A method of transferring a metal electrode

Abstract

The present application relates to a kind of transfer method of metal electrode, the method includes: depositing metal electrode on polydimethylsiloxane film, metal electrode on polydimethylsiloxane film is adhered and is attached to target substrate using flexible adhesive layer, remove flexible adhesive layer, metal electrode transfer can be completed.Just because the surface energy of polydimethylsiloxane film is low, and adhesion is weak, therefore metal electrode can be completely adhered by flexible adhesive layer, and will not remain on polydimethylsiloxane film, ensure the integrity of metal electrode transfer, improve yield, and because polydimethylsiloxane material is low in price, therefore reduce transfer cost, so as to realize while giving consideration to high yield and low transfer cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor structure preparation, in particular to a transfer method of metal electrode. BACKGROUND

[0002] With the continuous development of semiconductor technology, the integration of integrated circuits is continuously improved, and the device size is continuously miniaturized. Currently, the electrical connection (metal interconnection) in microelectronic devices is usually realized by directly depositing a metal electrode on a target material, such as through an electron beam evaporation deposition process or a magnetron sputtering deposition process. However, due to the chemical sensitivity of some materials, the high-energy process involved in these deposition processes can easily damage the surface and interior of the material, resulting in defects, metal diffusion, layer fracture or strain effect, etc., which reduces the performance of the device. Therefore, the academic community proposes to use a transfer method to construct a metal thin film deposited elsewhere on a target material at low temperature and normal pressure, so as to avoid damage to the target material.

[0003] Although there are some preliminary transfer methods now, these transfer methods have the problems of low yield or high transfer cost, and cannot simultaneously consider high yield and low transfer cost, so they are difficult to be popularized and used. SUMMARY

[0004] The present application provides a transfer method of metal electrode, which can simultaneously consider high yield and low transfer cost.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A transfer method of metal electrode, comprising:

[0007] providing a first substrate, sequentially forming a first thin film and a metal electrode on the first substrate, the first thin film being a polydimethylsiloxane thin film;

[0008] providing a second substrate, forming a flexible adhesive layer on the second substrate;

[0009] peeling the flexible adhesive layer from the second substrate, and adhering the flexible adhesive layer to one side of the first thin film where the metal electrode is placed, so that the flexible adhesive layer covers the metal electrode;

[0010] providing a target substrate, peeling the flexible adhesive layer together with the metal electrode from the first thin film, and adhering one side of the metal electrode to the target substrate, so that the metal electrode forms van der Waals contact with the target substrate;

[0011] removing the flexible adhesive layer, and completing the transfer of the metal electrode.

[0012] Optionally, the forming process of the first thin film comprises:

[0013] preparing a polydimethylsiloxane solution;

[0014] coating the polydimethylsiloxane solution on the first substrate;

[0015] heating at a first preset temperature for a period of time to solidify the polydimethylsiloxane solution coated on the first substrate to form a polydimethylsiloxane film as the first film.

[0016] Optionally, after forming the first film and before forming the metal electrode, the method further comprises:

[0017] tearing the first film from the first substrate and adhering the surface of the first film originally away from the first substrate to the first substrate.

[0018] Optionally, the forming of the metal electrode comprises:

[0019] depositing the metal electrode on the side of the first film away from the first substrate by an electron beam evaporation deposition process or a magnetron sputtering deposition process.

[0020] Optionally, after removing the flexible adhesive layer and completing the transfer of the metal electrode, the method further comprises:

[0021] coating photoresist on the side of the metal electrode away from the target substrate;

[0022] exposing and developing the photoresist by an ultraviolet light beam to make the photoresist have a preset pattern;

[0023] using the photoresist with the preset pattern as a mask to etch the metal electrode to make the metal electrode have the preset pattern;

[0024] removing the photoresist.

[0025] Optionally, the forming of the metal electrode comprises:

[0026] depositing the metal electrode by using a mask with a preset pattern to make the metal electrode have the preset pattern.

[0027] Optionally, the flexible adhesive layer is a polypropylene carbonate film or a polyvinyl alcohol film, and the forming of the flexible adhesive layer comprises:

[0028] preparing a polypropylene carbonate solution or a polyvinyl alcohol solution;

[0029] coating the polypropylene carbonate solution or the polyvinyl alcohol solution on the second substrate;

[0030] heating at a second preset temperature for a period of time to solidify the polypropylene carbonate solution or the polyvinyl alcohol solution coated on the second substrate to form a polypropylene carbonate film or a polyvinyl alcohol film as the flexible adhesive layer.

