A method and system for modeling a shielded gate trench MOSFET

Abstract

The present application relates to the technical field of power semiconductor device design, and particularly relates to a modeling method and system of shielded gate trench MOSFET. The method comprises the following steps: selecting characteristic point key positions of the shielded gate trench structure, wherein the characteristic point key positions comprise corners, edges and centers; calculating the electric field intensity of the characteristic point key positions through two-dimensional simulation to generate an electric field intensity distribution map; based on the electric field intensity distribution map, defining a set of trapezoidal angle parameters to design the shape of the shielded gate as a trapezoidal structure with the upper part being wide and the lower part being narrow; modeling and establishing a quantitative relationship between the side wall inclination angle and the electric field intensity of the trench corner; generating an angle-electric field response curve; and calculating the change of the overlapping area between the shielded gate and the control gate in the trench for different trapezoidal structures. The present application provides clear performance improvement indicators and optimization directions for power MOSFET design by analyzing the relationship between the trapezoidal angle and the gate overlapping area.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power semiconductor device design, and particularly relates to a modeling method and system of shielded gate trench MOSFET. BACKGROUND

[0002] Power semiconductor devices are the core components of modern power electronic systems, among which shielded gate trench MOSFETs are widely used due to their excellent switching performance and low on-resistance. However, the traditional rectangular shielded gate MOSFET has a problem of electric field concentration at the corner, especially in the sharp corner region where the shielded gate bottom and side meet. Through accurate modeling analysis, these sharp corner regions become the highest points of electric field strength, limiting the breakdown voltage of the device, and are also hot spots and reliability hazards.

[0003] In the prior art, the shielded gate structure is mostly designed in a rectangular shape, which is relatively simple in manufacturing process, but in high-voltage applications, the sharp corners of the rectangular structure can cause serious electric field concentration. This electric field concentration not only reduces the breakdown voltage of the device, but also causes local hot spots during long-term operation, accelerating device aging and failure. In addition, the large-area overlap of the rectangular shielded gate and the control gate also increases the gate charge, reduces the switching speed, and increases the switching loss.

[0004] Currently, the industry's optimization of shielded gate structures mainly focuses on adjusting parameters such as gate spacing and depth, lacking systematic research and optimization methods for the gate geometry itself. Especially in the modeling and design stage, there is a lack of comprehensive optimization methods that combine changes in geometry, electric field distribution, gate charge, and manufacturing process, which limits the improvement of device performance.

[0005] Therefore, there is an urgent need for a modeling method that can systematically optimize the shielded gate geometry while considering electric field distribution, gate charge, and manufacturing process to improve the performance and reliability of power MOSFETs. SUMMARY

[0006] Therefore, it is necessary to provide a modeling method and system of shielded gate trench MOSFET to solve at least one of the above technical problems.

[0007] To achieve the above purpose, a modeling method of shielded gate trench MOSFET includes the following steps:

[0008] Step S1: Selecting key positions of characteristic points of the shielded gate trench structure, wherein the key positions of the characteristic points include corners, edges, and centers, calculating the electric field strength of the key positions of the characteristic points through two-dimensional simulation, and generating an electric field strength distribution map;

[0009] Step S2: Based on the electric field intensity distribution map, the shape of the shielding gate is designed as a trapezoidal structure with the upper part being wide and the lower part being narrow by defining a set of trapezoidal angle parameters, a quantitative relationship between the sidewall inclination angle and the electric field intensity at the corner of the trench is modeled and established, and an angle-electric field response curve is generated;

[0010] Step S3: Using the angle-electric field response curve, the change in the overlapping area between the shielding gate and the control gate in the trench of different trapezoidal structures is calculated, and the gate charge optimization rate and the optimal trapezoidal angle are generated;

[0011] Step S4: Obtain the angle control parameters and reactive ion etching parameters of the etching equipment, based on the gate charge optimization rate, and combined with the angle control capability parameters of the semiconductor etching process, the target structure is realized by adaptively controlling the etching conditions, and a trapezoidal shielding gate process scheme is generated;

[0012] Step S5: Compare the performance difference between the trapezoidal shielding gate designed by the trapezoidal shielding gate process scheme and the preset rectangular shielding gate, measure the breakdown voltage improvement amplitude, switch loss reduction ratio and heat distribution improvement degree, and generate a structure optimization benefit report.

[0013] Preferably, the present application also provides a shielding gate trench MOSFET modeling system for executing the shielding gate trench MOSFET modeling method as described above, the shielding gate trench MOSFET modeling system comprising:

[0014] An electric field distribution analysis module for selecting key characteristic points of the shielding gate trench structure, wherein the key characteristic points include corners, edges and centers, calculating the electric field intensity of the key characteristic points through two-dimensional simulation, and generating an electric field intensity distribution map;

[0015] A trapezoidal structure optimization module for designing the shape of the shielding gate as a trapezoidal structure with the upper part being wide and the lower part being narrow by defining a set of trapezoidal angle parameters based on the electric field intensity distribution map, modeling and establishing a quantitative relationship between the sidewall inclination angle and the electric field intensity at the corner of the trench, and generating an angle-electric field response curve;

[0016] A gate charge balance module for calculating the change in the overlapping area between the shielding gate and the control gate in the trench of different trapezoidal structures using the angle-electric field response curve, and generating the gate charge optimization rate and the optimal trapezoidal angle;

[0017] A process parameter conversion module for obtaining the angle control parameters and reactive ion etching parameters of the etching equipment, based on the gate charge optimization rate, and combined with the angle control capability parameters of the semiconductor etching process, realizing the target structure by adaptively controlling the etching conditions, and generating a trapezoidal shielding gate process scheme;

[0018] The performance comparison and evaluation module is used for comparing the performance difference between the trapezoidal shielding gate designed by the trapezoidal shielding gate process scheme and the preset rectangular shielding gate, measuring the breakdown voltage improvement amplitude, the switch loss reduction ratio and the heat distribution improvement degree, and generating a structure optimization benefit report.

[0019] The present application has the following advantages:

[0020] On the one hand, by analyzing the electric field distribution characteristics in the shielding gate trench structure, identifying the key feature point position, and establishing the quantitative relationship between the side wall inclination angle and the electric field intensity, the accurate regulation and control of the electric field distribution are realized. The design of the trapezoidal structure with wide upper part and narrow lower part eliminates the sharp corner, makes the electric field distribution more uniform, and significantly improves the breakdown voltage of the device, typically by 15-25%.

[0021] On the other hand, by establishing the relationship model between the trapezoidal angle and the gate overlap area, the optimization of the gate charge is realized. The trapezoidal structure reduces the overlap area between the shielding gate and the control gate, reduces the Miller capacitance, improves the switching speed, reduces the switching loss, and maintains good shielding effect.

[0022] In addition, the present application combines the theoretical model with the actual process parameters, establishes the conversion mechanism from the optimal trapezoidal angle to the etching process parameters, and ensures the implementability of the design scheme. By adaptively controlling the etching conditions, the accurate manufacturing of the trapezoidal shielding gate structure is realized without adding additional manufacturing steps, maintaining the process compatibility and cost effectiveness.

