Method for manufacturing a free standing membrane and method for forming a electroplating layer using a free standing membrane

Abstract

A method for manufacturing a free-standing membrane may include a membrane transfer step and a grain growth step. In the membrane transfer step, a free-standing region overlapping with the through-hole on a plane may be provided on the membrane by transferring the membrane onto a first substrate provided with a through-hole. In the grain growth step, the grain size of the free-standing region may be increased.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a free-standing membrane, and more specifically, to a method for manufacturing a free-standing membrane having a free-standing region that is not directly supported by a substrate, and a method for forming an electroplated layer using a free-standing membrane. Background Technology

[0002] Functional membranes are widely used in various fields, such as water purification, low-energy desalination, high-permeability selectivity gas separation, cell co-culture, and pellicles for EUV lithography (extreme ultraviolet lithography). In particular, ultra-thin membranes with nano-scale thickness are highly valuable as they can be applied to high-value-added industries such as bio and semiconductors due to their fast liquid diffusion rates and optical transparency.

[0003] Conventionally, semiconductor or MEMS (micro-electromechanical systems) process technologies have been primarily utilized for the fabrication of ultrathin membranes.

[0004] For example, it was possible to form an ultrathin membrane layer with a nano-scale thickness on a substrate by utilizing technologies such as PVD (physical vapor deposition), CVD (chemical vapor deposition), electroplating, SOG (spin-on glass), and ALD (atomic layer deposition).

[0005] In addition, after forming an ultrathin membrane layer, a portion of the substrate supporting the ultrathin membrane layer was etched through a chemical etching process, thereby enabling the fabrication of a free-standing membrane having a free-standing region that is not directly supported by the substrate.

[0006] However, such conventional technologies had disadvantages, including high product manufacturing and environmental treatment costs, and long production times, as they were equipment-intensive and involved chemical etching processes.

[0007] Furthermore, because the chemical etching process causes chemical or mechanical defects or tensile or compressive residual stress in the ultrathin membrane layer, the layer can easily break; consequently, it has been difficult to fabricate very thin ultrathin membranes using conventional technology. For example, wrinkles may form in the free-standing region of the membrane, and the free-standing region, for example, 1 cm 2 It had the limitation of being able to be produced only within a very small area. The problem to be solved

[0008] An embodiment of the present invention provides a method for manufacturing a free-standing membrane having a free-standing region not directly supported by a substrate, and a method for forming an electroplated layer using the free-standing membrane. means of solving the problem

[0009] A method for producing a free-standing membrane according to one aspect of the present invention may include a membrane transfer step and a grain growth step.

[0010] In the above membrane transfer step, by transferring the membrane onto a first substrate provided with a through hole, a free-standing area overlapping with the through hole on a plane can be provided on the membrane.

[0011] In the grain growth stage above, the grain size of the free-standing area can be increased.

[0012] According to one embodiment of the present invention, in the membrane transfer step, the membrane may be transferred onto the first substrate to cover the through hole.

[0013] According to one embodiment of the present invention, after the membrane transfer step, the membrane may be provided with the free-standing region and a substrate support region that overlaps with the first substrate on a plane.

[0014] According to one embodiment of the present invention, the grain growth step may include a heat treatment process of heating and then cooling the membrane.

[0015] According to one embodiment of the present invention, the grain size of the free-standing region can be increased by the heat treatment process and the grains of the free-standing region can be aligned in a predetermined direction.

[0016] According to one embodiment of the present invention, the method for manufacturing a free-standing membrane may further include a substrate preparation step and a preliminary transfer step.

[0017] In the above substrate preparation step, a second substrate on which the membrane is disposed on one side can be prepared.

[0018] In the above preliminary transfer step, the second substrate can be pushed into the liquid to transfer the membrane onto the surface of the liquid.

[0019] In the above membrane transfer step, the membrane transferred on the surface of the liquid can be scooped up by the first substrate and transferred onto the first substrate.

[0020] According to one embodiment of the present invention, the method for manufacturing a free-standing membrane may further include a drying step.

[0021] In the drying step above, the liquid remaining on the membrane after the membrane transfer step and before the heat treatment process can be removed by evaporation.

