Measuring device, measurement method, and measurement program

Abstract

To provide a technique that makes it possible to calculate an SER in a space proton environment at low cost.SOLUTION: A measuring device 10 includes an acceleration coefficient calculation unit 104 which, by assuming a proton SEU cross section as a neutron cross section in an energy range where a proton SEU (single event upset) cross section dependent on proton energy and a neutron SEU cross section dependent on neutron energy can be considered mutually the same value, calculates an index for converting the SER (soft error rate) by a neutron ray generated by a semiconductor device to the SER by a proton ray.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measurement device, a measurement method, and a measurement program. [Background technology]

[0002] Cosmic radiation emitted from the sun and galaxies flies around in space. Since the main component of cosmic radiation is protons, it is necessary to understand the effects of cosmic proton rays when operating semiconductor devices in space.

[0003] As a method for measuring the effect of cosmic proton rays on semiconductor devices on the ground, there is a method using a proton accelerator. In Non-Patent Document 1, a proton SEU cross section σ 2 where protons cause SEU (Single Event Upset) in semiconductor devices is measured using a proton accelerator. p Measure.

[0004] Measured proton SEU cross section σ p The proton flux φ that passes through the semiconductor device per unit time and unit area is p By multiplying this by 0 MeV and integrating it over the energy range of 0 MeV to infinity, the SER (Soft Error Rate: the number of SEUs / soft errors that occur per unit time) in a cosmic proton beam environment is calculated.

[0005]

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[0006] σ p (E) is the proton SEU cross section depending on the proton energy E. φ p (E) is the proton flux of proton energy E in the cosmic proton beam environment (= proton flux / proton energy spectrum = number of incident protons per unit time and unit area).

[0007] SEU is an event in which a single particle (neutron, proton, heavy particle, etc.) strikes a semiconductor device, causing a nuclear reaction to generate an electric charge, which inverts the data in the semiconductor device. SEU is also sometimes called a soft error.

[0008] The SEU cross section σ is the rate at which particles cause SEUs. In other words, it is the soft error occurrence rate when one particle passes through a semiconductor device per unit area. The SEU cross section σ is expressed by equation (2), where N is the number of SEUs that occur when a semiconductor device is irradiated with particles at a fluence Φ (the number of particles passing through per unit area).

[0009]

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[0010] The above method allows for evaluation of the effects of cosmic proton rays at the level of a single semiconductor device (for example, a single LSI). On the other hand, when evaluating the effects of cosmic proton rays at the level of an electronic system containing multiple semiconductor devices (for example, Figure 6-2 in Non-Patent Document 2), there is a method that uses neutrons, which have no electric charge.

[0011] In Patent Document 1, the proton SEU cross section σ p and neutron SEU cross section σ n From these measurements, the acceleration factor F A (An index for converting SER due to neutron beams to SER due to proton beams) is calculated in advance.

[0012]

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[0013] σ p (E p ) is the proton energy E p is the proton SEU cross section that depends on φ p (Ep ) is the proton energy E p is the proton flux of σ n (E n ) is the neutron energy E n is the neutron SEU cross section that depends on φ n (E n ) is the neutron energy E n Neutron flux (= neutron flux / neutron energy spectrum = number of neutrons incident per unit time and unit area) of the neutron SEU cross section σ n can be measured, for example, using the time-of-flight method of Patent Document 2.

[0014] Acceleration factor F A After calculating the SER, neutrons are irradiated from the accelerator neutron source to the electronic system to be measured, and the SER due to the accelerator neutron source in the electronic system is measured with the accelerator neutron source. The SER due to the measured accelerator neutron source and the acceleration factor F calculated in advance are used to calculate the SER. A Using this, the SER in the cosmic proton beam environment is calculated from the relationship of "SER due to accelerator neutron source / SER due to cosmic proton beam" in equation (3).

