Method for evaluating radiation resistance of semiconductor device under test using heavy ions and pulsed laser

Abstract

A method for evaluating radiation resistance of a semiconductor device under test according to the present invention may comprise the steps of: providing a semiconductor device under test to a heavy ion device to measure a cross-section (σ) value of the semiconductor device under test according to a linear energy transfer (LET) value in a base interval; providing the semiconductor device under test to a pulsed laser device and measuring the cross-section value of the semiconductor device under test according to a laser energy value; and converting the laser energy value provided to the pulsed laser device into a corresponding linear energy transfer value to estimate the cross-section value of the semiconductor device under test according to the linear energy transfer value in intervals other than the base interval.

Description

Radiation resistance evaluation method for semiconductor devices under test using heavy ions and pulsed lasers

[0001] The present invention relates to a method for evaluating radiation resistance of a semiconductor device under test using heavy ions and a pulsed laser, and more specifically, to a method for evaluating radiation resistance of a semiconductor device under test by inferring the cross-sectional area value of the semiconductor device under test using heavy ion equipment and a pulsed laser equipment.

[0002] Outer space is a region where various radiation particles are widely distributed, including cosmic rays propagating from galaxies and various charged particles generated by the sun. In contrast, the Earth is protected from a significant amount of radiation due to the Earth's magnetic field lines. Therefore, measurements and other measures must be performed in outer space to protect semiconductor devices from these various radiation particles.

[0003] Since semiconductors used in spacecraft may be subject to Single-Event Effects (SEE), which refer to momentary malfunctions caused by collisions with high-energy particles, and Total Ionizing Dose (TID), where leakage current occurs, threshold voltage values ​​change, and degradation occurs depending on the degree of exposure as the number of traps in insulating films increases, it is mandatory to conduct a radiation resistance evaluation and use only products that have passed it.

[0004] In particular, evaluations such as radiation resistance to heavy ions and TID (Total Ionizing Dose) are essential. Satellites orbiting in polar orbits must intensively analyze heavy ions, and in the case of satellites orbiting in equatorial orbits, TID.

[0005] Since TID is evaluated using gamma rays and the like, there are almost no restrictions on facility usage and preparing the facilities is relatively easy, so there are no difficulties in evaluation; however, heavy ions require a large accelerator. Currently, the number of institutions possessing large heavy ion accelerators is limited, and heavy ion equipment in Korea capable of semiconductor measurement does not satisfy the internationally accepted range of linear energy transfer values.

[0006] As the space industry shifts its focus toward the private sector and the frequency of launches of various types of spacecraft increases, the demand for radiation resistance assessments is rising; however, expanding assessment facilities requires a significant amount of time. Consequently, securing opportunities to use these facilities for assessment is becoming increasingly difficult. Not only is there a shortage of facilities, but it is also becoming harder to obtain measurement opportunities because Europe and the United States prioritize domestic allocation, while countries like Japan operate in a closed manner. Furthermore, internationally, political issues such as various regulations involving China and Russia have made these facilities inaccessible to private companies.

[0007] Equipment is relatively easier to use in Europe than in the United States. To address the difficulties in using large heavy ion accelerators, the European Space Components Coordination (ECSS) SEE evaluation method and guidelines (ESCC Basic Specification No. 25100, pp. 19-21) suggest the possibility of using alpha particles and lasers as alternative sources. For example, Korean Registered Patent Publication 10-2514258 discloses a semiconductor device inspection device comprising a stage on which a semiconductor device to be tested is placed, a support table supporting the stage, an alpha particle source placed on the stage to irradiate a beam containing alpha particles onto the semiconductor device to be tested, and a beam control unit placed adjacent to the stage to control the irradiation angle of the beam irradiated from the alpha particle source, wherein the beam control unit includes a magnetic body embedded within the upper region of the support table, and the magnetic body includes a first region that overlaps with the alpha particle source and a second region that does not overlap with the alpha particle source.

[0008] The technical problem that the present invention aims to solve is to provide a method for evaluating the radiation resistance of a semiconductor device under test, wherein the inferred cross-sectional area value of the semiconductor device under test has high reliability.

[0009] Another technical problem that the present invention aims to solve is to provide a method for evaluating the radiation resistance of a semiconductor device under test that can overcome the limitations of heavy ion equipment, which is not internationally accepted due to the narrow range of linear energy transfer (LET) values ​​provided.

[0010] Another technical problem that the present invention aims to solve is to provide a method for evaluating the radiation resistance of an analog semiconductor device under test using heavy ions and a pulsed laser.

[0011] Another technical problem that the present invention aims to solve is to provide a method for improving the precision of evaluating radiation resistance characteristics of an analog semiconductor device under test.

[0012] Another technical problem that the present invention aims to solve is to provide an evaluation method that can obtain the effect of using heavy ion equipment with a wide linear energy transfer value range (providing not only the LET for the base section but also the LET for a section other than the base section) by using heavy ion equipment with a narrow linear energy transfer value range (providing only the LET for the base section).

[0013] The technical problems that the present invention aims to solve are not limited to those described above.

[0014] To solve the above technical problem, the present invention provides a method for evaluating radiation resistance of a semiconductor device under test.

[0015] According to one embodiment, the method comprises the steps of: providing a semiconductor device to be tested to a heavy ion device and measuring the cross-sectional area (σ) of the semiconductor device to be tested according to the linear energy transfer (LET) value of the base section; providing the semiconductor device to be tested to a pulse laser device and measuring the cross-sectional area value of the semiconductor device to be tested according to the laser energy value; and using the cross-sectional area value of the semiconductor device to be tested according to the laser energy value, inferring the cross-sectional area value of the semiconductor device to be tested according to the linear energy transfer value of the remaining section excluding the base section, wherein the base section may include a range of linear energy transfer values ​​that the heavy ion device can provide due to the characteristics of the heavy ion device.

[0016] According to one embodiment, the heavy ion equipment includes providing the linear energy transfer value of the base section, and unlike the heavy ion equipment, the internationally accepted heavy ion equipment includes equipment that provides the linear energy transfer value of the base section and the remaining section, and the internationally accepted heavy ion equipment may include being able to provide the linear energy transfer value of 60 LET or more to the semiconductor device under test.

[0017] According to one embodiment, the method may include providing the semiconductor device under test to the internationally accepted heavy ion equipment and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section and the remainder section, and deriving a correlation between the laser energy value and the linear energy transfer value by using the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value measured in the internationally accepted heavy ion equipment and the cross-sectional area value of the semiconductor device under test according to the laser energy value measured in the pulse laser equipment.

[0018] According to one embodiment, the relationship between the laser energy value and the linear energy transfer value may vary depending on the laser light source of the pulse laser equipment.

[0019] According to one embodiment, the laser light source of the pulse laser equipment is single photon absorption (SPA) and the relationship between the laser energy value and the linear energy transfer value is linearly proportional, and the laser light source of the pulse laser equipment is two photon absorption (non-linear absorption) and the linear energy transfer value is proportional to the power of the laser energy value.

[0020] According to one embodiment, the method may include a step of providing the semiconductor device under test to the heavy ion equipment to measure the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section, wherein at least one of the threshold energy value or the saturation cross-section value of the semiconductor device under test is not confirmed, and a step of providing the semiconductor device under test to the pulse laser equipment to measure the cross-sectional area value of the semiconductor device under test according to the laser energy value, and a step of converting the laser energy value of the pulse laser equipment into the linear energy transfer value to infer the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section excluding the base section, wherein at least one of the threshold energy value or the saturation cross-section value of the semiconductor device under test is inferred.

[0021]

[0022] To solve the above technical problems, the present invention provides a method for evaluating radiation resistance of an analog semiconductor device under test.

[0023] According to one embodiment, the method for evaluating radiation resistance of the analog semiconductor device under test comprises the steps of: providing the analog semiconductor device under test to a heavy ion device to obtain a first graph representing a first cross-sectional value of the analog semiconductor device under test according to a linear energy transfer (LET) value of the base section; providing the analog semiconductor device under test to a pulse laser device to derive a second cross-sectional value of the semiconductor device under test according to a laser energy value, deriving an equivalent linear energy transfer value using the second cross-sectional value, and obtaining a second graph representing the second cross-sectional value according to the equivalent linear energy transfer value; and obtaining an integrated graph by combining the first graph and the second graph, and deriving the first cross-sectional value of the remaining section excluding the base section from the integrated graph, wherein the base section may be a range of the linear energy transfer value that the heavy ion device can provide due to the characteristics of the heavy ion device.

[0024] According to one embodiment, the analog semiconductor device under test may include any one of a comparator, an operational amplifier (OP-AMP), a bandgap reference, an LDO regulator, an analog-to-digital converter (ADC), and an analog switch.

[0025] According to one embodiment, the first cross-sectional area value may be derived according to the following <Equation 6>.

[0026] <Mathematical Formula 6>

[0027]

[0028] (σ: the first cross-sectional area value, NSET1 : The number of events generated from the analog semiconductor device under test when heavy ions are irradiated onto the analog semiconductor device under test, wherein the event is one in which the voltage deviation in the output waveform is greater than or equal to a reference voltage deviation, φ beam : Number of heavy ion particles irradiated onto the above-mentioned analog semiconductor device per unit area)

[0029] According to one embodiment, the second cross-sectional area value may be derived according to the following <Equation 7>.

[0030] <Mathematical Formula 7>

[0031]

[0032] (σ Laser : The above second cross-sectional area value, N SET2 : The number of events generated from the analog semiconductor device under test when a laser is irradiated onto the analog semiconductor device under test, wherein the event is one in which the voltage deviation in the output waveform is greater than or equal to a reference voltage deviation, N Pulse : Total number of laser pulses irradiated onto the above-mentioned analog semiconductor device under test)

[0033] According to one embodiment, the equivalent linear energy transfer value may be derived differently depending on whether the laser light source of the pulse laser equipment is single photon absorption (SPA) or two photon absorption, wherein when the laser light source is single photon absorption, it is derived according to <Equation 8> and <Equation 8-1> below, and when it is two photon absorption, it is derived according to <Equation 9> and <Equation 9-1> below.

[0034] <Mathematical Formula 8>

[0035]

[0036] (LET LASER_SPA: The above equivalent linear energy transfer value, α: single photon absorption proportionality constant, E: laser energy, z: depth of laser penetration from the surface of the above analog semiconductor device under test)

[0037] <Mathematical Formula 8-1>

[0038]

[0039] (LET LASER_SPA : The above equivalent linear energy transfer value, A: Single photon absorption correction factor, E: Laser energy, α s : Surface absorption coefficient, α: Single photon absorption proportionality constant, E: Laser energy, z: Depth of laser penetration from the surface of the analog semiconductor device under test)

[0040] <Mathematical Formula 9>

[0041]

[0042] (LET LASESR_TPA : The above equivalent linear energy transfer value, β2: nonlinear absorption proportionality constant, E: laser energy, ω0: angular frequency, τ: pulse time, α: single photon absorption proportionality constant, z: depth of laser penetration from the surface of the above analog semiconductor device under test, S(z, z foc ): Energy spatial distribution function of a focused pulsed laser)

[0043] <Mathematical Formula 9-1>

[0044]

[0045] (LET LASESR_TPA : The above equivalent linear energy transfer value, B: Nonlinear absorption correction factor, E: Laser energy, β T : Nonlinear absorption proportionality constant, S: Energy spatial distribution function of the focused pulsed laser, ω0: Angular frequency, τ: Pulse time)

[0046] According to one embodiment, the following <Equation 10> may be applied to the integrated graph to derive the first cross-sectional area value of the remaining section excluding the base section.