[0022] According to one embodiment of the present invention, wrinkles in the free-standing region can be smoothed out by the heat treatment process.

[0023] A method for forming an electroplated layer using a free-standing membrane according to another aspect of the present invention may include a membrane transfer step, a grain growth step, and an electroplating step.

[0024] In the above membrane transfer step, by transferring the membrane onto a first substrate provided with a through hole, a free-standing area overlapping with the through hole on a plane can be provided on the membrane.

[0025] In the grain growth stage above, the grain size of the free-standing area can be increased by a heat treatment process.

[0026] In the above electroplating step, an electroplated layer can be formed on the free-standing area after the above heat treatment process.

[0027] According to one embodiment of the present invention, the grains of the electroplating layer may be aligned in substantially the same direction as the grains of the free-standing area. Effects of the invention

[0028] According to an embodiment of the present invention, compared to conventional technology, there are advantages such as lower manufacturing costs, the omission of the chemical etching process resulting in no environmental treatment costs, and shorter product manufacturing time.

[0029] In addition, an ultrathin membrane with a nano-scale thickness can be fabricated to provide a free-standing area with a very large size compared to conventional ones, for example, a diameter of 10 cm or more.

[0030] In addition, as the grain size of the free-standing region increases, the electrical resistance of the membrane can also be lowered.

[0031] In addition, defects or wrinkles that may occur during conventional membrane layer formation and etching processes can be suppressed or eliminated.

[0032] In addition, the mechanical strength of the membrane is improved, so that a functional layer may be formed on a free-standing region using the membrane as a base substrate through spin coating, electroplating, sputtering, etc.

[0033] In particular, as the grains in the free-standing region grow and are aligned in a predetermined direction through a heat treatment process, when an electroplating layer is formed on the free-standing region, the grains constituting the electroplating layer, i.e., the metal crystals, can also be formed in a large size and aligned in a predetermined direction, and as a result, the electrical resistance of the electroplating layer is lowered and the corrosion resistance is improved, and an electroplating layer in which the crystals are aligned in a predetermined direction, such as single-crystal copper, can be obtained. Brief explanation of the drawing

[0034] FIG. 1 is a flowchart of a method for manufacturing a freestanding membrane according to an embodiment of the present invention, and FIG. 2 is a drawing illustrating a second substrate having a membrane disposed on one surface, and FIG. 3 is a modified example of FIG. 2, and FIG. 4 is a diagram illustrating the preliminary transfer step of the membrane illustrated in FIG. 2, and FIG. 5 is a diagram illustrating the preliminary transfer step of the membrane illustrated in FIG. 3, and FIGS. 6 and 7 are drawings for explaining a membrane transfer step for a membrane transferred onto the surface of a liquid, and FIG. 8 is a modified example of the first substrate shown in FIG. 6, and FIG. 9 is another variation of the first substrate shown in FIG. 6, and FIGS. 10 to 12 are drawings for explaining the grain growth mechanism in the grain growth stage, and FIG. 13 is a diagram illustrating the effect of improving wrinkles in a membrane according to a heat treatment process, and FIG. 14 is a flowchart of a method for forming an electroplated layer using a freestanding membrane according to an embodiment of the present invention, and FIG. 15 is a drawing for explaining the electroplating step of FIG. 14, and FIG. 16 is a drawing illustrating a first substrate having an electroplated layer formed on a membrane by electroplating, and Figure 17 is a cross-sectional view taken along I-I of Figure 16. Specific details for implementing the invention

[0035] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0036] The attached drawings are not drawn to the actual scale to aid in understanding the invention, and the dimensions of some components may be exaggerated.

[0037] Terms used in the specification and claims of the present invention should not be limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0038] In this specification, the singular form shall be deemed to include the plural form unless otherwise specifically stated.

[0039] In addition, if it is stated that a part "includes" a certain component, it means that the part may include additional components.

[0040] In addition, when a component is described as "up," it refers to the area above or below the component, and does not necessarily mean that it is located on the upper side relative to the direction of gravity.

