JP2012209481A - Reflective mask blank and method of manufacturing reflective mask blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective mask blank having a light-shielding frame with high light-shielding properties, and a method of manufacturing the reflective mask blank.SOLUTION: In a manufacturing process of a reflective mask blank 140 having: a substrate 11; a multilayer reflection layer 21 formed on a surface of the substrate 11; and an absorption layer 51 formed above the multilayer reflection layer 21, by providing a process of irradiating laser from a rear surface of the substrate 11 to an area of at least the multilayer reflection layer 21, which is positioned outside a circuit pattern transfer region 5 provided in the absorption layer 51, a light-shielding frame 1 with a composite layer 31 of an intermediate layer by eliminating interface of the multilayer reflection layer 21. In the light-shielding frame 1, the light-shielding frame 1 having high light-shielding properties, in which reflection intensity from the multilayer reflection layer 21 is reduced and optical property of the absorption layer 51 is maintained, is fabricated.

Description

  The present invention relates to a reflective mask blank and a method for manufacturing a reflective mask blank. In particular, the present invention relates to a reflective mask blank and a reflective mask blank manufacturing method used in a semiconductor device using EUV lithography that uses extreme ultraviolet (EUV) as a light source.

In recent years, with the miniaturization of semiconductor devices, EUV lithography using EUV having a wavelength of around 13.5 nm as a light source has been proposed.
EUV lithography needs to be performed in a vacuum due to the characteristics of the light source wavelength. Furthermore, in the EUV wavelength region, the refractive index of most substances is slightly smaller than 1, and the light absorption is very high. For this reason, in EUV lithography, the refractive optical system conventionally used cannot be used, but becomes a reflection optical system. Therefore, the conventional transmissive mask cannot be used as the mask, so it is necessary to use a reflective mask.

  In such a reflective mask, a multilayer reflective layer showing a high reflectance with respect to the exposure light source wavelength and an absorption layer having the exposure light source wavelength are sequentially formed on the substrate. A back conductive film for the electrostatic chuck is formed. There is also an EUV mask having a structure having a buffer film between the multilayer reflective layer and the absorption layer. In the case of a structure having a buffer film with the absorption layer partially removed, this is also removed to form a circuit pattern comprising an absorption portion and a reflection portion. The light image reflected by the reflective mask is transferred onto the semiconductor substrate through a reflective optical system.

In the exposure method using the reflective optical system, irradiation is performed at an incident angle inclined by a predetermined angle from the vertical direction with respect to the mask surface. Therefore, when the absorption layer is thick, the shadow of the pattern itself is generated. Since the reflection intensity in the part which becomes is smaller than the part which is not a shadow, the contrast is lowered, and the pattern edge part is blurred and deviated from the design dimension.
In order to prevent such blurring of the pattern edge portion and deviation from the design dimension, it is effective to reduce the thickness of the absorption layer and reduce the height of the pattern, but when the thickness of the absorption layer becomes small As a result, the light shielding property in the absorbing layer is lowered, and the transfer contrast is lowered.

  Therefore, a phase shift type absorption layer in which the thickness of the absorption layer is designed to have a phase shift function that makes the phase of the reflected light on the surface of the absorption layer different from the phase of the reflected light from the multilayer reflective layer via the absorption layer. Thus, the transfer contrast can be improved while reducing the thickness of the absorption layer. However, when comparing absorption layers with different film thicknesses, which are made of the same material and designed to have the same phase shift function, the light-shielding property of the absorption layer with a smaller film thickness compared with an absorption layer with a larger film thickness is Inferior.

On the other hand, when a transfer circuit pattern is formed on a semiconductor substrate using a reflective mask, chips having a plurality of circuit patterns are formed on one semiconductor substrate.
Therefore, in order to provide a frame that divides the chips on the semiconductor substrate, a light shielding region by an absorption layer, that is, a light shielding frame may be provided on the reflective mask in advance so as to surround the circuit pattern region.

