Pattern formation method, and method of manufacturing article

Abstract

To provide a technique advantageous in reducing restrictions when obtaining a desired inversion pattern.SOLUTION: A pattern formation method includes: a first inversion layer formation step of depositing a first inversion layer on an uneven pattern of a curable composition; a second inversion layer formation step of depositing a flattened inversion layer as a second inversion layer on the first inversion layer; a first etching step of exposing a top face of a projection of the uneven pattern by etching upper layer parts of inversion layers including the first inversion layer and the flattened inversion layer; and a second etching step of etching a pattern of the curable composition exposed with the inversion layer, which is left in a recess of the uneven pattern, as a mask. In the first etching step, the first inversion layer and the flattened inversion layer are etched using a mixture gas mixing a plurality of etching gases.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pattern forming method and a method for manufacturing an article. [Background technology]

[0002] As demand for miniaturization of semiconductor devices and MEMS increases, in addition to conventional photolithography technology, imprint technology, which forms an imprint material on a substrate using a mold and then forms a pattern of the imprint material on the substrate, is attracting attention.

[0003] The imprinting technique involves contacting a mold with an imprint material applied to a substrate to form a concave-convex pattern. The pattern obtained using this imprinting technique is used as a mask to process the substrate, and a process called the inversion process can be applied.

[0004] Patent Document 1 discloses the following inversion process steps: First, an inversion layer is formed on the concave-convex pattern (inversion layer formation step), and the concave portions are filled with an inversion layer material. At this time, the inversion layer material is also deposited on the tops of the convex portions of the concave-convex pattern, forming an excess inversion layer. Therefore, the excess inversion layer is removed (excess inversion layer removal step) so as to expose the top surfaces of the convex portions of the concave-convex pattern of the cured film of the curable composition, thereby exposing the inversion layer filled in the concave portions. Then, using the exposed inversion layer as a mask, the remaining film of the concave-convex pattern (remaining film etching step) and the underlying processed layer are etched to form an inversion pattern (processed layer processing step).

[0005] In such an inversion process, it is desirable that the inversion layer be smooth. Patent Document 2 proposes a method for smoothing the inversion layer by forming it using an inkjet method, and a method for further smoothing the inversion layer by pressing it with a flat mold, in order to obtain the desired smoothness of the inversion layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-162862 [Patent Document 2] Japanese Patent Application Publication No. 2018-98470 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the method described in Patent Document 2 imposes limitations on the material's physical properties due to compatibility with inkjet printing and smoothing by pressing with a smooth mold. Prioritizing these limitations could result in insufficient etching resistance for the inversion layer to function as a mask during the process of using the inversion layer as a mask to remove the remaining film of the uneven pattern (residual film etching process). Furthermore, similar problems could arise during the process of etching the underlying workpiece layer to form the inversion pattern (workpiece layer processing process). Therefore, the method described in Patent Document 2 requires the selection of a material that combines material properties suitable for inkjet printing and flat mold pressing with material properties that provide etching resistance, potentially limiting the flexibility in selecting usable materials. Furthermore, the limited flexibility required for developing new materials can lead to high development difficulties and cost issues.

[0008] The present invention has been made in view of the above problems of the conventional techniques, and has an exemplary object to provide a technique that is advantageous in terms of reducing the constraints imposed when obtaining a desired inverted pattern. [Means for solving the problem]

[0009] In order to achieve the above object, one embodiment of the present invention includes a first inversion layer forming step of forming a first inversion layer on a concave-convex pattern of a curable composition, a second inversion layer forming step of forming a planarizing inversion layer as a second inversion layer on the first inversion layer, a first etching step of etching the first inversion layer and an upper layer portion of the inversion layer including the planarizing inversion layer to expose top surfaces of convex portions of the concave-convex pattern, and a second etching step of etching the exposed pattern of the curable composition using the inversion layer remaining in the concave portions of the concave-convex pattern as a mask, The first etching step is characterized in that the first inversion layer and the planarizing inversion layer are etched using a mixed gas containing a plurality of etching gases. [Effects of the Invention]

[0010] According to the present invention, for example, it is possible to provide a technique that is advantageous in that it reduces the constraints imposed when obtaining a desired inverted pattern. [Brief explanation of the drawings]

[0011] [Figure 1] 5A to 5C are schematic diagrams illustrating a flow of a reversal process according to the first embodiment. [Figure 2] 5A to 5C are schematic diagrams illustrating a flow of a reversal process according to the first embodiment. [Figure 3] FIG. 4 is a diagram showing an example of an etching rate relative to a mixture ratio of an etching gas in the first embodiment. [Figure 4] 10 is a flowchart illustrating an inversion layer forming step according to the second embodiment. [Figure 5] 1A-1C are schematic diagrams illustrating known inversion process steps. [Figure 6] 10A and 10B are schematic diagrams illustrating possible problems that may occur in the reversal process. [Figure 7] 10 is a flowchart illustrating a placement process. [Figure 8] 1A and 1B are schematic diagrams illustrating a photo-nanoimprint method. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] <Inversion process> FIG. 5 is a schematic diagram illustrating a known inversion process. The inversion process will be described using this diagram. FIG. 5(A) is a schematic diagram illustrating an initial cured film formation process. In the inversion process, as shown in FIG. 5(A), a concave-convex pattern 2 is formed on a substrate 1 using a curable composition, including protrusions 12 and recesses 13. In other words, the initial cured film formation process can be considered a concave-convex pattern formation process. Hereinafter, the film formed here will be referred to as a cured film 11. Also, as shown in FIG. 5(A), the portion of the cured film 11 below the concave-convex pattern 2 (base portion) will be referred to as a residual film 3. This residual film 3 is unnecessary for the etching process after pattern formation and must be removed in a later process. Methods for forming the cured film 11 having the concave-convex pattern 2 on a substrate 1 in the initial cured film formation process include, for example, photo-nanoimprinting and photolithography. In this embodiment, the concave-convex pattern 2 is formed by photo-nanoimprinting, but the method is not limited to this. The photo-nanoimprinting method will be described in detail later.

