Measuring device, measuring method, and measurement program

Abstract

To provide a technique that enables accurate soft error testing of semiconductor devices at an electronic system level in a cosmic proton beam environment.SOLUTION: A measurement device 1 comprises a computation unit 12 configured to apply an acceleration coefficient of neutrons from an accelerator neutron source in a proton beam environment to a neutron-caused soft error occurrence rate in semiconductor devices within an electronic system as measured using the accelerator neutron source, and regard the soft error occurrence rate after the application of the acceleration coefficient as the soft error occurrence rate of the semiconductor devices in the cosmic proton beam environment.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a technique for measuring the influence of SEU (Single Event Upset) in a cosmic proton beam environment. SEU refers to an event in which a single particle (neutron, proton, heavy particle, etc.) impinges on a semiconductor device (LSI such as a memory), and the data stored inside is inverted by the charge generated by a nuclear reaction. SEU is also called a soft error.

Background Art

[0002] In outer space, cosmic rays generated from the sun and galaxies are flying around. Since the main component of cosmic rays is protons, it is necessary to understand the influence of proton beams when operating semiconductor devices in outer space.

[0003] When measuring the influence of cosmic proton beams on the ground, a proton accelerator is used. By measuring the rate at which protons generate SEU in a semiconductor device using a proton accelerator and multiplying it by the number of protons passing through per unit time and per unit area in that semiconductor device, the SER (Soft Error Rate; the number of SEU / soft errors generated per unit time) in a cosmic proton beam environment is calculated (Non-Patent Document 1).

[0004] Specifically, a proton SEU cross section is measured using a proton accelerator. Here, the SEU cross section is a measure representing the rate at which particles generate SEU in a semiconductor device. The SEU cross section σ of a particle is expressed by Equation (1), where N is the value of SEU generated when irradiating a semiconductor device with a fluence Φ [n / cm 2 (the total number of particles incident on a unit area).

[0005]

Equation

[0006] From Equation (1), the proton accelerator has a proton SEU cross section σ for protonsp Measure it. Then, using the measurement result of the proton SEU cross-section σ p the measuring device calculates SER in the cosmic proton beam environment from Equation (2).

[0007]

Equation

[0008] σ p (E) is the proton SEU cross-section at energy E. φ p (E) is the proton flux at energy E in the cosmic environment (the number of protons passing through per unit time and per unit area).

[0009] Conventionally, using the above method, a soft error test (measurement and evaluation of the SEU effect) at the semiconductor device level (single LSI) has been performed.

Prior Art Documents

Non-Patent Documents

[0010]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] However, when performing a soft error test at the electronic system level (e.g., a communication device) including semiconductor devices rather than at the semiconductor device level using protons, the protons react with substances other than semiconductor devices (e.g., a housing, a heat sink, a heat spreader), generating attenuation, secondary particles (e.g., neutrons), etc. Therefore, it has been difficult to perform a soft error test at the electronic system level using protons.

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique capable of accurately performing a soft error test of a semiconductor device in a cosmic proton beam environment at the electronic system level.

Means for Solving the Problems

[0013] A measuring device according to an aspect of the present invention includes an arithmetic unit that applies an acceleration coefficient of neutrons by the accelerator neutron source in a proton beam environment to a soft error occurrence rate in a semiconductor device in an electronic system measured by neutrons measured using the accelerator neutron source, and sets the soft error occurrence rate after application of the acceleration coefficient as the soft error occurrence rate of the semiconductor device in a cosmic proton beam environment.

[0014] A measuring method according to an aspect of the present invention includes, in a measuring method performed by a measuring device, a step of applying an acceleration coefficient of neutrons by the accelerator neutron source in a proton beam environment to a soft error occurrence rate in a semiconductor device in an electronic system measured by neutrons measured using the accelerator neutron source, and setting the soft error occurrence rate after application of the acceleration coefficient as the soft error occurrence rate of the semiconductor device in a cosmic proton beam environment.

[0015] A measurement program according to an aspect of the present invention causes a computer to function as the above-described measuring device.

Effects of the Invention

[0016] According to the present invention, it is possible to provide a technique capable of accurately performing a soft error test of a semiconductor device in a cosmic proton beam environment at the electronic system level.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same reference numerals are given to the same parts and the description thereof is omitted.

[0019] [Overview] The present invention focuses on neutrons.

[0020] Although the main component of cosmic radiation is protons, the soft error events caused by neutrons are the same events as those caused by protons. That is, regardless of the particle causing the event, the events that occur are the same. In addition, since neutrons do not have a charge, they can irradiate the semiconductor devices in the electronic system uniformly without depending on the mounting components of the electronic system and their positions.

