Electrochemical deposition additive manufacturing method for copper column array with interlocking anchoring structure

Abstract

The invention provides an electrochemical deposition additive manufacturing method for a copper column array with an interlocking anchoring structure, which comprises the following steps of: uniformly coating glue on the surface of a substrate, and patterning a mask plate; performing deep silicon etching on the substrate, and generating a sunken structure on the inner wall of the etching hole; forming a metal layer on the upper surface of the substrate, and dividing the substrate into a plurality of small blocks; a printing pool solution and printing ink are provided, and the hollow atomic force probe channel is filled with the printing ink; filling a printing pool with a printing pool solution, pressing and fixing the small substrate block in the center of the printing pool by using a graphite electrode, and controlling voltage applied to a working electrode until current feedback is stable; the printing probe is moved into the printing liquid; obtaining a surface etching hole structure of the small substrate block through a hollow atomic force probe, and setting a printing structure and position parameters; and controlling the hollow atomic force probe to perform suspended jet ion flow deposition on the etching holes to complete hole filling and printing of a metal three-dimensional structure. The bonding strength of the metal three-dimensional array structure and the substrate can be improved.

Description

Technical Field

[0001] The present application relates to the field of metal additive manufacturing, and in particular, to a method for electrochemical deposition additive manufacturing of a copper pillar array with an interlocking anchoring structure. Background Art

[0002] In metal additive manufacturing research, material voxels are stacked layer by layer through welding, deposition, bonding or chemical means to achieve the target three-dimensional structure. Since complex structures are supported by the combination of the bottom printed voxels and the substrate, high substrate bonding strength is usually required. Localized electrochemical deposition technology forms a directional local electric field between the micro-anode and the cathode substrate to induce the reduction and deposition of metal ions in the electrolyte, and then prints a three-dimensional metal microstructure on the substrate. In theory, the minimum cross-sectional size of the metal microstructure manufactured by the localized growth electrodeposition technology is determined by the shape of the micro-anode end surface, and it has the greatest potential in the forming of micro-scale metal parts. Therefore, many scholars have conducted extensive research on the localized growth electrodeposition technology to form metal parts.

[0003] Currently, forming metal parts using localized electrodeposition technology is an important technical means for micro-scale additive manufacturing of metal parts. A search revealed a Chinese invention patent application with publication number CN111781402A, which discloses an additive manufacturing device and method based on localized electrodeposition using a hollow AFM probe. This patent successfully achieves forward micro-additive manufacturing of submicron-scale metal three-dimensional cantilever structures by integrating localized electrochemical technology with microfluidics and AFM probe technology. In recent years, this technology has been used to process precision metal parts both domestically and internationally, but there are no reports on research into the strength of the bond between the structure and the substrate.

[0004] A search revealed a Chinese invention patent application with publication number CN109152240A, which discloses a printed circuit board with a metallized keyhole structure and a hole metallization process. By etching away the base copper surrounding the hole opening, the conductive film deposition area on the substrate is increased. The printed circuit board is then treated with a conductive film and then electroplated with copper to form a keyhole-shaped metallized hole. While this prior art can achieve keyhole-shaped metallized holes, it is limited to printed circuit boards or similar two-dimensional structures. Summary of the Invention

[0005] In view of one of the defects in the prior art, the purpose of this application is to provide an electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure.

[0006] The present application provides a method for electrochemical deposition additive manufacturing of a copper pillar array having an interlocking anchoring structure, comprising:

[0007] Spreading a photoresist on the surface of the substrate and patterning the photoresist on the substrate using an ultraviolet exposure system;

[0008] Performing deep silicon etching on the substrate to produce a concave structure on the inner wall of the etched hole;

[0009] removing the photoresist, forming a metal layer on the upper surface of the substrate, and dividing the substrate into a plurality of small blocks;

[0010] providing a printing pool solution and printing ink, and filling the printing ink into the hollow atomic force probe channel;

[0011] Filling the printing pool with the printing pool solution to a preset liquid level, pressing the substrate block to fix it in the center of the printing pool using a graphite electrode, and controlling the voltage applied to the working electrode by the three-electrode system until the current feedback is stable;

[0012] The printing probe is moved into the printing liquid, and the etched hole structure of the substrate surface is obtained through the hollow atomic force probe, and the printing structure and position parameters are set according to the etched hole structure;

[0013] According to the printing structure and position parameters, the hollow atomic force probe is controlled by optical feedback to fill the etched holes and print the metal three-dimensional structure.