[0023] Finally, the present application quantitatively analyzes the comprehensive advantages of the trapezoidal shielding gate structure relative to the traditional rectangular structure through systematic performance comparison and evaluation, provides clear performance improvement indicators and optimization direction for power MOSFET design, has significant practical value and popularization significance. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 It is a step flowchart of a modeling method for a shielding gate trench MOSFET.

[0025] Fig. 2 It is a comparison diagram of the traditional rectangular shielding gate and the trapezoidal shielding gate structure.

[0026] The purpose realization, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0027] The technical method of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] In addition, the drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. Identical reference numerals in the drawings represent identical or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities, which do not necessarily have to correspond to physically or logically independent entities. The functional entities can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0029] It should be understood that although the terms "first", "second" and the like can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element can be referred to as a second element, and similarly a second element can be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] To achieve the above-mentioned purpose, please refer to Figs. 1-2 The present application provides a modeling method of shielded gate trench MOSFET, comprising the following steps:

[0031] Step S1: selecting characteristic point key positions of the shielded gate trench structure, wherein the characteristic point key positions include corners, edges and centers, calculating the electric field intensity of the characteristic point key positions by two-dimensional simulation, and generating an electric field intensity distribution map;

[0032] In the embodiments of the present application, first, the key positions sensitive to the electric field distribution characteristics in the shielded gate trench structure are selected as characteristic points, which include corners, edges and center positions. The characteristic points are calculated by two-dimensional simulation to obtain the electric field intensity of each point, and an electric field intensity distribution map is generated to intuitively display the electric field concentration area.

[0033] In an implementation form of the embodiment of the application, the key positions of the feature points specifically include a 90° corner point at the bottom of the shield gate, a middle point of the sidewall, a top transition region, and a depletion region boundary point, etc. The electric field intensity of each feature point is obtained by simulating and calculating the electric field intensity of these feature points under a preset bias condition (such as a drain voltage of 600 V) through a finite element analysis software. For example, in a rectangular shield gate structure, the electric field intensity of the 90° corner point at the bottom reaches V / cm, and the electric field intensity of the middle point of the sidewall is V / cm.

[0034] Step S2: Based on the electric field intensity distribution map, the shape of the shield gate is designed as a trapezoidal structure with the top wide and the bottom narrow by defining a set of trapezoidal angle parameters, a quantitative relationship between the sidewall inclination angle and the electric field intensity at the trench corner is established, and an angle-electric field response curve is generated;

[0035] In the embodiment of the application, the electric field concentration region is mainly located at the 90° corner at the bottom of the shield gate according to the electric field intensity distribution map obtained in step S1. In order to optimize the electric field distribution of this region, a set of trapezoidal angle parameters is defined, the shape of the shield gate is designed as a trapezoidal structure with the top wide and the bottom narrow, so as to eliminate the sharp corner and make the electric field distribution more uniform.

[0036] In an implementation form of the embodiment of the application, the set of trapezoidal angle parameters includes five different angle variable values of 75°, 80°, 85°, 87°, and 89°, and the top width of the shield gate is kept unchanged. For each angle value, the electric field intensity of the feature point is recalculated, a functional relationship between the sidewall inclination angle and the maximum electric field intensity at the corner region is established, and an angle-electric field response curve is generated. For example, when the sidewall inclination angle decreases from 90° (rectangular) to 85°, the maximum electric field intensity at the corner region decreases from V / cm to V / cm, which is reduced by about 20%.

[0037] Step S3: The variation of the overlapping area between the shield gate and the control gate in the trench of different trapezoidal structures is calculated by using the angle-electric field response curve, and a gate charge optimization rate and an optimal trapezoidal angle are generated.

[0038] In the embodiment of the application, after the angle-electric field response curve is obtained, the influence of the trapezoidal structure on the gate charge is further analyzed. Due to the characteristics of the trapezoidal structure with the top wide and the bottom narrow, the overlapping area between the shield gate and the control gate in the trench is reduced, so as to reduce the gate charge and improve the switching speed.

[0039] In one implementation of the embodiment of the present application, the inter-electrode capacitance of the gate-shield gate under different trapezoidal angles is calculated by the segmented integration method. For example, when the sidewall inclination angle is 85°, the overlapping area is reduced by 15% compared with the rectangular shield gate structure, and the corresponding gate charge is also reduced by about 15%. By comprehensively considering the dual benefits of the reduction of electric field intensity and the reduction of gate charge, the optimal trapezoidal angle is determined.

[0040] Step S4: Obtain the angle control parameters and reactive ion etching parameters of the etching equipment, based on the gate charge optimization rate, and combined with the angle control capability parameters of the semiconductor etching process, realize the target structure by adaptively controlling the etching conditions, and generate a trapezoidal shield gate process scheme;

[0041] In the embodiment of the present application, the theoretical design is combined with the actual process to obtain the angle control parameters and reactive ion etching parameters of the etching equipment to evaluate the feasibility of the process implementation. Based on the gate charge optimization rate and the optimal trapezoidal angle obtained in step S3, combined with the angle control capability parameters of the etching process, a trapezoidal shield gate process scheme is generated.

[0042] In one implementation of the embodiment of the present application, for the determined optimal trapezoidal angle (such as 85°), the reactive ion etching parameters are adjusted, including the gas ratio, power, pressure and time parameters, to generate an angle etching formula table. For example, by increasing the ratio of (Carbon tetrafluoride) to (Oxygen), and increasing the radio frequency power, a trapezoidal sidewall closer to 85° can be achieved. At the same time, a corresponding relationship between the etching parameters and the actual formed angle is established to realize adaptive adjustment of the process parameters, and to ensure that the angle deviation is controlled within ±0.5°.

[0043] Step S5: Compare the performance difference between the trapezoidal shield gate designed by the trapezoidal shield gate process scheme and the preset rectangular shield gate, measure the breakdown voltage improvement amplitude, switch loss reduction ratio and heat distribution improvement degree, and generate a structure optimization benefit report.

[0044] In the embodiment of the present application, based on the same device structure parameters, the performance difference between the trapezoidal shield gate and the traditional rectangular shield gate is compared, and the key parameters are measured, including the breakdown voltage, on-resistance, gate charge and switching time, to generate a double-structure parameter comparison table.

[0045] In one implementation of the embodiment of the present application, compared with the rectangular shield gate structure, the trapezoidal shield gate structure has a 20% increase in breakdown voltage (such as from 600V to 720V), a 15% reduction in gate charge, a 12% reduction in switch loss, a more uniform heat distribution, and a 15°C reduction in hotspot temperature. By calculating the input-output ratio, the overall application value of the trapezoidal shield gate structure is evaluated, and a structure optimization benefit report is generated.

