Sensible Domain Inference Method

Abstract

This technology provides a method for estimating the sensitive region of semiconductor devices. [Solution] In a sensitive region estimation method for estimating the sensitive region of an SEU (Single Event Upset), the radiation irradiation device 10 performs a first step of irradiating a semiconductor device to be measured with a plurality of different radiations, and a second step of comparing the SEU occurrence rates of each radiation generated in the semiconductor device to be measured with each other and calculating the relative magnitudes of the radiations in relation to the SEU occurrence rate. The sensitive region estimation device 20 performs a third step of using information showing the relationship between the amount of energy loss and the penetration depth for each radiation in the semiconductor device to calculate the penetration depth at which the relative magnitudes of the radiations in relation to the amount of energy loss match the relative magnitudes of the radiations in relation to the SEU occurrence rate, and a fourth step of estimating the said penetration depth as the sensitive region of the semiconductor device to be measured.

Description

Technical Field

[0001] The present disclosure relates to a method for estimating a sensitive region.

Background Art

[0002] When radiation is incident on a semiconductor device, the energy imparted by the radiation ionizes a part of the semiconductor device and becomes electrical noise. This electrical noise causes single event upset (SEU) in which the bit information in the semiconductor device is inverted.

[0003] To prevent the occurrence of SEU, it is conceivable to use a radiation shielding material. However, in order to effectively utilize the radiation shielding material, it is necessary to know the sensitive region (for example, the memory region by charge) in the semiconductor device where SEU is likely to occur.

[0004] Therefore, conventionally, the semiconductor device was destroyed and the sensitive region was visually recognized (see Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, since the semiconductor device was destroyed and the sensitive region was visually recognized, human error occurred in the detection accuracy of the sensitive region.

[0007] This disclosure is made in view of the above circumstances and aims to provide a technology that can estimate the sensitive region of a semiconductor device. [Means for solving the problem]

[0008] A sensitive region estimation method according to one aspect of the present disclosure is a sensitive region estimation method for estimating the sensitive region of a Single Event Upset (SEU), comprising: a first step in which a radiation irradiation device irradiates a semiconductor device to be measured with a plurality of different radiations; a second step in which the SEU occurrence rate of each radiation generated in the semiconductor device to be measured is compared with one another and the relative magnitudes of the radiations with respect to the SEU occurrence rate is calculated; a third step in which the sensitive region estimation device uses information showing the relationship between the amount of energy loss and the penetration depth for each radiation in the semiconductor device to calculate a penetration depth in which the relative magnitudes of the radiations with respect to the amount of energy loss match the relative magnitudes of the radiations with respect to the SEU occurrence rate; and a fourth step in which the penetration depth is estimated as the sensitive region of the semiconductor device to be measured. [Effects of the Invention]

[0009] This disclosure provides a technology capable of estimating the sensitive region of a semiconductor device. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows an example of the configuration of a sensitive area estimation system. [Figure 2] Figure 2 shows an example of a sensitive area. [Figure 3] Figure 3 shows the processing flow of the radiation irradiation device. [Figure 4] Figure 4 shows an example of the relative magnitudes of radiation with respect to the SEU cross-section. [Figure 5] Figure 5 shows the processing flow of the sensitive area estimation device. [Figure 6] Figure 6 shows an example of the estimation of the sensitive area. [Figure 7]Figure 7 shows the processing flow of the sensitive area estimation device according to Example 1. [Figure 8] Figure 8 shows an example of excluding the sensitive area according to Example 1. [Figure 9] Figure 9 shows an example of estimating the sensitive area according to Example 1. [Figure 10] Figure 10 shows an example of exclusion and estimation of the sensitive area according to Example 2. [Figure 11] Figure 11 shows an example of the hardware configuration of a sensitive area estimation device. [Modes for carrying out the invention]

[0011] Embodiments of this disclosure will be described below with reference to the drawings.

[0012] [Summary of this disclosure] When radiation enters a semiconductor device, it interacts with the atomic nuclei within the device, propagating while transferring some of its energy to the device.

[0013] The energy imparted by radiation to a semiconductor device changes moment by moment at each position (penetration depth) along the radiation's path within the semiconductor device, depending on the energy of the incident radiation and the degree of interaction with the semiconductor device.

