Imprint system, imprint method, replica mold manufacturing method, and article manufacturing method

Abstract

To provide an imprint system capable of improving alignment performance using a substrate side mark.SOLUTION: An imprinting system for transferring a pattern formed on a mold to an imprint material supplied on a substrate, comprises: forming means for forming a substrate side mark including a predetermined material by transferring and processing a desired substrate side mark after constituting on the surface of the substrate a predetermined material having an optical difference in physical properties from the imprint material larger than the substrate; and alignment means for aligning the substrate side mark including the predetermined material with a mold side mark on the mold.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an imprint system ,stomach an imprint method, a method for manufacturing a replica mold , and a method for manufacturing an article, and the like.

Background Art

[0002] In recent years, a microfabrication technology for pressure-transferring a fine structure on a mold to a workpiece such as resin or metal has been developed and has attracted attention.

[0003] This technology is called nanoimprint or nanoembossing, etc., and has a resolution on the order of several nm, so there is increasing expectation as a next-generation semiconductor manufacturing technology to replace optical exposure devices such as steppers and scanners.

[0004] Furthermore, since this technology can batch-process a three-dimensional structure on a wafer, its application to manufacturing technologies in fields other than semiconductors is expected.

[0005] When applying such an imprint method to semiconductor manufacturing technology, it is performed as follows. That is, a photocurable imprint material layer is formed on a substrate (for example, a semiconductor wafer). Then, a mold having a desired uneven pattern formed on its processing surface is pressed against the imprint material, the imprint material is filled into the uneven portions, and the resin is cured by irradiating ultraviolet light. Thus, since the above pattern is transferred to the imprint material layer, etching or the like is performed using this imprint material layer as a mask layer, and pattern formation on the semiconductor wafer is performed.

[0006] In such imprint technology, aligning the mold pattern with the substrate pattern is a crucial issue when transferring the mold's raised and recessed pattern. Patent Document 1 describes how to align the two in the following way: A light-transmitting mold substrate is provided with position reference marks, and marks corresponding to the position reference marks on the mold substrate are also formed on the substrate. These position reference marks are then used to align the mold with the substrate.

[0007] In other words, by transmitting light from above the mold substrate and simultaneously observing the position reference marks provided on the mold substrate and the marks formed on the workpiece, the mold and the workpiece can be aligned. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2000-323461 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] On the other hand, in recent years, applications to manufacturing technologies in fields other than semiconductors have been explored. Examples include optical elements such as photonic crystals, or biochip manufacturing technologies such as μ-TAS (Micro Total Analysis System). In this case, a problem arises where the substrate material has small differences in optical properties from the photocurable imprint material used for imprinting, such as glass, making it difficult to detect the marks on the substrate.

[0010] The aforementioned mold marks require high durability because they are used repeatedly, and the material composition for the marking area could be time-consuming and costly. However, the marks on the circuit board only need to be visible during the imprinting process, so durability is not necessary, and they need to be simple to produce in large quantities. In addition, it is necessary to suppress cost increases by minimizing unnecessary steps within the series of processes.

[0011] In view of the above-mentioned problems, one objective of the present invention is to provide an imprint system capable of improving alignment performance using substrate-side marks. [Means for solving the problem]

[0012] To achieve the above objectives, one aspect of the present invention is: In an imprint system that transfers a pattern formed in a mold onto an imprint material supplied onto a substrate, Forming means for forming a substrate-side mark containing the predetermined material by first forming a predetermined material on the surface of the substrate in which the difference in predetermined optical properties from the imprint material is greater than that of the substrate, and then transferring and processing a desired substrate-side mark, With the mold in contact with the imprint material, the substrate-side mark, which includes the predetermined material covered by the imprint material, is optically detected. The present invention is characterized by having alignment means for aligning the substrate-side mark containing the predetermined material with the mold-side mark provided on the mold. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an imprint system that can improve alignment performance using substrate-side marks. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing an example of the configuration of an imprint device 1 according to Embodiment 1 of the present invention. [Figure 2] (A) and (B) are diagrams illustrating an example of the configuration of alignment marks according to Embodiment 1. [Figure 3] (A) to (C) are diagrams showing the imprint process according to Embodiment 1. [Figure 4] (A)-1, (A)-2, (B) to (D) are diagrams showing the manufacturing process of the mark portion and the imprint process in the imprint system according to Embodiment 1 of the present invention. [Figure 5] (A) to (C) are diagrams showing the manufacturing process of the mark portion and the imprint process of Embodiment 1. [Figure 6] (A) to (C) are diagrams for explaining an example in which optical simulation is used to obtain the necessary optical physical property values of Material 24. [Figure 7] (A) to (C) are diagrams for explaining an example in which optical simulation is used when changing the thickness of Material 24 and the depth of the concave structure in FIG. 6. [Figure 8] (A) to (H) are diagrams showing the process of creating a replica mold of Embodiment 2 of the present invention.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. In each figure, the same members or elements are denoted by the same reference numerals, and duplicate explanations are omitted or simplified.

