Filling process and filling equipment for micropores in interconnection structure

Abstract

The invention belongs to the technical field of electronic materials and microelectronic packaging, and particularly relates to a filling process and filling equipment for micropores in an interconnection structure, and the filling process comprises the following steps: A, preparing a core-shell microcapsule; wherein the core-shell microcapsule comprises a liquid metal inner core and a conductive shell layer which are sequentially arranged from inside to outside, and the raw material of the liquid metal inner core comprises liquid metal with the melting point smaller than 30 DEG C; b, uniformly mixing copper nanoparticles, core-shell microcapsules, a dispersing agent and water to obtain composite filling slurry; wherein the sintering temperature of the copper nanoparticles is lower than the decomposition temperature of the conductive shell layer; and C, filling micropores in the interconnection structure with the composite filling slurry, and calcining in an inert atmosphere. According to the filling technology for the micropores in the interconnection structure, the micropores can be effectively filled, conductive self-repairing can be achieved on microcracks generated in the follow-up using process, and therefore the long-term reliability of the interconnection structure is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electronic materials and microelectronic packaging, and particularly relates to a filling process of micropores in an interconnection structure and a filling device thereof. BACKGROUND

[0002] With the increasingly wide application of electronic products, the demand for small and powerful integrated circuits and interconnection structures such as circuit boards is also increasing. In the manufacturing process of the interconnection structure, micropores (including through holes and / or blind holes) with metallized pore walls are usually arranged on each layer of the interconnection structure, and the interconnection between the layers is realized by a filling method, thereby reducing the time delay, reducing the energy consumption and improving the integration, which plays a crucial role in the fields of advanced packaging technologies such as 2.5D / 3D packaging, wafer-level chip-size packaging and system-level packaging.

[0003] The traditional filling method mainly relies on electroplating copper process. Although the technology is mature, the process has inherent defects such as complex process and long time-consuming, and because the convection of the electroplating solution in the micropore is uneven, defects such as hole filling and clamping are easily generated, which affects the conductive reliability of the product.

[0004] In order to overcome the above-mentioned defects, the existing technology has appeared a low-temperature sintering filling process based on nano-metal particles (especially copper nano-particles). This method fills copper nano-particle slurry in the micropore and then sintering, and uses the high surface energy of copper nano-particles to realize densification, so as to obtain a filling body with excellent conductivity and realize effective filling of the micropore.

[0005] However, both the electroplating copper process and the nano-metal particle sintering forming process face serious long-term reliability challenges. The specific reasons are as follows: due to the significant difference in thermal expansion coefficient between the filling body and the interconnection structure base material (such as FR-4 and ceramic), periodic thermal stress will be generated in the subsequent use process. This stress is easy to cause delamination and cracking at the interface between the filling body and the micropore, and is easy to cause micro-cracks in the filling body (especially in the sintering defects or weak grain boundaries). The above-mentioned micro-cracks will cause the local resistance of the circuit of the interconnection structure to increase sharply, the signal transmission to be unstable, and even cause a short circuit, which seriously threatens the service life of the interconnection structure.

[0006] To cope with this challenge, the concept of self-repairing is introduced. Current self-repairing mainly includes intrinsic self-repairing technology and external self-repairing technology, and the external self-repairing technology is concerned due to high repair efficiency and small influence on initial performance of the substrate. The principle is to encapsulate the repairing agent in microcapsules, and to pre-disperse the microcapsules in the copper nanoparticle slurry to form a composite filling slurry; when a microcrack is generated in the material, the stress at the tip of the microcrack will cause the microcapsule to break, release the repairing agent and realize repair through solidification reaction. However, direct application of existing microcapsule technology to micro-hole filling will face a series of fundamental technical bottlenecks, as follows: (1) functional failure: traditional repairing agents (such as monomers and solvents) are mostly insulators, and even if the physical continuity of the crack is successfully repaired, the necessary conductive function cannot be restored; (2) introduction difficulty: how to uniformly introduce and stably exist in the narrow deep hole structure, and not to interfere with the initial filling and densification of copper nanoparticles, is a difficult process problem; (3) process compatibility: the sintering temperature of copper nanoparticles is usually higher than 220℃, which requires that the microcapsule must maintain structural integrity and thermal stability at this high temperature to avoid premature rupture or decomposition; (4) trigger and repair effectiveness: it is necessary to ensure that when a microcrack is generated inside the filling body, the local stress can effectively trigger the microcapsule to break, and the released repairing agent can wet the metal surface and fill the crack, and rebuild a high-conductive path through a reliable mechanism.

[0007] The existence of the above problems results in that even if microcapsules are added to the composite filling slurry, the micro-holes cannot be effectively filled, and at the same time, the microcracks generated in the subsequent use process cannot be repaired, resulting in low reliability of the interconnection structure. SUMMARY

[0008] The purpose of the present application is to provide a filling process for micro-holes in an interconnection structure, which not only effectively fills the micro-holes, but also realizes conductive self-repairing of microcracks generated in the subsequent use process, thereby improving the long-term reliability of the interconnection structure, to overcome the shortcomings in the prior art.

[0009] Another purpose of the present application is to provide a filling device for micro-holes in an interconnection structure, which cooperates with the filling process for micro-holes in the interconnection structure, can effectively improve the technical problem that the prior art cannot effectively fill the micro-holes, and at the same time, can realize conductive self-repairing of microcracks generated in the subsequent use process, which is beneficial to ensure the filling reliability.