[0015] Neutrons have no electric charge, so they react very little with materials other than semiconductor devices (for example, the housing of a communications device). Therefore, even if multiple semiconductor devices mounted in multiple stages within an electronic system are irradiated with neutrons almost perpendicularly, the number of neutron particles is not affected. This makes it possible to evaluate the effects of cosmic proton rays on semiconductor devices at the electronic system level. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Japanese Patent Application Publication No. 2023-103746 [Patent Document 2] PCT / JP2020 / 026274 [Non-patent literature]

[0017] [Non-Patent Document 1] NA Dodds, et al., “The Contribution of Low-Energy Protons to the Total On-Orbit SEU Rate”, IEEE Transactions on Nuclear Science, Vol.62, No.6, December 2015, p.2440-p.2451 [Non-patent document 2] “SERIES K: PROTECTION AGAINST INTERFERENCE, Design methodologies for telecommunication systems applying soft error measures”, ITU-T, TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU, K.131, January 2022 Summary of the Invention [Problem to be solved by the invention]

[0018] However, in Patent Document 1, both proton irradiation experiments and neutron irradiation experiments are carried out, which is costly.

[0019] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a technology that can calculate the SER in a space proton beam environment at low cost. [Means for solving the problem]

[0020] A measurement device according to one embodiment of the present invention includes a calculation unit that calculates an index for converting the SER (Soft Error Rate) due to neutron rays generated in a semiconductor device to the SER due to proton rays, by regarding the proton SEU (Single Event Upset) cross-section, which depends on proton energy, as a neutron SEU cross-section in an energy range in which the proton SEU cross-section and the neutron SEU cross-section, which depends on neutron energy, can be considered equivalent to each other.

[0021] A measurement method according to one embodiment of the present invention is a measurement method performed using a measurement device, in which a proton SEU (Single Event Upset) cross-section, which depends on proton energy, and a neutron SEU cross-section, which depends on neutron energy, are considered equivalent to each other in an energy range in which the proton SEU cross-section is considered to be a neutron SEU cross-section, and an index is calculated for converting the SER (Soft Error Rate) due to neutron rays generated in a semiconductor device into the SER due to proton rays.

[0022] A measurement program according to one aspect of the present invention causes a computer to function as the measurement device. [Effects of the Invention]

[0023] According to the present invention, a technology can be provided that enables calculation of SER in a space proton beam environment at low cost. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram showing the overall configuration of the measurement system. [Figure 2A] FIG. 2A shows the measurement results of neutron SEU cross-section and proton SEU cross-section generated in an FPGA (28 nm). [Figure 2B] FIG. 2B shows the measurement results of neutron SEU cross-section and proton SEU cross-section generated in an FPGA (40 nm). [Figure 2C] FIG. 2C shows the measurement results of neutron SEU cross-section and proton SEU cross-section generated in an FPGA (55 nm). [Figure 3] FIG. 3 is a diagram showing a calculation flow of the acceleration coefficient. [Figure 4] FIG. 4 is a diagram showing a calculation flow of the SER. [Figure 5] FIG. 5 is a diagram illustrating the hardware configuration of the measurement device. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0026] [overview] The present disclosure provides a proton SEU cross section σ in the energy range where the proton SEU cross section and the neutron SEU cross section are considered equivalent to each other. p σ is the neutron SEU cross section n and the acceleration factor F A Calculate.

[0027] Since the acceleration factor can be calculated using only neutron irradiation experiments, proton irradiation experiments are no longer necessary, and soft error testing at the electronic system level can be performed using only neutron irradiation experiments, allowing the SER in a space proton beam environment to be calculated at low cost.

[0028] [Measurement system configuration] FIG. 1 is a diagram showing the overall configuration of a measurement system according to this embodiment.

[0029] The measurement system 1 is a system for measuring the effect of cosmic proton rays on semiconductor devices on the ground. The measurement system 1 includes a measurement apparatus 10, an accelerator neutron source 20, and an electronic system 30 incorporating a semiconductor device.

[0030] The measurement device 10 includes an input unit 101 , a soft error calculation unit 102 , an output unit 103 , and an acceleration factor calculation unit 104 .

[0031] The input unit 101 receives a neutron SEU cross section σ 1 depending on the neutron energy E, which is measured by irradiating the electronic system 30 with a neutron beam from the accelerator neutron source 20. n (E) has the function to obtain it.

