JP2013065739A - Reflection mask, reflection mask blank, and manufacturing method of reflection mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection mask having a shielding region of absorber layer lamination system that reduces radiation of reflected light of EUV light, in which an alignment signal having a sufficient contrast can be obtained when detecting an alignment mark by using an EB drawing device.SOLUTION: The reflection mask includes at least a substrate, a reflection layer reflecting the EUV light, an absorber pattern formed of a first absorber layer absorbing the EUV light, a shielding region which reduces radiation of reflected light of the EUV light, and an alignment mark for use in alignment exposure by an electron beam. The shielding region is a reflection mask provided by laminating a second absorber layer on the first absorber layer, the alignment mark is formed in the shielding region by etching the second absorber layer, and the second absorber layer has a thickness thicker than that required for shielding the EUV light.

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, alignment during mask pattern formation. The present invention relates to a reflective mask that is easily exposed, a reflective mask blank, and a method for manufacturing a reflective mask.

  Along with the miniaturization of semiconductor devices, an exposure method of transferring a pattern onto a wafer using a photomask is currently being performed by an optical projection exposure apparatus using an ArF excimer laser. In these exposure methods using an optical projection exposure apparatus, the resolution limit will eventually be reached. Therefore, new pattern forming methods such as direct drawing using an electron beam drawing apparatus, imprint lithography, and EUV lithography have been proposed.

  Among these new lithography techniques, EUV exposure, which is regarded as the limit of shortening the wavelength of ultraviolet exposure, uses EUV light with a wavelength of about 13.5 nm, which is a shorter wavelength than an excimer laser, and a mask pattern is usually 1 This is an exposure technology that reduces the size to about / 4 and transfers it to a resist on a wafer, and is attracting attention as a next-generation lithography technology for semiconductor devices. In EUV exposure, since a refractive optical system cannot be used due to a short wavelength, a reflective optical system is used, and a reflective mask has been proposed as a mask (see Patent Document 1).

  This reflective mask for EUV exposure (hereinafter also referred to as a reflective mask) is formed of a reflective layer having a multilayer structure that reflects EUV light, and an absorbing layer that absorbs EUV light on the reflective layer. It is a mask provided with at least a pattern (hereinafter referred to as an absorber pattern) to be transferred to a transfer medium such as a wafer.

  FIG. 13 is a sectional view showing an example of such a conventional reflective mask for EUV exposure. The reflective mask 130 for EUV exposure shown in FIG. 13 has a reflective layer 132 that reflects EUV light in a multilayer structure on a substrate 131, and an absorber composed of an absorbing layer 135 that absorbs EUV light on the reflective layer 132. It has a structure in which a pattern is formed. The EUV light incident on the reflective mask is reflected by the reflective layer 112, absorbed by the absorption layer 135, and a reduced transfer pattern is formed on the wafer by the reflected EUV light. Note that a capping layer 133 that protects the reflective layer and a buffer layer 134 that prevents etching damage to the reflective layer 132 when forming the mask pattern may be provided on the reflective layer 132. Further, an antireflection layer 136 may be provided on the absorption layer 135 in order to increase the detection sensitivity at the time of inspection.

  FIG. 8 is a conceptual diagram of EUV exposure using a reflective mask. As shown in FIG. 8, in the EUV exposure, the EUV light 81 is incident from a direction inclined by several degrees (for example, 6 degrees) from the direction perpendicular to the surface of the reflective mask 80. Therefore, if the thickness of the absorption layer 115 pattern is large, the pattern itself shadows, and a sharp transfer image cannot be obtained due to a phenomenon called shadowing such as blurring of the edge portion of the pattern transferred during exposure. In terms of formation, it is more preferable that the thickness of the absorption layer 115 is thinner. From this point, it is advantageous that the absorption layer 115 has a larger absorption coefficient with respect to the wavelength of the exposure light, and the film thickness of the absorption layer 115 is sufficient to absorb the EUV light 81 as the exposure light. And as thin as possible.

However, when the thickness of the absorption layer 115 is reduced, the following problem of resist overexposure at the exposure field boundary occurs.
In EUV exposure, similar to the stepper exposure of a photomask, the pattern area on the reflective mask 80 is divided into rectangular exposure fields 84 by a blade 82 installed on the reflective mask 80 as shown in FIG. Then, the wafer 83 is subjected to multi-face exposure by the step-and-repeat method. Here, as described above, when the film thickness of the absorption layer 115 is reduced, the intensity of the reflected light emitted from the absorption layer 115 increases, and in the overlapping portion of the outer periphery of the exposure field 84 corresponding to the vicinity of the blade 82 boundary. The resist on the wafer 83 is overexposed due to multiple exposure.

  FIG. 9 is an explanatory diagram of the above-described problem caused by EUV exposure, and illustrates a state in which four exposure fields are transferred onto the wafer 83. As shown in FIG. 9, in the periphery of the field boundary on the wafer, the exposure is overlapped by double or quadruple exposure due to adjacent shots at the time of exposure, resulting in multiple exposure as a field overlap portion 86. Resists resist and causes resist damage. For example, when a positive type resist is used, even if it is appropriate exposure in one exposure shot, the resist in the portion where the field 84 overlaps is overexposed by multiple exposure. The problem of dimensional variation arises.

  In order to solve the above-described problem of light shielding at the exposure field boundary, a reflective mask having a light shielding region around the transfer pattern region of the mask has been proposed (see Patent Document 2). Here, the transfer pattern area is a pattern area on a reflective mask corresponding to an exposure field transferred to a transfer object such as a wafer, and the light shielding area is the transfer pattern area. This is an area where reflection of EUV light provided in the periphery is reduced, and by providing a light shielding area, resist over-exposure at the boundary between adjacent exposure fields on the wafer is prevented.

  Patent Document 2 discloses two methods as shown in FIG. 10 as typical examples of a reflective mask for EUV exposure provided with a light shielding region.

  A reflective mask 100a shown in FIG. 10A is a reflective mask in which an absorption layer of a light shielding region 108 around a transfer pattern region 107 is laminated in a two-stage structure (hereinafter also referred to as an absorption layer lamination method). A second absorption layer 106 is provided on one absorption layer 105 to form a light shielding region 108. Note that an antireflection layer (not shown) may be provided on the surface of the first absorption layer 105 in order to perform defect inspection of the reflective mask more accurately. In addition, a capping layer 103 for protecting the reflection layer is usually provided on the surface of the reflection layer 102. Between the capping layer 103 and the absorption layer 105, the reflection layer is removed from etching during processing of the absorption layer. A buffer layer 104 for protection may be provided.

