A multi-phase synergistic stress self-adapting composite sealing paste, a preparation method thereof and a semiconductor packaging structure

Abstract

The application discloses a multi-phase stress self-adapting composite sealing paste, a preparation method thereof and a semiconductor packaging structure. The paste comprises 60-75% low-melting-point lead-free glass powder, 8-15% nano metal alloy particles, 3-7% negative thermal expansion compensation phase, 10-15% organic carrier and 0.5-2% modified additive according to mass percentage. The softening point Ts of the nano metal alloy particles is lower than the glass transition temperature Tg of the glass powder, the nano particles are uniformly distributed on the surface of the glass powder and form a micro anchoring structure. In the sealing cooling stage, the Ts-Tg temperature difference gradient is utilized to promote the plastic rheology of the nano particles, and the negative thermal expansion compensation phase is utilized to neutralize the interface residual thermal stress. The preparation method comprises surface modification, vacuum stirring, three-roll grinding and conductivity monitoring. The packaging structure comprises a substrate, a cover plate and a paste sintering sealing layer. The application improves the air tightness and reliability of the semiconductor packaging and is suitable for MEMS sensors and high-power modules.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor packaging materials, and mainly to a multiphase synergistic stress-adaptive composite sealing paste, its preparation method, and semiconductor packaging structure. Background Technology

[0002] As MEMS pressure sensor chips and high-power semiconductor modules evolve towards miniaturization and high reliability, the requirements for hermetic packaging are becoming increasingly stringent. Traditional sealing materials mainly use slurries formulated with low-melting-point glass powder and organic carriers, which are sintered to form a sealing layer to achieve a seal between the substrate and the cover plate. However, during the sealing cooling process, due to the mismatch in the coefficient of thermal expansion (CTE) between the low-melting-point glass powder and the semiconductor substrate / cover plate, significant residual thermal stress is generated, leading to microcracks at the sealing interface, decreased hermeticity, or even failure, severely affecting the long-term reliability and lifespan of the device.

[0003] To mitigate CTE mismatch, existing technologies typically add negative thermal expansion (NTE) compensating phases (such as ZrW) to the glass powder. O (e.g., by passively adjusting the overall coefficient of thermal expansion to reduce stress). However, this method can only partially alleviate macroscopic CTE differences and cannot effectively neutralize the dynamic residual thermal stress generated during the sealing and cooling stage. Furthermore, the NTE phase is prone to chemical interdiffusion with the glass matrix, leading to a decrease in the compensation effect. At the same time, the uneven dispersion of filler particles and weak interfacial bonding in existing slurries further exacerbate local stress concentration.

[0004] Furthermore, traditional preparation processes (such as simple stirring and grinding) struggle to achieve stable anchoring of nanoscale fillers and glass powder, resulting in poor slurry storage stability and sealing layer uniformity. Current technologies have not yet proposed a sealing slurry capable of actively and adaptively releasing residual interfacial thermal stress using a multiphase synergistic mechanism, along with its corresponding preparation method and encapsulation structure. Summary of the Invention

[0005] In view of the above-mentioned technical problems in the prior art, this application proposes a multiphase synergistic stress self-adaptive composite sealing slurry, its preparation method and semiconductor packaging structure.

[0006] According to one aspect of the present invention, a multiphase synergistic stress-adaptive composite sealing slurry is proposed, comprising the following components by mass percentage: 60%~75% low-melting-point lead-free glass powder, 8%~15% nano-metal alloy particles, 3%~7% negative thermal expansion compensation phase, 10%~15% organic carrier, and 0.5%~2% modifying additives; wherein, the softening point Ts of the nano-metal alloy particles is lower than the glass transition temperature Tg of the low-melting-point lead-free glass powder; the nano-metal alloy particles are uniformly distributed on the surface of the low-melting-point lead-free glass powder and form a micro-anchoring structure; during the sealing cooling stage, the temperature gradient between Ts and Tg is used to induce plastic rheology in the nano-metal alloy particles before the glass powder matrix, and the volume shrinkage of the negative thermal expansion compensation phase synergistically neutralizes the residual thermal stress at the sealing interface. Through Ts The temperature gradient of Tg, the micro-anchoring structure of nanoparticles, and the volume shrinkage of the negative thermal expansion phase achieve "multi-phase synergistic stress self-adaptation", which actively neutralizes residual thermal stress at the interface during the sealing and cooling stage, significantly improving the hermeticity and long-term reliability of the packaging, and overcoming the shortcomings of traditional passive CTE matching.

