JP2012038787A - Method of manufacturing reflective mask blank having pseudo phase defect, and method of manufacturing reflective mask having pseudo phase defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a reflective mask blank having a pseudo phase defect and a method of manufacturing a reflective mask having a pseudo phase defect capable of forming several kinds of concave design defects with different depths on the same substrate while improving size accuracy and position accuracy, without using expensive and high definition electron beam lithography equipment a plurality of times depending on the number of kinds of depths of the design defects.SOLUTION: All patterns of several kinds of concave design defects with different depths are collectively formed on a hard mask formed on a substrate. Thereafter, the substrate is sequentially etched while masking the hard mask pattern.

Description

  The present invention relates to a reflective mask for EUV exposure for transferring a mask pattern onto a wafer using extreme ultraviolet light (hereinafter referred to as EUV), and more specifically, inspection and evaluation of phase defects. The present invention relates to a method for manufacturing a reflective mask blank having a pseudo phase defect and a method for manufacturing a reflective mask having a pseudo phase defect.

  In recent years, with the miniaturization of semiconductor devices in the semiconductor industry, EUV lithography, which is an exposure technique using EUV light, is promising.

  Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, and specifically, light having a wavelength of about 0.2 to 100 nm. As a mask used in this EUV lithography, for example, a reflective mask described in Patent Document 1 has been proposed.

  Such a reflective mask has at least a reflective layer made of a multilayer film that reflects EUV light on the main surface of the substrate, and a partial absorption layer that absorbs EUV light formed on the reflective layer. The absorber pattern is formed by removing the target.

  The EUV light incident on the reflective mask mounted on the EUV exposure machine is absorbed in a part where the absorber is present, and is reflected by the reflective layer in a part where there is no absorber, and the optical image is reflected on the transfer target through the reflective optical system. Transcribed.

The above-described reflective mask substrate has a low thermal expansion coefficient in order to maintain high pattern position accuracy, and further has high smoothness and flatness in order to obtain high reflectance and transfer accuracy. A substrate excellent in resistance to a cleaning solution used for cleaning in a mask manufacturing process is required. For example, glass substrates such as quartz glass, SiO ₂ —TiO ₂ low thermal expansion glass, crystallized glass on which β quartz solid solution is deposited, etc. Is used.

  And what formed said reflection layer, absorption layer, etc. in the main surface of the above board | substrates is called reflection type mask blanks.

  The reflective mask is obtained by partially removing the absorption layer of the reflective mask blank to form an absorber pattern that becomes a mask pattern.

  In order to form the absorber pattern, for example, a resist is formed on the surface side (surface on which the absorption layer is formed) of the reflective mask blank, and this resist is formed into a mask pattern by electron beam drawing or the like. Using the mask as a mask, the absorption layer is etched to obtain a desired absorber pattern.

  Here, for example, if there is a step due to scratches or adhesion of foreign matter on the substrate surface, the layer structure of the reflective layer formed thereon is destroyed, causing a phase change in the EUV light reflected by the reflective layer. End up. This phase change causes the positional accuracy and contrast of the transferred pattern to deteriorate, and such a defect that causes a phase change that affects the transfer is called a phase defect (Patent Document 2).

  For example, in the case of EUV light having a wavelength of 13.5 nm, a step of only 3.4 nm (≈1 / 4 wavelength) can be a phase defect of 180 degrees.

  For this reason, in the reflective mask for EUV exposure, the phase defect control of the reflective mask blanks is the most important issue.

  In reflective mask blanks, it is ideal to eliminate this phase defect, but in reality it is difficult to eliminate this, and phase defect correction technology, phase defect transferability and inspection sensitivity Is an important technical development issue in EUV lithography (Patent Document 3).

JP-A-63-201656 JP 2004-289110 A JP-T 2002-532738

  In order to inspect and evaluate the phase defect as described above, a reflective mask blank and a reflective mask in which a step (design defect) having a predetermined size as a source of the phase defect is formed at a predetermined position of the substrate. It is necessary to prepare.

