Conservative estimation method for total dose performance of bipolar devices based on variable dose rate irradiation

Abstract

To address the high testing costs associated with variable dose rate irradiation methods, the present invention provides a conservative estimation method for the total dose resistance of bipolar devices based on variable dose rate irradiation. Specifically, the present invention utilizes high dose rates to accelerate radiation damage to bipolar devices. Secondly, low dose rate irradiation is used to determine the parameter degradation rate of bipolar devices at low dose rates. Finally, assuming that the degradation rate of sensitive parameters of the test samples does not significantly change at low dose rates, the total dose effect failure threshold of the test samples is estimated by linearly extrapolating the damage curve at low dose rates. This provides a simple, effective, and highly operational ground simulation test method for evaluating the total dose resistance of bipolar devices with a low dose rate enhancement effect.

Description

Technical Field

[0001] The present invention relates to the field of spatial total dose effect, and in particular to a conservative estimation method for total dose resistance performance of a bipolar device based on variable dose rate irradiation. Background Art

[0002] The natural radiation environment in space can produce cumulative ionizing radiation effects (referred to as total dose effects) in electronic systems or electronic devices, leading to degradation of electronic system electrical parameters or even functional failure, seriously affecting the life and reliability of spacecraft and strategic weapons. Therefore, it is necessary to study the simulation test method of the total dose effect of electronic devices on the ground to evaluate the total dose resistance performance of the devices. Since natural radiation in space is a low-dose rate radiation environment (about 10 -4 rad(Si) / s~10 -2 rad(Si) / s). If simulation tests are carried out on the ground within this dose rate range, it will take up a lot of time and cost. Therefore, studying accelerated test methods is one of the key issues in the ground simulation test research of electronic devices.

[0003] Bipolar process electronic devices are the main components of space electronic devices. During operation, there is a weak applied electric field (<0.1MV / cm) in the oxide layer and passivation layer. Therefore, when devices of the same model and batch number are irradiated at different dose rates, different built-in electric fields will be induced in the oxide layer and passivation layer of the device. As a result, after receiving the same total dose of irradiation, the radiation damage at a low dose rate is significantly worse than that at a high dose rate. This is the low-dose-rate radiation damage enhancement effect (ELDRS).

[0004] At present, two ground acceleration test methods have been developed in China for the ELDRS effect, mainly high temperature irradiation acceleration test method and variable dose rate irradiation acceleration test method. The basic principle of variable dose rate irradiation acceleration test method (such as Figure 1 As shown), the devices are divided into N groups (about 5 devices in each group). Each group is first irradiated at a high dose rate in a high dose environment to a specified total dose point (the total irradiation dose of the first group is zero, that is, no high dose rate irradiation is performed), and then irradiated at a low dose rate (an irradiation dose rate similar to the space environment). After the test is completed, the low dose rate data of groups 2 to N are sequentially translated to the damage curve of the test samples in group 1 according to the principle of equal radiation damage, thereby reconstructing the radiation damage curve of the device at a low dose rate. The advantage of this method is that it can accelerate the radiation damage in the device through high dose rate irradiation and obtain the radiation damage of the device in the low dose rate radiation environment of actual operation. It is a fast and accurate method to estimate the actual damage of the device in orbit. However, this method has fatal disadvantages:

[0005] (1) Multiple groups of test samples are required, and the number of samples is 3 to 5 times that of the high-temperature irradiation accelerated test method, resulting in high test costs;

[0006] (2) Since the radiation damage data of multiple groups of test samples in a low-dose rate environment are needed to reconstruct the radiation damage curve of the device at a low dose rate, the uncertainty of the radiation damage of the test samples in each group is required to be small. However, in practice, especially during the growth of thick oxide layers and passivation layers in bipolar devices, process fluctuations are inevitable, resulting in fluctuations in the position, concentration, and energy level of defects in the Si and oxide layer surfaces, oxide layers, and passivation layers in the device. This may cause large differences in the low-dose rate radiation damage of different groups of test samples, making it difficult to complete the reconstruction of the low-dose rate radiation damage curve. In order to reduce the uncertainty of radiation damage between groups of samples, the number of samples in each group can only be increased, which will also lead to the problem of high test costs. Summary of the Invention