[0014] Optionally, performing deep silicon etching on the substrate to generate a recessed structure on the inner wall of the etching hole includes: generating a recessed structure with concave and convex threads on the inner wall of the etching hole by adjusting the number of etchings and the etching and passivation times.

[0015] Optionally, deep silicon etching is performed on the substrate to generate a recessed structure on the inner wall of the etching hole, wherein the depth of the etching hole is 3-15 μm.

[0016] Optionally, a metal layer is formed on the upper surface of the substrate, wherein: the metal layer is formed by sputtering, and the metal layer is a Cu layer.

[0017] Optionally, a printing pool solution and printing ink are provided, wherein: the printing pool solution is H2SO4 solution, and the printing ink is CuSO4 solution.

[0018] Optionally, before filling the printing pool with the printing pool solution to a preset liquid level, the method includes: ultrasonically cleaning the substrate small pieces, and selecting the substrate small pieces that are intact after cleaning.

[0019] Optionally, the printing pool solution is used to fill the printing pool to a preset liquid level, wherein: the liquid level of the printing pool solution is 1-2 mm higher than the counter electrode of the three-electrode system;

[0020] The voltage applied to the working electrode by the three-electrode system is controlled until the current feedback is stable, wherein the applied voltage is -0.45V to -0.54V and the current feedback is less than 1mA.

[0021] Optionally, before moving the printing probe into the printing liquid to complete the laser focus calibration and signal feedback detection operations, the method includes: checking the airtightness of the joint between the printing probe and the hollow atomic force probe.

[0022] Optionally, the printing structure and position parameters are set according to the etched hole structure, wherein the printing structure and position parameters include at least one of a feedback threshold, a response time threshold, a printing height, a probe pressure, and a voxel spacing.

[0023] Optionally, after completing the pore filling and printing of the metal three-dimensional structure by controlling the hollow atomic force probe to perform suspended jet ion flow deposition on the etched holes according to the printing structure and position parameters through optical feedback, it also includes: changing the printing position to print to obtain a metal three-dimensional printed structure array.

[0024] The electrochemical deposition additive manufacturing method for copper pillar arrays with interlocking anchoring structures provided in this application uses deep silicon etching of the substrate to create recessed structures on the inner walls of the etched holes. During the structure printing process, based on the principles of electrochemical deposition and high-precision optical feedback, the pore structure is highly filled and the metal three-dimensional structure is printed, thereby improving the bonding strength between the metal three-dimensional structure and the substrate. Compared with traditional methods, this method has mild conditions and does not require post-processing. The high substrate bonding strength of the metal three-dimensional printed structure makes it possible to stably prepare complex structures, effectively avoiding problems such as frequent and large-scale structural collapse that lead to low production efficiency.

[0025] Other technical effects brought about by the additional features will be further explained in the corresponding embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0027] Figure 1 The present invention is a flow chart showing a method for electrochemical deposition additive manufacturing of a copper pillar array with an interlocking anchoring structure according to an exemplary embodiment;

[0028] Figure 2 FIG1 is a process flow chart of an electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to an exemplary embodiment;

[0029] Figure 2 Middle: 1 is the mask, 2 is the substrate, 3 is the photolithography system, 4 is the photoresist, 5 is the deep reactive ion etching system, 6 is the metal layer, 7 is acetone, 8 is the ultrasonic cleaning machine, 9 is the printing bath solution, 10 is the three-electrode system, 11 is the hollow atomic force probe, and 12 is the printing probe;

[0030] Figure 3 is a schematic structural diagram of an electrochemical deposition additive manufacturing device according to an exemplary embodiment;

[0031] Figure 4 Schematic diagram of forming a printing probe and a copper column according to an exemplary embodiment;

[0032] Figure 5 The figures are scanning electron microscope images of silicon etched holes and copper pillar array filled printed samples at different magnifications according to an exemplary embodiment, and Figure (b) is a partial enlarged view of Figure (a). DETAILED DESCRIPTION

[0033] The present application is described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present application, but are not intended to limit the present application in any form. It should be noted that, without departing from the concept of the present application, a number of variations and improvements may be made by those skilled in the art, and these all fall within the scope of protection of the present application. Parts not described in detail in the following examples may be implemented using existing technologies.

[0034] Traditional printing strategies use flat surfaces as the printing substrate, resulting in unstable structures and prone to collapse. This makes reliable applications difficult when faced with high aspect ratios and high mechanical strength requirements. To address these issues, the present invention provides an electrochemical deposition additive manufacturing method for copper pillar arrays with interlocking anchoring structures to address these issues.

