JP5317137B2 - Mask blank and mask - Google Patents

Description

In the present invention, as a resist species, an acid of a catalyst substance generated in a resist film by exposure is
The present invention relates to a mask blank, a mask, and the like using a chemically amplified resist that develops a resist function by reacting with a functional group or a functional substance that controls solubility of a polymer in a subsequent heat treatment step.

Photomask (used for microfabrication technology that is a manufacturing method of semiconductor devices etc. (LSI etc.)
In the production of a reticle, for example, a chromium film as a light shielding layer is formed on a transparent substrate, a chromium oxide film as an antireflection layer is formed on the chromium film, and a resist film is formed on the chromium oxide film. A prepared photomask blank is prepared in advance. In this photomask blank, selective exposure of the resist is performed, and a resist pattern is formed through post-exposure baking and development, and the chromium oxide film and the chromium film are selectively etched using the resist pattern as a mask. The photomask is manufactured by removing and forming a predetermined mask pattern.
Further, in the manufacture of a halftone phase shift mask used in recent ultra-fine processing technology, for example, a chromium oxide film or a chromium fluoride film or an oxidation and / or oxidation film having both a light shielding function and a phase shift function on a transparent substrate. Alternatively, a phase shift mask blank prepared by forming a halftone film of a molybdenum nitride silicide film and forming a resist film on the halftone film is prepared in advance. Then, in this phase shift mask blank, the resist is selectively exposed, a resist pattern is formed through post-exposure baking and development, and both the light shielding function and the phase shift function are performed using this resist pattern as a mask. The phase shift mask is manufactured by selectively removing the provided halftone film by etching to form a predetermined mask pattern.

In the mask manufacturing field described above, the acceleration voltage of an electron beam in resist drawing (exposure) using an electron beam is about to shift from the current 10 to 20 keV to 50 keV or more. This is because it is necessary to resolve a finer resist pattern by reducing the forward scattering of the electron beam passing through the electron beam resist and increasing the focusing property of the electron beam. When the acceleration voltage of the electron beam is low, forward scattering occurs on the resist surface or in the resist, and when there is forward scattering, the resolution of the resist deteriorates.
However, when the acceleration voltage of the electron beam is 50 keV or more, forward scattering decreases in inverse proportion to the acceleration voltage, and energy imparted to the resist by forward scattering decreases.
With the electron beam resist used at 0 keV, the sensitivity of the resist is insufficient and the throughput is lowered. Therefore, in the mask manufacturing field, it has become necessary to use a chemically amplified resist having high sensitivity to high acceleration voltage and high resolution.

A photomask blank and a method for manufacturing the photomask will be described in detail with reference to FIG.
First, a chromium film 2 as a light shielding film and a chromium oxide film 3 as an antireflection film are formed intermittently or continuously on the surface of a transparent substrate 1 such as synthetic quartz by a sputtering method or the like. Then
On the chromium oxide film 3, “catalytic substance acid generated in the resist film by exposure reacts with a functional group or functional substance that controls the solubility of the polymer in the subsequent heat treatment step, thereby developing a resist function. (Chemical amplification resist) is applied by spin coating, etc., and then heat treated (baked)
And dried to form a chemically amplified resist film 4 to obtain mask blanks 5 (FIG. 1A
)).
Next, a predetermined portion is selectively irradiated with light or an electron beam, and then the blanks 5 (that is, the chemically amplified resist film 4) is baked, and then the chemically amplified resist film 4 is developed and exposed. The resist pattern 4a is formed by removing the part (FIG. 1B).
Next, the exposed chromium oxide film 3 and the chromium film 2 are removed by a wet etching process using an etching solution (for example, a ceric ammonium nitrate chromium etching solution) or a dry etching process using an etching gas (for example, chlorine gas). Thereafter, the resist pattern 4a is removed to obtain a photomask 6 (FIG. 1C).
In the development process, as shown in FIG. 2A, there is a problem that a footing-like protrusion 7 is generated at the bottom of the chemically amplified resist film 4 (resist film near the chromium oxide film). . Such a skirt-like protrusion 7 is an unnecessary residue of the exposed portion 8 that should be completely removed by the development process, and the edge portions of the pattern formed on the chromium oxide film 3 and the chromium film 2 are notched. Cause significant loss of pattern dimension uniformity, or in some cases,
As shown in FIG. 2B, adjacent resist patterns are connected with part or all of the resist bottom 9, and the chromium oxide film 3 and the chromium film 2 are not etched at all, resulting in poor resolution or poor resolution. cause.