  The step can be obtained, for example, by forming a concave design defect on the main surface of the substrate of the reflective mask blank. In addition to the form in which the design defects are formed in the same substrate with several different opening areas, there is a demand for forms in which the design defects are formed in several different depths.

  Here, several kinds of concave design defects with different opening areas can be easily formed on the same substrate by making the drawing pattern into a desired opening pattern using, for example, a conventional lithography technique using electron beam drawing. can do.

  However, for several types of concave design defects of different depths, it is usually not possible to have one type of depth for each forming step, and several types of concave design defects of different depths are not identical. In order to create the substrate, it was necessary to perform a plurality of forming steps.

  For example, as shown in FIGS. 7 to 9, in order to manufacture a reflective mask blank 100 having concave design defects of two different depths on the same substrate, the main surface of the substrate 102 is used in the conventional method. First, a resist pattern 112A for forming a concave design defect 103A having the first depth is formed (FIG. 7B), and the substrate 102 is formed in a predetermined pattern using the resist pattern 112A as a mask. After etching to the first depth (FIG. 7C) and removing the resist pattern 112A (FIG. 7D), a resist for forming the concave design defect 103B having the second depth A pattern 112B is formed (FIG. 8E), the substrate 102 is etched to a predetermined second depth using the resist pattern 112B as a mask (FIG. 8F), and the resist pattern 112B is removed (FIG. 8F). (G)) After that, the reflective layer 104 is formed on the substrate 102 so as to cover the concave design defects 103A and 103B (FIG. 8H), and the absorption layer 105 is formed thereon (FIG. 9). (I)) was a complicated and long process.

  The reflective mask 110 having concave design defects of two different depths can be obtained by partially removing the absorption layer 105 of the reflective mask blank 100 to form the absorber pattern 105A. (FIG. 9 (j)).

  In the conventional method described above, in order to form a concave design defect of three or more different depths, the above-described series of steps of resist pattern formation, substrate etching, and resist pattern removal are performed using the necessary depth types. Will be repeated according to the number of.

  However, since the design defect pattern as described above requires a pattern smaller than the absorber pattern of the reflective mask, it is necessary to use a high-definition electron beam drawing machine for the pattern formation. When a high-definition electron beam drawing machine is used for forming a resist pattern a plurality of times as described above, the manufacturing cost is very high.

  In addition, the above minute patterns have low dimensional stability due to the stability of the electron beam in the electron beam drawing machine and the reproducibility limit of the development process, and it is necessary to form a resist pattern multiple times. In the conventional method, a difference in dimensional finish has occurred between patterns having different depths.

  Further, in the conventional method that requires multiple times of resist pattern formation, positional deviation occurs between design defect patterns having different depths due to the limit of alignment accuracy in an electron beam lithography machine. The positional relationship between the absorber pattern and the design defect differs depending on the depth of the design defect, which makes it difficult to perform inspection and evaluation with high accuracy.

  The present invention has been made in view of the above problems, and an object of the present invention is to use an expensive high-definition electron beam drawing machine a plurality of times depending on the number of types of design defect depths. Without producing a reflective mask blank having a quasi-phase defect capable of forming several types of concave design defects of different depths with improved dimensional accuracy and positional accuracy on the same substrate, and It is an object of the present invention to provide a method for manufacturing a reflective mask having a quasi phase defect.

  As a result of various studies, the present inventor collectively formed all the patterns of concave design defects of several different depths on a hard mask formed on a substrate, and then masked the hard mask pattern. However, the present invention has been completed by finding that the above problems can be solved by sequentially etching the substrate.

