Method for obtaining device equivalent silicon layer thickness and single event upset LET threshold

Abstract

The present application relates to a kind of device equivalent silicon layer thickness and the acquisition method of single event upset LET threshold, belong to space radiation effect simulation experiment technique and anti-radiation hardening technical field, solve the technical problem that device equivalent silicon layer thickness and single event upset LET threshold are difficult to obtain, its acquisition method includes obtaining average proton energy and LET value and range in silicon;Obtain the relationship curve of device single event upset cross section and average proton energy;Extract the energy upper and lower limit corresponding to the single event upset cross section peak of low-energy proton of device;Based on energy lower limit, the equivalent silicon layer thickness of device is calculated;Based on energy upper limit, the proton range, energy and LET value in the sensitive volume of device are calculated;Based on the proton higher than and closest to energy upper limit, the proton range, energy and LET value in the sensitive volume are calculated;The step of obtaining the LET threshold of device single event upset.The method can realize the accurate acquisition of device equivalent silicon layer thickness and single event upset LET threshold.

Description

Technical Field

[0001] This invention belongs to the fields of space radiation effect simulation experiment technology and radiation hardening technology, specifically involving a method for obtaining the equivalent silicon layer thickness of a device and the single-particle flip (LET) threshold. Background Technology

[0002] Heavy ions and protons in the space radiation environment are the main sources of single-event effects (SEE) in electronic devices. In SEE experiments on devices, it is typically necessary to perform Weibull function fitting based on experimental data of the device's heavy ion SEE cross-section to evaluate the device's SEE resistance and predict its on-orbit SEE rate. Since lower heavy ion LET values ​​result in higher flux in the space radiation environment, determining the LET threshold for heavy ion SEE is crucial for function fitting and on-orbit prediction. The LET threshold is the minimum LET value required for the device to exhibit SEE. Obtaining this value directly from heavy ion SEE experimental data is difficult, and relying on Weibull function fitting based on this data would introduce significant errors. Furthermore, with advancements in device technology, mounted devices now have multilayer metal wiring layers ranging from several micrometers to tens of micrometers above their sensitive areas, while flip-chip devices have silicon substrates hundreds of micrometers thick above their sensitive areas. This leads to a significant difference between the effective heavy ion LET value within the device's sensitive area and the LET value at the device surface. Experimenters often lack knowledge of the specific process information of the device, as well as the information of the metal wiring layer above the device's sensitive volume and the substrate. This makes it difficult to accurately determine the effective LET value of heavy ions reaching the device's sensitive volume in heavy ion single-event effect experiments. This will introduce a larger source of error for heavy ion experimental data with shorter ranges.

[0003] Therefore, based on the above problems and current situation, it is necessary to develop a new method for obtaining the equivalent silicon layer thickness of the device and the single-event flip (LET) threshold. As device technology advances to the nanoscale, the single-event flip critical charge decreases to below 1 fc, and the LET threshold drops to as low as 0.1 MeV·cm⁻¹. 2 / mg. Because the LET value of direct proton ionization does not exceed 0.55 MeV.cm 2 With a low energy loss ( / mg), it can effectively penetrate multiple metal wiring layers or thick substrates in flip-chip devices to reach the sensitive volume of the device. For nanodevices, low-energy protons with energies less than 1 MeV within the sensitive volume can induce high-cross-section single-event flips (LETs) through direct ionization. Based on this, a method is proposed to determine the equivalent silicon layer thickness above the sensitive volume and the LET threshold of the single-event flip based on experimental data of low-energy protons. This method has practical significance for scientifically evaluating the heavy-ion single-event resistance performance of devices and accurately predicting the on-orbit error rate.

[0004] Chinese invention patent CN100538378C discloses a method for obtaining the relationship between the single-event effect cross-section and the linear energy transfer of heavy ions. This invention provides an experimental method for measuring the single-event effect cross-section of heavy ions based on a heavy-ion accelerator testing device. Chinese invention patent CN112230081A discloses a method for calculating the equivalent LET value in pulsed laser single-event effect experiments. This invention provides a method for calculating the equivalent single-event effect cross-section of heavy ions with different LET values ​​using pulsed laser single-event experimental data. Chinese invention patent CN113109859A discloses a method for obtaining the single-event flip cross-section of heavy ions with low LET values. This invention provides a method for obtaining the single-event flip cross-section of low LET values ​​using low-energy proton experimental data. None of these three patents involve methods for obtaining the equivalent silicon layer thickness above the sensitive volume of the device and the single-event flip LET threshold using low-energy proton experimental data. Summary of the Invention

[0005] To overcome the difficulty in obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of a device, this invention proposes a method for obtaining the equivalent silicon layer thickness and the LET threshold of a device.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A method for obtaining the equivalent silicon layer thickness of a device and the single-event flip (LET) threshold includes the following steps:

[0008] Step S1: Calculate the average proton energy, the LET value in silicon, and the range.