[0016] In an imprint system, a pattern formed on a mold (die) is brought into contact with an imprint material supplied onto a substrate, and energy for curing is applied to the imprint material, thereby forming a pattern of a cured product in which the concave and convex pattern of the mold (die) is transferred. That is, in the imprint system, for example, a liquid imprint material is supplied onto a substrate, and ultraviolet light is irradiated onto the imprint material in a state where a mold (die) having a concave and convex pattern is brought into contact with the imprint material on the substrate to cure it.

[0017] Then, by widening the gap between the mold and the substrate and peeling (releasing) the mold from the cured imprint material, the pattern of the mold can be transferred onto the imprint material on the substrate. Such a series of processes is called "imprinting process" and is performed for each of the plurality of shot regions on the substrate.

[0018] As the imprint material, a curable composition (which may also be referred to as an uncured resin or imprint material) that cures when energy for curing is applied is used. As the energy for curing, electromagnetic waves, heat, etc. are used. As the electromagnetic waves, for example, light such as infrared rays, visible light, and ultraviolet rays whose wavelength is selected from the range of 10 nm or more and 1 mm or less is used.

[0019] The curable composition is a composition that cures by irradiation with light or by heating. Among these, the photocurable composition that cures by light contains at least a polymerizable compound and a photopolymerization initiator, and may contain a non-polymerizable compound or a solvent as necessary. The non-polymerizable compound is at least one selected from the group consisting of a sensitizer, a hydrogen donor, an internal mold release agent, a surfactant, an antioxidant, a polymer component, etc. The imprint material is applied in a film form on the substrate by a spin coater or a slit coater.

[0020] Alternatively, it may be applied on the substrate in the form of droplets or in an island or film form formed by connecting a plurality of droplets by a liquid injection head. The viscosity of the imprint material (viscosity at 25°C) is, for example, 1 mPa·s or more and 100 mPa·s or less.

[0021] <Embodiment 1> FIG. 1 is a schematic diagram showing a configuration example of an imprint apparatus 1 according to Embodiment 1. The imprint apparatus 1 forms and cures an imprint material (not shown) supplied onto a substrate 13 with a mold (die) 11 having a pattern region on which an uneven pattern is formed. Then, an imprint process for forming a pattern on the substrate is performed by pulling the mold away (releasing, peeling) from the cured imprint material.

[0022] In the imprinting apparatus 1, the space in which the imprinting process is performed is called the processing area. In this embodiment, resin is used as the imprinting material, and a photocuring method is employed in which the resin is cured by irradiation with ultraviolet light.

[0023] The imprint device 1 includes a mold holding unit 12 for holding the mold 11, a substrate holding unit 14 for holding the substrate 13, a detection unit 15, an irradiation unit 16, and a control unit 17. The control unit has a built-in CPU as a computer and memory as a storage medium, and the CPU executes a computer program stored in the memory to control the imprint process and other operations performed by the imprint device.

[0024] Furthermore, the imprint apparatus may also include a supply unit containing a dispenser for supplying ultraviolet-curable imprint material onto the substrate, and a shape deformation mechanism for deforming the pattern area 11a of the mold 11 by applying force to the side surface of the mold 11. In addition, the imprint apparatus 1 may also include a bridge plate for holding the mold holding unit 12, a base plate for holding the substrate holding unit 14, and a storage unit for storing multiple molds 11.

[0025] The mold 11 has a pattern region 11a on which a pattern (recessed pattern) to be transferred to the substrate 13 (the imprint material on it) is formed. The mold 11 is made of a material that transmits ultraviolet light for curing the imprint material on the substrate 13, such as quartz. Alignment marks (mold-side marks 18) used to control the positioning of the mold 11 and the substrate 13 are formed in the pattern region 11a of the mold 11.

[0026] The mold holding section 12 is a holding mechanism for holding the mold 11. The mold holding section 12 includes, for example, a mold chuck for vacuum or electrostatic attraction of the mold 11, a mold stage on which the mold chuck is placed, and a drive system for driving (moving) the mold stage.

[0027] Such a drive system drives the mold stage (i.e., the mold 11) at least along the Z-axis direction (the direction of imprinting when the mold 11 is imprinted on the imprint material on the substrate 13). Furthermore, such a drive system may also have the function of driving the mold stage not only in the Z-axis direction, but also in the X-axis direction, Y-axis direction, and θ (rotation around the Z-axis) direction.

[0028] The substrate 13 is a substrate onto which the pattern of the mold 11 is transferred (i.e., a substrate on which a pattern composed of imprint material is formed). Examples of materials that can be used for the substrate 13 include glass, ceramics, metal, semiconductor, and resin. Imprint material is supplied (applied) to the substrate 13 from a supply unit (not shown). Furthermore, alignment marks (substrate-side marks 19) used to control the positioning between the mold 11 and the substrate 13 are formed on the substrate 13.

[0029] The substrate holding section 14 is a holding mechanism for holding the substrate 13. The substrate holding section 14 includes, for example, a substrate chuck for vacuum or electrostatic adsorption of the substrate 13, a substrate stage on which the substrate chuck is placed, and a drive system for driving the substrate stage.

