JP2024145579A - Binary mask blank, binary mask, and method for manufacturing binary mask - Google Patents

Abstract

To provide a binary mask blank, a binary mask, and a method for producing the binary mask, which are difficult to add a side etching in a light shielding layer even when the binary mask is corrected with an electron beam correction device.SOLUTION: The binary mask blank 100 of this embodiment is a binary mask blank used to produce a binary mask 10 applied to photolithography using an exposure light with a wavelength of 200 nm or less as a light source, and comprises a substrate 11 and a light-shielding film 12. The light-shielding film 12 includes a light-shielding layer 13 having light-shielding properties against the exposure light, and a low-reflective layer 14 formed on the light-shielding layer 13 and reducing reflection of the exposure light. When an electron beam correction etching rate of the light-shielding layer 13 is R1, the electron beam correction etching rate of the low-reflective layer 14 is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer 13 and the low-reflective layer 14 is R12, R12 is 0.5 or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a binary mask blank, a binary mask, and a method for manufacturing a binary mask.

In binary masks that use exposure light with a wavelength of 200 nm or less, a film structure in which a low-reflection layer is provided on a light-shielding layer to suppress scattering of light during exposure is generally adopted. For example, Patent Document 1 describes a technology related to such conventional binary masks.

In advanced binary masks, MoSiN is primarily used as the material for the light-shielding layer, and MoSiON is primarily used as the material for the low-reflection layer. Binary masks with this configuration are prone to side etching of the light-shielding layer located below the binary mask during the correction process, which is one of the photomask manufacturing processes, when correction processing is performed using an electron beam correction device (so-called electron beam correction). As a result, the dimensional accuracy of the binary mask may decrease.

Patent No. 4883278

The present invention has been made in light of the above circumstances, and aims to provide a binary mask blank, a binary mask, and a method for manufacturing a binary mask in which side etching of the light-shielding layer is unlikely to occur even when the binary mask is repaired using an electron beam repair device.

The present invention has been made to solve the above problems, and a binary mask blank according to one aspect of the present invention is a binary mask blank used to fabricate a binary mask applied to photolithography using exposure light with a wavelength of 200 nm or less as a light source, and is provided with a transparent substrate and a light-shielding film formed on the transparent substrate, the light-shielding film including a light-shielding layer having light-shielding properties against the exposure light, and a low-reflection layer formed on the light-shielding layer and reducing reflection of the exposure light, characterized in that R12 is 0.5 or more when R1 is the etching rate of the light-shielding layer in an electron beam correction device, R2 is the etching rate of the low-reflection layer in an electron beam correction device, and R12 is the ratio (R2/R1) of the etching rates of the light-shielding layer and the low-reflection layer.

In addition, a binary mask according to one aspect of the present invention is a binary mask applied to photolithography using exposure light with a wavelength of 200 nm or less as a light source, and having a transfer pattern formed thereon, the binary mask comprising a transparent substrate and a light-shielding film patterned on the transparent substrate, the light-shielding film including a light-shielding layer having light-shielding properties against the exposure light and a low-reflection layer formed on the light-shielding layer and reducing reflection of the exposure light, characterized in that R12 is 0.5 or more when the etching rate of the light-shielding layer in an electron beam correction device is R1, the etching rate of the low-reflection layer in an electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer and the low-reflection layer is R12.

The method for manufacturing a binary mask according to one aspect of the present invention is the method for manufacturing a binary mask described above, and is characterized by including the steps of forming a light-shielding film on the transparent substrate, forming a resist pattern on the light-shielding film formed on the transparent substrate, forming a pattern on the light-shielding film by fluorine-based etching after forming the resist pattern, removing the resist pattern after forming the pattern on the light-shielding film, and performing electron beam correction after removing the resist pattern.

In addition, a method for manufacturing a binary mask according to another aspect of the present invention is the method for manufacturing a binary mask described above, characterized in that it includes the steps of forming a light-shielding film on the transparent substrate, forming a hard mask film on the light-shielding film, forming a resist pattern on the hard mask film formed on the light-shielding film, forming a pattern on the hard mask film by oxygen-containing chlorine-based etching after forming the resist pattern, forming a pattern on the hard mask film by fluorine-based etching after forming a pattern on the hard mask film, removing the resist pattern and removing the hard mask film after forming a pattern on the light-shielding film, and performing electron beam correction after removing the hard mask film.

By using a binary mask blank or binary mask according to one embodiment of the present invention, it is possible to provide a binary mask blank or binary mask in which side etching is unlikely to occur in the light-shielding layer even when the binary mask is repaired using an electron beam repair device. As a result, it is possible to provide a binary mask blank or binary mask in which the deterioration of dimensional accuracy is reduced. More specifically, by using a binary mask blank or binary mask according to one embodiment of the present invention, it is possible to provide a binary mask blank or binary mask in which the repaired shape of the binary mask is improved and the success rate of repairing the binary mask is increased, thereby improving productivity.

1 is a schematic cross-sectional view showing a configuration of a binary mask blank according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a configuration of a binary mask according to an embodiment of the present invention. 1A to 1C are schematic cross-sectional views showing a manufacturing process of a binary mask using a binary mask blank according to an embodiment of the present invention. 1A to 1C are schematic cross-sectional views showing a manufacturing process of a binary mask using a binary mask blank according to an embodiment of the present invention. FIG. 11 is a schematic cross-sectional view showing a configuration of a binary mask blank according to a modified example of an embodiment of the present invention. FIG. 11 is a schematic cross-sectional view showing a configuration of a binary mask blank according to a modified example of an embodiment of the present invention. 1A is a schematic plan view showing a structure of a binary mask before a repair process according to an embodiment of the present invention; FIG. 5A to 5C are schematic cross-sectional views showing a process for repairing a binary mask according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view for explaining the amount of side etching of a light-shielding layer according to an embodiment of the present invention.

The inventors of the present application have discovered that the difference in etching rate during electron beam correction between the low-reflection layer arranged on the upper layer of the binary mask and the light-shielding layer arranged on the lower layer of the binary mask is the cause of side etching. More specifically, the inventors of the present application have investigated the cause of side etching of the light-shielding layer during correction processing using an electron beam correction device and found that the etching rates of the low-reflection layer and the light-shielding layer are significantly different. Specifically, in the binary mask according to the conventional technology, the low-reflection layer has a relatively small etching rate and the light-shielding layer has a relatively large etching rate, so that as soon as the etching of the low-reflection layer arranged on the upper layer of the binary mask is completed, the etching of the light-shielding layer arranged on the lower layer of the binary mask progresses rapidly, and the light-shielding layer is over-etched.
Therefore, the inventors of the present application have found that the side etching occurring in the light-shielding layer can be improved by adjusting the film configuration so that the etching rates of the respective layers are as equal as possible.

As described above, the inventors of the present application believe that excessive side etching occurring in the light-shielding layer can be reduced by adjusting the difference between the etching rate of the low-reflection layer and the etching rate of the light-shielding layer, and have configured the binary mask blank or binary mask as follows. In other words, the binary mask blank and binary mask according to this embodiment are based on the technical idea of reducing excessive side etching occurring in the light-shielding layer by setting R12 to 0.5 or more, where R1 is the etching rate of the light-shielding layer in the electron beam correction device, R2 is the etching rate of the low-reflection layer in the electron beam correction device, and R12 is the ratio (R2/R1) of the etching rates of the light-shielding layer and the low-reflection layer.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the schematic cross-sectional views do not accurately reflect the actual dimensional ratio or the number of patterns, and the amount of engraving in the transparent substrate and the amount of damage to the film are omitted.
Suitable embodiments of the binary mask blank and binary mask of the present invention include the following forms.

(Overall configuration of binary mask blank)
FIG. 1 is a cross-sectional schematic diagram showing the configuration of a binary mask blank according to an embodiment of the present invention. The binary mask blank 100 shown in FIG. 1 is a binary mask blank used to produce a binary mask applied to photolithography using an exposure light having a wavelength of 200 nm or less as a light source, and includes a substrate (hereinafter, also simply referred to as "substrate") 11 transparent to the exposure wavelength and a light-shielding film 12 formed on the substrate 11. The light-shielding film 12 includes a light-shielding layer 13 having light-shielding properties against the exposure light and a low-reflection layer 14 formed on the light-shielding layer 13 and reducing reflection of the exposure light. In addition, when the etching rate of the light-shielding layer 13 in an electron beam correction device is R1, the etching rate of the low-reflection layer 14 in an electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer 13 and the low-reflection layer 14 is R12, R12 is 0.5 or more.
Each layer constituting the binary mask blank 100 according to the embodiment of the present invention will be described in detail below.

(substrate)
There is no particular limitation on the substrate 11, and as the substrate 11, for example, quartz glass, _CaF2 , aluminosilicate glass, or the like is generally used.

