Nitrogen ions of various doses are implanted into the buried oxide (BOX) of commercial silicon-on-insulator (SOI) materials, and subsequent annealings are carried out at various temperatures. The total dose radiat...Nitrogen ions of various doses are implanted into the buried oxide (BOX) of commercial silicon-on-insulator (SOI) materials, and subsequent annealings are carried out at various temperatures. The total dose radiation responses of the nitrogen-implanted SOI wafers are characterized by the high frequency capacitance-voltage (C-V) technique after irradi- ation using a Co-60 source. It is found that there exist relatively complex relationships between the radiation hardness of the nitrogen implanted BOX and the nitrogen implantation dose at different irradiation doses. The experimental results also suggest that a lower dose nitrogen implantation and a higher post-implantation annealing temperature are suitable for improving the radiation hardness of SOI wafer. Based on the measured C V data, secondary ion mass spectrometry (SIMS), and Fourier transform infrared (FTIR) spectroscopy, the total dose responses of the nitrogen-implanted SOI wafers are discussed.展开更多
The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors (nMOSFETs) is investigated. Experimental results show that hot-carrier degradati...The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors (nMOSFETs) is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation (STI). The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.展开更多
The pattern dependence in synergistic effects was studied in a 0.18 μm static random access memory(SRAM) circuit.Experiments were performed under two SEU test environments:3 Me V protons and heavy ions.Measured re...The pattern dependence in synergistic effects was studied in a 0.18 μm static random access memory(SRAM) circuit.Experiments were performed under two SEU test environments:3 Me V protons and heavy ions.Measured results show different trends.In heavy ion SEU test,the degradation in the peripheral circuitry also existed because the measured SEU cross section decreased regardless of the patterns written to the SRAM array.TCAD simulation was performed.TIDinduced degradation in n MOSFETs mainly induced the imprint effect in the SRAM cell,which is consistent with the measured results under the proton environment,but cannot explain the phenomena observed under heavy ion environment.A possible explanation could be the contribution from the radiation-induced GIDL in pMOSFETs.展开更多
Pattem imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is inves- tigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiat...Pattem imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is inves- tigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ASNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device.展开更多
Functional failure mode of commercial deep sub-micron static random access memory(SRAM) induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize th...Functional failure mode of commercial deep sub-micron static random access memory(SRAM) induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result.展开更多
Deep submicron n-channel metal-oxide-semiconductor field-effect transistors (NMOSFETs) with shallow trench isolation (STI) are exposed to ionizing dose radiation under different bias conditions. The total ionizing...Deep submicron n-channel metal-oxide-semiconductor field-effect transistors (NMOSFETs) with shallow trench isolation (STI) are exposed to ionizing dose radiation under different bias conditions. The total ionizing dose radiation induced subthreshold leakage current increase and the hump effect under four different irradiation bias conditions including the worst case (ON bias) for the transistors are discussed. The high electric fields at the corners are partly responsible for the subthreshold hump effect. Charge trapped in the isolation oxide, particularly at the Si/SiO2 interface along the sidewalls of the trench oxide creates a leakage path, which becomes a dominant contributor to the offstate drain-to-source leakage current in the NMOSFET. Non-uniform charge distribution is introduced into a threedimensional (3D) simulation. Good agreement between experimental and simulation results is demonstrated. We find that the electric field distribution along with the STI sidewall is important for the radiation effect under different bias conditions.展开更多
Piezoresistive pressure sensors with a twin-island structure were suc- cessfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline s...Piezoresistive pressure sensors with a twin-island structure were suc- cessfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline silicon overlayer of the SOI wafer and were totally isolated by the buried SiO2. the sensors are radiation-hard. The sensitivity and the linearity of the pressure sensors keep their original values after being irradiated by 60Co γ-rays up to 2.3×104Gy (H2O). However, the offset voltage of the sensor has a slight drift, increasing with the radiation dose. The absolute value of the offset voltage deviation depends on the pressure sensor itself. For comparison, corresponding polysilicon pressure sensors were fabricated using the similar process and irradiated at the same condition.展开更多
