Methods and systems for reducing reverse leakage current of diodes

Abstract

This invention provides a method and system for reducing reverse leakage current in diodes. By designing the electrode ends as a multi-level stepped structure, the physical path of potential change is extended, resulting in a smoother electric field gradient distribution. Simultaneously, an electrically isolated annular auxiliary electrode is set around the main electrode, and an intermediate potential is applied to introduce a transverse electric field component. This component is superimposed on the longitudinal electric field to reconstruct the edge electric field distribution. This method optimizes the electric field distribution from two dimensions: electrode structure and potential configuration, without changing the semiconductor material or doping process. The stepped structure allows the geometric contour of the electrode ends to gradually transition, avoiding abrupt potential changes and significantly reducing local electric field peaks. The transverse electric field generated by the annular auxiliary electrode guides the electric field lines to diffuse outward, reducing the density concentrated in the semiconductor interior. The combination of these two factors reduces the overall combined electric field intensity in the edge region, effectively suppressing the point of maximum field strength.

Description

Technical Field

[0001] This invention belongs to the field of diode technology, specifically relating to a method and system for reducing reverse leakage current in diodes. Background Technology

[0002] In semiconductor devices, the reverse leakage current of a diode is one of the key factors affecting its performance and reliability. When a diode is in reverse bias, the electric field distribution is uneven due to abrupt changes in geometry at the edge of the depletion region of the PN junction, which easily leads to electric field concentration. This localized high electric field significantly enhances the collisional ionization effect of charge carriers, resulting in an increase in reverse leakage current. In severe cases, it can trigger avalanche breakdown, reducing the device's operational stability and withstand voltage capability.

[0003] In existing technologies, a uniform planar electrode structure is typically used, with the electrode edges aligned with the semiconductor boundary. Under high reverse voltages, this structure concentrates potential changes in a narrow region at the electrode tip, creating a strong electric field gradient and exacerbating the problem of edge field concentration. Although some solutions attempt to alleviate field concentration through passivation layers or field plate structures, their controllability is limited, making it difficult to effectively disperse the potential change path at the electrode edge, and the effect of suppressing leakage current is not significant.

[0004] Therefore, how to reduce the edge electric field strength of the diode under reverse bias and reduce the reverse leakage current has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for reducing reverse leakage current in diodes, which effectively disperses the electric field concentration at the electrode edge, making the maximum electric field strength lower than the material breakdown threshold, thereby significantly suppressing the generation of reverse leakage current and improving the withstand voltage performance and operational reliability of the device, thus solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for reducing reverse leakage current of a diode, comprising the following steps:

[0007] Define the geometric dimensions of the P-region and N-region of the diode, and define the lateral length and PN junction position to provide a spatial reference for subsequent potential distribution analysis;

[0008] Based on the aforementioned geometric dimensions and the net doping concentrations of the P and N regions, the built-in potential is calculated, and a reverse bias voltage is applied to form a total applied potential difference, which serves as the input for the electrode boundary conditions.

[0009] Based on the total applied potential difference, a grounded metal electrode A is covered on the top of the P region, and a metal electrode B with a reverse bias voltage is covered on the bottom of the N region, thus constructing a rectangular electrode structure with the electrode edge aligned with the semiconductor edge.

[0010] Based on the rectangular electrode structure, the Poisson equation is solved under the depletion layer approximation to calculate the potential distribution, derive the electric field intensity, and identify the high field intensity concentration points in the electrode edge region.

[0011] For the high field strength concentration point, the end of the original rectangular electrode is modified into a multi-stage stepped structure. The total extension length is determined by the number of steps and the width of a single stage, so as to extend the potential change path and reduce the local electric field gradient.

[0012] A ring-shaped auxiliary electrode is set around the stepped main electrode. The inner boundary of the auxiliary electrode is reserved with a gap between the edge of the main electrode and the edge of the main electrode. The width of the ring structure is fixed. The electrode is electrically isolated from the main electrode. The potential is set to an intermediate potential between the potential of the main electrode and the ground potential, which is used to regulate the distribution of the edge electric field.

[0013] Based on the electric field modulation effect introduced by the ring auxiliary electrode, by adjusting the number of steps, the width of a single stage, the distance between the ring electrode and the main electrode, and the ratio of the intermediate potential to the reverse bias voltage, the electric field strength in the edge region can be made lower than the field strength threshold corresponding to material breakdown.

[0014] Preferably, modifying the end of the original rectangular electrode into a multi-level stepped structure includes:

[0015] Based on the total potential change that needs to be controlled at the identified high field strength concentration points, determine the minimum length required for the potential change path.

[0016] The total extension length is compared with the minimum length to determine whether the electric field dispersion requirement is met.

[0017] If the total extension length is insufficient, increase the number of steps or widen the single-stage width to distribute the potential across more or wider steps.

[0018] Verify whether the adjusted stepped structure makes the edge electric field strength lower than the breakdown threshold. If it does not meet the standard, repeat the adjustment.

[0019] Preferably, the potential of the annular auxiliary electrode is provided through a voltage divider circuit, specifically including:

[0020] Connect the voltage divider circuit between the main electrode and ground to form an intermediate potential output node;

[0021] Connect the intermediate potential output node to the ring auxiliary electrode so that the ring electrode obtains a stable potential, which is between the main electrode potential and the ground potential.

[0022] The potential difference between the intermediate potential and the main electrode potential is distributed over the spatial distance between the ring electrode and the main electrode. After the potential difference is distributed in space, it forms a transverse electric field component, which is used to change the direction of the electric field lines at the edge of the electrode.

