JP7117445B1 - Reflective photomask blanks and reflective photomasks - Google Patents

Abstract

Kind Code: A1 A reflective photomask and a reflective photomask that suppresses or reduces the projection effect of a reflective photomask for pattern transfer using light having a wavelength in the extreme ultraviolet region as a light source and has resistance to hydrogen radicals. Provide photomask blanks. A reflective photomask blank 10 according to an embodiment of the present invention is a reflective photomask blank for producing a reflective photomask 20 for pattern transfer using extreme ultraviolet light as a light source. , a reflective layer 2 including a multilayer film formed on a substrate 1, and an absorbing layer 4 formed on the reflective layer 2, the absorbing layer 4 comprising tin (Sn) and oxygen (o) and a total of 70 atomic % or more, the valence of tin (Sn) is 3.3 or more, and 5 atomic % or more and 20 atomic % or less of tantalum (Ta) is mixed, and the absorption layer 4 has a film density of 4.0 g/cm 3 or more, and the film thickness of the absorption layer 4 is in the range of 17 nm or more and 45 nm or less. [Selection drawing] Fig. 1

Description

The present invention relates to a reflective photomask used in lithography using light in the ultraviolet region as a light source and a reflective photomask blank for producing the same.

2. Description of the Related Art In the process of manufacturing semiconductor devices, the demand for finer photolithography techniques is increasing as semiconductor devices become finer. The minimum resolution dimension of a transfer pattern in photolithography largely depends 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 replacing conventional ArF excimer laser light with a wavelength of 193 nm with light in the EUV (Extreme Ultra Violet) region with a wavelength of 13.5 nm.

Since most substances absorb light in the EUV region at a high rate, a reflective photomask is used as a photomask for EUV exposure (EUV mask) (see, for example, Patent Document 1). In Patent Document 1, a reflective layer composed of a multilayer film in which molybdenum (Mo) layers and silicon (Si) layers are alternately laminated on a glass substrate is formed, and a light absorbing layer containing tantalum (Ta) as a main component is formed thereon. An EUV photomask obtained by forming a layer and patterning the light absorbing layer is disclosed.

In addition, since EUV lithography cannot use a refractive optical system that utilizes light transmission as described above, the optical system members of the exposure machine are not lenses but reflective (mirrors). For this reason, there is a problem that the incident light and the reflected light to the reflective photomask (EUV mask) cannot be designed to be coaxial. A method of guiding the reflected light reflected at an angle of minus 6 degrees to the semiconductor substrate is adopted.

In this way, in EUV lithography, the optical axis is tilted via a mirror, so the EUV light incident on the EUV mask casts a shadow on the mask pattern (patterned light absorption layer) of the EUV mask, the so-called "projection effect". A problem called

In current EUV mask blanks, a film mainly composed of tantalum (Ta) having a thickness of 60 to 90 nm is used as a light absorption layer. When pattern transfer exposure is performed with an EUV mask fabricated using this mask blank, the contrast may be reduced at the edge portion where the mask pattern is shadowed, depending on the relationship between the incident direction of the EUV light and the direction of the mask pattern. may cause it. Along with this, problems such as an increase in line edge roughness of a transfer pattern on a semiconductor substrate and an inability to form a line width with a target dimension may occur, resulting in deterioration of transfer performance.

Therefore, consideration has been given to changing the light absorption layer from tantalum (Ta) to a material having a high absorption (extinction coefficient) for EUV light, or to a reflective photomask blank in which a material having a high absorption is added to tantalum (Ta). ing. For example, in Patent Document 2, the light absorption layer contains Ta as a main component of 50 atomic % (at %) or more, and further Te, Sb, Pt, I, Bi, Ir, Os, W, Re, Sn, In, A reflective photomask blank composed of a material containing at least one element selected from Po, Fe, Au, Hg, Ga and Al is described.

In addition, mirrors are known to be contaminated by EUV generation by-products (eg, Sn), carbon, and the like. Accumulation of contaminants on the mirrors reduces the reflectivity of the mirror surfaces and reduces the throughput of the lithographic apparatus. In response to this problem, Patent Document 3 discloses a method of removing contaminants from a mirror by generating hydrogen radicals in an apparatus and reacting the hydrogen radicals with contaminants.

However, in the reflective photomask blank described in Patent Document 2, no consideration is given to the light absorption layer having resistance to hydrogen radicals (hydrogen radical resistance). Therefore, the transfer pattern (mask pattern) formed on the light absorption layer cannot be stably maintained by introduction into the EUV exposure apparatus, and as a result, transferability may deteriorate.

JP 2011-176162 A JP 2007-273678 A JP 2011-530823 A

Therefore, the present invention suppresses or reduces the projection effect of a reflective photomask for pattern transfer using light of a wavelength in the extreme ultraviolet region as a light source, and has resistance to hydrogen radicals, and a reflective photomask blank and a reflective mask blank. The purpose is to provide a photomask. More specifically, the present invention provides a reflective photomask and a reflective photomask blank for producing the same, in which the possibility of deterioration in transferability is reduced by imparting hydrogen radical resistance to the light absorption layer. intended to provide

In order to solve the above problems, a reflective photomask blank according to one aspect of the present invention is a reflective photomask blank for producing a reflective photomask for pattern transfer using extreme ultraviolet light as a light source, a substrate, a reflective layer including a multilayer film formed on the substrate, and an absorbing layer formed on the reflective layer, the absorbing layer containing tin (Sn) and oxygen (◯) The valence of the tin (Sn) contained in the absorption layer is 3.3 or more, and the absorption layer contains 5 atomic % of tantalum (Ta). 20 atomic % or less is mixed, the film density of the absorption layer is 4.0 g/cm ³ or more, and the film thickness of the absorption layer is in the range of 17 nm or more and 45 nm or less.

The film thickness of the absorption layer in the reflective photomask blank according to one aspect of the present invention may be in the range of 20 nm or more and 30 nm or less.

The absorption layer in the reflective photomask blank according to one aspect of the present invention includes Pt, Te, In, Zr, Hf, Ti, W, Si, Cr, Mo, B, Pd, Ni, P, F, N, It may be formed of a material further containing one or more elements selected from the group consisting of C and H.

A reflective photomask blank according to an aspect of the present invention may further have a barrier layer formed on the absorbing layer.

The barrier layer in the reflective photomask blank according to an aspect of the present invention is an oxide, nitride, boride, fluoride, oxynitride, oxyboride, and oxyfluoride of tantalum (Ta), or Contains one or more compounds selected from the group consisting of oxides containing tantalum (Ta) and tin (Sn), nitrides, borides, fluorides, oxynitrides, oxyborides, and oxyfluorides It may be made of a material that

The film thickness of the barrier layer in the reflective photomask blank according to one aspect of the present invention may be 5 nm or less.