[0007] The purpose of the present invention is to solve the problem that the variable dose rate irradiation method requires a large number of test samples and has high test costs, and to provide a conservative estimation method for the total dose resistance performance of bipolar devices based on variable dose rate irradiation.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for conservatively estimating the total dose resistance performance of a bipolar device based on variable dose rate irradiation is characterized in that it includes the following steps:

[0010] Step 1: Select a test sample of the device to be tested, measure the initial performance parameters and irradiation parameters of the test sample, and determine the high dose rate, low dose rate, total irradiation dose at the high dose rate value, and total irradiation dose at the low dose rate value of the irradiated test sample;

[0011] The irradiation parameters include source type, radiation dose field uniformity, and test sample performance measurement time;

[0012] Step 2: irradiate the test sample at a high dose rate according to the set high dose rate value and total irradiation dose, measure the performance parameters of the test sample after irradiation, calculate the high dose rate reliability of each performance parameter, determine the most sensitive irradiation parameter of the test sample at the high dose rate and judge whether its reliability meets the requirements. If so, proceed to the next step; otherwise, repeat step 2;

[0013] Step 3: annealing the test sample at room temperature after high dose rate irradiation;

[0014] Step 4: irradiate the test sample at a low dose rate according to the set low dose rate value and total irradiation dose, measure the performance parameters of the test sample after irradiation, calculate the low dose rate reliability of each performance parameter, determine the most sensitive irradiation parameter of the test sample at the low dose rate and judge whether its reliability meets the requirements. If so, proceed to the next step; otherwise, repeat step 4;

[0015] Step 5: Interpolate and calculate the total dose TID0 that the test sample will receive when it fails and the total dose value TID corresponding to the initial parameter value obtained by extrapolating the damage fitting curve of the test sample at a low dose rate. fit , and then get the total dose failure threshold estimate TID of the test sample th =TID0-TID fit .

[0016] Furthermore, step 2 is specifically as follows:

[0017] 2.1. Perform high-dose-rate irradiation on the test sample according to the set high-dose-rate value and total irradiation dose;

[0018] 2.2. During the high dose rate irradiation period, the performance parameters of the test samples shall be measured at least three times;

[0019] 2.3. Calculate the high-dose rate reliability of each performance parameter and determine the parameter with the lowest reliability as the most sensitive parameter of the test sample under high-dose rate irradiation;

[0020] 2.4. Determine whether the calculated reliability of the most sensitive parameter is less than the high dose rate reliability threshold A. If so, end the high dose rate irradiation test; otherwise, return to step 2.1.

[0021] Furthermore, step three is specifically as follows:

[0022] 3.1. Anneal the test samples at room temperature after high dose rate irradiation;

[0023] 3.2. Set the time interval t to measure the test sample parameters once, and end the annealing test until the change in the test sample parameters or the annealing time meets the annealing end requirements;

[0024] The annealing completion requirement is that the change in the test sample parameters is less than 5% / day, or the annealing time is greater than 168 hours.

[0025] Furthermore, step four is specifically as follows:

[0026] 4.1. Perform low-dose rate irradiation on the test sample according to the set low-dose rate value and total irradiation dose;

[0027] 4.2. During the low-dose rate irradiation period, measure the performance parameters of the test sample at least three times;

[0028] 4.3. Calculate the low-dose rate reliability of each performance parameter and determine the parameter with the lowest reliability as the most sensitive parameter of the test sample under low-dose rate irradiation;

[0029] 4.4. Determine whether the calculated reliability of the most sensitive parameter is less than the low-dose rate reliability threshold B. If so, end the low-dose rate irradiation test; otherwise, return to step 4.1.