(Light-shielding film)
The light-shielding film 12, which includes at least a light-shielding layer 13 and a low-reflection layer 14, is a film that mainly functions to shield exposure light, and is formed on the substrate 11 with or without other films interposed therebetween.
The light-shielding film 12 preferably has an optical density of 2.0 or more with respect to exposure light having a wavelength of 200 nm or less.
The thickness of the light-shielding film 12 is preferably in the range of 30 nm to 60 nm, more preferably in the range of 30 nm to 50 nm, and even more preferably in the range of 35 nm to 40 nm. From the viewpoints of washing collapse, pattern resolution, and the like, it is ideally preferable that the thickness of the light-shielding film 12 is as thin as possible, but sufficient performance in these characteristics can be obtained as long as the thickness is at least 60 nm. From the viewpoints of light-shielding properties and low reflectivity, a thickness of 30 nm or more is preferable.

The light-shielding film 12 is, for example, a film that is resistant to oxygen-containing chlorine-based dry etching (Cl/O-based) and can be etched by fluorine-based dry etching (F-based). The above-mentioned "resistance to oxygen-containing chlorine-based dry etching (Cl/O-based)" means that the oxygen-containing chlorine-based dry etching selectivity of the hard mask film 15 described later to the light-shielding film 12 is 2 or more.
Here, fluorine-based dry etching refers to dry etching using a gas containing fluorine, and the gas containing fluorine may be any gas containing elemental fluorine, such as fluorine gas, a gas containing carbon and fluorine, such as _CF4 or _{C2F6 ,} a gas containing sulfur and fluorine, such as _SF6 , or a mixed gas of a gas containing fluorine and a gas not containing fluorine, such as helium. In addition, a gas such as oxygen may be added as necessary.

<Light-shielding layer>
In this embodiment, the light-shielding layer 13 is made of a material that can be etched by fluorine-based dry etching, such as a silicon-containing material. Examples of the silicon-containing material include silicon alone and silicon compounds containing silicon and one or more selected from oxygen, nitrogen, and carbon. More specific examples of the silicon compounds include silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon nitridecarbide, and silicon oxynitridecarbide.

Also suitable are alloys of transition metals and silicon, and transition metal silicon compounds containing a transition metal, silicon, and one or more selected from oxygen, nitrogen, and carbon. More specific examples of the transition metal silicon compounds include transition metal silicon oxides, transition metal silicon nitrides, transition metal silicon oxynitrides, transition metal silicon oxycarbides, transition metal silicon carbide nitrides, and transition metal silicon oxynitride carbides.
The transition metal is preferably at least one material selected from titanium, vanadium, cobalt, nickel, zirconia, niobium, molybdenum, hafnium, tantalum and tungsten, with molybdenum being particularly preferred from the standpoint of dry etching processability.

The silicon-containing material of the light-shielding layer 13 can be etched by fluorine-based dry etching, but by selecting the composition, it is also possible to etch it with chlorine gas that does not contain oxygen.
The composition of the light-shielding layer 13 is preferably such that silicon is from 10 atomic % to 95 atomic % and particularly from 30 atomic % to 95 atomic %; oxygen is from 0 atomic % to 50 atomic % and particularly from 0 atomic % to 30 atomic %; nitrogen is from 0 atomic % to 40 atomic % and particularly from 0 atomic % to 20 atomic %; carbon is from 0 atomic % to 20 atomic % and particularly from 0 atomic % to 5 atomic %; and transition metal is from 0 atomic % to 35 atomic % and particularly from 1 atomic % to 20 atomic %.

The light-shielding layer 13 of the present embodiment may have a single-layer structure or a multi-layer structure. By using a single-layer structure, the film structure and the process reflecting this can be simplified.
In cases where the adhesion between the light-shielding layer 13 and the low-reflection layer 14, substrate 11, etc. is low and pattern defects, etc. are likely to occur, the adhesion can be improved by making the portions of the light-shielding layer 13 in contact with the low-reflection layer 14, substrate 11, etc., i.e., in the case of a single-layer structure, one or both of the end face portions in the thickness direction of the light-shielding layer 13, and in the case of a multilayer structure, one or both of the layers located at both ends in the thickness direction of the light-shielding layer 13, from a material containing, for example, nitrogen and/or oxygen, and adjusting the content of this nitrogen and/or oxygen. In addition, by forming the light-shielding layer 13 so that the composition is continuously or stepwise graded in the thickness direction, it is possible to improve the perpendicularity of the cross-sectional shape of the etching pattern. These structures can be easily formed by controlling the sputtering conditions of reactive sputtering.

The composition of the light-shielding layer 13 with a gradient in the thickness direction is preferably 10 atomic % to 95 atomic % silicon, particularly 15 atomic % to 95 atomic %, 0 atomic % to 60 atomic % oxygen, particularly 0 atomic % to 30 atomic %, 0 atomic % to 57 atomic % nitrogen, particularly 0 atomic % to 40 atomic %, 0 atomic % to 30 atomic % carbon, particularly 0 atomic % to 20 atomic %, and 0 atomic % to 35 atomic % transition metal, particularly 1 atomic % to 20 atomic %.

Furthermore, when the silicon-containing material contains a transition metal and silicon, various composition ratios can be selected. For example, a composition ratio of transition metal to silicon of transition metal:silicon = 1:4 to 1:15 (atomic ratio) is preferable because it increases stability against chemicals used for cleaning and the like. Even if the composition ratio of transition metal to silicon is outside the above range, the necessary chemical stability can be obtained by including nitrogen, particularly by setting the nitrogen content to 5 atomic % or more and 40 atomic % or less, which is particularly effective in reducing damage during dry etching with chlorine-based gas containing oxygen when etching a Cr film used in the hard mask film 15 described later. In this case, the ratio of transition metal to silicon can be, for example, transition metal:silicon = 1:1 to 1:10 (atomic ratio).

In addition, when the thickness of the low reflection layer 14 is d1 and the thickness of the light-shielding layer 13 is d2, from the viewpoint of achieving both light-shielding and low reflectivity, d1 is preferably in the range of 3 nm to 30 nm, and d2 is preferably in the range of 20 nm to 60 nm. The thickness d2 of the light-shielding layer 13 is more preferably in the range of 20 nm to 50 nm, and even more preferably in the range of 40 nm to 50 nm. If the thickness d2 of the light-shielding layer 13 is less than 20 nm, a sufficient light-shielding effect may not be obtained, and if it exceeds 60 nm, high-precision processing may become difficult with a thin resist having a thickness of 250 nm or less, or the film stress may cause warping of the substrate 11. In addition, a thickness of 60 nm or less is preferable from the viewpoint of cleaning collapse, pattern resolution, etc.
Furthermore, the thickness d2 of the light-shielding layer 13 is preferably in the range of 6 to 20 times the thickness d1 of the low-reflection layer 14, more preferably in the range of 10 to 20 times, and even more preferably in the range of 15 to 20 times.

<Low reflection layer>
The low reflection layer 14 is preferably made of a metal or metal compound that can be etched by fluorine-based dry etching, and examples thereof include transition metal-containing materials. Examples of transition metal-containing materials that contain only transition metal as a metal include a simple transition metal and a transition metal compound that contains a transition metal and one or more selected from oxygen, nitrogen, and carbon. More specific examples of the transition metal compound include transition metal oxides, transition metal nitrides, transition metal oxynitrides, transition metal oxide carbides, transition metal nitride carbides, and transition metal oxynitride carbides.

The constituent material of the low reflection layer 14 may be a silicon-containing material. Examples of the silicon-containing material include silicon alone as a metal, and silicon compounds containing silicon and at least one selected from oxygen, nitrogen, and carbon. More specifically, examples of the silicon compounds include silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon carbide nitride, and silicon oxynitride carbide.
In addition, as a metal containing silicon and a metal other than silicon, an alloy of a transition metal and silicon, and a transition metal silicon compound containing a transition metal, silicon, and one or more selected from oxygen, nitrogen, and carbon are also suitable. More specific examples of the transition metal silicon compound include transition metal silicon oxides, transition metal silicon nitrides, transition metal silicon oxynitrides, transition metal silicon oxycarbides, transition metal silicon carbide nitrides, and transition metal silicon oxynitrides.

The transition metal is preferably at least one material selected from titanium, vanadium, cobalt, nickel, zirconium, niobium, molybdenum, hafnium, tantalum and tungsten, with tantalum being particularly preferred from the standpoint of repairability.
The tantalum content is preferably within a range of 10 atomic % or more and 70 atomic % or less with respect to the entire low reflective layer 14. From the viewpoint of the correction etching rate of the low reflective layer 14, the tantalum content is preferably 10 atomic % or more, and from the viewpoint of the reflectance of the low reflective layer 14, the tantalum content is preferably 70 atomic % or less. Moreover, the tantalum content is more preferably within a range of 20 atomic % or more and 50 atomic % or less with respect to the entire low reflective layer 14.

Furthermore, the transition metal-containing material of the low reflective layer 14 can be etched by fluorine-based dry etching, but by selecting the composition, it is also possible to etch it with chlorine gas that does not contain oxygen.
The composition of the silicon-containing material described above is preferably such that silicon is from 10 atomic % to 80 atomic %, particularly from 30 atomic % to 50 atomic %, oxygen is from 0 atomic % to 60 atomic %, particularly from 0 atomic % to 40 atomic %, nitrogen is from 0 atomic % to 57 atomic %, particularly from 20 atomic % to 50 atomic %, carbon is from 0 atomic % to 20 atomic %, particularly from 0 atomic % to 5 atomic %, and transition metal is from 0 atomic % to 35 atomic %, particularly from 1 atomic % to 20 atomic %.