A reflective photomask blank according to an aspect of the present invention may further include a capping layer formed between the reflective layer and the absorbing layer.

In order to solve the above problems, a reflective photomask according to an aspect of the present invention includes a substrate, a reflective layer including a multilayer film formed on the substrate, and a transfer layer on the reflective layer. an absorption pattern layer in which an absorption pattern serving as a pattern is formed, wherein the absorption pattern layer is formed of a material containing a total of 70 atomic % or more of tin (Sn) and oxygen (◯), and the absorption The tin (Sn) contained in the pattern layer has a valence of 3.3 or more, and the absorption pattern layer contains 5 atomic % or more and 20 atomic % or less of tantalum (Ta). The density is 4.0 g/cm ³ or more, and the film thickness of the absorption pattern layer is in the range of 17 nm or more and 45 nm or less.

The film thickness of the absorption pattern layer in the reflective photomask according to one aspect of the present invention may be in the range of 20 nm or more and 30 nm or less.

The absorption pattern layer in the reflective photomask according to one aspect of the present invention includes Pt, Te, In, Zr, Hf, Ti, W, Si, Cr, Mo, B, Pd, Ni, P, F, N, It may be formed of a material further containing one or more elements selected from the group consisting of C and H.

The absorption pattern layer in the reflective photomask according to one aspect of the present invention may further have a barrier layer on at least one of the upper surface and side surfaces of the absorption pattern layer.

The barrier layer in the reflective photomask according to one aspect of the present invention includes oxide, nitride, boride, fluoride, oxynitride, oxyboride, and oxyfluoride of tantalum (Ta), or tantalum. Contains one or more compounds selected from the group consisting of oxides containing (Ta) and tin (Sn), nitrides, borides, fluorides, oxynitrides, oxyborides, and oxyfluorides It may be made of any material.

The film thickness of the barrier layer in the reflective photomask according to one aspect of the present invention may be 5 nm or less.

A reflective photomask according to an aspect of the present invention may further include a capping layer formed between the reflective layer and the absorbing layer.

According to one aspect of the present invention, a reflective photomask can be expected that has improved transfer performance to a semiconductor substrate in patterning using light having a wavelength in the extreme ultraviolet region as a light source and that can be used even in a hydrogen radical environment. That is, the reflective photomask according to one aspect of the present invention suppresses or reduces the projection effect of the reflective photomask for pattern transfer using light with a wavelength in the extreme ultraviolet region as a light source, and also suppresses or reduces the projection effect on hydrogen radicals. Tolerant.

1 is a schematic cross-sectional view showing the structure of a reflective photomask blank according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view showing the structure of a reflective photomask according to an embodiment of the present invention; FIG. 4 is a graph showing the optical constants of each metal material at the wavelength of EUV light; 1 is a schematic cross-sectional view showing the structure of a reflective photomask blank according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view showing the structure of a reflective photomask according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view showing the structure of a reflective photomask according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view showing the structure of a reflective photomask blank according to an example of the present invention; FIG. 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to an example of the present invention; 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to an example of the present invention; 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to an example of the present invention; 1 is a schematic cross-sectional view showing the structure of a reflective photomask according to an example of the present invention; FIG. FIG. 4 is a schematic plan view showing the shape of the design pattern of the reflective photomask according to the example of the present invention; 1 is a schematic cross-sectional view showing the structure of a reflective photomask according to an example of the present invention; FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments shown below. In the embodiments shown below, technically preferred limitations are made for implementing the present invention, but the limitations are not essential to the present invention.

FIG. 1 is a schematic cross-sectional view showing the structure of a reflective photomask blank 10 according to an embodiment of the invention. Also, FIG. 2 is a schematic cross-sectional view showing the structure of a reflective photomask 20 according to an embodiment of the present invention. Here, the reflective photomask 20 according to the embodiment of the present invention shown in FIG. 2 is formed by patterning the absorption layer 4 of the reflective photomask blank 10 according to the embodiment of the present invention shown in FIG. be.

(overall structure)
As shown in FIG. 1, a reflective photomask blank 10 according to an embodiment of the present invention includes a substrate 1, a reflective layer 2 formed on the substrate 1, and a capping layer 3 formed on the reflective layer 2. and an absorbing layer 4 formed on the capping layer 3 .

(substrate)
A flat Si substrate, a synthetic quartz substrate, or the like, for example, can be used as the substrate 1 according to the embodiment of the present invention. Further, the substrate 1 can be made of low thermal expansion glass to which titanium is added, but the present invention is not limited to these materials as long as the material has a small thermal expansion coefficient.

(reflective layer)
The reflective layer 2 according to the embodiment of the present invention may reflect EUV light (extreme ultraviolet light), which is exposure light, and is a multilayer reflective film made of a combination of materials having significantly different refractive indices for EUV light. good too. The reflective layer 2 including a multi-layer reflective film is formed by repeatedly stacking a combination of Mo (molybdenum) and Si (silicon) or Mo (molybdenum) and Be (beryllium) about 40 cycles. may

(capping layer)
The capping layer 3 according to the embodiment of the present invention is made of a material that is resistant to dry etching performed when forming a transfer pattern (mask pattern) on the absorption layer 4, and the absorption layer 4 is etched. In this case, it functions as an etching stopper to prevent damage to the reflective layer 2 . The capping layer 3 is made of Ru (ruthenium), for example. Depending on the material of the reflective layer 2 and etching conditions, the capping layer 3 may not be formed. Moreover, although not shown, a back conductive film can be formed on the surface of the substrate 1 on which the reflective layer 2 is not formed. The back conductive film is a film for fixing the reflective photomask 20 using the principle of an electrostatic chuck when the reflective photomask 20 is installed in the exposure machine.

(absorbent layer)
As shown in FIG. 2, by removing part of the absorbing layer 4 of the reflective photomask blank 10, that is, by patterning the absorbing layer 4, an absorbing pattern (absorbing pattern layer) 41 of the reflective photomask 20 is formed. is formed. In EUV lithography, EUV light is obliquely incident and reflected by the reflective layer 2, but the absorption pattern 41 obstructs the optical path, resulting in a projection effect, which may deteriorate the transfer performance onto a wafer (semiconductor substrate). . This deterioration in transfer performance can be reduced by reducing the thickness of the absorption layer 4 that absorbs EUV light. In order to reduce the thickness of the absorption layer 4, it is preferable to use a material that absorbs EUV light more than conventional materials, that is, a material that has a high extinction coefficient k for a wavelength of 13.5 nm.

FIG. 3 is a graph showing the optical constants of each metal material with respect to an EUV light wavelength of 13.5 nm. The horizontal axis of FIG. 3 represents the refractive index n, and the vertical axis represents the extinction coefficient k. The extinction coefficient k of tantalum (Ta), which is the main material of the conventional absorption layer 4, is 0.041. If the compound material has a larger extinction coefficient k than that, it is possible to make the thickness of the absorption layer 4 thinner than before.

