Electrophoresis glass passivation method for improving electrical property of semiconductor device and semiconductor device

Abstract

The invention discloses an electrophoretic glass passivation method for improving the electrical property of a semiconductor device and the semiconductor device, and relates to the technical field of semiconductor devices.The method comprises the steps that a semiconductor chip to be passivated is obtained, electrophoretic glass liquid is prepared, the semiconductor chip is placed in the electrophoretic glass liquid, electrophoretic deposition conditions are applied, and the semiconductor chip is passivated; depositing the glass powder on the surface of the semiconductor chip to form a glass wet film; carrying out sintering annealing treatment on the glass wet film, introducing a mixed atmosphere of oxygen and nitrogen into a sintering furnace in the sintering annealing treatment, and carrying out heating, heat preservation and cooling according to a preset multi-stage temperature curve so as to melt and densify the glass wet film and form a glass passivation layer; and obtaining the semiconductor device on which the glass passivation layer is formed. Through the technical scheme of the invention, the risks of glass cavities, cracks and stripping are reduced, the surface insulation and voltage endurance capability of the device is improved, the electric leakage and failure rate are reduced, and the electrical consistency and long-term reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and in particular to an electrophoretic glass passivation method for improving the electrical properties of semiconductor devices, and a semiconductor device. Background Technology

[0002] Semiconductor devices are susceptible to moisture, ion contamination, and concentrated surface electric fields during long-term service, leading to reliability issues such as increased leakage current, decreased breakdown voltage, and drift in electrical parameters. To improve the surface insulation and interface stability of devices, existing technologies typically form a glass passivation layer on the chip surface. Among these, electrophoretic deposition glass passivation is widely used in the surface passivation process of power devices and related chips due to its advantages such as high film formation efficiency, good coverage, and adaptability to complex surfaces.

[0003] Existing electrophoretic glass passivation processes generally include: preparing an electrophoretic glass melt (glass powder and solvent system, combined with organic components for dispersion and film formation); depositing glass powder particles under an applied electric field to form a wet glass film; and then melting, flowing, and densifying the wet film through sintering and annealing to finally obtain a glass passivation layer. However, in actual production, this type of process still has several key challenges: First, if the solid content of the glass powder, the amount of binder and dispersant, and the matching of the solvent system in the electrophoretic glass melt are not properly controlled, it can easily lead to the sedimentation or agglomeration of the glass powder, resulting in uneven deposition thickness, local pinholes, and insufficient edge coverage, affecting the consistency of the subsequent passivation layer. Second, the solvent and organic components in the wet film need to be fully volatilized and decomposed during the sintering and annealing stage; if the temperature rises too quickly or a single high-temperature isothermal process is used, the volatiles and decomposition gases are not easily released in time, easily forming bubbles, pores, and interface voids during the glass melting process, resulting in insufficient density of the passivation layer. Third, unstable atmosphere (oxygen-nitrogen ratio, flow rate stability, etc.) and pressure control within the sintering furnace may lead to incomplete decomposition of organic matter, residual defects, or uncontrollable interfacial reactions, thereby weakening the bonding reliability between the glass layer and the substrate. Fourth, if effective stress release control is lacking during the cooling stage, microcracks or localized delamination are easily generated due to differences in thermal expansion coefficients, further deteriorating insulation performance and long-term stability.

[0004] Therefore, there is an urgent need for a process method for electrophoretic glass passivation that can reduce the risk of structural defects such as pores / voids during sintering without sacrificing process compatibility, improve the density of the glass passivation layer and the stability of the interface bonding, thereby achieving repeatable improvement in the electrical properties and reliability of semiconductor devices. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an electrophoretic glass passivation method and semiconductor device for improving the electrical properties of semiconductor devices. By limiting the solid content of glass powder and the ratio of binder and dispersant in the electrophoretic glass melt, stable dispersion of glass powder particles and improved electrophoretic deposition efficiency are achieved, resulting in a uniform and continuous wet glass film on the surface of the semiconductor chip, reducing pinholes and uneven thickness. Furthermore, by heating, holding, and cooling according to a multi-stage temperature curve in a mixed atmosphere of oxygen and nitrogen and limiting the heating rate, the wet film is fully debonded, melted and densified, and stress is released, reducing the risk of glass voids, cracks, and peeling, forming a dense glass passivation layer. This improves the surface insulation and withstand voltage of the device, reduces leakage current and failure rate, and improves electrical consistency and long-term reliability.

