Reflection type mask blank, reflection type mask and production method of reflection type mask

Abstract

To provide a reflection type mask blank capable of forming a fine resist pattern without disappearance of the resist pattern in developing a resist film even when the pattern has a higher aspect ratio while capable of preventing a reduction in film thickness of a light absorption layer from occurring in removing a hard mask by etching, and also to provide a reflection type mask produced using the reflection type mask blank and a production method of the reflection type mask.SOLUTION: A reflection type mask blank 11 includes a substrate 1, a light absorption layer 2, a protective layer 3 and a hard mask 4 in this order. The protective layer 3 at least includes one or more elements selected from tantalum and silicon. The hard mask 4 at least includes one or more metal elements selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, stannum and indium.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reflective mask blank, a reflective mask manufactured using the reflective mask blank, and a method for manufacturing the reflective mask. [Background technology]

[0002] In the manufacturing process of semiconductor devices, the demand for miniaturization of photolithography technology is increasing along with the miniaturization of semiconductor devices. The minimum resolution dimension of the transfer pattern in photolithography depends heavily on the wavelength of the exposure light source, and the shorter the wavelength, the smaller the minimum resolution dimension can be. For this reason, the exposure light source is being replaced from the conventional ArF excimer laser light with a wavelength of 193 nm to light in the EUV (Extreme Ultra Violet) region with a wavelength of 13.5 nm.

[0003] Light in the EUV region is absorbed at a high rate by most substances, so a reflective photomask is used as a photomask for EUV exposure (EUV mask) (see, for example, Patent Document 1). Patent Document 1 discloses an EUV photomask obtained by forming a reflective layer made of a multilayer film in which molybdenum (Mo) layers and silicon (Si) layers are alternately laminated on a glass substrate, forming a light absorbing layer mainly composed of tantalum (Ta) thereon, and forming a pattern on this light absorbing layer.

[0004] Furthermore, as mentioned above, EUV lithography cannot use refractive optical systems that utilize the transmission of light, so the optical components of the exposure machine are reflective (mirrors) rather than lenses. This causes a problem in that the light incident on the reflective photomask (EUV mask) and the light reflected by the reflective photomask cannot be designed to be coaxial. Therefore, EUV lithography usually employs a method in which the optical axis is tilted 6 degrees from the vertical direction of the EUV mask, and the reflected light reflected at an angle of minus 6 degrees is guided to the semiconductor substrate.

[0005] As such, in EUV lithography, the optical axis is tilted via a mirror, which can cause a problem known as the "projection effect," in which the EUV light entering the EUV mask casts a shadow on the mask pattern (patterned light-absorbing layer) of the EUV mask. Current EUV mask blanks use a tantalum (Ta)-based film with a thickness of 60 to 90 nm as the light absorption layer. When performing pattern transfer exposure with an EUV mask fabricated using this mask blank, there is a risk of a decrease in contrast at the shadow edge of the mask pattern depending on the relationship between the incident direction of the EUV light and the orientation of the mask pattern. This can lead to problems such as increased line edge roughness of the transferred pattern on the semiconductor substrate and inability to form the line width to the targeted dimension, resulting in a deterioration of transfer performance.

[0006] Therefore, reflective photomask blanks are being considered in which the light absorption layer is changed from tantalum (Ta) to a material with high absorptivity (extinction coefficient) for EUV light, or a material with high absorptivity is added to tantalum (Ta). For example, Patent Document 2 describes a reflective photomask blank in which the light absorption layer is made of a material containing 50 atomic % (at %) or more of Ta as the main component and further containing at least one element selected from Te, Sb, Pt, I, Bi, Ir, Os, W, Re, Sn, In, Po, Fe, Au, Hg, Ga, and Al.

[0007] Furthermore, it is known that the EUV mask blank according to the conventional technology has a problem that when a resist film that functions as a mask for etching the EUV mask blank to form a pattern is developed, a fine resist pattern disappears and a fine pattern cannot be formed. Therefore, various methods for solving these problems have been studied. For example, there is a method of providing a hard mask between the resist film and the light absorbing layer in order to prevent the fine resist pattern from disappearing when the resist film is developed (see Patent Document 3). When a hard mask is provided between the resist film and the light absorbing layer, the photomask pattern is produced by obtaining a resist pattern, etching the hard mask using the resist pattern as a mask to form a hard mask pattern, and then etching the light absorbing layer using the hard mask pattern as a mask to obtain a light absorbing layer pattern.

[0008] In this way, by providing a hard mask between the resist film and the light absorbing layer, it is possible to reduce the thickness of the resist film and reduce the aspect ratio of the resist pattern (pattern height ÷ pattern width), thereby alleviating the surface tension when developing the resist film and preventing the disappearance of the fine resist pattern. In addition, when a hard mask is provided between the resist film and the light absorbing layer, the hard mask must function as a mask when etching the thin film. Therefore, the hard mask must be resistant to the etching conditions of the light absorbing layer. In addition, after the light absorbing layer is etched to form a pattern, the hard mask may be peeled off by etching, so the light absorbing layer must be resistant to the etching conditions when peeling off the hard mask. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2011-176162 A [Patent Document 2] JP 2007-273678 A [Patent Document 3] Patent No. 4989800 Summary of the Invention [Problem to be solved by the invention]

[0010] In order to obtain a photomask in which the fine resist pattern is not lost when the resist film is developed, it is effective to provide a hard mask mainly made of a material that is resistant to etching with a fluorine-based gas or an oxygen-free chlorine-based gas on a light absorbing layer that can be etched with a fluorine-based gas or an oxygen-free chlorine-based gas.

[0011] When a hard mask is provided on a light absorbing layer that can be etched with a fluorine-based gas, a hard mask containing chromium as a main component is often used. However, although hard masks containing chromium as a main component have sufficient resistance to etching with fluorine-based gases and oxygen-free chlorine-based gases, many of them do not have sufficient adhesion to resist patterns (resist films). As a result, the developer enters between the resist pattern and the hard mask during development, making the resist pattern prone to disappear. In particular, when the aspect ratio of the resist pattern becomes high, the resist pattern becomes even more prone to disappearance, which has been a problem. Furthermore, when the hard mask is peeled off by etching, the light absorbing layer does not have sufficient resistance to the etching used for peeling off the hard mask, which causes a problem that the film thickness of the light absorbing layer is reduced.

[0012] The present invention has been made based on the above circumstances, and has an object to provide a reflective mask blank which is capable of forming a fine resist pattern without causing the resist pattern to disappear during development of the resist film, not only in the case of a resist pattern with a low aspect ratio but also in the case of a resist pattern with a high aspect ratio, and which is capable of suppressing a decrease in the film thickness of the light absorbing layer which occurs when the hard mask is peeled off by etching, a reflective mask manufactured using the reflective mask blank, and a method for manufacturing the reflective mask. [Means for solving the problem]

[0013] The present invention has been made to solve the above-mentioned problems. A reflective mask blank according to one embodiment of the present invention is a reflective mask blank used for manufacturing a reflective mask for pattern transfer using extreme ultraviolet light as a light source, comprising: a substrate; a light absorbing layer formed on the substrate, having resistance to oxygen-containing chlorine-based gas etching and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; a protective layer formed on the light absorbing layer, having a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; and a hard mask formed on the protective layer, having resistance to fluorine-based gas or oxygen-free chlorine-based gas etching and capable of being etched by an oxygen-containing chlorine-based gas, wherein the protective layer contains at least one element selected from tantalum and silicon, and the hard mask contains at least one metal element selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium.

[0014] In addition, in a reflective mask blank according to one embodiment of the present invention, the hard mask may be composed of a plurality of layers, have an adhesion layer containing the metal element on at least the outermost surface, and have a lower layer, located closer to the substrate than the adhesion layer, that is more resistant to etching with a fluorine-based gas or an oxygen-free chlorine-based gas than the adhesion layer. In addition, in a reflective mask blank according to one embodiment of the present invention, the hard mask may be composed of a plurality of layers, have an adhesion layer containing the metal element on at least the outermost surface, and have a lower layer containing chromium on the substrate side of the adhesion layer.

[0015] In the reflective mask blank according to one aspect of the present invention, the adhesion layer may have a thickness in the range of 1 nm or more and 10 nm or less. In the reflective mask blank according to one aspect of the present invention, the lower layer may have a thickness in the range of 1 nm or more and 19 nm or less. In the reflective mask blank according to one aspect of the present invention, the hard mask may have a thickness in the range of 2 nm to 20 nm. In the reflective mask blank according to one aspect of the present invention, the protective layer may have a thickness in the range of 1 nm or more and 20 nm or less.

[0016] In the reflective mask blank according to one embodiment of the present invention, the light absorbing layer may contain at least one compound selected from a tin compound and an indium compound. In the reflective mask blank according to one embodiment of the present invention, the tin compound may contain tin and one or more elements selected from nitrogen, boron, oxygen, and carbon. In the reflective mask blank according to one embodiment of the present invention, the indium compound may contain indium and one or more elements selected from nitrogen, boron, oxygen, and carbon.

[0017] In addition, in the reflective mask blank according to one aspect of the present invention, a multilayer reflective film having a multilayer structure and reflecting extreme ultraviolet rays may be provided between the substrate and the light absorbing layer. Furthermore, in the reflective mask blank according to one embodiment of the present invention, a second protective layer containing at least one element selected from tantalum, silicon, and chromium may be provided between the multilayer reflective film and the light absorbing layer. In the reflective mask blank according to one embodiment of the present invention, the second protective layer may have a thickness in the range of 1 nm or more and 20 nm or less.