[0032] The input unit 101 has a function of acquiring the SER due to the accelerator neutron source 20 (SER due to neutron beam) measured by irradiating the electronic system 30 to be measured with a neutron beam from the accelerator neutron source 20.

[0033] The soft error calculation unit 102 calculates the SER due to the accelerator neutron source 20 and the acceleration factor F A It has the function of calculating the SER in a cosmic proton beam environment (SER due to cosmic proton beams) using the above.

[0034] The output unit 103 has a function of outputting the SER in a space proton beam environment.

[0035] The acceleration coefficient calculation unit (calculation unit) 104 calculates the proton SEU cross section σ p and neutron SEU cross section σ n In the energy range where and can be considered equivalent to each other, the proton SEU cross section σ p σ is the neutron SEU cross section n Assuming that the acceleration factor of the cosmic proton beam environment is F A In other words, for the SEU cross section, the neutron SEU cross section σ, which depends on the energy E, is calculated in advance. n Use only (E).

[0036] Acceleration factor F of the cosmic proton beam environment A is an index for converting SER due to neutron rays generated in semiconductor devices in the electronic system 30 into SER due to cosmic proton rays. Specifically, it is an index that indicates how many times the accelerator environment of the accelerator neutron source 20 must be accelerated relative to the cosmic proton ray environment to test the soft error occurrence rate.

[0037] 2A to 2C show the cross-section σ of a neutron SEU generated in a field programmable gate array (FPGA) in the energy range of 0 MeV to approximately 800 MeV. n and proton SEU cross section σ p FIG.

[0038] From the figure, the proton SEU cross section σ p (○) indicates the neutron SEU cross section σ in the energy range above 20 MeV. n In the energy range below 20 MeV, the proton SEU cross section σ p decreases rapidly and can be considered to be 0 MeV.

[0039] Therefore, in this embodiment, in the energy range of 20 MeV to ∞ MeV, the proton SEU cross section σ p σ is the neutron SEU cross section n The acceleration coefficient calculation unit 104 calculates the acceleration coefficient F using the formula (4) obtained by improving the formula (3) in this way. A Calculate.

[0040]

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[0041] In equation (4), σ in equation (3) p (E p ) to σ n (E), and the integral range of the denominator has been changed to 20 MeV to ∞ MeV. n (E) is the neutron SEU cross section depending on the neutron energy E.

[0042] φ n,test (E) is the neutron flux of neutron energy E in the neutron irradiation test environment. p,space (E) is the proton flux with proton energy E in the cosmic proton beam environment. The neutron flux and proton flux are calculated in advance by measurements using detectors or simulations.

[0043] From equation (4), in the irradiation experiment, the neutron SEU cross section σ nOnly neutron irradiation experiments using an accelerator neutron source 20 are sufficient to measure the acceleration factor F A This makes it possible to calculate the proton irradiation experiment unnecessary.

[0044] [Calculation method of acceleration factor] FIG. 3 is a diagram showing a calculation flow of the acceleration coefficient.

[0045] Step S101; The accelerator neutron source 20 irradiates the electron system 30 with a neutron beam, and the neutron SEU cross section σ n (E) is measured.

[0046] Step S102; The acceleration factor calculation unit 104 of the measurement device 10 calculates the measured neutron SEU cross section σ n (E) into equation (4) to obtain the measured neutron SEU cross section σ n The acceleration factor F is calculated by multiplying (E) by a predetermined neutron flux and integrating it over the energy range 0 MeV to infinity, and dividing the result by the measured neutron SEU cross section multiplied by a predetermined proton flux and integrating it over the energy range 20 MeV to infinity. A Calculate φ n,test (E) and φ p,space (E) uses a pre-calculated value.

[0047] [Calculation method for SER in a space proton beam environment] FIG. 4 is a diagram showing the calculation flow of the SER in a space proton beam environment.

[0048] Step S201; The accelerator neutron source 20 irradiates a neutron beam onto the electronic system 30 to be measured, and the SER caused by the accelerator neutron source 20 is measured.

