Method for forming fine pattern of two-dimensional layered material

Abstract

To provide a pattern forming method for easily forming a fine pattern composed of a two-dimensional layered material with high quality.SOLUTION: The method includes: a step of preparing a negative-positive reversal transfer pattern substrate on which a transfer pattern formed of recesses or voids is engraved; a step of preparing transfer means in which a handling pad is disposed; a step of preparing a nanosheet formed of a two-dimensional layered substance; a step of disposing the nanosheet on the transfer pattern substrate; a nanosheet piece extraction step of attaching a transfer pattern-shaped nanosheet piece to the handling pad and peeling the nanosheet piece; a transfer step of attaching the nanosheet piece onto a to-be processed substrate; and a handling pad separation step of separating the handling pad from the to-be processed substrate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for forming a two-dimensional layer material fine pattern.

Background Art

[0002] A two-dimensional layer material, which is a substance having a layered structure in which atomic layers are bonded by weak van der Waals forces, has unique electronic, optical, and mechanical properties. Therefore, two-dimensional layer materials are substances that have received great attention in fields such as solar cells, lithium-ion batteries, field-effect transistors, and gas sensors. Furthermore, two-dimensional layer materials processed into a pattern shape are highly expected to open the way for applications to, for example, photonic devices having a metamaterial structure and two-dimensional network structures.

[0003] Two-dimensional layer materials can be supplied in the form of nanosheets. As methods for patterning the nanosheets to form fine patterns, there are (1) a processing method by focused ion beam irradiation, (2) a processing method by femtosecond laser, (3) a processing method of cutting the nanosheet along the crystal axis, and (4) a processing method by lithography and dry etching. However, these methods have the problems shown below, and the development of a new method for easily forming a submicron-sized fine pattern made of a two-dimensional layer material with high quality has been eagerly awaited.

[0004] The processing method by focused ion beam irradiation is a method of irradiating a nanosheet with a high-density focused helium ion beam or gallium beam and cutting the nanosheet by sputtering phenomenon or sublimation of atoms due to heat generated by irradiation, as disclosed in Non-Patent Documents 1 and 2. The problem of this method is that the substrate is also processed at the same time, and fusion with the substrate occurs, and melting, defects, atomic movement, and deformation of the nanosheet due to heat generation occur around the cutting edge.

[0005] The processing method using a femtosecond laser is a method of focusing and scanning a high-intensity femtosecond laser to sublime and cut the atoms constituting the nanosheet. This method has problems such as restrictions on spatial resolution due to optical limitations caused by the wavelength of the laser light, melting due to heat generation, and the generation of defects.

[0006] The processing method of cutting the nanosheet along the crystal axis is a method of placing the oxide nanosheet dispersed in a solvent on a substrate with protrusions and cutting it along the crystal axis of the nanosheet, which is disclosed in Patent Document 1. This method has a problem that it can only cut along the axial direction of the crystal, and it is difficult to form a pattern with a free shape.

[0007] The processing method using lithography and dry etching is the most common processing method, but there is a problem that it is easy to damage and contaminate the substrate, which is the object to be processed, during resist removal and dry etching.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0009]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] The problem to be solved by the present invention is to provide a method for simply and with high quality forming a submicron-sized fine pattern made of a two-dimensional layer material, in which the above problems of the conventional method are avoided.