[0031] Optionally, the flexible adhesive layer is attached to the side of the first film where the metal electrode is placed, so that the flexible adhesive layer covers the metal electrode, comprising:

[0032] applying ethanol and / or water on the side of the metal electrode and the first film away from the first substrate;

[0033] attaching the flexible adhesive layer to the side of the metal electrode and the first film coated with ethanol and / or water, and standing at room temperature for a period of time to utilize the surface tension of ethanol or water to tightly attach the flexible adhesive layer to the first film, clamping the metal electrode;

[0034] heating at a third preset temperature for a period of time to soften the flexible adhesive layer, so that the flexible adhesive layer and the metal electrode are adhered together.

[0035] Optionally, the side of the metal electrode is attached to the target substrate, so that the metal electrode forms van der Waals contact with the target substrate, comprising:

[0036] applying ethanol and / or water on the target substrate;

[0037] attaching the side of the metal electrode to the side of the target substrate coated with ethanol and / or water, and standing at room temperature for a period of time to utilize the surface tension of ethanol or water to make the metal electrode form van der Waals contact with the target substrate;

[0038] heating at a fourth preset temperature for a period of time to soften the flexible adhesive layer, so that the flexible adhesive layer and the target substrate are adhered together, and the metal electrode is more tightly attached to the target substrate.

[0039] Optionally, the flexible adhesive layer is a polypropylene carbonate film, and removing the flexible adhesive layer comprises:

[0040] immersing the target substrate with the metal electrode and the flexible adhesive layer attached thereto in a benzyl ether solution for a period of time to remove the flexible adhesive layer.

[0041] Compared with the prior art, the above technical solutions have the following advantages:

[0042] The embodiment of the present application provides a metal electrode transfer method, first, a first thin film (a polydimethylsiloxane thin film) and a metal electrode are sequentially formed on a first substrate, that is, the metal electrode is directly deposited on the polydimethylsiloxane thin film, a flexible adhesive layer is formed on a second substrate, then the flexible adhesive layer is peeled from the second substrate, and the flexible adhesive layer is attached to one side of the polydimethylsiloxane thin film where the metal electrode is placed, so that the flexible adhesive layer covers the metal electrode, the flexible adhesive layer with the metal electrode is integrally peeled from the polydimethylsiloxane thin film, and then is attached to a target substrate, finally, the flexible adhesive layer is removed, and the transfer of the metal electrode is completed. In this process, due to the characteristics of low surface energy and weak adhesion of the polydimethylsiloxane thin film, the metal electrode can be completely adhered by the flexible adhesive layer and will not be left on the polydimethylsiloxane thin film, so that the integrity of the metal electrode transfer is ensured, the yield is improved, and simultaneously, the transfer cost is reduced due to the low price of the polydimethylsiloxane material, so that the high yield and the low transfer cost are simultaneously considered. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0044] Figure 1 The flowchart of the metal electrode transfer method provided by the embodiment of the present application is shown in the figure.

[0045] Figures 2(a)-2(e) In the metal electrode transfer method provided by the embodiment of the present application, the structure schematic diagram corresponding to each step is shown in the figure.

[0046] Figures 3(a)-3(b) In another metal electrode transfer method provided by the embodiment of the present application, the structure schematic diagram corresponding to each step is shown in the figure.

[0047] Figures 4(a)-4(b) In another metal electrode transfer method provided by the embodiment of the present application, the structure schematic diagram corresponding to each step is shown in the figure.

[0048] Figure 5 In the metal electrode transfer method provided by the embodiment of the present application, the current-voltage curve of the gold electrode deposited on the polydimethylsiloxane thin film and the gold electrode transferred to the silicon wafer is shown in the figure. DETAILED DESCRIPTION

[0049] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0050] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other manners different from those described herein, and a person of ordinary skill in the art can make similar generalizations without departing from the spirit and scope of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0051] Secondly, the present application is described in detail in combination with the schematic diagram, and in the detailed description of the embodiments of the present application, the cross-sectional view of the device structure is locally enlarged without the general proportion for the convenience of description, and the schematic diagram is only an example, which should not limit the scope of protection of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in actual manufacturing.

[0052] As in the background section, the existing metal electrode transfer method has the problems of low yield or high transfer cost, and cannot simultaneously consider high yield and low transfer cost, so it is difficult to be popularized and used.

[0053] The inventors have found that the existing metal electrode transfer method mainly has the following two methods:

[0054] The first method is to first deposit a metal electrode on a silicon substrate or a silicon dioxide substrate, then spin-coat a PMMA (Polymethyl methacrylate) or PVA (Polyvinylalcohol) high polymer material solution on the metal electrode, and after solidification, the metal electrode can be adhered to the PMMA film or PVA film, then the PMMA film with the metal electrode is peeled off or the PVA film with the metal electrode is peeled off, and is attached to a target substrate, and then the PMMA film or PVA film is removed, so as to complete the transfer of the metal electrode.