  That is, the invention according to claim 1 of the present invention is formed on the main surface of the substrate so as to cover the substrate, the concave design defect formed on the main surface of the substrate, and the design defect. A method of manufacturing a reflective mask blank for EUV exposure, comprising at least a reflective layer comprising a multilayer film and an absorption layer formed on the reflective layer, wherein a plurality of reflective mask blanks are formed on the main surface of the substrate. A thin film pattern forming step for forming a thin film pattern having an opening; and a protective film pattern forming step for exposing a desired portion of the thin film pattern and forming a protective film pattern covering another portion on the thin film pattern; A step of forming the design defect by etching the substrate using the protective film pattern and the exposed thin film pattern as an etching mask; and removing the protective film pattern A protective film pattern removing step, a thin film pattern removing step of removing the thin film pattern, a reflective layer forming step of forming the reflective layer on the main surface of the substrate so as to cover the design defect, and the reflective An absorption layer forming step of forming the absorption layer on a layer, and a series of steps of the protective film pattern forming step, the design defect forming step, and the protective film pattern removing step, A plurality of design defects having different depths are formed on the substrate by changing the position of the thin film pattern to be coated with and changing the etching depth of the substrate and repeating the necessary number of times. It is a manufacturing method of a reflective mask blank having a quasi phase defect.

  In the invention according to claim 2 of the present invention, the thin film pattern that serves as a mask for etching the substrate is a thin film containing metal, metal oxide, or metal nitride processed into a pattern. The method for producing a reflective mask blank having a quasi-phase defect according to claim 1, wherein

  In the invention according to claim 3 of the present invention, the protective film pattern is obtained by processing an ultraviolet resist or an electron beam resist into a pattern. It is a manufacturing method of the reflective mask blanks which have the following pseudo phase defects.

  Moreover, the invention according to claim 4 of the present invention is the absorbing layer of the reflective mask blank obtained by using the manufacturing method of the reflective mask blank having the pseudo phase defect according to any one of claims 1 to 3. Is partially removed, and an absorber pattern is formed so that the reflective layer is exposed at a desired site. A method for producing a reflective mask having a quasi-phase defect.

  According to the present invention, since all patterns of design defects are collectively formed on a thin-film hard mask formed on a substrate, an expensive, high-definition electron beam lithography machine can be used even if the types of depths increase. The number of processes using the mask is only one, and reflective mask blanks and reflective masks having concave design defects of several different depths on the same substrate can be manufactured at low cost.

  In addition, according to the present invention, all patterns of design defects are collectively formed on the hard mask formed on the substrate, so that, for example, all the patterns can be collectively drawn in one step, and the electron beam can be drawn once. Since all the patterns can be developed in one step in this process, the dimensional finish of all the patterns is more stable than the conventional method that required multiple resist pattern formation processes, and as a result, a concave design with improved dimensional accuracy. Reflective mask blanks and reflective masks having defects can be produced.

  In addition, according to the present invention, since all patterns of design defects are collectively formed on a hard mask formed on a substrate, for example, all patterns can be collectively drawn in one step, so that a plurality of patterns can be drawn. A reflective mask blank and a reflective mask having a concave design defect with improved relative positional accuracy between patterns can be manufactured as compared with the conventional method that required a resist pattern forming process twice.

It is a schematic sectional drawing which shows the example of the reflection type mask blank which has a quasi phase defect based on this invention. It is a schematic sectional drawing which shows the example of the reflective mask which has a quasi phase defect based on this invention, (a) shows the example where a design defect is located in the approximate center between absorber patterns, (b) shows a design defect. The example which adjoined to the absorber pattern is shown. It is a typical process figure showing an example of a manufacturing method of a reflective mask which has a quasi phase defect concerning the present invention. FIG. 4 is a schematic process diagram illustrating an example of a method for manufacturing a reflective mask having a pseudo phase defect according to the present invention following FIG. 3. FIG. 5 is a schematic process diagram illustrating an example of a manufacturing method of a reflective mask having a pseudo phase defect according to the present invention following FIG. 4. FIG. 6 is a schematic process diagram illustrating an example of a manufacturing method of a reflective mask having a pseudo phase defect according to the present invention following FIG. 5. It is typical process drawing which shows the example of the manufacturing method of the reflection type mask which has the conventional pseudo phase defect. FIG. 8 is a schematic process diagram illustrating an example of a manufacturing method of a reflective mask having a conventional quasi phase defect following FIG. 7. FIG. 9 is a schematic process diagram illustrating an example of a manufacturing method of a reflective mask having a conventional quasi phase defect following FIG. 8.

