Modeling IC's in an Ionizing Radiation Environment with a Time Varying Wiener Model

The Wiener theory of modeling nonlinear systems is generalized to include time varying systems. With radiation effects in integrated circuits being considered as internal time varying effects, this generalized technique can be used to model an integrated circuit in a radiation environment.     

An Investigation of the Transient Ionizing Radiation Response of Diffused Resistors Using a Pulsed Laser

The transient response of diffused resistors to high dose rate ionizing radiation has been experimentally investigated using a pulsed GaAs laser. The effects of bias, bias configuration, and meandered isolation on the transient response have been determined. It is shown that the transient response of a homogeneous resistor-tub structure is due to conductivity modulation, whereas the response of a heterogeneous structure is dominated by photocurrent generation. Further, the heterogeneous structure response is shown to be highly sensitive to bias and bias configuration, and that meandered isolation improves the transient response significantly at low-bias voltages.     

Response of MNOS Capacitors to Ionizing Radiation at 80°k

MNOS capacitors with oxide thicknesses 85?-600? and silicon nitride thicknesses 200-2000? have been irradiated with 2 MeV electrons at 80°K. Measured flatband shifts are found to depend on both polarity and magnitude of the applied field, oxide thickness, nitride thickness, and variations in device processing. For negative gate bias and effective applied fields 1-2?106 V/Cm, ?VFB is independent of device processing and magnitude of the applied field. For these bias conditions, it is shown that flatband shifts in all MNOS samples may be explained by considering only generation and trapping of holes in the oxide. The holes travel a mean free path of 125± 25? in the oxide before being trapped. For positive gate bias, electrons generated in the oxide are trapped at the oxide-nitride interface and/or in the bulk of the nitride, compensating the effect of the positively charged trapped holes in the oxide, and producing a relatively smaller ?VFB for positive bias. The electron trapping process is considerably processing dependent. For high effective applied fields exceeding ± 2×106 V/cm, a strongly field-dependent mechanism of charge generation in the gate insulator is observed.     

Computerized Model for Response of Transistors to a Pulse of Ionizing Radiation

A computer program has been formulated to solve the time-dependent differential equations describing electron and hole concentrations and the electric field in one-dimensional planar semiconductor-device geometry. The usual assumptions of small minority-carrier concentration and requirements for separating devices into neutral and space-charge regions are not required since the depletion layer is a natural result of the computer solution. Problems which have been studied include the relaxation of P-N junction diodes and transistors from an intense short pulse of ionizing radiation. The phenomena observed include an apparent long recovery time of diodes in high-impedance circuits, ambipolar diffusion of electron-hole pairs toward the junction of alloy diodes, and electric-field peaking in the depletion layer of reverse-biased alloy junctions.     

瞬时电离辐射敏感开关设计及效应分析

采用瞬时辐射敏感开关可避免电子器件在瞬时电离辐射环境下发生闩锁而失效或损毁。性能较好的开关须满足灵敏度高、抗辐射、抗干扰、驱动能力强等要求。本工作在RC延时电路的基础上设计了放电型和充电型两种辐射敏感开关,并通过瞬时电离辐射实验对两种开关的敏感度、关断时间稳定度、抗干扰能力进行了测试。结果表明,放电型开关的关断时间稳定度和抗干扰能力不及充电型开关,且探测单元采用晶闸管较采用二极管或三极管综合性能好;充电型开关更适合用于多次脉冲辐射环境,但开关中的缓冲单元输入端不能含有静电保护电路,否则影响开关关断时间。     

Response of TlCl(I,Be) Crystals to Energetic Ionizing Radiation

Studies of scintillation TlCl(I,Be) crystals have been conducted using 8-GeV negative pions and 50- to 130-MeV positrons. Pulse shapes and resolutions of these crystals have been measured. Pulses from TlCl(I,Be) are observed to have a fast rise time (?2 nsec) and a complicated decay scheme consisting of at least three separate components. Attempts were also made to observe the Cerenkov radiation from these crystals due to highly relativistic particles. The resolution of the pulse height spectrum for a 2.9-cm diameter by 3.8-cm length TlCl(I,Be) scintillator was measured for 8-GeV negative pions. For comparison, the resolution of the same size CsI(Tl) scintillator was measured using the same experimental configuration. The resolution of CsI(Tl) is only slightly greater than theoretical prediction. The resolution of TlCl(I,Be) is greater, being limited by photon statistics even for 35 MeV of deposited energy. The resolution of a 7.6-cm diameter by 7.6-cm length TlCl(I,Be) crystal used as a Total Absorption Shower Counter for 50-130 MeV positrons has also been measured. This resolution is in reasonable agreement with previously reported data.     

