JP2015065214A - Method for manufacturing imprint mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an imprint mold having a fine uneven pattern in which no unnecessary closed loop is present.SOLUTION: The method comprises: preparing a premold 1 having one or more protruding patterns 4 which is an uneven pattern in a dimension less than the minimum dimension that can be patterned by a lithographic process and which has a closed loop structure, and a mold substrate 12 having a mask layer 13 on one surface thereof, the mask layer having such a shape in a plan view that the layer does not overlap a part of a space defined by the closed loop structure in the protruding pattern 4 of the premold 1; bringing the premold 1 and the mold substrate 12 to be closer to each other and spreading and curing a resist 31 therebetween; then separating the premold to form a resist pattern 32; etching the mask layer 13 by using the resist pattern 32 as a mask to form a fine mask pattern 13'; and etching the mold substrate 12 by using the fine mask 13' as a mask to form a fine pattern 14 to manufacture an imprint mold 11.

Description

  The present invention relates to an imprint mold manufacturing method, for example, an imprint mold manufacturing method having a pattern with a half pitch of 20 nm or less.

For example, in semiconductor devices, further miniaturization of patterns is required due to demands for high-speed operation and low power consumption operation, but pattern formation using an electron beam lithography method is difficult to form a pattern with a half pitch of 20 nm or less. Alternatively, there is a problem that it is not desirable from the viewpoint of throughput.
In recent years, a pattern forming technique using an imprint method has attracted attention as a fine pattern forming technique that replaces the photolithography technique. The imprint method is a pattern formation technique that transfers a micro structure at an equal magnification by using a mold member (mold) having a micro concavo-convex structure and transferring the concavo-convex structure to a molding object. Applications in various fields are being promoted. In the manufacture of a mold used for the imprint method, for example, an electron beam sensitive resist is applied to a metal thin film such as chromium provided on a substrate such as quartz glass, and exposure and development are performed using an electron beam lithography method. A resist pattern is formed, the metal thin film is etched using the resist pattern as an etching mask to form a fine pattern, the substrate is etched using the fine pattern as an etching mask, and an uneven structure is formed on the surface of the substrate. However, here too, there are the above-mentioned problems in pattern formation using electron beam lithography.

  In order to solve the problem in pattern formation using such an electron beam lithography method, a pattern formation film is formed so as to cover a core pattern formed using the electron beam lithography method. A method using a so-called sidewall process is proposed in which a pattern structure is formed on the side wall of the core pattern by etching, the core pattern is then removed to leave the pattern structure, and this pattern structure is used as an etching mask. (Patent Document 1). However, in the sidewall process for forming the pattern structure on the sidewall of the core pattern, a closed loop (hereinafter referred to as a closed loop) structure is generated in the formed pattern structure. Therefore, in the line and space pattern formed by forming a pattern structure on the metal layer and etching the metal layer using the pattern structure as an etching mask, an unnecessary closed loop structure exists, and each line is It is not isolated. For this reason, for example, when used as an electric circuit, there is a problem that it does not function as a wiring because it is not electrically isolated as a line.

  On the other hand, the imprint mold is used for the purpose of improving the wet spread of the imprint resin with respect to the surface having the concavo-convex structure of the mold, the mold releasability between the cured imprint resin and the mold, and the like. Dummy patterns and alignment marks are formed in addition to the main pattern for the purpose of improving the density of the pattern in the surface having the concavo-convex structure, or for the purpose of aligning the mold and the transferred substrate during imprinting. Things have been done. Dummy patterns and alignment marks formed for such purposes can be simultaneously formed by the same sidewall process as that of the main pattern if they have the same fine dimensions as the main pattern. However, when all the dummy patterns and the like having the same fine dimensions as the main pattern are formed by the sidewall process, there is a problem that the manufacturing cost of the mold increases from the viewpoint of manufacturing yield. Moreover, since the concavo-convex structure provided in the mold is a fine pattern, there is a problem that the frequency of occurrence of defects in the mold during imprinting increases. In consideration of such a problem and the dummy pattern formed for the purpose as described above is not directly related to the function of the semiconductor device or the like manufactured using the imprint mold, the dummy pattern or The alignment mark is not designed with the same dimensions as the main pattern, but is designed with a large dimension of, for example, about several tens of nanometers to several micrometers. For example, a method of forming an imprint mold having a main pattern having a fine pattern with a half pitch of 20 nm or less and a dummy pattern or a large pattern of alignment marks larger than the main pattern by a sidewall process has been proposed. (Patent Document 2).

  In the imprint mold manufacturing method described in Patent Document 2, a hard mask layer (such as a chromium film) and a core layer (such as a silicon oxide film) are stacked in this order on a mold base material, and an electron is formed on the core layer. A first resist pattern is formed by a line lithography method, etc., the core layer is etched by using the first resist pattern as a mask to form a core layer pattern, and the core layer pattern is slimmed to form a core material. A sidewall pattern is formed on the sidewall of the material. Next, a second resist pattern is formed so as to cover the core material and the side wall pattern in a region (a region where a dummy pattern and an alignment mark are formed) excluding a region where a main pattern having a fine pattern is formed. Only the core material in the region where the pattern is to be formed is removed by etching. As a result, the side wall pattern from which the core material is removed exists in the area where the main pattern is formed, and the side wall pattern where the core material remains in the area where the dummy pattern or alignment mark having a larger dimension than the main pattern is formed. Is formed. Thereafter, the hard mask layer is etched using the side wall pattern from which the core material is removed and the side wall pattern from which the core material remains as a mask to form a hard mask, and the mold substrate is etched through the hard mask. . As a result, it is possible to manufacture an imprint mold having a main pattern having a fine pattern and a dummy pattern or alignment mark having a size larger than that of the main pattern. The imprint mold manufactured in this way has a closed loop structure in the main pattern. In the invention described in Patent Document 2, a pattern is formed on the mask layer on the workpiece by the imprint method using the imprint mold, and the mask layer is etched through the pattern to form a mask pattern. Then, the closed loop structure of the mask pattern is removed. As a method for removing the closed loop structure, a method is employed in which a region other than the closed loop structure portion is protected with a resist, the closed loop structure is removed by etching in this state, and then the resist is peeled off.