[0030] Such a drive system drives the substrate stage (i.e., the substrate 13) in at least the X-axis direction and the Y-axis direction (directions perpendicular to the Z-axis direction, which is the direction in which the mold 11 is imprinted). Furthermore, such a drive system may also have the function of driving the substrate stage not only in the X-axis direction and the Y-axis direction, but also in the Z-axis direction and the θ (rotation around the Z-axis) direction. The drive system of the substrate holding section 14 functions as an alignment means for aligning the substrate-side mark 19 and the mold-side mark 18.

[0031] The detection unit 15 can detect the position of alignment marks (substrate-side marks 19) provided on the substrate 13. In this embodiment, the detection unit 15 includes a scope for optically observing the substrate-side marks 19 and mold-side marks 18 through the mold 11, and detects the relative position between the mold-side marks 18 and the corresponding substrate-side marks 19.

[0032] For example, the detection unit 15 measures the relative position between the mold-side mark 18 and the corresponding substrate-side mark 19 using a scope, and calculates the relative position between the mold 11 (pattern area 11a) and the substrate 13 (shot area) based on the measurement results.

[0033] The detection unit 15 may include a scope equipped with an optical system for simultaneously imaging two marks, or it may include a scope for detecting signals that reflect the relative positional relationship of the two marks, such as interference signals or moiré patterns.

[0034] Furthermore, the detection unit 15 does not necessarily need to be able to detect the mold-side mark 18 and the substrate-side mark 19 simultaneously. For example, the detection unit 15 may detect the relative positional relationship between the mold-side mark 18 and the substrate-side mark 19 by determining the respective positions of the mold-side mark 18 and the substrate-side mark 19 with respect to a reference position located inside.

[0035] The irradiation unit 16 irradiates the imprint material on the substrate with light 30 (e.g., ultraviolet light) for curing the imprint material via the mold 11, thereby curing the imprint material. The irradiation unit 16 may include, for example, a light source that emits light 30 for curing the imprint material, and an optical system for adjusting the light 30 emitted from the light source to the optimal light for the imprint process.

[0036] The imprint apparatus 1 of this embodiment is configured such that light 30 emitted from the irradiation unit 16 is reflected by the beam splitter 32 and irradiated onto the substrate 13 (specifically, the imprint material on the substrate).

[0037] The observation unit 31 includes, for example, a camera with a field of view that encompasses the entire pattern area 11a of the mold 11, and has the function of observing (confirming) the hardening state of the imprint material on the substrate by irradiation with ultraviolet light.

[0038] In this embodiment, the imprint apparatus 1 is configured such that the observation unit 31 observes the hardening state of the imprint material on the substrate via the beam splitter 32. The observation unit 31 can also observe the pressing state of the mold 11 onto the imprint material on the substrate, the filling state of the imprint material into the pattern of the mold 11, and the release state of the mold 11 from the hardened imprint material on the substrate.

[0039] Figures 2(A) and 2(B) illustrate an example of the alignment mark configuration according to Embodiment 1, showing the mold-side mark 18 and the substrate-side mark 19. In the example shown in Figures 2(A) and 2(B), six chip regions are arranged in one shot region of the substrate 13.

[0040] Figure 2(A) shows an example of the arrangement of mold-side marks 18a to 18h formed at the four outer corners of the pattern area 11a (the entire six rectangular areas enclosed by dotted lines) of the mold 11. In Figure 2(A), mold-side marks 18a, 18b, 18e, and 18f, which have their longitudinal direction in the X-axis direction, are marks for measuring position in the X-axis direction.

[0041] Furthermore, the mold-side marks 18c, 18d, 18g, and 18h, which have a longitudinal direction in the Y-axis direction, are marks for measuring the position in the Y-axis direction. Also, in Figure 2(A), the six rectangular regions 11b enclosed by dotted lines represent the pattern regions 11a to be transferred to each of the six chip regions 13b on the substrate.

[0042] Figure 2(B) shows substrate-side marks 19a to 19h located at the four outer corners of one shot area 13a (the entirety of the six rectangular areas enclosed by solid lines) on the substrate 13. In Figure 2(B), substrate-side marks 19a, 19b, 19e, and 19f, which have their longitudinal direction in the X-axis direction, are marks for measuring position in the X-axis direction.

[0043] Furthermore, the substrate-side marks 19c, 19d, 19g, and 19h, which have a longitudinal direction in the Y-axis direction, are marks for measuring the position in the Y-axis direction. Also, in Figure 2(B), the six regions enclosed by solid lines that constitute the shot region 13a each represent a chip region 13b. Note that each chip region 13b is a region from which, for example, one semiconductor chip on which an integrated circuit is formed can be obtained.

[0044] During the imprint process, when the mold 11 and the imprint material on the substrate are brought into contact, the mold-side marks 18a to 18h on the mold 11 and the substrate-side marks 19b to 19h on the substrate 13 come into close proximity. Therefore, by detecting the mold-side marks 18 and the substrate-side marks 19 with the detection unit 15, the position and shape of the pattern area 11a of the mold 11 and the position and shape of the shot area 13a of the substrate 13 can be compared.

[0045] If there is a difference (misalignment) between the position and shape of the pattern area 11a of the mold 11 and the position and shape of the shot area 13a on the substrate 13, the overlapping accuracy will decrease, leading to poor pattern transfer (product defects).