Transient Radiation Response of Complementary-Symmetry MOS Integrated Circuits

Complementary-symmetry MOS (CMOS) integrated circuits were subjected to a sub-microsecond burst of high intensity ionizing radiation using 10-MeV electrons from a LINAC. The results show that, at peak doserate values of less than 8 × 108 rads (Si)/s, the transient change in output voltage of a CMOS inverter is small and can be attributed simply to the net junction photocurrent flowing at the output node. At dose rates in excess of 8 × 108 rads (Si)/s, however, a new type of response comes into play and the transient change in output voltage becomes very large, approaching the operating voltage. In some instances, this change can result in a non-destructive temporary latch-up condition. The results suggest that this condition is caused by a parasitic effect, namely the interaction of the P-well, the source-drain diffusions, and the protection diodes that constitute a four layer structure.     

Design Concepts of a Transient Signal Recorder for Operation in Pulsed Ionizing Radiation

The feasibility of a recorder for measuring transient radiation effects, and which is radiation hardened so that it minimizes ionizing effects on the instrumentation itself, has been investigated by designing, fabricating, and testing a 10 channel analog sampling recorder which samples an input signal of ± 6 mA at 100 MHz sampling rate for 100 ns period. The instantaneous sample values are stored as magnetic flux in successive thin magnetic films of a channel. Upon non-destructive readout of the thin films, a time amplitude reconstruction of the input signal is made to within ± 15% of full scale. The system shows radiation hardness in excess of 1010 r/sec, except for the interface amplifier which is hard to 5 × 109 r/sec.     

ONO反熔丝结构的电离辐照性能研究

描述了ONO反熔丝的物理结构,采用ONO薄膜传导模型分析了ONO反熔丝结构在受到电离辐照时,其内部电子-空穴的运动规律。分别对ONO反熔丝FPGA A1460A和A40MX04进行了电离辐照实验,测试了电流与辐照剂量的关系以及FPGA功能失效阈值。理论分析和实验数据说明了该结构比单层SiO2具有更好的抗电离辐照性能。     

Ionizing Radiation Effects in SOS Structures

The total ionizing radiation effects of n-channel enhancement mode silicon on sapphire MISFET's have been characterized up to a total dose of 107 rads (Si). The drain current versus drain voltage characteristics of the n-channel devices showing the "kink" effect were measured over a range of gate voltages and as a function of ionizing radiation. The effect of the ionizing radiation on the "kink" phenomenon was determined and the implications of this effect on the radiation hardness of n-channel MISFET's is discussed. The results show that the equivalent threshold voltage at the operating drain voltage must be defined and used in determining the radiation hardness of the n-channel device. The radiation induced back channel leakage currents of n-channel MISFET's are characterized in terms of device geometry and the amount of radiation induced trapped charge in the sapphire substrate. Results showing the leakage current plotted as a function of drain voltage suggest that the "kink" effect and related phenomena also enhance the radiation induced leakage current effects and lead to substantially increased values of leakage current.     

CCD电离辐射加固工艺研究

本文以简单的MOS电容为手段,研究CCD工艺,以提高器件的抗电离辐射能力。研究发现,栅氧化温度、SiO_2栅介质厚度和CCD工艺中栅氧化以后的高温过程对辐照性能的影响最大;并提出减薄SiO_2栅介质厚度、在1000℃干氧栅氧化、表面栅和埋栅下SiO_2介质在相同条件下生长以及栅氧化后工艺流程中的高温步骤的温度不能超过栅氧化温度和尽量减少栅氧化后的高温步骤等改进的工艺措施。     

Transient Radiation Response of Hardened CMOS/SOS Microprocessor and Memory Devices

Transient tests on rad-hard microprocessor and memory devices of CMOS/SOS design were carried out with the Boeing Linac as the electron pulse source of 40 ns duration. Mean temporary and permanent upset levels were determined to be 1.1×1010 and 1.3×1010 rads (Si)/s for the microprocessor, and 1.3×1010 and 5.1×1010 rads (Si)/s for the memory, respectively. All of these values correspond to the worst case exposure conditions which were found to be static rather than dynamic (i.e., a transition state). Storage pattern sensitivity for both device types during exposure was also determined to be a dominant-zero pattern, that is, a few ones in a field of zeroes in the case of the microprocessor, and a single one in a field of zeroes for the memory. Transient annealing measurements on the microprocessor indicated a recovery time of 20 ?s to 87% of VOH following a 27 kilorad dose/pulse for a 1.8 ?s electron pulse.     