As shown in FIG. 3, materials satisfying the above extinction coefficient k include, for example, silver (Ag), platinum (Pt), indium (In), cobalt (Co), tin (Sn), nickel ( Ni) and tellurium (Te). However, some of these metal materials have the problem of low volatility of elemental halides and poor dry etching properties. Therefore, even if a reflective photomask blank having an absorbing layer made of these metal materials is manufactured, the absorbing pattern layer cannot be patterned on the absorbing layer. A problem arises that the photomask cannot be processed. Alternatively, since the melting points of these metal materials are low, they cannot withstand heat during the production of a reflective photomask or during EUV exposure, resulting in a poorly practical reflective photomask.

In order to avoid the above drawbacks, the absorbing layer 4 of the reflective photomask blank of this embodiment or the absorbing pattern layer 41 of the reflective photomask 20 of this embodiment is made of a material containing tin (Sn) and oxygen (O). It shall be formed by Sn _alone has a melting point of around 230° C., which is lower than the temperature of the heat used during reflective photomask production and EUV exposure, and has a problem with thermal stability. , the respective melting points can be significantly increased. A plurality of tin oxide (SnO ₂ ) films were actually produced by reactive sputtering, and the melting point was measured with a thermal analysis device. It is thought that

Moreover, since the reflective photomask 20 is exposed to a hydrogen radical environment, the reflective photomask 20 cannot withstand long-term use unless it is made of a light-absorbing material with high resistance to hydrogen radicals. In the present embodiment, a material having a film reduction rate of 0.01 nm/s or less is treated with hydrogen radicals in a hydrogen radical environment at a power of 1 kW and a hydrogen pressure of 0.36 mbar or less using microwave plasma. Use highly durable materials.
Tin (Sn) alone is known to have low resistance to hydrogen radicals, but the addition of oxygen increases the resistance to hydrogen radicals. Furthermore, by mixing tantalum (Ta), the resistance is greatly increased, and it becomes possible to satisfy the above-mentioned hydrogen radical resistance standard. This is probably because the addition of tantalum (Ta), which is resistant to hydrogen radicals, increases the strength and contributes to the improvement of the stability of the compound.

The absorption layer 4 in this embodiment is made of a material containing tin (Sn), oxygen (O) and tantalum (Ta), and preferably has a film density of 4.0 g/cm ³ or more. If the film density of the absorption layer 4 is less than 4.0 g/cm ³ , the bondability is unstable, and minute cavities are present inside the film, resulting in insufficient resistance to hydrogen radicals. occurs. There is also the problem that sufficient absorption performance for EUV light can not be obtained. On the other hand, although there is no particular upper limit to the film density of the absorption layer 4, the higher the film density, the more difficult it is to obtain smoothness of the film, and the more difficult it is to process the film by sputtering or by dry etching. Therefore, the film density of the absorption layer 4 is preferably 4.0 g/cm ³ or more, more preferably in the range of 5.0 g/cm ³ to 12.0 g/cm ³ , and 6.0 g/cm 3 or more. More preferably, it is within the range of cm ³ to 10.0 g/cm ³ .
The film density of the absorption layer 4 in this embodiment was calculated from the measurement results of Rutherford Backscattering Spectroscopy (RBS).

As described above, the film density of the absorption layer 4 affects the smoothness of the film and the line edge roughness of the formed absorption pattern layer 41 . If the surface roughness of the absorption layer 4 is large, it may affect the reflection efficiency of EUV light. Therefore, the surface roughness (RMS) of the absorption layer 4 is preferably 0.6 nm or less, more preferably 0.4 nm or less.
In this embodiment, the surface roughness (RMS) of the absorbing layer 4 was measured using an atomic force microscope (AFM), for example.

The material forming the absorption layer 4 preferably contains tin (Sn) and oxygen (O) in a total amount of 70 atomic % or more. Furthermore, the absorption layer 4 preferably contains tantalum (Ta) in an amount of 5 atomic % or more and 20 atomic % or less. That is, the absorption layer 4 is made of a material containing a total of 70 atomic % or more of tin (Sn) and oxygen (O) and containing 5 atomic % or more and 20 atomic % or less of tantalum (Ta). is preferred. This is because if the absorption layer 4 contains a component other than tin (Sn) and oxygen (O), the EUV light absorbability may decrease, but This is because if the content of the component is less than 30 atomic %, the deterioration of the EUV light absorptivity is very slight, and the performance as the absorption layer 4 of the EUV mask hardly deteriorates. Furthermore, since tin oxide (SnO ₂ ) can be dry-etched using a chlorine-based gas, a reflective photomask blank can be processed into a reflective photomask, but tantalum (Ta) cannot be mixed. workability is reduced by If the content of tantalum (Ta) mixed in the absorption layer 4 is 5 atomic % or more and 20 atomic %, and if the film density of the absorption layer 4 is 4.0 g/cm ³ or more, the workability is hardly lowered by dry etching. It is small, and hydrogen radical resistance is also improved.
If the tantalum (Ta) content is less than 5 atomic percent, the hydrogen radical resistance cannot be improved. In addition, if the tantalum (Ta) content exceeds 20 atomic %, it is expected that the workability by dry etching will be lowered and the line edge roughness (LER) will increase, adversely affecting the wafer transferability. Furthermore, when the content of tantalum (Ta) exceeds 20 atomic %, the contrast in DUV (Deep Ultra Violet) light with a wavelength of 190 to 260 nm is lowered, resulting in poor testability. Therefore, the content of tantalum (Ta) is preferably 5 atomic % or more and 20 atomic % or less, more preferably 8 atomic % or more and 15 atomic % or less.

The composition ratio of the material constituting the absorption layer 4 is calculated based on the analysis result by Rutherford Backscattering Spectroscopy (RBS), and the content may vary depending on the analysis method. For example, as a result of analyzing a material with a tantalum (Ta) content of 5 atomic % to 20 atomic % by RBS analysis using X-ray photoelectron spectroscopy (XPS), even if it is 4 atomic % to 13 atomic % good. Furthermore, for example, a material with a tantalum (Ta) content of 5 atomic % to 20 atomic % by RBS analysis was analyzed using energy dispersive X-ray spectroscopy (EDX), and the result was 8 atomic % to 34 atomic %. can be

As described above, the material containing tin (Sn) and oxygen (O) for forming the absorption layer 4 preferably has a stoichiometric composition close to tin oxide (SnO ₂ ). Moreover, it is desirable that the mixed Ta also forms a stable structure. That is, the valence of tin (Sn) in the material forming the absorption layer 4 is preferably 3.3 or more, more preferably 3.5 or more.
Further, the valence of tin (Sn) and the measurement result of the composition ratio of stoichiometric tin oxide (SnO ₂ ) do not necessarily match. Even if the atomic ratio (O/Sn) exceeds 2.0, there is no problem if the valence of tin (Sn) is 3.3 or more. That is, as long as the valence of tin (Sn) is 3.3 or more, the ratio (O/Sn) between oxygen (O) and tin (Sn) does not matter, but the ratio is 2.0 to 3.2. It is preferably in the vicinity, for example, in the range of 1.7 to 3.5, more preferably in the range of 1.8 to 3.0.
The valence of tin (Sn) in this embodiment is the result of measurement by XAFS (X-ray absorption fine structure).
When the above-mentioned tantalum (Ta) is mixed in the absorption layer 4, the tantalum (Ta) may be oxidized like tin (Sn), or may not be oxidized.

