An interconnection method using solvent-assisted sintering

Abstract

The present invention discloses an interconnection method using solvent-assisted sintering, which relates to the field of device packaging interconnection technology. The present invention uses a solvent-assisted sintering interconnection method, comprising the following steps: (1) depositing nano-metal particles in a deposition area of ​​a substrate to form a metal deposition layer in the deposition area of ​​the substrate; (2) dripping an auxiliary solvent onto the surface of the metal deposition layer; (3) under a protective gas, aligning and heating a matching workpiece with the substrate of step (2) to bond them, and obtaining a sandwich interconnection structure after cooling; wherein the volatilization temperature of the auxiliary solvent is lower than the heating temperature of the bonding, and the matching workpiece is a chip or another substrate that matches the substrate of step (2). The present invention uses a solvent-assisted sintering interconnection method, by directly depositing nano-metal particles in the deposition area of ​​the substrate and using an auxiliary solvent to assist sintering, to achieve better performance interconnection and meet advanced packaging requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of device packaging interconnection, and in particular to an interconnection method using solvent-assisted sintering. Background Art

[0002] In the field of advanced semiconductor and microelectronic packaging, the integration of various electronic components into a single package is becoming increasingly important. Traditional metal solder pastes have a small wetting angle during application, poor contact with the substrate, low packing density after application, and solvent evaporation during sintering, which can cause the sintered structure to collapse and damage, reducing the mechanical strength of the chip and affecting its reliability during use.

[0003] While the addition of solvents such as adhesives can enhance the density and mechanical properties of bonded joints to a certain extent, these polymer adhesives have high melting points, making them difficult to remove during the sintering process. Residual adhesives in the system can affect the chip's electrical and thermal conductivity. Therefore, there is an urgent need to develop an interconnection method that delivers superior performance and meets the requirements of advanced packaging. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to propose an interconnection method using solvent-assisted sintering. By depositing nanometal particles directly on the deposition area of ​​the substrate and using auxiliary solvent-assisted sintering, better interconnection performance can be achieved to meet advanced packaging requirements.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] An interconnection method using solvent-assisted sintering comprises the following steps:

[0007] (1) depositing nano-metal particles in a deposition area of ​​the substrate to form a metal deposition layer in the deposition area of ​​the substrate;

[0008] (2) adding an auxiliary solvent dropwise to the surface of the metal deposition layer;

[0009] (3) Under a protective gas, aligning the mating workpiece with the substrate of step (2) and heat-bonding them, and obtaining a sandwich interconnection structure after cooling; wherein the evaporation temperature of the auxiliary solvent is lower than the heating temperature of the bonding, and the mating workpiece is a chip or another substrate mating with the substrate of step (2).

[0010] Preferably, the auxiliary solvent is any one or more of anhydrous ethanol, ethylene glycol, terpineol, polyethylene glycol, rosin, acetone and chloroform.

[0011] Preferably, in step (2), the amount of the auxiliary solvent added is 0.01 to 2 mL.

[0012] Preferably, step (1) specifically includes the following steps:

[0013] (1.1) Preparation of nano-metal particles using spark ablation technology;

[0014] (1.2) coating the nanometal particles with a molecular complexing agent to obtain coated nanometal particles;

[0015] (1.3) The coated nano-metal particles are deposited in a deposition area of ​​the substrate to form a metal deposition layer in the deposition area of ​​the substrate.

[0016] Preferably, in step (1.2), the nano-metal particles are coated with a molecular complexing agent under heating conditions; wherein the heating temperature is greater than the vaporization temperature of the molecular complexing agent.

[0017] Preferably, the molecular complexing agent includes any one or more combinations of polyvinyl pyrrolidone, cetyltrimethylammonium bromide, oleylamine, oleic acid, lactic acid, gelatin, gum arabic and imidazole compounds.

[0018] Preferably, step (1.1) specifically includes the following steps: installing the electrode target in a spark ablation device, applying a voltage of 0.1 to 10 kV and a pulse current of 1 to 40 mA to the electrode target, so that the electrode target undergoes a spark ablation reaction to generate nano-metal particles.

[0019] Preferably, in step (3), the bonding temperature of the heating bonding is 150-350° C., the bonding pressure is 0-40 MPa, and the ultrasonic driving frequency is 0-100 kHz.

[0020] Preferably, the nano-metal particles are nano-metal elemental particles or alloy nano-materials;

[0021] The nano-metal element particles include any one of gold, silver, copper, lithium, beryllium, magnesium, aluminum, calcium, vanadium, chromium, manganese, tungsten, iron, palladium, platinum, zinc, iridium, cobalt, nickel and tin nanoparticles;

[0022] The alloy nanomaterial includes any one of gold-palladium nanomaterial, silver-palladium nanomaterial, iron-copper nanomaterial, iron-zinc nanomaterial and silver-copper nanomaterial.

[0023] A sandwich interconnect structure is used in preparing an ultra-fine pitch all-copper interconnect structure and / or a copper-silver-copper interconnect structure. The sandwich interconnect structure is prepared using the above-mentioned interconnect method using solvent-assisted sintering.