The low reflective layer 14 of the present embodiment may have a single-layer structure or a multi-layer structure. By using a single-layer structure, the film structure and the process reflecting this can be simplified.
In the case where the adhesion between the low-reflection layer 14 and the light-shielding layer 13 or the hard mask film 15 is low and pattern defects or the like are likely to occur, the adhesion can be improved by making the part where the low-reflection layer 14 contacts the light-shielding layer 13 or the part where the low-reflection layer 14 contacts the hard mask film 15, i.e., in the case of a single-layer structure, one or both of the end surface parts in the thickness direction of the low-reflection layer 14, and in the case of a multilayer structure, one or both of the layers located at both ends in the thickness direction of the low-reflection layer 14, a material containing, for example, nitrogen and/or oxygen, and adjusting the content of this nitrogen and/or oxygen. In addition, by forming the low-reflection layer 14 so that the composition is continuously or stepwise graded in the thickness direction, it is possible to improve the verticality of the cross-sectional shape of the etching pattern. These structures can be easily formed by controlling the sputtering conditions of reactive sputtering.

The composition of the low reflection layer 14 with a gradient in the thickness direction is preferably 0 atomic % to 90 atomic % silicon, particularly 10 atomic % to 90 atomic %, 0 atomic % to 67 atomic % oxygen, particularly 5 atomic % to 67 atomic %, 0 atomic % to 57 atomic % nitrogen, particularly 5 atomic % to 50 atomic %, 0 atomic % to 20 atomic % carbon, particularly 0 atomic % to 5 atomic %, and 0 atomic % to 95 atomic % transition metal, particularly 1 atomic % to 20 atomic %.

In this embodiment, the film thickness of the low-reflective layer 14 varies depending on the wavelength of the exposure light in exposure using a photomask, the wavelength of the light used for inspection required when producing or using the photomask, and the composition of the low-reflective layer 14, but an anti-reflection effect can be obtained by making the film thickness within the range of 3 nm or more and 30 nm or less, and a film thickness within the range of 8 nm or more and 25 nm or less is particularly preferable for ArF excimer laser exposure.
In particular, when the constituent material of the low-reflection layer 14 is a transition metal-containing material or a silicon-containing material, the film thickness is preferably in the range of 3 nm to 30 nm, and more preferably in the range of 4 nm to 10 nm when considering both low reflectivity and ease of correction. If the film thickness of the low-reflection layer 14 is less than 3 nm, a sufficient reflection effect may not be obtained, and if it exceeds 30 nm, high-precision processing may become difficult with a thin resist having a thickness of 250 nm or less, or film stress may cause warping of the substrate 11.

(Overall structure of binary mask)
The configuration of the binary mask 10 according to the embodiment of the present invention will be described below.
Fig. 2 is a schematic cross-sectional view showing the configuration of a binary mask according to an embodiment of the present invention. The binary mask 10 shown in Fig. 2 is applied to photolithography using an exposure light having a wavelength of 200 nm or less as a light source, and is a binary mask on which a circuit pattern (transfer pattern) is formed, and includes a substrate 11 transparent to the exposure wavelength and a light-shielding film 12 (12a) having a circuit pattern formed on the substrate 11. The light-shielding film 12 (12a) includes a light-shielding layer 13 having a light-shielding property against the exposure light, and a low-reflection layer 14 formed on the light-shielding layer 13 to reduce reflection of the exposure light.
The composition, configuration, etc. of the substrate 11 and the light-shielding film 12 (12a) having a circuit pattern that constitute the binary mask 10 according to the embodiment of the present invention are the same as the composition, configuration, etc. of the substrate 11 and the light-shielding film 12 that constitute the binary mask blank 100 according to the embodiment of the present invention described above. Therefore, detailed description of the composition, configuration, etc. of the substrate 11 and the light-shielding film 12 (12a) having a circuit pattern will be omitted.

(Etching rates of the light-shielding layer 13 and the low-reflection layer 14)
The binary mask blank 100 or binary mask 10 according to the conventional technology is configured by combining a low reflective layer 14 made of MoSiON and a light-shielding layer 13 made of MoSiN. However, this material configuration has a very slow correction etching rate for the low reflective layer 14 compared to the light-shielding layer 13, and when correction processing is performed under etching conditions that can process the low reflective layer 14, excessive side etching is caused in the light-shielding layer 13.
Therefore, when performing correction processing, it is preferable to make the etching rates of the low reflection layer 14 and the light-shielding layer 13 as equal as possible, and it is necessary to either increase the etching rate of the low reflection layer 14 or decrease the etching rate of the light-shielding layer 13. Here, in order to decrease the etching rate of the light-shielding layer 13, it is effective to decrease the Mo ratio of the conventional MoSiN and increase the Si ratio, but in order to obtain sufficient light-shielding properties, the film thickness becomes relatively thick. Therefore, the inventors of the present application have studied a material configuration in the direction of increasing the etching rate of the low reflection layer 14, and as a result, it has become clear that a low reflection layer 14 using Ta can obtain a correction etching rate faster than a low reflection layer 14 using MoSiN.

In this way, in the task of improving the correction etching processability of the binary mask blank 100 or binary mask 10, the inventors of the present application have found that it is important to make the correction etching rates of the low-reflection layer 14 and the light-shielding layer 13 as equal as possible. Therefore, this application discloses a new technical method of limiting (selecting) a film configuration that provides good correction processability by introducing a new parameter, the "ratio of the correction etching rates of the low-reflection layer 14 and the light-shielding layer 13."

In this embodiment, when the etching rate of the light shielding layer 13 in the electron beam correction device is R1, the etching rate of the low reflective layer 14 in the electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light shielding layer 13 and the low reflective layer 14 is R12, the film configuration is adjusted so that R12 is 0.5 or more, more preferably so that R12 is close to 1. R12 is adjusted by changing the type and content of each of the constituent materials of the light shielding layer 13 and the low reflective layer 14.
If R12 is 0.5 or more, the amount of side etching of the light-shielding layer 13 can be kept within 5 nm. If the amount of side etching of the light-shielding layer 13 is within 5 nm, the deterioration of the dimensional accuracy of the binary mask can be reduced.
Furthermore, the upper limit of R12 is not particularly limited, but is more preferably 6.0 or less, which is more preferable since side etching of the low reflective layer can be suppressed by making R12 6.0 or less.

The etching rates of the low reflective layer 14 and the light-shielding layer 13 are measured, for example, by irradiating the light-shielding film 12 (light-shielding film pattern 12a) with an electron beam in a fluorine-based gas atmosphere, for example, a gas atmosphere ( _XeF2 ) consisting of fluorine and xenon, using an electron beam correction device (MeRiT MG45: manufactured by Carl Zeiss). The flow rate of the fluorine-based gas at this time is set, for example, using a cold trap technique controlled by temperature. The temperature of the fluorine-based gas is set to 0°C. The EB current is set to 50 pA, and the EB acceleration voltage is set to 1 kV.

In this embodiment, the etching rates of the low reflective layer 14 and the light-shielding layer 13 were determined under the above-mentioned measurement conditions using the following measurement method.
First, a rectangular (500 nm×500 nm) hole pattern is formed by electron beam correction, and the amount of engraving at the processing location is measured using an AFM (Atomic Force Microscope).
Next, the amount of digging per unit time was defined as the corrected etching rate of each of the low reflection layer 14 and the light-shielding layer 13 by dividing the amount of digging by the time required for processing.
Each corrected etching rate was determined as an average value of five points on the mask surface.

The thus measured repair etching rate R1 when only the light-shielding layer 13 is repaired by electron beam is preferably, for example, 2.5 nm/min or more, more preferably 3.0 nm/min or more, and even more preferably 3.5 nm/min or more.
If the corrected etching rate R1 of the light-shielding layer 13 is within the above numerical range, the selectivity with respect to the substrate 11 becomes appropriate, so that unnecessary digging into the substrate 11 can be suppressed.
The correction etching rate R2 measured in this manner when only the low-reflective layer 14 is corrected by the electron beam may be 0.5 times or more, preferably in the range of 0.5 times or more and 6.0 times or less, and more preferably in the range of 0.5 times or more and 2.0 times or less, relative to the correction etching rate R1 when only the light-shielding layer 13 is corrected by the electron beam.

(Binary mask manufacturing method)
The method for manufacturing a binary mask 10 using the binary mask blank 100 according to this embodiment includes the steps of forming a light-shielding film 12 including at least a light-shielding layer 13 and a low-reflection layer 14 on a substrate 11, forming a resist pattern 16 on the light-shielding film 12 formed on the substrate 11, forming a pattern in the light-shielding film 12 (light-shielding layer 13 and low-reflection layer 14) by fluorine-based dry etching (F-based) after forming the resist pattern 16, removing the resist pattern 16 after forming the pattern in the light-shielding film 12, and performing a defect inspection after removing the resist pattern 16. Furthermore, in the method for manufacturing a binary mask 10 using the binary mask blank 100 according to this embodiment, when a defect is detected by the above-mentioned defect inspection, the light-shielding film 12 (light-shielding layer 13 and low-reflection layer 14) at the defective portion is subjected to electron beam correction etching using a fluorine-based gas.