  When the number of chips formed on one semiconductor substrate is increased, there may be a region where the region of the light shielding frame on the reflective mask overlaps between adjacent chips. In this case, this region is exposed a plurality of times. Therefore, in the case where exposure is performed using a reflective mask having a phase shift type absorption layer with a small film thickness of the absorption layer, a part of the region to be a frame that divides each chip is obtained by multiple exposure. There is a problem that it is difficult to form an accurate frame for separating each chip due to exposure to light.

  In order to solve such a problem, a groove reaching the multilayer reflective layer from the absorption layer of the reflective mask, a film thicker than the thickness of the absorption layer in the circuit pattern region, There has been proposed a reflective mask provided with a light-shielding frame having a high light-shielding property with respect to the exposure light source wavelength by reducing the reflectance of the multilayer reflective layer by laser irradiation or ion implantation on the mask (Patent Document 1).

JP 2009-212220 A

  However, in the manufacturing process of the reflective mask, when forming a light shielding frame by forming a groove reaching the multilayer reflective layer from the absorption layer or by forming a film thicker than the thickness of the absorption layer in the circuit pattern region, Since the patterning process by lithography newly occurs in the formation of the light shielding frame and the process of manufacturing the reflective mask becomes complicated, there is a concern that the yield is deteriorated.

  Therefore, an object of the present invention is to provide a reflective mask blank having a light shielding frame with high light shielding properties, and a method for manufacturing the reflective mask blank.

  The reflective mask blank of the present invention is a reflective mask blank comprising a substrate, a multilayer reflective layer formed on the substrate surface, and an absorption layer formed on the multilayer reflective layer. A light-shielding frame comprising a composite layer formed on the outer side of a transfer circuit pattern region formed on a reflective mask manufactured using blanks and formed by an intermediate layer of a plurality of layers constituting each interface of a multilayer reflective layer And the optical property of the absorption layer located in the region corresponding to the light shielding frame is equivalent to the optical property of the absorption layer located in the region corresponding to the transfer circuit pattern region. Is.

  The reflective mask blank of the present invention is characterized in that a conductive film is formed on the back surface of the substrate, and the composite layer includes a plurality of the intermediate layers. It is.

  In the reflective mask blank of the present invention, the multilayer reflective layer has an interface between the uppermost layer located closest to the absorption layer of the multilayer reflective layer and its adjacent layer in the region where the light shielding frame is formed. It may exist including a corresponding part.

  In the reflective mask blank of the present invention, the multilayer reflective layer has an interface between the uppermost layer located closest to the absorption layer of the multilayer reflective layer and its adjacent layer, and the light shielding layer among the interfaces. Instead of the interface, an intermediate layer made of the material of the uppermost layer and its adjacent layer may exist in a portion corresponding to the region where the frame is formed.

  In the reflective mask blank of the present invention, an interface may exist between the absorbing layer and its adjacent layer, including a portion corresponding to the region where the light shielding frame is formed.

  In the reflective mask blank of the present invention, an interface exists between the absorption layer and its adjacent layer, and corresponds to a region where the light shielding frame is formed in the interface between the absorption layer and its adjacent layer. Instead of the interface between the absorption layer and its adjacent layer, an intermediate layer made of the material of the absorption layer and its adjacent layer may be present in the portion.

  Moreover, the manufacturing method of the reflective mask blank of this invention manufactures the reflective mask blank which includes the process of forming a multilayer reflective layer on the substrate surface, and the process of forming an absorption layer above the multilayer reflective layer. The method includes the step of performing laser irradiation or ion implantation on at least the multilayer reflective layer from the back surface of the substrate.

  Moreover, the photomask blank manufacturing method of the present invention includes a step of forming a conductive film on the back surface of the substrate after the laser irradiation or ion implantation step.

The present invention provides a reflective mask blank that suppresses the intensity of reflected light generated from a multilayer reflective layer and further suppresses changes in the optical properties of the absorbing layer, thereby forming a light shielding frame having a high light shielding property. There is an effect that the yield in the production of the mold mask can be improved.
When a light shielding frame is formed by laser irradiation or ion implantation from a reflective mask, there is a loss of laser light or ions due to other than the multilayer reflective layer. I have to do it. Further, there is a concern that the film other than the multilayer reflective layer is damaged by irradiation with laser light or ions, and the absorption rate of the exposure light source wavelength of the absorption layer is lowered.
However, in one embodiment of the present invention, the reflectance of the multilayer reflective layer in the region other than the transfer circuit pattern region is reduced by irradiating at least the multilayer reflective layer with laser light or ions from the back side of the substrate. Therefore, it is possible to eliminate the need to set the laser beam or ion power in consideration of the loss due to the film other than the multilayer reflective layer. In addition, damage to the absorption layer due to irradiation with laser light or ions can be suppressed, and changes in the optical properties of the absorption layer can be prevented.