Missions flying to giant planets frequently provide telemetry data after substantial time lag. Determination of crucial environmental characteristic sometimes detrimental for the mission health may be further delayed ...Missions flying to giant planets frequently provide telemetry data after substantial time lag. Determination of crucial environmental characteristic sometimes detrimental for the mission health may be further delayed by duration of subsequent data analysis. We propose a fast method used in-flight to assess the electron total ionizing dose and dose rate onboard of the JUICE ESA mission to JUPITER. The procedure provides estimated values of dose rate behind various thickness of shielding using counting rates from the electron telescope EHD of the RADEM radiation hard electron monitor instrument onboard JUICE.展开更多
Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID eff...Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID effects in complementary metaloxide semiconductor(CMOS)digital ICs based on the input/output buffer information specification(IBIS)was proposed.The digital IC was first divided into three parts based on its internal structure:the input buffer,output buffer,and functional area.Each of these three parts was separately modeled.Using the IBIS model,the transistor V-I characteristic curves of the buffers were processed,and the physical parameters were extracted and modeled using VHDL-AMS.In the functional area,logic functions were modeled in VHDL according to the data sheet.A golden digital IC model was developed by combining the input buffer,output buffer,and functional area models.Furthermore,the golden ratio was reconstructed based on TID experimental data,enabling the assessment of TID effects on the threshold voltage,carrier mobility,and time series of the digital IC.TID experiments were conducted using a CMOS non-inverting multiplexer,NC7SZ157,and the results were compared with the simulation results,which showed that the relative errors were less than 2%at each dose point.This confirms the practicality and accuracy of the proposed modeling method.The TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID,which has potential applications in the design of radiation-hardening tolerance in digital ICs.展开更多
The total ionizing dose(TID) effect is a key cause for the degradation/failure of semiconductor device performance under energetic-particle irradiation. We developed a dynamic model of mobile particles and defects by ...The total ionizing dose(TID) effect is a key cause for the degradation/failure of semiconductor device performance under energetic-particle irradiation. We developed a dynamic model of mobile particles and defects by solving the rate equations and Poisson's equation simultaneously, to understand threshold voltage shifts induced by TID in silicon-based metal–oxide–semiconductor(MOS) devices. The calculated charged defect distribution and corresponding electric field under different TIDs are consistent with experiments. TID changes the electric field at the Si/SiO_(2) interface by inducing the accumulation of oxide charged defects nearby, thus shifting the threshold voltage accordingly. With increasing TID, the oxide charged defects increase to saturation, and the electric field increases following the universal 2/3 power law. Through analyzing the influence of TID on the interfacial electric field by different factors, we recommend that the radiation-hardened performance of devices can be improved by choosing a thin oxide layer with high permittivity and under high gate voltages.展开更多
The synergistic effect of total ionizing dose(TID) and single event gate rupture(SEGR) in SiC power metal–oxide–semiconductor field effect transistors(MOSFETs) is investigated via simulation. The device is found to ...The synergistic effect of total ionizing dose(TID) and single event gate rupture(SEGR) in SiC power metal–oxide–semiconductor field effect transistors(MOSFETs) is investigated via simulation. The device is found to be more sensitive to SEGR with TID increasing, especially at higher temperature. The microscopic mechanism is revealed to be the increased trapped charges induced by TID and subsequent enhancement of electric field intensity inside the oxide layer.展开更多
The Uranium-238 (<sup>238</sup>U), Thorium-232 (<sup>232</sup>Th) families and Potassium-40 (<sup>40</sup>K) are of terrestrial origin and contribute generally to an individual’s e...The Uranium-238 (<sup>238</sup>U), Thorium-232 (<sup>232</sup>Th) families and Potassium-40 (<sup>40</sup>K) are of terrestrial origin and contribute generally to an individual’s external exposure through our presence in this environment. They also contribute to the internal exposure through the ingestion of products and beverages such as water that are close to the earth. The aim of this work is to determine the committed effective dose or Total Indicative Dose (TID) due to gamma radioactivity of the borehole water from the Nord Riviera (NR) well field operated by the Côte d’Ivoire Water Distribution Company (SODECI) for the supply of drinking water to part of the population of Abidjan. In addition, the populations, with their habits, could use these borehole waters directly as drinking water. To this end, water samples from the seven (07) functional boreholes were collected and analyzed on a gamma spectrometry chain, equipped with an HPGe detector in the laboratory of the Radiation Protection Institute (RPI) of the GHANA Atomic Energy Commission (GAEC). The results of the specific activities of <sup>238</sup>U, <sup>232</sup>Th and <sup>40</sup>K obtained were transcribed into TID. As the natural radioactivity of the borehole water is high [1], the TIDs calculated from the activity results of the natural radionuclides<sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K vary for the seven boreholes from 0.150 to 0.166 mSv/yr with an average of 0.161 ± 0.034 mSv/yr. The TID of the control tower, where the borehole water is mixed and treated for household use, is equal to 0.136 ± 0.03 mSv/yr. The TIDs obtained are therefore all slightly greater than the WHO reference dose value of 0.1 mSv/yr. But all remain below the UNSCEAR reference dose of 0.29 mSv/yr.展开更多