[0023] Preferably, by adjusting the distance between the ring electrode and the main electrode and the ratio of the intermediate potential, the combined electric field intensity at the edge points is reduced after the transverse electric field component and the longitudinal electric field component of the main junction region are vector-superimposed. Specifically, this includes:

[0024] Based on the longitudinal electric field distribution, determine the longitudinal electric field intensity at the edge point of the main electrode end;

[0025] Adjust the ratio of the intermediate potential of the ring auxiliary electrode to make the generated transverse electric field component reach the expected control level.

[0026] Adjust the distance between the ring electrode and the main electrode to ensure that the transverse electric field covers the high field strength region at the end of the stepped structure;

[0027] Calculate the vector sum of the longitudinal and transverse electric fields at the edge points to verify whether the combined electric field strength is below the breakdown threshold.

[0028] Preferably, the height of the stepped structure decreases progressively, allowing the electrode tip to gradually transition from the main electrode plane to an uncovered area, specifically including:

[0029] Determine the difference between the initial height of the main electrode and the height of the semiconductor surface, and divide the difference into multiple decreasing amounts, corresponding to the height reduction value of each step;

[0030] Starting from the end of the main electrode, each step decreases by a certain amount from the previous step, forming a continuously descending profile. This profile allows the potential to transition smoothly from the main electrode potential to the semiconductor surface potential.

[0031] Preferably, the step of setting an annular auxiliary electrode around the stepped main electrode, with a pre-reserved gap between its inner boundary and the edge of the main electrode, includes:

[0032] Determine the required coverage width based on the lateral extent of the high field strength region;

[0033] The inner boundary of the ring electrode is set outside the high field strength region, maintaining a spacing distance. The spacing distance ensures that the electric field influence range of the ring electrode covers the entire high field strength region.

[0034] The study verified whether the transverse electric field could effectively guide the distribution of the identified electric field lines and reduce the peak field strength at the edges under the given interval.

[0035] Preferably, it further includes: determining whether the electrode layout has a sufficient safety margin by evaluating the ratio of the electric field strength in the edge region to the breakdown threshold, specifically including:

[0036] Calculate the maximum electric field intensity in the optimized edge region, compare the maximum electric field intensity with the material breakdown threshold, and obtain the ratio.

[0037] If the ratio is less than the preset safety threshold, the layout is deemed to meet the safety requirements.

[0038] If the ratio is greater than or equal to the preset safety threshold, adjust the step parameters or ring electrode parameters until the safety requirements are met.

[0039] On the other hand, the present invention proposes a system for reducing diode reverse leakage current, comprising:

[0040] A semiconductor substrate, comprising P-regions and N-regions, forms a PN junction;

[0041] The main electrode covers the surface of the N-region, and its edges adopt a stepped structure composed of multiple continuous steps.

[0042] A ring-shaped auxiliary electrode is arranged around the main electrode, with a physical gap between it and the main electrode to achieve electrical isolation, and is connected to an independent potential supply source.

[0043] The potential supply unit applies a reverse bias voltage to the main electrode and an intermediate potential to the ring auxiliary electrode.

[0044] The packaging structure is used to fix the main electrode, the ring-shaped auxiliary electrode and the semiconductor substrate, and to maintain the insulation between the electrodes.

[0045] Preferably, in the stepped structure of the main electrode, the width of each step is consistent and the height decreases step by step, so that the electrode end forms a gradual profile and extends the potential change path.

[0046] Preferably, the potential of the ring auxiliary electrode is provided by a voltage divider circuit, so that the potential difference between it and the main electrode is distributed in space to form a transverse electric field. The transverse electric field is superimposed with the longitudinal electric field of the main junction to reduce the intensity of the edge-combined electric field.

[0047] Technical effects and advantages of the present invention: Compared with the prior art, the method and system for reducing diode reverse leakage current proposed in this invention have the following advantages:

[0048] This invention designs the electrode ends with a multi-level stepped structure, extending the physical path of potential change and making the electric field gradient distribution smoother. Simultaneously, an electrically isolated ring-shaped auxiliary electrode is placed around the main electrode, applying an intermediate potential to introduce a transverse electric field component. This component, superimposed on the longitudinal electric field, reconstructs the edge electric field distribution. This method optimizes the electric field distribution synergistically from two dimensions: electrode structure and potential configuration, without altering the semiconductor material or doping process. The stepped structure allows for a gradual transition in the geometric contour of the electrode ends, avoiding abrupt potential changes and significantly reducing local electric field peaks. The transverse electric field generated by the ring-shaped auxiliary electrode guides the electric field lines to diffuse outward, reducing the density concentrated in the semiconductor interior. The combination of these two factors results in an overall decrease in the combined electric field strength in the edge region, effectively suppressing the point of maximum field strength. Consequently, the carrier tunneling probability and collisional ionization rate under reverse bias are significantly reduced, fundamentally weakening the leakage current generation mechanism. The device exhibits reduced leakage current under the same reverse voltage, can withstand higher voltages without breakdown, and has improved withstand voltage capability. Meanwhile, the homogenization of the electric field distribution reduces local thermal effects and material stress concentration, extends device life, and improves long-term operational stability. Attached Figure Description

[0049] Figure 1 This is a flowchart of a method for reducing reverse leakage current of a diode according to the present invention. Detailed Implementation

[0050] 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. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. 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.