It is a schematic sectional drawing of the reflective mask blank which does not have the light shielding frame which concerns on embodiment of the manufacturing method of the reflective mask blank and reflective mask blank of this invention. It is a schematic sectional drawing of the reflective mask blank of 1st and 2nd embodiment of the manufacturing method of the reflective mask blank and reflective mask blank of this invention. It is a schematic sectional drawing of the reflective mask blank of 3rd and 4th embodiment of the manufacturing method of the reflective mask blank and reflective mask blank of this invention. It is a schematic sectional drawing of the reflective mask blank which does not have the light shielding frame used for the Example of the manufacturing method of the reflective mask blank of this invention, and a reflective mask blank.

Hereinafter, first to fourth embodiments according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the component which has the same function, and the same description shall not be repeated except the case where it refuses.
First, the structure of a reflective mask blank that does not have a light shielding frame and is used in the manufacturing process of the reflective mask blank according to the first to fourth embodiments of the present invention will be described. FIG. 1A and FIG. 1B show cross sections of a reflective mask blank 100 and a reflective mask blank 101 provided with a light shielding frame as an example of a light shielding region according to the first and second embodiments. . Moreover, FIG.1 (c) and FIG.1 (d) show the cross section of the reflective mask blank 200 which provides the light-shielding frame as an example of the light-shielding area | region, and the reflective mask blank 201 based on 3rd and 4th embodiment. ing. That is, in the first and second embodiments, the reflective mask blank 100 of FIG. 1A may be used, or the reflective mask blank 101 of FIG. 1B may be used. In the fourth embodiment, the reflective mask blank 200 of FIG. 1C may be used, or the reflective mask blank 201 of FIG. 1D may be used. The light shielding area provided in the reflective mask blank of the present invention is not limited to the frame shape (light shielding frame), but to the shape of the portion that is desired to avoid being exposed multiple times during pattern transfer to the semiconductor substrate. Depending on the situation, it can be made into an appropriate shape.

In the reflective mask blank 100 shown in FIG. 1A, a multilayer reflective layer 21 and an absorption layer 51 are sequentially formed on the surface of a substrate 11. The reflective mask blank 101 shown in FIG. 1B has a structure in which a multilayer reflective layer 21 and an absorption layer 51 are sequentially formed on the surface of the substrate 11 and a conductive film 71 is formed on the back surface of the substrate 11. ing. That is, in the reflective mask blank 101 of FIG. 1B, the conductive film 71 is formed on the back surface of the substrate 11 of the reflective mask blank 100 of FIG. In the reflective mask blank 200 of FIG. 1C, the multilayer reflective layer 22, the buffer layer 41, the absorption layer 51, and the low reflective layer 61 are sequentially formed on the surface of the substrate 11. The reflective mask blank 201 in FIG. 1D has a structure in which a conductive film 71 is formed on the back surface of the substrate 11 of the reflective mask blank 200 in FIG.
As the substrate 11, for example, low thermal expansion glass can be used. Low thermal expansion glass includes super thermal expansion glass having a higher coefficient of thermal expansion. Further, as the substrate 11, quartz glass, quartz glass added with other elements or compounds, or quartz ceramics having EUV (extreme ultraviolet) transparency can be used. In addition, chalcogenite glass, germanium, calcium fluoride (fluorite), barium fluoride, and zinc sulfide can also be used as the substrate 11 from the viewpoint of a material that transmits the laser when irradiated.