[0018] Moreover, a reflective mask according to one embodiment of the present invention is a reflective mask to which exposure light of extreme ultraviolet rays is applied to form a transfer pattern, the reflective mask comprising: a substrate; a light absorbing layer formed on the substrate, having resistance to oxygen-containing chlorine-based gas etching and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; a protective layer formed on the light absorbing layer, having a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; and a hard mask formed on the protective layer, having resistance to fluorine-based gas or oxygen-free chlorine-based gas etching and capable of being etched by an oxygen-containing chlorine-based gas, wherein the protective layer contains at least one element selected from tantalum and silicon, and the hard mask contains at least one metal element selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium.

[0019] Moreover, a manufacturing method of a reflective mask according to one aspect of the present invention is a manufacturing method of a reflective mask using the above-mentioned reflective mask blank, comprising the steps of: forming a resist pattern on the hard mask of the reflective mask blank; etching the hard mask with an oxygen-containing chlorine-based gas using the resist pattern as a mask to form a hard mask pattern; etching the protective layer and the light absorbing layer successively with a fluorine-based gas or an oxygen-free chlorine-based gas using the hard mask pattern as a mask to form a pattern consisting of the protective layer and the light absorbing layer; and peeling off the hard mask pattern by etching with an oxygen-containing chlorine-based gas. Effect of the Invention

[0020] According to one aspect of the present invention, it is possible to provide a reflective mask blank which is capable of forming a fine resist pattern without causing the resist pattern to disappear during development of the resist film, not only in the case of a resist pattern with a low aspect ratio but also in the case of a resist pattern with a high aspect ratio, and which is capable of suppressing a decrease in the film thickness of the light absorbing layer that occurs when the hard mask is peeled off by etching, a reflective mask manufactured using the reflective mask blank, and a method for manufacturing the reflective mask. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view showing a structure of a reflective mask blank according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic cross-sectional view showing a structure of a reflective mask blank according to a second embodiment of the present invention. [Diagram 3] 1 is a schematic cross-sectional view showing a structure of a reflective mask blank according to a third embodiment of the present invention. [Figure 4] FIG. 11 is a schematic cross-sectional view showing the structure of a reflective mask blank according to a fourth embodiment of the present invention. [Diagram 5] 1 is a schematic cross-sectional view showing a structure of a reflective mask according to a first embodiment of the present invention. [Figure 6] 5 is a schematic cross-sectional view showing the structure of a reflective mask according to a second embodiment of the present invention. [Figure 7] 5 is a schematic cross-sectional view showing the structure of a reflective mask according to a third embodiment of the present invention. [Figure 8] FIG. 11 is a schematic cross-sectional view showing the structure of a reflective mask according to a fourth embodiment of the present invention. [Figure 9] 1A to 1C are schematic cross-sectional views sequentially showing a manufacturing process of a reflective mask using a reflective mask blank according to a first embodiment of the present invention. [Figure 10] 5A to 5C are schematic cross-sectional views sequentially showing the manufacturing process of a reflective mask using a reflective mask blank according to a second embodiment of the present invention. [Figure 11]10A to 10C are schematic cross-sectional views sequentially showing the manufacturing process of a reflective mask using a reflective mask blank according to a third embodiment of the present invention. [Figure 12] 10A to 10C are schematic cross-sectional views sequentially showing the manufacturing process of a reflective mask using a reflective mask blank according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the configurations shown in the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. are different from the actual ones. In addition, the embodiments shown below are examples of configurations for embodying the present invention, and the present invention is not limited to the materials, shapes, structures, etc. of the components described below. In addition, various modifications can be made to the present invention within the technical scope defined by the claims.

[0023] (Configuration of reflective mask blank and reflective mask) 1 is a schematic cross-sectional view showing the structure of a reflective mask blank 11 according to a first embodiment of the present invention. As shown in FIG. 1, the reflective mask blank 11 according to the first embodiment of the present invention includes at least a substrate 1, a light absorbing layer 2 formed on the substrate 1, which has resistance to oxygen-containing chlorine-based gas etching and can be etched by a fluorine-based gas or an oxygen-free chlorine-based gas, a first protective layer (protective layer) 3 formed on the light absorbing layer 2, which has a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer 2 and can be etched by a fluorine-based gas or an oxygen-free chlorine-based gas, and a hard mask 4 formed on the first protective layer 3, which has resistance to fluorine-based gas or oxygen-free chlorine-based gas etching and can be etched by an oxygen-containing chlorine-based gas. Note that the hard mask 4 in the reflective mask blank 11 according to this embodiment is a single layer.

[0024] 2 is a schematic cross-sectional view showing the structure of a reflective mask blank 12 according to a second embodiment of the present invention. As shown in FIG. 2, the reflective mask blank 12 according to the second embodiment of the present invention comprises at least a substrate 1, a light absorbing layer 2 formed on the substrate 1, which has resistance to oxygen-containing chlorine-based gas etching and can be etched by a fluorine-based gas or an oxygen-free chlorine-based gas, a first protective layer (protective layer) 3 formed on the light absorbing layer 2, which has a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer 2 and can be etched by a fluorine-based gas or an oxygen-free chlorine-based gas, and a hard mask 4 formed on the first protective layer 3, which has resistance to fluorine-based gas or oxygen-free chlorine-based gas etching and can be etched by an oxygen-containing chlorine-based gas. In addition, in the reflective mask blank 12 according to this embodiment, the hard mask 4 comprises a lower layer 4a located on the first protective layer 3 side and an adhesive layer 4b formed on the lower layer 4a.

[0025] FIG. 3 is a schematic cross-sectional view showing the structure of a reflective mask blank 13 according to a third embodiment of the present invention. As shown in FIG. 3, the reflective mask blank 13 according to the third embodiment of the present invention at least comprises a substrate 1, a light absorbing layer 2 formed on the substrate 1, having resistance to oxygen-containing chlorine-based gas etching, and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas, a first protective layer (protective layer) 3 formed on the light absorbing layer 2, having a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer 2, and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas, and a hard mask 4 formed on the first protective layer 3, having resistance to fluorine-based gas or oxygen-free chlorine-based gas etching, and capable of being etched by an oxygen-containing chlorine-based gas. In the reflective mask blank 13 according to this embodiment, the hard mask 4 comprises a lower layer 4a located on the first protective layer 3 side, and an adhesive layer 4b formed on the lower layer 4a. In addition, the reflective mask blank 13 according to this embodiment comprises a second protective layer 7 on the surface of the light absorbing layer 2 on the substrate 1 side.

[0026] FIG. 4 is a schematic cross-sectional view showing the structure of a reflective mask blank 14 according to a fourth embodiment of the present invention. As shown in FIG. 4, the reflective mask blank 14 according to the fourth embodiment of the present invention comprises at least a substrate 1, a light absorbing layer 2 formed on the substrate 1, which has resistance to oxygen-containing chlorine-based gas etching and can be etched by a fluorine-based gas or an oxygen-free chlorine-based gas, a first protective layer (protective layer) 3 formed on the light absorbing layer 2, which has a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer 2 and can be etched by a fluorine-based gas or an oxygen-free chlorine-based gas, and a hard mask 4 formed on the first protective layer 3, which has resistance to fluorine-based gas or oxygen-free chlorine-based gas etching and can be etched by an oxygen-containing chlorine-based gas. In addition, the hard mask 4 in the reflective mask blank 14 according to this embodiment is a single layer. In addition, the reflective mask blank 14 according to this embodiment comprises a second protective layer 7 on the surface of the light absorbing layer 2 on the substrate 1 side. The reflective mask blanks 11 to 14 according to each of the above-mentioned embodiments may include a multilayer reflective film 5 between the substrate 1 and the light absorbing layer 2, or may include a capping layer 6 between the multilayer reflective film 5 and the light absorbing layer 2, as shown in FIGS. 1 to 4 .

[0027] Fig. 5 is a schematic cross-sectional view showing the structure of a reflective mask 21 according to a first embodiment of the present invention. The reflective mask 21 according to the first embodiment of the present invention shown in Fig. 5 is formed by patterning the hard mask 4, the first protective layer 3, and the light absorbing layer 2 of the reflective mask blank 11 according to the first embodiment of the present invention shown in Fig. 1. 6 is a schematic cross-sectional view showing the structure of a reflective mask 22 according to a second embodiment of the present invention. The reflective mask 22 according to the second embodiment of the present invention shown in Fig. 6 is formed by patterning the hard mask 4 (adhesive layer 4b, lower layer 4a), first protective layer 3 and light absorbing layer 2 of the reflective mask blank 12 according to the second embodiment of the present invention shown in Fig. 2.

[0028] 7 is a schematic cross-sectional view showing the structure of a reflective mask 23 according to a third embodiment of the present invention. The reflective mask 23 according to the third embodiment of the present invention shown in Fig. 7 is formed by patterning the hard mask 4 (adhesive layer 4b, lower layer 4a), first protective layer 3, light absorbing layer 2, and second protective layer 7 of the reflective mask blank 13 according to the third embodiment of the present invention shown in Fig. 3. 8 is a schematic cross-sectional view showing the structure of a reflective mask 24 according to a fourth embodiment of the present invention. The reflective mask 24 according to the fourth embodiment of the present invention shown in Fig. 8 is formed by patterning the hard mask 4, the first protective layer 3, the light absorbing layer 2, and the second protective layer 7 of the reflective mask blank 14 according to the fourth embodiment of the present invention shown in Fig. 4. Each layer will be described in detail below.

[0029] (substrate) For example, a flat Si substrate, a synthetic quartz substrate, etc. can be used for the substrate 1 according to the embodiment of the present invention. In addition, low thermal expansion glass containing titanium can be used for the substrate 1, but the present embodiment is not limited to these as long as the material has a small thermal expansion coefficient. A back conductive film (not shown) can be formed on the surface of the substrate 1 on which the multilayer reflective film 5 is not formed. The back conductive film is a film for fixing the reflective mask by utilizing the principle of an electrostatic chuck when the reflective mask is placed on an exposure machine.