[0046] Figures 3(A) to 3(C) illustrate the imprint process according to Embodiment 1. Referring to Figures 3(A) to 3(C), the imprint process, in which the pattern of the mold 11 is transferred to the imprint material on the substrate 13 and molded, will be described.

[0047] As shown in Figure 3(A), before the mold 11 starts printing, the imprint material 20 is supplied to the target shot area on the substrate (the shot area to be imprinted). Imprint materials commonly used in imprint machines are highly volatile, so they are supplied to the substrate immediately before the imprinting process. However, if the imprint material has low volatility, it may be supplied to the substrate in advance using a spin coater or the like.

[0048] Furthermore, after supplying the imprint material 20 onto the substrate, the substrate 13 is moved downwards from the mold 11. The detection unit 15 then detects the relative position between the mold-side mark 18 and the substrate-side mark 19, and based on the detection result, the alignment of the mold 11 and the substrate 13 and the shape correction of the mold 11 are controlled while the mold is in contact with the imprint material.

[0049] Next, as shown in Figure 3(B), the mold 11 is brought into contact with the imprint material 20 on the substrate, and a predetermined time is allowed to pass in this state to fill the pattern (recessed structure) of the mold 11 with the imprint material 20. During this time, the detection unit 15 is also used to detect the mold-side mark 18 and the substrate-side mark 19, and the alignment of the mold 11 and the substrate 13 is controlled based on the detection results.

[0050] Once the pattern of the mold 11 is filled with the imprint material 20 (i.e., after a predetermined time has elapsed), the irradiation unit 16 irradiates the imprint material 20 on the substrate with light 30 to cure the imprint material 20.

[0051] Then, as shown in Figure 3(C), the mold 11 is removed (released) from the hardened imprint material 20 on the substrate. This allows the pattern 21 made of the imprint material 20 to be formed on the substrate. In other words, the pattern of the mold 11 can be transferred onto the substrate.

[0052] In Figure 3(B), if the difference in optical properties between the mold 11 and the imprint material 20 is small, and the mold-side mark 18 consists only of a raised and recessed structure, it may be difficult for the detection unit 15 to detect the mold-side mark 18.

[0053] Therefore, it is desirable to configure the mold-side mark 18 with a material having different optical properties (refractive index and extinction coefficient) than the mold 11, or to change the refractive index of the mold-side mark 18 region by ion irradiation or the like. This makes it possible for the detection unit 15 to detect the mold-side mark 18 even when the mold 11 is in contact with the imprint material 20 on the substrate.

[0054] However, Nanoimprint Lithography (NIL) is sometimes used to fabricate optical elements that exhibit optical functions. In such cases, the imprint process is performed using substrates such as glass, which have optical properties similar to those of the imprint material, or substrates whose optical properties are not significantly different from those of the ambient gas.

[0055] In that case, the marks formed on the substrate become difficult to see during or before contact with the liquid. Unlike molding, a very large number of substrates are processed during mass production, so it is necessary to apply a simple and inexpensive method. On the other hand, durability is not required as the marks only need to be visible during pattern transfer using NIL. Taking these factors into consideration, in this embodiment, easily observable substrate-side marks are created as follows.

[0056] Figures 4(A)-1, (A)-2, (B) to (D) illustrate the mark fabrication process and the imprint process in the imprint system according to Embodiment 1 of the present invention. Figure 4(A)-1 shows an example of creating a pattern or mark on a substrate used for imprinting using a lithography exposure apparatus, and Figure 4(A)-2 shows an example of creating a pattern or mark on a substrate used for imprinting using NIL. In both cases, after a predetermined material 24 is formed on the surface of the substrate, the desired substrate-side mark is transferred.

[0057] Figure 4(A)-1 shows a lithography resist 22 applied to a substrate 13, with the reticle pattern being transferred and exposed using ultraviolet light. Although there are differences in negative and positive depending on the resist characteristics, in Figure 4(A)-1, the exposed area 23 is considered the etched region. At this time, the material 24 can be formed between the resist and the substrate by first forming the material 24 on the substrate 13 and then applying the resist 22.

[0058] Furthermore, material 24 is a material whose optical properties differ from those of the substrate and imprint material by a predetermined value or more. Here, the difference in optical properties between material 24 and the imprint material is greater than the difference in optical properties between the imprint material and the substrate. Here, the predetermined optical properties are the refractive index and the extinction coefficient.

[0059] On the other hand, in Figure 4(A)-2, the material 24 is pre-formed on the substrate 13, and the mold pattern is transferred to it using the NIL process shown in Figure 3.

[0060] Figure 4(B) shows the state after development or demolding of the mold. Figure 4(C) shows the result of processing by applying an etching process as a processing step, using the imprint material 20 or resist 22 as an etching mask.

[0061] Thus, the steps in Figure 4(A)-1 or (A)-2, (B), and (C) function as a forming step to create a substrate-side mark containing the predetermined material 24 by first forming the predetermined material 24 on the surface of the substrate and then transferring and processing the desired substrate-side mark. Furthermore, a process apparatus serving as a forming means for carrying out this forming step is provided in the imprint system.