The present invention has been made to solve the above-described problems, and in mask blanks coated with a chemically amplified resist, the occurrence of tail-like protrusions that occur at the bottom of the pattern after formation of the resist pattern, etc. An object is to provide mask blanks and masks that can be suppressed.

  In order to achieve the above object, the present invention has the following configuration.

(Configuration 1) A mask blank having a light-shielding film on a transparent substrate,
When forming a chemically amplified resist film on the light-shielding film and forming a resist pattern,
A mask blank having a film density higher than at least the film density in the vicinity of the surface of the light-shielding film and having a deactivation suppressing film for suppressing deactivation of the resist film.

(Configuration 2) The mask blank according to Configuration 1, wherein the light-shielding film is a material containing Cr.

(Configuration 3) The deactivation suppressing film is an inorganic film selected from a material containing Mo, a material containing Si, a material containing MoSi, a material containing Ta, or an organic film having a deactivation suppressing function. The mask blank according to the first or second feature.

(Configuration 4) The mask blank according to any one of Configurations 1 to 3, wherein the deactivation suppressing film has an antireflection function.

(Structure 5) The mask blank according to any one of Structures 1 to 4, wherein a chemically amplified resist film is formed on the deactivation suppression film.

(Structure 6) A mask, wherein the mask blank according to any one of Structures 1 to 5 is used, and the light-shielding film pattern is formed by patterning the light-shielding film in the mask blank.

The mask blank referred to in the present invention includes a photomask blank and a phase shift mask blank. The mask blank referred to in the present invention includes a blank with a resist film and a blank before forming a resist film. The phase shift mask blank referred to in the present invention includes a case where a light shielding film such as a chromium-based material is formed on a halftone film.
The mask referred to in the present invention includes a photomask and a phase shift mask.
The mask referred to in the present invention includes a reticle.

Hereinafter, the present invention will be described in detail.
The following mechanisms can be considered as the cause of the above problems.
As described above, the function of the chemically amplified resist (positive type) is that the acid of the catalyst substance produced in the resist film by exposure is a functional group or functional substance that controls the solubility of the polymer in the subsequent heat treatment step. The resist function is expressed by reacting with (the exposed part is dissolved in an alkali developer by removing the functional group or the like). Therefore, the concentration of the acid of the catalyst substance produced in the resist film by exposure is remarkably lowered for some reason (generally called deactivation), and is not dissolved in the alkali developer. This phenomenon occurs in the vicinity of a film to which a chemically amplified resist is applied (hereinafter simply referred to as a base film), for example, in the vicinity of a chromium-based light-shielding film (that is, at the bottom of the resist film). it is conceivable that.
The deactivation phenomenon is considered to be caused by the fact that the acid of the catalyst substance generated in the resist film by exposure moves due to diffusion into the base film (for example, a chromium-based light-shielding film). When the film density near the surface of the base film is relatively sparse or rough, it is considered that the acid of the catalyst substance generated in the resist film by exposure is likely to be captured, and the influence on tailing is large. Conceivable.
Therefore, as in the invention described in the configuration 1, an inactivation suppressing film having a film density higher than the film density in the vicinity of the surface of the light shielding film is interposed between the light shielding film and the chemically amplified resist film. By this, the deactivation of the chemically amplified resist film can be suppressed very effectively as in the examples described later,
It turned out that the mask blank which can suppress generation | occurrence | production of a skirt-like protrusion part is obtained.

