A GPP rectifier diode chip with a gradient-doped composite glass passivation layer

Abstract

The application discloses a GPP rectifier diode chip with a gradient-doped composite glass passivation layer, and belongs to the technical field of semiconductor devices. The GPP rectifier diode chip with the gradient-doped composite glass passivation layer comprises a base substrate, a gradient diffusion zone and a composite glass passivation layer. The application solves the problems of poor interface charge stability, large leakage current and insufficient long-term reliability of a conventional single-layer or multi-layer glass passivation layer of an existing GPP rectifier diode chip. The first gradient distribution of the resistivity of the base substrate along the thickness direction, the second gradient distribution of the impurity concentration of the gradient diffusion zone surface along the transverse direction and the composite glass passivation layer with periodic fluctuation of carbon content inhibit the concentration effect of the junction edge electric field, improve the interface matching property and compactness of the passivation layer and the semiconductor surface, thereby reducing the leakage current, and improving the voltage resistance and long-term working stability of the device.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, specifically to a GPP rectifier diode chip with a gradient-doped composite glass passivation layer. Background Technology

[0002] Glass passivation process (GPP) is one of the key technologies in rectifier diode chip manufacturing. It protects the PN junction by forming a glass passivation layer on the chip surface, preventing corrosion from external impurities and moisture, thereby improving the reliability and stability of the device. Traditional GPP rectifier diodes typically use a single-structure glass layer (such as lead silicate glass or borosilicate glass) as the passivation layer. However, under high temperature, high humidity, and strong electric field environments, they still suffer from poor interface charge stability, insufficient withstand voltage, and high leakage current.

[0003] With the increasing demands on diode performance, especially in applications with stringent reliability requirements such as power supplies, automotive electronics, and communication equipment, traditional GPP diode chips are gradually revealing the following technical problems:

[0004] 1. When the substrate resistivity is uniformly distributed, there is an irreconcilable contradiction between the on-state voltage drop and the reverse breakdown voltage of the device. The uniformly doped substrate makes the expansion behavior of the space charge region under reverse bias fixed, making it difficult to reduce the forward on-resistance while maintaining a high breakdown voltage.

[0005] 2. In the PN junction region formed by traditional diffusion process, the impurity concentration is relatively uniform in both the lateral and longitudinal directions, resulting in a significant junction edge curvature effect and severe electric field concentration, which reduces the actual breakdown voltage and surge resistance of the device.

[0006] 3. Conventional single-layer or simple multi-layer glass passivation layers have insufficient thermal matching and interfacial bonding with semiconductor surfaces, and the passivation layer itself has limited density. After long-term operation, interface trap charge accumulation is likely to occur, leading to increased leakage current and breakdown voltage drift in the device.

[0007] Therefore, it does not meet the existing requirements, so we propose a GPP rectifier diode chip with a gradient doped composite glass passivation layer. Summary of the Invention

[0008] The purpose of this invention is to provide a GPP rectifier diode chip with a gradient-doped composite glass passivation layer. Through a first gradient distribution of substrate resistivity along the thickness direction, the contradiction between on-state voltage drop and reverse breakdown voltage can be alleviated. Through a second gradient distribution of surface impurity concentration in the gradient diffusion region, the electric field concentration effect at the junction edge can be suppressed. Furthermore, through the periodically fluctuating carbon content of the intermediate silicon-oxygen-hydrogen layer and the amorphous silicon carbide layer in the composite glass passivation layer, interface matching and density can be improved. This significantly reduces leakage current, improves breakdown voltage, and enhances long-term reliability under high temperature and high humidity environments, thus solving the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a GPP rectifier diode chip with a gradient-doped composite glass passivation layer, comprising a substrate, a gradient diffusion region, and a composite glass passivation layer;

[0010] The resistivity of the substrate exhibits a first gradient distribution along the thickness direction, and the carrier concentration exhibits a monotonically decreasing distribution or a step-decreasing distribution from the first main surface to the second main surface of the substrate.

[0011] The gradient diffusion region is formed in the first main surface of the substrate, the junction depth of the gradient diffusion region is 5μm to 30μm, and the surface impurity concentration of the gradient diffusion region exhibits a second gradient distribution along the lateral direction;

[0012] The composite glass passivation layer covers the gradient diffusion region and part of the first main surface of the substrate. The composite glass passivation layer consists of the following layers in sequence from the first main surface of the substrate outward: a first amorphous silicon carbide layer, an intermediate silicon-oxygen-carbon-hydrogen layer, and a second amorphous silicon carbide layer.

[0013] The carbon content of the intermediate silicon-oxygen-hydrogen layer fluctuates periodically along the thickness direction, with the number of periods ranging from 3 to 10.