Means for Solving the Problem

[0011] The configuration of the present invention for solving the problem is shown below. (Configuration 1) A method for forming a fine pattern made of a two-dimensional layer material, comprising: a transfer pattern substrate preparation step of preparing a negative-positive inversion transfer pattern substrate on which a transfer pattern having the shape of the fine pattern to be formed, which is composed of a concave portion or a void, is formed in a portion corresponding to the fine pattern to be formed; a transfer means preparation step of preparing transfer means having a handling pad for transfer; a nanosheet preparation step of preparing a nanosheet made of the two-dimensional layer material; a nanosheet placement step of placing the nanosheet on the transfer pattern substrate; a nanosheet piece extraction step of bringing the handling pad into contact with the nanosheet, and partially attaching and peeling off a nanosheet piece having the shape of the transfer pattern from the nanosheet placed on the transfer pattern substrate to the handling pad; a transfer step of bringing the nanosheet piece attached to the handling pad into contact with a workpiece substrate and then attaching the nanosheet piece to the workpiece substrate; A method for forming a fine pattern of a two-dimensional layer material, comprising a handling pad separation step of separating the handling pad from the workpiece substrate. (Configuration 2) The handling pad is made of a material whose adhesive force changes with temperature. The transfer step consists of bringing the nanosheet piece adhered to the handling pad into contact with the substrate to be processed, and then changing the temperature of the handling pad to weaken the adhesion of the nanosheet piece to the handling pad, thereby adhering the nanosheet piece onto the substrate to be processed. The method for forming a two-dimensional layer material fine pattern according to Configuration 1. (Configuration 3) At least the surface of the handling pad is made of a polymer. The method for forming a two-dimensional layer material fine pattern according to Configuration 1 or 2. (Configuration 4) The temperature is a temperature near the softening temperature of the polymer. The method for forming a two-dimensional layer material fine pattern according to Configuration 3. (Configuration 5) The handling pad has a structure in which a polydimethylsiloxane (PDMS) film and a polypropylene carbonate (PPC) film are sequentially formed. The method for forming a two-dimensional layer material fine pattern according to Configuration 1 or 2. (Configuration 6) The handling pad includes a thermal release tape. The method for forming a two-dimensional layer material fine pattern according to Configuration 1 or 2. (Configuration 7) The two-dimensional layer material is bonded between layers by van der Waals forces. The method for forming a two-dimensional layer material fine pattern according to any one of Configurations 1 to 6. (Configuration 8) The two-dimensional layer material consists of one selected from the group consisting of graphene, transition metal dichalcogenide (TMDC), oxide, and nitride. The method for forming a two-dimensional layer material fine pattern according to any one of Configurations 1 to 7. (Configuration 9) The transition metal dichalcogenide consists of one selected from the group consisting of ZrSe2, TaSe2, TaS2, NbSe2, WSe2, MoTe2, MoSe2, MoS2, GaSe, GaS, SnSe2, and SnS2. The method for forming a two-dimensional layer material fine pattern according to Configuration 8. (Configuration 10) The thickness of the nanosheet is 1 atomic layer or more and 200 nm or less. The fine pattern forming method according to any one of Configurations 1 to 9. (Configuration 11) The method for forming a two-dimensional layer material fine pattern according to any one of Configurations 1 to 10, wherein the width of the minimum part of the formed fine pattern is 0.1 μm or more and 10 μm or less.

Advantages of the Invention

[0012] According to the present invention, there is provided a method for simply forming a submicron-sized fine pattern made of a two-dimensional layer material with high quality.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

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Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0014] Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. Note that A to B in the text indicates A or more and B or less.

[0015] In the method for forming a two-dimensional layer material fine pattern of the present invention, a so-called negative-positive inversion type transfer pattern substrate 31 in which the shape of the fine pattern to be formed is formed as a concave or / and hole-shaped (void) 33 in the substrate 32 is prepared (Fig. 1(a)). A nanosheet 61 made of a two-dimensional layer material to be patterned is placed on the prepared transfer pattern substrate 31 (Fig. 1(b)). A nanosheet piece 62 having the shape of the fine pattern to be formed is transferred onto the substrate 52 to be processed using a transfer means such as a stamp or a thermal release tape (Fig. 1(c)), and a sample 51 having a fine pattern of the two-dimensional layer material formed thereon is obtained. Here, in Fig. 1(b), the void 33 formed in the transfer pattern substrate 31 under the nanosheet 61 is shown by a broken line. In addition, in Fig. 1, the case where the transfer pattern substrate 31 forms a void 33 in the substrate 32 to form a corresponding pattern portion to be formed is shown, but it may be concave (dug-in shape) instead of the void 33. Regarding the stamp technique, for example, it is disclosed in Patent Document 2.