[0010] To achieve this purpose, the present application adopts the following technical solutions: A filling process for micro-holes in an interconnection structure, comprising the following steps: A. preparing core-shell microcapsules; wherein the core-shell microcapsules comprise a liquid metal core and a conductive shell layer arranged from inside to outside, and the raw material of the liquid metal core comprises a liquid metal with a melting point less than 30℃; B. mixing copper nanoparticles, core-shell microcapsules, a dispersing agent and water uniformly to obtain a composite filling slurry; wherein the sintering temperature of the copper nanoparticles is lower than the decomposition temperature of the conductive shell layer; C. filling the composite filling slurry into micropores in the interconnection structure and calcining under an inert atmosphere.

[0011] Further, in step A, the liquid metal comprises any one of gallium and indium-gallium alloy.

[0012] Further, in step A, the raw material of the conductive shell layer comprises, in terms of mass percentage, 85-95% of a conductive material and 5-15% of a stress-sensitive material. The decomposition temperature of the conductive material and the stress-sensitive material is higher than the sintering temperature of the copper nanoparticles.

[0013] Further, the conductive material comprises at least two of poly(3,4-ethylenedioxythiophene), sodium polystyrene sulfonate, polyaniline, polypyrrole, poly(3-alkylthiophene), poly(p-phenylenevinylene), polyfluorene, polycarbazole, polyperylene and polyazulene. The stress-sensitive material comprises any one of silica particles and glass powder.

[0014] Further, in step A, the particle size of the core-shell microcapsules is 1-1000 nm.

[0015] Further, in step B, the raw material of the composite filling slurry comprises, in terms of mass percentage, 50-60% of copper nanoparticles, 2-6% of core-shell microcapsules, 1-2% of a dispersing agent and 35-45% of water.

[0016] Further, in step B, the particle size of the copper nanoparticles is 5-500 nm.

[0017] Further, in step C, the calcination curve of the calcination is as follows: heating from room temperature to 100-350℃ at a heating rate of 1-10℃ / min, and holding for 0.2-0.5 h.

[0018] Further, in step C, the filling method is as follows: primary filling is performed under a vacuum degree of -10 to -50 kPa; deep filling is performed under a vacuum degree of -80 to -100 kPa; standing under normal pressure for 0.5-1 min.

[0019] The application discloses a filling device for micropores in an interconnection structure, which is used for realizing the filling process of the micropores in the interconnection structure. The gas pressure adjusting device is in communication with the vacuum cavity, and is used for adjusting the vacuum degree of the vacuum cavity. The optical detection device, the slurry filling device and the platform moving device are located inside the vacuum cavity, the optical detection device and the slurry filling device are located on two sides above the platform moving device respectively, and the platform moving device can move in the horizontal direction and the vertical direction relative to the optical detection device and the slurry filling device. The collection and analysis device is installed on the top of the optical detection device, and the collection and analysis device is electrically connected with the optical detection device, the slurry filling device and the platform moving device. The platform moving device is used for placing the interconnection structure, the optical detection device is used for collecting the micropore image of the interconnection structure, the collection and analysis device is used for analyzing the micropore image of the interconnection structure, accurately positioning all micropore coordinates and generating a moving path instruction and a filling instruction, and the slurry filling device is used for filling the composite filling slurry into the micropores of the interconnection structure.

[0020] The technical scheme provided by the application can have the following beneficial effects: 1. In the calcination process, the core-shell microcapsules can maintain the structural integrity and be dispersed and embedded in the interior of the filling body because the decomposition temperature of the conductive shell layer of the core-shell microcapsules is higher than the sintering temperature of the copper nanoparticles. The conductive shell layer makes the core-shell microcapsules have the electrical conductivity, so that the core-shell microcapsules can be used as a component of the conductive network, thereby minimizing the influence on the initial conductive performance of the filling body and ensuring that the micropores are effectively and highly filled.

[0021] 2、When microcracks occur in the filler during subsequent use, whether the microcracks occur inside the filler or at the interface between the filler and the micropores (i.e., the filler interface), as long as the microcrack propagation path passes through or is close to the core-shell microcapsule, and the microcrack tip stress reaches the fracture threshold of the conductive shell layer of the core-shell microcapsule, the conductive shell layer will break, releasing the liquid metal with a melting point below 30℃ in the liquid metal core. The liquid metal has extremely high electrical conductivity and excellent flow wettability, and can quickly fill and bridge the gap of the microcrack, and even backfill the cavity of the core-shell microcapsule. At the same time, the conductive shell layer debris after breaking still has conductivity and can participate in conduction, thereby achieving accurate and efficient repair of the microcrack. It should be noted that during the sintering and filling process, some core-shell microcapsules will naturally distribute in or near the interface region between the filler and the micropores. Therefore, when microcracks occur at the interface between the filler and the micropores due to differences in thermal expansion coefficients and other reasons, their propagation can also trigger the core-shell microcapsules in this region to release liquid metal to effectively repair the interface cracks, thereby restoring the mechanical bonding strength and electrical continuity of the interface. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of a filling device for micropores in an interconnection structure.

