JP6300466B2 - Mask blank substrate, mask blank, imprint mold, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a mask blank substrate used for an imprint mold, a mask blank, an imprint mold formed using these, and a method of manufacturing the same.

  For the formation of various fine patterns such as circuit patterns in semiconductor devices, optical function patterns in optical components, and magnetic layer patterns in magnetic recording media such as hard disk drives, the imprint method, which is one of the transfer methods, is applied. It is being considered.

  In the imprint method, an imprint mold (stamper) in which a fine mold pattern is formed is used as an original plate, and the imprint mold is directly pressed against a resist film such as a photo-curing resin applied on a transfer object. Thus, the mold pattern is transferred to the resist film. Therefore, according to the imprint method, it is possible to transfer a large amount of the same fine pattern.

  As one aspect of the imprint mold as described above, one disclosed in Patent Document 1 is known. This imprint mold has a configuration in which a concave portion is provided on the main surface on the back side with respect to the front main surface on which the mold pattern is formed, and the thickness of the substrate in the region where the mold pattern is formed is thinner than the surrounding area. ing. Thus, after transferring the mold pattern to the photo-curable resin applied to the transfer object, the mold pattern has a thinner substrate than the surrounding by applying multiple forces to the imprint mold. The forming region can be curved in the direction in which the mold pattern spreads, and the mold pattern can be easily peeled from the photocurable resin.

  When manufacturing an imprint mold having such a configuration, a recess is formed by grinding the main surface on the back side with a processing tool before the mold pattern is formed on the front main surface on which the mold pattern of the substrate is formed. And a method of bonding a substrate on which a mold pattern is formed and a substrate in which a through hole is formed between two main surfaces facing each other as illustrated in Patent Document 1.

Special table 2009-536591

  However, in the method of forming a recess by grinding the main surface on the back side, the residual stress remains on the bottom surface of the recess after digging because the processing tool is pressed strongly against the main surface on the back side. There are concerns. Further, when the concave bottom surface after grinding is polished to a mirror surface, there is a concern that abrasive grains remain on the bottom surface and side surfaces of the concave portion.

  On the other hand, in the case of a method of bonding two substrates, there is no concern like a method of forming a recess by grinding with a processing tool. However, in this method, it is not easy to bond the two substrates so that the outer peripheral end surfaces coincide with each other, and it is difficult to avoid a step on the outer peripheral end surfaces of the two substrates joined by the bonding.

  Here, when the imprint mold is fixed to the mold mounting portion of the transfer device, in general, the back surface side of the imprint mold is chucked, and the outer peripheral end surface of the imprint mold is also fixed by a fixing tool. This is to prevent the imprint mold from shifting in the horizontal direction with respect to the transfer object.

  In this case, if the above-described step is present on the outer peripheral end surface of the imprint mold, it is difficult to fix the outer peripheral end surface of the imprint mold in a normal state with the fixing device of the transfer device. For this reason, after joining two board | substrates, it is necessary to shape | mold an outer peripheral end surface by grinding or grinding | polishing with respect to an outer peripheral end surface. However, when grinding or polishing is performed on the outer peripheral end face, there is a possibility that polishing abrasive grains or the like may adhere to the concave portion of the bonded substrate, which is a problem.

  Therefore, in the present invention, when imprinting is performed using an imprint mold provided with a recess by joining two base materials, the imprint mold can be normally fixed without polishing the outer peripheral end face. An object of the present invention is to provide a mask blank substrate and a mask blank for imprint mold, and further an imprint mold. Moreover, an object of this invention is to provide these manufacturing methods.

  The present invention has the following configuration as means for solving the above-described problems.

(Configuration 1)
A mask blank substrate used for manufacturing an imprint mold, comprising a first base material and a second base material, wherein the first base material has two main surfaces facing each other. And an outer peripheral end surface, and having a hole having a predetermined shape penetrating between the two main surfaces, the second base material includes two opposing main surfaces and an outer peripheral end surface, One main surface of the base material and one main surface of the second base material are joined, and the main surface on the side serving as the joint surface of the second base material and the first base material A mask is characterized in that a recess is formed by the hole, and the outer peripheral end surface of one of the first base material and the second base material protrudes over the entire periphery from the other outer peripheral end surface. This is a blank substrate.

(Configuration 2)
2. The mask blank substrate according to Configuration 1, wherein an outer peripheral end face of the first base material protrudes over an entire periphery rather than an outer peripheral end face of the second base material.

(Configuration 3)
At least one of said 1st base material and said 2nd base material consists of glass, It is a board | substrate for mask blanks of the structure 1 or 2 characterized by the above-mentioned.

(Configuration 4)
4. The mask blank substrate according to any one of configurations 1 to 3, wherein the recess is formed in a region larger than a mold pattern formation region set on the other main surface of the second base material.

(Configuration 5)
5. The mask blank substrate according to claim 1, wherein the surface roughness of the bottom surface of the recess is an arithmetic average roughness Ra of 0.3 nm or less.

(Configuration 6)
A mask blank substrate manufacturing method used for manufacturing an imprint mold, wherein a first base material having two opposed main surfaces and an outer peripheral end surface is penetrated between the two main surfaces. A through hole forming step of forming a hole of a predetermined shape, a step of preparing a second base material provided with two opposing main surfaces and an outer peripheral end surface, and one of the first base material in which the holes are formed A main surface of the second base material and a first main surface of the second base material, and in the joining step, the main surface on the side that becomes the joint surface of the second base material and the first surface A recess is formed by the hole of the base material, and the outer peripheral end surface of one of the first base material and the second base material is extended over the entire circumference from the other outer peripheral end surface. Method of manufacturing mask blank substrate characterized by protruding It is.

(Configuration 7)
In the bonding step, the outer peripheral end surface of the first base material is protruded over the entire periphery from the outer peripheral end surface of the second base material. is there.

