X-ray total dose determination method for integrated circuit chip radiation effect evaluation test

Abstract

The invention discloses an X-ray total dose determination method for an integrated circuit chip radiation effect evaluation test, and the method comprises the steps: carrying out the simulation modeling of each plate layer structure related to a radiation sensitive region in a to-be-tested integrated circuit chip, and obtaining a real structure model, simulating an X-ray irradiation environment and counting the absorbed dose of a sensitive area in the real structure model of the integrated circuit chip; performing simulation by adopting a balance model body, and layering the balance model body according to each plate layer structure of the real structure model to obtain a simulation structure model; simulating an X-ray irradiation environment and counting the absorbed dose of a sensitive area in the simulation structure model; and calculating a dose conversion factor according to the real structure model and the absorbed dose of the sensitive area of the balance die body, and correcting according to the dose conversion factor to obtain the X-ray total dose of the radiation effect evaluation test. According to the invention, the total X-ray dose is corrected through simulation calculation before the test, so that the dose accuracy in the irradiation test process can be ensured.

Description

Technical Field

[0001] This invention belongs to the field of device radiation effect evaluation, and in particular relates to a method for determining the total X-ray dose in an integrated circuit chip radiation effect evaluation test. Background Technology

[0002] Integrated circuit chips operating in space radiation environments and strong nuclear radiation environments (e.g., deep submicron level chips) are susceptible to drift, failure, and even damage due to the radiation effects of these environments. Therefore, radiation effect assessments of integrated circuit chips operating in space radiation environments and strong nuclear radiation environments are necessary using ground-based simulation facilities. Wafer-level chip ionizing total dose testing allows for rapid feedback during device development and avoids reliability issues arising from packaging. It also reduces costs and time.

[0003] Due to its advantages such as ease of setup, low-energy and easy collimation, convenient beam current adjustment and testing, and high safety, X-rays are widely used in multi-stress coupling tests in the space radiation environment of wafer-level devices and in strong nuclear radiation environments. GB / T139-2008 stipulates that when using a ferrous sulfate dosimeter to measure X-ray absorbed dose, the dosimeter should be surrounded by a water-equivalent material (such as polystyrene or polyethylene) to achieve approximate electronic equilibrium conditions.

[0004] However, high atomic number materials inside the chip (such as metal interconnect layers in back-end processes) can undergo the Compton effect with X-rays, generating more photoelectrons. Some of these photoelectrons are transported to the radiation-sensitive Si material of the chip, increasing the energy deposited in the sensitive area and causing the actual absorbed dose in the radiation-sensitive area to be higher than the calibrated dose. Therefore, it is necessary to calculate and assess the absorbed dose in the sensitive area inside the device before radiation. Summary of the Invention

[0005] To address the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for determining the total X-ray dose in an integrated circuit chip radiation effect evaluation test.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for determining the total X-ray dose in an integrated circuit chip radiation effect assessment test, comprising the following steps: S1. Model the layer structure of each plate related to the radiation-sensitive area in the integrated circuit chip under test in the simulation software to obtain the real structural model of the integrated circuit chip. Simulate the radiation effect of X-rays to evaluate the irradiation environment of the test and count the absorbed dose of the sensitive area in the real structural model of the integrated circuit chip. S2. Simulate using a balanced phantom based on the thickness of the real structural model, and layer the balanced phantom according to the layer structure of each plate of the real structural model to obtain the simulated structural model; simulate the same X-ray irradiation environment as in step S1 and count the absorbed dose in the sensitive area of ​​the simulated structural model of the integrated circuit chip. S3. Calculate the dose conversion factor based on the absorbed dose of the sensitive area of ​​the real structural model in step S1 and the absorbed dose of the sensitive area of ​​the equilibrium phantom in step S2, and obtain the total X-ray dose of the radiation effect assessment test based on the dose conversion factor.

[0007] Furthermore, in step S1, the thickness and material information of each layer related to the radiation-sensitive area in the integrated circuit chip under test are first obtained; then, based on the thickness and material information of each layer related to the radiation-sensitive area in the integrated circuit chip under test, a corresponding model is formed in the simulation software as the real structural model of the integrated circuit chip.