[0016] The key points of the method of the present invention are that the transfer is performed using the negative-positive inversion type transfer pattern substrate 31 and that the pattern to be formed is made of a two-dimensional layer material. Since the portion corresponding to the pattern formation is in a concave or / and hole-shaped 33, the nanosheet 61 made of the two-dimensional layer material formed on the corresponding portion is held in a floating state without touching the substrate 32. When transfer is performed in this state using a stamp or a thermal release tape, the pattern piece to be transferred is attracted to the transfer handling pad such as a stamp by a very weak force (van der Waals force) and adheres to the handling pad. Therefore, the pattern piece to be transferred is hardly damaged. On the other hand, in stamp transfer using a normal positive-type transfer pattern substrate, since the handling pad is pressed against the transfer pattern, the two-dimensional layer material is likely to be damaged. In addition, since the force acting between atomic layers in the two-dimensional layer material is the weak van der Waals force, when a pattern piece of the formed pattern shape is drawn to the handling pad and taken out from the nanosheet 61 made of the two-dimensional layer material disposed on the transfer pattern substrate 31 for transfer, it can be peeled off as a pattern piece along the contour of the transfer pattern formed on the transfer pattern substrate 31. From the above, by the method of the present invention, it becomes possible to easily form a fine pattern made of a two-dimensional layer material with high quality. It has been experimentally confirmed that the size of the pattern transfer of the method of the present invention is particularly suitable for micron to submicron.

[0017] The details of the measurement method procedure will be described below with reference to FIG. 2 which is a flowchart diagram and FIG. 3 which is a process conceptual diagram.

[0018] First, as a transfer pattern substrate preparation step, a negative-positive inverted transfer pattern substrate having a transfer pattern of the formed fine pattern shape formed of a concave portion or a void is prepared in the portion corresponding to the formed fine pattern (FIG. 2, step S11).

[0019] The transfer pattern substrate is roughly classified into a through-hole type transfer pattern substrate 31 in which a void (hole) 33 is formed in a substrate 32 shown in FIG. 4(a) which is a cross-sectional view, and a recess type (dug type) transfer pattern substrate 31' in which a recess 37 is formed in a substrate 36 shown in FIG. 4(b). When the through-hole type transfer pattern substrate 31 is used, the pattern along the void 33 is transferred, and when the recess type transfer pattern substrate 31' is used, the pattern along the recess 37 is transferred. The surfaces 34 and 38 of the substrates 32 and 36 each become a field portion.

[0020] The through-hole type transfer pattern substrate 31 has the characteristics that pattern inspection is easy, and when a nanosheet made of a two-dimensional layer material is disposed on the transfer pattern substrate 31 in a later process, the pattern portion does not contact the substrate 32 even if the nanosheet is bent, and defects are less likely to occur. On the other hand, the recessed type transfer pattern substrate 31' has the feature that it can transfer a hollowed-out type pattern. That is, for example, the donut-shaped pattern 61a shown in Fig. 5(a) can be transferred and formed using the transfer pattern substrate 31' shown in Figs. 5(b) and 5(c). Note that Fig. 5(b) is a plan view, and Fig. 5(c) is a cross-sectional view showing the cross-section when cut along the line connecting A and A' in Fig. 5(b).

[0021] Examples of the materials of the substrates 32 and 36 include synthetic quartz, glass, silicon, silicon nitride, silicon oxide, ceramics such as SiC, metals such as tungsten, and plastics. In the pattern portion, that is, the width W of the minimum portion of the void 33 in the through-hole type transfer pattern substrate 31 and the recess 37 in the recessed type transfer pattern substrate 31' is preferably 0.1 μm or more and 10 μm or less. In the subsequent nano-sheet piece extraction step (step S15), when the width W of the minimum portion is less than 0.1 μm, it is difficult to extract a nano-sheet piece with a desired shape. When the minimum width exceeds 10 μm, the nano-sheet arranged in the pattern portion is likely to be bent, making it difficult to extract a nano-sheet piece with a desired shape.

[0022] Second, as a transfer means preparation step, prepare a transfer means with a handling pad for transfer arranged on the surface. For example, when using the stamp technique as the transfer means, prepare a stamp including a transfer handling chip 18 with a transfer handling pad 42 arranged on the surface 46 (steps S12, Fig. 6(a)). The transfer handling chip 18 is composed of a substrate 41 and a handling pad 42. The substrate 41 is preferably a transparent substrate in order to accurately and efficiently perform alignment during stamp transfer.

[0023] Here, the handling pad for transfer preferably consists of a material whose adhesive force changes with temperature. In the method of the present invention, as described later, there are steps of attaching the nanosheet pieces to the handling pad side and to the substrate to be processed side. However, when the nanosheet pieces are detached while controlling the adhesive force by temperature control using a handling pad for transfer made of a material whose adhesive force changes with temperature, defects in the nanosheet pieces can be reduced, the detachment accuracy can be improved, and the detachment failure rate can be significantly lowered.