[0023] Among them: platform moving device 1, placing platform 11, moving base 12, optical detection device 2, acquisition camera 21, light source 22, acquisition analysis device 3, slurry filling device 4, air pressure adjusting device 5, slurry conveying device 6, pressure pump 61, slurry storage tank 62, conveying pipe 63. DETAILED DESCRIPTION

[0024] The technical solution provides a filling process for micropores in an interconnection structure, which comprises the following steps: A. Preparing core-shell microcapsules; wherein the core-shell microcapsules comprise a liquid metal core and a conductive shell layer arranged in sequence from inside to outside, and the raw material of the liquid metal core comprises a liquid metal with a melting point less than 30℃; B. Mixing copper nanoparticles, core-shell microcapsules, a dispersing agent and water uniformly to obtain a composite filling slurry; wherein the sintering temperature of the copper nanoparticles is less than the decomposition temperature of the conductive shell layer; C. Filling the composite filling slurry into micropores in an interconnection structure and calcining under an inert atmosphere.

[0025] In order to solve the technical problem that the filling process of the micropore in the prior art cannot effectively fill the micropore while realizing the electrically conductive self-repair of the microcrack generated in the subsequent use process, the technical scheme provides a filling process of micropore in interconnection structure, which comprises A (preparation of core-shell microcapsule), B (preparation of composite filling slurry) and C (filling and calcination). By optimizing the filling process and raw materials, the micropore can be effectively filled, and the microcrack generated in the subsequent use process can be repaired, thereby improving the long-term reliability of the interconnection structure to meet the actual use requirements.

[0026] Specifically, the composite filling slurry of the technical scheme comprises copper nanoparticles, core-shell microcapsules, a dispersing agent and water, and then the composite filling slurry is filled into the micropore in the interconnection structure and calcined in an inert atmosphere. In this process, the water in the composite filling slurry evaporates, and the copper nanoparticles and the copper nanoparticles form metallurgical bonding through atomic diffusion and dynamic recrystallization phenomenon, thereby forming a dense filling body. At the same time, the copper nanoparticles and the micropore also form metallurgical bonding through atomic thermal diffusion, thereby establishing a strong and tough metal bond between them, ensuring the interface bonding strength and electrical continuity between the filling body and the micropore.

[0027] Further, in the calcination process, since the decomposition temperature of the conductive shell layer of the core-shell microcapsule is higher than the sintering temperature of the copper nanoparticles, the core-shell microcapsule remains structurally intact and is dispersed and embedded in the interior of the filling body. The conductive shell layer makes the core-shell microcapsule itself have electrical conductivity, so that the core-shell microcapsule can be used as a component of the conductive network, thereby minimizing the influence on the initial electrical conductivity of the filling body and ensuring that the micropore is effectively and highly conductive.

[0028] When the filling body generates a microcrack in the subsequent use process, whether the microcrack is generated inside the filling body or at the interface between the filling body and the micropore (i.e. the interface of the filling body), as long as the microcrack propagation path passes through or is close to the core-shell microcapsule, and the stress at the tip of the microcrack reaches the fracture threshold of the conductive shell layer of the core-shell microcapsule, the conductive shell layer will be broken, releasing the liquid metal with a melting point lower than 30℃ in the liquid metal core. The liquid metal has extremely high electrical conductivity and excellent flow wettability, and can quickly fill and bridge the gap of the microcrack, and even backfill the cavity of the core-shell microcapsule. At the same time, the conductive shell layer debris after breaking still has electrical conductivity and can participate in conduction, thereby realizing accurate and efficient repair of the microcrack. It should be noted that during the sintering and filling process, part of the core-shell microcapsules will naturally distribute in or near the interface region between the filling body and the micropore. Therefore, when a microcrack is generated at the interface between the filling body and the micropore due to differences in thermal expansion coefficient and other reasons, its propagation can also trigger the core-shell microcapsules in this region to release the liquid metal to effectively repair the interface crack, thereby restoring the mechanical bonding strength and electrical continuity of the interface.

[0029] In summary, this approach ensures initial filling quality by utilizing the core-shell microcapsules as a stable conductive dopant phase during sintering; subsequently, they transform into active repair units, releasing liquid metal as needed during use. This dual mechanism synergistically achieves high-quality micropore filling and conductive self-repair during use, thereby enhancing the long-term reliability of the interconnect structure.

[0030] Furthermore, the composite filling slurry based on copper nanoparticles in this technical solution, thanks to its nano-size effect and good rheological properties, can effectively penetrate and initially fill deep pores through capillary action. Secondly, the composite filling slurry in this technical solution can achieve conductive self-healing during later use, fundamentally overcoming the bottleneck of traditional high aspect ratio filling which is prone to defects due to stress concentration and ultimately leads to failure. Thus, even if the aspect ratio of the micropores (the aspect ratio refers to the ratio of depth to pore diameter) is as high as 50:1, it can still ensure the process feasibility and long-term reliability of filling.

[0031] Secondly, the core of this technical solution is liquid metal, which is itself a highly conductive material. After it is released, it can quickly fill and bridge the two ends of the crack, fundamentally ensuring the restoration of conductivity after repair, rather than insulation and sealing, thus avoiding the technical problem of functional failure even after repair.

