A method for fabricating thin film micro devices on a non-planar structure

Abstract

This invention provides a method for fabricating microdevices on irregular structures, comprising: attaching a dry film photoresist onto the irregular structure; fixing a first flexible mask onto the irregular structure; performing photolithography and development on the irregular structure; and depositing a first material layer on the irregular structure, followed by peeling off the dry film to form a pattern of the first material layer. This invention directly attaches the dry film to the surface of the irregular structure and uses a flexible mask instead of a traditional hard metal mask, enabling the fabrication of fine patterned structures on the surface of irregular structures. Furthermore, this invention provides a method for achieving fine patterning and overlay of multilayer thin films on the surface of irregular structures, providing a technical approach for the in-situ integration of multiple sensors on irregular components within limited space, and its applications are increasingly evident in many areas.

Description

Technical Field

[0001] This invention generally relates to the field of microfabrication technology. Specifically, this invention relates to a method for fabricating thin-film microdevices on irregular structures. Background Technology

[0002] MEMS microfabrication technology originated from semiconductor and microelectronic processes, using basic process steps such as photolithography, epitaxy, thin film deposition, oxidation, diffusion, implantation, sputtering, evaporation, etching, dicing, and packaging to fabricate complex three-dimensional shapes. However, because standard MEMS / IC processes only allow the fabrication of microstructures on flat panels, MEMS / IC components can only be placed on flat chip substrates. This technology has been quite mature after many years of development. While patterning processes on curved surfaces have been studied to some extent, they remain in a state of low reliability and cannot be mass-produced.

[0003] Chinese patent CN 105259733 A discloses a method for fabricating a flexible mask for patterning curved surfaces. In this method, a Ni metal thin film with the same shape as the curved surface is first formed on a curved substrate using an electroplating process. The Ni metal thin film is then released using ultrasound. Next, the Ni metal thin film, which has a certain deformability, is fixed to glass. The Ni metal thin film is then patterned using photolithography and etching processes. Finally, the patterned Ni metal thin film is attached to the curved substrate as a metal mask, and a metal pattern is sputtered.

[0004] This curved surface patterning process requires the fabrication of a hard metal mask, which is complex. Furthermore, when using a hard metal mask for sputtering, the precision of the pattern on the curved surface cannot be improved due to factors such as high temperature and deformation, and it is difficult to reuse the mask multiple times. It is suitable for single-layer thin film patterns, but the alignment process for more challenging multi-layer curved thin film patterns is not addressed. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a method for fabricating thin film microdevices by thin film patterning on irregular structures, which can realize the fine patterning of multilayer thin films on the surface of irregular structures, and provide a basis for the integration of multiple sensors on irregular components with limited space.

[0006] This invention provides a method for fabricating microdevices on irregular structures, comprising:

[0007] Dry film photoresist is applied to irregularly shaped structures;

[0008] The first flexible mask plate is fixed onto the irregular structure;

[0009] Photolithography and development of irregular structures; and

[0010] A first material layer is deposited on an irregular structure, and then the dry film is peeled off to form a pattern of the first material layer.

[0011] In one embodiment of the present invention, the method includes performing a pretreatment process on the curved substrate before applying dry film photoresist, the pretreatment process including polishing, grinding and cleaning.

[0012] In one embodiment of the present invention, the first flexible mask is fixed to the irregular structure by an adhesive layer to ensure that the first flexible mask is in close contact with the irregular structure.

[0013] In one embodiment of the present invention, a first material layer is deposited by physical vapor deposition, and then the irregular structure is immersed in a 1% NaOH solution to remove the dry film and the first material layer on its surface, leaving only the pattern of the first material layer directly deposited on the surface of the irregular structure.

[0014] In one embodiment of the present invention, the method includes:

[0015] Dry film photoresist is applied to an irregular structure with a pattern of the first material layer;

[0016] The second flexible mask plate is fixed onto the irregular structure;

[0017] Photolithography and development of irregular structures; and

[0018] A second material layer is deposited on the irregular structure, and then the dry film is peeled off to form a pattern of the second material layer.

[0019] In one embodiment of the present invention, the pattern of the irregular structure is aligned with the pattern on the second flexible mask using a special fixture under a yellow light microscope.

[0020] The special fixture includes a displacement stage, a workpiece fixture fixed on the displacement stage, and a mask plate support located above the workpiece fixture.

