JP2008070881A - Method for manufacturing mask blank and method for manufacturing mask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a mask blank and a mask, wherein the linearity is suppressed to 10 nm or less by suppressing a difference (real dimensional difference) between a design dimension of a line width of a transfer pattern on a transfer mask and a dimension of a line width of a transfer pattern formed on a substrate. <P>SOLUTION: In the method for manufacturing a mask blank, a thin film for forming a mask pattern is formed on a substrate 12 and a chemically amplified resist film is formed above the thin film, wherein the total amount of organic acids present on the face of the thin film where the resist film is formed is controlled to 1 μg/cm<SP>2</SP>or less, and then the resist film is formed on the face. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mask blank manufacturing method and a mask manufacturing method used in the manufacture of semiconductor devices, display devices (display panels) and the like.

  For example, photomasks (reticles) used in semiconductor device microfabrication technologies exhibit transfer functions (light shielding, phase control, transmittance control, reflectance control, etc.) as mask patterns formed on a transparent substrate. It is manufactured by patterning a thin film (hereinafter referred to as a thin film for forming a mask pattern), for example, a light-shielding film, which is mainly formed. The light-shielding film is patterned by, for example, dry etching using a resist pattern as a mask. The resist pattern is formed by, for example, an electron beam lithography method.

In recent years, in the mask manufacturing field, it has been studied to increase the acceleration voltage of an electron beam used in an electron beam lithography method 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. For example, at an acceleration voltage of 10 to 20 keV The electron beam resist that has been used lacks the sensitivity of the resist, resulting in decreased throughput. Therefore, in the mask manufacturing field, it has become necessary to use a chemically amplified resist film as used in the fine processing technology of semiconductor wafers. The chemically amplified resist film has high sensitivity and high resolution with respect to a high acceleration voltage (see, for example, Patent Document 1).
In a chemically amplified resist, for example, an acid is generated in the chemically amplified resist film by electron beam exposure, and the acid-sensitive substance reacts with this acid as a catalyst to change the solubility of the polymer. A resist is obtained.
JP 2003-107675 A

By the way, when a chemically amplified resist film is used in the field of mask manufacturing, a film (a film corresponding to the resist with respect to the resist) on which the chemically amplified resist is directly formed by coating, for example, a chromium-based light shielding property When the film density near the surface of a thin film for forming a mask pattern such as a film is relatively sparse or rough (that is, not smooth), it is generated in a chemically amplified resist film by electron beam exposure. The acid of the catalyst material to be moved is easily moved into the thin film for forming a mask pattern corresponding to the base of the resist (especially in the surface layer), and in the thin film for forming the mask pattern (especially in the thin film). In the surface layer), the movement of the acid is promoted by supplementing the acid, so that the acid concentration at the bottom of the resist film is significantly reduced (commonly called deactivation). Fruit, in the foot portion of the resist pattern, in a chemically amplified positive resist film "footing" bad shape such as "Erosion" occurs in the negative. Conventionally, in order to solve the problem of remarkably poor shape of the resist pattern due to deactivation, an acid in the chemically amplified resist film is formed between the thin film for forming the mask pattern and the chemically amplified resist film. There is known a configuration in which a deactivation suppressing film having a density capable of preventing migration into a thin film (particularly in the surface layer) for forming a thin film is provided (for example, see Patent Document 1). The deactivation suppression film described in Patent Document 1 has a smoother surface than the thin film for forming the mask pattern having a relatively sparse or rough surface, and “bottoming”. As a result, it is considered to have a surface state that does not cause erosion. Patent Document 1
A structure in which a silicide-based material such as a material containing Si or a material containing metal silicide, an inorganic film such as a material containing Mo or a material containing Ta, or an organic film such as an organic bark is introduced as a deactivation suppressing film. Is disclosed.

  However, when the deactivation suppression film described in Patent Document 1 is applied to a mask blank used for photolithography with a DRAM half pitch (hp) of 65 nm or less in the semiconductor design rule, it has been found that there are the following problems. did.

