Flexible electronic device, preparation method thereof and flexible electronic equipment

Abstract

The invention provides a flexible electronic device, a preparation method thereof and flexible electronic equipment. The method comprises the following steps: providing a substrate; patterning the surface of the substrate to form an embedded groove and a flexible groove; a plurality of embedding grooves are formed in the two sides of the flexible groove respectively; pasting a chip into the embedding groove, wherein a gap is formed between the chip and the side wall of the embedding groove; pressing a photoetching material into the flexible groove and the gap by using a dry film lamination process, and forming a photoetching film layer covering the surface of the substrate; performing patterning and metal wiring on the photoetching film layer to form a rewiring layer of the chip attached into the embedded groove; removing redundant substrate materials on the two sides of the flexible structure formed in the flexible groove; and thinning the back of the substrate until the flexible structure is exposed. In the application, by preparing the flexible structure in the substrate, the substrate can be flexible, so that the flexibility of the electronic device is realized, and the flexibility requirement of the high-performance electronic device is met.

Description

Technical Field

[0001] The present application relates to the field of flexible electronic technology, and specifically to a flexible electronic device and a preparation method thereof, and a flexible electronic device. Background Art

[0002] The advent of the information age has put forward new intelligent requirements for information terminals, such as wearable, implantable, and human-computer interaction, which has brought new challenges to traditional rigid electronic devices. It is urgent to explore the implementation of flexible electronic information systems. Flexible electronic technology integrates multidisciplinary knowledge such as microelectronics, materials science, mechanics, and bionics. The prepared flexible electronic system can work effectively in various deformation modes such as bending, folding, stretching, and twisting. It has broad demand and application prospects in wearable / implantable devices, aerospace, health care, smart Internet, and all fields of the future smart society. The flexible electronic technology that has emerged has become a cutting-edge research hotspot in the field of electronic technology worldwide, and is considered to be an important direction for the future development of electronic information systems.

[0003] At present, there are two main technical routes for the preparation of flexible electronic systems: one is to use intrinsically flexible organic materials such as organic polymers and organic semiconductors to prepare flexible electronic devices through printing and surface modification technology; the other is to transfer ultra-thin inorganic materials to flexible or elastic substrates to achieve flexibility of inorganic semiconductor chips.

[0004] The former technical route is developed based on organic semiconductor materials. Since organic semiconductors have excellent bending and stretching characteristics, the method has a simple flexible process and is easy to print, pattern, and form thin films to form flexible electronic systems. For the latter route, the core idea is to use ultra-thin silicon materials (silicon nanofilms, silicon nanobelts, and silicon nanowires) with the assistance of elastomers to realize flexible electronic devices based on inorganic materials.

[0005] Flexible electronic devices made directly from organic materials have good flexibility and can be prepared on a large scale to a certain extent through synthesis and other methods. However, for currently known organic semiconductors, low mobility is still an important factor limiting their performance. For example, the elastic organic semiconductor material studied by the current team can maintain 1.5 cm in the process of being stretched from a free state to twice its original length. 2 / V·s, but still much lower than the carrier mobility of silicon (102 -103cm 2 / V·s). Inorganic semiconductor materials represented by silicon not only have higher mobility, but also have formed a set of mature large-scale manufacturing processes. Using appropriate methods to make silicon-based structures flexible can obtain higher-performance flexible electronic devices and facilitate large-scale manufacturing, thus making it easier for industrial transformation. However, flexible electronic devices made by existing processes have low reliability and are incompatible with existing large-scale manufacturing processes, and cannot meet the flexibility requirements of higher-performance electronic devices. Summary of the invention

[0006] The purpose of this application is to provide a flexible electronic device and a preparation method thereof, and a flexible electronic device to meet users' demand for flexibility of higher performance electronic devices.

[0007] In a first aspect, the present application provides a method for preparing a flexible electronic device, comprising:

[0008] providing a substrate;

[0009] Patterning the surface of the substrate to form a buried groove and a flexible groove; the buried grooves are multiple in number and are respectively located on both sides of the flexible groove;

[0010] Pasting a chip into the buried groove, with a gap between the chip and the side wall of the buried groove;

[0011] Using a dry film lamination process, the photolithography material is pressed into the flexible groove and the gap to form a photolithography film layer covering the surface of the substrate;

[0012] Patterning the photoresist film layer and metal wiring to form a redistribution layer for the chip attached to the buried groove;

[0013] removing excess substrate material on both sides of the flexible structure formed in the flexible groove;

[0014] The back of the substrate is thinned until the flexible structure is exposed.