(Configuration 8)
The method for manufacturing a mask blank substrate according to Configuration 6 or 7, wherein each of the first base material and the second base material is made of glass.

(Configuration 9)
6. A mask blank comprising a mask blank substrate according to any one of Structures 1 to 5, wherein a thin film for pattern formation is provided on the other main surface of the second base material.

(Configuration 10)
A method for forming a mask blank substrate according to any one of Structures 6 to 8, wherein a pattern is formed on the other main surface of the second base material before or after the bonding step in the mask blank substrate manufacturing method. It has the thin film formation process which provides the thin film for a mask, The manufacturing method of the mask blank characterized by the above-mentioned.

(Configuration 11)
An imprint mold, wherein a mold pattern is formed on the other main surface of the second base material in the mask blank substrate according to any one of configurations 1 to 5.

(Configuration 12)
It includes a method for manufacturing the mask blank according to Configuration 10, and includes a step of etching the other main surface of the thin film and the second base material after the thin film forming step in the method for manufacturing the mask blank. It is a manufacturing method of an imprint mold.

  According to the present invention, in the mask blank substrate provided with a recess by joining two base materials, the outer peripheral end surface of one base material is protruded over the entire periphery from the other outer peripheral end surface. When the imprint mold configured as described above is mounted on the transfer device, the imprint mold can be normally fixed by sandwiching the outer peripheral end face having no step from both sides.

It is a figure for demonstrating the structure of the board | substrate for mask blanks of this invention. It is sectional drawing for demonstrating the structure of the mask blank of this invention. It is sectional drawing for demonstrating the structure of the imprint mold of this invention. It is sectional process drawing for demonstrating the manufacturing method of the imprint mold of this invention. It is sectional process drawing explaining the imprint method using the imprint mold of this invention.

  The present inventor has conducted intensive research on means for solving the above-described technical problem that occurs when a substrate having a recess on the main surface on the back side by joining two base materials. As a result, instead of making the outer peripheral dimensions of the first base material and the second base material the same, the outer peripheral dimension of any of the base materials is increased as a whole, and the first base material and the second base material are increased. When the materials are bonded together, the outer peripheral end surface of either the first base material or the second base material relatively protrudes over the entire periphery from the outer peripheral end surface of the other base material, The conclusion was reached. Thereby, the mask blank substrate formed by joining the first base material and the second base material has a shape in which either one of the first member side and the second member side protrudes over the entire outer peripheral end surface. It becomes. When the imprint mold manufactured from the mask blank substrate is fixed to the mold mounting portion of the transfer apparatus, the outer peripheral end surface of the protruding base material may be fixed with a fixing tool. For this reason, after joining the first base material and the second base material, it is not necessary to perform grinding or polishing on the outer peripheral end face, and there is no possibility that the abrasive grains or the like adhere to the concave portion of the substrate.

  The detailed configuration of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same component and it demonstrates.

≪Mask blank substrate≫
1A and 1B are diagrams for explaining the configuration of a mask blank substrate according to the present invention. FIG. 1A is a sectional view and FIG. 1B is an exploded perspective view. The mask blank substrate 1 shown in these drawings is processed as an imprint mold having an uneven mold pattern, and is before the mold pattern is formed. In the following description, the imprint mold is an imprint mold produced from the mask blank substrate 1.

  The mask blank substrate 1 is obtained by bonding and bonding a first base material 10 and a second base material 20 together. Among these, the 1st base material 10 is a board | substrate which has the hole 10a as a through-hole in the center of the flat base material which has two main surfaces, and supports the 2nd base material 20 (henceforth support). (Referred to as substrate 10). The second base material 20 is a substrate on which a mold pattern is formed (hereinafter referred to as a mold substrate 20). The mask blank substrate 1 having a structure in which the support substrate 10 and the mold substrate 20 are bonded has a configuration in which one opening of the hole 10a of the support substrate 10 has a recess 1a closed by the mold substrate 20. .

  In particular, the mask blank substrate 1 is characterized in that the outer peripheral end surface of one of the support substrate 10 and the mold substrate 20 protrudes over the entire periphery from the other outer peripheral end surface. Here, as an example, it is assumed that the outer peripheral end surface of the support substrate 10 protrudes over the entire periphery from the outer peripheral end surface of the mold substrate 20. Next, detailed configurations of the support substrate 10 and the mold substrate 20 will be described.

  The support substrate 10 is a substrate that supports the mold substrate 20 by having a hole 10a having a predetermined shape penetrating between the two main surfaces in a plate-like material having two opposing main surfaces and an outer peripheral end surface. . One main surface 11 of the support substrate 10 is a surface bonded to the mold substrate 20 (hereinafter referred to as a bonding surface 11). The other main surface 12 of the support substrate 10 is a surface that is fixed to the mold mounting portion of the transfer device when the imprint mold is fixed to the transfer device (hereinafter referred to as a chuck surface 12).

  The support substrate 10 has a planar shape viewed from the main surface side that is slightly larger than the planar shape of the mold substrate 20, and constitutes the outermost peripheral end surface of the mask blank substrate 1. That is, the outer peripheral end surface of the support substrate 10 is the outer peripheral end surface of the mask blank substrate 1.

  Such support substrate 10 preferably has a rectangular shape or polygonal shape as viewed from the main surface side. Thereby, when fixing the imprint mold formed using this mask blank substrate 1 to the mold mounting part of the transfer device, the imprint mold is easily sandwiched and fixed from the opposing outer peripheral end face side. In consideration of such fixing, the outer shape of the support substrate 10 is desirably a rectangular shape having a high degree of parallelism in which a variation in width between opposing outer peripheral end faces is 50 μm or less, more preferably 40 μm or less. In this case, it is desirable that the flatness of the end face is 20 μm or less, more preferably 10 μm or less.