In the present invention, the “light-shielding film” includes a light-shielding film that blocks exposure light, and a halftone film having a light-shielding function and a phase shift function.
The film material, film composition, film structure, film thickness, etc. of the light-shielding film are not particularly limited.
As a film material of the light-shielding film, for example, as in Configuration 2, chromium alone, a material containing at least one element composed of oxygen, nitrogen and carbon in chromium (material containing Cr), or L
Acetal resist and HEAR (Hi) for EAR (Low Energy Activation Resist)
For example, when a chemically amplified resist such as an SCAP resist is used for gh Energy Activation Resist), a film material or the like in which a skirt-like protrusion is formed on the bottom of the resist pattern can be used. In the present invention, when the film to which the chemically amplified resist is applied is a film material that becomes a surface state (a state in which the film density is sparse and there is a pore (vacancy) or a rough state) that causes tailing. Is particularly effective.
The film composition of the light-shielding film is appropriately adjusted according to optical characteristics (such as optical density and reflectance in a photomask blank, and transmittance and phase shift amount in a phase shift mask blank).
As the film structure of the light-shielding film, a single-layer or multi-layer structure made of the above film materials can be used. Further, in different compositions, a multi-layer structure formed stepwise or a film structure in which the composition is continuously changed can be used.
The film thickness of the light-shielding film is appropriately adjusted according to optical characteristics (such as optical density in the case of a photomask blank and transmittance and phase shift amount in the case of a phase shift mask blank). For example, in the case of a photomask blank, the film thickness of the light-shielding film is 300 to 1500 angstroms. In the case of the phase shift mask blank, the film thickness of the halftone film having the light-shielding function and the phase shift function is 500 to 1500 angstroms.

In the present invention, the film thickness of the deactivation suppressing film is not particularly limited as long as it can prevent or suppress deactivation. However, in order to suppress the movement of the acid of the catalyst substance produced in the resist film by exposure, it is preferable that the film thickness is not less than the film thickness that can cover the entire surface of the light-shielding film. Further, in order to pattern the light-shielding film, a film thickness of a predetermined value or less is preferable in view of the etching time. Considering these points, the preferred thickness of the deactivation suppressing film is desirably 50 to 1000 angstroms, and more desirably 100 to 500 angstroms. Further, when the deactivation suppressing film is an inorganic film, 50 to 1000 angstroms is preferable, and when the deactivation suppressing film is an organic film, 300 to 1000 angstroms is preferable.

In the present invention, the film material of the deactivation suppressing film may be organic or inorganic as long as it has a deactivation suppressing function. However, as in the configuration 3, a material containing Mo, a material containing Si, MoSi Inorganic films such as Ta-containing materials, Ta-containing materials, and bark (BARC: Bottom Anti Reflection C
oating: base antireflection film) An organic film such as neutral bark is particularly preferable. The inorganic deactivation suppressing film is preferably a film having a film density (dense) that can prevent or suppress deactivation.
A material containing Mo, a material containing Si, a material containing MoSi, a material containing Ta, or the like is a material having a higher film density than a light-shielding film material containing Cr, and thus is generated in the resist film by exposure. It is possible to suppress the movement of the acid of the catalyst substance and to prevent the occurrence of the trailing protrusions.
You may add elements, such as oxygen and nitrogen, to these materials. Further, elements such as carbon and hydrogen may be added without departing from the effects of the present invention.
Moreover, the film material of a deactivation suppression film | membrane can also be made into the material containing Ta. A material containing Ta is preferable because film stress is smaller than that of a material containing Mo, and fine crystal grains are formed, so that patterning characteristics are improved. Specific materials include Ta and T with B added to Ta.
a ₄ B, and TaBN to which nitrogen is further added. It is not limited to these materials, and elements such as oxygen, silicon, and nitrogen may be added to Ta.
The film material of the deactivation suppressing film may be an organic film material such as bark (neutral bark, acid bark), polyvinyl alcohol, SOG (spin-on-glass). As the neutral bark, a commercially available product can be used, and examples thereof include BARL manufactured by Shipley. When bark is used, the deactivation suppression effect is not achieved unless the film thickness is increased to some extent, and the deactivation suppression effect does not change even if the thickness is increased beyond a certain level.