[0024] The technical solutions provided by the embodiments of the present application may have the following beneficial effects:

[0025] 1. This technical solution prepares nanometal particles through spark ablation vapor deposition, then deposits the nanometal particles on a substrate. A specific auxiliary solvent is then added to the deposition area of ​​the substrate (i.e., the metal deposition layer) for auxiliary sintering. During the evaporation of the auxiliary solvent, under the action of capillary pressure, a pressure difference will be generated on both sides of the liquid surface. Driven by this pressure difference, the pores (i.e., the areas not filled when the nanometal particles form sintering necks during the sintering process) will tend to close, making the particles more tightly bonded, which is conducive to improving the sintering performance, thereby improving the shear strength, electrical conductivity, and thermal conductivity of the interconnect structure. This technical solution optimizes the chip interconnection process, can achieve stronger chip interconnection, and can meet the requirements of advanced packaging interconnection.

[0026] 2. This technical solution uses spark ablation technology to prepare nanometal particles, and the prepared nanometal particles are directly deposited in the deposition area of ​​the substrate. The method of this technical solution for preparing nanometal particles is not only simple and pollution-free, but also produces nanometal particles of fine and uniform size and better sintering performance. In addition, because the nanometal particles prepared by this technical solution are directly deposited in the deposition area of ​​the substrate, subsequent bonding can be performed directly, omitting the step of dipping and transferring the copper paste, resulting in a simple and efficient process.

[0027] 3. For easily oxidized nano-metal particles, this technical solution performs molecular complexation coating on the surface of the easily oxidized nano-metal particles during the deposition process to prevent the agglomeration and oxidation of the nano-metal particles. Through molecular complexation coating, the oxidation resistance of the nano-metal particles can be significantly improved, and chip interconnection with greater oxidation resistance and stronger connection can be achieved, which can meet the requirements of advanced packaging interconnection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of the interconnection method using solvent-assisted sintering in Example 1 of the present invention;

[0029] Figure 2 Schematic diagram of the application of the solvent-assisted sintering interconnection method in preparing an ultra-fine pitch all-copper interconnection structure according to Example 1 of the present invention;

[0030] Figure 3 Schematic diagram of the sintering process of nano-copper particles with the assistance of solvent in Example 1 of the present invention;

[0031] Figure 4 Schematic diagram of the structure of the vapor deposition equipment used in Example 1 of the present invention;

[0032] Figure 5 for Figure 4 A circuit diagram of a power supply device of the vapor deposition apparatus shown;

[0033] Among them: gas source device 1, air flow control valve 2, spark ablation device 3, power supply device 4, mounting chuck 5, electrode target material 6, coating device 7, molecular complexing agent 8, heating device 9, collecting device 10, nozzle 11, receiving base 12, exhaust hole 13. DETAILED DESCRIPTION

[0034] For ease of understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0035] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in this field or the product instructions were used. Raw materials used without manufacturer specified are all commercially available conventional products.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0038] An interconnection method using solvent-assisted sintering comprises the following steps:

[0039] (1) depositing nano-metal particles in a deposition area of ​​the substrate to form a metal deposition layer in the deposition area of ​​the substrate;

[0040] (2) adding an auxiliary solvent dropwise to the surface of the metal deposition layer;

[0041] (3) Under a protective gas, aligning the mating workpiece with the substrate of step (2) and heat-bonding them, and obtaining a sandwich interconnection structure after cooling; wherein the evaporation temperature of the auxiliary solvent is lower than the heating temperature of the bonding, and the mating workpiece is a chip or another substrate mating with the substrate of step (2).

[0042] It is worth mentioning that the present technical solution deposits the nano-metal particles directly on the deposition area of ​​the substrate, and then adds an auxiliary solvent to the surface of the deposition area of ​​the substrate (i.e., the metal deposition layer) for auxiliary sintering. The sintering described in the present technical solution includes bonding. During the bonding process, the auxiliary solvent evaporates. During the volatilization process, under the action of capillary pressure, a pressure difference will be generated on both sides of the liquid surface. Driven by this pressure difference, the holes that are not filled when the nano-metal particles form sintering necks during the bonding process will tend to close, making the particles more tightly bonded, which is conducive to improving the sintering performance. After the substrate and the mating workpiece (a chip or another substrate that matches the substrate in step (2)) are heated and bonded, they are cooled at room temperature to obtain a sandwich interconnection structure. The present technical solution adopts an interconnection method of solvent-assisted sintering. The addition of the auxiliary solvent provides a strong auxiliary effect in the bonding process, which can promote the diffusion between particles to form sintering necks and coarsening processes, such as Figure 5 As shown, direct sintering would result in large pores. This solution, by adding an auxiliary solvent for assisted sintering, improves sintering performance, making the sintered layer denser and more rigid, thereby increasing the shear strength, electrical conductivity, and thermal conductivity of the interconnect structure. This solution optimizes the interconnect process, enabling stronger connections and meeting the interconnect requirements of advanced packaging.