  When the imprint mold is fixed to the mold mounting portion of the transfer device, the thickness t1 of the support substrate 10 is set to a size that allows the imprint mold to be sandwiched and fixed from the outer peripheral end face side. Although depending on the material of the support substrate 10, the mold bonded to the support substrate 10 by applying a plurality of pressing forces to the support substrate 10 in a state where the imprint mold is fixed to the mold mounting portion of the transfer device. When the substrate 20 is curved, it is assumed that the support substrate 10 is deformed by the applied pressing force.

  The hole 10 a provided in the support substrate 10 constitutes a recess 1 a of the mask blank substrate 1. It is most desirable that the center of the hole 10a coincides with the center of the support substrate 10, and at least the deviation is preferably 100 μm or less, more preferably 50 μm or less.

  The opening shape of the hole 10a may be a rectangular shape or a polygonal shape in addition to the circular shape as illustrated, and is appropriately determined according to the use, size, etc. of the imprint mold. However, the opening shape of the hole 10a is preferably a perfect circle. Thus, the bottom portion 20a of the concave portion 1a formed of a part of the mold substrate 20 is obtained by changing the internal pressure by using the concave portion 1a formed by the hole 10a as a sealed space or by applying a pressing force to the support substrate 10 from a plurality of locations. Is deformed, the influence of the internal pressure and the pressing force becomes a concentric distribution, and the deformation of the bottom portion 20a is easily controlled.

  The size of the hole 10a preferably has a size that encloses a pattern formation region a set on the pattern formation surface 22 of the mold substrate 20 described below. Such a hole 10a has a diameter when the opening shape is circular, and preferably has a length in the short side direction of 50 mm or more in the case of a rectangle, and is preferably 60 mm or more. In consideration of securing the rigidity of the support substrate 10 with the holes 10a, when the size of the support substrate 10 is about 152 mm square, the diameter of the hole 10a or the length in the short side direction is 100 mm or less. It is desirable that it is 90 mm or less.

  On the other hand, the mold substrate 20 is a plate-like material having two opposing main surfaces and an outer peripheral end surface. One main surface 21 of the mold substrate 20 is a surface bonded to the support substrate 10 (hereinafter referred to as a bonding surface 21). The other main surface 22 of the mold substrate 20 is a surface on which a mold pattern is formed (hereinafter referred to as a pattern formation surface 22). The pattern formation surface 22 has a pattern formation region a at the center thereof.

  The pattern formation region a is preferably sized to be included in the recess 1a in the mask blank substrate 1. Thereby, when the bottom part 20a of the recessed part 1a comprised by a part of mold substrate 20 is changed, the whole area | region of the pattern formation area a can be changed.

  The pattern formation region a is preferably arranged at the center of the recess 1a. Thereby, when pattern transfer is performed on the transfer object using the imprint mold, the deformation at the time of pressing or peeling off the imprint mold is expanded concentrically with respect to the center of the pattern formation region a. Can do.

  Such a mold substrate 20 has a planar shape as viewed from the main surface side that is slightly smaller than the planar shape of the support substrate 10, and the outer peripheral end surface is located inside the outer peripheral end surface of the support substrate 10. Moreover, the planar shape seen from the main surface side of the mold substrate 20 is not limited to the rectangular shape or the polygonal shape as illustrated, and may be a circular shape or an elliptical shape. Such a planar shape and size of the mold substrate 20 ensure that sufficient bonding strength with respect to the support substrate 10 is ensured and the positioning accuracy in bonding to the support substrate 10 is taken into consideration from the outer periphery of the support substrate 10. It should be a size that does not protrude.

  For example, when the shape of the main surface of the mold substrate 20 is rectangular, the length of one side of the main surfaces 21 and 22 is a length obtained by adding 10 mm to the diameter of the hole 10a in consideration of the bonding strength with the support substrate 10. It is required to be more than that. The length of one side of the main surfaces 21 and 22 is preferably not less than the length of 20 mm added to the diameter of the hole 10a, and more preferably not less than the length of 30 mm. When the main surfaces 11 and 12 of the support substrate 10 and the main surfaces 21 and 22 of the mold substrate 20 are both rectangular, the length of one side of the main surfaces 21 and 22 of the mold substrate 20 is The length is required to be equal to or less than the length obtained by subtracting 1 mm from the length of one side of the main surfaces 11 and 12. The length of one side of the main surfaces 21 and 22 of the mold substrate 20 is preferably equal to or less than the length of one side of the main surfaces 11 and 12 of the support substrate 10 less than or equal to the length of 10 mm or less. Is more preferable.

  In particular, when the mold substrate 20 is made of a light-transmitting material, the surface roughness of the region constituting the bottom 20a of the recess 1a on the bonding surface 21 of the mold substrate 20 is arithmetic average roughness. Ra is 0.3 nm or less. Thus, when pattern transfer is performed on the transfer object using the imprint mold, light scattering is caused when the resist film of the transfer object is cured by light irradiation from the concave portion 1a through the mold substrate 20. The transmittance of light transmitted from the bottom 20a to the pattern formation region a on the other main surface 22 can be increased.

  The pattern formation surface 22 of the mold substrate 20 is required to have a surface roughness of square root mean square roughness Rq of 0.2 nm or less, preferably 0.15 nm or less, and more preferably 0.1 nm or less. preferable. Further, the flatness in the pattern formation region a on the pattern formation surface 22 of the mold substrate 20 is required to be 0.1 μm or less. Further, the flatness in the pattern formation region a is preferably 0.05 μm or less. As will be described later, when an imprint mold is manufactured using the mask blank substrate 1, the pattern forming surface 22 in the outer region of the pattern forming region a in the mold substrate 20 is entirely formed to form a pedestal structure. Drilled down by etching. For this reason, the flatness of the outer region of the pattern formation region a on the pattern formation surface 22 is not required to be equal to or higher than that of the bonding surface 21.