JP 2009-10317 A Japanese Patent No. 4825891

  However, for example, when a fine pattern having a half pitch of 20 nm or less is formed on a workpiece using an imprint mold manufactured by the method described in Patent Document 2, the following problems are encountered. Exists. That is, in the removal method of the closed loop structure described in Patent Document 2, there is a problem that the mask pattern may be damaged or fallen due to the resist coating / peeling operation, and foreign matter may be attached, and the process becomes complicated. is there. Further, there is a problem in that the surface state of the object to be processed is different between the portion where the etching for removing the closed loop structure is performed and the portion protected by the resist. The problem with such a closed loop structure removal process is that, in the manufacture of an imprint mold, when the closed loop structure is removed at the side wall pattern stage, or when the closed loop structure is removed at the hard mask stage, or for molds. In the case of removing the closed loop structure in the mold after etching the base material, the problem arises in any case. Therefore, the problem of removing the closed loop structure in the case of manufacturing an imprint mold for forming only a fine pattern by a sidewall process is a problem that cannot be solved in Patent Document 2.

When an imprint mold for simultaneously forming a fine main pattern and a large pattern of a dummy pattern or an alignment mark on a workpiece is manufactured by the manufacturing method described in Patent Document 2, a core material or a sidewall pattern Since the dimensions of the surface are extremely fine, the surface tension of the developer or rinse liquid acts on the sidewall pattern in a series of wet processes including a development process, a rinsing process, and a drying process in the lithography process when forming the second resist pattern. The sidewall pattern not covered with the second resist pattern may fall down, be damaged, peel off, or deform. When such a sidewall pattern falls, breaks, peels, deforms, etc., the production yield of the imprint mold decreases. Therefore, a method for reliably manufacturing an imprint mold for simultaneously forming a fine pattern and a large pattern using a sidewall process has not yet been established.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a method for manufacturing an imprint mold that does not have an unnecessary closed loop structure and has a fine uneven pattern. .

  In order to achieve such an object, the present invention provides a method for producing an imprint mold having a fine pattern having a concavo-convex pattern having a dimension less than the minimum dimension that can be patterned by a lithography method, wherein the pattern is less than the minimum dimension. A pre-mold having one or more convex patterns having a closed-loop structure, and a plan view shape that does not partially overlap a space defined by the closed-loop structure in the convex pattern of the pre-mold. A mold base comprising a mask layer on one surface, a space defined by a closed loop structure of a convex pattern of the premold, and the premold and the mold base; The pre-mold and the mold substrate are aligned so that the mask layers do not partially overlap each other. And developing the resist supplied between and curing the resist, separating the pre-mold and forming a resist pattern, and etching the mask layer using the resist pattern as an etching mask, The method includes a step of forming a mask pattern and a step of forming the fine pattern by etching the base material for mold using the fine mask pattern as an etching mask.

As another aspect of the present invention, a large mask pattern for forming a large pattern having a dimension equal to or larger than the minimum dimension on the mold substrate is the same surface as the surface on which the mask layer is located, In the step of forming the pre-mold and the mold base so as not to overlap with the convex pattern of the pre-mold, and etching the mold base, the fine mask pattern The mold substrate is etched using the large mask pattern as an etching mask to form the fine pattern and the large pattern.
As another aspect of the present invention, a core material pattern is formed on a mask layer located on one surface of the premold base material, a side wall material film is formed so as to cover at least the core material pattern, and the side wall Etching is performed on the material film and the core material pattern, a sidewall pattern made of the sidewall material film is formed on the sidewall of the remaining core material pattern, the core material pattern is removed, and the sidewall pattern is used as an etching mask. The mask layer is etched to form a mask pattern, and the pre-mold is manufactured by etching the pre-mold substrate using the mask pattern as an etching mask.
As another aspect of the present invention, the core material pattern is formed using an electron beam sensitive resist or a photosensitive resist.
As another aspect of the present invention, the core material pattern is subjected to a slimming process for reducing the core material pattern to a desired dimension.

  In the present invention, alignment is performed so that the space defined by the closed loop structure of the convex pattern of the pre-mold and the mask layer do not partially overlap, and the pre-mold and the mold substrate are brought close to each other by an imprint method. A resist pattern is formed, and the mask layer is etched using the resist pattern as a mask to form a fine mask pattern. Therefore, the fine mask pattern does not have a closed loop structure. An imprint mold having an uneven pattern can be manufactured.

FIG. 1 is a plan view showing an example of a pre-mold used in the method for producing an imprint mold of the present invention. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a plan view for explaining a process of the pre-mold manufacturing example. FIG. 4 is a cross-sectional view for explaining the steps of the pre-mold manufacturing example. FIG. 5 is a cross-sectional view for explaining a process of a pre-mold manufacturing example. FIG. 6 is a plan view showing an example of a mold substrate used in the method for producing an imprint mold of the present invention. 7 is a longitudinal sectional view taken along line III-III in FIG. FIG. 8 is a cross-sectional view for explaining the manufacturing process of the imprint mold of the present invention. FIG. 9 is a cross-sectional view for explaining the manufacturing process of the imprint mold of the present invention. FIG. 10 is a plan view for explaining the manufacturing process of the imprint mold of the present invention. FIG. 11 is a plan view showing an example of a mold base material provided with a large mask pattern. FIG. 12 is a plan view for explaining the manufacturing process of the imprint mold of the present invention. FIG. 13 is a longitudinal sectional view taken along the line VI-VI in FIG. FIG. 14 is a plan view for explaining a method for producing an imprint mold of the present invention when a pre-mold and a mold base material according to another embodiment are used. FIG. 15 is a plan view for explaining a method for producing an imprint mold of the present invention when a pre-mold and a mold base material according to another embodiment are used. FIG. 16: is a top view for demonstrating the manufacturing method of the imprint mold of this invention at the time of using the premold of another aspect, and the base material for molds. FIG. 17: is a top view for demonstrating the manufacturing method of the imprint mold of this invention at the time of using the premold of another aspect and the base material for molds. FIG. 18 is a perspective view for explaining an example of forming a sidewall pattern in the production of the pre-mold used in the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Note that the drawings are schematic or conceptual, and the dimensions of each member, the ratio of sizes between the members, etc. are not necessarily the same as the actual ones, and represent the same members. However, in some cases, the dimensions and ratios may be different depending on the drawing.
The imprint mold manufacturing method of the present invention includes a pre-mold having a concavo-convex pattern having a dimension less than the minimum dimension that can be patterned by a lithography method and having one or more convex patterns having a closed loop structure, and a convex of the pre-mold. A mold base material provided with a mask layer on one surface having a planar shape that does not partially overlap with a space defined by the closed loop structure in the shape pattern, and a premold and a mold base material Are aligned so that the space defined by the closed loop structure of the convex pattern of the pre-mold and the mask layer do not partially overlap, and the resist supplied between the pre-mold and the mold substrate is removed. The step of unfolding and curing the resist, and separating the pre-mold to form a resist pattern; A step of forming a fine mask pattern by etching the mask layer using the strike pattern as an etching mask, and a dimension less than the minimum dimension that can be formed by lithography using the fine mask pattern as an etching mask and etching the mold substrate. Forming a fine pattern having a concave-convex pattern.