[0055] For this method, since the adhesion between the silicon substrate or the silicon dioxide substrate and the metal is high, when the metal electrode is peeled off, part of the metal will be left on the silicon substrate or the silicon dioxide substrate, and the complete metal electrode cannot be transferred, thereby affecting the integrity and conductivity of the metal electrode, and further affecting the yield, which is very unfavorable for practical application.

[0056] For this purpose, the silicon substrate or the silicon dioxide substrate can be treated by HMDS (Hexamethyldisilazane) to reduce the adhesion of the silicon substrate or the silicon dioxide substrate to the metal, to improve the yield, but the yield cannot reach 100%, and the transfer process of the metal electrode is complicated and the cost is increased.

[0057] The second method is to first deposit a graphene film on a germanium wafer, then deposit a metal electrode on the graphene film, and then spin-coat PVA on the metal electrode. After solidification, the metal electrode is adhered to the PVA film. The PVA film with the metal electrode is peeled off and attached to the target substrate. Then, the PVA film is removed, and the transfer of the metal electrode is completed.

[0058] In this method, although the adhesion between the graphene film and the metal is extremely low, the complete transfer of the metal electrode can be achieved, but the growth cost of the graphene film is too high.

[0059] As can be seen, the above two methods of transferring the metal electrode are difficult to simultaneously consider high yield and low transfer cost, and therefore are difficult to be widely used.

[0060] Based on the above research, the embodiments of the present application provide a method for transferring a metal electrode to simultaneously consider high yield and low transfer cost.

[0061] The embodiments of the present application provide a method for transferring a metal electrode. First, a first film (a polydimethylsiloxane film) and a metal electrode are formed on a first substrate in sequence, that is, the metal electrode is directly deposited on the polydimethylsiloxane film. A flexible adhesive layer is formed on a second substrate. Then, the flexible adhesive layer is peeled off from the second substrate and attached to one side of the polydimethylsiloxane film on which the metal electrode is placed, so that the flexible adhesive layer covers the metal electrode. The flexible adhesive layer with the metal electrode is peeled off from the polydimethylsiloxane film as a whole and attached to a target substrate. Finally, the flexible adhesive layer is removed, and the transfer of the metal electrode is completed. In this process, due to the characteristics of the low surface energy and weak adhesion of the polydimethylsiloxane film, the metal electrode can be completely adhered by the flexible adhesive layer and will not be left on the polydimethylsiloxane film, which ensures the integrity of the metal electrode transfer and improves the yield. At the same time, since the polydimethylsiloxane material has a low price, the transfer cost is also reduced, so that high yield and low transfer cost are simultaneously considered.

[0062] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0063] Figure 1 A flowchart of a method for transferring a metal electrode provided by the embodiments of the present application is shown in FIG. 1.Figure 1 As shown, the transfer method includes:

[0064] S10: Referring to FIG2(a), a first substrate 1 is provided, and a first thin film 2 and a metal electrode 3 are sequentially formed on the first substrate 1. The first thin film 2 is a polydimethylsiloxane thin film.

[0065] Optionally, the first substrate 1 can be a silicon substrate or a silicon dioxide substrate, such as a glass plate.

[0066] In practical applications, it is usually necessary to first clean the first substrate 1, then form a first thin film 2 on the cleaned first substrate 1, and then form a metal electrode 3 on the side of the first thin film 2 away from the first substrate 1.

[0067] In this method, a polydimethylsiloxane (PDMS) film is used as the first film 2. When the metal electrode 3 is directly deposited on the first film 2, the low surface energy and weak adhesion of the PDMS film result in a weaker adhesion between the metal electrode 3 and the first film 2. Consequently, when the metal electrode 3 is subsequently peeled off, it is less likely to remain on the first film 2, thus improving the yield. At the same time, the PDMS film is relatively inexpensive, thereby reducing the transfer cost of the metal electrode.

[0068] It is understandable that the orthographic projection area of ​​the first thin film 2 on the plane of the first substrate 1 can be greater than the orthographic projection area of ​​the metal electrode 3 on the plane of the first substrate 1. That is, the orthographic projection of the metal electrode 3 on the plane of the first substrate 1 is located within the orthographic projection range of the first thin film 2 on the plane of the first substrate 1, thereby facilitating the deposition of a flat and uniform metal electrode 3 on the first thin film 2.

[0069] In addition, the surface of the first substrate 1 is as smooth and flat as possible in order to form a uniform and flat first thin film 2, and then a uniform and flat metal electrode 3.

[0070] S20: Referring to FIG2(b), a second substrate 4 is provided, and a flexible adhesive layer 5 is formed on the second substrate 4.

[0071] Optionally, the second substrate 4 can be a silicon substrate or a silicon dioxide substrate, such as a silicon wafer.