Furthermore, a manufacturing method of the binary mask 10 using the binary mask blank 100 according to this embodiment may include the steps of forming a light-shielding film 12 including at least a light-shielding layer 13 and a low-reflection layer 14 on a substrate 11, forming a hard mask film 15 on the light-shielding film 12 formed on the substrate 11, forming a resist pattern 16 on the hard mask film 15 formed on the light-shielding film 12, forming a pattern in the hard mask film 15 by oxygen-containing chlorine-based dry etching (Cl/O-based) after forming the resist pattern 16, forming a pattern in the hard mask film 15 by fluorine-based dry etching (F-based) after forming the pattern in the hard mask film 15 (light-shielding layer 13 and low-reflection layer 14), forming a pattern in the light-shielding film 12 (light-shielding layer 13 and low-reflection layer 14) by fluorine-based dry etching (F-based) after forming the pattern in the light-shielding film 12, removing the resist pattern 16 and removing the hard mask film 15, and performing a defect inspection after removing the hard mask film 15. Furthermore, in the manufacturing method of the binary mask 10 using the binary mask blank 100 of this embodiment, when a defect is detected by the above-mentioned defect inspection, the light-shielding film 12 (light-shielding layer 13 and low-reflection layer 14) in the defective area is subjected to electron beam correction etching using a fluorine-based gas.
Here, the above-mentioned hard mask film 15 according to the embodiment of the present invention will be described.

(Hard mask film)
The hard mask film 15 is a layer formed on the binary mask blank 100 (low reflective layer 14) according to the embodiment of the present invention described above.
The hard mask film 15 in this embodiment is required to be resistant to fluorine-based dry etching. Here, the above-mentioned "resistant to fluorine-based dry etching" means that the fluorine-based dry etching selectivity of the light-shielding film 12 to the hard mask film 15 is 2 or more.

In fluorine-based dry etching, the hard mask film 15 is preferably such that the etching selectivity to the light-shielding film 12 (fluorine-based dry etching selectivity of the light-shielding film 12 to the hard mask film 15) is 2 or more, since this suppresses the amount of side etching of the pattern and provides a photomask blank that enables the formation of finer patterns.
Furthermore, by making the etching selectivity ratio of the hard mask film 15 to the substrate 11 in fluorine-based dry etching (the fluorine-based dry etching selectivity of the substrate 11 to the hard mask film 15) 10 or more, a photomask blank suitable for manufacturing a Levenson type or CPL type photomask in which a photomask is formed by etching the substrate 11 can be obtained.

For such a hard mask film 15, a chromium-based material or a material containing tantalum but not containing silicon can be used.
The chromium-based material may be chromium alone or a chromium compound containing chromium and one or more selected from oxygen, nitrogen, and carbon, and is preferably silicon-free. More specifically, the chromium compound may be chromium oxide, chromium nitride, chromium oxynitride, chromium oxide carbide, chromium nitride carbide, or chromium oxynitride carbide. These materials have high resistance to fluorine-based dry etching.

In particular, a chromium content of 50 atomic % or more, particularly 60 atomic % or more, is preferable because it has good resistance to fluorine-based dry etching and can provide sufficient etching selectivity to the light-shielding film 12 and/or the substrate 11, while at the same time allowing the hard mask film 15 to be dry-etched under dry etching conditions containing chlorine and oxygen to form a pattern.
The chromium-based material may, for example, contain chromium in an amount of 50 atomic % or more and 100 atomic % or less, particularly 60 atomic % or more and 100 atomic % or less, oxygen in an amount of 0 atomic % or more and 50 atomic % or less, particularly 0 atomic % or more and 40 atomic % or less, nitrogen in an amount of 0 atomic % or more and 50 atomic % or less, particularly 0 atomic % or more and 40 atomic % or less, and carbon in an amount of 0 atomic % or more and 20 atomic % or less, particularly 0 atomic % or more and 10 atomic % or less, thereby making it possible to provide the hard mask film 15 with sufficient etching selectivity for the light-shielding film 12 and/or the substrate 11.

The hard mask film 15 of the present embodiment can have a single-layer structure or a multi-layer structure. If it has a single-layer structure, the film configuration and the process reflecting this can be simplified.
In cases where the adhesion between the hard mask film 15 and the light-shielding film 12, etc. is low and pattern defects, etc. are likely to occur, or when the resist pattern 16 is formed directly on the hard mask film 15 during photomask manufacturing, tailing or constriction of the resist pattern 16 occurs, resulting in a poor cross-sectional shape, etc., the adhesion can be improved by making the part where the hard mask film 15 is in contact with the light-shielding film 12, etc., or the part where the resist pattern 16 is in contact, i.e., in the case of a single-layer structure, one or both of the end face parts in the thickness direction of the hard mask film 15, or in the case of a multilayer structure, one or both of the layers located at both ends in the thickness direction of the hard mask film 15, a material containing, for example, nitrogen and/or oxygen, and adjusting the content of this nitrogen and/or oxygen. In addition, by forming the hard mask film 15 so that the composition is continuously or stepwise graded in the thickness direction, it is possible to improve the verticality of the cross-sectional shape of the etching pattern. These structures can be easily formed by controlling the sputtering conditions of reactive sputtering.

The composition of the hard mask film 15 having a gradient in composition in the thickness direction is preferably chromium from 50 atomic % to 100 atomic %, particularly from 60 atomic % to 100 atomic %, oxygen from 0 atomic % to 60 atomic %, particularly from 0 atomic % to 50 atomic %, nitrogen from 0 atomic % to 50 atomic %, particularly from 0 atomic % to 40 atomic %, and carbon from 0 atomic % to 20 atomic %, particularly from 0 atomic % to 10 atomic %.
The hard mask film 15, which has etching resistance to fluorine-based dry etching, is made thin enough to avoid the problem of density dependency of the transferred pattern during dry etching, thereby avoiding the problem of density dependency of the hard mask film 15. In this embodiment, the density dependency of the transferred pattern is clearly lower than that of a conventional photomask blank using a film that cannot be etched by fluorine-based dry etching as the light-shielding film 12.

The thickness of the hard mask film 15 can be appropriately selected depending on the film configuration. Usually, a thickness of 2 to 55 nm is sufficient to provide a sufficient hard mask function (etching mask function) for etching the light-shielding film 12 and for etching the substrate 11 together with the light-shielding film 12, but in order to reduce the density dependency of the hard mask film 15, a thickness of 2 to 30 nm is particularly preferable.
When the binary mask 10 of this embodiment is used after removing the hard mask film 15, the combined optical density OD of the light-shielding layer 13 and the low-reflection layer 14 (i.e., the optical density OD of the light-shielding film 12 with respect to exposure light having a wavelength of 200 nm or less) is preferably 2.0 or more, particularly 2.7 or more, and especially 3.0 or more. If the optical density OD is 2.0 or more, it can be said that the light-shielding film 12 functions.

When the binary mask 10 of this embodiment is used without removing the hard mask film 15, it is preferable that the combined optical density OD of the hard mask film 15, the light-shielding layer 13, and the low-reflection layer 14 (i.e., the optical density OD for exposure light with a wavelength of 200 nm or less when the light-shielding film 12 and the hard mask film 15 are stacked) is 2.0 or more, particularly 2.7 or more, and especially 3.0 or more. If the optical density OD is 2.0 or more, it can be said to function as a light-shielding film 12.

The hard mask film 15 can be formed by a known method. A preferred method for obtaining a film having excellent uniformity most easily is a sputtering film formation method, but the present embodiment is not limited to the sputtering film formation method.
The target and the sputtering gas are selected according to the film composition. For example, a method for forming a film containing chromium can be exemplified by using a target containing chromium and performing reactive sputtering in only an inert gas such as argon gas, only a reactive gas such as oxygen, or a mixed gas of an inert gas and a reactive gas. The flow rate of the sputtering gas can be adjusted according to the film characteristics, and may be constant during film formation, or may be changed according to the desired composition when the amount of oxygen or nitrogen is to be changed in the thickness direction of the film. In addition, the power applied to the target, the distance between the target and the substrate, and the pressure in the film formation chamber may be adjusted.

The steps of the method for manufacturing the binary mask 10 according to an embodiment of the present invention are described in detail below.