[Premold]
First, the premold used for the manufacturing method of the imprint mold of this invention is demonstrated. FIG. 1 is a plan view showing an example of a pre-mold, and FIG. 2 is a longitudinal sectional view taken along the line II of FIG. The pre-mold 1 is provided with a plurality of convex patterns 4 having a closed loop structure, which is a concavo-convex pattern having a dimension less than the minimum dimension that can be patterned by a lithography method, on one surface 2a of the substrate 2. In the illustrated example, three convex patterns 4 are shown for convenience, but the convex patterns are not limited to the illustrated number. Here, the dimension less than the minimum dimension that can be patterned by the lithography method is a dimension that is difficult or impossible to form a pattern by a lithography method such as an electron beam lithography method or a photolithography method (the resolution limit of the lithography method ( The dimension is less than the limit exposure line width), and is, for example, about several nanometers to tens of nanometers.

When the resist used for imprinting in the imprint mold manufacturing to be described later is photo-curable, the material of the base material 2 constituting the pre-mold 1 is a material that can transmit irradiation light for curing them. For example, in addition to glass such as quartz glass, silicate glass, calcium fluoride, magnesium fluoride, and acrylic glass, sapphire and gallium nitride, and resins such as polycarbonate, polystyrene, acrylic, and polypropylene, or Any of these laminated materials can be used. Moreover, when the resist to be used is not photocurable, or when it is possible to irradiate light for curing the resist from the mold base material described later, the base material 2 does not have to be light transmissive. In addition to the above materials, for example, metals such as silicon, nickel, titanium, and aluminum, alloys thereof, oxides, nitrides, or any laminated material thereof can be used.
The thickness of the base material 2 of the pre-mold 1 can be set in consideration of the shape of the mold, the strength of the material, suitability for handling, and the like, and can be appropriately set within a range of about 300 μm to 10 mm, for example. The substrate 2 has a so-called mesa structure in which one surface 2a having a plurality of convex patterns 4 has a convex structure of one step or two steps or more with respect to the surrounding area. There may be.

Each of the plurality of convex patterns 4 provided in the pre-mold 1 has a closed loop structure. In the example shown in FIG. 1 and FIG. 2, six line-shaped patterns in which the half pitch P is arranged in parallel with a dimension smaller than the minimum dimension that can be patterned by a lithography method have two ends as one unit. Are connected to form an endless continuous pattern, thereby forming three convex patterns 4 having a closed loop structure.
Here, an example of manufacture of such a premold 1 is demonstrated, referring FIGS. 3-5. FIG. 3 is a plan view for explaining the process of the manufacturing example of the pre-mold 1, and FIGS. 4 and 5 are cross-sectional views for explaining the process of the manufacturing example of the pre-mold 1.
First, the core material pattern 5 is formed on the mask layer 3 located on one surface 2a of the premold base 2 (FIGS. 3A and 4A). 4A is a vertical cross-sectional view taken along line II-II in FIG. 3A, and FIGS. 4 and 5 below also show vertical cross-sections at corresponding positions.

  The mask layer 3 can be made of a material having an etching rate smaller than that of the pre-mold substrate 2, such as a metal such as chromium, titanium, tantalum, silicon, and aluminum, chromium nitride, and chromium oxide. Chrome compounds such as chromium oxynitride, tantalum compounds such as tantalum oxide, tantalum oxynitride, tantalum boride, tantalum oxynitride, titanium nitride, silicon nitride, silicon oxynitride, etc. It can be used in the above combination. Such a mask layer 3 can be formed by, for example, a vacuum film forming method such as a sputtering method.

  The core material pattern 5 can be formed on the mask layer 3 by, for example, an electron beam lithography method, a photolithography method, or an imprint method. When the electron beam lithography method is used, an electron beam sensitive resist is disposed on the mask layer 3, and the core material pattern 5 having a desired shape can be formed by performing electron beam drawing and development. In the case of using a photolithography method, a core resist pattern 5 is formed by disposing a photosensitive resist on the mask layer 3, exposing by light irradiation through a photomask having a light transmitting portion of a desired shape, and developing. Can be formed. In the case of using the imprint method, a curable resist is supplied onto the mask layer 3, and a mold having a desired concavo-convex structure is brought close to the curable resist to be developed between the mask layer 3 and the mold. Then, the curable resist is cured, and then the mold is separated to form a resist pattern. Next, the core material pattern 5 can be formed by removing the thin film (residual film) present in the recesses of the resist pattern by oxygen ashing or the like.

The planar view shape of the core material pattern 5 formed in this way is a rectangular shape in the illustrated example, but is not limited thereto. The dimension in plan view of the core material pattern 5 can be appropriately set in consideration of the dimension after slimming described later and the dimension of the convex pattern 4 to be formed. Furthermore, the thickness of the core material pattern 5 can be appropriately set within a range of 10 nm to 1 μm, for example.
In this manufacturing example, next, the core material pattern 5 is processed by, for example, oxygen plasma and slimmed to form the core material pattern 5 ′ (FIGS. 3B and 4B). In the present invention, slimming is to reduce the width of the pattern of the core material pattern 5 and reduce the film thickness by dry etching or the like (including oxygen plasma treatment). For example, by performing slimming by oxygen plasma treatment, the pattern width can be reduced to about ½ without changing the pattern pitch of the core material pattern 5 formed first.
Next, as shown in FIGS. 3C and 4C, a sidewall material film 6 is formed on the mask layer 3 of the premold base 2 so as to cover the core material pattern 5 '. The sidewall material film 6 can be formed by, for example, a low temperature vacuum film forming method such as an ALD method (atomic layer deposition method) or a CVD method (chemical vapor deposition method). In particular, the ALD method can be suitably used because it can be accurately formed at a low temperature regardless of the shape of the surface on which the atomic layer is deposited, such as an uneven surface or a curved surface.