[0030] (Light absorbing layer and light absorbing pattern layer) The light absorbing layer 2 according to the embodiment of the present invention is a layer formed on the substrate 1, and is a layer that absorbs EUV light, which is the exposure light. The light absorbing layer 2 is also a layer that forms a light absorbing pattern layer (transfer pattern) 2a, which is a fine pattern for transfer. That is, by removing a part of the light absorbing layer 2 of the reflective mask blanks 11 to 14, i.e., by patterning the light absorbing layer 2, the light absorbing patterns (light absorbing pattern layer 2a) of the reflective masks 21 to 24 shown in Figs. 5 to 8 are formed. More specifically, the light absorbing layer 2 is a thin film having a lower reflectance at a wavelength of 13.5 nm than the multilayer reflective film 5. The light absorbing layer 2 is, for example, a layer having a reflectance at a wavelength of 13.5 nm in the range of 0% or more and less than 6.5%, and preferably 0% or more and less than 2%. If the reflectance of the light absorbing layer 2 is within the above numerical range, the reflectance (reflection ratio) of the EUV light with respect to the multilayer reflective film 5 becomes sufficiently low, and high transfer performance can be imparted to the reflective masks 21-24 including the light absorbing layer 2.

[0031] The light absorbing layer 2 is a light absorbing layer that has resistance to etching with an oxygen-containing chlorine-based gas and can be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. Here, the above phrase "has resistance to oxygen-containing chlorine-based gas etching and can be etched with a fluorine-based gas or an oxygen-free chlorine-based gas" means that the ratio of the etching rate when the light-absorbing layer 2 is etched with a fluorine-based gas or an oxygen-free chlorine-based gas to the etching rate when the light-absorbing layer 2 is etched with an oxygen-containing chlorine-based gas (etching rate when the light-absorbing layer 2 is etched with a fluorine-based gas or an oxygen-free chlorine-based gas / etching rate when the light-absorbing layer 2 is etched with an oxygen-containing chlorine-based gas) is greater than 1 (1.1 or more).

[0032] The light absorbing layer 2 is, for example, a single layer film containing at least one compound selected from a tin compound and an indium compound, or a mixed film of these compounds, or a multilayer film. Specifically, the light absorbing layer 2 made of a tin compound is a single layer film containing tin and one or more elements selected from nitrogen, boron, oxygen, and carbon, or a multilayer film or a gradient film thereof. The light absorbing layer 2 made of an indium compound is a single layer film containing indium and one or more elements selected from nitrogen, boron, oxygen, and carbon, or a multilayer film or a gradient film thereof. Tin compounds and indium compounds have low reflectance to EUV light, and the light absorbing layer 2 can be thinned, so it is desirable for the light absorbing layer 2 to contain at least one of a tin compound and an indium compound.

[0033] The tin compound may contain tin in an element ratio of 5 atomic % to 95 atomic % in the entire tin compound, more preferably in the range of 15 atomic % to 75 atomic % in the entire tin compound, and even more preferably in the range of 25 atomic % to 55 atomic % in the entire tin compound. If the tin content is within the above numerical range, the light absorption is further improved. The indium compound may contain indium in an element ratio of 10 atomic % to 95 atomic % in the entire indium compound, more preferably in a range of 22 atomic % to 75 atomic % in the entire indium compound, and even more preferably in a range of 35 atomic % to 55 atomic % in the entire indium compound. If the indium content is within the above numerical range, the light absorption property is further improved.

[0034] The thickness of the light absorbing layer 2 is adjusted so that the reflectance to EUV light is less than 6.5%. The thickness of the light absorbing layer 2 is preferably, for example, in the range of 17 nm to 90 nm, particularly in the range of 25 nm to 75 nm. If the thickness of the light absorbing layer 2 is within the above numerical range, the reflectance to EUV light is sufficiently low, and high transfer performance can be imparted to the reflective mask 20 including the light absorbing layer 2.

[0035] (protective layer) The protective layer (first protective layer) 3 is a layer formed on the light absorbing layer 2, and is a layer for suppressing a decrease in the film thickness of the light absorbing layer 2 when the hard mask 4 is peeled off. The protective layer 3 is a layer that has a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer 2, and can be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. Specifically, the protective layer 3 is a single layer film containing at least one element selected from tantalum and silicon, or a multilayer film or gradient film thereof. The reason why at least one element selected from tantalum and silicon is added to the protective layer 3 will be explained below.

[0036] The light absorbing layer 2 containing tin or indium may be etched by the oxygen-containing chlorine-based gas etching used when the hard mask 4 is stripped off, which may result in a reduction in the film thickness (layer thickness). On the other hand, tantalum has high resistance to oxygen-containing chlorine-based gas etching and is difficult to etch. Silicon, like tantalum, also has high resistance to oxygen-containing chlorine-based gas etching and is difficult to etch. Therefore, in this embodiment, a material containing at least one or more elements selected from tantalum and silicon is used as the material constituting the protective layer 3 that protects the light absorbing layer 2, which makes it possible to suppress a decrease in the film thickness (layer thickness) of the light absorbing layer 2 when the hard mask 4 is peeled off.

[0037] The protective layer 3 may contain tantalum in an element ratio of 5 atomic % to 95 atomic % to 80 atomic %, more preferably 10 atomic % to 90 atomic %, and even more preferably 20 atomic % to 80 atomic %, of the entire protective layer 3. If the tantalum content is within the above range, the resistance to etching with an oxygen-containing chlorine-based gas is further increased. Furthermore, the protective layer 3 may contain silicon in an elemental ratio of 5 atomic % to 95 atomic % to less than 10 atomic % to less than 90 atomic %, and more preferably in a range of 20 atomic % to less than 80 atomic %, in the entire protective layer 3. If the silicon content is within the above numerical range, the resistance to etching with an oxygen-containing chlorine-based gas is further increased. The protective layer 3 may contain tantalum and silicon in an element ratio (total element ratio of tantalum and silicon) of 5 atomic % to 95 atomic % inclusive, more preferably 10 atomic % to 90 atomic % inclusive, and even more preferably 20 atomic % to 80 atomic % inclusive, of the entire protective layer 3. If the total content of tantalum and silicon is within the above numerical range, the resistance to etching with an oxygen-containing chlorine-based gas is further increased.

[0038] In order to ensure etching resistance against oxygen-containing chlorine-based gas etching, the thickness of the protective layer 3 is preferably in the range of 1 nm to 20 nm, more preferably in the range of 1 nm to 15 nm, and even more preferably in the range of 1 nm to 10 nm. More specifically, if the thickness of the protective layer 3 is 1 nm or more, it can function as a layer having etching resistance against oxygen-containing chlorine-based gas etching. If the thickness of the protective layer 3 is 20 nm or less, the projection effect can be reduced.

[0039] (Hard Mask) The hard mask 4 is a layer formed on the protective layer 3, and is a layer (film) for enhancing adhesion with the resist pattern. The hard mask 4 is a single layer film containing at least one metal element selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium, or a multilayer film or gradient film thereof. The above-mentioned metal elements have a lower surface free energy than chromium, so a hard mask containing these metal elements has higher adhesion to a resist pattern than a hard mask that does not contain the above-mentioned metal elements and contains chromium as a main component on the outermost surface located farther from the substrate 1. Furthermore, if the hard mask 4 contains the above-mentioned metal element, etching with an oxygen-containing chlorine-based gas becomes possible.

[0040] The film thickness of the hard mask 4 is preferably in the range of 2 nm to 20 nm, more preferably in the range of 4 nm to 15 nm, in order to suppress damage to the resist pattern during hard mask etching and to provide (ensure) etching resistance to fluorine-based gas or oxygen-free chlorine-based gas etching. In this manner, the hard mask 4 according to this embodiment is resistant to etching with a fluorine-based gas or an oxygen-free chlorine-based gas, and can be etched with an oxygen-containing chlorine-based gas.

[0041] The hard mask 4 may contain one or more metal elements selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium in an element ratio of the entire hard mask in a range of 10 atomic % to 95 atomic % or less, more preferably in a range of 20 atomic % to 70 atomic % or less, and even more preferably in a range of 30 atomic % to 60 atomic % or less. If the content of the above-mentioned metal elements is within the above numerical range, the adhesion between the hard mask 4 and the resist pattern can be improved. In particular, among the above-mentioned metal elements, hafnium and tin are preferable as metal elements to be added to the hard mask 4 because they have particularly low surface free energy compared to other elements.

[0042] In addition, when using a metal element having a relatively low etching resistance against fluorine-based gas or oxygen-free chlorine-based gas etching among the above-mentioned metal elements, it is preferable to form the hard mask into a multi-layer film. For example, the hard mask 4 may be composed of an adhesion layer 4b, which is a layer containing the above-mentioned metal element and is located farther from the substrate 1, and a lower layer 4a, which is a layer having a higher resistance against fluorine-based gas or oxygen-free chlorine-based gas etching than the adhesion layer 4b and is located closer to the substrate 1 than the adhesion layer 4b. In particular, it is preferable that the lower layer 4a contains chromium, which has excellent etching resistance against fluorine-based gas or oxygen-free chlorine-based gas etching. The chromium-containing lower layer 4a is, for example, a single layer film containing chromium and one or more elements selected from nitrogen, oxygen, and carbon, or a multilayer film or gradient film thereof.

[0043] The above-mentioned "lower layer 4a having higher resistance to fluorine-based gas or oxygen-free chlorine-based gas etching than the adhesion layer 4b" means that the ratio of the etching rate of the adhesion layer 4b when etched with a fluorine-based gas or oxygen-free chlorine-based gas to the etching rate of the lower layer 4a when etched with a fluorine-based gas or oxygen-free chlorine-based gas (etching rate of the lower layer 4a when etched with a fluorine-based gas or oxygen-free chlorine-based gas / etching rate of the adhesion layer 4b when etched with a fluorine-based gas or oxygen-free chlorine-based gas) is less than 1.