[0021] During the alignment process, the irregular structure is fixed on the workpiece fixture, the second flexible mask is fixed on the mask support, and the displacement stage drives the irregular structure to move, so as to align the pattern on the irregular structure with the pattern on the second flexible mask.

[0022] In one embodiment of the present invention, the material of the first and / or second flexible mask includes one or more of PET, PP, PC, PVC, and PDMS.

[0023] In one embodiment of the present invention, when the surface undulation of the irregular structure exceeds the adaptability range of the first and / or second flexible mask plates, making it impossible for the first and / or second flexible mask plates to achieve close contact with the irregular structure through elastic deformation, the light-blocking pattern of the flexible mask plates is finely adjusted according to actual needs so that the projection of light passing through the mask plates becomes the expected shape.

[0024] In one embodiment of the present invention, dry film photoresist is applied only to a portion of the surface of the irregular structure; and / or

[0025] Apply pressure with rollers to assist in film application, then place in an oven to remove excess air bubbles.

[0026] In one embodiment of the present invention, the first material layer and / or the second material layer include a metal layer and a ceramic layer.

[0027] This invention uses a flexible mask instead of a traditional hard mask and combines it with dry film lithography to create fine patterned structures on curved surfaces. It can realize the patterning of curved surfaces. The flexible mask is reusable, low in cost, and flexible and convenient to operate.

[0028] Compared with existing technologies, the beneficial effects of this invention are:

[0029] 1. Photolithography can be performed on substrates with complex curved surfaces to achieve the patterning of complex devices. Conventional IC / MEMS device fabrication is carried out on planar surfaces. This invention utilizes dry film photolithography, employing a flexible mask to achieve pattern transfer and repeated printing on curved surfaces.

[0030] 2. Applying a dry film: A flexible mask is applied to the substrate for exposure and development, directly creating the pattern. The flexible mask can adhere tightly to the curved substrate and maintain a shape consistent with the curvature of the substrate. This allows for high-fidelity pattern transfer of lithographic patterns on curved surfaces.

[0031] 3. The simplified process steps of exposure, development, and sputtering greatly reduce the fabrication process of micro-devices on curved substrates and lower costs.

[0032] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention. Attached Figure Description

[0033] To further illustrate the advantages and other features of the various embodiments of the present invention, a more specific description of the embodiments of the present invention will be presented with reference to the accompanying drawings. It is understood that these drawings depict only typical embodiments of the invention and are therefore not intended to limit its scope. In the drawings, identical or corresponding parts will be indicated by the same or similar reference numerals for clarity.

[0034] Figure 1 A cross-sectional view of the process of depositing a thermistor wire sensor structure on an insulating curved surface is shown according to an embodiment of the present invention.

[0035] Figure 2 A process flow diagram of depositing a thermistor wire sensor structure on an insulating curved surface is shown according to an embodiment of the present invention.

[0036] Figure 3 A cross-sectional view of the process for fabricating a heat flow sensor structure by multilayer overlay on an insulating curved substrate is shown, according to another embodiment of the present invention.

[0037] Figure 4 A process flow diagram is shown for fabricating a heat flow sensor structure by multilayer overlay on an insulating curved substrate according to another embodiment of the present invention.

[0038] Figure 5 A special fixture for aligning irregular structures with flexible mask plates is shown according to an embodiment of the present invention. Detailed Implementation

[0039] It should be noted that the components in the various figures may be shown exaggeratedly for illustrative purposes and are not necessarily to scale. In each figure, the same reference numerals are used for components that are identical or have the same function.

[0040] In this invention, unless otherwise specified, "arranged on," "arranged above," and "arranged on" do not exclude the possibility of an intermediate element between them. Furthermore, "arranged on or above" merely indicates the relative positional relationship between two components, and in certain cases, such as when the product orientation is reversed, it can also be converted to "arranged below or under," and vice versa.

[0041] In this invention, the various embodiments are merely intended to illustrate the solutions of the invention and should not be construed as limiting.

[0042] In this invention, unless otherwise specified, the quantifiers “a” and “one” do not exclude scenarios involving multiple elements.

[0043] It should also be noted that, in the embodiments of the present invention, only a portion of the components or parts may be shown for clarity and simplicity. However, those skilled in the art will understand that, under the teachings of the present invention, necessary components or parts can be added as needed for specific scenarios. Furthermore, unless otherwise stated, features in different embodiments of the present invention can be combined with each other. For example, a feature in the second embodiment can replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment will also fall within the scope of disclosure or description of this application.