[0009] Based on the device information, a proton accelerator and initial proton energy were selected. Using SRIM software, the average proton energy reaching the device surface after the initial proton energy passes through aluminum foil of different thicknesses, as well as the LET value and range in silicon, were calculated.

[0010] Step S2: Obtain the relationship curve between the single-particle flip-off cross section and the average proton energy of the device.

[0011] Experiments were conducted on the low-energy proton single-particle effect of the device to obtain the relationship curve between the single-particle flip-off cross section and the average proton energy.

[0012] Step S3: Extract the upper and lower energy limits corresponding to the low-energy proton single-particle flip cross-section peak of the device.

[0013] Based on experimental data of the low-energy proton single-particle effect of the device, the low-energy proton single-particle flip cross-section peak of the device was extracted, and the upper and lower limits of the proton energy corresponding to the cross-section peak were recorded.

[0014] Step S4: Calculate the equivalent silicon layer thickness of the device.

[0015] Based on the lower energy limit corresponding to the low-energy proton single-particle flip section peak and the silicon range corresponding to the lower energy limit, the equivalent silicon layer thickness above the sensitive volume of the device is calculated, i.e., the equivalent silicon layer thickness of the device.

[0016] Step S5: Calculate the proton range, energy, and LET value within the sensitive volume of the device at the upper energy limit.

[0017] Based on the upper limit of the energy corresponding to the low-energy proton single-particle flip section peak, the silicon range corresponding to the upper limit of the energy, and the equivalent silicon layer thickness of the device, the proton range, energy, and LET value reaching the sensitive volume of the device are calculated.

[0018] Step S6: Calculate the range, energy, and LET value of protons that are above and closest to the energy limit and reach the sensitive volume of the device.

[0019] Based on the proton energy that is higher than the upper limit of the single-particle flip section peak energy and closest to the upper limit, the corresponding range in silicon, and the equivalent silicon layer thickness of the device, the proton range, energy, and LET value reaching the sensitive volume of the device are calculated.

[0020] Step S7: Obtain the LET threshold for single-event flip of the device.

[0021] The LET value of the proton with the upper energy limit obtained in step S5 within the sensitive volume of the device is averaged with the LET value of the proton with the energy limit higher than and closest to the upper energy limit obtained in step S6 within the sensitive volume of the device to obtain the single-particle flip LET threshold of the device.

[0022] The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the above-mentioned device, wherein step S2 further includes:

[0023] In the experiment, based on the calculation results of step S1, protons with initial energy were made to pass through energy reduction plates of different thicknesses to reach the device surface, thereby obtaining different average proton energies at the device surface. The single-particle flip-off cross section of the device was measured sequentially from high to low proton energy. The formula for calculating the single-particle flip-off cross section σ is as follows:

[0024]

[0025] In the formula, σ is the single-particle flip cross section, N is the single-particle flip number, F is the incident proton fluence, and M is the device storage capacity.

[0026] The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the above-mentioned device, wherein step S4 further includes:

[0027] The equivalent silicon layer thickness of the device is: the silicon range corresponding to the lower limit of the peak energy of the low-energy proton single-particle flip section, minus the device sensitive volume thickness.

[0028] The method for obtaining the equivalent silicon layer thickness and single-particle flip (LET) threshold of the above-mentioned device, wherein the sensitive volume thickness of the device is 1 micrometer.

[0029] The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the above-mentioned device, wherein step S5 further includes:

[0030] Based on the upper limit of the energy corresponding to the low-energy proton single-particle flip section peak, and based on the calculation results of step S1, the silicon range corresponding to this upper limit of energy is obtained.

[0031] The silicon mid-range corresponding to the upper energy limit is subtracted from the equivalent silicon layer thickness of the device to obtain the silicon mid-range that reaches the sensitive volume of the device.

[0032] Using SRIM software, the proton energy and LET value corresponding to the silicon range of protons within the sensitive volume were calculated.

[0033] The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the above-mentioned device, wherein step S6 further includes:

[0034] Extract the proton energy that is higher than the upper limit of the single-particle flip section peak energy and closest to the upper limit of the energy. Based on the calculation results of step S1, obtain the silicon range corresponding to this energy.