[0062] As shown in Figure 4(C), the material 24 is etched according to the transfer pattern. As a result, when the substrate 13 is optically observed from above, a difference in signal intensity is generated due to the difference in reflectivity between the areas where the material 24 is present and those where it is not, making it possible to detect it as a mark.

[0063] Furthermore, in the mark detection method utilizing diffraction, diffracted light is generated by creating a certain optical path difference (phase difference). Therefore, for example, the refractive index and thickness of material 24 can be changed to obtain the desired optical path difference. The optimal material properties will vary depending on the mark detection method, so they should be estimated as appropriate through simulations or other means.

[0064] Figure 4(D) shows the process of supplying imprint material to the substrate created in the steps up to Figure 4(C), and then imprinting, similar to Figure 3(B). The imprint material 20 is filled into the uneven areas of the substrate 13 and the mold 11 by pressing. It is desirable that the mold marks be made of mold mark material 25 in the recess of the mold mark 18, which has optical properties that differ from the imprint material and mold material by a predetermined value or more, so that the mold marks can be detected even in this state.

[0065] In the state shown in Figure 4(D), the relative positions of the mold-side mark 18 and the substrate-side mark 19, which includes the material 24 (with some material 24 remaining), are measured using the detection unit 15, and the alignment process is performed. From the differences between each mark obtained, the shift, rotation, magnification, and deformation of the shot shape are calculated, and corrections are performed using the respective correction mechanisms.

[0066] Figures 5(A) to 5(C) show the mark fabrication process and imprint process of Embodiment 1, and illustrate the substrate pattern processing process when the remaining unprinted area is reversed. Figure 5(A) is equivalent to Figure 4(B) in terms of process and shows the state after lithography transfer and development, or the state after NIL transfer. Figure 5(B) shows the result of performing an etching process using this imprint material 20 or resist 22 as an etching mask.

[0067] Figure 5(C) shows the substrate in Figure 5(B) after the imprint process has been performed. Since material 24 remains on the raised parts of the marks on the substrate, a high-contrast detection signal can be obtained due to the optical difference in physical properties between the parts where material 24 remains and the parts where material 24 is not, similar to Figure 4(D).

[0068] As described above, material 24 should preferably have physical properties that allow for signal acquisition when observing alignment marks. Specifically, when measuring during imprinting, it is desirable that the difference in optical properties (refractive index, extinction coefficient) between the imprint material and the material is greater than or equal to a predetermined value. Furthermore, if the difference in optical properties between the ambient gas and the substrate is not large even before contact with the imprint material, the contrast of the detection signal will be weakened. However, by using the alignment marks on the substrate side created using the method of this embodiment, it is possible to stably acquire a detection signal with higher contrast.

[0069] Furthermore, if the material 24 is to be peeled off after the etching process using the pattern transferred in this process, a material that is easy to peel off is preferable. For example, a resin that is easy to peel off by washing may be used as material 24. Moreover, if it is to be used in a device process, a material suitable for that process is preferable. For example, metals such as Cu or Co may be used as material 24, as is done in wiring processes.

[0070] Figures 6(A) to 6(C) illustrate an example of using optical simulation to determine the required optical properties of material 24. Figures 7(A) to 7(C) illustrate an example of using optical simulation when the thickness of material 24 and the depth of the concave structure are changed compared to Figure 6.

[0071] Figure 6(A) shows a model of the cross-sectional structure during imprinting. Material 24 is constructed on a glass substrate 13, and a concave structure with a width of 1000 nm and a depth of 150 nm is created by etching. Subsequently, the imprint material 20 is applied, and the image shows the state after imprinting with mold 11. In this case, material 24 has a thickness of 100 nm, and the imprint material 20 has a thickness of 50 nm. On the other hand, Figure 7(A) shows a model with the same structure as in Figure 6(A), but with a material 24 thickness of 150 nm.

[0072] Figures 6(B) and 6(C) show the results of optical simulations in which the refractive index n and extinction coefficient k, which are optical properties of material 24 in Figure 6(A), were varied. Figures 7(B) and 7(C) show the results of performing a similar optical simulation using the model in Figure 7(A). The contrast on the vertical axis represents the value obtained by "(maximum - minimum) ÷ (maximum + minimum)" of the signal intensity obtained from the simulation.

[0073] Figures 6(B) and 7(B) show that when the extinction coefficient k is zero, the contrast changes significantly with respect to the change in refractive index n. Furthermore, comparing Figures 6(B) and 7(B) in this case reveals a difference in the change in contrast with respect to the refractive index.

[0074] From these observations, it can be inferred that when the extinction coefficient k is zero, optical interference in material 24 affects the contrast. On the other hand, when the extinction coefficient increases, a consistently high contrast is observed. This is thought to be because the light transmittance of material 24 decreases, making it less susceptible to the effects of optical interference.