[0032] Meanwhile, this technical solution utilizes a dispersant to ensure uniform and stable mixing of core-shell microcapsules and copper nanoparticles in the composite filling slurry. This allows the core-shell microcapsules to flow into the micropores along with the composite filling slurry during filling, achieving a natural and uniform distribution without acting as foreign matter and interfering with particle stacking. This avoids interference with the initial filling and densification of copper nanoparticles, thus solving the problem of introduction.

[0033] In addition, the decomposition temperature of the conductive outer shell layer in this technical solution is higher than the sintering temperature of copper nanoparticles, which ensures that the conductive outer shell layer maintains structural integrity during the sintering process, thereby protecting the liquid metal core and preventing premature cracking or decomposition, thus improving process compatibility.

[0034] Secondly, as described above, after calcination, the conductive outer shell becomes part of the filler. When microcracks are generated and propagate to the core-shell microcapsule, the conductive outer shell will rupture due to localized stress concentration. Liquid metals with a melting point <30℃ remain liquid at room temperature, possessing excellent fluidity and intrinsic wettability to metal surfaces. They can automatically fill capillary cracks and rebuild conductive paths by forming direct metal-to-metal connections, thus overcoming the shortcomings of existing technologies that cannot trigger and effectively repair these cracks.

[0035] It should be noted that the micropores in this technical solution refer to micropores with metallized pore walls. Furthermore, in existing technologies, micropores requiring conductive filling for electrical interconnection all have metallized pore walls. Therefore, the micropores in this technical solution, having metallized pore walls, are well-known in the art. Simultaneously, the micropores include through-holes and / or blind holes. When the micropore is a through-hole, a filter membrane needs to be placed at the bottom of the through-hole, and the pore size of the filter membrane is smaller than the particle size of the copper nanoparticles, thereby preventing copper nanoparticles from falling directly into the through-hole. Additionally, the filter membrane material can be polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polyacrylonitrile (PAC), etc. The specific material type can be selected according to actual needs, and no specific material type is limited here.

[0036] It should be further noted that the core-shell microcapsules of this technical solution are prepared using an in-situ polymerization method commonly used in existing technologies; the specific method will not be described in detail here. The inert atmosphere can be a nitrogen atmosphere or an argon atmosphere, etc., and the specific type is not limited here.

[0037] To further clarify, in step A, the liquid metal includes either gallium or an indium-gallium alloy.

[0038] Both gallium and indium gallium alloys possess high electrical conductivity and low melting points, remaining liquid at room temperature. This allows them to flow, fill, and bridge microcracks during the repair process. Therefore, this technical solution preferably uses either gallium or indium gallium alloys as the liquid metal. This not only improves the conductive self-healing performance but also allows for the selection of a suitable liquid metal based on actual needs, enhancing the flexibility of the solution.

[0039] To further explain, in step A, the raw materials of the conductive outer shell layer, calculated by mass percentage, include 85-95% conductive material and 5-15% stress-sensitive material; The decomposition temperatures of both the conductive material and the stress-sensitive material are greater than the sintering temperature of the copper nanoparticles.

[0040] This technical solution optimizes the raw materials for the conductive outer shell layer, including conductive and stress-sensitive materials. This allows the conductive materials to ensure the conductivity of the outer shell layer, while the stress-sensitive materials, which readily form stress concentration points within the conductive outer shell layer, lower the rupture threshold of the core-shell microcapsules, making them more sensitive to microcracks. Simultaneously, the amounts of conductive and stress-sensitive materials added are limited to ensure that the core-shell microcapsules do not rupture under normal conditions (such as sintering and processing stress), but rupture promptly under microcrack stress (such as 0.2% strain), thereby achieving conductive self-healing.

[0041] Furthermore, this technical solution limits the decomposition temperatures of both the conductive material and the stress-sensitive material to be higher than the sintering temperature of the copper nanoparticles. This double protection ensures that the decomposition temperature of the conductive outer shell is higher than the sintering temperature of the copper nanoparticles. During the sintering process, the conductive outer shell maintains its structural integrity, thus protecting the liquid metal core and preventing premature cracking or decomposition, thereby improving the reliability of the repair effect.

[0042] Further explanation: the conductive material includes at least two of poly(3,4-ethylenedioxythiophene), sodium polystyrene sulfonate, polyaniline, polypyrrole, poly(3-alkylthiophene), poly(p-phenylenevinylene), polyfluorene, polycarbazole, polypentaphenylene, and poly(pyrrolethiophene). The stress-sensitive material includes either silica particles or glass powder.

[0043] Poly(3,4-ethylenedioxythiophene), sodium polystyrene sulfonate, polyaniline, polypyrrole, poly(3-alkylthiophene), poly(p-phenylenevinylene), polyfluorene, polycarbazole, polypentaphenylene, and poly(3-alkylthiophene) all possess good electrical conductivity, thermal stability, and film-forming properties, and can maintain structural integrity during sintering. Therefore, this technical solution preferably uses the above-mentioned types of conductive materials, which is beneficial to ensuring the performance of the conductive materials.

[0044] Furthermore, both silica particles and glass powder possess characteristics of high brittleness, chemical stability, and low cost. They also readily form stress concentration points in the conductive outer shell, lowering the fracture threshold of the core-shell microcapsules and making them more sensitive to microcracks. Therefore, this technical solution preferably uses the aforementioned types of stress-sensitive materials to improve conductive self-healing performance.