[0047] <Mathematical Formula 10>

[0048]

[0049] (σ(x): The first cross-sectional area value of a specific section among the remaining sections excluding the base section, σ sat : Saturation values ​​of the first cross-sectional area value and the second cross-sectional area value within the integrated graph above, P w : Width of the rise interval between the first cross-sectional area value and the second cross-sectional area value within the integrated graph above, X: Specific linear energy transfer value, X th : Linear energy transfer value at the point where the first cross-sectional area value and the second cross-sectional area value within the above integrated graph change from 0 to a positive value, s: Shape factor of the Weibull distribution representing the rate of change of the slope of the above integrated graph)

[0050] A method for evaluating radiation resistance of a semiconductor device under test according to the present invention may include the steps of: providing the semiconductor device under test to a heavy ion device to measure the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of a base section (e.g., 10 LET or more and 40 LET or less); providing the semiconductor device under test to a pulse laser device to measure the cross-sectional area value of the semiconductor device under test according to the laser energy value; and using the cross-sectional area value of the semiconductor device under test according to the laser energy value to infer the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section excluding the base section (e.g., less than 10 LET or more than 40 LET).

[0051] The cross-sectional area value of the semiconductor device under test, measured according to the laser energy value using the pulse laser equipment, and the linear energy transfer value of the base section and the remaining section can be compared using internationally accepted heavy ion equipment capable of providing the linear energy transfer value to the semiconductor device under test.

[0052] Accordingly, the correlation between the laser energy value and the linear energy transfer value is derived, and the laser energy value can be easily converted into a converted linear energy transfer value such that it corresponds to the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section and the remaining section.

[0053] Accordingly, the cross-sectional area value of the semiconductor device under test corresponding to the converted linear energy transfer value can be displayed as a discontinuous graph. Accordingly, the cross-sectional area value of the semiconductor device under test corresponding to the linear energy transfer value of the remaining section, which could not be measured by the heavy ion equipment, can be easily inferred.

[0054] The inferred cross-sectional area value of the semiconductor device under test can have high reliability because it is substantially identical to the cross-sectional area value of the semiconductor device under test measured using the internationally accepted heavy ion equipment.

[0055] In addition, by fitting the above discontinuous graph into a continuous graph using the Weibull fitting method, the threshold energy value and / or saturation cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section that could not be verified by the heavy ion equipment can be easily calculated.

[0056] The calculated threshold energy value and / or saturation cross-sectional area value match the threshold energy value and / or saturation cross-sectional area value of the semiconductor device under test measured using the internationally accepted heavy ion equipment, so it can have high reliability.

[0057] FIG. 1 is a flowchart for explaining a method for evaluating radiation resistance of a semiconductor device under test according to a first embodiment of the present invention.

[0058] FIG. 2 is a drawing for explaining a method for evaluating radiation resistance of a semiconductor device under test according to a first embodiment of the present invention.

[0059] FIG. 3 is a flowchart illustrating a method for evaluating radiation resistance of an analog semiconductor device under test according to a second embodiment of the present invention.

[0060] FIG. 4 is a graph for comparing the cross-sectional area value measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value inferred by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 1.

[0061] FIG. 5 is a graph for comparing the cross-sectional area value measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value inferred by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 2.

[0062] Figure 6 is a graph for comparing the correlation between linear energy transfer values ​​and laser energy values ​​for each semiconductor under test in the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 3 and Experimental Example 4 of the present invention.

[0063] Figure 7 is a graph showing the cross-sectional area values ​​inferred by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 3 of the present invention.

[0064] FIG. 8 is a graph for comparing the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 1.

[0065] FIG. 9 is a graph for comparing the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 5.

[0066] FIG. 10 is a graph for comparing the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 5 of the present invention with the cross-sectional area value inferred by the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 6.

[0067] FIG. 11 is a graph for explaining the characteristics of an analog single-event transient waveform occurring in an analog semiconductor device under test according to an embodiment of the present invention.

[0068] FIG. 12 is a graph illustrating the change in cross-sectional area according to laser energy based on the input voltage difference of an analog semiconductor device under test according to an embodiment of the present invention.

[0069] FIG. 13 is a graph illustrating the change in an analog single-event transient waveform according to the injection laser energy in an analog semiconductor device under test according to an embodiment of the present invention.

[0070] FIG. 14 is a graph illustrating the waveform characteristics and distribution changes of an analog single-event transient observed under the same laser irradiation energy conditions in an analog semiconductor device under test according to an embodiment of the present invention.

[0071] FIG. 15 is a graph showing the pulse characteristic distribution of a single event transient according to the change in injection energy when the input voltage conditions are different in an analog comparator element under test according to an embodiment of the present invention.

[0072] FIG. 16 is a diagram illustrating the phenomenon in which the location and magnitude of an analog single-event transient changes depending on the polarity change of the input voltage difference in an analog comparator element according to an embodiment of the present invention.

[0073] FIG. 17 is a diagram showing the circuit configuration of a DUT board equipped with a comparator element ISL7119 used in a single-event effect test evaluation according to an embodiment of the present invention.

[0074] FIG. 18 is a diagram illustrating the configuration of a heavy ion irradiation device for performing a single event effect test according to an embodiment of the present invention, and the arrangement of measuring equipment and a test target board.

[0075] FIG. 19 is a diagram illustrating the configuration of a SRAM SEE evaluation control system according to an embodiment of the present invention.

[0076] FIG. 20 is a diagram showing the configuration of a Comparator SEE evaluation control system according to an embodiment of the present invention.

[0077] FIG. 21 is a diagram showing the results of analyzing the cross-sectional structure of a comparator according to an embodiment of the present invention using a scanning electron microscope.

[0078] FIG. 22 is a graph showing a comparison of the results of measuring an analog single-event transient waveform according to an embodiment of the present invention in different heavy ion irradiation environments.

[0079] FIG. 23 is a graph showing the change in the cross-sectional area of ​​an analog single-event transient according to an embodiment of the present invention, compared with the linear energy transition of heavy ions and the input overdrive voltage.

[0080] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete, and to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art.

[0081] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the films and regions are exaggerated for the effective description of the technical content.

[0082] Additionally, although terms such as first, second, third, etc. have been used to describe various components in various embodiments of this specification, these components should not be limited by such terms. Accordingly, what is referred to as the first component in one embodiment may be referred to as the second component in another embodiment.

[0083] Each embodiment described and exemplified herein also includes its complementary embodiment. Additionally, the term 'and / or' in this specification is used to mean including at least one of the components listed before and after it.

[0084] In the specification, singular expressions include plural expressions unless the context clearly indicates otherwise. Furthermore, terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, components, or combinations thereof described in the specification, and should not be understood as excluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0085] In addition, in describing the present invention below, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0086]

[0087] FIG. 1 is a flowchart for explaining a method for evaluating radiation resistance of a semiconductor device under test according to a first embodiment of the present invention, and FIG. 2 is a diagram for explaining a method for evaluating radiation resistance of a semiconductor device under test according to a first embodiment of the present invention.

[0088] Referring to FIGS. 1 and 2, a semiconductor device under test is provided to a heavy ion device, and the cross-sectional area (σ) of the semiconductor device under test is measured according to the linear energy transfer (LET) value of the base section (S100).

[0089] In the specification of this application, the heavy ion equipment refers to equipment capable of providing the linear energy transfer value of the base section to the semiconductor device under test due to the characteristics of the heavy ion equipment. For example, the heavy ion equipment may be the 6MV heavy ion equipment owned by the Korea Institute of Science and Technology (KIST) in Korea.

[0090] Furthermore, internationally accepted heavy ion equipment refers to equipment capable of providing linear energy transfer values ​​for the base section and the remaining section excluding the base section. For example, the internationally used heavy ion equipment includes RADEF (RADiation Effects Facility, in Finland), TAMU (Texas A&M Univ.) REF (Radiation Effects Facility Heavy Ion Testing, in USA), BNL (Brookhaven National Laboratory, in USA), LBNL (Lawrence Berkeley National Laboratory, in USA), FRIB (Facility for Rare Isotope Beams, at MSU in USA), GANIL (Grand Accιlιrateur National d'Ions Lourds, in France), CYCLONE (CYClotron of Lovain la NEuvs, in Netherlands), KVI-CART (Kernfysisch Versneller Instituut-Center for Advanced Radiation Technology, in Netherlands), GSI (Gesellschaft fur Schwerionenforschung, in Germany), CERN Heavy ion (in Switzerland & France), HIF-UCL (Heavy Ions Facility-Universitι It could be any one of the following: Catholique de Louvain, in Belgium.

[0091] And, in the specification of the present application, the cross-sectional area value of the device under test refers to the number of errors occurring in the semiconductor device under test.

[0092] According to one embodiment, σ of the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value can be expressed by the following <Equation 1>. For example, the semiconductor device under test may be a semiconductor device that can be used in a space environment. For example, the semiconductor device under test may include Cypress SRAM and ISSI SRAM.

[0093] <Mathematical Formula 1>

[0094]

[0095] In the above <Mathematical Formula 1>, N SEU Is When the linear energy transfer value is provided to the semiconductor device under test provided to the heavy ion equipment, it is the number of errors detected in the semiconductor device under test, and φ beam represents the linear energy transfer value provided to the semiconductor device under test provided to the heavy ion equipment above.

[0096] In addition, due to the characteristics of the heavy ion equipment, the linear energy transfer value of the base section may be 10 LET or more and 40 LET or less. As another example, the linear energy transfer value of the base section may be 13 LET or more and 40 LET or less. As yet another example, the linear energy transfer value of the base section may be 9 LET or more and 45 LET or less.

[0097] Accordingly, as shown in Fig. 2(c), the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section can be measured using the heavy ion equipment.

[0098] However, it may be impossible to measure the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section using the heavy ion equipment. Accordingly, within the range of the linear energy transfer value of the remaining section, at least one of the threshold energy value and the saturation cross-section value associated with errors and malfunctions of the semiconductor device under test in a space environment may not be confirmed.

[0099] Referring to FIGS. 1 and 2, the semiconductor device under test is provided to a pulse laser device, and the cross-sectional area value of the semiconductor device under test is measured according to the laser energy value (S200).

[0100] According to one embodiment, the cross-sectional area value (σ) of the semiconductor device under test according to the laser energy value Laser ) can be expressed as the following <Mathematical Formula 2>.

[0101] <Mathematical Formula 2>

[0102]

[0103] According to the above <Mathematical Formula 2>, the cross-sectional area value of the semiconductor device under test can be measured according to the laser energy value provided to the semiconductor device under test. For example, the pulse laser equipment may be a femtosecond pulse laser. For example, the pulse width of the pulse laser equipment may be 100 to 500 fs. For example, the laser light source of the pulse laser equipment may be single photon absorption (SPA) or nonlinear absorption two photon absorption. Accordingly, depending on the laser light source of the pulse laser equipment, the cross-sectional area value of the semiconductor device under test according to the laser energy value may be measured differently.

[0104] In addition, using the above internationally accepted heavy ion equipment, the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section and the remainder section can be measured as shown in FIG. 2(a). For example, the base section may be 10 LET or more and 40 LET or less. For example, the remainder section may be less than 10 LET and greater than 40 LET.

