Prediction method for single event effect induced failure rate of FPGA (Field Programmable Gate Array) system in radiation

Abstract

The invention provides a method for predicting a single event effect induced failure rate of an FPGA (Field Programmable Gate Array) system in radiation. The method comprises the following specific steps: representing a radiation environment of the FPGA system; determining the sensitivity of the single particle effect of the FPGA system in the radiation environment; and establishing a fluence domain reliability model of the FPGA system in the radiation environment: converting the characteristics of the single event effect cross section sigma SEE into a corresponding average fault-free fluence MFTF, and establishing an FPGA system reliability model of each energy spectrum band or LET spectrum band in a given radiation fluence according to the average fault-free fluence MFTF and the total number phi of particles passing through a unit area in a radiation field. According to the method, physical process analysis and data driving means are combined, and the fluence domain reliability model is established, so that the reliability of related equipment in a special physical environment is improved.

Description

Technical Field

[0001] The present invention relates to the field of radiation environment reliability, and in particular to a method for predicting the failure rate of a FPGA system induced by a single particle effect in radiation. Background Art

[0002] Field Programmable Gate Array (FPGA) systems are widely used in many fields, but the use of FPGA development systems in radiation environments has the following disadvantages: Single-Particle Upset (SEU) Problem: High-energy particles in the radiation environment hit the circuit nodes in the FPGA, which may deposit enough charge to change the state of the node, causing the FPGA to fail to work properly, seriously affecting the reliability of the system. Firmware Error: In a radiation environment, a single-bit SEU of the FPGA configuration element may cause a firmware error. Logical Function Error: Radiation may affect the logic circuit inside the FPGA, causing the switching characteristics of the logic gate to change, resulting in errors in the results of logical operations. Increased Current Leakage: Radiation can change the characteristics of semiconductor devices such as transistors in the FPGA, resulting in increased leakage current; the increase in leakage current will not only increase the power consumption of the FPGA, but may also cause circuit misoperation and even interfere with other electronic components. This phenomenon is called single-particle lockout (SEL).

[0003] Therefore, when working in a given radiation environment, the probability of single-event effects (SEE) occurring in FPGAs is usually estimated using ground simulation test methods, software simulation methods, empirical formula methods, and fault injection methods.

[0004] The above-mentioned traditional single particle effect SEE analysis method mainly multiplies the total number of bits in the design by the error rate to obtain the system error rate, so it cannot effectively characterize the error rate or the mean time to failure MTTF. When facing complex systems in radiation environments, it cannot give the failure rate induced by SEE in FPGA. The deviation of the obtained failure rate induced by SEE in FPGA is very large, so reliability data such as reliability and failure rate cannot be obtained. The main reasons are: the operation mode of FPGA-based systems is different from that of memories. In addition, using the same multiplication factor in the trigger DFF will produce extreme overestimation. Fault injection or simulation will not determine the contribution rate of frequency to SEE sensitivity. Various components in FPGA are prone to SEU. However, the SEU sensitivity characteristics of such components are accurately described at the per-bit level. The estimated granularity of the error rate calculated at the transistor level is too small to be properly extrapolated to complex systems. Therefore, the present invention proposes a method for predicting the failure rate induced by single particle effects in complex FPGA systems, and solves the reliability evaluation problem under the influence of radiation processes by establishing a fluence domain reliability model. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for predicting the failure rate of single particle effect induced by radiation in an FPGA system. SEE The characteristics are converted into the corresponding mean fault-free flux MFTF and the total number of particles passing through a unit area in the radiation field Φ, and the FPGA system reliability model of each energy spectrum segment or LET spectrum segment within a given radiation flux is established. The reliability of the FPGA system in the radiation environment is calculated, and the reliability of the FPGA system in a specified radiation environment and a specified time period is obtained, thereby solving the reliability assessment problem under the influence of the radiation process, which is of great value for improving the reliability of related equipment in special physical environments.

