This research focuses on the displacement - total ionizing dose synergistic effect of the UC1825 PWM under neutron and gamma ray irradiation. After irradiating with 2×1012 n/cm2 (the equivalent fluence of 1MeV neutrons) and gamma ray, it's found that neutron irradiation reduces the device's total ionizing dose tolerance. Geant4 simulations reveal that the increase in the density of oxide trap charges caused by oxygen atom displacement is the key factor in this synergistic effect. Moreover, the impact of low - energy neutrons should not be underestimated. In harsh radiation environments, it is necessary to choose more radiation - resistant PWM devices and appropriately increase the radiation design margins.

In this article, a degradation mechanism based on electric field reconstruction was proposed to evaluate the impact of heavy ion irradiation on the gate oxide of 1200 V SiC MOSFETs with planar gate structure. Experimental tests were firstly conducted by starting with a low VDS, which was gradually increased in steps of 20 V, using 181Ta heavy ion species with an energy of 1483 MeV. Notably, the real-time monitoring data showed observable changes in the increasing rate of gate leakage current (IGSS) in the high VDS region (i.e. when VDS exceeded 320 V in this experiment). For mechanism analysis of such experimental phenomena, TCAD simulations were carried out. Simulation results revealed that the gate oxide degradation was influenced by the coupling of two mechanisms, with ion strikes generating two electric field peaks corresponding to different physical processes. The first peak was attributed to conventional hole accumulation in the JFET region, while the second peak resulted from electric field reconstruction caused by the activation of the parasitic bipolar junction transistor. It was found that the second electric field peak which continued to rise as VDS increased plays a dominant role in gate oxide degradation under high VDS conditions, resulting in a change in the increasing rate of IGSS. Furthermore, simulation results showed that the second electric field was less influenced by the ion strike position or the width of the JFET region, indicating that the electric field reconstruction could be triggered in almost any location within the active area and the traditional radiation hardness technique of optimizing JFET structures was ineffective.

Abstract High-voltage silicon carbide (SiC) metal-oxide field-effect transistor (MOSFET) is limited by its ability to resist single event effect (SEE), so it is necessary to study its ability to resist SEE and form an effective reinforcement method. In this paper, it will be studied that how the influence of device structure on the anti-single event ability of SiC MOSFET from the irradiation experiment, and the safe working area of single event leakage degradation of the device is examined. It is found that the width of junction field effect transistor (JFET) and P- type ohmic contact interval both affect the SEE of the device. The SEE mechanism of the device is analyzed based on the experimental results. And the failure caused by local electrothermal stress concentration is confirmed. In view of this mechanism, the reinforced structure is designed with SiO2 barrier layer added in the single event sensitive area, the electrical stress is effectively alleviated, and the peak drain current is reduced by about 18%.

对某型宇航用射频同轴匹配负载电压驻波比超限、参数不稳定等质量问题进行了研究,通过失效物理分析、三维建模仿真分析,将问题定位为该型射频同轴匹配负载内部结构尺寸设计不合理,外界对插应力可直接传递至陶瓷基片,导致部分产品在测试时出现驻波不稳定,个别产品出现陶瓷基板断裂的情况.根据分析结果,对该型射频同轴匹配负载内部焊针、射频电阻、U形夹和衬套开孔等结构尺寸进行系统性优化,提升了产品的固有可靠性.

In this work, we establish a novel numerical model of total ionizing dose effect and use it to simulate the radiation degradation of Si n-metal-oxide-semiconductor field effect transistor (NMOSFET) under different bias voltages. The model is based on the capture/emission process of traps, and is used to simulate the transient characteristics of semiconductor devices under total ionizing dose effect. In the simulation, the changes of trapped holes in Si/SiO2 interface and gate oxide layer are extracted, and it is found that the number of trapped holes at different positions tends to be saturated with the increase of the total dose. When the radiation bias voltage is positive, the degradation amplitude of the threshold voltage is significantly higher than that when the radiation bias voltage is negative. Whether the gate is applied with positive bias or negative bias during the radiation, the degradation amplitude of the threshold voltage shows a trend of first increasing and then decreasing with the increase of the absolute value of radiation bias voltage. Radiation bias voltage also has a certain effect on the annealing effect after radiation. If a gate bias voltage is applied to the device during the annealing, the electrical characteristics recovery amplitude of the device is lower than that under zero bias voltage.