[0041] In addition, where it is stated that a component is "attached" to another component, this may include not only cases where the component is directly attached to the other component, but also cases where the component is indirectly attached through yet another component.

[0042] In addition, terms such as "first," "second," etc., may be used to describe a component; however, these terms are intended merely to distinguish the component from other components and are not intended to limit the essence, order, or sequence of the component.

[0043] In an embodiment of the present invention, first to third directions (DR1 to DR3) may be defined. The first direction (DR1) may be a direction parallel to one surface of the first substrate (SUB1). The second direction (DR2) may be a direction intersecting the first direction (DR1) and parallel to one surface of the first substrate (SUB1). The third direction (DR3) may be a direction perpendicular to one surface of the first substrate (SUB1). In an embodiment of the present invention, the expression “on a plane” may mean a view from the third direction (DR3).

[0044] FIG. 1 is a flowchart of a method for manufacturing a freestanding membrane according to one embodiment of the present invention.

[0045] Referring to FIG. 1, a method for manufacturing a free-standing membrane according to one embodiment of the present invention may include a substrate preparation step (S100), a preliminary transfer step (S200), a membrane transfer step (S300), a drying step (S400), and a grain growth step (S500). However, it is not necessarily limited thereto, and some of the steps described above may be omitted.

[0046] FIG. 2 is a drawing showing a second substrate with a membrane disposed on one surface, and FIG. 3 is a modified example of FIG. 2.

[0047] Referring to FIG. 2, a membrane (M) can be formed on one side of the second substrate (SUB2) (S100).

[0048] For example, a sacrificial layer (SL) may be placed between the second substrate (SUB2) and the membrane (M).

[0049] The second substrate (SUB2) can be used to transfer the membrane (M) onto the surface of the liquid.

[0050] The second substrate (SUB2) can be manufactured with a sufficient thickness to prevent the membrane (M) from being smoothly separated from the second substrate (SUB2) or deformed when the second substrate (SUB2) with the membrane (M) attached is pushed into a liquid and the second substrate (SUB2) fails to overcome the surface tension of the liquid and excessive bending deformation occurs.

[0051] In the experimental example of the present invention, a silicon substrate was used as the second substrate (SUB2), but it is not necessarily limited thereto, and the second substrate (SUB2) may be made of metal or plastic, etc.

[0052] The sacrificial layer (SL) can be dissolved in the liquid when the second substrate (SUB2) is pushed into the liquid, causing the membrane (M) to be separated from the second substrate (SUB2) and transferred onto the surface of the liquid.

[0053] The sacrificial layer (SL) may include a material that can be well dissolved in the liquid, for example, a polymer material, a metal, or a ceramic.

[0054] For example, the sacrificial layer (SL) may include at least one of a polymer material, such as PSS (polystyrene sulfonate) or PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate).

[0055] In this case, the liquid may be a deionized water-based solvent in which the polymer material can be well dissolved.

[0056] However, it is not necessarily limited to this, and aqueous solutions or alcohol-based solvents may also be used.

[0057] Such a polymer sacrificial layer can be formed by applying a coating solution onto a second substrate (SUB2). The application of the coating solution can be performed by spin coating, but is not necessarily limited thereto; depending on the concentration, drop casting, blade coating, etc., may also be utilized.

[0058] As another example, the sacrificial layer (SL) may include a metal or ceramic. In this case, the liquid may be an acidic aqueous solution in which the metal, etc. can be well dissolved. For example, the liquid may be prepared using ammonium persulfate or, in some cases, strong acids such as hydrogen chloride (HCl) or sulfuric acid.

[0059] Such a metal or ceramic sacrificial layer can be formed on a second substrate (SUB2) using technologies used in semiconductor processes, such as PVD (physical vapor deposition), CVD (chemical vapor deposition), electroplating, and SOG (spin-on glass) technology.

[0060] The membrane (M) can be formed by depositing or coating a metallic material, for example, gold (Au), silver (Ag), or copper (Cu), on a sacrificial layer (SL). However, it is not necessarily limited to this, and the membrane (M) may be formed from other types of metals, ceramics, or polymer materials.

[0061] The membrane (M) may be an ultrathin membrane having a thickness in the nanometer range. For example, the thickness of the membrane (M) may be 30 nm to 200 nm.