[0051] This invention provides, for example Figure 1 The method shown aims to reduce the reverse leakage current of a diode by optimizing the electrode layout structure to reduce the electric field concentration effect in the edge region of the device, thereby effectively suppressing the carrier tunneling and thermal excitation process caused by high field strength under reverse bias, and ultimately achieving a significant reduction in leakage current. The method includes the following steps:

[0052] By setting the geometric dimensions of the P-region and N-region of the diode, defining the lateral length and the position of the PN junction, a spatial reference is provided for subsequent potential distribution analysis. By precisely setting the geometric dimensions of the P-region and N-region and defining the position of the PN junction, a physical spatial framework for potential and electric field analysis is established, providing an accurate structural basis for subsequent electric field distribution calculations.

[0053] Based on the aforementioned geometric dimensions and the net doping concentrations of the P and N regions, the built-in potential is calculated, and a reverse bias voltage is applied to form a total applied potential difference, which serves as the input for the electrode boundary conditions. The built-in potential is calculated in conjunction with the net doping concentration, and the reverse bias voltage and the built-in potential are used together as the total applied potential difference, which truly reflects the electrical boundary conditions under the device's operating state and improves the accuracy of electric field simulation and optimization.

[0054] Based on the total applied potential difference, a grounded metal electrode A is placed on top of the P-region, and a metal electrode B with a reverse bias voltage is placed on the bottom of the N-region, constructing a rectangular electrode structure with the electrode edges aligned with the semiconductor edges. Constructing this rectangular electrode structure ensures that the potential application method is consistent with the actual device, making the identification of high-field regions representative and providing a reliable starting point for subsequent targeted optimization of the electrode morphology. This series of steps collectively ensures the integrity and realism of the entire method in terms of structural modeling and electrical condition setting, laying the foundation for effectively suppressing reverse leakage current.

[0055] Based on the rectangular electrode structure, the Poisson equation is solved under the depletion layer approximation to calculate the potential distribution and derive the electric field intensity, identifying high field intensity concentration points in the electrode edge region. For these high field intensity concentration points, the original rectangular electrode ends are modified into multi-stage stepped structures, with the total extension length determined by the number of steps and the width of each stage, to extend the potential change path and reduce the local electric field gradient. This structure alters the convergence trend of electric field lines, causing the electric field distribution to gradually transition along the stepped contour, significantly reducing the local peak electric field intensity, weakening collisional ionization and tunneling effects, suppressing reverse leakage current generation at its source, and improving the device's withstand voltage performance and operational stability.

[0056] The modification of the original rectangular electrode end into a multi-stage stepped structure includes: determining the minimum length required for the potential change path based on the total potential change to be controlled at the identified high field strength concentration points; comparing the total extension length with the minimum length to determine whether the electric field dispersion requirement is met; if the total extension length is insufficient, increasing the number of steps or expanding the width of a single step to distribute the potential across more or wider steps; verifying whether the adjusted stepped structure makes the edge electric field strength lower than the breakdown threshold, and repeating the adjustment if it fails to meet the standard.

[0057] By establishing a quantitative matching relationship between the potential change path length and the electric field dispersion requirement, the stepped structure is ensured to have sufficient physical extension to bear the potential gradient. The number of steps or the width of a single step are dynamically adjusted according to the minimum length requirement to achieve targeted optimization of structural parameters and avoid insufficient electric field control or over-design. The optimization results are continuously evaluated through a cyclic verification mechanism to ensure that the final structure can keep the edge electric field strength stable below the breakdown threshold, thereby improving device reliability and design robustness.

[0058] The height of the stepped structure decreases step by step, so that the electrode end gradually transitions from the main electrode plane to the uncovered area. Specifically, this includes: determining the difference between the initial height of the main electrode and the height of the semiconductor surface, dividing the difference into multiple reduction amounts, corresponding to the height reduction value of each step; starting from the end of the main electrode, each step decreases by one reduction amount based on the previous step, forming a continuous descending profile, which allows the potential to transition smoothly from the main electrode potential to the semiconductor surface potential.

[0059] By gradually decreasing the height of the steps to form a smooth geometric transition profile, abrupt height changes between the electrode tip and the semiconductor surface are avoided, effectively reducing electric field concentration caused by structural abrupt changes. The continuously decreasing shape promotes the smooth release of potential along the steps, reducing the peak potential gradient at the interface, further weakening the acceleration effect of the local strong electric field on the charge carriers, thereby significantly suppressing the generation of reverse leakage current and improving the uniformity of electric field distribution and insulation reliability of the device.

[0060] A ring-shaped auxiliary electrode is set around the stepped main electrode, with a reserved gap between its inner boundary and the edge of the main electrode. This includes: determining the required coverage width based on the lateral range of the high field strength region; setting the inner boundary of the ring electrode outside the high field strength region while maintaining a gap, ensuring that the electric field influence range of the ring electrode covers the entire high field strength region; and verifying whether the lateral electric field can effectively guide the distribution of the identified electric field lines and reduce the peak field strength at the edge under the gap.

[0061] By rationally setting the position of the ring-shaped auxiliary electrode, its electric field range accurately covers the high-field region at the edge of the main electrode, giving full play to the electric field regulation effect. The inner boundary is located outside the high-field region and maintains an appropriate interval, which is conducive to forming a stable transverse electric field component, guiding the electric field lines to diffuse outward, and avoiding their dense convergence at the end of the main electrode. This layout enhances the ability to actively intervene in the edge electric field distribution, significantly weakens the peak field strength, and improves the uniformity of the electric field distribution, thereby effectively reducing the reverse leakage current and enhancing the device's operating stability and withstand voltage capability under high voltage.