[0035] Reference Figures 1 to 3 As shown, in one embodiment of the present application, a method for electrochemical deposition additive manufacturing of a copper pillar array having an interlocking anchoring structure includes:

[0036] Step S1: applying a smear on the surface of a substrate and patterning the substrate using a photolithography system;

[0037] Step S2: performing deep silicon etching on the substrate to generate a concave structure on the inner wall of the etching hole;

[0038] Step S3: removing the photoresist, forming a metal layer on the upper surface of the substrate, and dividing the substrate into a plurality of small blocks;

[0039] Step S4: providing a printing pool solution and printing ink, and filling the hollow atomic force probe channel with the printing ink;

[0040] Step S5: Filling the printing pool with a printing pool solution to a preset liquid level, pressing the substrate block to the center of the printing pool using the counter electrode of the three-electrode system, and controlling the voltage applied to the working electrode by the three-electrode system until the current feedback is stable;

[0041] Step S6: Using the bottom optical microscope for real-time observation, the hollow atomic force probe is aligned and grasped, and the printing probe is moved into the printing liquid to complete the laser focus calibration and signal feedback detection operations; the hollow atomic force probe is used to obtain the etched hole structure on the surface of the substrate block, and the printing structure and position parameters are set according to the etched hole structure;

[0042] Step S7: Based on the printing structure and position parameters, the hollow atomic force probe is controlled by optical feedback to perform suspended jet ion flow deposition on the etched holes to complete pore filling and printing of the metal three-dimensional structure.

[0043] Specifically, in order to address the problem that the structure of parts formed by traditional printing strategies is prone to collapse and it is impossible to achieve complex structures with large aspect ratios, in order to increase the bonding strength between the structure and the substrate (i.e., adhesion strength), deep silicon etching process (deep reactive ion etching process) and electrochemical deposition additive manufacturing technology are used to form interlocking structures by filling deep silicon etching holes, thereby improving the connection strength and stability of metal three-dimensional printed structures (such as printed copper pillars), thereby providing key technical support for high-end manufacturing fields such as TSV advanced packaging and micro-aerospace parts.

[0044] The substrate can be a silicon wafer, or other commonly used micro-nanofabrication substrates. Photoresist is spin-coated on the substrate. During deep silicon etching, alternating etching and passivation processes create silicon etched holes with threaded sidewalls. This recessed structure significantly enhances the mechanical interlocking strength between the subsequently deposited copper pillars and the substrate.

[0045] In step S6, a bottom-up optical mirror, located below the print platform, assists the print probe in accurately positioning and grasping the hollow atomic force probe. After grasping the hollow atomic force probe, the print probe, carrying the hollow atomic force probe, moves into the print pool. Laser focus feedback testing is used to calibrate and test the voxel printing laser feedback function; this technology is subsequently used to monitor the voxel printing progress during the printing process.

[0046] In the electrochemical deposition metal additive manufacturing device, the flow controller is connected to the pipe in the hollow atomic force probe cantilever, and controls the flow rate and flow of the printing ink through pressure; the laser emitter and photodetector form an optical feedback system, which is located in the printing probe. It emits laser to the surface of the printed voxel and receives feedback signals to detect the formation of individual voxels, thereby advancing the printing process.

[0047] The prior art CN111781402A can only realize the preparation of three-dimensional structures on a complete planar substrate. The above-mentioned embodiment of the present application can use the method of suspended jet ion flow deposition to fill a substrate with a porous structure, and then continue to print on it to form a three-dimensional structure with an interlocking anchoring structure to enhance the bonding strength between the substrate and the structure, thereby facilitating the formation of complex three-dimensional metal structures on the filled holes.

[0048] In the above-described embodiments of this application, deep silicon etching of the substrate creates a recessed structure on the inner wall of the etched hole. During the structure printing process, based on the principles of electrochemical deposition and high-precision optical feedback, the pore structure is highly filled and the metal three-dimensional structure is printed, thereby improving the bonding strength between the metal three-dimensional structure and the substrate. Compared with traditional methods, this method has mild conditions and does not require post-processing. The high substrate bonding strength of the metal three-dimensional printed structure makes it possible to stably prepare complex structures, effectively avoiding problems such as frequent and large-scale structural collapse that lead to low production efficiency.

[0049] In order to form a concave-convex thread structure of a certain depth on the inner wall of the etched hole, in some specific embodiments of the present application, in step S2, a concave structure with a concave-convex thread is generated on the inner wall of the etched hole by adjusting the number of etching times, etching and passivation time.