[0014] In this process, the energy supplied by radiation ionizes a portion of the semiconductor device, creating electrical noise and generating SEUs. An SEU is an event in which a single radiation particle enters an LSI (Large Scale Integration) and the resulting charge generated by a nuclear reaction inverts the bit information within the LSI. SEUs are also known as soft errors.

[0015] Therefore, the SEU-sensitive region in a semiconductor device is likely to be correlated with the amount of energy of radiation lost (energy loss amount) per unit traveling path length (unit penetration depth). Also, the energy loss amount changes each time depending on the penetration depth of the radiation in the semiconductor device, and it is considered that the likelihood of SEU occurrence (SEU occurrence degree) also changes depending on the penetration depth of the radiation. Furthermore, the energy loss amount and the SEU occurrence degree differ depending on the radionuclide and energy of the radiation.

[0016] Therefore, the present disclosure discloses a method for obtaining the penetration depth in which the magnitude relationship between radiations regarding the energy loss amount matches the magnitude relationship between radiations regarding the SEU occurrence degree, and estimating the obtained penetration depth as the sensitive region of the semiconductor device to be measured.

[0017] Hereinafter, the likelihood of SEU occurrence when radiation is incident on a semiconductor device is referred to as the SEU cross-sectional area. The SEU cross-sectional area has a value that depends on the radionuclide and energy of the incident radiation for each semiconductor device.

[0018] [Configuration of Sensitive Region Estimation System] FIG. 1 is a diagram showing a configuration example of a sensitive region estimation system according to the present embodiment.

[0019] The sensitive region estimation system 1 includes a radiation irradiation device 10, a sensitive region estimation device 20, and a database 30. [[ID=2,0]]

[0020] The radiation irradiation device 10 includes an irradiation unit 11, a measurement unit 12, a calculation unit 13, and a storage unit 14. [[ID=&]]

[0021] The irradiation unit 11 has a function of irradiating the semiconductor device 100 to be measured with a plurality of radiations having different radionuclides and / or energies respectively.

[0022] The measurement unit 12 has a function of measuring the amount of SEU occurrence for each radiation generated in the semiconductor device 100 to be measured.

[0023] The calculation unit 13 has the function of determining the SEU cross-section for each radiation from the SEU generation amount for each radiation, that is, converting the SEU generation amount of each radiation into an SEU cross-section, comparing the SEU cross-sections of each radiation with one another, and calculating the relative magnitudes of the radiations in terms of SEU cross-section.

[0024] The storage unit 14 has the function of storing all data and information handled by the radiation irradiation device 10 in a readable format.

[0025] A radiation irradiation device 10 equipped with such functions can, for example, utilize an existing radiation irradiation machine. It may also be implemented by combining an existing radiation irradiation machine with a computer.

[0026] The sensitive area estimation device 20 is connected to the radiation irradiation device 10 via wired and / or wireless communication. The sensitive area estimation device 20 comprises an acquisition unit 21, an estimation unit 22, an output unit 23, and a storage unit 24.

[0027] The acquisition unit 21 has the function of acquiring SEU generation amount information for each radiation and magnitude relationship information between radiations regarding SEU cross-sectional area from the radiation irradiation device 10.

[0028] The acquisition unit 21 has the function of acquiring from the database 30 energy loss information showing the relationship between the amount of energy loss and penetration depth for each type of radiation in a semiconductor device (not shown in Figure 1), and residual energy information showing the relationship between the residual energy and penetration depth for each type of radiation in a semiconductor device (not shown in Figure 1).

[0029] The estimation unit 22 has a function to calculate the penetration depth in which the relative magnitudes of radiation with respect to energy loss match the relative magnitudes of radiation with respect to SEU cross-section, using energy loss information.

[0030] The estimation unit 22 has the function of estimating (determining) the calculated penetration depth as the sensitive region of the semiconductor device 100 to be measured. An example of the sensitive region of the semiconductor device 100 is shown in Figure 2.

[0031] The estimation unit 22 uses residual energy information to calculate the penetration depth at which the residual energy of radiation becomes zero for radiation with zero SEU generation, and has a function to exclude penetration depths shallower than that penetration depth from the felt region.

[0032] The estimation unit 22 uses residual energy information to calculate the penetration depth at which the residual energy of radiation becomes zero for radiation whose SEU generation is not zero, and excludes penetration depths greater than that depth from the sensitive region.

[0033] The output unit 23 has a function to output the sensitive region (including the range of the sensitive region) of the semiconductor device 100 to be measured.