[0006] The present invention provides a method for predicting the failure rate of a single-particle effect induced by radiation in an FPGA system, and the specific implementation steps are as follows:

[0007] S1. Characterize the radiation environment of the FPGA system:

[0008] S11, obtaining the LET spectrum and energy spectrum according to the work requirements and task profile of the reliability assessment of the FPGA system in the radiation environment;

[0009] S12, dividing the LET spectrum and energy spectrum obtained in step S11 into a plurality of energy segments and LET segments according to requirements, and calculating the particle fluence of each energy segment and LET segment within a specified time;

[0010] S2. Determine the sensitivity of the FPGA system to single-particle effects in a radiation environment: Use ions with different linear energy transfers, protons with different energies, or neutrons with different energies to conduct SEE tests on the energy spectrum and LET spectrum obtained in step S11, and obtain the single-particle effect cross sections σ corresponding to ions with different LETs, protons with different energies, or neutrons with different energies. SEE , the single event effect cross section σ SEE The expression is:

[0011] σ SEE =#errors / fluence

[0012] Where #errors is the number of failed particles, and fluence refers to the total number of particles passing through a unit area, which is usually used to describe the intensity of a particle beam or radiation field.

[0013] S3. Establish the fluence domain reliability model of FPGA system in radiation environment:

[0014] S31, the single particle effect cross section σ obtained in step S2 SEE The characteristic is converted into the corresponding mean fault-free flux MFTF, and the specific expression is:

[0015] MFTF=1 / σ SEE ;

[0016] S32, according to the mean fault-free fluence MFTF obtained in step S31 and the total number of particles passing through per unit area in the radiation field Φ, establish the FPGA system reliability model of each energy spectrum segment or LET spectrum segment within a given radiation fluence, the specific expression of the fluence domain reliability model of the FPGA system is:

[0017] R(Φ)=e -φ / MFTF ;

[0018] S4. Calculate the reliability of the FPGA system in a radiation environment:

[0019] S41, calculating the particle flux of each energy spectrum segment and LET spectrum segment according to the working time of the FPGA system in the radiation environment;

[0020] S42, using the particle flux obtained in step S41 and the fluence domain reliability model obtained in step S3 to calculate the reliability of each energy spectrum segment and LET spectrum segment;

[0021] S5. Based on the reliability result obtained in step S4, the reliability is compared with the reliability requirement in step S11 to obtain the reliability of the FPGA system within a specified time period in a specified radiation environment.

[0022] Preferably, in step S11, the mission profile includes flight altitude, flight latitude, flight longitude and flight time.

[0023] Preferably, in step S11, the LET spectrum is the radiation spectrum of heavy ions in the radiation environment, and the energy spectrum is the radiation spectrum of protons and neutrons in the radiation environment.

[0024] Preferably, in step S2, the occurrence of single event effect events in the SEE test is random, and the single event effect cross section σ SEE The value is a constant value.

[0025] Preferably, in step S3, the total number of particles Φ passing through a unit area in the radiation field is the intensity of the radiation field in the radiation environment.

[0026] Preferably, in step S5, the specified time period of the FPGA system in the specified radiation environment means that the types of high-energy particles in the radiation environment and their energy spectrum are determined, and the system operating time in the radiation environment is determined.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The present invention establishes an effective injection domain reliability model through a mapping method combined with physical process analysis and data-driven means. It has broad application prospects in many fields such as semiconductors and nuclear energy, and is of great value in improving the reliability of related equipment in special physical environments.

[0029] Reliability assessment of semiconductor devices for aerospace: In the space environment, semiconductor devices are exposed to radiation from high-energy particles such as cosmic rays. By mapping the classic reliability model to the fluence domain, the risk of chip failure can be assessed in advance based on the fluence estimate of the space radiation environment, and the life of these devices in the space radiation environment can be predicted more accurately.