[0035] The silicon range corresponding to the proton energy that is higher than the upper limit of the single-particle flip section peak energy and closest to the upper limit is subtracted from the equivalent silicon layer thickness of the device to obtain the proton silicon range that reaches the sensitive volume of the device.

[0036] Using SRIM software, the proton energy and LET value corresponding to the silicon range of protons within the sensitive volume were calculated.

[0037] The beneficial effects of this invention are:

[0038] A method for obtaining the equivalent silicon layer thickness and single-particle flip (LET) threshold of a device is provided. This method can obtain the equivalent silicon layer thickness above the sensitive volume of the device without performing longitudinal sectioning and scanning electron microscopy analysis, thereby accurately determining the effective LET value of heavy ions within the sensitive volume of the device and improving the accuracy of heavy ion experimental data.

[0039] A method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of a device is proposed. Based on low-energy proton single-event effect experiments on nanodevices, the method can accurately obtain the LET threshold of the device, reduce the dependence on heavy-ion accelerator beam conditions, and effectively improve the Weibull function fitting accuracy of heavy-ion experimental data. This method has important practical significance for scientifically evaluating the device's resistance to heavy-ion single-event effects and accurately predicting the on-orbit error rate. Attached Figure Description

[0040] Figure 1 This is a flowchart of the acquisition method according to Embodiment 2 of the present invention;

[0041] Figure 2 It is the curve showing the relationship between the low-energy proton single-particle flip-off cross section of the device and the average proton energy on the device surface. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] This invention discloses a method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of a device, comprising: calculating the average proton energy and its LET value and range in silicon after the initial proton energy passes through aluminum foil of different thicknesses to reach the device surface; conducting low-energy proton single-event effect experiments to measure the relationship curve between the single-event flip cross section and the average proton energy of the nanodevice; extracting the proton energy range and upper and lower limits corresponding to the peak of the low-energy proton single-event flip cross section of the device; subtracting the device sensitive volume thickness from the silicon range corresponding to the lower limit of the cross section peak energy to obtain the equivalent silicon layer thickness above the device sensitive volume; subtracting the equivalent silicon layer thickness from the silicon range corresponding to the upper limit of the cross section peak energy to calculate the proton range, energy, and corresponding LET value reaching the device sensitive volume; extracting the proton energy and silicon range that are higher than the upper limit of the cross section peak energy and closest to the upper limit of the energy, subtracting the equivalent silicon layer thickness, and calculating the proton range, energy, and corresponding LET value reaching the device sensitive volume; averaging the above two LET values ​​to obtain the device single-event flip (LET) threshold. This method can effectively improve the accuracy of experimental data on heavy-ion single-event effects and the accuracy of on-orbit prediction. Specifically, it includes the following steps:

[0045] Step S1: Select the proton accelerator and initial proton energy. Use SRIM software to calculate the average proton energy, LET value, and range in silicon after the initial proton energy passes through aluminum foils of different thicknesses, reaching the device surface. Specifically:

[0046] Based on a preliminary understanding of the device information, a suitable proton accelerator and initial proton energy were selected to conduct low-energy proton single-particle effect experiments on nanodevices.

[0047] Step S2 involves conducting low-energy proton single-particle effect experiments on nanodevices using a proton accelerator to obtain the relationship curve between the single-particle flip-off cross section and the average proton energy. Specifically:

[0048] In the experiment, based on the calculation results of step S1, protons with initial energy were made to pass through energy reduction plates of different thicknesses to reach the device surface, thereby obtaining different average proton energies at the device surface. The single-particle flip-off cross section of the device was measured sequentially from high to low proton energy. The formula for calculating the single-particle flip-off cross section σ is as follows:

[0049]

[0050] In the formula, σ is the single-particle flip cross section of the device, N is the single-particle flip number, F is the incident proton fluence, and M is the device storage capacity.

[0051] Step S3: Extract the low-energy proton single-particle flip cross-section peak of the device and record the proton energy range and upper and lower limits corresponding to the cross-section peak.

[0052] Step S4: Based on the lower energy limit corresponding to the low-energy proton single-particle flip section peak, and combined with the silicon range corresponding to this lower energy limit calculated in step S1, calculate the equivalent silicon layer thickness above the sensitive volume of the device. Specifically:

[0053] Subtracting the device sensitive volume thickness of 1 micrometer from the silicon range corresponding to the lower limit of the low-energy proton single-particle flip section peak energy calculated in step S1, the equivalent silicon layer thickness above the device sensitive volume can be obtained.

