4H-SiC SBD device structure parameter and working voltage prediction model

Abstract

The invention relates to the field of semiconductors, and discloses a 4H-SiC SBD device structure parameter and working voltage prediction model, which comprises the following steps: calculating based on a theoretical formula related to 4H-SiC breakdown characteristics, and determining the device structure parameter; an adaptive physical model is selected, simulation software is used for calculating electrical characteristics, and structural parameters are adjusted according to a working principle to obtain an optimal optimization scheme; obtaining an optimal simulation physical model according to process tape-out and chip test data; and in combination with an on-resistance calculation formula and a tape-out test result, completing consistency verification of simulation of chips of different specifications and tape-out data, and establishing a relation prediction model of structural parameters and working voltage of a chip of a target specification. According to the method, the forward working voltage of the SiC SBD devices of different specifications is predicted and analyzed by establishing the prediction model combining the structural parameters and the on resistance, the process tape-out period is shortened, the process cost is reduced, and the research and development efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more particularly to a predictive model for the structural parameters and operating voltage of a 4H-SiC SBD device. Background Technology

[0002] With the emergence, improvement, and refinement of new semiconductor devices, my country's electronics industry technology is developing rapidly. However, behind this is increasingly fierce competition within the semiconductor industry. This intensifying market competition will inevitably accelerate the upgrading and iteration of semiconductor chips, which will continuously compress the time for project research and development, gradually turning it into a race against time.

[0003] Currently, semiconductor-related equipment is expensive and raw material investment is huge. Simply experimenting with semiconductor chips would result in a massive waste of human, material, and financial resources, putting immense pressure on the entire semiconductor industry. Therefore, it is particularly important to develop efficient products within a short R&D cycle and at a lower cost to seize market opportunities. This necessitates a physical model capable of accurately predicting the manufacturing process of devices with different specifications to guide production. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a predictive model for the structural parameters and operating voltage of a 4H-SiC SBD device, so as to achieve predictability of semiconductor device production results.

[0005] To achieve the aforementioned objectives, the technical solution adopted is as follows: A predictive model for the structural parameters and operating voltage of a 4H-SiC SBD device includes the following steps: S1. Preliminary design: Based on the theoretical formulas related to the breakdown characteristics of 4H-SiC, determine the structural parameters corresponding to the target device specification 4H-SiC SBD device. S2. Based on the target structural parameters, select a suitable physical model, use simulation software to calculate the electrical characteristics, and adjust the structural parameters according to the working principle to obtain the best optimization scheme. S3. Based on the optimized scheme, the process fabrication is carried out, and the simulation physical model that best matches the process fabrication is obtained based on the feedback results of chip test data. S4. Based on this simulation physical model, combined with the on-resistance calculation formula and the chip fabrication test results, complete the consistency verification of simulation and fabrication data for chips of different specifications, and establish a predictive model of the relationship between structural parameters and the operating voltage of the target specification chip.

[0006] As a further improvement of the present invention, in step S1, the specific steps for calculating and determining the structural parameters corresponding to the target device specification 4H-SiC SBD device based on the theoretical formula related to the breakdown characteristics of 4H-SiC are as follows: S1-1. Based on the 4H-SiC SBD breakdown mechanism, the critical avalanche breakdown electric field and breakdown voltage of 4H-SiC material based on the punch-through structure were obtained according to the structural parameter values ​​of the preliminary design. S1-2. Based on the 4H-SiC SBD breakdown mechanism, the concentration of ionized donor impurities, the built-in potential difference of the PN junction, and the width of the depletion region are obtained according to the structural parameter values ​​of the preliminary design. S1-3. Based on the 4H-SiC SBD breakdown mechanism, the field limiting ring structure parameters are obtained according to the target withstand voltage value. S1-4. Based on the breakdown voltage value of the specified terminal efficiency of the target device, adjust the structural parameters to obtain the structural parameters of the 4H-SiC SBD device.