[0045] To further explain, in step A, the particle size of the core-shell microcapsules is 1–1000 nm.

[0046] This technical solution limits the particle size of core-shell microcapsules, which not only allows the core-shell microcapsules to be uniformly dispersed in the composite filler slurry and effectively fill the micropores, but also makes their particle size match the microcrack size, especially the microcracks with a length of 3-10000nm. This ensures that the stress at the microcrack tip can effectively trigger rupture and release sufficient liquid metal to repair the microcrack.

[0047] To further explain, in step B, the raw materials of the composite filler slurry, calculated by mass percentage, include 50-60% copper nanoparticles, 2-6% core-shell microcapsules, 1-2% dispersant, and 35-45% water.

[0048] This technical solution optimizes the addition amounts of each raw material in the composite filler slurry, allowing each material to fully utilize its properties. This ensures the performance of the resulting composite filler slurry, thereby guaranteeing both filling and self-healing effects. It should be noted that the dispersant can be ammonium polyacrylate.

[0049] Preferably, the mixing ratio of the core-shell microcapsule to the copper nanoparticles is 1:(10-30) by mass ratio.

[0050] This technical solution, by limiting the mixing ratio of core-shell microcapsules and copper nanoparticles, facilitates the uniform dispersion of core-shell microcapsules in the filler after calcination of the composite filler slurry. This not only helps to effectively repair microcracks but also does not affect the sintering densification and initial conductivity of the copper nanoparticles.

[0051] To further clarify, in step B, the particle size of the copper nanoparticles is 5–500 nm.

[0052] This technical solution improves the flexibility of the solution by allowing the selection of copper nanoparticles with appropriate particle size according to actual needs through the control of the particle size of copper nanoparticles.

[0053] To further explain, in step C, the calcination curve is as follows: the temperature is increased from room temperature to 100-350°C at a heating rate of 1-10°C / min, and then held at that temperature for 0.2-0.5 hours.

[0054] This technical solution limits the calcination curve, allowing copper nanoparticles to diffuse and densify on the surface under this calcination curve, while preventing the conductive outer shell from splitting, thereby avoiding premature failure of the core-shell microcapsule.

[0055] To further explain, in step C, the filling method is as follows: The initial filling was carried out under a vacuum of -10 to -50 kPa. Deep filling is performed under a vacuum of -80 to -100 kPa; Let it stand for 0.5 to 1 minute under normal pressure.

[0056] This technical solution optimizes the filling method. Initial filling introduces the composite filler slurry to the bottom of the micropores and removes most of the residual gas. Then, deep filling is performed under a higher vacuum environment to completely fill the micropores with the composite filler slurry and remove any remaining gas. Finally, the slurry is allowed to stand at atmospheric pressure for 0.5–1 minute, utilizing its surface tension to smooth it and prevent voids at the top. Therefore, this segmented filling method reduces capillary resistance and gas retention, ensuring continuous filling of the composite filler slurry from the bottom to the top of the pore, thereby improving the conductivity of the filler.

[0057] A device for filling micropores in an interconnect structure, used to realize the above-mentioned filling process of micropores in the interconnect structure, includes a platform moving device 1, an optical detection device 2, a data acquisition and analysis device 3, a slurry filling device 4, a pressure regulating device 5, and a vacuum chamber. The air pressure regulating device 5 is interconnected with the vacuum chamber, and the air pressure regulating device 5 is used to regulate the vacuum level of the vacuum chamber; The optical detection device 2, the slurry filling device 4, and the platform moving device 1 are all located inside the vacuum cavity. The optical detection device 2 and the slurry filling device 4 are located on opposite sides above the platform moving device 1, and the platform moving device 1 can move relative to the optical detection device 2 and the slurry filling device 4 in the horizontal and vertical directions. The acquisition and analysis device 3 is installed on the top of the optical detection device 2, and the acquisition and analysis device 3 is electrically connected to the optical detection device 2, the slurry filling device 4 and the platform moving device 1. The platform moving device 1 is used to place the interconnect structure, the optical detection device 2 is used to acquire micro-hole images of the interconnect structure, the acquisition and analysis device 3 is used to analyze the micro-hole images of the interconnect structure, accurately locate the coordinates of all micro-holes, and generate moving path instructions and filling instructions, and the slurry filling device 4 is used to fill the micro-holes of the interconnect structure with composite filling slurry.

[0058] This technical solution also proposes a device for filling micropores in interconnect structures, which, in conjunction with the micropore filling process in interconnect structures, can effectively improve the technical problem of the inability to effectively fill micropores in existing technologies at a lower equipment cost, while also enabling conductive self-repair of microcracks generated during subsequent use, thus helping to ensure filling reliability.