[0008] Furthermore, the layer structures related to the radiation-sensitive area in the integrated circuit chip under test include a metal interconnect layer, a gate silicon layer, a gate oxide layer, a silicon substrate, a contact layer, and a molding compound layer, wherein the gate oxide layer is the sensitive area; in step S1, during simulation, the metal interconnect layer is split into a wiring metal layer and a wiring material layer according to the material.

[0009] Furthermore, when the integrated circuit chip to be tested has a capping layer, an additional capping layer is added on the metal interconnect layer.

[0010] Furthermore, in step S2, the balancing phantom includes a front balancing layer, a conversion region, and a rear balancing layer thickness. The thickness of the front balancing layer meets the requirement of ensuring dose balance in the sensitive area of ​​the integrated circuit chip under test. The thickness of the conversion region is equal to the sum of the thicknesses of all other layers in the real structural model except for the molding compound layer, and is layered according to the real structural model. The thickness of the rear balancing layer is the same as the thickness of the molding compound layer in the real structural model.

[0011] Furthermore, in steps S1 and S2, X-rays with an energy of 10 keV are used, and the simulation environment is constructed in a parallel incident mode for simulation calculation.

[0012] Furthermore, in steps S1, S2, and S3, Monte Carlo simulation software is used for simulation modeling.

[0013] Furthermore, in step S2, the balancing layer uses a water-equivalent balancing material, such as water-equivalent polyethylene.

[0014] Furthermore, the integrated circuit chip is a deep submicron level chip.

[0015] Furthermore, step S3 includes the following sub-steps: S310. Calculate the ratio of the absorbed dose in the sensitive region of the real structural model in step S1 to the absorbed dose in the sensitive region of the equilibrium phantom in step S2 as the dose conversion factor DF. S320. Obtain the total X-ray dose D1 when the absorbed dose in the sensitive area of ​​the balanced phantom reaches the requirements of the radiation effect assessment test. S330. The ratio of the total X-ray dose D1 to the dose conversion factor DF is taken as the total X-ray dose D2 in the actual radiation effect evaluation test.

[0016] In this invention, when conducting X-ray irradiation tests on integrated circuit chips operating in space radiation environments and strong nuclear radiation environments, the problem of increased radiation dose in the sensitive area of ​​the chip due to the Compton effect is addressed. By calculating the ratio of the absorbed dose in the sensitive area of ​​the real structural model to the absorbed dose in the sensitive area of ​​the equilibrium phantom, a dose conversion factor is obtained. The total X-ray dose is then adjusted based on the dose conversion factor to determine the total X-ray dose during the actual radiation effect assessment test. This significantly reduces the error caused by the Compton effect in the irradiation test and ensures the accuracy of the total X-ray dose in the irradiation test. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of an embodiment of the method for determining the total X-ray dose in the radiation effect evaluation test of integrated circuit chips according to the present invention.

[0018] Figure 2 This is a schematic diagram of a typical structure of a deep submicron chip.

[0019] Figure 3 This is a schematic diagram of the structure of the balancing phantom.

[0020] Figure 4 This is a diagram showing the deep energy deposition of X-rays in water, Si, and SiO2 material layers.

[0021] Figure 5 This is a schematic diagram comparing the actual absorbed dose of each layer of the chip with the absorbed dose of the equilibrium phantom.

[0022] Figure 6 This is a dose enhancement distribution diagram of X-rays of different energies at a 10 μm Cu-SiO2 interface.

[0023] Figure 7The curves show the dose conversion factor (DF) of X-rays under three different materials as a function of thickness.

[0024] Figure 8 The curves show the dose conversion factor (DF) as a function of thickness for X-rays on wire metals made of three different materials. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] Please see Figure 1 , Figure 1 This is a flowchart of an embodiment of the method for determining the total X-ray dose in an integrated circuit chip radiation effect evaluation test according to the present invention. The method for determining the total X-ray dose in this embodiment includes the following steps: S1. Based on the structure of each layer in the radiation-sensitive area of ​​the integrated circuit chip under test, a model is created in simulation software to obtain the true structural model of the integrated circuit chip. The radiation effect of X-rays is simulated to evaluate the irradiation environment of the experiment, and the absorbed dose in the sensitive area of ​​the true structural model of the integrated circuit chip is statistically analyzed. In this step, the thickness and material information of each layer in the radiation-sensitive area of ​​the integrated circuit chip under test are first obtained; then, based on the thickness and material information of each layer, a corresponding model is created in the simulation software as the true structural model of the integrated circuit chip. Monte Carlo simulation software can be used for simulation modeling.