[0050] Specifically, for silicon substrates, deep reactive ion etching is a reactive ion deep silicon etching system, which uses a reactive ion deep silicon etching system in combination with a photomask to perform Bosch process deep silicon etching. After two to ten cycles, while adjusting the etching and passivation time, the depth of the etched hole is 3-15μm, and the inner wall depth is within 1-1.5μm.

[0051] It should be noted that the hole depth takes into account that the limit of the hollow atomic force probe's penetration depth is about 15μm, and the inner wall depth is the limit of deep silicon etching technology; the hole depth is positively correlated with the inner wall depth, and the larger the two values, the greater the enhanced bonding strength.

[0052] In the above-mentioned embodiments of the present application, by regulating the etching process, the inner wall structure of the pores can be controlled, thereby further improving the bonding strength between the metal three-dimensional printed structures such as copper pillars and the substrate surface.

[0053] In order to obtain a conductive printed substrate, in some specific embodiments of the present application, in step S3, a metal layer is formed by sputtering, and the metal layer is a Cu layer.

[0054] Specifically, a sputtering machine is used to form a Ti / Cu seed layer on a substrate, such as a silicon wafer. The Ti layer serves as an adhesion layer, and the Cu layer serves as a surface conductive layer. A copper thin film is then deposited to ensure conductivity between the substrate surface and the inside of the pores. A dicing machine is then used to divide the substrate into small samples.

[0055] For example, the thickness of the Ti layer is ∼13 nm, the thickness of the Cu layer is ∼100 nm, and the side length of the square sample is 15-25 mm.

[0056] The above-mentioned embodiment of the present application utilizes a deep reactive ion etching process, selects appropriate etching and passivation time and number of cycles, performs side wall thread line width and number of turns superposition, and then performs metal layer sputtering to realize the preparation of the printed substrate.

[0057] It should be noted that the metal layer can also be prepared by other micron-level metal thin film preparation methods. The dicing process can also use other micron-level high-precision silicon wafer cutting equipment.

[0058] In some specific embodiments of the present application, in step S4, the printing pool solution is H2SO4 solution, and the printing ink is CuSO4 solution.

[0059] Specifically, deionized water, sulfuric acid solution, and copper sulfate solution are used in a certain proportion to prepare the required solution, such as 100 mL of 0.8 M CuSO4 solution and 0.5 M H2SO4 solution with a pH of 3.

[0060] The printed ink is filtered using a filter (pore size ~0.45μm) to remove large particles that can clog the hollow AFM. The process of transferring and filling the hollow AFM using a pipette involves injecting the previously prepared metal printing ink into the hollow AFM and applying a certain pressure, such as 400-500mbar, using a flow control system to allow the solution to fill the probe channel.

[0061] In order to obtain a clean substrate to improve the printing effect, in some specific embodiments of the present application, before step S5, it includes: using an ultrasonic cleaning machine to ultrasonically clean the substrate small pieces, and selecting the substrate small pieces that are intact after cleaning.

[0062] Specifically, the substrate is first cleaned with an acetone solution, then immersed in a deionized water solution, and cleaned with an ultrasonic cleaner for 5 minutes. The substrate with a clean and scratch-free surface after ultrasonic cleaning is selected, and the clean substrate is fixed on the printing platform.

[0063] In some specific embodiments of the present application, in step S5, the printing pool is cleaned with deionized water and filled with a printing pool solution (i.e., an electrolyte) to a suitable liquid level. The three-electrode system includes a counter electrode, a working electrode, and a reference electrode, and the liquid level of the printing pool solution is 1-2 mm higher than the counter electrode (e.g., a graphite sheet) of the three-electrode system. The voltage applied to the working electrode by the three-electrode system is controlled until the current feedback is stable, wherein the applied voltage is -0.45 V to -0.54 V and the current feedback is less than 1 mA, thereby achieving copper deposition under the three-electrode system.

[0064] Exemplarily, the appropriate liquid level is 12-15 mm, so as to be higher than the liquid level of the counter electrode to form a complete three-electrode system; the reduction potential is -0.50 V and is applied to the working electrode.

[0065] It should be noted that the above parameters can be adjusted accordingly according to the requirements for structure printing speed and surface roughness.

[0066] In order to ensure the printing effect, in some specific embodiments of the present application, in step S6, before moving the printing probe into the printing liquid to complete the laser focus calibration and signal feedback detection operations, it includes: checking the airtightness of the joint between the printing probe and the hollow atomic force probe.