[0021] Therefore, the present invention conducts a soft error test of an electronic system used in space using an accelerator neutron source. Specifically, when performing a soft error test on an electronic system equipped with a certain semiconductor device, the acceleration coefficient of neutrons in the cosmic proton beam environment is calculated using the energy-dependent SEU cross-section data of protons and neutrons, and applied to the test results of the soft error test at the electronic system level using neutrons from the accelerator neutron source.

[0022] [System Configuration] FIG. 1 is a diagram showing the overall configuration of the measurement system according to the present embodiment.

[0023] The measurement system 100 is a system that measures the influence of cosmic proton beams on the ground using neutrons. The measurement system 100 includes a measurement device 1, an accelerator neutron source 2, and an electronic system 3 incorporating a semiconductor device.

[0024] The measurement device 1 includes an input unit 11, an arithmetic unit 12, an output unit 13, and an acceleration coefficient arithmetic unit 14.

[0025] The acceleration coefficient arithmetic unit 14 has a function of calculating the acceleration coefficient of neutrons by the accelerator neutron source 2 in the cosmic proton beam environment using the proton SEU cross-section data dependent on proton energy, the proton flux of proton energy, the neutron SEU cross-section data dependent on neutron energy, and the neutron flux of neutron energy.

[0026] The input unit 11 has a function of inputting the neutron fluence when the accelerator neutron source 2 irradiates the semiconductor device in the electronic system 3 with neutron beams and the soft error occurrence rate in the semiconductor device in the electronic system 3 due to neutrons.

[0027] The calculation unit 12 applies the neutron acceleration factor calculated by the acceleration factor calculation unit 14 to the soft error occurrence rate in the semiconductor device within the electronic system 3 due to neutrons, and outputs the soft error occurrence rate to which the acceleration factor is applied as the soft error occurrence rate of the semiconductor device in the cosmic proton beam environment.

[0028] The output unit 13 has a function of outputting the soft error occurrence rate of the semiconductor device in the cosmic proton beam environment to a monitoring device or the like.

[0029] [Method for Calculating Acceleration Factor] FIG. 2 is a diagram showing the calculation flow of the acceleration factor.

[0030] Steps S101, S102; First, the proton accelerator measures the proton SEU cross section of a single semiconductor device that depends on the proton energy. Next, the accelerator neutron source 2 measures the neutron SEU cross section of a single semiconductor device that depends on the neutron energy.

[0031] The measurement of the proton SEU cross section can be carried out using existing technologies as described above. The measurement of the neutron SEU cross section can also be carried out using existing technologies. For example, the neutron SEU cross section can be measured using the time-of-flight method. Specifically, a determination circuit that outputs a value different from the normal state when an SEU occurs in a semiconductor element is formed in the semiconductor device, and in a neutron radiation environment, the neutron SEU cross section is calculated based on the number of abnormal operations that occurred in the determination circuit.

[0032] Step S103; Thereafter, in the measuring device 1, the acceleration factor calculation unit 14 uses the proton SEU cross section that depends on the proton energy, the proton flux of that proton energy, the neutron SEU cross section that depends on the neutron energy, and the neutron flux of that neutron energy, and from Equation (3), the acceleration factor F A is calculated.

[0033]

Number

[0034] σ p (E p ) is the proton SEU cross-section of proton energy E p (p:proton). φ p (E p ) is the proton flux of proton energy E p . σ n (E n ) is the neutron SEU cross-section of neutron energy E n (n:neutron). φ n (E n ) is the neutron flux of neutron energy E n .

[0035] Acceleration coefficient F A is an index indicating how many times the neutron accelerator environment (accelerator neutron source 2) can accelerate neutrons for a soft error test with respect to the cosmic proton beam environment.

[0036] Note that the above calculation flow is an example. For example, step S102 may be performed before or simultaneously with step S101. Also, for the proton SEU cross-section and the neutron SEU cross-section, if there is existing data, the acceleration coefficient F A may be calculated without performing steps S101 and S102 and using those existing data.

[0037] [Method for calculating soft error occurrence rate] Figure 3 is a diagram showing the calculation flow of the soft error occurrence rate.

[0038] Step S201; First, the accelerator neutron source 2 irradiates neutrons on the electronic system 3 including the semiconductor device that is the measurement target of the soft error occurrence rate, and measures the soft error occurrence rate in the semiconductor device in the electronic system 3 due to the neutrons.

[0039] Here, the simulation results when irradiating a semiconductor device in an electronic system with neutron beams are shown in FIG. 4. In this simulation, an 80 [MeV] neutron beam was irradiated onto the electronic system, and the number of protons and neutrons in LSI1 and LSI2 was calculated. To simulate the electronic system, stainless steel as the housing, heat sink, heat spreader, LSI, and printed circuit board are reproduced.