  A reflective mask 100b shown in FIG. 10B is a reflective mask of a reflective layer processing method in which the reflective layer 102 in the light shielding region 108 around the transfer pattern region 107 is removed by etching. Also in this method, similarly to the example shown in FIG. 10A, an antireflection layer is formed on the transfer pattern made of the absorption layer 105 in order to perform defect inspection of the reflective mask with higher accuracy. May be provided. In addition, a capping layer 103 for protecting the reflection layer is usually provided on the surface of the reflection layer 102. Between the capping layer 103 and the absorption layer 105, the reflection layer is removed from etching during processing of the absorption layer. A buffer layer 104 for protection may be provided.

  When manufacturing an absorption layer lamination type reflective mask in which an absorption layer is laminated as shown in FIG. 10A, two methods have been proposed as shown in FIGS.

  In the first method shown in FIG. 11, an absorption layer is laminated in advance, and the laminated second absorption layer 114 and the first absorption layer 113 serving as a transfer pattern are successively subjected to pattern etching (FIG. 11A )), And then the second absorption layer 114 on the upper portion of the absorber pattern 113a is removed by etching to form a transfer pattern region 115 and a light shielding region 116 (FIG. 11B). In this method, since the film thickness to be etched is increased, pattern deterioration due to resist damage during etching, limitation of the absorber film thickness, damage to the reflective layer 112 when removing the upper second absorption layer Various problems have occurred.

  In the second method shown in FIG. 12, after removing the laminated second absorption layer 114 to be the transfer pattern region 115 (FIG. 12A), the first absorption layer 113 in the transfer pattern region 115 is etched. Thus, the absorber putter 113a is created (FIG. 12B). In the case of this method, the resist process at the time of creating the absorber pattern is affected by, for example, sulfate ions used in the cleaning process when removing the second absorption layer 114 remaining on the substrate. The problem is that it adversely affects accuracy.

  However, due to recent cleaning processes and resist improvements, for the reflective mask, the latter second method shown in FIG. 12 is a more promising manufacturing method than the former first method shown in FIG.

Japanese Unexamined Patent Publication No. 63-201656 JP 2009-212220 A

  Here, when the reflective mask is made using the above-described second method shown in FIG. 12, an alignment mark (not shown) is simultaneously formed when patterning the upper second absorption layer 114. Then, using this alignment mark as a reference, the absorber pattern is exposed to the transfer pattern region with an electron beam (EB) to form a resist pattern.

  However, when performing alignment exposure using an electron beam, a resist (thickness of about 150 nm) is applied to the surface, so that the edge of the alignment pattern becomes smooth, and the edge of the alignment pattern is captured by an EB scan during EB alignment exposure. Inability to perform EB alignment exposure has occurred. For this reason, the conventional method of manufacturing a reflective mask of the absorption layer lamination type as shown in FIG. 12 has a problem that it is difficult to form a resist pattern for forming an absorber pattern with high positional accuracy. It was.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the radiation of the reflected light of the EUV light and shield it from being provided around the transfer pattern area formed by the absorber pattern. In a reflective mask for EUV exposure having a light-shielding region of an absorption layer stacking method, an alignment signal having sufficient contrast can be obtained when an alignment mark is detected using an EB drawing apparatus, and alignment exposure is easy Then, it is providing the manufacturing method of the reflective mask which can form the resist pattern for forming an absorber pattern with sufficient position accuracy, a reflective mask blank, and a reflective mask.

  In order to solve the above-described problems, a reflective mask according to the first aspect of the present invention includes a substrate, a reflective layer that is formed on the main surface of the substrate and reflects EUV light, and the reflective layer. An absorber pattern formed by a first absorption layer that absorbs the EUV light, a light shielding region for shielding the EUV light around a transfer pattern region formed by the absorber pattern, and the absorption An EUV comprising at least an alignment mark used for alignment exposure by an electron beam for forming a body pattern, wherein the light-shielding region is provided by laminating a second absorption layer on the first absorption layer A reflective mask for exposure, wherein the alignment mark is formed in the light shielding region by etching the second absorption layer, and the alignment mark The thickness of the absorbing layer is a thickness capable of detecting the alignment mark by the electron beam, is characterized in that the thicker than the thickness needed to shield the EUV light.

  A reflective mask according to a second aspect of the present invention is the reflective mask according to the first aspect, wherein the thickness of the second absorbent layer is the same as the thickness of the first absorbent layer or the first mask. It is characterized by being thicker than the thickness of one absorption layer.

  A reflective mask according to a third aspect of the present invention is the reflective mask according to the first or second aspect, wherein the thickness of the second absorption layer is in the range of 60 nm to 200 nm. It is what.

  A reflective mask according to a fourth aspect of the present invention is the reflective mask according to any one of the first to third aspects, wherein the cross-sectional shape of the layer constituting the alignment mark is such that the substrate surface side is The shape is an inverted trapezoid narrower than the surface side.

  A reflective mask blank according to a fifth aspect of the present invention is a substrate, a reflective layer that is formed on the main surface of the substrate, reflects EUV light, and absorbs the EUV light on the reflective layer. A reflective mask blank for EUV exposure comprising at least one absorption layer and a second absorption layer laminated on the first absorption layer, wherein the thickness of the second absorption layer is When the alignment mark is formed by etching the second absorption layer, the alignment mark has a thickness that can be detected by an electron beam, and is thicker than a thickness necessary for shielding the EUV light. Is.

  The reflective mask blank according to claim 6 of the present invention is the reflective mask blank according to claim 5, wherein the thickness of the second absorbent layer is the same as the thickness of the first absorbent layer, or It is characterized by being thicker than the thickness of the first absorption layer.

  The reflective mask blank according to claim 7 of the present invention is the reflective mask blank according to claim 5 or 6, wherein the thickness of the second absorption layer is in the range of 60 nm to 200 nm. It is characterized by.

  A reflective mask manufacturing method according to an eighth aspect of the present invention is the reflective mask manufacturing method according to the fourth aspect, wherein the reflective mask according to any one of the fifth to seventh aspects is provided. Using a mold mask blank, a first resist pattern for forming the transfer pattern region and the alignment mark is formed on the second absorption layer, and the second resist is used as a mask. The transfer layer is etched to form the transfer pattern region and the alignment mark at the same time. Next, after the first resist pattern is peeled off, a second resist is applied on the main surface of the substrate, and the alignment mark is formed. The second resist pattern for forming the absorber pattern on the first absorption layer is formed on the first absorption layer, and the second resist pattern is formed. In the method of manufacturing a reflective mask, the first absorption layer is etched using the mask to form the absorber pattern, and then the second resist pattern is peeled off. The shape is created in an inverted trapezoidal shape in which the substrate surface side is narrower than the surface side.