[0067] Specifically, by observing the lower optical microscope image, the hollow atomic force probe is aligned and grasped, 20mbar air pressure is applied, and the air tightness of the joint between the printing probe and the hollow atomic force probe is checked by checking the feedback air pressure (test pressure <0.3mbar). Use a certain pressure to pre-fill the hollow atomic force probe (400-500mbar). Move the printing probe into the printing liquid to complete the laser focus calibration and signal feedback detection operation. Preferably, the detection feedback pressure should be less than 0.3mbar.

[0068] In order to determine the printing parameters, in some specific embodiments of the present application, in step S7, an optical microscope is used for positioning, and the hollow atomic force probe is gradually approached to the specified position of the substrate by macroscopically and microscopically adjusting the precision Z-axis system. The cantilever of the hollow AFM probe accurately senses the presence of atomic force, maps and characterizes the structure of the pore structure area on the surface of the substrate, and feeds back the mapping results in the computer program, and sets the printing structure and position parameters in combination with the mapping results. The copper pillar structure designed by the software is placed in the etched hole, and a suitable height from the bottom is set for the hollow atomic force probe. The printing structure and position parameters include at least one of the feedback threshold, the response time threshold, the printing height, the probe pressure, and the voxel spacing, so that the lower end of the printed structure completely fills the substrate pores as completely as possible and the upper copper pillar maintains alignment and a small line width.

[0069] Specifically, taking the formation of copper pillars as an example, the response time threshold is set according to the depth of the hole to adjust the filling time limit, and the printing height and probe pressure are set for the filling section (i.e., the structure deposited in the filling hole) and the structure section (i.e., the specific structure above the filling section) respectively, so that the lower end of the printed structure can completely fill the substrate pores as completely as possible and form the height of the copper pillar. The voxel spacing is set to control the surface roughness and line width of the copper pillar structure. Again, through macroscopic and microscopic adjustment of the precision Z-axis system, the hollow atomic force probe is gradually brought close to the mapped surface of the substrate surface, and the probe is controlled to perform ultra-precise localized electrochemical deposition in the hole structure area. The metal ions are reduced to metal atoms through electrochemical action and enter the metal lattice to form a metal solid, thereby achieving pore filling and copper pillar printing.

[0070] In step S7, using the principles of electrochemical deposition and optical feedback, the probe is first controlled to perform suspended jet ion flow deposition above the bottom of the hole to complete pore filling, and then the metal three-dimensional structure is printed above the filling section to achieve controllable 3D printing and complete the printing of metal three-dimensional structures with high substrate bonding strength.

[0071] For example, the response time threshold range is 5-30 min, the filling segment height range is 5-20 μm, the probe pressure range is 300-800 mbar, the structure segment height range is 0-1000 μm, the probe pressure range is 20-100 mbar, and the voxel spacing setting range is 0.5-1.0 μm, thereby obtaining copper pillars with high bonding strength and structural alignment, such as Figure 4 and Figure 5 By adjusting the parameters of the printing program, the diameter, height, and surface roughness of the copper pillars can be adjusted.

[0072] It should be noted that in some other embodiments, in addition to the columnar shape, the three-dimensional printed structure can also be of other shapes.

[0073] In the above-mentioned embodiment of the present application, probe alignment and grasping, hollow atomic force probe pre-filling, laser focusing calibration and signal feedback detection operations are performed in sequence in the printing process, optical positioning and mapping of the substrate pore structure are used, position parameters are set, and the probe is controlled to perform suspended jet ion flow deposition pore filling and structure printing, so that the lower end of the printed structure fills the substrate pores as completely as possible and forms a metal three-dimensional printed structure.

[0074] In order to obtain a printed structure array, in some specific embodiments of the present application, after step S7, the method further includes: changing the printing position to perform printing to obtain a metal three-dimensional printed structure array.

[0075] For example, after preparing copper pillars with high bonding strength and structural alignment, the printing position is changed and moved to another etched hole for printing. The above structure is repeated several times, and then a copper pillar array with an interlocking anchoring structure is obtained.

[0076] It should be noted that the array printing shape can be any one of an array of squares, array of circles, array of triangles, etc.

[0077] The micro-nanofabrication methods described in the aforementioned embodiments of this application achieve highly filled pore structures and the printing of metal 3D structures, such as copper pillars with micron-scale diameters. These methods can also be fabricated in arrays and batches, achieving smaller line widths under controllable conditions. The interlocking anchoring structures of micron-scale metal 3D structures with strong substrate adhesion prepared in this application can be applied to research and manufacturing fields such as TSV advanced packaging and micro-aerospace parts.