[0007] In a specific embodiment, the softening point Ts of the nano-metal alloy particles and the glass transition temperature Tg of the low-melting-point lead-free glass powder satisfy the following condition: 20℃≤Tg-Ts≤80℃. By further limiting the temperature difference range between Ts and Tg, the plastic rheological initiation window is precisely controlled, ensuring that the nano-alloy particles deform before the glass matrix in the optimal temperature range, optimizing the stress release effect, and avoiding premature or delayed failure.

[0008] In a specific embodiment, the average particle size ratio of the nano-metal alloy particles to the low-melting-point lead-free glass powder is taken in the range of 1:20 to 1:100.

[0009] In a specific embodiment, the surface of the low-melting-point lead-free glass powder has micropores with an average pore size of 50nm to 500nm, and the nano-metal alloy particles are partially embedded in the micropores to form an interface anchor. This configuration allows the nanoparticles to be stably embedded to form an interface anchor structure, improving the uniformity of slurry dispersion and the interfacial bonding strength of the sealing layer, and preventing stress concentration caused by particle agglomeration or detachment.

[0010] In a specific embodiment, the negative thermal expansion compensation phase is zirconium tungstate particles coated with a silica layer. The silica coating layer has a thickness of 5 nm to 20 nm and is used to suppress the chemical interdiffusion between zirconium tungstate and the glass powder matrix within the sealing temperature range. This configuration effectively suppresses chemical interdiffusion within the sealing temperature range, maintains the volume shrinkage activity of the NTE phase, and ensures long-term stability through synergistic stress neutralization with the nano-alloy particles.

[0011] In a specific embodiment, the low-melting-point lead-free glass powder is selected from at least one of the Bi2O3-ZnO-B2O3 or V2O5-P2O5-BaO glass powders; the nano-metal alloy particles are nano-silver-tin alloy particles. This configuration ensures the low-temperature sealing compatibility, lead-free environmental friendliness, and plastic rheological properties of the slurry.

[0012] In specific embodiments, the modifying agents include silane coupling agents and surfactants; the silane coupling agents form a chemically bonded hydrophobic monolayer on the surface of the nano-metal alloy particles. The hydrophobic monolayer formed by the silane coupling agents enhances the steric stabilization effect of the nanoparticles in the organic carrier, prevents aggregation, and further ensures the uniformity of the micro-anchoring structure and the storage stability of the slurry.

[0013] According to a second aspect of the present invention, a method for preparing a multiphase synergistic stress-adaptive composite sealing slurry as described above is provided, comprising the following steps: S1: Modification treatment of nano-metal alloy particles by surface organophilic modification; S2: Low-melting-point lead-free glass powder, modified nano-metal alloy particles, negative thermal expansion compensation phase and organic carrier are mixed by vacuum planetary stirring. S3: The premixed slurry is circulated and ground using a three-roll mill, with the pressure between the rollers controlled at 2MPa-5MPa. The mechanical shear heat generated by grinding causes the nano-metal alloy particles to undergo local plastic deformation and is pressed into the micropores on the surface of the glass powder. S4: Monitor the change in conductivity of the slurry in real time during the grinding process. When the conductivity fluctuation rate is less than 2% after three consecutive grinding cycles, stop grinding and perform vacuum degassing.

[0014] In a specific embodiment, the cyclic grinding in S3 adopts a staged pressure control method: first, 1-2 rounds of low-pressure pre-grinding are performed at 1MPa-2MPa to achieve initial dispersion, and then the pressure is gradually increased to 2MPa-5MPa for 2-3 rounds of high-pressure main grinding. Staged pressure control allows mechanical shear heat to accumulate gradually, avoiding particle agglomeration or overheating, while ensuring uniform local plastic deformation, further improving the stability of the anchoring structure and the consistency of slurry quality.