[0062] A ring-shaped auxiliary electrode is set around the stepped main electrode. The inner boundary of the auxiliary electrode is reserved with a gap between the edge of the main electrode and the edge of the main electrode. The width of the ring structure is fixed. The electrode is electrically isolated from the main electrode. The potential is set to an intermediate potential between the potential of the main electrode and the ground potential, which is used to regulate the distribution of the edge electric field.

[0063] Specifically, the potential of the ring auxiliary electrode is provided by a voltage divider circuit, which includes: connecting the voltage divider circuit between the main electrode and ground to form an intermediate potential output node; connecting the intermediate potential output node to the ring auxiliary electrode to enable the ring electrode to obtain a stable potential, which is between the potential of the main electrode and the ground potential; the potential difference between the intermediate potential and the main electrode potential is distributed over the spatial distance between the ring electrode and the main electrode, and the potential difference forms a transverse electric field component after being distributed in space, which is used to change the direction of the electric field lines at the edge of the electrode.

[0064] By setting an electrically isolated ring auxiliary electrode and applying a controllable intermediate potential, an independent electric field control path is constructed to avoid interference with the main electrode's operating state. A stable intermediate potential is provided using a voltage divider circuit to ensure the accuracy and long-term consistency of the ring electrode potential, thereby improving the reliability of electric field control. The potential difference between the main electrode and the ring electrode forms a directional transverse electric field within the reserved gap, effectively changing the electric field line distribution in the electrode edge region, transforming it from a vertically dense distribution to an inclined or divergent shape, significantly reducing the electric field line density and local field strength peaks. This transverse electric field works in conjunction with the longitudinal electric field control of the stepped structure to achieve multi-dimensional electric field optimization, further suppressing edge electric field concentration, reducing the probability of carrier tunneling and collisional ionization, thereby significantly reducing reverse leakage current and improving the device's insulation performance and withstand voltage level.

[0065] Based on the electric field modulation effect introduced by the ring auxiliary electrode, by adjusting the number of steps, the width of a single stage, the distance between the ring electrode and the main electrode, and the ratio of the intermediate potential to the reverse bias voltage, the electric field strength in the edge region can be made lower than the field strength threshold corresponding to material breakdown.

[0066] Furthermore, by adjusting the distance between the ring electrode and the main electrode, as well as the ratio of the intermediate potential, the combined electric field strength at the edge points is reduced after the transverse electric field component and the longitudinal electric field component of the main junction region are vector-superimposed. Specifically, this includes: determining the longitudinal electric field strength at the edge points of the main electrode end based on the longitudinal electric field distribution; adjusting the ratio of the intermediate potential of the ring auxiliary electrode to achieve the expected control level for the generated transverse electric field component; adjusting the distance between the ring electrode and the main electrode to ensure that the transverse electric field covers the high field strength region at the end of the stepped structure; and calculating the vector sum of the longitudinal and transverse electric fields at the edge points to verify whether the combined electric field strength is lower than the breakdown threshold.

[0067] Through multi-parameter coordinated adjustment, precise control of the edge electric field distribution is achieved. Optimization of the number of steps and the width of a single stage further extends the potential transition path and reduces the longitudinal electric field gradient. The coordinated adjustment of the ring electrode spacing and the ratio of the intermediate potential enables the transverse electric field strength and the effective range to be precisely matched to the high field strength region. The transverse electric field component and the longitudinal electric field component are vector superimposed at the edge point, effectively offsetting part of the longitudinal field strength and significantly reducing the peak value of the synthesized electric field. By quantitatively verifying the relationship between the synthesized electric field strength and the breakdown threshold, it is ensured that the optimization results meet the safety margin requirements, fundamentally suppressing the electric field-induced carrier multiplication effect, significantly reducing the reverse leakage current, and improving the reliability and stability of the device under high reverse voltage.

[0068] The safety margin of the electrode layout is determined by evaluating the ratio of the electric field strength in the edge region to the breakdown threshold. Specifically, this includes: calculating the maximum electric field strength in the optimized edge region, comparing the maximum electric field strength with the material breakdown threshold, and obtaining the ratio; if the ratio is less than the preset safety threshold, the layout is deemed to meet the safety requirements; if the ratio is greater than or equal to the preset safety threshold, the step parameters or ring electrode parameters are adjusted until the safety requirements are met.

[0069] By quantifying the ratio of the maximum electric field strength in the edge region to the material breakdown threshold, a clear safety margin evaluation standard is established, enabling an objective judgment of the electrode structure optimization effect. This evaluation mechanism can promptly identify layouts with insufficient electric field control, triggering readjustments to the number of steps, single-stage width, annular electrode spacing, or intermediate potential ratio, forming a closed-loop optimization process. This ensures that the final structure can maintain an electric field strength below the critical value under various operating conditions, effectively avoiding the risk of local breakdown. It also improves the reliability and robustness of the device design, ensuring long-term stable operation of the diode under high reverse voltage.

[0070] On the other hand, the present invention proposes a system for reducing diode reverse leakage current, comprising:

[0071] A semiconductor substrate, comprising P-regions and N-regions, forms a PN junction;

[0072] The main electrode covers the surface of the N-region, and its edges adopt a stepped structure composed of multiple continuous steps.