[0105] Accordingly, by comparing the cross-sectional area value of the semiconductor device under test (Fig. 2(a)) based on the linear energy transfer value measured by the internationally accepted heavy ion equipment with the cross-sectional area value of the semiconductor device under test based on the laser energy value measured by the pulse laser equipment, a correlation between the laser energy value and the linear energy transfer value can be derived.

[0106] The reason the linear energy transfer value of the internationally accepted heavy ion equipment and the laser energy value of the pulsed laser equipment have a correlation is that the linear energy transfer value provided to the semiconductor device under test by the internationally certified heavy ion equipment affects the electron-hole pairs (EHPs) generated on the substrate of the semiconductor device under test, thereby influencing the operation of the semiconductor device under test, and the laser energy value provided to the semiconductor device under test by the pulsed laser equipment affects the electron-hole pairs generated on the substrate of the semiconductor device under test, thereby influencing the operation of the semiconductor device under test, are similar to each other.

[0107] As described above, since the cross-sectional area value of the semiconductor device under test is measured differently depending on the laser light source of the pulse laser equipment, the correlation between the linear energy transfer value of the internationally accepted heavy ion equipment and the laser energy value of the pulse laser equipment may differ.

[0108] According to one embodiment, when the laser light source of the pulse laser equipment undergoes single photon absorption (SPA), the linear energy transfer value may be linearly proportional to the laser energy value. Specifically, the correlation between the laser energy value and the linear energy transfer value can be expressed by the following <Equation 3>.

[0109] <Mathematical Formula 3>

[0110]

[0111] In the above <Equation 3>, α is a single photon absorption proportionality constant, E is laser energy, e is an exponential function, and z may be a beam incident in the z-axis direction. Accordingly, the above <Equation 3> can be simplified into the following <Equation 3-1>.

[0112] <Mathematical Formula 3-1>

[0113]

[0114] In the above <Mathematical Formula 3-1>, the above α s ε₀ may be a single-photon absorption proportionality constant. Therefore, according to <Equation 3> and <Equation 3-1> above, when the laser light source of the pulse laser equipment is a single-photon absorber, it can be seen that the correlation between the laser energy value and the linear energy transfer value is linearly proportional.

[0115] According to one embodiment, when the laser light source of the pulse laser equipment is a nonlinear absorption two-photon, the linear energy transfer value may be proportional to the power of the laser energy value. Specifically, the correlation between the laser energy value and the linear energy transfer value can be expressed by the following <Equation 4>.

[0116] <Mathematical Formula 4>

[0117]

[0118] In the above <Equation 4>, β2 is the nonlinear absorption proportionality constant, E is the laser energy, ω0 is the angular frequency (e.g., 2πV0, where V0 is the frequency (Hz)), τ is the pulse time (e.g., ~100fs), and S(z,z foc ) is the energy spatial distribution function of a focused pulsed laser, and z foc ε₀ may be the vertical distance (e.g., z-axis) from the surface of the pulsed laser light source to the focused position on the surface of the semiconductor device under test. Accordingly, the above <Equation 4> can be simplified into the following <Equation 4-1>.

[0119] <Mathematical Formula 4-1>

[0120]

[0121] In the above <Mathematical Formula 4-1>, β T ε is a nonlinear absorption proportionality constant, and S can be the energy spatial distribution function of a focused pulsed laser. Therefore, according to <Equation 4> and <Equation 4-1> above, when the laser light source of the pulsed laser equipment is a nonlinear absorption two-photon, it can be seen that the correlation between the laser energy value and the linear energy transfer value is proportional to the power of the power.

[0122] Accordingly, by utilizing the correlation between the laser energy value and the linear energy transfer value, the laser energy value can be converted into a converted linear energy transfer value (Equivalent LET) such that it corresponds to the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section and the remainder section.

[0123] Referring to FIGS. 1 and 2, the cross-sectional area value of the semiconductor device under test according to the laser energy value is used to infer the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section excluding the base section (S300).

[0124] Generally, if the linear energy transfer value provided to the semiconductor device under test is the same, the cross-sectional area value of the semiconductor device under test is measured to be the same.

[0125] Accordingly, among the cross-sectional area values ​​of the semiconductor device under test according to the laser energy value measured from step S200, the cross-sectional area value of the semiconductor device under test corresponding to the converted linear energy transfer value can be shown as a discontinuous graph, as illustrated by the blue solid line in (d) of FIG. 2. Therefore, the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section that the heavy ion equipment could not measure can be inferred.

[0126] And, using the following <Equation 5>, the above discontinuous graph can be fitted into a continuous graph. For example, the above <Equation 5> may be a general mathematical formula for Weibull fitting.

[0127] <Mathematical Formula 5>

[0128]

[0129] In the above <Equation 5>, F(χ) is the inferred cross-sectional area value of the semiconductor device under test, A is the saturation cross-section, the χ-axis is a variable corresponding to the energy value (e.g., Linear Energy Transfer Value (LET)), χ0 is the stopping power threshold, and P w is a width parameter, and s is a dimensionless exponent, which is a coefficient that determines the shape of the overall curve. Accordingly, the discontinuous graph representing the cross-sectional area value of the semiconductor device under test corresponding to the transformed linear energy transfer value can be fitted into a continuous graph by <Equation 5>. Accordingly, at least one of the threshold energy value at which an error occurs depending on the energy value provided to the semiconductor device under test in the remaining section, which was difficult to verify using the heavy ion equipment, and the saturated cross-sectional area value at which an error no longer occurs and saturation occurs as the energy value provided to the semiconductor device under test increases can be easily calculated.

[0130] In conclusion, the method for evaluating radiation resistance of the semiconductor device under test according to an embodiment of the present application may include the steps of: providing the semiconductor device under test to the heavy ion equipment to measure the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section; providing the semiconductor device under test to the pulse laser equipment to measure the cross-sectional area value of the semiconductor device under test according to the laser energy value; and using the cross-sectional area value of the semiconductor device under test according to the laser energy value to infer the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section excluding the base section.

[0131] The cross-sectional area value of the semiconductor device under test, measured according to the laser energy value using the pulse laser equipment, and the cross-sectional area value of the semiconductor device under test, measured according to the linear energy transfer value using the internationally accepted heavy ion equipment capable of providing the linear energy transfer value of the base section and the remaining section, can be compared.

[0132] Accordingly, the correlation between the laser energy value and the linear energy transfer value is derived, and the laser energy value can be easily converted into the converted linear energy transfer value so that it corresponds to the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section and the remaining section.

[0133] Accordingly, the cross-sectional area value of the semiconductor device under test corresponding to the converted linear energy transfer value can be displayed on the discontinuous graph. Accordingly, the cross-sectional area value of the semiconductor device under test corresponding to the linear energy transfer value of the remaining section, which could not be measured by the heavy ion equipment, can be easily inferred.

[0134] The inferred cross-sectional area value of the semiconductor device under test can have high reliability because it is substantially identical to the cross-sectional area value of the semiconductor device under test measured using the internationally accepted heavy ion equipment.

[0135] In addition, by fitting the above discontinuous graph into a continuous graph using the Weibull fitting method, the threshold energy value and / or saturation cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section that could not be measured by the heavy ion equipment can be easily calculated.

[0136] The calculated threshold energy value and / or saturation cross-sectional area value match the threshold energy value and / or saturation cross-sectional area value of the semiconductor device under test measured using the internationally accepted heavy ion equipment, so it can have high reliability.

[0137] FIG. 3 is a flowchart illustrating a method for evaluating radiation resistance of an analog semiconductor device under test according to a second embodiment of the present invention.

[0138] Referring to FIG. 3, an analog semiconductor device under test is provided to a heavy ion device, and a first graph showing the value of the first cross-section of the analog semiconductor device under test according to the linear energy transfer (LET) value of the base section can be obtained (S10).

[0139] According to one embodiment, the heavy ion equipment refers to equipment capable of providing the linear energy transfer value of the base section to the analog semiconductor device under test due to the characteristics of the heavy ion equipment. For example, the heavy ion equipment may be a 6MV heavy ion equipment owned by the Korea Institute of Science and Technology (KIST) in Korea.

[0140] Furthermore, internationally accepted heavy ion equipment refers to equipment capable of providing linear energy transfer values ​​not only for the aforementioned base section but also for the remaining sections excluding the base section. For example, the internationally used heavy ion equipment includes RADEF (RADiation Effects Facility, in Finland), TAMU (Texas A&M Univ.) REF (Radiation Effects Facility Heavy Ion Testing, in USA), BNL (Brookhaven National Laboratory, in USA), LBNL (Lawrence Berkeley National Laboratory, in USA), FRIB (Facility for Rare Isotope Beams, at MSU in USA), GANIL (Grand Accιlιrateur National d'Ions Lourds, in France), CYCLONE (CYClotron of Lovain la NEuvs, in Netherlands), KVI-CART (Kernfysisch Versneller Instituut-Center for Advanced Radiation Technology, in Netherlands), GSI (Gesellschaft fur Schwerionenforschung, in Germany), CERN Heavy ion (in Switzerland & France), HIF-UCL (Heavy Ions Facility-Universitι It may be any one of the following (Catholic Catholique de Louvain, in Belgium). That is, the present invention provides a method that utilizes the above-mentioned heavy ion equipment and can produce substantially the same effect as the result obtained using internationally accepted heavy ion equipment.

[0141] According to one embodiment, the first cross-sectional area value can be derived according to the following <Equation 6>.

[0142] <Mathematical Formula 6>

[0143]

[0144] (σ: the first cross-sectional area value, N SET1 : The number of events generated from the analog semiconductor device under test when heavy ions are irradiated onto the analog semiconductor device under test, wherein the event is one in which the voltage deviation in the output waveform is greater than or equal to a reference voltage deviation, φ beam : Number of heavy ion particles irradiated onto the above-mentioned analog semiconductor device per unit area)

[0145] According to one embodiment, the analog semiconductor device under test has two input voltages (V + , V - It may include a comparator that switches the output to High / Low by comparing ). Unlike digital-based storage devices such as SRAM, the aforementioned comparator may experience Single Event Transient (SET) errors due to charge imbalance and transient current. Accordingly, the present invention can derive the first cross-sectional area value using the number of events measured from the output waveform, rather than using the number of errors as in conventional SRAM. In particular, since the output signal of the comparator appears as a continuous analog voltage waveform unlike SRAM, the voltage deviation (△V) of the output waveform generated during heavy ion irradiation can be monitored in real time, and signals showing a voltage deviation greater than a reference voltage deviation can be recognized as events and their counts can be calculated. Therefore, the method according to the present invention can easily and quantitatively evaluate analog signal-based radiation-induced abnormal events (Single Event Transient, SET) that cannot be measured by error-based evaluation methods of digital memory devices such as SRAM.

[0146] For example, the linear energy transfer value of the base section may be 10 LET or more and 40 LET or less. According to another embodiment, the linear energy transfer value of the base section may be 13 LET or more and 40 LET or less. As yet another example, the linear energy transfer value of the base section may be 9 LET or more and 45 LET or less. That is, in step S100, the first graph showing the change in the first cross-sectional area value at 10 LET or more and 40 LET (or 13 LET or more and 40 LET or less, or 9 LET or more and 45 LET or less) can be obtained.