[0006] To achieve the above objectives, the present invention provides an electrophoretic glass passivation method for improving the electrical properties of semiconductor devices, comprising: A semiconductor chip to be passivated is obtained and an electrophoretic glass melt is prepared. The electrophoretic glass melt includes glass powder, solvent, binder and dispersant. The mass fraction of the glass powder in the electrophoretic glass melt is 15wt% to 25wt%, the amount of binder is 1% to 3% of the mass of the glass powder, and the amount of dispersant is 0.5% to 1.5% of the mass of the glass powder. The semiconductor chip is placed in the electrophoretic glass melt and electrophoretic deposition conditions are applied to deposit the glass powder on the surface of the semiconductor chip to form a wet glass film. The glass wet film is subjected to sintering annealing treatment. The sintering annealing treatment is carried out in a sintering furnace with a mixed atmosphere of oxygen and nitrogen. The oxygen flow rate in the mixed atmosphere is 15 L / min and the nitrogen flow rate is 3 L / min. The temperature is raised, held and cooled according to a preset multi-stage temperature curve. The multi-stage temperature curve includes: raising the temperature to 200℃ and holding for 30 min, raising the temperature to 600℃ and holding for 20-30 min, raising the temperature to 720-750℃ and holding for 10-20 min, and lowering the temperature to 560℃ and holding for 20 min and then continuing to cool to below 200℃. The heating rate is not greater than 8℃ / min, so as to melt and densify the glass wet film and form a glass passivation layer. A semiconductor device having the glass passivation layer formed thereon is obtained.

[0007] In the above technical solution, preferably, the dispersant is a polyacrylate dispersant or a polycarboxylate ammonium salt dispersant, and the binder is ethyl cellulose or polyvinyl butyral; The electrophoretic glass melt also includes a charge regulator, which is a quaternary ammonium salt compound, and the amount of the charge regulator is 0.1% to 0.3% of the mass of the glass powder.

[0008] In the above technical solution, preferably, the solvent includes a main solvent and a co-solvent, the main solvent includes isopropanol and propylene glycol methyl ether acetate, the co-solvent includes ethanol and lanthanum nitrate solution, and the ratio of the total volume of the main solvent to the total volume of the co-solvent is 15:1.

[0009] In the above technical solution, preferably, the glass powder is a low melting point glass powder, the particle size of the glass powder is 1μm to 5μm, the softening temperature is 450 to 750℃, and the sintering temperature is 500 to 800℃.

[0010] In the above technical solution, preferably, in the multi-stage temperature curve, before heating to 720-750℃ and holding at that temperature, the temperature is first raised to 650℃, and then the temperature continues to rise from 650℃ to 720-750℃ before entering the holding stage.

[0011] In the above technical solution, preferably, the glass powder is lead-based glass powder or lead-free glass powder, wherein: The lead-based glass powder comprises, by mass percentage, 20%–30% SiO2, 15%–25% B2O3, 40%–55% PbO, and 2%–5% Al2O3; The lead-free glass powder comprises, by mass percentage, 25%–35% SiO2, 20%–30% B2O3, 15%–25% ZnO, and 10%–15% Bi2O3, and further comprises TiO2.

[0012] In the above technical solution, preferably, before preparing the electrophoretic glass melt, the glass powder is vacuum dried at 200°C for 4 hours, and the dried glass powder is sieved through a 300-mesh sieve to remove agglomerated particles.

