Flexible electronic device and laser processing method thereof

Abstract

The present invention belongs to the technical field related to the preparation of flexible electronics, and discloses a flexible electronic device and a laser processing method thereof, comprising the following steps: (1) preparing a sacrificial layer on a transparent substrate, and preparing a patterned structure on the sacrificial layer by a patterning process; the difference between the thermal expansion coefficient of the material of the sacrificial layer and the thermal expansion coefficient of the material of the patterned structure is greater than 10 ‑5 K ‑1 ; (2) depositing a functional layer on the exposed area of ​​the sacrificial layer and the patterned structure; (3) depositing a substrate layer on the functional layer to obtain a semi-finished product of a flexible electronic device, and scanning the transparent substrate with a laser beam, the laser beam passes through the transparent substrate and acts on other structures of the semi-finished product; (4) mechanically separating the semi-finished product after the laser action to obtain a patterned flexible electronic device. The present invention realizes the patterning and peeling of the functional layer at the same time, simplifying the process.

Description

Technical Field

[0001] The present invention belongs to the technical field related to flexible electronic preparation, and more specifically, relates to a flexible electronic device and a laser processing method thereof. Background Art

[0002] Flexible electronic device manufacturing is an emerging electronic technology that builds devices on flexible or ductile substrates. It can realize the integrated manufacturing of structures and devices of different sizes and materials. Due to its unique flexibility and ductility, it is widely used in flexible displays, radio frequency identification, electronic skin, etc. The key to the manufacture of flexible electronic devices includes manufacturing processes, substrates and materials, and its core is micro-nano patterned manufacturing. Patterned flexible electronic devices account for a large proportion of flexible electronics. With its development towards integration, intelligence, and multi-parameter detection, and the need for flexible arrangement according to measurement conditions, patterned flexible electronics has also become a general trend.

[0003] However, the manufacturing of flexible patterned electronic devices often involves complicated steps, and requires the preparation of patterned electrodes, the preparation of patterned functional layers, stripping, and packaging. Among them, the patterning process of the electrodes and functional layers requires them to form completely overlapping identical patterns, which places a very high demand on the patterning technology. If photolithography technology is used to pattern the electrodes and functional layers, the problem of multi-layer mask alignment needs to be solved. At present, in the manufacture of flexible electronic devices, the patterning technologies of electrode layers and functional layers mainly include photolithography, microcontact printing, inkjet printing, etc., and the methods for stripping mainly include mechanical ejector stripping, chemical etching, laser stripping, etc. No matter how it is combined, the preparation process of flexible patterned sensing electronic devices is still very complicated. For example, when Byun uses lead zirconate titanate lanthanum (PLZT) piezoelectric film to prepare flexible piezoelectric sensors (Byun M. Poly (vinylpyrrolidone) -modification of sol-gel films for flexible piezoelectric energy harvesting systems [J]. Thin Solid Films, 2018, 663: 31-36.), the PLZT functional layer is patterned using photolithography technology, and then the PLZT film is peeled off from the rigid substrate by laser lift-off technology (LLO) to complete the preparation of the patterned device. Therefore, for the low-cost industrial manufacturing pursued by flexible electronics, it is necessary to seek a simplified preparation process for flexible patterned electronic devices. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a flexible electronic device and a laser processing method thereof, which can simultaneously realize the patterning of the flexible electronic structure and the device peeling. Under the conditions of certain laser parameters and the control of the thickness of the sacrificial layer, at the interface where the pattern exists, due to the large difference in the thermal expansion coefficients of the two materials intersecting at the interface, when subjected to the same high temperature, the thermal deformation produced by the two materials is quite different, which will cause the two contacting materials to separate, thereby greatly reducing the adhesion strength of the interface. The patterned interface can be separated under the action of external mechanical force to obtain a two-dimensional patterned device prepared on a substrate, thereby solving the problem of patterning alignment of the electrode layer and the functional layer in the preparation process of flexible patterned electronic devices.