[0044] It should also be noted that, within the scope of this invention, the terms "same," "equal," and "equal to" do not imply that the two values ​​are absolutely equal, but rather allow for a certain reasonable margin of error. In other words, the terms also encompass "substantially the same," "substantially equal," and "substantially equal to." Similarly, in this invention, the directional terms "perpendicular to," "parallel to," etc., also encompass the meanings of "substantially perpendicular to" and "substantially parallel to."

[0045] Furthermore, the numbering of the steps in the methods of the present invention does not limit the execution order of the method steps. Unless otherwise specified, the method steps may be executed in different orders.

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0047] This invention provides a method for fabricating microdevices on irregular structures using thin-film patterning, resulting in excellent performance. This invention uses a flexible mask instead of a traditional hard mask, enabling the fabrication of fine patterned structures on curved surfaces. It allows for the patterning of curved surfaces, and the flexible mask is reusable, low-cost, and easy to operate.

[0048] In embodiments of the present invention, irregular structures refer to non-flat structures. For example, irregular structures may include spherical, cylindrical, conical, or polygonal shapes. In the specification of the present invention, irregular structures may also be referred to as curved substrates.

[0049] Before patterning the thin film, the curved substrate can undergo pretreatment processes. These pretreatment processes may include polishing, grinding, and cleaning. For example, the workpiece surface may be rough polished, surface oil may be removed with acetone solvent, and electrochemical degreasing and ultrasonic cleaning may be used to clean the surface.

[0050] Figure 1 A cross-sectional view of the process of depositing a thermistor wire sensor structure on an insulating curved surface is shown according to an embodiment of the present invention. Figure 2 A process flow diagram of depositing a thermistor wire sensor structure on an insulating curved surface is shown according to an embodiment of the present invention.

[0051] First, in step 201, a film-laminating process is performed on the curved substrate. Before laminating, ensure the curved substrate is thoroughly cleaned, and take care to avoid air bubbles during the lamination process. After lamination, place the substrate in an oven to bake and remove excess air bubbles. In some embodiments of the present invention, film can be laminated only on the areas where the device is fabricated, leaving other areas unlaminated. In other embodiments of the present invention, film can be laminated on the entire surface of the curved substrate.

[0052] Next, in step 202, the flexible photomask is fixed onto the curved substrate. The flexible photomask is a flexible plate with a certain elastic deformation capability and a light-shielding pattern. In embodiments of the present invention, an adhesive layer can be used to fix the flexible photomask onto the curved substrate to ensure close contact between the flexible photomask and the curved substrate, preventing light leakage during the photolithography process. For example, the material of the flexible photomask includes one or more of PET, PP, PC, PVC, and PDMS. The flexible photomask is fixed to the curved substrate using polyimide tape.

[0053] In step 203, the curved substrate is photolithographically etched and developed.

[0054] In step 204, a metal layer is deposited on the curved substrate, followed by stripping the dry film to form a metal pattern. In embodiments of the invention, the metal layer deposition can be accomplished using a physical vapor deposition process such as sputtering. The curved substrate is then immersed in a 1% NaOH solution to remove the dry film and its surface metal layer, leaving only the metal pattern deposited directly on the substrate surface.

[0055] This example utilizes flexible thin films for curved surface deposition, which has a short process flow, simple subsequent processes, good repeatability, and low cost.

[0056] Figure 3 A cross-sectional view of the process for fabricating a heat flow sensor structure by multilayer overlay on an insulating curved substrate is shown, according to another embodiment of the present invention. Figure 4 A process flow diagram is shown for fabricating a heat flow sensor structure by multilayer overlay on an insulating curved substrate according to another embodiment of the present invention.

[0057] First, in step 401, a film-laminating process is performed on the curved substrate. Before laminating, ensure the curved substrate is thoroughly cleaned, and take care to avoid air bubbles during the lamination process. After lamination, place the substrate in an oven to bake and remove excess air bubbles. In some embodiments of the present invention, film can be laminated only on the areas where the device is fabricated, leaving other areas unlaminated. In other embodiments of the present invention, film can be laminated on the entire surface of the curved substrate.

[0058] Next, in step 402, the first flexible mask is fixed onto the curved substrate. The first flexible mask is a flexible plate with a certain elastic deformation capability and a light-shielding pattern. In embodiments of the present invention, polyimide tape can be used to fix the first flexible mask onto the curved substrate to ensure close contact between the flexible mask and the curved substrate, preventing light leakage during the photolithography process. The material of the first flexible mask includes one or more of PET, PP, PC, PVC, and PDMS.