[0078] The preferred features of the above embodiments can be used alone in any embodiment, or in any combination without conflict. In addition, parts not described in detail in the embodiments can be implemented using existing technologies.

[0079] The following further illustrates the present application in conjunction with specific application examples / comparative examples to facilitate a better understanding of the above technical solutions of the present application. It should be understood that the following are merely partial examples and are not intended to limit the present application.

[0080] Example 1

[0081] A method for preparing high-substrate bonding strength copper pillars and their arrays based on deep silicon etching and electrochemical deposition additive manufacturing is described. The method operation process can be divided into nine steps, which are described in detail as follows:

[0082] The first step, such as Figure 2 (a) Selecting a silicon wafer and designing a photomask, using a photolithography system to select a silicon wafer and design a photomask, applying a smear on the silicon wafer surface, and patterning the photoresist using photolithography;

[0083] The second step is Figure 2 (b) Using a reactive ion deep silicon etching system combined with a photomask to perform Bosch deep silicon etching, two cycles of etching were performed to produce a recessed structure of approximately 1 μm on the inner wall of the etched hole, resulting in a hole depth of 3 μm.

[0084] The third step, such as Figure 2 (c) The substrate prepared in the previous step was processed using a sputtering system to form a 13 nm Ti layer and a 100 nm Cu layer on the surface. The substrate was then divided into squares with a side length of 15 mm using a dicing saw.

[0085] Step 4: Prepare 100 mL of 0.8M CuSO₄ solution and 0.5M H₂SO₄ solution (pH 3) for use as the metal printing ink and the printing pool solution, respectively. Filter the printing ink using a filter loaded with a 450 nm membrane. Then, inject the previously prepared metal printing ink (0.8M CuSO₄ aqueous solution) into the hollow atomic force probe and apply a constant pressure using a flow control system to ensure that the solution fills the probe channel.

[0086] Step 5: Figure 2 (d) Cleaning the substrate with an acetone solution, and then immersing the substrate in a deionized water solution for 5 minutes using an ultrasonic cleaning machine, and selecting the substrate with a clean and scratch-free surface after ultrasonic cleaning;

[0087] Step 6: Figure 2 (e) Rinse the printing pool with deionized water and fill it with the prepared printing pool solution (0.5M H₂SO₄ aqueous solution) until the liquid level is 1-2 mm above the graphite counter electrode. Use a graphite sheet to hold the substrate in place in the center of the printing pool. Apply a -0.45 V voltage to the working electrode using a computer-controlled three-electrode system and wait several minutes for the current feedback to stabilize (<1 mA).

[0088] Step 7: Use the bottom optical microscope to observe in real time, align and grasp the hollow atomic force probe, apply 20mbar air pressure to check the airtightness of the joint between the printed probe and the hollow atomic force probe (test pressure <0.3mbar). Use 500mbar pressure to pre-fill the hollow atomic force probe tip, move the printed probe into the printing liquid to complete the laser focus calibration and signal feedback detection operation;

[0089] In the eighth step, the optical microscope is used for positioning. The precision Z-axis system is adjusted macroscopically and microscopically to gradually bring the hollow atomic force probe close to the specified position of the substrate. The hollow AFM probe is used to map and characterize the structure of the pore structure area on the substrate surface. The mapping results are fed back to the computer program, and the printing structure and position parameters are set based on the mapping results.

[0090] Step 9: Figure 2 (f) The printed copper pillar height segmentation is set to 5-15 μm, the height from the bottom is set to 15 μm, the probe pressure segmentation is set to 20-300 mbar, the response time is set to 5 min, and the voxel spacing is set to 0.5 μm. A copper pillar array with a height of 20 μm is prepared by printing.

[0091] Example 2

[0092] A method for preparing copper pillars and arrays with high substrate bonding strength based on deep silicon etching and electrochemical deposition additive manufacturing is described. The method operation process can be subdivided into nine steps, which are described in detail as follows:

[0093] The first step, such as Figure 2 (a) Selecting a silicon wafer and designing a photomask, using a photolithography system to select a silicon wafer and design a photomask, applying a smear on the silicon wafer surface, and patterning the photoresist using photolithography;

[0094] The second step is Figure 2 (b) Using a reactive ion deep silicon etching system combined with a photomask to perform Bosch deep silicon etching, the etching was continued for five cycles, resulting in a concave structure of approximately 1.3 μm on the inner wall of the etched hole, with a hole depth of 8 μm.