[0030] Furthermore, in step 2 and step 4, the reliability R i Calculated by the following formula:

[0031]

[0032] Among them, M i is the margin of the test sample performance parameter i, that is, the difference between the upper and lower limits of the performance parameter i and the current measured value of the performance parameter i; U i is the uncertainty of performance parameter i;

[0033]

[0034] Where N is the total number of samples; k is the expansion factor; P i,j is the value of the jth device parameter i in the test sample; is the average value of parameter i.

[0035] Furthermore, the value of k meets the following requirements:

[0036] When the reliability R of performance parameter i i When the confidence level is 0.95, k = 2; the reliability R of performance parameter i i When the confidence level is 0.99, k = 2.58.

[0037] Further, in step 2.4, the high dose rate reliability threshold A=1.2;

[0038] In step 4.4, the low dose rate reliability threshold B=0.9.

[0039] Furthermore, step five is specifically as follows:

[0040] 5.1. Draw the parameter damage curve of the test sample under high dose rate irradiation;

[0041] 5.2. Fit the damage curve of the parameters under high dose rate irradiation and interpolate to calculate the total dose TID corresponding to the parameter value at the end of room temperature annealing anneal ;

[0042] 5.3. Total dose TID annealThe starting point of the total dose at low dose rate is used to draw the parameter curve of the test sample under low dose rate irradiation;

[0043] 5.4. Fit and extrapolate the parameter damage curve under low dose rate irradiation, and interpolate the total dose TID0 that the test sample will withstand when it fails and the total dose value TID corresponding to the initial parameter value fit ;

[0044] 5.5. Calculation of the total dose failure threshold of the test sample to estimate TID th =TID0-TID fit .

[0045] Furthermore, in step 1, the range of the high dose rate value is 0.5 to 5 rad(Si) / s; the total irradiation dose at the high dose rate value satisfies: the reliability of the most sensitive radiation parameter is 1.1≤R≤1.2;

[0046] The low dose rate value is 0.01 rad(Si) / s; the total irradiation dose at the low dose rate value satisfies: the reliability of the most sensitive parameter is less than or equal to 0.9.

[0047] Furthermore, in step 5.4, the parameter damage curve is fitted by linear fitting or negative exponential fitting according to the degradation of the radiation parameters, and the weights of the first 1 to 3 measurement points are reduced during fitting.

[0048] Compared with the prior art, the present invention has the following beneficial technical effects:

[0049] 1. The conservative estimation method for the total dose resistance performance of bipolar devices based on variable dose rate irradiation provided by the present invention can conservatively estimate the failure threshold of the test samples using only one group of test samples. The number of test samples used is only 1 / 3 to 1 / 5 of the original method, which greatly saves the test cost; at the same time, it avoids the problem of differences in radiation damage between different groups of test samples in the original variable dose rate test method, making the method more operable and reducing the uncertainty of the test results.

[0050] 2. The conservative estimation method for the total dose resistance performance of bipolar devices based on variable dose rate irradiation provided by the present invention adds a room temperature annealing process between the high and low dose rate tests, so that the radiation-induced products accelerated by the high dose rate are more stable, the accuracy of the parameter degradation curve at the low dose rate is improved, and the scope of applicable devices of the variable dose rate irradiation test method is expanded, so that the operability and applicability of the conservative estimation test of the dose rate resistance performance of bipolar devices are effectively improved.

[0051] 3. The conservative estimation method for the total dose resistance performance of bipolar devices based on variable dose rate irradiation provided by the present invention provides a simple, effective and highly operational ground simulation test method for evaluating the total dose resistance performance of bipolar devices with low dose rate enhancement effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a basic principle diagram of the existing variable dose rate irradiation accelerated test method;

[0053] Figure 2 This is a schematic diagram of a conservative estimation method for the dose rate resistance performance of a bipolar device based on variable dose rate irradiation according to the present invention;

[0054] Figure 3 This is a diagram showing the general variation of the electrical parameters of bipolar devices during irradiation;