[0014] Furthermore, the resistivity of the substrate is distributed in a first gradient by at least two epitaxial growth processes combined with ion implantation. An epitaxial layer is provided on the first main surface of the substrate. The epitaxial layer is formed by at least two epitaxial growth processes. The doping source flux used in two adjacent epitaxial growth processes is set to decrease progressively, and the initial doping concentration of the later epitaxial growth process is not higher than the doping concentration at the end of the previous epitaxial growth process.

[0015] Wherein, an interface region with a continuous transition in carrier concentration is formed between the epitaxial layer and the substrate body, the thickness of the interface region is 0.5μm to 3μm, and the carrier concentration distribution within the interface region satisfies:

[0016]

[0017] In the formula, The depth is the distance from the first main surface; The concentration at the first principal surface; The characteristic attenuation length; The substrate bulk concentration is denoted as .

[0018] Furthermore, an ion implantation region is provided in the first main surface of the substrate, the implanted impurity type of the ion implantation region is the same as the conductivity type of the substrate, and the peak concentration of the ion implantation region is located at a depth of 0.2 μm to 1.5 μm below the first main surface of the substrate;

[0019] The ion implantation region and the gradient diffusion region are provided with a lateral spacing, which is not less than 0.3 times the junction depth of the gradient diffusion region.

[0020] Furthermore, the surface impurity concentration in the gradient diffusion region exhibits a second gradient distribution in a concentric ring shape along the lateral direction, and is successively divided into a central flat region, a gradually changing transition region, and an edge enhancement region from the center to the periphery.

[0021] Among them, the surface impurity concentration in the central flat region is uniform and the lowest, the surface impurity concentration in the edge enhancement region is the highest, the surface impurity concentration in the transitional gradient region increases continuously in the radial direction, and the width of the transitional gradient region accounts for 15% to 35% of the total radius of the gradient diffusion region.

[0022] Furthermore, the surface impurity concentration of the edge enhancement region is 1.5 to 4 times that of the central flat region, and the lateral distance between the outer boundary of the edge enhancement region and the inner boundary of the composite glass passivation layer on the first main surface is 2 μm to 8 μm. The impurity concentration in this region gradually reaches its peak from the inner boundary outward, which is used to adjust the curvature of the edge of the space charge region under reverse bias.

[0023] Furthermore, the intermediate silicon-oxygen-carbon-hydrogen layer is composed of multiple periodic sublayer pairs stacked together. Each sublayer pair includes a carbon-rich silicon-oxygen-carbon-hydrogen sublayer and a carbon-poor silicon-oxygen-carbon-hydrogen sublayer. The carbon-rich sublayer has a carbon atom percentage of 25% to 45%, and the carbon-poor sublayer has a carbon atom percentage of 5% to 15%. Within one period, the carbon content transitions continuously from the carbon-rich silicon-oxygen-carbon-hydrogen sublayer to the carbon-poor silicon-oxygen-carbon-hydrogen sublayer in a gradient.

[0024] Furthermore, in the periodic fluctuation, the average carbon content of two adjacent cycles decreases monotonically in the direction away from the first main surface, and the total decrease does not exceed 20% of the average carbon content of the first cycle. In addition, the carbon-depleted sublayer of the last cycle is in direct contact with the second amorphous silicon carbide layer, and the two form a transition layer with a carbon content of at least 30% and a thickness of 10nm to 50nm at the interface.

[0025] Furthermore, a silicon oxynitride interface control layer with a thickness of 5nm to 20nm is provided between the first amorphous silicon carbide layer and the intermediate silicon-oxygen-hydrogen layer, and between the intermediate silicon-oxygen-hydrogen layer and the second amorphous silicon carbide layer. The refractive index of the silicon oxynitride interface control layer is between the refractive indices of the two adjacent layers, and the ratio of nitrogen content to oxygen content gradually changes along the thickness direction.

[0026] Furthermore, the outer boundary of the gradient diffusion region is formed into a three-dimensional gradually varying junction profile through multiple selective diffusion superpositions. The junction depth of the gradient diffusion region gradually decreases from the center to the edge in the vertical direction, and the junction depth at the edge is 40% to 75% of the junction depth at the center. Moreover, the isoconcentration lines of the lateral concentration gradient and the isobaths of the three-dimensional gradually varying junction profile are locally orthogonal in the edge region.