  The thickness t2 of the mold substrate 20 is preferably in the range of 0.1 to 0.25 times the total thickness of the mask blank substrate 1. By making the thickness of the mold substrate 20 smaller than 0.25 times, the force applied to bend the mold substrate 20 does not become too large, and there is a risk that it will not return to its original shape after deformation or cracks may occur. Absent. Further, by making the thickness of the mold substrate 20 larger than 0.1 times, it is possible to prevent cracks from occurring when the mold substrate 20 is bent.

The material of the support substrate 10 and the mold substrate 20 as described above is not particularly limited as long as it is a material having appropriate strength and rigidity required for use as an imprint mold, and can be arbitrarily used. For example, glass materials such as quartz glass, SiO ₂ —TiO ₂ low expansion glass, soda lime glass, aluminosilicate glass, CaF ₂ glass, metal materials such as silicon, stainless steel (SUS), aluminum, copper, nickel, and resin materials Etc. Of these, glass materials are particularly suitable. The glass material can be processed with very high accuracy and is excellent in flatness and smoothness. Therefore, when pattern transfer is performed using the imprint mold obtained by the present invention, distortion of the transfer pattern does not occur. Can perform highly accurate pattern transfer. Therefore, at least one of the support substrate 10 and the mold substrate 20 is preferably made of glass.

In addition, when the mask blank substrate 1 is for producing an imprint mold for performing pattern transfer on a photo-curing resin, at least the mold substrate 20 is desirably a glass material, such as quartz glass or SiO ₂ —TiO ₂ low expansion glass is particularly preferable.

  Further, the support substrate 10 and the mold substrate 20 may be made of the same material or different materials. When different materials are used, it is particularly preferable to combine materials having different thermal expansion coefficients. Since the support substrate 10 and the mold substrate 20 are made of materials having different thermal expansion coefficients, the recess 1a is formed on the mask blank substrate 1, and heating or cooling is performed when the imprint mold is released. A relative tensile stress or compressive stress acts between the support substrate 10 and the mold substrate 20 to facilitate mold release (that is, release with a smaller force). For example, quartz glass and silicon have a thermal expansion coefficient that differs by an order of magnitude. Therefore, when silicon is used for the support substrate 10 and quartz glass is used for the mold substrate 20, when the imprint mold is cooled when the imprint mold is released, A difference in thermal expansion occurs between the support substrate 10 and the mold substrate 20, and a compressive stress acts on the support substrate 10, while a tensile stress acts relatively on the mold substrate 20. The bottom portion 20a of the recessed portion 1a expands outward and curves so that the imprint mold can be easily released.

  In the present embodiment, both the support substrate 10 and the mold substrate 20 use one base material, but one of the support substrate 10 and the mold substrate 20 or both of them are each two or more base materials. It is good also as a structure which joined.

  The mask blank substrate 1 having the above-described configuration has a configuration in which the outer peripheral end surface of the support substrate 10 protrudes over the entire periphery from the outer peripheral end surface of the mold substrate 20. For this reason, when fixing an imprint mold having a mold pattern formed on the pattern formation region a of the mask blank substrate 1 to the mold mounting portion of the transfer device, the outer peripheral end face without a step is sandwiched from both sides. It becomes possible to fix the print mold in a normal state. Therefore, it is possible to perform pattern transfer with high accuracy by using an imprint mold configured using the mask blank substrate 1.

<< Manufacturing Method for Mask Blank Substrate >>
Next, a method for manufacturing the mask blank substrate 1 described with reference to FIG. 1 will be described.

  First, a through-hole forming step is performed in which a hole 10a having a predetermined shape that penetrates between the two main surfaces is formed in the support substrate 10 including two opposing main surfaces and outer peripheral end surfaces. The support substrate 10 before forming the holes 10a uses a flat plate-like base material finished to the above-described predetermined outer diameter shape, outer dimensions, and plate thickness.

  The processing means for forming the hole 10a is not particularly limited, and a known micromachining method such as a machining method or an etching method can be arbitrarily used. Specifically, for example, laser processing, cutting processing, ion beam milling processing represented by gas cluster ion beam (GCIB), magneto-rheological finishing (MRF) processing, water jet processing, etching (wet etching) , Dry etching), polishing using a polishing slurry, and the like, and may be appropriately selected and used in consideration of the material of the support substrate 10 and the shape and size of the hole 10a to be processed.

  Moreover, the mold substrate 20 provided with two main surfaces and outer peripheral end surfaces which oppose is prepared. The mold substrate 20 uses a flat plate-like base material finished to the above-described predetermined shape, outer dimensions, and plate thickness. In addition, when the mask blank substrate 1 manufactured here is an imprint mold that performs pattern transfer on a photo-curing resin, the mold substrate 20 is made of a light-transmitting material, and the main surface on the side that becomes the bonding surface 21 thereof. It is assumed that the surface is polished so that at least the region serving as the bottom surface of the concave portion 1a described above has an arithmetic average roughness Ra of 0.3 nm or less.

  Next, a bonding step is performed in which the support substrate 10 in which the holes 10a are formed and the mold substrate 20 are bonded and bonded together. In this bonding step, one main surface (bonding surface 11) of the support substrate 10 and one main surface (bonding surface 21) of the mold substrate 20 are bonded. Thereby, a recess 1 a is formed in which the opening on the bonding surface 11 side in the hole 10 a of the support substrate 10 is closed by the bonding surface 21 of the mold substrate 20. At this time, the support substrate 10 is supported so that the outer peripheral end surface protrudes over the entire periphery from the outer peripheral end surface of the mold substrate 20 and the pattern formation region a set on the pattern formation surface 22 of the mold substrate 20 is the center of the recess 1a. The substrate 10 and the mold substrate 20 are bonded in a positioned state.