[0147] After step S10 above, the analog semiconductor device under test is provided to a pulse laser device to derive a second cross-sectional area value of the semiconductor device under test according to the laser energy value, and an equivalent linear energy transfer value (Equivalent LET) is derived using the second cross-sectional area value, and a second graph representing the second cross-sectional area value according to the equivalent linear energy transfer value can be obtained (S20).

[0148] According to one embodiment, the second cross-sectional area value can be derived according to <Equation 7> below, and the equivalent linear energy transfer value can be derived according to <Equation 8>, <Equation 8-1>, <Equation 9>, and <Equation 9-1> below.

[0149] <Mathematical Formula 7>

[0150]

[0151] (σ Laser : The above second cross-sectional area value, N SET2 : The number of events generated from the analog semiconductor device under test when a laser is irradiated onto the analog semiconductor device under test, wherein the event is one in which the voltage deviation in the output waveform is greater than or equal to a reference voltage deviation, N Pulse: Total number of laser pulses irradiated onto the above-mentioned analog semiconductor device under test)

[0152] According to one embodiment, the laser light source of the pulse laser equipment may be single photon absorption (SPA) or two photon absorption (nonlinear absorption). Accordingly, different mathematical formulas may be applied to each laser light source of the pulse laser equipment to derive the equivalent linear energy transfer value.

[0153] More specifically, when the laser light source of the pulse laser equipment is single-photon absorption, the equivalent linear energy transfer value can be derived according to <Equation 8> and <Equation 8-1> below, and <Equation 8-1> can be derived from <Equation 8>.

[0154] <Mathematical Formula 8>

[0155]

[0156] (LET LASER_SPA : The above equivalent linear energy transfer value, α: single photon absorption proportionality constant, E: laser energy, z: depth of laser penetration from the surface of the above analog semiconductor device under test)

[0157] <Mathematical Formula 8-1>

[0158]

[0159] (LET LASESR_SPA : The above equivalent linear energy transfer value, A: Single photon absorption correction factor, E: Laser energy, α s : Surface absorption coefficient, α: Single photon absorption proportionality constant, E: Laser energy, z: Depth of laser penetration from the surface of the analog semiconductor device under test)

[0160] In contrast, when the laser light source of the pulse laser equipment is a nonlinear absorption two-photon, the equivalent linear energy transfer value can be derived according to <Equation 9> and <Equation 9-1> below, and <Equation 9-1> can be derived from <Equation 9>.

[0161] <Mathematical Formula 9>

[0162]

[0163] (LET LASESR_TPA : The above equivalent linear energy transfer value, β2: nonlinear absorption proportionality constant, E: laser energy, ω0: angular frequency, τ: pulse time, α: single photon absorption proportionality constant, z: depth of laser penetration from the surface of the above analog semiconductor device under test, S(z, z foc ): Energy spatial distribution function of a focused pulsed laser)

[0164] <Mathematical Formula 9-1>

[0165]

[0166] (LET LASESR_TPA : The above equivalent linear energy transfer value, B: Nonlinear absorption correction factor, E: Laser energy, β T : Nonlinear absorption proportionality constant, S: Energy spatial distribution function of the focused pulsed laser, ω0: Angular frequency, τ: Pulse time)

[0167] That is, in the above S200 step, a second graph showing the change in the second cross-sectional area value according to the equivalent linear energy transfer value can be obtained.

[0168] After the above step S200, an integrated graph combining the first graph and the second graph is obtained, and the value of the first cross-sectional area of ​​the remaining section excluding the base section can be derived from the integrated graph (S300).

[0169] As described above, since both the first graph and the second graph represent cross-sectional area values ​​for linear energy transfer values, they can be easily combined. However, since the first graph and the second graph were obtained by different methods, they may appear in a discontinuous form when simply combined. Therefore, by applying the following <Equation 10> to the integrated graph combining the first graph and the second graph, the graph can appear in a continuous form, and from this, the first cross-sectional area value of the remaining section excluding the base section can be derived.

[0170] <Mathematical Formula 10>

[0171]

[0172] (σ(x): The first cross-sectional area value of a specific section among the remaining sections excluding the base section, σ sat : Saturation values ​​of the first cross-sectional area value and the second cross-sectional area value within the integrated graph above, P w : Width of the rise interval between the first cross-sectional area value and the second cross-sectional area value within the integrated graph above, X: Specific linear energy transfer value, X th : Linear energy transfer value at the point where the first cross-sectional area value and the second cross-sectional area value within the above integrated graph change from 0 to a positive value, s: Shape factor of the Weibull distribution representing the rate of change of the slope of the above integrated graph)

[0173] Consequently, the radiation resistance evaluation method of an analog semiconductor device under test according to an embodiment of the present invention can precisely evaluate radiation resistance characteristics with respect to a comparator. In particular, by using a heavy ion device with a narrow linear energy transfer value range (providing only LET for the base region), the effect of using a heavy ion device with a wide linear energy transfer value range (providing LET for the base region as well as for regions other than the base region) can be obtained.

[0174]

[0175] Specific experimental examples are described below.

[0176] SRAM Internal Radiation Assessment

[0177] FIG. 4 is a graph for comparing the cross-sectional area value measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value inferred by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 1.

[0178] Referring to FIG. 4(a), the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 was performed by providing the semiconductor device under test (Cypress SRAM, ISSI SRAM) to an internationally accepted heavy ion device (providable linear energy transfer value; 2 LET ~ 85.6 LET), respectively, and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value. Then, using <Equation 5> described above in the embodiment of the present application, the discontinuous graph was fitted into a continuous graph to confirm the threshold energy value and the saturation cross-sectional area value of the semiconductor device under test. Referring to FIG. 4(b), the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 1 was performed by measuring the cross-sectional area of ​​each semiconductor device under test (Cypress SRAM, ISSI SRAM) using a laser device (SPA light source, pulse width 800 fs ~ 1,200 fs). Then, using <Equation 3> and <Equation 3-1> described above in the embodiment of the present application, the laser energy value was converted into a linear energy transfer value. Then, using <Equation 5> described above in the embodiment of the present application, the discontinuous graph was fitted into a continuous graph to confirm the threshold energy value and the saturation cross-sectional area value of the semiconductor device under test.

[0179] As can be seen in Figures 4 (a) and (b), when comparing the cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Comparative Example 1 with the cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Experimental Example 1, it can be seen that they are similar to each other, and also that the threshold energy value and the saturation cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) match each other.

[0180] In addition, in the radiation resistance evaluation method of the semiconductor under test according to Experimental Example 1, it can be seen that when the semiconductor device under test is a Cypress SRAM, the converted linear energy transfer value extends up to 110 LET. Also, when the semiconductor device under test is an ISSI SRAM, it can be seen that the converted linear energy transfer value extends up to 70 LET.

[0181] FIG. 5 is a graph for comparing the cross-sectional area value measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value inferred by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 2.

[0182] Referring to FIG. 5(a), the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 was performed by providing the semiconductor device under test (Cypress SRAM) to an internationally accepted heavy ion device (providable linear energy transfer value; 2 LET ~ 85.6 LET) and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value. Then, using <Equation 5> described above in the embodiment of the present application, the discontinuous graph was fitted into a continuous graph to confirm the threshold energy value and the saturation cross-sectional area value of the semiconductor device under test. Referring to FIG. 5(b), the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 2 was performed by measuring the cross-sectional area of ​​the semiconductor device under test (Cypress SRAM) using a laser device (TPA light source, pulse width 100 fs ~ 500 fs). Then, using <Equation 4> and <Equation 4-1> described above in the embodiment of the present application, the laser energy value was converted into a linear energy transfer value. Then, using <Equation 5> described above in the embodiment of the present application, the discontinuous graph was fitted into a continuous graph to confirm the threshold energy value and the saturation cross-sectional area value of the semiconductor device under test.

[0183] As can be seen in Figures 5 (a) and (b), when comparing the cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Comparative Example 1 with the cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Experimental Example 2, it can be seen that they are similar to each other, and also that the threshold energy value and the saturation cross-sectional area value of the semiconductor device under test (Cypress SRAM) match each other.

[0184] And, in the radiation resistance evaluation method of the semiconductor under test according to Experimental Example 2, when the semiconductor device under test is Cypress SRAM, it can be seen that the converted linear energy transfer value is extended up to 120 LET.

[0185] Table 1 is a table for comparing the cross-sectional area values ​​of a semiconductor device under test measured using a pulsed laser device in the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 1 and Experimental Example 2 of the present invention.

[0186] Referring to , in the method for evaluating the radiation resistance of a semiconductor device under test according to Experimental Example 1 described in Fig. 4(b), the cross-sectional area of ​​each semiconductor device under test (Cypress SRAM, ISSI SRAM) was measured using a pulsed laser device (SPA light source, pulse width 800fs to 1,200fs). Then, in the method for evaluating the radiation resistance of a semiconductor device under test according to Experimental Example 2 described in Fig. 5(b), the cross-sectional area of ​​the semiconductor device under test (Cypress SRAM) was measured using a pulsed laser device (TPA light source, pulse width 100fs to 500fs).

[0187] As can be seen in , the cross-sectional area value of the semiconductor device under test (Cypress SRAM) measured by the radiation resistance evaluation method according to Experimental Example 1 and the cross-sectional area value of the semiconductor device under test (Cypress SRAM) measured by the radiation resistance evaluation method according to Experimental Example 2 are lower depending on the laser energy value.

[0188] Laser energy value (nJ) Cross-sectional area value per Mbit of Cypress SRAM according to Experiment Example 1 (σ / Mbit) Cross-sectional area value per Mbit of ISSI SRAM according to Experiment Example 1 (σ / Mbit) Cross-sectional area value per Mibit of Cypress SRAM according to Experiment Example 2 (σ / Mbit) 0.1 0.1 45 0.00 49.00 x 10 -5 0.150.190.0115-0.20.2050.01656.00x10 -3 0.30.2250.0251.10x10 -2 0.40.2350.031.20x10 -1 0.50.2450.03251.90x10 -1 0.60.24250.0341.90x10 -1

[0189] FIG. 6 is a graph for comparing the correlation between linear energy transfer values ​​and laser energy values ​​for each semiconductor under test in the radiation resistance evaluation method of semiconductor devices under test according to Experimental Example 3 and Experimental Example 4 of the present invention, and FIG. 7 is a graph showing the cross-sectional area values ​​inferred by the radiation resistance evaluation method of semiconductor devices under test according to Experimental Example 3 of the present invention.

[0190] Referring to Fig. 6(a), the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 3 was conducted by measuring the cross-sectional area values ​​for each semiconductor device under test (Cypress SRAM, ISSI SRAM) using an internationally accepted heavy ion device (2nd LET ~ 85.6 LET), and measuring the cross-sectional area values ​​for each semiconductor device under test using a pulse laser device (SPA, pulse width 800 fs ~ 1,200 fs). In addition, the linear energy transfer value (MeV·cm²) 2 The correlation between the ( / mg) and laser energy values ​​(nJ) was graphed. Referring to Fig. 6(b), the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 4 was conducted by measuring the cross-sectional area values ​​for each semiconductor device under test (Cypress SRAM, ISSI SRAM) using an internationally accepted heavy ion device (2nd LET ~ 85.6 LET), and measuring the cross-sectional area values ​​for each semiconductor device under test using a pulse laser device (TPA, pulse width 100 fs ~ 500 fs). Additionally, the linear energy transfer value (MeV·cm²) 2 The correlation between the laser energy value (nJ) and the ( / mg) value is shown in a graph. Specifically, the red solid line shown in Figures 6 (a) and (b) represents the linear energy transfer value (MeV·cm²) for Cypress SRAM. 2 It shows the correlation between / mg) and laser energy value (nJ), and the green solid line represents the linear energy transfer value (MeV·cm²) for ISSI SRAM. 2 This shows the correlation between (mg) and laser energy value (nJ), and the purple solid line represents the average of the red and green solid lines.