Usually, photolithography when microfabricating a semiconductor substrate is performed by reduced projection exposure, so the pattern size formed on the transfer mask is about four times larger than the pattern size formed on the semiconductor substrate. Yes. However, in the photolithography according to the above semiconductor design rule (DRAM hp 65 nm or less), the size of the circuit pattern transferred onto the semiconductor substrate is considerably smaller than the wavelength of the exposure light. When reduced projection exposure is performed using a transfer mask on which a transfer pattern enlarged about twice is used, the shape according to the transfer pattern can be transferred to the resist film on the semiconductor substrate due to the influence of exposure light interference, etc. Disappear.
Therefore, by performing optical proximity effect correction (OPC) as a super-resolution mask, an OPC mask to which an optical proximity effect correction technique that deteriorates transfer characteristics is applied, or the center of a light shielding pattern such as a line shape. A phase shift mask (enhancer mask) or the like that enhances the light-shielding property of the mask pattern and improves the resolution of the line pattern by using a structure (mask enhancer) provided with a phase shifter in the part is used. For example, it is necessary to form an OPC pattern (for example, an assist bar or a hammer head having a line width of less than 100 nm) having a size equal to or smaller than a half of the circuit pattern on the OPC mask. Further, a light-shielding pattern in the enhancer mask and a line width of the phase shifter are required to have a very narrow line width.
The enhancer mask can be adjusted by adjusting the pattern width and the phase shifter width so that the intensity of the light that travels from the periphery of the light shielding pattern to the back side of the light shielding pattern and the intensity of the light that passes through the phase shifter are just balanced. The amplitude intensity of the transmitted light has a distribution that becomes 0 at a position corresponding to the center of the mask enhancer, and the intensity of the light transmitted through the mask enhancer (the square of the amplitude intensity) also corresponds to the center of the mask enhancer. It is a mask having a distribution such that the position is zero.
However, when the deactivation suppressing film described in Patent Document 1 is used as a mask blank for producing a transfer mask of the semiconductor design rule (DRAM hp65 nm or less), as a chemically amplified resist pattern on a thin film for patterning Although the line and space pattern of 100 nm is resolved, the difference between the design dimension and the dimension of the transfer pattern actually formed on the substrate (actual dimension difference) increases, and the above semiconductor design rule (DRAM hp 65 nm or less) In other words, the linearity required by the customer cannot meet the requirement of 10 nm or less.
Therefore, the present invention has been made to solve the above problems, and the difference (actual size difference) between the design dimension of the transfer pattern line width of the transfer mask and the transfer pattern line width dimension formed on the substrate. An object of the present invention is to provide a mask blank manufacturing method and a mask manufacturing method that can suppress the linearity to 10 nm or less.

The inventor of the present application diligently studied the cause of an increase in the actual size difference of the transfer pattern formed on the substrate.
As a result, an ion chromatographic analysis was performed on the substrate on which the deactivation suppressing film described in Patent Document 1 was formed on a thin film (not including the deactivation suppressing film) for forming the mask pattern. The existence became clear. And this contaminant is hardly detected by the ion chromatographic analysis result of the quartz substrate alone or the quartz substrate / deactivation suppression film alone substrate (therefore, the contaminant is not caused by the deactivation suppression film or the substrate). It is understood that a relatively large number of ions are detected in the result of ion chromatography analysis of the substrate of the thin film alone for forming the substrate / mask pattern, so that the thin film for forming the mask pattern passes through the deactivation suppression film. It became clear that it was a pollutant that appeared (contaminated ions, etc.).
These contaminants (contaminated ions, etc.) enter the chemically amplified resist film from the thin film for forming the mask pattern through the deactivation suppression film, and deteriorate the function (main reaction) of the chemically amplified resist. As a result, it has been found that it becomes an impediment to improving linearity and further improving the resolution of chemically amplified resists. In this case, the function (main reaction) of the chemically amplified resist may be reduced, for example, by reducing the function as an acid (for example, decreasing the catalytic action (reactivity) of the acid or eliminating the catalytic action due to neutralization of the acid). ) And other reactivity reductions. At this time, there is no decrease in the acid concentration itself in the chemically amplified resist, so the concept is different from deactivation due to a decrease in acid concentration.
Then, contaminants that enter the chemically amplified resist film from the thin film for forming the mask pattern and reduce the function (main reaction) of the chemically amplified resist are removed from the thin film for forming the mask pattern by the chemically amplified resist. The chemical amplification type formed on the mask blank is provided on the bottom (bottom surface) of the chemically amplified resist film with a film (film capable of preventing the entry of contaminants) capable of blocking (insulating) entry into the film. The present inventors have found that it is necessary to further improve the resolution of a resist and a transfer pattern formed using the resist pattern as a mask and to improve the pattern accuracy.

