Method for predicting low-dose-rate irradiation damage of bipolar device
By establishing a physical model of the structure and defects of bipolar devices and combining simulation and experimental data, a low-dose-rate irradiation damage prediction model was formed, which solved the problem of difficult assessment in the existing technology, realized rapid and quantitative device damage assessment, and supported the rapid development of aerospace missions.
Patent Information
- Application Number
- CN202411367528.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2025-01-14
AI Technical Summary
Existing technologies are insufficient to effectively assess and predict the damage of bipolar devices to low-dose-rate irradiation under high cumulative doses, making existing models unsuitable for assessing the device's ability to withstand high total dose effects and failing to meet the needs of rapidly evolving aerospace missions.
By establishing a structural model and a defect physical model of a bipolar device using simulation software, and combining low-dose-rate irradiation test data, an ionizing radiation damage model is established. Through calibration and verification, a low-dose-rate irradiation damage prediction model is formed, enabling the prediction of device irradiation damage under different cumulative doses.
It enables rapid and quantitative assessment of radiation damage to bipolar devices under low dose rates and different cumulative dose conditions, shortens assessment time, reduces costs, and supports the development of independently controllable radiation-hardened bipolar processes.
Smart Images
Figure CN119312549A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of device radiation damage simulation, and in particular relates to a method for predicting low-dose rate radiation damage of a bipolar device. Background Art
[0002] In 2003, Turflinker et al. reported the results of a five-year space payload experiment, and found that the space radiation environment was a low-dose rate environment with an average dose rate of 0.1mrad(Si) / s to 5mrad(Si) / s. The results of the space-borne bipolar device irradiation experiment were compared with those on the ground. 60 Comparing the irradiation results of Co-γ-ray sources, it was found that the degree of damage in space was comparable to that at a dose rate of 10mrad(Si) / s in ground-based simulation experiments, confirming the existence of the ELDRS effect in bipolar devices in space radiation environments. The generally accepted low-dose rate effect changes with the total dose in the threshold region, linear region, and saturation region, but the latest research has found that device degradation shows an increasing trend under high ionizing doses. This phenomenon causes the existing empirical model to no longer be applicable to the assessment of the ability of bipolar devices to resist high total dose effects. On the other hand, the data obtained from low-dose rate irradiation experiments under high cumulative doses is limited, time-consuming, and costly, and cannot meet the needs of rapidly developing space missions. Therefore, it is urgent to conduct in-depth research on the prediction and assessment of low-dose rate effect damage in bipolar devices.
[0003] Fleedwood et al. first proposed a high-temperature irradiation accelerated evaluation method. T.Carriere et al. further optimized the experimental conditions of high-temperature irradiation (dose rate <1rad(Si) / s) and obtained better evaluation results, but its universality has not been verified. Pease et al. proposed a hydrogen atmosphere irradiation accelerated evaluation technology, which uses the characteristic of defect charges directly fragmenting hydrogen molecules to provide new proton sources to achieve rapid growth of interface trap charges. However, since hydrogen injection changes the initial distribution of hydrogen in the device oxide layer, it cannot truly reflect the hydrogen content of the device, and there are certain limitations in identifying the ELDRS effect. In summary, due to the limitations of irradiation time and research methods, the current low-dose rate effect evaluation research at home and abroad is carried out at the total dose range of 100krad(Si). There are few reports on the ELDRS effect at high cumulative doses (>100krad(Si)), and the research at the physical level is still incomplete. With the rise of emerging research fields such as Mars immigration and deep space exploration, bipolar devices will face a complex environment with higher ionization doses. Therefore, conducting research on radiation damage assessment and prediction methods for bipolar devices under high total doses is of great significance for quickly simulating and understanding the actual situation of device operation in orbit and improving the device reinforcement level. Summary of the invention
[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a method for predicting low-dose rate irradiation damage of bipolar devices.
[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:
[0006] A method for predicting low-dose rate radiation damage of a bipolar device comprises the following steps:
[0007] S1. According to the bipolar device structure and process parameters, a bipolar device structure model is established through simulation software, and the structure model is calibrated based on the measured electrical parameters of the bipolar device;
[0008] S2. Establish a defect physical model through simulation software, and obtain the corresponding relationship between the defect physical model parameters and the cumulative dose through experiments;
[0009] S3. Establish an ionizing radiation damage model by coupling the defect physical model and the bipolar device structure model through simulation software; and calibrate the ionizing radiation damage model in combination with low-dose rate and low cumulative dose irradiation test data to form a low-dose rate irradiation damage prediction model for bipolar devices;
[0010] S4. Based on the low-dose rate radiation damage prediction model of bipolar devices, electrical parameter simulation under different cumulative doses is performed to realize the radiation damage prediction of devices under different cumulative dose points.