[0062] Referring to FIG. 3, the membrane (M) may be formed directly on the second substrate (SUB2) without a sacrificial layer.

[0063] The sacrificial layer may be omitted, as in the present variation example, if the membrane (M) can be smoothly separated from the second substrate (SUB2) without the sacrificial layer and transferred onto the surface of the liquid when the second substrate (SUB2) is pushed into the liquid.

[0064] In this modified example, the second substrate (SUB2) may be a silicon substrate, and the membrane (M) may be formed by depositing or applying gold (Au) on the second substrate (SUB2).

[0065] FIG. 4 is a diagram illustrating the preliminary transfer step of the membrane shown in FIG. 2, and FIG. 5 is a diagram illustrating the preliminary transfer step of the membrane shown in FIG. 3.

[0066] Referring to FIGS. 4 and 5, a second substrate (SUB2) with a membrane (M) attached can be pushed into a liquid (L) to separate the membrane (M) from the second substrate (SUB2) and transfer it onto the surface of the liquid (L) (S200).

[0067] For example, the second substrate (SUB2) can be pushed in at an angle to the surface of the liquid (L).

[0068] As a result, the separation and transfer of the membrane (M) can proceed from the bottom of the membrane (M) to the top.

[0069] When the membrane (M) is transferred onto the surface of the liquid (L), it can be in a free-standing state that is not directly supported by the substrate as shown in the drawing.

[0070] The liquid (L) may include one of a deionized water-based solvent, an aqueous solution, an alcohol-based solvent, or an acidic aqueous solution as described above, but is not necessarily limited thereto.

[0071] FIGS. 6 and 7 are drawings for explaining the membrane transfer step for a membrane transferred onto the surface of a liquid, FIG. 8 is a modified example of the first substrate shown in FIG. 6, and FIG. 9 is another modified example of the first substrate shown in FIG. 6.

[0072] Referring to FIGS. 6 and 7, a free-standing region (A1) can be provided on the membrane (M) by transferring the membrane (M) onto a first substrate (SUB1) provided with a through hole (TH) (S300).

[0073] According to an embodiment of the present invention, a membrane (M) that is freely supported on the surface of the liquid (L) can be transferred onto the first substrate (SUB1) by lowering the first substrate (SUB1) into the liquid (L) and then slowly lifting it in a direction perpendicular to the surface of the liquid (L). That is, the membrane (M) that is freely supported on the surface of the liquid (L) can be scooped up by the first substrate (SUB1) and transferred onto the first substrate (SUB1).

[0074] At this time, a transfer device (not shown) for transferring the first substrate (SUB1) in the up and down direction may be used.

[0075] The first substrate (SUB1) may be in an upright state so as to extend in a direction perpendicular to the surface of the liquid (L) during the membrane transfer step.

[0076] As a result, the membrane (M) can be transferred onto the first substrate (SUB1), which is a perforated substrate, without damage.

[0077] The first substrate (SUB1) can be manufactured with a sufficient thickness to prevent excessive bending deformation caused by the surface tension of the liquid (L), which would prevent smooth transfer of the membrane (M) to the first substrate (SUB1), or it can be manufactured with a material having a high elastic modulus.

[0078] In the experimental example of the present invention, a thin sheet with well-controlled surface roughness, for example, a nickel thin sheet with a thickness of 500 μm, was used as the first substrate (SUB1).

[0079] However, it is not necessarily limited to this, and the first substrate (SUB1) may be a silicon substrate used in semiconductor processes, etc., or may be made of a metal such as copper or plastic.

[0080] A through hole (TH) may be formed in the first substrate (SUB1) that penetrates one side of the first substrate (SUB1) and the other side opposite to the one side.

[0081] Through holes (TH) can be formed by various processing methods. For example, processing methods such as laser processing, water jet processing, milling, turning, and chemical etching may be used.

[0082] Meanwhile, in an embodiment of the present invention, the membrane (M) is described as being transferred onto the surface of the liquid (L) before being transferred onto the first substrate (SUB1), but is not necessarily limited thereto.