  According to the present invention, a pattern is drawn to form a chemically amplified resist pattern, and a mask blank capable of suppressing the linearity of the transfer pattern formed on the substrate using the resist pattern as a mask to 10 nm or less, and A mask can be provided.

The present invention has the following configuration.
(Structure 1) A mask blank manufacturing method in which a thin film for forming a mask pattern is formed on a substrate, and a chemically amplified resist film is formed above the thin film,
A method for manufacturing a mask blank, characterized in that a total amount of organic acids present on a surface on a thin film on which the resist film is formed is 1 μg / cm ² or less, and the resist film is formed on the surface.
(Configuration 2) A mask blank manufacturing method in which a thin film for forming a mask pattern is formed on a substrate, and a chemically amplified resist film is formed above the thin film,
A mask blank manufacturing method comprising: forming a clean surface above the thin film so that a substance that inhibits a chemical amplification function does not inhibit formation of a resist pattern; and forming the resist film on the surface .
(Structure 3) A method of manufacturing a mask blank according to Structure 1 or 2, wherein the thin film is a metal film.
(Structure 4) The method of manufacturing a mask blank according to any one of structures 1 to 3, wherein the thin film is a film formed by a reactive sputtering method.
(Structure 5) A method of manufacturing a mask blank according to any one of Structures 1 to 4, wherein the thin film is coated with a resin film having a predetermined film density.
(Structure 6) The mask blank manufacturing method according to any one of structures 1 to 5, wherein the mask blank is a mask blank before forming the chemically amplified resist film.
(Structure 7) A mask manufacturing method comprising patterning the thin film in a mask blank manufactured by the manufacturing method according to any one of Structures 1 to 6 to form a transfer pattern on a substrate.

Hereinafter, the present invention will be described in detail.
The mask blank manufacturing method of the present invention is a mask blank manufacturing method in which a thin film for forming a mask pattern is formed on a substrate, and a chemically amplified resist film is formed above the thin film,
The total amount of organic acids present on the surface on the thin film on which the resist film is formed is 1 μg / cm ² or less, and the resist film is formed on this surface (Configuration 1).
In the invention according to Configuration 1, the total amount of organic acids present on the surface on the thin film on which the chemically amplified resist film is formed is 1 μg / cm ² or less, and the chemically amplified resist film is formed on this surface. Therefore, a substance (organic acid) that inhibits the function of the chemically amplified resist can be prevented from entering the resist film from the bottom of the resist film, and the chemically amplified resist and the transfer formed using the resist pattern as a mask. This contributes to further improvement of pattern resolution and improvement of pattern accuracy.
Examples of the organic acid include acetic acid, formic acid, benzoic acid, malic acid, tartaric acid, and oxalic acid. Preferably, the total amount of organic acid is 0.5 μg / cm ² or less. The amount of the organic acid was determined by ion chromatography analysis. A Teflon (registered trademark) ring (120 mmφ) was placed on the surface on which the chemically amplified resist film was formed, and 15 mL of ultrapure water was placed inside. It was set as the amount of organic acid components extracted by standing for a minute (a semi-quantitative value of the extraction amount (μg / cm ² ) per 1 cm ^{2 of the} sample).

The mask blank manufacturing method of the present invention is a mask blank manufacturing method in which a thin film for forming a mask pattern is formed on a substrate, and a chemically amplified resist film is formed on the thin film. And
A clean surface is formed above the thin film so that a substance that inhibits the chemical amplification function does not inhibit the formation of a resist pattern, and the resist film is formed on this surface (Configuration 2).
In the invention according to Configuration 2, a clean surface is formed so that a substance that inhibits the chemical amplification function does not inhibit the formation of the resist pattern, and a chemically amplified resist film is formed on this surface. It is possible to prevent substances that inhibit the function (such as organic acids) from entering the resist film from the bottom of the resist film, and the resolution of the chemically amplified resist and the transfer pattern formed using the resist pattern as a mask. It contributes to further improvement and can contribute to improvement of pattern accuracy.
Examples of the substance that inhibits the function of the chemically amplified resist include organic acids and amines. Examples of the organic acid include acetic acid, formic acid, benzoic acid, malic acid, tartaric acid, and oxalic acid. Examples of the amines include methylamine, dimethylamine, trimethylamine, and tetramethylammonium. The total amount of substances that inhibit the function of these chemically amplified resists is preferably 1 μg / cm ² or less, more preferably 0.5 μg / cm ² or less. A substance that inhibits the function of the chemically amplified resist can be determined by the same ion chromatography analysis as described above.