[0030] Reliability assessment of semiconductor devices for aviation or ground use: At the cruising altitude of aircraft and in some special environments with strong ground radiation, the fluence domain reliability model can help evaluate the reliability of electronic equipment working in these areas in the radiation environment. Through the fluence domain reliability model, the probability of chip failure due to radiation fluence accumulation within a certain period of time can be predicted, and then the chip replacement cycle can be reasonably arranged to ensure the long-term stable operation of the monitoring system.

[0031] Photovoltaic device reliability research: Photovoltaic cells are affected by photon fluence during operation. By mapping the reliability model to the fluence domain, the reliability of photovoltaic cells under different light intensities, i.e., photon fluence, can be analyzed. Using the fluence domain reliability model, the performance degradation of photovoltaic cells can be predicted, providing a reference for power station maintenance and battery replacement plans, thereby improving the overall economic benefits of photovoltaic power generation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of the method for predicting the failure rate induced by single-particle effect in radiation of FPGA system according to the present invention;

[0033] Figure 2 The atmospheric neutron energy spectrum at 41° north latitude and -74° longitude for the prediction method of the single particle effect induced failure rate of the FPGA system in radiation of the present invention;

[0034] Figure 3 The present invention is a neutron flux 4h histogram for the prediction method of the failure rate induced by single particle effect in FPGA system in radiation. DETAILED DESCRIPTION

[0035] In order to fully describe the technical content, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0036] like Figure 1 As shown in Figure 1, the prediction method for the failure rate of single-event effects induced by radiation in FPGA systems is implemented as follows:

[0037] S1. Characterize the radiation environment of the FPGA system.

[0038] S2. Determine the sensitivity of the FPGA system to single-particle effects in a radiation environment: Use ions with different linear energy transfers (LETs), protons with different energies, or neutrons with different energies to conduct SEE tests on the energy spectrum and LET spectrum obtained in step S11, and obtain the single-particle effect cross sections σ corresponding to ions with different LETs, protons with different energies, or neutrons with different energies. SEE , single event effect cross section σ SEE The expression is:

[0039] σ SEE =#errors / fluence

[0040] Where #errors is the number of failed particles, and fluence refers to the total number of particles passing through a unit area, which is usually used to describe the intensity of a particle beam or radiation field.

[0041] Furthermore, in a preferred embodiment of the present invention, the single event effect (SEE) cross section is the probability of a semiconductor device being hit by a single particle such as a heavy ion, proton, or neutron per unit area and producing a specific effect such as a single event upset SEU or a single event lockout SEL; the SEE cross section usually changes with the energy of the particle, and particles of different energies have different effects on the device. Therefore, the occurrence of a single event effect SEE event in a SEE test is random, and the single event effect cross section σ SEE The value is a constant value.

[0042] S3. Establish a fluence domain reliability model of the FPGA system in a radiation environment.

[0043] S4. Calculate the reliability of the FPGA system in a radiation environment.

[0044] S5. Based on the reliability result obtained in step S4, the reliability requirement in step S11 is compared to verify whether the reliability of the FPGA system in a specified radiation environment and a specified time period can meet the mission requirements of the system, and make engineering decisions. Specifically, engineering decisions include device replacement and solution optimization in the FPGA system.

[0045] Furthermore, the specific operation steps for characterizing the radiation environment of the FPGA system in step S1 are:

[0046] S11. According to the work requirements and task profile of the reliability assessment of the FPGA system in the radiation environment, the LET spectrum and energy spectrum are obtained.

[0047] S12, dividing the LET spectrum and energy spectrum obtained in step S11 into multiple energy segments and LET segments according to needs, and calculating the particle fluence of each energy segment and LET segment within a specified time.

[0048] Specifically, the mission profile includes flight altitude, flight latitude, flight longitude and flight time. The LET spectrum is the radiation spectrum of heavy ions in the radiation environment, and the energy spectrum is the radiation spectrum of protons and neutrons in the radiation environment.

[0049] Furthermore, the specific process of establishing the fluence domain reliability model of the FPGA system in the radiation environment in step S3 includes:

[0050] S31, the single particle effect cross section σ obtained in step S2 SEE The characteristic is converted into the corresponding mean fault-free flux MFTF, and the specific expression is:

[0051] MFTF=1 / σ SEE .