[0043] Further explanation, in the traditional interconnection process, it is generally necessary to adopt a chemical method to prepare nano copper paste, and then the suction head of the bonding machine is used to suck the chip to immerse the copper pillar structure on the chip in the nano copper paste and lift it up, so that the copper pillar structure on the chip is dipped with nano copper paste, and finally the chip and the substrate are bonded to obtain a sandwich interconnection structure. The use of this method to prepare nano copper paste and to dip and transfer nano copper paste is not only complicated and tedious, but also produces chemical pollution. The present technical solution deposits nano metal particles directly in the deposition area of ​​the substrate without the need to prepare nano copper paste, so there is no need to add chemical substances such as adhesives, which is not only simple in process but also free of chemical pollution. Moreover, since the nano metal particles prepared by the present technical solution are directly deposited in the deposition area of ​​the substrate, bonding can be performed directly later, omitting the step of dipping and transferring copper paste, and the process is simple and efficient.

[0044] This technical solution adds an auxiliary solvent with a volatilization temperature lower than the bonding heating temperature to the metal deposit layer to assist sintering. During the volatilization process of the auxiliary solvent, under the action of capillary pressure, a pressure difference will be generated on both sides of the liquid surface. Driven by this pressure difference, the pores between the nano-metal particles will tend to close, making the particles more tightly bonded, which is conducive to improving the sintering performance. Specifically, when the metal deposit layer without adding solvent is sintered, the particles are filled with gas medium. At this time, it is a solid-gas-solid phase sintering. Heat needs to be conducted through the gaps in the gas medium to achieve sintering between the particles. However, after the metal deposit layer is assisted by the solvent, the solvent exhibits strong wettability. Under the action of surface tension, it will squeeze out the gas medium filled between the particles. During hot pressing sintering, the particles, medium, and particles show a solid-liquid-solid phase sintering. Since the thermal conductivity of the liquid is significantly greater than that of air, heat is more easily conducted, which is conducive to achieving sintering between the particles, thereby improving the sintering performance.

[0045] Further explanation: the interconnection method using solvent-assisted sintering in this technical solution can be used to prepare sandwich interconnection structures such as ultra-fine pitch all-copper interconnection structures and copper-silver-copper interconnection structures.

[0046] Preferably, in order to further improve the interconnection effect, the present technical solution further includes the steps of cleaning and pre-treating the mating workpiece and substrate before step (1), including the following steps: selecting a substrate and chip of a certain specification, cleaning them and performing pre-treatment, and the pre-treatment includes using one or more of SAM, acid treatment and plasma treatment.

[0047] Preferably, the sizes of the chip and substrate are 1 mm to 300 mm respectively.

[0048] It is worth noting that the method of aligning and heating the workpiece and substrate for bonding in step (3) of the present technical solution is well known.

[0049] Preferably, when the interconnection method of this scheme is used to prepare fine-pitch interconnection structures such as ultra-fine-pitch all-copper interconnection structures, the mating workpiece at this time is a chip. Since the specifications of the chip are very small, the mating workpiece (chip) and the substrate can be aligned through the optical system of the bonding machine, and then pressure, ultrasound and temperature are applied to perform bonding in the bonding machine.

[0050] Preferably, when the interconnection method of the present scheme is used to prepare an interconnection structure such as a copper-silver-copper interconnection structure, the mating workpiece at this time is another substrate that cooperates with the substrate deposited with the metal deposition layer. Since the area of ​​the substrate is large, the deposition areas of the mating workpiece and the substrate can be manually aligned, and then sintered in a hot press furnace.

[0051] Preferably, the protective gas of the present technical solution includes one or more of nitrogen, helium and argon.

[0052] Preferably, in step (1), the method of depositing the nano-metal particles in the deposition area of ​​the substrate includes any one of direct deposition, filtration deposition, diffusion deposition, stamping deposition, spray deposition and electrostatic deposition.

[0053] Further explanation: the auxiliary solvent is any one or more combinations of anhydrous ethanol, ethylene glycol, terpineol, polyethylene glycol, rosin, acetone and chloroform.

[0054] Preferably, the auxiliary solvent of the present technical solution is a combination of any one or more of anhydrous ethanol, ethylene glycol, terpineol, polyethylene glycol, rosin, acetone and chloroform. The use of these auxiliary solvents can make the particles more tightly bonded during the heating and bonding process, which is more conducive to improving the sintering performance. The present technical solution performs auxiliary sintering by adding any one or more auxiliary solvents of anhydrous ethanol, ethylene glycol, terpineol, polyethylene glycol, rosin, acetone and chloroform to the metal deposit layer. During the volatilization process of these auxiliary solvents, under the action of capillary pressure, a pressure difference will be generated on both sides of the liquid surface. Driven by this pressure difference, the pores between the nano-metal particles will tend to close, making the particles more tightly bonded, which is more conducive to improving the sintering performance.

[0055] Further explanation: in step (2), the amount of the auxiliary solvent added is 0.01 to 2 mL.

[0056] It is worth noting that the amount of auxiliary solvent added in this technical solution is 0.01 to 2 mL. Within this amount range, the particles can be more tightly bonded, which is more conducive to improving the sintering performance and making the mechanical strength of the prepared sandwich interconnection structure higher.

[0057] Specifically, the method of adding auxiliary solvent to the metal deposition layer in the present technical solution is well known. Preferably, one of the dripping methods such as dripping method, spin coating method, spraying method and deposition method can be adopted to better control the amount of auxiliary solvent added.

[0058] To further illustrate, step (1) specifically includes the following steps:

[0059] (1.1) Preparation of nano-metal particles using spark ablation technology;

[0060] (1.2) coating the nanometal particles with a molecular complexing agent to obtain coated nanometal particles;

[0061] (1.3) The coated nano-metal particles are deposited in a deposition area of ​​the substrate to form a metal deposition layer in the deposition area of ​​the substrate.