As described above, the material constituting the absorption layer 4 preferably contains a total of 70 atomic % or more of tin (Sn) and oxygen (O) and 5 atomic % or more and 20 atomic % or less of tantalum (Ta). Examples of materials other than tin (Sn), oxygen (O) and tantalum (Ta) include Pt, Te, In, Zr, Hf, Ti, W, Si, Cr, Mo, B, Pd, Ni, P, F , N, C, and H may be mixed. That is, the absorption layer 4 includes Pt, Te, In, Zr, Hf, Ti, W, Si, Cr, Mo, B, Pd, Ni, in addition to tin (Sn), oxygen (O), and tantalum (Ta). It may further contain one or more elements selected from the group consisting of P, F, N, C, and H. That is, the absorption layer 4 includes Pt, Te, In, Zr, Hf, Ti, W, Si, Cr, Mo, B, Pd, Ni, in addition to tin (Sn), oxygen (O), and tantalum (Ta). At least one element selected from the group consisting of P, F, N, C, and H may be further contained as long as it is less than 25 atomic % with respect to the total number of atoms constituting the absorption layer 4. good.
For example, by mixing Pt, Te, In, Pd, and Ni in the absorption layer 4, it is possible to impart conductivity to the film (absorption layer 4) while ensuring high absorption of EUV light. Therefore, it is possible to improve the inspectability in mask pattern inspection using DUV (Deep Ultra Violet) light with a wavelength of 190 to 260 nm.
Moreover, when N, Hf, or Zr, Mo, Cr, B, and F are mixed in the absorption layer 4, it becomes possible to make the film quality more amorphous. Therefore, it is possible to improve the roughness and in-plane dimensional uniformity of the absorption layer pattern (mask pattern) after dry etching, or the in-plane uniformity of the transferred image.
Also, when Ti, W, and Si are mixed in the absorption layer 4, it is possible to increase the resistance to cleaning of the absorption layer 4 (absorption pattern layer 41).

As described above, a compound material containing Ta as a main component has been applied to the absorption layer 4 (absorption pattern layer 41) of a conventional EUV reflective photomask. In this case, the film thickness of the absorption layer 4 is 40 nm in order to obtain 1 or more in the optical density OD (formula 1), which is an index representing the contrast of the light intensity between the absorption layer 4 (absorption pattern layer 41) and the reflection layer 2. In order to obtain an OD of 2 or more, the film thickness of the absorption layer 4 must be 70 nm or more. The extinction coefficient k of Ta is 0.041. According to the law, if the OD is at least 1, the thickness of the absorption layer 4 can be reduced to 17 nm or less, and if the OD is 2 or more, the thickness of the absorption layer 4 should be 45 nm or less. is possible. However, when the thickness of the absorption layer 4 (absorption pattern layer 41) exceeds 45 nm, the absorption layer 4 (absorption pattern layer 41) with a thickness of 60 nm formed of a conventional compound material containing Ta as a main component and the projection effect becomes the same.
OD=−log(Ra/Rm) (Formula 1)
Therefore, the film thickness of the absorption layer 4 according to the embodiment of the present invention is preferably 17 nm or more and 45 nm or less. That is, when the thickness of the absorption layer 4 is within the range of 17 nm or more and 45 nm or less, the projection effect can be sufficiently reduced compared to the conventional absorption layer 4 formed of a compound material containing Ta as a main component. and the transfer performance is improved. The optical density (OD) value is the contrast between the absorption layer 4 (absorption pattern layer 41) and the reflection layer 2, and if the OD value is less than 1, sufficient contrast cannot be obtained. , the transfer performance tends to decrease. The film thickness of the absorption layer 4 is preferably in the range of 17 nm or more and 45 nm or less, and more preferably in the range of 20 nm or more and 30 nm or less.
Moreover, the above-mentioned "main component" refers to a component containing 50 atomic % or more of the total number of atoms in the absorption layer.

(barrier layer)
As shown in FIG. 4, the reflective photomask blank 10 according to the embodiment of the present invention may have a barrier layer 5 formed on the absorption layer 4 . Furthermore, the reflective photomask 20 according to the embodiment of the present invention may have a barrier layer 51 formed on the absorbing pattern layer 41 as shown in FIG. A barrier layer 51 may be formed on each of the upper surface and the side surface of the . That is, each absorbing pattern layer 41 may be covered with a barrier layer 51 over its entire exposed surface. The absorption pattern layer 41 may have the barrier layer 51 formed on at least one of the upper surface and the side surface of the absorption pattern layer 41 .

The barrier layer 5 and the barrier layer 51 according to the embodiment of the present invention may be a film, a natural oxide film generated by reaction with the atmosphere, or a mask manufacturing process such as a cleaning process. may be used, and have the function of further increasing the resistance to hydrogen radicals.

Materials constituting the barrier layer 5 and the barrier layer 51 are tin (Sn) and tantalum (Ta) constituting the absorption layer 4 and the absorption pattern layer 41, or oxides, nitrides, borides, fluorides of tantalum (Ta). one or more compounds selected from the group consisting of oxides, oxynitrides, oxyborides, and oxyfluorides. That is, the barrier layer 5 and the barrier layer 51 are made of oxides, nitrides, borides, fluorides, oxynitrides, oxyborides, and oxyfluorides of tantalum (Ta), or tantalum (Ta) and tin ( A layer made of a material containing one or more compounds selected from the group consisting of oxides, nitrides, borides, fluorides, oxynitrides, oxyborides, and oxyfluorides containing Sn) is.
For example, in the case of a natural oxide film or the barrier layers 5 and 51 formed in the mask manufacturing process, the oxide of tantalum (Ta) or the oxide of tantalum (Ta) and tin (Sn) is mainly used. A thin film is formed.