  The reflective mask manufacturing method according to the ninth aspect of the present invention is the reflective mask manufacturing method according to the eighth aspect, wherein the second absorbent layer is etched on the first absorbent layer. The etching stop layer, the second absorption layer, and a mask layer that serves as a mask when etching the second absorption layer are provided in this order.

The method for manufacturing a reflective mask according to claim 10 of the present invention is the method for manufacturing a reflective mask according to claim 8 or 9, wherein the first absorption layer and the second absorption layer are the same. It is a Ta film, and the etching stop layer and the mask layer are TaO ₂ films.

  According to the reflective mask for EUV exposure of the present invention, the light shielding property of the overlapping portion of the transfer pattern field in the EUV exposure is improved, and the resist film is reduced by the multiple exposure at the time of exposure to the wafer, and the pattern size finish accuracy is lowered. It is possible to form a high-resolution transfer pattern with high positional accuracy by providing a light-blocking area of the absorption layer lamination method that is prevented.

  According to the reflective mask blanks for EUV exposure of the present invention, the reflective mask blanks for EUV exposure having a light-shielding region of an absorption layer lamination method having sufficient light-shielding properties and having a high-resolution absorber pattern with high positional accuracy. A mask can be obtained.

  According to the method for manufacturing a reflective mask for EUV exposure of the present invention, in manufacturing a reflective mask for EUV exposure having a light-shielding region of an absorption layer lamination method, when detecting an alignment mark using an EB drawing apparatus, An alignment signal having sufficient contrast can be obtained, alignment exposure is easy, and a resist pattern for forming an absorber pattern with high positional accuracy can be formed.

It is the schematic sectional drawing and top view which show 1st Embodiment in the reflective mask of this invention which has a light shielding area | region. It is a schematic sectional drawing which shows 2nd Embodiment in the reflective mask of this invention which has a light shielding area | region. It is a schematic sectional drawing which shows other embodiment in the reflective mask of this invention which has a light shielding area | region. It is a schematic sectional drawing which shows an example of embodiment in the reflective mask blanks of this invention. It is a figure explaining the effect of the alignment mark in the reflective mask of this invention. It is a figure explaining the problem of the alignment mark in the conventional reflective mask. It is a cross-sectional schematic diagram which shows the manufacturing process of the reflective mask of this invention which has the light-shielding area | region shown in FIG. It is a conceptual diagram of EUV exposure. It is explanatory drawing of the problem of the multiple exposure in the part with which the field by EUV exposure overlaps. It is a schematic diagram which shows the cross-section of the reflection type mask which has the conventional light-shielding area | region. It is partial explanatory drawing of the 1st manufacturing method in the case of manufacturing the reflection type mask of an absorption layer lamination system. It is partial explanatory drawing of the 2nd manufacturing method in the case of manufacturing the reflection type mask of an absorption layer lamination system. It is sectional drawing which shows an example of the reflection type mask for conventional EUV exposure.

  Embodiments of a reflective mask for EUV exposure, a reflective mask blank, and a method for manufacturing a reflective mask according to the present invention will be described below with reference to the drawings.

<Reflective mask>
(First embodiment)
FIG. 1 is a diagram showing a first embodiment of a reflective mask 10 of the present invention having a light shielding region, and FIG. 1 (a) is a schematic cross-sectional view and is a plan view seen from the mask pattern side. Sectional drawing in the AA of 1 (b) is shown. As shown in FIG. 1, a transfer pattern region 21 and a light shielding region 22 are formed on one main surface (front surface) of the reflective mask 10. Here, the transfer pattern area 21 is a pattern area on the reflective mask 10 corresponding to an exposure field transferred to a transfer object such as a wafer, and the light shielding area 22 is provided around the transfer pattern area 21. It is an area where EUV light reflection is reduced, and is provided in an area where multiple exposure is performed during EUV exposure. For example, in a 6-inch square reflective mask, the area of the transfer pattern region 21 is about 100 mm × 130 mm, and the width of the light shielding region 22 is about 3 mm to 25 mm. The outer side of the light shielding region 22 can be shielded with a blade during exposure.

  As shown in FIG. 1A, the reflective mask 10 of this embodiment includes a multilayer reflective layer 12 that reflects EUV light on one main surface (front surface) of a substrate 11, and a reflective layer 12 on the reflective layer 12. In order to reduce and shield the radiation of the reflected light of the EUV light around the absorber pattern 13a formed by the first absorption layer 13 that absorbs the EUV light and the transfer pattern region 21 formed by the absorber pattern 13a. At least, and an alignment mark 15 used for alignment exposure by an electron beam for forming the absorber pattern 13a. The light shielding region 22 is provided by laminating the second absorption layer 14 on the first absorption layer 13, and the alignment mark 15 is formed in the light shielding region 22 by etching the second absorption layer 14. The thickness of the second absorption layer 14 constituting the alignment mark 15 is such that the alignment mark can be detected with an electron beam, giving priority to the viewpoint of alignment exposure, and is necessary for shielding EUV light. It is thicker than a certain thickness.

In the present invention, the thickness of the second absorption layer capable of detecting the edge of the alignment mark provided on the second absorption layer coated with the resist with an electron beam may be 60 nm or more.
On the other hand, in a reflective mask in which a light-blocking region is formed by laminating an absorption layer, a sufficient light-blocking effect is usually obtained if the first absorption layer and the second absorption layer have a total absorption layer thickness of about 100 nm. Can be obtained. Therefore, in the present invention, the thickness of the second absorption layer necessary for shielding the EUV light is set to a thickness equal to or larger than a value obtained by subtracting the thickness (nm) of the first absorption layer from 100 nm. .

  In a reflective mask having a light shielding region in which an absorption layer is laminated, the first absorption layer is usually set to a thickness of 60 nm to 70 nm in order to obtain a phase effect during mask pattern transfer and increase resolution.