[0024] Also, the transfer means is not limited to a stamp. For example, a thermal release tape can also be used. The thermal release tape refers to a tape whose adhesive force changes with temperature, and a tape with a change range of the adhesive force suitable for detaching the nanosheet pieces is used. Specifically, Repar Alpha (manufactured by Nitto) can be cited as the thermal release tape.

[0025] As the material of at least the surface of the handling pad, a polymer can be preferably used. The reason for this is that the polymer is less likely to damage the nanosheet pieces when they are attached and the adhesive force changes greatly near the softening temperature. Here, as the polymer, silicone-based polymers such as polydimethylsiloxane (PDMS) and polypropylene carbonate (PPC) can be preferably used.

[0026] Here, the index of softening is the temperature at which the surface begins to dissolve. In the case of silicone-based rubber (thermal decomposition or thermal melting temperature 160°C to 250°C) mainly composed of silicone-based polymers such as PDMS and PPC, 50 to 90°C is used. After the pad is brought into contact with the nanosheet pieces and held for several minutes, peeling is performed.

[0027] As shown in FIG. 6(a), the handling pad may be a handling pad 42 composed of a single layer, or as shown in FIG. 6(b), a handling pad 45 composed of a laminated film. The number of laminated layers may be two or more. As a handling chip 18' for transfer using the two-layer film handling pad 45, an example shown in FIG. 6(b) where the handling pad 45 includes a two-layer film composed of polydimethylsiloxane (PDMS) (43) and polypropylene carbonate (PPC) (44) can be cited. In this case, both cushioning properties and adhesion are excellent, enabling high-quality stamp transfer. As the shape of the handling pad, it is preferable that the first main surface is flat. The edge portion of the handling pad may be rounded or have an acute angle.

[0028] Thirdly, as a nanosheet preparation step, a nanosheet made of a two-dimensional layered material is prepared (step S13). Here, as the two-dimensional layered material used for the nanosheet, any material can be preferably used as long as the layers are bonded by van der Waals forces. Specific examples of the two-dimensional layered material include one selected from the group consisting of graphene, transition metal dichalcogenide (TMDC), oxide, and nitride. Here, as the transition metal dichalcogenide, one selected from the group consisting of ZrSe2, TaSe2, TaS2, NbSe2, WSe2, MoTe2, MoSe2, MoS2, GaSe, GaS, SnSe2, and SnS2 can be cited. Since the force acting between atomic layers of these materials is the weak van der Waals force, pattern pieces can be taken out with high precision (pattern shape accuracy) during the nanosheet extraction step (step S15). The thickness of the nanosheet is preferably 1 atomic layer or more and 200 nm or less. If it is less than 1 atomic layer, it is porous and brittle, and defects are likely to occur. If it exceeds 200 nm, it becomes difficult to take out pattern pieces with high precision during the nanosheet extraction step (step S15).

[0029] Fourth, as the nano-sheet placement step, the nano-sheet 61 is placed on the transfer pattern substrate 31 (substrate 32) (step S14, Fig. 3(a)).

[0030] Fifth, as the nano-sheet piece extraction step, the handling pad 45 is brought into contact with the nano-sheet 61 (Fig. 3(b)), and a nano-sheet piece 62 having the transfer pattern shape is partially attached to and peeled off from the nano-sheet 61 placed on the transfer pattern substrate 31 onto the handling pad 45 (step S15). Specifically, the handling pad 45 is moved upward to peel off the nano-sheet piece 62 (Fig. 3(c)). At this time, a nano-sheet residue 63 remains on the substrate 32.

[0031] Here, the configuration of the stamper device 101 will be described with reference to Fig. 7. The stamper device 101 of the present embodiment includes a temperature adjustment means 12 and a mounting substrate 13, a mounting table (stage) 14 for mounting the transfer pattern substrate 31 and / or the sample 51, a position moving means 15 for moving the mounting table 14, an arm 17 having a transfer handling chip 18, a position moving means 19 for moving the arm 17, an image observing means 20 for observing the sample 51 via the transfer handling chip 18 and the arm 17, and a control means 21 for inputting image information from the image observing means 20 and changing the relative positions of the mounting table 14 and the arm 17 using the position moving means 15 and the position moving means 19 to perform transfer control and temperature control by the temperature adjustment means 12. Here, the position movement of the mounting table 14 may be performed by connecting the position moving means 15 and the mounting table 14 via a rod 16, or by placing the position moving means 15 on the mounting table 14. Also, either one of the position moving means 15 and the position moving means 19 may be used to simplify the device. Further, the position moving means 15 may be specialized for horizontal (XY) and rotational (θ) movement, and the position moving means 19 may be specialized for vertical (Z) movement. The transfer handling chip 18 is preferably transparent to the light used for the image observation means 20 so that the sample 11 can be observed by the image observation means 20. When the arm 17 also blocks the field of view when observing the sample 11 with the image observation means 20, it is preferably transparent to the light used for the image observation means 20.