[0014] The substrate 1 may be, for example, a silicon wafer. The substrate 1 may have a separate workable layer on its surface, and another layer may be formed below the workable layer. In addition to a silicon wafer, the substrate 1 may be selected from any substrate known as a substrate for semiconductor devices, such as aluminum, titanium-tungsten alloy, aluminum-silicon alloy, aluminum-copper-silicon alloy, silicon oxide, or silicon nitride. The outermost workable layer of the substrate 1 may be subjected to a surface treatment such as silane coupling treatment, silazane treatment, or formation of an organic thin film to improve adhesion to the curable composition.

[0015] In this embodiment, the curable composition contains at least a polymerizable compound and a polymerization initiator. It may further contain a non-polymerizable compound or a solvent, if necessary. The non-polymerizable compound is at least one selected from the group consisting of sensitizers, hydrogen donors, internal mold release agents, surfactants, antioxidants, and polymer components. In this embodiment, a certain workpiece layer is present on a substrate. In the initial cured film formation process, the processes from the placement process to the release process (described later) are performed on the workpiece layer of the substrate 1 using a curable composition (a) containing 1 wt. % or less of inorganic elements, preferably containing no inorganic elements such as silicon atoms. This allows a cured film 11 having a pattern including protrusions 12 and recesses 13 to be formed on the substrate 1. Examples of the curable composition (a) that can be used include, but are not limited to, those described in JP 2016-162862 A.

[0016] FIG. 5(B) is a schematic diagram showing the inversion layer formation step. The inversion layer formation step is performed following the initial cured film formation step. In the inversion layer formation step, an inversion layer 4 is formed on the cured film 11 having the formed concave-convex pattern 2. The inversion layer 4 is used as a mask for etching the cured film 11 in the remaining film etching step described below, so it is required to have a sufficient etching selectivity with the curable composition that forms the cured film 11. At this time, as shown in the figure, the inversion layer 4 in the upper layer of the cured film 11, located on the convex portions 12, is called the excess inversion layer 5.

[0017] FIG. 5(C) is a schematic diagram showing the excess inversion layer removal step. The excess inversion layer removal step is performed following the inversion layer formation step. In the excess inversion layer removal step, the excess inversion layer 5 is removed. Specifically, the inversion layer 4 (excess inversion layer 5) is removed until the upper portions (top surfaces 12a) of the convex portions 12 of the cured film 11 having the concave-convex pattern 2 are exposed. FIG. 5(C) shows the state after the inversion layer 4 (excess inversion layer 5) has been removed and the top surfaces 12a of the convex portions 12 are exposed.

[0018] FIG. 5(D) is a schematic diagram showing the remaining film etching step. The remaining film etching step is performed after the excess inversion layer removal step. In the remaining film etching step, the remaining film 3 of the cured film 11 is removed. In the remaining film etching step, the inversion layer 4 remaining in the recesses 13 of the uneven pattern 2 in the excess inversion layer removal step is used as a processing mask. Using this processing mask, etching is performed starting from the protrusions 12 of the uneven pattern 2 exposed by removing the inversion layer 4 in the excess inversion layer removal step. Etching continues until the surface 1a of the workpiece layer of the substrate 1 is exposed. This step forms a pattern (hereinafter referred to as an inversion pattern 14) on the workpiece layer that is the inverse of the uneven pattern 2 of the curable composition. FIG. 5(D) shows the state in which the remaining film 3 has been etched and the inversion pattern 14 has been formed on the workpiece layer.

[0019] FIG. 5(E) is a schematic diagram showing the process of processing the layer to be processed. The process of processing the layer to be processed is performed after the remaining film etching process. In the process of processing the layer to be processed, a reverse pattern is transferred to the layer to be processed on the substrate 1. In the process of processing the layer to be processed, the reverse pattern 14 formed in the remaining film etching process is used as a processing mask to etch the layer to be processed on the substrate 1, thereby obtaining (forming) the layer to be processed 6 having a pattern shape. FIG. 5(E) shows the state in which the layer to be processed 6 has been formed.

[0020] 5(F) is a schematic diagram showing the reverse pattern removal step. The reverse pattern removal step is the final step of the reversal process, which is performed after the process layer processing step. In the reverse pattern removal step, the reverse pattern 14, which is the processing mask, is removed after the process layer of the substrate 1 is processed.

[0021] As mentioned above, in the inversion process, depending on the uneven shape of the uneven pattern 2 of the cured film 11 and the conditions for forming the inversion layer 4, it may not be possible to form the desired inversion pattern. This problem will be explained using FIG. 6. FIG. 6 is a schematic diagram illustrating a problem that may occur in the inversion process. FIG. 6(A) is a schematic diagram showing the inversion layer formation step S200. When the uneven shape of the uneven pattern 2 is large, the inversion layer 4 may not be formed uniformly as shown in FIG. 6(A), and the film thickness of the inversion layer 4 formed on the convex portions 12 of the uneven pattern 2 may be too thick compared to the film thickness of the inversion layer 4 formed on the concave portions 13.

[0022] FIG. 6(B) is a schematic diagram showing the excess inversion layer removal step 201. The excess inversion layer removal step 201 is performed following the inversion layer formation step S200. If the next step, the excess inversion layer removal step 201, is performed in the state shown in FIG. 6(A), the cured film 11 on the bottom surface 13a of the recessed portion 13 may be exposed first before the excess inversion layer 5 is completely removed to expose the top surface 12a of the protrusion 12. If an attempt is made to further remove the excess inversion layer 5 from this point to expose the top surface 12a of the protrusion 12 of the cured film 11, the cured film 11 made of the curable composition in the recessed portion 13 may be damaged, as shown in the excess inversion layer removal step 202 in FIG. 6(C).

[0023] 6(D), the inversion layer 4 acting as a mask in the recesses 13 is absent, and the curable composition (cured film 11) does not remain in the desired locations 7, making it impossible to form the desired inversion pattern. To prevent this from happening, it is desirable to form the inversion layer 4 on the cured film 11 in a smoothed state.

[0024] <Initial cured film formation process> Next, the photo-nanoimprinting method used in the initial cured film formation step in this embodiment will be described. The photo-nanoimprinting method forms an initial cured film having a desired shape on a substrate through four broadly divided steps. Specifically, first, a curable composition is applied (supplied) to a pattern formation region on the substrate (placement step). Next, the curable composition is molded using a mold on which a pattern has been formed (mold contact step). Then, the curable composition is cured by irradiating it with light (light irradiation step). After that, the mold is separated (mold release step).