[0052] S32. According to the mean fault-free fluence MFTF obtained in step S31 and the total number of particles passing through the unit area in the radiation field Φ, a reliability model of the FPGA system in each energy spectrum segment or LET spectrum segment within a given radiation fluence is established. The specific expression of the fluence domain reliability model of the FPGA system is:

[0053] R(Φ)=e -φ / MFTF .

[0054] Specifically, the total number of particles Φ passing through a unit area in the radiation field is the intensity of the radiation field in the radiation environment; reliability in a radiation environment refers to the probability that a product can successfully perform its required functions under specific conditions and within a specified time. Φ is used to describe the intensity of the particle beam or radiation field.

[0055] Specifically, the fluence domain reliability model of the FPGA system in the radiation environment in step S3 is mainly based on the traditional time domain reliability model, and the similarity between the reliability parameters and the single particle effect parameters is compared, and the parameters of the traditional time domain reliability model are replaced with the single particle effect parameters one by one to complete the construction of the fluence domain reliability model. Given that the single particle effect is a random event, and the reliability index distribution model is a reliability model that can describe random events, the modeling method of the fluence domain reliability model is to replace the traditional time domain parameters in the reliability index distribution model with the single particle effect parameters, so as to obtain the system reliability determined within a given radiation fluence.

[0056] Furthermore, the specific process of calculating the reliability of the FPGA system in the radiation environment in step S4 includes:

[0057] S41. Calculate the particle flux of each energy spectrum segment and LET spectrum segment according to the working time of the FPGA system in the radiation environment.

[0058] S42, using the particle flux obtained in step S41 and the fluence domain reliability model obtained in step S3 to calculate the reliability of each energy spectrum segment and LET spectrum segment.

[0059] The following is a further description of a method for predicting the failure rate of a single-particle effect induced by radiation in an FPGA system according to the present invention in conjunction with an embodiment:

[0060] In this specific embodiment, the method of the present invention is used to predict the failure rate of the FPGA system caused by the single-particle effect in radiation to evaluate the reliability of the avionics system based on the FPGA embedded with the microprocessor under the given service radiation and given service time. The specific implementation steps are as follows:

[0061] S1. Characterize the radiation environment of avionics systems based on FPGAs embedded with microprocessors:

[0062] S11. According to the reliability requirements of the avionics system based on the FPGA embedded with the microprocessor: at a cruising altitude of 12,000 meters at longitude -74° and latitude 41° north, the reliability within 4 flight hours reaches 3 9s, that is, 99.9%, and the LET spectrum and energy spectrum are obtained, such as Figure 2 shown.

[0063] S12. Based on step S11, a histogram of neutron flux and energy range (E) for 4 hours is created. Considering that the main contribution of the atmospheric neutron energy spectrum to the SEE of the device in the avionics system based on the FPGA embedded microprocessor has three energy ranges: thermal neutron ≤ 0.025eV, thermal neutron 1-10MeV and thermal neutron> 10MeV, the neutron flux of the three energy ranges for 4 hours is calculated respectively, such as Figure 3 shown.

[0064] S2. Determine the sensitivity of the FPGA system to single-particle effects in a radiation environment: Use ions with different linear energy transfers (LETs), protons with different energies, or neutrons with different energies to conduct SEE tests on the energy spectrum and LET spectrum obtained in step S11, and obtain the single-particle effect cross sections σ corresponding to ions with different LETs, protons with different energies, or neutrons with different energies. SEE , single event effect cross section σ SEE The expression is:

[0065] σ SEE =#errors / fluence

[0066] Where #errors is the number of failed particles, and fluence refers to the total number of particles passing through a unit area, which is usually used to describe the intensity of a particle beam or radiation field.