[0032] The temperature adjustment range by the temperature adjustment means 12 is, for example, 0°C or higher and 150°C or lower. When the handling pad 45 is made of a polymer, it is preferable to control the temperature in the range from room temperature to near the temperature at which the polymer starts to soften to desorb the nanosheet pieces. Here, the vicinity refers to the range of 50 to 90°C. When in this temperature range, the desorption of the nanosheet pieces 62 from the handling pad 45 and the desorption onto the substrate to be processed 52 are stabilized, and desorption is possible with an appropriate adhesion force, so that the damage to the two-dimensional layer material is also reduced.

[0033] Sixthly, as a transfer step, the substrate to be processed 52 is arranged so that the substrate to be processed 52 comes under the handling pad 45. When there is alignment, after adjusting the positions of the handling pad 45 and the substrate to be processed 52 (Fig. 3(d)), the nanosheet pieces 62 attached to the handling pad 45 are brought into contact with the substrate to be processed 52, and the nanosheet pieces are attached to the substrate to be processed 52 (step S16, Fig. 3(e)). Here, preferably, the temperature of the handling pad 45 is changed to weaken the adhesion force of the nanosheet pieces 62 to the handling pad 45 to perform step S16. When a polymer is used as the handling pad, it is from 50°C to 90°C.

[0034] Seventhly, as a handling pad separation step, the handling pad 45 is separated from the substrate to be processed 52, and a nanosheet piece 62 (a pattern of a desired shape made of a two-dimensional layer material) is formed on the substrate to be processed 52 (step S17, Fig. 3(f)).

[0035] According to this method, by means of stamp transfer or the like using a negative-positive inversion type transfer substrate in which the pattern forming portion is a void or a recess, a two-dimensional substance can be easily cut along the pattern, and a desired pattern composed of a two-dimensional layer-like substance including thin films such as 1 to 3 layers can be produced without damage to the two-dimensional layer-like substance. The method of the present invention hardly suffers from lattice defects or deformation of the edge portion associated with heat generation as described in the background, can cut nanosheets at an arbitrary angle, and can form a pattern of a desired shape.

[0036] The pattern of the two-dimensional layer-like substance has the potential to be applied to the formation of photonic devices having a metamaterial structure or a two-dimensional network structure. According to the present invention, for example, it is possible to apply to a novel two-dimensional device in which nano-micro sized heterostructures are locally arranged with respect to a photonic device formed by patterning and arranging two-dimensional layer-like substances having a metamaterial effect on light having a wavelength from sub-micrometer to micrometer, and a two-dimensional device made of a uniform material.

Example

[0037] Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are only given here to assist in the understanding of the present invention, and the present invention is not limited thereto.

[0038] In the example, an example will be described in which graphene having a thickness of 2 atomic layers is used as the two-dimensional layer material, and a circular two-dimensional layer pattern having a diameter of about 3 μm is formed on a silicon substrate having a silicon oxide film formed on the surface.

[0039] First, as a step of preparing a transfer pattern substrate (FIG. 2, step S11), a transfer pattern substrate 31 in which holes having a diameter of 3 μm are arranged in a staggered manner on a substrate 32 made of silicon nitride (SiN x ) with a thickness of 0.2 μm was prepared (FIG. 4(a), FIG. 9(a)).

[0040] Second, as a step of preparing transfer means (step S12), a stamp device 101 shown in FIG. 8 was prepared. The stamping device 101 includes a mounting table (stage) composed of a temperature adjustment means 12 for mounting a sample 51 for pattern formation and a mounting substrate 13, a position movement means 15 and a rod 16 for moving the mounting table, an arm 17 provided with a transfer handling chip 18', a position movement means 19 for moving the arm 17, and an image observation means 20 for observing the sample through the transfer handling chip 18' and the arm 17. Here, when taking out the nanosheet piece, a transfer substrate on which the nanosheet is placed is placed on the mounting table instead of the sample 51.