[0005] To achieve the above object, according to one aspect of the present invention, a laser processing method for a flexible electronic device is provided, the method mainly comprising the following steps:

[0006] (1) preparing a sacrificial layer on a transparent substrate, and preparing a patterned structure on the sacrificial layer by a patterning process; wherein the difference between the thermal expansion coefficient of the material of the sacrificial layer and the thermal expansion coefficient of the material of the patterned structure is greater than 10 -5 K -1 ;

[0007] (2) depositing a functional layer on the exposed area of ​​the sacrificial layer and the patterned structure to fill and cover the exposed area of ​​the sacrificial layer and the patterned structure;

[0008] (3) depositing a substrate layer on the functional layer to obtain a semi-finished product of a flexible electronic device, and scanning the transparent substrate with a laser beam, wherein the laser beam passes through the transparent substrate and acts on other structures of the semi-finished product;

[0009] (4) Mechanically separate the semi-finished products after laser treatment to obtain patterned flexible electronic devices.

[0010] Furthermore, the shape of the functional layer pattern structure of the flexible electronic device is the same as the shape of the patterned structure.

[0011] Furthermore, under the action of the laser beam, the interface separation occurs on the contact surface between the patterned structure and the sacrificial layer, and at the same time, the interface between the functional layer and the substrate layer is separated except for the area corresponding to the patterned structure.

[0012] Furthermore, the thickness of the sacrificial layer is 500nm-600nm.

[0013] Furthermore, laser parameters: laser energy density 50mJ / cm 2 ~250mJ / cm2 .

[0014] Furthermore, the transparent substrate is Al2O3, quartz, sapphire substrate or glass sheet.

[0015] Furthermore, the material of the sacrificial layer is an electrical material PZT, zinc oxide or amorphous silicon.

[0016] Furthermore, the material of the patterned structure is Ni, Ag, Cu, Ti, Au or Pt.

[0017] Furthermore, the material of the substrate layer is polyimide, polydimethylsiloxane or polyethylene terephthalate.

[0018] According to another aspect of the present invention, a flexible electronic device is provided, which is prepared by the laser processing method of the flexible electronic device as described above, and the flexible electronic device includes a substrate layer and a functional layer pattern structure formed on the substrate layer, and the functional layer pattern structure includes the patterned structure and an area of ​​the functional layer corresponding to the patterned structure.

[0019] In general, compared with the prior art, the flexible electronic device and the laser processing method thereof provided by the present invention have the following beneficial effects:

[0020] 1. The laser beam passes through the transparent substrate and acts on other structures of the semi-finished product. Under the action of the laser beam, the interface separation occurs on the contact surface between the patterned structure and the sacrificial layer, and at the same time, the interface between the functional layer and the substrate layer except the area corresponding to the patterned structure is separated. This simplifies the process flow. During the process of completing the peeling of electronic devices from the rigid substrate by the laser peeling process, the functional layer can be patterned at the same time, so that the two-step process of peeling and patterning of the functional layer is combined into one step, which greatly simplifies the process and improves the preparation efficiency.

[0021] 2. The difference between the thermal expansion coefficient of the material of the sacrificial layer and the thermal expansion coefficient of the material of the patterned structure is within an order of magnitude (i.e., 10 -5 / K -1 ) or more, and then under the action of laser, such a large difference in thermal expansion coefficients causes the thermal stress generated by the two at higher temperatures to be mismatched, thereby promoting interface separation.

[0022] 3. The thickness of the sacrificial layer is 500m~600nm, and the laser energy density parameter range is 50mJ / cm 2 ~250mJ / cm 2In this way, under the conditions of suitable laser parameters and sacrificial layer thickness, the laser beam passes through the transparent substrate and acts on other layer structures above it. Since the thermal expansion coefficients of the material of the patterned structure and the material of the sacrificial layer are quite different, the corresponding thermal deformation is also quite different, which in turn greatly reduces the adhesion strength of the interface between the patterned structure and the sacrificial layer.

[0023] 4. The difficulty of patterning and aligning the electrode layer and the functional layer in the preparation process of flexible patterned electronic devices is solved. By adjusting the laser parameters, the present invention can directly realize the breaking of the functional layer from the edge of the patterned structure during the laser stripping process, and obtain the same pattern that completely overlaps with the patterned structure, thereby eliminating the need to perform the patterning process of the functional layer, and effectively avoiding the problem of pattern alignment between the patterned structure and the functional layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic flow chart of the laser processing method of the flexible electronic device provided by the present invention;

[0025] Figure 2 It is a schematic structural diagram of a transparent substrate involved in the laser processing method of a flexible electronic device provided by the present invention;

[0026] Figure 3 is Figure 2 A schematic diagram of a structure after a sacrificial layer is prepared on a transparent substrate;

[0027] Figure 4-1 is Figure 3 A schematic diagram of a structure after a patterned structure is prepared on a sacrificial layer;

[0028] Figure 4-2 yes Figure 4-1 A cross-sectional view of the structure along the AA direction;

[0029] Figure 5 is Figure 4-1 A schematic diagram of a structure after a functional layer is prepared on a patterned structure;

[0030] Figure 6 is Figure 5 A schematic diagram of a structure after a substrate layer is prepared on a functional layer;

[0031] Figure 7 It is a laser pair Figure 6 Schematic diagram of the structure in action;

[0032] Figure 8 yes Figure 6 Schematic diagram of the structure after being acted on by laser;

[0033] Fig. 9 yes Figure 8Schematic diagram of mechanical peeling of the structure in FIG.