[0007] As a further improvement of the present invention, in step S1-1, the formula for calculating the critical avalanche breakdown electric field of 4H-SiC material based on the punch-through structure is as follows: in, E ( x () represents the critical avalanche breakdown electric field. q For electron charge, E c Based on the critical avalanche breakdown electric field of a non-penetrating structure, N D The doping concentration of the epitaxial layer, ɛ s The relative permittivity of the material is t epi Indicates the thickness of the epitaxial layer; The formula for calculating the ideal one-dimensional breakdown voltage of a 4H-SiC SBD device is as follows: in, E c Based on the critical avalanche breakdown electric field of a non-penetrating structure, t epi Indicates the thickness of the epitaxial layer. q For electron charge, N D The doping concentration of the epitaxial layer, ɛ s is the relative permittivity of the material.

[0008] As a further improvement of the present invention, in step S1-2, the formula for calculating the built-in potential difference of the PN junction for 4H-SiC material is as follows: in, ψ bi For the built-in potential difference of the PN junction, N D The doping concentration of the epitaxial layer, N A for p + Ion implantation concentration, k Boltzmann's constant, T For temperature, n i For SiC, the carrier concentration is as follows: The formula for calculating the width of the depletion region is as follows: in, W D The width of the exhaustion region, ɛ s The relative permittivity of the material is ψ bi For the built-in potential difference of the PN junction, q For electron charge, N The concentration of ionized donor impurities. N D The doping concentration of the epitaxial layer, N A for p + Ion implantation concentration.

[0009] As a further improvement of the present invention, in steps S1-3, the potential distribution obeys the Poisson equation of the cylindrical junction, and its boundary conditions are: , The electric field and potential of the main junction are calculated as follows: Where, r j The depth of the main knot, r d The width of the depletion layer resulting from the electric potential falling across the ends of the cylindrical junction; When a field-limiting loop structure is introduced, the edge voltage of the field-limiting loop is obtained. V i and edge peak electric field E max,Fi The calculation formula is as follows: No. i The formula for calculating the maximum electric field at the edge of each ring is as follows: In the formula, q For electron charge, N D The doping concentration of the epitaxial layer, ε The dielectric constant of the material is ε 0 is the vacuum permittivity. r i This indicates the position of the i-th field-limited loop. r i+1 Indicates the first i +1 field limit loop width, l i+1 This represents the distance between the (i+1)th ring and the main node. r j The knot is deep enough to be the main knot.

[0010] As a further improvement of the present invention, in steps S1-4, the structural parameters include the doping concentration and thickness of the epitaxial layer in the source region, the width and spacing of the field confinement ring, the junction depth, and... p + Ion implantation concentration.

[0011] As a further improvement of the present invention, in step S2, the simulation software used is one or more of Sentaurus TCAD, SPICE or Silvaco TCAD; the electrical characteristics include forward output characteristics, reverse breakdown characteristics, current density and electric field distribution.

[0012] As a further improvement of the present invention, in step S3, the test data includes forward current characteristics and reverse output characteristics.

[0013] As a further improvement of the present invention, in step S3, the simulation physical model that best matches the process fabrication is obtained based on the chip test data feedback results. The specific steps are as follows: the simulation data and the fabrication test data are processed into images, and the simulation physical model is adjusted according to the working principle of 4H-SiC SBD, thereby making the simulation and fabrication data consistent and fitted.

[0014] As a further improvement of the present invention, in step S4, the formula for calculating the on-resistance is as follows: Where ΔV represents the change in voltage and ΔI represents the change in current. l Given the single-sided dimension of the chip, calculate the on-resistance corresponding to the structural parameters of a specific chip; The forward operating voltage of the target device is calculated as follows: in, V th Threshold voltage; V a To compensate for the voltage, it is derived from the difference between the voltage at a certain point on the fixed curve that is tangent to the output characteristic on the x-axis and the threshold voltage.