Such a sidewall material film 6 damages the core material pattern 5 ′ at a temperature sufficiently lower than the glass transition temperature of the resist constituting the core material pattern 5 ′, for example, 20 to 100 ° C., preferably about room temperature. A film can be formed using a material that can be formed without being applied. For example, the mask layer 3 is a metal layer, and the material of the sidewall material film 6 that can exhibit etching resistance in the etching of the mask layer 3 includes silicon-based oxide such as silicon oxide, silicon nitride, and silicon oxynitride, oxidation Examples thereof include aluminum-based materials such as aluminum, hafnium-based materials such as hafnium oxide, and titanium-based materials such as titanium nitride.
The side wall material film 6 to be formed may be formed of a single layer or a stacked film of two or more layers. The film thickness of the sidewall material film 6 is preferably set to a film thickness corresponding to a half pitch design. For example, a series of atomic layers are continuously formed until a desired thickness of about several nanometers to about tens of nanometers is obtained. Can be stacked.

Next, as shown in FIG. 3D and FIG. 4D, the sidewall material film 6 is etched and etched back to expose the mask layer 3 and the remaining core material. The sidewall material film 6 is left only on the sidewall of the pattern 5 '. Thereby, a sidewall pattern 7 made of the sidewall material film 6 is formed. Etch back is an operation of cutting the entire surface in the thickness direction by etching, and can be performed using an appropriate etching gas depending on the material constituting the sidewall material film 6. For example, when the sidewall material film 6 is made of silicon oxide, etching back can be performed using a fluorine-based gas such as CF ₄ , CHF ₃ , or C ₂ F ₆ as an etching gas. As described above, the core material pattern 5 'formed using the resist is shaved in the thickness direction by such etching. In the illustrated example, the etching rate of the core material pattern 5 ′ is shown as being substantially the same as the etching rate of the sidewall material film 6, but the former etching rate may be higher.
Thereafter, the core material pattern 5 ′ is removed (FIG. 5A), and then the mask layer 3 is etched using the sidewall pattern 7 as an etching mask to form a mask pattern 3 ′ (FIG. 5B). . Next, using the mask pattern 3 ′ as an etching mask, the premold substrate 2 is etched to produce a premold 1 having three convex patterns 4 having a closed loop structure (FIG. 5C).

[Mold substrate]
Next, an example of the mold substrate used in the method for producing an imprint mold of the present invention will be described. FIG. 6 is a plan view showing an example of a mold substrate, and FIG. 7 is a longitudinal sectional view taken along line III-III in FIG. The mold substrate 12 includes a mask layer 13 on one surface 12a. This mask layer 13 is a space defined by the closed loop structure in each convex pattern 4 of the pre-mold 1 (in FIG. 6, the convex pattern 4 is indicated by an alternate long and short dash line, and the space defined by the closed loop structure is hatched. And has a plan view shape that does not partially overlap. In the example shown in FIG. 6, the mask layer 13 is set so as not to overlap both ends of the space defined by the closed loop structure of each convex pattern 4.

  When the resist used in the imprint using the imprint mold produced according to the present invention is photocurable, the material of the mold base 12 is a material that can transmit the irradiation light for curing them. For example, in addition to glass such as quartz glass, silicate glass, calcium fluoride, magnesium fluoride, and acrylic glass, sapphire and gallium nitride, and resins such as polycarbonate, polystyrene, acrylic, and polypropylene, or Any of these laminated materials can be used. In addition, when the resist to be used is not photocurable, or when it is possible to irradiate light for curing the resist from the pattern formation substrate side used in imprinting, the mold base 12 is light transmissive. In addition to the above materials, for example, metals such as silicon, nickel, titanium, and aluminum, alloys thereof, oxides, nitrides, or any laminated material thereof can be used. .

The thickness of the mold base 12 can be set in consideration of the shape of the imprint mold manufactured according to the present invention, the strength of the material, the handling suitability, and the like, for example, appropriately set in the range of about 300 μm to 10 mm. Can do. The mold base 12 has a so-called mesa structure in which one surface 12a provided with the mask layer 13 has a convex structure of one step or two steps or more with respect to the surrounding area. May be.
The mask layer 13 provided in the mold base 12 can be made of a material having a lower etching rate than the mold base 12 and having etching resistance, such as a metal such as chromium, titanium, tantalum, silicon, and aluminum. Chromium compounds such as chromium nitride, chromium oxide and chromium oxynitride, tantalum compounds such as tantalum oxide, tantalum oxynitride, tantalum boride, tantalum oxynitride, titanium nitride, silicon nitride, silicon oxynitride, etc. Or it can be used in a combination of two or more. Such a mask layer 13 is formed, for example, by forming a thin film on the mold substrate 12 by a vacuum film forming method such as a sputtering method using the material as described above, providing a resist on the thin film, and performing a photolithography method. The resist pattern can be formed by, for example, and the thin film can be etched using the resist pattern as an etching mask.

  As described above, the mask layer 13 has a plan view shape that does not partially overlap the space defined by the closed loop structure in each convex pattern 4 of the pre-mold 1. Further, as will be described later, the portion of the mask layer 13 that does not overlap with the convex pattern 4 of the pre-mold 1 in the plan view shape remains on the mold substrate 12 as a fine mask pattern, and thus is manufactured. The shape and dimensions of the mask layer 13 in plan view can be set in consideration of the shape of the uneven pattern required for the imprint mold.