[0046] Preferably, step S1 comprises the following steps:

[0047] Step S11: positioning the points sensitive to the electric field distribution in the shielded gate trench structure, including the bottom 90° corner point, the sidewall midpoint, the top transition region, and the depletion region boundary point, recording the spatial coordinates, and generating an electric field characteristic point position table;

[0048] In the embodiment of the present application, first, the points sensitive to the electric field distribution in the shielded gate trench structure are accurately positioned. These points include the bottom 90° corner point, the sidewall midpoint, the top transition region, and the depletion region boundary point. The accurate spatial coordinates of these points are determined by device simulation software, and an electric field characteristic point position table is generated.

[0049] In one implementation manner of the embodiment of the present application, it is assumed that the trench depth is 3 μm, the width is 1 μm, and the shielded gate thickness is 0.5 μm. The coordinates of the bottom 90° corner point are (0.5 μm, 2.5 μm), the coordinates of the sidewall midpoint are (0.5 μm, 2.0 μm), the coordinates of the top transition region are (0.5 μm, 1.5 μm), and the coordinates of the depletion region boundary point are (0.7 μm, 2.5 μm). These coordinate values are recorded in the electric field characteristic point position table, providing a basis for subsequent electric field calculation.

[0050] Step S12: calculating the electric field intensity vector and the potential gradient under the preset bias condition for the electric field characteristic point position table, recording the electric field intensity value and direction, and generating a characteristic point electric field intensity table;

[0051] In the embodiment of the present application, based on the electric field characteristic point position table obtained in step S11, the electric field intensity vector and the potential gradient of each characteristic point are calculated under the preset bias condition (such as a drain voltage of 600 V and a gate voltage of 0 V). The value and direction of the electric field intensity are recorded, and a characteristic point electric field intensity table is generated.

[0052] In one implementation manner of the embodiment of the present application, the following results are calculated by the finite element analysis method:

[0053] The electric field intensity of the bottom 90° corner point is V / cm, and the direction is 135°;

[0054] The electric field intensity of the sidewall midpoint is V / cm, and the direction is 180°;

[0055] The electric field intensity of the top transition region is V / cm, and the direction is 225°;

[0056] The electric field intensity of the depletion region boundary point is V / cm, and the direction is 90°.

[0057] These values and direction information are recorded in the feature point electric field strength table.

[0058] Step S13: connecting the electric field values of each feature point to form a continuous electric field distribution representation, identifying the area where the electric field strength exceeds the preset threshold, and generating an electric field strength distribution map.

[0059] In the embodiment of the present application, based on the feature point electric field strength table obtained in step S12, the electric field values of each feature point are connected to form a continuous electric field distribution representation. A preset threshold (such as V / cm) is set to identify the area where the electric field strength exceeds the threshold, and an electric field strength distribution map is generated.

[0060] In one implementation of the embodiment of the present application, the electric field values of each feature point are connected by an interpolation algorithm to generate a continuous electric field distribution surface. In the electric field strength distribution map, color gradient is used to represent the change of electric field strength, red color represents the area with the highest electric field strength, and blue color represents the area with lower electric field strength. The area where the electric field strength exceeds V / cm is identified, and these areas are mainly concentrated at the 90° corner at the bottom of the shield gate, which is the focus of subsequent optimization.

[0061] Preferably, step S2 comprises the following steps:

[0062] Step S21: defining the trapezoidal side wall inclination angle, setting five different angle variable values of 75°, 80°, 85°, 87°, 89°, and keeping the shield gate top width unchanged to generate a trapezoidal angle parameter set;

[0063] In the embodiment of the present application, in order to systematically study the influence of trapezoidal structure on electric field distribution, the trapezoidal side wall inclination angle α is defined, and five different angle variable values of 75°, 80°, 85°, 87°, 89° are set. When setting different angles, the shield gate top width is kept unchanged, and only the inclination degree of the side wall is changed, thereby generating a trapezoidal angle parameter set.

[0064] In one implementation of the embodiment of the present application, it is assumed that the shield gate top width is 0.5 μm and the trench depth is 3 μm. When the side wall inclination angle is 90°, the shield gate is a standard rectangular shield gate structure, and the bottom width is also 0.5 μm; when the side wall inclination angle is 85°, the bottom width is reduced to about 0.44 μm; when the side wall inclination angle is 80°, the bottom width is reduced to about 0.38 μm; and when the side wall inclination angle is 75°, the bottom width is reduced to about 0.32 μm. These trapezoidal structures with different angles constitute a trapezoidal angle parameter set.

[0065] Step S22: for each trapezoidal angle parameter in the trapezoidal angle parameter set, calculating the position coordinates corresponding to the feature points to generate an angle adjustment position mapping table;

[0066] In the embodiment of the present application, for each angle value in the trapezoidal angle parameter set, the position coordinates of the feature points are recalculated. Due to the change in the position of the feature points caused by the trapezoidal structure, a mapping relationship between the angle and the position needs to be established to generate an angle adjustment position mapping table.

[0067] In one implementation manner of the embodiment of the present application, taking the bottom corner point as an example, when the side wall inclination angle is 90°, the coordinates are (0.5 μm, 2.5 μm); when the side wall inclination angle is 85°, the coordinates become (0.44 μm, 2.5 μm); when the side wall inclination angle is 80°, the coordinates become (0.38 μm, 2.5 μm). Similarly, the position coordinates of other feature points under different angles are calculated to generate a complete angle adjustment position mapping table.

[0068] Step S23: constructing a geometric shape model of the shielding gate according to the angle adjustment position mapping table;

[0069] In the embodiment of the present application, based on the angle adjustment position mapping table obtained in step S22, a geometric shape model of the shielding gate is constructed. For each trapezoidal angle parameter, a corresponding shielding gate geometric shape model is generated to provide a basis for subsequent electric field analysis.

[0070] In one implementation manner of the embodiment of the present application, using computer-aided design (CAD) software, a shielding gate geometric shape model of different trapezoidal angles is constructed according to the coordinate data in the angle adjustment position mapping table. For example, for a trapezoidal structure with a side wall inclination angle of 85°, a trapezoidal model with a top width of 0.5 μm, a bottom width of 0.44 μm, and a height of 0.5 μm is constructed. These geometric shape models will be used for subsequent electric field simulation analysis.

[0071] Step S24: recalculating the electric field intensity of each feature point under different trapezoidal angles according to the geometric shape model, establishing a functional relationship between the angle and the maximum electric field intensity of the corner region, and generating an angle-electric field response curve.

[0072] In the embodiment of the present application, based on the geometric shape model constructed in step S23, the electric field intensity of each feature point under different trapezoidal angles is recalculated. The change in the electric field distribution of the corner region is particularly concerned, a functional relationship between the side wall inclination angle and the maximum electric field intensity of the corner region is established, and an angle-electric field response curve is generated.