[0059] Specifically, the micropore filling device in the interconnect structure includes a platform moving device 1, an optical detection device 2, an acquisition and analysis device 3, a slurry filling device 4, a pressure regulating device 5, and a vacuum chamber. First, the pressure regulating device 5 evacuates the vacuum chamber to a preset vacuum level to eliminate gas interference. Then, the platform moving device 1 carries the interconnect structure, and the optical detection device 2 scans the interconnect structure and transmits the image to the acquisition and analysis device 3. The acquisition and analysis device 3 analyzes the image transmitted by the optical detection device 2, accurately locates the coordinates of all micropores in the interconnect structure, and generates movement path instructions and filling instructions. Next, the platform moving device moves the micropores in the interconnect structure one by one to below the slurry filling device 4 according to the movement path instructions of the acquisition and analysis device 3. After the movement is completed, the slurry filling device 4 injects a quantitative amount of composite filling slurry into each micropore according to the filling instructions of the acquisition and analysis device 3. This process is repeated until all micropores are filled. Finally, calcination is carried out in an inert environment to achieve high density and defect-free filling of the micropores.

[0060] Preferably, the platform moving device 1 includes a placement platform 11 and a moving base 12 connected sequentially from top to bottom. The placement platform 11 is located below the optical detection device 2 and the slurry filling device 4, and the placement platform 11 can move relative to the optical detection device 2 and the slurry filling device 4 in the horizontal and vertical directions via the moving base 12. The placement platform 11 is used to place interconnection structures.

[0061] This technical solution, through the above-mentioned settings, enables the placement platform 11 to place the interconnect structure, while the movable base 12 can move along the X, Y, and Z axes, ensuring the positioning accuracy and stability of the interconnect structure at the two key work stations of micropore detection and slurry filling, and improving the filling quality.

[0062] Preferably, the optical detection device 2 includes a data acquisition camera 21 and a light source 22 connected sequentially from top to bottom. The light source 22 is located above the platform moving device 1, and the data acquisition camera 21 is electrically connected to the data acquisition and analysis device 3.

[0063] Through the above-mentioned settings, this technical solution enables the light source 22 to uniformly illuminate the surface of the interconnect structure from top to bottom, resulting in clear optical contrast for features such as micropores. The camera 21 acquires high-quality images from an almost coaxial angle, minimizing shadow and reflection interference, thereby providing the acquisition and analysis device 2 with sharp outlines and rich details. This directly improves the system's accuracy and reliability in identifying the position, size, and morphology of micropores, providing a fundamental visual guarantee for subsequent accurate alignment and high-quality filling.

[0064] Preferably, it also includes a slurry conveying device 6, the outlet of which is connected to the inlet of the slurry filling device 4, and the slurry conveying device 6 is used to store the composite filling slurry and convey the composite filling slurry to the slurry filling device 4.

[0065] This technical solution, by setting up a slurry filling device 4, facilitates the centralized storage and stable transportation of composite filling slurry, thereby improving the efficiency of the filling process.

[0066] Preferably, the slurry conveying device 6 includes a pressure pump 61, a slurry storage tank 62, and a conveying pipe 63. The outlet of the slurry storage tank 62 is connected to the inlet of the slurry filling device 4 through the conveying pipe 63. The pressure pump 61 is used to pump the slurry located in the slurry storage tank 62 into the slurry filling device 4.

[0067] Through the above-mentioned settings, the pressure pump 61 plays an auxiliary role in the transportation of composite filler slurry, ensuring that the composite filler slurry can be transported to the end of the delivery pipe 63 (the end near the outlet of the delivery pipe 63) when micropore filling is not performed. At the same time, when micropore filling is performed, the transmission pressure of the composite filler slurry can be adjusted according to different air pressures to achieve segmented filling of the composite filler slurry.

[0068] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0069] Performance testing methods: Initial resistance: The sintered and filled sample was cut along a direction perpendicular to the micropore axis using a diamond wire cutter, and the cross-section was polished to expose the complete cross-section of the filler. Under optical microscopy, the probe of a four-probe tester was precisely placed against the center region of the cross-section of a single filler for measurement. Ten fillers were randomly selected from the same batch of samples for testing, and their average resistance was used as the initial resistance reference value (R0).

[0070] Resistance recovery rate: A micro-force testing system is used to apply a preset load (e.g., to generate a controllable microcrack with a length of 3-10000 nm) to the central region of the filler cross-section where the initial resistance has been measured. Subsequently, the repaired resistance value (R0) is measured in situ using a four-probe tester. According to the formula: Resistance recovery rate = (R0 / R) Calculate the resistance recovery rate by multiplying the resistance recovery rate by 100%. If the resistance recovery rate is ≥95%, the conductive path is considered to have been effectively repaired.

[0071] Filling integrity: Backscattered electron imaging was performed on the polished cross-section of the filler using a scanning electron microscope. Image analysis software was used to perform threshold segmentation on the image to distinguish the filler area from the void area, and the percentage of the filled area in the total pore area was automatically calculated. At the same time, the percentage of the filled area in the total pore area of multiple cross-sections such as the top, middle, and bottom of the pore was checked along the pore depth direction. If the percentage of the filled area of all detected cross-sections is ≥98% and no through-hole voids are found, the filling integrity is determined to be qualified.