In the present invention, as in the configuration 4, oxygen, nitrogen, or the like can be added to the deactivation suppressing film to provide an antireflection function. In this case, when manufacturing a photomask, the step of removing the deactivation suppressing film after patterning the light-shielding film can be omitted, which is preferable. Deactivation suppression films with antireflection function include MoSiO, MoSiN, MoSiON, TaS
iO, TaSiN, TaSiON, WSiO, WSiN, WSiON, ZrSiO, Zr
SiN, ZrSiON, TiSiO, TiSiN, TiSiON, etc. are mentioned.
The film thickness when the deactivation suppressing film also has an antireflection function is preferably a film thickness that can sufficiently prevent deactivation and that can sufficiently prevent reflection.

In the present invention, the photomask manufactured by using the photomask blank according to any one of the first to fifth configurations as in the sixth configuration has a jagged pattern edge due to the occurrence of a skirt-like projection, and a short-circuit connection between the projections. The resolution defect due to is hardly generated, and the processing capability and reliability of fine processing are improved.

In the present invention, the method for forming the light-shielding film and the deactivation suppressing film is not limited. For example, a sputtering method, a vacuum evaporation method, etc. are mentioned.

Example 1
On a synthetic quartz substrate having a size of 6 inches square and a thickness of 0.25 inches, a light-shielding film mainly composed of chromium having a thickness of about 600 angstroms is formed by sputtering, followed by chromium oxide having a thickness of about 300 angstroms. An anti-reflection film containing as a main component was formed, and a molybdenum silicide (MoSi ₂ ) deactivation suppression film having a thickness of about 800 Å was further formed.
Next, a commercially available chemical amplification type positive resist for electron beam exposure (FEP171: manufactured by Fuji Film Arch Co., Ltd.) is applied by a spin coating method to a thickness of about 4000 angstroms, and then heat treated at 130 ° C. for 10 minutes on a hot plate. The resist film was dried to obtain a photomask blank with a resist film.
Next, this mask blank was exposed with an electron beam exposure apparatus, and then a post-exposure baking process was performed, followed by a development process to form a resist pattern. A cross-sectional photograph of the resist pattern (measured with a SEM (scanning electron microscope)) is shown in FIG. As is clear from FIG. 4, it was confirmed that no skirt-like projections were formed on the skirt portion of the resist pattern.
Next, using the resist pattern as a mask, the exposed molybdenum silicide film is removed by dry etching using CF ₄ + O ₂ as an etching gas, followed by chromium etching which is a solution of cerium nitrate diammonium and perchloric acid. The chromium oxide film and the chromium film exposed with the liquid were removed by etching. Finally, the resist pattern is immersed in a resist stripping solution obtained by adding hydrogen peroxide to concentrated sulfuric acid, the resist pattern is removed, the molybdenum silicide film is removed by dry etching using CF ₄ + O ₂ as an etching gas, and a photomask ( Reticle).
When the protrusions (pattern edge roughness) of the chromium oxide film and the chromium film pattern in the obtained photomask were examined by SEM (scanning electron microscope), the roughness was about 10 nm or less. Further, it was confirmed that a 100 nm line & space pattern was resolved.

Comparative Example 1
A photomask blank and a photomask were produced in the same manner as in Example 1 except that the deactivation suppressing film was not formed in Example 1.
FIG. 5 shows a cross-sectional photograph (measured with a SEM (scanning electron microscope)) of the resist pattern after development. As is clear from FIG. 5, it was confirmed that a skirt-like protrusion was formed at the skirt of the resist pattern.
Further, when the chrome oxide film and the protrusion portion of the chrome film pattern (with pattern edge jaggedness) in the photomask were examined with a SEM (scanning electron microscope), it was found to have a jaggedness of about 30 nm. In addition, the 200 nm line & space pattern was only resolved.