[0027] Please see Figure 2 This is a schematic diagram of a typical structure of a deep submicron-level chip. When the integrated circuit chip under test adopts this typical structure, the layers related to the radiation-sensitive region include a metal interconnect layer, a gate silicon layer (made of silicon), a gate oxide layer (made of silicon dioxide), a silicon substrate (made of silicon), an attachment pad (made of epoxy material), and a molding compound layer (made of molding compound material). In the above typical structure, the gate oxide layer is the radiation-sensitive region. In this step, since the layering is mainly based on the influence of materials, the metal interconnect layer is split into a wiring metal layer (made of metal) and a wiring material layer (made of dielectric material used to fix the wiring metal) during simulation. Of course, many deep submicron-level chips also have a capping layer (Lid), in which case a capping layer is added on the metal interconnect layer. When the capping layer is made of the same or similar metal material, the capping layer and the wiring metal layer can also be combined into one layer. Figure 2In the structure, the remaining layers (e.g., Fild Oxide layer, Buried Oxide layer, Si Substrate 2 layer, and Attach adhesive layer) have little correlation with the radiation-sensitive area, and therefore can be removed when simulating to form a realistic structural model. This step uses Monte Carlo simulation software for modeling; a simulation environment is constructed using 10keV X-rays, set to parallel incidence mode, for calculation.

[0028] In the typical structure used in this embodiment, the simulation material for the capping layer is Cu, the simulation material for the wiring metal layer is Al, and the specific simulation materials and thicknesses of each layer related to the radiation-sensitive area are shown in Table 1. Table 1

[0029] S2. Simulate using a balanced phantom based on the thickness of the actual structural model. Then, layer the balanced phantom according to the structure of each layer of the actual structural model to obtain the simulated structural model. Simulate the same X-ray irradiation environment as in step S1 (i.e., using 10keV X-rays in a parallel incidence mode to construct the simulation environment) and calculate the absorbed dose in the sensitive area of ​​the simulated integrated circuit chip structural model. Please refer to [link to relevant documentation]. Figure 3 In this step, Monte Carlo simulation software can be used for simulation modeling; the balancing model adopts water equivalent balancing material (e.g., water equivalent polyethylene material), and generally includes a front balancing layer 100, a conversion zone 200 and a rear balancing layer 300.

[0030] The structural plane size of the balancing phantom can be set to 10×10 mm. 2 After establishing the equilibrium phantom, the dose coefficients for the three materials were calculated, and the statistical results are shown in Table 2. The numerical values ​​mean that when the water absorption dose measured by the ionization chamber is 1 Gy (water), the dose after conversion to silicon is 6.92 Gy (Si), and the dose after conversion to silicon dioxide is 4.01 Gy (SiO2).

[0031] Table 2

[0032] The interaction between X-rays and target materials is mainly through the photoelectric effect. Please refer to [link / reference]. Figure 4 This is to reduce the dose accumulation of X-rays in water, silicon, and silica material layers. Figure 4 As can be seen, when the thickness of the current balance layer 100 is 20μm during X-ray irradiation, the dose balance of the chip's sensitive area can be guaranteed.

[0033] Therefore, in the subsequent simulation structural model, the thickness of the front balancing layer 100 can be set to 20 μm, so that the sensitive region is located after the absorption peak, thus ensuring the dose balance of the sensitive region of the integrated circuit chip under test. The thickness of the conversion region 200 is equal to the sum of the thicknesses of all other layers in the actual structural model except for the molding compound layer, namely: the sum of the thicknesses of the capping layer (if the actual structural model includes the capping layer), wiring metal layer, wiring material layer, gate silicon layer, gate oxide layer, silicon substrate, and contact layer; and it is layered according to the actual structural model (i.e., according to the capping layer, wiring metal layer, wiring material layer, gate silicon layer, gate oxide layer, silicon substrate, and contact layer), wherein the region corresponding to the gate oxide layer in the conversion region 200 is the sensitive region of the simulation structural model. The thickness of the rear balancing layer 300 is the same as the thickness of the molding compound layer in the actual structural model.