[0015] In some embodiments of the present application, the flexible groove is a circular flexible groove, a paper-cut structure flexible groove, or an origami structure flexible groove.

[0016] In some embodiments of the present application, the buried groove and the flexible groove have the same or different depths.

[0017] In some embodiments of the present application, the step of attaching the chip into the buried groove includes:

[0018] The chip with the die-bonding film attached to the back is attached to the embedded groove by a flip-chip bonding machine or a sub-micron chip mounter.

[0019] In some implementations of the present application, the photolithography material is a photolithography dry film material or a polyimide material.

[0020] In some implementations of the present application, the metal wiring is made of Ti / Al, Ti / Cu or Ti / Au alloy.

[0021] In some embodiments of the present application, removing excess substrate material on both sides of the flexible structure formed in the flexible groove includes:

[0022] The redundant substrate material on both sides of the flexible structure formed in the flexible groove is removed by dry etching.

[0023] In some embodiments of the present application, the substrate is a silicon substrate.

[0024] In a second aspect, the present application provides a flexible electronic device, which is prepared by the method for preparing a flexible electronic device described in the first aspect.

[0025] In a third aspect, the present application provides a flexible electronic device, wherein the flexible electronic device comprises the flexible electronic device described in the second aspect.

[0026] Compared with the prior art, the preparation method of the flexible electronic device provided in the present application includes providing a substrate; patterning the surface of the substrate to form an embedded groove and a flexible groove; the number of the embedded grooves is multiple, and they are respectively located on both sides of the flexible groove; the chip is attached to the embedded groove, and there is a gap between the chip and the side wall of the embedded groove; using a dry film lamination process, the photolithography material is pressed into the flexible groove and the gap, and a photolithography film layer covering the surface of the substrate is formed; the photolithography film layer is patterned and metal wired to form a redistribution layer of the chip attached to the embedded groove; the excess substrate material on both sides of the flexible structure formed in the flexible groove is removed; the back of the substrate is thinned until the flexible structure is exposed. In the present application, by preparing a flexible structure in the substrate, the substrate can be made flexible, thereby realizing the flexibility of the electronic device, and a higher performance flexible electronic device can be obtained. Compared with the flexible electronic device made by the existing process, the present application has high reliability and can be compatible with the existing large-scale manufacturing process, thereby meeting the flexibility requirements of higher performance electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 A flow chart showing a method for preparing a flexible electronic device provided in the present application is shown;

[0029] Figures 2A to 2H A schematic diagram showing a process of forming a flexible electronic device provided by the present application is shown;

[0030] Figure 3 What is shown is a schematic diagram of a flexible structure made by using a circular flexible groove;

[0031] Figure 4 Shows Figures 2A to 2H A top view of a flexible electronic device formed;

[0032] Figure 5 A top view of a flexible structure made of a paper-cut structure flexible groove is shown.

[0033] Reference numerals:

[0034] Substrate 10 ; buried groove 110 ; flexible groove 120 ; chip 111 ; gap 112 ; die-bonding adhesive film 113 ; photolithography film layer 20 ; flexible structure 210 ; redistribution layer 30 . DETAILED DESCRIPTION

[0035] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0036] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by technicians in the field to which this application belongs.

[0037] In addition, the terms "first" and "second" etc. are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products or devices.

[0038] To further illustrate the solution of the embodiment of the present application, the following description will be made in conjunction with the accompanying drawings. It is understandable that in the following embodiments, the same or corresponding contents can be referenced to each other, and for the sake of simplicity of description, no further description will be given later.

[0039] Many mobile phone manufacturers at home and abroad have launched flexible commercial products such as foldable screen mobile phones and tablets. Their bending also mainly depends on the flexibility of display materials. The integrated circuits (IC) chips and sensors (especially high-performance sensors) are still rigid as a whole. Therefore, strictly speaking, the existing flexible electronic products are "flexible in shape but not in core": they can only be flexible "outside" (the substrate is made of flexible materials), but not "inside" (the core IC and sensor chips are flexible themselves). To obtain high-performance flexible electronic products that are truly flexible in both "shape and core", bendable and even curlable, it is urgent to develop flexible processing methods for electronic devices that are compatible with integrated circuit processes, can stably guarantee electrical performance, and can be manufactured on a large scale, as well as flexible hybrid integration methods for multiple heterogeneous and heterogeneous chips, so that electronic devices can achieve comprehensive flexibility from the inside to the outside, greatly reduce the weight and volume of smart hardware by reducing the application of packaging structures and materials, and improve the human-computer interaction ability by improving the ability to adhere to the human body, so that smart devices and the physical world can achieve unprecedented deep integration.