[0072] It is understandable that the plane where the first substrate 1 is located and the plane where the second substrate 2 is located can be parallel. Therefore, the orthogonal projection area of ​​the flexible adhesive layer 5 on the plane where the second substrate 2 is located (i.e., the plane where the first substrate 1 is located) can be larger than the orthogonal projection area of ​​the metal electrode 3 on the plane where the first substrate 1 is located, so that when the metal electrode 3 is peeled off using the flexible adhesive layer 5, the metal electrode 3 can be easily and completely bonded together.

[0073] S30: Referring to FIG2(c), the flexible adhesive layer 5 is peeled off from the second substrate 4 and the flexible adhesive layer 5 is attached to the side of the first thin film 2 where the metal electrode 3 is placed, so that the flexible adhesive layer 5 covers the metal electrode 3.

[0074] As previously known, the plane containing the first substrate 1 and the plane containing the second substrate 2 can be parallel. The projected area of ​​the flexible adhesive layer 5 on the plane containing the second substrate 2 (i.e., the plane containing the first substrate 1) can be greater than the projected area of ​​the metal electrode 3 on the plane containing the first substrate 1. Therefore, in step S30, when the flexible adhesive layer 5 is attached to the side of the first thin film 2 where the metal electrode 3 is placed, the flexible adhesive layer 5 can not only completely cover the metal electrode 3, but also form direct contact with the first thin film 2. The fact that the flexible adhesive layer 5 completely covers the metal electrode 3 is beneficial for the flexible adhesive layer 5 to completely adhere the metal electrode 3. The direct contact between the flexible adhesive layer 5 and the first thin film 2 is beneficial for the flexible adhesive layer 5 and the metal electrode 3 to be in closer contact, thereby increasing the adhesion between the flexible adhesive layer 5 and the metal electrode 3, and further facilitating the flexible adhesive layer 5 to completely adhere the metal electrode 3.

[0075] S40: Referring to Figure 2(d), a target substrate 6 is provided, the flexible adhesive layer 5 and the metal electrode 3 are peeled off from the first thin film 2, and one side of the metal electrode 3 is attached to the target substrate 6 so that the metal electrode 3 and the target substrate 6 form a van der Waals contact.

[0076] It should be noted that van der Waals contact, also known as intermolecular force, arises from the electrostatic interaction between molecules or atoms. In step S40, the flexible adhesive layer 5, along with the metal electrode 3, is peeled off from the first thin film 2, and one side of the metal electrode 3 is attached to the target substrate 6, so that the metal electrode 3 and the target substrate 6 form a van der Waals contact, so as to facilitate subsequent electrical connection of the metal electrode 3.

[0077] It should also be noted that the target substrate material can be silicon or a two-dimensional material. Among them, two-dimensional materials have shown excellent properties in terms of optics, electricity, magnetism, and heat, and are currently being widely studied, with the potential to become the next generation of semiconductor materials and functional electronic materials.

[0078] S50: Referring to Figure 2(e), remove the flexible adhesive layer 5 to complete the transfer of the metal electrode 3.

[0079] Optionally, the flexible adhesive layer 5 can be directly peeled off, or it can be removed in a corrosive solution, or other methods can be used to remove the flexible adhesive layer 5, thereby completing the transfer of the metal electrode 3. This application does not limit this, and the specific method depends on the circumstances.

[0080] Therefore, the embodiments of this application provide a method for transferring a metal electrode. First, a first thin film 2 (polydimethylsiloxane film) and a metal electrode 3 are sequentially formed on a first substrate 1, that is, the metal electrode 3 is directly deposited on the polydimethylsiloxane film. A flexible adhesive layer 5 is formed on a second substrate 4. Then, the flexible adhesive layer 5 is peeled off from the second substrate 4 and attached to the side of the polydimethylsiloxane film where the metal electrode 3 is placed, so that the flexible adhesive layer 5 covers the metal electrode 3. The flexible adhesive layer 5 and the metal electrode 3 are peeled off from the polydimethylsiloxane film and attached to the target substrate 6. Finally, the flexible adhesive layer 5 is removed, and the transfer of the metal electrode 3 is completed. During this process, due to the low surface energy and weak adhesion of the polydimethylsiloxane film, the metal electrode 3 can be completely adhered to the flexible adhesive layer 5 without leaving any residue on the polydimethylsiloxane film, thus ensuring the integrity of the metal electrode 3 transfer and improving the yield. At the same time, since the polydimethylsiloxane material is inexpensive, the transfer cost is also reduced, thereby achieving both high yield and low transfer cost.

[0081] Optionally, in one embodiment of this application, providing a first substrate 1 in step S10 may include:

[0082] S11: The surface of the first substrate 1 is smoothed and cleaned.