[0055] Figure 4 The present invention is a flow chart of a conservative estimation method for the dose rate resistance performance of a bipolar device based on variable dose rate irradiation. DETAILED DESCRIPTION

[0056] To further clarify the objectives, advantages, and features of the present invention, the following describes in further detail a conservative estimation method for the total dose resistance of a bipolar device based on variable dose rate irradiation, in conjunction with the accompanying drawings and specific examples. Those skilled in the art should understand that these embodiments are merely intended to illustrate the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0057] The basic idea of the present invention is (as Figure 2 As shown in Figure 3, first, a high dose rate is used to accelerate the radiation damage of the bipolar device; second, a low dose rate is used to obtain the parameter degradation rate of the bipolar device at a low dose rate; finally, assuming that the degradation rate of the sensitive parameters of the test sample does not change significantly at a low dose rate, the total dose effect failure threshold (TID) of the test sample is estimated by linearly extrapolating the damage curve at a low dose rate. th :

[0058] TID th =TID0-TID fit (1)

[0059] Among them, TID0 is the total dose that the sample receives when it fails, TID fit The total dose value TID is the initial parameter value obtained by extrapolating the damage fitting curve of the device at low dose rate. fit .

[0060] The reason why the present invention can estimate the total dose failure threshold of bipolar devices is:

[0061] (1) Numerous experimental results have shown that the radiation damage to most bipolar devices exhibiting the ELDRS effect at high and low dose rates is independent of each other. That is, the radiation damage caused by high doses does not affect the device parameter degradation rate at low dose rates. This is mainly because the steady-state radiation damage formed in current bipolar devices has a relatively high energy level and is not easily annealed during room temperature irradiation. This is also the basic requirement for test samples in current variable dose rate irradiation methods.

[0062] (2) During the irradiation process, the degradation of bipolar devices parameters mainly includes three processes (such as Figure 3 As shown): ① slow change process; ② linear change process; ③ saturation process. Under normal circumstances, the slow change process of device parameters can be long or short, and it is also possible that no obvious slow change process can be observed for the parameters of some devices; the failure of device parameters mainly occurs in the linear change process. For devices without obvious slow change process, the present invention can estimate the failure threshold of the parameter more accurately, but for devices with slow change process, since the present invention only has one group of devices and directly carries out high-dose rate tests, it is impossible to obtain the slow change process of the device parameters at low dose rates. The degradation rate of the test sample parameters at low dose rates did not show obvious degradation before the parameter failure, which essentially means that the device does not have a slow change process. Since the parameter degradation rate in the slow change process is lower than that in the linear process, the total dose failure threshold obtained is lower than the actual effective threshold of the device, which is a conservative estimate of the device damage.

[0063] like Figure 4 As shown in the figure, a conservative estimation method for the total dose resistance performance of bipolar devices based on variable dose rate irradiation is provided. The specific steps are as follows:

[0064] Step 1: Preparation for irradiation test

[0065] 1.1. Select a group of test samples according to the test requirements and measure the initial device performance parameters and irradiation parameters;

[0066] The irradiation parameters include source type, radiation dose field uniformity, test sample performance measurement time, etc. For details, please refer to GJB5422-2005. In this embodiment, the radiation source is a cobalt source, and the radiation field dose non-uniformity is less than 10%.

[0067] 1.2. Determine the high dose rate value and low dose rate value of the irradiation test sample, as well as the low dose rate value and the total irradiation dose at the low dose rate value;

[0068] Step 2: High Dose Rate Irradiation Stage

[0069] 2.1. Irradiate the test sample at a high dose rate according to the set high dose rate value;

[0070] In this embodiment, the dose rate of high-dose-rate irradiation ranges from 0.5 to 5 rad(Si) / s. The total irradiation dose is recommended to ensure that the margin of the most sensitive radiation parameter reaches 80% to 90% of the maximum allowable margin, that is, the reliability is 1.1 to 1.2.