[0083] A membrane (M) transferred onto a first substrate (SUB1) may be provided with a free-standing region (A1) and a substrate support region (A2).

[0084] The free-standing area (A1) may be an area that overlaps with the through hole (TH) of the first substrate (SUB1) on a plane.

[0085] That is, the membrane (M) may be provided with a free-standing region (A1) that is not directly supported by the first substrate (SUB1).

[0086] According to an experimental example of the present invention, it was confirmed that a free-standing region (A1) can be formed up to a diameter of 10 cm without damage to a membrane (M) with a thickness of 30 nm to 200 nm.

[0087] The substrate support area (A2) may be an area that overlaps with one side of the first substrate (SUB1) on a plane.

[0088] The substrate support area (A2) may not overlap in plane with the through hole (TH) provided in the first substrate (SUB1).

[0089] The substrate support area (A2) can be positioned to surround the free-standing area (A1) on a plane.

[0090] For example, the membrane (M) can be transferred onto the first substrate (SUB1) to cover the through hole (TH) of the first substrate (SUB1) during the membrane transfer step.

[0091] The membrane (M) can be attached to the first substrate (SUB1) by the van der Waals force acting between the first substrate (SUB1) and the membrane (M) in the substrate support area (A2).

[0092] Referring to FIGS. 8 and 9, the size of the first substrate (SUB1), the number and shape of the through holes (TH) provided in the first substrate (SUB1), etc., can be designed in various ways without limitation.

[0093] Meanwhile, when the liquid (L) on the surface of the membrane (M) is transferred onto the first substrate (SUB1), some of the liquid (L) may remain on the membrane (M) or the first substrate (SUB1), and such remaining liquid (L) may rapidly vaporize during the heat treatment process described later, thereby damaging the membrane (M). Accordingly, a drying process needs to be performed before the heat treatment process (S400).

[0094] In an experimental example of the present invention, the process time could be shortened by placing the first substrate (SUB1) on which the membrane (M) has been transferred onto a hot plate or placing it in an oven and heating it to a second temperature, for example, about 50°C, which is lower than the first temperature of the heat treatment process.

[0095] Meanwhile, when the membrane (M) is transferred onto the first substrate (SUB1) from the surface of the liquid (L), it can be attached to the inner surface of the first substrate (SUB1) that partitions the through hole (TH) due to the surface tension of the remaining liquid (L), and when the remaining liquid (L) vaporizes according to the drying process, it separates from the inner surface of the first substrate (SUB1), and wrinkles may occur in the free-standing area (A1).

[0096] Next, in the grain growth stage (S500), the grain size in the free-standing region (A1) of the membrane (M) can be increased.

[0097] The grain growth step (S500) may include a heat treatment process of heating and then cooling the membrane (M).

[0098] The heat treatment process may be carried out using a hot plate, an oven, a furnace, or electric row heating.

[0099] Meanwhile, although the embodiment of the present invention describes growing grains by a heat treatment process, it is not necessarily limited thereto, and various alternative processes capable of growing the grain size of the free-standing region (A1) may be applied.

[0100] FIGS. 10 to 12 are drawings for explaining the grain growth mechanism in the grain growth stage.

[0101] FIGS. 10 to 12 respectively show a plan view of a first substrate (SUB1) with a membrane (M) attached and a cross-sectional view of the membrane (M) in a free-standing area (A1), and for ease of understanding, the boundaries of the grains constituting the membrane (M) are also shown.

[0102] In the experimental examples illustrated in FIGS. 10 to 12, a silicon substrate was used as the first substrate (SUB1).

[0103] Referring to FIG. 10, it can be seen that the grain size of the membrane (M) transferred onto the first substrate (SUB1) is very small before undergoing the grain growth step (S500), for example, the heat treatment process.

[0104] Referring to FIGS. 11 and 12, the first substrate (SUB1) to which the membrane (M) is attached may undergo a heat treatment process.

[0105] In an experimental example of the present invention, a silicon substrate with a gold thin film attached was heated from room temperature (RT) to a first temperature, for example, about 250°C, and then slowly cooled to room temperature.