[0067] S3. Establish the fluence domain reliability model of FPGA system in radiation environment:

[0068] S31, the single particle effect cross section σ obtained in step S2 SEE The characteristics are converted into the corresponding mean fault-free flux MFTF, as shown in Table 1.

[0069] Table 1 MFTF corresponding to each energy

[0070] Serial number energy <![CDATA[Cross-section (cm -2 )]]> MFTF 1 ≤0.025eV 4.40E-11 2.27E+10 2 (1~10)MeV 3.10E-08 3.23E+07 4 >10MeV 8.20E-08 1.22E+07

[0071] S32. According to the mean fault-free fluence MFTF obtained in step S31 and the total number of particles passing through the unit area in the radiation field Φ, a reliability model of the FPGA system in each energy spectrum segment or LET spectrum segment within a given radiation fluence is established. The specific expression of the fluence domain reliability model of the FPGA system is:

[0072] R(Φ)=e -φ / MFTF .

[0073] S4. Calculate the reliability of the FPGA system in a radiation environment:

[0074] S41. Calculate the particle flux of each energy spectrum segment and LET spectrum segment according to the working time of the FPGA system in the radiation environment.

[0075] S42. The particle flux obtained in step S41 is used to calculate the reliability of each energy spectrum segment and LET spectrum segment using the fluence domain reliability model obtained in step S3, as shown in Table 2.

[0076] Table 2 Reliability corresponding to each energy range

[0077]

[0078]

[0079] S5. Compare the reliability result obtained in step S4 with the reliability requirement in step S11 to obtain that the device in the avionics system based on the FPGA embedded with the microprocessor cannot meet the reliability requirement.

[0080] If the traditional single particle effect analysis method is used to evaluate the reliability of the avionics system based on FPGA embedded microprocessor under given service radiation and given service time, the reliability index of the FPGA avionics system is mainly estimated based on the single particle effect (SEE) sensitive characteristic data of the FPGA system.

[0081] The specific implementation steps of the traditional single event effect analysis method are:

[0082] On the basis of step S1, ions with different linear energy transfer, protons with different energies, or neutrons with different energies are used to carry out single-particle effects, and single-particle effect cross sections σ corresponding to ions with different linear energy transfer, protons with different energies, or neutrons with different energies are obtained. SEE .

[0083] In this specific embodiment, the failure rate of the avionics system based on the FPGA embedded with a microprocessor and the σ of each functional module SEE Proportional, the expression is as follows:

[0084] P(fs) system ∝P Configuration +P(fs) functionLogic +P SEFI

[0085] Where fs is the operating frequency of the avionics system based on embedded microprocessor FPGA, P(fs) system is the failure probability of the avionics system based on embedded microprocessor FPGA, P Configuration P(fs) is the single event upset rate of the configuration unit in the avionics system based on embedded microprocessor FPGA. functionLogic is the SEU rate of the functional logic blocks in the avionics system based on embedded microprocessor FPGA, the functional logic blocks include sequential logic blocks and combinational logic blocks; P SEFI The probability of occurrence of SEFI for a single event function abort is contributed by the global routing and hidden logic blocks in the FPGA.

[0086] σ SEE It is calculated based on the analysis of SEE test data. The devices of the avionics system based on embedded microprocessor FPGA are complex and contain multiple different functional modules. Each functional module has its own σ SEE Contributes to σ SEU The dominant contribution is usually the configuration unit or functional logic unit of the avionics system based on embedded microprocessor FPGA. In the traditional single event effect analysis method, due to the untestability of the global routing SEE in the avionics system based on embedded microprocessor FPGA, its impact on σ SEE The contribution is neglected. Therefore, in determining the dominant σ SEU After that, combined with the radiation environment spectrum during service, the σ per bit SEU Converted to λ per bit bit , and bitMultiply by the total number of bits, the total number of bits in the configuration unit and functional logic block is P(fs) system .

[0087] According to the experimentally obtained σ SEE / bit, use the error rate calculation tool to obtain the error rate per bit. In this analysis method, λ bit Multiply by the number of memory bits used in the target design to obtain the error rate λ for an avionics system based on an FPGA embedded with a microprocessor system .