[0083] It is understood that smoothing and cleaning the surface of the first substrate 1 is beneficial for obtaining a high-quality and smooth first thin film 2 on the first substrate 1. This application does not limit the smoothing and cleaning steps; the specific steps shall be determined according to actual needs. For example, when the first substrate 1 is a glass plate, the surface of the glass plate is polished and then cleaned sequentially with acetone, ethanol, and deionized water.

[0084] Optionally, in one embodiment of this application, the formation process of the first thin film 2 in step S10 may include:

[0085] S12: Prepare a polydimethylsiloxane solution;

[0086] S13: Coat the first substrate 1 with a polydimethylsiloxane solution;

[0087] S14: Heating at a first preset temperature for a period of time to solidify the polydimethylsiloxane solution coated on the first substrate 1 to form a polydimethylsiloxane film, which serves as the first film 2.

[0088] In step S12, this application does not limit the proportion of the polydimethylsiloxane solution. Optionally, the polydimethylsiloxane solution may be a polydimethylsiloxane precursor mixture (Dow Corning Sylgard 184, 10:1).

[0089] In step S14, heating at the first preset temperature for a period of time is to accelerate the curing speed of the polydimethylsiloxane solution. This application does not limit the first preset temperature or the heating time at the first preset temperature. Optionally, the first preset temperature can be set to 70°C. For example, heating at 70°C for 1 hour can cure the polydimethylsiloxane solution and form a polydimethylsiloxane film.

[0090] Further optionally, in one embodiment of this application, after forming the first thin film 2 and before forming the metal electrode 3, the method further includes:

[0091] S15: Peel the first film 2 off the first substrate 1 and attach the surface of the first film 2 that was originally away from the first substrate 1 to the first substrate 1.

[0092] It is understandable that after the first thin film 2 is formed on the first substrate 1, the surface of the first thin film 2 that was originally in contact with the first substrate 1 is more uniform and flat than the surface of the first thin film 2 that is away from the first substrate 1. Therefore, in step S15, the first thin film 2 is peeled off from the first substrate 1, and the surface of the first thin film 2 that was originally away from the first substrate 1 is attached to the first substrate 1, so that the metal electrode 3 is deposited on the more uniform and flat surface of the first thin film 2 that was originally in contact with the first substrate 1. This makes the deposited metal electrode 3 more uniform and flat, and thus makes the metal electrode 3 more completely peeled off when it is peeled off from the first thin film 2 using a flexible adhesive layer, reducing the residue of the metal electrode 3 on the first thin film 2 and improving the yield.

[0093] Optionally, in one embodiment of this application, in step S10, after forming the first thin film 2 on the first substrate 1, a metal electrode 3 needs to be formed on the side of the first thin film 2 facing away from the first substrate 1. Specifically, the formation process of the metal electrode 3 includes:

[0094] S16: Deposit a metal electrode 3 on the side of the first thin film 2 away from the first substrate 1 using an electron beam evaporation deposition process or a magnetron sputtering deposition process.

[0095] Optionally, the material of the metal electrode 3 may be gold.

[0096] In practical applications, the metal electrode 3 usually needs to be patterned. Optionally, in one embodiment of this application, after the metal electrode 3 is formed in step S16 and the flexible adhesive layer 5 is removed to complete the transfer of the metal electrode 3, the method further includes:

[0097] S60: Pattern the metal electrode 3.

[0098] Specifically, in step S60, patterning the metal electrode 3 includes:

[0099] S61: Coat the metal electrode 3 on the side facing away from the target substrate 6 with photoresist;

[0100] S62: Use an ultraviolet light beam to expose and develop the photoresist, so that the photoresist has a preset pattern;

[0101] S63: As shown in Figure 3(a), the metal electrode 3 is etched using a photoresist with a preset pattern as a mask 7, so that the metal electrode 3 has a preset pattern.

[0102] S64: Remove the photoresist to obtain a metal electrode 3 with a preset pattern on the target substrate 6, as shown in Figure 3(b).

[0103] In step S63, a solution that corrodes the metal electrode 3 but not the target substrate 6 and the photoresist can be used to etch the metal electrode 3. Optionally, if the material of the metal electrode 3 is gold, potassium iodide and iodine solution can be used to etch the gold to give the gold electrode a preset pattern.

[0104] Optionally, in another embodiment of this application, the metal electrode 3 can also be patterned directly during the formation of the metal electrode 3. Specifically, the formation process of the metal electrode 3 includes:

[0105] S17: As shown in Figure 4(a), a metal electrode 3 is deposited using a mask 8 with a preset pattern, so that the metal electrode 3 has a preset pattern, resulting in Figure 4(b).

[0106] Optionally, in one embodiment of this application, in step S20, the flexible adhesive layer 5 can be a polypropylene carbonate (PPC) film or a polyvinyl alcohol film.