[0106] Figure 11 shows the state heated to a first temperature, and Figure 12 shows the state cooled to room temperature.

[0107] After such a heat treatment process, it can be seen that the grain size of the membrane (M) increases in the free-standing area (A1).

[0108] As a result, the electrical resistance of the membrane (M) decreased by about 25% before and after the heat treatment process.

[0109] In addition, it was also confirmed that the grains of the membrane (M) in the free-standing area (A1) after the heat treatment process were aligned in a predetermined direction, for example, in the 111 direction.

[0110] Meanwhile, in a comparative experiment example in which a membrane (M) with a free-standing region (A1) is heat-treated as in the embodiment of the present invention, it was confirmed that the effect of increasing grain size was insignificant, and that the grains disappeared completely when the temperature exceeded a certain level.

[0111] Specifically, a comparative experiment example was conducted using a silicon substrate without through-holes, rather than a perforated substrate.

[0112] As a result, it was confirmed that the membrane attached to the entire surface of a silicon substrate without through holes did not peel off even when the heating temperature was only about 300°C, and when the temperature was about 400°C to 500°C, it was completely divided into silicon and the grains disappeared.

[0113] Figure 13 is a diagram illustrating the effect of improving wrinkles in a membrane according to a heat treatment process.

[0114] Referring to FIG. 13, wrinkles may occur in the free-standing area (A1) as in the first image during the process of transferring the membrane (M) onto the first substrate (SUB1), and wrinkles may occur as in the second image as described above during the drying step (S400).

[0115] However, during the heat treatment process for grain growth, it can be seen that the wrinkles in the free-standing region (A1) are flattened out as shown in the third image.

[0116] When the wrinkles are flattened in this way, the membrane (M) can become much stronger compared to before.

[0117] That is, the mechanical strength of the membrane (M) can be improved.

[0118] As a result, it is possible to form a functional layer by spin coating, electroplating, sputtering, etc. on the free-standing region (A1) of the membrane (M) using the membrane (M) as a base substrate.

[0119] FIG. 14 is a flowchart of a method for forming an electroplated layer using a free-standing membrane according to an embodiment of the present invention, and FIG. 15 is a diagram for explaining the electroplating step of FIG. 14.

[0120] Referring to FIG. 14, a method for forming an electroplated layer using a free-standing membrane according to one embodiment of the present invention may include a substrate preparation step (S100), a preliminary transfer step (S200), a membrane transfer step (S300), a drying step (S400), a grain growth step (S500), and an electroplating step (S600). However, it is not necessarily limited thereto, and some of the steps described above may be omitted.

[0121] In the method for forming an electroplated layer according to an embodiment of the present invention, the substrate preparation step (S100), preliminary transfer step (S200), membrane transfer step (S300), drying step (S400), and grain growth step (S500) may be substantially the same as the substrate preparation step (S100), preliminary transfer step (S200), membrane transfer step (S300), drying step (S400), and grain growth step (S500) of the method for manufacturing a free-standing membrane described in relation to FIGS. 1 to 13, so a detailed description thereof is omitted.

[0122] In the electroplating step (S600), an electroplated layer can be formed on the free-standing area (A1) after the heat treatment process.

[0123] In an experimental example of the present invention, a first substrate (SUB1) with a membrane (M) attached and a copper substrate (CS) were placed in a solution, and electroplating was performed by applying voltage.

[0124] As a result, an electroplated layer containing copper can be formed on the membrane (M).

[0125] However, it is not necessarily limited to this, and electroplating may also be performed using a conductive substrate containing a conductive material other than a copper substrate.

[0126] FIG. 16 is a drawing showing a first substrate having an electroplated layer formed on a membrane by electroplating, and FIG. 17 is a cross-sectional view taken along I-I of FIG. 16.

[0127] Referring to FIGS. 16 and 17, a membrane (M) transferred onto a first substrate (SUB1) provided with a through hole (TH) may have a free-standing region (A1) and a substrate support region (A2) defined therein.

[0128] The free-standing area (A1) may be an area that overlaps with the through hole (TH) of the first substrate (SUB1) on a plane.

[0129] The substrate support area (A2) may be an area that overlaps with one side of the first substrate (SUB1) on a plane.