(First manufacturing method)
FIG. 3 is a schematic cross-sectional view showing a manufacturing process of a binary mask 10 using the binary mask blank 100 shown in FIG. 1. FIG. 3(a) shows a process of forming a light-shielding film 12 having a light-shielding layer 13 and a low-reflection layer 14 on a substrate 11. FIG. 3(b) shows a process of applying a resist film on the light-shielding film 12, performing drawing, and then performing a development process to form a resist pattern 16. FIG. 3(c) shows a process of patterning the light-shielding film 12 by fluorine-based dry etching (F-based) along the resist pattern 16 to form a light-shielding film pattern 12a. FIG. 3(d) shows a process of peeling off and removing the resist pattern 16, followed by cleaning. In this way, the binary mask 10 according to this embodiment is manufactured.
The present manufacturing process includes a step of performing a defect inspection after peeling and removing the resist pattern 16. If a defect is detected in the defect inspection, the light-shielding film 12 (light-shielding layer 13 and low-reflection layer 14) at the defective portion is subjected to electron beam correction etching using a fluorine-based gas, thereby manufacturing the binary mask 10 according to the present embodiment.

The binary mask 10 according to this embodiment manufactured in this manner is a binary mask to which exposure light having a wavelength of 200 nm or less is applied, and includes a substrate 11 and a light-shielding film 12 formed on the substrate 11 with or without other films. The light-shielding film 12 (12a) having a circuit pattern includes a light-shielding layer 13 having light-shielding properties against the exposure light, and a low-reflection layer 14 formed on the light-shielding layer 13 and reducing the reflection of the exposure light. Furthermore, when the etching rate of the light-shielding layer 13 in the electron beam correction device is R1, the etching rate of the low-reflection layer 14 in the electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer 13 and the low-reflection layer 14 is R12, R12 is 0.5 or more.

In the step of FIG. 3(b), the resist film may be made of either a positive resist or a negative resist, but it is preferable to use a chemically amplified resist for electron beam writing, which allows for the formation of a highly accurate pattern. The thickness of the resist film is, for example, in the range of 50 nm to 250 nm. In particular, when making a binary mask that requires fine pattern formation, in order to prevent pattern collapse, it is necessary to make the resist film thin so that the aspect ratio of the resist pattern 16 does not become large, and a thickness of 200 nm or less is preferable. On the other hand, the lower limit of the thickness of the resist film is determined by comprehensively considering conditions such as the etching resistance of the resist material used, and is preferably 60 nm or more. When a chemically amplified resist for electron beam writing is used as the resist film, the energy density of the electron beam during writing is in the range of 35 μC/cm ² to 100 μC/cm ² , and after this writing, a heat treatment and a development treatment are performed to obtain the resist pattern 16.
In the step of FIG. 3D, the resist pattern 16 may be removed by wet stripping using a stripping solution, or by dry stripping using dry etching.

In the process of Fig. 3(c), the conditions of the fluorine-based dry etching (F-based) for patterning the light-shielding film 12 may be known ones that have been used when dry etching a silicon-based compound film, a tantalum compound film, a molybdenum compound film, etc., and the fluorine-based gas is generally _CF4 , _{C2F6 ,} or _SF6 , and may be mixed with an active gas such as oxygen, or an inert gas such as nitrogen gas or helium gas as necessary. In the case of Fig. 3(c), the upper resist pattern 16 has resistance to the fluorine-based dry etching (F-based) and functions as a mask for patterning the light-shielding film 12 in this process, so it is not completely removed and remains. In Fig. 3(c), it is common to simultaneously dig the substrate 11 by about 1 nm to 3 nm to prevent the light-shielding film 12 from being removed.

(Second manufacturing method)
FIG. 4 is a schematic cross-sectional view showing a manufacturing process of a binary mask 10 using the binary mask blank 100 shown in FIG. 1. FIG. 4(a) shows a process of forming a light-shielding film 12 having a light-shielding layer 13 and a low-reflection layer 14 on a substrate 11, and forming a hard mask film 15 on the light-shielding film 12. FIG. 4(b) shows a process of applying a resist film on the hard mask film 15, performing drawing, and then performing a development process to form a resist pattern 16. FIG. 4(c) shows a process of patterning the hard mask film 15 by oxygen-containing chlorine-based dry etching (Cl/O-based) along the resist pattern 16. FIG. 4(d) shows a process of patterning the light-shielding film 12 by fluorine-based dry etching (F-based) along the pattern of the hard mask film 15 to form a light-shielding film pattern 12a. FIG. 4(e) shows a process of peeling and removing the resist pattern 16, followed by cleaning. 4F shows a process of removing the hard mask film 15 from above the light-shielding film 12 (low-reflection layer 14) on which the pattern is formed, by oxygen-containing chlorine-based dry etching (Cl/O-based). In this manner, the binary mask 10 according to this embodiment is manufactured.
The present manufacturing process includes a step of performing a defect inspection after removing the hard mask film 15. If a defect is detected in the defect inspection, the light-shielding film 12 (light-shielding layer 13 and low-reflection layer 14) at the defective portion is subjected to electron beam correction etching using a fluorine-based gas, thereby manufacturing the binary mask 10 according to the present embodiment.

The binary mask 10 according to this embodiment manufactured in this manner is a binary mask to which exposure light having a wavelength of 200 nm or less is applied, and includes a substrate 11 and a light-shielding film 12 formed on the substrate 11 with or without other films. The light-shielding film 12 (12a) having a circuit pattern includes a light-shielding layer 13 having light-shielding properties against the exposure light, and a low-reflection layer 14 formed on the light-shielding layer 13 and reducing the reflection of the exposure light. Furthermore, when the etching rate of the light-shielding layer 13 in the electron beam correction device is R1, the etching rate of the low-reflection layer 14 in the electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer 13 and the low-reflection layer 14 is R12, R12 is 0.5 or more.

In the step of FIG. 4(b), the resist film may be made of either a positive resist or a negative resist, but it is preferable to use a chemically amplified resist for electron beam writing, which allows for the formation of a highly accurate pattern. The thickness of the resist film is, for example, in the range of 50 nm to 250 nm. In particular, when making a binary mask that requires fine pattern formation, in order to prevent pattern collapse, it is necessary to thin the resist film so that the aspect ratio of the resist pattern 16 does not become large, and a thickness of 200 nm or less is preferable. On the other hand, the lower limit of the thickness of the resist film is determined by comprehensively considering conditions such as the etching resistance of the resist material used, and is preferably 60 nm or more. When a chemically amplified resist for electron beam writing is used as the resist film, the energy density of the electron beam during writing is in the range of 35 μC/cm ² to 100 μC/cm ² , and after this writing, a heat treatment and a development treatment are performed to obtain the resist pattern 16.
In the step of FIG. 4(e), the resist pattern 16 may be removed by wet stripping using a stripping liquid, or by dry stripping using dry etching.

In the step of FIG. 4(c), the conditions of the oxygen-containing chlorine-based dry etching (Cl/O-based) for patterning the hard mask film 15 made of chromium alone or a chromium compound may be known conditions that have been used to remove chromium compound films, and in addition to chlorine gas and oxygen gas, an inert gas such as nitrogen gas or helium gas may be mixed as necessary. The lower light-shielding film 12 is resistant to the oxygen-containing chlorine-based dry etching (Cl/O-based), so it remains without being removed or patterned in this step.

In the step of FIG. 4(d), the conditions of the fluorine-based dry etching (F-based) for patterning the light-shielding film 12 may be known conditions that have been used when dry etching a silicon-based compound film, a tantalum compound film, a molybdenum compound film, or the like, and the fluorine-based gas is generally CF ₄ , C ₂ F ₆ , or SF ₆ , and may be mixed with an active gas such as oxygen, or an inert gas such as nitrogen gas or helium gas, as necessary. In the case of FIG. 4(d), the upper hard mask film 15 or resist pattern 16 has resistance to the fluorine-based dry etching (F-based), and in this step, the upper hard mask film 15 mainly functions as a mask for patterning the light-shielding film 12, and is not completely removed and remains. The resist pattern 16 does not necessarily need to remain after the dry etching, and if the upper hard mask film 15 has sufficient resistance to the fluorine-based dry etching (F-based), it may be peeled off before the dry etching. In FIG. 4D, the substrate 11 is generally recessed by about 1 nm to 3 nm at the same time to prevent the light-shielding film 12 from being removed.

In the step of FIG. 4(f), the conditions for the oxygen-containing chlorine-based dry etching (Cl/O-based) for removing the hard mask film 15 may be known conditions that have been used to remove chromium compound films, and in addition to chlorine gas and oxygen gas, an inert gas such as nitrogen gas or helium gas may be mixed as necessary. The underlying light-shielding film 12 and substrate 11 are both resistant to oxygen-containing chlorine-based dry etching (Cl/O-based), and therefore remain without being removed or patterned in this step.

Other Embodiments
In this embodiment, as shown in Fig. 1, a binary mask blank 100 including a substrate 11 and a light-shielding film 12 having a light-shielding layer 13 and a low-reflection layer 14 has been described, but the present invention is not limited thereto. For example, the binary mask blank 100 may be in a form including the above-mentioned hard mask film 15 on the light-shielding film 12, as shown in Fig. 5. With the above-mentioned form, a finer photomask pattern can be created.
The thickness of the hard mask film 15 is determined from the viewpoints of the selectivity with respect to the light-shielding film 13 during light-shielding film etching and the processability of the hard mask film 15 itself, and is preferably thin from the viewpoint of processability if the hard mask film 15 has sufficient F-based etching resistance. Specifically, the thickness is preferably 20 nm or less, and more preferably 5 nm to 10 nm.