[0025] The disposing step will now be described in detail. FIG. 7 is a flowchart illustrating the disposing step. Methods for applying the curable composition in the disposing step include spin coating and inkjet printing. In this embodiment, inkjet printing is used as an example. In this embodiment, during this application, the droplet pattern to be applied to the substrate is distributed to match the volume of the fine concave-convex pattern on the surface of the mold that will be contacted in the next mold contact step. Therefore, in S111, concave-convex pattern information for the mold 9 is acquired. Then, in S112, a processing unit of a processing device (semiconductor manufacturing device, imprinting device) (not shown) determines the droplet pattern. Specifically, in S112, using the concave-convex pattern information for the mold 9 acquired in S111, the droplet pattern is determined so that a volume of curable composition equal to the volume of the concave-convex pattern 2 plus the volume of one-third of the remaining film is supplied to each pattern position of the mold. This is desirable because it ensures that the thickness of the remaining film of the formed initial cured film is consistent within the mold. Then, in S113, using the droplet pattern determined in S112, droplets of the initial cured film are supplied onto the substrate 1. Note that the droplet pattern is information indicating the arrangement (disposition) of droplets of the curable composition to be placed on the substrate 1, and may include information such as the volume of the droplets and shape parameters of the droplets.

[0026] The processing unit may be configured by a computer having a processor such as a CPU (Central Processing Unit) and a storage unit such as a memory. The processing unit comprehensively controls each unit of the processing device in accordance with various programs stored in the storage unit, and performs the initial hardened film formation step.

[0027] Here, the droplet pattern is simply determined from the combined volume of the concave-convex pattern of the mold and the volume of the remaining film, but this is not limited to this, and the droplet pattern may be determined taking into account the shape of the concave-convex pattern of the mold 9 or the position, such as the outside of the center, within the mold.

[0028] 8A and 8B are schematic diagrams illustrating the photo-nanoimprinting method. Fig. 8A is a schematic diagram illustrating the disposing step. In the disposing step, droplets of the curable composition 8 are disposed (supplied) on the substrate 1, as described above.

[0029] FIG. 8(B) is a schematic diagram showing the mold contacting step. In the mold contacting step, the curable composition 8 and the mold 9 are brought into contact with each other. The contacting step includes a step of changing a state in which the curable composition 8 and the mold 9 are not in contact with each other (not shown) to a state in which they are in contact with each other, and a step of maintaining the state in which they are in contact with each other. FIG. 8(B) shows the state in which the curable composition 8 and the mold 9 are in contact with each other. By maintaining the state in which the curable composition 8 and the mold 9 are in contact with each other, the liquid of the curable composition fills the recesses of the fine pattern on the surface of the mold 9, and this liquid becomes a liquid film that fills the fine pattern of the mold 9.

[0030] A mold made of a light-transmitting material is used as the mold 9. Specific examples of materials for the mold 9 include glass, quartz, optically transparent resins such as PMMA and polycarbonate resin, transparent metal vapor deposition films, flexible films such as polydimethylsiloxane, photocurable films, and metal films. However, when an optically transparent resin is used as the material for the mold 9, a resin that is insoluble in the components contained in the curable composition is selected. Quartz is a desirable material for the mold because it has a low thermal expansion coefficient and small pattern distortion. The pattern formed on the surface of the mold 9 has a height of, for example, 4 nm to 200 nm. The lower the height of the pattern of the mold 9 (the height of the convex portions), the smaller the force required to separate the mold 9 from the cured film of the curable composition in the demolding step, i.e., the demolding force, and the fewer demolding defects remaining on the mold 9 due to the pattern of the curable composition being torn off. Furthermore, the impact caused by the demolding of the mold 9 can elastically deform the pattern of the curable composition, causing adjacent pattern elements to come into contact with each other, resulting in adhesion or breakage. To avoid these problems, it is advantageous for the height of the pattern element to be approximately twice or less its width (aspect ratio of 2 or less). On the other hand, if the height of the pattern element is too low, the processing accuracy of the substrate will decrease.

[0031] The mold 9 may be subjected to a surface treatment before the contact step in order to improve the releasability of the mold 9 from the curable composition. Examples of surface treatments include applying a release agent to the surface of the mold 9 to form a release agent layer. Examples of release agents that can be applied to the surface of the mold 9 include silicone-based release agents, fluorine-based release agents, hydrocarbon-based release agents, polyethylene-based release agents, polypropylene-based release agents, paraffin-based release agents, montan-based release agents, and carnauba-based release agents. Commercially available coating release agents, such as Optool (registered trademark) DSX manufactured by Daikin Industries, Ltd., can also be suitably used. One type of release agent may be used alone, or two or more types may be used in combination. Of the above-mentioned release agents, fluorine-based and hydrocarbon-based release agents are particularly preferred.

[0032] In the contacting step, the pressure applied to the curable composition 8 when the mold 9 is brought into contact with the curable composition 8 is not particularly limited and may be, for example, 0 MPa to 100 MPa. The pressure applied to the curable composition 8 when the mold 9 is brought into contact with the curable composition 8 is preferably 0 MPa to 50 MPa, more preferably 0 MPa to 30 MPa, and even more preferably 0 MPa to 20 MPa. The contacting step can be performed under any of the following conditions: air, reduced pressure, or inert gas; however, a reduced pressure or inert gas atmosphere is preferred to prevent the curing reaction from being affected by oxygen or moisture. Specific examples of inert gases used when the contacting step is performed under an inert gas atmosphere include nitrogen, carbon dioxide, helium, argon, various chlorofluorocarbon gases, and mixtures thereof. When the contacting step is performed under a specific gas atmosphere, including air, the preferred pressure is 0.0001 atmospheres to 10 atmospheres.

[0033] 8(C) is a schematic diagram showing the curing step. In the curing step, the curable composition 8 is irradiated with irradiation light 10 as curing energy, thereby curing the curable composition 8 and forming a cured film 11. In the curing step, for example, the curable composition 8 is irradiated with irradiation light 10 through a mold 9. More specifically, the curable composition 8 filled in the fine pattern of the mold 9 is irradiated with irradiation light 10 through the mold 9. As a result, the curable composition 8 filled in the fine pattern of the mold 9 is cured to form a cured film 11 having the pattern.