[0073] A ring-shaped auxiliary electrode is arranged around the main electrode, with a physical gap between it and the main electrode to achieve electrical isolation, and is connected to an independent potential supply source.

[0074] The potential supply unit applies a reverse bias voltage to the main electrode and an intermediate potential to the ring auxiliary electrode.

[0075] The packaging structure is used to fix the main electrode, the ring-shaped auxiliary electrode and the semiconductor substrate, and to maintain the insulation between the electrodes.

[0076] Preferably, in the stepped structure of the main electrode, the width of each step is consistent and the height decreases step by step, so that the electrode end forms a gradual profile and extends the potential change path.

[0077] Preferably, the potential of the ring auxiliary electrode is provided by a voltage divider circuit, so that the potential difference between it and the main electrode is distributed in space to form a transverse electric field. The transverse electric field is superimposed with the longitudinal electric field of the main junction to reduce the intensity of the edge-combined electric field.

[0078] This system, through the aforementioned electrode layout design, achieves effective control of the edge electric field, suppressing leakage current without altering the semiconductor's inherent properties. The entire scheme is logically rigorous, with each step interconnected, forming a complete technical path from initial modeling to final evaluation. The proposed stepped structure, working synergistically with the ring electrode, addresses the fundamental problem of edge electric field concentration in traditional designs from both geometric and potential distribution perspectives. By extending the potential change path and introducing a transverse electric field component, the local field strength is significantly reduced, thereby suppressing unintended carrier transport and improving the diode's performance under reverse bias.

[0079] In addition, the aforementioned system components are also used to implement other steps of the method for reducing diode reverse leakage current, as follows:

[0080] Step 1: Determine the initial geometric parameters and electrical boundary conditions of the diode's main structure.

[0081] Define the geometric dimensions of the P-type and N-type semiconductor regions of the diode, including the lateral lengths of the P-type and N-type regions. and And the coordinates of the interface between the two (i.e., the PN junction). Let the axis extend laterally, with the origin at... Located at the left boundary of region P, then This setting is used to establish a one-dimensional spatial coordinate system, which facilitates the subsequent mathematical description of electric potential and electric field.

[0082] By clearly defining spatial coordinates and regional divisions, a clear geometric foundation is provided for modeling the potential distribution. This coordinate system will be used throughout all subsequent analysis processes, ensuring that all physical quantities are expressed within a unified framework.

[0083] In semiconductor devices, the potential distribution directly depends on spatial location, especially near the PN junction, where the potential gradient determines the electric field strength. Therefore, establishing an accurate spatial coordinate system is a prerequisite for analyzing electric field behavior.

[0084] Given the net doping concentrations of the P-region and the N-region, denoted as […]. and The unit is Assuming the doping distribution is uniform, i.e., within their respective regions... (when ), (when This setting is used to determine the space charge density. The initial expression.

[0085] The uniform doping assumption simplifies the charge distribution model, making the potential equation analytically solvable while still reflecting the main electrical characteristics of practical devices. The space charge density, contributed by dopant ions, dominates the source term of the Poisson equation within the depletion layer. This is the crucial first step in solving for the potential distribution.

[0086] Based on doping concentration and temperature (Set to 300K), calculate the built-in potential. Its expression is: ;

[0087] in Boltzmann's constant, The amount of electron charge. This represents the intrinsic carrier concentration. This value indicates the potential difference across the PN junction at zero bias and serves as the reference for the superposition of reverse bias voltages. The built-in potential determines the initial level of the depletion layer width and the maximum electric field strength, and is an important input parameter for subsequent electric field analysis. This formula originates from the Fermi level alignment principle and reflects the natural potential barrier formed by the difference in carrier concentration between the P-region and the N-region.

[0088] Apply reverse bias voltage ( At this point, the total applied potential difference is This voltage will widen the depletion layer and enhance the electric field strength near the junction, especially in the edge region where strong field concentration is likely to occur. This condition is set as the boundary input for subsequent electric field distribution calculations. Reverse bias is the main operating state for leakage current generation, and it is clearly defined... The values ​​can simulate the electric field behavior in real-world application scenarios. The applied reverse voltage increases the potential difference within the depletion layer, leading to a stronger electric field, which in turn increases the tunneling probability and leakage current level. Therefore, the edge field strength must be evaluated under these conditions.

[0089] Step 2: Establish the initial electrode layout and calculate the electric field distribution in the edge region.

[0090] After completing the basic structure and boundary conditions, the next step is to construct a standard planar electrode structure and derive the electric field intensity in its edge region using the potential equation, identify high field intensity concentration points, and provide target areas for subsequent electrode shape optimization.

[0091] The design features a standard rectangular electrode structure: metal electrode A covers the top of the P-region, and metal electrode B covers the bottom of the N-region. The lateral width of the electrodes is consistent with that of the semiconductor region. Furthermore, the electrode edges are aligned with the semiconductor edges. Electrode A is grounded (0V), and electrode B is applied... Voltage (relative to ground).

[0092] This structure is a traditional design, which is convenient to use as a benchmark for comparison and highlights the advantages of subsequent optimization schemes.

[0093] Electrode voltage directly sets the potential value at the semiconductor boundary, thus affecting the internal potential distribution. Aligned edge structures are common in manufacturing, but they can easily lead to concentration of the edge electric field.

[0094] Under the depletion layer approximation, the one-dimensional Poisson equation is solved to obtain the potential distribution. In the P-region depletion layer ( ) and N-region depletion layer ( Within ) the equation is: ;

[0095] in The dielectric constant of a semiconductor is _____. Within the depletion region, it is approximately constant (a one-sided abrupt knot can be simplified to...). ).