(Reflective mask blanks and reflective masks)
First, a reflective mask blank and a reflective mask according to the present invention will be described.

  FIG. 1 is a schematic sectional view showing an example of a reflective mask blank having a pseudo phase defect according to the present invention.

  As shown in FIG. 1, in the reflective mask blank 1 having a quasi phase defect according to the present invention, concave design defects 3 </ b> A and 3 </ b> B having different depths are formed on the main surface of the substrate 2. A reflective layer 4 is formed on the main surface so as to cover the design defects 3A and 3B, and an absorbing layer 5 is formed on the reflective layer 4.

  FIG. 2 is a schematic cross-sectional view showing an example of a reflective mask having a quasi-phase defect according to the present invention, in which (a) shows an example in which a design defect is located at the approximate center between absorber patterns, and (b) Shows an example in which the design defect is close to the absorber pattern.

  The reflective mask 10 having a quasi-phase defect according to the present invention partially removes the absorption layer 5 of the reflective mask blank 1 and forms the absorber pattern 5A so that the reflective layer 4 is exposed at a desired portion. As shown in FIG. 2A, in addition to the embodiment in which the design defect is located at the approximate center between the absorber patterns, for example, as shown in FIG. There are embodiments close to the absorber pattern.

  In addition, a form in which a part of the design defect is hidden under the absorber pattern and a form in which the design defect is completely hidden under the absorber pattern are also included in the reflective mask having a pseudo phase defect according to the present invention.

  The purpose of manufacturing the reflective mask in which the positional relationship between the design defect and the absorber pattern is changed as described above is to evaluate the influence of the phase change caused by each design defect on the transfer in EUV exposure. .

  The shape of the design defect as described above is mainly a dot or a line, and the opening width is, for example, in the range of about 25 nm to 200 nm. The depth of the design defect is, for example, about 1 nm to 20 nm. The shape and depth of the design defect can be measured with an atomic force microscope (AFM) or the like.

  The absorber pattern is mainly a line and space pattern or a hole array pattern. For example, the line width of the line and space pattern is 64 nm to 128 nm.

Next, other elements constituting the reflective mask blank and the reflective mask according to the present invention will be described.
(substrate)
The substrate 2 constituting the reflective mask of the present invention has a low thermal expansion coefficient in order to maintain high pattern position accuracy, and has high smoothness and flatness in order to obtain high reflectivity and transfer accuracy. A glass substrate having excellent resistance to a cleaning liquid used for cleaning in a mask manufacturing process is preferable, and a glass substrate such as quartz glass, SiO2-TiO2 low thermal expansion glass, crystallized glass on which β-quartz solid solution is deposited, or silicon is used. You can also.