[0041] The mounting table is provided with a θ rotation and XYZ movement mechanism (position movement means 15, etc.), and its height can be controlled by an electric motor (Z coupler and focus controller MSS-FC, Central Precision Industry, Japan) with a step resolution of 0.2 μm. The temperature of the mounting table can be adjusted to a desired value from room temperature to 150°C by the temperature adjustment means 12. As the arm 17, a slide glass is used, and a micromanipulator (Thorlab Inc., USA) for fixing the slide glass is arranged near the mounting table. A transfer handling chip 18' is attached to the tip of the slide glass. Here, when observing the sample 51 using the image observation means 20, it can be observed only through the transfer handling chip 18' without passing through the slide glass which is the arm 17. The image observation means 20 consists of microscopes of 5× and 20× having two types of objective lenses. A halogen lamp is used for the observation light. The NA of the lenses is 0.15 and 0.45 respectively.

[0042] As shown in Fig. 6(b), the handling chip 18' for transfer has a handling pad 45 on a transparent substrate 41 composed of a slide glass and a PDMS-based gel film polymer sheet, on which a polymer composed of a PDMS film 43 and a PPC film 44 is disposed. Here, the PDMS film 43 is a spin-coated film, and its surface is treated with O2 plasma by reactive ion etching (RIE), and its surface roughness is about 19 nm in RMS. The PPC film 44 is also a spin-coated film. The PPC film 44 is a film whose adhesion changes greatly near its glass transition temperature.

[0043] Thirdly, as the nanosheet preparation step (step S13), a nanosheet (graphene sheet, manufactured by NORCADA (USA)) composed of graphene with a thickness of 2 atomic layers was prepared. Here, the size of the graphene sheet is 0.5 mm × 0.5 mm. Fourthly, as the nanosheet placement step (step S14), after preparing the nanosheet, the graphene sheet 61 was placed on the transfer pattern substrate 31 (substrate 32) (Fig. 3(a)).

[0044] Fifthly, as the nanosheet piece extraction step (step S15), the handling pad 45 was brought into contact with the graphene sheet 61 to extract a circular nanosheet piece 62 with a diameter of about 3 μm. Specifically, the handling pad 45 was brought into contact with the graphene sheet 61, and the transfer pattern substrate 31 was heated to 81 °C by the temperature adjustment means 12 and held for about 5 minutes (Fig. 3(b), Fig. 9(b)). Then, using the position moving means 19, the transfer handling chip 18' was slowly moved upward to separate the handling pad 45 from the surface of the transfer pattern substrate 31. At this time, the graphene sheet located at the position of the hole in the substrate was cut to become the nanosheet piece 62, and the nanosheet piece 62 moved to the surface 46 of the handling pad 45 (Fig. 3(c)).

[0045] Sixthly, as the transfer step (step S16), first, a silicon substrate 52 having a silicon oxide layer formed on the first main surface with a thickness of 90 nm was prepared, and the lateral positions of the silicon substrate 52 and the handling pad 45 were adjusted using the position moving means 15 and 19 so as to be at predetermined positions (FIG. 3(d)). Subsequently, the handling pad 45 was brought into contact with the silicon substrate 52, and the temperature of the silicon substrate 52 was set to 81° C. by the temperature adjusting means 12 and held for about 5 minutes (FIG. 3(e)).

[0046] Seventhly, as the handling pad separation step (step S17), the handling pad 45 was slowly moved upward (at about 5 mm / min) using the position moving means 19 to separate the handling pad 45 from the silicon substrate 52, and the circular nano-sheet piece 62 was transferred onto the silicon substrate 52 having the silicon oxide layer formed on its surface (FIG. 3(f)). When the surface of the silicon substrate 52 was observed with an optical microscope (manufactured by Olympus), it was confirmed that graphene disks with a diameter of about 3 μm were arranged (FIG. 9(c)). Further, when this disk was observed with an atomic force microscope (Dimension Icon Brucker), flat graphene disks were observed (FIG. 9(d)). From the above, it was demonstrated that a micron-sized fine pattern made of graphene, which is a two-dimensional layered material, can be easily transferred with a simple device.