In the present invention, the mask blank includes a photomask blank, a phase shift mask blank, a reflective mask blank, and an imprint transfer plate substrate. The mask blank includes a mask blank with a resist film and a mask blank (configuration 6) before forming the resist film. The mask blank before forming the resist film includes a mask blank in which a thin film for forming the mask pattern is covered with a resin film having a predetermined film density. The phase shift mask blank includes a case where a light-shielding film such as a chromium-based material is formed on the halftone film. In this case, the thin film for forming the mask pattern indicates a halftone film or a light shielding film. In the case of a reflective mask blank, a structure in which an absorber film of a tantalum material or a chromium material to be a transfer pattern is formed on a multilayer reflective film or a buffer layer provided on the multilayer reflective film, The imprint transfer plate includes a structure in which a transfer pattern forming thin film such as a chromium-based material is formed on a base material to be a transfer plate. The mask includes a photomask, a phase shift mask, a reflective mask, and an imprint transfer plate. The mask includes a reticle.

  In the present invention, as a thin film for forming a mask pattern, a light-shielding film that blocks exposure light, a semi-transparent film that adjusts and controls the amount of transmission of exposure light, and the reflectance of exposure light are adjusted. Examples include a reflectance control film (including an antireflection film) to be controlled, a phase shift film that changes a phase with respect to exposure light and the like, a halftone film having a light shielding function and a phase shift function, and the like.

  The mask blank manufacturing method of the present invention is particularly effective when the thin film for forming a mask pattern is a metal film (Configuration 3). Examples of the metal film include chromium, tantalum, molybdenum, titanium, hafnium, tungsten, an alloy containing these elements, or a film made of a material containing the above elements or the above alloys.

  The mask blank manufacturing method of the present invention is characterized in that the mask pattern forming thin film is a film formed by a reactive sputtering method (Configuration 4). Examples of the reactive gas used during sputtering include oxygen gas, nitrogen gas, nitric oxide gas, carbon dioxide gas, hydrocarbon gas, or a mixed gas thereof. Since the surface of the thin film for patterning formed by the reactive sputtering method is generally likely to be supplemented with a substance that hinders the function of the chemically amplified resist (for example, the surface becomes rough), the above problem is particularly serious. Since it is easy to become a problem, it is particularly effective to combine the present invention with a patterning thin film formed by a reactive sputtering method.

As a thin film for forming the mask pattern according to Configuration 4, it is preferable to use a thin film with an increased dry etching rate in terms of miniaturization of the transfer pattern and improvement in pattern accuracy. Specifically, when the metal is chromium, an additive element that increases the dry etching rate is added. Examples of the additive element that increases the dry etching rate include oxygen and / or nitrogen.
When oxygen is contained in the thin film containing chromium, the content of oxygen is preferably in the range of 5 to 80 atomic%. When the oxygen content is less than 5 atomic%, it is difficult to obtain the effect of increasing the dry etching rate. On the other hand, when the oxygen content exceeds 80 atomic%, the absorption coefficient of, for example, ArF excimer laser (wavelength 193 nm) of the exposure light wavelength (200 nm or less) applied at a DRAM half pitch of 65 nm or less in the semiconductor design rule is Therefore, it is necessary to increase the film thickness in order to obtain a desired optical density, which is not preferable because the pattern accuracy cannot be improved.
Moreover, the range of 20-80 atomic% is suitable for content of nitrogen when nitrogen is contained in the thin film containing chromium. If the nitrogen content is less than 20 atomic%, it is difficult to obtain the effect of increasing the dry etching rate. On the other hand, if the nitrogen content exceeds 80 atomic%, the absorption coefficient at, for example, ArF excimer laser (wavelength 193 nm) of the wavelength of exposure light (200 nm or less) applied at a DRAM half pitch of 65 nm or less in the semiconductor design rule is Therefore, it is necessary to increase the film thickness in order to obtain a desired optical density, which is not preferable because the pattern accuracy cannot be improved.
Further, the thin film containing chromium may contain both oxygen and nitrogen. The content in that case is preferably such that the sum of oxygen and nitrogen is in the range of 10 to 80 atomic%. In addition, the content ratio of oxygen and nitrogen when the thin film containing chromium contains both oxygen and nitrogen is not particularly limited, and is appropriately determined depending on the absorption coefficient and the like.
In addition, the chromium thin film containing oxygen and / or nitrogen may contain other elements such as carbon, hydrogen, and helium.
From the viewpoint of reducing the amount of oxygen in the dry etching gas, it is possible to use a dry etching gas that does not contain oxygen.