The substrate 2 preferably has a smooth surface of 0.2 nmRms or less and a flatness of 100 nm or less in order to obtain a high reflectance and transfer accuracy. As the flatness of the mask blank, for example, 50 nm or less is required in the pattern region.
(Reflective layer)
The reflective layer 4 is made of a material that reflects EUV light used for EUV exposure with high reflectivity, and a multilayer film composed of a Mo (molybdenum) layer and a Si (silicon) layer is often used. For example, 2.8 nm. Examples include a reflective layer made of a multilayer film in which 40 layers each of a Mo layer having a thickness and a Si layer having a thickness of 4.2 nm are stacked. Other than that, as a material capable of obtaining a high reflectance in a specific wavelength range, Ru / Si, Mo / Be, Mo compound / Si compound, Si / Nb periodic multilayer film, Si / Mo / Ru periodic multilayer film, Si / Mo / Ru / Mo periodic multilayer film and Si / Ru / Mo / Ru periodic multilayer film can also be used. However, the optimum film thickness varies depending on the material. In the case of a multilayer film composed of an Mo layer and an Si layer, an Si layer is first formed using an Si target by ion beam sputtering, and then an Mo layer is formed using an Mo target. 30 to 60 cycles, preferably 40 cycles, to obtain a multilayer reflective layer. As described above, in order to reflect EUV light with a high reflectance, the reflectance of the reflective layer 4 when 13.5 nm EUV light is incident at an incident angle of 6.0 degrees usually indicates 60% or more. Is set to
(Capping layer)
In order to increase the reflectance of the reflective layer 4, it is preferable to use a Mo layer having a high refractive index as the uppermost layer. As a protective layer, a capping layer is provided by depositing Si or Ru (ruthenium) by a sputtering method or the like. For example, when Si is used as the capping layer, the uppermost layer of the reflective layer 4 is provided with a thickness of 11 nm.
(Buffer layer)
In order to prevent damage to the lower reflective layer 4 when pattern-etching the absorbing layer 5 that absorbs EUV light used for EUV exposure by a method such as dry etching, the reflective layer 4 and the absorbing layer 5 A buffer layer may be provided between the two. As the material of the buffer layer, SiO ₂ , Al ₂ O ₃ , Cr, CrN or the like is used. When CrN is used, it is preferable to form a CrN film with a film thickness of about 5 nm to 15 nm on the reflective layer in a N ₂ gas atmosphere using a Cr target by RF magnetron sputtering.
(Absorption layer)
The material of the absorption layer 5 that forms a mask pattern and absorbs EUV light is selected from Ta, TaN, TaB, TaBN, and other materials containing Ta as the main component, Cr, Cr as the main component, N, O, and C Such a material containing at least one component is used in a thickness range of about 20 nm to 100 nm.
(Hard mask layer)
A hard mask layer may be provided on the absorption layer 5 as an etching mask for the absorption layer. As a material for the hard mask layer, it is necessary to use a material that is resistant to the etching of the absorption layer 5 and suitable for fine processing according to the transfer pattern of the reflective mask. For example, chromium (Cr), zirconium (Zr), hafnium (Hf), and nitrides and oxides thereof.

  The material of the hard mask layer is preferably the same material as the buffer layer. In this case, after the absorption layer 5 is etched, the hard mask layer and the buffer layer can be removed in the same process.

  The thickness of the hard mask layer is, for example, 5 nm to 15 nm, although it depends on the etching resistance of the material and the processing accuracy according to the size of the transfer pattern.

As the hard mask layer, for example, a hard mask layer made of CrN can be provided by sputtering Cr in a mixed gas atmosphere of Ar and nitrogen.
(Conductive layer)
A conductive layer may be formed on the other surface (back surface side) facing the reflective layer 4 provided on the main surface of the substrate 2. This conductive layer is provided to electrostatically attract the back surface of the reflective mask. This conductive layer is a thin film such as a metal or metal nitride exhibiting conductivity. For example, chromium (Cr) or chromium nitride (CrN) is formed to a thickness of about 20 nm to 150 nm.
(Manufacturing method of reflective mask blanks and manufacturing method of reflective mask)
Next, a method for manufacturing a reflective mask blank having a pseudo phase defect according to the present invention and a method for manufacturing a reflective mask having a pseudo phase defect will be described.

  3 to 6 are schematic process diagrams showing an example of a method for manufacturing a reflective mask having a pseudo phase defect according to the present invention.

  First, as shown in FIG. 3A, a surface-polished substrate 2 is prepared, and a hard mask layer 11 is formed on the main surface (FIG. 3B).

  The hard mask layer 11 can be a thin film containing any one of metal, metal oxide, or metal nitride. For example, the hard mask layer 11 is made of a metal such as Cr (chromium) on the main surface of the substrate 2. It can be formed by sputtering film formation with a thickness of about 5 nm to 20 nm.

  Next, as shown in FIG. 3C, a positive electron beam resist 12 is formed on the hard mask layer 11, and an opening having a desired shape and size is formed at a predetermined position by electron beam drawing. A resist pattern 12A is formed (FIG. 3D), and then the hard mask layer 11 exposed in the opening of the resist pattern 12A is etched (FIG. 4E), and then the resist pattern 12A is removed to obtain a desired pattern. A hard mask pattern 11A in which all the design defect patterns are collectively formed is obtained (FIG. 4F).