[0096] This equation describes how charge distribution affects the second-order change of electric potential and is the core of electric field calculations.

[0097] Poisson's equation is the fundamental equation of electrostatics, connecting charge density and electric potential curvature; its solution directly determines the electric field. .

[0098] Integrate the above equation twice and apply the boundary conditions. We obtain the electric potential function. Then, by differentiation, we obtain the electric field distribution: ;

[0099] in The integral constant is determined by the junction position and doping. The maximum electric field occurs at... place, that is , The expression represents the total depletion layer width. This expression reveals the relationship between the maximum electric field and the doping concentration, dielectric constant, and depletion layer width, providing a quantitative basis for subsequent optimization. In the abrupt junction model, the electric field exhibits a linear distribution, with the peak value located at the junction center.

[0100] A two-dimensional effect is introduced to analyze the edge electric field enhancement. Considering the curvature effect at the electrode edge, conformal mapping or numerical methods are used to estimate the edge electric field amplification factor. Its empirical expression is: ;

[0101] in The effective radius of curvature of the electrode edge (approaches 0 in a rectangular structure, leading to...) Therefore, the edge electric field The electric field strength is much higher than that in the central region. This formula quantifies the phenomenon of enhanced electric field at the edges, clearly indicating that sharp edges are the root cause of high field strength. In an electrostatic field, the greater the curvature (smaller the radius) of a conductor's edge, the higher the charge density, leading to a sharp increase in the local electric field. This is the physical root cause of concentrated leakage current.

[0102] Step 3: Design a stepped electrode edge structure to disperse edge charge density

[0103] To address the problem of concentrated edge electric fields identified in step two, this step proposes a stepped electrode edge layout. By changing the geometry of the electrode ends, the potential change path is extended, thereby reducing the local electric field gradient.

[0104] The right-angled edges of the original rectangular electrode were modified into a multi-level stepped structure. Assume the electrode ends are divided laterally into... There are 1 step, and the width of each step is... decreasing in height The total extension length is The structure gradually transitions from the main electrode region to the electrode-free area. The stepped structure increases the equivalent radius of curvature at the electrode edges, preventing abrupt changes in potential. Since the potential must be continuous on the conductor surface, the stepped edges force the potential to change over a longer path, thus reducing the electric field strength.

[0105] Establish an equivalent potential distribution model for the stepped region. Let the first... The potential of the step is Since the metal electrode is an equipotential body, all steps have the same potential, which is... However, the potential of the semiconductor surface beneath it gradually decreases due to its distance from the main junction region. Introducing a lateral distance... (Extending from the main junction to the edge), then the surface potential satisfy: ;

[0106] in The potential decay length is related to the depletion layer characteristics. This equation describes the exponential decay behavior of the potential in the edge region. This model reflects the weakening trend of the electric field away from the junction region, providing a distance basis for stepped design. In the edge region, the electric field lines diverge outward, causing the potential change to slow down, which can be approximated by an exponential function.

[0107] Calculate the local electric field under the stepped structure. In the... At the end of the step, the transverse electric field component Determined by the potential gradient: ;

[0108] in .because The changes were gradual, and limited, Significantly lower than the theoretical infinity at the right-angled edge. The finite step width disperses the potential difference across multiple small segments, avoiding drastic changes at a single point. The electric field is the spatial derivative of the potential; discretization transforms the derivative into a difference, limiting its maximum value.

[0109] Optimize the number of steps With single-level width The objective is to maximize the edge electric field. Below the breakdown threshold .Depend on ;

[0110] Require , can be obtained This condition guides the selection of structural parameters. This inequality provides a lower limit for the design, ensuring that the electric field is controlled within a safe range.

[0111] The total potential difference was The burden is shared among the steps, with each step bearing approximately [amount missing]. The pressure drop spans are Therefore, the electric field is inversely proportional to .

[0112] Step 4: Introduce a ring-shaped auxiliary electrode to guide the uniform distribution of electric field lines.

[0113] To further improve the electric field distribution, this step adds a ring-shaped auxiliary electrode around the main electrode. The electric field lines are guided by the setting of its potential, reducing the tendency to concentrate towards the edge.

[0114] A ring-shaped conductive structure, denoted as electrode C, is disposed around the main electrode (electrode B). The inner boundary of electrode C is located at a distance of [distance missing] from the edge of the main electrode. The ring width is Electrode C is electrically isolated from the main electrode and can be applied with a potential independently. .

[0115] Electrode C, as an electric field control element, does not participate in the main current path and is only used for electrostatic field shaping.

[0116] The electric potential of the external conductor affects the internal electric field distribution; this can be mitigated by proper configuration. It can change the divergence direction of electric field lines.

[0117] Connect electrode C to a voltage divider circuit to make its potential Between the main electrode potential Between the ground potential of 0V and the earth potential of 0V. Assume... ,in This intermediate potential makes electrode C a "buffer zone" for the electric field lines.

[0118] Intermediate potential avoids from The direct jump to 0 allows for a smooth transition of the electric field lines.

[0119] Electric field lines begin at high potentials and terminate at low potentials. Setting an intermediate potential point can attract some of the electric field lines, reducing their concentration towards the physical edges.

