High-density stretchable array device based on three-dimensional metal electrode and preparation method thereof
By designing three-dimensional metal electrodes and combining multiple technologies, the problem of high-density integration caused by the excessive area occupied by electrodes in existing devices has been solved. This has enabled the three-dimensional arrangement of flexible electrodes and high-density chip integration, which is applicable to fields such as biomedicine.
Patent Information
- Application Number
- CN202511418508.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-02-13
AI Technical Summary
Existing stretchable devices are difficult to integrate at high density because the electrodes parallel to the chip array plane occupy too much area, resulting in a small number of chips and making it difficult to achieve high-density integration.
By adopting a three-dimensional metal electrode design, the electrodes are changed from being parallel to the chip array plane to being perpendicular to the circuit plane. Combined with photomask with compensation structure, isotropic etching technology and secondary structure modification technology, three-dimensional metal electrodes are formed through electroforming process to achieve three-dimensional arrangement of flexible electrodes.
It significantly improves the integration of devices, reduces the footprint of stretchable electrodes, and achieves high-density chip integration, making it particularly suitable for complex surface bonding applications in fields such as biomedicine.
Smart Images
Figure CN121531871A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of flexible electronics technology, and particularly relates to a high-density stretchable array device based on three-dimensional metal electrodes and its fabrication method. Background Technology
[0002] Flexible and stretchable array devices, due to their flexibility and stretchability, offer better surface adhesion to complex surfaces than traditional rigid circuits, demonstrating broad research value and application potential in fields such as biomedicine. Existing devices primarily utilize materials such as PDMS and Ecoflex00-30 platinum-catalyzed silicone rubber as flexible substrates, combining stretchable electrodes to give the devices stable stretchability. Current stretchable devices mainly employ flexible materials such as irregularly shaped metals, elastomers doped with conductive particles, or liquid metals as stretchable electrodes. Among these, irregularly shaped metal electrodes, made by fabricating rigid metals into specially designed shapes, possess certain stretching characteristics. Compared to the latter two types of electrodes, they maintain a relatively stable electrical state during stretching, have lower device packaging requirements, and have more mature processes. However, because the electrodes need to be designed into stretchable patterns, they occupy a larger area, resulting in a smaller number of chips per unit area, making it difficult to achieve high-density chip integration, thus limiting the application of the devices. Summary of the Invention
[0003] In view of this, the present invention aims to provide a high-density stretchable array device based on three-dimensional metal electrodes and its fabrication method. The electrodes are designed in a direction perpendicular to the plane of the chip array, transforming the traditional electrodes parallel to the chip array plane into stretchable electrodes perpendicular to the circuit plane. This allows more flexible electrodes and circuit chips to be arranged within a unit area of the chip array plane, effectively reducing the volume and improving the device integration. It also avoids the problem of complex-shaped electrodes parallel to the chip array plane occupying too much device area, solving the problem that existing solutions are difficult to fabricate three-dimensional stretchable electrodes.
[0004] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes, comprising: S1: Based on the design parameters of the chip array, a mask layer is prepared on the surface of the silicon wafer, the silicon wafer is etched to leave flexible electrode holes on the surface of the silicon wafer, and then the mask layer is removed. S2: An electroforming seed layer is prepared on the silicon wafer surface after step S1, and photolithography is performed on the photoresist coated on the electroforming seed layer; after the photolithography operation, electroforming is performed at the location of the flexible electrode hole on the electroforming seed layer to form a three-dimensional metal electrode. S3: Fix the chip array at the position of the three-dimensional metal electrode made in step S2, and use a flexible polymer to cover the surface where the chip array and the three-dimensional metal electrode are located in the current structure to form a top encapsulation layer; S4: Separate the silicon wafer from the structure obtained in step S3 and lead out the connection lines of the driver chip array; in this structure, a flexible polymer is coated on the opposite side of the top encapsulation layer as the bottom encapsulation layer.