[0044] The lower layer 4a may contain chromium in an elemental ratio of 10 to 95 atomic % inclusive, more preferably 40 to 95 atomic % inclusive, and even more preferably 50 to 95 atomic % inclusive. If the chromium content is within the above numerical range, the etching resistance against fluorine-based gas or oxygen-free chlorine-based gas etching is further improved.

[0045] Thus, the hard mask 4 may be composed of a plurality of layers, and may have an adhesive layer 4b containing the above-mentioned metal element at least on the outermost surface, and a lower layer 4a having higher resistance to fluorine-based gas or oxygen-free chlorine-based gas etching than the adhesive layer 4b, on the substrate 1 side of the adhesive layer 4b. Here, the adhesive layer 4b of the hard mask 4 may contain one or more metal elements selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium in an element ratio of the entire adhesive layer 4b in a range of 10 atomic % to 95 atomic % or less, more preferably in a range of 20 atomic % to 70 atomic % or less, and even more preferably in a range of 30 atomic % to 60 atomic % or less. If the content of the above-mentioned metal element is within the above numerical range, the adhesion between the hard mask 4 (adhesion layer 4b) and the resist pattern is further improved. In particular, among the above-mentioned metal elements, hafnium and tin are preferable as metal elements to be added to the adhesive layer 4b because they have particularly low surface free energy compared to other elements.

[0046] The thickness of the adhesion layer 4b is preferably in the range of 1 nm to 10 nm, particularly in the range of 2 nm to 5 nm. If the thickness of the adhesion layer 4b is within the above numerical range, the adhesion between the hard mask 4 (adhesion layer 4b) and the resist pattern can be sufficiently increased. The thickness of the lower layer 4a is preferably in the range of 1 nm to 19 nm, particularly preferably in the range of 2 nm to 10 nm. If the thickness of the lower layer 4a is in the above range, the etching resistance against etching with a fluorine-based gas or an oxygen-free chlorine-based gas can be sufficiently increased.

[0047] (Multilayer reflective film) The multilayer reflective film 5 is a film having a multilayer structure located between the substrate 1 and the light absorbing layer 2, and is a film that reflects light with a wavelength of 13.5 nm. The multilayer reflective film 5 reflects EUV light such as light with a wavelength of 13.5 nm, and is made of a combination of materials with significantly different refractive indices for EUV light. For example, it can be formed by repeatedly stacking layers of combinations of molybdenum and silicon, or molybdenum and beryllium, for example, for about 40 periods. The multilayer reflective film 5 is, for example, a thin film capable of reflecting 50% or more of light having a wavelength of 13.5 nm, and is preferably a thin film capable of reflecting 60% or more of the light.

[0048] (capping layer) The capping layer 6 is a layer located between the multilayer reflective film 5 and the light absorbing layer 2, and functions as an etching stopper that prevents damage to the multilayer reflective film 5 when the light absorbing pattern layer 2a is formed by etching the light absorbing layer 2. Note that depending on the material of the multilayer reflective film 5 and the etching conditions, the capping layer 6 may not be provided. The capping layer 6 may be made of any material that is resistant to the dry etching performed when forming the pattern of the light absorbing layer 2. Therefore, for example, the material of the capping layer 6 may be ruthenium (Ru).

[0049] (Second protective layer) The second protective layer 7 is located between the capping layer 6 and the light absorbing layer 2, and is a layer for suppressing a decrease in the thickness of the capping layer 6. The second protective layer 7 is, for example, a single layer film containing at least one element selected from tantalum, silicon, and chromium, or a multilayer film or gradient film thereof. The thickness of the second protective layer 7 is preferably in the range of 1 nm to 20 nm, particularly in the range of 5 nm to 15 nm.

[0050] The light absorbing layer 2, the first protective layer 3, the hard mask 4 (the lower layer 4a and the adhesive layer 4b), the multilayer reflective film 5, the capping layer 6, and the second protective layer 7 can all be formed by known methods. A preferred method for obtaining a film with excellent uniformity most easily is a sputtering film formation method, but the present embodiment does not need to be limited to the sputtering film formation method.

[0051] The target and the sputtering gas are selected according to the film composition. For example, a method for forming a film containing silicon can be exemplified by a method in which a silicon-containing target is used and reactive sputtering is performed in a gas consisting of only an inert gas such as argon gas, in a gas consisting of only a reactive gas such as oxygen, or in 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 content of oxygen, etc. is to be changed in the thickness direction of the film. When the content of oxygen, etc. is to be changed in the thickness direction of the film, the power applied to the target, the distance between the target and the substrate, or the pressure in the film formation chamber may be adjusted. In addition, for example, in the formation of a film containing silicon and a metal, a target with an adjusted content ratio of silicon and metal may be used alone as the target, or multiple targets may be appropriately selected from a silicon target, a metal target, and a target consisting of silicon and a metal. The reflective masks 21 to 24 are obtained by patterning or removing each of the films of the reflective mask blanks 11 to 14 of this embodiment described above into a desired pattern.

[0052] (Reflective mask blank and manufacturing method of reflective mask) Preferred embodiments of the method for producing the reflective mask blanks 11 to 14 and the reflective masks 21 to 24 of this embodiment will be described below. FIG. 9 is a schematic cross-sectional view showing the steps of manufacturing a reflective mask 21 using the reflective mask blank 11 shown in FIG. 5. FIG. 9(a) shows a process of applying a resist film onto a hard mask 4 constituting the reflective mask blank 11, drawing, and then performing a development process to form a resist pattern 8. FIG. 9(b) shows a process of patterning the hard mask 4 by oxygen-containing chlorine-based gas etching along the resist pattern 8. FIG. 9(c) shows a process of peeling and removing the remaining resist pattern 8, followed by cleaning. FIG. 9(d) shows a process of successively patterning the first protective layer 3 and the light absorbing layer 2 by fluorine-based gas etching or oxygen-free chlorine-based gas etching along the pattern of the hard mask 4. In this way, the reflective mask 21 according to this embodiment is manufactured. After successive patterning of the first protective layer 3 and the light absorbing layer 2, a part of the pattern of the hard mask 4 may be peeled off (removed) by oxygen-containing chlorine-based gas etching.

[0053] FIG. 10 is a schematic cross-sectional view showing the steps of manufacturing a reflective mask 22 using the reflective mask blank 12 shown in FIG. 6. FIG. 10(a) shows a process of applying a resist film onto a hard mask 4 constituting the reflective mask blank 12, drawing the resist film, and then performing a development process to form a resist pattern 8. FIG. 10(b) shows a process of patterning the hard mask 4 by oxygen-containing chlorine-based gas etching along the resist pattern 8. FIG. 10(c) shows a process of peeling off and removing the remaining resist pattern 8, followed by cleaning. FIG. 10(d) shows a process of successively patterning the first protective layer 3 and the light absorbing layer 2 by fluorine-based gas etching or oxygen-free chlorine-based gas etching along the pattern of the hard mask 4 composed of the adhesive layer 4b and the lower layer 4a. In this way, the reflective mask 22 according to this embodiment is manufactured. After successive patterning of the first protective layer 3 and the light absorbing layer 2, the adhesive layer 4b of the hard mask 4 may be peeled off by oxygen-containing chlorine-based gas etching.

[0054] FIG. 11 is a schematic cross-sectional view showing the steps of manufacturing a reflective mask 23 using the reflective mask blank 13 shown in FIG. 7. FIG. 11(a) shows a process of applying a resist film onto a hard mask 4 constituting the reflective mask blank 13, drawing the resist film, and then performing a development process to form a resist pattern 8. FIG. 11(b) shows a process of patterning the hard mask 4 by oxygen-containing chlorine-based gas etching along the resist pattern 8. FIG. 11(c) shows a process of peeling off and removing the remaining resist pattern 8, followed by cleaning. FIG. 11(d) shows a process of successively patterning the first protective layer 3 and the light absorbing layer 2 by fluorine-based gas etching or oxygen-free chlorine-based gas etching along the pattern of the hard mask 4 composed of the adhesive layer 4b and the lower layer 4a. After successive patterning of the first protective layer 3 and the light absorbing layer 2, the adhesive layer 4b of the hard mask 4 may be peeled off by oxygen-containing chlorine-based gas etching. The second protective layer 7 may be removed when peeling off the adhesive layer 4b of the hard mask 4. In this manner, the reflective mask 23 according to this embodiment is manufactured. 11(d) shows a form (reflective mask 23a) in which the second protective layer 7 is removed when the adhesion layer 4b of the hard mask 4 is peeled off, and FIG 11(e) shows a form (reflective mask 23b) in which the second protective layer 7 is not removed when the adhesion layer 4b of the hard mask 4 is peeled off.

[0055] FIG. 12 is a schematic cross-sectional view showing the steps of manufacturing a reflective mask 24 using the reflective mask blank 14 shown in FIG. 8. FIG. 12(a) shows a process of applying a resist film onto a hard mask 4 constituting the reflective mask blank 14, drawing the resist film, and then performing a development process to form a resist pattern 8. FIG. 12(b) shows a process of patterning the hard mask 4 by oxygen-containing chlorine-based gas etching along the resist pattern 8. FIG. 12(c) shows a process of peeling off and removing the remaining resist pattern 8, followed by cleaning. FIG. 12(d) shows a process of successively patterning the first protective layer 3 and the light absorbing layer 2 by fluorine-based gas etching or oxygen-free chlorine-based gas etching along the pattern of the hard mask 4. After successive patterning of the first protective layer 3 and the light absorbing layer 2, a part of the pattern of the hard mask 4 may be peeled off by oxygen-containing chlorine-based gas etching. Also, the second protective layer 7 may be removed when a part of the hard mask 4 is peeled off. In this way, the reflective mask 24 according to this embodiment is manufactured. 12(d) shows a form (reflective mask 24a) in which the second protective layer 7 is removed when part of the hard mask 4 is peeled off, and FIG 12(e) shows a form (reflective mask 24b) in which the second protective layer 7 is not removed when part of the hard mask 4 is peeled off.