[0040] At present, research in the field of flexible electronics is mainly focused on flexible display screens, flexible supercapacitors, flexible functional materials, etc., and there is still a blank in high-performance flexible electronic systems, such as flexible force sensor arrays and flexible memory chips. For example, force sensors are considered to be the core components of industrial robots. The sensing materials widely used in existing flexible force sensors are mainly carbon-based sensitive materials (carbon nanotubes, graphene, etc.), conductive polymer materials, and inorganic piezoelectric materials. Limited by the properties of materials and processing methods, the flexible force sensors prepared using the above materials have problems that need to be overcome, such as poor batch consistency, difficulty in arraying, large unit area, large temperature drift, poor linearity, poor stability, and inability to scale manufacturing. In addition, the preparation of flexible memory chips usually adopts SOI process or bulk silicon thinning process to achieve chip flexibility, and the curvature radius of its bending cannot be further reduced. Therefore, it is an urgent need for the development of the flexible electronics field to develop a high-reliability, high-performance flexible electronic device processing method that is compatible with integrated circuit technology and can be scaled and manufactured, as well as a flexible hybrid integration method for multi-heterogeneous and heterogeneous chips, to achieve high-performance flexible electronic systems (including silicon-based MEMS sensors and silicon-based IC chips).

[0041] The ultra-thin silicon structure obtained by the existing method has low reliability, complex interconnection process with the flexible substrate, and is incompatible with the existing large-scale manufacturing process, and cannot meet the flexibility requirements of high-performance silicon-based MEMS sensors / actuators with thickness requirements. Some other technical solutions, such as flexible electronic devices prepared based on Parylene MEMS process, are limited by the physical and chemical properties of Parylene itself and have the following defects:

[0042] 1. High cost: The material and coating process of polyparaxylene are relatively expensive, making it costly in large-scale applications.

[0043] 2. High requirements for surface cleanliness: Parylene coating has very high requirements for the cleanliness of the substrate surface. Any tiny contaminants will affect the adhesion and overall performance of the coating.

[0044] 3. Limited mechanical strength: The mechanical strength and wear resistance of polyparaxylene are relatively low, and it may not be suitable for some applications that require high mechanical strength and wear resistance.

[0045] 4. Difficult to repair: Once the polyparaxylene coating is damaged or defective, it is difficult to repair and usually requires re-coating.

[0046] 5. Complex process: The coating process of polyparaxylene needs to be carried out under vacuum conditions, and the process parameters need to be precisely controlled, which increases the complexity of the process and the requirements for equipment.

[0047] 6. Limited high temperature resistance: Parylene has poor stability in high temperature environments. Although it has good performance at room temperature, its mechanical properties and chemical stability may drop significantly when the temperature exceeds 100°C, which limits its use in high temperature applications.

[0048] 7. Adhesion problem: Parylene has relatively poor adhesion on some substrates. Although proper surface treatment (such as plasma treatment) can improve its adhesion, adhesion problems still exist on some special materials or complex surfaces. This may cause the coating to fall off or peel off during long-term use, thus affecting the reliability of the package.

[0049] In view of this, an embodiment of the present application provides a method for preparing a flexible electronic device, which is described below in conjunction with the accompanying drawings.

[0050] Figure 1 A flow chart showing a method for preparing a flexible electronic device provided in the present application is shown; Figures 2A to 2H A schematic diagram showing the formation process of the flexible electronic device provided by the present application is shown.

[0051] like Figure 1 As shown, the present application provides a method for preparing a flexible electronic device, comprising the following steps:

[0052] S101, providing a substrate 10;

[0053] Figure 2AThe cross-sectional schematic diagram of the substrate 10 provided in the embodiment of the present application is shown. The surface of the substrate 10 can be round or square, and the present application does not limit this. Specifically, the substrate 10 can be a silicon substrate, and of course other inorganic semiconductor material substrates can also be used. Inorganic semiconductor materials represented by silicon not only have higher mobility, but also have formed a set of mature large-scale manufacturing processes. The use of appropriate methods to achieve the flexibility of silicon-based structures can obtain higher-performance flexible electronic devices, and it is easy to achieve large-scale manufacturing, which is more convenient for industrial transformation.