[0005] Furthermore, step S1 includes: S11: Determine the structural parameters of the silicon wafer based on the design parameters of the chip array, and prepare a mask layer on the surface of the silicon wafer; S12: Design and utilize a photomask with a compensation structure to perform photolithography and etching on the mask layer of step S11 to pattern the mask layer; remove the photoresist to expose the periodically arranged mask pattern. S13: Use HNA mixed solution to perform isotropic etching on silicon wafers, leaving a series of flexible electrode holes at the corresponding positions of the mask pattern on the silicon wafer; S14: Remove the mask layer using a wet etching process or a dry etching process.
[0006] Furthermore, step S1 also includes: S15: The silicon wafer from which the mask layer was removed in step S14 isotropically etched again to smooth the edges of the flexible electrode holes.
[0007] Furthermore, step S2 includes: S21: Apply PMMA solution to the side of the silicon wafer with the flexible electrode hole and heat to cure it to form a PMMA film; S22: The surface of the PMMA film obtained in step S21 is sprayed with PAA solution, and the PAA solution is imidized by stepwise heating to form a PI film; S23: Copper film is deposited on the PI film in step S22 by magnetron sputtering to form an electroforming seed layer; S24: Coat the electroforming seed layer formed in step S23 with a thick film of photoresist and perform photolithography to expose the electrode area to be electroformed. The thickness of the remaining photoresist structure is greater than the thickness of the designed electrode. S25: Based on the flexible electrode hole, a three-dimensional metal electrode is formed at the position to be electroformed on the electroforming seed layer after photolithography by electroforming process. S26: The photoresist is removed using a photoresist remover corresponding to the photoresist, and the electroforming seed layer covered by the photoresist is removed by wet etching, while retaining the three-dimensional metal electrode.
[0008] Furthermore, in step S24, laser direct writing technology is used to perform a real-time focused irradiation direct writing operation on the photoresist on the surface of the electroformed seed layer.
[0009] Furthermore, step S3 includes: S31: Place the chip array on the solder pad area coated with solder, heat the solder to melt it, and solder the chip array to the solder pad of the three-dimensional metal electrode. S32: Cover the surface of the chip array and three-dimensional metal electrodes in the structure obtained in step S31 with a flexible polymer film, and wait for the flexible polymer film to cure to form a top encapsulation layer.
[0010] Furthermore, step S4 includes: S41: Peel the composite structure containing three-dimensional metal electrodes, chip array and top packaging layer from the silicon wafer from one side of the PI film; S42: The PI film is etched away using a dry etching process to expose the three-dimensional metal electrode; S43: Clean the exposed 3D metal electrode with dilute hydrochloric acid and lead out the connection wire from the pad of the 3D metal electrode. S44: A flexible polymer is used to form the bottom encapsulation layer, thus completing the bottom encapsulation of the stretchable array device.
[0011] A high-density stretchable array device based on three-dimensional metal electrodes is prepared using the fabrication method of the high-density stretchable array device based on three-dimensional metal electrodes provided by the present invention.
[0012] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The high-density stretchable array device of three-dimensional metal electrodes and its preparation method created by the present invention transforms the stretchable electrode from the traditional pattern design in the circuit plane to a three-dimensional electrode perpendicular to the circuit plane, which greatly reduces the area occupied by the stretchable electrode and can significantly improve the integration of the chip in the circuit, thereby solving the problem of fabrication of three-dimensional stretchable electrodes. (2) The fabrication method of the high-density stretchable array device of three-dimensional metal electrodes described in this invention combines photomask design with compensation structure, isotropic etching technology of silicon with secondary structure modification technology, three-dimensional structure electroforming technology, and substrate peeling technology of flexible stretchable structure. By adding a specially designed compensation structure, the size and shape of the flexible electrode that meets the design requirements can be achieved. The silicon wafer with the mask layer removed is subjected to maskless secondary isotropic etching again to achieve smooth modification of the structure. At the same time, PMMA film is used as a sacrificial layer, and the complete peeling of the stretchable structure and on-chip structure protection can be achieved through sacrificial layer technology and other processes. This invention solves the problem that existing solutions are difficult to fabricate three-dimensional stretchable electrodes through the above-mentioned fabrication method. Attached Figure Description
[0013] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A flowchart illustrating the fabrication method of a high-density stretchable array device based on three-dimensional metal electrodes as described in the embodiments of the present invention; Figure 2 A schematic flowchart illustrating the fabrication method of a high-density stretchable array device based on three-dimensional metal electrodes according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the high-density stretchable array device based on three-dimensional metal electrodes as described in an embodiment of the present invention.