[Manufacture of imprint molds]
Next, an embodiment of manufacturing an imprint mold of the present invention will be described with reference to FIGS. 8 to 10 as an example using the pre-mold 1 and the mold base 12 described above. 8 and 9 are cross-sectional views for explaining the manufacturing process of the imprint mold, and FIG. 10 is a plan view for explaining the manufacturing process of the imprint mold.
First, the resist 31 is supplied onto the mold base 12, and the premold 1 and the mold base 12 are defined by the closed loop structure of each convex pattern 4 of the premold 1, as shown in FIG. The resist 31 is developed between the pre-mold 1 and the mold base 12 by aligning them so that they do not overlap each other and the mask layer 13 (FIG. 8A).
The resist 31 can be supplied, for example, as droplets from an inkjet head to a desired portion of the mold base 12. Further, the resist 31 may be supplied onto the mold substrate 12 by a spin coating method.
Next, the resist 31 is cured, and then the pre-mold 1 is separated to form a resist pattern 32 on the mold substrate 12 (FIGS. 8B, 8C, and 10A). ). The formed resist pattern 32 has an opening 32 a corresponding to the convex pattern 4 having the closed loop structure of the pre-mold 1. Note that FIG. 8B shows a longitudinal section taken along line IV-IV in FIG. 10A, and FIG. 9 below also shows a longitudinal section at the corresponding position. FIG. 8C shows a vertical cross section taken along line VV in FIG. Further, in FIG. 10A, the resist pattern 32 is indicated by hatching. The opening 32a of the resist pattern 32 constitutes a predetermined line / space on the mask layer 13, as shown in FIG. As shown in FIGS. 8C and 10A, a resist pattern thin film is present at the bottom of the opening 32a in a portion of the opening 32a that is off the mask layer 13.

Next, the mask layer 13 is etched using the resist pattern 32 as an etching mask (FIG. 9A), and then the resist pattern 32 is removed to form a fine mask pattern 13 ′ on the mold substrate 12 (FIG. 9). 9 (B), FIG. 10 (B)). The fine mask pattern 13 ′ thus formed does not have a closed loop structure, and has a line / space shape in the illustrated example.
Next, the imprint mold 11 having the fine pattern 14 is manufactured by etching the mold base 12 using the fine mask pattern 13 'as an etching mask (FIGS. 9C and 10C). The fine pattern 14 thus formed has a concavo-convex pattern having a dimension less than the minimum dimension that can be formed by lithography.

  In such an invention, the space defined by the closed loop structure of each convex pattern 4 of the pre-mold 1 and the mask layer 13 are aligned so as not to partially overlap to form a resist pattern 32, Since the fine mask pattern 13 'is formed by etching the mask layer 13 using this as an etching mask, the closed loop structure of the convex pattern 4 that does not overlap with the mask layer 13 does not exist in the fine mask pattern 13'. Therefore, in the present invention, the closed loop structure can be removed simultaneously with the formation of the fine mask pattern 13, and a separate process for removing the closed loop structure is unnecessary. This makes it possible to manufacture an imprint mold having an uneven pattern having a dimension less than the minimum dimension that can be formed by a lithography method without an unnecessary closed loop. Further, when the premold 1 is manufactured using the sidewall process, once the premold is manufactured, it is not necessary to perform the sidewall process thereafter, and the imprint mold can be manufactured by repeatedly using the premold. It is possible to simplify the process and reduce the manufacturing cost.

  In the imprint mold manufacturing method of the present invention, a fine pattern having a dimension less than the minimum dimension that can be patterned by the lithography method and a pattern having a dimension larger than the minimum dimension that can be formed by the lithography method (hereinafter referred to as a large pattern). For example, an imprint mold having a dummy pattern or an alignment mark pattern can be manufactured. In this case, in addition to the mask layer described above, a mold substrate having a large mask pattern for forming a large pattern having a dimension larger than the minimum dimension capable of pattern formation by lithography is used as the mold substrate. To do. FIG. 11 is a plan view showing an example of a mold base material having such a large mask pattern. In FIG. 11, the mold base 12 'includes a mask layer 13 and a large mask pattern 23 on one surface 12'a. The mask layer 13 is a space defined by the closed loop structure in each convex pattern 4 of the pre-mold 1 (in FIG. 11, the convex pattern 4 is indicated by a one-dot chain line, as in the mold base 12 described above, and the closed loop structure And the space defined by (2) is hatched), and has a shape in plan view that does not partially overlap. The large mask pattern 23 is located on the surface 12'a on which the mask layer 13 is located, and when the premold 1 and the mold base 12 'are brought close to each other, the convex pattern 4 of the premold 1 is provided. It is located in a part that doesn't overlap.

Such a large mask pattern 23 can be made of a material having a smaller etching rate than that of the mold base 12 ′ and having etching resistance, and can be formed using the same material as the mask layer 13. Usually, the large mask pattern 23 is formed simultaneously with the formation of the mask layer 13 by the same method as the formation of the mask layer 13.
A method for producing an imprint mold of the present invention using such a mold base 12 'and the above premold 1 will be described with reference to FIGS. In this imprint mold manufacturing method, the resist pattern 32 can be formed in the same process as the example using the pre-mold 1 and the mold base 12 described above. FIG. 12A is a plan view showing a state in which the resist pattern 32 is formed on the mold base 12 ′, and the resist pattern 32 is shown by hatching. FIG. 13 is a longitudinal sectional view taken along the line VI-VI in FIG. As shown in FIG. 12A and FIG. 13, the formed resist pattern 32 has an opening 32 a corresponding to the convex pattern 4 having the closed loop structure of the premold 1. The opening 32a constitutes a predetermined line / space on the mask layer 13, and a thin film of a resist pattern exists at the bottom of the opening 32a at a portion off the mask layer 13. On the other hand, the large mask pattern 23 is covered with a resist pattern 32.

Next, the mask layer 13 is etched using the resist pattern 32 as an etching mask, and then the resist pattern 32 is removed to form a fine mask pattern 13 'on the mold substrate 12' (FIG. 12B). ). The fine mask pattern 13 ′ thus formed does not have a closed loop structure, and has a line / space shape in the illustrated example. In the etching using the resist pattern 32 as an etching mask, the large mask pattern 23 is covered with the resist pattern 32, so that the shape at the time of formation is maintained without being etched.
Next, the mold substrate 12 'is etched using the fine mask pattern 13' and the large mask pattern 23 as an etching mask, thereby producing an imprint mold 11 'having the fine pattern 14 and the large pattern 24 (FIG. 12 (C)). The fine pattern 14 formed in this way has a concavo-convex pattern with a dimension less than the minimum dimension that can be formed by lithography, while the large pattern 24 has a dimension that is greater than or equal to the minimum dimension that can be patterned by lithography. It has dimensions.
In the present invention, a process for removing the closed loop structure is not provided, there is no unnecessary closed loop, and a fine pattern having a dimension less than the minimum dimension that can be patterned by the lithography method, and pattern formation by the lithography method. It is possible to manufacture an imprint mold having a large pattern having a dimension larger than the minimum possible dimension with a high yield.