[0062] Preferably, the present technical solution prepares nano-metal particles by spark ablation, and then deposits the nano-metal particles on the substrate by vapor deposition.

[0063] Step (1.1) of this technical solution uses spark ablation technology to prepare nanometal particles, and the prepared nanometal particles can be directly deposited in the deposition area of ​​the substrate. The method of this technical solution for preparing nanometal particles is not only simple and pollution-free, but also produces nanometal particles of fine and uniform size and better sintering performance. Furthermore, because the nanometal particles prepared by this technical solution are directly deposited in the deposition area of ​​the substrate, subsequent bonding can be performed directly, resulting in a simple and efficient process.

[0064] It is worth noting that when the nano-metal particles are nano-metal particles with good oxidation resistance (such as nano-silver particles), the nano-metal particles do not need to be coated. The nano-metal particles prepared by spark ablation technology can be directly deposited on the substrate. For easily oxidized nano-metal particles (such as nano-copper particles), preferably, during the deposition process, molecular complex coating is performed on the surface of the easily oxidized nano-metal particles to prevent the agglomeration and oxidation of the nano-metal particles. The molecular complex coating can significantly improve the oxidation resistance of the nano-metal particles, and can achieve more resistant to oxidation and stronger chip interconnection, which can meet the requirements of advanced packaging interconnection. If the easily oxidized nano-metal particles (such as nano-copper particles) are not coated for oxidation resistance, the electrical and thermal conductivity of the oxidized nano-metal particles will drop significantly, and it will not be easy to sinter.

[0065] Preferably, in step (1.3), the deposition time is 5 to 60 minutes, more preferably, the deposition time is 30 minutes.

[0066] As a further explanation, in step (1.2), the nano-metal particles are coated with a molecular complexing agent under heating conditions; wherein the heating temperature is greater than the vaporization temperature of the molecular complexing agent.

[0067] The technical solution adopts gas phase coating, which vaporizes the molecular complexing agent by heating. The vaporized molecular complexing agent combines with the electrons on the surface of the nano-metal particles to form a complex coating layer to prevent the agglomeration and oxidation of the nano-metal particles, thereby improving the oxidation resistance of the nano-metal particles.

[0068] Specifically, the molecular complexing agent used in this technical solution is well known. Those skilled in the art can select a molecular complexing agent that vaporizes upon heating and can combine with electrons on the surface of the nanometal particles to form a complex coating. The heating temperature used in this technical solution is a temperature at which the molecular complexing agent vaporizes, and the heating temperature can be determined based on the type of molecular complexing agent used.

[0069] To further illustrate, the molecular complexing agent includes any one or more combinations of polyvinyl pyrrolidone, cetyltrimethylammonium bromide, oleylamine, oleic acid, lactic acid, gelatin, gum arabic and imidazole compounds.

[0070] Preferably, to achieve better coating effects on nano-metal particles, the molecular complexing agent of the present technical solution is selected from any one or more combinations of polyvinyl pyrrolidone, cetyltrimethylammonium bromide, oleylamine, oleic acid, lactic acid, gelatin, gum arabic, and imidazole compounds. These molecular complexing agents have good coating effects and require lower heating temperatures for coating. The imidazole compounds include imidazole compounds such as 2-methylimidazole and benzimidazole.

[0071] Specifically, when the molecular complexing agent is 2-methylimidazole, the heating temperature can be set to 45-55°C, more preferably, the heating temperature is 50°C; when the molecular complexing agent is benzimidazole, the heating temperature can be set to 60-70°C; when the molecular complexing agent is hexadecyltrimethylammonium bromide, the heating temperature can be set to 45-55°C, more preferably, the heating temperature is 50°C.

[0072] To further explain, step (1.1) specifically includes the following steps: installing the electrode target in a spark ablation device, applying a voltage of 0.1 to 10 kV and a pulse current of 1 to 40 mA to the electrode target, and causing the electrode target to undergo a spark ablation reaction to generate nano-metal particles.

[0073] It is worth noting that different breakdown voltages are selected according to different electrode target materials and reaction conditions. When the voltage value reaches the breakdown voltage, as the current value increases, the electric spark will transform into an arc, and the generation of an arc will seriously affect the efficiency of electrode ablation, which is not conducive to the preparation of nanoparticles. In order to maximize the yield of the produced nanoparticles and at the same time ensure the generation of stable electric sparks, the current value needs to be increased to a value close to the limit of arc generation. Preferably, in the spark ablation device of the present technical solution, the voltage range applied to the electrode target is 0.1 to 10 kV, and the pulse current range applied is 1 to 40 mA.

[0074] Further explanation, in step (3), the bonding temperature of the heating bonding is 150-350° C., the bonding pressure is 0-40 MPa, and the ultrasonic driving frequency is 0-100 kHz.

[0075] Specifically, bonding is a type of sintering that offers the advantages of high precision and is suitable for preparing sandwich interconnect structures. Preferably, this technical solution bonds the workpiece and substrate at 150-350°C, 0-40 MPa pressure, and 0-100 kHz ultrasonic drive frequency, further improving bonding efficiency and enhancing the connection strength, electrical and thermal conductivity, and electrical conductivity between the chip and substrate.