The worst-case radiation effect in deep-submicron SRAM (static random access memory) circuits is studied through theoretical analysis and experimental validation. Detailed analysis about the radiation effect in diff...The worst-case radiation effect in deep-submicron SRAM (static random access memory) circuits is studied through theoretical analysis and experimental validation. Detailed analysis about the radiation effect in different parts of circuitry is presented. For SRAM cells and a sense amplifier which includes flip-flop structures, their failure level against ionizing radiation will have a connection with the storage state during irradiation. They are inclined to store or read the same state as the one stored during irradiation. Worst-case test scheme for an SRAM circuit is presented, which contains a write operation that changes the storage states into the opposite ones after irradiation and then a read operation with opposite storage states. An irradiation experiment is designed for one 0.25 μm SRAM circuit which has a capacity of I k×8 bits. The failure level against ionizing radiation concluded from this test scheme (150 krad(Si)) is much lower than the one from the simplest test scheme (1 Mrad(Si)). It is obvious that the failure level will be overestimated if the simplest test scheme is chosen as the test standard for SRAM circuits against ionizing radiation.展开更多
Based on 0.18 μm MOS transistors, for the first time, the total dose effects on the matching properties of deep submicron MOS transistors are studied. The experimental results show that the total dose radiation magni...Based on 0.18 μm MOS transistors, for the first time, the total dose effects on the matching properties of deep submicron MOS transistors are studied. The experimental results show that the total dose radiation magnifies the mismatch among identically designed MOS transistors. In our experiments, as the radiation total dose rises to 200 krad, the threshold voltage and drain current mismatch percentages of NMOS transistors increase from 0.55% and 1.4% before radiation to 17.4% and 13.5% after radiation, respectively. PMOS transistors seem to be resistant to radiation damage. For all the range of radiation total dose, the threshold voltage and drain current mismatch percentages of PMOS transistors keep under 0.5% and 2.72%, respectively.展开更多
Total dose irradiation and the hot-carrier effects of sub-micro NMOSFETs are studied. The results show that the manifestations of damage caused by these two effects are quite different, though the principles of damage...Total dose irradiation and the hot-carrier effects of sub-micro NMOSFETs are studied. The results show that the manifestations of damage caused by these two effects are quite different, though the principles of damage formation are somewhat similar. For the total dose irradiation effect, the most notable damage lies in the great increase of the off-state leakage current. As to the hot-carrier effect, most changes come from the decrease of the output characteristics curves as well as the decrease of trans-conductance. It is considered that the oxide-trapped and interface-trapped charges related to STI increase the current during irradiation, while the negative charges generated in the gate oxide, as well as the interface-trapped charges at the gate interface, cause the degradation of the hot-carrier effect. Different aspects should be considered when the device is generally hardened against these two effects.展开更多
This paper studies the total ionizing dose radiation effects on MOS (metal-oxide-semiconductor) transistors with normal and enclosed gate layout in a standard commercial CMOS (compensate MOS) bulk process. The lea...This paper studies the total ionizing dose radiation effects on MOS (metal-oxide-semiconductor) transistors with normal and enclosed gate layout in a standard commercial CMOS (compensate MOS) bulk process. The leakage current, threshold voltage shift, and transconductance of the devices were monitored before and after γ-ray irradiation. The parameters of the devices with different layout under different bias condition during irradiation at different total dose are investigated. The results show that the enclosed layout not only effectively eliminates the leakage but also improves the performance of threshold voltage and transconductance for NMOS (n-type channel MOS) transistors. The experimental results also indicate that analogue bias during irradiation is the worst case for enclosed gate NMOS. There is no evident different behaviour observed between normal PMOS (p-type channel MOS) transistors and enclosed gate PMOS transistors.展开更多