[Other Embodiments]
In the above-described embodiment, the pre-mold 1 is provided with a plurality of convex patterns 4 having the same shape and dimensions, but the pre-mold used in the present invention has a width of the convex portion of the convex pattern provided. The dimension may be less than the minimum dimension that can be patterned by the lithography method, and the dimension of the plan view shape of the space defined by the closed loop structure of the convex pattern must be less than the minimum dimension that can be patterned by the lithography method. It can be set appropriately. Therefore, the pre-mold may include a plurality of types of convex patterns having different shapes. Correspondingly, the plan view shape of the mask layer provided in the mold base material can also be set as appropriate. Below, the manufacturing method of the imprint mold at the time of using the premold of the other aspect different from the above-mentioned premold 1 and the base materials 12 and 12 'for molds, and the base material for molds is demonstrated.

FIG. 14 is a plan view for explaining a method for producing an imprint mold of the present invention when a pre-mold and a mold base material according to another embodiment are used.
As shown in FIG. 14A, the pre-mold 101 includes a plurality of concave and convex patterns having a closed-loop structure that are less than a minimum dimension that can be patterned by a lithography method on one surface 102a of the substrate 102. A convex pattern 104 is provided. The convex pattern 104 has three types of convex patterns 104a, 104b, and 104c having different shapes in plan view of the space defined by the closed loop structure. These convex patterns 104a, 104b, and 104c have dimensions such that the width of the convex portions is less than the minimum dimension that can be formed by lithography.
As shown in FIG. 14B, the mold base 112 includes a mask layer 113 on one surface 112a. The mask layer 113 is a space defined by the closed loop structure in each convex pattern 104 of the pre-mold 101 (in FIG. 14B, the convex pattern 104 is indicated by a one-dot chain line, and is a space defined by the closed loop structure. And has a plan view shape that does not partially overlap. In this example, both end portions of the space defined by the closed loop structure of each convex pattern 104 are set so as not to overlap the mask layer 113.

  The imprint mold manufacturing method of the present invention using such a premold 101 and a mold substrate 112 can be performed in the same manner as in the example using the premold 1 and the mold substrate 12 described above. In the imprint mold manufacturing method using the pre-mold 101 and the mold substrate 112, the fine mask pattern 113 ′ formed by etching the mask layer 113 using the formed resist pattern as an etching mask is shown in FIG. As shown in (), it becomes a fine pattern with different dimensions. Then, by etching the mold substrate 112 using the fine mask pattern 113 'as an etching mask, an imprint mold having a fine uneven pattern having different dimensions and having no unnecessary closed loops can be manufactured. it can.

FIG. 15 is a plan view for explaining a method for producing an imprint mold of the present invention when a pre-mold and a mold base material according to another embodiment are used.
As shown in FIG. 15A, the pre-mold 201 has a plurality of concave and convex patterns having a closed-loop structure with a dimension less than the minimum dimension that can be patterned by a lithography method on one surface 202a of the base material 202. Convex pattern 204 is provided. The convex pattern 204 has three types of convex patterns 204a, 204b, and 204c having different shapes in plan view of the space defined by the closed loop structure. These convex patterns 204a, 204b, and 204c have dimensions such that the width of the convex portions is less than the minimum dimension that can be patterned by a lithography method.

  As shown in FIG. 15B, the mold base 212 includes a mask layer 213 and a large mask pattern 223 on one surface 212a. That is, the mold substrate 212 is an example of a mold substrate for manufacturing an imprint mold having a large pattern together with a fine pattern. In the mold base 212, the mask layer 213 is a space defined by the closed loop structure in each convex pattern 204 of the pre-mold 201 (in FIG. 15B, the convex pattern 204 is indicated by a one-dot chain line, The space defined by the closed loop structure is indicated by hatching), and has a plan view shape that does not partially overlap. Further, the large mask pattern 223 is located on the surface 212a where the mask layer 213 is located, and does not overlap the convex pattern 204 of the premold 201 when the premold 201 and the mold base 212 are brought close to each other. Located in the site.

The imprint mold manufacturing method of the present invention using such a premold 201 and a mold base 212 can be performed in the same manner as in the example using the premold 1 and the mold base 12 ′ described above. . In the imprint mold manufacturing method using the pre-mold 201 and the mold base 212, the fine mask pattern 213 ′ formed by etching the mask layer 213 using the formed resist pattern as an etching mask is shown in FIG. As shown in (), it becomes a fine pattern with different dimensions. In addition, the large mask pattern 223 is maintained in its formed shape without being etched.
Next, the mold base material 212 is etched using the fine mask pattern 213 ′ and the large mask pattern 223 as an etching mask, so that an unnecessary closed loop does not exist and a fine uneven pattern and a large pattern having different dimensions are provided. The imprint mold can be manufactured with a high yield.

FIG. 16: is a top view for demonstrating the manufacturing method of the imprint mold of this invention at the time of using the premold of another aspect, and the base material for molds.
As shown in FIG. 16 (A), the pre-mold 301 has a plurality of concave and convex patterns having a closed loop structure on a surface 302a of a base material 302 having a dimension less than the minimum dimension that can be patterned by a lithography method. A convex pattern 304 is provided. This convex pattern 304 has two types of convex patterns 304a and 304b having different planar shapes of the space defined by the closed loop structure, and adjacent convex patterns 304a have desired dimensions along the longitudinal direction. It is in a state shifted by. These convex patterns 304a and 304b have dimensions that are less than the minimum dimension at which the width of the convex portions can be formed by lithography.
As shown in FIG. 16B, the mold base 312 includes a mask layer 313 and a large mask pattern 323 on one surface 312a.
This mold base material 312 is an example of a mold base material for manufacturing an imprint mold having a large pattern together with a fine pattern, and the large pattern is an example of developing a predetermined function in cooperation with the fine pattern. . In the mold substrate 312, the mask layer 313 is a space defined by the closed loop structure in each convex pattern 304 of the pre-mold 301 (in FIG. 16B, the convex pattern 304 is indicated by a one-dot chain line, The space defined by the structure is indicated by hatching) and has a planar view shape that does not partially overlap. In the illustrated example, the convex pattern 304a is set so that one end of the space defined by the closed loop structure does not overlap the mask layer 313. The large mask pattern 323 is continuous with the mask layer 313 via the connection portion 315, is located on the surface 312a where the mask layer 313 is located, and the premold 301 and the mold base material 312 are close to each other. It is located in the site | part which does not overlap with the convex pattern 304 of the premold 301 when it is made to do. Note that the connection portion 315 is formed simultaneously with the formation of the mask layer 313 and the large mask pattern 323.