[0191] Referring to FIG. 7(a), the linear energy transfer value (MeV·cm²) of the semiconductor device under test (Cypress SRAM, ISSI SRAM) illustrated in FIG. 6(a) 2Using the slope value corresponding to the correlation between the laser energy value (nJ) and the laser energy value ( / mg), the laser energy value was converted into a linear energy transfer value, and the cross-sectional area values ​​of the semiconductor devices under test (Cypress SRAM, ISSI SRAM) according to the converted linear energy transfer value were plotted on a graph. Referring to Fig. 7(b), the linear energy transfer values ​​(MeV·cm²) of the Cypress SRAM and ISSI SRAM, which are shown in purple in Fig. 6(a), 2 Using the slope value, which is the average correlation between the laser energy value (nJ) and the laser energy value ( / mg), the laser energy value was converted into a linear energy transfer value, and the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) according to the converted linear energy transfer value was graphed.

[0192] As can be seen in Figures 6 (a) and (b), when the light source of the pulsed laser equipment is SPA, it can be seen that the linear energy transfer value and the laser energy value are linearly proportional. In contrast, when the light source of the pulsed laser equipment is TPA, it can be seen that the linear energy transfer value and the laser energy value are proportional to each other in a power-law manner.

[0193] As can be seen in Figures 7 (a) and (b), when comparing the cross-sectional area value of the semiconductor device (Cypress SRAM, ISSI SRAM) using the correlation between the linear energy transfer value and the laser energy value for each semiconductor device (Cypress SRAM, ISSI SRAM) with the cross-sectional area value of the semiconductor device (Cypress SRAM, ISSI SRAM) using the average correlation between the linear energy transfer value and the laser energy value (nJ) of the Cypress SRAM and ISSI SRAM, it can be seen that the cross-sectional area values ​​of the semiconductor devices (Cypress SRAM, ISSI SRAM) are similar.

[0194] FIG. 8 is a graph for comparing the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 1.

[0195] Referring to Fig. 8(a), the radiation resistance evaluation method of the semiconductor device under test according to Comparative Example 1 was carried out by measuring the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) according to the linear energy transfer value using internationally accepted heavy ion equipment (providable linear energy transfer value; 2 LET ~ 85.6 LET). Referring to Fig. 8(b), the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 1 was carried out by measuring the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) according to the laser energy value (nJ) using pulse laser equipment (SPA light source, pulse width 800 fs ~ 1,200 fs).

[0196] As can be seen in Figures 8 (a) and (b), when comparing the cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Comparative Example 1 with the cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Experimental Example 1, it can be seen that the phenomenon in which the cross-sectional area value of Cypress SRAM decreases sharply around the threshold energy value and the phenomenon in which the cross-sectional area value of ISSI SRAM decreases more gradually than that of Cypress SRAM around the threshold energy value are observed identically. Accordingly, it can be seen that there is a correlation between the graph of the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the internationally accepted heavy ion equipment and the graph of the cross-sectional area value of the semiconductor device under test according to the laser energy value of the pulse laser equipment.

[0197] FIG. 9 is a graph for comparing the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 of the present invention with the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 5.

[0198] Referring to Fig. 9, the radiation resistance evaluation method of a semiconductor device under test according to Comparative Example 1 (RADEF) was conducted by providing the semiconductor device under test (Cypress SRAM, ISSI SRAM) to an internationally accepted heavy ion device (providable linear energy transfer value; 2 LET ~ 85.6 LET), respectively, and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value. In addition, the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 5 (KIST) was conducted by providing the semiconductor device under test (Cypress SRAM, ISSI SRAM) to a heavy ion device (providable linear energy transfer value; 13 LET or more and 40 LET or less), respectively, and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value. The results were summarized in . In addition, the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) measured by the radiation resistance evaluation method of the semiconductor device under test according to Comparative Example 1 (RAFDEF) and the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) measured by the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 5 (KIST) were plotted as a continuous graph using <Equation 5> described above in the embodiment of the present invention.

[0199] As can be seen from Figure 9 and Table 2, in the same range (13 LET or more and 40 LET or less), the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) measured by the radiation resistance evaluation method of the semiconductor device under test according to Comparative Example 1 and the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) measured by the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 5 are substantially similar.

[0200] And, by examining the cross-sectional area values ​​of the semiconductor device under test (Cypress SRAM, ISSI SRAM) measured by the radiation resistance evaluation method of the semiconductor device under test according to Comparative Example 1 using the above trend line, it can be seen that threshold energy values ​​and saturation cross-sectional area values ​​for the semiconductor device under test were observed.

[0201] In contrast, in the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 5, when examining the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) measured using the heavy ion equipment, the saturated cross-sectional area value of the semiconductor device under test was observed, but since the characteristics of the heavy ion equipment do not provide a linear energy transfer value of less than 13 LET, it can be seen that it is impossible to confirm the threshold energy value for the semiconductor device under test (Cypress SRAM, ISSI SRAM).

[0202] Linear energy transfer value (MeV·cm) 2 / mg) Cross-sectional area value per Mbit of Cypress SRAM according to Comparison Example 1 (σ / Mbit) Cross-sectional area value per Mbit of ISSI SRAM according to Comparison Example 1 (σ / Mbit) Linear energy transfer value (MeV·cm 2 / mg) Cross-sectional area value per Mbit of Cypress SRAM according to Experimental Example 1 (σ / Mbit) Cross-sectional area value per Mbit of ISSI SRAM according to Experimental Example 1 (σ / Mbit) 2.3 9.20 x 10 -3 5.80x10 -4 14.32.15x10 -1 1.85x10 -2 7.21.10x10 -1 6.20x10 -3 20.42.27x10 -1 2.80x10 -2 13.31.80x10 -1 1.50x10 -2 302.35x10 -1 3.50x10 -2 24.51.90x10-1 2.70x10 -2 402.46x10 -1 3.60x10 -2 45.51.90x10 -1 3.00x10 -2 ---601.91x10 -1 3.10x10 -2 ---

[0203] FIG. 10 is a graph for comparing the cross-sectional area value of a semiconductor device under test measured by the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 5 of the present invention with the cross-sectional area value inferred by the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 6.

[0204] Referring to Fig. 10(a), the radiation resistance evaluation method of a semiconductor device under test according to Experimental Example 5 (KIST) involved providing the semiconductor device under test (Cypress SRAM, ISSI SRAM) to a heavy ion device (providable linear energy transfer value of 10 LET or more and 40 LET or less), and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value. Referring to FIG. 10(b), the radiation resistance evaluation method of the semiconductor device under test according to Experimental Example 6 measured the cross-sectional area of ​​the semiconductor device under test (Cypress SRAM, ISSI SRAM) using a heavy ion device (providable linear energy transfer value; 10 LET or more and 40 LET or less) and a pulse laser device (SPA light source, pulse width 800 fs to 1,200 fs), and used <Equation 3> and <Equation 3-1> described above in the embodiment of the present application to infer the cross-sectional area value of the semiconductor device under test (Cypress SRAM, ISSI SRAM) according to the linear energy transfer value less than 10 LET and greater than 40 LET by using the correlation between the laser energy value and the linear energy transfer value.

[0205] As can be seen in Figures 10 (a) and (b), when looking at the cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Experimental Example 5, the saturated cross-sectional area value can be confirmed, but since the characteristics of the heavy ion equipment cannot provide a linear energy transfer value of less than 10 LET to the semiconductor device under test, it can be seen that the threshold energy value of the semiconductor device under test cannot be confirmed.

[0206] In contrast, when looking at the inferred cross-sectional area value of the semiconductor device under test measured by the radiation resistance evaluation method according to Experimental Example 6, it can be seen that the cross-sectional area value of the semiconductor device under test is inferred for linear energy transfer values ​​less than 10 LET and exceeding 40 LET, excluding linear energy transfer values ​​between 10 LET and 40 LET, and thus the threshold energy value of the semiconductor device under test can also be confirmed. Furthermore, when compared with the graph shown in Fig. 4 (a), it can be seen that the cross-sectional area value inferred by the radiation resistance evaluation method according to Experimental Example 6 is similar to the cross-sectional area value actually measured by the radiation resistance evaluation method according to Comparative Example 1.

[0207]

[0208] Comparator Internal Radiation Evaluation

[0209] FIG. 11 is a graph for explaining the characteristics of an analog Single Event Transient (SET) waveform occurring in an analog semiconductor device under test according to an embodiment of the present invention.

[0210] Referring to Fig. 11, the output voltage of the analog semiconductor device under test exhibits an instantaneous transient response to heavy ions or pulsed lasers, showing a waveform in which the voltage rises for a certain period of time and then returns to the reference voltage. This transient waveform is a phenomenon that occurs as charges induced in the internal nodes of the device by single particle collisions are propagated to the output nodes, and the radiation sensitivity of the device can be quantitatively evaluated through the temporal variation range of the output voltage.

[0211] In particular, in the present invention, as shown in FIG. 11, the amplitude and wavelength of the output waveform can be defined as quantitative variables, respectively. The amplitude is the maximum voltage fluctuation range (△V) from the reference voltage at the time of transient occurrence. max It means ), and the wavelength refers to the time interval (△t) during which the reference voltage deviation is maintained above a certain level. These two physical variables can be used as key indicators to determine the intensity and persistence of the Analog Single Event Transient (ASET) occurring in the device under test.

[0212] In the radiation evaluation of general digital circuits, radiation resistance characteristics are determined simply by whether an error occurs; however, since the output of analog circuits appears as a continuous voltage waveform, an analog evaluation method that simultaneously considers the amplitude and wavelength of transients is required. Accordingly, the present invention precisely analyzes changes in waveform amplitude and wavelength in both heavy ion irradiation and laser-based irradiation, thereby deriving the correlation between the two results and calculating the equivalent linear energy transfer value (equivalent LET).

[0213] Accordingly, the waveform analysis shown in FIG. 11 visually represents the intensity and duration of the SET occurring at the output node of the analog semiconductor device under test, and can be used to derive the first cross-sectional area value and the second cross-sectional area value in subsequent steps (S20, S30).

[0214] FIG. 12 shows the input voltage difference (V) of an analog semiconductor device under test according to an embodiment of the present invention. OD Laser energy (E) according to ) LASER )Cross-sectional area (σ ASET This is a graph to explain the change in ).

[0215] Referring to FIG. 12, the input voltage difference (V) of the device under test OD When ) is -10 mV, -50 mV, +10 mV, and +50 mV, σ according to each output voltage state (0 V or 5 V). ASET It can be observed that the magnitude and rate of change of change. Here, σ ASET A single-event transient (A) generated during pulsed laser irradiation SET It is a value converted into a cross-sectional probability of occurrence of ), and can be used as an indicator to quantitatively evaluate changes in sensitivity according to laser energy.