  The multilayer reflective layer 21 shown in FIGS. 1A and 1B is designed to achieve a reflectance of about 60% with respect to EUV near 13.5 nm. Molybdenum (Mo) and silicon ( A laminated film in which 50 pairs of Si) are alternately laminated, and the uppermost layer is made of ruthenium (Ru). The layer adjacent to the Ru layer is a Si layer. The multilayer reflective layer 22 in FIGS. 1C and 1D is designed to achieve a reflectivity of about 60% with respect to EUV near 13.5 nm, and Mo and Si are alternately 40 The uppermost layer is composed of a Si layer. In the transfer circuit pattern region 5 of the absorption layer 51 in FIGS. 1A and 1B, a pattern to be transferred to a semiconductor substrate after the light-shielding frame of each embodiment is formed according to the procedure described later is conventionally known. Formed by a process.

The buffer layer 41 shown in FIGS. 1C and 1D is used to protect the Si layer, which is the uppermost layer of the multilayer reflective layer 22 adjacent to the buffer layer, when the absorbing layer 51 is etched or modified. It is provided and is made of a nitrogen compound (CrN) of chromium (Cr).
The absorption layer 51 in FIGS. 1A to 1D is composed of a nitrogen compound (TaN) of tantalum (Ta) having a high absorption rate with respect to EUV near 13.5 nm. Other materials may be tantalum boron nitride (TaBN) or tantalum silicon (TaSi).

  The low reflection layer 61 in FIGS. 1C and 1D has an antireflection function for ultraviolet light of 190 nm to 260 nm, and is made of Ta oxynitride (TaON). Other materials may be tantalum boron oxide (TaBO) or tantalum silicon oxide (TaSiO). The conductive film 71 shown in FIGS. 1B and 1D is made of CrN. In the transfer circuit pattern region 6 of the absorption layer 51 and the low reflection layer 61 in FIG. 1C and FIG. 1D, the light shielding frame of each embodiment is formed by the procedure described later, and then transferred to the semiconductor substrate. A pattern is formed by a conventionally known process.

(First embodiment)
Hereinafter, the reflective mask blank of the first embodiment and the manufacturing method of the reflective mask blank will be described. First, a reflective mask blank 100 having no light shielding frame shown in FIG.

  Next, a pulse laser is irradiated from the back surface of the substrate 11 of the reflective mask blank 100 to the outside of the transfer circuit pattern region 5, and at least these two layers are formed between the Mo layer and the Si layer of the multilayer reflective layer 21. A composite layer 31 is formed in which an intermediate layer containing Mo and Si as constituent materials is formed. Since the composite layer 31 is an intermediate layer having no interface, the reflectance of light is suppressed and the composite layer 31 functions as the light shielding frame 1. In this way, as shown in FIG. 2A, a reflective mask blank 110 in the middle of production in which the light-shielding frame 1 is formed in a portion that is outside the transfer circuit pattern region 5 is obtained. In this step, by precisely adjusting the energy of the laser irradiation and the optical axis, the interface between the Ru layer and the Si layer and the part of the Mo layer and the Si layer in the multilayer reflective layer 21 can be left.

  A reflective mask with the light shielding frame 1 shown in FIG. 2B is formed by forming a conductive film 71 on the back surface of the substrate 11 of the reflective mask blank 110 in the process of forming the light shielding frame 1 by sputtering. A blank 120 is obtained. When the reflective mask blank 120 is irradiated with EUV near 13.5 nm, EUV that is not absorbed by the absorption layer 51 in the light shielding frame 1 is reflected at the interface between the Ru layer and the Si layer, but the reflected light is absorbed again. Since it passes through the layer 51, it is further absorbed. In this way, the light shielding frame 1 having a high light shielding property can be formed.

In addition, when obtaining the reflective mask blank 120 with the light shielding frame 1 using the reflective mask blank 101 without the light shielding frame of FIG. However, since it is necessary to take into account the loss of laser irradiation energy due to the conductive film 71, it is difficult to form the light shielding frame 1 with high accuracy, but the step of forming the conductive film 71 by sputtering is omitted.
Further, when the thickness of the substrate 11 is sufficiently small, the composite layer 31 can be formed by performing ion implantation instead of laser irradiation.
In the reflection type mask blank 120 thus obtained, the pulse laser does not pass through the absorption layer 51 when forming the composite layer 31 serving as the light shielding frame 1. There is no need to set power. Further, since the absorption layer 51 is not damaged by the transmission of the pulse laser and the optical property does not change, the absorption layer 51 corresponding to the light shielding frame 1 and the absorption corresponding to the periphery of the light shielding frame 1 are absorbed. It can be avoided that the optical properties of the layer 51 are different.