  The means for joining the support substrate 10 and the mold substrate 20 is not particularly limited as long as a sufficient adhesive force can be obtained between the support substrate 10 and the mold substrate 20. Here, the sufficient adhesive force is an adhesive force that does not cause separation between the support substrate 10 and the mold substrate 20 when the imprint mold is used. Specifically, for example, methods such as a welding (welding) method, an adhesion method, an anodic bonding method, a hydrofluoric acid bonding method, and an optical welding method (optical contact) can be preferably used.

  The welding (welding) method is a method in which the joining surfaces of two members to be joined (in this embodiment, the support substrate 10 and the mold substrate 20) are fused and integrated (fused) by heating or the like. This method can be applied regardless of the materials of the support substrate 10 and the mold substrate 20 and when the materials of the support substrate 10 and the mold substrate 20 are the same or different.

  The bonding method is a method in which two members to be bonded (in this embodiment, the support substrate 10 and the mold substrate 20) are bonded to each other using an adhesive (for example, an ultraviolet (UV) curable adhesive is preferable). It is. Although this method depends on the type of adhesive used, it is preferable because particularly high adhesiveness can be obtained when the support substrate 10 and the mold substrate 20 are made of the same material. In this case, in the produced mask blank substrate 1, an adhesive layer made of an adhesive is sandwiched between the support substrate 10 and the mold substrate 20.

  The anodic bonding method is a method in which the bonding surfaces of two members to be bonded (in this embodiment, the support substrate 10 and the mold substrate 20) are superposed and heated (for example, about 300 to 500 ° C.) with a voltage (for example, 400). (Approx. ~ 600V), and by this, bonding by covalent bonding can be performed at the bonding interface. However, this method can be preferably applied when one of the support substrate 10 and the mold substrate 20 is a glass material and the other is silicon or metal. When glass materials are bonded to each other, a thin film such as SiN, SiC, or amorphous silicon is preferably formed on at least one bonding surface.

  The hydrofluoric acid bonding method is a method in which hydrofluoric acid is dropped on the bonding surfaces of two members to be bonded (in this embodiment, the support substrate 10 and the mold substrate 20), and then the bonding surfaces are overlapped with each other and applied with a predetermined pressure. This is a method of bonding by pressing, and is suitable for bonding glass materials to each other.

  In addition, the optical welding method (also referred to as optical contact) means that the bonding surfaces of two members (in this embodiment, the support substrate 10 and the mold substrate 20) finished with high flatness and high smoothness are brought into close contact ( In some cases, pressure is applied simultaneously), and bonding is performed by intermolecular force (intermolecular bond) generated at the bonding interface. This method is particularly suitable when bonding precisely polished glass planes.

  As described above, since each joining means has its own characteristics, a suitable joining method may be appropriately selected and used depending on the materials of the support substrate 10 and the mold substrate 20 to be joined.

  In addition, when joining the support substrate 10 and the mold substrate 20, in order to obtain a strong joining force, the flatness of each of the joining surfaces 11 and 21 is high, regardless of which joining method is used. In particular, the optical welding method requires high flatness and high smoothness of the joint surface.

  Therefore, prior to the step of bonding the support substrate 10 and the mold substrate 20, the bonding surface 11 of the support substrate 10 and the bonding surface 21 of the mold substrate 20 have a predetermined flatness, for example, a flatness of about 5 μm or less. It is preferable to include the process of finishing. Here, the flatness is a value representing a warp (deformation amount) of the surface indicated by TIR (Total Indicated Reading). For example, in a 142 mm square area, a plane defined by the least square method with reference to the substrate surface is a focal plane. And the absolute value of the difference in height between the highest position of the substrate surface above the focal plane and the lowest position of the substrate surface below the focal plane. However, in the case of bonding by the optical welding method, high bonding strength is required in the present invention. Therefore, the surface accuracy of both bonding surfaces is, for example, λ / 10 (at λ = 633 nm) and the flatness is set to high accuracy of 60 nm or less. It is desirable to keep it.

  The processing means for finishing the joint surfaces 11 and 21 of both the support substrate 10 and the mold substrate 20 so as to have a predetermined flatness need not be particularly limited, and a known machining method, etching method, etc. Any surface processing method can be used. Specifically, for example, processing by local plasma etching, ion beam processing represented by gas cluster ion beam (GCIB), magnetic-fluid polishing (MRF) processing, etching (wet etching, dry etching), A surface treatment method such as mirror polishing using a polishing slurry or chemical mechanical polishing (CMP) may be appropriately selected in consideration of the material of the substrate. The glass material can be subjected to surface processing with extremely high accuracy, and high flatness and high smoothness can be obtained.

  In addition, regarding the support substrate 10, either the process of forming the hole 10 a having a predetermined shape or the process of finishing the bonding surface 11 to have a predetermined flatness may be performed first, but the process load of the process is increased. From the viewpoint of reducing, it is preferable to perform the process of first finishing the joining surface 11 to have a predetermined flatness and then the process of drilling the hole 10a having a predetermined shape.

  Further, the pattern forming surface 22 of the mold substrate 20 is finished in a suitable surface state so that a thin film for forming a mask blank for forming a fine mold pattern (uneven pattern) of the imprint mold can be formed. It is desirable.

  The manufacturing method of the mask blank substrate having the above-described configuration has a configuration in which the support substrate 10 and the mold substrate 20 are bonded so that the outer peripheral end surface of the support substrate 10 protrudes over the entire periphery from the outer peripheral end surface of the mold substrate 20. is there. Accordingly, it is not necessary to polish the outer peripheral end face after bonding, and therefore, a mask blank having an outer peripheral end face without a step without increasing the number of steps and without attaching abrasive grains or the like to the recess 1a. It becomes possible to produce the substrate 1 for use.