[0034] The irradiation light 10 is selected depending on the wavelength to which the curable composition 8 is sensitive. Specifically, the irradiation light 10 is appropriately selected from ultraviolet light having a wavelength of 150 nm or more and 400 nm or less, X-rays, electron beams, etc. It is particularly preferable that the irradiation light 10 is ultraviolet light. This is because many of the commercially available curing aids (photopolymerization initiators) are compounds that are sensitive to ultraviolet light.

[0035] Examples of light sources that emit ultraviolet light include high-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, deep-UV lamps, carbon arc lamps, chemical lamps, metal halide lamps, xenon lamps, KrF excimer lasers, ArF excimer lasers, and F2 lasers. However, ultra-high-pressure mercury lamps are particularly preferred as light sources that emit ultraviolet light. The number of light sources may be one or more.

[0036] Furthermore, the entire area of ​​the curable composition 8 filled in the fine pattern of the mold 9 may be irradiated with light, or only a partial area (a limited area) may be irradiated with light. Furthermore, light irradiation may be performed intermittently multiple times over the entire area of ​​the substrate 1, or may be performed continuously over the entire area of ​​the substrate 1. Furthermore, light may be irradiated over a first area of ​​the substrate 1 in a first irradiation process, and light may be irradiated over a second area of ​​the substrate different from the first area in a second irradiation process.

[0037] FIG. 8(D) is a schematic diagram showing the demolding step. In the demolding step, the mold 9 is separated from the cured film 11, which is the cured curable composition 8. By separating the patterned cured film 11 from the mold 9, a free-standing cured film 11 having a pattern that is an inverse of the fine pattern of the mold 9 is obtained. The method for separating the mold 9 from the patterned cured film 11 is not particularly limited, as long as a portion of the patterned cured film is not physically damaged during separation. For example, the substrate 1 may be fixed and the mold 9 may be moved away from the substrate 1. Alternatively, the mold 9 may be fixed and the substrate 1 may be moved away from the mold 9. The mold 9 may be separated from the patterned cured film 11 by moving both the mold 9 and the substrate 1 in opposite directions.

[0038] A series of steps from the above-mentioned placement step to the demolding step, in this order, can provide a cured film 11 having a desired concave-convex pattern shape (a pattern shape that follows the concave-convex shape of the mold) at desired positions. In the initial cured film formation step of this embodiment, the repeating unit (shot) from the placement step to the demolding step is repeated multiple times on the same substrate, thereby providing a cured film having multiple desired patterns at desired positions on the substrate.

[0039] First Embodiment A pattern forming method (pattern processing method) according to the first embodiment will be described in detail below. In this embodiment, the inversion layer has a two-layer structure and is etched at approximately the same rate.

[0040] 1 and 2 are schematic diagrams showing the flow of the reversal process step according to the first embodiment. Fig. 1(A) is a schematic diagram showing the initial hardened film forming step S300 according to the first embodiment. The initial hardened film forming step S300 according to this embodiment is similar to the initial hardened film forming step of the known reversal process step shown above, and therefore a description thereof will be omitted.

[0041] FIG. 1(B) is a schematic diagram showing the inversion layer formation step S301 according to the first embodiment. The inversion layer formation step according to this embodiment forms a two-layer inversion layer, unlike the known inversion layer formation steps described above. Specifically, a first inversion layer 4a is first formed on the cured film 11 having the concave-convex pattern 2 formed in the initial cured film formation step S300. In this embodiment, a material containing 10% by weight or more of an inorganic element is used as the material for the first inversion layer 4a. By containing 10% by weight or more of an inorganic element, a sufficient etching selectivity can be achieved with respect to the cured film 11 having the concave-convex pattern 2.

[0042] The material for the first inversion layer 4a can be selected from silicon-based materials such as SiO2 and SiN, silicon-containing organic materials, metal oxide films such as TiO2 and Al2O3, and general metal materials. For example, a method for forming an inversion layer made of a silicon-containing organic material is spin coating using SOG (Spin On Glass). Also, a method for forming an inversion layer made of SiO2 is plasma CVD deposition using TEOS (Tetra Ethyl Orthosilicate). In this embodiment, the first inversion layer 4a is formed by spin coating with Honeywell T-111.

[0043] Several examples of methods for forming the first inversion layer 4a are given. However, with any method, including this embodiment, if the cured film 11 has large irregularities, it is difficult to form a smooth first inversion layer 4a due to the influence of the irregularities. As a result, the first inversion layer 4a is likely to be formed unevenly, as shown in FIG. 1(B). If the process proceeds to the next step as is, the desired inversion pattern cannot be formed, as described above, which is undesirable.

[0044] In contrast, in this embodiment, the uneven, or in other words, the non-smooth, first inversion layer 4a is smoothed by forming a planarizing inversion layer 4b as a second inversion layer on top of the first inversion layer 4a. That is, the inversion layer 4 in this embodiment includes the first inversion layer 4a and the second inversion layer (planarizing inversion layer 4b).

[0045] 1(C) is a schematic diagram showing the inversion layer formation step S302 according to the first embodiment. In this embodiment, in the inversion layer formation step S302, droplets 16 of a planarization inversion layer material (planarization layer material, second reversal material) are discretely supplied from an inkjet nozzle 15 according to the unevenness of the cured film 11. That is, the droplet pattern is distributed so that the volume of the planarization layer material disposed at locations corresponding to the recesses 13 of the unevenness pattern 2 is greater than the volume of the planarization layer material disposed at locations corresponding to the protrusions 12 of the unevenness pattern 2. By forming the planarization inversion layer 4b by an inkjet method, it is possible to control the supply or application amount of the planarization layer material according to the pattern density of the unevenness pattern 2 of the cured film 11, etc.

[0046] Using the inkjet method, droplets 16 of the planarization layer material are ejected from an inkjet nozzle 15 onto the first inversion layer 4a. The droplets 16 then spread, and on the first inversion layer 4a, the droplets 16 either become closer to each other or merge to form a continuous liquid film. The solvent in the liquid film then evaporates, forming a smoothed film on the cured film 11. This method therefore makes it easy to smooth the inversion layer 4.