[0072] Example 1 A. Preparation of core-shell microcapsules with a gallium-indium alloy as the liquid metal core and poly(3,4-ethylenedioxythiophene), sodium polystyrene sulfonate, and silica particles as the conductive outer shell layer; the specific preparation method is as follows: After mixing 0.25 g of sodium dodecyl sulfate with 50 ml of deionized water evenly, a sodium dodecyl sulfate solution is obtained; 5.0 g of gallium-indium alloy is added to the sodium dodecyl sulfate solution, and after ultrasonic treatment for 10 min, an emulsion is obtained; 0.30 g of 3,4-ethylenedioxythiophene, 0.50 g of sodium polystyrene sulfonate, and 0.05 g of silica particles are successively added to the emulsion to obtain a mixed solution; after mixing 0.50 g of ammonium persulfate with 10 ml of deionized water evenly, an ammonium persulfate solution is obtained; under a nitrogen atmosphere, the ammonium persulfate solution is added dropwise to the mixed solution, the reaction temperature is controlled at 8-12 °C, and after continuous stirring for 18 h, a core-shell microcapsule suspension is obtained; the core-shell microcapsule suspension is centrifuged at a speed of 8000 r / min for 15 min, the supernatant is discarded, and a first precipitate is obtained; the first precipitate is washed with a mixed solution of deionized water and absolute ethanol with a volume ratio of 1:1 until the filtrate is colorless and transparent, and a second precipitate is obtained; the second precipitate is dried in a vacuum drying oven at 40 °C for 12 h to obtain core-shell microcapsules with a particle size distribution of 30-80 nm; B. 50% of copper nanoparticles with a particle size of 50 nm, 5% of core-shell microcapsules, 1% of ammonium polyacrylate, and 44% of water are mixed evenly by mass percentage to obtain a composite filling slurry; C. The composite filling slurry is filled into the micropores with a pore diameter of 10 μm and a depth of 300 μm in the interconnect structure and calcined under a nitrogen atmosphere; among them, the calcination curve for calcination is: heating from room temperature to 240 °C at a heating rate of 5 °C / min and then holding for 0.5 h; the filling method is: primary filling is carried out under a vacuum of -20 kPa; deep filling is carried out under a vacuum of -80 kPa; and it is allowed to stand at normal pressure for 0.5 min.

[0073] Example 2 A. Preparation of core-shell microcapsules with gallium as the liquid metal core and poly(3,4-ethylenedioxythiophene), sodium polystyrene sulfonate, and glass powder as the conductive outer shell; the specific preparation method is as follows: 0.25g of sodium dodecyl sulfate is mixed evenly with 50ml of deionized water to obtain a sodium dodecyl sulfate solution; 5.0g of gallium is added to the sodium dodecyl sulfate solution, and ultrasonic treatment is performed for 10min to obtain an emulsion; 0.30g of 3,4-ethylenedioxythiophene, 0.50g of sodium polystyrene sulfonate, and 0.05g of glass powder are added sequentially to the emulsion to obtain a mixed solution; 0.50g of ammonium persulfate is mixed with 10ml of deionized water... After the water was mixed evenly, an ammonium persulfate solution was obtained. Under a nitrogen atmosphere, the ammonium persulfate solution was added dropwise to the mixed solution, the reaction temperature was controlled at 8-12℃, and the mixture was stirred continuously for 18 hours to obtain a core-shell microcapsule suspension. The core-shell microcapsule suspension was centrifuged at 7000 r / min for 18 min, and the supernatant was discarded to obtain the first precipitate. The first precipitate was washed with a 1:1 volume ratio of deionized water and anhydrous ethanol until the filtrate was colorless and transparent to obtain the second precipitate. The second precipitate was dried in a vacuum drying oven at 50℃ for 12 hours to obtain core-shell microcapsules with a particle size distribution of 30-80 nm. B. Mix 55% copper nanoparticles with a particle size of 60nm, 3% core-shell microcapsules, 2% ammonium polyacrylate and 40% water by mass percentage to obtain a composite filler slurry. C. The composite filler slurry is filled into micropores with a diameter of 20 μm and a depth of 30 μm in the interconnect structure and calcined under an argon atmosphere. The calcination curve is as follows: the temperature is increased from room temperature to 250℃ at a heating rate of 3℃ / min and then held at that temperature for 0.3h. The filling method is as follows: initial filling is carried out under a vacuum of -50kPa; deep filling is carried out under a vacuum of -80kPa; and the mixture is allowed to stand for 1min under normal pressure.

[0074] Example 3 A. Preparation of core-shell microcapsules with a gallium-indium alloy as the liquid metal core and polyaniline, sodium polystyrene sulfonate, and silica particles as the conductive outer shell; the specific preparation method is as follows: 0.25g of sodium dodecyl sulfate is mixed evenly with 50ml of deionized water to obtain a sodium dodecyl sulfate solution; 5.0g of gallium-indium alloy is added to the sodium dodecyl sulfate solution, and ultrasonic treatment is performed for 10min to obtain an emulsion; 0.30g of polyaniline, 0.50g of sodium polystyrene sulfonate, and 0.05g of silica particles are added sequentially to the emulsion to obtain a mixed solution; 0.50g of ammonium persulfate is mixed with 10ml of deionized water. After homogenization, an ammonium persulfate solution was obtained. Under a nitrogen atmosphere, the ammonium persulfate solution was added dropwise to the mixed solution, the reaction temperature was controlled at 8-12℃, and the mixture was stirred continuously for 18 hours to obtain a core-shell microcapsule suspension. The core-shell microcapsule suspension was centrifuged at 8000 r / min for 15 min, and the supernatant was discarded to obtain the first precipitate. The first precipitate was washed with a 1:1 volume ratio of deionized water and anhydrous ethanol until the filtrate was colorless and transparent to obtain the second precipitate. The second precipitate was dried in a vacuum drying oven at 40℃ for 12 hours to obtain core-shell microcapsules with a particle size distribution of 30-80 nm. B. Mix 60% copper nanoparticles with a particle size of 20nm, 4% core-shell microcapsules, 1% ammonium polyacrylate and 35% water by mass percentage to obtain a composite filler slurry. C. The composite filler slurry is filled into micropores with a diameter of 50 μm and a depth of 500 μm in the interconnect structure and calcined under a nitrogen atmosphere. The calcination curve is as follows: the temperature is increased from room temperature to 230℃ at a heating rate of 3℃ / min and then held at that temperature for 0.4h. The filling method is as follows: initial filling is carried out under a vacuum of -10kPa; deep filling is carried out under a vacuum of -90kPa; and the mixture is allowed to stand for 0.8min under normal pressure.