[0013] In the above technical solution, preferably, the specific process for preparing the electrophoretic glass melt includes: The solvent is mixed with the binder, the dispersant and the charge regulator, and then ultrasonically dispersed for 10 minutes. The obtained electrophoretic glass melt was degassed under vacuum at -0.08 MPa for 20–30 min and then filtered through a 5 μm pore size filter membrane.

[0014] In the above technical solution, preferably, during the sintering annealing process, a slightly positive pressure of +50Pa to +100Pa is maintained in the sintering furnace, and the flow rates of oxygen and nitrogen are controlled in a closed loop. After the heat treatment at 720–750°C is completed, the semiconductor chip is removed from the heating zone of the sintering furnace at a speed of no more than 5 cm / min to achieve controlled cooling.

[0015] The present invention also proposes a semiconductor device, including a semiconductor chip and a glass passivation layer formed on the surface of the semiconductor chip, wherein the glass passivation layer is formed by an electrophoretic glass passivation method for improving the electrical properties of a semiconductor device disclosed in any of the above technical solutions.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By limiting the solid content of glass powder in the electrophoretic glass melt to 15wt% to 25wt%, and controlling the amount of binder to 1% to 3% of the glass powder mass and the amount of dispersant to 0.5% to 1.5% of the glass powder mass, the glass powder particles are kept stably dispersed and depositable in the solvent system, which improves the film uniformity and adhesion stability of the electrophoretic deposition process, and reduces wet film particle agglomeration, pinholes and uneven thickness from the source.

[0017] (2) By placing the semiconductor chip in the electrophoretic glass liquid and applying electrophoretic deposition conditions, the glass powder is deposited in a direction on the chip surface to form a glass wet film, thus establishing a controllable passivation layer precursor film structure. This reduces the coating dead corners and edge accumulation problems that are easy to occur in traditional coating processes, and provides a consistent film layer basis for subsequent sintering densification.

[0018] (3) By introducing a mixed atmosphere of oxygen at 15L / min and nitrogen at 3L / min into the sintering furnace, and sintering and annealing according to a multi-stage temperature curve (holding at 200℃, holding at 600℃, holding at 720~750℃, holding at 560℃ and then cooling) with a heating rate not greater than 8℃ / min, the wet film completes degumming, degassing, melting and flow and densification, while achieving controlled cooling and stress release, reducing the risk of glass voids, cracks and peeling, and forming a dense and continuous glass passivation layer.

[0019] (4) The formed glass passivation layer passivates and isolates the surface defects and interfaces of the device, improves the surface insulation and withstand voltage, reduces leakage and failure rate, and enhances the electrical consistency and long-term working reliability of the device. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of an electrophoretic glass passivation method for improving the electrical properties of semiconductor devices, as disclosed in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings: like Figure 1 As shown, to address the problems of insufficient density of the passivation layer on the surface of semiconductor chips and the electrical fluctuations of devices caused by voids after sintering, this invention provides an electrophoretic glass passivation method for improving the electrical properties of semiconductor devices, comprising: A semiconductor chip to be passivated is obtained, and an electrophoretic glass melt is prepared. The electrophoretic glass melt includes glass powder, solvent, binder, and dispersant. The mass fraction of glass powder in the electrophoretic glass melt is 15wt% to 25wt%, the amount of binder is 1% to 3% of the mass of glass powder, and the amount of dispersant is 0.5% to 1.5% of the mass of glass powder. If the solid content of the glass powder is too high, it will easily become viscous; if it is too low, the film-forming efficiency will be low. Therefore, by controlling the ratio of the solid content of the glass powder to the amount of binder / dispersant components, the electrophoretic glass melt can balance suspension stability and deposition film-forming ability, reduce the risk of wet film defects caused by glass powder sedimentation and agglomeration, and ensure that the wet film has the basic adhesion and continuity to withstand subsequent heat treatment.