In this embodiment, as shown in FIG. 1, the binary mask blank 100 is described in the form in which the substrate 11 and the light-shielding layer 13 constituting the light-shielding film 12 are in contact with each other, but the present invention is not limited to this. For example, as shown in FIG. 6, the binary mask blank 100 may have a low-reflection layer 14' between the substrate 11 and the light-shielding layer 13 constituting the light-shielding film 12. In other words, the binary mask blank 100 may have a form in which the substrate 11, the low-reflection layer (second low-reflection layer) 14', the light-shielding layer 13, and the low-reflection layer (first low-reflection layer) 14 are provided in this order. With the above form, a photomask with higher transfer performance can be created.

The thickness of the low reflection layer (second low reflection layer) 14' is determined from the viewpoints of back surface reflectance and processability. When suppressing back surface reflectance, if the layer is too thin, sufficient low reflection performance cannot be obtained, while if the layer is too thick, processability deteriorates and a good pattern shape cannot be obtained. When considering both of these, a thickness of 1 nm or more and 10 nm or less is preferable.
In addition, the constituent material of the low reflection layer (second low reflection layer) 14' may be the same as or different from the constituent material of the low reflection layer (first low reflection layer) 14. For example, the low reflection layer 14' may have a higher or lower tantalum content than the low reflection layer 14. Increasing the tantalum content increases the electron beam correction etching rate, which is preferable from the viewpoint of correction processability. However, on the other hand, the low reflection performance decreases, so it is necessary to select the content taking these factors into consideration.

[Example]
The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

Example 1
A light-shielding layer made of silicon and nitrogen was formed to a thickness of 60 nm on a quartz substrate using a DC sputtering device with one target. The target was silicon, and the sputtering gas was argon and nitrogen. The composition of this light-shielding layer was analyzed by ESCA and found to be Si:N=80:20 (atomic % ratio).
Next, a low reflection layer made of tantalum and oxygen was formed on the light-shielding layer to a thickness of 5 nm using a DC sputtering device. The target was tantalum, and the sputtering gas was argon and oxygen. The composition of this low reflection layer was analyzed by ESCA and found to be Ta:O=35:65 (atomic % ratio).

Next, a hard mask film made of chromium and nitrogen was formed on the low reflection layer to a thickness of 5 nm using a DC sputtering device. Chromium was used as the target, and argon and nitrogen were used as the sputtering gas. The composition of this hard mask film was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio).
In this manner, a binary mask blank according to Example 1 was obtained.
Next, a negative chemically amplified electron beam resist was spin-coated onto this hard mask film to a thickness of 80 nm, and a pattern was written using an electron beam at a dose of 35 μC/ ^cm2. The resist was then heat-treated at 110° C. for 10 minutes and developed by paddle development for 90 seconds to form a resist pattern.
Next, the hard mask film was patterned using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 400 W, and the bias power to 10 W. Overetching was performed by 200%.

Next, the light-shielding film (light-shielding layer and low-reflection layer) was patterned using a dry etching device. _SF6 and helium were used as the etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 200 W, and the bias power to 50 W. Overetching was performed by 30%.
Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and water.
Next, the hard mask film was removed using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 10 mTorr, the ICP power to 500 W, and the bias power to 10 W. Overetching was performed by 200%. During this process, no damage was caused to the lower light-shielding film (light-shielding layer and low-reflection layer) and the quartz substrate.
In this manner, the binary mask according to the first embodiment was obtained.

Next, this binary mask was subjected to electron beam correction, the method of which will be described below.
(How to fix it)
A method for electron beam repair of the binary mask 10 will be described with reference to Figures 7 and 8. Note that, although a case where defect inspection and repair are performed after removing the hard mask film 15 will be described here, defect inspection and repair may also be performed after removing the resist pattern 16 and before removing the hard mask film 15.

7 shows an enlarged view of a portion of the light-shielding film 12 (light-shielding film pattern 12a) in the binary mask 10. More specifically, Fig. 7(a) is a schematic plan view showing the structure of the binary mask 10 according to this embodiment before the repair process, and Fig. 7(b) is a schematic cross-sectional view showing the structure of the binary mask 10 according to this embodiment before the repair process.
Hereinafter, a specific method will be described for performing electron beam correction etching on the light-shielding film 12 (light-shielding film pattern 12a) formed by dry etching using the resist pattern 16. In Fig. 7(a), "L" indicates the region where the light-shielding film 12 is formed, and "S" indicates the region where the substrate 11 is exposed. Also, in Fig. 7, "12b" indicates the electron beam correction etching location.

First, as shown in Fig. 7, the light-shielding film 12 (light-shielding film pattern 12a) was irradiated with an electron beam in a fluorine-based gas atmosphere, for example, a gas atmosphere ( _XeF2 ) consisting of fluorine and xenon, using an electron beam correction device (MeRiT MG45: manufactured by Carl Zeiss) to perform electron beam correction etching. The flow rate of the fluorine-based gas at this time was controlled by a cold trap technique controlled by temperature. In this embodiment, the temperature of the fluorine-based gas was set to 0°C. The EB current was set to 50 pA, and the EB acceleration voltage was set to 1 kV.
In this way, as shown in FIG. 8, a binary mask 10 was obtained in which the light-shielding film 12 (light-shielding film pattern 12a) was subjected to electron beam correction etching.

The evaluation results of the above-mentioned repairability are shown in Table 1 below.
In addition, "low reflective layer/light-shielding layer R12 (R2/R1)" shown in Table 1 indicates the ratio of the low reflective layer correction etching rate R2 to the light-shielding layer correction etching rate R1.
In Example 1, it was confirmed that "R12 (R2/R1)" in the electron beam correction etching of the light-shielding film 12 (light-shielding film pattern 12a) was 17.80.

The above "R12 (R2/R1)" means that the larger the value, the more difficult the electron beam correction etching of the light-shielding layer is compared with the electron beam correction etching of the low-reflecting layer, and the more the excessive side etching of the light-shielding layer in the electron beam correction etching is reduced. If "R12 (R2/R1)" is 0.5 or more, the excessive side etching of the light-shielding layer is less likely to occur, and if "R12 (R2/R1)" is 1.0 or more, the excessive side etching of the light-shielding layer is even less likely to occur. Note that if "R12 (R2/R1)" is less than 0.5, it can be said that there is a possibility that the light-shielding layer will have excessive side etching in the electron beam correction etching.
From the above measurement results, it was confirmed that, in the case of the binary mask of Example 1, since "R12 (R2/R1)" is 17.80, it is possible to prevent the occurrence of excessive side etching in the light-shielding layer during electron beam correction of the light-shielding film.

Also, as shown in Table 1, it was confirmed that the side etching amount of the light-shielding layer 13 in the electron beam correction etching was 0 nm. In other words, the side surface of the light-shielding layer 13 was perpendicular to the surface of the substrate 11. The "side etching amount of the light-shielding layer 13" measured in this embodiment means the "width of the side etching", and as shown in FIG. 9, when the most protruding part in the in-plane direction of the light-shielding film 12 on the side surface in contact with the electron beam correction etching part of the light-shielding film 12 is the convex part, and the most recessed part in the in-plane direction of the light-shielding film 12 is the concave part, it means the distance from the convex part to the concave part in the in-plane direction of the light-shielding film 12. In FIG. 9, the above-mentioned convex part corresponds to the end part of the low reflection layer 14, and the above-mentioned concave part corresponds to the surface part of the light-shielding layer 13. The side etching amount according to the embodiment of the present invention is preferably 5 nm or less. If the side etching amount is 5 nm or less, the deterioration of the transfer performance can be reduced.

Example 2
A light-shielding layer made of silicon and nitrogen was formed to a thickness of 60 nm on a quartz substrate using a DC sputtering device with one target. The target was silicon, and the sputtering gas was argon and nitrogen. The composition of this light-shielding layer was analyzed by ESCA and found to be Si:N=80:20 (atomic % ratio).
Next, a low-reflection layer made of molybdenum, silicon, and nitrogen was formed on the light-shielding layer with a thickness of 5 nm using a DC sputtering device. Molybdenum and silicon were used as targets, and argon and nitrogen were used as sputtering gas. The composition of this low-reflection layer was analyzed by ESCA and found to be Mo:Si:N=10:35:55 (atomic percentage ratio).

Next, a hard mask film made of chromium and nitrogen was formed on the low reflection layer to a thickness of 5 nm using a DC sputtering device. Chromium was used as the target, and argon and nitrogen were used as the sputtering gas. The composition of this hard mask film was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio).
In this manner, a binary mask blank according to Example 2 was obtained.
Next, a negative chemically amplified electron beam resist was spin-coated onto this hard mask film to a thickness of 80 nm, and a pattern was written using an electron beam at a dose of 35 μC/ ^cm2. The resist was then heat-treated at 110° C. for 10 minutes and developed by paddle development for 90 seconds to form a resist pattern.
Next, the hard mask film was patterned using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 400 W, and the bias power to 10 W. Overetching was performed by 200%.