[0076] Preferably, the bonding time is 2 to 40 minutes.

[0077] Further explanation: the nano metal particles are nano metal element particles or alloy nano materials;

[0078] The nano-metal element particles include any one of gold, silver, copper, lithium, beryllium, magnesium, aluminum, calcium, vanadium, chromium, manganese, tungsten, iron, palladium, platinum, zinc, iridium, cobalt, nickel and tin nanoparticles;

[0079] The alloy nanomaterial includes any one of gold-palladium nanomaterial, silver-palladium nanomaterial, iron-copper nanomaterial, iron-zinc nanomaterial and silver-copper nanomaterial.

[0080] A sandwich interconnect structure is used in preparing an ultra-fine pitch all-copper interconnect structure and / or a copper-silver-copper interconnect structure. The sandwich interconnect structure is prepared using the above-mentioned interconnect method using solvent-assisted sintering.

[0081] Specifically, the sandwich interconnect structure of this technical solution includes a copper-silver-copper interconnect structure and an ultra-fine pitch all-copper interconnect structure.

[0082] Preferably, the present technical solution may adopt the following vapor deposition equipment to prepare nano-metal particles, and deposit the nano-metal particles in the deposition area of ​​the substrate.

[0083] like Figure 4 and Figure 5 As shown, the vapor deposition equipment includes a gas source device 1, a spark ablation device 3 and a collecting device 10 which are connected in sequence through pipelines. An airflow control valve 2 is provided between the gas source device 1 and the spark ablation device 3, and between the spark ablation device 3 and the collecting device 10. The airflow control valve 2 is used to control the flow rate of the protective gas; the spark ablation device 3 includes a power supply device 4, a mounting chuck 5 and an electrode target material 6, and the spark ablation device 3 is used to produce nano-metal particles; the collecting device 10 includes a nozzle 11, a receiving substrate 12 and an exhaust hole 13; when preparing nano-metal particles, the substrate is installed on the receiving substrate 12, and the collecting device 10 is used to collect the nano-metal particles and deposit the nano-metal particles in the deposition area of ​​the substrate.

[0084] In a preferred technical solution of the present technical solution, the vapor deposition equipment further includes a coating device 7 and a heating device 9. The coating device 7 contains a molecular complexing agent 8, and the coating device 7 is placed in the heating device 9. The spark ablation device 3 is connected to the coating device 7 through a pipe, and the pipe extends into the interior of the coating device 7, and the output port of the pipe is close to the molecular complexing agent 8. At the same time, the coating device 7 is connected to the collecting device 10, and the coating device 7 is used for molecular complexing and coating the nano-metal particles produced in the spark ablation device 3. The vapor deposition equipment of the present technical solution including the coating device 7 is used to prepare easily oxidizable nano-metal particles, and deposit the coated nano-metal particles on the surface of the substrate.

[0085] The technical solution of the present invention is further described below with reference to specific embodiments and comparative examples.

[0086] Example 1

[0087] This embodiment adopts a solvent-assisted sintering interconnection method, which includes the following steps:

[0088] (1) Selecting a chip and a substrate with a copper pillar diameter of 40 μm, a copper pillar spacing of 40 μm, and 9 copper pillar bumps, and cleaning the substrate and chip, and then pre-treating them with ultrasonic cleaning using dilute sulfuric acid; masking the non-deposition area of ​​the substrate with a mask; using a vapor deposition device to prepare nano-copper particles; using a molecular complexing agent and under heating conditions, molecular complexing coating is performed on the surface of the nano-copper particles to obtain coated nano-copper particles, and the coated nano-copper particles are deposited in the deposition area of ​​the treated substrate to form a metal deposition layer in the deposition area of ​​the substrate; wherein the voltage applied to the copper target in the spark ablation device is 1.3 kV, the applied pulse current range is 11 mA, the carrier gas type in the gas source device is nitrogen, the molecular complexing agent is 2-methylimidazole, the heating temperature of the coating device is 50°C, and the deposition method is diffusion deposition;

[0089] (2) Loading the substrate from step (1) into a bonding machine, the bonding machine sucks the chip with the copper pillar I / O output port and flips it so that the copper pillar structure faces outward; dripping 0.03 mL of auxiliary solvent (ethylene glycol) onto the surface of the metal deposition layer of the substrate;

[0090] (3) Protective gas (nitrogen) is introduced, and the copper pillars and the corresponding gaskets (i.e., metal deposition layers) on the substrate are aligned through the optical system of the bonding machine. A pressure of 10 MPa, an ultrasonic driving frequency of 0 kHz, and a temperature of 260°C are applied for bonding, and the bonding time is 8 minutes. After cooling to room temperature, the mask plate is removed to obtain an ultra-fine pitch all-copper interconnect structure.

[0091] Specifically, the ultra-fine-pitch all-copper interconnect structure obtained in this embodiment was tested, and the overall shear strength obtained by shearing with a push-pull test machine was 42.6 MPa, the resistivity measured by the four-point probe method was 6.1 μΩcm, and the pass rate of the heating box high-temperature storage test was 99%. This shows that the interconnection method using solvent-assisted sintering in this technical solution can achieve better interconnection performance and can be applied to the preparation of ultra-fine-pitch all-copper interconnect structures. The prepared ultra-fine-pitch all-copper interconnect structure has high overall shear strength and good conductivity, and the ultra-fine-pitch all-copper interconnect structure has good stability and reliability in high-temperature environments.