Partially-depleted Silicon-On-Insulator Negative Channel Metal Oxide Semiconductor (SOI NMOS) transistors with different layouts are fabricated on radiation hard Separation by IMplanted OXygen (SIMOX) substrate an...Partially-depleted Silicon-On-Insulator Negative Channel Metal Oxide Semiconductor (SOI NMOS) transistors with different layouts are fabricated on radiation hard Separation by IMplanted OXygen (SIMOX) substrate and tested using 10 keV X-ray radiation sources. The radiation performance is characterized by transistor threshold voltage shift and transistor leakage currents as a function of the total dose up to 2.0×10^6 rad(Si). The results show that the total dose radiation effects on NMOS devices are very sensitive to their layout structures.展开更多
Using 0.18 μm CMOS transistors, the total dose effects on the 1/f noise of deep-submicron CMOS transistors are studied for the first time in China's Mainland. From the experimental results and the theoretic analy...Using 0.18 μm CMOS transistors, the total dose effects on the 1/f noise of deep-submicron CMOS transistors are studied for the first time in China's Mainland. From the experimental results and the theoretic analysis, we realize that total dose radiation causes a lot of trapped positive charges in STI (shallow trench isolation) SiO2 layers, which induces a current leakage passage, increasing the 1/f noise power of CMOS transistors. In addition, we design some radiation-hardness structures on the CMOS transistors and the experimental results show that, until the total dose achieves 750 krad, the 1/f noise power of the radiation-hardness CMOS transistors remains unchanged, which proves our conclusion.展开更多
Total dose hardened fully-depleted SOI materials are fabricated on separation by implanted oxygen (SIMOX) materials by silicon ion implantation and annealing. The ID-VG characteristics of pseudo-MOS transistors pre-...Total dose hardened fully-depleted SOI materials are fabricated on separation by implanted oxygen (SIMOX) materials by silicon ion implantation and annealing. The ID-VG characteristics of pseudo-MOS transistors pre- and post-irradiation are tested with ^60Co gamma rays. The chemical bonds and the structure of Si in the buried oxide are also studied by X-ray photoelectron spectroscopy and cross-sectional high-resolution transmission electron microscopy, respectively. The results show that Si nanocrystals in the buried oxide produced by ion implantation are efficient deep electron traps, which can significantly compensate positive charge buildup during irradiation. Si implantation can enhance the total-dose radiation tolerance of the fully-depleted SOI materials.展开更多
In most of the total dose radiation models, the drift of the threshold voltage and the degradation of the carrier mobility were only studied when the bulk potential is zero. However, the measured data indicate that th...In most of the total dose radiation models, the drift of the threshold voltage and the degradation of the carrier mobility were only studied when the bulk potential is zero. However, the measured data indicate that the total dose effect is closely related to the bulk potential. In order to model the influence of the bulk potential on the total dose effect, we proposed a macro model. The change of the threshold voltage, carrier mobility and leakage current with different bulk potentials were all modeled in this model, and the model is well verified by the measured data based on the 0.35μm PDSOI process developed by the Institute of Microelectronics of the Chinese Academy of Sciences, especially the part of the leakage current.展开更多
文摘Nitrogen ions of various doses are implanted into the buried oxide (BOX) of commercial silicon-on-insulator (SOI) materials, and subsequent annealings are carried out at various temperatures. The total dose radiation responses of the nitrogen-implanted SOI wafers are characterized by the high frequency capacitance-voltage (C-V) technique after irradi- ation using a Co-60 source. It is found that there exist relatively complex relationships between the radiation hardness of the nitrogen implanted BOX and the nitrogen implantation dose at different irradiation doses. The experimental results also suggest that a lower dose nitrogen implantation and a higher post-implantation annealing temperature are suitable for improving the radiation hardness of SOI wafer. Based on the measured C V data, secondary ion mass spectrometry (SIMS), and Fourier transform infrared (FTIR) spectroscopy, the total dose responses of the nitrogen-implanted SOI wafers are discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11475255,U1532261 and 11505282
文摘The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors (nMOSFETs) is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation (STI). The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1532261)
文摘The pattern dependence in synergistic effects was studied in a 0.18 μm static random access memory(SRAM) circuit.Experiments were performed under two SEU test environments:3 Me V protons and heavy ions.Measured results show different trends.In heavy ion SEU test,the degradation in the peripheral circuitry also existed because the measured SEU cross section decreased regardless of the patterns written to the SRAM array.TCAD simulation was performed.TIDinduced degradation in n MOSFETs mainly induced the imprint effect in the SRAM cell,which is consistent with the measured results under the proton environment,but cannot explain the phenomena observed under heavy ion environment.A possible explanation could be the contribution from the radiation-induced GIDL in pMOSFETs.