[0014] Explanation of reference numerals in the attached figures: 1. Silicon wafer; 2. Mask layer; 3. Flexible electrode aperture; 4. Mask pattern; 5. Electroformed seed layer; 6. Three-dimensional metal electrode; 7. PMMA thin film; 8. PI thin film; 9. Photoresist; 10. LED light-emitting unit; 11. Top encapsulation layer; 12. Bottom encapsulation layer; 13. Connecting wire. Detailed Implementation
[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.
[0016] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.
[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0019] The invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0020] like Figures 1 to 2 As shown in the embodiment of the present invention, the method for fabricating a high-density stretchable array device of three-dimensional metal electrodes includes: S1: According to the design parameters of the chip array, a mask layer 2 is prepared on the surface of silicon wafer 1, and silicon wafer 1 is etched to leave flexible electrode holes 3 on the surface of silicon wafer 1. Then the mask layer 2 is removed.
[0021] In some embodiments, step S1 includes: S11: Determine the structural parameters of silicon wafer 1 according to the design parameters of the chip array, and prepare a mask layer 2 on the surface of silicon wafer 1, such as... Figure 2 (a) In this embodiment of the invention, the design of a high-density stretchable array device for LED arrays is mainly carried out. That is, in step S11, a silicon wafer 1 of a suitable size is determined according to the size of the LED array circuit. The silicon wafer 1 is made of single crystal silicon material, and the LED array is obtained by arraying LED light-emitting units 10. In addition, the material of the mask layer 2 in this embodiment of the invention is preferably silicon nitride.
[0022] S12: Design and utilize a photomask with a compensation structure to perform photolithography and etching on the mask layer 2 from step S11, thus patterning the mask layer; remove the photoresist to expose the periodically arranged mask pattern 4, such as... Figure 2 (b) In this embodiment of the invention, the design of the compensation structure in the photomask is based on the structural shape of the LED array circuit, the process characteristics of isotropic etching, and the properties of single-crystal silicon material, thereby determining the specific size and shape of the mask pattern 4.
[0023] In step S12, the photomask is a crucial tool in photolithography for controlling light transmission, comprising a substrate, a light-shielding material, an anti-reflective layer, and a protective film. The substrate is typically a high-transmittance material, such as quartz or glass. Quartz, due to its high transparency and low coefficient of thermal expansion, is the most commonly used substrate material, ensuring light transmission and maintaining shape stability during processing and use. The light-shielding material is generally chromium, plated onto the substrate surface. Chromium has high absorbance, low surface reflectivity, and good durability and chemical stability in the ultraviolet and visible light ranges; the desired light-shielding pattern can be formed by patterning chromium. The anti-reflective layer reduces light reflection and scattering, improving pattern contrast and clarity. Common materials include inorganic materials such as alumina (Al2O3) and silicon nitride (Si3N4), as well as organic materials such as polymers and optical coatings. The protective film can be added as needed, primarily to prevent contamination of the photomask through an external protective cover. In this embodiment of the invention, the periodically arranged mask pattern 4 contains a compensation structure. Furthermore, during the process of photolithography and etching of the mask layer 2 using a photomask to expose the periodically arranged mask pattern 4, a light source is used to illuminate the transparent area of the photomask (i.e., the mask pattern 4), projecting the pattern on the photomask (i.e., the mask pattern 4) onto the surface of the mask layer 2 coated with photoresist. After development, etching and other processes, the mask pattern 4 is transferred onto the mask layer 2.
[0024] S13: Using an HNA solution, isotropic etching is performed on silicon wafer 1, leaving a series of flexible electrode holes 3 at the corresponding positions of the mask pattern 4 on silicon wafer 1, such as... Figure 2 (c) In this embodiment of the invention, the cross-section of the flexible electrode hole 3 is hemispherical; in other embodiments, the cross-section of the flexible electrode hole 3 can be a smooth curve shape similar to a sine function.