表面n沟CCD的电离辐射损伤

本文报道了150光敏元表面n沟CCD(电荷耦合器件)在不同能量电子和γ射线辐照后的电离辐射效应。试验结果表明,转移失效率在≤10Gy时已明显增大。但大多数器件在累积剂量≤50Gy时,通过调整“胖零”注入仍可工作。在高剂量辐照期间,不同栅偏压器件的转移效率退化存在较大差异。应用高频和准静态C-V技术分析了参数退化的原因。     

Effects of Ionizing Radiation on Monolithic PMOS Inverters

The problem of radiation hardening of metal-oxidesemiconductor (MOS) systems is discussed from a circuit viewpoint. An inverter chain is studied, and its performance in radiation is related to device quality. Techniques for testing and hardening circuits are given.     

Detailed Lumped-Model Analysis of Transistor Ionizing Radiation Effects

Transient response of a transistor exposed to an ionizing radiation environment can be predicted solely from knowledge of the radiation environment and transistor lumped-model parameters calculated from geometrical and electrical data. Accuracy of the lumped-model transistor representation depends on the detail and accuracy of the data used for calculation of the lumped-model parameter values, an accurate representation of the carrier generation rate in the semiconductor transistor chip, and an accurate representation of the interaction of the radiation environment and the transistor leads and package. In general, we have found that the detailed transistor model represents the common emitter transient response to well within a factor of two. The transistor response is calculated from electrical and geometrical data and the measurement of the radiation intensity from a silicon PIN detector. The transistor response is considered over the entire practical range of quiescent emitter current (<10 ?a to > 10 ma) and common-emitter source resistance (100 ohms to 10 kilohms).     

SOS—CMOS电路的电离辐照响应特性

本文通过对ＳＯＳ－ＣＭＯＳ门电路４０８２进行不同偏置条件下的电离辐照实验，研究了电离辐照环境中引起ＳＯＳ－ＣＭＯＳ门电路失效的几种重要漏电机制，。探讨了ＳＯＳ－ＣＭＯＳ电离辐射损伤的最劣辐照偏置条件。     

Effect of Ionizing Radiation on Gunn Diode Amplifiers

X-band Gunn diode amplifiers have been tested while exposed to pulsed ionizing radiation. Peak photo currents induced vary as the .65 power of the dose rate, as had been found for oscillator diodes. The principal effect is a transient loss of gain, with the recovery time less than 400 ns for dose rates up to 5×1010 rad (Si)/s. The dependence of gain on dose rate agrees very well with a calculation based on the change in electric field distribution caused by radiation-induced excess carriers. A permanent failure mode was also observed at the maximum operating voltage and dose rate.     

医用电离辐射中的防护与安全

IRPA-1 0大会就医用电离辐射中的防护与安全领域提供了 4次特别讲座、2次专题会议和 70余篇壁报展示。本文对这个领域的论文进行评论 ,共由两部分组成 :第 1部分叙述特别讲座中 4个报告的内容 ;第 2部分叙述专题会议和壁报的内容 ,其中又分为 3个方面 ,即放射诊断学 (包括介入放射学 )、核医学和放射治疗。     

电离辐射诱发的基因组不稳定性和旁效应

近10年来,对于基因组不稳定性和旁效应的研究已成为生物学和放射生物学领域的一个热点。随着对辐射损伤研究的深入,电离辐射引起的非靶效应（如基因组不稳定性、旁效应等）将对与辐射照射有关的危险评价提出新的挑战。本文就体内、外电离辐射诱发的基因组不稳定性,体内、外旁效应以及二者之间的关系做一简要概述。     

Transient annealing of Sn implanted GaAs

High temperature ( 900°C) transient annealing of Sn⁺ implants into GaAs have been studied by secondary ion mass spectroscopy, electrical measurements and transmission electron microscopy. A two-layer encapsulant (Si₃N₄ + AlN) has been used prior to annealing using an incoherent light furnace. Secondary ion mass spectroscopy measurements show that outdiffusion of tin has occurred which depends both on the dose and annealing conditions. The as implanted atomic profiles are wider than the theoretical profiles and up to 17% further broadening occurs during annealing. Electron concentrations approaching 10¹⁹ cm⁻³ have been measured reproducibly. Transmission electron microscopy results show both faulted and unfaulted dislocation loops and dislocation lines, all defects being decorated with precipitates which contain metallic tin. A large concentration of stacking fault tetrahedra is also produced.