[0120] Analyze the effect of electrode C on the electric field distribution. Let the potential difference between point A at the edge of the main electrode and point B on electrode C be... The distance between the two points is The average electric field is then: ;

[0121] when When it approaches 1, Decrease A decrease means that electrode C effectively shields the strong field at the edge of the main electrode. This can be achieved by adjusting... The edge electric field strength can be dynamically controlled. Reducing the potential difference directly lowers the electric field, while... It provides adjustable degrees of freedom.

[0122] optimization and The combination of [variables] is required. The maximum electric field at the edge is required after electrode C is introduced. satisfy: ;

[0123] in For the target suppression ratio, Let be the edge electric field strength without electrode C. Determine the condition that satisfies the given conditions through numerical simulation or approximate calculation. scope.

[0124] This condition ensures that the performance improvement achieves the expected target. The effect of electrode C varies with distance. Increase and decrease, but Need to follow Adjustments were made to maintain the shielding effect.

[0125] Step 5: Combine the stepped structure with the ring electrode to achieve composite electric field modulation.

[0126] By combining the stepped main electrode from step three with the ring-shaped auxiliary electrode from step four, a composite electrode layout is formed, enabling multi-dimensional electric field control and further reducing the electric field peak value in the edge region.

[0127] Using the stepped electrode from step three as the main electrode (electrode B), its end has Step-like steps. Based on this, the annular electrode C from step four is arranged around the entire periphery of the main electrode, with its inner boundary maintaining a distance from the outermost step of the main electrode. The stepped structure addresses the local potential gradient, while the ring electrode regulates the overall electric field direction; the two work synergistically. Combining local geometric optimization with global potential guidance more comprehensively suppresses electric field concentration.

[0128] Set the potential of the ring electrode C ,in The selection is based on the optimization results. At this point, the potential difference from the outermost step of the main electrode to electrode C is... The pressure drop is distributed at a distance of Above, a transverse electric field is formed: The direction of this electric field is perpendicular to the electric field of the main junction, which has a lateral stretching effect and reduces the vertical field strength at the edge.

[0129] The transverse electric field alters the direction of the electric field lines, making them more parallel to the surface and reducing the vertical component. The electric field is a vector, and its direction is determined by all charges. The external electrodes introduce a transverse component, which can partially offset the vertical concentration.

[0130] Calculate the total electric field intensity under the composite structure. At the edge point P, the electric field consists of three superimposed parts: the longitudinal field of the main junction... Transverse field caused by stepped structure Transverse field caused by ring electrode The synthesized electric field mode is: ;

[0131] Through design Large enough to significantly reduce ,even though Unchanged. The vector summation effect allows the overall field strength to be weakened by increasing the transverse component. The electric field strength is determined by the vector sum; increasing the orthogonal component can change the direction and magnitude of the resultant force.

[0132] Verify the stability of the composite structure. Under reverse voltage... When changes occur, check Does it always remain below Define the safety margin. ;

[0133] Requirements for all work ,have If not satisfied, adjust. Continue until the target is met. Ensure the device operates safely across its entire operating range. When the reverse voltage increases, all electric field components are enhanced; sufficient margin must be allowed.

[0134] Step Six: Complete the electrode layout and evaluate the leakage current suppression effect.

[0135] After completing the electrode structure optimization, the final step is to integrate all design parameters to form the final layout and estimate the degree of reduction in leakage current based on the electric field distribution.

[0136] Summary of all structural parameters: The main electrode adopts Steps, each step is wide The distance between the annular auxiliary electrode C and the main electrode ,Width The potential is set to Semiconductor parameters Keeping constant, estimate the optimized maximum edge electric field. .

[0137] Combining the vector model with the step voltage effect, we have: This formula combines the longitudinal depletion field and the transverse modulation field to evaluate the total field strength.

[0138] Reverse leakage current estimated based on electric field strength The leakage current is mainly contributed by tunneling and thermal excitation, and its field dependence is as follows: ;in These are material-related constants. It can be seen that... right Extremely sensitive.

[0139] Calculate leakage current suppression ratio : ;

[0140] like ,but This indicates a significant reduction in leakage current. This ratio quantifies the performance gain of this scheme, completing the final evaluation. Utilizing the field strength sensitivity of leakage current, even a small decrease in the electric field can lead to a substantial suppression of the current.

[0141] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reducing reverse leakage current of a diode, characterized in that, Includes the following steps: Define the geometric dimensions of the P-region and N-region of the diode, and define the lateral length and PN junction position to provide a spatial reference for subsequent potential distribution analysis; Based on the aforementioned geometric dimensions and the net doping concentrations of the P and N regions, the built-in potential is calculated, and a reverse bias voltage is applied to form a total applied potential difference, which serves as the input for the electrode boundary conditions. Based on the total applied potential difference, a grounded metal electrode A is covered on the top of the P region, and a metal electrode B with a reverse bias voltage is covered on the bottom of the N region, thus constructing a rectangular electrode structure with the electrode edge aligned with the semiconductor edge. Based on the rectangular electrode structure, the Poisson equation is solved under the depletion layer approximation to calculate the potential distribution, derive the electric field intensity, and identify the high field intensity concentration points in the electrode edge region. For the high field strength concentration point, the end of the original rectangular electrode is modified into a multi-stage stepped structure. The total extension length is determined by the number of steps and the width of a single stage, so as to extend the potential change path and reduce the local electric field gradient. A ring-shaped auxiliary electrode is set around the stepped main electrode. The inner boundary of the auxiliary electrode is reserved with a gap between the edge of the main electrode and the edge of the main electrode. The width of the ring structure is fixed. The electrode is electrically isolated from the main electrode. The potential is set to an intermediate potential between the potential of the main electrode and the ground potential, which is used to regulate the distribution of the edge electric field. Based on the electric field modulation effect introduced by the ring auxiliary electrode, by adjusting the number of steps, the width of a single stage, the distance between the ring electrode and the main electrode, and the ratio of the intermediate potential to the reverse bias voltage, the electric field strength in the edge region can be made lower than the field strength threshold corresponding to material breakdown.