The chromium-based thin film is preferably etched (patterned) by dry etching from the viewpoint of improving the pattern accuracy of the chromium-based thin film.
For dry etching of the chromium-based thin film, it is preferable to use a chlorine-based gas or a dry etching gas composed of a mixed gas containing a chlorine-based gas and an oxygen gas. The reason for this is that for a chromium-based thin film made of a material containing chromium and an element such as oxygen and nitrogen, the dry etching rate can be increased by performing dry etching using the above dry etching gas, This is because the dry etching time can be shortened and a light-shielding film pattern having a good cross-sectional shape can be formed. Examples of the chlorine-based gas used for the dry etching gas include Cl ₂ , SiCl ₄ , HCl, CCl ₄ , and CHCl ₃ .

The mask blank of the present invention is particularly useful when the chemically amplified resist film is subjected to pattern exposure (drawing) with an electron beam accelerated by an acceleration voltage of 50 keV or more to form a resist pattern.
This is because the present invention is intended to further improve the resolution of the chemically amplified resist pattern formed on the mask blank when 50 keV compliant EB lithography is applied.
In the chemically amplified resist film of the present invention, for example, an acid of a catalyst substance generated in the resist film by exposure reacts with a functional group or a functional substance that controls the solubility of the polymer in the subsequent heat treatment step. Thus, a resist film that exhibits a resist function is included. Here, the expression of the resist function means that the resist function is dissolved in an alkali by removing a functional group or the like.

The mask blank manufacturing method of the present invention is characterized in that a thin film for forming the mask pattern is covered with a resin film having a predetermined film density (Configuration 5). The film density of the resin film is 1.4 g / cm ³ or more, more preferably 1.6 g / cm ³ or more. The film density is a film density determined by an X-ray reflectivity method (Grazing Incidence X-ray Reflective technique (GXIR)). By setting the film density, for example, even if a substance that inhibits the chemical amplification function exists on the surface of the thin film, the chemical that prevents the chemical amplification function does not inhibit the formation of the resist pattern. The surface on which the amplification resist is formed can be a clean surface, and even if a substance that inhibits the chemical amplification function exists on the surface of the thin film, the function of the chemical amplification resist can be improved. Since the inhibiting substance can be effectively prevented from entering the chemically amplified resist from the bottom of the resist film, the resolution of the chemically amplified resist and the transfer pattern formed using the resist pattern as a mask can be improved. Can contribute to the improvement of the pattern accuracy.
The film thickness of the resin film is preferably 2 nm or more and 20 nm or less, more preferably 5 nm or more and 20 nm or less. Thereby, the further improvement of the resolution of the chemically amplified resist formed on the mask blank and the transfer pattern formed using the resist pattern as a mask can be surely realized. Specifically, it is possible to reliably realize a mask blank that can satisfy the pattern accuracy required for a fine pattern forming mask having a DRAM half pitch of 65 nm or less according to the semiconductor design rule.
The mask blank of the present invention is particularly effective when it is used for forming a resist pattern having a line width of less than 100 nm on the mask blank. Examples of such a mask blank include an OPC mask and a mask having an enhancer structure (enhancer mask). In these masks (OPC masks and enhancer masks), the width of the auxiliary pattern provided around the present pattern is the narrowest for the purpose of improving the resolution of the present pattern. Useful.

