be replaced by a beryllium (Be) layer, and the multilayer film 22 may be formed by a molybdenum layer 22a and a beryllium layer.

As described above, in this embodiment, since the entire surface of the mask blank 20 is coated with the ruthenium film 23, the cleaning method using sulfuric acid / hydrogen peroxide and ammonia / hydrogen peroxide, which are cleaning methods generally used in the semiconductor manufacturing process, are used. Even if the reflective mask is washed by washing, hydrochloric acid / hydrogen peroxide washing, and hydrofluoric acid washing, the reflective mask is not deteriorated or damaged.

Next, a second embodiment of the present invention will be described. Note that description of the same structure and operation as those of the first embodiment will be omitted.

FIG. 10 is a sectional view of a reflective mask according to the second embodiment of the present invention.

As shown in the figure, the reflective mask 30
Is tantalum nitride (TaN) formed as a mask pattern on the base substrate 21 and the multilayer film 22 of the mask blank 20 having the same configuration as that of the first embodiment.
It has a membrane 31. The tantalum nitride film 31 absorbs EUV light incident on the reflective mask, and another film may be deposited as a buffer layer under the tantalum nitride film 31. Then, a thin tantalum film (or a tantalum alloy film) 32 is coated on the outermost surface and the side wall of the tantalum nitride film 31 as a chemical solution cleaning protection film.

Next, the manufacturing process of the reflective mask 30 will be described.

FIG. 11 is a first diagram showing a manufacturing process of a reflective mask according to the second embodiment of the present invention, and FIG. 12 shows a manufacturing process of a reflective mask according to the second embodiment of the present invention. FIG. 2 and FIG. 13 are third diagrams showing the manufacturing process of the reflection type mask in the second embodiment of the present invention, and FIG.
FIG. 4 is a fourth diagram showing the manufacturing process of the reflective mask according to the second embodiment of the present invention.

First, referring to FIG. 1 in the first embodiment.
A thin film of tantalum nitride is deposited as a metal thin film for a mask pattern on the entire surface of the ruthenium film 23 on the surface of the mask blank 20 having the same structure as shown in FIG. 1 by a sputtering method, a CVD method or the like. Note that another film may be deposited as a buffer layer below the thin film of tantalum nitride in order to facilitate mask pattern processing. Then, similarly to the first embodiment, a resist pattern is formed on the thin film of tantalum nitride, and plasma dry etching is performed using the resist pattern as a mask to obtain a desired pattern as shown in FIG. Tantalum nitride film 3 as a mask pattern formed on the substrate
1 can be obtained.

Next, as shown in FIG. 12, the entire surface of the mask blank 20 on which the tantalum nitride film 31 is formed is subjected to a sputtering method, a CVD method or the like.
A tantalum film (or a tantalum alloy film such as TaGe or TaB) 32 is formed. Subsequently, a photoresist is applied on the entire surface of the tantalum film 32, the resist is exposed and developed along the mask pattern, and a resist pattern 35 is formed as shown in FIG. Subsequently, plasma dry etching is performed using the resist pattern 35 as a mask, and as shown in FIG.
At 5 the unmasked tantalum film 32 is removed. Then, by removing the resist pattern 35, the reflective mask 30 as shown in FIG. 10 is formed.

As a result, the ruthenium film 23 is coated on the periphery of the mask blank 20, that is, on the front and back surfaces and the entire sidewalls of the multilayer film 22 and the base substrate 21, and the entire surface of the tantalum nitride film 31 serving as a mask pattern is covered with tantalum. The reflective mask 30 coated with the film (or the tantalum alloy film) 32 can be obtained.

The reflective mask 30 of this embodiment having such a structure can be cleaned by a cleaning method other than the ammonia-hydrogen peroxide cleaning.