[0216] More specifically, the input voltage difference (V OD When ) has a negative (-) value (i.e., the output voltage is 0 V), as the peak amplitude increases from 1 V to 2 V, σ ASET The range of change increases rapidly, but tends to saturate above a certain energy level. On the other hand, the input voltage difference (V OD When ) has a positive (+) value (i.e., the output voltage is 5 V), σ increases with increasing laser energy. ASET It can be seen that it increases gradually and maintains a stable rate of change even when the peak amplitude extends to 3 V.

[0217] This is because the internal differential amplifier of the analog comparator element forms different charge accumulation and emission paths depending on the operating voltage state (output High / Low), and the deviation of the input voltage (V OD As ) increases, the location of transient generation and charge distribution change, causing the sensitivity to vary non-linearly. In other words, under negative input voltage conditions, transient current is concentrated mainly in the source region of the input transistor, leading to high σ ASET It represents the value, and under positive (+) input voltage conditions, it exhibits relaxed response characteristics due to charge diffusion at the output terminal. Consequently, the graph in Fig. 12 shows the operating conditions (V) of the analog semiconductor device under test. OD , V OUT It shows that the transient cross-sectional area varies depending on ), which proves the effectiveness of the hybrid radiation resistance evaluation method (combination of heavy ion + laser) proposed in the present invention. In particular, this method can correct sensitivity differences according to operational deviations that are difficult to obtain with single heavy ion evaluation alone through laser-based experiments, thereby improving the reliability of the evaluation.

[0218] FIG. 13 shows the injected laser energy (E) in an analog semiconductor device under test according to an embodiment of the present invention. LASER This is a graph to explain the change in the analog Single Event Transient (SET) waveform according to ).

[0219] Referring to FIG. 13, the input voltage difference (V OD For the case where ) is -10 mV (left graph) and the case where it is +10 mV (right graph), it can be seen that the output voltage waveform changes into different shapes as the laser injection energy increases to 0.1 nJ, 0.2 nJ, 0.3 nJ, and 0.4 nJ.

[0220] When the input voltage is -10 mV, as the laser energy increases, the maximum amplitude (peak voltage) of the output voltage gradually increases to 1 V, 2 V, and 3 V, and E LASER A nonlinear response is observed in which the waveform characteristics differ distinctly in the 0.3 nJ and 0.4 nJ range. On the other hand, when the input voltage is +10 mV, the output voltage exhibits a transient form in which it instantaneously drops from the steady state (5 V), and E_ LASER When the value is 0.3 nJ and 0.4 nJ, the peaks are observed to be nearly identical (saturated).

[0221] These results are related to the magnitude of the injected energy and the operating state of the device (V OD This means that the formation and extinction behavior of transients differ depending on the sign and output voltage level. That is, under negative (-) input voltage conditions, the transient appears as a positive transient, and under positive (+) input voltage conditions, it appears as a negative transient, and even with the same injection energy, the shape of the response waveform changes depending on the internal potential distribution and charge recombination path of the device.

[0222] Furthermore, the results in Fig. 13 show that the waveform characteristics of SET in analog semiconductor devices have a close correlation with the linear energy transfer value (LET) of heavy ions. That is, E LASER The tendency for the amplitude of the waveform to increase and the wavelength to lengthen as α increases exhibits the same physical behavior as the phenomenon observed when the LET value increases during heavy ion irradiation.

[0223] Therefore, in the present invention, an equivalent LET relationship between laser energy and heavy ion LET is established using these waveform changes, and based on this, a hybrid radiation resistance evaluation for analog devices can be performed. In conclusion, Figure 4 shows the asymmetric response of the SET waveform according to the input voltage conditions and injection energy changes of the comparator device under test. This is an analog-specific characteristic not observed in digital devices and can be used as data to prove the precision and reliability of the heavy ion-laser combined evaluation technique proposed in the present invention.

[0224] FIG. 14 is a graph illustrating the waveform characteristics and distribution changes of an analog Single Event Transient (SET) observed under the same laser irradiation energy conditions (0.3 nJ and 0.4 nJ) in an analog semiconductor device under test according to an embodiment of the present invention.

[0225] The graph on the left in Fig. 14 shows the correlation distribution between peak amplitude and pulse width of transients measured under injection energies of 0.3 nJ and 0.4 nJ. Under the 0.3 nJ condition, the amplitude shows a relatively constant clustering pattern within the range of approximately 1-4 V and the pulse width within approximately 50-250 ns, whereas under the 0.4 nJ condition, two independent distribution groups (high-amplitude / long pulse group and low-amplitude / short pulse group) are formed within the same range. This implies that as the injection energy increases, additional charge diffusion and recombination mechanisms intervene in addition to a single charge collection path, causing different SET responses to occur simultaneously.

[0226] The graph on the right in Fig. 14 shows representative waveforms corresponding to these distribution groups in the time domain. The upper graph corresponds to a cluster with relatively short pulse widths and low amplitudes (the lower region of the upper scatter plot), exhibiting a pattern where the transient duration is short and the state returns quickly to a steady state. Conversely, the lower graph corresponds to a cluster with long pulse widths and large amplitudes (the upper region of the upper scatter plot), showing deep potential fluctuations and long return times. These differences suggest that even within the same device, different charge collection and discharge paths exist depending on the injection location and internal electric field distribution.

[0227] Consequently, through the analysis of Figure 14, it can be confirmed that there is a multimodal response of the nonlinear SET response that cannot be classified solely by wavelength or amplitude. In particular, the two clusters observed under the 0.4 nJ condition have a high correlation with the multi-branch response observed in a specific LET interval during heavy ion irradiation, and can be used as a basis for verifying the reliability of the hybrid evaluation method (heavy ion + laser combination) proposed in this invention.

[0228] FIG. 15 is a graph showing the pulse characteristic distribution of a Single Event Transient (SET) according to the change in injection energy (0.1 nJ, 0.2 nJ, 0.3 nJ, 0.4 nJ) when the input voltage conditions are different (2.5V-2.6V and 2.6V-2.5V) in an analog comparator element under test according to an embodiment of the present invention.

[0229] The top graph of Fig. 15 shows the results measured under the condition where the non-inverting input (V+) and the inverting input (V-) of the comparator's input terminals are 2.5 V and 2.6 V (i.e., the output is in a Low state), and as the injection energy increases, the distribution of peak amplitude and pulse width shows a tendency to shift upward with a constant slope. Under this condition, the input difference (V inside the comparator) OD Since ) has a negative (-) value, transients mainly occur in the source region of the input differential pair, and as the injection energy increases, the charge collection efficiency increases, forming a single cluster in which the amplitude and pulse width increase together.

[0230] On the other hand, the bottom graph of Fig. 15 shows the case where the input conditions are set in reverse (V+ = 2.6 V, V- = 2.5 V, i.e., the output is in a High state). In this case, as the potential distribution at the input terminal is reversed and transients spread toward the load transistor at the output terminal, it is confirmed that two or more distinct distribution groups are formed even at the same injection energy. In particular, from the time the injection energy increases to 0.3 nJ or more, a region where scattered points with an amplitude of 1-3 V are concentrated around a pulse width of about 150-250 ns and a low-pulse, low-amplitude region below it appear simultaneously, which suggests that two distinct error mechanisms coexist.

[0231] Therefore, FIG. 15 shows the input voltage deviation (V) in the analog comparator element. OD It clearly demonstrates that the generation pattern of SET varies significantly depending on the polarity of ), and as a result, the statistical distribution of pulse characteristics (width and height) changes into multiple forms. This represents a difference in sensitivity inherent to analog circuits that is not observed in digital memory devices (such as SRAM); therefore, to align the heavy ion evaluation results with the laser injection evaluation results, simply σ ASETThis implies that a comparison of LET alone is insufficient, and that shape distribution based on operating conditions can be additionally performed.

[0232] In conclusion, FIG. 15 demonstrates that the morphological response of SET changes significantly despite minute differences in input voltage (±100 mV level), and shows that the hybrid radiation resistance evaluation method proposed in the present invention can quantitatively distinguish changes in error types according to the actual operating conditions of the analog circuit.

[0233] FIG. 16 shows an analog comparator element according to an embodiment of the present invention, wherein the input voltage difference (V OD This is a diagram to explain the phenomenon in which the location and magnitude of an analog Single Event Transient (SET) change depending on the change in polarity of ).

[0234] The left image of Fig. 16 shows an input voltage difference of +700 mV (V OD This shows the laser irradiation results under the condition of = +△700 mV, demonstrating that the SET response occurs intensively in certain regions within the comparator circuit (mainly near the input terminal and reference voltage terminal). Under this condition, the comparator output is in an operating state transitioning from Low to High, and transients occur mainly in the input differential pair and the surrounding gain amplifier (Preamp region). Therefore, the location of the error is localized, and the magnitude of the output fluctuation (transient amplitude) is observed within a relatively limited range depending on the injection location.

[0235] On the other hand, the right image of Fig. 16 shows an input voltage difference of -700 mV (V ODThis shows the results under the condition where = -△700 mV). In this case, as the output state of the comparator is inverted, the bias current flow in the internal circuit is redistributed, and the sensitivity to SET spreads over a wider area than under the previous condition. In fact, the blue area indicated in the figure is where error occurrence is concentrated, with numerous transients detected mainly in the cascade transistor and load resistance network near the output terminal. This implies that when the input polarity is inverted, the internal current path changes, altering the charge collection path, and consequently, the spatial distribution of the error changes asymmetrically.

[0236] As such, FIG. 16 visually demonstrates that in an analog circuit, the location and intensity of SET occurrence can change solely due to variations in input voltage conditions. In particular, unlike digital circuits (SRAM, D-FF, etc.) where errors primarily occur at fixed nodes within memory cells, analog circuits are distinguished by the fact that the error sensitivity region dynamically shifts according to circuit structural asymmetry and changes in the operating point. Consequently, the experimental results in FIG. 16 prove that the hybrid radiation evaluation method proposed in this invention can quantitatively identify not only waveform characteristics (amplitude and width) but also the spatial distribution of error occurrence (spatial sensitivity map). This relates to the operating conditions of the analog circuit (V OD By accurately identifying error-vulnerable regions based on bias current, output level, etc., it provides important basic data for improving radiation hardness during the design phase.

[0237] FIG. 17 is a diagram showing the circuit configuration of a comparator element ISL7119 used in a Single Event Effect (SEE) test evaluation according to an embodiment of the present invention and a Device Under Test (DUT) board equipped with the same.

[0238] The top left of Fig. 17 is a photograph of the actual fabricated DUT board, in which a comparator element is mounted in the center, and external input / output ports, a bias resistor, and a terminal for applying a reference voltage are arranged around it. This DUT board is a dedicated measurement platform designed to stably control the operation of the comparator and precisely measure output fluctuations in heavy ion and laser injection test environments.

[0239] The circuit diagram on the right side of Fig. 17 shows the electrical connection configuration of the corresponding DUT board. An ISL7119 comparator is positioned at the center of the circuit; this is a Dual High-Speed ​​Voltage Comparator that includes two independent comparison circuits within a single monolithic chip. This comparator was fabricated using the Radiation Hardened Silicon Gate (RSG) process to ensure reliability in radiation environments and is designed to provide stable performance in space environments with immunity to Single Event Latch-up (SEL).