≪Mask blank≫
FIG. 2 is a cross-sectional view for explaining the configuration of the mask blank of the present invention. The mask blank 2 shown in this figure is a mask blank for imprint molding, and a thin film 30 for pattern formation is formed on the pattern formation surface 22 of the mold substrate 20 in the mask blank substrate 1 of the present invention described above. It is the structure provided.

  The thin film 30 for pattern formation may have a single layer structure or a laminated structure. As an example of the thin film 30 having a single layer structure, a thin film 30 made of a material using chromium (Cr) can be given. In addition, as the thin film 30 having the laminated structure, at least the lower layer located on the pattern forming surface 22 side is made of a material using tantalum (Ta), and the upper layer is made of a material using chrome (Cr). As an example.

  The material using chromium (Cr) includes Cr alone, or Cr compounds such as Cr nitride, oxide, carbide, carbonitride, oxynitride, oxycarbonitride, etc., and the thin film 30 has a single layer structure. In this case, CrOCN is particularly preferable.

  As a material using tantalum (Ta), for example, Ta compounds such as TaHf, TaZr, TaHfZr, etc., or using these Ta compounds as a base material, for example, auxiliary materials such as B, Ge, Nb, Si, C, and N are added. The material etc. are illustrated.

  The illustration of the structure and material of the thin film 30 as described above is merely an example, and the present invention is not necessarily limited to these.

  Although illustration is omitted here, the mask blank 2 for imprint mold of the present invention may have a form in which a resist film is further formed on the thin film 30.

  In the mask blank 2 having the above-described configuration, as will be described in detail later, a mold pattern is formed on the pattern forming surface 22 of the mask blank substrate 1 using the patterned thin film 30 as a mask. A print mold is produced.

  Since the mask blank 2 having the above-described configuration is configured using the mask blank substrate 1 of the present invention, the same effect as the mask blank substrate 1 of the present invention can be obtained.

≪Mask blank manufacturing method≫
The mask blank 2 described with reference to FIG. 2 is manufactured by forming a pattern forming thin film 30 on the pattern forming surface 22 of the mask blank substrate 1 described above. In this case, the step of forming the thin film 30 on the pattern formation surface 22 of the mold substrate 20 after performing the bonding step of the support substrate 10 and the mold substrate 20 in the same manner as described in the method for manufacturing the mask blank substrate 1. Can be done.

  A method for forming the thin film 30 is not particularly limited, but a sputtering film forming method is particularly preferable. The sputtering film forming method is preferable because a uniform film having a constant film thickness can be formed.

  For example, when the thin film 30 made of CrOCN is formed by a sputtering film forming method, a Cr target is used as a sputtering target, and a mixed gas of argon gas, helium gas, carbon dioxide, and nitrogen is introduced into the chamber as a sputtering gas, and the sputtering process is performed. Do the membrane.

  As another example of the manufacturing method of the mask blank 2, before performing the bonding step of the support substrate 10 and the mold substrate 20 in the above-described manufacturing method of the mask blank substrate 1, the pattern blank 22 on the mold substrate 20 is formed. The procedure for forming the thin film 30 is exemplified. However, it is assumed that the pattern forming surface 22 on which the thin film 30 is formed is finished in a suitable surface state so that the thin film 30 can be formed. In this case, the mask blank 2 is produced by bonding the support substrate 10 provided with the holes 10a and the mold substrate 20 on which the thin film 30 is formed. In this case, the support substrate 10 and the mold substrate 20 are joined in the same manner as described in the previous method for manufacturing the mask blank substrate 1 as long as the thin film 30 already formed is not affected.

<Effect of manufacturing method of mask blank of the present invention>
The method for manufacturing a mask blank having the above-described configuration includes the method for manufacturing a mask blank substrate of the present invention. For this reason, the mask blank 2 which has the outer peripheral end surface without a level | step difference, without increasing the number of processes and adhering an abrasive grain etc. to the recessed part 1a similarly to the effect of the preparation method of the board | substrate for mask blanks above. Can be produced.

≪Imprint mold≫
FIG. 3 is a cross-sectional view for explaining the configuration of the imprint mold of the present invention. The imprint mold 3 shown in this figure has a configuration in which a mold pattern P is provided on the pattern forming surface 22 of the mask blank substrate 1 of the present invention described above.

  The imprint mold 3 has, for example, a pedestal structure 23 obtained by etching the periphery of the pattern formation region a on the pattern formation surface 22, and an uneven mold pattern P is provided on the surface of the pedestal structure 23.

  In such an imprint mold 3, as described also in the mask blank substrate 1 described above, it is preferable that the pattern formation region a is disposed at the center of the recess 1a. As a result, as described in the subsequent imprint method, when the bottom 20a of the recess 1a formed of the mold substrate 20 is curved so as to protrude toward the pattern formation surface 22, the pattern formation region a It is possible to prevent the resist film sandwiched between the mold patterns P from being crushed when all of the mold patterns P are opened outward and only some of the mold patterns P are opened outward. In particular, in the case of the imprint mold 3 that performs pattern transfer with respect to the photocurable resin, it is possible to perform normal incidence of light for curing the photocurable resin over the entire pattern formation region a. The resin can be cured.

<Effect of imprint mold of the present invention>

  Since the imprint mold 3 having the above-described configuration is configured using the mask blank substrate 1 of the present invention, as described in the mask blank substrate 1 of the present invention, when mounted on a transfer apparatus, By sandwiching the outer peripheral end surface of the protruding base material from both sides, it is possible to make the transfer device normal. As a result, highly accurate pattern transfer can be performed.