FIG. 15 is a diagram showing changes in sheet resistance due to chemical treatment of the tantalum film, the tantalum nitride film and the ruthenium film in the second embodiment of the present invention. The vertical axis in the figure represents the rate of change [%] of the sheet resistance on the surfaces of the tantalum film, the tantalum nitride film and the ruthenium film.

As shown in the figure, the tantalum nitride film 31
When the chemical solution treatment with hydrochloric acid and hydrofluoric acid is performed, the rate of change in sheet resistance on the film surface is increased.
No. 2 shows almost no change in sheet resistance. This indicates that the tantalum film 32 has chemical solution cleaning resistance to hydrochloric acid and hydrofluoric acid. Therefore, by coating the surface of the tantalum nitride film 31 as a mask pattern with the tantalum film 32, it is possible to carry out a chemical treatment with hydrochloric acid and hydrofluoric acid to remove particles and the like.

As described above, in the present embodiment, the tantalum film (or the tantalum alloy film of TaGe, TaB, etc.) 32 is coated on the entire peripheral surface of the tantalum nitride film 31 as the mask pattern. Even if the reflective mask 30 is cleaned by the commonly used cleaning methods such as sulfuric acid / hydrogen peroxide cleaning, hydrochloric acid / hydrogen peroxide cleaning, and hydrofluoric acid cleaning, the mask pattern is not altered or damaged.

Next, a third embodiment of the present invention will be described. It should be noted that description of the same structure and the same operation as those of the first and second embodiments will be omitted.

FIG. 16 is a sectional view of a reflective mask according to the third embodiment of the present invention.

As shown in the figure, the reflective mask 40 in the present embodiment is formed on the base substrate 21 and the multilayer film 22 of the mask blank 20 having the same structure as in the first and second embodiments. , Having a tantalum nitride film 31 formed as a mask pattern. Note that another film may be deposited as a buffer layer under the tantalum nitride film 31. A thin tantalum oxide (TaO) film 42 is coated on the outermost surface and sidewalls of the tantalum nitride film 31.

In the present embodiment, the surface and side walls of the tantalum nitride film 31 as a mask pattern are coated with a tantalum film by the same manufacturing process as in the second embodiment, and the tantalum film contains oxygen. The tantalum oxide film 42 as a chemical-resistant cleaning protective film is formed on the surface and the side wall of the tantalum nitride film 31 by oxidation by heat treatment or plasma treatment in a dark gas atmosphere.

In the reflective mask 40 of the present embodiment thus formed, the tantalum nitride film 31 as a mask pattern functioning as an absorber that absorbs EUV light is coated with a tantalum oxide film 42 on the periphery. In comparison with the tantalum nitride film 31 of the second embodiment, it has the same chemical solution cleaning resistance and D
The mask contrast for UV light can be increased. This is because the tantalum oxide film has a smaller reflectance for DUV light than the tantalum film (see Japanese Patent Application No. 2001-043720).

Here, DUV is electromagnetic radiation in the wavelength band of 100 to 250 [nm] called deep ultraviolet or vacuum ultraviolet.

As described above, in the present embodiment, the tantalum oxide film 42 is coated on the entire peripheral surface of the tantalum nitride film 31 as the mask pattern. Even if the reflective mask 40 is washed by washing with water, washing with hydrochloric acid / hydrogen peroxide, and washing with hydrofluoric acid, the mask pattern is not altered or damaged. Moreover, the mask contrast for DUV light is not reduced.

Next explained is the fourth embodiment of the invention. Note that description of the same structure and the same operation as those of the first to third embodiments will be omitted.

FIG. 17 is a first diagram showing a manufacturing process of a reflective mask according to the fourth embodiment of the present invention, and FIG. 18 shows a manufacturing process of a reflective mask according to the fourth embodiment of the present invention. FIG. 2 and FIG. 19 are third and second views showing the manufacturing process of the reflective mask in the fourth embodiment of the present invention.
FIG. 0 is a fourth diagram showing the manufacturing process of the reflective mask according to the fourth embodiment of the present invention.