When the barrier layer 5 is deposited, the absorption layer 4 of the reflective photomask blank 10 can be formed by sputtering or atomic layer deposition (ALD). Further, when forming the barrier layer 51 on the absorption pattern layer 41 in which the absorption layer 4 is patterned, for example, selective ALD (Area-selective deposition) can be used.

The film thickness of the barrier layer 5 and the barrier layer 51 includes a natural oxide film formed naturally, so there is no particular upper limit. However, if the barrier layer 5 and the barrier layer 51 are thickened, the structure (reflection type photomask blank 10) shown in FIG. 4 may deteriorate the workability by dry etching. (reflection type photomask 20) shown in FIG.
Therefore, the film thicknesses of the barrier layers 5 and 51 are preferably 5 nm or less, more preferably 4 nm or less, and even more preferably 3 nm or less. Although there is no particular lower limit for the film thicknesses of the barrier layers 5 and 51, it is preferable that the film thicknesses of the barrier layers 5 and 51 are 1 nm or more because film formation is facilitated.
Moreover, even if there is a clear boundary between the barrier layer 5 (barrier layer 51) and the absorption layer 4 (absorption pattern layer 41), even if the composition ratio changes continuously (that is, a clear no boundaries exist), no problem.
Further, as shown in FIG. 6, the thickness of the barrier layer 51 formed on the upper surface of the absorption pattern layer 41 is defined as "DT", and the thickness of the barrier layer 51 formed on the side surface of the absorption pattern layer 41 is defined as "DT". When "DS" is defined, the film thickness DT and the film thickness DS may have the same value.
Also, the film thickness DT may be thicker than the film thickness DS. In that case, the film thickness DS may be 0.1 times or more and less than 1 time the film thickness DT, and more preferably 0.5 times or more and 0.8 times or less the film thickness DT.
Also, the film thickness DT may be thinner than the film thickness DS. In that case, the film thickness DT may be 0.1 times or more and less than 1 time the film thickness DS, and more preferably 0.5 times or more and 0.8 times or less the film thickness DS.

Examples of a reflective photomask blank and a reflective photomask according to the present invention will be described below.

[Example 1]
First, a method for manufacturing the reflective photomask blank 10 will be described with reference to FIG.
First, as shown in FIG. 7, on a synthetic quartz substrate 1 having low thermal expansion characteristics, a reflective layer is formed by laminating 40 pairs of laminated films of silicon (Si) and molybdenum (Mo). 2 is formed. The film thickness of the reflective layer 12 was set to 280 nm.
Next, a capping layer 3 made of ruthenium (Ru) was formed as an intermediate film on the reflective layer 12 so as to have a thickness of 3.5 nm.
Next, an absorption layer 4 containing tin (Sn), oxygen (O), and tantalum (Ta) was formed on the capping layer 3 to a thickness of 26 nm. The valence of tin (Sn) was 3.7 as determined by XAFS (X-ray absorption fine structure). Further, when composition analysis was performed using Rutherford backscattering spectroscopy (RBS), the total content of tin (Sn) and oxygen (O) was 90 atomic % in the entire absorption layer 4, and tantalum (Ta) was It contained 10 atomic %. Furthermore, the density was calculated from the results of RBS measurement and was 7.0 g/cm ³ . Moreover, when the crystallinity of the absorption layer 4 was measured by XRD (X-ray diffraction device), it was amorphous although the crystallinity was slightly observed.
Next, a back conductive film 6 made of chromium nitride (CrN) was formed to a thickness of 100 nm on the side of the substrate 1 on which the reflective layer 2 was not formed. 10 was created.

A sputtering apparatus was used for film formation (layer formation) of each film on the substrate 1 . The film thickness of each film was controlled by the sputtering time. The absorption layer 4 was formed by a reactive sputtering method so that the valence of tin (Sn) was 3.7 by controlling the amount of oxygen introduced into the chamber during sputtering.

Next, a method for manufacturing the reflective photomask 20 will be described with reference to FIGS. 8 to 11. FIG.
First, as shown in FIG. 8, on the absorption layer 4 of the reflective photomask blank 10, a positive chemically amplified resist (SEBP9012: manufactured by Shin-Etsu Chemical Co., Ltd.) was applied by spin coating to a thickness of 120 nm. ° C. for 10 minutes to form a resist film 7 .
Next, a predetermined pattern was drawn on the resist film 7 by an electron beam drawing machine (JBX3030: manufactured by JEOL Ltd.). After that, pre-bake treatment was performed at 110° C. for 10 minutes, and then development treatment was performed using a spray developing machine (SFG3000: manufactured by Sigma Meltec). Thereby, a resist pattern 71 was formed as shown in FIG.

Next, using the resist pattern 71 as an etching mask, the absorption layer 4 was patterned by dry etching mainly using a chlorine-based gas. As a result, an absorption pattern (absorption pattern layer) 41 was formed in the absorption layer 4, as shown in FIG.
Next, the resist pattern 71 was removed in a cleaning process, and a reflective photomask 20 of this example was produced as shown in FIG. In this embodiment, the absorption pattern 41 formed in the absorption layer 4 is a LS (line and space) pattern with a line width of 64 nm on the reflective photomask 20 for transfer evaluation. It includes a LS pattern with a line width of 200 nm and a 4 mm square absorption layer removal part for EUV reflectance measurement. In this example, the line width 64 nm LS pattern was designed in both the x direction and the y direction, as shown in FIG. 12, so that the influence of the projection effect due to EUV irradiation can be easily seen.

[Example 2]
The total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 95 atomic percent of the entire absorption layer 4, and the remaining 5 atomic percent is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.5 and the film density was 6.5 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Example 2 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Example 3]
The total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 80 atomic % of the entire absorption layer 4, and the remaining 20 atomic % is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.9 and the film density was 7.1 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Example 3 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Example 4]
The total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 95 atomic percent of the entire absorption layer 4, and the remaining 5 atomic percent is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed so as to have a film thickness of 18 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.6 and the film density was 8.5 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Example 4 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Example 5]
The absorption layer 4 is formed so that the total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 90 atomic percent of the entire absorption layer 4, and the remaining 10 atomic percent is tantalum (Ta). 4 was deposited. In addition, the absorption layer 4 was formed so as to have a film thickness of 39 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.4 and the film density was 4.4 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Example 5 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Example 6]
The total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 80 atomic % of the entire absorption layer 4 , and the remaining 15 atomic % is tantalum (Ta) and 5 atomic % is titanium ( Ti), the absorption layer 4 was formed. Also, the absorption layer 4 was formed so as to have a film thickness of 35 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.7 and the film density was 7.2 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Example 6 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Example 7]
The total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 80 atomic % of the entire absorption layer 4 , and the remaining 15 atomic % is tantalum (Ta) and 5 atomic % is tungsten ( W), the absorption layer 4 was formed. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.8 and the film density was 7.1 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Example 7 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Example 8]
The total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 72 atomic % of the entire absorption layer 4 , and the remaining 20 atomic % is tantalum (Ta) and 8 atomic % is tellurium ( Te), the absorption layer 4 was formed. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.8 and the film density was 7.4 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Example 8 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Example 9]
The absorption layer 4 is formed so that the total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 90 atomic percent of the entire absorption layer 4, and the remaining 10 atomic percent is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.7 and the film density was 7.0 g/cm ³ . Further, as shown in FIG. 13, tantalum oxide (Ta ₂ O ₅ ) of the barrier layer 51 is deposited to a thickness of 6 nm on the top and side surfaces of the patterned absorption pattern layer 41 by selective ALD (Area-selective deposition). filmed. A reflective photomask blank 10 and a reflective photomask 20 of Example 9 were produced in the same manner as in Example 1 except for forming the absorption layer 4 and the barrier layer 51 .