[0092] Example 2

[0093] This embodiment adopts a solvent-assisted sintering interconnection method, which includes the following steps:

[0094] (1) Copper substrates of sizes 10 mm × 10 mm and 2 mm × 2 mm were selected. Before the experiment, the copper substrates were polished with sandpaper to remove surface dirt and oxide film to reveal the metallic luster; then they were placed in 10% dilute sulfuric acid and anhydrous ethanol and cleaned in an ultrasonic cleaner; nanosilver particles were prepared by vapor deposition equipment, and the nanosilver particles were deposited on the deposition area of ​​the treated 10 mm × 10 mm copper substrate to form a silver deposition layer in the deposition area of ​​the copper substrate; wherein, the voltage applied to the silver electrode target in the spark ablation device was 1.2 kV, the pulse current range applied was 10 mA, the carrier gas type in the gas source device was argon, and the deposition method was stamping deposition;

[0095] (2) 0.06 mL of auxiliary solvent (ethylene glycol) was dripped onto the silver deposition layer (i.e., the silver deposition area) of a 10 mm × 10 mm substrate;

[0096] (3) Copper substrates of sizes 10 mm × 10 mm and 2 mm × 2 mm were aligned and loaded into a hot press furnace. Protective gas (argon) was introduced, and a pressure of 2 MPa, an ultrasonic driving frequency of 10 kHz, and a temperature of 260°C were applied for sintering. The sintering time was 30 min. After cooling at room temperature, a copper-silver-copper interconnection structure was obtained.

[0097] Specifically, testing of the copper-silver-copper interconnect structure obtained in this embodiment revealed an overall shear strength of 80 MPa, a resistivity of 0.5 μΩcm, and a high-temperature storage test pass rate of 99%. This demonstrates that the solvent-assisted sintering interconnect method employed in this technical solution can achieve improved interconnect performance and can be applied to the preparation of copper-silver-copper interconnect structures. The resulting copper-silver-copper interconnect structure exhibits high overall shear strength and good electrical conductivity, and exhibits excellent stability and reliability in high-temperature environments.

[0098] Example 3

[0099] This embodiment adopts a solvent-assisted sintering interconnection method, which includes the following steps:

[0100] (1) A chip and substrate with a copper pillar diameter of 20 μm, a copper pillar spacing of 40 μm and 100 copper pillar bumps were selected. After cleaning the substrate and chip, they were pretreated with Ar plasma to clean and activate the surface. The flow rate, RF power and pressure were 140 sccm, 100 W and 130 Pa respectively. N2 plasma was then used to passivate the surface to prevent oxidation. The flow rate, RF power and pressure were 250 sccm, 100 W and 130 Pa respectively. The non-deposition area on the substrate was covered with a mask. Vapor deposition was used. Nano-copper particles are prepared using a device; a molecular complexing agent is used and, under heating conditions, molecular complexing coating is performed on the surface of the nano-copper particles to obtain coated nano-copper particles, and the coated nano-copper particles are deposited on a deposition area of ​​a treated substrate to form a copper deposition layer in the deposition area of ​​the substrate; wherein, the voltage applied to the copper target in the spark ablation device is 1.2 kV, the pulse current applied is in the range of 10 mA, the carrier gas in the gas source device is argon, the molecular complexing agent is benzimidazole, the heating temperature of the coating device is 70° C., and the deposition method is stamping deposition;

[0101] (2) The substrate of step (1) is loaded into a bonding machine. The bonding machine sucks the chip with the copper pillar I / O output port and flips it so that the copper pillar structure faces outward; 0.02 mL of auxiliary solvent (polyethylene glycol) is dripped into the copper deposit layer of the substrate;

[0102] (3) Protective gas (argon) is introduced, and the copper pillars and the corresponding pads on the substrate (i.e., the copper deposited layer) are aligned through the optical system of the bonding machine. A pressure of 2 MPa, an ultrasonic driving frequency of 10 kHz, and a temperature of 260°C are applied for bonding. The bonding time is 8 minutes. After cooling at room temperature, the mask plate is removed to obtain an ultra-fine pitch all-copper interconnect structure.

[0103] Specifically, the ultra-fine pitch all-copper interconnect structure obtained in this embodiment was tested, and the overall shear strength was found to be 30.2 MPa, the resistivity was 8.1 μΩcm, and the high-temperature storage test pass rate was 96%.