[0054] S102, patterning the surface of the substrate 10 to form a buried groove 110 and a flexible groove 120; the buried grooves 110 are multiple in number and are respectively located on both sides of the flexible groove 120;

[0055] The embedded groove 110 is used to embed the electronic device chip. The flexible groove 120 is used to form a flexible structure to realize the flexibility of the electronic device and realize the bendability.

[0056] Figure 2B It is a cross-sectional schematic diagram after forming the buried groove 110 and the flexible groove 120 in the substrate 10. The depths of the buried groove 110 and the flexible groove 120 can be the same or different, and the specific value of the depth can be set according to actual needs.

[0057] Specifically, the flexible groove 120 may be a circular flexible groove, a Kirigami structure flexible groove, or an Origami structure flexible groove.

[0058] In the present application, the substrate is etched with chip embedding grooves and flexible grooves, wherein the flexible grooves can be a meandering flexible groove, or a flexible groove with a structured design similar to Kirigami, Origami, etc.

[0059] S103, pasting the chip 111 into the embedding groove 110, with a gap 112 between the chip 111 and the side wall of the embedding groove 110;

[0060] Figure 2C FIG. 1 is a cross-sectional view of a chip 111 after it is pasted into the buried groove 110 .

[0061] Specifically, the chip 111 with the die-bonding film 113 attached to the back can be attached to the embedded groove 110 by a flip-chip bonding machine or a sub-micron bonding machine.

[0062] Die Attach Film (DAF) is a high-performance adhesive film. According to different performance and uses, die attach films can be divided into two types: insulating die attach films and conductive die attach films. Insulating die attach films have insulating properties and can be used to fix chips; conductive die attach films have electrical conductivity and can be used for electrical connection in semiconductor packaging processes. In this application, the DAF film is used to fix the chip in the embedded groove 110 of the substrate.

[0063] S104, using a dry film lamination process, pressing the photolithography material into the flexible groove 120 and the gap 112, and forming a photolithography film layer 20 covering the surface of the substrate;

[0064] Figure 2D The cross-sectional view of the photoresist layer 20 formed by dry film lamination process is shown in FIG. The photoresist material pressed into the flexible groove 120 forms a flexible structure 210 .

[0065] The dry film lamination process can be implemented by a vacuum laminator, and the photolithography material can be a photolithography dry film material or a polyimide material. In this step, the dry film lamination process is used to press the photolithography dry film or polyimide film into the flexible groove and the gap between the embedded chip and the embedded groove under vacuum heating conditions, and the process temperature is determined according to different types of dry films.

[0066] S105 , patterning and metal wiring are performed on the photoresist film layer 20 to form a redistribution layer 30 of the chip attached to the buried groove.

[0067] Figure 2E FIG. 2 is a schematic cross-sectional view of the photoresist film layer 20 after patterning. Figure 2E As shown, the photoresist film layer 20 is photolithographically opened to expose the chip pad (Pad). If it is a photosensitive dry film, it can be directly photolithographically exposed, or exposed by oxygen plasma etching.

[0068] Figure 2F The figure shows a cross-sectional schematic diagram of a redistribution layer 30 formed after metal wiring. The metal wiring can be made of Ti / Al, Ti / Cu or Ti / Au alloy. When preparing the metal layer (Ti / Al or Ti / Cu or Ti / Au), magnetron sputtering or metal evaporation process can be used. The metal layer is patterned to form a redistribution layer (RDL), which can be made by metal etching or common semi-processed RDL customization.

[0069] S106 , removing excess substrate material on both sides of the flexible structure 210 formed in the flexible groove 120 .

[0070] Figure 2GThe figure shows a cross-sectional view after removing the excess substrate material on both sides of the flexible structure 210. Specifically, dry etching can be used to remove the excess substrate material on both sides of the flexible structure formed in the flexible groove, and the etching is performed on the patterned gaps of the redistribution layer 30. When a silicon substrate is used, deep silicon etching can be used to remove the excess silicon in the flexible groove to form a pure flexible structure.

[0071] S107 , thinning the back of the substrate until the flexible structure 210 is exposed.