[0034] For the typical structure in Table 1 (with the cap removed), a balanced phantom structure is constructed with front balancing layer 100, conversion region 200, and rear balancing layer 300 having thicknesses of 20 μm, 604.4 μm, and 3 mm, respectively. In this step, the absorbed dose of each layer within the conversion region 200, obtained through simulation, is used as the true absorbed dose D_DOS of each layer of the chip. In step S1, the absorbed dose of each layer in the typical chip structure, obtained through simulation, is used as the uncorrected absorbed dose D_DUT of each layer. For detailed simulation results, please refer to [link to simulation results]. Figure 5 . Figure 5 The numbers 1-7 on the horizontal axis correspond one-to-one with the serial numbers of each layer of the chip in Table 1, and the vertical axis represents the absorbed dose. Figure 5 It can be observed that the actual absorbed dose (D_DUT) in the chip is too high, while the absorbed dose (D_DOS) in the equilibrium phantom is more uniformly distributed. The difference between the two is more obvious in the third oxide gate layer and the fourth silicon dioxide sensitive region layer (i.e., the gate oxide layer), indicating that the actual absorbed dose in the chip's sensitive area is much greater than the preset absorbed dose. Without dose correction, the chip's radiation resistance level may be miscalculated, posing a significant risk to the satellite's on-orbit mission. Therefore, simulation correction of the chip structure before conducting X-ray irradiation experiments is a necessary means to ensure the accuracy of experimental data.

[0035] Before the experiment, to verify whether the wiring metal layer and the cover of the chip had a significant impact on the radiation dose to the sensitive area of ​​the chip under X-ray irradiation, this embodiment also conducted separate simulations based on the materials of the wiring metal layer and the cover. The process and results of the separate simulation of the wiring metal layer are as follows: A simulation phantom was constructed, comprising a front balancing layer 100, a sensitive region, and a rear balancing layer 300. The front balancing layer 100 can have a thickness of 20 μm, the sensitive region typically has a thickness of 1 μm, and the rear balancing layer 300 can have a thickness of 10 mm. Using the dose conversion in Table 1, the effect of absorbed dose enhancement was compared. The material of the front balancing layer 100 was set to Cu, a high atomic number material, to simulate the wiring metal layer of the chip. Simulation calculations were performed at X-ray energies of 10 keV, 20 keV, 30 keV, and 40 keV. The calculation results can be found in [reference needed]. Figure 6 .from Figure 6 As can be seen, at the interface between the high-Z material and the silica material, there is a higher absorbed dose enhancement on the silica side. Furthermore, for X-rays of different energies, within 10 μm of the Cu-SiO2 interface, the absorbed dose is enhanced relative to the equilibrium dose. The enhancement coefficient is related to the material thickness and the energy of the X-rays. Within the thickness range where the enhancement effect exists, the dose change is approximately linearly related to the thickness; that is, the thinner the oxide layer, the greater the relative dose enhancement coefficient. Higher X-ray energy results in a greater depth of material affected by the dose enhancement effect. Figure 6 The simulation results show that, in order to ensure the accuracy of the chip absorbed dose in the radiation effect assessment experiment, the dose of the sensitive area of ​​the chip needs to be calibrated and confirmed before X-ray irradiation.

[0036] The process and results of simulating the cap separately are as follows: Since wafer-level chip capping typically involves ceramic, plastic, and alloy capping layers, to confirm the impact of capping on X-ray dose distribution, this embodiment expands the simulation phantom based on the typical chip structure, performing cumulative simulation calculations under multiple layers of different materials. The dimensions of the newly established simulation phantom are: a front balancing layer 100 thickness of 2500 μm, a sensitive area thickness of 1 μm, and a rear balancing layer 300 thickness of 10 mm. Table 3 shows the composition and density of the front balancing layer 100 material in the three simulation experiments: Table 3