[0073] In one implementation manner of the embodiment of the present application, through a finite element analysis software, an electric field simulation is performed on the shielding gate structure of different trapezoidal angles. The calculation result shows that as the side wall inclination angle decreases from 90° to 75°, the maximum electric field intensity of the corner region gradually decreases. For example, when the angle is 90° (rectangle), the maximum electric field intensity is V / cm; when the angle is 85°, the maximum electric field strength is reduced to V / cm; when the angle is 80°, the maximum electric field strength is further reduced to V / cm; when the angle is 75°, the maximum electric field strength is reduced to V / cm. By these data points, the angle-electric field response curve is drawn, which intuitively shows the influence of trapezoidal angle on electric field strength.

[0074] Please refer to Fig. 2 shown, for a comparison diagram of a traditional rectangular shielding gate and a trapezoidal shielding gate structure.

[0075] The left side of the comparison diagram is a traditional rectangular shielding gate structure: the sidewall and the bottom form a standard 90° right angle; the top and bottom widths are both 0.5 μm; the corner is marked as an electric field concentration area (red dashed circle); the electric field lines show the electric field concentration phenomenon at the sharp corner.

[0076] The right side of the comparison diagram is a trapezoidal shielding gate structure, the sidewall inclination angle is 80° (less than 90°); the trapezoidal structure is wide at the top and narrow at the bottom: the top is 0.5 μm, and the bottom is about 0.38 μm; the electric field line distribution is more uniform and smooth, eliminating the sharp 90° corner.

[0077] The electric field line distribution is more uniform and smooth, the electric field distribution is more uniform, the overlapping area of the shielding gate and the control gate is reduced, and the gate charge is effectively reduced.

[0078] Preferably, the step S24 comprises:

[0079] The maximum electric field strength of the rectangular shielding gate in the corner area is calculated, which is set as a reference value, the trapezoidal angle parameter set is superimposed and analyzed with the electric field strength distribution diagram, the ratio of the electric field strength at each angle to the reference value is identified, and the electric field strength reduction percentage is obtained;

[0080] A curve graph is drawn with the electric field strength reduction percentage as the ordinate and the angle value of the trapezoidal angle parameter set as the abscissa, the change of the curve slope is analyzed, the inflection point angle with the maximum change slope of the electric field strength reduction rate is determined, and the inflection point angle is taken as the electric field modulation efficiency angle;

[0081] When the angle value decreases from 90° to the electric field modulation efficiency angle, the electric field strength reduction rate shows an accelerating trend;

[0082] When the angle value is less than the electric field modulation efficiency angle, the electric field strength reduction rate tends to be flat, and the process complexity significantly increases.

[0083] In one implementation manner of the embodiment of the present application, first, the maximum electric field strength of the rectangular shielding gate (the sidewall inclination angle is 90°) in the corner area is calculated, which is assumed to be V / cm, which is taken as a reference value. Then, for each angle value in the trapezoidal angle parameter set, the ratio of its corresponding maximum electric field strength to the reference value is calculated to obtain the percentage of electric field strength reduction. For example, when the angle is 85°, the maximum electric field strength is

[0084] V / cm, and the percentage of reduction is (3.5-2.8) / 3.5x100%=20%.

[0085] When the angle is 80°, the maximum electric field strength is V / cm, and the percentage of reduction is (3.5-2.3) / 3.5x100%=34%.

[0086] When the angle is 75°, the maximum electric field strength is V / cm, and the percentage of reduction is (3.5-2.1) / 3.5x100%=40%.

[0087] In another implementation of the embodiment of the present application, a curve is plotted with the percentage of electric field strength reduction as the ordinate and the angle value in the trapezoidal angle parameter set as the abscissa. By analyzing the change of the slope of the curve, the inflection point angle with the maximum slope of the electric field strength reduction rate is determined. For example, the curve analysis shows that when the angle decreases from 90° to 83°, the electric field strength reduction rate shows an accelerating trend; when the angle is less than 83°, the electric field strength reduction rate tends to be flat. Therefore, 83° is determined as the electric field modulation efficiency angle.

[0088] In another implementation of the embodiment of the present application, when the angle value decreases from 90° to the electric field modulation efficiency angle (such as 83°), the electric field strength reduction rate shows an accelerating trend. This indicates that in this angle range, reducing the sidewall inclination angle has a significant effect on reducing the electric field strength. For example, when the angle decreases from 90° to 87°, the electric field strength is reduced by 10%; and when the angle decreases from 87° to 84°, the electric field strength is reduced by 15%, and the reduction rate accelerates.

[0089] In another implementation of the embodiment of the present application, when the angle value is less than the electric field modulation efficiency angle (such as 83°), the electric field strength reduction rate tends to be flat, while the process complexity increases significantly. For example, when the angle decreases from 83° to 80°, the electric field strength is only reduced by 5%; and when the angle decreases from 80° to 77°, the electric field strength is only reduced by 3%. At the same time, the smaller the angle, the higher the difficulty and complexity of the etching process, resulting in increased manufacturing cost and decreased yield. Therefore, in practical applications, it is necessary to find a balance between the electric field reduction effect and the process complexity.

[0090] Preferably, the step S3 comprises the following steps:

[0091] ​Step S31: calculating the actual overlapping area of the shielding gate and the control gate in the trench according to the trapezoidal angle parameter set, and generating a gate overlapping area table by combining the area reduction effect caused by the sidewall inclination angle;

[0092] In the embodiment of the present application, the actual overlapping area of the shielding gate and the control gate in the trench is calculated based on the trapezoidal angle parameter set defined in step S2. Due to the characteristics of the trapezoidal structure that the upper part is wide and the lower part is narrow, the sidewall angle inclination will cause the overlapping area to decrease, thereby affecting the gate charge. By accurately calculating the overlapping area change under different angles, the gate overlapping area table is generated.

[0093] In one implementation manner of the embodiment of the present application, it is assumed that under the rectangular shielding gate structure (the sidewall inclination angle is 90°), the overlapping area of the shielding gate and the control gate is 0.25 μm When the sidewall inclination angle is 85°, the overlapping area is reduced to 0.21 μm , reduced by 16%; when the sidewall inclination angle is 80°, the overlapping area is reduced to 0.18 μm , reduced by 28%; when the sidewall inclination angle is 75°, the overlapping area is reduced to 0.15 μm , reduced by 40%. These data are recorded in the gate overlapping area table, providing a basis for subsequent analysis.

[0094] Step S32: calculating the gate-shielding gate capacitance value under different trapezoidal angles by using the piecewise integration method, and generating gate capacitance distribution data;

[0095] In the embodiment of the present application, the gate-shielding gate capacitance value under different trapezoidal angles is calculated by using the piecewise integration method based on the gate overlapping area table obtained in step S31. Due to the change of the overlapping area, the capacitance value will also change accordingly, thereby affecting the gate charge. By accurate calculation, the gate capacitance distribution data is generated.