[0056] As described above, the manufacturing method of reflective masks 21-24 using reflective mask blanks 11-14 according to this embodiment includes the steps of forming a resist pattern 8 on a hard mask 4 of the reflective mask blanks 11-14, etching the hard mask 4 with an oxygen-containing chlorine-based gas using the resist pattern 8 as a mask to form a hard mask pattern, etching the first protective layer 3 and the light absorbing layer 2 successively with a fluorine-based gas or an oxygen-free chlorine-based gas using the hard mask pattern as a mask to form a pattern consisting of the first protective layer 3 and the light absorbing layer 2, and peeling off the hard mask pattern by etching with the oxygen-containing chlorine-based gas.

[0057] In each process of FIG. 9(a), FIG. 10(a), FIG. 11(a), and FIG. 12(a), either a positive resist or a negative resist can be used as the material of the resist film, but it is preferable to use a chemically amplified resist for electron beam writing, which enables the formation of a high-precision pattern. The thickness of the resist film is, for example, within the range of 50 nm to 200 nm. In addition, in order to prevent the resist pattern from collapsing, a thickness of 150 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 10 μC / cm. 2 More than 200μC / cm 2 After this drawing, a heat treatment and a development treatment are carried out to obtain a resist pattern 8.

[0058] 9(b), 10(b), 11(b), and 12(b), the conditions of the oxygen-containing chlorine-based gas etching for patterning the hard mask 4 composed of only the adhesive layer 4b, and the conditions of the oxygen-containing chlorine-based gas etching for successively patterning the hard mask 4 composed of the adhesive layer 4b and the lower layer 4a may be the same as the known conditions that have been used conventionally for removing chromium compound films. The conditions of the oxygen-containing chlorine-based gas etching for patterning the hard mask 4 may be, for example, a gas containing chlorine gas and oxygen gas, or may be a mixture of chlorine gas, oxygen gas, and an inert gas such as nitrogen gas or helium gas as necessary. It should be noted that the first protective layer 3 and the light absorbing layer 2 are resistant to etching with an oxygen-containing chlorine-based gas, and therefore are left without being removed or patterned in this process.

[0059] In addition, in each of the steps of Figures 9(c), 10(c), 11(c), and 12(c), the resist pattern 8 can be stripped off by etching, but is generally stripped off by wet stripping using a stripping liquid. In each of the steps of FIG. 9(d), FIG. 10(d), FIG. 11(d), and FIG. 12(d), the conditions of the fluorine-based gas etching for successively patterning the first protective layer 3 and the light absorbing layer 2 may be the same as the known conditions conventionally used for etching silicon compounds, and the fluorine-based gas may be CF 4 Or C 2 F 6 or Sci-Fi 6 is generally used, and may be mixed with an inert gas such as nitrogen gas or helium gas as required.

[0060] The conditions for the oxygen-free chlorine-based gas etching for successively patterning the first protective layer 3 and the light absorbing layer 2 may be the same as those known to have been used in the past when etching tantalum compounds, and may be, for example, chlorine gas, or a mixture of chlorine gas and an inert gas such as nitrogen gas or helium gas as necessary. Incidentally, since the capping layer 6 and the multilayer reflective film 5 are resistant to fluorine-based gas etching or oxygen-free chlorine-based gas etching, they are left without being removed or patterned in this process.

[0061] In each of the steps of FIG. 9(d), FIG. 10(d), FIG. 11(d), and FIG. 12(d), the conditions for the oxygen-containing chlorine-based gas etching to peel off a part of the hard mask 4 composed only of the adhesion layer 4b, or to peel off the adhesion layer 4b in the hard mask 4 composed of the adhesion layer 4b and the lower layer 4a, may be, for example, oxygen gas, or may be a mixture of oxygen gas and an inert gas such as nitrogen gas or helium gas as necessary.

[0062] [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.

[0063] Example 1 A multilayer reflective film was formed with a thickness of 280 nm on a LTEM (Low Thermal Expansion Material: for example, a low thermal expansion glass substrate), which is a substrate with small thermal expansion due to exposure, by using a DC sputtering device. The targets used were molybdenum for the molybdenum layer and silicon for the silicon layer, and argon was used as the sputtering gas. When the composition of this multilayer reflective film was analyzed by ESCA, the molybdenum layer had Mo=100 (atomic %) and the silicon layer had Si=100 (atomic %). The thickness of the molybdenum layer was 3 nm, and the silicon layer had 4 nm.

[0064] Next, a capping layer made of ruthenium was formed on the multilayer reflective film to a thickness of 3.5 nm using a DC sputtering device. The target was ruthenium, and the sputtering gas was argon. The composition of the capping layer was analyzed by ESCA, and it was found that Ru=100 (atomic %). Next, a light absorbing layer made of tin and oxygen was formed on the capping layer to a thickness of 30 nm using a DC sputtering device. The target was tin oxide, and the sputtering gas was argon and oxygen. The composition of this light absorbing layer was analyzed by ESCA and found to be Sn:O=38:62 (atomic %).

[0065] Next, a first protective layer (protective layer) made of tantalum and oxygen was formed on the light absorbing layer with a thickness of 3 nm using a DC sputtering device. The target used was tantalum, and the sputtering gas was argon and oxygen. The composition of this first protective layer (protective layer) was analyzed by ESCA and found to be Ta:O=30:70 (atomic %). Next, a hard mask (adhesion layer only) consisting of hafnium and nitrogen was deposited on the first protective layer (protection layer) with a thickness of 5 nm using an RF sputtering device. Hafnium nitride was used as the target, and argon was used as the sputtering gas. The composition of this hard mask (adhesion layer only) was analyzed by ESCA and found to be Hf:N=50:50 (atomic % ratio).

[0066] In this way, a reflective mask blank of Example 1 was obtained in which a multilayer reflective film made of molybdenum and silicon, a capping layer made of ruthenium, a light absorbing layer made of tin and oxygen, a first protective layer (protective layer) made of tantalum and oxygen, and a hard mask (only an adhesive layer) made of hafnium and nitrogen were laminated in this order on a substrate with small thermal expansion due to exposure. The multilayer reflective film thus formed was a film having a multilayer structure that reflects light with a wavelength of 13.5 nm. The light absorbing layer thus formed was a film that absorbs light with a wavelength of 13.5 nm, had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The first protective layer (protective layer) thus formed was a film that had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The hard mask thus formed (only an adhesive layer) was a layer that had high resistance to fluorine-based gas or oxygen-free chlorine-based gas etching.

[0067] Next, a positive chemically amplified electron beam resist was spin-coated on this hard mask (only the adhesion layer) to a thickness of 100 nm, and the pattern was formed with a dose of 35 μC / cm 2 The resist was patterned by electron beam drawing at 800 .ANG., heat-treated at 110.degree. C. for 10 minutes, and developed by paddle development for 90 seconds to form a resist pattern. The resolution limit of the resist pattern of the positive chemically amplified electron beam resist used in Example 1 was 45 nm, and the aspect ratio at the resolution limit when the resist film thickness after development was 97 nm was 2.2.

[0068] Next, a hard mask (only the adhesive layer) was patterned on the reflective mask blank of Example 1 using an etching device to obtain a hard mask pattern. Chlorine, oxygen, and helium were used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed at 100%. At this time, there was no damage to the first protective layer (protective layer). Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and hydrogen peroxide. Next, the first protective layer (protective layer) and the light absorbing layer were patterned using an etching device to obtain a light absorbing pattern layer. Chlorine was used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed by 50%. At this time, the damage amount of the hard mask was 1 nm, and a part of the hard mask was lost, but there was no damage to the first protective layer (protective layer) and the light absorbing layer.

[0069] Next, the hard mask was removed using an etching device. Chlorine, oxygen, and helium were used as the 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 50%. At this time, the damage amount of the first protective layer (protective layer) was 1 nm, the damage amount of the light absorption layer was 0 nm, and the damage amount of the capping layer was 1 nm. In this manner, the reflective mask of Example 1 was obtained. In this way, a reflective mask of Example 1 was obtained, which comprises a reflective region formed by stacking a substrate having small thermal expansion due to exposure, a multilayer reflective film, and a capping layer, and an absorbing region formed by stacking a substrate having small thermal expansion due to exposure, a multilayer reflective film, a capping layer, and an absorbing film.

[0070] Example 2 A multilayer reflective film was formed with a thickness of 280 nm on an LTEM substrate with small thermal expansion due to exposure using a DC sputtering device, with 40 pairs of molybdenum layers and silicon layers stacked together. The targets used were molybdenum for the molybdenum layers and silicon for the silicon layers, and argon was used as the sputtering gas. Analysis of the composition of this multilayer reflective film by ESCA revealed that the molybdenum layers had Mo=100 (atomic %) and the silicon layers had Si=100 (atomic %). The thickness of the molybdenum layers was 3 nm, and the thickness of the silicon layers was 4 nm.

[0071] Next, a capping layer made of ruthenium was formed on the multilayer reflective film to a thickness of 3.5 nm using a DC sputtering device. The target was ruthenium, and the sputtering gas was argon. The composition of the capping layer was analyzed by ESCA, and it was found that Ru=100 (atomic %). Next, a light absorbing layer made of tin and oxygen was formed on the capping layer to a thickness of 30 nm using a DC sputtering device. The target was tin oxide, and the sputtering gas was argon and oxygen. The composition of this light absorbing layer was analyzed by ESCA and found to be Sn:O=38:62 (atomic %). Next, a first protective layer (protective layer) made of tantalum and oxygen was formed on the light absorbing layer with a thickness of 3 nm using a DC sputtering device. The target used was tantalum, and the sputtering gas was argon and oxygen. The composition of this first protective layer (protective layer) was analyzed by ESCA and found to be Ta:O=30:70 (atomic %).