[0104] Example 4

[0105] This embodiment adopts a solvent-assisted sintering interconnection method, which includes the following steps:

[0106] (1) A chip and a substrate with a copper pillar diameter of 15 μm, a chip spacing of 30 μm and 50 copper pillar bumps were selected, and the substrate and the chip were ultrasonically cleaned with dilute hydrochloric acid and then treated with H2 plasma, with a flow rate, radio frequency power and pressure of 300 sccm, 100 W and 100 Pa respectively; the non-deposition area on the substrate was masked with a mask; nano-copper particles were prepared using a vapor deposition device; then a molecular complexing agent was used under heating conditions to perform molecular complexing coating on the surface of the nano-copper particles to obtain coated nano-copper particles, and the coated nano-copper particles were deposited in the deposition area of ​​the treated substrate to form a copper deposition layer in the deposition area of ​​the substrate; wherein the voltage applied to the copper target in the spark ablation device was 1.5 kV, the pulse current range applied was 15 mA, the carrier gas type in the gas source device was argon, the molecular complexing agent was hexadecyltrimethylammonium bromide, the heating temperature of the coating device was 50 ° C, and the deposition method was diffusion deposition;

[0107] (2) Loading the substrate from step (1) into a bonding machine, the bonding machine sucks the chip with the copper pillar I / O output port and flips it so that the copper pillar structure faces outward; dripping 0.02 mL of auxiliary solvent (ethylene glycol) into the copper deposit layer of the substrate;

[0108] (3) Protective gas (argon) is introduced, and the copper pillars and the corresponding pads on the substrate (i.e., the copper deposited layer) are aligned through the optical system of the bonding machine. A pressure of 10 MPa, an ultrasonic driving frequency of 20 kHz, and a temperature of 300°C are applied for bonding, and the bonding time is 8 minutes. After cooling at room temperature, the mask plate is removed to obtain an ultra-fine pitch all-copper interconnect structure.

[0109] Specifically, the ultra-fine pitch all-copper interconnect structure obtained in this embodiment was tested, and the overall shear strength was found to be 26.3 MPa, the resistivity was 5.8 μΩcm, and the high-temperature storage test pass rate was 99%.

[0110] Example 5

[0111] This embodiment adopts a solvent-assisted sintering interconnection method, which includes the following steps:

[0112] (1) A chip and substrate with a copper pillar diameter of 25 μm, a chip pitch of 50 μm, and 80 copper pillar bumps were selected. The substrate and chip were ultrasonically cleaned with dilute hydrochloric acid and then treated with Ar plasma to clean and activate the surface. The flow rate, RF power, and pressure were 140 sccm, 100 W, and 130 Pa, respectively. The surface was then passivated with N2 plasma to prevent oxidation. The flow rate, RF power, and pressure were 250 sccm, 100 W, and 130 Pa, respectively. The non-deposition area on the substrate was masked with a mask. Vapor deposition was used. The device prepares nano-copper particles; then, a molecular complexing agent is used to perform molecular complexing coating on the surface of the nano-copper particles under heating conditions to obtain coated nano-copper particles; the coated nano-copper particles are deposited on a deposition area of ​​a treated substrate to form a copper deposition layer in the deposition area of ​​the substrate; wherein, the voltage applied to the copper target material in the spark ablation device is 1.8 kV, the applied pulse current range is 15 mA, the carrier gas type in the gas source device is helium, the molecular complexing agent is benzimidazole, the coating device is heated at 60°C, and the deposition method is stamping deposition;

[0113] (2) The substrate of step (1) is loaded into a bonding machine. The bonding machine sucks the chip with the copper pillar I / O output port and flips it so that the copper pillar structure faces outward; 0.03 mL of auxiliary solvent (polyethylene glycol) is dripped into the copper deposit layer of the substrate;

[0114] (3) Protective gas (helium) is introduced, and the copper pillars are aligned with the corresponding pads on the substrate (i.e., the copper deposited layer) through the optical system of the bonding machine. A pressure of 30 MPa, an ultrasonic driving frequency of 60 kHz, and a temperature of 200°C are applied for bonding, and the bonding time is 10 minutes. After cooling to room temperature, the mask plate is removed to obtain an ultra-fine pitch all-copper interconnect structure.

[0115] Specifically, the ultra-fine pitch all-copper interconnect structure obtained in this embodiment was tested, and the overall shear strength was found to be 28.26 MPa, the resistivity was 10.2 μΩcm, and the high-temperature storage test pass rate was 96%.

[0116] Comparative Example 1

[0117] The chip and substrate selected in the interconnection method using solvent-assisted sintering in this comparative example are the same as those in Example 1, and the interconnection method using solvent-assisted sintering in this comparative example is also the same as the substrate in Example 1. The difference is that in step (2) of this comparative example, 0.03 mL of ethylene glycol is not dripped into the metal deposition layer of the substrate (that is, this comparative example does not use an auxiliary solvent for auxiliary sintering), and an ultra-fine pitch all-copper interconnection structure is prepared according to the above method.

[0118] Specifically, the ultra-fine pitch all-copper interconnect structure obtained in this comparative example was tested, and the overall shear strength of the ultra-fine pitch all-copper interconnect structure was 9.1 MPa, the resistivity was 12.1 μΩcm, and the high-temperature storage test pass rate was 86%. This shows that compared with Example 1, the lack of auxiliary solvent for auxiliary sintering results in poor sintering performance. The overall shear strength of the ultra-fine pitch all-copper interconnect structure obtained is greatly reduced, and the resistivity is increased. The resistivity is close to twice that of the ultra-fine pitch all-copper interconnect structure in Example 1, which shows that the conductive performance is also significantly reduced. At the same time, the high-temperature storage test pass rate is also significantly reduced.