[0059] In step 403, the curved substrate is photolithographically etched and developed.

[0060] In step 404, a first metal layer is deposited on the curved substrate, followed by stripping the dry film to form a first metal pattern. In embodiments of the invention, the deposition of the first metal layer can be accomplished using a physical vapor deposition process such as sputtering. Then, the curved substrate is immersed in a 1% NaOH solution to remove the dry film and its surface metal layer, leaving only the first metal pattern deposited directly on the substrate surface.

[0061] Next, a second metal pattern is fabricated on the curved substrate with the first metal pattern. The fabrication process of the second metal pattern is similar to that of the first metal pattern. The difficulty lies in aligning the second flexible mask with the first metal pattern during the fabrication of the second metal pattern. Since the curved substrate is not a standard-sized and shaped semiconductor substrate, and the flexible mask used is not a standard mask, existing photolithography equipment cannot be used for mask alignment, photolithography, and other processes. Therefore, existing technologies can only form single-layer patterns on irregular structures and cannot achieve the fabrication of multi-layer, fine patterns. To address this problem, this invention provides a dedicated fixture for aligning and fixing irregular structures with flexible masks.

[0062] Figure 5 A specialized fixture for aligning irregularly shaped structures with flexible photomasks, according to an embodiment of the present invention, is shown. Figure 5 As shown, the special fixture includes a displacement stage 501, a workpiece fixture 502 fixed on the displacement stage 501, and a mask plate support 503 located above the workpiece fixture 502. During the alignment process, the irregularly shaped workpiece is fixed on the workpiece fixture 502, and the flexible mask plate is fixed on the mask plate support 503. The displacement stage 501 can perform up, down, forward, backward, left, right, and rotation movements, thereby moving the irregularly shaped workpiece and achieving alignment between the pattern on the irregularly shaped workpiece and the pattern on the flexible mask plate.

[0063] The special fixture of this invention enables the alignment of patterns on irregularly shaped workpieces with patterns on flexible photomasks. Specifically, [the following text is missing: "return"] Figure 3 and Figure 4The process flow shown includes step 405, where a film is applied to the curved substrate. Step 405 is similar to step 401. Care must be taken to avoid air bubbles during the film application process. After film application, the substrate is placed in an oven to remove excess air bubbles.

[0064] In step 406, the second flexible mask is aligned with the curved substrate using a special fixture under a yellow light microscope, and then fixed onto it. The second flexible mask is a flexible plate with a certain elastic deformation capability and a light-shielding pattern. In embodiments of the present invention, polyimide tape can be used to fix the second flexible mask onto the curved substrate to ensure close contact between the flexible mask and the curved substrate, preventing light leakage during the photolithography process. The material of the second flexible mask includes one or more of PET, PP, PC, PVC, and PDMS.

[0065] Then, the curved substrate is photolithographically etched and developed.

[0066] In step 407, a second metal layer is deposited on the curved substrate, followed by peeling off the dry film to form a second metal pattern. In embodiments of the invention, the deposition of the second metal layer can be accomplished using a physical vapor deposition process such as sputtering. Then, the curved substrate is immersed in a 1% NaOH solution to remove the dry film and its surface metal layer, leaving only the second metal pattern deposited directly on the substrate surface. The material of the second metal layer can be the same as or different from the material of the first metal layer.

[0067] In embodiments of the present invention, steps 405 to 407 can be repeated multiple times to form a multilayer metal layer pattern.

[0068] Next, in step 408, a film-laminating process is performed on the curved substrate. Step 408 is similar to step 401. Care must be taken to avoid air bubbles during the film-laminating process. After film lamination, place the substrate in an oven to remove excess air bubbles.

[0069] In step 409, the third flexible mask is aligned with the curved substrate using a special fixture under a yellow light microscope, and then fixed onto it. The third flexible mask is a flexible plate with a certain elastic deformation capability and a light-shielding pattern. In embodiments of the present invention, polyimide tape can be used to fix the third flexible mask onto the curved substrate to ensure close contact between the flexible mask and the curved substrate, preventing light leakage during the photolithography process. The material of the third flexible mask includes one or more of PET, PP, PC, PVC, and PDMS.

[0070] Then, the curved substrate is photolithographically etched and developed.