(Second Embodiment)
Hereinafter, the reflective mask blank of the second embodiment and the manufacturing method of the reflective mask blank will be described. About 2nd Embodiment, it is the same as 1st Embodiment until the process of obtaining the reflective mask blank which does not have a light-shielding frame shown to Fig.1 (a).

  Next, a pulse laser is irradiated from the back surface of the substrate 11 of the reflective mask blank 100 to the outside of the transfer circuit pattern region 5, and at least two layers between the Mo layer and the Si layer in the multilayer reflective layer 21 are irradiated. The intermediate layer containing Mo and Si, which are constituent materials, forms a composite layer 32 in which at least an intermediate layer containing Ru and Si, which are constituent materials of the two layers, is formed between the Ru layer and the Si layer. . Since the composite layer 32 is an intermediate layer having no interface, the reflectance of light is suppressed, and the composite layer 32 functions as the light shielding frame 2. In this way, as shown in FIG. 2C, a reflective mask blank 130 in the middle of production in which the light-shielding frame 2 is formed on the outer side of the transfer circuit pattern region 5 is obtained. In this step, the interface between the Ru layer, which is the uppermost layer of the multilayer reflective layer 21, and the absorbing layer 51 can be left by precisely adjusting the energy of the laser irradiation and the optical axis.

  A reflective mask with the light shielding frame 2 shown in FIG. 2D is formed by forming a conductive film 71 on the back surface of the substrate 11 of the reflective mask blank 130 in the process of forming the light shielding frame 2 by sputtering. A blank 140 is obtained. When the reflective mask blank 140 is irradiated with EUV near 13.5 nm, EUV not absorbed by the absorption layer 51 in the light shielding frame 2 is the interface between the absorption layer 51 and the Ru layer that is the uppermost layer of the multilayer reflective layer 21. However, since the reflected light passes through the absorption layer 51 again, it is further absorbed. In this way, the light shielding frame 2 having a high light shielding property can be formed.

In addition, when obtaining the reflective mask blank 140 in which the light shielding frame 2 is formed using the reflective mask blank 101 without the light shielding frame in FIG. However, since it is necessary to take into account the loss of laser irradiation energy due to the conductive film 71, it is difficult to form the light-shielding frame 2 with high accuracy, but the step of forming the conductive film 71 by sputtering is omitted.
Further, when the thickness of the substrate 11 is sufficiently small, the composite layer 32 can be formed by performing ion implantation instead of laser irradiation.
In the reflective mask blank 140 obtained in this way, the pulse laser does not pass through the absorption layer 51 when forming the composite layer 32 serving as the light shielding frame 2. There is no need to set power. Further, since the absorption layer 51 is not damaged by the transmission of the pulse laser and the optical property does not change, the absorption layer 51 corresponding to the light shielding frame 2 and the absorption corresponding to the periphery of the light shielding frame 2 are absorbed. It can be avoided that the optical properties of the layer 51 are different.

(Third embodiment)
Hereinafter, the reflective mask blank of the third embodiment and the method for manufacturing the reflective mask blank will be described. First, a reflective mask blank 200 having no light shielding frame shown in FIG. 1C is prepared.

  Next, a pulse laser is irradiated from the back surface of the substrate 11 of the reflective mask blank 200 to the outside of the transfer circuit pattern region 6, and at least these two layers are interposed between the Mo layer and the Si layer of the multilayer reflective layer 22. The intermediate layer containing Mo and Si, which are constituent materials, has at least Si, Cr, and nitrogen (N) between the Ru layer and the Si layer, between the uppermost layer of the multilayer reflective layer 22 and the buffer layer 41. The composite layer 33 in which the intermediate layers including the respective layers are formed is formed. Since the composite layer 33 is an intermediate layer having no interface, the reflectance of light is suppressed and the composite layer 33 functions as the light shielding frame 3. In this way, as shown in FIG. 3A, a reflective mask blank 210 in the middle of production in which the light-shielding frame 3 is formed on the outer side of the transfer circuit pattern region 6 is obtained. In this step, the interface between the absorption layer 51 and the buffer layer 41 can be left by precisely adjusting the laser irradiation energy and the optical axis.