The mask of the present invention is characterized in that a transfer pattern formed by patterning the thin film in the mask blank according to the present invention is formed on a substrate (Configuration 7).
The mask of the present invention can satisfy the pattern accuracy required for the corresponding mask at a DRAM half pitch of 65 nm or less in the semiconductor design rule.

  In the present invention, examples of the substrate include a synthetic quartz substrate, a soda lime glass substrate, an alkali-free glass substrate, and a low thermal expansion glass substrate.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an example of a mask blank 10 according to the first embodiment of the present invention. In this example, the mask blank 10 is a mask blank for a binary mask, and includes a transparent substrate 12, a light shielding film 13 (a laminated film of a light shielding layer 14 and an antireflection film 16), a resin film 18, and a chemical amplification type. A resist film 20 is provided.

The transparent substrate 12 is made of a material such as a synthetic quartz substrate or soda lime glass. The light shielding film 13 is a laminated film of a light shielding layer 14 and an antireflection layer 16.
The light shielding layer 14 has, for example, a chromium nitride film 22 and a chromium carbonitride film 24 in this order on the transparent substrate 12. The chromium nitride film 22 is a layer mainly composed of chromium nitride (CrN), and has a film thickness of, for example, 10 to 20 nm. The chromium carbonitride film 24 is a layer mainly composed of chromium carbonitride (CrCN), and has a film thickness of, for example, 25 to 60 nm.
The antireflection layer 16 is, for example, a film containing chromium and oxygen and nitrogen (CrON film), and is formed on the chromium carbonitride film 24. The film thickness of the antireflection layer 16 is, for example, 15 to 30 nm.
These light shielding layer 14 and antireflection layer 16 use chromium as a sputtering target, and are in a reactive gas (for example, oxygen gas, nitrogen gas, nitric oxide gas, carbon dioxide gas, hydrocarbon gas, or a mixed gas thereof). The film can be formed by the reactive sputtering method in FIG.
As described above, the light-shielding film 13 is composed of the material of the chromium nitride film 22, the chromium carbonitride nitride film 24, and the chromium oxynitride film from the transparent substrate 12 side. By including at least one element of chromium and oxygen and nitrogen in each layer, or by including mainly a large amount of nitrogen in each layer, the dry etching rate during dry etching using a chlorine-based gas can be increased.
Examples of the material of the light-shielding film 13 include chromium alone, chromium containing at least one element composed of oxygen, nitrogen, carbon, and hydrogen (a material containing Cr). The film structure of the light-shielding film 13 can be a single layer or a multi-layer structure made of the above film material. Further, in different compositions, a multi-layer structure formed in stages or a film structure in which the composition is continuously changed can be obtained.

  The resin film 18 is a layer for making the surface on which the chemically amplified resist is formed a clean surface so that a substance that inhibits the chemical amplification function does not inhibit the formation of the resist pattern, and the surface of the light shielding film. Even when a substance that inhibits the chemical amplification function is present in the substrate, it is effective that the substance that inhibits the function of the chemical amplification resist enters the chemical amplification resist from the bottom of the resist film. It is a blocking layer and is formed on the light-shielding film 13 with the antireflection layer 16 interposed therebetween.

The resin film 18 is resistant to a developer used when forming a resist pattern on the chemically amplified resist film 20, and has an etching rate with respect to an etchant used when etching the resin film. Further, it is preferable that etching is possible with an etchant used for etching the light-shielding film 13 using the resist pattern as a mask, and the etching rate is high.
The resin film 18 may be an acrylic resin, a novolac resin, or the like. The resin film 18 may have a predetermined film density (specifically, 1.4 g / cm ³ or more) by appropriately adjusting molecular weight, viscosity, and baking conditions in order to maximize the above functions. preferable.

  In the modification of the present embodiment, the mask blank 10 may be a mask blank for a phase shift mask. In this case, the mask blank 10 further includes a phase shift film, for example, between the transparent substrate 12 and the light shielding film 13. As the phase shift film, for example, various known chromium-based (CrO, CrF, etc.), molybdenum-based (MoSiON, MoSiN, MoSiO, etc.), tungsten-based (WSiON, WSiN, WSiO, etc.), and silicon-based (SiN, SiON, etc.). The halftone film can be used. The mask blank 10 for the phase shift mask may include a phase shift film on the light shielding film 13.