[0034] Figure 10-1 Is adopted Figure 1 A schematic diagram of a flexible electronic device obtained by laser processing of a flexible electronic device as shown;

[0035] Figure 10-2 yes Figure 10-1 Cross-sectional view of the flexible electronic device along the BB direction.

[0036] In all drawings, the same reference numerals are used to denote the same elements or structures, wherein: 10 - transparent substrate, 20 - sacrificial layer, 30 - patterned structure, 40 - functional layer, 50 - substrate layer, 60 - laser beam, 41 - functional layer pattern structure. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The laser processing method of the flexible electronic device provided by the present invention adopts laser. Among them, laser stripping technology is a new process widely used in flexible electronic manufacturing, which can be used to separate multi-layer thin film structures. The laser passes through a transparent substrate and irradiates the interface material. The interface material absorbs the laser and undergoes interface reactions such as ablation, melting, decomposition, evaporation, and quenching, resulting in a decrease in the adhesion strength of the interface, thereby causing interface separation.

[0039] Laser is used to pass through a transparent substrate and act on the interface of a multilayer structure. By adjusting the thickness of the sacrificial layer and the laser irradiation parameters (such as irradiation energy and number of irradiations), the multilayer structure will produce different results when the interface layer is peeled off under the action of lasers of different energies. Laser peeling technology uses laser processing, which has the advantages of fast processing speed and easy control of processing position, which conforms to the development trend of high-efficiency, automated, and mass production. Using this technology, high-efficiency, large-area, and low-cost flexible patterned electronic devices can be prepared, and the laser peeling process can effectively reduce problems such as chemical contamination of electronic devices, greatly simplifying the process.

[0040] See also Figure 1 , the laser processing method mainly includes the following steps:

[0041] S11, providing a transparent substrate, and depositing a sacrificial layer on the surface of the transparent substrate. The sacrificial layer should have a predetermined thickness, so that when the energy density of the laser beam 60 is too high, the sacrificial layer can block most of the laser energy, thereby preventing the device from being damaged. In this embodiment, the thickness of the sacrificial layer is 500nm.

[0042] Specifically, see Figure 2 and Figure 3 First, clean the transparent substrate 10. The transparent substrate 10 needs to be transparent to the set wavelength. For example, for the 308nm wavelength excimer laser, quartz glass or sapphire glass can be used, which has high transparency to the 308nm wavelength ultraviolet laser. The transparent substrate 10 can be Al2O3, quartz, sapphire substrate or glass sheet.

[0043] Next, a sacrificial layer 20 is deposited on the transparent substrate 10 by a deposition process. The material of the sacrificial layer 20 is PZT, and the sacrificial layer 20 needs to have a certain thickness so that it can directly absorb most of the laser energy when the laser energy is high, reduce the ablation or thermal damage caused by the high energy of the laser to the internal device, and play a role in protecting the device layer. The material of the sacrificial layer 20 can be formed by chemical vapor deposition (CVD), plasma assisted chemical deposition (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD), spin coating or other process methods. The material of the sacrificial layer 20 can be a piezoelectric material PZT, zinc oxide (ZnO) or amorphous silicon (α-Si).

[0044] S12, preparing a patterned structure with a desired pattern on the sacrificial layer through a patterning process, and exposing a portion of the sacrificial layer.

[0045] Specifically, see Figure 4-1 and Figure 4-2 , a metal layer pattern (such as an electrode layer) is sputtered on the sacrificial layer 20 using a magnetron sputtering process with a physical mask, i.e., a patterned structure 30. The patterned structure 30 is a rectangular island-shaped two-dimensional array structure. The island-shaped array structure can be easily interconnected with other structures, which is conducive to the preparation of multifunctional, integrated devices. In the magnetron sputtering process, patterned structures with different patterns can also be deposited by replacing different mask plates, so as to finally obtain electronic devices with different patterns or different functional applications.