[0047] In this embodiment, a photocurable composition (b) that is cured by irradiation with light is used as the planarizing layer material, as shown below. Therefore, after applying the curable composition (b), the curable composition (b) is cured by irradiating it with light of a desired wavelength. The photocurable composition (b) in this embodiment is prepared by blending the components (A) and (B) shown below and filtering the mixture through a 0.2 μm ultra-high molecular weight polyethylene filter. The mole fraction weighted average molecular weight of component (A) is 212.24. (1-1) Component (A): 100 parts by weight in total <a-1>Neopentyl glycol diacrylate (manufactured by Kyoeisha Chemical, trade name: NP-A, molecular weight 212.24): 100 parts by weight (1-2) Component (B): Total 3 parts by weight <b-1>Lucirin (registered trademark) TPO (manufactured by BASF): 3 parts by weight The viscosity of the photocurable composition prepared in this manner was measured at 25°C using a cone-plate rotational viscometer RE-85L (manufactured by Toki Sangyo Co., Ltd.) and found to be 5.33 mPa·s, making it suitable for use in the inkjet method.

[0048] FIG. 1(D) is a schematic diagram illustrating the inversion layer formation step S303 according to the first embodiment. As described above, the curable composition (b) has a viscosity suitable for inkjet printing. Therefore, in the inversion layer formation step S303 according to this embodiment, the inversion layer 4 is formed smoothly by the planarized inversion layer 4b. Although the photocurable composition described above is used in this embodiment, this is not limited thereto; thermosetting compositions and the like can also be used. The material used should preferably be a composition containing at least a polymerizable compound and a polymerization initiator, and may further contain a non-polymerizable compound or a solvent as needed. A viscosity (25°C) of 1 mPa·s to 30 Pa·s is preferred, and a viscosity (25°C) of 1 mPa·s to 20 mPa·s is more preferred. A viscosity (25°C) of less than 1 mPa·s may make it difficult to form droplets, while a viscosity (25°C) of more than 30 Pa·s may make it difficult to eject (or form) droplets. In this case, the non-polymerizable compound is at least one selected from the group consisting of sensitizers, hydrogen donors, internal mold release agents, surfactants, antioxidants, polymer components, and the like.

[0049] FIG. 2(A) is a schematic diagram illustrating the excess inversion layer removal step S304 according to the first embodiment. In this embodiment, in the excess inversion layer removal step S304, the first inversion layer 4a and the planarization inversion layer 4b are etched at approximately the same etching rate. The etching rate may be such that the top surfaces 12a of the convex portions 12 of the uneven pattern 2 are exposed before the bottom surfaces 13a of the concave portions 13 of the uneven pattern 2. It is more preferable that the etching rates of the first inversion layer 4a and the planarization inversion layer 4b are equal. As described above, in the past, the bottom surfaces 13a of the concave portions 13 were exposed before the excess inversion layer 5 was completely removed to expose the top surfaces 12a of the convex portions 12, resulting in the problem that the mask material required for subsequent steps was not present in the concave portions 13 of the concave-convex pattern 2. In this embodiment, the smoothed inversion layer is etched at an etching rate that exposes the top surfaces 12a of the convex portions 12 of the uneven pattern 2 before the bottom surfaces 13a of the concave portions 13 of the concave-convex pattern 2. This prevents the occurrence of a situation where the mask material required for subsequent steps is not present in the recesses 13. In this embodiment, the surface of the inversion layer 4 is smoothed in the inversion layer formation step S303. Therefore, by etching the first inversion layer 4a and the planarization inversion layer 4b at approximately the same rate, the top surfaces 12a of the protrusions 12 of the concave-convex pattern 2 are exposed before the bottom surfaces 13a of the recesses 13 of the concave-convex pattern 2. This makes it possible to remove the inversion layer 4 in a smooth state, as shown in the excess inversion layer removal step S304.

[0050] In this embodiment, etching is performed in a plasma etching apparatus by mixing multiple etching gases. x H y F z (where C represents carbon, H represents hydrogen, F represents fluorine, and x, y, and z each represent an integer of 1 or more) and a gas containing a chain hydrocarbon compound represented by C a F b The etching gases used in this example include fluorocarbon compound gases represented by the formula (a and b each represent an integer of 1 or greater). Here, Ar, CF4, and CHF3 are used as etching gases. FIG. 3 shows an example of the etching rate versus the mixture ratio of etching gases in the first embodiment. Specifically, this figure shows the etching rates of the first inversion layer 4a and the planarization inversion layer 4b of this embodiment versus the mixture ratio of the etching gases CF4 and CHF3. The vertical axis of this figure represents the etching rate, and the horizontal axis represents the flow rates of CF4 and CHF3. Here, Ar is kept constant at 50 sccm.

[0051] In this embodiment, etching is performed under conditions where the etching rates of the first inversion layer 4a and the planarization inversion layer 4b are closest, preferably overlapping. Figure 3 shows that the etching rates of the first inversion layer 4a (here, SiO2) and the planarization inversion layer 4b (here, photocurable composition (b)) overlap when Ar = 50 sccm, CF4 = 30 sccm, and CHF3 = 10 sccm. By performing etching under these conditions, it becomes possible to etch each layer at approximately the same rate.

[0052] Here, the above gas mixture ratio was used as an example to demonstrate that etching at approximately equal rates was possible. However, the required gas species and ratios vary depending on the materials used, and adjustments and considerations are necessary depending on the conditions. However, by using materials such as those shown in this embodiment as the first inversion layer material and the planarization layer material, it is possible to etch each layer at approximately equal rates by adjusting the mixture ratio, even if the gas species used changes. Furthermore, the options for first inversion layer material and planarization layer material that can be etched at approximately equal rates by adjusting the gas mixture ratio are broader than those for single materials that have sufficient etching selectivity with respect to the cured film and have a viscosity that facilitates smoothing. Therefore, when developing new materials, it is easy to focus on the characteristics of each layer, allowing for high flexibility in development, which also leads to cost reductions, and this embodiment has a significant advantage.