[0025] S14: Remove mask layer 2 using a wet etching process, such as... Figure 2 (d) In some other embodiments, a dry etching process can also be used to remove the mask layer 2.
[0026] S15: The silicon wafer 1 after removing the mask layer 2 in step S14 is subjected to isotropic etching again, such as... Figure 2 (e) Smooth the edge of the flexible electrode hole 3 to ensure the structural continuity and stress-strain balance of the prepared electrode.
[0027] In some other embodiments, when it is necessary to fabricate an LED array with large stretching, flexible electrode holes 3 can be fabricated by using anisotropic etching technology with a compensation structure. After removing the mask layer 2, the edges of the structure are then modified by isotropic etching.
[0028] S2: An electroforming seed layer 5 is prepared on the silicon wafer surface after step S1, and photoresist coated on the electroforming seed layer 5 is photolithographically applied; after the photolithography operation, electroforming is performed at the position of the flexible electrode hole 3 on the electroforming seed layer 5 to form a three-dimensional metal electrode 6.
[0029] In some embodiments, step S2 includes: S21: A PMMA (polymethyl methacrylate) solution is coated onto one side of the silicon wafer 1 where the flexible electrode hole 3 is located, and then cured by heating to form a PMMA film 7, such as... Figure 2 (f) in the middle.
[0030] S22: A PAA (polyamic acid) solution is sprayed onto the surface of the PMMA film 7 obtained in step S21, and the temperature is increased in stages to imidize it and form a PI (polyimide) film 8, such as... Figure 2 (g) In this context, PMMA film 7 is the sacrificial layer and needs to be removed later.
[0031] S23: A copper thin film is deposited on the PI thin film 8 from step S22 by magnetron sputtering to form an electroforming seed layer 5, such as... Figure 2 As shown in (h), the material of the electroforming seed layer 5 is copper. In other embodiments, the electroforming seed layer 5 can be gold.
[0032] S24: A thick film of photoresist 9 is coated onto the electroforming seed layer formed in step S23 for photolithography, exposing the electrode area to be electroformed. The remaining photoresist 9 has a structural thickness greater than the designed thickness of the metal electrode, such as... Figure 2 As shown in (i) in the figure. Since the device in the current structure is not flat, the laser direct writing technology is used in this embodiment of the invention to perform a direct writing operation on the surface of the electroformed seed layer 5 by real-time focused irradiation.
[0033] S25: Based on the flexible electrode hole 3, a three-dimensional metal electrode 6 is formed at the position to be electroformed on the photolithographically lithographically formed electroforming seed layer 5 using an electroforming process. In this embodiment, the material of the electroforming seed layer 5 is copper, and correspondingly, the material of the three-dimensional metal electrode 6 is also copper. In other embodiments, the electroforming seed layer 5 can be gold, and correspondingly, the material of the three-dimensional metal electrode 6 is also gold. Thus, this invention obtains the flexible electrode hole 3 based on a photolithography plate with a compensation structure, thereby obtaining a three-dimensional metal electrode 6 that meets the design requirements.
[0034] S26: Remove the photoresist 9 using a photoresist remover appropriate for the photoresist, and remove the electroforming seed layer 5 covered by the photoresist 9 using wet etching, retaining the three-dimensional metal electrode 6, such as Figure 2 As shown in (j) in the figure. In some other embodiments, dry etching can also be used to remove the electroformed seed layer 5, leaving the three-dimensional metal electrode 6 intact.
[0035] In some other embodiments, a sputtered or thermally grown silicon dioxide film is prepared on the surface of the silicon wafer after step S1 as a sacrificial layer, and a copper (or gold) film is deposited on the surface of the sacrificial layer as an electroforming seed layer 5. After the three-dimensional metal electrode 6 is prepared by thick photolithography and electroforming, the copper film 5 is removed and the three-dimensional metal electrode 6 is retained. That is, the sacrificial layer can be silicon dioxide.