[0072] Next, a hard mask lower layer made of chromium and nitrogen was deposited on the first protective layer (protective layer) with 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 the hard mask lower layer was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio). Next, a 2 nm thick adhesion layer of tin and oxygen was formed on the lower layer of the hard mask using a DC sputtering device. Tin oxide was used as the target, and argon and oxygen were used as the sputtering gas. The composition of the adhesion layer of the hard mask was analyzed by ESCA and found to be Sn:O=38:62 (atomic % ratio).

[0073] In this way, a reflective mask blank of Example 2 was obtained, in which a multilayer reflective film made of molybdenum and silicon, a capping layer made of ruthenium, a light absorbing layer made of tin and oxygen, a first protective layer (protective layer) made of tantalum and oxygen, a lower layer of a hard mask made of chromium and nitrogen, and an adhesive layer of a hard mask made of tin and oxygen were laminated in this order on a substrate with small thermal expansion due to exposure. The multilayer reflective film thus formed was a film having a multilayer structure that reflects light with a wavelength of 13.5 nm. The light absorbing layer thus formed was a film that absorbs light with a wavelength of 13.5 nm, had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The first protective layer (protective layer) thus formed was a film that had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The hard mask (lower layer, adhesive layer) thus formed was a layer that had high resistance to fluorine-based gas or oxygen-free chlorine-based gas etching.

[0074] Next, a positive chemically amplified electron beam resist was spin-coated on the adhesion layer of this hard mask to a thickness of 100 nm, and the pattern was formed with a dose of 35 μC / cm 2The resist was patterned by electron beam drawing at 800 .ANG., heat-treated at 110.degree. C. for 10 minutes, and developed by paddle development for 90 seconds to form a resist pattern. The resolution limit of the resist pattern of the positive chemically amplified electron beam resist used in Example 2 was 43 nm, and the aspect ratio at the resolution limit when the resist film thickness after development was 97 nm was 2.3.

[0075] Next, a hard mask (lower layer, adhesive layer) was patterned on the reflective mask blank of Example 2 using an etching device to obtain a hard mask pattern. Chlorine, oxygen, and helium were used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed at 100%. At this time, there was no damage to the first protective layer (protective layer). Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and hydrogen peroxide.

[0076] Next, the first protective layer (protective layer) and the light absorbing layer were patterned using an etching device to obtain a light absorbing pattern layer. Chlorine was used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed by 50%. At this time, the damage amount of the hard mask (lower layer, adhesive layer) was 3 nm, and part of the hard mask was lost, but there was no damage to the first protective layer (protective layer) and the light absorbing layer.

[0077] Next, the hard mask (lower layer, adhesive layer) was removed using an 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 50%. At this time, the damage amount of the first protective layer (protective layer) was 1 nm, the damage amount of the light absorption layer was 0 nm, and the damage amount of the capping layer was 1 nm. In this manner, the reflective mask of Example 2 was obtained.

[0078] Example 3 A multilayer reflective film was formed with a thickness of 280 nm on an LTEM substrate with small thermal expansion due to exposure using a DC sputtering device, with 40 pairs of molybdenum layers and silicon layers stacked together. The targets used were molybdenum for the molybdenum layers and silicon for the silicon layers, and argon was used as the sputtering gas. Analysis of the composition of this multilayer reflective film by ESCA revealed that the molybdenum layers had Mo=100 (atomic %) and the silicon layers had Si=100 (atomic %). The thickness of the molybdenum layers was 3 nm, and the thickness of the silicon layers was 4 nm.

[0079] Next, a capping layer made of ruthenium was formed on the multilayer reflective film to a thickness of 3.5 nm using a DC sputtering device. The target was ruthenium, and the sputtering gas was argon. The composition of the capping layer was analyzed by ESCA, and it was found that Ru=100 (atomic %). Next, a second protective layer made of chromium and nitrogen was deposited on the capping layer to a thickness of 3 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 second protective layer was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio).

[0080] Next, a light absorbing layer made of tin and oxygen was formed on the second protective layer to a thickness of 30 nm using a DC sputtering device. The target was tin oxide, and the sputtering gas was argon and oxygen. The composition of this light absorbing layer was analyzed by ESCA and found to be Sn:O=38:62 (atomic % ratio). Next, a first protective layer (protective layer) made of silicon and oxygen was deposited on the light absorbing layer with a thickness of 3 nm using a DC sputtering device. Silicon was used as the target, and argon and oxygen were used as the sputtering gas. The composition of this first protective layer (protective layer) was analyzed by ESCA and found to be Si:O=33:67 (atomic % ratio).

[0081] Next, a hard mask lower layer made of chromium and nitrogen was deposited on the first protective layer (protective layer) with 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 the hard mask lower layer was analyzed by ESCA and found to be Cr:N=90:10 (atomic % ratio). Next, a 2 nm thick adhesion layer of tin and oxygen was formed on the lower layer of the hard mask using a DC sputtering device. Tin oxide was used as the target, and argon and oxygen were used as the sputtering gas. The composition of the adhesion layer of the hard mask was analyzed by ESCA and found to be Sn:O=38:62 (atomic % ratio).

[0082] In this way, a reflective mask blank of Example 3 was obtained, in which a multilayer reflective film made of molybdenum and silicon, a capping layer made of ruthenium, a second protective layer made of chromium and nitrogen, a light absorbing layer made of tin and oxygen, a first protective layer (protective layer) made of silicon and oxygen, a lower layer of a hard mask made of chromium and nitrogen, and an adhesive layer of a hard mask made of tin and oxygen were laminated in this order on a substrate with small thermal expansion due to exposure. The multilayer reflective film thus formed was a film having a multilayer structure that reflects light with a wavelength of 13.5 nm. The light absorbing layer thus formed was a film that absorbs light with a wavelength of 13.5 nm, had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The first protective layer (protective layer) thus formed was a film that had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. Moreover, the hard mask (lower layer, adhesive layer) thus formed was a layer that had high resistance to etching with a fluorine-based gas or an oxygen-free chlorine-based gas.

[0083] Next, a positive chemically amplified electron beam resist was spin-coated on the adhesion layer of this hard mask to a thickness of 100 nm, and the pattern was formed with a dose of 35 μC / cm 2The resist was patterned by electron beam drawing at 800 .ANG., heat-treated at 110.degree. C. for 10 minutes, and developed by paddle development for 90 seconds to form a resist pattern. The resolution limit of the resist pattern of the positive chemically amplified electron beam resist used in Example 3 was 43 nm, and the aspect ratio at the resolution limit when the resist film thickness after development was 97 nm was 2.3.

[0084] Next, a hard mask (lower layer, adhesive layer) was patterned on the reflective mask blank of Example 3 using an etching device to obtain a hard mask pattern. Chlorine, oxygen, and helium were used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed at 100%. At this time, there was no damage to the first protective layer (protective layer). Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and hydrogen peroxide.

[0085] Next, the first protective layer (protective layer) and the light absorbing layer were patterned using an etching device to obtain a light absorbing pattern layer. The etching gas was fluorine (CF 4 ) and oxygen were used, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed by 50%. During this process, the damage to the hard mask (lower layer, adhesion layer) was 3 nm, and part of the hard mask was lost, but there was no damage to the first protective layer (protective layer) or the light absorption layer.

[0086] Next, the hard mask (lower layer, adhesive layer) was removed using an 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 50%. At this time, the damage amount of the first protective layer (protective layer) was 1 nm, the damage amount of the light absorption layer was 0 nm, the damage amount of the second protective layer was 3 nm, and the damage amount of the capping layer was 0 nm. That is, in the reflective mask of Example 3, the second protective layer was removed and did not remain. In this way, the reflective mask of Example 3 was obtained.

[0087] Example 4 A multilayer reflective film was formed with a thickness of 280 nm on an LTEM substrate with small thermal expansion due to exposure using a DC sputtering device, with 40 pairs of molybdenum layers and silicon layers stacked together. The targets used were molybdenum for the molybdenum layers and silicon for the silicon layers, and argon was used as the sputtering gas. Analysis of the composition of this multilayer reflective film by ESCA revealed that the molybdenum layers had Mo=100 (atomic %) and the silicon layers had Si=100 (atomic %). The thickness of the molybdenum layers was 3 nm, and the thickness of the silicon layers was 4 nm.

[0088] Next, a capping layer made of ruthenium was formed on the multilayer reflective film to a thickness of 3.5 nm using a DC sputtering device. The target was ruthenium, and the sputtering gas was argon. The composition of the capping layer was analyzed by ESCA, and it was found that Ru=100 (atomic %). Next, a second protective layer made of silicon and oxygen was deposited on the capping layer to a thickness of 2 nm using a DC sputtering device. Silicon was used as the target, and argon and oxygen were used as the sputtering gas. The composition of this second protective layer was analyzed by ESCA and found to be Si:O=33:67 (atomic % ratio).

[0089] Next, a light absorbing layer made of indium and nitrogen was formed on the second protective layer to a thickness of 33 nm using an RF sputtering device. Indium was used as the target, and argon and nitrogen were used as the sputtering gas. The composition of this light absorbing layer was analyzed by ESCA and found to be In:N=50:50 (atomic % ratio). Next, a first protective layer (protective layer) made of tantalum and oxygen was formed on the light absorbing layer with a thickness of 3 nm using a DC sputtering device. The target used was tantalum, and the sputtering gas was argon and oxygen. The composition of this first protective layer (protective layer) was analyzed by ESCA and found to be Ta:O=30:70 (atomic %). Next, a hard mask (adhesion layer only) consisting of hafnium and nitrogen was deposited on the first protective layer (protection layer) with a thickness of 5 nm using an RF sputtering device. Hafnium nitride was used as the target, and argon was used as the sputtering gas. The composition of this hard mask (adhesion layer only) was analyzed by ESCA and found to be Hf:N=50:50 (atomic % ratio).