Example 2
On a synthetic quartz substrate having a size of 6 inches square and a thickness of 0.25 inches, a light-shielding film mainly composed of chromium having a thickness of about 600 angstroms is formed by sputtering, followed by chromium oxide having a thickness of about 300 angstroms. Was formed, and a deactivation suppressing film of tantalum boron (Ta ₄ B) having a thickness of about 800 Å was formed.
Next, a commercially available chemical amplification type positive resist for electron beam exposure (FEP171: manufactured by Fuji Film Arch Co., Ltd.) is applied by a spin coating method to a thickness of about 4000 angstroms, and then heat treated at 130 ° C. for 10 minutes on a hot plate. The resist film was dried to obtain a photomask blank with a resist film.
Next, this mask blank was exposed with an electron beam exposure apparatus, and then a post-exposure baking process was performed, followed by a development process to form a resist pattern. When the cross section of the resist pattern was measured with (SEM (scanning electron microscope)), it was confirmed that no skirt-like protrusions were formed on the skirt portion of the resist pattern as in Example 1.
Next, using the resist pattern as a mask, the tantalum boron film exposed by dry etching using Cl ₂ as an etching gas is removed, and subsequently, the oxidation exposed by dry etching using Cl ₂ + O ₂ as an etching gas. The chromium film and the chromium film were removed by etching. Finally, the resist pattern is immersed in a resist stripping solution obtained by adding hydrogen peroxide to concentrated sulfuric acid, the resist pattern is removed, the tantalum boron film is removed by dry etching using Cl ₂ gas as an etching gas, and a photomask (reticle) is obtained. )
When the protrusions (pattern edge roughness) of the chromium oxide film and the chromium film pattern in the obtained photomask were examined by SEM (scanning electron microscope), the roughness was about 10 nm or less. Further, it was confirmed that a 100 nm line & space pattern was resolved.

Examples 3-4
Photomask blanks and photomasks were prepared in the same manner as in Example 2, except that a tantalum boron nitride film (Example 3) and a tantalum film (Example 4) were used instead of tantalum boron (Ta ₄ B) in Example 2 above. A mask was prepared.
It was confirmed that no skirt-like projections were formed on the bottom of the resist pattern after development.
Further, the protrusion portion of the chromium oxide film and the chromium film pattern in the obtained photomask (
When the edge of the pattern edge is checked with a scanning electron microscope (SEM), it is about 10 nm.
It was less than a degree of jaggedness. Further, it was confirmed that a 100 nm line & space pattern was resolved.

Example 5
On a synthetic quartz substrate having a size of 6 inches square and a thickness of 0.25 inches, a light shielding film mainly composed of chromium having a thickness of about 600 angstroms is formed by sputtering, followed by an antireflection film and a deactivation suppressing film. As a result, a molybdenum silicide oxynitride film (MoSiON) having a thickness of about 500 Å was formed.
Next, a commercially available chemical amplification type positive resist for electron beam exposure (FEP171: manufactured by Fuji Film Arch Co., Ltd.) is applied by a spin coating method to a thickness of about 4000 angstroms, and then heat treated at 130 ° C. for 10 minutes on a hot plate. The resist film was dried to obtain a photomask blank with a resist film.
Next, this mask blank was exposed with an electron beam exposure apparatus, and thereafter a post-exposure baking process was performed, followed by a development process to form a resist pattern. The cross section of the register pattern is S
When confirmed by EM (scanning electron microscope), it was confirmed that no skirt-like projections were formed on the skirt of the resist pattern.
Next, using the resist pattern as a mask, the exposed molybdenum silicide oxide film is removed by dry etching using CF ₄ + O ₂ as an etching gas. Subsequently, chromium which is a solution of cerium nitrate diammonium and perchloric acid is used. The chromium film exposed with the etching solution was removed by etching. Finally, the resist pattern was immersed in a resist stripping solution obtained by adding hydrogen peroxide to concentrated sulfuric acid, and the resist pattern was removed to obtain a photomask (reticle).
When the protrusion portion (pattern edge roughness) of the molybdenum silicide oxide film and the chromium film pattern in the obtained photomask was examined by SEM (scanning electron microscope), the roughness was about 10 nm or less. Further, it was confirmed that a 100 nm line & space pattern was resolved.