[0053] The etching gas may be an etching gas containing halogen, specifically, an etching gas containing one or more of fluorine, chlorine, and bromine. For example, the etching gas may be C5F6, CF4, SF6, CHF3, CH2F2, Cl2, BCl3, SiCl4, CCl4, PCl3, SF 6、 Alternatively, BBr3 or the like can be used alone or in combination of two or more gases. In addition, oxygen gas, carbon dioxide gas, nitrogen gas, helium gas, argon gas, hydrogen gas, hydrocarbon gas, or the like can be added to the above etching gas as appropriate. Gases containing hydrocarbon gas or hydrogen gas can also be used as etching gas. Examples of hydrocarbons used as etching gases include methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H 10 ), ethylene (C2H4), propylene (C3H6), acetylene (C2H2), and propyne (C3H4) can be used. Fluorocarbon gases such as CF4, CHF4, C2F6, C3F8, C4F8, C5F8, C4F6, CCl2F2, and CBrF3 can also be used as etching gases. These gases can also be used in combination.

[0054] Returning to FIG. 2, the remaining film etching step S305 is then performed. FIG. 2(B) is a schematic diagram showing the remaining film etching step S305 according to the first embodiment. Here, since the curable resin used as the planarizing layer material has substantially the same composition as the curable resin constituting the initial cured film, the planarizing inversion layer 4b is simultaneously removed in the remaining film etching step S305. However, the first inversion layer 4a remains in the recess 13. That is, as shown in FIG. 2(B), the planarizing inversion layer 4b is removed from the recess 13, and the first inversion layer 4a remains. In this state, the cured film 11 that should have remained is not lost in the remaining film etching step.

[0055] 2(C) is a schematic diagram showing the processable layer processing step S306 according to the first embodiment. In the processable layer processing step S306, since the desired reverse pattern (cured film 11) remains in the remaining film etching step S305, the processable layer on the substrate 1 is etched using the reverse pattern as a processing mask, thereby obtaining (forming) the processable layer 6 having the pattern shape.

[0056] 2(D) is a schematic diagram showing the reverse pattern removal step S307 according to the first embodiment. After the process layer processing step S306, in the reverse pattern removal step S307, the process layer of the substrate 1 is processed and then the reverse pattern, which is a processing mask, is removed. This makes it possible to form a desired pattern in the process layer.

[0057] As described above, in this embodiment, in the inversion process, a first inversion layer 4a is formed, and then a planarizing inversion layer 4b is formed on top of the first inversion layer 4a as a second inversion layer to smooth the inversion layer 4. Then, by etching the first inversion layer 4a and the planarizing inversion layer 4b at approximately the same rate, it is possible to obtain a desired pattern in the processed layer with a high degree of freedom in the selection of the inversion layer material.

[0058] Although the present embodiment uses a photocurable composition (b) as the planarization layer material, the curable composition may also contain a polymerizable compound, a photopolymerization initiator, and a solvent. Preferably, the polymerizable compound contains at least a compound having an aromatic structure, an aromatic heterocyclic structure, or an alicyclic structure. Preferably, the curable composition has a viscosity of 2 mPa·s to 60 mPa·s at 23°C. Alternatively, the curable composition may have a viscosity of 30 mPa·s to 10,000 mPa·s at 23°C in a solvent-free state, with the solvent content being 70% to 95% by volume. In this case, droplets of the planarization layer material tend to bond together and form a substantially continuous liquid film, making it easier to form a smoother inversion layer.

[0059] Furthermore, in this embodiment, the planarization inversion layer is formed by curing the material immediately after application. However, after the inversion layer formation step 302, the planarization inversion layer 4b may be smoothed using a mold (flat plate) with a flat (smooth) surface. Specifically, after the planarization layer material is ejected by inkjet printing, the flat surface of the flat plate is pressed against the planarization layer material. The planarization layer material is then cured, and the flat plate is released from the mold. This also makes it easier to form a smoother inversion layer.

[0060] In this embodiment, the inversion layer 4 is described as being composed of a first inversion layer 4a and a planarization inversion layer 4b as a second inversion layer. However, the inversion layer 4 may include three or more layers. Even in this case, the etching rate must be such that the top surfaces 12a of the convex portions 12 of the concave-convex pattern 2 are exposed before the bottom surfaces 13a of the concave-convex pattern 2. It is preferable that the etching rates of all layers included in the inversion layer 4 are equal. Alternatively, for example, the inversion layer 4 may include a first inversion layer 4a and a planarization inversion layer 4b, with a second planarization inversion layer formed on the planarization inversion layer 4b. Here, the planarization inversion layer 4b is the first planarization inversion layer. In this case, the first planarization inversion layer and the second planarization inversion layer may be etched at approximately the same rate, and then, once the second planarization inversion layer is removed, the first planarization inversion layer and the first inversion layer may be etched at approximately the same rate.

[0061] Second Embodiment In this embodiment, the basic inversion process steps are the same as in the first embodiment (the flow shown in FIGS. 1 and 2). In this embodiment, the inversion layer formation step is different from the first embodiment. Since the other steps are the same as in the first embodiment, a description thereof will be omitted here.

[0062] In the inversion layer formation step of this embodiment, droplets 16 of planarization layer material are applied (supplied) onto the first inversion layer 4a using an inkjet method, as in the first embodiment described above. In this embodiment, the application of the planarization layer material is performed by referring to information about the droplet pattern of the curable composition supplied onto the substrate during the initial cured film formation step. When the cured film 11 has a concave-convex pattern 2 and the first inversion layer material is applied using the method described in the first embodiment, the concave portions 13 of the concave-convex pattern 2, i.e., the convex regions of the mold, tend to form a concave shape as the first inversion layer. Furthermore, the convex portions 12 of the concave-convex pattern 2, i.e., the concave regions of the mold, tend to form a convex shape as the first inversion layer.

[0063] Therefore, there is a relationship between the amount of curable composition applied (supplied) during the initial cured film formation process and the amount of planarization layer material applied (supplied) required for smoothing. Therefore, in this embodiment, the droplet pattern of the planarization inversion layer material is determined by subtracting a uniform volume of one-third of the remaining film from the droplet pattern of the curable composition placed on the substrate 1 during the initial cured film formation process. The determined droplet pattern is then applied to smooth the inversion layer. This is desirable because calculations based on the droplet pattern of the curable composition applied during the initial cured film formation process allow for more efficient determination of the droplet pattern of the planarization inversion layer material.