[Example 10]
The absorption layer 4 is formed so that the total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 90 atomic percent of the entire absorption layer 4, and the remaining 10 atomic percent is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.7 and the film density was 7.0 g/cm ³ . Further, as shown in FIG. 13, tantalum oxide (Ta ₂ O ₅ ) of the barrier layer 51 is deposited to a thickness of 3 nm on the top and side surfaces of the patterned absorption pattern layer 41 by selective ALD (Area-selective deposition). filmed. A reflective photomask blank 10 and a reflective photomask 20 of Example 10 were produced in the same manner as in Example 1 except for forming the absorption layer 4 and the barrier layer 51 .

[Example 11]
The absorption layer 4 is formed so that the total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 90 atomic percent of the entire absorption layer 4, and the remaining 10 atomic percent is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed so as to have a film thickness of 27 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.9 and the film density was 7.1 g/cm ³ . Further, as shown in FIG. 13, a barrier layer 51 was formed by natural oxidation to a thickness of 4 nm on the top and side surfaces of the patterned absorption pattern layer 41 . As for the composition of the barrier layer 51, the total content of tin (Sn) and oxygen (O) was 94 atomic %, and the remaining 6 atomic % was tantalum (Ta). A reflective photomask blank 10 and a reflective photomask 20 of Example 11 were produced in the same manner as in Example 1 except for forming the absorption layer 4 and the barrier layer 51 .

[Comparative Example 1]
The absorption layer 4 is formed so that the total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 90 atomic percent of the entire absorption layer 4, and the remaining 10 atomic percent is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.6 and the film density was 3.5 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Comparative Example 1 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Comparative Example 2]
An absorption layer 4 made of only tin (Sn) and oxygen (O) was formed. Also, the absorption layer 4 was formed so as to have a film thickness of 26 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.9 and the film density was 7.1 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Comparative Example 2 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

[Comparative Example 3]
The absorption layer 4 is formed so that the total content of tin (Sn) and oxygen (O) in the absorption layer 4 is 90 atomic percent of the entire absorption layer 4, and the remaining 10 atomic percent is tantalum (Ta). 4 was deposited. Also, the absorption layer 4 was formed to have a film thickness of 47 nm. Analysis of the absorption layer 4 revealed that the valence of tin (Sn) was 3.7 and the film density was 7.0 g/cm ³ . A reflective photomask blank 10 and a reflective photomask 20 of Comparative Example 3 were produced in the same manner as in Example 1 except for forming the absorption layer 4 .

Apart from the above-described examples and comparative examples, a reflective photomask having a conventional tantalum (Ta)-based absorption pattern layer was also compared as a reference example. For the reflective photomask blank, 40 sheets of a laminated film of a pair of silicon (Si) and molybdenum (Mo) are laminated on a synthetic quartz substrate having low thermal expansion characteristics in the same manner as in the above-described Examples and Comparative Examples. and a ruthenium (Ru) capping layer 3 with a thickness of 3.5 nm. The absorption layer 4 formed on the capping layer 3 is formed with a thickness of 2 nm on TaN with a thickness of 58 nm. is a film of TaO. In addition, in the same manner as in the above-described Examples and Comparative Examples, those having the absorption layer 4 patterned were used for the evaluation.

In the above examples and comparative examples, the film thicknesses of the absorption layer 4 and the barrier layer 51 were measured with a transmission electron microscope.

The evaluation items evaluated in this example will be described below.
(Reflectance)
In the examples and comparative examples described above, the reflectance Ra of the absorption pattern layer 41 region (see FIG. 12) of the manufactured reflective photomask 20 was measured with a reflectance measuring device using EUV light. In addition, the reflectance Rm of the reflecting portion 8 (see FIG. 12) where the absorption pattern layer 41 is not formed was measured with an EUV light reflectance measuring device. Thus, the OD values of the reflective photomasks 20 according to the example and the comparative example were calculated using Equation 1 described above.

(Wafer exposure evaluation)
An EUV exposure apparatus (NXE3300B: manufactured by ASML) was used to transfer and expose the absorption pattern 41 of the reflective photomask 20 produced in Examples and Comparative Examples onto a semiconductor wafer coated with an EUV positive chemically amplified resist. . At this time, the exposure amount was adjusted so that the LS pattern in the x direction shown in FIG. 12 was transferred as designed. Specifically, in this exposure test, the x-direction LS pattern (64 nm line width) shown in FIG. 12 was exposed on the semiconductor wafer so as to have a line width of 16 nm. Observation and line width measurement of the transferred resist pattern were carried out by an electron beam dimension measuring machine, and simulations were performed to compare how the HV bias value changes.
The HV bias value is the line width difference of the transfer pattern depending on the orientation of the mask pattern, that is, the difference between the line width in the horizontal (H) direction and the line width in the vertical (V) direction. The line width in the H direction indicates the line width of a linear pattern perpendicular to the surface formed by incident light and reflected light (hereinafter sometimes referred to as the “incident surface”), and the line width in the V direction indicates the line width on the incident surface. Line widths of parallel linear patterns are shown. That is, the line width in the H direction is the length in the direction parallel to the plane of incidence, and the line width in the V direction is the length in the direction orthogonal to the plane of incidence.

(hydrogen radical resistance)
Using 2.45 GHz MWP (Micro Wave Plasma: microwave plasma), in a hydrogen radical environment with a power of 1 kW and a hydrogen pressure of 0.36 mbar or less, the reflection type photo produced in Examples and Comparative Examples A mask 20 and a reflective photomask were installed. A change in film thickness of the absorption pattern layer 41 after the hydrogen radical treatment was confirmed using a transmission electron microscope. The measurement was performed with an LS pattern with a line width of 200 nm.
These evaluation results are shown in Table 1. In addition to the above evaluation results, Table 1 also shows the refractive index n and the extinction coefficient k.