[0054] Step S5: Based on the upper energy limit corresponding to the low-energy proton single-particle flip section peak and the range in silicon, combined with the equivalent silicon layer thickness in step S4, calculate the proton range, energy, and corresponding LET value reaching the device's sensitive volume. Specifically:

[0055] 5.1) Based on the energy limit corresponding to the low-energy proton single-particle flip section peak, obtain the silicon range corresponding to the energy limit based on the calculation results of step S1.

[0056] 5.2) Subtract the equivalent silicon layer thickness obtained in step S4 from the silicon mid-range corresponding to the upper energy limit to obtain the silicon mid-range of protons within the sensitive volume of the device.

[0057] 5.3) Using SRIM software, calculate the proton energy and proton LET value corresponding to the range in proton silicon within the sensitive volume in 5.2).

[0058] Step S6: Extract the proton energy above the upper limit of the single-particle flip section peak energy and closest to the upper limit, along with the range in silicon. Combine this with the equivalent silicon layer thickness from step S4 to calculate the proton range, energy, and corresponding LET value reaching the device's sensitive volume. Specifically:

[0059] 6.1) Extract the proton energy that is higher than the upper limit of the single-particle flip section peak energy and closest to the upper limit of the energy, and obtain the silicon range corresponding to the energy based on the calculation results of step S1.

[0060] 6.2) Subtract the equivalent silicon layer thickness obtained in step S4 from the silicon mid-range in 6.1) to obtain the proton silicon mid-range that reaches the sensitive volume of the device.

[0061] 6.3) Using SRIM software, calculate the proton energy and proton LET value corresponding to the range in proton silicon within the sensitive volume in 6.2).

[0062] Step S7: Averaging the proton LET value obtained in step S5 and the proton LET value obtained in step S6 yields the LET threshold for single-particle flipping of the device.

[0063] Example 2

[0064] Figure 1 This is a flowchart of a method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of a device based on low-energy proton experimental data, according to the present invention. Figure 1 The steps of this method are described in detail.

[0065] Step S1: The device is a standard device. A low-energy proton accelerator is selected, and the initial proton energy is 1.2 MeV. The SRIM software is used to calculate the average proton energy, LET value and range in silicon of 1.2 MeV protons after passing through aluminum foils of different thicknesses. Table 1 shows the average proton energy and corresponding LET value and range in silicon of 1.2 MeV protons after passing through aluminum foils of different thicknesses.

[0066] Table 1

[0067]

[0068] Step S2: Conduct a low-energy proton single-event effect experiment. Use energy-degrading sheets of varying thicknesses to achieve rapid proton energy switching. Measure the relationship between the single-event flip cross-section and the average proton energy sequentially from high to low energy until no single-event flip occurs. (See [link to experiment]). Figure 2 .

[0069] Step S3: Extract the low-energy proton single-particle flip cross-section peak of the device and record the proton energy range corresponding to the cross-section peak as 0.67MeV to 0.83MeV, with an upper energy limit of 0.83MeV and a lower energy limit of 0.67MeV.

[0070] Step S4: The silicon range corresponding to the lower limit of the low-energy proton single-particle flip cross-section peak energy of 0.67 MeV in Table 1 of Step S1 is 9.0 micrometers. Subtracting the device sensitive volume thickness of 1 micrometer, the equivalent silicon layer thickness above the device sensitive volume is obtained as 8 micrometers.

[0071] Step S5: The silicon range corresponding to the upper limit of the low-energy proton single-particle flip cross-section peak energy of 0.83 MeV in Table 1 is 12.4 μm. Subtracting the equivalent silicon layer thickness of 8 μm from step S4, the silicon range of the proton reaching the device's sensitive region is 4.4 μm. Using SRIM software, the proton energy corresponding to the range of 4.4 μm is calculated to be 0.40 MeV, and the corresponding LET value is 0.284 MeV / cm. 2 / mg.

[0072] Step S6: The proton energy closest to the single-particle flip section peak energy limit is extracted as 0.88 MeV. In Table 1, this energy corresponds to a silicon range of 13.5 μm. Subtracting the equivalent silicon layer thickness of 8 μm obtained in step S4, the proton range in silicon reaching the device's sensitive region is 5.5 μm. Using SRIM software, the proton energy corresponding to the 5.5 μm range is calculated to be 0.47 MeV, with a corresponding LET value of 0.264 MeV / cm. 2 / mg.

[0073] Step S7, the proton LET value obtained in step S5 is 0.286 MeV.cm 2 / mg and the proton LET value obtained in step S6 is 0.264 MeV.cm 2 By averaging per mg, the LET threshold for single-particle flip (SPT) of the device can be obtained as 0.275 MeV.cm. 2 / mg.