[0130] The substrate support area (A2) may not overlap in plane with the through hole (TH) provided in the first substrate (SUB1).

[0131] The electroplated layer (EPL) is a layer formed by electroplating and can be placed on the membrane (M).

[0132] The electroplating layer (EPL) can cover the free-standing area (A1) and the substrate support area (A2).

[0133] Grains in the free-standing region (A1) of the membrane (M) can be aligned in a predetermined direction while growing through the aforementioned heat treatment process. Therefore, when an electroplating layer (EPL) is formed on the membrane (M) that has undergone such a grain growth process, the grains constituting the electroplating layer (EPL), i.e., metal crystals, can be formed in a large size and can be aligned in a predetermined direction, for example, substantially the same direction as the alignment direction of the grains in the free-standing region (A1) of the membrane (M), and as a result, an electroplating layer (EPL) with low electrical resistance and excellent corrosion resistance, and in which crystals are aligned in a predetermined direction, such as single-crystal copper, can be obtained.

[0134] The electroplating layer (EPL) may include copper, but is not necessarily limited thereto, and may include other conductive materials, such as gold or silver.

[0135] Although the present invention has been described above with reference to preferred embodiments, this is merely illustrative and does not limit the invention. A person skilled in the art may modify and change the embodiments in various ways by adding, changing, deleting, or adding components without departing from the technical spirit of the invention as described in the claims, and such modifications and changes are also to be considered to be included within the scope of the rights of the present invention. Explanation of the symbols

[0136] SUB1: 1st substrate TH: Penetrating hole A1: Free Standing Area A2: Substrate support area SUB2: Second Substrate M: Membrane SL: Sacrifice Layer L: Liquid CS: Copper substrate EPL: Electroplated layer

Claims

Claim 1 A method for producing a freestanding membrane, comprising: a membrane transfer step of transferring a membrane onto a first substrate provided with a through hole to provide a freestanding region on the membrane that overlaps with the through hole on a plane; and a grain growth step of increasing the grain size of the membrane located in the freestanding region by a heat treatment process of heating and then cooling the membrane while the freestanding region is provided. Claim 2 A method for manufacturing a free-standing membrane according to claim 1, wherein in the membrane transfer step, the membrane is transferred onto the first substrate to cover the through hole. Claim 3 A method for manufacturing a free-standing membrane according to claim 1, wherein after the membrane transfer step, the membrane is provided with the free-standing region and a substrate support region that overlaps with the first substrate in a plane. Claim 4 delete Claim 5 A method for manufacturing a free-standing membrane according to claim 1, wherein the grain size of the membrane located in the free-standing region is increased by the heat treatment process and the grains of the membrane located in the free-standing region are aligned in a predetermined direction. Claim 6 A method for manufacturing a free-standing membrane according to claim 1, further comprising: a substrate preparation step of preparing a second substrate on which the membrane is disposed on one surface; and a preliminary transfer step of pushing the second substrate into a liquid to transfer the membrane onto the surface of the liquid, wherein in the membrane transfer step, the membrane transferred onto the surface of the liquid is scooped up by the first substrate and transferred. Claim 7 A method for manufacturing a freestanding membrane according to claim 6, further comprising a drying step for removing the liquid remaining on the membrane after the membrane transfer step and before the heat treatment process by evaporating it. Claim 8 A method for manufacturing a free-standing membrane in which the wrinkles of the free-standing region are flattened by the heat treatment process according to claim 6. Claim 9 A method for forming an electroplated layer using a free-standing membrane, comprising: a membrane transfer step of providing a free-standing region on the membrane that overlaps with the through-hole on a plane by transferring the membrane onto a first substrate provided with a through-hole; a grain growth step of increasing the grain size of the membrane located in the free-standing region by a heat treatment process of heating and then cooling the membrane while the free-standing region is provided; and an electroplating step of forming an electroplated layer on the free-standing region after the heat treatment process. Claim 10 In claim 9, a method for forming an electroplated layer using a free-standing membrane in which the grains of the electroplated layer are aligned in the same direction as the grains of the membrane located in the free-standing region.

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