  A reflective mask with the light-shielding frame 3 shown in FIG. 3B is formed by forming a conductive film 71 on the back surface of the substrate 11 of the reflective mask blank 210 in the process of forming the light-shielding frame 3 by sputtering. A blank 220 is obtained. When the reflective mask blank 220 is irradiated with EUV near 13.5 nm, EUV that is not absorbed by the absorption layer 51 in the light shielding frame 3 is partially reflected at the interface between the absorption layer 51 and the buffer layer 41, but is reflected. Since the light passes through the absorption layer 51 again, it is further absorbed. In this way, the light shielding frame 3 having a high light shielding property can be formed.

In addition, when obtaining the reflective mask blank 220 in which the light-shielding frame 3 is formed by using the reflective mask blank 201 in FIG. However, since it is necessary to take into account the loss of laser irradiation energy due to the conductive film 71, it is difficult to form the light shielding frame 1 with high accuracy, but the step of forming the conductive film 71 by sputtering is omitted.
In the reflection type mask blank 220 obtained in this way, the pulse laser does not pass through the absorption layer 51 and the buffer layer 41 when forming the composite layer 33 serving as the light-shielding frame 3. The need to set the laser power can be eliminated. In addition, since the absorption layer 51 and the buffer layer 41 are not damaged by the transmission of the pulse laser and the optical properties are not changed, the absorption layer 51 and the buffer layer 41 corresponding to the light shielding frame 3 and the light shielding frame 3 are not affected. It is possible to avoid the difference in optical properties between the absorbing layer 51 and the buffer layer 41 corresponding to the periphery.

(Fourth embodiment)
Hereinafter, the reflective mask blank of 4th Embodiment and the manufacturing method of a reflective mask blank are demonstrated. About 4th Embodiment, it is the same as 3rd Embodiment until the process of preparing the reflective mask blank 200 which does not have the light-shielding frame shown to Fig.1 (a).
A pulse laser is irradiated from the back surface of the substrate 11 of the reflective mask blank 200 in the process of production to the outside of the transfer circuit pattern region 6, and at least these two layers are formed between the Mo layer and the Si layer of the multilayer reflective layer 21. An intermediate layer containing Mo and Si as constituent materials is between the uppermost layer of the multilayer reflective layer 22 and the buffer layer 41, and an intermediate layer containing at least Si, Cr and N is between the buffer layer 41 and the absorption layer 51. A composite layer 34 in which intermediate layers containing at least Cr, Ta, and N are formed is formed between the layers. Since the composite layer 34 is an intermediate layer having no interface, the reflectance of light is suppressed and the composite layer 34 functions as the light shielding frame 4. In this way, as shown in FIG. 3C, a reflective mask blank 230 in the middle of production in which the light shielding frame 4 is formed on the portion outside the transfer circuit pattern region 6 is obtained. In this step, the composite layer 34 is formed in a part of the absorption layer 51 by precisely adjusting the energy of the laser irradiation and the optical axis.

  A reflective mask with the light-shielding frame 4 formed as shown in FIG. 3D by forming a conductive film 71 on the back surface of the substrate 11 of the reflective mask blank 230 in the process of forming the light-shielding frame 4 by sputtering. A blank 240 is obtained. When the reflective mask blank 240 is irradiated with EUV near 13.5 nm, EUV that is not absorbed by the absorption layer 51 in the light shielding frame 4 is not reflected because of the composite layer 34. In this way, the light shielding frame 3 having a high light shielding property can be formed.