[0075] From these, it is possible to determine the appropriate refractive index n, extinction coefficient k, film thickness, etc., as conditions for material 24 to obtain the contrast necessary to achieve the required measurement accuracy. For example, in the case of the configuration in Figure 6(A), if a high contrast of 0.5 or higher is desired, one should select from the calculated ranges in Figures 6(B) and (C) a refractive index of 3.5 or higher and an extinction coefficient of 0 to 2, or an extinction coefficient of 2 to 4 and a refractive index of 1.5 to 3.5. In the case of the configuration in Figure 7(A), if a high contrast of 0.5 or higher is desired, one should select from the calculated ranges in Figures 7(B) and (C) a refractive index of 2.3 to 3.6 and an extinction coefficient of 0 to 2, or an extinction coefficient of 2 to 4 and a refractive index of 1.5 to 3.5.

[0076] Furthermore, the necessary conditions for material 24 include optical interference conditions due to the film thickness and structure of the substrate and mold, as well as the layered structure of other materials constructed on the substrate side. Therefore, it is desirable to confirm these conditions through sequential simulations and actual evaluations.

[0077] Furthermore, since material 24 is formed to create a mark on the substrate side, it is removed after etching using the transfer pattern by performing the process shown in Figure 4(D). That is, after transferring the mold pattern to the imprint material, there is a removal step to remove the material 24 formed on the substrate. The imprint system also has a process apparatus as a removal means for performing the above removal step. However, if material 24 can be used in a series of device manufacturing processes, it may be left in place without being removed.

[0078] As described above, the substrate mark formation method of Embodiment 1 makes it possible to easily and inexpensively create substrate marks that are easily detectable during imprinting on substrates with small differences in optical properties from the imprint material. Furthermore, by using the substrate alignment marks created in this embodiment, it is possible to stably acquire detection signals with higher contrast, enabling highly accurate alignment and improving the reliability of products manufactured by imprinting.

[0079] Furthermore, when the substrate is generally made of glass or similar material, it does not absorb much light, making it difficult to correct the substrate shape by locally irradiating it with light to generate heat. However, as in this embodiment, by using a material 24 with a high light absorption rate, the material 24 absorbs the illumination light locally irradiated onto the substrate, generating heat. This makes it possible to correct the shot shape by locally irradiating a part of the substrate with light.

[0080] <Embodiment 2> As Embodiment 2, a method for fabricating a nanoimprint mold using Embodiment 1 will be described. In the nanoimprint mold, the mold is in contact with a liquid, and after the imprint material (UV-curable type) is filled into the mold pattern, the imprint material is cured by irradiation with ultraviolet light. For this reason, the mold must be made of a material that transmits ultraviolet light, such as quartz.

[0081] To reduce costs, mold patterns are sometimes created by drawing the pattern on an EB (Electron Beam) lithography device (a so-called master mold). This master mold is then imprinted onto another mold substrate to transfer the pattern, which is then etched and used as an imprint mold (a so-called replica mold).

[0082] In recent years, patterns for devices have become increasingly miniaturized, to the point where they cannot be drawn even with electron beam printing (EB). While lithography projects a reduced mask pattern, nanoimprint lithography, in particular, requires 1:1 size transfer, necessitating the construction of the required fine patterns on a NIL mask.

[0083] Therefore, by performing processing steps such as SADP (Self-Aligned Double Patterning) and SAQP (Self-Aligned Quadruple Patterning) on ​​the patterns transferred onto the molded substrate, even finer line widths can be achieved.

[0084] However, when the above process is applied to a mold for nanoimprinting, the alignment marks become so thin that they are difficult to detect, even at the level of actual devices. Furthermore, even if an attempt is made to create a separate material in the mark recess to make the mold-side mark visible when wetted, if the width of the recess is narrow, it is difficult to create the separate material in the mark recess, resulting in an extremely thin film, making it difficult to obtain a detection signal.

[0085] Furthermore, when creating a device pattern using processing steps such as SADP or SAQP as described above, and then constructing alignment marks, it is necessary to precisely align the relative position with the device pattern. Therefore, it is necessary to form marks with good detection accuracy, but marks on quartz substrates, for example, are generally difficult to observe during imprinting. Accordingly, even when the substrate is quartz or similar, applying the method of Embodiment 1 can improve the contrast of the alignment marks.

[0086] Figures 8(A) to 8(H) show the process for creating a replica mold according to Embodiment 2 of the present invention, and an example of the replica mold manufacturing method in Embodiment 2 will be explained with reference to Figures 8(A) to 8(H).

[0087] Figure 8(A) shows the process of transferring the device pattern onto the mold substrate 13 (replica mold substrate) for the replica mold, and Figure 8(B) shows the developed state. Here, the reticle pattern is transferred by lithography, but the desired pattern may also be transferred by nanoimprint. In that case, the transferred pattern will have the same shape as in Figure 8(B).

[0088] Here, the steps in Figures 8(A) and 8(B) function as a forming step to create the substrate-side mark. In the forming step, after the material 24 is formed on the surface of the replica mold substrate, the first pattern and the substrate-side mark are transferred onto the replica mold substrate, and the material 24 is processed along with the material. As a result, the first pattern including the material 24 and the substrate-side mark including the material 24 are formed on the replica mold substrate.

[0089] In Figure 8(C), a thin film 27 is formed on the surface of this transfer pattern (first pattern) in order to perform SADP. Then, by removing the pattern created in Figure 8(B), only the thin film 27 can be left, as shown in Figure 8(D). By etching using this as a mask, a finer and denser pattern can be created than the initial transfer pattern. By repeating the same process once more, an even finer and denser pattern can be created (SAQP process).