Examples of the present invention and comparative examples are shown below.
(Example 1)
(Preparation of substrate sample)
A synthetic quartz substrate having a size of 6 inches square and a thickness of 0.25 inches is used as the transparent substrate 12, and a chromium nitride film 22, a chromium carbonitride film 24, a chromium oxynitride film ( Each of the antireflection layers 16) was continuously formed by a sputtering method (FIG. 1). The light-shielding film 13 includes nitrogen in almost the entire region in the film thickness direction, and mainly includes a large amount of nitrogen in each layer, thereby increasing the dry etching rate with respect to the chlorine-based gas. The film thickness of the light shielding film 13 was 68 nm.
Next, a resin film 18 made of a novolak resin was formed on the light-shielding film 13 by spin coating, and then heat-treated at 150 ° C. for 10 minutes to form a film having a thickness of 15 nm (FIG. 1).
As described above, a substrate sample according to Example 1 was obtained.

(Comparative example)
(Preparation of substrate sample)
A synthetic quartz substrate having a size of 6 inches square and a thickness of 0.25 inches is used as the transparent substrate 12, and a chromium nitride film 22, a chromium carbonitride film 24, a chromium oxynitride film ( Each of the antireflection layers 16) was continuously formed by a sputtering method (FIG. 1). The light-shielding film 13 includes nitrogen in almost the entire region in the film thickness direction, and mainly includes a large amount of nitrogen in each layer, thereby increasing the dry etching rate with respect to the chlorine-based gas. The film thickness of the light shielding film 13 was 68 nm.
As described above, a substrate sample according to a comparative example was obtained.

(Ion chromatographic analysis)
Ion chromatographic analysis was performed on the substrate samples in Example 1 and Comparative Example.
Specifically, an organic acid component and an amine component were calculated using an ion chromatograph analyzer (Dionex: DX-500) under the following measurement conditions.
A Teflon (registered trademark) ring (120 mmφ) is placed on the surface of the substrate sample before the chemically amplified resist film 20 is formed, and 15 mL of ultrapure water is placed inside, and the amount of components extracted by standing for 5 minutes (sample 1 cm) The extraction amount from ² (semi-quantitative value of μg / cm ² ) In the measurement of the organic acid component, 6 mM sodium hydrogen carbonate was used as an eluent, 2 mmφ × 250 mm, Ion Pac AS14 was used as a separation column, and the column temperature was measured at 35 ° C.
As a result, the presence of an organic acid (formic acid, benzoic acid) was clarified in the substrate sample according to the comparative example, and the total amount of the organic acid was 3 μg / cm ² .
On the other hand, in the substrate sample according to Example 1, the presence of organic acid (acetic acid, formic acid, benzoic acid, malic acid, tartaric acid, oxalic acid) was less than the detection limit, and the presence of organic acid could not be confirmed. .

(Preparation of mask blank with resist film)
Next, a chemical amplification type positive resist for electron beam drawing (FEP171: manufactured by Fuji Film Electronics Materials Co., Ltd.) is applied as a chemical amplification type resist film 20 to the substrate samples of Example 1 and Comparative Example by spin coating. A thickness of 300 nm was applied, and then heat-treated at 130 ° C. for 10 minutes on a hot plate to dry the chemically amplified resist film 20 to obtain a mask blank 10 that is a photomask blank with a resist film for ArF excimer laser exposure. .
(Formation of resist pattern)
For the mask blanks according to Example 1 and the comparative example, a chemically amplified resist pattern was formed in order to compare the difference in resolution of the chemically amplified resist pattern. Specifically, each mask blank is subjected to pattern exposure (drawing) with an electron beam accelerated at an acceleration voltage of 50 keV or higher using an electron beam exposure apparatus, and then subjected to post-exposure baking and development to chemically amplify. A mold resist pattern was formed.
As a result, in Example 1 and the comparative example, it was confirmed that no skirt-like protrusion was formed on the skirt portion of the chemically amplified resist pattern. In Example 1, it was confirmed that the 80 nm line and space chemically amplified resist pattern was resolved. In the comparative example, the 200 nm line and space chemically amplified resist pattern was resolved. I was staying.