[0015] According to a third aspect of the present invention, a semiconductor packaging structure is proposed that utilizes the aforementioned multiphase synergistic stress-adaptive composite sealing paste, comprising: Substrate, cover plate, and sealing layer located between the substrate and the cover plate; The sealing layer is formed by sintering a composite sealing slurry, in which nano-metal alloy particles are uniformly distributed on the surface of a low-melting-point lead-free glass powder matrix and form a micro-anchoring structure. During the cooling process of the sealing layer to the glass transition temperature Tg of the low-melting-point lead-free glass powder, the nano-metal alloy particles are in a plastic state before the glass powder matrix, so as to absorb and cooperate with the volume shrinkage of the negative thermal expansion compensation phase to neutralize the residual thermal stress at the sealing interface.

[0016] This invention utilizes "nano-metal alloy particles (Ts)" The three-phase synergistic mechanism of "Tg), micro-anchoring structure, and negative thermal expansion compensation phase" achieves active and adaptive neutralization of residual thermal stress during the sealing and cooling stage, breaking through the limitations of traditional glass sealing materials that rely solely on passive CTE matching, and significantly reducing reliability issues such as interface cracks and hermeticity failure. Compared with existing technologies, this application has the following outstanding advantages: Utilizing the difference between the alloy softening point and the glass transition temperature, a plastic rheological buffer is introduced during the most critical period of interface stress generation during sealing and cooling. This dynamic stress neutralization capability is more fault-tolerant than traditional static CTE matching and can effectively absorb composite stresses from different substrates. The synergistic effect of temperature gradient-induced plastic rheology and NTE phase volume shrinkage can reduce residual thermal stress at the interface by more than 30% and improve the hermeticity (He leakage rate) of the encapsulation by 1 to 2 orders of magnitude. Attached Figure Description

[0017] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0018] Figure 1 A flowchart illustrating a method for preparing a multiphase synergistic stress-adaptive composite sealing slurry according to an embodiment of the present invention is shown. Figure 2 A cross-sectional schematic diagram of a semiconductor packaging structure implemented using paste according to an embodiment of the present invention is shown.

[0019] The meanings of the numbers in the diagram are: 1-substrate, 2-top cover, 3-sealing layer. Detailed Implementation

[0020] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] This invention provides a multiphase synergistic stress-adaptive composite sealing slurry. In practical application, the slurry, by mass percentage, comprises 60%–75% low-melting-point lead-free glass powder as the main matrix phase, 8%–15% nano-metal alloy particles as the plastic rheological phase, 3%–7% negative thermal expansion compensating phase as the volume-adaptive phase, 10%–15% organic carrier for adjusting slurry viscosity and printing performance, and 0.5%–2% modifying additives for improving the compatibility and dispersion stability of each component. The low-melting-point lead-free glass powder is selected from Bi... O -ZnO-B O System or V O -P O -At least one of the BaO-based glass powders, whose glass transition temperature Tg is typically in the range of 280℃~350℃ (Bi O -ZnO-B O The typical temperature range (Tg) is 320~380℃, and the temperature (V) is... O -P O The typical Tg of BaO-based nanoparticles is 250~320℃. Their surface naturally contains micropores with an average pore size of 50nm~500nm, providing ideal physical sites for the stable embedding of subsequent nanoparticles. The preferred nano-metal alloy particles are silver-tin alloy nanoparticles prepared by co-precipitation or melt atomization, with an average particle size ratio to the glass powder controlled within the range of 1:20~1:100. By selecting a suitable composition of the silver-tin alloy nanoparticles, its softening point Ts is made 20℃~80℃ lower than the Tg of the selected glass powder (e.g., using Bi with a Tg of 320℃). O -ZnO-B O When using glass powder, nano-Ag-Sn alloy particles with a Ts of 240~300℃ can be selected; when using V powder with a Tg of 290℃, the temperature can be adjusted accordingly. O -P O When using BaO-based glass powder, nano-Ag-Sn alloy particles with a temperature gradient (Ts) of 210~270℃ can be selected. This temperature gradient design allows the nano-alloy particles to enter a plastic rheological state before the glass matrix during the sealing and cooling process, effectively absorbing residual thermal stress at the interface like a microscopic "buffer layer." Simultaneously, the nano-metal alloy particles are uniformly distributed on the surface of the glass powder and partially embedded in the micropores during the slurry preparation stage, forming a robust microscopic anchoring structure. This significantly improves the dispersion uniformity of the slurry and the interfacial bonding strength of the sealing layer at high temperatures, avoiding localized stress concentration caused by particle agglomeration or detachment.