The imprint mold manufacturing method of the present invention using such a premold 301 and the mold base material 312 can be performed in the same manner as the example using the premold 1 and the mold base material 12 'described above. . In the imprint mold manufacturing method using the pre-mold 301 and the mold base material 312, the fine mask pattern 313 ′ formed by etching the mask layer 313 using the formed resist pattern as an etching mask is shown in FIG. ), A pattern 313′a that is continuous when bent is formed, and a striped pattern 313′b that is positioned between the bent pattern 313′a. In addition, the connection portion 315 and the large mask pattern 323 are maintained in their formed shapes without being etched, and the large mask pattern 323 is continuous with the pattern 313 ′ via the connection portion 315.
Next, the mold base material 312 is etched using the fine mask pattern 313 ′, the connection portion 315 and the large mask pattern 323 as an etching mask, so that there is no unnecessary closed loop and a fine uneven pattern and large pattern are formed. The provided imprint mold can be manufactured with a high yield.

FIG. 17: is a top view for demonstrating the manufacturing method of the imprint mold of this invention at the time of using the premold of another aspect and the base material for molds.
As shown in FIG. 17A, the pre-mold 401 includes a plurality of concave and convex patterns having a closed loop structure on a surface 402a of a base material 402 that are less than a minimum dimension that can be patterned by a lithography method. A convex pattern 404 is provided. The convex pattern 404 has a desired shape in which the planar shape of the space defined by the closed loop structure has a dimension that is equal to or larger than the minimum dimension that can be formed by lithography, while the convex portion of the convex pattern 404 The width is a dimension less than the minimum dimension that can be patterned by a lithography method.
As shown in FIG. 17B, the mold base 412 includes a square annular mask layer 413 on one surface 412a. The mask layer 413 is a space defined by the closed loop structure in the convex pattern 404 of the pre-mold 401 (in FIG. 17B, the convex pattern 404 is indicated by a one-dot chain line, and is defined in the space defined by the closed loop structure. It has a plan view shape that does not partially overlap with a slanted line).

The imprint mold manufacturing method of the present invention using such a pre-mold 401 and the mold base 412 can be performed in the same manner as the example using the pre-mold 1 and the mold base 12 described above. In the imprint mold manufacturing method using the pre-mold 401 and the mold base 412, the fine mask pattern 413 ′ formed by etching the mask layer 413 using the formed resist pattern as an etching mask is shown in FIG. As shown in FIG. 5B, a part of the rectangular mask layer 413 is cut into a fine width. Then, by etching the mold substrate 412 using the fine mask pattern 413 ′ as an etching mask, an imprint mold having no unnecessary closed loop and having a fine uneven pattern can be manufactured.
Here, the manufacturing example of the pre-mold described with reference to FIGS. 3 to 5 will be further described using the pre-mold 201 including the convex pattern 204 shown in FIG. 15A as an example.

FIG. 18 is a perspective view showing a state after the etch back shown in FIGS. 3D and 4D (a state in which the side wall pattern 7 is formed only on the side wall of the remaining core material pattern 5 ′). is there. In FIG. 18A, the side wall pattern 7 is positioned so as to surround the side wall of the core material pattern 5 ′ having a desired fine shape. In FIG. 18B, the sidewall pattern 7 is located on the sidewall of the opening 5′a of the core material pattern 5 ′ having the opening 5′a formed in a desired fine shape. In the embodiment as shown in FIG. 18 (A), for example, a site where the core material pattern 5 (see FIGS. 3 (A) and 4 (A)) is formed using a negative electron beam sensitive resist. It can be carried out by drawing with an electron beam and developing, and then performing a slimming process to form the core material pattern 5 '. On the other hand, in the mode as shown in FIG. 18B, for example, a positive electron beam sensitive resist is used to draw a portion where an opening is to be formed (when slimming treatment is performed, after slimming treatment) And development is performed to form a core material pattern 5 'having an opening 5'a.
The above-described embodiments of the present invention are exemplifications, and the imprint mold manufacturing method of the present invention is not limited to these embodiments.

Next, the present invention will be described in more detail with specific examples.
<Pre-mold preparation>
A synthetic quartz glass substrate having an outer shape of 6 inches square and a thickness of 0.25 inches was prepared as a premold substrate. A chromium film having a thickness of 5 nm was formed as a mask layer by forming a film of chromium on one surface of the premold base material by a sputtering method.
Next, an electron beam sensitive resist is applied onto the chromium layer by a spin coating method, and the resist layer is drawn with an electron beam and developed, whereby 1000 core material patterns (thicknesses) are formed on the plane of the mesa structure. 50 nm). The core material pattern had a line and space shape with a pattern width of 30 nm, a half pitch of 30 nm, and a line length of 3000 μm (see FIG. 3A).
Next, the core material pattern was slimmed by dry etching with oxygen plasma, and the pattern width of each core material pattern was set to 15 nm, and the thickness of each core material pattern was set to 43 nm (see FIG. 3B).
A silicon oxide film (thickness: 15 nm) was formed as a sidewall material film on the chromium layer by the ALD method so as to cover the slimmed core material pattern (see FIG. 4C).
Next, the entire surface of the silicon oxide sidewall material film was etched back by dry etching using CF ₄ gas to expose the upper surface of the core material pattern and the chromium layer. Thus, the sidewall pattern was formed by leaving the sidewall material film of silicon oxide only on the sidewall of the core material pattern (see FIG. 4D).