[0240] The input terminal of the circuit is configured to apply signals to the non-inverting input (+In) and inverting input (-In) of each comparator, and the reference voltage (V) through the resistor divider network (R1~R8) ref It is connected to ) and ground (GND). The output terminals (Out1, Out2) are configured in the form of SMA terminals so that they can be directly connected to an oscilloscope or data acquisition device to measure transient waveforms. In addition, the ±Vs power line maintains the normal operation of the comparator through a symmetric supply of ±5 V, and to minimize noise caused by external voltage fluctuations, the reference voltage (V) is connected through a resistor network (R3, R6, R11, R12). refIt is designed to ensure that ) is stably applied. This DUT board was fabricated to quantitatively evaluate the single-event transient (SET) phenomenon occurring at the internal node of the comparator and is designed to operate under bias conditions identical to the electrical characteristics in the datasheet. This allows for real-time observation of the amplitude, waveform distortion, and return time of the analog output signal generated during testing, and is utilized to analyze the correlation between the results of heavy ion irradiation and laser injection experiments.

[0241] Consequently, FIG. 17 is a diagram specifically showing the basic hardware platform (DUT board) of the hybrid radiation evaluation system proposed in the present invention, and provides a core foundational structure to ensure operational stability, measurement precision, and reproducibility of the comparator circuit.

[0242] FIG. 18 is a diagram illustrating the configuration of a heavy ion irradiation device for performing a Single Event Effect (SEE) test according to an embodiment of the present invention, and the arrangement of measuring equipment and a test target board (DUT board).

[0243] The bottom of FIG. 18 is a schematic system configuration diagram of a heavy ion irradiation device, consisting of a heavy ion source, a heavy ion accelerator, and an ion extraction port for semiconductor device evaluation. Ions generated from the heavy ion source are selected and accelerated according to their charge state, pass through the heavy ion accelerator, and then are sent to a test vacuum chamber through a multi-line type extraction port. In this process, the ion energy, incident angle, and linear energy transfer (LET) can be adjusted, and an irradiation environment of desired intensity can be implemented for a specific semiconductor device (DUT) depending on the experimental conditions.

[0244] The enlarged image on the right side of Fig. 18 shows the configuration of the actual experimental equipment. A DUT board is installed inside the Test Vacuum Chamber located above the beamline, and an ion beam is directly irradiated onto the surface of the DUT. A dosimeter is attached to the outside of the vacuum chamber to measure the irradiation dose and flux in real time, while an Electric Measurement Unit simultaneously measures changes in the output voltage of the DUT from the outside. This measurement device consists of an oscilloscope, a waveform data collector, and a low-noise current-voltage amplifier, enabling real-time recording of Single Event Transient (SET) or Latch-up (SEL) phenomena occurring during irradiation. The inset image at the bottom right shows the DUT board used in the actual test, equipped with the aforementioned comparator (ISL7119). The DUT board is fixed inside the vacuum chamber and connected to an external measurement system via an SMA connector. This DUT is designed to transmit minute voltage changes occurring during heavy ion irradiation without loss, making it optimized for accurately measuring instantaneous abnormal signals generated in analog circuits.

[0245] This device is based on the heavy ion accelerator beamline of the Korea Institute of Science and Technology (KIST), and experiments are performed at the semiconductor device testing outlet among multiple outlets. The red translucent area of ​​the beamline indicates the path for semiconductor device evaluation, and uniform irradiation conditions can be provided to the DUT by adjusting the irradiation energy and beam homogeneity in that section. Accordingly, FIG. 9 is a diagram specifically showing the actual configuration of the heavy ion irradiation-based SEE test system used in an embodiment of the present invention, through which the output waveform of the DUT circuit can be monitored in real time and the SET and SEL characteristics resulting from radiation incidence can be quantitatively evaluated. Such a configuration functions as a core experimental platform for obtaining physical data comparable to laser injection experiments.

[0246] FIG. 19 is a diagram illustrating the configuration of a SRAM SEE (Single Event Effect) evaluation control system (VLSI Digital System) according to an embodiment of the present invention.

[0247] This system consists of a Device Under Test (DUT) placed inside a vacuum chamber, a Digital Signal Generator / Analyzer capable of externally controlling and analyzing signals from the device, and a Control and Analysis System responsible for overall control.

[0248] A DUT is mounted inside the vacuum chamber for heavy ion irradiation experiments and contains radiation-sensitive components such as SRAM devices or comparator circuits. An ion beam is irradiated onto the surface of the DUT within the chamber to induce Single Event Transient (SET) or Single Event Latch-up (SEL) phenomena. Signals generated by the DUT during irradiation are transmitted to an external signal generator / analyzer module via multi-pin connectors and ribbon cables.

[0249] The digital signal generator / analyzer is centered around a National Instruments PXI-based module and generates digital control signals to control the read, write, and hold states of the SRAM or to apply comparator input signals, while simultaneously sampling and analyzing response waveforms output during radiation irradiation at high speed. Equipped with high-speed digital input / output (DIO) channels and timing synchronization functions, this device can detect real-time SEE events without omission. The control system (SEE analysis module) is linked with the digital signal analyzer to monitor the operating status of the DUT and analyze the temporal correlation between the timing of ion irradiation and electrical abnormal signals. Through this, the frequency, duration, and voltage level changes of SEE events occurring in specific circuit blocks (e.g., memory cells, comparators, amplifiers, etc.) within the DUT can be quantitatively evaluated.

[0250] In addition, the enlarged image shown in the lower left of FIG. 19 illustrates the internal structure of an SRAM chip, showing that the chip is directly exposed to an ion beam irradiation to simulate the occurrence of actual radiation-induced errors (Soft Errors). This configuration enables the experimental reproduction of radiation effects that may occur in actual satellite, aviation, or nuclear power plant environments. Accordingly, FIG. 19 is a diagram specifically illustrating the configuration of an integrated control system for SEE evaluation of SRAM and analog circuits according to an embodiment of the present invention. This system enables the real-time operation of the DUT inside the vacuum chamber to be controlled and monitored by external equipment, thereby allowing for the precise identification of the mechanism of radiation-induced errors and their utilization in optimizing radiation-resistant circuit design.

[0251] FIG. 20 is a diagram showing the configuration of a Comparator SEE (Single Event Effect) evaluation control system (IC Analog System) according to an embodiment of the present invention.

[0252] This system is a device configured to quantitatively evaluate the single-event effects of analog integrated circuits (particularly comparators) in a radiation environment, and consists of an in-vacuum chamber, a DC power supply, a digital storage oscilloscope, and a control and data processing system.

[0253] Inside the vacuum chamber shown on the left side of Fig. 20, a DUT board equipped with a Device Under Test (DUT) is installed. The DUT includes a radiation-resistant comparator (ISL7119), and an ion beam is directly irradiated onto the active area of ​​the comparator chip. At this time, each input terminal (+In, -In) and power terminal (±15 V) is connected to a power supply outside the vacuum chamber, and the output terminal (Output1) is connected to an oscilloscope to monitor changes in the analog signal occurring during radiation irradiation in real time.

[0254] The DUT board has a total of 8 SMA ports, and each port has an input voltage (2.1~2.6 V) and a reference voltage (V _ref It consists of a power supply (+15 V, -15 V), ground, and an output signal path. When heavy ion irradiation occurs, the single-event transient (SET) phenomenon generated in the transistor inside the comparator appears as an instantaneous voltage fluctuation in the output waveform, and this signal is recorded by high-speed sampling through an oscilloscope.

[0255] Keysight’s E3631A and E3632A DC Power Supplies are positioned in the center of Fig. 20, and they maintain stable operating conditions for the comparator by independently supplying power of ±15 V and ±25 V. These power supplies are connected to the Control Data Processing System on the right via RS232 or GPIB (General Purpose Interface Bus) communication, and the control system is configured to automatically adjust the output values ​​of each power supply or to store and analyze measured waveform data in real time. The Digital Storage Oscilloscope (DSO) in the upper right is a key device for measuring the output waveform of the comparator, capturing minute voltage changes (at the level of tens of mV) and pulse widths (in the range of ns to μs) that occur during heavy ion irradiation with high resolution. These measurement results are transmitted to the data processing system, where the frequency, amplitude, and duration of single-event transients are automatically calculated, and comparative analysis is performed with previous experimental conditions (e.g., LET value, irradiation angle, power level, etc.).

[0256] Accordingly, FIG. 20 is a diagram specifically illustrating the overall configuration and measurement flow of a SEE evaluation system for an analog comparator according to an embodiment of the present invention. The system provides an integrated experimental platform capable of collecting and analyzing circuit response characteristics in real time in response to radiation by controlling a DUT inside a vacuum chamber in an integrated manner with external measurement equipment. Through this, it is possible to verify radiation-resistant circuit designs and perform feedback design for improving radiation resistance.

[0257] FIG. 21 is a diagram showing the results of analyzing the cross-sectional structure of a comparator according to an embodiment of the present invention using a scanning electron microscope (SEM).

[0258] Referring to FIG. 21, the comparator element is composed of a Si-Layer (silicon active layer) formed on a Si-Bulk (silicon bulk layer) and a dielectric layer interposed therebetween, and the emitter and base regions of a Bipolar Junction Transistor (BJT) are formed on the upper side. This dielectric layer is inserted between the silicon substrate (Si-Bulk) and the Si-Layer and serves to block electrons or holes generated from the substrate from flowing into the transistor region. In other words, the dielectric layer suppresses the transfer of radiation-induced charges generated within the substrate to the active layer, thereby preventing charge accumulation or leakage current generation within the BJT.

[0259] In particular, in environments involving heavy ion or high-energy particle irradiation, electron-hole pairs generated within the silicon substrate can move rapidly and cause device malfunction. However, the dielectric layer observed in this figure effectively blocks the diffusion path of these charges, thereby significantly reducing the probability of a single-event effect (SEE) caused by radiation. By electrically insulating the charge transfer path between the BJT and the Si-Layer, this minimizes transient current and voltage fluctuations within the device, and consequently provides the effect of improving the radiation hardness of the circuit. Accordingly, Figure 21 demonstrates that a dielectric isolation structure is applied to enhance radiation resistance through the cross-sectional structure of a comparator chip according to an embodiment of the present invention. This isolation structure blocks the inflow of charges from the substrate during radiation irradiation, thereby suppressing the occurrence of single-event transients (SET) and latch-up (SEL) and enabling high-reliability analog circuit operation.

[0260] FIG. 22 is a graph showing a comparison of the results of measuring an analog Single Event Transient (SET) waveform according to an embodiment of the present invention in different heavy ion irradiation environments.

[0261] Figure 22(a) shows the waveform measured at the radiation testing facility of Texas A&M University (TAMU) under a Linear Energy Transfer (LET) of 42.8 MeV·cm² / mg, and Figure 22(b) shows the results measured at the heavy ion accelerator facility of the Korea Institute of Science and Technology (KIST) under a LET of 40 MeV·cm² / mg. In this test, the output voltage (V) of the comparator circuit OD By monitoring ), instantaneous voltage anomalies (SET) occurring when heavy ions are irradiated at the input were detected. The SET judgment criterion was the output voltage (V OD It was defined as a case where the fluctuation range of ) exceeds a reference value (e.g., ±0.8 V) or the output voltage deviates from the normal operating level (e.g., 4.6 V or higher or 0.8 V or lower).