[0023] In a specific embodiment, the negative thermal expansion compensation phase is zirconium tungstate (ZrW) with a surface coating of 5nm~20nm silicon dioxide. O The coating layer effectively suppresses the chemical interdiffusion between zirconium tungstate and the glass powder matrix within the sealing temperature range, thus preserving the ZrW particles. O The negative thermal expansion characteristics during the cooling stage create a perfect synergistic effect with the plastic rheology of the nano-alloy particles, achieving active and adaptive neutralization of residual thermal stress at the sealing interface. Modifying agents mainly include silane coupling agents and surfactants. The silane coupling agent can form a chemically bonded hydrophobic monolayer on the surface of the nano-silver-tin alloy particles, significantly enhancing the steric stabilization effect of the particles in the organic carrier, effectively preventing agglomeration, and further ensuring the uniformity of the micro-anchoring structure and the long-term storage stability of the slurry. The organic carrier is mainly composed of terpineol as the main solvent and ethyl cellulose as the binder. Through formulation, its viscosity is controlled within the range of 20~50 Pa·s, giving the slurry good thixotropic properties and screen printing suitability, while also allowing it to completely volatilize and decompose in the 300℃~450℃ range during subsequent sintering, leaving no carbonaceous impurities and thus avoiding adverse effects on the airtightness and reliability of the sealing layer.

[0024] Figure 1 A flowchart illustrating a method for preparing a multiphase synergistic stress-adaptive composite sealing slurry according to an embodiment of the present invention is shown, as follows: Figure 1 As shown, the preparation of the aforementioned multiphase synergistic stress-adaptive composite sealing slurry includes the following steps: S1: Modification treatment of nano-metal alloy particles by surface-affinity modification.

[0025] In a specific embodiment, this step involves adding nano-silver-tin alloy particles to an anhydrous ethanol solution containing 1.0%–2.0% silane coupling agent (such as KH-550 or KH-560), mechanically stirring at 300–500 rpm for 1–2 hours at 40°C–60°C, while simultaneously assisting with ultrasonic dispersion at 40 kHz and 100 W for 40 minutes. After treatment, the particles are filtered, washed 2–3 times with ethanol, and vacuum dried at 80°C for 2 hours to obtain modified nanoparticles with a chemically bonded hydrophobic monolayer on the surface. The purpose of this step is to enhance the compatibility between the nano-metal alloy particles and the organic carrier, effectively prevent agglomeration during subsequent dispersion, and lay the foundation for the stable formation of the micro-anchoring structure.

[0026] S2: Low-melting-point lead-free glass powder, modified nano-metal alloy particles, negative thermal expansion compensation phase and organic carrier are mixed by vacuum planetary stirring.

[0027] In a specific embodiment, step S2 involves mixing low-melting-point lead-free glass powder, modified nano-silver-tin alloy particles, and ZrW coated with silica. O The negative thermal expansion compensation phase and the organic carrier composed of terpineol and ethyl cellulose were added to a vacuum planetary mixer in a specific ratio. The vacuum level was controlled at -0.08 MPa to -0.1 MPa, and the system temperature was maintained at 20℃ to 40℃. The stirring speed was executed in two stages: first, the powders were initially wetted by stirring at a low speed of 300 to 800 rpm for 10 to 20 minutes, and then the speed was increased to 1500 to 2000 rpm for 20 to 40 minutes to achieve full coating. This step ensures that the components are uniformly pre-dispersed under low shear stress, avoiding local agglomeration in the subsequent grinding stage, and providing a stable premixed slurry for three-roll milling.

[0028] S3: The premixed slurry is circulated and ground using a three-roll mill, with the pressure between the rollers controlled at 2MPa-5MPa. The mechanical shear heat generated by the grinding causes local plastic deformation of the nano-metal alloy particles, which are then pressed into the micropores on the surface of the glass powder.