Reflective mask 40 in the present embodiment.
Is similar to that of the third embodiment, except for the step of forming a tantalum oxide film that coats the periphery of the tantalum nitride film 31 as a mask pattern.

First, FIG. 1 in the first embodiment.
A thin film of tantalum nitride is deposited as a metal thin film for a mask pattern on the entire surface of the ruthenium film 23 on the surface of the mask blank 20 as shown in FIG. Note that another film may be deposited as a buffer layer below the thin film of tantalum nitride in order to facilitate mask pattern processing. Then, similarly to the first embodiment, a resist pattern is formed on the thin film of tantalum nitride, and plasma dry etching is performed using the resist pattern as a mask.
As shown in, the tantalum nitride film 31 as a mask pattern formed in a desired pattern can be obtained.

Next, as shown in FIG. 18, the entire surface of the mask blank 20 having the tantalum nitride film 31 formed thereon is formed by a sputtering method, a CVD method or the like.
A tantalum oxide film 52 is formed. Subsequently, a photoresist is applied on the entire surface of the tantalum oxide film 52, the resist is exposed and developed along the mask pattern, and a resist pattern 35 is formed as shown in FIG. Subsequently, plasma dry etching is performed using the resist pattern 35 as a mask to remove the tantalum oxide film 52 which is not masked by the resist pattern 35, as shown in FIG. Then, by removing the resist pattern 35, a reflective mask 40 similar to that shown in FIG. 16 in the third embodiment is formed.

As a result, the periphery of the mask blank 20, that is, the front and back surfaces and the entire sidewalls of the multilayer film 22 and the base substrate 21 are coated with the ruthenium film 23 as a chemical-resistant cleaning protection film, and tantalum nitride as a mask pattern is coated. It is possible to obtain the reflection-type mask 40 in which the entire surface around the film 31 is coated with the tantalum oxide film 52 as the chemical-resistant solution cleaning protective film.

As described above, in the present embodiment, when forming the tantalum oxide film 52 which coats the entire peripheral surface of the tantalum nitride film 31 as the mask pattern, the tantalum oxide film 52 is directly formed by the sputtering method, the CVD method or the like. To form. Therefore, the oxidation process for oxidizing the tantalum film can be omitted, and the manufacturing process of the reflective mask 40 can be simplified.

Next explained is the fifth embodiment of the invention. Note that description of the same structure and the same operation as those of the first to fourth embodiments will be omitted.

FIG. 21 is a sectional view of a reflective mask according to the fifth embodiment of the present invention.

The reflective mask in this embodiment is the same as in the third and fourth embodiments, except that the step of forming a tantalum oxide film for coating the periphery of the tantalum nitride film 31 as a mask pattern is performed. Be different.

First, referring to FIG. 1 in the first embodiment.
A thin film of tantalum (or a tantalum alloy such as TaGe or TaB) is deposited as a metal thin film for a mask pattern on the entire surface of the ruthenium film 23 on the surface of the mask blank 20 as shown in FIG. Let Note that another film may be deposited as a buffer layer under the thin film of tantalum (or tantalum alloy) in order to facilitate mask pattern processing. And
Similar to the first embodiment, a resist pattern is formed on the thin film of tantalum (or tantalum alloy), and plasma dry etching is performed using the resist pattern as a mask to form a mask having a desired pattern. Tantalum film as a pattern (or TaGe, TaB
Can be obtained.

Next, the tantalum film (or TaGe, T
a tantalum alloy film 41 such as aB) is oxidized by heat treatment or plasma treatment in a gas atmosphere containing oxygen, so that the surface and the side wall of the tantalum film (or tantalum alloy film) 41 are thin as a chemical-resistant cleaning protective film. A tantalum oxide film 42 is formed.