[0262] In the TAMU test results shown in Fig. 22 (a), a representative SET waveform with a pulse width of approximately 6 μs and a maximum amplitude of approximately 4.6 V was observed. This waveform represents a typical transient phenomenon caused by the instantaneous inflow of parasitic current into the transistor inside the comparator due to incident heavy ions. Fig. 22 (b) shows the results of irradiating the same device in the KIST heavy ion accelerator environment, confirming that the overall waveform shape and the voltage amplitude during the rise section are very similar to the TAMU results. This implies that the difference in LET values ​​between the two experiments is minimal, and that the internal structure and radiation response characteristics of the device are consistent. Thus, by demonstrating that the heavy ion irradiation results performed at KIST match those of the international standard test (TAMU), it has been proven that the reliability of radiation immunity (SEE) evaluation at an international level can be secured even in a domestic test environment. In addition, the circuit of the present invention exhibits stable return characteristics and fast voltage recovery characteristics even in such heavy ion environments, confirming that it has excellent immunity to single-event transients (SET Immunity). Accordingly, FIG. 22 is a diagram experimentally verifying that the comparator circuit of the present invention exhibits similar SET response characteristics under different LET conditions and test facility environments, demonstrating that the proposed circuit structure demonstrates equivalent performance as a high-reliability analog IC with radiation immunity.

[0263] FIG. 23 shows the cross-sectional area (σ) of an analog Single Event Transient (SET) generation according to an embodiment of the present invention. SET The change in ) is the Linear Energy Transfer (LET) of heavy ions and the input overdrive voltage (V OD This is a graph showing a comparison based on ).

[0264] FIG. 23(a) shows the SET cross-sectional area (σ) measured in different evaluation environments (TAMU (Texas A&M University Radiation Testing Facility), KIST (Korea Institute of Science and Technology Heavy Ion Accelerator), and PL TPA (Laser Injection-based Evaluation System)). SET It shows the relationship between ) and LET. Referring to Fig. 23(a), the LET value in all three evaluation environments is approximately 10 MeV·cm⁻¹. 2 In the region below / mg, σ SET This shows a rapidly increasing trend, and subsequently 40 MeV·cm 2 It can be confirmed that a saturation region is formed in the high LET region above / mg. In particular, the results measured at the KIST Heavy Ion Accelerator show an increasing trend almost identical to the TAMU test results, and the laser-based evaluation results also show the same σ SET -LET correlation characteristics were reproduced. This signifies that the heavy ion test environment established at KIST is cross-verified with radiation test results of international standards (TAMU), and demonstrates the reliability of quantitative radiation tolerance assessment using domestic equipment.

[0265] Figure 23 (b) is the input overdrive voltage (V OD σ measured under KIST heavy ion (40 LET) conditions while varying ) from -100 mV to +400 mV SET This is a graph showing the change of V OD ε is the potential difference at the comparator input (Input Overdrive Voltage); as the input voltage increases, the sensitivity of the output decreases, and accordingly, the SET cross-sectional area tends to decrease gradually. In particular, V in the graph OD σ under the condition of =100 mV SETIt was confirmed that the value closely matches TAMU's 42.8 LET result. This implies that the results obtained from the laser injection experiment correspond well to the actual radiation response in the heavy ion experiment within an equivalent electrical influence range. Consequently, Figure 23 experimentally demonstrates that the comparator device of the present invention possesses a quantitative correlation with the probability of SET occurrence according to the change in heavy ion energy (LET), and that radiation sensitivity can be controlled by adjusting the input overdrive voltage. Accordingly, the device of the present invention demonstrates that by securing cross-correlation between heavy ion-based test results and laser-based simulation experiments, it can significantly improve the reliability of verification for radiation effect assessments at the level of actual space environments.

[0266]

[0267] Although the present invention has been described in detail using preferred embodiments, the scope of the invention is not limited to specific embodiments and should be interpreted by the appended claims. Furthermore, those skilled in the art will understand that many modifications and variations are possible without departing from the scope of the invention.

[0268] The present invention can be used in the semiconductor industry.

Claims

1. A step of providing a semiconductor device under test to a heavy ion device and measuring the cross-sectional area (σ) value of the semiconductor device under test according to the linear energy transfer (LET) value of the base region; A step of providing the semiconductor device under test to a pulse laser device and measuring the cross-sectional area value of the semiconductor device under test according to the laser energy value; and The method includes the step of inferring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the remaining section excluding the base section, using the cross-sectional area value of the semiconductor device under test according to the laser energy value. A method for evaluating radiation resistance of a semiconductor device under test, wherein the above base range is a range of linear energy transfer values ​​that the heavy ion equipment can provide due to the characteristics of the heavy ion equipment.

2. In Paragraph 1, The above heavy ion equipment includes providing the linear energy transfer value of the base section, and Unlike the above-mentioned heavy ion equipment, internationally accepted heavy ion equipment includes equipment that provides linear energy transfer values ​​for the base section and the remaining section, and A method for evaluating radiation resistance of a semiconductor device, comprising the above internationally accepted heavy ion equipment capable of providing a linear energy transfer value of 60 LET or more to the semiconductor device under test.

3. In Paragraph 2, The method includes providing the semiconductor device under test to the above internationally accepted heavy ion equipment and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section and the remainder section. A method for evaluating radiation resistance of a semiconductor device under test, comprising deriving a correlation between the laser energy value and the linear energy transfer value by using the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value measured by the above internationally accepted heavy ion equipment and the cross-sectional area value of the semiconductor device under test according to the laser energy value measured by the above pulse laser equipment.

4. In Paragraph 3, A method for evaluating radiation resistance of a semiconductor device under test, comprising the relationship between the laser energy value and the linear energy transfer value being different depending on the laser light source of the pulsed laser equipment.

5. In Paragraph 4, The laser light source of the pulse laser equipment is single photon absorption (SPA), and the relationship between the laser energy value and the linear energy transfer value is linearly proportional. A method for evaluating radiation resistance of a semiconductor device under test, comprising that the laser light source of the pulse laser equipment is a non-linear absorbing two-photon absorption, and the linear energy transfer value is proportional to the power of the laser energy value.

6. In Paragraph 1, In the step of providing the semiconductor device under test to the heavy ion equipment and measuring the cross-sectional area value of the semiconductor device under test according to the linear energy transfer value of the base section, It includes the fact that at least one of the threshold energy value or saturation cross section value of the semiconductor device under test is not confirmed, and A method for evaluating radiation resistance of a semiconductor device to be tested, comprising the steps of providing the semiconductor device to be tested to the pulse laser equipment and measuring the cross-sectional area value of the semiconductor device to be tested according to the laser energy value, and using the cross-sectional area value of the semiconductor device to be tested according to the laser energy value to infer the cross-sectional area value of the semiconductor device to be tested according to the linear energy transfer value of the remaining section excluding the base section, thereby inferring at least one of the threshold energy value or the saturation cross-sectional area value of the semiconductor device to be tested.

7. A step of providing the analog semiconductor device under test to a heavy ion device to obtain a first graph representing the value of the first cross-section of the analog semiconductor device under test according to the linear energy transfer (LET) value of the base section; A step of providing the analog semiconductor device under test to a pulse laser device to derive a second cross-sectional area value of the semiconductor device under test according to a laser energy value, deriving an equivalent linear energy transfer value using the second cross-sectional area value, and obtaining a second graph representing the second cross-sectional area value according to the equivalent linear energy transfer value; and The method includes the step of obtaining an integrated graph by combining the first graph and the second graph, and deriving the first cross-sectional area value of the remaining section excluding the base section from the integrated graph. A method for evaluating radiation resistance of an analog semiconductor device under test, wherein the above base range is a range of linear energy transfer values ​​that the heavy ion equipment can provide due to the characteristics of the heavy ion equipment.

8. In Paragraph 7, A method for evaluating the radiation resistance of an analog semiconductor device under test, wherein the analog semiconductor device under test comprises any one of a comparator, an operational amplifier (OP-AMP), a bandgap reference, an LDO regulator, an analog-to-digital converter (ADC), and an analog switch.

9. In Paragraph 8, A method for evaluating radiation resistance of an analog semiconductor device under test, comprising the above first cross-sectional area value being derived according to the following <Equation 6>. <Mathematical Formula 6> (σ: the first cross-sectional area value, N SET1 : The number of events generated from the analog semiconductor device under test when heavy ions are irradiated onto the analog semiconductor device under test, wherein the event is one in which the voltage deviation in the output waveform is greater than or equal to a reference voltage deviation, φ beam : Number of heavy ion particles irradiated onto the above-mentioned analog semiconductor device per unit area) 10. In Paragraph 9, A method for evaluating radiation resistance of an analog semiconductor device under test, comprising deriving the second cross-sectional area value according to the following <Equation 7>. <Mathematical Formula 7> (σ Laser : The above second cross-sectional area value, N SET2 : The number of events generated from the analog semiconductor device under test when a laser is irradiated onto the analog semiconductor device under test, wherein the event is one in which the voltage deviation in the output waveform is greater than or equal to a reference voltage deviation, N Pulse : Total number of laser pulses irradiated onto the above-mentioned analog semiconductor device under test) 11. In Paragraph 10, The above equivalent linear energy transfer value is derived differently depending on whether the laser light source of the pulsed laser equipment is single photon absorption (SPA) or two-photon absorption, A method for evaluating radiation resistance of an analog semiconductor device under test, comprising deriving according to <Equation 8> and <Equation 8-1> below when the laser light source is a single photon absorber, and deriving according to <Equation 9> and <Equation 9-1> below when the laser light source is a nonlinear absorber two-photon absorber. <Mathematical Formula 8> (LET LASER_SPA : The above equivalent linear energy transfer value, α: single photon absorption proportionality constant, E: laser energy, z: depth of laser penetration from the surface of the above analog semiconductor device under test) <Mathematical Formula 8-1> (LET LASER_SPA : The above equivalent linear energy transfer value, A: Single photon absorption correction factor, E: Laser energy, α s : Surface absorption coefficient, α: Single photon absorption proportionality constant, E: Laser energy, z: Depth of laser penetration from the surface of the analog semiconductor device under test) <Mathematical Formula 9> (LET LASESR_TPA : The above equivalent linear energy transfer value, β2: nonlinear absorption proportionality constant, E: laser energy, ω0: angular frequency, τ: pulse time, α: single photon absorption proportionality constant, z: depth of laser penetration from the surface of the above analog semiconductor device under test, S(z, z foc ): Energy spatial distribution function of a focused pulsed laser) <Mathematical Formula 9-1> (LET LASESR_TPA : The above equivalent linear energy transfer value, B: Nonlinear absorption correction factor, E: Laser energy, β T : Nonlinear absorption proportionality constant, S: Energy spatial distribution function of the focused pulsed laser, ω0: Angular frequency, τ: Pulse time) 12. In Paragraph 11, A method for evaluating radiation resistance of an analog semiconductor device under test, comprising applying the following <Mathematical Formula 10> to the above integrated graph to derive the above first cross-sectional area value of the remaining section excluding the above base section. <Mathematical Formula 10> (σ(x): The first cross-sectional area value of a specific section among the remaining sections excluding the base section, σ sat : Saturation values ​​of the first cross-sectional area value and the second cross-sectional area value within the integrated graph above, P w : Width of the rise interval between the first cross-sectional area value and the second cross-sectional area value within the integrated graph above, X: Specific linear energy transfer value, X th : Linear energy transfer value at the point where the first cross-sectional area value and the second cross-sectional area value within the above integrated graph change from 0 to a positive value, s: Shape factor of the Weibull distribution representing the rate of change of the slope of the above integrated graph)

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