[0027] Furthermore, the composite glass passivation layer has a local thickening region at a position corresponding to the junction edge of the gradient diffusion region. The total thickness of the local thickening region is 15% to 35% greater than the thickness of the surrounding region. The thickening is mainly achieved by the intermediate silicon-oxygen-carbon-hydrogen layer having 1 to 3 more cycles at this position than other regions. The radial width of the local thickening region is 5 μm to 15 μm.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. This invention solves the contradiction between the on-state voltage drop and the reverse breakdown voltage in traditional uniformly doped substrates by making the substrate resistivity distributed in a first gradient along the thickness direction. This gradient structure makes the high concentration side reduce the on-state resistance when forward biased, and widen the space charge region and improve the breakdown voltage when reverse biased, thereby achieving synergistic optimization of the two.

[0030] 2. This invention suppresses the curvature effect and electric field concentration at the edge of the PN junction by distributing the surface impurity concentration in the gradient diffusion region in a second gradient direction along the lateral direction, thereby improving the actual breakdown voltage and surge protection capability of the device and overcoming the problem of premature breakdown caused by the traditional single impurity distribution.

[0031] 3. The present invention adopts a composite glass passivation layer structure, especially the carbon content of the middle silicon-oxygen-carbon-hydrogen layer fluctuates periodically along the thickness direction. Combined with the upper and lower amorphous silicon carbide layers, it can significantly improve the thermal matching and interfacial bonding between the passivation layer and the semiconductor surface. The periodic fluctuation structure can effectively block the accumulation path of interface trap charges, thereby reducing leakage current and breakdown voltage drift under high temperature and high humidity environments and improving the long-term reliability of the device. Attached Figure Description

[0032] Figure 1This is a schematic diagram of the structure of the GPP rectifier diode chip with gradient doped composite glass passivation layer of the present invention;

[0033] Figure 2 This is a structural block diagram of the GPP rectifier diode chip with gradient doped composite glass passivation layer according to the present invention.

[0034] In the figure: 1. Substrate; 2. Gradient diffusion region; 3. Composite glass passivation layer. Detailed Implementation

[0035] 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, and 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.

[0036] To address the technical challenges of balancing forward voltage drop and reverse breakdown voltage in existing GPP rectifier diode chips, the low breakdown voltage due to concentrated electric field at the PN junction edge, and the poor interface charge stability, high leakage current, and insufficient long-term reliability of conventional single-layer or multi-layer glass passivation layers, please refer to [link to relevant documentation]. Figures 1-2 This embodiment provides the following technical solution:

[0037] A GPP rectifier diode chip with a gradient-doped composite glass passivation layer 3 includes a substrate 1, a gradient diffusion region 2, and a composite glass passivation layer 3.

[0038] The resistivity of the substrate 1 is distributed in a first gradient along the thickness direction, and the carrier concentration is monotonically decreasing or stepwise decreasing from the first main surface to the second main surface of the substrate 1. Specifically, the first main surface is the upper surface (top surface) of the substrate 1, and the second main surface is the lower surface (bottom surface) of the substrate 1.

[0039] The gradient diffusion region 2 is formed in the first main surface of the substrate 1, the junction depth of the gradient diffusion region 2 is 5μm to 30μm, and the surface impurity concentration of the gradient diffusion region 2 exhibits a second gradient distribution along the lateral direction.

[0040] The composite glass passivation layer 3 covers the gradient diffusion region 2 and part of the first main surface of the substrate 1. The composite glass passivation layer 3 consists of the following layers in sequence from the first main surface of the substrate 1 outward: a first amorphous silicon carbide layer, an intermediate silicon-oxygen-carbon-hydrogen layer, and a second amorphous silicon carbide layer.

[0041] The carbon content of the intermediate silicon-oxygen-hydrogen layer fluctuates periodically along the thickness direction, with the number of periods ranging from 3 to 10.

[0042] Specifically, the substrate 1 serves as the base of the chip, and the first main surface of the substrate 1 is embedded with a gradient diffusion region 2. The composite glass passivation layer 3 is located on the top surface of the chip and covers the first main surface, while also covering the gradient diffusion region 2 and the surrounding surface of the substrate 1.

[0043] In a specific example, the resistivity gradient distribution principle of the substrate 1 is as follows: when the carrier concentration decreases monotonically or in a stepwise manner along the thickness direction from the first main surface to the second main surface, the substrate resistance can be effectively reduced and a high breakdown voltage can be maintained. In some embodiments, the substrate resistivity gradient variation range can be 0.01 Ω·cm to 0.1 Ω·cm. The junction depth and surface impurity concentration gradient distribution principle of the gradient diffusion region 2 is as follows: when the junction depth is 5 μm to 30 μm and the surface impurity concentration exhibits a second gradient distribution along the lateral direction, the electric field distribution can be optimized and edge breakdown can be suppressed. In some embodiments, the junction depth is preferably 10 μm to 20 μm.