Example 6
A halftone film mainly composed of chromium oxide having a thickness of about 1300 angstroms is formed on a synthetic quartz substrate having a size of 6 inches square and a thickness of 0.25 inches by a sputtering method, and subsequently thickened as a deactivation suppressing film. A molybdenum silicide film (MoSi ₂ ) having a thickness of about 800 Å was formed.
Next, a commercially available chemical amplification type positive resist for electron beam exposure (FEP171: manufactured by Fuji Film Arch Co., Ltd.) is applied by a spin coating method to a thickness of about 4000 angstroms, and then heat treated at 130 ° C. for 10 minutes on a hot plate. The resist film was dried to obtain a photomask blank with a resist film.
Next, this mask blank was exposed with an electron beam exposure apparatus, and then a post-exposure baking process was performed, followed by a development process to form a resist pattern. When the cross section of the resist pattern was confirmed by SEM (scanning electron microscope), it was confirmed that no skirt-like projections were formed on the skirt portion of the resist pattern.
Next, using the resist pattern as a mask, the exposed molybdenum silicide film is removed by dry etching using CF ₄ + O ₂ as an etching gas, followed by chromium etching which is a solution of cerium nitrate diammonium and perchloric acid. The chromium oxide film exposed with the solution was removed by etching. Finally, the resist pattern is immersed in a resist stripping solution obtained by adding hydrogen peroxide to concentrated sulfuric acid to remove the resist pattern, and the molybdenum silicide film is removed by dry etching using CF ₄ + O ₂ as an etching gas to remove the photomask ( Reticle).
When the protrusion portion (pattern edge roughness) of the obtained photomask was examined by SEM (scanning electron microscope), the roughness was about 10 nm or less. Further, it was confirmed that a 100 nm line & space pattern was resolved.

Example 7
A molybdenum silicide nitride film having a thickness of about 900 angstroms is formed as a halftone film on a synthetic quartz substrate having a size of 6 inches square and a thickness of 0.25 inches by sputtering. Subsequently, a thickness of about 1000 angstroms is formed as a light shielding film. Forming a chromium film of
Subsequently, a tantalum film having a thickness of about 800 Å was formed as a deactivation suppressing film.
Next, a commercially available chemical amplification type positive resist for electron beam exposure (FEP171: manufactured by Fuji Film Arch Co., Ltd.) is applied by a spin coating method to a thickness of about 4000 angstroms, and then heat treated at 130 ° C. for 10 minutes on a hot plate. The resist film was dried to obtain a photomask blank with a resist film.
Next, this mask blank was exposed with an electron beam exposure apparatus, and then a post-exposure baking process was performed, followed by a development process to form a resist pattern. When the cross section of the resist pattern was confirmed by SEM (scanning electron microscope), it was confirmed that no skirt-like projections were formed on the skirt portion of the resist pattern.
Next, using the resist pattern as a mask, the tantalum film that is a deactivation suppressing film exposed by dry etching using Cl ₂ as an etching gas is removed, and subsequently, dry etching using CF ₄ + O ₂ as an etching gas. The exposed chromium film, which is a light shielding film, was removed by etching, and then the molybdenum silicide nitride film, which was a halftone film, was removed by dry etching using CF ₄ + O ₂ as an etching gas. Finally, the resist pattern is immersed in a resist stripping solution containing concentrated sulfuric acid and hydrogen peroxide solution to remove the resist pattern, and the tantalum film is removed by dry etching using Cl ₂ gas as an etching gas to form a photomask (reticle). Got.
When the protrusions of the chromium film and molybdenum silicide nitride film pattern (with pattern edge roughness) in the obtained photomask were examined with SEM (scanning electron microscope), the roughness was about 10 nm or less. Further, it was confirmed that a 100 nm line & space pattern was resolved.