[0071] 2.2 During the high dose rate irradiation period, the performance parameters of the test samples shall be measured regularly or irregularly;

[0072] 2.3. Calculate the high-dose rate reliability of each performance parameter and determine the parameter with the lowest reliability as the most sensitive parameter of the test sample under high-dose rate irradiation;

[0073] The most sensitive radiation parameter is evaluated by dimensionless reliability. The reliability of radiation parameter i is R i :

[0074]

[0075] Among them, M i is the margin of the test sample performance parameter i, that is, the difference between the upper and lower limits of the performance parameter i and the current measured value of the performance parameter i. For performance parameters with clear upper and lower limits, the value with the smaller margin should be taken, that is, M i =min(P i,upperLimit -P i ,P i -P i,lowLimit ), where P i is the value of performance parameter i;

[0076] The maximum margin allowed for performance parameter i refers to the difference between the tolerance and initial value of the performance parameter i before irradiation. If the performance parameter i drifts towards the lower limit after irradiation, the maximum margin should be calculated as P i,0 -P i,lowLimit (where P i,0 is the initial value of performance parameter i), otherwise it should be P i,upperLimit -P i,0 .

[0077] During variable dose rate irradiation, high-dose rate irradiation is intended to accelerate the formation of stable radiation damage within the test sample. Excessively high dose rates can form oxide trap charges that are prone to annealing, thus affecting the parameter degradation rate during subsequent low-dose rate irradiation tests. Therefore, it is recommended to consider both test time and radiation-induced products. The determination of the total irradiation dose should also be based on radiation damage, ensuring that the device incurs sufficient radiation damage, thereby reducing the low-dose rate irradiation time and improving test efficiency.

[0078] U iThe uncertainty of performance parameter i is the type A uncertainty of the test result (ignore type B uncertainty and only consider type A uncertainty and extended uncertainty) which is the standard parameter of the test parameter, that is:

[0079]

[0080] Among them, P i,j is the value of the jth device parameter i in the test sample, is the average value of parameter i, N is the total number of samples. k is the expansion factor, which is related to the reliability R i The performance parameters of general devices obey the normal distribution. When the confidence level is 0.95, k = 2; when the confidence level is 0.99, k = 2.58.

[0081] After obtaining the reliability of each parameter of the test sample, the most sensitive parameter of the device is the parameter with the lowest reliability.

[0082] 2.4. Determine whether the calculated reliability of the most sensitive parameter is less than and close to the high dose rate reliability threshold A = 1.2. If so, end the high dose rate irradiation test; otherwise, return to step 2.1 and perform the high dose rate irradiation test.

[0083] Step 3: Room temperature annealing stage

[0084] 3.1. Anneal the test samples at room temperature after high dose rate irradiation;

[0085] 3.2. Set the time interval t to measure the test sample parameters once, and determine whether the change in the test sample parameters is less than 5% / day or the annealing time is greater than 168h. If so, end the annealing test; otherwise, return to step 3.1.

[0086] Enhanced room temperature annealing between high and low dose rate tests offers the following advantages:

[0087] ① Applicability of the extended method: Some devices will experience annealing effects after high-dose-rate irradiation. If low-dose-rate test results are directly carried out, the final test results will be affected. Adding room-temperature annealing can make the radiation-induced damage at high dose rates more stable and reduce the impact of room-temperature annealing of radiation-induced products on the degradation rate of low-dose-rate radiation damage.

[0088] ② Enhance the operability of the method: The test sources currently available for device total dose effect simulations are difficult to be compatible with both high and low dose rates, and generally require replacement of the radiation source. Adding a room temperature annealing process between the high and low dose rate test stages can leave more time for source replacement, greatly improving the operability of the method described in the present invention.

[0089] Step 4: Low-dose-rate irradiation stage

[0090] 4.1. Irradiate the test sample at a low dose rate according to the set low dose rate value;

[0091] For low-dose-rate irradiation, it is recommended to select the dose rate at which the device actually operates. For space applications, the average on-orbit dose rate can generally be selected. If the on-orbit environment is unknown, a dose rate of 0.01 rad(Si) / s is generally selected. The total irradiation dose at low dose rates should meet the following two conditions: ① The degradation of the most sensitive parameters of all test samples is greater than 1.1 to 1.2 times the maximum allowable degradation, that is, the reliability is 0.8 to 0.9; ② Obtain damage curves of the device's sensitive parameters at low dose rates.