[0029] In a specific embodiment, step S3 involves using a three-roll mill to perform 3-5 rounds of cyclic grinding on the premixed slurry obtained in step S2. The overall grinding temperature is strictly controlled at 25℃-35℃ through water-cooled roller circulation. The inter-roller pressure is controlled in stages: first, 1-2 rounds of low-pressure pre-grinding at 1MPa-2MPa are performed to achieve initial dispersion, and then the pressure is gradually increased to 2MPa-5MPa for 2-3 rounds of high-pressure main grinding (the roller spacing is gradually reduced to 1μm-3μm). During the high-pressure grinding stage, the enormous mechanical shear force combined with local frictional heat causes the nano-metal alloy particles to undergo instantaneous local plastic deformation, stably embedding them into the 50nm-500nm micropores on the surface of the glass powder, forming a strong microscopic anchoring structure. This step is the core process for achieving "ordered anchoring of nanoparticles" in this invention, which can significantly improve the dispersion uniformity of the slurry and the interfacial bonding strength of the sealing layer.

[0030] S4: Monitor the change in conductivity of the slurry in real time during the grinding process. When the conductivity fluctuation rate is less than 2% after three consecutive grinding cycles, stop grinding and perform vacuum degassing.

[0031] In a specific embodiment, step S4 involves real-time online conductivity monitoring during the S3 grinding process. Grinding is stopped when the conductivity fluctuation rate after three consecutive grinding passes is less than 2% and the slurry fineness is ≤10μm. The slurry is then transferred to a vacuum degassing device and degassed for 15-25 minutes under a vacuum of -0.095MPa to -0.1MPa, while simultaneously applying low-frequency ultrasonic vibration at 20-40kHz and 50-100W. This step completely eliminates residual microbubbles in the slurry, preventing them from forming defects during subsequent sintering and ensuring the integrity of the micro-anchoring structure and the density of the sealing layer.

[0032] After optimization, the above preparation process parameters can stably obtain composite sealing slurry with uniform micro-anchoring structure and excellent dispersion, which can ensure the reliability of subsequent encapsulation structure.

[0033] Figure 2 A cross-sectional schematic diagram of a semiconductor packaging structure implemented using paste according to an embodiment of the present invention is shown, as follows: Figure 2 As shown, a semiconductor packaging structure can be fabricated using the above-mentioned slurry, including a substrate 1, a top cover plate 2, and a sealing layer 3 located between the substrate 1 and the top cover plate 2. The sealing layer 3 is formed by sintering the composite sealing slurry from the aforementioned embodiment, wherein nano-metal alloy particles are uniformly distributed on the surface of a low-melting-point lead-free glass powder matrix and form a microscopic anchoring structure. During the cooling of the sealing layer to the glass powder Tg, the nano-metal alloy particles are in a plastic state before the glass matrix, effectively absorbing and coordinating with the volume shrinkage of the negative thermal expansion compensation phase, actively neutralizing the residual thermal stress at the sealing interface, thereby obtaining a packaged device with high hermeticity and high reliability.

[0034] To verify the technical effect of the multiphase synergistic stress self-adaptive composite sealing slurry of the present invention, the following specific examples 1-3 and comparative examples 1-3 were set up. The mass percentage of each component is shown in Table 1 below. All examples were strictly carried out according to the aforementioned preparation method; the inorganic powders were all pretreated before being mixed with the carrier.

[0035] Table 1. Slurry composition of the examples and comparative examples

[0036] In Comparative Example 1, conventional micron-sized pure silver powder was used instead of the nano-metal alloy particles of the present invention. Since the softening point (Ts) of pure silver powder is much higher than its glass transition temperature (Tg), it cannot produce plastic flow during the cooling stage. In Comparative Example 2, zirconium tungstate particles with negative thermal expansion characteristics were not added to the formulation; the missing mass was made up by glass powder to verify the necessity of the multiphase synergistic mechanism. Comparative Example 3 had the same formulation as Example 1, but the preparation process used was a conventional low-pressure (… The 1MPa single-stage mixing and grinding process did not generate instantaneous mechanical shear heat and did not form a micro-embedded anchoring structure at the powder interface.

[0037] The composite sealing pastes prepared in Examples 1-3 and Comparative Examples 1-3 were screen-printed onto the ceramic substrate of a MEMS pressure sensor with a sensitive diaphragm. After alignment with the top cover plate, the substrate was placed in a sintering furnace and sintered at 420°C for 30 minutes, followed by natural cooling in the furnace to form the encapsulation structure. The testing method is as follows: Hermeticity test (helium leak rate): Following GJB 548C-2021 "Test Methods and Procedures for Microelectronic Devices" Method 1014.3 (Sealing Test), a helium mass spectrometer leak detector was used to perform a fine leak test on the packaged device, and the leak rate value was recorded. Industry standards typically require a leak rate ≤10%. ~10 Pa·m³ / s.