  Here, in the conventional method, only a design defect pattern corresponding to one kind of depth can be formed in one pattern forming process, but in the present invention, all kinds of design defect patterns can be formed in one pattern forming process. Design defect patterns corresponding to the depth are collectively formed.

  Therefore, in the present invention, the conventional pattern formation process by electron beam drawing is not required, and an expensive high-definition electron beam drawing machine is used even if the types of depth increase. The number of steps is one, and reflective mask blanks and reflective masks having concave design defects of several different depths on the same substrate can be manufactured at low cost.

  In addition, since all the patterns of design defects are collectively formed on the hard mask, for example, all the patterns can be drawn in an electron beam in one step, and all the patterns can be developed in one step. Therefore, the dimensional finish of all the patterns is more stable than the conventional method that required a plurality of resist pattern forming steps, and as a result, the reflective mask blank and the reflective mask having a concave design defect with improved dimensional accuracy. Can be manufactured.

  In addition, since all patterns of design defects are collectively formed on a hard mask, for example, since all the patterns can be collectively drawn in a single step, a conventional resist pattern forming step is required. The reflective mask blanks and the reflective mask having a concave design defect with improved relative positional accuracy between the patterns can be manufactured as compared with the above method.

  In addition to the design defect pattern, an alignment mark pattern for aligning and forming the absorber pattern of the reflective mask may be formed on the hard mask pattern. By drawing both the alignment mark and design defect patterns together in an electron beam, reflective mask blanks with improved relative positional accuracy between the patterns can be manufactured. By using this alignment mark, This is because a reflective mask with improved relative positional accuracy between the absorber pattern and the design defect can be manufactured.

  Next, as shown in FIG. 4G, a protective film pattern 13A is formed on the hard mask pattern 11A so as to expose a desired portion of the hard mask pattern 11A and cover other portions.

  In the protective film pattern 13A, for example, an ultraviolet resist or an electron beam resist is applied and formed on the main surface of the substrate with a thickness of about 300 nm to 500 nm, and a desired portion is opened by ordinary ultraviolet light or electron beam lithography. It can be formed as a pattern.

  Next, as shown in FIG. 4H, the substrate 2 is etched by a predetermined amount using the protective film pattern 13A and the exposed hard mask pattern 11A as an etching mask to form a design defect 3A having a desired depth. . For the etching, for example, a buffered hydrofluoric acid solution adjusted to a low concentration is used in order to reduce the etching rate. The reason for reducing the etching rate is to facilitate the control of the etching depth of about 1 nm to 20 nm.

  In FIG. 4 (h), only one design defect is shown for ease of explanation, but usually, a plurality of design defects having the same design value are formed collectively.

  Next, as shown in FIG. 5 (i), the protective film pattern 13A is removed, and then, as shown in FIG. 5 (j), the position of covering the hard mask pattern 11A is changed to form the protective film pattern 13B. Then, the depth at which the substrate 2 is etched is changed to a depth different from that in the first design defect formation step (FIG. 4H), thereby making the design different in depth from the design defect 3A. A defect 3B is formed (FIG. 5 (k)). Thereafter, as shown in FIG. 5L, the protective film pattern 13B is removed.

As described above, the design defects 3A and 3B having two kinds of depths can be formed by the steps so far. Here, in FIGS. 3A to 5L, a method of forming the design defects 3A and 3B having two kinds of depths is shown.
A series of the protective film pattern forming step (for example, FIG. 5 (j)), the design defect forming step (for example, FIG. 5 (k)), and the protective film pattern removing step (for example, FIG. 5 (l)). It is possible to form design defects of a plurality of different depths on the substrate 2 by repeating the process as many times as necessary by changing the position where the protective film pattern is covered and changing the depth of etching the substrate. it can.