[0044] The technical effects of the above-mentioned technical solution are as follows: The first gradient distribution of resistivity along the thickness direction of the substrate 1 allows the space charge region to preferentially expand towards the low-concentration side under reverse bias, significantly reducing the forward voltage drop while maintaining a high reverse breakdown voltage, thus alleviating the contradiction between on-resistance and withstand voltage capability; the second gradient distribution of impurity concentration along the lateral direction on the surface of the gradient diffusion region 2 effectively suppresses the curvature effect at the PN junction edge, making the electric field distribution more uniform, improving the actual breakdown voltage and surge resistance, while reducing the leakage current at the junction edge; the composite glass passivation layer 3 adopts... The stacked structure of the first amorphous silicon carbide layer, the intermediate silicon-oxygen-hydrogen layer, and the second amorphous silicon carbide layer, wherein the periodic fluctuation of the carbon content of the intermediate silicon-oxygen-hydrogen layer can form a multi-periodic stress buffer and defect trapping interface in the thickness direction, can significantly improve the compactness and anti-ion migration ability of the passivation layer, improve the thermal matching and interfacial bonding with the semiconductor surface, thereby effectively suppressing the accumulation of interface trap charges under long-term operation, thus significantly reducing leakage current drift and breakdown voltage degradation under high temperature and high humidity environments, and improving the long-term reliability and stability of the device in harsh application scenarios such as power supply and automotive electronics.

[0045] The resistivity of the substrate 1 is distributed in a first gradient by at least two epitaxial growth processes combined with ion implantation. An epitaxial layer is provided on the first main surface of the substrate 1. The epitaxial layer is formed by at least two epitaxial growth processes. The doping source flux used in two adjacent epitaxial growth processes is set to decrease, and the initial doping concentration of the later epitaxial growth process is not higher than the doping concentration at the end of the previous epitaxial growth process.

[0046] Wherein, an interface region with a continuous transition in carrier concentration is formed between the epitaxial layer and the substrate 1, the thickness of the interface region is 0.5 μm to 3 μm, and the carrier concentration distribution within the interface region satisfies:

[0047]

[0048] In the formula, The depth is the distance from the first main surface; The concentration at the first principal surface; The characteristic attenuation length; The substrate bulk concentration is denoted as .

[0049] In a specific example, the principle for forming a first gradient distribution of resistivity in the substrate 1 is as follows: it is achieved through at least two epitaxial growth processes combined with ion implantation. The doping source flux used in adjacent epitaxial growth processes decreases progressively, and the initial doping concentration of the subsequent epitaxial growth process is no higher than the doping concentration at the end of the previous epitaxial growth process, thereby obtaining a smooth carrier concentration gradient distribution. In some embodiments, the number of epitaxial growth processes can be 2 to 5. The thickness of the interface region is 0.5 μm to 3 μm, and the carrier concentration distribution within the interface region satisfies an exponential decay form. In some embodiments, the characteristic decay length L can be 0.2 μm to 1 μm.

[0050] The technical effects of the above solution are as follows: A resistivity gradient distribution is formed through at least two epitaxial growth processes combined with ion implantation. A decreasing doping source flux setting results in a higher carrier concentration at the first main surface and a lower concentration in the substrate bulk, thus achieving low on-resistance under forward bias and allowing the space charge region to fully expand towards the low-concentration side under reverse bias, significantly improving the breakdown voltage. A continuous transition interface region with a thickness of 0.5μm to 3μm and satisfying an exponential decay law is formed between the epitaxial layer and the substrate bulk, avoiding electric field spikes and defect enrichment problems at traditional abrupt junction interfaces and reducing interface leakage current. The characteristic decay length L can precisely control the slope of the concentration gradient, allowing the depletion layer width to change smoothly under different reverse voltages, thereby suppressing electric field concentration. Simultaneously, the multiple epitaxial growth combined with ion implantation process has strong compatibility, good concentration distribution repeatability, and improved yield, effectively solving the technical contradiction between on-state voltage drop and breakdown voltage capability in uniformly doped substrates.

[0051] An ion implantation region is provided in the first main surface of the substrate 1. The implanted impurity type in the ion implantation region is the same as the conductivity type of the substrate 1. The peak concentration of the ion implantation region is located at a depth of 0.2 μm to 1.5 μm below the first main surface of the substrate 1.

[0052] The ion implantation region and the gradient diffusion region 2 are provided with a lateral spacing, which is not less than 0.3 times the junction depth of the gradient diffusion region 2.