[0049] Step S202; The soft error calculation unit 102 of the measurement device 10 calculates the SER due to the measured accelerator neutron source 20 and the acceleration factor FA SER in the cosmic proton beam environment is calculated using the acceleration factor F A is used to convert the SER due to neutrons into the SER due to cosmic protons.

[0050] Acceleration factor F A As mentioned above, the acceleration factor F is an index that indicates how many times the accelerator environment of the accelerator neutron source 20 must be accelerated relative to the cosmic proton beam environment to test the soft error rate. For example, the acceleration factor F A is 10 million, and the SER by the accelerator neutron source 20 is 100 times per hour, A From the relationship "SER due to accelerator neutron source / SER due to cosmic proton beams", it is calculated that 100 soft errors will occur in 10 million hours (1 hour x 10 million) in an electronic system 30 in space.

[0051] Step S203; The output unit 103 of the measurement device 10 outputs the SER in the cosmic proton beam environment as a measurement result report to various devices (for example, a monitor device, a printer device, a server device, or a client device).

[0052] [effect] According to this embodiment, in the energy range in which the proton SEU cross section and the neutron SEU cross section can be regarded as equivalent, the proton SEU cross section is regarded as the neutron SEU cross section and the acceleration factor in the space proton beam environment is calculated in advance. This eliminates the need for proton irradiation experiments, allowing soft error testing at the electronic system level to be performed using only neutron irradiation experiments, and enabling the SER in the space proton beam environment to be calculated at low cost.

[0053] [others] The present invention is not limited to the above-described embodiment. Many modifications of the present invention are possible within the scope of the present invention. The measuring device 10 according to this embodiment can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0054] For example, the measuring device 10 according to this embodiment can be realized using a general-purpose computer system including a CPU 901, a memory 902, a storage 903, a communication device 904, an input device 905, and an output device 906, as shown in Fig. 5. The memory 902 and the storage 903 are storage devices. In this computer system, the CPU 901 executes a predetermined program loaded onto the memory 902, thereby realizing each function of the measuring device 10.

[0055] The measuring device 10 may be implemented by one computer. The measuring device 10 may be implemented by multiple computers. The measuring device 10 may be a virtual machine implemented on a computer. The program for the measuring device 10 may be stored in a computer-readable recording medium such as a HDD, SSD, USB memory, CD, or DVD. The program for the measuring device 10 may also be distributed via a communication network. [Explanation of symbols]

[0056] 1. Measurement system 10...Measuring equipment 101...input section 102...Soft error calculation unit 103...Output section 104...Acceleration coefficient calculation unit 20…Accelerator neutron source 30...Electronic Systems 901...CPU 902...Memory 903…Storage 904...Communication equipment 905...Input device 906...Output device

Claims

1. a calculation unit that calculates an index for converting a soft error rate (SER) caused by a neutron beam generated in a semiconductor device into a soft error rate (SER) caused by a proton beam, by regarding the proton SEU (Single Event Upset) cross section as a neutron SEU cross section in an energy range in which a proton SEU cross section dependent on proton energy and a neutron SEU cross section dependent on neutron energy can be regarded as equivalent to each other; A measuring device comprising:

2. The calculation unit 2. The measurement device of claim 1, wherein the index is calculated by multiplying the neutron SEU cross section by a predetermined neutron flux and integrating the result over an energy range of 0 MeV to infinity MeV, and dividing the result by a value obtained by multiplying the neutron SEU cross section by a predetermined proton flux and integrating the result over an energy range of 20 MeV to infinity MeV.

3. In a measurement method performed using a measurement device, In an energy range in which a proton SEU (Single Event Upset) cross section, which depends on proton energy, and a neutron SEU cross section, which depends on neutron energy, can be regarded as equivalent, the proton SEU cross section is regarded as a neutron SEU cross section, and an index for converting a neutron-induced soft error rate (SER) generated in a semiconductor device into a proton-induced SER is calculated. Measurement method.

4. A measurement program that causes a computer to function as the measurement device according to claim 1 or 2.

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