[0090] In this way, a reflective mask blank of Example 4 was obtained in which a multilayer reflective film made of molybdenum and silicon, a capping layer made of ruthenium, a second protective layer made of chromium and nitrogen, a light absorbing layer made of tin and oxygen, a first protective layer (protective layer) made of silicon and oxygen, and a hard mask (only an adhesive layer) made of hafnium and nitrogen were laminated in this order on a substrate with small thermal expansion due to exposure. The multilayer reflective film thus formed was a film having a multilayer structure that reflects light with a wavelength of 13.5 nm. The light absorbing layer thus formed was a film that absorbs light with a wavelength of 13.5 nm, had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The first protective layer (protective layer) thus formed was a film that had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The hard mask thus formed (only an adhesive layer) was a layer that had high resistance to fluorine-based gas or oxygen-free chlorine-based gas etching.

[0091] Next, a positive chemically amplified electron beam resist was spin-coated on this hard mask (only the adhesion layer) to a thickness of 100 nm, and the pattern was formed with a dose of 35 μC / cm 2 The resist was patterned by electron beam drawing at 800 .ANG., heat-treated at 110.degree. C. for 10 minutes, and developed by paddle development for 90 seconds to form a resist pattern. The resolution limit of the resist pattern of the positive chemically amplified electron beam resist used in Example 4 was 45 nm, and the aspect ratio at the resolution limit when the resist film thickness after development was 97 nm was 2.2.

[0092] Next, the hard mask (only the adhesion layer) was patterned on the reflective mask blank of Example 4 using an etching device to obtain a hard mask pattern. Chlorine, oxygen, and helium were used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed at 100%. At this time, there was no damage to the first protective layer (protective layer). Next, the resist pattern was stripped and cleaned by washing with sulfuric acid and hydrogen peroxide.

[0093] Next, the first protective layer (protective layer) and the light absorbing layer were patterned using an etching device to obtain a light absorbing pattern layer. Chlorine was used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed by 50%. At this time, the damage amount of the hard mask (only the adhesion layer) was 1 nm, and a part of the hard mask was lost, but there was no damage to the first protective layer (protective layer) and the light absorbing layer.

[0094] Next, the hard mask (only the adhesive layer) was removed using an etching device. Chlorine, oxygen, and helium were used as the 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 50%. At this time, the damage amount of the first protective layer (protective layer) was 1 nm, the damage amount of the light absorption layer was 0 nm, the damage amount of the second protective layer was 0 nm, and the damage amount of the capping layer was 0 nm. That is, in the reflective mask of Example 4, the second protective layer remains. In this manner, the reflective mask of Example 4 was obtained.

[0095] Comparative Example 1 A multilayer reflective film was formed with a thickness of 280 nm on an LTEM substrate with small thermal expansion due to exposure using a DC sputtering device, with 40 pairs of molybdenum layers and silicon layers stacked together. The targets used were molybdenum for the molybdenum layers and silicon for the silicon layers, and argon was used as the sputtering gas. Analysis of the composition of this multilayer reflective film by ESCA revealed that the molybdenum layers had Mo=100 (atomic %) and the silicon layers had Si=100 (atomic %). The thickness of the molybdenum layers was 3 nm, and the thickness of the silicon layers was 4 nm.

[0096] Next, a capping layer made of ruthenium was formed on the multilayer reflective film to a thickness of 3.5 nm using a DC sputtering device. The target was ruthenium, and the sputtering gas was argon. The composition of the capping layer was analyzed by ESCA, and it was found that Ru=100 (atomic %). Next, a light absorbing layer made of tin and oxygen was formed on the capping layer to a thickness of 30 nm using a DC sputtering device. The target was tin oxide, and the sputtering gas was argon and oxygen. The composition of this light absorbing layer was analyzed by ESCA and found to be Sn:O=38:62 (atomic %). Next, a hard mask (lower layer only) consisting of chromium and nitrogen was deposited on the light absorbing layer with 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 (lower layer only) was analyzed by ESCA and found to be Cr:N=90:10 (atomic %).

[0097] In this way, a reflective mask blank of Comparative Example 1 was obtained, in which a multilayer reflective film made of molybdenum and silicon, a capping layer made of ruthenium, a light absorbing layer made of tin and oxygen, and a hard mask (lower layer only) made of chromium and nitrogen were laminated in this order on a substrate with small thermal expansion due to exposure. The multilayer reflective film thus formed was a film having a multilayer structure that reflects light with a wavelength of 13.5 nm. The light absorbing layer thus formed was a film that absorbs light with a wavelength of 13.5 nm, had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The hard mask (lower layer only) thus formed was a layer that was highly resistant to fluorine-based gas or oxygen-free chlorine-based gas etching.

[0098] Next, a positive chemically amplified electron beam resist was spin-coated on this hard mask (only the lower layer) to a thickness of 100 nm, and the pattern was formed with a dose of 35 μC / cm 2 The resist was patterned by electron beam drawing at 800 .ANG., heat-treated at 110.degree. C. for 10 minutes, and developed by paddle development for 90 seconds to form a resist pattern. The resolution limit of the resist pattern of the positive chemically amplified electron beam resist used in Comparative Example 1 was 57 nm, and the aspect ratio at the resolution limit when the resist film thickness after development was 97 nm was 1.7.

[0099] Next, a hard mask (only the lower layer) was patterned using an etching device on the reflective mask blank of Comparative Example 1 to obtain a hard mask pattern. Chlorine, oxygen, and helium were used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed to 100%. Next, the light absorbing layer was patterned using an etching device to obtain a light absorbing pattern layer. Chlorine was used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed by 50%. At this time, the damage amount of the hard mask was 1 nm, and a part of the hard mask was lost. Next, the hard mask was removed using an etching device. Chlorine, oxygen, and helium were used as the 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 50%. The amount of damage to the capping layer was 1 nm. In this manner, the reflective mask of Comparative Example 1 was obtained.

[0100] Comparative Example 2 A multilayer reflective film was formed with a thickness of 280 nm on an LTEM substrate with small thermal expansion due to exposure using a DC sputtering device, with 40 pairs of molybdenum layers and silicon layers stacked together. The targets used were molybdenum for the molybdenum layers and silicon for the silicon layers, and argon was used as the sputtering gas. Analysis of the composition of this multilayer reflective film by ESCA revealed that the molybdenum layers had Mo=100 (atomic %) and the silicon layers had Si=100 (atomic %). The thickness of the molybdenum layers was 3 nm, and the thickness of the silicon layers was 4 nm.

[0101] Next, a capping layer made of ruthenium was formed on the multilayer reflective film to a thickness of 3.5 nm using a DC sputtering device. The target was ruthenium, and the sputtering gas was argon. The composition of the capping layer was analyzed by ESCA, and it was found that Ru=100 (atomic %). Next, a light absorbing layer made of tin and oxygen was formed on the capping layer to a thickness of 30 nm using a DC sputtering device. The target was tin oxide, and the sputtering gas was argon and oxygen. The composition of this light absorbing layer was analyzed by ESCA and found to be Sn:O=38:62 (atomic %). Next, a hard mask (adhesion layer only) consisting of hafnium and nitrogen was deposited on the light absorption layer with a thickness of 5 nm using an RF sputtering device. The target was hafnium nitride, and the sputtering gas was argon. The composition of this hard mask (adhesion layer only) was analyzed by ESCA and found to be Hf:N=50:50 (atomic % ratio).

[0102] In this way, a reflective mask blank of Comparative Example 2 was obtained, in which a multilayer reflective film made of molybdenum and silicon, a capping layer made of ruthenium, a light absorbing layer made of tin and oxygen, and a hard mask (only an adhesive layer) made of hafnium and nitrogen were laminated in this order on a substrate with small thermal expansion due to exposure. The multilayer reflective film thus formed was a film having a multilayer structure that reflects light with a wavelength of 13.5 nm. The light absorbing layer thus formed was a film that absorbs light with a wavelength of 13.5 nm, had resistance to oxygen-containing chlorine-based gas etching, and was a film that could be etched with a fluorine-based gas or an oxygen-free chlorine-based gas. The hard mask thus formed (only an adhesive layer) was a layer that had high resistance to fluorine-based gas or oxygen-free chlorine-based gas etching.

[0103] Next, a positive chemically amplified electron beam resist was spin-coated on this hard mask (only the adhesion layer) to a thickness of 100 nm, and the pattern was formed with a dose of 35 μC / cm 2 The resist was patterned by electron beam drawing at 800 .ANG., heat-treated at 110.degree. C. for 10 minutes, and developed by paddle development for 90 seconds to form a resist pattern. The resolution limit of the resist pattern of the positive chemically amplified electron beam resist used in Comparative Example 2 was 45 nm, and the aspect ratio at the resolution limit when the resist film thickness after development was 97 nm was 2.2.

[0104] Next, a hard mask (only the adhesive layer) was patterned using an etching device on the reflective mask blank of Comparative Example 2 to obtain a hard mask pattern. Chlorine, oxygen, and helium were used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed 100%. Next, the light absorbing layer was patterned using an etching device to obtain a light absorbing pattern layer. Chlorine was used as the etching gas, and the gas pressure was set to 5 mTorr, the ICP power to 400 W, and the bias power to 40 W. Overetching was performed by 50%. At this time, the damage amount of the hard mask was 1 nm, and a part of the hard mask was lost. Next, the hard mask was removed using an etching device. Chlorine, oxygen, and helium were used as the 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 50%. At this time, the damage amount of the light absorption layer was 5 nm, and the damage amount of the capping layer was 1 nm. In this manner, a reflective mask of Comparative Example 2 was obtained.

[0105] [Table 1]

[0106] From the evaluation results of Examples 1 to 4, the reflective mask blank of this Example can suppress the disappearance of the resist pattern during development of the resist film, form a fine resist pattern, and suppress the reduction in the film thickness of the light absorbing layer that occurs when the hard mask is peeled off by etching, compared to the reflective mask blanks of Comparative Examples 1 and 2, which are conventional reflective mask blanks.