[0011] Furthermore, the step S1 includes the following sub-steps:
[0012] S101, establishing a device structure model according to doping, size and layout parameters of the bipolar device;
[0013] S102, using a simulation physical model to complete the electrical performance simulation of the bipolar device;
[0014] S103. Based on the comparison between the measured results of Gummel characteristics and the numerical simulation results, the calibration of the device structure model is completed by correcting the parameters of key impurity injection, thermal diffusion process and physical model.
[0015] Furthermore, in the step S101, when establishing the device structure model, the consistency between the input conditions in the simulation process and the actual process is strictly controlled, and the input conditions include ion implantation dose, energy, diffusion time, temperature and etching size.
[0016] Furthermore, in the step S102, the models used in the electrical performance simulation include a fluid mechanics carrier transport model, a Philips unified mobility model, a bandgap narrowing model, a rate saturation model, and an Auger and SRH generation-recombination model.
[0017] Furthermore, in the step S103, the physical characteristics of the device are discretized and distributed to non-uniform grid nodes to obtain multiple nonlinear equations, and the multiple equations are iteratively solved to obtain the physical characteristics at each node, the gummel characteristics of the device are extracted, and the first model electrical parameter calibration is completed through experimental test results and PDK parameters.
[0018] Furthermore, the step S2 includes the following sub-steps:
[0019] S201, customize irradiation test board and test board, and complete the construction of the experimental platform;
[0020] S202. Complete the gamma low-dose rate irradiation experiment and key parameter test characterization to obtain the degradation law of low-dose rate effect of bipolar devices under low-dose rate;
[0021] S203, constructing oxide traps and interface traps, establishing a defect physical model, and obtaining the corresponding relationship between the defect physical model parameters and the cumulative dose at the corresponding dose point through experiments.
[0022] Furthermore, in step S202, when conducting low-dose rate and different cumulative dose gamma-ray irradiation experiments, the dose rate is selected as 0.1rad(Si) / s, and the irradiation is performed to dose points of 100krad(Si), 200krad(Si), 300krad(Si), 500krad(Si), 800krad(Si), and 1Mrad(Si).
[0023] Furthermore, in the step S203, the correspondence between the defect physical model parameters and the cumulative dose includes the physical relationship between the irradiation dose, dose rate and physical parameters such as the type, concentration, energy level, capture cross section and the like of oxide trap charges and interface trap charges.
[0024] Furthermore, the S3 step includes the following sub-steps:
[0025] S301, establishing an effective and physically meaningful defect physical model related to radiation dose by setting trap parameters, combining the generation-recombination model related to the defect capture-emission process, and inputting it into the bipolar device structure model to obtain an ionizing radiation damage model; the trap parameters include the type and concentration of oxide traps and interface traps, the position and distribution of discrete trap energy levels, and the electron / hole capture cross section;
[0026] S302, based on the ionizing radiation damage model, simulate the change of the gummel characteristic of the bias voltage VBE in the range of 0 to 1V with the radiation dose;
[0027] S303. According to the measured results of gummel characteristics before and after irradiation, the excess base current curve of the measured data is compared with the simulation results, and the ionizing radiation damage model is calibrated and verified by pulling the key process conditions and correcting the physical model.
[0028] Furthermore, in the S4 step, device radiation damage prediction at different cumulative dose points is realized based on the low-dose rate radiation damage prediction model for bipolar devices, wherein for dose points between the measured doses, device parameter characteristics are obtained by interpolation; for dose points outside the measured doses, device parameter characteristics are obtained by extrapolation.
[0029] In the present invention, based on the TCAD simulation tool, a method combining irradiation experiments and numerical simulation is adopted. Based on the physical connection between radiation-induced microscopic defects and ionization cumulative dose, a bipolar device structure model and a bipolar device low-dose rate irradiation damage prediction model are established. For the radiation damage of the self-owned bipolar process device under low dose rate and different cumulative dose conditions, a rapid and quantitative prediction of the degradation behavior of the key electrical characteristics of the device within a wide operating voltage range is achieved. The research results can be extended to the ELDRS effect damage assessment of the same type of process bipolar devices, thereby greatly shortening the low-dose rate damage effect assessment time, reducing the assessment cost, and supporting the development of independent controllable radiation-resistant reinforced bipolar processes. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0031] Figure 1 The flowchart is a method for predicting low-dose rate radiation damage of bipolar devices according to an embodiment of the present invention.