[0015] The beneficial effects of this invention are: this invention obtains the formula for the relationship between structural parameters and operating voltage and current through calculation, and through verification with the fabrication process, the structural parameters and operating voltage of each specification can be basically consistent. Finally, the operating voltage of the chip can be predicted by changing the structural parameters through simulation. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of the prediction model establishment process of this invention; Figure 2 This is a comparison chart of the simulation results and the fabrication results for a certain specification of output characteristics. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0019] like Figure 1 As shown, a predictive model for the structural parameters and operating voltage of a 4H-SiC SBD device includes the following steps: S1. Preliminary design: Based on theoretical formulas related to the breakdown characteristics of 4H-SiC, the structural parameters corresponding to the target device specification 4H-SiC SBD device are determined. The specific steps are as follows: S1-1. Based on the 4H-SiC SBD breakdown mechanism, the critical avalanche breakdown electric field and breakdown voltage of 4H-SiC material based on the punch-through structure were obtained according to the structural parameter values ​​of the preliminary design. The formula for calculating the critical avalanche breakdown electric field of 4H-SiC material based on the punch-through structure is as follows: in, E ( x () represents the critical avalanche breakdown electric field. q For electron charge, E c Based on the critical avalanche breakdown electric field of a non-penetrating structure, N D The doping concentration of the epitaxial layer, ɛ s The relative permittivity of the material is t epi Indicates the thickness of the epitaxial layer; The formula for calculating the ideal one-dimensional breakdown voltage of a 4H-SiC SBD device is as follows: in, E c Based on the critical avalanche breakdown electric field of a non-penetrating structure, t epi Indicates the thickness of the epitaxial layer. q For electron charge, N D The doping concentration of the epitaxial layer, ɛ s is the relative permittivity of the material.

[0020] S1-2. Based on the 4H-SiC SBD breakdown mechanism, the concentration of ionized donor impurities, the built-in potential difference of the PN junction, and the width of the depletion region are obtained according to the structural parameter values ​​of the preliminary design. The formula for calculating the built-in potential difference of the PN junction in 4H-SiC material is as follows: in, ψ bi For the built-in potential difference of the PN junction, N D The doping concentration of the epitaxial layer, N A for p + Ion implantation concentration, k Boltzmann's constant, T For temperature, n i For SiC, the carrier concentration is as follows: The formula for calculating the width of the depletion region is as follows: in, W D The width of the exhaustion region, ɛ s The relative permittivity of the material is ψ bi For the built-in potential difference of the PN junction, q For electron charge, N The concentration of ionized donor impurities. N D The doping concentration of the epitaxial layer, N A for p + Ion implantation concentration.

[0021] S1-3. Based on the 4H-SiC SBD breakdown mechanism, the field limiting ring structure parameters are obtained according to the target withstand voltage value. The potential distribution obeys the Poisson equation for the cylindrical junction, and its boundary conditions are: , The electric field and potential of the main junction are calculated as follows: Where, r j The depth of the main knot, r d The width of the depletion layer resulting from the electric potential falling across the ends of the cylindrical junction; When a field-limiting loop structure is introduced, the edge voltage of the field-limiting loop is obtained. V i and edge peak electric field E max,Fi The calculation formula is as follows: No. i The formula for calculating the maximum electric field at the edge of each ring is as follows: In the formula, q For electron charge, N D The doping concentration of the epitaxial layer, ε The dielectric constant of the material is ε 0 is the vacuum permittivity. r i This indicates the position of the i-th field-limited loop. r i+1 Indicates the first i +1 field limit loop width, l i+1This represents the distance between the (i+1)th ring and the main node. r j The knot is deep enough to be the main knot.

[0022] S1-4. Based on the breakdown voltage value required for the terminal efficiency of the target device, adjust the structural parameters to obtain the structural parameters of the 4H-SiC SBD device; the structural parameters include the doping concentration and thickness of the source region epitaxial layer, the width and spacing of the field confinement ring, the junction depth, and... p + Ion implantation concentration.