In addition, when obtaining the reflective mask blank 240 in which the light-shielding frame 4 is formed using the reflective mask blank 201 having no light-shielding frame in FIG. However, since it is necessary to take into account the loss of laser irradiation energy due to the conductive film 71, it is difficult to form the light shielding frame 1 with high accuracy, but the step of forming the conductive film 71 by sputtering is omitted.
In the reflection type mask blank 240 thus obtained, the pulse laser does not pass through the absorption layer 51 and the buffer layer 41 when forming the composite layer 34 to be the light shielding frame 4. The need to set the laser power can be eliminated. Further, the absorption layer 51 and the buffer layer 41 are not damaged by the transmission of the pulse laser, and the composite layer 34 is formed so as to reach a part of the absorption layer 51 as shown in FIG. However, the optical properties hardly change. Therefore, the optical properties of the absorption layer 51 and the buffer layer 41 corresponding to the light shielding frame 4 and the absorption layer 51 and the buffer layer 41 corresponding to the periphery of the light shielding frame 4 are greatly different. Can be avoided.
As described above, the reflective mask blanks 120, 140, 220, 240 of the first to fourth embodiments are the substrate 11, the multilayer reflective layers 21, 22 formed on the surface of the substrate 11, and the multilayer reflection. The transfer circuit pattern regions 5 and 6 formed on the reflective mask manufactured using the reflective mask blanks 120, 140, 220, and 240, having the absorption layer 51 formed on the layers 21 and 22. And having light-shielding frames 1, 2, 3, 4 comprising composite layers 31, 32, 33, 34 formed of intermediate layers of a plurality of layers constituting the interfaces of the multilayer reflective layers 21, 22. The optical properties of the absorbing layer 51 located in the region corresponding to the light shielding frames 1, 2, 3, 4 are equivalent to the optical properties of the absorbing layer 51 located in the region corresponding to the transfer circuit pattern regions 5 and 6. It is characterized by being .
The reflective mask blanks 120, 140, 220, and 240 of the first to fourth embodiments are characterized in that a conductive film 71 is formed on the back surface of the substrate 11, and the third and fourth embodiments. The reflective mask blanks 220 and 240 are characterized in that the composite layers 33 and 34 include a plurality of intermediate layers.
Further, as in the reflective mask blank 120 of the first embodiment, the multilayer reflective layer 21 has the light shielding frame 1 at the interface between the uppermost layer located closest to the absorption layer of the multilayer reflective layer 21 and its adjacent layer. It may exist including a portion corresponding to the formed region.
Further, like the reflective mask blanks 140, 220, and 240 of the second to fourth embodiments, the multilayer reflective layers 21 and 22 include the uppermost layer located on the most absorbing layer side of the multilayer reflective layers 21 and 22, and the layers thereof. There is an interface with the adjacent layer, and the portion corresponding to the region where the light shielding frames 2, 3, and 4 are formed is replaced with the uppermost layer and the adjacent layer instead of the interface between the uppermost layer and the adjacent layer. An intermediate layer (composite layers 32, 33, 34) may be present.
Further, like the reflective mask blanks 120, 140, and 220 of the first to third embodiments, the light shielding frame 1, There may be an interface including a portion corresponding to the region in which 2 and 3 are formed.
Further, as in the reflective mask blank 240 of the fourth embodiment, an interface exists between the absorption layer 51 and its adjacent layer (buffer layer 41), and light is shielded from the interface between the absorption layer 51 and the buffer layer 41. Instead of the interface between the absorption layer 51 and the buffer layer 41, an intermediate layer (composite layer 34) made of the material of the absorption layer 51 and the buffer layer 41 exists in the portion corresponding to the region where the frame 4 is formed. Also good.
The reflective mask blanks 120, 140, 220, and 240 of the first to fourth embodiments include the steps of forming the multilayer reflective layers 21 and 22 on the surface of the substrate 11, and the multilayer reflective layers 21 and 22. And a step of performing laser irradiation or ion implantation on at least the multilayer reflective layers 21 and 22 from the back surface of the substrate 11.