  In the reflective mask of the present invention, the thickness of the second absorption layer may be smaller than the thickness of the first absorption layer, provided that an alignment signal having a contrast is obtained by an electron beam and alignment exposure is possible. In order to make alignment exposure easier and more reliable, the thickness of the second absorption layer is more preferably the same as the thickness of the first absorption layer or thicker than the thickness of the first absorption layer.

  In the reflective mask of the present invention, in order to detect the edge of the alignment mark provided on the second absorption layer with an electron beam, the thickness of the second absorption layer may be 60 nm or more as described above. When the film thickness of the absorption layer 2 exceeds 200 nm, etching processing becomes difficult. Therefore, the thickness of the second absorption layer of the reflective mask of the present invention is preferably in the range of 60 nm to 200 nm, more preferably in the range of 80 nm to 150 nm.

  In the present invention, the shape of the alignment mark is not particularly limited, and an alignment mark shape usually used for electron beam drawing can be applied. For example, a cross mark or the like can be used.

(Operational effect of the present invention)
Next, the thickness of the second absorption layer 14 is such that the alignment mark can be detected with an electron beam, and is thicker than the thickness necessary for shielding EUV light. The effects of the alignment mark for forming the absorber pattern will be described with reference to the drawings in comparison with the alignment mark of the conventional reflective mask.

  In a reflective mask for EUV exposure in which a light shielding region is formed by laminating absorption layers, a sufficient light shielding effect can be obtained if the first absorption layer and the second absorption layer have a total absorption layer thickness of about 100 nm. In order to obtain a phase effect at the time of mask pattern transfer and increase the resolution of the transfer pattern, the lower first absorption layer is usually set to a thickness of about 60 nm to 70 nm. The thickness of the absorption layer is conventionally about 30 nm to 50 nm.

  FIG. 6 is a diagram for explaining alignment marks in a conventional reflective mask for comparison. FIG. 6A is a schematic cross-sectional view of a reflective mask in the middle of production in which an alignment mark 65 is formed on the second absorbent layer 64 in the method for producing a reflective mask of the absorbent layer stacking method. As described above, conventionally, the thickness of the second absorption layer 64 is smaller than the thickness of the first absorption layer 63.

  FIG. 6B is an enlarged cross-sectional view of the alignment mark region M2 shown in FIG. 6A when an electron beam resist for forming an absorber pattern is applied in the next step after forming the alignment mark. . When performing alignment exposure with an electron beam, a resist (thickness of about 150 nm) is applied to the substrate surface. Since the thickness of the second absorption layer 64 is small, at the step of about 30 nm to 50 nm of the thickness of the second absorption layer, as shown in FIG. 6B, when the resist for processing the absorber pattern is applied The resist 66 on the alignment mark 65 has a gentle slope.

  FIG. 6C shows the secondary electron intensity profile 67 of the alignment mark 65 during alignment by the electron beam after the resist 66 is formed. In the EB scan at the time of EB alignment exposure, since the intensity of the secondary electrons is weak, the pattern edge of the alignment mark cannot be detected and alignment cannot be performed.

  On the other hand, FIG. 5 is a figure explaining the effect of the alignment mark in the reflective mask of this invention. FIG. 5A is a schematic cross-sectional view in the process of manufacturing a reflective mask showing a state in which the alignment mark 15 is formed on the second absorbent layer 14 in the above-described method for manufacturing a reflective mask of the absorption layer lamination method. . As described above, in the present invention, the thickness of the second absorption layer 14 gives priority to the viewpoint of alignment exposure, and is a thickness that can detect the edge of the alignment mark with an electron beam through a resist, and shields EUV light. It is thicker than necessary. FIG. 5A illustrates a case where the thickness of the second absorption layer 14 is larger than the thickness of the first absorption layer 13.

  FIG. 5B is an enlarged cross-sectional view of the alignment mark region M1 shown in FIG. 5A when an electron beam resist for forming an absorber pattern is applied in the next step after forming the alignment mark. . Since the thickness of the second absorption layer 14 is large, the resist (first resist) 56 on the alignment mark 15 has a steep slope.

  FIG. 5C shows a secondary electron intensity profile 57 of the alignment mark 15 during alignment by the electron beam after the resist 56 is formed. Since the resist on the alignment mark has a steep slope, the edge of the alignment mark 15 is detected by the electron beam through the resist 56, and a very clear alignment signal can be obtained.

  The present invention provides a reflective mask of an absorption layer stacking system in which the upper second absorption layer is not less than a film thickness as a light shielding region required for EUV exposure in order to perform alignment exposure of an absorber pattern with an electron beam. In order to facilitate alignment during EB alignment exposure. In other words, the thickness of the upper second absorption layer is made sufficiently thick not only from the viewpoint of light shielding during EUV exposure but also from the viewpoint of EB alignment exposure to facilitate EB alignment exposure. Since the absorption efficiency of EUV light increases as the thickness of the absorption layer increases, the EUV exposure is not adversely affected by increasing the thickness of the upper second absorption layer serving as a light shielding region.

  Further, since the second absorption layer other than the light shielding region is removed by etching, there is no obstacle to the transfer characteristics of the mask pattern. However, if the upper second absorption layer is too thick, etching is difficult to perform. Therefore, the thickness of the upper second absorption layer is preferably 200 nm or less. On the other hand, the thickness of the upper second absorption layer is preferably in the range of 60 nm to 200 nm, and more preferably in the range of 80 nm to 150 nm because the thickness of the upper absorption layer is preferably 60 nm or more in order to detect the edge of the alignment mark. If it is within the range, a reflective mask structure is obtained which is easy to etch, can achieve sufficient EUV light absorption efficiency, and is easy to align exposure.

(Second Embodiment)
FIG. 2 is a schematic sectional view showing a second embodiment of a reflective mask having a light-shielding region according to the present invention. 2, the same reference numerals as those in FIG. 1 are used to indicate the same parts and materials as those in FIG. As shown in FIG. 2, a transfer pattern region 21 and a light shielding region 22 are formed on one main surface (front surface) of the reflective mask 20. Here, the transfer pattern area 21 is a pattern area on the reflective mask 20 corresponding to an exposure field transferred to a transfer object such as a wafer, and the light shielding area 22 is provided around the transfer pattern area 21. It is an area where EUV light reflection is reduced, and is provided in an area where multiple exposure is performed during EUV exposure.