[0036] S3: Fix the chip array at the position of the three-dimensional metal electrode 6 made in step S2, and use a flexible polymer to cover the surface where the chip array and the three-dimensional metal electrode 6 are located to form a top encapsulation layer 11.
[0037] In some embodiments, step S3 includes: S31: Place the chip array on the solder pad area, heat the solder to melt it, and solder the chip array to the solder pads of the three-dimensional metal electrode 6, such as... Figure 2 In the embodiment of the invention, since the chip array is an LED array, the LED light-emitting units 10 are soldered to the pads of the three-dimensional metal electrode 6 in an array form.
[0038] S32: Cover the surface of the chip array and three-dimensional metal electrode 6 in the structure obtained in step S31 with a flexible polymer film, and wait for the flexible polymer film to cure to form the top encapsulation layer 11, as shown. Figure 2 As shown in (l) in the figure. In this embodiment of the invention, since the chip array is a light-emitting LED array, in order to ensure the light output efficiency of the LED array, this embodiment of the invention preferably uses a flexible transparent polymer film to form the top encapsulation layer 11. Specifically, the flexible transparent polymer can be a flexible and stretchable polymer material such as silicone or hydrogel.
[0039] S4: Remove silicon wafer 1 from the structure obtained in step S3 and lead out the connection line 13 of the driver chip array; in this structure, a flexible polymer is coated on the opposite side of the top encapsulation layer 11 as the bottom encapsulation layer 12.
[0040] In some embodiments, step S4 includes: S41: The composite structure containing the three-dimensional metal electrode 6, the chip array, and the top encapsulation layer 11 is peeled off from one side of the PI film 8 from the silicon wafer 1, as follows: Figure 2 As shown in (m); S42: The PI thin film 8 is etched away using a dry etching process to expose the three-dimensional metal electrode 6, such as... Figure 2 As shown in (n); S43: Clean the exposed three-dimensional metal electrode 6 with dilute hydrochloric acid, and lead the connecting wire 13 from the pad position of the three-dimensional metal electrode 6, such as... Figure 2 As shown in (o); S44: A flexible polymer is used to form the bottom encapsulation layer 12, completing the bottom encapsulation, such as... Figure 2 As shown in (p). Specifically, a flexible polymer is coated on the bottom of the composite structure obtained in step S43, and the flexible polymer is cured to form the bottom encapsulation layer 12, thus completing the bottom encapsulation of the stretchable array device.
[0041] In some other embodiments, step S4 includes: releasing the top encapsulation layer 11 by etching the silicon dioxide sacrificial layer or etching the silicon wafer, then leading out the connection line 13 at the exposed electrode pad location, and coating the opposite side of the top encapsulation layer 11 with a flexible polymer as the bottom encapsulation layer 12.
[0042] This invention utilizes a method for fabricating a high-density stretchable array device of three-dimensional metal electrodes to obtain, as shown in the provided method, a high-density stretchable array device of three-dimensional metal electrodes. Figure 3 The high-density stretchable array device with three-dimensional metal electrodes shown in this invention includes a flexible polymer as a top encapsulation layer 11 and a bottom encapsulation layer 12, a chip array, three-dimensional metal electrodes 6, and connecting lines 13. In this embodiment, the chip array is an LED array obtained by arraying LED light-emitting units 10. (The LED array is shown for clarity.) Figure 3 The top encapsulation layer 11 is omitted. Unlike traditional stretchable devices, the three-dimensional metal electrode 6 of the high-density stretchable array device based on three-dimensional metal electrodes proposed in this invention is bent in a direction perpendicular to the plane where the chip array is located. This avoids the problem that the flexible electrodes of existing solutions occupy too large an area in the plane where the chip array is located, making it difficult to achieve high-density circuit integration. When the chip array is an LED array, the high-density stretchable array device based on three-dimensional metal electrodes provided by this invention greatly improves the LED light-emitting unit density and illumination uniformity.
[0043] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.