[0034] The memory unit 24 has the function of storing all data and information handled by the sensitive area estimation device 20 in a readable format.

[0035] A sensitive area estimation device 20 with such functions can be realized, for example, using a computer.

[0036] Database 30 is a database such as SRIM (The Stopping and Range of Ions in Matter) located on the communication network 40. Database 30 publishes the energy loss and residual energy theoretically predicted from the radionuclides and / or energies of the radiation.

[0037] [Operation of the radiation irradiation device] Figure 3 shows the processing flow of the radiation irradiation device 10.

[0038] The irradiation unit 11 irradiates the semiconductor device 100 to be measured with radiation of a predetermined nuclide and predetermined energy (step S101).

[0039] The measurement unit 12 measures the amount of SEU generated by the semiconductor device 100 to be measured and stores the measured amount of SEU in the storage unit 14 (step S102).

[0040] The measurement unit 12 determines whether or not the semiconductor device 100 to be measured has been irradiated with radiation of all required nuclides and energies (step S103). If not all radiation has been irradiated, the process returns to step S101.

[0041] If all radiation is being applied, the calculation unit 13 reads the SEU generation amount for each radiation from the storage unit 14 and converts the read SEU generation amount for each radiation into an SEU cross-sectional area for each radiation (step S104).

[0042] The calculation unit 13 compares the SEU cross-sections of each radiation with each other, calculates the relative magnitudes of the radiations in relation to their SEU cross-sections, and stores the calculated relative magnitudes of the radiations in relation to their SEU cross-sections in the storage unit 14 (step S105).

[0043] Figure 4 shows an example of the relative magnitudes of radiation with respect to the SEU cross-section. When semiconductor device 100 is irradiated with radiation 1 to 3, the relative magnitudes obtained are "SEU cross-section 1 > SEU cross-section 2 > SEU cross-section 3". In this case, the relative magnitudes of radiation with respect to the SEU cross-section are calculated as "radiation 1 > radiation 2 > radiation 3".

[0044] [Sensible area estimation device operation] Figure 5 shows the processing flow of the sensitive area estimation device 20.

[0045] The acquisition unit 21 acquires information on the relative magnitudes of radiation radiation with respect to the SEU cross-sectional area from the radiation irradiation device 10 (step S201).

[0046] The acquisition unit 21 acquires energy loss amount information from the database 30 (step S202).

[0047] The estimation unit 22 compares the relative magnitudes of radiation with respect to energy loss included in the energy loss information with the relative magnitudes of radiation with respect to SEU cross-section, and calculates the penetration depth at which these two types of relative magnitudes coincide (step S203).

[0048] The estimation unit 22 estimates the calculated penetration depth as the sensitive region of the semiconductor device 100 to be measured (step S204).

[0049] An example of estimating the sensitive region is shown in Figure 6. For radiation 1 to 3, which were exemplified in Figure 4, the amount of energy loss with respect to penetration depth is exemplified. In the case of the energy loss amounts exemplified in Figure 6, the penetration depth that matches the order of magnitude between radiation with respect to the SEU cross-section, "radiation 1 > radiation 2 > radiation 3", is in the range of D.

[0050] In other words, since the amount of energy loss from radiation changes each time depending on the penetration depth of the radiation within the semiconductor device, it is thought that the SEU cross-section also changes depending on the penetration depth of the radiation. Therefore, it is estimated that the sensitive region exists at the penetration depth where the relative magnitudes of the two coincide.

[0051] If the accuracy of the estimated sensitive area is low, steps S101 to S105 and steps S201 to S204 are repeated until the required accuracy is achieved.

[0052] [Example 1] Example 1 describes the case where radiation from multiple radionuclides is applied.

[0053] For example, let's consider the case where semiconductor device 100 is irradiated with H, C, Ar, and Kr radiation, respectively. In this case, the relative magnitudes of the radiations in terms of SEU cross-section are "Ar > C > H", and the amount of SEU generated by Kr is zero.

[0054] Figure 7 shows the processing flow of the sensitive area estimation device 20 according to Example 1.

[0055] The acquisition unit 21 acquires information on the amount of SEU generated for each radiation and information on the relative magnitudes of radiations in relation to the SEU cross-sectional area from the radiation irradiation device 10 (step S301).

[0056] The acquisition unit 21 acquires residual energy information and energy loss amount information from the database 30 (step S302).