[0119] Comparative Example 2

[0120] The substrate selected in the interconnection method using solvent-assisted sintering in this comparative example is the same as that in Example 2, and the interconnection method using solvent-assisted sintering in this comparative example is also the same as that in Example 2. The difference is that in step (2), 0.06 mL of ethylene glycol is not dripped into the silver deposition layer of the 10 mm × 10 mm substrate in this comparative example (that is, no auxiliary solvent is used for auxiliary sintering in this comparative example), and a copper-silver-copper interconnection structure is prepared according to the above method.

[0121] Specifically, the copper-silver-copper interconnect structure obtained in this comparative example was tested, and the overall shear strength of the copper-silver-copper interconnect structure was 20 MPa, the resistivity was 3 μΩcm, and the high-temperature storage test pass rate was 92%. This shows that compared with Example 2, the lack of auxiliary solvent for auxiliary sintering resulted in poor sintering performance. The overall shear strength of the copper-silver-copper interconnect structure obtained decreased, and the resistivity increased. The resistivity was six times that of the copper-silver-copper interconnect structure in Example 2, indicating a significant decrease in conductivity. Simultaneously, the high-temperature storage test pass rate was significantly reduced.

[0122] Comparative Example 3

[0123] The chip and substrate selected in the interconnection method using solvent-assisted sintering in this comparative example are the same as those in Example 1, and the interconnection method using solvent-assisted sintering in this comparative example is also the same as the substrate in Example 1. The difference is that in step (1) of this comparative example, no molecular complexing agent (2-methylimidazole) is used to coat the nano-copper particles. Nano-copper particles prepared by vapor deposition equipment are directly deposited on the deposition area of ​​the substrate, and an ultra-fine pitch all-copper interconnection structure is prepared according to the above method.

[0124] Specifically, the ultra-fine-pitch all-copper interconnect structure obtained in this comparative example was tested, and the overall shear strength and resistivity of the ultra-fine-pitch all-copper interconnect structure were 9.6 MPa, 13.1 μΩcm, and a high-temperature storage test pass rate of 78%. This shows that, compared to Example 1, if the easily oxidized nano-copper particles are not coated with a molecular complexing agent, the overall shear strength of the ultra-fine-pitch all-copper interconnect structure is significantly reduced, the resistivity is increased, and the high-temperature storage test pass rate is also significantly reduced.

[0125] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. An interconnection method using solvent-assisted sintering, characterized in that: The following steps are involved: (1) depositing nano-metal particles in a deposition area of ​​a substrate to form a metal deposition layer in the deposition area of ​​the substrate; (2) adding an auxiliary solvent to the surface of the metal deposition layer; (3) Under a protective gas atmosphere, aligning the mating workpiece with the substrate of step (2) and heating and bonding them, and obtaining a sandwich interconnection structure after cooling; wherein the evaporation temperature of the auxiliary solvent is lower than the heating temperature of the bonding, and the mating workpiece is a chip or another substrate mating with the substrate of step (2); The auxiliary solvent is any one or more of anhydrous ethanol, ethylene glycol, terpineol, polyethylene glycol, rosin, acetone and chloroform; In step (2), the amount of the auxiliary solvent added is 0.01~2mL; In step (3), the bonding temperature of the heating bonding is 150-350°C, the bonding pressure is 0-40 MPa, and the ultrasonic driving frequency is 0-100 kHz; Step (1) specifically includes the following steps: (1.1) Preparation of nano-metal particles using spark ablation technology; (1.2) coating the nanometal particles with a molecular complexing agent to obtain coated nanometal particles; (1.3) depositing the coated nano-metal particles in a deposition area of ​​the substrate to form a metal deposition layer in the deposition area of ​​the substrate; Among them, step (1.1) specifically includes the following steps: installing the electrode target material in a spark ablation device, applying a voltage of 0.1~10kV and a pulse current of 1~40mA to the electrode target material, and causing the electrode target material to undergo a spark ablation reaction to generate nano-metal particles.

2. The interconnection method using solvent-assisted sintering according to claim 1, characterized in that: In step (1.2), the nano-metal particles are coated with a molecular complexing agent under heating conditions; wherein the heating temperature is greater than the vaporization temperature of the molecular complexing agent.

3. The interconnection method using solvent-assisted sintering according to claim 2, characterized in that: The molecular complexing agent includes any one or more combinations of polyvinyl pyrrolidone, cetyltrimethylammonium bromide, oleylamine, oleic acid, lactic acid, gelatin, gum arabic and imidazole compounds.

4. The interconnection method using solvent-assisted sintering according to claim 1, characterized in that: The nano-metal particles are nano-metal elemental particles or alloy nano-materials; The nano-metal element particles include any one of gold, silver, copper, lithium, beryllium, magnesium, aluminum, calcium, vanadium, chromium, manganese, tungsten, iron, palladium, platinum, zinc, iridium, cobalt, nickel and tin nanoparticles; The alloy nanomaterial includes any one of gold-palladium nanomaterial, silver-palladium nanomaterial, iron-copper nanomaterial, iron-zinc nanomaterial and silver-copper nanomaterial.

5. A sandwich interconnect structure is used in the preparation of an ultra-fine pitch all-copper interconnect structure and / or a copper-silver-copper interconnect structure, characterized in that: The sandwich interconnect structure is prepared using the interconnect method using solvent-assisted sintering according to any one of claims 1 to 4.

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