[0053] In a specific example, the principle for setting the ion implantation region is as follows: by implanting impurities of the same conductivity type as the substrate 1, and forming a peak concentration at a depth of 0.2 μm to 1.5 μm below the first main surface, the surface electric field distribution can be optimized and the surface leakage current reduced. In some embodiments, the ion implantation dose can be 1 × 10⁻⁶. 12 cm -2 ~5×10 13 cm -2 A lateral spacing is provided between the ion implantation region and the gradient diffusion region 2. The principle for determining this spacing is that when the lateral spacing is not less than 0.3 times the junction depth of the gradient diffusion region 2, the electric field concentration effect between the implantation region and the diffusion region can be effectively avoided, thereby improving the breakdown voltage stability of the chip. In some embodiments, the lateral spacing can be 2μm to 10μm.

[0054] The technical effects of the above solution are as follows: An ion implantation region with the same conductivity as the substrate is set in the first main surface, and its peak concentration is located 0.2μm to 1.5μm below the surface. Without significantly increasing the forward conduction resistance, the surface electric field distribution can be effectively modulated, thereby suppressing the premature expansion of the depletion layer to the surface under reverse bias, thus reducing the surface leakage current. A lateral spacing of not less than 0.3 times the junction depth is maintained between the ion implantation region and the gradient diffusion region 2, thereby avoiding direct coupling between the implantation region and the diffusion region, preventing the formation of parasitic channels or premature breakdown. At the same time, this spacing region can serve as a buffer zone to disperse the electric field concentration at the junction edge, thereby improving the actual breakdown voltage and surge resistance of the device, and improving the high-temperature reverse bias stability.

[0055] The surface impurity concentration in gradient diffusion region 2 is distributed in a second gradient pattern along the transverse direction in a concentric ring shape, and is divided into a central flat region, a transitional gently changing region, and an edge enhancement region from the center to the periphery.

[0056] Among them, the surface impurity concentration in the central flat region is uniform and the lowest, the surface impurity concentration in the edge enhancement region is the highest, the surface impurity concentration in the transitional gradient region increases continuously in the radial direction, and the width of the transitional gradient region accounts for 15% to 35% of the total radius of the gradient diffusion region 2;

[0057] The surface impurity concentration of the edge enhancement region is 1.5 to 4 times that of the central flat region, and the lateral distance between the outer boundary of the edge enhancement region and the inner boundary of the composite glass passivation layer 3 on the first main surface is 2 μm to 8 μm. The impurity concentration in this region gradually reaches its peak from the inner boundary to the outside, which is used to adjust the curvature of the edge of the space charge region under reverse bias.

[0058] The intermediate silicon-oxygen-carbon-hydrogen layer is composed of multiple periodic sublayer pairs stacked together. Each sublayer pair includes a carbon-rich silicon-oxygen-carbon-hydrogen sublayer and a carbon-poor silicon-oxygen-carbon-hydrogen sublayer. The carbon-rich sublayer has a carbon atom percentage of 25% to 45%, and the carbon-poor sublayer has a carbon atom percentage of 5% to 15%. Within one period, the carbon content transitions continuously from the carbon-rich silicon-oxygen-carbon-hydrogen sublayer to the carbon-poor silicon-oxygen-carbon-hydrogen sublayer, rather than an abrupt interface.

[0059] In one specific example, the principle of the concentric ring-shaped second gradient distribution of surface impurity concentration in the gradient diffusion region 2 is as follows: from the center outwards, it is divided into a central flat region, a gradually changing transition region, and an edge enhancement region. The curvature of the space charge region edge is adjusted by the higher surface impurity concentration in the edge enhancement region (1.5 to 4 times that of the central flat region), thereby reducing the peak surface electric field. In some embodiments, the width of the gradually changing transition region can account for 20% to 30% of the total radius of the diffusion region. The lateral distance between the outer boundary of the edge enhancement region and the inner boundary of the composite glass passivation layer 3 is 2 μm to 8 μm to ensure that the passivation layer effectively covers the high electric field region. The intermediate silicon-oxygen-carbon-hydrogen layer is composed of multiple periodic sublayer pairs stacked together. Each sublayer pair includes a carbon-rich silicon-oxygen-carbon-hydrogen sublayer (25% to 45% carbon atom percentage) and a carbon-poor silicon-oxygen-carbon-hydrogen sublayer (5% to 15% carbon atom percentage). The carbon content within a period shows a continuous gradient transition rather than an abrupt interface to reduce interface stress and improve the compactness of the passivation layer. In some embodiments, the number of periods can be 3 to 10.