[0032] Figure 2 This is a comparison chart between the experimental data and numerical simulation results of excess base current of Si Ge bipolar devices under low dose rate irradiation conditions. DETAILED DESCRIPTION
[0033] The following describes the implementation methods of the present invention through specific examples. The illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention. The following embodiments and features in the embodiments may be combined with each other without conflict.
[0034] Bipolar Junction Transistor (BJT) plays an important role in aerospace electronic systems due to its high current driving capability, low noise, good linear characteristics and matching. Various analog and hybrid circuits based on BJT occupy an important position in aerospace electronic systems. However, the Enhanced Low Dose Rate Sensitivity (ELDRS) effect of BJT used in space environment has become a key breakthrough in the development of radiation hardening of bipolar process devices for aerospace in recent years, and it is also one of the long-term research directions in the field of radiation hardening in the world. On the one hand, the data obtained from ground-based low-dose rate irradiation experiments are limited, time-consuming and costly, and cannot meet the needs of rapidly developing aerospace missions. On the other hand, the study found that the degradation of devices under low dose rate and high cumulative dose shows an increasing trend. This phenomenon makes the existing empirical model no longer suitable for the evaluation of the ability of bipolar devices to resist high total dose effects. Therefore, it is urgent to propose a method for predicting the damage of bipolar devices with low dose rate effects.
[0035] See also Figure 1 , Figure 1 This is a flow chart of an embodiment of a method for predicting low-dose rate radiation damage to bipolar devices of the present invention. The method for predicting low-dose rate radiation damage to bipolar devices of this embodiment comprises the following steps:
[0036] S1. According to the bipolar device structure and process parameters, a bipolar device structure model is established through simulation software, and the bipolar device structure model is calibrated based on the measured electrical parameters of the bipolar device. This step may include the following sub-steps:
[0037] S101. According to the process information of the Si Ge bipolar device with its own process, such as doping, size and layout parameters, the device structure model is established using the Sprocess simulation tool of the Sentaurus simulation software in the TCAD software. When establishing the device structure model, it is necessary to strictly control the consistency between the input conditions in the simulation process and the actual process, and the input conditions include ion implantation dose, energy, diffusion time, temperature and etching size, etc.
[0038] S102. Use the Sdevice module of the Sentaurus simulation model to complete the electrical performance simulation of the bipolar device; the models used in the electrical performance simulation include the fluid mechanics carrier transport model, the Philips unified mobility model, the bandgap narrowing model, the rate saturation model, the Auger and SRH generation-recombination model, etc.
[0039] S103, based on the comparison between the measured results of the Gummel characteristics and the numerical simulation results, the device structure model is calibrated by correcting the parameters of the key impurity injection, thermal diffusion and other processes and physical models. Specifically, the physical characteristics of the device are discretized and distributed to non-uniform grid nodes to obtain multiple nonlinear equations, and the multiple equations are iteratively solved to obtain the physical characteristics at each node, the gummel characteristics of the device are extracted, and the first model electrical parameter calibration is completed through the experimental test results and PDK parameters (i.e., the modeling parameters of the bipolar device structure model).
[0040] S2. Establish a defect physical model through simulation software, and obtain the corresponding relationship between the defect physical model parameters and the cumulative dose through experiments. This step may include the following sub-steps:
[0041] S201. Customize irradiation test boards and test boards to complete the construction of the experimental platform.
[0042] S202. Complete the gamma low-dose rate irradiation experiment and key parameter test characterization to obtain the degradation law of low-dose rate effect of bipolar devices under low-dose rate. When conducting low-dose rate and different cumulative dose gamma ray irradiation experiments, select a dose rate of 0.1rad(Si) / s, and irradiate to dose points of 100krad(Si), 200krad(Si), 300krad(Si), 500krad(Si), 800krad(Si), and 1Mrad(Si). The irradiated device is placed on a dedicated PCB adapter according to the packaging form, and the test instrument is connected to the aging seat fixed on the general circuit board. When testing, the PCB adapter is directly inserted into the aging seat to achieve rapid switching between sample irradiation and testing. The interval between two irradiations does not exceed 1 hour to avoid the influence of annealing effect. After irradiation, extract the degradation law of the device gummel characteristics with cumulative dose at room temperature. Through the gamma irradiation experiment, extract the gummel curve of the bias voltage VBE in the range of 0~1V after irradiation with different doses.