Claims

1. A method for obtaining the equivalent silicon layer thickness of a device and the single-event flip (LET) threshold, characterized in that, Includes the following steps: Step S1: Calculate the average proton energy, LET value in silicon, and range. Based on the device information, a proton accelerator and initial proton energy were selected. Using SRIM software, the average proton energy reaching the device surface after the initial proton energy passes through aluminum foil of different thicknesses, as well as the LET value and range in silicon, were calculated. Step S2: Obtain the relationship curve between the single-particle flip-off cross section and the average proton energy of the device: Conduct low-energy proton single-particle effect experiments on the device to obtain the relationship curve between the single-particle flip-off cross section and the average proton energy. Step S3: Extract the upper and lower energy limits corresponding to the low-energy proton single-particle flip cross-section peak of the device: Based on experimental data of low-energy proton single-particle effect of the device, the low-energy proton single-particle flip cross-section peak of the device was extracted, and the upper and lower limits of proton energy corresponding to the cross-section peak were recorded. Step S4, calculate the equivalent silicon layer thickness of the device: The equivalent silicon layer thickness above the sensitive volume of the device is determined based on the lower energy limit corresponding to the low-energy proton single-particle flip section peak and the silicon range corresponding to the lower energy limit. Step S5: Calculate the proton range, energy, and LET value within the sensitive volume of the device at the upper energy limit: Based on the upper energy limit corresponding to the low-energy proton single-particle flip section peak, the silicon range corresponding to the upper energy limit, and the equivalent silicon layer thickness of the device, calculate the proton range, energy, and LET value within the sensitive volume of the device. Step S6: Calculate the range, energy, and LET value of the proton that is above and closest to the energy limit and reaches the sensitive volume of the device. Based on the proton energy that is higher than the upper limit of the single-particle flip section peak energy and closest to the upper limit, the corresponding silicon range, and the equivalent silicon layer thickness of the device, the proton range, energy, and LET value reaching the sensitive volume of the device are calculated. Step S7, obtain the LET threshold for single-event flip of the device: The LET value of the proton with the upper energy limit obtained in step S5 within the sensitive volume of the device is averaged with the LET value of the proton with the energy limit higher than and closest to the upper energy limit obtained in step S6 within the sensitive volume of the device to obtain the single-particle flip LET threshold of the device.

2. The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the device according to claim 1, characterized in that, Step S2 further includes: In the experiment, based on the calculation results of step S1, protons with initial energy were made to pass through energy reduction plates of different thicknesses to reach the device surface, thereby obtaining different average proton energies at the device surface. The single-particle flip-off cross section of the device was measured sequentially from high to low proton energy. The formula for calculating the single-particle flip-off cross section σ is as follows: In the formula, σ is the single-particle flip cross section, N is the single-particle flip number, F is the incident proton fluence, and M is the device storage capacity.

3. The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the device according to claim 1, characterized in that, Step S4 further includes: The equivalent silicon layer thickness of the device is: the range in silicon corresponding to the lower limit of the peak energy of the low-energy proton single-particle flip section. Subtract the thickness of the sensitive part.

4. The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the device according to claim 1, characterized in that, The device has a sensitive volume thickness of 1 micrometer.

5. The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the device according to claim 1, characterized in that, Step S5 further includes: Based on the upper limit of the energy corresponding to the low-energy proton single-particle flip section peak, and based on the calculation results of step S1, the silicon range corresponding to this upper limit of energy is obtained. Subtract the equivalent silicon layer thickness of the device from the silicon range corresponding to the upper energy limit to obtain the silicon range of protons reaching the sensitive volume of the device. Using SRIM software, the proton energy and LET value corresponding to the silicon range of protons within the sensitive volume were calculated.

6. The method for obtaining the equivalent silicon layer thickness and single-event flip (LET) threshold of the device according to claim 1, characterized in that, Step S6 further includes: Extract the proton energy that is higher than the upper limit of the single-particle flip section peak energy and closest to the upper limit of the energy. Based on the calculation results of step S1, obtain the silicon range corresponding to this energy. The silicon range corresponding to the proton energy that is higher than the upper limit of the single-particle flip section peak energy and closest to the upper limit is subtracted from the equivalent silicon layer thickness of the device to obtain the proton silicon range that reaches the sensitive volume of the device. Using SRIM software, the proton energy and LET value corresponding to the silicon range of protons within the sensitive volume were calculated.

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