[0071] In step 410, a first thermal resistance layer is deposited on the curved substrate, followed by peeling off the dry film to form a first thermal resistance layer pattern. In embodiments of the invention, the deposition of the first thermal resistance layer can be accomplished using a physical vapor deposition process such as sputtering. Then, the curved substrate is immersed in a 1% NaOH solution to remove the dry film and the first thermal resistance layer on its surface, leaving only the first thermal resistance layer pattern directly deposited on the substrate surface. The material of the thermal resistance layer can be ceramic.

[0072] In embodiments of the present invention, steps 408 to 410 can be repeated multiple times to form a multilayer thermal resistance layer pattern.

[0073] In some embodiments of the present invention, when the surface undulations of the curved substrate exceed the adaptability range of the flexible mask, making it impossible for the flexible mask to achieve close contact with the curved substrate through elastic deformation, the light-blocking pattern of the flexible mask can be finely adjusted according to actual needs so that the projection of light passing through the mask is the expected shape. In this case, when fixing the mask to the surface of the curved substrate, it is necessary to first align the mask with the curved substrate.

[0074] It should be noted that the microfabrication method used in the above embodiments is only a specific embodiment of the present invention. The shape and size of the substrate, as well as the type of material layer on the curved surface to be deposited, can also be changed. For example, the deposition material can be metal, ceramic, etc. It is not limited to the description of the above examples, and all of them can achieve the purpose of the present invention.

[0075] This invention allows for the direct application of a dry film to the surface of irregularly shaped structures, using a flexible mask instead of a traditional hard metal mask, enabling the creation of intricate patterns on these surfaces. Furthermore, this invention is low-cost and offers flexible and convenient operation; its applications are increasingly evident in many areas.

[0076] Although various embodiments of the invention have been described above, it should be understood that they are presented by way of example only and not as limitations. It will be apparent to those skilled in the art that various combinations, modifications, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the breadth and scope of the invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined solely by the appended claims and their equivalents.

Claims

1. A method for fabricating thin-film microdevices on irregular structures, characterized in that, The irregular structure is a spherical structure, cylindrical structure, conical structure, or polygonal structure, including: Dry film photoresist is applied to irregularly shaped structures; The first flexible mask is fixed to the irregular structure by an adhesive layer, and the curvature of the flexible mask is consistent with that of the irregular structure. Photolithography and development are performed on irregularly shaped structures; A first material layer is deposited on an irregular structure, and then a dry film is peeled off to form a pattern of the first material layer. Dry film photoresist is applied to an irregular structure with a pattern of the first material layer; The second flexible mask plate is fixed onto the irregular structure; Photolithography and development of irregular structures; and A second material layer is deposited on the irregular structure, followed by peeling off the dry film to form a pattern of the second material layer. In this process, a special fixture is used to align the pattern of the irregular structure with the pattern on the second flexible mask under a yellow light microscope. When the surface undulations of the irregular structure exceed the adaptability range of the first and / or second flexible masks, making it impossible for the first and / or second flexible masks to achieve close contact with the irregular structure through elastic deformation, the light-blocking pattern of the flexible masks is finely adjusted according to actual needs so that the projection of light passing through the masks becomes the desired shape. The special fixture includes a displacement stage, a workpiece fixture fixed on the displacement stage, and a mask plate support located above the workpiece fixture. During the alignment process, the irregular structure is fixed on the workpiece fixture, the second flexible mask is fixed on the mask support, and the displacement stage drives the irregular structure to move, so as to align the pattern on the irregular structure with the pattern on the second flexible mask.

2. The method according to claim 1, characterized in that, It also includes a pretreatment process for irregular structures before applying dry film photoresist, the pretreatment process including polishing, grinding and cleaning.

3. The method according to claim 1, characterized in that, The first material layer is deposited by physical vapor deposition. Then, the irregular structure is immersed in a 1% (w / w) NaOH solution to remove the dry film and the first material layer on its surface, leaving only the pattern of the first material layer directly deposited on the surface of the irregular structure.

4. The method according to claim 1, characterized in that, The materials of the first flexible mask and / or the second flexible mask include one or more of PET, PP, PC, PVC, and PDMS.

5. The method according to claim 1, characterized in that, Dry film photoresist is applied only to certain surfaces of the irregularly shaped structure; and / or Apply pressure with rollers to assist in film application, then place in an oven to remove excess air bubbles.

6. The method according to claim 1, characterized in that, The first material layer and / or the second material layer include a metal layer and a ceramic layer.

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