[0072] Figure 2H It is a cross-sectional schematic diagram after the back side is thinned to release the flexible structure 210. The back side of the substrate is the other side away from the substrate surface, and the manufactured flexible structure 210 can be released by thinning the back side of the substrate.

[0073] Figure 2H What is formed is a flexible structure made using a Kirigami structure flexible groove.

[0074] Figure 3 Shown is a flexible structure made using a meander-shaped flexible groove.

[0075] Figure 4 Shows Figures 2A to 2H A top view of the formed flexible electronic device, wherein the functional unit corresponds to the buried groove area of ​​the chip, and the parallel grooves correspond to the parallel-parallel flexible structures 210 . Figure 5 A top view of a flexible structure 210 made of a kirigami structure flexible groove is shown. For example, the length L of each opening in the structure is 200 μm, the width W is 50 μm, and the edge thickness S is 10 μm.

[0076] The method for preparing the above-mentioned flexible electronic device provided in the embodiment of the present application can make the substrate flexible by preparing a flexible structure in the substrate, thereby realizing the flexibility of the electronic device, and obtaining a higher performance flexible electronic device. Compared with the flexible electronic devices made by the existing process, the present application has high reliability and can be compatible with the existing large-scale manufacturing process, thereby meeting the flexibility requirements of higher performance electronic devices.

[0077] The embodiment of the present application further provides a flexible electronic device, which is prepared by using the method for preparing the flexible electronic device in the above embodiment.

[0078] The embodiment of the present application also provides a flexible electronic device, wherein the flexible electronic device comprises the above-mentioned flexible electronic device. For example, the flexible electronic device is a foldable mobile phone, a foldable watch, etc.

[0079] In the description of this specification, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0080] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0081] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0082] In the present disclosure, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being “above”, “above”, and “above” a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0083] The disclosure above provides many different embodiments or examples to implement different structures of the present disclosure. In order to simplify the present disclosure, the components and settings of specific examples are described above. Of course, they are only examples, and the purpose is not to limit the present disclosure. In addition, the present disclosure can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0084] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of various changes or replacements within the technical scope disclosed in the present disclosure. Different parts in different embodiments can be combined with each other without conflict, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for preparing a flexible electronic device, characterized in that: include: providing a substrate; Patterning the surface of the substrate to form a buried groove and a flexible groove; the buried grooves are multiple in number and are respectively located on both sides of the flexible groove; Pasting a chip into the buried groove, with a gap between the chip and the side wall of the buried groove; Using a dry film lamination process, the photolithography material is pressed into the flexible groove and the gap to form a photolithography film layer covering the surface of the substrate; Patterning the photoresist film layer and metal wiring to form a redistribution layer for the chip attached to the buried groove; removing excess substrate material on both sides of the flexible structure formed in the flexible groove; The back of the substrate is thinned until the flexible structure is exposed.

2. The method for preparing a flexible electronic device according to claim 1, characterized in that: The flexible groove is a circular flexible groove, a paper-cut structure flexible groove or an origami structure flexible groove.

3. The method for preparing a flexible electronic device according to claim 1, characterized in that: The buried groove and the flexible groove may have the same depth or different depths.

4. The method for preparing a flexible electronic device according to claim 1, characterized in that: The step of pasting the chip into the buried groove comprises: The chip with the die-bonding film attached to the back is attached to the embedded groove by a flip-chip bonding machine or a sub-micron chip mounter.

5. The method for preparing a flexible electronic device according to claim 1, characterized in that: The photolithography material is a photolithography dry film material or a polyimide material.

6. The method for preparing a flexible electronic device according to claim 1, characterized in that: The metal wiring is made of Ti / Al, Ti / Cu or Ti / Au alloy.

7. The method for preparing a flexible electronic device according to claim 1, characterized in that: The removing of excess substrate material on both sides of the flexible structure formed in the flexible groove comprises: The redundant substrate material on both sides of the flexible structure formed in the flexible groove is removed by dry etching.

8. The method for preparing a flexible electronic device according to claim 1, characterized in that: The substrate is a silicon substrate.

9. A flexible electronic device, characterized in that: The flexible electronic device is prepared by the method for preparing a flexible electronic device according to any one of claims 1 to 8.

10. A flexible electronic device, characterized in that: The flexible electronic device comprises the flexible electronic device according to claim 9.

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