[0096] In one implementation manner of the embodiment of the present application, it is assumed that under the rectangular shielding gate structure, the gate-shielding gate capacitance value is 100 pF. By the piecewise integration method, it is calculated that when the sidewall inclination angle is 85°, the capacitance value is reduced to 84 pF, reduced by 16%; when the sidewall inclination angle is 80°, the capacitance value is reduced to 72 pF, reduced by 28%; when the sidewall inclination angle is 75°, the capacitance value is reduced to 60 pF, reduced by 40%. These data constitute the gate capacitance distribution data, which directly shows the influence of the trapezoidal angle on the gate capacitance.

[0097] Step S33: calculating the gate charge reduction ratio of the trapezoidal structure, analyzing the charge optimization effect, and generating a gate charge optimization rate.

[0098] In the embodiment of the present application, based on the gate capacitance distribution data obtained in step S32, the gate charge reduction ratio of the trapezoidal structure relative to the rectangular shield gate structure is calculated. The gate charge is proportional to the gate capacitance, so the reduction of the capacitance directly reflects the reduction of the charge. By analyzing the charge optimization effect, the gate charge optimization rate is generated.

[0099] In one implementation of the embodiment of the present application, the gate charge reduction ratio is the same as the gate capacitance reduction ratio. When the sidewall inclination angle is 85°, the gate charge is reduced by 16%; when the sidewall inclination angle is 80°, the gate charge is reduced by 28%; and when the sidewall inclination angle is 75°, the gate charge is reduced by 40%. These data constitute the gate charge optimization rate, which is used to evaluate the improvement effect of the trapezoidal structure on the switching performance.

[0100] Preferably, the step S33 comprises:

[0101] The data in the gate overlap area table is grouped according to the trapezoidal angle, and the percentage of the reduction of the overlap area at each angle value in the trapezoidal angle parameter set is calculated based on the structure overlap area of the rectangular shield gate as the reference value.

[0102] A functional relationship between the angle and the overlap area reduction rate is established with the angle as the horizontal coordinate and the overlap area reduction percentage as the vertical coordinate, and a charge optimization curve is obtained.

[0103] The charge optimization curve and the angle-electric field response curve are superimposed in the same coordinate system, the intersection region of the two curves is analyzed, and the intersection angle range near the intersection point of the two curves is determined.

[0104] Within the intersection angle range, the angle is subdivided by 0.5° as the step, the electric field intensity and the gate charge are repeatedly calculated, the comprehensive performance index is defined as the weighted sum of the electric field reduction percentage and the charge reduction percentage, and the optimal trapezoidal angle is determined within the intersection angle range.

[0105] In one implementation of the embodiment of the present application, first, the data in the gate overlap area table is grouped according to the trapezoidal angle. The overlap area of the rectangular shield gate (the sidewall inclination angle is 90°) is 0.25 μm as the reference value, and the percentage of the reduction of the overlap area at each angle is calculated. For example, when the angle is 85°, the overlap area is reduced by 16%; when the angle is 80°, the overlap area is reduced by 28%; and when the angle is 75°, the overlap area is reduced by 40%.

[0106] In another implementation of the embodiment of the present application, the function relationship between the angle and the reduction rate of the overlapping area is established by taking the angle as the horizontal coordinate and the reduction rate of the overlapping area as the vertical coordinate, to obtain a charge optimization curve. Meanwhile, the charge optimization curve and the angle-field response curve obtained in step S24 are superimposed in the same coordinate system, and the intersection region of the two curves is analyzed. For example, the two curves intersect or are close to each other in the angle range of 83°-85°, and this interval is determined as the intersection angle range.

[0107] In another implementation of the embodiment of the present application, the angle is subdivided by 0.5° in the determined intersection angle range (such as 83°-85°), and the field intensity and the gate charge are repeatedly calculated. The comprehensive performance index is defined as the weighted sum of the field reduction percentage and the charge reduction percentage, for example: comprehensive performance index = 0.6 × field reduction percentage + 0.4 × charge reduction percentage. The comprehensive performance index of each subdivided angle in the intersection angle range is calculated to determine the optimal trapezoidal angle. For example, it is found through calculation that the angle of 84.5° has the highest comprehensive performance index, and therefore 84.5° is determined as the optimal trapezoidal angle.

[0108] Preferably, step S4 comprises the following steps:

[0109] Step S41: screening the process angle range based on the gate charge optimization rate and the angle control parameter to generate a process feasible angle interval;

[0110] In the embodiment of the present application, the process feasible angle interval is generated by screening the process angle range based on the gate charge optimization rate and the optimal trapezoidal angle obtained in step S3 and in combination with the angle control parameter of the etching equipment. This step combines the theoretically optimal angle with the actual process capability to ensure the implementability of the design scheme.

[0111] In one implementation of the embodiment of the present application, it is assumed that the theoretically calculated optimal trapezoidal angle is 84.5°, and the angle control accuracy of the etching equipment is ±1°. Considering the process fluctuation and the equipment capability, the process feasible angle interval is determined as 83.5°-85.5°. In this interval, the etching process can stably achieve the target angle while maintaining good field reduction effect and gate charge optimization effect.

[0112] Step S42: adjusting the gas ratio, power, pressure and time parameters of the reactive ion etching parameters for the target angle to generate an angle etching recipe table;

[0113] In the embodiment of the present application, the angle etching recipe table is generated by adjusting the reactive ion etching parameters, including the gas ratio, power, pressure and time parameters, for the determined target angle (such as 84.5°). By accurately controlling these parameters, the side wall inclination angle is accurately controlled.

[0114] In one implementation of the embodiment of the present application, the influence of each etching parameter on the sidewall angle is systematically studied through orthogonal experimental design. For example, increasing the ratio of and can make the sidewall angle closer to 90°, while decreasing the ratio makes the angle smaller; increasing the RF power can improve the anisotropy of etching, making the sidewall steeper; increasing the cavity pressure makes the etching more isotropic, and the sidewall angle is smaller. By adjusting the combination of these parameters, the best formula for stably achieving a 84.5° sidewall angle is found, and an angle etching formula table is generated.

[0115] Step S43: Integrate the best trapezoidal angle, the process feasible angle interval and the angle etching formula table to generate a trapezoidal shield gate process scheme.

[0116] In the embodiment of the present application, the process feasible angle interval obtained in step S41 and the angle etching formula table obtained in step S42 are integrated to generate a complete trapezoidal shield gate process scheme in combination with the best trapezoidal angle. The scheme includes target angle, allowable deviation range, etching parameter formula and quality control requirements, etc.

[0117] In one implementation of the embodiment of the present application, the trapezoidal shield gate process scheme includes the following contents: the target trapezoidal angle is 84.5°, the allowable deviation range is ±1°; the etching gas ratio is : 8:2, the RF power is 500W, the cavity pressure is 50mTorr, and the etching time is 60 seconds; the quality control requirements include angle measurement frequency, acceptance standard and abnormal handling process, etc. This process scheme provides complete technical guidance for the actual manufacture of trapezoidal shield gate structure.