Next, the core material pattern was selectively removed by plasma ashing using an oxygen-containing gas so that a side wall pattern of silicon oxide was present on the chromium layer (see FIG. 5A). The formed side wall pattern had a line and space shape with a width of 15 nm, a height of 15 nm, and a half pitch of 15 nm, and a closed loop structure was present at the end of the pattern.
Next, using the sidewall pattern as an etching mask, the chromium layer was dry etched (etching gas: Cl ₂ + O ₂ ), and then the sidewall pattern was removed to form a mask pattern (see FIG. 5B). Thereafter, the premold substrate was dry-etched using CF ₄ gas using the mask pattern as an etching mask. As a result, a line-shaped pattern having a width of 15 nm and a height of 35 nm is arranged in a line & space shape with a half pitch of 15 nm, and two adjacent line-shaped patterns are connected as one unit, and both end portions are connected to each other without end. Thus, a pre-mold having a plurality of convex patterns having a closed loop structure was produced (see FIG. 1).

<Preparation of mold substrate>
On the other hand, a synthetic quartz glass substrate having an outer shape of 6 inches square and a thickness of 0.25 inches was prepared as a mold substrate. This mold base material had a mesa structure with a convex structure part having a shape of 26 mm × 23 mm and a height of 30 μm at the center. A chromium layer having a thickness of 5 nm was formed by forming a film of chromium on the surface having the mesa structure of the mold base by a sputtering method. Next, a photocurable resist is supplied as droplets from the inkjet head onto the chromium layer located in the convex structure, and a mold having a desired uneven structure is brought close to the photocurable resist between the chromium layer and the mold. In this state, the photo-curable resist is cured by irradiating light, and then a resist pattern is formed by separating the mold, and the chromium layer is dry-etched using this resist pattern as an etching mask (etching gas: Cl ₂ + O ₂ ). Thus, a rectangular mask layer (70 μm × 2900 μm) and a large mask pattern (3 μm × 3 μm) positioned so as to be 10 μm apart from the side of the mask layer having a length of 70 μm were formed. The formed mask layer has a plan view shape such that both ends in the longitudinal direction of the space (width 15 nm, length about 3000 μm) defined by the closed loop structure in each convex pattern of the pre-mold do not overlap. did. Moreover, the large mask pattern shall exist in the position which does not overlap with each convex pattern of said premold (refer FIG. 11).

<Production of imprint mold>
A photocurable resist is supplied as droplets from the inkjet head to the mask layer forming surface side of the mold substrate on which the mask layer is formed as described above, and is defined by the closed loop structure of each convex pattern of the premold. Positioning was performed so that both end portions of the space to be overlapped with the mask layer, the premold and the mold base were brought close to each other, and a photocurable resist was developed.
Next, light irradiation was performed from the premold side to cure the photocurable resist, and then the premold was separated to form a resist pattern (see FIG. 12A).
Next, the mask layer was dry etched (etching gas: Cl ₂ + O ₂ ) using the resist pattern as an etching mask, and the resist pattern was removed to form a fine mask pattern. As a result, the formed fine mask pattern and the large mask pattern were present on the mold substrate (see FIG. 12B). Thereafter, the mold substrate was dry-etched using CF ₄ gas using the fine mask pattern and large mask pattern as an etching mask. As a result, an imprint mold having a fine pattern with a line & space shape with a half pitch of 15 nm and a large pattern of 3 μm × 3 μm was obtained.

  The present invention can be applied to various manufacturing fields that require pattern formation with a dimension less than the minimum dimension that can be patterned by a lithography method, and various manufacturing fields that process a workpiece using the formed pattern structure.

1, 101, 201, 301, 401 ... Pre-mold 4, 104, 204, 304, 404 ... Convex pattern 12, 112, 212, 312, 412 ... Mold substrate 13, 113, 213, 313, 413 ... Mask Layers 13 ', 113', 213 ', 313', 413 '... fine mask pattern 23, 223, 323 ... large mask pattern 32 ... resist pattern 5, 5' ... core material pattern 6 ... sidewall material film 7 ... sidewall pattern

Claims (5)

In a method for producing an imprint mold having a fine pattern having a concavo-convex pattern having a dimension less than the minimum dimension that can be patterned by a lithography method,
A pre-mold having at least one convex pattern having a closed-loop structure, which is a concavo-convex pattern having a dimension less than the minimum dimension, and does not partially overlap a space defined by the closed-loop structure in the convex pattern of the pre-mold A step of preparing a mold base material provided with a mask layer having a planar view shape on one surface;
The premold and the mold base material are aligned so as to be close to each other so that the space defined by the closed loop structure of the convex pattern of the premold and the mask layer do not overlap, and the premold And developing the resist supplied between the mold base and curing the resist, separating the pre-mold and forming a resist pattern;
Etching the mask layer using the resist pattern as an etching mask to form a fine mask pattern;
And a step of forming the fine pattern by etching the base material for mold using the fine mask pattern as an etching mask.   A large mask pattern for forming a large pattern having a dimension equal to or larger than the minimum dimension on the mold substrate is the same surface as the surface on which the mask layer is located, and the premold and the mold base In the step of forming the substrate so as not to overlap the convex pattern of the pre-mold when the material is brought close to the substrate, and etching the mold substrate, the fine mask pattern and the large mask pattern are etched masks. The method for producing an imprint mold according to claim 1, wherein the mold substrate is etched to form the fine pattern and the large pattern. A core material pattern is formed on the mask layer located on one surface of the premold substrate,
Forming a sidewall material film so as to cover at least the core material pattern;
Etching is performed on the sidewall material film and the core material pattern, and a sidewall pattern made of the sidewall material film is formed on the sidewall of the remaining core material pattern,
Removing the core pattern,
Etching the mask layer using the sidewall pattern as an etching mask to form a mask pattern;
The imprint mold manufacturing method according to claim 1, wherein the premold is manufactured by etching the base material for premold using the mask pattern as an etching mask.   The method for producing an imprint mold according to claim 3, wherein the core material pattern is formed using an electron beam sensitive resist or a photosensitive resist.   The imprint mold manufacturing method according to claim 3, wherein a slimming process for reducing the core material pattern to a desired dimension is performed on the core material pattern.

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