(Manufacture of mask)
Subsequently, the resin film 18 and the light-shielding film 13 are formed by dry etching using an etching gas containing chlorine gas and oxygen gas using the resist pattern of the chemically amplified resist in the mask blank with a resist film of Example 1 as a mask. After patterning, the chemically amplified resist film 20 and the resin film 18 were removed by dipping in an alkaline aqueous solution to produce a transfer mask.
On the other hand, using the resist pattern of the chemically amplified resist in the mask blank with a resist film of the comparative example as a mask, the light-shielding film 13 is patterned by dry etching using an etching gas containing chlorine gas and oxygen gas. The amplification resist film 20 was removed by dipping in an alkaline aqueous solution to produce a transfer mask.
As a result, in Example 1, the pattern of the light-shielding film 13 was examined by SEM (scanning electron microscope). As a result, an 80 nm line and space pattern was resolved, and the pattern edge roughness was small and good. On the other hand, in the comparative example, only 200 nm line and space pattern was resolved as the pattern of the light shielding film 13.
Further, as a result of examining the actual dimension difference with respect to the design dimension of the mask pattern of Example 1, the actual dimension difference with respect to the design dimension of 120 nm to 1000 nm was 10 nm or less. This satisfied the linearity of 10 nm or less in the semiconductor design rule DRAM half pitch 65 nm.

(Example 2)
A mask blank and a mask were produced in the same manner as in Example 1 except that the resin film in Example 1 was changed to an acrylic resin. The film thickness of the protective film was 25 nm. When the organic acid component and the amine component were measured using an ion chromatograph analyzer in the same manner as in Example 1, the presence of the organic acid (formic acid) was clarified, and the amount was 0.6 μg / cm ³ . The total amount of organic acid was 1 μg / cm ³ or less.
In Example 2, it was also confirmed that the 80 nm line and space chemically amplified resist pattern was resolved.
Also, in the produced mask, an 80 nm line and space pattern consisting of a light-shielding film pattern is resolved, the actual dimension difference with respect to the design dimension of 120 nm to 1000 nm is 10 nm or less, and the linearity of 10 nm in the semiconductor design rule DRAM half pitch 65 nm The following were satisfied.

As mentioned above, although this invention was demonstrated using embodiment and an Example, the technical scope of this invention is not limited to the range as described in the said embodiment and Example. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above-described embodiments and examples. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

  INDUSTRIAL APPLICATION This invention can be utilized suitably for the mask blank and mask used in manufacture of a semiconductor device, a flat panel display (FPD) liquid crystal display device, etc.

It is a mimetic diagram showing an example of mask blank 10 concerning a 1st embodiment of the present invention.

Explanation of symbols

10 .... Mask blank, 12 .... Transparent substrate, 13 .... Light shielding film, 14 .... Light shielding layer, 16 .... Antireflection layer, 18 .... Resin film, 20 .... Chemically amplified resist film

Claims (7)

A method of manufacturing a mask blank in which a thin film for forming a mask pattern is formed on a substrate, and a chemically amplified resist film is formed above the thin film,
A method for manufacturing a mask blank, characterized in that a total amount of organic acids present on a surface on a thin film on which the resist film is formed is 1 μg / cm ² or less, and the resist film is formed on the surface. A method of manufacturing a mask blank in which a thin film for forming a mask pattern is formed on a substrate, and a chemically amplified resist film is formed above the thin film,
A mask blank manufacturing method comprising: forming a clean surface above the thin film so that a substance that inhibits a chemical amplification function does not inhibit formation of a resist pattern; and forming the resist film on the surface . The method for manufacturing a mask blank according to claim 1, wherein the thin film is a metal film. The method for manufacturing a mask blank according to claim 1, wherein the thin film is a film formed by a reactive sputtering method. The method for manufacturing a mask blank according to claim 1, wherein the thin film is covered with a resin film having a predetermined film density. 6. The method of manufacturing a mask blank according to claim 1, wherein the mask blank is a mask blank before forming the chemically amplified resist film. A mask manufacturing method, comprising: patterning the thin film in a mask blank manufactured by the manufacturing method according to claim 1 to form a transfer pattern on a substrate.

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