In addition, this invention is not limited to the Example etc. which were mentioned above.
For example, in the case where the deactivation suppressing film of the present invention is not formed, if the film generates a trailing protrusion at the bottom of the chemically amplified resist pattern, the film of the present invention is interposed between the film and the chemically amplified resist. A deactivation suppression film can be applied (formed).
The type of chemically amplified resist is not limited, and other chemically amplified resists (for example, O
Even when EBR-CAP209 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used, the same effect as in the above-described example was observed. The chemically amplified resist may be a negative type.
Moreover, the same effect as the Example mentioned above was recognized also when neutral organic bark (for example, BARL made by Shipley Co., Ltd.) was used as the deactivation suppression film.
As the deactivation suppressing film, a material containing W, a material containing Zr, or a material containing Ti may be used as long as it has a film density higher than at least the film density in the vicinity of the surface of the light-shielding film.
In addition, the light shielding film, the antireflection film, the halftone film, the deactivation suppressing film, etc. are wet etching,
Alternatively, it can be etched by either dry etching.

(Effect of the invention)
As described above, according to the present invention, the deactivation suppression film is formed on the light shielding film in the photomask blank or the halftone film in the phase shift mask blank, thereby forming the deactivation suppression film. Inactivation of the chemically amplified resist film can be suppressed, and the occurrence of tail-like protrusions at the bottom of the resist pattern can be suppressed.

It is typical sectional drawing for demonstrating the manufacturing process of a mask blank and a mask. It is a schematic diagram for demonstrating the skirt-like projection part etc. in the resist pattern bottom part. 6 is a cross-sectional photograph of a register pattern in Example 1. FIG. 6 is a cross-sectional photograph of a register pattern in Comparative Example 1. FIG.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Chromium film 3 Chromium oxide film 4 Chemical amplification type resist film 4a Resist pattern 5 Mask blank 6 Photomask 7 Footing-like protrusion 8 Exposed part which should be originally removed by development processing 9 Resist bottom

Claims (7)

A mask blank,
A base film made of a material containing chromium, formed on a transparent substrate;
A deactivation suppression film formed on the base film and suppressing deactivation of the chemically amplified resist film,
The deactivation suppressing film suppresses deactivation of the chemically amplified resist film caused by the movement of the acid of the catalyst substance generated in the chemically amplified resist film by exposure to the base film by diffusion. A film having a density obtained, and having a density higher than at least a density in the vicinity of the surface of the base film,
The mask blank, wherein the deactivation suppression film is neutral bark or polyvinyl alcohol .   2. The mask blank according to claim 1, wherein the material containing chromium is a material containing at least one element composed of oxygen, nitrogen, and carbon in chromium.   The mask blank according to claim 1, wherein a chemically amplified resist film for electron beam exposure is formed on the deactivation suppressing film.   A method for producing a mask, comprising: using the mask blank according to claim 3 and exposing the chemically amplified resist film for electron beam exposure to an electron beam acceleration voltage of 50 keV or more to form a resist pattern. . Removing the deactivation suppression film exposed by dry etching using the resist pattern as a mask;
Subsequently, the base film exposed by dry etching is removed,
The method for manufacturing a mask according to claim 4, wherein a photomask is obtained by removing the resist pattern and the deactivation suppressing film.   6. The method of manufacturing a mask according to claim 5, wherein the base film is removed by dry etching using Cl2 + O2 as an etching gas.   A mask manufactured by the mask manufacturing method according to claim 4.

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