[0060] The technical effects of the above solution are as follows: the surface impurity concentration of the gradient diffusion region 2 exhibits a concentric annular gradient distribution consisting of a central flat region, a gradually changing transition region, and an edge enhancement region. The concentration in the edge enhancement region is 1.5 to 4 times that of the central flat region, and it maintains a lateral distance of 2 μm to 8 μm from the inner boundary of the composite glass passivation layer 3. This significantly suppresses the edge curvature effect of the PN junction, allowing the edge of the space charge region to smoothly expand outward under reverse bias, thus avoiding premature breakdown caused by electric field concentration and improving the actual breakdown voltage and surge withstand capability. The width of the gradually changing transition region accounts for 15% of the total radius. The concentration ranges from 25% to 35%, ensuring a continuous distribution and avoiding electric field spikes caused by abrupt changes. Meanwhile, the intermediate silicon-oxygen-carbon-hydrogen layer uses alternating stacking of carbon-rich sublayers (25%–45% carbon atoms) and carbon-poor sublayers (5%–15% carbon atoms), with a continuous gradient transition of carbon content within each cycle rather than an abrupt interface. This significantly reduces interlayer stress and interface defect density, forming a multidimensional bandgap modulation structure. This effectively blocks carrier injection and ion migration, improves the insulation performance and moisture erosion resistance of the passivation layer, and thus maintains low leakage current and high breakdown stability during long-term operation.

[0061] During the periodic fluctuations, the average carbon content of two adjacent cycles decreases monotonically in the direction away from the first principal surface, and the total decrease does not exceed 20% of the average carbon content of the first cycle. Furthermore, the carbon-depleted sublayer of the last cycle is in direct contact with the second amorphous silicon carbide layer, and the two form a transition layer with a carbon content of at least 30% and a thickness of 10nm to 50nm at the interface.

[0062] The technical effects of the above solution are as follows: the stress inside the passivation layer is released gradually along the thickness direction, which can avoid cumulative cracking; the decreasing carbon content combined with the high carbon transition layer can optimize the interface matching with the second amorphous silicon carbide layer, thereby enhancing the bonding force and density, further suppressing the accumulation of interface trap charges, and reducing leakage current drift.

[0063] A silicon oxynitride interface control layer with a thickness of 5 nm to 20 nm is provided between the first amorphous silicon carbide layer and the intermediate silicon-oxygen-hydrogen layer, and between the intermediate silicon-oxygen-hydrogen layer and the second amorphous silicon carbide layer. The refractive index of the silicon oxynitride interface control layer is between the refractive indices of the two adjacent layers, and the ratio of nitrogen content to oxygen content gradually changes along the thickness direction.

[0064] In one specific example, a silicon oxynitride interface control layer with a thickness of 5 nm to 20 nm is disposed between the first amorphous silicon carbide layer and the intermediate silicon-oxygen-hydrogen layer, and between the intermediate silicon-oxygen-hydrogen layer and the second amorphous silicon carbide layer. The refractive index of this control layer is between that of the two adjacent layers, and the ratio of nitrogen content to oxygen content gradually changes along the thickness direction, thereby reducing interlayer interface reflection, alleviating stress mismatch, and improving interlayer bonding. In some embodiments, the ratio of nitrogen content to oxygen content in the silicon oxynitride interface control layer can gradually change from 3:1 near the silicon carbide layer to 1:3 near the silicon-oxygen-hydrogen layer.

[0065] The technical effects of the above solution are as follows: by setting a silicon oxynitride interface control layer with a thickness of 5nm to 20nm, whose refractive index is between that of adjacent layers and whose nitrogen-oxygen ratio gradually changes along the thickness, the reflection and interface state defects caused by the abrupt change in optical and dielectric constants between layers can be effectively eliminated; the gradient interface reduces stress concentration and trapped charge density, enhances interlayer bonding and thermal matching, and suppresses interface delamination and charge accumulation under high temperature and high humidity conditions, thereby reducing leakage current drift and thus improving the long-term reliability and breakdown resistance of the passivation layer.

[0066] The outer boundary of the gradient diffusion region 2 forms a three-dimensional gradually changing junction profile through multiple selective diffusion superpositions. The junction depth of the gradient diffusion region 2 gradually decreases from the center to the edge in the vertical direction, and the junction depth at the edge is 40% to 75% of the junction depth at the center. Furthermore, the isoconcentration lines of the lateral concentration gradient and the isodepth lines of the three-dimensional gradually changing junction profile are locally orthogonal in the edge region.

[0067] In one specific example, a three-dimensional gradually varying junction profile is formed through multiple selective diffusion stackings. This causes the junction depth in the vertical direction to gradually decrease from the center to the edge, with the junction depth at the edge being 40%–75% of the depth at the center, thereby effectively reducing the edge electric field concentration effect. The isoconcentration lines of the lateral concentration gradient and the isobaths of the three-dimensional gradually varying junction profile exhibit a locally orthogonal distribution in the edge region, achieving a smooth transition at the boundary of the space charge region and suppressing edge breakdown. In some embodiments, the multiple selective diffusions can be 2–4 times, with the window size decreasing sequentially for each diffusion.