[0044] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes, characterized in that, include: S1: According to the design parameters of the chip array, a mask layer is prepared on the surface of the silicon wafer, the silicon wafer is etched to leave flexible electrode holes on the surface of the silicon wafer, and then the mask layer is removed. S2: An electroforming seed layer is prepared on the silicon wafer surface after step S1, and photoresist coated on the electroforming seed layer is photolithographically etched; after the photolithography operation, electroforming is performed at the location of the flexible electrode hole on the electroforming seed layer to form a three-dimensional metal electrode. S3: Fix the chip array at the position of the three-dimensional metal electrode made in step S2, and use a flexible polymer to cover the surface where the chip array and the three-dimensional metal electrode are located in the current structure to form a top encapsulation layer; S4: In the structure obtained in step S3, the silicon wafer is separated and the connection line for driving the chip array is led out; in this structure, a flexible polymer is coated on the opposite side of the top encapsulation layer as a bottom encapsulation layer.
2. The method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes according to claim 1, characterized in that, Step S1 includes: S11: Determine the structural parameters of the silicon wafer according to the design parameters of the chip array, and prepare the mask layer on the surface of the silicon wafer; S12: Design and utilize a photomask with a compensation structure to perform photolithography and etching on the mask layer of step S11 to pattern the mask layer; remove the photoresist to expose the periodically arranged mask pattern. S13: Use HNA solution to perform isotropic etching on the silicon wafer, leaving a series of flexible electrode holes at the corresponding positions of the mask pattern on the silicon wafer; S14: Remove the mask layer using a wet etching process or a dry etching process.
3. The method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes according to claim 2, characterized in that, Step S1 also includes: S15: The silicon wafer from which the mask layer was removed in step S14 isotropically etched again to smooth the edges of the flexible electrode holes.
4. The method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes according to claim 1, characterized in that, Step S2 includes: S21: A PMMA solution is coated on the side of the silicon wafer where the flexible electrode hole is located and then heated to cure, forming a PMMA film; S22: The surface of the PMMA film obtained in step S21 is sprayed with PAA solution, and the PAA solution is imidized by stepwise heating to form a PI film; S23: Copper film is deposited on the PI film in step S22 by magnetron sputtering to form an electroforming seed layer; S24: Coat the electroforming seed layer formed in step S23 with a thick film of photoresist and perform photolithography to expose the electrode area to be electroformed. The thickness of the remaining photoresist structure is greater than the thickness of the designed electrode. S25: Based on the flexible electrode hole, the three-dimensional metal electrode is formed at the position to be electroformed on the photolithographically lithographically formed electroforming seed layer through an electroforming process. S26: Remove the photoresist using a photoresist remover corresponding to the photoresist, and remove the electroforming seed layer covered by the photoresist using wet etching, while retaining the three-dimensional metal electrode.
5. The method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes according to claim 4, characterized in that, In step S24, laser direct writing technology is used to perform a real-time focused irradiation of the photoresist on the surface of the electroformed seed layer.
6. The method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes according to claim 4, characterized in that, Step S3 includes: S31: Place the chip array on the solder pad area coated with solder, heat the solder to melt it, and solder the chip array to the solder pad of the three-dimensional metal electrode; S32: Cover the surface of the chip array and the three-dimensional metal electrode in the structure obtained in step S31 with a flexible polymer film, and wait for the flexible polymer film to cure to form the top encapsulation layer.
7. The method for fabricating a high-density stretchable array device based on three-dimensional metal electrodes according to claim 6, characterized in that, Step S4 includes: S41: Peel the composite structure containing the three-dimensional metal electrode, the chip array and the top encapsulation layer from the silicon wafer from one side of the PI film; S42: The PI film is etched away using a dry etching process to expose the three-dimensional metal electrode; S43: Clean the exposed three-dimensional metal electrode with dilute hydrochloric acid and lead the connection line out from the pad of the three-dimensional metal electrode; S44: The bottom encapsulation layer is formed using the flexible polymer, thus completing the bottom encapsulation of the stretchable array device.
8. A high-density stretchable array device based on three-dimensional metal electrodes, characterized in that, It is prepared using the fabrication method of the high-density stretchable array device based on three-dimensional metal electrodes according to any one of claims 1 to 7.