Next, the light-shielding film (light-shielding layer and low-reflection layer) was patterned using a dry etching device. _SF6 and helium were used as the etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 200 W, and the bias power to 50 W. Overetching was performed by 30%.
Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and water.
Next, the hard mask film was removed using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 10 mTorr, the ICP power to 500 W, and the bias power to 10 W. Overetching was performed by 200%. During this process, no damage was caused to the lower light-shielding film (light-shielding layer and low-reflection layer) and the quartz substrate.
In this manner, a binary mask according to the second embodiment was obtained.

Next, this binary mask was subjected to electron beam correction, and the etching rate of each layer during the electron beam correction was measured. As a result, "R12 (R2/R1)" was 3.38, and the "side etching amount of the light-shielding layer" was 0 nm.
From the above results, it was confirmed that with the binary mask of Example 2, since "R12 (R2/R1)" is 3.38, it is possible to prevent excessive side etching of the light-shielding layer during electron beam correction of the light-shielding film.

Example 3
A light-shielding layer made of silicon and nitrogen was formed to a thickness of 60 nm on a quartz substrate using a DC sputtering device with one target. The target was silicon, and the sputtering gas was argon and nitrogen. The composition of this light-shielding layer was analyzed by ESCA and found to be Si:N=80:20 (atomic % ratio).
Next, a low-reflection layer made of molybdenum, silicon, and nitrogen was formed on the light-shielding layer with a thickness of 5 nm using a DC sputtering device. Molybdenum and silicon were used as targets, and argon, oxygen, and nitrogen were used as sputtering gas. The composition of this low-reflection layer was analyzed by ESCA and found to be Mo:Si:O:N=5:40:35:20 (atomic percentage ratio).

Next, a hard mask film made of chromium and nitrogen was formed on the low reflection layer to a thickness of 5 nm using a DC sputtering device. Chromium was used as the target, and argon and nitrogen were used as the sputtering gas. The composition of this hard mask film was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio).
In this manner, a binary mask blank according to Example 3 was obtained.
Next, a negative chemically amplified electron beam resist was spin-coated onto this hard mask film to a thickness of 80 nm, and a pattern was written using an electron beam at a dose of 35 μC/ ^cm2. The resist was then heat-treated at 110° C. for 10 minutes and developed by paddle development for 90 seconds to form a resist pattern.
Next, the hard mask film was patterned using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 400 W, and the bias power to 10 W. Overetching was performed by 200%.

Next, the light-shielding film (light-shielding layer and low-reflection layer) was patterned using a dry etching device. _SF6 and helium were used as the etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 200 W, and the bias power to 50 W. Overetching was performed by 30%.
Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and water.
Next, the hard mask film was removed using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 10 mTorr, the ICP power to 500 W, and the bias power to 10 W. Overetching was performed by 200%. During this process, no damage was caused to the lower light-shielding film (light-shielding layer and low-reflection layer) and the quartz substrate.
In this manner, a binary mask according to the third embodiment was obtained.

Next, this binary mask was subjected to electron beam correction, and the etching rate of each layer during the electron beam correction was measured. As a result, "R12 (R2/R1)" was 1.56, and the "side etching amount of the light-shielding layer" was 0 nm.
From the above results, it was confirmed that with the binary mask of Example 3, since "R12 (R2/R1)" is 1.56, it is possible to prevent excessive side etching of the light-shielding layer during electron beam correction of the light-shielding film.

Example 4
A light-shielding layer made of silicon, molybdenum, oxygen, and nitrogen was formed to a thickness of 45 nm on a quartz substrate using a DC sputtering device with one target. The target was molybdenum silicide, and the sputtering gas was argon, oxygen, and nitrogen. The composition of this light-shielding layer was analyzed by ESCA and found to be Mo:Si:N=55:20:25 (atomic percentage ratio).
Next, a low reflection layer made of tantalum and oxygen was formed on the light-shielding layer to a thickness of 5 nm using a DC sputtering device. The target was tantalum, and the sputtering gas was argon and oxygen. The composition of this low reflection layer was analyzed by ESCA and found to be Ta:O=35:65 (atomic % ratio).

Next, a hard mask film made of chromium and nitrogen was formed on the low reflection layer to a thickness of 5 nm using a DC sputtering device. Chromium was used as the target, and argon and nitrogen were used as the sputtering gas. The composition of this hard mask film was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio).
In this manner, a binary mask blank according to Example 4 was obtained.
Next, a negative chemically amplified electron beam resist was spin-coated onto this hard mask film to a thickness of 80 nm, and a pattern was written using an electron beam at a dose of 35 μC/ ^cm2. The resist was then heat-treated at 110° C. for 10 minutes and developed by paddle development for 90 seconds to form a resist pattern.
Next, the hard mask film was patterned using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 400 W, and the bias power to 10 W. Overetching was performed by 200%.

Next, the light-shielding film (light-shielding layer and low-reflection layer) was patterned using a dry etching device. _SF6 and helium were used as the etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 200 W, and the bias power to 50 W. Overetching was performed by 30%.
Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and water.
Next, the hard mask film was removed using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 10 mTorr, the ICP power to 500 W, and the bias power to 10 W. Overetching was performed by 200%. During this process, no damage was caused to the lower light-shielding film (light-shielding layer and low-reflection layer) and the quartz substrate.
In this manner, a binary mask according to Example 4 was obtained.

Next, this binary mask was subjected to electron beam correction, and the etching rate of each layer during the electron beam correction was measured. As a result, "R12 (R2/R1)" was 0.66, and the "side etching amount of the light-shielding layer" was 2 nm.
From the above results, it was confirmed that with the binary mask of Example 4, since "R12 (R2/R1)" is 0.66, it is possible to prevent excessive side etching of the light-shielding layer during electron beam correction of the light-shielding film.

(Comparative Example 1)
A light-shielding layer made of silicon, molybdenum, oxygen, and nitrogen was formed to a thickness of 45 nm on a quartz substrate using a DC sputtering device with one target. The target was molybdenum silicide, and the sputtering gas was argon, oxygen, and nitrogen. The composition of this light-shielding layer was analyzed by ESCA and found to be Mo:Si:N=55:20:25 (atomic percentage ratio).
Next, a low-reflection layer made of molybdenum, silicon, oxygen, and nitrogen was formed on the light-shielding layer with a thickness of 5 nm using a DC sputtering device. Molybdenum and silicon were used as targets, and argon, oxygen, and nitrogen were used as sputtering gas. The composition of this low-reflection layer was analyzed by ESCA and found to be Mo:Si:O:N=5:40:35:20 (atomic percentage ratio).

Next, a hard mask film made of chromium and nitrogen was formed on the low reflection layer to a thickness of 5 nm using a DC sputtering device. Chromium was used as the target, and argon and nitrogen were used as the sputtering gas. The composition of this hard mask film was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio).
In this manner, a binary mask blank according to Comparative Example 1 was obtained.
Next, a negative chemically amplified electron beam resist was spin-coated onto this hard mask film to a thickness of 80 nm, and a pattern was written using an electron beam at a dose of 35 μC/ ^cm2. The resist was then heat-treated at 110° C. for 10 minutes and developed by paddle development for 90 seconds to form a resist pattern.
Next, the hard mask film was patterned using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 400 W, and the bias power to 10 W. Overetching was performed by 200%.

Next, the light-shielding film (light-shielding layer and low-reflection layer) was patterned using a dry etching device. _SF6 and helium were used as the etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 200 W, and the bias power to 50 W. Overetching was performed by 30%.
Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and water.
Next, the hard mask film was removed using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 10 mTorr, the ICP power to 500 W, and the bias power to 10 W. Overetching was performed by 200%. During this process, no damage was caused to the lower light-shielding film (light-shielding layer and low-reflection layer) and the quartz substrate.
In this manner, a binary mask according to Comparative Example 1 was obtained.

Next, this binary mask was subjected to electron beam correction, and the etching rates of each layer in the electron beam correction were measured, and "R12 (R2/R1)" was 0.06, and the "side etching amount of the light-shielding layer" was 22 nm. In other words, the binary mask according to Comparative Example 1 is a binary mask in which "R12 (R2/R1)" is less than 0.5.
From the above results, it was confirmed that in the binary mask of Comparative Example 1, since "R12 (R2/R1)" is 0.06, excessive side etching occurs in the light-shielding layer during electron beam correction of the light-shielding film.

(Comparative Example 2)
A light-shielding layer made of tantalum and nitrogen was formed to a thickness of 45 nm on a quartz substrate using a DC sputtering device with one target. The target was tantalum, and the sputtering gas was argon and nitrogen. The composition of this light-shielding layer was analyzed by ESCA and found to be Ta:N=70:30 (atomic %).
Next, a low reflection layer made of tantalum and oxygen was formed on the light-shielding layer to a thickness of 5 nm using a DC sputtering device. The target was tantalum, and the sputtering gas was argon and oxygen. The composition of this low reflection layer was analyzed by ESCA and found to be Ta:O=35:65 (atomic % ratio).