  As shown in FIG. 2, the reflective mask 20 of this embodiment includes a multilayer reflective layer 12 that reflects EUV light on one main surface of a substrate 11, and a first layer that absorbs EUV light on the reflective layer 12. An absorber pattern 13a formed by one absorber layer 13, a light shielding region 22 for reducing the radiation of reflected light of EUV light around the transfer pattern region 21 formed by the absorber pattern 13a, and an absorber And at least an alignment mark 15 used for alignment exposure by an electron beam for forming the pattern 13a. The light shielding region 22 is provided by laminating the second absorption layer 14 on the first absorption layer 13, and the alignment mark 15 is formed in the light shielding region 22 by etching the second absorption layer 14. The thickness of the second absorption layer 14 constituting the alignment mark 15 is such that the alignment mark can be detected by an electron beam and is thicker than necessary to shield EUV light. The cross-sectional shape of the layers constituting the alignment mark is an inverted trapezoid whose substrate surface side is narrower than the surface side.

  In the present embodiment, the thickness of the second absorption layer 14 is such that the alignment mark can be detected by an electron beam, and in addition to the effect of increasing the thickness more than necessary to shield EUV light, the alignment mark is By making the cross-sectional shape of the constituent layers into an inverted trapezoidal shape, the resist cross-section on the alignment mark 15 has a steeper slope when an electron beam resist for creating an absorber pattern is applied, and is clear during alignment with an electron beam. An alignment signal can be obtained, and alignment exposure with an electron beam is further facilitated.

  In the present embodiment, the alignment mark having the inverted trapezoidal cross-sectional shape is not only the inverted trapezoidal shape whose cross-section is continuously narrower from the surface side toward the substrate surface side, but also the cross-sectional surface side is wide and the substrate surface side is narrow. It includes a T-shaped inverted trapezoidal alignment mark. Even with an alignment mark having a T-shaped cross section, the resist cross section applied on the mark has a steep slope, and alignment exposure by an electron beam is possible.

  The reflective mask of the present invention can be applied with the components and materials of the conventional reflective mask, which will be described below.

(substrate)
The substrate 11 of the reflective mask 10 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 solution used for cleaning in the manufacturing process is preferable. Glass substrate such as quartz glass, SiO ₂ —TiO ₂ low thermal expansion glass, crystallized glass on which β quartz solid solution is deposited, and silicon It can also be used. As the flatness of the mask blank, for example, 50 nm or less is required in the pattern region.

(Reflective layer)
The multilayer reflective layer 12 is made of a material that reflects EUV light used for EUV exposure with a high reflectivity, and a multilayer film composed of Mo and Si is frequently used. Examples include a reflective layer made of a multilayer film in which 40 layers of 11 nm of Si are laminated. 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 Mo and Si, a Si film is first formed in an Ar gas atmosphere using a Si target by a DC magnetron sputtering method, and then a Mo film is used in an Ar gas atmosphere using a Mo target. Is formed as a cycle, and laminated for 30 to 60 cycles, preferably 40 cycles, to obtain a multilayer reflective layer. As described above, in order to reflect EUV light with high reflectivity, the reflectivity of the multilayer reflective layer 12 when EUV light of 13.4 nm is incident at an incident angle of 6.0 degrees is usually 60% or more. Is set to show.

(Absorption layer)
The material of the first absorption layer 13 that forms the absorber pattern 13a in the transfer region 21 of the mask and absorbs EUV light and the second absorption layer 15 that forms the light shielding region 22 includes Ta, TaB, TaBN, and the like. A material containing Ta as a main component, a material containing Cr, Cr as a main component, and containing at least one component selected from N, O, and C is a film thickness in the range of about 30 nm to 100 nm, more preferably 50 nm to 85 nm. It is used in the range.

(Other components)
In addition to the above-described components, other components may be used for the reflective mask of the present invention. FIG. 3 is an example of the reflective mask of the present invention to which other components are added. As shown in FIG. 3, in the reflective mask 30 of the present invention, the first absorption layer 13 forming the absorber pattern 13a does not necessarily have to be in direct contact with the multilayer reflection layer 12. In order to prevent damage to the lower multilayer reflective layer 12 when the first absorbent layer 13 is dry-etched in a pattern, a buffer layer is usually provided between the reflective layer 12 and the first absorbent layer 13. 17 is provided. Further, if necessary, a capping layer (also referred to as a protective layer) 16 is provided on the multilayer reflective layer 12 to prevent oxidation of the reflective layer. In addition, an antireflection layer 18 may be provided on the first absorption layer 13 in order to increase the reflection contrast of the inspection light during mask inspection. Below, the material of said other component is demonstrated.

(Capping layer)
In order to increase the reflectivity of the multilayer reflective layer 12, it is preferable to use Mo having a large refractive index as the uppermost layer. However, Mo is easily oxidized in the atmosphere and the reflectivity is lowered. As a protective film for this, Si or Ru may be formed by sputtering or the like, and the capping layer 16 may be provided. For example, Si is provided as the capping layer 16 on the uppermost layer of the reflective film 12 to a thickness of 11 nm. When Ru is used as a capping layer, a structure that does not use a buffer layer described later can be used.

(Buffer layer)
In order to prevent damage to the lower multilayer reflective layer 12 when the first absorption layer 13 that absorbs EUV light used for EUV exposure is subjected to pattern etching by a method such as dry etching, as necessary. The buffer layer 17 is provided using CrN or the like.

(Antireflection layer)
In addition, in order to increase the detection sensitivity at the time of mask pattern inspection, an antireflection layer 18 having low reflection with respect to inspection light (wavelength 250 nm) may be provided on the first absorption layer 13. Examples of the material of the antireflection layer 18 include tantalum nitride (TaN), oxide (TaO), oxynitride (TaNO), tantalum boron oxide (TaBN), and tantalum boron nitride (TaBN). The film thickness is in the range of about 5 nm to 30 nm. In the present invention, it is preferable that the antireflection layer 18 also functions as an etching stop layer that prevents the lower first absorption layer 13 from being damaged when the second absorption layer 14 is etched.

(Conductive layer)
In a reflective mask for EUV exposure, when the mask is set in an exposure apparatus, it is usually performed by an electrostatic chuck using a conductive layer provided on the main surface (back surface) opposite to the mask pattern. As a material of the conductive layer 19, a thin film such as a metal or metal nitride showing conductivity is provided. For example, chromium (Cr), chromium nitride (CrN), or the like is formed to a thickness of about 20 nm to 150 nm. Used.

According to the reflective mask for EUV exposure of the present invention described above, the light shielding property of the overlapping portion of the transfer pattern field in the EUV exposure is improved, and the resist film is reduced by the multiple exposure at the time of exposure to the wafer and the pattern finishing accuracy is lowered. It is possible to form a high-resolution transfer pattern with high positional accuracy.
Next, the reflective mask blank for EUV exposure of the present invention will be described.