[0092] 4.2. During the low-dose rate irradiation period, the performance parameters of the test samples shall be measured regularly or irregularly;

[0093] 4.3. Calculate the low-dose rate reliability of each performance parameter and determine the parameter with the lowest reliability as the most sensitive parameter of the test sample under low-dose rate irradiation;

[0094] 4.4. Determine whether the calculated reliability of the most sensitive parameter is less than the low-dose rate reliability threshold B = 0.9. If so, terminate the low-dose rate irradiation test; otherwise, return to step 4.1 and perform the low-dose rate irradiation test;

[0095] Step 5: Data processing stage

[0096] 5.1. Draw the parameter damage curve of the test sample under high dose rate irradiation;

[0097] 5.2. Fit the damage curve of the parameters under high dose rate irradiation and interpolate to calculate the total dose TID corresponding to the parameter value at the end of room temperature annealing anneal

[0098] 5.3. Total dose TID anneal The total dose starting point of the low dose rate is used to draw the damage curve of the test sample performance parameters versus the total dose;

[0099] 5.4. Fit and extrapolate the parameter damage curve under low dose rate irradiation, and interpolate the total dose TID0 that the test sample will withstand when it fails and the total dose value TID corresponding to the initial parameter value fit ;

[0100] The radiation damage at low dose rate is fitted and extrapolated to the initial value of the parameter before irradiation, and the total dose TID corresponding to the initial value is calculated. fit The curve fitting is done by linear fitting or negative exponential fitting according to the parameter degradation. The weight of the first 1 to 3 measurement points can be reduced during fitting to minimize the degradation effect of radiation-induced products under high dose rates.

[0101] 5.5. Calculation of the total dose failure threshold of the test sample to estimate TID th =TID0-TID fit .

[0102] A conservative estimate of the total dose resistance performance of bipolar devices based on variable dose rate irradiation is achieved.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A conservative estimation method for the total dose resistance performance of bipolar devices based on variable dose rate irradiation, characterized in that: The following steps are involved: Step 1: Select a test sample of the device to be tested, measure the initial performance parameters and irradiation parameters of the test sample, and determine the high dose rate, low dose rate, total irradiation dose at the high dose rate value, and total irradiation dose at the low dose rate value of the irradiated test sample; The irradiation parameters include source type, radiation dose field uniformity, and test sample performance measurement time; Step 2: irradiate the test sample at a high dose rate according to the set high dose rate value and total irradiation dose, measure the performance parameters of the test sample after irradiation, calculate the high dose rate reliability of each performance parameter, determine the most sensitive irradiation parameter of the test sample at the high dose rate and judge whether its reliability meets the requirements. If so, proceed to the next step; otherwise, repeat step 2; Step 3: annealing the test sample at room temperature after high dose rate irradiation; Step 4: irradiate the test sample at a low dose rate according to the set low dose rate value and total irradiation dose, measure the performance parameters of the test sample after irradiation, calculate the low dose rate reliability of each performance parameter, determine the most sensitive irradiation parameter of the test sample at the low dose rate and judge whether its reliability meets the requirements. If so, proceed to the next step; otherwise, repeat step 4; Step 5: Interpolate and calculate the total dose TID0 that the test sample will receive when it fails and the total dose value TID corresponding to the initial parameter value obtained by extrapolating the damage fitting curve of the test sample at a low dose rate. fit , and then get the total dose failure threshold estimate TID of the test sample th =TID0-TID fit .

2. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 1, characterized in that: Step 2 is as follows: 2.

1. Perform high-dose-rate irradiation on the test sample according to the set high-dose-rate value and total irradiation dose; 2.