[0023] A semiconductor chip is placed in an electrophoretic glass melt and electrophoretic deposition conditions are applied. Under the action of an external electric field, glass powder migrates and deposits directionally on the chip surface, forming a wet glass film covering the chip surface. This step allows the glass powder to build an initial glass layer on the chip surface in a controllable manner, providing a continuous material basis for subsequent sintering and densification, thereby reducing voids and pinholes caused by local weak areas.

[0024] The glass wet film is subjected to sintering annealing treatment. The sintering annealing treatment is carried out in a sintering furnace with a mixed atmosphere of oxygen and nitrogen. The oxygen flow rate in the mixed atmosphere is 15L / min and the nitrogen flow rate is 3L / min. The temperature is raised, held and cooled according to a preset multi-stage temperature curve. The multi-stage temperature curve includes: raising the temperature to 200℃ and holding for 30min, raising the temperature to 600℃ and holding for 20-30min, raising the temperature to 720-750℃ and holding for 10-20min, and cooling to 560℃ and holding for 20min and then continuing to cool to below 200℃. The heating rate is no more than 8℃ / min.

[0025] The segmented setting of the multi-stage temperature profile is used to achieve the coordinated process of binder removal, gas release, glass powder softening and flow, and final densification, reducing the probability of voids and pinholes in the glass layer and improving the quality of interfacial bonding. Through the coordinated control of atmosphere and multi-stage thermal history, the glass wet film gradually completes the release of volatile components, softening and wetting of the glass phase, melting and flow, and densification, while suppressing thermal stress concentration and interfacial defect propagation during the cooling stage, thereby forming a denser glass passivation layer and improving the electrical consistency of the device.

[0026] Specifically, in the above four temperature control processes: The first stage, heating to 200℃ and holding for 30 minutes, is the preheating and degumming stage, which is to remove volatiles. This stage can slowly discharge solvent / binder and prevent boiling and gas generation. The second stage involves heating to 600℃ and holding for 20-30 minutes, which is the expansion and heat preservation stage. This stage is for interface wetting, which softens the glass, allows it to initially wet the silicon wafer, and removes small air bubbles. The third stage involves heating to 720–750℃ and holding for 10–20 minutes. This is the melting and densification stage, which is for the expulsion of air bubbles. This stage can fully melt the glass, causing the air bubbles to rise and be expelled, and forming a strong bond at the interface. The fourth stage involves cooling to 560℃ and holding for 20 minutes, followed by further cooling to below 200℃. This is a slow cooling and stress relief stage designed to prevent debonding. This stage helps to match thermal expansion, eliminate internal stress, and prevent voids in the interface gaps.

[0027] After the aforementioned deposition and sintering annealing, a glass passivation layer is formed on the chip surface, resulting in a semiconductor device with a glass passivation layer. This serves as a surface passivation and insulation protection structure, reducing electrical fluctuations and reliability risks caused by defects. This glass passivation layer is used in semiconductor device surface insulation and passivation scenarios, forming a dense isolation layer to reduce ion contamination intrusion and suppress surface leakage channels, thereby reducing reverse leakage current levels and improving device electrical consistency and reliability.

[0028] In this embodiment, by limiting the solid content of glass powder and the ratio of binder and dispersant in the electrophoretic glass melt, stable dispersion of glass powder particles and improved electrophoretic deposition efficiency are achieved, resulting in a uniform and continuous wet glass film on the semiconductor chip surface. This reduces pinholes and uneven thickness. Furthermore, by heating, holding, and cooling according to a multi-stage temperature curve under a mixed atmosphere of oxygen and nitrogen and limiting the heating rate, the wet film is fully debonded, melted and densified, and stress is released, reducing the risk of glass voids, cracks, and peeling, and forming a dense glass passivation layer. This improves the surface insulation and withstand voltage of the device, reduces leakage current and failure rate, and improves electrical consistency and long-term reliability.