[0064] The inversion layer forming step in this embodiment will now be described in detail with reference to Fig. 4. Fig. 4 is a flowchart illustrating the inversion layer forming step according to a second embodiment. First, in S221, a droplet pattern of the curable composition during the formation of an initialized cured film is obtained.

[0065] Next, in S222, the droplet pattern of the planarization layer material is determined. Specifically, the droplet pattern of the planarization inversion layer material is determined by subtracting the volume of one-third of the remaining film from the droplet pattern of the curable composition disposed on the substrate 1 upon formation of the initial cured film obtained in S221. As described above, when the initial cured film has a concave-convex pattern 2, the concave portions 13 of the concave-convex pattern 2, i.e., the convex regions of the mold, tend to form a concave shape as the first inversion layer, while the convex portions 12 of the concave-convex pattern 2, i.e., the concave regions of the mold, tend to form a convex shape as the first inversion layer. For this reason, for example, the droplet pattern is given a distribution so that the volume of the planarization layer material disposed at the locations corresponding to the concave portions 13 of the concave-convex pattern 2 is greater than the volume disposed at the locations corresponding to the convex portions 12 of the concave-convex pattern 2. This distribution can be achieved by increasing or decreasing the volume of each droplet, or by varying the droplet arrangement density.

[0066] In S223, droplets of the planarization layer material are supplied (applied) onto the first inversion layer 4a using the droplet pattern determined in S222, and then in S224, the planarization layer material is cured.

[0067] In addition, instead of or in addition to the information on the droplet pattern of the curable composition during the initial cured film formation process, design information of the mold used to form the initial cured film, and / or information on the concave-convex pattern 2 of the cured film 11 may be used.

[0068] The droplet pattern of the planarizing layer material may also be determined by taking into account various conditions, such as the flow of droplets of the planarizing layer material near the concave-convex pattern 2, and calculating with reference to the droplet pattern of the curable composition during the initial cured film formation process. Furthermore, if it is known in advance that unevenness will occur during the formation of the first inversion layer 4a (for example, the thickness will be thinner at the periphery of the substrate 1), such information may be taken into account. Furthermore, the substrate 1 itself may have manufacturing unevenness, and such unevenness may also be taken into account. Manufacturing unevenness of the substrate 1 tends to be similar for each lot. One lot contains multiple substrates.

[0069] Furthermore, the planarization layer material used in this embodiment can be any of the materials shown in the first embodiment, and a suitable hardening method can be used in S224.

[0070] Furthermore, although an example has been shown in which the planarization layer material is hardened as is after application, the planarization inversion layer may be smoothed by pressing the flat surface of a flat plate against the planarization layer material after application, as in the first embodiment.

[0071] As described above, in the second embodiment, when applying the planarizing layer material, the droplet pattern of the planarizing layer material is determined by referring to the droplet pattern of the curable composition in the initial cured film forming step, which makes it possible to more efficiently determine the droplet pattern when applying the planarizing layer material.

[0072] <Production method of the article> The reverse pattern formed by the pattern formation method of the present invention can be used as is as at least a part of a component of various articles. The reverse pattern can also be temporarily used as a processing mask for etching or ion implantation of a process layer on a substrate. After etching or ion implantation of the process layer on the substrate during the processing step, the reverse pattern serving as a processing mask is removed. This allows various articles to be manufactured.

[0073] The article may be an electric circuit element, an optical element, a MEMS, a recording element, a sensor, or a mold. Examples of the electric circuit element include volatile or nonvolatile semiconductor memory such as DRAM, SRAM, flash memory, and MRAM, and semiconductor elements such as LSI, CCD, image sensor, and FPGA. If the processed layer is an insulating layer, it can be used as an interlayer insulating film included in the semiconductor memory or semiconductor element.

[0074] The patterned layer obtained through the initial cured film formation process and the reverse pattern removal process can be used as an optical component such as a diffraction grating or a polarizing plate (including as a component of an optical component) to obtain an optical element. In such cases, an optical element can be obtained that has at least a substrate and a patterned layer on the substrate. Examples of optical elements include microlenses, light guides, waveguides, anti-reflection films, diffraction gratings, polarizing elements, color filters, light-emitting elements, displays, solar cells, etc.

[0075] Examples of MEMS include DMDs, microchannels, and electromechanical conversion elements. Examples of recording elements include optical disks such as CDs and DVDs, magnetic disks, magneto-optical disks, and magnetic heads. Examples of sensors include magnetic sensors, optical sensors, and gyro sensors. Examples of molds include molds for imprinting.

[0076] <Other embodiments> While the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes are possible within the scope of the present invention. In addition, the respective embodiments may be combined.

[0077] The disclosure of this embodiment includes the following methods and configurations. (Method 1) a first inversion layer forming step of forming a first inversion layer on the concave-convex pattern of the curable composition; a second inversion layer forming step of forming a planarizing inversion layer as a second inversion layer on the first inversion layer; a first etching step of etching the first inversion layer and an upper layer portion of the inversion layer including the planarizing inversion layer to expose top surfaces of the convex portions of the concave-convex pattern; a second etching step of etching the exposed pattern of the curable composition using the inversion layer remaining in the recesses of the concave-convex pattern as a mask, a first etching step for etching the first inversion layer and the planarizing inversion layer using a mixed gas containing a plurality of etching gases;

[0078] (Method 2) The pattern formation method according to Method 1, wherein the mixing ratio of the plurality of etching gases is a ratio that results in an etching rate that exposes the top surfaces of the convex portions of the concave-convex pattern before the bottom surfaces of the concave-convex pattern in the first etching step.

[0079] (Method 3) 3. The pattern formation method according to Method 1 or 2, wherein the mixing ratio of the plurality of etching gases is such that the first inversion layer and the planarizing inversion layer can be etched at approximately equal etching rates.

[0080] (Method 4) 4. The pattern formation method according to any one of Methods 1 to 3, wherein the first inversion layer contains 10% by weight or more of an inorganic element.