Further, by repeating the above-described series of processes N times, it is theoretically possible to form design defects of 2 ^N −1 different depths at the maximum. For example, as shown in Table 1, seven types of design defects having different depths can be formed by repeating the above-described series of steps three times.

  Therefore, according to the manufacturing method of the present invention, design defects having a plurality of depths can be formed more efficiently than the conventional method.

上述のようにして、所望の設計欠陥を全て形成した後は、図６（ｍ）に示すように、ハードマスクパターン１１Ａを除去し、露出させた基板２の主面の上に、設計欠陥３Ａ、３Ｂを被覆するようにして反射層４を形成し（図６（ｎ））、さらに反射層４の上に吸収層５を形成して（図６（ｏ））、本発明に係る擬似位相欠陥を有する反射型マスクブランクス１を得る。

After all the desired design defects are formed as described above, the hard mask pattern 11A is removed and the design defects 3A are formed on the exposed main surface of the substrate 2 as shown in FIG. 3B is formed so as to cover 3B (FIG. 6 (n)), and the absorbing layer 5 is further formed on the reflective layer 4 (FIG. 6 (o)), and the pseudo phase according to the present invention is formed. A reflective mask blank 1 having defects is obtained.

  Although omitted in FIG. 6, a capping layer or a buffer layer may be formed between the reflective layer 4 and the absorption layer 5.

  Finally, the absorber layer 5 of the reflective mask blank 1 is partially removed to form an absorber pattern 5A so that the reflective layer 4 is exposed at a desired site (FIG. 6 (p)). A reflective mask 10 having such a quasi phase defect is obtained.

  As mentioned above, although the manufacturing method of the reflective mask blank which has a pseudo phase defect which concerns on this invention, and the manufacturing method of the reflective mask which has a pseudo phase defect were demonstrated, this invention is not limited to the said embodiment. . The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration and exhibits the same function and effect regardless of the case. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
As a substrate, an optically polished 6-inch square (0.25-inch thick) synthetic quartz substrate was used, and a hard mask layer was formed by sputtering Cr on the main surface to a thickness of 10 nm. Then, a positive type electron beam resist (ZEP520, manufactured by Nippon Zeon Co., Ltd.) is formed on the hard mask layer, and a desired design defect pattern is formed using a spot beam electron beam drawing machine having an acceleration voltage of 100 kV. An alignment mark pattern was formed, and then a Cr thin film pattern in which the above patterns were collectively formed was formed by dry etching using a chlorine-based gas, and then the resist pattern was stripped.

  Next, an ultraviolet resist (manufactured by Tokyo Ohka Kogyo Co., Ltd., THMR-IP3500) is formed with a thickness of 400 nm on the Cr thin film pattern, and the first type of depth (1 nm) is first obtained using a laser drawing machine. The plate is made so that only the design defect pattern is exposed, and the exposed design defect pattern is wet-etched with diluted buffered hydrofluoric acid solution to form a design defect having a depth of 1 nm. Removed with aqueous sulfuric acid.

  Next, the above-mentioned ultraviolet resist is again formed to a thickness of 400 nm on the Cr thin film pattern from which the resist has been removed, and a design defect having a second depth (1.5 nm) is formed using a laser drawing machine. The plate is made so that only the pattern is exposed, and the exposed design defect pattern is wet-etched with a diluted buffered hydrofluoric acid solution to form a design defect with a depth of 1.5 nm. Removed with aqueous sulfuric acid.

  After that, in the same manner as described above, a series of steps of UV resist plate making, substrate wet etching, and UV resist removal is performed by changing the position of the Cr thin film pattern covered with the UV resist pattern and changing the depth of etching the substrate. By repeating three times, design defects having depths of 2.0 nm, 3.0 nm, and 5.0 nm were further formed.

  Next, on the Cr thin film pattern from which the resist was removed, the above-mentioned ultraviolet resist was again formed to a thickness of 400 nm, and the plate was made using a laser drawing machine so that only the alignment mark pattern was exposed and exposed. The alignment mark pattern is wet-etched with a buffered hydrofluoric acid solution to form a cross-shaped alignment mark having a total length of 2 mm, a line width of 2 μm, and a depth of 500 nm. Then, the Cr thin film pattern was removed with an aqueous cerium ammonium nitrate solution.