[0029] In the above embodiments, preferably, the functional component types and electrical stability of the electrophoretic glass melt are further defined. The dispersant is a polyacrylate dispersant or a polycarboxylate ammonium salt dispersant, with low volatility to reduce high-temperature decomposition and gas generation. This is used to suppress glass powder particle agglomeration and improve the dispersion stability of the system, thereby reducing film thickness fluctuations and localized deposition defects during the electrophoretic deposition process. The binder is ethyl cellulose (EC) or polyvinyl butyral (PVB), which completely decomposes without residue during sintering. This is used to improve the adhesion stability of the glass wet film to the chip surface and reduce the probability of cracking and peeling of the wet film during handling and heating stages.

[0030] The electrophoretic glass melt also includes a charge regulator, which is a quaternary ammonium salt compound. The amount of charge regulator is 0.1% to 0.3% of the glass powder mass. By regulating the charge state of the particles through the charge regulator, stable positive / negative charges are imparted to the glass powder particles, ensuring the efficiency of electrophoretic deposition, improving the repeatability of electrophoretic deposition, and enabling the formation of a more stable and uniform coating structure of the glass wet film.

[0031] In one specific embodiment, the quaternary ammonium salt compound selected is hexadecyltrimethylammonium bromide to improve the stability of particle zeta potential and inhibit sedimentation and agglomeration, thereby reducing pinhole and streak defects in the deposited film.

[0032] In the above embodiments, preferably, the solvent includes a main solvent and a co-solvent. The main solvent includes isopropanol (IPA) and propylene glycol methyl ether acetate (PGMEA), and the co-solvent includes ethanol and lanthanum nitrate solution. The ratio of the total volume of the main solvent to the total volume of the co-solvent is 15:1.

[0033] The main solvents are isopropanol and propylene glycol methyl ether acetate, which have good solubility and moderate evaporation rate, balancing evaporation rate and film uniformity, and avoiding pinholes in the film. Ethanol is used to adjust viscosity, and lanthanum nitrate solution is used to improve the dispersibility of glass powder and reduce the tendency of particle agglomeration.

[0034] In one specific embodiment, the solvent system is adjusted to bring the viscosity of the electrophoretic glass melt into the range of 50–150 mPa·s, so as to balance deposition efficiency and wet film surface smoothness, and reduce the risk of pinholes and local accumulation.

[0035] In this embodiment, the repeatability of electrophoretic deposition is improved by regulating the charge state of the particles through a charge regulator, resulting in a more stable and uniform covering structure of the glass wet film.

[0036] In the above embodiments, preferably, the glass powder is a low-melting-point glass powder. The particle size of the glass powder is detected using a laser particle size analyzer. Excessive coarseness can easily lead to film formation defects, while excessive fineness can easily cause agglomeration. The preferred particle size of the glass powder is 1μm to 5μm to avoid agglomeration leading to localized enrichment of volatiles. The softening temperature of the low-melting-point glass powder is 450–750℃, and the sintering temperature is 500–800℃ to match the semiconductor metallization process.

[0037] In this embodiment, by matching and controlling the particle size with the softening / sintering temperature window, the glass powder can achieve relatively stable migration and accumulation behavior during the electrophoretic deposition stage, and can also achieve effective softening, melting flow and densification in the sintering annealing temperature range, thereby reducing the impact of voids and structural defects on the electrical properties of the device.

[0038] In the above embodiments, preferably, in the multi-stage temperature curve, before heating to 720-750°C and holding at that temperature, the temperature is first raised to 650°C, and then the temperature is further raised from 650°C to 720-750°C before entering the holding stage.

[0039] In this embodiment, by introducing an intermediate heating section of 650°C, the glass wet film achieves a smoother thermal transition before entering the high-temperature heat preservation stage, completes more thorough debinding and release of volatile components before entering the high-temperature melting and densification stage, reduces glass layer bubbling and voids caused by the sudden release of gas in the high-temperature stage, and improves the consistency of subsequent melting and densification, thereby improving glass layer void defects and electrical fluctuations.