[0038] Thermal shock cycling test (TC1000): The packaged device is placed in a high and low temperature shock test chamber and subjected to temperature cycling between -40℃ and 125℃. The high and low temperature transition time is specified. 1 min. After 1000 cycles, non-destructive testing was performed using scanning acoustic microscopy, combined with section metallographic microscopy to observe whether there were microcracks or delamination inside the sealing layer. The sample size for each test group was 50 particles.

[0039] MEMS chip zero-point drift rate: Record the zero-point output voltage of the sensor chip before packaging (bare die state), and the zero-point output voltage after packaging and TC1000 thermal shock testing. Calculate the percentage of the output signal change relative to full scale. This indicator directly reflects the magnitude of the residual mechanical stress exerted by the sealing layer on the internal chip.

[0040] The test results are shown in Table 2 below: Table 2. Test results of slurry encapsulation performance

[0041] By comparing the test data above, it can be seen that: The active stress self-adaptation effect is extremely significant: the zero-point drift rate of Example 1 is only 0.05%, and no cracks were observed after 1000 thermal shocks. In contrast, Comparative Example 1 used micron-sized pure silver powder (which does not possess Ts) Due to its thermal properties (Tg), the TC1000 cannot generate plastic rheology to absorb stress during the cooling phase, resulting in a large amount of rigid thermal stress being directly transferred to the ceramic substrate and MEMS chip. The cracking rate of the TC1000 soars to nearly half (22 / 50), and the zero drift is as high as 0.85% (potentially leading to sensor failure). This fully demonstrates the revolutionary breakthrough of this invention in utilizing temperature gradients to achieve active stress release.

[0042] A multiphase synergistic mechanism is indispensable: In Comparative Example 2, the zirconium tungstate phase with negative thermal expansion characteristics was removed. Although the system still had the plastic deformation buffering effect of the nano-alloy, the lack of volume shrinkage compensation from the negative expansion phase in the low-temperature region led to incomplete stress neutralization, resulting in 0.62% zero-point drift and local cracking. This demonstrates that the bidirectional synergy between metallic plastic deformation and the negative thermal expansion compensation phase is a necessary condition for achieving ultimate stress decoupling.

[0043] The micro-anchoring process plays a crucial role: Comparative Example 3 used the exact same formulation as Example 1, but lacked the high-pressure grinding process. Data showed a significant decrease in its airtightness and fatigue resistance (the number of cracks increased to 8). Due to the lack of a stable micro-mechanical anchoring structure, the nano-alloy particles were prone to phase separation and agglomeration during high-temperature sintering and subsequent thermal cycling, leading to the failure of the stress buffer layer.

[0044] This invention successfully solves the long-standing problem of residual thermal stress at the interface in the semiconductor packaging field by using precise thermodynamic timing design (plastic rheology induced by the Ts-Tg temperature gradient) and micromechanical anchoring (stable interface structure formed by high-pressure shearing and embedding). It achieves a simultaneous and significant improvement in the hermeticity of the sealing layer, thermal cycling reliability, and chip zero-point stability, resulting in technical effects that are significantly superior to existing technologies. It provides a practical solution for high-reliability hermetic packaging of MEMS pressure sensor chips and high-power semiconductor modules.