[0107] In this embodiment, the process of forming the flexible adhesive layer 5 may include:

[0108] S21: Prepare polypropylene carbonate solution or polyvinyl alcohol solution;

[0109] S22: Coat the second substrate 4 with a polypropylene carbonate solution or a polyvinyl alcohol solution;

[0110] S23: Heating at a second preset temperature for a period of time to solidify the polypropylene carbonate solution or polyvinyl alcohol solution coated on the second substrate 4 to form a polypropylene carbonate film or polyvinyl alcohol film as a flexible adhesive layer 5.

[0111] In step S21, this application does not limit the mass fraction of the prepared polypropylene carbonate solution or polyvinyl alcohol solution, and can select according to actual needs. Optionally, the mass fraction of the polypropylene carbonate solution can be 10% (the solvent is anisole).

[0112] In step S23, heating at the second preset temperature for a period of time is to accelerate the curing speed of the flexible adhesive layer 5. This application does not limit the second preset temperature or the heating time at the second preset temperature; the specific temperature can be determined according to the material and size of the flexible adhesive layer 5. Optionally, when the flexible adhesive layer 5 is a polypropylene carbonate film, the second preset temperature can be 90°C. For example, heating at 90°C for 30 minutes can solidify the polypropylene carbonate solution to form a polypropylene carbonate film.

[0113] In this application, when polypropylene carbonate film or polyvinyl alcohol film is used as flexible adhesive layer 5, the transfer cost of metal electrode is further reduced because the materials of polypropylene carbonate film and polyvinyl alcohol film are inexpensive.

[0114] Optionally, in one embodiment of this application, in step S30, attaching the flexible adhesive layer 5 to the side of the first thin film 1 where the metal electrode 3 is placed, so that the flexible adhesive layer 5 covers the metal electrode 3, includes:

[0115] S31: Coat the metal electrode 3 and the first thin film 2 on the side facing away from the first substrate 1 with ethanol and / or water;

[0116] S32: The flexible adhesive layer 5 is attached to the metal electrode 3 and the side of the first film 2 coated with ethanol and / or water, and left to stand at room temperature for a period of time to utilize the surface tension of ethanol or water to make the flexible adhesive layer 5 adhere tightly to the first film 2 and clamp the metal electrode 3.

[0117] S33: Heat at a third preset temperature for a period of time to soften the flexible adhesive layer 5, thereby causing the flexible adhesive layer 5 and the metal electrode 3 to adhere together.

[0118] In step S31, the coating with ethanol and / or water can be a mixture of water and ethanol, or just water or ethanol. This application does not limit this, and the coating can be performed according to actual needs. Optionally, ethanol can be coated on the side of the metal electrode 3 and the first thin film 2 facing away from the first substrate 1.

[0119] In step S32, the mixture is left to stand at room temperature for a period of time to utilize the surface tension of ethanol or water, allowing the flexible adhesive layer 5 to adhere tightly to the first film 2 and clamp the metal electrode 3. During the standing process at room temperature, the ethanol and / or water will evaporate. As the amount of ethanol and / or water decreases, the flexible adhesive layer 5 adheres more closely to the first film 2. After the ethanol and / or water have completely evaporated, the flexible adhesive layer 5 adheres tightly to the first film 2, clamping the metal electrode 3. Optionally, when ethanol is used for coating, the mixture can be left to stand at room temperature for 10 minutes.

[0120] In step S33, heating at the third preset temperature for a period of time is intended to soften the flexible adhesive layer 5, thereby allowing the flexible adhesive layer 5 and the metal electrode 3 to adhere together. This application does not limit the third preset temperature or the heating time at that temperature; the specific time can be determined based on the material and size of the flexible adhesive layer 5. However, the overall time should not be too long to prevent excessive softening of the flexible adhesive layer 5, which could lead to deformation. Optionally, when the flexible adhesive layer 5 is a polypropylene carbonate film, the third preset temperature can be 90°C. For example, heating at 90°C for 10 minutes can soften the polypropylene carbonate film.

[0121] Optionally, in one embodiment of this application, in step S40, attaching one side of the metal electrode 3 to the target substrate 6 to form a van der Waals contact between the metal electrode 3 and the target substrate 6 includes:

[0122] S41: Coat the target substrate 6 with ethanol and / or water;

[0123] S42: Attach one side of the metal electrode 3 to the side of the target substrate 6 coated with ethanol and / or water, and let it stand at room temperature for a period of time to utilize the surface tension of ethanol or water to make the metal electrode 3 and the target substrate 6 fit tightly together and complete the van der Waals contact.