[0081] (Method 5) 5. The pattern forming method according to any one of Methods 1 to 4, wherein the curable composition has an inorganic element content of 1% by weight or less.

[0082] (Method 6) 6. The pattern forming method according to any one of Methods 1 to 5, wherein the curable composition that forms the concave-convex pattern and the curable composition that forms the planarization inversion layer are the same.

[0083] (Method 7) The plurality of etching gases include C x H y F z (C represents carbon, H represents hydrogen, F represents fluorine, and x, y, and z each represent an integer of 1 or more), and a F b 7. The pattern formation method according to any one of Methods 1 to 6, wherein the gas contains a fluorocarbon compound gas represented by the following formula (a and b each represent an integer of 1 or more):

[0084] (Method 8) 8. The pattern formation method according to any one of Methods 1 to 7, wherein the first inversion layer is formed by spin coating.

[0085] (Method 9) 9. The pattern formation method according to any one of Methods 1 to 8, wherein the planarization inversion layer is formed by an inkjet method.

[0086] (Method 10) A pattern formation method described in any one of methods 1 to 9, characterized in that in the second inversion layer formation process, after ejecting the inversion material of the planarizing inversion layer onto the first inversion layer using an inkjet method, the droplets of the inversion material spread, the distance between the droplets decreases, or the droplets combine to form a continuous liquid film, and the solvent in the liquid film evaporates, thereby forming the planarizing inversion layer.

[0087] (Method 11) The pattern formation method described in any one of methods 1 to 9, characterized in that the second inversion layer formation process includes a process of ejecting an inversion material of the planarization inversion layer by an inkjet method, pressing the flat surface of a mold including a flat surface against the inversion material, hardening the inversion material, and releasing the flat mold.

[0088] (Method 12) a concave-convex pattern forming step of forming the concave-convex pattern of the curable composition using a mold, the concave-convex pattern forming step includes a step of supplying droplets of the curable composition onto the substrate in a droplet pattern determined based on the concave-convex pattern of the mold, 12. A pattern forming method according to any one of methods 1 to 11, characterized in that the step of forming the planarizing inversion layer includes a step of supplying droplets of an inversion material onto the first inversion layer, and the droplet pattern used in supplying the inversion material is determined based on the droplet pattern of the curable composition.

[0089] (Production method of article) forming the pattern of the curable composition on a substrate using the pattern forming method according to any one of Methods 1 to 12; and processing the substrate on which the pattern has been formed in the process. A method for manufacturing an article, comprising manufacturing an article from the processed substrate. [Explanation of symbols]

[0090] 1 board 2. Concave and convex patterns 3 Residual membrane 4. Inversion Layer 4a First inversion layer 4b Planarization inversion layer 11 Cured film 12 Convex part 12a Top surface 13 Recess 13a Bottom 14 Reversal Patterns

Claims

1. a first inversion layer forming step of forming a first inversion layer on the concave-convex pattern of the curable composition; a second inversion layer forming step of forming a planarizing inversion layer as a second inversion layer on the first inversion layer; a first etching step of etching the first inversion layer and an upper layer portion of the inversion layer including the planarizing inversion layer to expose top surfaces of the convex portions of the concave-convex pattern; a second etching step of etching the exposed pattern of the curable composition using the inversion layer remaining in the recesses of the concave-convex pattern as a mask, a first etching step for etching the first inversion layer and the planarizing inversion layer using a mixed gas containing a plurality of etching gases;

2. 2. The pattern formation method according to claim 1, wherein a mixing ratio of the plurality of etching gases is a ratio that results in an etching rate that exposes the top surfaces of the convex portions of the concave-convex pattern before the bottom surfaces of the concave-convex pattern in the first etching step.

3. 2. The pattern formation method according to claim 1, wherein the mixture ratio of the plurality of etching gases is a ratio that allows etching of the first inversion layer and the planarizing inversion layer at approximately equal etching rates.

4. 2. The pattern formation method according to claim 1, wherein the first inversion layer contains 10% by weight or more of an inorganic element.

5. 2. The pattern forming method according to claim 1, wherein the curable composition contains inorganic elements in an amount of 1% by weight or less.

6. 2. The pattern forming method according to claim 1, wherein the curable composition for forming the concave-convex pattern and the curable composition for forming the planarization inversion layer are the same.

7. The plurality of etching gases include C ｘ H ｙ F ｚ (C represents carbon, H represents hydrogen, F represents fluorine, and x, y, and z each represent an integer of 1 or more), and ａ F ｂ 2. The pattern formation method according to claim 1, wherein the fluorocarbon compound gas contains a fluorocarbon compound gas represented by the following formula (a and b): (a and b each represent an integer of 1 or more).

8. 2. The pattern formation method according to claim 1, wherein the first inversion layer is formed by spin coating.

9. 2. The pattern formation method according to claim 1, wherein the planarization inversion layer is formed by an ink-jet method.

10. The pattern formation method described in claim 1, characterized in that in the second inversion layer formation process, after the inversion material of the planarizing inversion layer is ejected onto the first inversion layer by an inkjet method, the droplets of the inversion material spread, the distance between the droplets decreases, or the droplets combine to form a continuous liquid film, and the solvent in the liquid film evaporates, thereby forming the planarizing inversion layer.

11. The pattern formation method of claim 1, characterized in that the second inversion layer formation process includes a process of ejecting an inversion material of the planarization inversion layer by an inkjet method, pressing the flat surface of a mold including a flat surface against the inversion material, hardening the inversion material, and releasing the flat mold.

12. a concave-convex pattern forming step of forming the concave-convex pattern of the curable composition using a mold, the concave-convex pattern forming step includes a step of supplying droplets of the curable composition onto the substrate in a droplet pattern determined based on the concave-convex pattern of the mold, 2. The pattern forming method of claim 1, wherein the step of forming the planarizing inversion layer includes a step of supplying droplets of an inversion material onto the first inversion layer, and the droplet pattern used in supplying the inversion material is determined based on the droplet pattern of the curable composition.

13. forming the pattern of the curable composition on a substrate using the pattern forming method according to any one of claims 1 to 12; and processing the substrate on which the pattern has been formed in the process. A method for manufacturing an article, comprising manufacturing an article from the processed substrate.

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