As described above, in the present embodiment, the tantalum film (or TaGe, T) as the mask pattern is used.
By oxidizing the tantalum alloy film 41 such as aB) 41, a tantalum oxide film 42 is coated on the entire circumference of the tantalum film (or tantalum alloy film such as TaGe or TaB) 41. Therefore, the step of newly forming a thin film that coats the periphery of the mask pattern can be omitted, and the manufacturing process of the reflective mask can be simplified.

Further, the stress change of the mask pattern due to the oxidation in the atmosphere can be suppressed. Moreover, when the outermost surface of the mask pattern is a tantalum film, the mask contrast with respect to DUV light is lowered, but the formation of the tantalum oxide film 42 can suppress the reduction in mask contrast with respect to DUV light.

Furthermore, the reflective mask of this embodiment is
It can be cleaned by a cleaning method other than the ammonia-hydrogen cleaning.

Next explained is the sixth embodiment of the invention. It should be noted that description of the same components and the same operations as those of the first to fifth embodiments will be omitted.

FIG. 22 is a sectional view of a reflective mask in the sixth embodiment of the present invention, and FIG. 23 is a sectional view of mask blanks of the reflective mask in the sixth embodiment of the present invention.

In this embodiment, the reflective mask 30 is used.
Has a structure similar to that of the first embodiment, and has a mask pattern 51 made of tantalum nitride, tantalum, a tantalum alloy, or tantalum oxide on a mask blank 20 whose periphery is coated with a ruthenium film 23.
When the reflective mask 30 is cleaned with ammonia / hydrogen peroxide, the ruthenium film 23 has chemical solution cleaning resistance against ammonia, so that the mask blanks 20 are not damaged. On the other hand, as described in the second embodiment, since tantalum nitride, tantalum, a tantalum alloy, or tantalum oxide does not have chemical cleaning resistance against ammonia, when the ammonia-hydrogen cleaning is performed, the mask is removed. The pattern 51 is etched and removed with aqueous ammonia. As a result, as shown in FIG. 23, the ruthenium film 2
The mask blank 20 coated with 3 remains.

As described above, in the present embodiment, when the mask pattern 51 is no longer needed, the mask blanks 20 the periphery of which is coated with the ruthenium film 23 are damaged by performing ammonia-hydrogen peroxide cleaning. Instead, the mask pattern 51 can be removed. Therefore, a new mask pattern can be formed on the mask blank 20. Therefore,
The mask blanks 20 can be reused.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention, and they are not excluded from the scope of the present invention.

[0097]

As described in detail above, according to the present invention, the entire surface of the reflective mask, including the back surface, is thinly coated with a film having a chemical cleaning resistance such as a ruthenium film. The chemical solution cleaning resistance can be improved. Further, by intentionally forming tantalum oxide on the whole or surface of a tantalum nitride film, a tantalum film, or a tantalum alloy film that is an EUV light absorber film, the stress change of the absorber due to oxidation in the atmosphere is suppressed. In addition, the reflectance of the surface of the absorber with respect to DUV light can be reduced, and the resistance to chemical cleaning can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a mask blank of a reflective mask according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a conventional reflective mask.

FIG. 3 is a first diagram showing a manufacturing process of a conventional reflective mask.

FIG. 4 is a second diagram showing a manufacturing process of a conventional reflective mask.

FIG. 5 is a third diagram showing the manufacturing process of the conventional reflective mask.

FIG. 6 is a cross-sectional view of another conventional reflective mask.

FIG. 7 is a diagram showing changes in sheet resistance due to chemical treatment of a tantalum nitride film in another conventional reflective mask.

FIG. 8 is a diagram showing a change in film thickness of a silicon oxide film in another conventional reflective mask due to chemical treatment.

FIG. 9 is a diagram showing changes in sheet resistance due to chemical treatment of the ruthenium film in the first embodiment of the present invention.

FIG. 10 is a sectional view of a reflective mask according to a second embodiment of the present invention.

FIG. 11 is a first diagram showing a manufacturing process of the reflective mask according to the second embodiment of the present invention.