[0040] FIG. 4(a) shows the number of each particle irradiated onto the front-side LSI1 in response to the input of the neutron beam. FIG. 4(b) shows the number of each particle irradiated onto the rear-side LSI2. There was almost no change in the number of irradiated particles for both LSI1 and LSI2, and they were almost the same regardless of the irradiation position of the particles. From this result, it can be seen that neutrons can irradiate the semiconductor device in the electronic system uniformly and do not depend on the mounting position of the electronic system components. Therefore, by using neutrons, the soft error test of the semiconductor device in the cosmic proton beam environment can be accurately carried out at the electronic system level.

[0041] The simulation results when irradiating the same simulation system with a proton beam are shown in FIG. 5. In LSI1, it can be seen that the peak of the protons, which was originally 80 [MeV], has decayed to 28 [MeV] due to the influence of stainless steel, heat sink, etc. Also, it can be seen that protons react with various parts of the electronic system and neutrons are generated. Furthermore, in the rear-side LSI2, the influence becomes greater, and it can be seen that the numbers of protons and neutrons are reversed. Thus, it is difficult to conduct a test at the electronic system level using protons.

[0042] Step S202; Thereafter, in the measuring device 1, the input unit 11 inputs the soft error occurrence rate in the semiconductor device in the electronic system 3 measured by the accelerator neutron source 2, and outputs the soft error occurrence rate to the calculation unit 12.

[0043] Then, the arithmetic unit 12 applies the acceleration coefficient F to the soft error rate A and outputs to the output unit 13 the soft error rate to which the acceleration coefficient F A is applied, as the soft error rate of the semiconductor device in the cosmic proton beam environment.

[0044] For example, when the acceleration coefficient F A is 10 million and the soft error rate in the accelerator neutron source 2 is 100 times per hour, the arithmetic unit 12 predicts and calculates that soft errors will occur 100 times in 10 million hours (1 hour × 10 million) in space.

[0045] After that, the output unit 13 inputs the soft error rate into the failure number report generated in the cosmic proton beam environment and outputs it to various devices (for example, a monitor device, a printing device, a server device, a client device).

[0046] [Effect] According to the present embodiment, the measuring device 1 applies the acceleration coefficient of neutrons by the accelerator neutron source in the proton beam environment to the soft error rate of the semiconductor device in the electronic system 3 measured by using the accelerator neutron source, and has the arithmetic unit 12 that sets the soft error rate after the application of the acceleration coefficient as the soft error rate of the semiconductor device in the cosmic proton beam environment. Therefore, the soft error test of the semiconductor device in the cosmic proton beam environment can be accurately and inexpensively performed at the electronic system level.

[0047] [Others] The present invention is not limited to the above embodiment. The present invention can be modified in various ways within the scope of the gist of the present invention. The measuring device 1 according to the present embodiment can also be realized by a computer and a program, and it is also possible to record the program on a recording medium or provide it through a network.

[0048] For example, as shown in FIG. 6, the measuring device 1 according to the present embodiment can be realized by 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. The memory 902 and the storage 903 are storage devices. In the computer system, each function of the measuring device 1 is realized by the CPU 901 executing a predetermined program loaded on the memory 902.

[0049] The measuring device 1 may be implemented by one computer. The measuring device 1 may be implemented by a plurality of computers. The measuring device 1 may be a virtual machine implemented on a computer. The program for the measuring device 1 can be stored in a computer-readable recording medium such as an HDD, an SSD, a USB memory, a CD, or a DVD. The program for the measuring device 1 can also be distributed via a communication network.

Explanation of Reference Numerals

[0050] 1... Measuring device 11... Input unit 12... Arithmetic unit 13... Output unit 14... Acceleration coefficient arithmetic unit 2... Accelerator neutron source 3... Electronic system 100... Measurement system 901... CPU 902... Memory 903... Storage 904... Communication device 905... Input device 906... Output device

Claims

1. An arithmetic unit that applies an acceleration coefficient of neutrons by the accelerator neutron source in a proton beam environment to the soft error occurrence rate in a semiconductor device in an electronic system measured by neutrons using the accelerator neutron source, and sets the soft error occurrence rate after application of the acceleration coefficient as the soft error occurrence rate of the semiconductor device in a cosmic proton beam environment. A measuring device comprising the same.

2. The measuring device according to claim 1, further comprising an acceleration coefficient calculation unit that calculates the acceleration coefficient using a proton SEU (Single Event Upset) cross section depending on proton energy and a neutron SEU cross section depending on neutron energy measured using the accelerator neutron source.

3. In a measuring method performed by a measuring device, a step of applying an acceleration coefficient of neutrons by the accelerator neutron source in a proton beam environment to the soft error occurrence rate in a semiconductor device in an electronic system measured by neutrons using the accelerator neutron source, and setting the soft error occurrence rate after application of the acceleration coefficient as the soft error occurrence rate of the semiconductor device in a cosmic proton beam environment. A measuring method for performing the same.

4. A measurement program for causing a computer to function as the measuring device according to claim 1 or 2.

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