  Next, on the exposed substrate, an ion beam sputtering method is used to form a Si film with a Si target with a thickness of 4.2 nm, followed by a Mo target with a Mo film with a thickness of 2.8 nm. A reflective layer composed of a multilayer film of Mo and Si was formed by laminating 40 periods as one period, and then a capping layer was formed by depositing an Si film on the outermost Mo film to a thickness of 11 nm.

Next, a CrN film is formed as a buffer layer to a thickness of 10 nm on the Si film by RF magnetron sputtering in a N ₂ atmosphere using a Cr target, and then on the CrN film. In addition, a TaN film is formed with a thickness of 70 nm in a mixed gas atmosphere of Ar and nitrogen by a DC magnetron sputtering method, and an absorption layer that absorbs EUV light is formed. A reflective mask blank was obtained.

Next, using this reflective mask blank, an electron beam resist is applied, alignment drawing is performed using the above alignment mark with an electron beam drawing apparatus, and an absorber pattern for a predetermined positional relationship with the above design defect is obtained. A resist pattern was formed. Next, the TaN absorption layer is dry-etched with Cl ₂ gas, and the CrN buffer layer is dry-etched with a mixed gas of Cl ₂ and oxygen to expose the capping layer, and the resist pattern is stripped. A reflective mask according to the above was obtained.

DESCRIPTION OF SYMBOLS 1 Reflective mask blanks 2 Substrate 3A, 3B Design defect 4 Reflective layer 5 Absorbing layer 5A Absorber pattern 10 Reflective mask 11 Hard mask layer 11A Hard mask pattern 12 Electron resist 12A Resist pattern 13A, 13B Protective film pattern 100 Reflective type Mask blank 102 Substrate 103A, 103B Design defect 104 Reflective layer 105 Absorbing layer 105A Absorber pattern 110 Reflective mask 112A, 112B Resist pattern

Claims (4)

A substrate, a concave design defect formed on the main surface of the substrate, a reflective layer made of a multilayer film formed on the main surface of the substrate so as to cover the design defect, and an upper surface of the reflective layer A reflective mask blank for EUV exposure having at least an absorption layer formed on
A thin film pattern forming step of forming a thin film pattern having a plurality of openings on the main surface of the substrate;
A protective film pattern forming step of exposing a desired part of the thin film pattern and forming a protective film pattern covering the other part on the thin film pattern;
A design defect forming step of forming the design defect by etching the substrate using the protective film pattern and the exposed thin film pattern as an etching mask;
A protective film pattern removing step for removing the protective film pattern;
A thin film pattern removing step of removing the thin film pattern;
A reflective layer forming step of forming the reflective layer on the main surface of the substrate so as to cover the design defects;
An absorption layer forming step of forming the absorption layer on the reflective layer,
Depth of changing the position of the thin film pattern covered with the protective film pattern and etching the substrate in a series of steps of the protective film pattern forming step, the design defect forming step, and the protective film pattern removing step And repeat as many times as necessary,
A manufacturing method of a reflective mask blank having a pseudo phase defect, wherein a plurality of design defects having different depths are formed on the substrate.   2. The thin film pattern serving as a mask for etching the substrate is a thin film containing any one of metal, metal oxide, and metal nitride processed into a pattern. Of manufacturing a reflective mask blank having a quasi-phase defect.   The method for producing a reflective mask blank having a pseudo phase defect according to claim 1, wherein the protective film pattern is obtained by processing an ultraviolet resist or an electron beam resist into a pattern. . The said absorption layer of the reflective mask blanks obtained using the manufacturing method of the reflective mask blank which has a quasi phase defect in any one of Claims 1-3 is partially removed, The said part in the desired part A method of manufacturing a reflective mask having a quasi-phase defect, wherein an absorber pattern is formed so that a reflective layer is exposed.

Images