[0118] Preferably, the step S43 includes:

[0119] Performing etching process verification on each angle of the process feasible angle interval to obtain etching parameters; using the best trapezoidal angle as the target angle, measuring the deviation angle between the actually formed trapezoidal angle and the target angle to obtain a measurement result;

[0120] According to the measurement result, establishing etching correction parameters of the deviation angle and the etching parameters, and automatically adjusting the etching parameters for the next time according to the etching correction parameters to form a closed-loop control mechanism;

[0121] Setting real-time monitoring points in the etching process to collect key process parameters, including gas flow, RF power, cavity pressure and substrate temperature, to form real-time monitoring parameters;

[0122] Correspondence between real-time monitoring parameters and the formation quality of each angle in the process feasible angle interval is established, and a parameter-angle mapping model is constructed.

[0123] Based on the parameter-angle mapping model, an online quality prediction model is established.

[0124] When the angle deviation is detected to be out of the preset range, the process parameter correction is automatically triggered.

[0125] In one implementation of the embodiment of the present application, for the angles in the process feasible angle interval (such as 83.5°-85.5°), a point is selected every 0.5° for etching process verification, and the etching parameter combination corresponding to each angle is obtained. Using the best trapezoidal angle 84.5° as the target angle, multiple etching experiments are performed, and the deviation of the actual formed trapezoidal angle from the target angle is measured. For example, under the same etching parameters, the actual angles measured are 84.3°, 84.7°, 84.2°, and the deviation angles are -0.2°, +0.2°, -0.3°, respectively.

[0126] In another implementation of the embodiment of the present application, according to the measurement results, a relationship model of the deviation angle and the etching parameters is established. For example, it is found that when the radio frequency power is increased by 10W, the side wall angle is increased by an average of 0.3°; when the gas ratio is increased by 5%, the side wall angle is increased by an average of 0.2°. Based on these relationships, an etching correction parameter table is established for automatically adjusting the etching parameters next time. A closed-loop control mechanism is formed to automatically adjust the etching parameters of the next batch according to the angle measurement results of the last batch.

[0127] In another implementation of the embodiment of the present application, real-time monitoring points are set in the etching process to collect key process parameters, including gas flow, radio frequency power, cavity pressure and substrate temperature. For example, the actual values of radio frequency power and cavity pressure are recorded every 10 seconds to form a real-time monitoring parameter sequence. By analyzing the relationship between these parameters and the finally formed side wall angle, a parameter-angle mapping model is constructed.

[0128] In another implementation of the embodiment of the present application, based on the parameter-angle mapping model, an online quality prediction model is established. This model can predict the finally formed side wall angle according to the real-time monitoring parameters, and realize real-time monitoring of the trapezoidal shielding gate shape. For example, when the radio frequency power fluctuation is detected to be more than 5%, the model predicts that the side wall angle deviates from the target value by 0.4°, triggering a warning signal. When the angle deviation is detected to be out of the preset range (such as ±0.5°), the system automatically triggers the process parameter correction, such as adjusting the radio frequency power or the gas ratio.

[0129] Preferably, step S5 comprises the following steps:

[0130] ​Step S51: Based on the same device structure parameters and the trapezoidal shield gate process scheme, the key parameters of the breakdown voltage, the on-resistance, the gate charge and the switching time of the trapezoidal shield gate and the rectangular shield gate are measured, and a double-structure parameter comparison table is generated;

[0131] In the embodiment of the application, in order to objectively evaluate the performance advantage of the trapezoidal shield gate structure, based on the same device structure parameters (such as trench depth, width, doping concentration, etc.) and the trapezoidal shield gate process scheme obtained in step S4, the trapezoidal shield gate and the traditional rectangular shield gate samples are manufactured. The key electrical parameters of the two structures are measured, including breakdown voltage, on-resistance, gate charge and switching time, etc., and a double-structure parameter comparison table is generated.

[0132] In one implementation manner of the embodiment of the application, the measurement results show that the breakdown voltage of the trapezoidal shield gate structure (with a side wall angle of 84.5°) is 720V, while the breakdown voltage of the rectangular shield gate structure is 600V; the on-resistance of the trapezoidal structure is 3.2mΩ·cm , and the on-resistance of the rectangular shield gate structure is 3.3mΩ·cm ; the gate charge of the trapezoidal structure is 85nC, and the gate charge of the rectangular shield gate structure is 100nC; the switching time of the trapezoidal structure is 35ns, and the switching time of the rectangular shield gate structure is 40ns. These data are recorded in the double-structure parameter comparison table, which provides a basis for performance evaluation.

[0133] Step S52: Calculate the improvement percentage of the trapezoidal structure relative to the rectangular structure of the rectangular shield gate in each performance index, including three core indexes of breakdown voltage improvement rate, gate charge reduction rate and switching loss reduction rate, and generate a performance improvement index diagram;

[0134] In the embodiment of the application, based on the double-structure parameter comparison table obtained in step S51, the improvement percentage of the trapezoidal structure relative to the rectangular structure in each performance index is calculated. The three core indexes of breakdown voltage improvement rate, gate charge reduction rate and switching loss reduction rate are focused on, and a performance improvement index diagram is generated.

[0135] In one implementation manner of the embodiment of the application, according to the measurement data, it is calculated that:

[0136] The breakdown voltage improvement rate of the trapezoidal shield gate structure is (720V-600V) / 600V×100%=20%;

[0137] The gate charge reduction rate is (100nC-85nC) / 100nC×100%=15%;

[0138] The switching loss reduction rate is (40ns-35ns) / 40ns×100%=12.5%.

[0139] The three core indicators constitute a performance improvement index diagram of the ladder-shaped shielding gate structure, and intuitively show the comprehensive advantages of the ladder-shaped structure relative to the traditional rectangular structure.

[0140] Step S53: According to the performance improvement index diagram, comprehensive analysis is performed, the input-output ratio is calculated, the overall application value of the ladder-shaped shielding gate trench structure is evaluated, and a structure optimization benefit report is generated.

[0141] In the embodiment of the present application, based on the performance improvement index diagram obtained in step S52, comprehensive analysis is performed. Considering the additional process cost and time required for the implementation of the ladder-shaped structure, the input-output ratio is calculated, the overall application value of the ladder-shaped shielding gate trench structure is comprehensively evaluated, and a structure optimization benefit report is generated.

[0142] In one implementation manner of the embodiment of the present application, the additional process cost required for the implementation of the ladder-shaped shielding gate structure mainly includes the cost of etching parameter optimization and angle control, and it is estimated that the manufacturing cost is increased by about 3%. The performance improvement index diagram shows that the ladder-shaped structure is improved by 20%, 15% and 12.5% in the core indicators of breakdown voltage, gate charge and switching loss, respectively. The input-output ratio is calculated as (20%+15%+12.5%) / 3 / 3%≈5.3, which indicates that for every 1% increase in manufacturing cost, about 5.3% of comprehensive performance improvement can be obtained. This high input-output ratio proves that the ladder-shaped shielding gate structure has significant application value. The structure optimization benefit report also includes performance advantage analysis of the ladder-shaped structure in different application scenarios, as well as evaluation results of long-term reliability and thermal stability, which provides comprehensive support for product design decision.