[0040] By adjusting the existing "constant temperature of 752℃" to "segmented heating from 650℃ followed by high-temperature heat preservation", the release of gas inside the glass layer is made more gradual, reducing the formation of voids. In a specific embodiment, the void ratio of the glass layer can be controlled to ≤0.5%, the interface bonding rate to ≥99%, and the electrical yield to ≥98%.

[0041] In the above embodiments, preferably, the glass powder is Japanese GP370 glass powder (core functional phase) material, including lead-based glass powder or lead-free glass powder, preferably borosilicate lead-based or lead-free borosilicate aluminum-based low-melting-point glass powder, wherein: Lead-based glass powder comprises, by mass percentage, 20%–30% SiO2, 15%–25% B2O3, 40%–55% PbO, and 2%–5% Al2O3; The lead-free glass powder comprises, by mass percentage, 25%–35% SiO2, 20%–30% B2O3, 15%–25% ZnO and 10%–15% Bi2O3, and further comprises TiO2, which is used to optimize sintering fluidity and promote densification.

[0042] Specifically, excessive PbO will exacerbate bubbling; the mass percentage of Bi2O3 should be controlled to ≤15%. The coefficient of thermal expansion of the sintered glass powder needs to be similar to that of the silicon wafer (~2.6×10⁻⁶). -6 The thermal expansion coefficient is adjusted by adjusting the content of Al2O3 and ZnO to match the silicon wafer / metal substrate (temperature range ℃) or the metal substrate. Otherwise, sintering cracks will occur.

[0043] In this embodiment, by defining the key component windows within lead-based and lead-free systems, the glass powder achieves more controllable softening flow and densification behavior while meeting the requirements for low melting point and sintering window. This reduces the impact of post-sintering structural defects on the insulation stability of the glass passivation layer and the consistency of device electrical properties. The formulation system achieves both low melting point and insulation while also considering thermal matching with the chip substrate / metallization layer.

[0044] In the above embodiments, preferably, before preparing the electrophoretic glass melt, the glass powder is vacuum dried at 200°C for 4 hours, and the dried glass powder is sieved through a 300-mesh sieve to remove agglomerated particles.

[0045] In this embodiment, vacuum drying reduces the volatilization sources carried by the glass powder, and sieving removes agglomerated particles, which reduces local accumulation and wet film defects during the electrophoretic deposition stage. It also lowers the risk of voids caused by volatilization and agglomeration during the subsequent sintering and annealing stage, thereby improving the density and consistency of the glass passivation layer. After powder pretreatment, the fluctuations in the electrophoretic deposition film thickness converge, improving the continuity and density of the glass layer and reducing leakage current dispersion in subsequent electrical tests.

[0046] In the above embodiments, when air bubbles are present in the deposited wet glass film, pinholes and pores are formed after sintering, leading to local insulation failure. Therefore, vacuum degassing and micron-level filtration reduce the probability of introducing air bubbles and coarse particles, thereby improving the continuity and electrical consistency of the glass layer. Preferably, the specific process for preparing the electrophoretic glass melt includes: The solvent, binder, dispersant, and charge modifier are mixed and ultrasonically dispersed for 10 minutes. The obtained electrophoretic glass melt was degassed under vacuum at -0.08 MPa for 20–30 min and then filtered through a 5 μm pore size filter membrane.

[0047] During the process, after ultrasonic dispersion, the dried glass powder is added to the solvent-additive mixture according to the specified ratio and stirred for 15 minutes using a magnetic stirrer (150–200 rpm) to form a preliminary suspension. Then, the mixture is vibrated for 15 minutes using an ultrasonic tank with a power of 0.5–0.8 MPa to break up any undissolved large glass powder particles. The glass particles in the molten glass are then adsorbed by a lanthanum nitrate solution. After the suspension is allowed to stand for 5 minutes, the large glass powder particles are filtered and precipitated to remove undispersed large particles and impurities. During filtration, the molten glass must be protected to prevent the introduction of air bubbles and pinholes in the electrophoresis membrane.