[0107] The reflective mask blank of the present invention, the reflective mask of the present invention, and the method for manufacturing a reflective mask using the reflective mask blank of the present invention have been described above using the present examples, but the above examples are merely examples for carrying out the present invention, and the present invention is not limited to these. Furthermore, modifications of these examples and the above-mentioned embodiments are within the scope of the present invention, and it is self-evident from the above description that various other examples are possible within the scope of the present invention.

[0108] Furthermore, for example, the present invention can have the following configuration. (1) A reflective mask blank used in the manufacture of a reflective mask for pattern transfer using extreme ultraviolet light as a light source, A substrate; a light absorbing layer formed on the substrate, the light absorbing layer having resistance to oxygen-containing chlorine-based gas etching and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; a protective layer formed on the light absorbing layer, the protective layer having a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; a hard mask formed on the protective layer, the hard mask having resistance to etching with a fluorine-based gas or an oxygen-free chlorine-based gas and capable of being etched with an oxygen-containing chlorine-based gas; the protective layer contains at least one element selected from tantalum and silicon, The hard mask is a reflective mask blank characterized in that it contains at least one or more metal elements selected from the group consisting of titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium. (2) The reflective mask blank described in (1) above is characterized in that the hard mask is made of a plurality of layers, has an adhesion layer containing the metal element at least on the outermost surface, and has a lower layer, located on the substrate side of the adhesion layer, which has a higher resistance to fluorine-based gas or oxygen-free chlorine-based gas etching than the adhesion layer. (3) The reflective mask blank according to (1) or (2) above, characterized in that the hard mask is composed of a plurality of layers, has an adhesion layer containing the metal element on at least the outermost surface, and has a lower layer containing chromium on the substrate side of the adhesion layer. (4) The reflective mask blank according to any one of (1) to (3) above, wherein the thickness of the adhesion layer is within the range of 1 nm or more and 10 nm or less. (5) The reflective mask blank according to any one of (1) to (4) above, wherein the thickness of the lower layer is within the range of 1 nm to 19 nm. (6) The reflective mask blank according to any one of (1) to (5) above, wherein the hard mask has a thickness in the range of 2 nm to 20 nm. (7) The reflective mask blank according to any one of (1) to (6) above, wherein the protective layer has a thickness in the range of 1 nm to 20 nm. (8) The reflective mask blank according to any one of (1) to (7) above, wherein the light absorbing layer contains at least one compound selected from the group consisting of tin compounds and indium compounds. (9) The reflective mask blank according to (8) above, wherein the tin compound contains tin and one or more elements selected from the group consisting of nitrogen, boron, oxygen, and carbon. (10) The reflective mask blank according to (8) above, wherein the indium compound contains indium and one or more elements selected from the group consisting of nitrogen, boron, oxygen, and carbon. (11) The reflective mask blank according to (9) or (10) above, characterized in that it has a multilayer reflective film between the substrate and the light absorbing layer, the multilayer reflective film having a multilayer structure and reflecting extreme ultraviolet light. (12) The reflective mask blank according to any one of the above (1) to (11), characterized in that it has a second protective layer between the multilayer reflective film and the light absorbing layer, the second protective layer containing at least one or more elements selected from tantalum, silicon, and chromium. (13) The reflective mask blank according to (12) above, wherein the thickness of the second protective layer is within the range of 1 nm or more and 20 nm or less. (14) A reflective mask on which an extreme ultraviolet exposure light is applied to form a transfer pattern, A substrate; a light absorbing layer formed on the substrate, the light absorbing layer having resistance to oxygen-containing chlorine-based gas etching and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; a protective layer formed on the light absorbing layer, the protective layer having a higher resistance to oxygen-containing chlorine-based gas etching than the light absorbing layer and capable of being etched by a fluorine-based gas or an oxygen-free chlorine-based gas; a hard mask formed on the protective layer, the hard mask having resistance to etching with a fluorine-based gas or an oxygen-free chlorine-based gas and capable of being etched with an oxygen-containing chlorine-based gas; the protective layer contains at least one element selected from tantalum and silicon, The hard mask is a reflective mask characterized in that it contains at least one or more metal elements selected from the group consisting of titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium. (15) A method for producing a reflective mask using a reflective mask blank according to any one of (1) to (13) above, comprising the steps of: forming a resist pattern on the hard mask of the reflective mask blank; forming a hard mask pattern by etching the hard mask with an oxygen-containing chlorine-based gas using the resist pattern as a mask; a step of sequentially etching the protective layer and the light absorbing layer with a fluorine-based gas or an oxygen-free chlorine-based gas using the hard mask pattern as a mask to form a pattern consisting of the protective layer and the light absorbing layer; and removing the hard mask pattern by etching with an oxygen-containing chlorine-based gas. [Industrial Applicability]

[0109] In the present invention, the compositions, film thicknesses, and layer structures of the reflective mask blank, as well as the manufacturing processes and conditions for the reflective mask using the same, are selected within appropriate ranges, making it possible to provide a transmission mask and a reflective mask on which fine patterns are formed with high precision, suitable for manufacturing logic devices of 28 nm or less, or memory devices of 30 nm or less. [Explanation of symbols]

[0110] 1 Board 2. Light absorbing layer 2a Light absorbing pattern layer 3 First protective layer (protective layer) 4. Hard Mask 4a lower layer 4b Adhesion layer 5 Multilayer reflective film 6 Capping Layer 7 Second protective layer 8. Resist Pattern 11 Reflective mask blanks 12 Reflective mask blanks 13 Reflective mask blanks 14 Reflective mask blanks 21 Reflective mask 22 Reflective mask 23 Reflective mask 24 Reflective mask

Claims

1. A reflective mask blank used in the manufacture of reflective masks for pattern transfer using extreme ultraviolet light as a light source, circuit board and A light-absorbing layer formed on the substrate, which has resistance to etching with oxygen-containing chlorine-based gases and can be etched with a fluorine-based gas or an oxygen-free chlorine-based gas, A protective layer formed on the light-absorbing layer, having higher resistance to etching with oxygen-containing chlorine-based gases than the light-absorbing layer, and capable of etching with fluorine-based gases or oxygen-free chlorine-based gases, The hard mask, formed on the protective layer, has resistance to etching with fluorine-based gases or oxygen-free chlorine-based gases, and is etchable with oxygen-containing chlorine-based gases, The protective layer contains at least one element selected from tantalum and silicon, The hard mask is characterized by containing at least one or more metallic elements selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium.

2. The hard mask is characterized in that it consists of multiple layers, has at least one adhesion layer containing the metal element on its outermost surface, and has a lower layer on the substrate side of the adhesion layer that has higher resistance to etching by fluorine-based gases or oxygen-free chlorine-based gases than the adhesion layer, as described in claim 1.

3. The reflective mask blank according to claim 1, characterized in that the hard mask comprises a plurality of layers, has at least one adhesion layer containing the metal element on its outermost surface, and has a lower layer containing chromium on the substrate side of the adhesion layer.

4. The reflective mask blank according to claim 3, characterized in that the thickness of the adhesion layer is in the range of 1 nm to 10 nm.

5. The reflective mask blank according to claim 4, characterized in that the film thickness of the lower layer is in the range of 1 nm to 19 nm.

6. The reflective mask blank according to claim 5, characterized in that the film thickness of the hard mask is in the range of 2 nm to 20 nm.

7. The reflective mask blank according to claim 6, characterized in that the thickness of the protective layer is in the range of 1 nm to 20 nm.

8. The reflective mask blank according to claim 7, characterized in that the light-absorbing layer contains at least one compound selected from tin compounds and indium compounds.

9. The reflective mask blank according to claim 8, characterized in that the tin compound contains tin and one or more elements selected from nitrogen, boron, oxygen, and carbon.

10. The reflective mask blank according to claim 8, characterized in that the indium compound contains indium and one or more elements selected from nitrogen, boron, oxygen, and carbon.

11. The reflective mask blank according to claim 9 or 10, characterized in that it has a multilayer reflective film having a multilayer structure that reflects extreme ultraviolet light between the substrate and the light-absorbing layer.

12. The reflective mask blank according to claim 11, characterized in that a second protective layer containing at least one element selected from tantalum, silicon, and chromium is provided between the multilayer reflective film and the light-absorbing layer.

13. The reflective mask blank according to claim 12, characterized in that the thickness of the second protective layer is in the range of 1 nm to 20 nm.

14. A reflective mask in which an exposure light of extreme ultraviolet light is applied and a transfer pattern is formed, circuit board and A light-absorbing layer formed on the substrate, which has resistance to etching with oxygen-containing chlorine-based gases and can be etched with a fluorine-based gas or an oxygen-free chlorine-based gas, A protective layer formed on the light-absorbing layer, having higher resistance to etching with oxygen-containing chlorine-based gases than the light-absorbing layer, and capable of etching with fluorine-based gases or oxygen-free chlorine-based gases, The hard mask, formed on the protective layer, has resistance to etching with fluorine-based gases or oxygen-free chlorine-based gases, and is etchable with oxygen-containing chlorine-based gases, The protective layer contains at least one element selected from tantalum and silicon, The hard mask is characterized by containing at least one metallic element selected from titanium, zirconium, niobium, hafnium, beryllium, aluminum, ruthenium, tin, and indium.

15. A method for manufacturing a reflective mask using a reflective mask blank according to any one of claims 1 to 10, A step of forming a resist pattern on the hard mask of the reflective mask blank, The process involves etching the hard mask with an oxygen-containing chlorine gas using the resist pattern as a mask to form a hard mask pattern. The process involves using the hard mask pattern as a mask to continuously etch the protective layer and the light-absorbing layer with a fluorine-based gas or an oxygen-free chlorine-based gas to form a pattern consisting of the protective layer and the light-absorbing layer. A method for manufacturing a reflective mask, comprising the step of removing the hard mask pattern by etching with an oxygen-containing chlorine-based gas.

Images