[0143] The embodiment of the present application also provides a modeling system of a shielding gate trench MOSFET, which is used to execute the above-mentioned modeling method of the shielding gate trench MOSFET, and the modeling system of the shielding gate trench MOSFET comprises:

[0144] An electric field distribution analysis module is configured to select characteristic point key positions of the shielding gate trench structure, wherein the characteristic point key positions include corners, edges and centers, calculate the electric field intensity of the characteristic point key positions through two-dimensional simulation, and generate an electric field intensity distribution diagram;

[0145] A ladder-shaped structure optimization module is configured to define a set of ladder-shaped angle parameters based on the electric field intensity distribution diagram, design the shape of the shielding gate as a ladder-shaped structure with a wide upper part and a narrow lower part, model and establish a quantitative relationship between the side wall inclination angle and the electric field intensity of the trench corner, and generate an angle-electric field response curve;

[0146] A gate charge balance module is configured to calculate the change of the overlap area between the shielding gate and the control gate in the trench of different ladder-shaped structures by using the angle-electric field response curve, and generate a gate charge optimization rate and an optimal ladder-shaped angle;

[0147] The process parameter conversion module is configured to acquire angle control parameters and reactive ion etching parameters of an etching device, and generate a trapezoidal shield gate process scheme by realizing a target structure through adaptive control of etching conditions based on a gate charge optimization rate and in combination with angle control capability parameters of a semiconductor etching process.

[0148] The performance comparison and evaluation module is configured to compare performance differences between the trapezoidal shield gate designed by the trapezoidal shield gate process scheme and a preset rectangular shield gate, measure a breakdown voltage improvement amplitude, a switch loss reduction ratio and a thermal distribution improvement degree, and generate a structure optimization benefit report.

[0149] In one implementation manner of the embodiment of the present application, the electric field distribution analysis module comprises a feature point positioning unit, an electric field calculation unit and a distribution map generation unit. The feature point positioning unit is configured to position feature points sensitive to electric field distribution in the shield gate trench structure; the electric field calculation unit is configured to calculate electric field intensity of the feature points under a preset bias condition; and the distribution map generation unit is configured to connect electric field values of the feature points to form a continuous electric field distribution representation and generate an electric field intensity distribution map.

[0150] In another implementation manner of the embodiment of the present application, the trapezoidal structure optimization module comprises an angle parameter setting unit, a position mapping unit, a geometric modeling unit and a response curve generation unit. The angle parameter setting unit is configured to define a set of trapezoidal sidewall inclination angle parameters; the position mapping unit is configured to calculate position coordinates of the feature points under different angles; the geometric modeling unit is configured to construct a geometric shape model of the shield gate; and the response curve generation unit is configured to calculate electric field intensity under different trapezoidal angles and generate an angle-electric field response curve.

[0151] In another implementation manner of the embodiment of the present application, the gate charge balance module comprises an overlapping area calculation unit, a capacitance distribution unit and a charge optimization unit. The overlapping area calculation unit is configured to calculate overlapping areas of the shield gate and the control gate under different trapezoidal angles; the capacitance distribution unit is configured to calculate gate-shield gate capacitance values; and the charge optimization unit is configured to analyze charge optimization effects and determine an optimal trapezoidal angle.

[0152] In another implementation manner of the embodiment of the present application, the process parameter conversion module comprises an angle range screening unit, an etching parameter adjustment unit and a process scheme generation unit. The angle range screening unit is configured to determine a process feasible angle interval; the etching parameter adjustment unit is configured to adjust etching parameters for a target angle; and the process scheme generation unit is configured to integrate the optimal trapezoidal angle and the etching parameters to generate a complete process scheme.

[0153] In another implementation form of the embodiment of the present application, the performance comparison evaluation module comprises a parameter measurement unit, an improvement index calculation unit and a benefit analysis unit. The parameter measurement unit is configured to measure the electrical parameters of the trapezoidal shielding grid and the rectangular shielding grid; the improvement index calculation unit is configured to calculate the improvement percentage of each performance index; and the benefit analysis unit is configured to evaluate the overall application value of the trapezoidal structure and generate a structure optimization benefit report.

[0154] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application being defined by the appended claims and not by the above description, and it is intended to include all the variations falling within the meaning and the scope of the equivalent elements of the application file.

[0155] The foregoing is considered only as illustrative of the principles of the application, and the application is to be limited only by the scope of the appended claims. Numerous modifications to these embodiments will be readily apparent to those skilled in the art, and the principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the application is not to be limited to only the embodiments shown herein and it is intended to cover all alternatives falling within the spirit and scope of the application.

Claims

1. A modeling method for a shielded gate trench MOSFET, characterized in that, Applied to power semiconductor device design, it includes the following steps: Step S1: Select key feature points of the shielding grid trench structure, including corners, edges and centers. Calculate the electric field intensity at the key feature points using two-dimensional simulation to generate an electric field intensity distribution map. Step S2: Based on the electric field intensity distribution map, the shape of the shielding grid is designed as a trapezoidal structure that is wider at the top and narrower at the bottom by defining a trapezoidal angle parameter set. A quantitative relationship between the sidewall tilt angle and the electric field intensity at the trench corner is modeled and established, generating an angle-electric field response curve. Step S2 includes the following steps: Step S21: Define the inclination angle of the trapezoidal sidewall, set five different angle variable values ​​of 75°, 80°, 85°, 87° and 89°, keep the top width of the shielding grid unchanged, and generate the trapezoidal angle parameter set; Step S22: For each trapezoidal angle parameter in the trapezoidal angle parameter set, calculate the position coordinates corresponding to the feature points and generate an angle adjustment position mapping table; Step S23: Construct the geometric model of the shielding fence according to the angle adjustment position mapping table; Step S24: Based on the geometric shape model, recalculate the electric field intensity of each feature point under different trapezoidal angles, establish the functional relationship between the angle and the maximum electric field intensity in the corner region, and generate the angle-electric field response curve; Step S3: Using the angle-electric field response curve, calculate the change in overlap area between the shielding gate and the control gate in the trench for different trapezoidal structures, and generate the gate charge optimization rate and the optimal trapezoidal angle; Step S3 includes the following steps: Step S31: Calculate the actual overlap area of ​​the shielding gate and the control gate in the trench based on the trapezoidal angle parameter set, and analyze the area reduction effect caused by the tilt angle of the sidewall to generate a gate overlap area table. Step S32: Calculate the gate-shield inter-gate capacitance value under different trapezoidal angles to generate gate capacitance distribution data; Step S33: Calculate the gate charge reduction ratio of the trapezoidal structure, analyze the charge optimization effect, and generate the gate charge optimization rate; wherein, step S33 includes: The data in the gate overlap area table are grouped by trapezoidal angle. Using the structural overlap area of ​​the rectangular shield gate as the baseline value, the percentage reduction in overlap area for each angle value in the trapezoidal angle parameter set is calculated. By establishing a functional relationship between angle and the rate of reduction of overlapping area with angle as the horizontal axis and percentage reduction of overlapping area as the vertical axis, the charge optimization curve is obtained. The charge optimization curve and the angle-electric field response curve are superimposed in the same coordinate system. The intersection region of the two curves is analyzed to determine the range of the intersection angle near the intersection point of the two curves. Within the intersection angle range, the angle is subdivided in 0.5° increments, and the electric field strength and gate charge are repeatedly calculated. The comprehensive performance index is defined as the weighted sum of the percentage reduction in electric field and the percentage reduction in charge. The optimal trapezoidal angle is determined within the intersection angle range. Step S4: Obtain the angle control parameters and reactive ion etching parameters of the etching equipment. Based on the gate charge optimization rate and combined with the angle control capability parameters of the semiconductor etching process, the target structure is achieved by adaptively controlling the etching conditions, and a trapezoidal shielding gate process scheme is generated. Step S5: Compare the performance differences between the trapezoidal shielding grid designed in the trapezoidal shielding grid process scheme and the preset rectangular shielding grid, measure the breakdown voltage increase, the reduction ratio of switching loss and the degree of improvement of heat distribution, and generate a structural optimization benefit report.