[0095] The third step, such as Figure 2 (c) The substrate prepared in the previous step was processed using a sputtering system to form a 13 nm Ti layer and a 100 nm Cu layer on the surface. The substrate was then divided into squares with a side length of 15 mm using a dicing saw.

[0096] Step 4: Prepare 100 mL of 0.8M CuSO₄ solution and 0.5M H₂SO₄ solution (pH 3) for use as the metal printing ink and the printing pool solution, respectively. Filter the printing ink using a filter loaded with a 450 nm membrane. Then, inject the previously prepared metal printing ink (0.8M CuSO₄ aqueous solution) into the hollow atomic force probe and apply a constant pressure using a flow control system to ensure that the solution fills the probe channel.

[0097] Step 5: Figure 2 (d) Cleaning the substrate with an acetone solution, and then immersing the substrate in a deionized water solution for 5 minutes using an ultrasonic cleaning machine, and selecting the substrate with a clean and scratch-free surface after ultrasonic cleaning;

[0098] Step 6: Figure 2 (e) Rinse the printing pool with deionized water and fill it with the previously prepared printing pool solution (0.5M H₂SO₄ aqueous solution) until the liquid level is 1-2 mm above the graphite counter electrode. Use a graphite sheet to hold the substrate in place in the center of the printing pool. Apply a -0.50 V voltage to the working electrode using a computer-controlled three-electrode system and wait several minutes for the current feedback to stabilize (<1 mA).

[0099] Step 7: Align and grasp the hollow atomic force probe by observing the lower optical microscope image, apply 20mbar air pressure to check the airtightness of the joint between the printed probe and the hollow atomic force probe (test pressure <0.3mbar). Use 500mbar pressure to pre-fill the hollow atomic force probe tip; move the printed probe into the printing liquid to complete the laser focus calibration and signal feedback detection operations;

[0100] In the eighth step, the optical microscope is used for positioning. The precision Z-axis system is adjusted macroscopically and microscopically to gradually bring the hollow atomic force probe close to the specified position of the substrate. The hollow AFM probe is used to map and characterize the structure of the pore structure area on the substrate surface. The mapping results are fed back to the computer program, and the printing structure and position parameters are set based on the mapping results.

[0101] Step 9: Figure 2 (f) The printed copper pillar height segmentation is set to 10-30 μm, the height from the bottom is set to 30 μm, the probe pressure segmentation is set to 20-500 mbar, the response time is set to 10 min, the voxel spacing is set to 1 μm, and a copper pillar array with a height of 40 μm is prepared by printing.

[0102] Example 3

[0103] A method for preparing high-substrate bonding strength copper pillars and their arrays based on deep silicon etching and electrochemical deposition additive manufacturing is described. The method operation process can be divided into nine steps, which are described in detail as follows:

[0104] The first step, such as Figure 2 (a) Selecting a silicon wafer and designing a photomask, using a photolithography system to select a silicon wafer and design a photomask, applying a smear on the silicon wafer surface, and patterning the photoresist using photolithography;

[0105] The second step is Figure 2 (b) Using a reactive ion deep silicon etching system combined with a photomask to perform Bosch deep silicon etching, the etching cycle was continued for ten times, resulting in a concave structure of about 1.5 μm on the inner wall of the etched hole, and the hole depth was 15 μm.

[0106] The third step, such as Figure 2 (c) The substrate prepared in the previous step was processed using a sputtering system to form a 13 nm Ti layer and a 100 nm Cu layer on the surface. The substrate was then divided into squares with a side length of 15 mm using a dicing saw.

[0107] Step 4: Prepare 100 mL of 0.8M CuSO₄ solution and 0.5M H₂SO₄ solution (pH 3) for use as the metal printing ink and the printing pool solution, respectively. Filter the printing ink using a filter loaded with a 450 nm membrane. Then, inject the previously prepared metal printing ink (0.8M CuSO₄ aqueous solution) into the hollow atomic force probe and apply a constant pressure using a flow control system to ensure that the solution fills the probe channel.

[0108] Step 5: Figure 2 (d) Cleaning the substrate with an acetone solution, and then immersing the substrate in a deionized water solution for 5 minutes using an ultrasonic cleaning machine, and selecting the substrate with a clean and scratch-free surface after ultrasonic cleaning;

[0109] Step 6: Figure 2 (e) Rinse the printing pool with deionized water and fill it with the previously prepared printing pool solution (0.5M H₂SO₄ aqueous solution) until the liquid level is 1-2 mm above the graphite counter electrode. Use a graphite sheet to hold the substrate in place in the center of the printing pool. Apply a -0.54 V voltage to the working electrode using a computer-controlled three-electrode system and wait several minutes for the current feedback to stabilize (<1 mA).