[0023] S2. Based on the physical characteristics of 4H-SiC Schottky diodes, select appropriate physical models, including theoretical models of Schottky contact mechanism, characteristic on-resistance and reverse breakdown voltage of SBD / JBS diodes, etc., and based on the special properties of 4H-SiC materials, establish physical models and related parameters that can accurately describe the changes in the electrical performance of the device with material doping, electric field and other conditions.

[0024] Based on the electrical characteristic data such as output characteristics obtained from simulation, the accuracy of the physical model and related structural parameters is verified.

[0025] After obtaining the simulation results, the structural parameters of the Schottky diode were optimized based on the target specifications and the electrical characteristics of the device, resulting in the final optimized design scheme.

[0026] S3. Based on the final optimized design scheme, the target device is fabricated to obtain the output and transfer characteristics of the SBD device. Based on the fabrication data, the simulation physical model suitable for the production of SBD devices is optimized.

[0027] S4. Based on this simulation physical model, combined with the on-resistance calculation formula and the chip fabrication test results, complete the consistency verification of simulation and fabrication data for chips of different specifications, and establish a predictive model of the relationship between structural parameters and the operating voltage of the target specification chip.

[0028] The formula for calculating on-resistance is as follows: Where ΔV represents the change in voltage and ΔI represents the change in current. l Given the single-sided dimension of the chip, calculate the on-resistance corresponding to the structural parameters of a specific chip; The forward operating voltage of the target device is calculated as follows: in, V th Threshold voltage; V aTo compensate for the voltage, it is derived from the difference between the voltage at a certain point on the fixed curve that is tangent to the output characteristic on the x-axis and the threshold voltage.

[0029] In step S2, the simulation software used is one or more of Sentaurus TCAD, SPICE, or Silvaco TCAD; the electrical characteristics include forward output characteristics, reverse breakdown characteristics, current density, and electric field distribution.

[0030] In step S3, the test data includes forward current characteristics and reverse output characteristics.

[0031] In step S3, based on the feedback results of chip test data, the simulation physical model most suitable for the fabrication process is obtained. The specific steps are as follows: The simulation data and fabrication test data are processed graphically; the simulation physical model is adjusted according to the working principle of 4H-SiC SBD, thereby achieving a consistent fit between the simulation and fabrication data. Figure 2 As shown.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, component splitting or combination, 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 predictive model for the structural parameters and operating voltage of a 4H-SiC SBD device, characterized in that, Includes the following steps: S1. Preliminary design: Based on the theoretical formulas related to the breakdown characteristics of 4H-SiC, determine the structural parameters corresponding to the target device specification 4H-SiCSBD device. S2. Based on the target structural parameters, select a suitable physical model, use simulation software to calculate the electrical characteristics, and adjust the structural parameters according to the working principle to obtain the best optimization scheme. S3. Based on the optimized scheme, the process fabrication is carried out, and the simulation physical model that best matches the process fabrication is obtained based on the feedback results of chip test data. S4. Based on this simulation physical model, combined with the on-resistance calculation formula and the chip fabrication test results, complete the consistency verification of simulation and fabrication data for chips of different specifications, and establish a predictive model of the relationship between structural parameters and the operating voltage of the target specification chip.

2. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 1, characterized in that: In step S1, the specific steps for determining the structural parameters corresponding to the target device specification 4H-SiCSBD device based on the theoretical formulas related to the breakdown characteristics of 4H-SiC are as follows: S1-1. Based on the 4H-SiC SBD breakdown mechanism, the critical avalanche breakdown electric field and breakdown voltage of 4H-SiC material based on the punch-through structure were obtained according to the structural parameter values ​​of the preliminary design. S1-2. Based on the 4H-SiC SBD breakdown mechanism, the concentration of ionized donor impurities, the built-in potential difference of the PN junction, and the width of the depletion region are obtained according to the structural parameter values ​​of the preliminary design. S1-3. Based on the 4H-SiC SBD breakdown mechanism, the field limiting ring structure parameters are obtained according to the target withstand voltage value. S1-4. Based on the breakdown voltage value of the specified terminal efficiency of the target device, adjust the structural parameters to obtain the structural parameters of the 4H-SiC SBD device.

3. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 2, characterized in that: In step S1-1, the formula for calculating the critical avalanche breakdown electric field of 4H-SiC material based on the punch-through structure is as follows: in, E ( x () represents the critical avalanche breakdown electric field. q For electron charge, E c Based on the critical avalanche breakdown electric field of a non-penetrating structure, N D The doping concentration of the epitaxial layer, ɛ s The relative permittivity of the material is t epi Indicates the thickness of the epitaxial layer; The formula for calculating the ideal one-dimensional breakdown voltage of a 4H-SiC SBD device is as follows: in, E c Based on the critical avalanche breakdown electric field of a non-penetrating structure, t epi Indicates the thickness of the epitaxial layer. q For electron charge, N D The doping concentration of the epitaxial layer, ɛ s is the relative permittivity of the material.

4. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 2, characterized in that: In step S1-2, the formula for calculating the built-in potential difference of the PN junction for 4H-SiC material is as follows: in, ψ bi For the built-in potential difference of the PN junction, N D The doping concentration of the epitaxial layer, N A for p + Ion implantation concentration, k Boltzmann's constant, T For temperature, n i For SiC, the carrier concentration is as follows: The formula for calculating the width of the depletion region is as follows: in, W D The width of the exhaustion region, ɛ s The relative permittivity of the material is ψ bi For the built-in potential difference of the PN junction, q For electron charge, N The concentration of ionized donor impurities. N D The doping concentration of the epitaxial layer, N A for p + Ion implantation concentration.

5. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 2, characterized in that, In steps S1-3, the potential distribution obeys the Poisson equation for the cylindrical junction, and its boundary conditions are: , The electric field and potential of the main junction are calculated as follows: Where, r j The depth of the main knot, r d The width of the depletion layer resulting from the electric potential falling across the ends of the cylindrical junction; When a field-limiting loop structure is introduced, the edge voltage of the field-limiting loop is obtained. V i and edge peak electric field E max,Fi The calculation formula is as follows: No. i The formula for calculating the maximum electric field at the edge of each ring is as follows: In the formula, q For electron charge, N D The doping concentration of the epitaxial layer, ε The dielectric constant of the material is ε 0 is the vacuum permittivity. r i This indicates the position of the i-th field-limited loop. r i+1 Indicates the first i +1 field limit loop width, l i+1 This represents the distance between the (i+1)th ring and the main node. r j The knot is deep enough to be the main knot.

6. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 2, characterized in that, In steps S1-4, the structural parameters include the doping concentration and thickness of the epitaxial layer in the source region, the width and spacing of the field confinement rings, the junction depth, and... p + Ion implantation concentration.

7. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 1, characterized in that, In step S2, the simulation software used is one or more of Sentaurus TCAD, SPICE, or Silvaco TCAD; the electrical characteristics include forward output characteristics, reverse breakdown characteristics, current density, and electric field distribution.

8. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 1, characterized in that, In step S3, the test data includes forward current characteristics and reverse output characteristics.

9. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 1, characterized in that, In step S3, based on the feedback results of chip test data, the simulation physical model that best matches the process fabrication is obtained. The specific steps are as follows: the simulation data and the fabrication test data are processed into images, and the simulation physical model is adjusted according to the working principle of 4H-SiC SBD, so that the simulation and fabrication data can be consistently fitted.

10. The prediction model for the structural parameters and operating voltage of a 4H-SiC SBD device according to claim 1, characterized in that, In step S4, the formula for calculating the on-resistance is as follows: Where ΔV represents the change in voltage and ΔI represents the change in current. l Given the single-sided dimension of the chip, calculate the on-resistance corresponding to the structural parameters of a specific chip; The forward operating voltage of the target device is calculated as follows: in, V th Threshold voltage; V a To compensate for the voltage, it is derived from the difference between the voltage at a certain point on the fixed curve that is tangent to the output characteristic on the x-axis and the threshold voltage.

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