文摘Pattem imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is inves- tigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ASNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device.
文摘Functional failure mode of commercial deep sub-micron static random access memory(SRAM) induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result.
文摘Deep submicron n-channel metal-oxide-semiconductor field-effect transistors (NMOSFETs) with shallow trench isolation (STI) are exposed to ionizing dose radiation under different bias conditions. The total ionizing dose radiation induced subthreshold leakage current increase and the hump effect under four different irradiation bias conditions including the worst case (ON bias) for the transistors are discussed. The high electric fields at the corners are partly responsible for the subthreshold hump effect. Charge trapped in the isolation oxide, particularly at the Si/SiO2 interface along the sidewalls of the trench oxide creates a leakage path, which becomes a dominant contributor to the offstate drain-to-source leakage current in the NMOSFET. Non-uniform charge distribution is introduced into a threedimensional (3D) simulation. Good agreement between experimental and simulation results is demonstrated. We find that the electric field distribution along with the STI sidewall is important for the radiation effect under different bias conditions.
基金Supported by Science and Technology Development Foundation of Shanghai under Grant (No.98JC14004) partly by National Natural
文摘Piezoresistive pressure sensors with a twin-island structure were suc- cessfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline silicon overlayer of the SOI wafer and were totally isolated by the buried SiO2. the sensors are radiation-hard. The sensitivity and the linearity of the pressure sensors keep their original values after being irradiated by 60Co γ-rays up to 2.3×104Gy (H2O). However, the offset voltage of the sensor has a slight drift, increasing with the radiation dose. The absolute value of the offset voltage deviation depends on the pressure sensor itself. For comparison, corresponding polysilicon pressure sensors were fabricated using the similar process and irradiated at the same condition.
文摘Missions flying to giant planets frequently provide telemetry data after substantial time lag. Determination of crucial environmental characteristic sometimes detrimental for the mission health may be further delayed by duration of subsequent data analysis. We propose a fast method used in-flight to assess the electron total ionizing dose and dose rate onboard of the JUICE ESA mission to JUPITER. The procedure provides estimated values of dose rate behind various thickness of shielding using counting rates from the electron telescope EHD of the RADEM radiation hard electron monitor instrument onboard JUICE.
基金This work was supported by the special fund of the State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(No.SKLIPR2011).
文摘Simulating the total ionizing dose(TID)of an electrical system using transistor-level models can be difficult and expensive,particularly for digital-integrated circuits(ICs).In this study,a method for modeling TID effects in complementary metaloxide semiconductor(CMOS)digital ICs based on the input/output buffer information specification(IBIS)was proposed.The digital IC was first divided into three parts based on its internal structure:the input buffer,output buffer,and functional area.Each of these three parts was separately modeled.Using the IBIS model,the transistor V-I characteristic curves of the buffers were processed,and the physical parameters were extracted and modeled using VHDL-AMS.In the functional area,logic functions were modeled in VHDL according to the data sheet.A golden digital IC model was developed by combining the input buffer,output buffer,and functional area models.Furthermore,the golden ratio was reconstructed based on TID experimental data,enabling the assessment of TID effects on the threshold voltage,carrier mobility,and time series of the digital IC.TID experiments were conducted using a CMOS non-inverting multiplexer,NC7SZ157,and the results were compared with the simulation results,which showed that the relative errors were less than 2%at each dose point.This confirms the practicality and accuracy of the proposed modeling method.The TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID,which has potential applications in the design of radiation-hardening tolerance in digital ICs.
基金Project supported by the Science Challenge Project of China (Grant No.TZ2018004)the National Natural Science Foundation of China (Grant Nos.11975018 and 11775254)+1 种基金the National MCF Energy R&D Program of China (Grant No.2018YEF0308100)the outstanding member of Youth Innovation Promotion Association CAS (Grant No.Y202087)。
文摘The total ionizing dose(TID) effect is a key cause for the degradation/failure of semiconductor device performance under energetic-particle irradiation. We developed a dynamic model of mobile particles and defects by solving the rate equations and Poisson's equation simultaneously, to understand threshold voltage shifts induced by TID in silicon-based metal–oxide–semiconductor(MOS) devices. The calculated charged defect distribution and corresponding electric field under different TIDs are consistent with experiments. TID changes the electric field at the Si/SiO_(2) interface by inducing the accumulation of oxide charged defects nearby, thus shifting the threshold voltage accordingly. With increasing TID, the oxide charged defects increase to saturation, and the electric field increases following the universal 2/3 power law. Through analyzing the influence of TID on the interfacial electric field by different factors, we recommend that the radiation-hardened performance of devices can be improved by choosing a thin oxide layer with high permittivity and under high gate voltages.