[0068] The technical effects of the above-mentioned technical solution are as follows: by forming a three-dimensional gradually varying junction profile through multiple selective diffusion superpositions, the edge junction depth is 40% to 75% of that at the center, and the transverse isoconcentration lines and longitudinal isodepth lines are locally orthogonal in the edge region, which can effectively reduce the curvature effect and electric field spikes at the edge of the PN junction, make the space charge region expand more uniformly, significantly improve the actual breakdown voltage and surge resistance, and reduce the edge leakage current, thereby improving the reliability and yield of the device.

[0069] The composite glass passivation layer 3 also has a local thickening region at the position corresponding to the junction edge of the gradient diffusion region 2. The total thickness of the local thickening region is 15% to 35% greater than the thickness of the surrounding region. The thickening is mainly achieved by the intermediate silicon-oxygen-carbon-hydrogen layer having 1 to 3 more cycles at this position than other regions. The radial width of the local thickening region is 5 μm to 15 μm.

[0070] In one specific example, a local thickening region is provided above the junction edge corresponding to the gradient diffusion region 2. Its total thickness is 15%–35% greater than the surrounding region, and the thickening is mainly achieved by the intermediate silicon-oxygen-carbon-hydrogen layer having 1–3 more cycles at this location than in other regions. The radial width of this local thickening region is 5 μm–15 μm, used to enhance the electric field shielding effect and ion blocking capability above the junction edge, reducing the influence of external charges on the electric field distribution at the junction edge. In some embodiments, the radial width of the local thickening region is preferably 8 μm–12 μm, and the thickening margin is preferably 20%–30%.

[0071] The technical effects of the above solution are as follows: a local thickening region is set above the junction edge, increasing the total thickness by 15% to 35%, which is achieved by adding 1 to 3 cycles to the intermediate silicon-oxygen-carbon-hydrogen layer, with a radial width of 5μm to 15μm. This specifically enhances the passivation protection capability of the area with the most concentrated electric field, thereby effectively suppressing edge breakdown and leakage current, while avoiding excessive stress caused by overall thickening, thus improving the withstand voltage reliability and long-term stability of the device.

[0072] Working principle: The resistivity of the substrate 1 exhibits a gradient distribution, allowing the space charge region to fully expand towards the low-concentration side under reverse bias, thus increasing the breakdown voltage. Conversely, during forward conduction, the high-concentration side reduces resistance, alleviating the voltage drop issue. The gradient diffusion region 2 features a lateral gradient distribution of impurity concentration on its surface, forming a gradually changing doping profile at the junction edge, weakening electric field concentration and curvature effects. In the composite glass passivation layer 3, the amorphous silicon carbide layer provides high density to block ion migration, while the intermediate silicon-oxygen-carbon-hydrogen layer introduces a multi-layer stress release and defect trapping interface through periodic fluctuations in carbon content, enhancing interface bonding and charge stability. This invention improves reverse breakdown voltage and surge resistance, thereby reducing forward conduction voltage drop and leakage current, suppressing electrical parameter drift under high temperature and humidity environments, and ultimately improving the long-term reliability of the chip.

[0073] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3), characterized in that, It includes a substrate (1), a gradient diffusion region (2), and a composite glass passivation layer (3); The resistivity of the substrate (1) is distributed in a first gradient along the thickness direction, and the carrier concentration is distributed in a monotonically decreasing or stepwise decreasing distribution from the first main surface to the second main surface of the substrate (1). The gradient diffusion region (2) is formed in the first main surface of the substrate (1), the junction depth of the gradient diffusion region (2) is 5μm to 30μm, and the surface impurity concentration of the gradient diffusion region (2) is distributed in a second gradient along the lateral direction. The composite glass passivation layer (3) covers the gradient diffusion region (2) and part of the first main surface of the substrate (1). The composite glass passivation layer (3) consists of the following layers from the first main surface of the substrate (1) outward: a first amorphous silicon carbide layer, an intermediate silicon-oxygen-hydrogen layer, and a second amorphous silicon carbide layer. The carbon content of the intermediate silicon-oxygen-hydrogen layer fluctuates periodically along the thickness direction, with the number of periods ranging from 3 to 10.