[0046] The difference between the thermal expansion coefficient of the material of the sacrificial layer 20 and the thermal expansion coefficient of the material of the patterned structure 30 is within 10 -5 K -1Such a large difference in thermal expansion coefficients causes the thermal stress generated by the two at higher temperatures to be mismatched, thereby promoting interface separation. The material of the patterned structure is pure metal or composite metal of Ni, Ag, Cu, Ti, Au or Pt; the patterning process can be photolithography, imprinting, micro-contact printing or inkjet printing technology.

[0047] S13, depositing a functional layer on the exposed area of ​​the sacrificial layer and the patterned structure to fill and cover the exposed area of ​​the sacrificial layer and the patterned structure.

[0048] Specifically, see Figure 5 A functional layer 40 is deposited on the exposed area of ​​the sacrificial layer 20 and the patterned structure 30 by a deposition process. The functional layer 40 is the key to realizing the function of the electronic device. The material of the functional layer 40 can be a PZT functional layer material, which has a piezoelectric effect and can generate an effect of an electrical signal under pressure, or the material can undergo mechanical deformation under the action of an electric field, and can be used in electronic devices such as drivers, sensors, and micro-displacers. The material of the functional layer 40 can specifically be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate (PZT), and anti-doped aluminum nitride (AlScN).

[0049] S14, depositing a substrate layer on the functional layer, thereby obtaining a semi-finished product of a flexible electronic device.

[0050] Specifically, see Figure 6 A substrate layer 50 is deposited on the functional layer 40. The substrate layer 50 plays a role in connecting the device support and protecting the device, and can ensure the efficiency and simplicity of the overall device transfer process. The material of the substrate layer 50 can be polyimide (PI), polydimethylsiloxane (PDMS) or polyethylene terephthalate (PET) material.

[0051] S15, scanning the transparent substrate with a laser beam, wherein the laser beam passes through the transparent substrate and acts on other structures of the semi-finished product. Wherein, a laser lift-off process is adopted, under the conditions of appropriate laser parameters and sacrificial layer thickness, so that the laser beam passes through the transparent substrate and acts on other layer structures above it, and since the thermal expansion coefficients of the material of the patterned structure and the material of the sacrificial layer are greatly different, the corresponding thermal deformation is also greatly different, which in turn causes the adhesion strength of the interface between the patterned structure and the sacrificial layer to be greatly reduced.

[0052] Specifically, see Figure 7 and Figure 8, a laser lift-off process is used, so that the laser beam 60 linearly scans the bottom surface of the transparent substrate 10. Since the transparent substrate 10 has a high transmittance to the laser beam 60, the laser beam 60 passes through the transparent substrate 10 and acts on other structures of the semi-finished product. The laser lift-off interface layer can be regulated by controlling the thickness of the sacrificial layer 20 and the laser action parameters. When the laser energy density is high, most of the laser energy will be absorbed by the sacrificial layer 20, and the temperature of the sacrificial layer 20 will increase, causing a series of reactions such as melting, decomposition, and ablation. At this time, the interfacial adhesion strength between the sacrificial layer 20 and the transparent substrate 10 is reduced, and separation will occur at this interface; when the laser energy density is low, the laser photons cannot be directly absorbed by the sacrificial layer 20, so they have the opportunity to penetrate the sacrificial layer 20 and act on the patterned structure 30. The laser acting on the patterned structure 30 can generate a large number of carriers on the surface of the patterned structure 30, and the carriers enhance the absorption of the laser by the surface of the patterned structure 30, so an overheating effect is generated at the interface between the patterned structure 30 and the sacrificial layer 20, and the temperature rises; and because the thermal expansion coefficients of the patterned structure 30 and the sacrificial layer 20 are quite different, at the interface between the patterned structure 30 and the sacrificial layer 20 at the same high temperature, the thermal stresses generated by the patterned structure 30 and the sacrificial layer 20 will not match, thereby promoting interface separation.

[0053] By adjusting the appropriate sacrificial layer thickness and laser parameters in the laser lift-off process, such as energy density and irradiation times, the laser can be separated on the surface of the patterned structure 30 and the sacrificial layer 20. In this embodiment, the laser energy density control range is 50 mJ / cm 2 ~250mJ / cm 2 The irradiation times range from 10 to 300 times.