基金Project supported by the National Natural Science Foundation of China(Grant No.12004329)Open Project of State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(Grant No.SKLIPR2115)+1 种基金Postgraduate Research and Practice Innovation Program of Jiangsu Province(Grant No.SJCX22_1704)Innovative Science and Technology Platform Project of Cooperation between Yangzhou City and Yangzhou University,China(Grant Nos.YZ202026301 and YZ202026306)。
文摘The synergistic effect of total ionizing dose(TID) and single event gate rupture(SEGR) in SiC power metal–oxide–semiconductor field effect transistors(MOSFETs) is investigated via simulation. The device is found to be more sensitive to SEGR with TID increasing, especially at higher temperature. The microscopic mechanism is revealed to be the increased trapped charges induced by TID and subsequent enhancement of electric field intensity inside the oxide layer.
文摘The Uranium-238 (<sup>238</sup>U), Thorium-232 (<sup>232</sup>Th) families and Potassium-40 (<sup>40</sup>K) are of terrestrial origin and contribute generally to an individual’s external exposure through our presence in this environment. They also contribute to the internal exposure through the ingestion of products and beverages such as water that are close to the earth. The aim of this work is to determine the committed effective dose or Total Indicative Dose (TID) due to gamma radioactivity of the borehole water from the Nord Riviera (NR) well field operated by the Côte d’Ivoire Water Distribution Company (SODECI) for the supply of drinking water to part of the population of Abidjan. In addition, the populations, with their habits, could use these borehole waters directly as drinking water. To this end, water samples from the seven (07) functional boreholes were collected and analyzed on a gamma spectrometry chain, equipped with an HPGe detector in the laboratory of the Radiation Protection Institute (RPI) of the GHANA Atomic Energy Commission (GAEC). The results of the specific activities of <sup>238</sup>U, <sup>232</sup>Th and <sup>40</sup>K obtained were transcribed into TID. As the natural radioactivity of the borehole water is high [1], the TIDs calculated from the activity results of the natural radionuclides<sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K vary for the seven boreholes from 0.150 to 0.166 mSv/yr with an average of 0.161 ± 0.034 mSv/yr. The TID of the control tower, where the borehole water is mixed and treated for household use, is equal to 0.136 ± 0.03 mSv/yr. The TIDs obtained are therefore all slightly greater than the WHO reference dose value of 0.1 mSv/yr. But all remain below the UNSCEAR reference dose of 0.29 mSv/yr.
基金supported by National Natural Science Foundation of China(No.11175271)
文摘The worst-case radiation effect in deep-submicron SRAM (static random access memory) circuits is studied through theoretical analysis and experimental validation. Detailed analysis about the radiation effect in different parts of circuitry is presented. For SRAM cells and a sense amplifier which includes flip-flop structures, their failure level against ionizing radiation will have a connection with the storage state during irradiation. They are inclined to store or read the same state as the one stored during irradiation. Worst-case test scheme for an SRAM circuit is presented, which contains a write operation that changes the storage states into the opposite ones after irradiation and then a read operation with opposite storage states. An irradiation experiment is designed for one 0.25 μm SRAM circuit which has a capacity of I k×8 bits. The failure level against ionizing radiation concluded from this test scheme (150 krad(Si)) is much lower than the one from the simplest test scheme (1 Mrad(Si)). It is obvious that the failure level will be overestimated if the simplest test scheme is chosen as the test standard for SRAM circuits against ionizing radiation.
基金Project supported by the National Key Laboratory Foundations(Nos.9140C090104120C09032,9140C090402110C0906)
文摘Based on 0.18 μm MOS transistors, for the first time, the total dose effects on the matching properties of deep submicron MOS transistors are studied. The experimental results show that the total dose radiation magnifies the mismatch among identically designed MOS transistors. In our experiments, as the radiation total dose rises to 200 krad, the threshold voltage and drain current mismatch percentages of NMOS transistors increase from 0.55% and 1.4% before radiation to 17.4% and 13.5% after radiation, respectively. PMOS transistors seem to be resistant to radiation damage. For all the range of radiation total dose, the threshold voltage and drain current mismatch percentages of PMOS transistors keep under 0.5% and 2.72%, respectively.