[0124] S43: Heating at the fourth preset temperature for a period of time softens the flexible adhesive layer 5, thereby causing the flexible adhesive layer 5 and the target substrate 6 to adhere together, thus making the metal electrode 3 more closely attached to the target substrate 6.

[0125] In step S41, coating with ethanol and / or water can be a mixture of water and ethanol, or just water or ethanol. This application does not limit this; the coating can be performed according to actual needs. Optionally, ethanol can be coated on the target substrate 6.

[0126] In step S42, the substrate is left to stand at room temperature for a period of time to utilize the surface tension of ethanol or water to ensure close contact between the metal electrode 3 and the target substrate 6, thus completing the van der Waals contact. During the standing process at room temperature, the ethanol and / or water will evaporate. As the amount of ethanol and / or water decreases, the metal electrode 3 and the target substrate 6 become increasingly adhered. Once the ethanol and / or water have completely evaporated, the metal electrode 3 and the target substrate 6 are tightly adhered, completing the van der Waals contact. Optionally, when ethanol is used as the coating, the substrate can be left to stand at room temperature for 10 minutes.

[0127] In step S43, heating at the fourth preset temperature for a period of time is intended to soften the flexible adhesive layer 5, thereby allowing the flexible adhesive layer 5 and the target substrate 6 to adhere together, and thus making the metal electrode 3 adhere more tightly to the target substrate 6. This application does not limit the fourth preset temperature or the heating time at the fourth preset temperature; the specific temperature can be determined based on the material and size of the flexible adhesive layer 5. Optionally, when the flexible adhesive layer 5 is a polypropylene carbonate film, the fourth preset temperature can be 90°C. For example, heating at 90°C for 10 minutes can soften the polypropylene carbonate film.

[0128] Optionally, in one embodiment of this application, in step S50, when the flexible adhesive layer 5 is a polypropylene carbonate film, removing the flexible adhesive layer 5 includes:

[0129] The target substrate 6, to which the metal electrode 3 and the flexible adhesive layer 5 are attached, is immersed in anisole solution for a period of time to remove the flexible adhesive layer 5.

[0130] It should be noted that this application does not limit the immersion time of the target substrate 6 with the metal electrode 3 and flexible adhesive layer 5 attached in the anisole solution; specifically, the immersion time is sufficient to completely remove the polypropylene carbonate film. Optionally, the target substrate 6 with the metal electrode 3 and flexible adhesive layer 5 attached can be immersed in the anisole solution for 12 hours to remove the flexible adhesive layer 5.

[0131] In summary, this application provides a method for transferring a metal electrode. The method includes: firstly, forming a first thin film 2 (polydimethylsiloxane film) and a metal electrode 3 sequentially on a first substrate 1, i.e., the metal electrode 3 is directly deposited on the polydimethylsiloxane film, and forming a flexible adhesive layer 5 on a second substrate 4; then peeling the flexible adhesive layer 5 off the second substrate 4 and attaching the flexible adhesive layer 5 to the side of the polydimethylsiloxane film where the metal electrode 3 is placed, so that the flexible adhesive layer 5 covers the metal electrode 3; peeling the flexible adhesive layer 5 and the metal electrode 3 together from the polydimethylsiloxane film and attaching it to the target substrate 6; finally removing the flexible adhesive layer 5 to complete the transfer of the metal electrode 3. During this process, due to the low surface energy and weak adhesion of the polydimethylsiloxane film, the metal electrode 3 can be completely adhered to the flexible adhesive layer 5 without leaving any residue on the polydimethylsiloxane film, thus ensuring the integrity of the metal electrode 3 transfer and improving the yield. At the same time, since the polydimethylsiloxane material is inexpensive, the transfer cost is also reduced, thereby achieving both high yield and low transfer cost.

[0132] To illustrate more specifically how the metal electrode transfer method provided in this application can improve yield, an example is given: by depositing a gold electrode on a polydimethylsiloxane film, using a polypropylene carbonate film to adhere the gold electrode on the polydimethylsiloxane film to a silicon wafer, and then removing the polypropylene carbonate film to complete the transfer of the gold electrode. Figure 5 This is a schematic diagram showing the current-voltage curves of a gold electrode deposited directly on a polydimethylsiloxane film and a gold electrode transferred to a silicon wafer in a metal electrode transfer method provided in this application embodiment. Figure 5 As shown, the resistance of the gold electrode transferred to the silicon wafer is not much different from that of the gold electrode directly deposited on the polydimethylsiloxane film, thus proving that the transferred gold electrode has no cracks and the electrode transfer success rate is close to 100%. Therefore, the metal electrode transfer method provided in this application has a high yield and can meet the requirements of device applications.

[0133] Furthermore, the embodiments of this application can transfer metal electrodes ranging from millimeter to micrometer size, and there are currently no known obstacles to transferring metal electrodes in the nanometer size range. Therefore, the metal electrode transfer method provided in the embodiments of this application is applicable to the transfer of metal electrodes of various sizes.