[0043] S203, establish a defect physical model through simulation software, and obtain the corresponding relationship between the defect physical model parameters and the cumulative dose at the corresponding dose point through experiments. Since ionizing radiation mainly induces oxide trap charges and interface trap charges in bipolar devices, the defect physical model is established by constructing oxide traps and interface traps. The corresponding relationship between the defect physical model parameters and the cumulative dose includes the physical relationship between the irradiation dose, dose rate and the physical parameters such as the type, concentration, energy level, and capture cross section of the oxide trap charge and the interface trap charge. Among them, the corresponding relationship between the fixed oxide trap charge density and the interface state density and the cumulative dose at the corresponding dose point can be expressed as:
[0044] Not =f1(E ox , D)
[0045] N it =f2(D)
[0046] Among them, N ot represents the fixed oxide trap charge density; f1 represents N ot Function corresponding to the cumulative dose; E ox represents the oxide electric field strength; D represents the cumulative dose; N it represents the interface state trap density; f2 represents N it Function corresponding to the cumulative dose.
[0047] S3. Use simulation software to couple the defect physical model and the bipolar device structure model to establish an ionizing radiation damage model; and calibrate the ionizing radiation damage model in combination with low-dose rate irradiation early degradation test data to form a bipolar device low-dose rate irradiation damage prediction model. This step may include the following sub-steps:
[0048] S301. By setting the type and concentration of traps (i.e., oxide traps and interface traps), the location and distribution of discrete trap energy levels, the electron / hole capture cross section and other parameters, an effective and physically meaningful defect physics model related to radiation dose is combined with a generation-recombination model related to the defect capture-emission process, and input into the bipolar device structure model to obtain an ionizing radiation damage model. Among them, the trap charge defect density is 1×10 10 ~1×10 12 cm -2 For the interface states, the acceptor-like traps are located near the conduction band edge at 0.40 eV and 0.60 eV, respectively, and the donor-like trap is located near the valence band edge at 0.60 eV.
[0049] S302. Based on the ionizing radiation damage model, simulate the change of the gummel characteristic of the bias voltage VBE in the range of 0 to 1 V with the radiation dose.
[0050] S303. Based on the gummel characteristic curves before and after irradiation (i.e., the gummel characteristic measured results), calculate and compare the measured data and the simulation results at VBE = 0.6V, and calibrate and verify the ionizing radiation damage model through key process condition deviation and physical model correction. Figure 2 , which is a comparison chart of the experimental data and numerical simulation results of excess base current of SiGe bipolar devices under low dose rate irradiation conditions. Among them, the separated points are the experimental results under different cumulative doses, and the dotted lines are the simulation results under different cumulative doses.
[0051] S4. Based on the low-dose rate irradiation damage prediction model for bipolar devices, device irradiation damage prediction is achieved at different cumulative dose points. In this step, the interpolation method and extrapolation method are used to calculate the corresponding device electrical parameter degradation at different cumulative dose points based on the low-dose rate irradiation damage prediction model for bipolar devices. The interpolation method (interpolation calculation) is used to obtain the parameter characteristics between the measured doses, and the extrapolation method (model extrapolation) is used to obtain the parameter characteristics outside the measured doses, and finally the model prediction error is ≤15% under the condition of 50% target cumulative dose.
[0052] TCAD simulation software becomes an effective numerical simulation tool to describe the changes of physical parameters inside the device by simultaneously coupling the physical equations that control carrier migration, recombination and transport and the external field equations that provide driving force. In this embodiment, based on the TCAD simulation tool, a method combining irradiation experiments and numerical simulations is adopted. Based on the physical connection between radiation-induced microscopic defects and ionization cumulative dose, a bipolar device structure model and a low-dose rate irradiation damage prediction model for bipolar devices are established. For the radiation damage of proprietary bipolar process devices under low dose rates and different cumulative doses, a rapid and quantitative prediction of the degradation behavior of key electrical characteristics of devices within a wide operating voltage range is achieved. The research results can be extended to the ELDRS effect damage assessment of bipolar devices of the same type of process, thereby greatly shortening the low-dose rate damage effect assessment time, reducing the assessment cost, and supporting the development of independent controllable radiation-resistant reinforced bipolar processes.