[0037] Please refer to the diagram for the variation of the dose conversion factor (DF) of X-rays with thickness for three different capping types. Figure 7 As can be seen, with the increase of the cap thickness, the absorbed dose reaches a relatively balanced value. Kovar alloy reaches this balance at relatively thinner thicknesses, but the resulting dose conversion factor (DF) is smaller. With increasing cap thickness, the X-ray shielding effect becomes more pronounced and does not maintain a relatively stable range. The cap thickness varies depending on the product's packaging type, typically ranging from 0.5mm to 2.5mm. Within this range, the dose conversion factor (DF) fluctuates significantly. Therefore, to ensure adequate dose in the sensitive area, dose conversion is necessary before testing.

[0038] To address the impact of different back-end processes on metal interconnects, this embodiment treats metal lines as equivalent to metal layer thicknesses in the simulation. X-ray simulations are performed without a cover plate. The material of the front balancing layer 100 of the simulation phantom is replaced with a metal layer, simulating the interconnect layer of the chip. The materials and thicknesses of the remaining parts remain unchanged. For the dose conversion factor DF obtained under different metal layer thicknesses, please refer to [reference needed]. Figure 8 As can be seen, for X-rays, due to the dose enhancement effect of the metal layer, the dose conversion factor (DF) also exhibits a high level. For common Cu / Al metal wiring, the DF is between 1.4 and 1.8. Al's DF is relatively more stable, while Au's DF value decreases linearly with the increase of wiring layer thickness, but is still greater than 1, proving that dose confirmation is required before the chip is irradiated with X-rays. Within the above simulated thickness range, the thickness variation of Al metal has a smaller impact, while Au's effect is the most significant, which also illustrates the difference in interaction between different atomic numbers on X-rays.

[0039] S3. Calculate the dose conversion factor DF based on the absorbed dose of the sensitive region of the real structural model in step S1 and the absorbed dose of the sensitive region of the equilibrium phantom in step S2. Then, correct the total X-ray dose based on the dose conversion factor DF to obtain the total X-ray dose for the radiation effect assessment experiment. This step may include the following sub-steps: S310. Calculate the ratio of the absorbed dose in the sensitive region of the real structural model in step S1 to the absorbed dose in the sensitive region of the equilibrium phantom in step S2 as the dose conversion factor DF. For example, for Figure 5 Based on the data, the ratio of the actual absorbed dose D_DUT to the absorbed dose D_DOS of the equilibrium phantom in the fourth layer can be calculated to be 1.3, that is, the dose conversion factor DF in the sensitive area is 1.3.

[0040] S320. Obtain the total X-ray dose D1 when the absorbed dose in the sensitive area of ​​the equilibrium phantom reaches the requirements of the radiation effect assessment test.

[0041] S330. The ratio of the total X-ray dose D1 to the dose conversion factor DF is taken as the total X-ray dose D2 in the actual radiation effect evaluation test, i.e., D2=D1 / DF.

[0042] In this embodiment, to address the issue of inaccurate dose absorption in sensitive areas of integrated circuit chips operating in space radiation and strong nuclear radiation environments during X-ray irradiation experiments in ground-based simulation devices, Monte Carlo simulation calculations are used before the experiment to ensure dose accuracy during the irradiation test. Before the X-ray experiment, the actual dose distribution in the sensitive area of ​​the integrated circuit chip is analyzed using Monte Carlo simulation. Then, the dose distribution in the sensitive area during the balanced phantom simulation is compared with the actual dose distribution to calculate the dose conversion factor (DF). Based on the dose conversion factor (DF), the total X-ray dose obtained from the balanced phantom simulation is corrected to ensure accurate irradiation absorption dose in the sensitive area during the actual irradiation experiment.