<Reflective mask blanks>
FIG. 4 is a schematic cross-sectional view as an example of the reflective mask blank of the present invention used for the production of the reflective mask of the present invention provided with a light shielding region of an absorption layer lamination system. In FIG. 4, when the same part and material as FIG. 1 are shown, the same code | symbol as FIG. 1 is used. As shown in FIG. 4, the reflective mask blank 40 of the present invention includes a substrate 11, a reflective layer 12 formed on a main surface of the substrate and made of a multilayer film that reflects EUV light, and an EUV on the reflective layer 12. The first absorption layer 13 that absorbs light and the second absorption layer 14 laminated on the first absorption layer 13 are provided at least, and the thickness of the second absorption layer 14 is the second absorption layer. When the alignment mark is formed by etching 14, the mask blank is thick enough to detect the alignment mark with an electron beam and thicker than necessary to shield EUV light.

In the present invention, the thickness of the second absorption layer that can detect the edge of the alignment mark provided on the second absorption layer with an electron beam through a resist may be 60 nm or more.
On the other hand, in a reflective mask in which a light-blocking region is formed by laminating an absorption layer, a sufficient light-blocking effect is usually obtained if the first absorption layer and the second absorption layer have a total absorption layer thickness of about 100 nm. Can be obtained. Therefore, in the present invention, the thickness of the second absorption layer necessary for shielding the EUV light is set to a thickness equal to or larger than a value obtained by subtracting the thickness (nm) of the first absorption layer from 100 nm. .

  In a reflective mask blank used for creating a reflective mask having a light-shielding region of an absorption layer stacking method, in order to obtain a phase effect at the time of mask pattern transfer and increase resolution, the lower first absorption layer is The thickness is 60 nm to 70 nm.

  In the reflective mask blank of the present invention, the thickness of the second absorption layer may be smaller than the thickness of the first absorption layer if alignment exposure can be performed by an electron beam. In order to facilitate, the thickness of the second absorbent layer is more preferably the same as the thickness of the first absorbent layer or thicker than the thickness of the first absorbent layer.

  In the reflective mask blank of the present invention described above, in order to detect the edge of the alignment mark provided in the second absorption layer, the film thickness of the second absorption layer may be 60 nm or more, while the second absorption layer If the film thickness exceeds 200 nm, the etching process becomes difficult. Therefore, the thickness of the second absorption layer of the reflective mask blank of the present invention is preferably in the range of 60 nm to 200 nm, more preferably in the range of 80 nm to 150 nm.

  The substrate 11, the reflective layer 12, the first absorption layer 13, and the second absorption layer 14 that are components of the reflective mask blank 40 shown in FIG. . In addition to the above components, the reflective mask blank of the present invention may use other components as described in the above reflective mask 10. Since other components are the same as those of the reflective mask 10 described above, description thereof is omitted.

  The reflective mask blank 40 of the present invention has a thickness that allows the second absorption layer 14 to be detected with an electron beam when the alignment mark is formed by etching the second absorption layer 14. When the electron beam resist for forming the absorber pattern is applied after forming the alignment mark, as described in the above reflective mask, the second thickness is increased by increasing the thickness more than necessary for shielding EUV light. Since the thickness of the absorption layer 14 is large, the resist on the alignment mark has a steep slope, the intensity of secondary electrons of the alignment mark during alignment by the electron beam increases, and alignment becomes easy.

According to the reflective mask blank of the present invention, it is possible to obtain a reflective mask having a light-shielding region of an absorption layer lamination system having sufficient light-shielding properties and having a high-resolution absorber pattern with high positional accuracy. .
Next, the manufacturing method of the reflective mask for the first EUV exposure of the present invention will be described.

<Manufacturing method of reflective mask>
(Manufacturing method of the reflective mask of the first embodiment)
Since the conventional manufacturing method can be applied to the reflective mask manufacturing method of the first embodiment of the present invention shown in FIG. 1, only the gist will be described below.

  A first resist pattern for forming a transfer pattern region and an alignment mark is formed on the second absorption layer of the reflective mask blank shown in FIG. 4, and the second absorption layer is formed using the first resist pattern as a mask. Are etched to form a transfer pattern region and an alignment mark at the same time. Next, after peeling off the first resist pattern, a second resist is applied onto the main surface of the substrate, and electron beam exposure is performed with reference to the alignment mark. Then, a second resist pattern for creating an absorber pattern is formed on the first absorption layer, and then the first absorption layer is etched using the second resist pattern as a mask to transfer the pattern region Then, an absorber pattern is formed, and then the second resist pattern is peeled off to obtain a reflective mask.

  According to the reflective mask manufacturing method of the first embodiment, when detecting an alignment mark using an EB lithography apparatus in manufacturing a reflective mask for EUV exposure having a light-blocking region of an absorption layer stacking method, An alignment signal having sufficient contrast is obtained by setting the thickness of the second absorption layer constituting the alignment mark to a thickness that can be detected by an electron beam, and increasing the thickness more than necessary to shield EUV light. Therefore, alignment exposure is easy, a resist pattern for forming an absorber pattern can be formed with high positional accuracy, and a highly accurate reflective mask can be manufactured.

(Manufacturing method of the reflective mask of the second embodiment)
Next, as shown in FIG. 2, a method for manufacturing a reflective mask for EUV exposure according to the present invention in which the cross-sectional shape of the layers constituting the alignment mark has an inverted trapezoidal shape in which the substrate surface side is narrower than the surface side will be described. .

  FIG. 7 is a schematic cross-sectional view showing an example of the manufacturing process of the reflective mask of the present invention having the light shielding region shown in FIG. In FIG. 7, the same reference numerals are used to indicate the same parts and materials as those in FIGS. In addition, since each component and material of the reflective mask in the manufacturing method of the present invention are the same as the contents described in the above reflective mask, description thereof is omitted.

  First, a reflective mask blank 40 for EUV exposure is prepared (FIG. 7A). The reflective mask blank 40 is the reflective mask blank shown in FIG.

  Next, a first resist pattern 71 for forming a transfer pattern region and an alignment mark is formed on the second absorption layer 14 (FIG. 7B), and the first resist pattern 71 is used as a mask to form a first resist pattern 71. The transfer pattern region 21 and the alignment mark 15 are simultaneously formed by dry etching the second absorption layer 14 (FIG. 7C). In the present invention, when the second absorption layer 14 is dry-etched, the cross-sectional shape of the second absorption layer of the alignment mark 15 is formed in an inverted trapezoidal shape in which the substrate surface side is narrower than the surface side.