[0057] The acquisition unit 21 uses the SEU generation amount information for each radiation to determine whether or not there is any radiation with an SEU generation amount of zero (step S303).

[0058] If there is radiation that generates zero SEU, the estimation unit 22 uses residual energy information to exclude penetration depths shallower than the penetration depth at which the residual energy of the radiation becomes zero from the sensitive region (step S304).

[0059] If there is no radiation that results in zero SEU generation, the estimation unit 22 uses residual energy information to exclude penetration depths deeper than the penetration depth at which the residual energy of the radiation becomes zero from the sensitive region (step S305).

[0060] Figure 8 shows an example of the exclusion of the sensitive region performed in steps S304 and S305. The residual energy of H, C, Ar, and Kr radiation with respect to penetration depth is illustrated. The values ​​calculated by SRIM after injecting H (65 MeV), C (320 MeV), Ar (520 MeV), and Kr (322 MeV) radiation into Si are shown.

[0061] Since the SEU generation amount for Kr is zero, in step S304, the D1 region is excluded from the candidate for the sensitive region. Since SEUs were generated for H, C, and Ar radiation, in step S305, the D2 region, which is deeper than the penetration depth at which the residual energy becomes zero for each of those radiations, is also excluded.

[0062] The estimation unit 22 compares the relative magnitudes of radiation with respect to energy loss included in the energy loss information with the relative magnitudes of radiation with respect to the SEU cross-section, and determines whether it is possible to calculate an penetration depth within the range of remaining penetration depths after the above exclusions in which the two types of relative magnitudes coincide (step S306).

[0063] If the penetration depth can be calculated, the estimation unit 22 estimates the calculated penetration depth as the sensitive region of the semiconductor device 100 to be measured (step S307).

[0064] Figure 9 shows an example of estimating the sensitive region. The energy loss amounts (derivative values ​​of residual energy shown in Figure 8) for each type of radiation, H, C, Ar, and Kr, with respect to penetration depth are exemplified. In the case of the energy loss amounts exemplified in Figure 9, the penetration depth that corresponds to the order of magnitude between radiation with respect to the SEU cross-section, "Ar > C > H", is in the range of D.

[0065] If the penetration depth cannot be calculated, the estimation unit 22 terminates the process without estimating the sensitive region of the semiconductor device 100 to be measured.

[0066] [Example 2] Example 2 describes the case where a single nuclide is irradiated with radiation of multiple energies.

[0067] For example, let's consider the case where a semiconductor device 100 is irradiated with C radiation having different initial energies (320 MeV, 220 MeV, and 75 MeV). In this case, SEU generation occurs only when irradiated with C(320 MeV), and the amount of SEU generated is zero for C(220 MeV) and C(75 MeV).

[0068] In Example 2, the same processing procedure as in Example 1 is performed.

[0069] The acquisition unit 21 obtains the residual energy of each radiation for a given penetration depth from the database 30. Figure 10 illustrates the residual energy of C radiation for a given penetration depth. The values ​​shown are those calculated by SRIM after C(320MeV), C(220MeV), and C(75MeV) radiation were incident on Si.

[0070] When irradiated with C(220MeV) and C(75MeV), the SEU generation is zero, so the D1 region where residual energy exists is excluded from the list of candidates for the sensitive region. When irradiated with C(320MeV), an SEU was generated, so there is a high possibility that residual energy is not zero, and the D2 region is also excluded from the list of candidates for the sensitive region.

[0071] In this case, since only one radiation source generated a SEU, the remaining penetration depth range D after the above exclusion becomes the sensitive region. Thus, when an SEU is detected with only one energy irradiation, the sensitive region can be estimated simply by confirming the range where residual energy exists, without referring to the amount of energy loss.

[0072] [effect] According to this embodiment, the radiation irradiation device 10 irradiates the semiconductor device 100 to be measured with a plurality of different radiations, compares the SEU cross-section (SEU generation rate) of each radiation generated in the semiconductor device 100 to calculate the relative magnitudes of the radiations in relation to the SEU cross-section, and the sensitive region estimation device 20 uses energy loss information showing the relationship between the energy loss amount and penetration depth for each radiation in the semiconductor device to calculate the penetration depth at which the relative magnitudes of the radiations in relation to the energy loss amount match the relative magnitudes of the radiations in relation to the SEU cross-section, and estimates the calculated penetration depth as the sensitive region of the semiconductor device 100 to be measured, thus providing a technology that can estimate the sensitive region of a semiconductor device.