Table 1 shows a comparison of OD values for each example and each comparative example. As described above, when the OD value is less than 1.0, sufficient contrast cannot be obtained, resulting in poor transfer performance. Therefore, if the OD value is 1.0 or more, it is determined that there is no problem with the transfer performance, and it is judged as "acceptable".
The OD value of a conventional reflective photomask having a tantalum (Ta)-based absorption pattern layer with a thickness of 60 nm (reflective photomask of the reference example) is 1.68, whereas the reflective photomask of Example 1 has an OD value of 1.68. The OD value of the mask 20 is 1.79, the OD value of the reflective photomask 20 of Example 2 is 1.55, the OD value of the reflective photomask 20 of Example 3 is 1.69, The OD value of the reflective photomask 20 of Example 4 is 1.53, the OD value of the reflective photomask 20 of Example 5 is 1.60, and the OD value of the reflective photomask 20 of Example 6 is is 1.64, the OD value of the reflective photomask 20 of Example 7 is 1.69, the OD value of the reflective photomask 20 of Example 8 is 1.66, and the reflective photomask of Example 9 is The OD value of the photomask 20 is 1.91, the OD value of the reflective photomask 20 of Example 10 is 1.49, and the OD value of the reflective photomask 20 of Example 11 is 1.67. there were. In the comparative examples, the OD value of the reflective photomask 20 of Comparative Example 1 is 0.76, the OD value of the reflective photomask 20 of Comparative Example 2 is 1.90, and the OD value of the reflective photomask 20 of Comparative Example 3 is 0.76. The OD value of the type photomask 20 was 3.12. That is, Comparative Example 1 had an OD value of less than 1.0 and did not meet the criteria for "acceptance".

Table 1 shows a comparison of HV bias between each example and each comparative example. As an evaluation method, the magnitude of the HV bias was evaluated as compared with the case of using an existing tantalum (Ta) mask. That is, when the LS pattern in the y direction is transferred as designed in a state in which the LS pattern in the x direction is adjusted to be transferred as designed, and the HV bias is smaller than in the case of using the existing tantalum (Ta) mask. was defined as "passed". Then, when the LS pattern in the x direction is adjusted to be transferred as designed, but the LS pattern in the y direction is not transferred as designed (when the LS pattern in the y direction is not resolved), or the HV bias is applied to the existing tantalum (Ta) mask was set as "failed".
The HV bias was 5.20 nm as a result of patterning with EUV light using a conventional reflective photomask having a tantalum (Ta)-based absorption pattern layer with a film thickness of 60 nm. In contrast, the HV bias of Example 1 is 2.35 nm, the HV bias of Example 2 is 2.10 nm, the HV bias of Example 3 is 2.25 nm, and the HV bias of Example 4 is 1 nm. .58 nm, the HV bias of Example 5 was 2.59 nm, the HV bias of Example 6 was 3.71 nm, the HV bias of Example 7 was 2.25 nm, and the HV bias of Example 8 was 2.25 nm. was 2.22 nm, the HV bias for Example 9 was 3.02 nm, the HV bias for Example 10 was 2.99 nm, and the HV bias for Example 11 was 3.24 nm. Also in the comparative examples, the HV bias of Comparative Example 1 was 1.07 nm, and the HV bias of Comparative Example 2 was 2.44 nm, both of which satisfied the "acceptance" criteria.
On the other hand, the HV bias of Comparative Example 3 was 5.74 nm, and as a result of patterning with EUV light, transferability deteriorated as compared with the conventional Ta-based photomask.

Table 1 shows the hydrogen radical resistance results of each example and each comparative example. When the film reduction rate of the absorption pattern layer 41 was 0.01 nm/s or less, it was evaluated as "◯", and when the film reduction was not confirmed, it was evaluated as "⊚", and the film reduction speed was 0. 01 nm/s to less than 0.1 nm/s was evaluated as "Δ", and the case where the film reduction rate was 0.1 nm/s or more was evaluated as "x". "◎" and "◯" are "passed", and "△" and "×" are unsuccessful.
As a result, the reflective photomasks 20 of Examples and Comparative Examples other than Comparative Examples 1 and 2, that is, Examples 1 to 11 and Comparative Example 3 satisfied the criteria of “acceptance” and Example 2 was a "Fail".

Table 1 shows the overall evaluation of OD value, HV bias and hydrogen radical resistance. For the reflective photomask 20 that can suppress or reduce the projection effect and has hydrogen radical resistance, "○" is written in the "judgment" column, and the projection effect could not be sufficiently suppressed or reduced, or hydrogen radical resistance The reflective photomask 20 not having the . Since the conventional Ta-based photomask is to be compared, it is marked with "Δ" in the column of "judgment".

Furthermore, the surface roughness (RMS) of Examples 1 to 11 and Comparative Examples 1 to 3 are also confirmed as a supplement. An atomic force microscope (AFM) was used for the measurement. In order to suppress the influence of the reflectance of EUV light, when the RMS is 0.6 nm or less as "pass", Examples and Comparative Examples other than Comparative Example 1, that is, Examples 1 to 11 and Comparative Examples 2 and 3 Reflective type The photomask 20 met the criteria of "acceptance", and Comparative Example 1 was "failed".

As a result, the absorption pattern layer 41 is formed of a material containing a total of 70 atomic % or more of tin (Sn) and oxygen (◯), the valence of tin (Sn) is 3.3 or more, and tantalum (Ta) is mixed at 5 atomic % or more and 20 atomic % or less, the film density of the absorption pattern layer 41 is 4.0 g/cm ³ or more, and the thickness of the absorption pattern layer 41 is within the range of 17 nm or more and 45 nm or less. If the reflective photomask is a reflective photomask, the optical density (OD value), HV bias, and hydrogen radical resistance are all good, so the projection effect can be reduced, the service life is long, and the transfer performance is high. became.

The reflective photomask according to the present invention can be suitably used for forming fine patterns by EUV exposure in the manufacturing process of semiconductor integrated circuits and the like.