[0048] In this embodiment, ultrasonic dispersion improves the uniformity of components and the stability of particle dispersion, vacuum degassing reduces bubble entrainment, and fine filtration removes large particles and impurities, thereby improving the uniformity and repeatability of electrophoretic deposition film and reducing the probability of wet film pinholes and subsequent sintering voids.

[0049] In the above embodiments, preferably, during the sintering annealing process, a slightly positive pressure of +50Pa to +100Pa is maintained in the sintering furnace, and the flow rates of oxygen and nitrogen are controlled in a closed loop to stabilize the oxygen partial pressure and atmosphere flow rate in the furnace, thereby improving the process consistency of the degumming and densification stages. After holding at 720–750℃, the semiconductor chip is removed from the heating zone of the sintering furnace at a speed not exceeding 5 cm / min to achieve controlled cooling and reduce thermal stress concentration.

[0050] Specifically, the atmosphere uses a high-purity gas mixture of nitrogen and oxygen, with an oxygen content of 5%–10%. This avoids excessive oxidation of silicon caused by pure oxygen, while pure nitrogen easily leads to glass reduction bubbles. During the melting stage, the oxygen content can be briefly increased to 15% to promote the formation of SiO2 at the interface and improve wettability. During the cooling stage, the oxygen content is switched back to ≥95% to prevent surface oxidation.

[0051] In one specific implementation, closed-loop control is used to control oxygen and nitrogen flow fluctuations within ±5% and furnace temperature fluctuations within ≤3°C, so as to reduce inter-batch void ratio and interface bonding fluctuations; controlled boat unloading is used to reduce thermal shock cracking of the glass layer and improve long-term reliability.

[0052] In this embodiment, the atmosphere and exhaust environment inside the furnace are stabilized by micro-positive pressure and flow closed-loop control. Combined with controlled removal after heat preservation, the cooling rhythm is controllable, which reduces the defect fluctuations caused by thermal shock and atmosphere fluctuations, and improves the batch consistency of glass layer densification output and the electrical stability of the device.

[0053] The key performance indicators of the electrophoretic glass passivation method for improving the electrical properties of semiconductor devices disclosed in the above embodiments include: ① Viscosity: Controlled at 25℃ between 50 and 150 mPa•s (rotational viscometer), which can be adjusted by adding or removing cosolvent; ② Zeta potential: Absolute value > 30mV (potential analyzer) to ensure particle dispersion stability; ③ Sedimentation stability: After standing for 24 hours, the height of the clear liquid in the upper layer is less than 5%; otherwise, dispersant needs to be added.

[0054] The present invention also proposes a semiconductor device, including a semiconductor chip and a glass passivation layer formed on the surface of the semiconductor chip, wherein the glass passivation layer is formed by an electrophoretic glass passivation method for improving the electrical properties of a semiconductor device disclosed in any of the above embodiments.