[0088] Through the above analysis, in the radiation environment, the λ of the avionics system based on the embedded microprocessor FPGA system It is smaller than the failure rate obtained based on the traditional single-particle effect analysis method. Therefore, the traditional single-particle effect analysis method that multiplies the total number of bits by the error rate λ is not suitable for predicting the failure rate of FPGA systems induced by single-particle effects in radiation.

[0089] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for predicting the failure rate of single-particle effects induced by radiation in an FPGA system, characterized in that: The specific implementation steps are: S1. Characterize the radiation environment of the FPGA system: S11, obtaining the LET spectrum and energy spectrum according to the work requirements and task profile of the reliability assessment of the FPGA system in the radiation environment; S12, dividing the LET spectrum and energy spectrum obtained in step S11 into a plurality of energy segments and LET segments according to requirements, and calculating the particle fluence of each energy segment and LET segment within a specified time; S2. Determine the sensitivity of the FPGA system to single-particle effects in a radiation environment: Use ions with different linear energy transfers, protons with different energies, or neutrons with different energies to conduct SEE tests on the energy spectrum and LET spectrum obtained in step S11, and obtain the single-particle effect cross sections σ corresponding to ions with different LETs, protons with different energies, or neutrons with different energies. SEE , the single event effect cross section σ SEE The expression is: σ SEE =#errors / fluence Where #errors is the number of failed particles, and fluence refers to the total number of particles passing through a unit area, which is usually used to describe the intensity of a particle beam or radiation field. S3. Establish the fluence domain reliability model of FPGA system in radiation environment: S31, the single particle effect cross section σ obtained in step S2 SEE The characteristic is converted into the corresponding mean fault-free flux MFTF, and the specific expression is: MFTF=1 / s SEE ; S32, according to the mean fault-free fluence MFTF obtained in step S31 and the total number of particles passing through per unit area in the radiation field Φ, establish the FPGA system reliability model of each energy spectrum segment or LET spectrum segment within a given radiation fluence, the specific expression of the fluence domain reliability model of the FPGA system is: R(Φ)=e -φ / MFTF ; S4. Calculate the reliability of the FPGA system in a radiation environment: S41, calculating the particle flux of each energy spectrum segment and LET spectrum segment according to the working time of the FPGA system in the radiation environment; S42, using the particle flux obtained in step S41 and the fluence domain reliability model obtained in step S3 to calculate the reliability of each energy spectrum segment and LET spectrum segment; S5. Based on the reliability result obtained in step S4, the reliability is compared with the reliability requirement in step S11 to obtain the reliability of the FPGA system within a specified time period in a specified radiation environment.

2. The method for predicting the failure rate of a FPGA system induced by a single event effect in radiation according to claim 1, characterized in that: In step S11, the mission profile includes flight altitude, flight latitude, flight longitude and flight time.

3. The method for predicting the failure rate of a FPGA system induced by a single event effect in radiation according to claim 1 or 2, characterized in that: In step S11, the LET spectrum is the radiation spectrum of heavy ions in the radiation environment, and the energy spectrum is the radiation spectrum of protons and neutrons in the radiation environment.

4. The method for predicting the failure rate of a FPGA system induced by a single event effect in radiation according to claim 1, characterized in that: In step S2, the occurrence of single event effect events in the SEE test is random, and the single event effect cross section σ SEE The value is a constant value.

5. The method for predicting the failure rate of a FPGA system induced by a single event effect in radiation according to claim 1, characterized in that: In step S3, the total number of particles Φ passing through a unit area in the radiation field is the intensity of the radiation field in the radiation environment.

6. The method for predicting the failure rate of a FPGA system induced by a single event effect in radiation according to claim 1, characterized in that: In step S5, the FPGA system specifies a time period in a specified radiation environment, which means that the types of high-energy particles in the radiation environment and their energy spectrum are determined, and the system operating time in the radiation environment is determined.

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