2. During the high dose rate irradiation period, the performance parameters of the test samples shall be measured at least three times; 2.

3. Calculate the high-dose rate reliability of each performance parameter and determine the parameter with the lowest reliability as the most sensitive parameter of the test sample under high-dose rate irradiation; 2.

4. Determine whether the calculated reliability of the most sensitive parameter is less than the high dose rate reliability threshold A. If so, terminate the high dose rate irradiation test; Otherwise, return to step 2.

1.

3. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 2, characterized in that: Step three is as follows: 3.

1. Anneal the test samples at room temperature after high dose rate irradiation; 3.

2. Set the time interval t to measure the test sample parameters once, and end the annealing test until the change in the test sample parameters or the annealing time meets the annealing end requirements; The annealing completion requirement is that the change in the test sample parameters is less than 5% / day, or the annealing time is greater than 168 hours.

4. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 3, characterized in that: Step 4 is as follows: 4.

1. Perform low-dose rate irradiation on the test sample according to the set low-dose rate value and total irradiation dose; 4.

2. During the low-dose rate irradiation period, measure the performance parameters of the test sample at least three times; 4.

3. Calculate the low-dose rate reliability of each performance parameter and determine the parameter with the lowest reliability as the most sensitive parameter of the test sample under low-dose rate irradiation; 4.

4. Determine whether the calculated reliability of the most sensitive parameter is less than the low-dose rate reliability threshold B. If so, terminate the low-dose rate irradiation test; Otherwise, return to step 4.

1.

5. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 4, characterized in that: In step 2 and step 4, the reliability R i Calculated by the following formula: Among them, M i is the margin of the test sample performance parameter i, that is, the difference between the upper and lower limits of the performance parameter i and the current measured value of the performance parameter i; U i is the uncertainty of performance parameter i; Where N is the total number of samples; k is the expansion factor; P i,j is the value of the jth device parameter i in the test sample; is the average value of parameter i.

6. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 5, characterized in that: The value of k meets the following requirements: When the reliability R of performance parameter i i When the confidence level is 0.95, k = 2; the reliability R of performance parameter i i When the confidence level is 0.99, k = 2.

58.

7. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 6, characterized in that: In step 2.4, the high dose rate reliability threshold A=1.2; In step 4.4, the low dose rate reliability threshold B=0.

9.

8. The method for conservatively estimating the total dose resistance performance of a bipolar device based on variable dose rate irradiation according to any one of claims 1 to 7, characterized in that: Step 5 is as follows: 5.

1. Draw the parameter damage curve of the test sample under high dose rate irradiation; 5.

2. Fit the damage curve of the parameters under high dose rate irradiation and interpolate to calculate the total dose TID corresponding to the parameter value at the end of room temperature annealing anneal ; 5.

3. Total dose TID anneal The starting point of the total dose at low dose rate is used to draw the parameter curve of the test sample under low dose rate irradiation; 5.

4. Fit and extrapolate the parameter damage curve under low dose rate irradiation, and interpolate the total dose TID0 that the test sample will withstand when it fails and the total dose value TID corresponding to the initial parameter value fit ; 5.

5. Calculation of the total dose failure threshold of the test sample to estimate TID th =TID0-TID fit .

9. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 1, characterized in that: In step 1, the range of the high dose rate value is 0.5 to 5 rad(Si) / s; the total irradiation dose at the high dose rate value satisfies: the reliability of the most sensitive radiation parameter is 1.1≤R≤1.2; The low dose rate value is 0.01 rad(Si) / s; the total irradiation dose at the low dose rate value satisfies: the reliability of the most sensitive parameter is less than or equal to 0.

9.

10. The method for conservatively estimating the total dose resistance performance of bipolar devices based on variable dose rate irradiation according to claim 8, characterized in that: In step 5.4, the parameter damage curve is fitted according to the degradation of the radiation parameters, and linear fitting or negative exponential fitting is selected. The weights of the first 1 to 3 measurement points are reduced during fitting.

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