[0055] Since the glass passivation layer originates from a glass wet film formed by electrophoretic deposition and then densified by sintering and annealing, it can form a continuous coverage structure on the chip surface, improving the surface passivation and insulation protection effect, reducing reverse leakage current and improving the electrical performance retention ability under humid heat / ion contamination environment. Furthermore, densification reduces the risk of local breakdown caused by voids and pinholes, reduces the impact of defects on device electrical performance, and enhances consistency and reliability.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for electrophoretic glass passivation to improve the electrical properties of semiconductor devices, characterized in that, include: A semiconductor chip to be passivated is obtained and an electrophoretic glass melt is prepared. The electrophoretic glass melt includes glass powder, solvent, binder and dispersant. The mass fraction of the glass powder in the electrophoretic glass melt is 15wt% to 25wt%, the amount of binder is 1% to 3% of the mass of the glass powder, and the amount of dispersant is 0.5% to 1.5% of the mass of the glass powder. The semiconductor chip is placed in the electrophoretic glass melt and electrophoretic deposition conditions are applied to deposit the glass powder on the surface of the semiconductor chip to form a wet glass film. The glass wet film is subjected to sintering annealing treatment. The sintering annealing treatment is carried out in a sintering furnace with a mixed atmosphere of oxygen and nitrogen. The oxygen flow rate in the mixed atmosphere is 15 L / min and the nitrogen flow rate is 3 L / min. The temperature is raised, held and cooled according to a preset multi-stage temperature curve. The multi-stage temperature curve includes: raising the temperature to 200℃ and holding for 30 min, raising the temperature to 600℃ and holding for 20-30 min, raising the temperature to 720-750℃ and holding for 10-20 min, and lowering the temperature to 560℃ and holding for 20 min and then continuing to cool to below 200℃. The heating rate is not greater than 8℃ / min, so as to melt and densify the glass wet film and form a glass passivation layer. A semiconductor device having the glass passivation layer formed thereon is obtained.

2. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 1, characterized in that, The dispersant is a polyacrylate dispersant or a polycarboxylate ammonium salt dispersant, and the binder is ethyl cellulose or polyvinyl butyral; The electrophoretic glass melt also includes a charge regulator, which is a quaternary ammonium salt compound, and the amount of the charge regulator is 0.1% to 0.3% of the mass of the glass powder.

3. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 1, characterized in that, The solvent includes a main solvent and a co-solvent. The main solvent includes isopropanol and propylene glycol methyl ether acetate, and the co-solvent includes ethanol and lanthanum nitrate solution. The ratio of the total volume of the main solvent to the total volume of the co-solvent is 15:

1.

4. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 1, characterized in that, The glass powder is a low melting point glass powder with a particle size of 1μm to 5μm, a softening temperature of 450 to 750℃, and a sintering temperature of 500 to 800℃.

5. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 1, characterized in that, In the multi-stage temperature curve, before heating to 720-750℃ and holding at that temperature, the temperature is first raised to 650℃, and then continues to rise from 650℃ to 720-750℃ before entering the holding stage.

6. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 4, characterized in that, The glass powder is lead-based glass powder or lead-free glass powder, wherein: The lead-based glass powder comprises, by mass percentage, 20%–30% SiO2, 15%–25% B2O3, 40%–55% PbO, and 2%–5% Al2O3; The lead-free glass powder comprises, by mass percentage, 25%–35% SiO2, 20%–30% B2O3, 15%–25% ZnO, and 10%–15% Bi2O3, and further comprises TiO2.

7. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 4, characterized in that, Before preparing the electrophoretic glass melt, the glass powder is vacuum dried at 200°C for 4 hours, and the dried glass powder is sieved through a 300-mesh sieve to remove agglomerated particles.

8. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 2, characterized in that, The specific process for preparing the electrophoretic glass melt includes: The solvent is mixed with the binder, the dispersant and the charge regulator, and then ultrasonically dispersed for 10 minutes. The obtained electrophoretic glass melt was degassed under vacuum at -0.08 MPa for 20–30 min and then filtered through a 5 μm pore size filter membrane.

9. The electrophoretic glass passivation method for improving the electrical properties of semiconductor devices according to claim 1, characterized in that, During the sintering annealing process, a slight positive pressure of +50Pa to +100Pa is maintained inside the sintering furnace, and the flow rates of oxygen and nitrogen are controlled in a closed loop. After the heat treatment at 720–750°C is completed, the semiconductor chip is removed from the heating zone of the sintering furnace at a speed of no more than 5 cm / min to achieve controlled cooling.

10. A semiconductor device, characterized in that, It includes a semiconductor chip and a glass passivation layer formed on the surface of the semiconductor chip, the glass passivation layer being formed by the electrophoretic glass passivation method for improving the electrical properties of a semiconductor device according to any one of claims 1 to 9.

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