[0053] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A method for predicting low-dose rate radiation damage of bipolar devices, characterized in that: The following steps are involved: S1. According to the bipolar device structure and process parameters, a bipolar device structure model is established through simulation software, and the bipolar device structure model is calibrated based on the measured electrical parameters of the bipolar device; S2. Establish a defect physical model through simulation software, and obtain the corresponding relationship between the defect physical model parameters and the cumulative dose through experiments; S3. The defect physical model and the bipolar device structure model are coupled by simulation software to establish an ionizing radiation damage model; and the ionizing radiation damage model is calibrated in combination with low-dose rate radiation degradation test data to form a low-dose rate radiation damage prediction model for bipolar devices; S4. Based on the low-dose rate radiation damage prediction model of bipolar devices, electrical parameter simulation under different cumulative doses is performed to realize the radiation damage prediction of devices under different cumulative dose points.
2. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 1, characterized in that: The S1 step includes the following sub-steps: S101, establishing a device structure model according to doping, size and layout parameters of the bipolar device; S102, using a simulation physical model to complete the electrical performance simulation of the bipolar device; S103. Based on the comparison between the measured results of the Gummel characteristics and the numerical simulation results, the calibration of the device structure model is completed by correcting the parameters of the key impurity injection, thermal diffusion process and physical model.
3. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 2, characterized in that: In the step S101, when establishing the device structure model, the consistency between the input conditions in the simulation process and the actual process is strictly controlled, and the input conditions include ion implantation dose, energy, diffusion time, temperature and etching size.
4. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 2, characterized in that: In the step S102, the models used in the electrical performance simulation include a fluid mechanics carrier transport model, a Philips unified mobility model, a bandgap narrowing model, a rate saturation model, and an Auger and SRH generation-recombination model.
5. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 2, characterized in that: In the step S103, the physical characteristics of the device are discretized and distributed to non-uniform grid nodes to obtain multiple nonlinear equations, and the multiple equations are iteratively solved to obtain the physical characteristics at each node, the gummel characteristics of the device are extracted, and the first model electrical parameter calibration is completed through experimental test results and PDK parameters.
6. The method for predicting low-dose rate radiation damage of bipolar devices according to any one of claims 1 to 5, characterized in that: The S2 step includes the following sub-steps: S201, customize irradiation test board and test board, and complete the construction of the experimental platform; S202. Complete the gamma low-dose rate irradiation experiment and key parameter test characterization to obtain the degradation law of low-dose rate effect of bipolar devices under low-dose rate; S203, constructing oxide traps and interface traps, establishing a defect physical model, and obtaining the corresponding relationship between the defect physical model parameters and the cumulative dose at the corresponding dose point through experiments.
7. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 6, characterized in that: In the step S202, when conducting low-dose rate and different cumulative dose gamma ray irradiation experiments, the dose rate is selected to be 0.1rad(Si) / s, and the irradiation is performed to dose points of 100krad(Si), 200krad(Si), 300krad(Si), 500krad(Si), 800krad(Si), and 1Mrad(Si).
8. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 6, characterized in that: In the step S203, the correspondence between the defect physical model parameters and the cumulative dose includes the physical relationship between the irradiation dose, the dose rate and the physical parameters of the oxide trap charge and the interface trap charge; the physical parameters of the oxide trap charge and the interface trap charge include the type, concentration, energy level, and capture cross section of the oxide trap charge and the interface trap charge.
9. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 6, characterized in that: The S3 step includes the following sub-steps: S301, establishing an effective and physically meaningful defect physical model related to radiation dose by setting trap parameters, combining the generation-recombination model related to the defect capture-emission process, and inputting it into the bipolar device structure model to obtain an ionizing radiation damage model; the trap parameters include the type and concentration of oxide traps and interface traps, the position and distribution of discrete trap energy levels, and the electron / hole capture cross section; S302, based on the ionizing radiation damage model, simulate the change of gummel characteristics of bias voltage VBE in the range of 0 to 1V with radiation dose; S303. Based on the measured results of gummel characteristics before and after irradiation, the excess base current curve of the measured data is compared with the simulation results. The ionizing radiation damage model is calibrated and verified by pulling the key process conditions and correcting the physical model, and a low-dose rate irradiation damage prediction model for bipolar devices is established.
10. The method for predicting low-dose rate radiation damage of bipolar devices according to claim 1, characterized in that: In the step S4, device radiation damage prediction at different cumulative dose points is achieved based on the low-dose rate radiation damage prediction model for bipolar devices, wherein for dose points between the measured doses, device parameter characteristics are obtained by interpolation; for dose points outside the measured doses, device parameter characteristics are obtained by extrapolation.