≪Imprint mold manufacturing method≫
Next, the manufacturing method of the imprint mold of this invention using the mask blank demonstrated above is demonstrated. FIG. 4 is a cross-sectional process diagram for explaining a method for producing an imprint mold of the present invention. Hereinafter, a method for producing an imprint mold will be described with reference to FIG.

  First, as shown in FIG. 4A, a resist film 41 is formed by applying, for example, a resist for electron beam drawing on the entire surface of the thin film 30 of the mask blank 2 of the present invention and performing a predetermined baking process. The mask blank 2 may be manufactured by any one of the manufacturing methods described above in the mask blank manufacturing method. That is, the thin film 30 may be formed before the bonding step between the support substrate 10 and the mold substrate 20 or may be formed after the bonding step.

  Next, as shown in FIG. 4B, after a predetermined pattern (for example, a line and space pattern) is drawn on the resist film 41 using an electron beam drawing machine or the like, the resist film 41 is developed to form a resist pattern 41a. . Here, a resist pattern 41a is formed on the resist film 41 on the pattern formation region a in the pattern formation surface 22 of the mask blank 2.

  4C, the mask blank 2 on which the resist pattern 41a is formed is introduced into a dry etching apparatus, and the thin film 30 is etched using the resist film 41 on which the resist pattern 41a is formed as a mask. Thereby, a thin film pattern 30 a is formed on the thin film 30. Here, the mask blank 2 may be once taken out from the dry etching apparatus, and the remaining resist film 41 may be removed. Depending on the layer structure and material of the thin film 30, the etching process may be performed in two or more stages instead of one stage.

  Next, the mold substrate 20 is etched by using the thin film 30 on which the thin film pattern 30 a is formed as a mask, and an uneven mold pattern P is formed in the pattern formation region a in the pattern formation surface 22 of the mold substrate 20.

  Next, as shown in FIG. 4D, a resist pattern 43 for forming a base structure is formed on the thin film 30 in the mask blank 2 on which the mold pattern P is formed. The resist pattern 43 for forming the pedestal structure is formed in a shape that covers the pattern formation region a where the mold pattern P is formed. Next, the thin film 30 outside the pattern formation region a is removed by etching using the resist pattern 43 as a mask, and the pattern formation surface 22 side of the mold substrate 20 is further etched. This etching is performed by wet etching, for example. By such etching, a pedestal structure 23 is formed in which the pattern formation region a in which the mold pattern P is formed is higher than the outer region. After the etching is completed, the resist pattern 43 and the thin film 30 are removed.

  As a result, as shown in FIG. 4E, the imprint mold 3 in which the mold pattern P is provided on the base structure 23 on the pattern forming surface 22 side of the mold substrate 20 is obtained.

  In addition, the above is an example of the manufacturing method of the imprint mold of this invention, and the manufacturing method of the imprint mold of this invention is not limited to this. The imprint mold manufacturing method of the present invention may be any imprint mold manufacturing method including the mask blank manufacturing method of the present invention. The following procedure is illustrated as another example of the method for manufacturing such an imprint mold 3.

  First, in the method of manufacturing the mask blank 2 described above, the thin film 30 is formed on the pattern forming surface 22 of the mold substrate 20 before performing the bonding step between the support substrate 10 and the mold substrate 20. Next, by performing the procedure described with reference to FIGS. 4A to 4D, the mold pattern P is formed on the pattern formation surface 22 of the mold substrate 20 and the pedestal structure 23 is further formed.

  Next, the mold substrate 20 on which the mold pattern P is formed and the support substrate 10 having the holes 10a are joined. In this case, the support substrate 10 and the mold substrate 20 are joined in the same manner as described in the previous method for manufacturing the mask blank substrate 1. At this time, on the mold pattern P, it is preferable to leave the resist pattern 43 that serves as a mask when the base structure 23 is formed. Thereby, the support substrate 10 and the mold substrate 20 can be bonded and bonded together in a state where the mold pattern P is protected by the resist pattern 43. Then, after the support substrate 10 and the mold substrate 20 are bonded, the resist pattern 43 and the thin film 30 are removed, and the imprint mold 3 is completed.

<Effect of manufacturing method of imprint mold of the present invention>
The method for producing an imprint mold having the above-described configuration includes the method for producing a mask blank substrate of the present invention. For this reason, similarly to the effect of the manufacturing method of the previous mask blank substrate, the outer peripheral end surface of the base material on the protruding side without increasing the number of steps and without attaching abrasive grains or the like to the recess 1a. It is possible to produce an imprint mold 3 having the following.

≪Method of forming fine pattern using imprint mold≫
FIG. 5 is a cross-sectional process diagram for explaining an imprint method using the imprint mold of the present invention. Hereinafter, pattern formation by the imprint method will be described with reference to FIG.

  First, as shown in FIG. 5A, the imprint mold 3 is fixed to the mold mounting portion of the transfer device. At this time, the inside of the vacuum groove 51a is sucked while the vacuum groove 51a of the suction chuck 51 of the transfer device is closed by the chuck surface 12 of the imprint mold 3, and the imprint mold 3 is chucked. Note that the suction chuck 51 used here is configured such that, for example, a portion facing the concave portion 1a of the fixed imprint mold 3 transmits light energy such as ultraviolet rays.

  Further, the imprint mold 3 is fixed by the mold holding portion 53 of the transfer device in a state where the imprint mold 3 is sandwiched from both sides on the outer peripheral end surface of the support substrate 10.

  Further, a resist film (for example, a UV curable resin or a thermosetting resin) 63 is applied and formed on the transfer object 61 on which a pattern is to be formed. At this time, when the imprint mold 3 is a replica mold, the transfer object is each substrate constituting an electronic device such as a semiconductor substrate or an electronic substrate. On the other hand, if the imprint mold 3 is a master mold, the transfer object 61 is a mask blank for producing a replica mold.