[0054] The deposited patterned structure 30 is a rectangular island-shaped two-dimensional array structure. This interface absorbs ultraviolet laser light transmitted through the upper medium, causing the temperature at the interface to rise. Since the thermal expansion coefficients of the metal material used in the patterned structure and the sacrificial layer material are quite different, under the action of large thermal stress, interface separation occurs on the contact surface between the patterned structure 30 and the sacrificial layer 20, and at the same time, the interface between the functional layer excluding the area corresponding to the patterned structure and the substrate layer is separated.

[0055] S16, mechanically separating the semi-finished product after the laser treatment to obtain a patterned flexible electronic device, wherein the flexible electronic device comprises a substrate layer and a functional layer pattern structure formed on the substrate layer, and the functional layer pattern structure comprises the patterned structure and a region of the functional layer corresponding to the patterned structure.

[0056] Specifically, see Fig. 9After the laser scanning is completed, the interface separation between the patterned structure 30 and the sacrificial layer 20 is achieved. However, although the bonding strength between the patterned structure 30 and the sacrificial layer 20 is reduced, the interface adhesion still exists, so that the patterned device is not completely separated from the sacrificial layer. Therefore, it is necessary to separate the upper patterned device from the lower sacrificial layer by mechanical separation or other means to obtain the functional layer pattern structure 41, and then obtain a patterned flexible electronic device, such as Figure 10-1 and Figure 10-2 shown.

[0057] The present invention also provides a flexible electronic device, which is prepared by the laser processing method of the flexible electronic device as described above, and the flexible electronic device includes a substrate layer and a functional layer pattern structure formed on the substrate layer, and the functional layer pattern structure includes the patterned structure and an area of ​​the functional layer corresponding to the patterned structure.

[0058] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser processing method for flexible electronic devices, It is characterized in that The method comprises the following steps: (1) preparing a sacrificial layer on a transparent substrate, and preparing a patterned structure on the sacrificial layer by a patterning process; wherein the difference between the thermal expansion coefficient of the material of the sacrificial layer and the thermal expansion coefficient of the material of the patterned structure is greater than 10 - 5 K -1 ; (2) depositing a functional layer on the exposed area of ​​the sacrificial layer and the patterned structure to fill and cover the exposed area of ​​the sacrificial layer and the patterned structure; (3) depositing a substrate layer on the functional layer to obtain a semi-finished product of a flexible electronic device, and scanning the transparent substrate with a laser beam, wherein the laser beam passes through the transparent substrate and acts on other structures of the semi-finished product; wherein under the action of the laser beam, the interface separation occurs on the contact surface between the patterned structure and the sacrificial layer, and at the same time, the interface between the functional layer and the substrate layer is separated except for the area corresponding to the patterned structure; the laser is distributed not only on the surface of the transparent substrate area corresponding to the patterned structure, but also on the surface of the transparent substrate area corresponding to the functional layer at the interface between the functional layer and the sacrificial layer; (4) Mechanically separate the semi-finished products after laser treatment to obtain patterned flexible electronic devices.

2. The laser processing method for a flexible electronic device according to claim 1, Features: The shape of the functional layer pattern structure of the flexible electronic device is the same as the shape of the patterned structure.

3. The laser processing method for a flexible electronic device according to claim 1, Features: The thickness of the sacrificial layer is 500nm-600nm.

4. The laser processing method for a flexible electronic device according to claim 3, Features: The energy density of the laser is 50mJ / cm 2 ~250mJ / cm 2 .

5. The laser processing method for a flexible electronic device according to any one of claims 1 to 4, Features: The transparent substrate is Al 2 O 3 , quartz, sapphire substrate or glass.

6. The laser processing method for a flexible electronic device according to any one of claims 1 to 4, Features: The material of the sacrificial layer is electrical material PZT, zinc oxide or amorphous silicon.

7. The laser processing method for a flexible electronic device according to claim 6, Features: The material of the patterned structure is Ni, Ag, Cu, Ti, Au or Pt.

8. The laser processing method for a flexible electronic device according to claim 7, Features: The material of the substrate layer is polyimide, polydimethylsiloxane or polyethylene terephthalate.

9. A flexible electronic device, Features: The flexible electronic device is prepared by the laser processing method of the flexible electronic device according to any one of claims 1 to 8, and the flexible electronic device includes a substrate layer and the functional layer pattern structure formed on the substrate layer, and the functional layer pattern structure includes the patterned structure and the area of ​​the functional layer corresponding to the patterned structure.

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