Industrial Applicability

[0047] According to the present invention, a sub-micron-sized fine pattern made of a two-dimensional layered material, which has a wide range of physical properties as a metal, semiconductor, and superconductor and is expected to be variously utilized as a functional material, can be formed simply and with high quality. Therefore, the present invention is utilized as a technology to support high-performance devices and is expected to greatly contribute to the development of the industry.

Explanation of Reference Numerals

[0048] 12: Temperature adjusting means 13: Mounting substrate 14: Mounting table (stage) 15: Position moving means 16: Rod 17: Arm 18: Transfer handling chip 18′: Transfer handling chip 19: Position moving means 20: Image observation means 21: Control means 31: Transfer pattern substrate 31´: Transfer pattern substrate 32: Substrate 33: Gap, hole (transfer pattern part) 34: Field part 36: Substrate 37: Concave part (transfer pattern part) 38: Field part 41: Substrate, transparent substrate 42: Handling pad 43: PDMS film 44: PPC film 45: Handling pad 46: Surface 51: Sample 52: Substrate to be processed, substrate 61: Nanoplate, graphene sheet 62: Nanoplate piece 63: Nanoplate residue 61a: Pattern to be formed, transfer pattern 101: Transfer device (stamp)

Claims

1. A method for forming a fine pattern made of a two-dimensional layer material, comprising: A transfer pattern substrate preparation step of preparing a transfer pattern substrate with a negative-positive inversion transfer pattern in which a transfer pattern having the shape of the fine pattern to be formed, which is a concave portion or a void, is formed in a portion corresponding to the fine pattern to be formed; A transfer means preparation step of preparing a transfer means having a handling pad for transfer; A nanosheet preparation step of preparing a nanosheet made of the two-dimensional layer material; A nanosheet placement step of placing the nanosheet on the transfer pattern substrate; A nanosheet piece extraction step of bringing the handling pad into contact with the nanosheet, and partially attaching and peeling off a nanosheet piece having the transfer pattern shape from the nanosheet placed on the transfer pattern substrate to the handling pad; A transfer step of bringing the nanosheet piece attached to the handling pad into contact with a substrate to be processed, and then attaching the nanosheet piece to the substrate to be processed; A two-dimensional layer material fine pattern forming method, comprising a handling pad separation step of separating the handling pad from the substrate to be processed.

2. The handling pad is made of a material whose adhesion force changes with temperature, The transfer step is: after bringing the nanosheet piece attached to the handling pad into contact with a substrate to be processed, changing the temperature of the handling pad to weaken the adhesion force of the nanosheet piece to the handling pad, and attaching the nanosheet piece to the substrate to be processed. The two-dimensional layer material fine pattern forming method according to Claim 1.

3. The two-dimensional layer material fine pattern forming method according to Claim 1 or 2, wherein at least the surface of the handling pad is made of a polymer.

4. The two-dimensional layer material fine pattern forming method according to Claim 3, wherein the temperature is a temperature near the softening temperature of the polymer.

5. The two-dimensional layer material fine pattern forming method according to Claim 1 or 2, wherein the handling pad has a structure in which a polydimethylsiloxane (PDMS) film and a polypropylene carbonate (PPC) film are sequentially formed.

6. The two-dimensional layer material fine pattern forming method according to Claim 1 or 2, wherein the handling pad includes a thermal release tape.

7. The method for forming a two-dimensional layer material fine pattern according to any one of claims 1 to 6, wherein the two-dimensional layer material is bonded between layers by van der Waals forces.

8. The method for forming a two-dimensional layer material fine pattern according to any one of claims 1 to 7, wherein the two-dimensional layer material consists of one selected from the group consisting of graphene, transition metal dichalcogenide (TMDC), oxide, and nitride.

9. The transition metal chalcogenide is ZrSe ２ , TaSe ２ , TaS ２ , NbSe ２ , WSe ２ , MoTe ２ , MoSe ２ , MoS ２ , GaSe, GaS, SnSe ２ and SnS ２ The method for forming a two-dimensional layer material fine pattern according to claim 8, which consists of one selected from the group consisting of

10. The method for forming a fine pattern according to any one of claims 1 to 9, wherein the thickness of the nanosheet is 1 atomic layer or more and 200 nm or less.

11. The method for forming a two-dimensional layer material fine pattern according to any one of claims 1 to 10, wherein the width of the minimum part of the fine pattern to be formed is 0.1 μm or more and 10 μm or less.

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