Next, a hard mask film made of chromium and nitrogen was formed on the low reflection layer to a thickness of 5 nm using a DC sputtering device. Chromium was used as the target, and argon and nitrogen were used as the sputtering gas. The composition of this hard mask film was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio).
In this manner, a binary mask blank according to Comparative Example 2 was obtained.
Next, a negative chemically amplified electron beam resist was spin-coated onto this hard mask film to a thickness of 80 nm, and a pattern was written using an electron beam at a dose of 35 μC/ ^cm2. The resist was then heat-treated at 110° C. for 10 minutes and developed by paddle development for 90 seconds to form a resist pattern.
Next, the hard mask film was patterned using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 400 W, and the bias power to 10 W. Overetching was performed by 200%.

Next, the light-shielding film (light-shielding layer and low-reflection layer) was patterned using a dry etching device. _SF6 and helium were used as the etching gas, and the gas pressure was set to 4 mTorr, the ICP power to 200 W, and the bias power to 50 W. Overetching was performed by 30%.
Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and water.
Next, the hard mask film was removed using a dry etching device. Chlorine, oxygen, and helium were used as etching gas, and the gas pressure was set to 10 mTorr, the ICP power to 500 W, and the bias power to 10 W. Overetching was performed by 200%. During this process, no damage was caused to the lower light-shielding film (light-shielding layer and low-reflection layer) and the quartz substrate.
In this manner, a binary mask according to Comparative Example 2 was obtained.

Next, this binary mask was subjected to electron beam correction, and the etching rates of each layer in the electron beam correction were measured, resulting in "R12 (R2/R1)" of 0.37 and "amount of side etching of the light-shielding layer" of 9 nm. In other words, the binary mask according to Comparative Example 2 is a binary mask in which "R12 (R2/R1)" is less than 0.5.
From the above results, it was confirmed that in the binary mask of Comparative Example 2, since "R12 (R2/R1)" is 0.37, excessive side etching occurs in the light-shielding layer during electron beam correction of the light-shielding film.

The binary mask blank of the present invention and the binary mask produced using the same have been described above using the above examples, but the above examples are merely examples for implementing the present invention, and the present invention is not limited to these. Furthermore, modifications of these examples are within the scope of the present invention, and it is self-evident from the above description that various other embodiments are possible within the scope of the present invention.

Furthermore, for example, the present invention can have the following configuration.
(1)
A binary mask blank used for producing a binary mask applied to photolithography using an exposure light source having a wavelength of 200 nm or less,
A transparent substrate and a light-shielding film formed on the transparent substrate,
the light-shielding film includes a light-shielding layer having a light-shielding property against the exposure light, and a low-reflection layer formed on the light-shielding layer and reducing reflection of the exposure light,
A binary mask blank, characterized in that R12 is 0.5 or more, when the etching rate of the light-shielding layer in an electron beam correction device is R1, the etching rate of the low-reflective layer in an electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer and the low-reflective layer is R12.
(2)
The binary mask blank according to (1) above, wherein the low reflective layer contains tantalum and at least one element selected from the group consisting of nitrogen, oxygen, and carbon.
(3)
The binary mask blank according to the above (1) or (2), wherein the light-shielding layer contains silicon.
(4)
the light-shielding layer contains silicon and at least one selected from a transition metal, nitrogen, oxygen, and carbon;
the transition metal is molybdenum;
The binary mask blank according to any one of (1) to (3), wherein the low reflective layer contains tantalum.
(5)
The binary mask blank according to any one of (1) to (4), wherein the light-shielding film has an optical density of 2.0 or more with respect to exposure light having a wavelength of 200 nm or less.
(6)
The binary mask blank according to any one of (1) to (5) above, wherein the thickness of the light-shielding film is in the range of 30 nm to 60 nm.
(7)
Further comprising a hard mask film on the low reflective layer,
The binary mask blank according to any one of (1) to (6), wherein the hard mask film contains chromium and at least one selected from the group consisting of nitrogen, oxygen, and carbon.
(8)
A binary mask applied to photolithography using an exposure light source with a wavelength of 200 nm or less, on which a transfer pattern is formed, comprising:
A transparent substrate and a light-shielding film formed in a pattern on the transparent substrate,
the light-shielding film includes a light-shielding layer having a light-shielding property against the exposure light, and a low-reflection layer formed on the light-shielding layer and reducing reflection of the exposure light,
A binary mask characterized in that R12 is 0.5 or more when the etching rate of the light-shielding layer in an electron beam correction device is R1, the etching rate of the low-reflection layer in an electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer and the low-reflection layer is R12.
(9)
A method for manufacturing a binary mask according to the above (8), comprising the steps of:
forming a light-shielding film on the transparent substrate;
forming a resist pattern on the light-shielding film formed on the transparent substrate;
forming a pattern on the light-shielding film by fluorine-based etching after forming the resist pattern;
removing the resist pattern after forming a pattern on the light-shielding film;
and performing electron beam correction after removing the resist pattern.
(10)
A method for manufacturing a binary mask according to the above (8), comprising the steps of:
forming a light-shielding film on the transparent substrate;
forming a hard mask film on the light-shielding film;
forming a resist pattern on the hard mask film formed on the light-shielding film;
forming a pattern on the hard mask film by oxygen-containing chlorine-based etching after forming the resist pattern;
forming a pattern on the hard mask film, and then forming a pattern on the light-shielding film by fluorine-based etching;
forming a pattern on the light-shielding film, thereafter removing the resist pattern and removing the hard mask film;
and performing electron beam correction after removing the hard mask film.

In the present invention, the electron beam correction etching rate R1 of the light-shielding layer and the electron beam correction etching rate R2 of the low-reflective layer in the binary mask blank are selected within appropriate ranges, making it possible to provide a binary mask in which fine patterns are formed with high precision, suitable for the manufacture of logic devices of 28 nm or less, or memory devices of 30 nm or less.

10: Binary mask 11: Substrate transparent to the exposure wavelength
12: Light-shielding film 12a: Light-shielding film pattern 13: Light-shielding layer 14: Low-reflection layer 15: Hard mask film 16: Resist pattern 100: Binary mask blank

Claims (10)

A binary mask blank used for producing a binary mask applied to photolithography using an exposure light source having a wavelength of 200 nm or less,
A transparent substrate and a light-shielding film formed on the transparent substrate,
the light-shielding film includes a light-shielding layer having a light-shielding property against the exposure light, and a low-reflection layer formed on the light-shielding layer and reducing reflection of the exposure light,
A binary mask blank, characterized in that R12 is 0.5 or more, when the etching rate of the light-shielding layer in an electron beam correction device is R1, the etching rate of the low-reflective layer in an electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer and the low-reflective layer is R12. The binary mask blank according to claim 1, characterized in that the low-reflection layer contains tantalum and at least one element selected from nitrogen, oxygen, and carbon. The binary mask blank according to claim 2, characterized in that the light-shielding layer contains silicon. the light-shielding layer contains silicon and at least one selected from a transition metal, nitrogen, oxygen, and carbon;
the transition metal is molybdenum;
The binary mask blank of claim 3 , wherein the low reflective layer contains tantalum. The binary mask blank according to claim 4, characterized in that the light-shielding film has an optical density of 2.0 or more for exposure light with a wavelength of 200 nm or less. The binary mask blank according to claim 5, characterized in that the thickness of the light-shielding film is in the range of 30 nm to 60 nm. Further comprising a hard mask film on the low reflective layer,
7. The binary mask blank according to claim 6, wherein the hard mask film contains chromium and at least one element selected from the group consisting of nitrogen, oxygen, and carbon. A binary mask applied to photolithography using an exposure light source with a wavelength of 200 nm or less, on which a transfer pattern is formed,
A transparent substrate and a light-shielding film formed in a pattern on the transparent substrate,
the light-shielding film includes a light-shielding layer having a light-shielding property against the exposure light, and a low-reflection layer formed on the light-shielding layer and reducing reflection of the exposure light,
A binary mask characterized in that R12 is 0.5 or more when the etching rate of the light-shielding layer in an electron beam correction device is R1, the etching rate of the low-reflection layer in an electron beam correction device is R2, and the ratio (R2/R1) of the etching rates of the light-shielding layer and the low-reflection layer is R12. A method for manufacturing a binary mask according to claim 8, comprising the steps of:
forming a light-shielding film on the transparent substrate;
forming a resist pattern on the light-shielding film formed on the transparent substrate;
forming a pattern on the light-shielding film by fluorine-based etching after forming the resist pattern;
removing the resist pattern after forming a pattern on the light-shielding film;
and performing electron beam correction after removing the resist pattern. A method for manufacturing a binary mask according to claim 8, comprising the steps of:
forming a light-shielding film on the transparent substrate;
forming a hard mask film on the light-shielding film;
forming a resist pattern on the hard mask film formed on the light-shielding film;
forming a pattern on the hard mask film by oxygen-containing chlorine-based etching after forming the resist pattern;
forming a pattern on the hard mask film, and then forming a pattern on the light-shielding film by fluorine-based etching;
forming a pattern on the light-shielding film, thereafter removing the resist pattern and removing the hard mask film;
and performing electron beam correction after removing the hard mask film.

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