[0043] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A method for determining an X-ray total dose for integrated circuit chip radiation effect evaluation testing, the method comprising: determining a total dose of X-rays to be delivered to a test sample; and delivering the total dose of X-rays to the test sample. The method comprises the following steps: S1, modeling the sensitive region related to radiation in the integrated circuit chip to be tested according to the structure of each board layer in the simulation software, obtaining a real structure model of the integrated circuit chip, simulating the irradiation environment of the radiation effect evaluation test of X-rays and counting the absorbed dose of the sensitive region in the real structure model of the integrated circuit chip; S2, simulating according to the thickness of the real structure model using a balance phantom, and layering the balance phantom according to the structure of each board layer of the real structure model, obtaining a simulation structure model; simulating the irradiation environment of X-rays identical to step S1 and counting the absorbed dose of the sensitive region in the simulation structure model of the integrated circuit chip; S3, calculating the dose conversion factor according to the absorbed dose of the sensitive region of the real structure model in step S1 and the absorbed dose of the sensitive region of the balance phantom in step S2, and correcting to obtain the total dose of X-rays of the radiation effect evaluation test according to the dose conversion factor.

2. The method for dose correction in the sensitive region of total dose testing for deep submicron devices as described in claim 1, characterized in that: In the S1 step, the thickness information and material information of each board layer related to the sensitive region of radiation in the integrated circuit chip to be tested are first obtained; then the corresponding model is modeled in the simulation software according to the thickness information and material information of each board layer related to the sensitive region of radiation in the integrated circuit chip to be tested, which is used as the real structure model of the integrated circuit chip.

3. The method for dose correction in the sensitive region of total dose testing for deep submicron devices as described in claim 1, characterized in that: The structure of each board layer related to the sensitive region of radiation in the integrated circuit chip to be tested includes a metal interconnection layer, a gate silicon layer, a gate oxide layer, a silicon substrate, a contact layer and a plastic encapsulation layer, and the gate oxide layer is the sensitive region; in the S1 step, the metal interconnection layer is split into a wiring metal layer and a wiring material layer according to the material during simulation.

4. The method for dose correction of a sensitive volume of a deep submicron device for total ionizing dose testing of claim 3, wherein: When the integrated circuit chip to be tested is provided with a cover, a cover layer is added on the metal interconnection layer.

5. The method of claim 3, wherein the X-ray total dose is determined by: ###0001### where, D is the X-ray total dose, E is the energy of the X-ray, t is the irradiation time, and I is the X-ray intensity. In the S2 step, the balance phantom includes a front balance layer, a conversion region and a rear balance layer thickness, the thickness of the front balance layer meets the requirement of ensuring the dose balance of the sensitive region of the integrated circuit chip to be tested; the thickness of the conversion region is equal to the sum of the thicknesses of each board layer except the plastic encapsulation layer in the real structure model, and the conversion region is layered according to the real structure model, and the thickness of the rear balance layer is the same as that of the plastic encapsulation layer of the real structure model.

6. The method for determining the total X-ray dose in the radiation effect evaluation test of integrated circuit chips as described in claim 1, characterized in that: In the S1 step and the S2 step, X-rays with an energy of 10 keV are used, and a parallel incident mode is set to construct a simulation environment for simulation calculation.

7. The method for determining the total X-ray dose in the radiation effect evaluation test of integrated circuit chips as described in claim 1, characterized in that: In the S1 step, the S2 step and the S3 step, Monte Carlo simulation software is selected for simulation modeling.

8. The method for determining the total X-ray dose in the radiation effect evaluation test of integrated circuit chips as described in claim 1, characterized in that: In the S2 step, the balance layer uses water equivalent balance material. For example, water equivalent polyethylene material.

9. The method for determining the total X-ray dose in the radiation effect evaluation test of integrated circuit chips as described in claim 1, characterized in that: The integrated circuit chip is a deep submicron chip.

10. The method of claim 1 to 9, wherein the X-ray total dose is determined by the following equation: ###00001### wherein, D is the X-ray total dose, E is the energy of the X-ray, t is the irradiation time, and I is the X-ray intensity. The S3 step comprises the following sub-steps: S310, calculating the ratio of the absorbed dose of the sensitive region of the real structure model in step S1 to the absorbed dose of the sensitive region of the balance phantom in step S2 as the dose conversion factor DF; S320, obtaining the total dose D1 of X-rays when the absorbed dose of the sensitive region of the balance phantom reaches the requirement of the radiation effect evaluation test; S330, taking the ratio of the total dose D1 of X-rays to the dose conversion factor DF as the total dose D2 of X-rays in the actual radiation effect evaluation test.

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