  Next, after the first resist pattern 71 is peeled off, a second resist is applied on the main surface of the substrate, electron beam exposure is performed using the alignment mark 15 as a reference, and an absorber pattern is formed on the first absorption layer 13. A second resist pattern 72 is formed for forming (FIG. 7D).

  Next, the first absorption layer 13 is etched using the second resist pattern 72 as a mask to form the absorber pattern 13a in the transfer pattern region 21, and then the second resist pattern 72 is peeled off to reflect the reflection type. A mask 20 is obtained (FIG. 7E).

According to the method for manufacturing a reflective mask for EUV exposure of the present invention, in manufacturing a reflective mask for EUV exposure having a light-shielding region of an absorption layer lamination method, when detecting an alignment mark using an EB drawing apparatus, The thickness of the second absorption layer that constitutes the alignment mark is set to a thickness that can be detected by an electron beam, and is thicker than necessary to shield EUV light, and the cross-sectional shape of the layer that constitutes the alignment mark is By adopting an inverted trapezoidal shape where the substrate surface side is narrower than the surface side, alignment signals with sufficient contrast can be obtained, alignment exposure is easy, and a resist pattern for forming an absorber pattern with high positional accuracy is formed This makes it possible to manufacture a highly accurate reflective mask.
Hereinafter, the present invention will be described in more detail by way of examples.

Example 1
As a substrate, an optically polished 6 inch square (0.25 inch thick) synthetic quartz substrate is used. On one main surface (front surface), an Si target is used by an ion beam sputtering method to form Si. After forming a film of 4.2 nm, and subsequently forming a Mo film of 2.8 nm using a Mo target and laminating it for 40 periods, a reflective layer made of a multilayer film of Mo and Si is formed. A capping layer was formed by forming a Si film with a thickness of 11 nm on the outermost Mo film.

Next, a CrN film having a thickness of 10 nm was formed as a buffer layer on the above capping layer in a N ₂ atmosphere using a Cr target by RF magnetron sputtering.

Next, a TaN film having a thickness of 40 nm was formed as a first absorption layer on the CrN film by a DC magnetron sputtering method using a Ta target in a mixed gas atmosphere of Ar and nitrogen. Next, a TaO ₂ film having a thickness of 15 nm is formed on the above TaN film in a mixed atmosphere of Ar and oxygen using a Ta target by a DC magnetron sputtering method in order to increase the reflection contrast of inspection light at the time of mask inspection. The antireflection layer was formed with a thickness of. The TaO ₂ film of the antireflection layer functions as an etching stop layer that prevents the first absorption layer below from being damaged when the second absorption layer provided on the first absorption layer is etched. It also serves as.

Next, a TaN film having a thickness of 100 nm is formed on the TaO ₂ film by a DC magnetron sputtering method using a Ta target in a mixed gas atmosphere of Ar and nitrogen to form a second absorption layer. A reflective mask blank was obtained.

  Next, a resist for electron beam is applied on the TaN film that forms the second absorption layer of the reflective mask blank, and a transfer pattern region and an alignment mark are formed using an electron beam drawing apparatus. The resist pattern was formed. Here, the resist pattern for forming the alignment mark was a cross-shaped pattern having a plane width of 5 μm.

Next, the TaN film forming the second absorption layer exposed from the opening of the resist pattern was dry-etched with Cl ₂ gas to form a transfer pattern region and a cross-shaped alignment mark at the same time.

  Next, the first resist pattern is peeled off, a second electron beam resist is applied onto the main surface of the substrate, electron beam exposure is performed with reference to the alignment mark, and the first absorption layer is absorbed. A second resist pattern for creating a body pattern was formed. In the electron beam exposure, the thickness of the second absorption layer is made larger than the thickness of the first absorption layer so that the alignment mark can be detected by the electron beam, and is thicker than the thickness necessary for shielding EUV light. Therefore, the resist on the alignment mark has a steep slope, and a clear alignment signal is obtained.

Next, using the second resist pattern as a mask, the TaO ₂ film for forming the antireflection layer is dry-etched with CF ₄ gas, and then the TaN film of the first absorption layer is dry-etched with Cl ₂ gas, The buffer layer CrN film was exposed.

Next, the exposed CrN film of the buffer layer is dry-etched with a mixed gas of Cl ₂ and oxygen to expose the capping layer to form an absorber pattern in the transfer pattern region, and then the second resist pattern is stripped, A reflective mask for EUV exposure having a light-shielding region of an absorption layer lamination system having sufficient light-shielding properties and having a high-resolution absorber pattern with good positional accuracy was obtained.

(Example 2)
As a substrate, an optically polished 6 inch square (0.25 inch thick) synthetic quartz substrate is used. On one main surface (front surface), an Si target is used by an ion beam sputtering method to form Si. After forming a film of 4.2 nm, and subsequently forming a Mo film of 2.8 nm using a Mo target and laminating it for 40 periods, a reflective layer made of a multilayer film of Mo and Si is formed. Then, a Ru film was formed to 2.5 nm on the outermost Mo film to form a capping layer. The Ru film also serves as a buffer layer.

  Next, a Ta film having a thickness of 35 nm was formed as a first absorption layer on the Ru film by a DC magnetron sputtering method using a Ta target in a mixed gas atmosphere of Ar and nitrogen.

Next, in order to increase the reflection contrast of the inspection light at the time of mask inspection, a TaO ₂ film having a thickness of 15 nm is formed on the Ta film by a DC magnetron sputtering method in a mixed gas atmosphere of Ar and oxygen using a Ta target. The antireflection layer was formed with a thickness of. The TaO ₂ film of the antireflection layer functions as an etching stop layer that prevents the first absorption layer below from being damaged when the second absorption layer provided on the first absorption layer is etched. It also serves as.

Next, a Ta film having a thickness of 90 nm was formed as a second absorption layer on the TaO ₂ film by a DC magnetron sputtering method using a Ta target in an Ar gas atmosphere. Furthermore, a TaO ₂ film having a thickness of 20 nm was formed as an etching mask layer on the second absorption layer Ta film to obtain a reflective mask blank. The etching mask layer TaO ₂ film is a part of the alignment mark and is used to form the cross-sectional shape of the second absorption layer in an inverted trapezoidal shape. The TaO ₂ film was formed by a DC magnetron sputtering method using a Ta target in a mixed gas atmosphere of Ar and oxygen.