2. The modeling method for a shielded gate trench MOSFET according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Locate the electric field distribution sensitive feature points in the shielding grid trench structure, including the bottom 90° corner point, the midpoint of the side wall, the top transition zone, and the boundary point of the depletion zone, record their spatial coordinates, and generate a table of electric field feature point locations; Step S12: Calculate the electric field intensity vector and potential gradient under the preset bias conditions for the electric field feature point location table, record the electric field intensity value and direction, and generate the feature point electric field intensity table. Step S13: Connect the electric field values ​​of each feature point to form a continuous electric field distribution representation, identify the region where the electric field intensity exceeds the preset critical value, and generate an electric field intensity distribution map.

3. The modeling method for a shielded gate trench MOSFET according to claim 1, characterized in that, Step S24 includes: Calculate the maximum electric field intensity of the rectangular shielding grid in the corner region and set it as the reference value. Overlay the trapezoidal angle parameter set with the electric field intensity distribution map for analysis, identify the ratio of the electric field intensity at each angle to the reference value, and obtain the percentage reduction in electric field intensity. Plot a curve with the percentage reduction in electric field intensity as the vertical axis and the angle values ​​of the trapezoidal angle parameter set as the horizontal axis. Analyze the changes in the slope of the curve, determine the inflection point angle with the largest slope of the change in electric field intensity reduction rate, and take the inflection point angle as the electric field modulation efficiency angle. When the angle value decreases from 90° to the electric field modulation efficiency angle, the rate of decrease in electric field strength shows an accelerating trend. When the angle value is smaller than the electric field modulation efficiency angle, the rate of decrease in electric field strength tends to level off, while the process complexity increases significantly.

4. The modeling method for a shielded gate trench MOSFET according to claim 1, characterized in that, Step S4 includes the following steps: Step S41: Based on the gate charge optimization rate and combined with the angle control parameters, screen the process angle range and generate a process feasible angle interval; Step S42: For the target angle, adjust the gas ratio, power, pressure and time parameters of the reactive ion etching parameters to generate an angle etching formula table; Step S43: Integrate the optimal trapezoidal angle, the process-feasible angle range, and the angle etching formula table to generate a trapezoidal shielding grid process scheme.

5. The modeling method for a shielded gate trench MOSFET according to claim 4, characterized in that, Step S43 includes: The etching process was verified for each angle within the feasible angle range to obtain etching parameters; the optimal trapezoidal angle was used as the target angle, and the deviation angle between the actual formed trapezoidal angle and the target angle was measured to obtain the measurement results; Based on the measurement results, etching correction parameters for the deviation angle and etching parameters are established. The etching parameters for the next etching are automatically adjusted based on the etching correction parameters, forming a closed-loop control mechanism. Set up real-time monitoring points during the etching process to collect key process parameters, including gas flow rate, RF power, cavity pressure and substrate temperature, to form real-time monitoring parameters; Establish a correspondence between real-time monitoring parameters and the formation quality of each angle in the feasible angle range of the process, and construct a parameter-angle mapping model; An online quality prediction model is established based on the parameter-angle mapping model. When an angular deviation is detected to exceed the preset range, the process parameters are automatically corrected.

6. The modeling method for a shielded gate trench MOSFET according to claim 1, characterized in that, Step S5 includes the following steps: Step S51: Based on the same device structure parameters and trapezoidal shielding gate process scheme, measure the key parameters in the breakdown voltage, on-resistance, gate charge and switching time of the trapezoidal shielding gate and the rectangular shielding gate, and generate a dual-structure parameter comparison table; Step S52: Calculate the percentage improvement of the trapezoidal structure over the rectangular structure of the rectangular shielding gate in various performance indicators, including the three core indicators of breakdown voltage improvement rate, gate charge reduction rate, and switching loss reduction rate, and generate a performance improvement index chart. Step S53: Based on the performance improvement index chart, conduct a comprehensive analysis, calculate the input-output ratio, evaluate the overall application value of the trapezoidal shielding grid trench structure, and generate a structural optimization benefit report.

7. A modeling system for shielded gate trench MOSFETs, characterized in that, A modeling system for performing the modeling method for a shielded gate trench MOSFET as described in claim 1, the modeling system for the shielded gate trench MOSFET comprising: The electric field distribution analysis module is used to select key locations of feature points in the shielding grid trench structure. These key locations include corners, edges, and the center. The module calculates the electric field intensity at these key locations through two-dimensional simulation and generates an electric field intensity distribution map. The trapezoidal structure optimization module is used to design the shape of the shielding grid into a trapezoidal structure that is wider at the top and narrower at the bottom by defining a trapezoidal angle parameter set based on the electric field intensity distribution map. It models and establishes a quantitative relationship between the side wall tilt angle and the electric field intensity at the trench corner, and generates an angle-electric field response curve. The gate charge balance module is used to calculate the change in the overlap area between the shield gate and the control gate with different trapezoidal structures in the trench using the angle-electric field response curve, and to generate the gate charge optimization rate and the optimal trapezoidal angle. The process parameter conversion module is used to obtain the angle control parameters and reactive ion etching parameters of the etching equipment. Based on the gate charge optimization rate and combined with the angle control capability parameters of the semiconductor etching process, the target structure is achieved by adaptively controlling the etching conditions, and a trapezoidal shielding gate process scheme is generated. The performance comparison and evaluation module is used to compare the performance differences between the trapezoidal shielding grid designed by the trapezoidal shielding grid process scheme and the preset rectangular shielding grid, measure the breakdown voltage increase, the reduction ratio of switching loss and the degree of heat distribution improvement, and generate a structural optimization benefit report.

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