FIG. 12 is a second diagram showing a manufacturing process of the reflective mask according to the second embodiment of the present invention.

FIG. 13 is a third view showing the manufacturing process of the reflective mask in the second embodiment of the invention.

FIG. 14 is a fourth diagram showing the manufacturing process of the reflective mask in the second embodiment of the invention.

FIG. 15 is a diagram showing changes in sheet resistance due to chemical treatment of a tantalum film, a tantalum nitride film, and a ruthenium film in the second embodiment of the present invention.

FIG. 16 is a sectional view of a reflective mask according to a third embodiment of the present invention.

FIG. 17 is a first diagram showing a manufacturing process of the reflective mask in the fourth embodiment of the invention.

FIG. 18 is a second diagram showing the manufacturing process of the reflective mask in the fourth embodiment of the invention.

FIG. 19 is a third view showing the manufacturing process of the reflective mask in the fourth embodiment of the invention.

FIG. 20 is a fourth diagram showing the manufacturing process of the reflective mask in the fourth embodiment of the invention.

FIG. 21 is a sectional view of a reflective mask according to a fifth embodiment of the present invention.

FIG. 22 is a sectional view of a reflective mask according to a sixth embodiment of the present invention.

FIG. 23 is a cross-sectional view of mask blanks of a reflective mask according to a sixth embodiment of the present invention.

[Explanation of symbols]

20 mask blanks 21 Base substrate 22 Multi-layer film 22b Silicon layer 23 Ruthenium film 30, 40 reflective mask 31 Tantalum nitride film 32, 41 tantalum film 42,52 tantalum oxide film 51 mask pattern

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naofumi Yoneda             2-1-1 Shibasaki, Chofu-shi, Tokyo Osamu Shimada             Chemical Industry Co., Ltd. F-term (reference) 2H095 BA01 BA10 BB22 BC20                 5F046 CB17 GD10

Claims (12)

[Claims] 1. A mask blank comprising: (a) a base substrate and a multilayer film formed on the base substrate and made of a plurality of kinds of materials having different refractive indices at exposure wavelengths; and (b) formed on the mask blank. Mask pattern, (c)
A reflective mask comprising: a chemical-resistant cleaning protective film for coating at least one surface of the mask blank or the mask pattern. 2. The reflective mask according to claim 1, wherein the multilayer film is made of silicon or beryllium and molybdenum, and the uppermost layer is a silicon layer or beryllium layer. 3. The reflective mask according to claim 1, wherein the chemical-resistant cleaning protective film is made of ruthenium and coats at least one surface other than the incident light reflecting surface. 4. The mask pattern includes a tantalum nitride film, and the chemical-resistant cleaning protective film includes a mask pattern protective film that coats the mask pattern.
The reflective mask according to any one of 1 to 3. 5. The reflective mask according to claim 4, wherein the mask pattern protective film is made of tantalum. 6. The reflective mask according to claim 4, wherein the mask pattern protective film is a tantalum oxide film formed by oxidizing a tantalum film coating the mask pattern. 7. The reflective mask according to claim 4, wherein the mask pattern protective film is a tantalum oxide film formed by a sputtering method, a CVD method or the like. 8. The reflective mask according to claim 1, wherein the mask pattern comprises a tantalum film or a tantalum alloy film. 9. The reflective mask according to claim 8, wherein the chemical-resistant cleaning protective film comprises a mask pattern protective film made of tantalum oxide for coating the mask pattern. 10. The reflective mask according to claim 1, which is used for forming a fine pattern on a semiconductor device. 11. (a) The mask pattern of the reflective mask according to claim 1 is removed by chemical cleaning, and (b) another mask pattern is formed on the mask blanks. A method for manufacturing a reflective mask, comprising: 12. A method of cleaning a reflective mask, comprising: (a) cleaning the reflective mask according to claim 1 with a chemical solution.