2. The GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, The resistivity of the substrate (1) is distributed in a first gradient and is formed by at least two epitaxial growth processes combined with ion implantation. An epitaxial layer is provided on the first main surface of the substrate (1). The epitaxial layer is formed by at least two epitaxial growth processes. The doping source flux used in two adjacent epitaxial growth processes is set to decrease, and the initial doping concentration of the later epitaxial growth process is not higher than the doping concentration at the end of the previous epitaxial growth process. Wherein, an interface region with a continuous transition of carrier concentration is formed between the epitaxial layer and the substrate (1) body, the thickness of the interface region is 0.5μm to 3μm, and the carrier concentration distribution in the interface region satisfies: ； In the formula, The depth is the distance from the first main surface; The concentration at the first principal surface; The characteristic attenuation length; The substrate bulk concentration is denoted as .

3. The GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, An ion implantation region is provided in the first main surface of the substrate (1). The implanted impurity type in the ion implantation region is the same as the conductivity type of the substrate (1). The peak concentration of the ion implantation region is located at a depth of 0.2 μm to 1.5 μm below the first main surface of the substrate (1). The ion implantation region and the gradient diffusion region (2) are provided with a lateral spacing, which is not less than 0.3 times the junction depth of the gradient diffusion region (2).

4. The GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, The surface impurity concentration of the gradient diffusion region (2) is distributed in a second gradient in a concentric ring along the transverse direction, and is divided into a central flat region, a transitional region and an edge enhancement region from the center to the periphery. Among them, the surface impurity concentration in the central flat region is uniform and the lowest, the surface impurity concentration in the edge enhancement region is the highest, the surface impurity concentration in the transitional gradient region increases continuously in the radial direction, and the width of the transitional gradient region accounts for 15% to 35% of the total radius of the gradient diffusion region (2).

5. A GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 4, characterized in that, The surface impurity concentration of the edge enhancement region is 1.5 to 4 times that of the central flat region, and the lateral distance between the outer boundary of the edge enhancement region and the inner boundary of the composite glass passivation layer (3) on the first main surface is 2 μm to 8 μm. The impurity concentration in this region gradually reaches its peak from the inner boundary outward, which is used to adjust the curvature of the edge of the space charge region under reverse bias.

6. The GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, The intermediate silicon-oxygen-carbon-hydrogen layer is composed of multiple periodic sublayer pairs stacked together. Each sublayer pair includes a carbon-rich silicon-oxygen-carbon-hydrogen sublayer and a carbon-poor silicon-oxygen-carbon-hydrogen sublayer. The carbon-rich sublayer has a carbon atom percentage of 25% to 45%, and the carbon-poor sublayer has a carbon atom percentage of 5% to 15%. Within one period, the carbon content transitions continuously from the carbon-rich silicon-oxygen-carbon-hydrogen sublayer to the carbon-poor silicon-oxygen-carbon-hydrogen sublayer in a gradient.

7. A GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, In the periodic fluctuation, the average carbon content of two adjacent cycles decreases monotonically in the direction away from the first main surface, and the total decrease does not exceed 20% of the average carbon content of the first cycle. The carbon-depleted sublayer of the last cycle is in direct contact with the second amorphous silicon carbide layer, and the two form a transition layer with a carbon content of at least 30% and a thickness of 10nm to 50nm at the interface.

8. A GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, Between the first amorphous silicon carbide layer and the intermediate silicon-oxygen-hydrogen layer, and between the intermediate silicon-oxygen-hydrogen layer and the second amorphous silicon carbide layer, a silicon oxynitride interface control layer with a thickness of 5nm to 20nm is provided. The refractive index of the silicon oxynitride interface control layer is between the refractive indices of the two adjacent layers, and the ratio of nitrogen content to oxygen content gradually changes along the thickness direction.

9. A GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, The outer boundary of the gradient diffusion region (2) is formed by multiple selective diffusion superpositions to form a three-dimensional gradually changing knot profile. The knot depth of the gradient diffusion region (2) in the vertical direction gradually becomes shallower from the center to the edge. The knot depth at the edge is 40% to 75% of the knot depth at the center. Moreover, the isoconcentration lines of the lateral concentration gradient and the isodepth lines of the three-dimensional gradually changing knot profile are locally orthogonal in the edge region.

10. A GPP rectifier diode chip with a gradient-doped composite glass passivation layer (3) according to claim 1, characterized in that, The composite glass passivation layer (3) also has a local thickening region at the position above the junction edge corresponding to the gradient diffusion region (2). The total thickness of the local thickening region is 15% to 35% greater than the thickness of the surrounding region. The thickening is mainly achieved by the intermediate silicon-oxygen-carbon-hydrogen layer having 1 to 3 more cycles at this position than other regions. The radial width of the local thickening region is 5 μm to 15 μm.

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