[0134] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0135] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for transferring a metal electrode, characterized in that, include: A first substrate is provided, on which a first thin film and a metal electrode are sequentially formed. The first thin film is a polydimethylsiloxane thin film. After the first thin film is formed and before the metal electrode is formed, the first thin film is peeled off from the first substrate, and the surface of the first thin film that was originally facing away from the first substrate is attached to the first substrate. A second substrate is provided, on which a flexible adhesive layer is formed, wherein the polydimethylsiloxane film enables the metal electrode to be adhered by the flexible adhesive layer without leaving any residue on the polydimethylsiloxane film; The flexible adhesive layer is peeled off from the second substrate and then attached to the side of the first thin film where the metal electrode is placed, so that the flexible adhesive layer covers the metal electrode. A target substrate is provided, and the flexible adhesive layer, together with the metal electrode, is peeled off from the first film. One side of the metal electrode is then attached to the target substrate, so that the metal electrode and the target substrate form a van der Waals contact. Remove the flexible adhesive layer to complete the transfer of the metal electrode.

2. The method for transferring a metal electrode according to claim 1, characterized in that, The formation process of the first thin film includes: Prepare a polydimethylsiloxane solution; The polydimethylsiloxane solution is coated onto the first substrate; The polydimethylsiloxane solution coated on the first substrate is heated at a first preset temperature for a period of time to solidify and form a polydimethylsiloxane film, which serves as the first film.

3. The method for transferring a metal electrode according to claim 1, characterized in that, The formation process of the metal electrode includes: The metal electrode is deposited on the side of the first thin film away from the first substrate using an electron beam evaporation deposition process or a magnetron sputtering deposition process.

4. The method for transferring a metal electrode according to claim 3, characterized in that, After removing the flexible adhesive layer and completing the transfer of the metal electrode, the method further includes: Photoresist is coated on the side of the metal electrode facing away from the target substrate; The photoresist is exposed and developed using an ultraviolet light beam, so that the photoresist has a preset pattern; Using the photoresist with a preset pattern as a mask, the metal electrode is etched to give the metal electrode the preset pattern; Remove the photoresist.

5. The method for transferring a metal electrode according to claim 1, characterized in that, The formation process of the metal electrode includes: The metal electrode is deposited using a mask with a preset pattern, so that the metal electrode has the preset pattern.

6. The method for transferring a metal electrode according to claim 1, characterized in that, The flexible adhesive layer is a polypropylene carbonate film or a polyvinyl alcohol film, and the formation process of the flexible adhesive layer includes: Prepare polypropylene carbonate solution or polyvinyl alcohol solution; The polypropylene carbonate solution or the polyvinyl alcohol solution is coated onto the second substrate; Heating at a second preset temperature for a period of time causes the polypropylene carbonate solution or the polyvinyl alcohol solution coated on the second substrate to solidify, forming a polypropylene carbonate film or a polyvinyl alcohol film as the flexible adhesive layer.

7. The method for transferring a metal electrode according to claim 1, characterized in that, The flexible adhesive layer is attached to the side of the first thin film where the metal electrode is placed, such that the flexible adhesive layer covers the metal electrode, comprising: Ethanol and / or water are coated on the metal electrode and the side of the first thin film facing away from the first substrate; The flexible adhesive layer is attached to the metal electrode and the side of the first film coated with ethanol and / or water, and left to stand at room temperature for a period of time to utilize the surface tension of ethanol or water to make the flexible adhesive layer adhere tightly to the first film and clamp the metal electrode. Heating at a third preset temperature for a period of time softens the flexible adhesive layer, thereby causing the flexible adhesive layer and the metal electrode to adhere together.

8. The method for transferring a metal electrode according to claim 1, characterized in that, Attaching one side of the metal electrode to the target substrate to form a van der Waals contact between the metal electrode and the target substrate includes: Ethanol and / or water are coated onto the target substrate; One side of the metal electrode is attached to the side of the target substrate coated with ethanol and / or water, and left to stand at room temperature for a period of time to utilize the surface tension of ethanol or water to form a van der Waals contact between the metal electrode and the target substrate. Heating at a fourth preset temperature for a period of time softens the flexible adhesive layer, thereby causing the flexible adhesive layer and the target substrate to adhere together, thus making the metal electrode more closely attached to the target substrate.

9. The method for transferring a metal electrode according to claim 1, characterized in that, The flexible adhesive layer is a polypropylene carbonate film, and removing the flexible adhesive layer includes: The target substrate with the attached metal electrode and the flexible adhesive layer is immersed in anisole solution for a period of time to remove the flexible adhesive layer.

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