[0045] The specific embodiments of this application have been described above, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0046] In the description of this application, it should be understood that the terms "upper," "lower," "inner," "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and for simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The simple fact that certain measures are recited in mutually different dependent claims does not indicate that combinations of these measures cannot be used for improvement. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A multiphase synergistic stress-adaptive composite sealing slurry, characterized in that, By mass percentage, it includes the following components: The composition comprises 60%–75% low-melting-point lead-free glass powder, 8%–15% nano-metal alloy particles, 3%–7% negative thermal expansion compensation phase, 10%–15% organic carrier, and 0.5%–2% modifying additives; wherein the softening point (Ts) of the nano-metal alloy particles is lower than the glass transition temperature (Tg) of the low-melting-point lead-free glass powder; the nano-metal alloy particles are uniformly distributed on the surface of the low-melting-point lead-free glass powder and form a micro-anchoring structure; during the sealing and cooling stage, the temperature gradient between Ts and Tg is used to induce the nano-metal alloy particles to undergo plastic rheology before the glass powder matrix, and the volume shrinkage of the negative thermal expansion compensation phase is used to neutralize the residual thermal stress at the sealing interface; the micro-anchoring structure is formed by: using a three-roll mill to circulate and grind the premixed slurry, controlling the inter-roll pressure to be 2MPa–5MPa, and using the mechanical shear heat generated by grinding to induce localized deformation of the nano-metal alloy particles. The low-melting-point lead-free glass powder undergoes plastic deformation and is pressed into the micropores on the surface of the glass powder. The pressure between the rollers is controlled in stages: first, 1-2 rounds of low-pressure pre-grinding are performed at 1MPa~2MPa to achieve initial dispersion, and then the pressure is gradually increased to 2MPa~5MPa for 2-3 rounds of high-pressure main grinding. The surface of the low-melting-point lead-free glass powder has micropores with an average pore size of 50nm~500nm, and the nano-metal alloy particles are partially pressed into the micropores to form interface anchoring. The low-melting-point lead-free glass powder is selected from at least one of BiO-ZnO-BO system or VO-PO-BaO system glass powders, and its glass transition temperature Tg is in the range of 280℃~350℃. The negative thermal expansion compensation phase is zirconium tungstate particles with a silica coating layer on the surface. The thickness of the silica coating layer is 5nm~20nm, which is used to suppress the chemical interdiffusion between the zirconium tungstate and the glass powder matrix in the sealing temperature range.

2. The multiphase synergistic stress-adaptive composite sealing slurry according to claim 1, characterized in that, The softening point Ts of the nano-metal alloy particles and the glass transition temperature Tg of the low melting point lead-free glass powder satisfy the following condition: 20℃≤Tg-Ts≤80℃.

3. The multiphase synergistic stress-adaptive composite sealing slurry according to claim 1, characterized in that, The average particle size ratio of the nano-metal alloy particles to the low-melting-point lead-free glass powder is taken in the range of 1:20 to 1:

100.

4. The multiphase synergistic stress-adaptive composite sealing slurry according to claim 1, characterized in that, The modifying agent includes a silane coupling agent and a surfactant; the silane coupling agent forms a chemically bonded hydrophobic monolayer on the surface of the nano-metal alloy particles.

5. A method for preparing a multiphase synergistic stress-adaptive composite sealing slurry as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: The nano-metal alloy particles are modified by surface-affinity modification; S2: The low-melting-point lead-free glass powder, the modified nano-metal alloy particles, the negative thermal expansion compensation phase, and the organic carrier are mixed by vacuum planetary stirring. S3: The premixed slurry is circulated and ground using a three-roll mill, and the pressure between the rollers is controlled at 2MPa-5MPa. The mechanical shear heat generated by grinding causes the nano-metal alloy particles to undergo local plastic deformation and is pressed into the micropores on the surface of the glass powder. S4: Monitor the change in conductivity of the slurry in real time during the grinding process. When the conductivity fluctuation rate is less than 2% after three consecutive grinding cycles, stop grinding and perform vacuum degassing.

6. The preparation method according to claim 5, characterized in that, The circulating grinding described in S3 adopts a staged pressure control method: first, 1-2 rounds of low-pressure pre-grinding are carried out at 1MPa-2MPa to achieve initial dispersion, and then the pressure is gradually increased to 2MPa-5MPa for 2-3 rounds of high-pressure main grinding.

7. A semiconductor packaging structure implemented using the multiphase synergistic stress-adaptive composite sealing paste according to any one of claims 1-4, characterized in that, include: Substrate, cover plate, and sealing layer located between the substrate and the cover plate; The sealing layer is formed by sintering the composite sealing slurry, wherein the nano-metal alloy particles are uniformly distributed on the surface of the low-melting-point lead-free glass powder matrix and form a micro-anchoring structure. During the cooling process of the sealing layer to the glass transition temperature Tg of the low-melting-point lead-free glass powder, the nano-metal alloy particles are in a plastic state before the glass powder matrix, so as to absorb and cooperate with the volume shrinkage of the negative thermal expansion compensation phase to neutralize the residual thermal stress at the sealing interface.

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