[0090] If this process is also applied to the marking area, it results in a fine-structured alignment mark, making it impossible to secure a sufficient line width to obtain an alignment signal. Therefore, in Embodiment 2, the alignment mark (new marking area) is created separately after this process.

[0091] Figure 8(E) shows the result of etching using a reversed pattern as a mask. The pattern's surface irregularities change depending on the transfer conditions, but it is possible to reverse the irregularities by applying a reversed film after pattern transfer and then removing the transferred pattern. Figure 8(F) shows the imprinting process of alignment marks (new marks) onto the substrate created in Figure 8(E). Prior to the process in Figure 8(F), there is a supply process in which the imprint material is supplied onto the replica mold substrate.

[0092] In the process shown in Figure 8(F), a step is formed in the mold 11 so that the imprint material becomes thicker, in order to protect the pattern created in the previous process with the imprint material in the next etching process.

[0093] Furthermore, although the marked area of ​​the mold substrate 13 for the replica mold has a fine structure, it can be observed with high contrast because it contains material 24. Therefore, the mark on the substrate and the mark on the mold are aligned. Then, the mark to be used when the mold substrate 13 for the replica mold is used as a mold (new mark area) and the layer of imprint material to protect the pattern area created in the previous step during the next etching step are transferred to the imprint material 20 on the replica mold substrate.

[0094] Furthermore, material 25 may be pre-formed in the recess of the mold mark to make it easier to detect the mold mark when stamping.

[0095] Figure 8(G) shows the state after etching using the imprint material transferred as described above as a mask, and Figure 8(H) shows the state after removing material 24.

[0096] If Embodiment 2 is not applied, the alignment accuracy of the marked area is significantly reduced. As a result, the relative position of the new marked area and the pattern area on the mold substrate 13 for the replica mold becomes very large, requiring a large alignment offset when imprinting using the replica mold. Nanoimprint employs a so-called die-di-alignment method in which the relative position of the mold-side mark and the substrate-side mark is measured for each shot, so a large offset can cause noise light from adjacent patterns to be introduced.

[0097] Therefore, by using the method of Embodiment 2, the offset can be reduced and kept within an acceptable range. However, in the case of replica molds created using the method of Embodiment 2, an offset may occur between the mark portion and the pattern portion. In such cases, the relative position can be measured separately, or the offset amount can be calculated by actually performing an imprint, and the position can be adjusted taking that offset amount into consideration.

[0098] According to Embodiment 2, by the above steps, it is possible to create an imprint mold that combines a fine pattern area with a new mark area having the line width necessary to obtain an alignment signal.

[0099] (Embodiment of a method for manufacturing articles) By using the imprint system and imprint method according to this embodiment, productivity and quality can be improved when manufacturing items such as microdevices like semiconductor devices or elements with fine structures.

[0100] This document describes a method for manufacturing devices as articles (semiconductor devices, magnetic storage media, liquid crystal display elements, etc.). Such a manufacturing method may include a pattern formation step in which a mold pattern is formed on the surface of a substrate (wafer, glass plate, film substrate, etc.) using a lithography apparatus. The step of transferring the mold pattern may include a pattern formation step in which a flat pattern is formed. Furthermore, the substrate is not limited to a single base material but may include a multilayer structure. Alternatively, the method may include a pattern formation step in which a pattern is exposed to a photoreceptor on the substrate using a lithography apparatus.

[0101] Furthermore, such a manufacturing method further includes a step of processing the substrate before or after the pattern formation step. For example, the processing step may include a step of removing residual pattern film or a development step. Furthermore, the process includes a processing step, such as etching the substrate using the pattern as a mask, on the substrate on which the pattern has been formed in the pattern formation step. The processing step may include a step of cutting out chips from the substrate (dicing), a step of placing chips on a frame and electrically connecting them (bonding), and a step of sealing with resin (molding).

[0102] The method for manufacturing articles using an imprinting device, etc., in this embodiment is advantageous in at least one of the following aspects of article performance, quality, productivity, and production cost, because it can stably ensure alignment accuracy compared to conventional methods.

[0103] Although the present invention has been described in detail above based on its preferred embodiments, the present invention is not limited to the above embodiments, and various modifications are possible in accordance with the spirit of the present invention, and these modifications are not excluded from the scope of the present invention. The above embodiments include, for example, at least the following configurations.

[0104] (Configuration 1) An imprint system for transferring a pattern formed on a mold onto an imprint material supplied onto a substrate, comprising: forming means for forming a substrate-side mark including the predetermined material by first forming a predetermined material on the surface of the substrate in which the difference in predetermined optical properties between the imprint material and the substrate is greater than that of the substrate, and then transferring and processing a desired substrate-side mark; and alignment means for aligning the substrate-side mark including the predetermined material with a mold-side mark provided on the mold.

[0105] (Configuration 2) The imprint system according to Configuration 1, characterized in that the alignment is performed while the mold is in contact with the imprint material.