[0075] Comparative Example 1 The preparation method and raw materials of this comparative example are the same as those of Example 2. The difference is that the raw materials of the composite filler slurry in this comparative example do not contain core-shell microcapsules. That is, calculated by mass percentage, the raw materials of the composite filler slurry include 57% copper nanoparticles, 2% ammonium polyacrylate, and 41% water.

[0076] The fillers prepared in the examples and comparative examples were subjected to performance tests, and the results are shown in Table 1 below: Table 1. Test results of relevant performance of the filler

[0077] As can be seen from the test data in Table 1, this technical solution can not only effectively fill micropores and make the filler have good conductivity, but also achieve conductive self-repair of microcracks generated during subsequent use, thereby improving the long-term reliability of the interconnect structure to meet actual use requirements.

[0078] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A process for filling micropores in an interconnect structure, characterized by, The method comprises the following steps: A. Preparing core-shell microcapsules; wherein the core-shell microcapsules comprise a liquid metal core and a conductive shell layer arranged from inside to outside, and the raw material of the liquid metal core comprises a liquid metal with a melting point less than 30℃; B. Mixing copper nanoparticles, core-shell microcapsules, a dispersing agent and water uniformly to obtain a composite filling slurry; wherein the sintering temperature of the copper nanoparticles is lower than the decomposition temperature of the conductive shell layer; C. Filling the composite filling slurry into micropores in the interconnection structure and calcining under an inert atmosphere.

2. The process of claim 1, wherein In step A, the liquid metal comprises any one of gallium and indium-gallium alloy.

3. The process of claim 1, wherein In step A, according to mass percentage, the raw material of the conductive shell layer comprises 85-95% of a conductive material and 5-15% of a stress-sensitive material; The decomposition temperature of the conductive material and the stress-sensitive material is higher than the sintering temperature of the copper nanoparticles.

4. The process of claim 3, wherein, The conductive material comprises at least two of poly(3,4-ethylenedioxythiophene), sodium polystyrene sulfonate, polyaniline, polypyrrole, poly(3-alkylthiophene), poly(p-phenylenevinylene), polyfluorene, polycarbazole, polyperylene and polythiophene; The stress-sensitive material comprises any one of silica particles and glass powder.

5. The process of claim 1, wherein In step A, the particle size of the core-shell microcapsules is 1-1000 nm.

6. The process of claim 1, wherein In step B, according to mass percentage, the raw material of the composite filling slurry comprises 50-60% of copper nanoparticles, 2-6% of core-shell microcapsules, 1-2% of a dispersing agent and 35-45% of water.

7. The process of claim 1, wherein In step B, the particle size of the copper nanoparticles is 5-500 nm.

8. The process of claim 1, wherein In step C, the calcination curve of the calcination is as follows: increasing the temperature from room temperature to 100-350℃ at a temperature increasing rate of 1-10℃ / min, and then keeping the temperature for 0.2-0.5 h.

9. The process of claim 1, wherein In step C, the filling method is as follows: Performing primary filling under a vacuum degree of -10 to -50 kPa; Performing deep filling under a vacuum degree of -80 to -100 kPa; Standing still under normal pressure for 0.5-1 min.

10. An apparatus for filling micropores in an interconnect structure, comprising: A filling process for micropores in the interconnection structure as claimed in any one of claims 1-9, comprising a platform moving device, an optical detection device, a collection and analysis device, a slurry filling device, a gas pressure adjusting device and a vacuum cavity; The gas pressure adjusting device is in communication with the vacuum cavity, and the gas pressure adjusting device is used to adjust the vacuum degree of the vacuum cavity; The optical detection device, the slurry filling device and the platform moving device are all located inside the vacuum cavity, the optical detection device and the slurry filling device are respectively located on the two sides above the platform moving device, and the platform moving device can move in the horizontal direction and the vertical direction relative to the optical detection device and the slurry filling device; The collection and analysis device is installed on the top of the optical detection device, and the collection and analysis device is electrically connected with the optical detection device, the slurry filling device and the platform moving device; The platform moving device is used for placing the interconnected structure, the optical detection device is used for collecting the micropore image of the interconnected structure, the collection and analysis device is used for analyzing the micropore image of the interconnected structure and accurately positioning all micropore coordinates and generating moving path instructions and filling instructions, and the slurry filling device is used for filling the composite filling slurry to the micropore of the interconnected structure.

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