  Next, as shown in FIG. 5B, the pattern formation surface 22 of the imprint mold 3 is disposed opposite to the resist film 63 formed on the transfer target 61, and the mold of the imprint mold 3 is opposed to the resist film 63. Press pattern P. In this state, the resist film 63 is cured, and the uneven shape of the mold pattern P is transferred to the resist film 63. At this time, if the resist film 63 is a UV curable resin, the resist film 63 is cured by irradiating the resist film 63 with UV light through the mold substrate 20 by UV irradiation from the suction chuck 51 side.

  Thereafter, as shown in FIG. 5C, the imprint mold 3 is peeled off from the cured resist film 63 to obtain a resist pattern 63a to which the uneven shape of the mold pattern P is transferred. At this time, a portion of the mold substrate 20 that is the bottom 20a of the recess 1a is curved so as to be convex toward the pattern forming surface 22 side, so that a resist film is formed from the peripheral portion of the pattern forming region a toward the center. By sequentially peeling the mold pattern P from 63, the imprint mold 3 can be easily peeled from the resist film 63.

  The bending of the mold substrate 20 as described above is performed by, for example, a configuration in which a plurality of actuators are provided in the mold holding unit 53 of the transfer device, and the support substrate 10 is pressed so as to be compressed from the periphery by driving these actuators. . As another method, a sealed space is provided by the suction chuck 51 of the transfer device and the recess 1a of the imprint mold 3, and this sealed space is pressurized.

  Next, as shown in FIG. 5D, the transfer object 61 is etched using the resist pattern 63 a as a mask to form a concavo-convex pattern 61 a on the transfer object 61.

  In the formation of the pattern 61a by the imprint method as described above, the imprint mold 3 produced using the mask blank of the present invention is used. For this reason, by providing the concave portion 1a, it is possible to easily remove the mold at the time of mold release with a smaller force, and therefore effectively prevent damage to the pattern transferred onto the transfer target or damage to the mold. Can do. In addition, since the pattern transfer can be performed in a state where the imprint mold 3 is accurately fixed to the transfer device, it is possible to transfer the pattern with high accuracy.

DESCRIPTION OF SYMBOLS 1 ... Mask blank substrate 1a ... Concave part 2 ... Mask blank 3 ... Imprint mold 10 ... Support substrate (1st base material)
10a ... hole 20 ... mold substrate (second base material)
20a ... bottom surface of recess 30 ... thin film a ... mold pattern formation region P ... mold pattern

Claims (12)

A mask blank substrate used to manufacture an imprint mold,
Comprising a first substrate and a second substrate;
The first base material is made of glass, has two main surfaces facing each other and an outer peripheral end surface, and has a circular hole penetrating between the two main surfaces,
The second base material is made of glass and includes two main surfaces and an outer peripheral end surface facing each other.
One main surface of the first base material and one main surface of the second base material are joined, and the main surface on the side serving as the joint surface of the second base material and the first base material A recess is constituted by the hole of the base material,
The outer peripheral end surface of the first base material protrudes over the entire periphery from the outer peripheral end surface of the second base material,
The two main surfaces of the second base material are rectangular, and the length of one side of these two main surfaces is equal to or longer than the diameter of the hole plus 10 mm. Mask blank substrate. The length of one side of the two main surfaces of the second base material is equal to or less than a length obtained by subtracting 4 mm from the length of the two main surfaces of the first base material. The mask blank substrate as described in 1.   The mask blank substrate according to claim 1, wherein the hole has a diameter of 50 mm or more.   4. The mask blank substrate according to claim 1, wherein the recess is formed in a region larger than a mold pattern forming region set on the other main surface of the second base material. 5.   5. The mask blank substrate according to claim 1, wherein the surface roughness of the bottom surface of the recess is an arithmetic average roughness Ra of 0.3 nm or less. A method of manufacturing a mask blank substrate used for manufacturing an imprint mold,
A through-hole forming step of forming a circular hole penetrating between the two main surfaces in a first base material made of glass and having two opposing main surfaces and an outer peripheral end surface;
A step of preparing a second base material made of glass and having two opposing main surfaces and an outer peripheral end surface;
A bonding step of bonding one main surface of the first base material in which the hole is formed and one main surface of the second base material;
In the joining step, a concave portion is formed by the main surface on the side serving as the joining surface of the second base material and the hole of the first base material, and the outer peripheral end surface of the first base material is Project over the entire circumference from the outer peripheral end surface of the second substrate,
The two main surfaces of the second base material are rectangular, and the length of one side of these two main surfaces is equal to or longer than the diameter of the hole plus 10 mm. A method for manufacturing a mask blank substrate. The length of one side of the two main surfaces of the second base material is equal to or less than a length obtained by subtracting 4 mm from the length of the two main surfaces of the first base material. The manufacturing method of the mask blank board | substrate of description.   The method for manufacturing a mask blank substrate according to claim 6 or 7, wherein the hole has a diameter of 50 mm or more.   A thin film that functions as a mask when a mold pattern is formed on the other main surface of the second base material of the second substrate of the mask blank substrate according to claim 1 by etching. A mask blank characterized by comprising:   A method for producing a mask blank substrate according to any one of claims 6 to 8, wherein before or after the bonding step in the method for producing a mask blank substrate, on the other main surface of the second base material, A method of manufacturing a mask blank, comprising a thin film forming step of providing a thin film that functions as a mask when a mold pattern is formed on the other main surface by etching.   An imprint mold, wherein a mold pattern is formed on the other main surface of the second base material in the mask blank substrate according to claim 1.   It has the process of carrying out the etching process of the other main surface of the said thin film and the said 2nd base material after the thin film formation process in the manufacturing method of the said mask blank including the manufacturing method of the mask blank of Claim 10. A method for manufacturing an imprint mold.

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