文摘Total dose irradiation and the hot-carrier effects of sub-micro NMOSFETs are studied. The results show that the manifestations of damage caused by these two effects are quite different, though the principles of damage formation are somewhat similar. For the total dose irradiation effect, the most notable damage lies in the great increase of the off-state leakage current. As to the hot-carrier effect, most changes come from the decrease of the output characteristics curves as well as the decrease of trans-conductance. It is considered that the oxide-trapped and interface-trapped charges related to STI increase the current during irradiation, while the negative charges generated in the gate oxide, as well as the interface-trapped charges at the gate interface, cause the degradation of the hot-carrier effect. Different aspects should be considered when the device is generally hardened against these two effects.
基金Project supported by the National Natural Science Foundation of China (Grant No 6037202/F010204).
文摘This paper studies the total ionizing dose radiation effects on MOS (metal-oxide-semiconductor) transistors with normal and enclosed gate layout in a standard commercial CMOS (compensate MOS) bulk process. The leakage current, threshold voltage shift, and transconductance of the devices were monitored before and after γ-ray irradiation. The parameters of the devices with different layout under different bias condition during irradiation at different total dose are investigated. The results show that the enclosed layout not only effectively eliminates the leakage but also improves the performance of threshold voltage and transconductance for NMOS (n-type channel MOS) transistors. The experimental results also indicate that analogue bias during irradiation is the worst case for enclosed gate NMOS. There is no evident different behaviour observed between normal PMOS (p-type channel MOS) transistors and enclosed gate PMOS transistors.
文摘Partially-depleted Silicon-On-Insulator Negative Channel Metal Oxide Semiconductor (SOI NMOS) transistors with different layouts are fabricated on radiation hard Separation by IMplanted OXygen (SIMOX) substrate and tested using 10 keV X-ray radiation sources. The radiation performance is characterized by transistor threshold voltage shift and transistor leakage currents as a function of the total dose up to 2.0×10^6 rad(Si). The results show that the total dose radiation effects on NMOS devices are very sensitive to their layout structures.
基金Project supported by the National Key Laboratory Foundations(No.9140C090402110C0906)
文摘Using 0.18 μm CMOS transistors, the total dose effects on the 1/f noise of deep-submicron CMOS transistors are studied for the first time in China's Mainland. From the experimental results and the theoretic analysis, we realize that total dose radiation causes a lot of trapped positive charges in STI (shallow trench isolation) SiO2 layers, which induces a current leakage passage, increasing the 1/f noise power of CMOS transistors. In addition, we design some radiation-hardness structures on the CMOS transistors and the experimental results show that, until the total dose achieves 750 krad, the 1/f noise power of the radiation-hardness CMOS transistors remains unchanged, which proves our conclusion.
文摘Total dose hardened fully-depleted SOI materials are fabricated on separation by implanted oxygen (SIMOX) materials by silicon ion implantation and annealing. The ID-VG characteristics of pseudo-MOS transistors pre- and post-irradiation are tested with ^60Co gamma rays. The chemical bonds and the structure of Si in the buried oxide are also studied by X-ray photoelectron spectroscopy and cross-sectional high-resolution transmission electron microscopy, respectively. The results show that Si nanocrystals in the buried oxide produced by ion implantation are efficient deep electron traps, which can significantly compensate positive charge buildup during irradiation. Si implantation can enhance the total-dose radiation tolerance of the fully-depleted SOI materials.
基金Project supported by the State Key Development Program for Basic Research of China(No.2006CB3027-01)
文摘In most of the total dose radiation models, the drift of the threshold voltage and the degradation of the carrier mobility were only studied when the bulk potential is zero. However, the measured data indicate that the total dose effect is closely related to the bulk potential. In order to model the influence of the bulk potential on the total dose effect, we proposed a macro model. The change of the threshold voltage, carrier mobility and leakage current with different bulk potentials were all modeled in this model, and the model is well verified by the measured data based on the 0.35μm PDSOI process developed by the Institute of Microelectronics of the Chinese Academy of Sciences, especially the part of the leakage current.