[0106] (Configuration 3) The imprint system according to Configuration 1 or 2, characterized in that it has a removal means for removing the predetermined material formed on the substrate after transferring the pattern of the mold to the imprint material.

[0107] (Configuration 4) An imprint system according to any one of Configurations 1 to 3, characterized in that the predetermined physical property value includes the refractive index or the extinction coefficient.

[0108] (Configuration 5) The imprint system according to any one of Configurations 1 to 4, characterized in that the substrate includes glass.

[0109] (Configuration 6) A substrate used in an imprint system configured to align a substrate-side mark and a mold-side mark when transferring a pattern formed on a mold to an imprint material supplied onto the substrate, characterized in that when creating the substrate-side mark, a predetermined material having a greater difference in predetermined optical properties from the imprint material than the substrate is formed on the surface of the substrate, a desired substrate-side mark is transferred, and the substrate-side mark is formed by processing including the predetermined material.

[0110] (Method 1) An imprint method having an imprint step of transferring a pattern formed in a mold onto an imprint material supplied onto a substrate, A forming step of forming a substrate-side mark containing the predetermined material by first forming a predetermined material on the surface of the substrate in which the difference in predetermined optical properties from the imprint material is greater than that of the substrate, and then transferring and processing a desired substrate-side mark, An imprint method characterized by comprising an alignment step of aligning a mark on the substrate side containing the predetermined material with a mark on the mold side provided on the mold.

[0111] (Method 2) A method for manufacturing a replica mold, comprising: (Method 2) a forming step of forming a first pattern including the predetermined material and the substrate-side mark including the predetermined material on the surface of the replica mold substrate, wherein the difference in predetermined optical properties between the imprint material and the replica mold substrate is greater than that of the replica mold substrate; (Method 3) a forming step of forming a first pattern including the predetermined material and the substrate-side mark including the predetermined material on the replica mold substrate by processing including the predetermined material; (Method 4) a supply step of supplying the imprint material onto the replica mold substrate; and (Method 5) an imprint step of aligning the substrate-side mark including the predetermined material with the mold-side mark provided on the mold and transferring the second pattern formed on the mold to the imprint material on the replica mold substrate.

[0112] (Method 3) A method for manufacturing an article, comprising the steps of forming the pattern on the imprint material using an imprint system described in any one of configurations 1 to 5, and processing the substrate on which the pattern was formed in the first step. [Explanation of Symbols]

[0113] 1: Imprint device 11: Mold 11a: Pattern area 12: Mold holding part 13: Circuit board 14: Board holding part 15: Detection unit 16: Irradiation area 17: Control Unit 18: Mold-side markings 19: Mark on the circuit board side 20: Imprint material 24: Material 25: Material 30: light 31: Observation Department

Claims

1. In an imprint system that transfers a pattern formed in a mold onto an imprint material supplied onto a substrate, Forming means for forming a substrate-side mark containing the predetermined material by first forming a predetermined material on the surface of the substrate in which the difference in predetermined optical properties from the imprint material is greater than that of the substrate, and then transferring and processing a desired substrate-side mark, An imprint system characterized by comprising: an alignment means for optically detecting a substrate-side mark containing the predetermined material covered by the imprint material while the mold is in contact with the imprint material, and for aligning the substrate-side mark containing the predetermined material with a mold-side mark provided on the mold.

2. The imprint system according to claim 1, characterized in that it has a removal means for removing the predetermined material formed on the substrate after transferring the pattern of the mold to the imprint material.

3. The imprint system according to claim 1, characterized in that the predetermined physical property value includes a refractive index or an extinction coefficient.

4. The imprint system according to claim 1, characterized in that the substrate includes glass.

5. An imprint method having an imprint step of transferring a pattern formed in a mold onto an imprint material supplied onto a substrate, A forming step of forming a substrate-side mark containing the predetermined material by first forming a predetermined material on the surface of the substrate in which the difference in predetermined optical properties from the imprint material is greater than that of the substrate, and then transferring and processing a desired substrate-side mark, An imprinting method characterized by comprising: an alignment step of optically detecting the substrate-side mark containing the predetermined material covered by the imprint material while the mold is in contact with the imprint material, and aligning the substrate-side mark containing the predetermined material with the mold-side mark provided on the mold.

6. A forming step is performed to form a predetermined material on the surface of the replica mold substrate, wherein the difference in optical properties between the imprint material and the replica mold substrate is greater than that of the replica mold substrate, then a first pattern and a substrate-side mark are transferred onto the replica mold substrate, and the predetermined material is processed to form the first pattern including the predetermined material and the substrate-side mark including the predetermined material on the replica mold substrate. A supply step of supplying the imprint material onto the replica mold substrate, A method for manufacturing a replica mold, comprising: an imprint step of optically detecting a substrate-side mark containing the predetermined material covered by the imprint material while the mold is in contact with the imprint material; aligning the substrate-side mark containing the predetermined material with a mold-side mark provided on the mold; and transferring a second pattern formed on the mold to the imprint material on the replica mold substrate.

7. A method for manufacturing an article, comprising the steps of: forming the pattern on the imprint material using the imprint system described in any one of claims 1 to 4; and processing the substrate on which the pattern has been formed in the first step.

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