[0110] Step 7: Align and grasp the hollow atomic force probe by observing the lower optical microscope image, apply 20mbar air pressure to check the airtightness of the joint between the printed probe and the hollow atomic force probe (test pressure <0.3mbar). Use 500mbar pressure to pre-fill the hollow atomic force probe tip, move the printed probe into the printing liquid to complete the laser focus calibration and signal feedback detection operation;

[0111] In the eighth step, the optical microscope is used for positioning. The precision Z-axis system is adjusted macroscopically and microscopically to gradually bring the hollow atomic force probe close to the specified position of the substrate. The hollow AFM probe is used to map and characterize the structure of the pore structure area on the substrate surface. The mapping results are fed back to the computer program, and the printing structure and position parameters are set based on the mapping results.

[0112] Step 9: Figure 2 (f) The printed copper pillar height segmentation is set to 20-60 μm, the height from the bottom is set to 60 μm, the probe pressure segmentation is set to 40-800 mbar, the response time is set to 30 min, the voxel spacing is set to 1.5 μm, and a copper pillar array with a height of 80 μm is prepared by printing.

[0113] The above describes some specific embodiments of the present application. It should be understood that the present application is not limited to the specific embodiments described above, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the substantive content of the present application. The above preferred features may be used in any combination as long as they do not conflict with each other.

Claims

1. A method for electrochemical deposition additive manufacturing of a copper pillar array with an interlocking anchoring structure, characterized in that: include: Spreading a photoresist on the surface of a substrate, and patterning the photoresist on the substrate using a photolithography system; Performing deep silicon etching on the substrate to produce a concave structure on the inner wall of the etched hole; removing the photoresist, forming a metal layer on the upper surface of the substrate, and dividing the substrate into a plurality of small blocks; providing a printing pool solution and printing ink, and filling the printing ink into the hollow atomic force probe channel; Filling the printing pool with the printing pool solution to a preset liquid level, pressing the substrate block to fix it in the center of the printing pool using a graphite electrode, and controlling the voltage applied to the working electrode by the three-electrode system until the current feedback is stable; The printing probe is moved into the printing liquid, and the etched hole structure of the substrate surface is obtained through the hollow atomic force probe, and the printing structure and position parameters are set according to the etched hole structure; According to the printing structure and position parameters, the hollow atomic force probe is controlled by optical feedback to fill the etched holes and print the metal three-dimensional structure.

2. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: The deep silicon etching of the substrate to generate a concave structure on the inner wall of the etching hole includes: adjusting the number of etchings and the etching and passivation time to generate a concave structure with concave and convex threads on the inner wall of the etching hole.

3. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: The substrate is subjected to deep silicon etching to generate a concave structure on the inner wall of the etching hole, wherein the depth of the etching hole is 3-15 μm.

4. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: A metal layer is formed on the upper surface of the substrate, wherein the metal layer is formed by sputtering and is a Cu layer.

5. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: The printing pool solution and printing ink are provided, wherein: the printing pool solution is H2SO4 solution, and the printing ink is CuSO4 solution.

6. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: Before the printing pool solution is filled to a preset liquid level, the method includes: ultrasonically cleaning the substrate small pieces, and selecting the substrate small pieces that are intact after cleaning.

7. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: The printing pool solution is filled into the printing pool to a preset liquid level, wherein the liquid level of the printing pool solution is 1-2 mm higher than the counter electrode of the three-electrode system; The voltage applied to the working electrode by the three-electrode system is controlled until the current feedback is stable, wherein the applied voltage is -0.45V to -0.54V and the current feedback is less than 1mA.

8. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: Before the printing probe is moved into the printing liquid to complete the laser focus calibration and signal feedback detection operations, the process includes: checking the airtightness of the joint between the printing probe and the hollow atomic force probe.

9. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: The printing structure and position parameters are set according to the etched hole structure, wherein the printing structure and position parameters include at least one of a feedback threshold, a response time threshold, a printing height, a probe pressure, and a voxel spacing.

10. The electrochemical deposition additive manufacturing method for a copper pillar array with an interlocking anchoring structure according to claim 1, characterized in that: After the pore filling and the printing of the metal three-dimensional structure are completed by controlling the hollow atomic force probe to perform suspended jet ion flow deposition on the etched holes according to the printing structure and position parameters through optical feedback, it also includes: changing the printing position to print to obtain a metal three-dimensional printed structure array.

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