2. The method for reducing diode reverse leakage current according to claim 1, characterized in that, The modification of the original rectangular electrode end to a multi-level stepped structure includes: Based on the total potential change that needs to be controlled at the identified high field strength concentration points, determine the minimum length required for the potential change path. The total extension length is compared with the minimum length to determine whether the electric field dispersion requirement is met. If the total extension length is insufficient, increase the number of steps or widen the single-stage width to distribute the potential across more or wider steps. Verify whether the adjusted stepped structure makes the edge electric field strength lower than the breakdown threshold. If it does not meet the standard, repeat the adjustment.

3. The method for reducing diode reverse leakage current according to claim 1, characterized in that, The potential of the ring-shaped auxiliary electrode is provided through a voltage divider circuit, specifically including: Connect the voltage divider circuit between the main electrode and ground to form an intermediate potential output node; Connect the intermediate potential output node to the ring auxiliary electrode so that the ring electrode obtains a stable potential, which is between the main electrode potential and the ground potential. The potential difference between the intermediate potential and the main electrode potential is distributed over the spatial distance between the ring electrode and the main electrode. After the potential difference is distributed in space, it forms a transverse electric field component, which is used to change the direction of the electric field lines at the edge of the electrode.

4. The method for reducing diode reverse leakage current according to claim 1, characterized in that, By adjusting the distance between the ring electrode and the main electrode, as well as the ratio of the intermediate potential, the combined electric field intensity at the edge points is reduced after the transverse electric field component and the longitudinal electric field component of the main junction region are vector-superimposed. Specifically, this includes: Based on the longitudinal electric field distribution, determine the longitudinal electric field intensity at the edge point of the main electrode end; Adjust the ratio of the intermediate potential of the ring auxiliary electrode to make the generated transverse electric field component reach the expected control level. Adjust the distance between the ring electrode and the main electrode to ensure that the transverse electric field covers the high field strength region at the end of the stepped structure; Calculate the vector sum of the longitudinal and transverse electric fields at the edge points to verify whether the combined electric field strength is below the breakdown threshold.

5. The method for reducing diode reverse leakage current according to claim 1, characterized in that, The height of the stepped structure decreases gradually, allowing the electrode tip to transition gradually from the main electrode plane to an uncovered area, specifically including: Determine the difference between the initial height of the main electrode and the height of the semiconductor surface, and divide the difference into multiple decreasing amounts, corresponding to the height reduction value of each step; Starting from the end of the main electrode, each step decreases by a certain amount from the previous step, forming a continuously descending profile. This profile allows the potential to transition smoothly from the main electrode potential to the semiconductor surface potential.

6. The method for reducing diode reverse leakage current according to claim 1, characterized in that, The provision of an annular auxiliary electrode around the stepped main electrode, with a pre-reserved gap between its inner boundary and the edge of the main electrode, includes: Determine the required coverage width based on the lateral extent of the high field strength region; The inner boundary of the ring electrode is set outside the high field strength region, maintaining a spacing distance. The spacing distance ensures that the electric field influence range of the ring electrode covers the entire high field strength region. The study verified whether the transverse electric field could effectively guide the distribution of the identified electric field lines and reduce the peak field strength at the edges under the given interval.

7. The method for reducing diode reverse leakage current according to claim 1, characterized in that, Also includes: The safety margin of the electrode layout is determined by evaluating the ratio of the electric field strength in the edge region to the breakdown threshold. Specifically, this includes: Calculate the maximum electric field intensity in the optimized edge region, compare the maximum electric field intensity with the material breakdown threshold, and obtain the ratio. If the ratio is less than the preset safety threshold, the layout is deemed to meet the safety requirements. If the ratio is greater than or equal to the preset safety threshold, adjust the step parameters or ring electrode parameters until the safety requirements are met.

8. A system for reducing diode reverse leakage current to implement the method as described in any one of claims 1-7, characterized in that, include: A semiconductor substrate, comprising P-regions and N-regions, forms a PN junction; The main electrode covers the surface of the N-region, and its edges adopt a stepped structure composed of multiple continuous steps. A ring-shaped auxiliary electrode is arranged around the main electrode, with a physical gap between it and the main electrode to achieve electrical isolation, and is connected to an independent potential supply source. The potential supply unit applies a reverse bias voltage to the main electrode and an intermediate potential to the ring auxiliary electrode. The packaging structure is used to fix the main electrode, the ring-shaped auxiliary electrode and the semiconductor substrate, and to maintain the insulation between the electrodes.

9. The system for reducing diode reverse leakage current according to claim 8, characterized in that, In the stepped structure of the main electrode, the width of each step is consistent and the height decreases step by step, so that the electrode end forms a gradual profile and extends the potential change path.

10. The system for reducing diode reverse leakage current according to claim 8, characterized in that, The potential of the ring auxiliary electrode is provided by a voltage divider circuit, which distributes the potential difference between it and the main electrode in space, forming a transverse electric field. The transverse electric field is superimposed with the longitudinal electric field of the main junction, which reduces the intensity of the edge-combined electric field.

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