[0073] Users interested in the SEU cross-section are likely to conduct radiation testing. In this embodiment, the depth of the sensitive region can be secondarily determined by utilizing such originally planned radiation testing opportunities.

[0074] Unlike conventional technologies, this embodiment allows for non-destructive estimation of the sensitive region. Therefore, there is no need to purchase extra semiconductor devices. Furthermore, human errors that occur during destructive measurement are eliminated.

[0075] Another method for estimating the sensitive region is numerical simulation that assumes the internal structure of the semiconductor device. However, this increases the number of assumptions, making it difficult to verify the validity of the results. In this embodiment, the device under inspection itself is used as the detector, thus reducing the number of assumptions and minimizing uncertainty.

[0076] In a radiation testing facility, for example, an aluminum plate may be placed between the radiation beam port and the semiconductor device to adjust (increase or decrease) the energy of the radiation irradiating the semiconductor device. By performing irradiation with a single nuclide and multiple energies, as shown in Example 2, while slightly changing the energy using an aluminum plate or the like, it is possible to obtain estimation results of the sensitive region with the accuracy desired by the user.

[0077] [others] This disclosure is not limited to the embodiments described above. This disclosure can be modified in numerous ways within the scope of its essence.

[0078] For example, the processing in the calculation unit 13 of the radiation irradiation device 10 may be handled by the sensitive area estimation device 20. In other words, the radiation irradiation device 10 only performs radiation irradiation and measurement of SEU generation, while all other calculation processing is performed by the sensitive area estimation device 20.

[0079] The sensitive area estimation device 20 of this embodiment described above can be realized using a general-purpose computer system, for example, as shown in Figure 11, which includes a CPU 901, a memory 902, a storage device 903, a communication device 904, an input device 905, and an output device 906. The memory 902 and the storage device 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 sensitive area estimation device 20.

[0080] The sensitive area estimation device 20 may be implemented on a single computer. The sensitive area estimation device 20 may be implemented on multiple computers. The sensitive area estimation device 20 may also be a virtual machine implemented on a computer.

[0081] The program for the sensitive area estimation device 20 can be stored on a computer-readable recording medium such as an HDD, SSD, USB memory, CD, or DVD. A computer-readable recording medium is, for example, a non-transitory recording medium. The program for the sensitive area estimation device 20 can also be distributed via a communication network. [Explanation of symbols]

[0082] 1. Sensible Area Estimation System 10 Radiation irradiation equipment 11 Irradiation area 12 Measuring part 13 Calculation section 14 Storage section 20 Sensitive area estimation device 21 Acquisition Department 22 Estimation part 23 Output section 24 Memory section 30 databases 40 Communication Networks 100 Semiconductor Devices 901 CPU 902 memory 903 Storage 904 Communication equipment 905 Input device 906 Output device

Claims

1. In a method for estimating the sensitive region of a Single Event Upset (SEU), The radiation irradiation device, The first step involves irradiating the semiconductor device to be measured with multiple different types of radiation, The second step involves comparing the SEU generation rates for each radiation emitted in the semiconductor device being measured and calculating the relative magnitudes of the radiations in relation to the SEU generation rates. The sensitive area estimation device A third step involves using information showing the relationship between the amount of energy loss for each type of radiation and the penetration depth in a semiconductor device to calculate the penetration depth at which the relative magnitudes of the radiations in terms of energy loss match the relative magnitudes of the radiations in terms of SEU occurrence. A fourth step is to estimate the penetration depth as the sensitive region of the semiconductor device to be measured. Sensitive area estimation method.

2. In step 3 described above, A method for estimating a sensitive region according to claim 1, which uses information showing the relationship between the residual energy and penetration depth for each type of radiation in a semiconductor device, calculates the penetration depth at which the residual energy of radiation becomes zero for radiation that generates zero SEU, and excludes penetration depths shallower than that penetration depth from the sensitive region.

3. In step 3 described above, A method for estimating a sensitive region according to claim 1, which uses information showing the relationship between the residual energy and penetration depth for each type of radiation in a semiconductor device, calculates the penetration depth at which the residual energy of radiation becomes zero for radiation whose SEU generation is not zero, and excludes penetration depths greater than that penetration depth from the sensitive region.

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