Next, a resist for electron beam is applied on the TaO ₂ film for forming the etching mask layer, and a first resist pattern for forming a transfer pattern region and an alignment mark is formed using an electron beam drawing apparatus. Formed. Here, the resist pattern for forming the alignment mark was a cross-shaped pattern having a plane width of 5 μm.

Next, the etching mask layer TaO ₂ film exposed from the opening of the resist pattern was dry-etched with CF ₄ gas. Next, the Ta film forming the second absorption layer is dry-etched with low bias power Cl ₂ gas plasma, and the cross-sectional shape of the layer constituting the alignment mark composed of the TaO ₂ film and the Ta film is reversed to be T-shaped. A trapezoidal alignment mark was formed simultaneously with the transfer pattern region.

  Next, the first resist pattern is peeled off, a second electron beam resist is applied onto the main surface of the substrate, electron beam exposure is performed with reference to the alignment mark, and the first absorption layer is absorbed. A second resist pattern for creating a body pattern was formed. In the present embodiment, in the electron beam exposure, the thickness of the second absorption layer constituting the alignment mark is larger than the thickness of the first absorption layer so that the alignment mark can be detected by the electron beam, and the EUV light is shielded. In addition to being thicker than necessary, the cross section of the layers that make up the alignment mark has a T-shaped inverted trapezoidal shape, so the resist on the alignment mark has a steeper slope and a clear alignment. A signal was obtained.

Next, using the second resist pattern as a mask, the TaO ₂ film for forming the antireflection layer is dry-etched with CF ₄ gas, and then the Ta film of the first absorption layer is dry-etched with Cl ₂ gas, The capping layer Ru film was exposed to form an absorber pattern in the transfer pattern region.

  Next, the second resist pattern was peeled off, and a reflective mask for EUV exposure having an absorption layer lamination type light shielding region having sufficient light shielding properties and having a high resolution absorber pattern with high positional accuracy was obtained. .

10, 20, 30 Reflective mask 11 Substrate 12 Reflective layer 13 First absorption layer 13a Absorber pattern 14 Second absorption layer 15 Alignment mark 16 Capping layer 17 Buffer layer 18 Antireflection layer 19 Conductive layer 21 Transfer pattern region 22 Light shielding area 40 Reflective mask blanks 56 Resist (first resist)
57 Secondary electron intensity profile 61 Substrate 62 Reflective layer 63 First absorption layer 64 Second absorption layer 65 Alignment mark 66 Resist 67 Secondary electron intensity profile 71 Resist pattern 80 Reflective mask 81 EUV light 82 Blade 83 Wafer 84 Field 85 Transfer pattern 86 Field overlap portion 100a, 100b, 110, 136 Reflective mask 101, 111, 131 Substrate 102, 112, 132 Reflective layer 103, 133 Capping layer 104, 134 Buffer layer 105, 113 First absorption layer 106, 114 Second absorption layer 107, 115 Transfer pattern area 108, 116 Shield area 135 Absorption layer 136 Antireflection layer

Claims (10)

A substrate, a reflective layer formed on the main surface of the substrate and reflecting EUV light, an absorber pattern formed on the reflective layer by a first absorbing layer that absorbs the EUV light, and the absorber Around a transfer pattern region formed by a pattern, at least a light shielding region for shielding the EUV light, and an alignment mark used for alignment exposure by an electron beam for forming the absorber pattern, The light shielding region is a reflective mask for EUV exposure provided by laminating a second absorption layer on the first absorption layer,
The alignment mark is formed in the light shielding region by etching the second absorption layer;
Reflection characterized in that the thickness of the second absorption layer constituting the alignment mark is such that the alignment mark can be detected by the electron beam and is thicker than necessary to shield the EUV light. Type mask.   2. The reflective mask according to claim 1, wherein the thickness of the second absorption layer is the same as the thickness of the first absorption layer or thicker than the thickness of the first absorption layer.   The reflective mask according to claim 1 or 2, wherein the thickness of the second absorption layer is in a range of 60 nm to 200 nm.   4. The reflective mask according to claim 1, wherein a cross-sectional shape of a layer constituting the alignment mark is an inverted trapezoidal shape in which the substrate surface side is narrower than the surface side. 5. A substrate, a reflective layer that is formed on the main surface of the substrate and reflects EUV light, a first absorption layer that absorbs the EUV light on the reflective layer, and a laminate on the first absorption layer A reflective mask blank for EUV exposure comprising at least the second absorbing layer,
The thickness of the second absorption layer is such that when the alignment mark is formed by etching the second absorption layer, the alignment mark can be detected by an electron beam, and is necessary for shielding the EUV light. Reflective mask blanks characterized by being thicker than the desired thickness.   6. The reflective mask blank according to claim 5, wherein the thickness of the second absorption layer is the same as the thickness of the first absorption layer or thicker than the thickness of the first absorption layer.   The reflective mask blank according to claim 5 or 6, wherein a thickness of the second absorption layer is in a range of 60 nm to 200 nm. It is a manufacturing method of the reflection type mask according to claim 4,
A first resist pattern for forming the transfer pattern region and the alignment mark is formed on the second absorption layer using the reflective mask blank according to any one of claims 5 to 7. And etching the second absorption layer using the first resist pattern as a mask to simultaneously form the transfer pattern region and the alignment mark,
Next, after peeling off the first resist pattern, a second resist is applied on the main surface of the substrate, electron beam exposure is performed with reference to the alignment mark, and the absorption is performed on the first absorption layer. Forming a second resist pattern for creating a body pattern;
In the method of manufacturing a reflective mask, the first absorption layer is etched using the second resist pattern as a mask to form the absorber pattern, and then the second resist pattern is peeled off.
A method for producing a reflective mask, wherein the cross-sectional shape of the layer constituting the alignment mark is formed in an inverted trapezoidal shape in which the substrate surface side is narrower than the surface side.   On the first absorption layer, an etching stop layer at the time of etching the second absorption layer, the second absorption layer, and a mask layer that serves as a mask at the time of etching the second absorption layer are provided in this order. The method for manufacturing a reflective mask according to claim 8, wherein: The reflection type according to claim 8 or 9, wherein the first absorption layer and the second absorption layer are Ta films, and the etching stop layer and the mask layer are TaO ₂ films. Mask manufacturing method.

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