  Examples of the reflective mask blank of the present invention and the manufacturing method thereof will be described below. FIG. 4 shows a reflective mask blank 300 having no light shielding frame prepared in the present embodiment. The reflective mask blank 300 is a stack of 50 pairs of Mo and Si designed to have a reflectivity of about 64% with respect to EUV of 13.5 nm on the surface of the low thermal expansion glass substrate 13 and Ru as the uppermost layer. The multilayer reflection layer 23, the absorption layer 52 made of TaN, and the low reflection layer 62 made of TaON are sequentially formed. The film thickness of the low reflection layer 62 was designed so that the reflectance is 10% or less with respect to ultraviolet light in the vicinity of 250 nm. The total thickness of the low reflection layer 62 and the absorption layer 52 was 50 nm.

  From the back surface of the low thermal expansion glass substrate 13 of the reflective mask blank 300 of FIG. 4, a pulsed laser was irradiated to a frame-shaped region having a line width of 5 mm to form a light shielding frame.

On the back surface of the low thermal expansion glass substrate 13, CrN was deposited by sputtering to produce a reflective mask blank having a light shielding frame.
Using the reflective mask blank, exposure using EUV of 13.5 nm as a light source was performed four times on the same region on the semiconductor substrate. In the exposed region on the semiconductor substrate, only the region corresponding to the light-shielding frame on the manufactured reflective mask blank was exposed four times, but the resist photosensitivity in the region on the semiconductor substrate was confirmed. Was not.

1, 2, 3, 4 ... light shielding frame 5, 6 ... transfer circuit pattern region 11 ... substrate 13 ... low thermal expansion glass substrate 21, 22, 23 ... multilayer reflective layers 31, 32, 33, 34 ... Composite layer 41 ... Buffer layer 51, 52 ... Absorbing layer 61, 62 ... Low reflection layer 71 ... Conductive film 100, 101, 200, 201, 300 ... Light shielding Reflective mask blanks without a frame 110, 130, 210, 230 ... Reflective mask blanks in the process of production 120, 140, 220, 240 ... Reflective mask blanks with a light shielding frame formed

Claims (9)

A substrate,
A multilayer reflective layer formed on the substrate surface;
An absorbing layer formed on the multilayer reflective layer;
In a reflective mask blank having
A composite layer formed on the outer side of a transfer circuit pattern region formed on a reflective mask manufactured using the reflective mask blanks and formed with an intermediate layer of a plurality of layers constituting each interface of the multilayer reflective layer. Having a light-shielding frame,
A reflective mask characterized in that an optical property of the absorbing layer located in a region corresponding to the light shielding frame is equivalent to an optical property of the absorbing layer located in a region corresponding to the transfer circuit pattern region. blank.   The reflective mask blank according to claim 1, wherein a conductive film is formed on a back surface of the substrate.   The reflective mask blank according to claim 1, wherein the composite layer includes a plurality of the intermediate layers.   In the multilayer reflective layer, an interface between the uppermost layer located on the most absorption layer side of the multilayer reflective layer and its adjacent layer is present including a portion corresponding to the region where the light shielding frame is formed. The reflective mask blank according to claim 3.   In the multilayer reflective layer, there is an interface between the uppermost layer located on the most absorption layer side of the multilayer reflective layer and its adjacent layer, and the portion corresponding to the region where the light shielding frame is formed in the interface, The reflective mask blank according to claim 3, wherein an intermediate layer made of a material of the uppermost layer and its adjacent layer is present instead of the interface.   The reflective mask blank according to claim 3, wherein an interface is present between the absorption layer and an adjacent layer including a portion corresponding to a region where the light shielding frame is formed.   An interface exists between the absorption layer and the adjacent layer, and a portion corresponding to a region where the light shielding frame is formed in an interface between the absorption layer and the adjacent layer includes the absorption layer and the adjacent layer. The reflective mask blank according to claim 3, wherein an intermediate layer made of a material of the absorption layer and its adjacent layer is present in place of the interface.   In a manufacturing method of a reflective mask blank including at least a step of forming a multilayer reflective layer on a substrate surface and a step of forming an absorption layer above the multilayer reflective layer, at least the multilayer reflective layer from the back surface of the substrate And a method of manufacturing a reflective mask blank, comprising the step of performing laser irradiation or ion implantation.   9. The method of manufacturing a reflective mask blank according to claim 8, further comprising a step of forming a conductive film on the back surface of the substrate after the laser irradiation or ion implantation step.

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