DESCRIPTION OF SYMBOLS 1... Substrate 2... Reflective layer 3... Capping layer 4... Absorption layer 41... Absorption pattern (absorption pattern layer)
5 Barrier layer 51 Barrier layer 10 Reflective photomask blank 20 Reflective photomask 6 Rear conductive film 7 Resist film 71 Resist pattern 8 Reflective part

Claims (20)

A reflective photomask blank for producing a reflective photomask for pattern transfer using extreme ultraviolet light as a light source,
a substrate;
a reflective layer including a multilayer film formed on the substrate;
an absorbing layer formed on the reflective layer;
The absorption layer contains a total of 70 atomic % or more of tin (Sn) and oxygen (◯) , and the ratio (O/Sn) of the oxygen (O) and the tin (Sn) is 1.7 or more. formed of a material that is within the range of 3.5 or less ,
The tin (Sn) contained in the absorption layer has a valence of 3.3 or more,
5 atomic % or more and 20 atomic % or less of tantalum (Ta) is mixed in the absorption layer;
The absorption layer has a film density of 4.0 g/cm ³ or more,
The reflective photomask blank, wherein the film thickness of the absorption layer is in the range of 17 nm or more and 45 nm or less. 2. The reflective photomask blank according to claim 1, wherein the thickness of said absorption layer is in the range of 20 nm or more and 30 nm or less. The absorption layer is one selected from the group consisting of Pt, Te, In, Zr, Hf, Ti, W, Si, Cr, Mo, B, Pd, Ni, P, F, N, C, and H. 3. The reflective photomask blank according to claim 1, further comprising the above elements. The reflective photomask blank according to any one of claims 1 to 3, further comprising a barrier layer formed on said absorbing layer. The reflective photomask blank according to any one of claims 1 to 3, further comprising a barrier layer formed only on said absorption layer. The barrier layer is an oxide, nitride, boride, fluoride, oxynitride, oxyboride, and oxyfluoride of tantalum (Ta), or an oxide containing tantalum (Ta) and tin (Sn). 6. The reflective photomask according to claim 4 or 5 , containing at least one compound selected from the group consisting of a compound, a nitride, a boride, a fluoride, an oxynitride, an oxyboride, and an oxyfluoride. blank. The barrier layer is a group consisting of nitrides, borides, and fluorides of tantalum (Ta) , or nitrides, borides, and fluorides containing tantalum ( Ta) and tin (Sn). 6. The reflective photomask blank of claim 4 or 5 , containing one or more compounds selected from The reflective photomask blank according to any one of claims 4 to 7, wherein the barrier layer has a thickness of 5 nm or less. The reflective photomask blank according to any one of claims 1 to 8 , further comprising a capping layer formed between said reflective layer and said absorbing layer. A reflective photomask blank for producing a reflective photomask for pattern transfer using extreme ultraviolet light as a light source,
a substrate;
a reflective layer including a multilayer film formed on the substrate;
an absorbing layer formed on the reflective layer;
a barrier layer formed on the absorbing layer ;
The absorption layer is formed of a material containing a total of 70 atomic % or more of tin (Sn) and oxygen (◯),
The tin (Sn) contained in the absorption layer has a valence of 3.3 or more,
5 atomic % or more and 20 atomic % or less of tantalum (Ta) is mixed in the absorption layer;
The absorption layer has a film density of 4.0 g/cm ³ or more,
The film thickness of the absorption layer is in the range of 17 nm or more and 45 nm or less ,
The barrier layer is an oxide, nitride, boride, fluoride, oxynitride, oxyboride, and oxyfluoride of tantalum (Ta), or an oxide containing tantalum (Ta) and tin (Sn). a reflective photomask blank containing one or more compounds selected from the group consisting of phosphates, nitrides, borides, fluorides, oxynitrides, oxyborides, and oxyfluorides . A reflective photomask for pattern transfer using extreme ultraviolet light as a light source,
a substrate;
a reflective layer including a multilayer film formed on the substrate;
an absorption pattern layer formed with an absorption pattern that serves as a transfer pattern for a transferred state on the reflective layer;
The absorption pattern layer contains a total of 70 atomic % or more of tin (Sn) and oxygen (◯) , and the ratio (O/Sn) of the oxygen (O) and the tin (Sn) is 1.7. formed of a material that is within the range of 3.5 or more ,
The tin (Sn) contained in the absorption pattern layer has a valence of 3.3 or more,
5 atomic % or more and 20 atomic % or less of tantalum (Ta) is mixed in the absorption pattern layer,
The absorption pattern layer has a film density of 4.0 g/cm ³ or more,
A reflective photomask, wherein the film thickness of the absorption pattern layer is in the range of 17 nm or more and 45 nm or less. 12. The reflective photomask according to claim 11 , wherein the film thickness of said absorption pattern layer is in the range of 20 nm or more and 30 nm or less. The absorbing pattern layer is selected from the group consisting of Pt, Te, In, Zr, Hf, Ti, W, Si, Cr, Mo, B, Pd, Ni, P, F, N, C, and H. 13. The reflective photomask according to claim 11 , further comprising at least one element. 14. The reflective photomask according to any one of claims 11 to 13 , further comprising a barrier layer formed on at least one of a top surface and a side surface of said absorption pattern layer. further comprising barrier layers formed on top and side surfaces of the absorbing pattern layer;
When the thickness of the barrier layer formed on the upper surface of the absorption pattern layer is defined as DT, and the thickness of the barrier layer formed on the side surface of the absorption pattern layer is defined as DS, the DS is the DT. Any one of claims 11 to 13, wherein the DT is in the range of 0.5 to 0.8 times the DS, or the DT is in the range of 0.5 to 0.8 times the DS The reflective photomask described in . The barrier layer is an oxide, nitride, boride, fluoride, oxynitride, oxyboride, and oxyfluoride of Ta, or an oxide, nitride, boride, fluoride containing Ta and Sn. 16. The reflective photomask according to claim 14 or 15 , containing at least one compound selected from the group consisting of oxides, oxynitrides, oxyborides, and oxyfluorides. The barrier layer is at least one compound selected from the group consisting of nitrides , borides, and fluorides of Ta , or nitrides, borides, and fluorides containing Ta and Sn. The reflective photomask according to claim 14 or 15 , containing 18. The reflective photomask according to any one of claims 14 to 17, wherein the thickness of the barrier layer is 5 nm or less. The reflective photomask according to any one of claims 11 to 18 , further comprising a capping layer formed between said reflective layer and said absorbing pattern layer. A reflective photomask for pattern transfer using extreme ultraviolet light as a light source,
a substrate;
a reflective layer including a multilayer film formed on the substrate;
an absorption pattern layer in which an absorption pattern that serves as a transfer pattern for a transferred state is formed on the reflective layer;
a barrier layer formed on at least one of a top surface and a side surface of the absorption pattern layer ;
The absorption pattern layer is formed of a material containing a total of 70 atomic % or more of tin (Sn) and oxygen (◯),
The tin (Sn) contained in the absorption pattern layer has a valence of 3.3 or more,
5 atomic % or more and 20 atomic % or less of tantalum (Ta) is mixed in the absorption pattern layer,
The absorption pattern layer has a film density of 4.0 g/cm ³ or more,
The film thickness of the absorption pattern layer is in the range of 17 nm or more and 45 nm or less ,
The barrier layer is an oxide, nitride, boride, fluoride, oxynitride, oxyboride, and oxyfluoride of Ta, or an oxide, nitride, boride, fluoride containing Ta and Sn. A reflective photomask containing at least one compound selected from the group consisting of oxides, oxynitrides, oxyborides, and oxyfluorides .

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