The rapid growth of China's aerospace sector,along with the creation of expansive space configurations like space stations,and the integration of high-perform-ance electric propulsion systems require power semiconductor devices of increasingly better performance.Consequently,it is vital to achieve a breakthrough in the research of radiation-resistant SiC high-voltage power devices.Various bias voltages were applied to SiC JFET devices and subsequent heavy-ion irradiation experiments were conducted.These experiments reveal the existence of two failure modes:single event leakage degra-dation and single event burnout(SEB),which are similar to those found in SiC MOSFET.However,due to the lack of an irradiation-sensitive gate oxide structure,the onset of leakage degradation is higher in SiC JFET than in SiC MOSFET.This implies that SiC JFET have a larger safe operating region.Single event leakage degradation is observed during heavy-ion irradiation when the drain bias voltage is set to 350 V.The extent of leakage degradation is directly proportional tothe absolute value of the drain bias voltage and the quantity of heavy-ion fluence.Additionally,SEB is observed when the heavy-ion irradiation takes place at a drain bias voltage of 400 V.The Sentaurus TCAD simulation study shows that the single event effect can be divided into two phases.The first phase involves heavy-ion irradiation,which is followed by collisional ionisation along the incidence path,resulting in the generation of a large number of carriers.The electric field along the incidence path then produces a current from the drain to the gate.The drain bias voltage was set at 350 V,causing the P+gate area and the PN end of the N-drift area to reach a temperature of 2 500 K due to the high-density current.It is possible that thermal stresses are responsible for the leakage degradation.The modulation of the electric field in the second stage leads to an increase in the electric field at the junction of the N+substrate and the N-drift region,reaching up to 3.2 MV/m.This strong electric field persists for a significant period and results in substantial collision ionisation.As a consequence,the local temperature at the junction of the N+substrate and N-drift region continues to rise to 3 000 K.Exceeding the sublimation temperature of SiC material results in SiC JFET device burnout.Adding a buffer layer at the junction of the N+substrate and N-drift region may enhance the SEB threshold voltage of SiC JFET.This study guides radiation reinforcement of SiC JFET devices and supports the application of SiC power devices in space environments.

Shield gate trench(SGT)MOSFET was used as the research object to study the pheno-menon and physical mechanism of single particle microdose effect induced by heavy ions.Heavy ion irradiation test on 30 V SGT MOSFET at different bias voltages was carried out,and the changing trend for the transfer characteristic curves of the device after heavy ion radiation was analyzed to reveal the deg-radation rule of single particle microdose effect.It is found that heavy ion incident will cause the increase of subthreshold current and lead to negative drift of threshold voltage,and the negative drift of subthreshold voltage is more serious under negative gate voltage.Experimental results combined with TCAD simulation further reveal that the positive oxide trap charge at the Si/SiO2 interface of the gate ox-ide side wall is the main reason for the degradation of device threshold voltage and subthreshold voltage.The results can provide guidance for the evaluation and modeling of single particle microdose effect of SGT MOSFET.

The single particle displacement damage effects and mechanisms in 8T Global Shutter CMOS image sensors (CISs) are studied. We provide radiation effects due to 129Xe ion irradiations of 8T Global Shutter CIS by the analyses of dark current spikes and dark current non-uniformity (DCUN). The experimental results show that low fluence irradiation-induced dark current distributions in 8T global shutter CIS exhibit a clear exponential hot pixel tail that appears difficult to match with cumulative radiation effect physical models. The degradation mechanism is a high electric field distribution exists at the overlap region between gate and pinned-photodiode (PPD). The emission rate of a defect can be dramatically enhanced via a high electric field. Irradiation-induced defects are the sources of the dark electron generation and the electric field acts as an amplifier.

为严格控制低成本卫星和商业卫星的研制成本,并缩短研制周期,有效手段之一是采用工业级器件、普军级器件,甚至是商用货架(Commercial Off-The-Shelf,COTS)器件.但是,研制成本与空间辐射环境适应性之间的矛盾是低等级器件和COTS器件在空间应用时需解决的主要问题.在分析低成本卫星和商业卫星空间辐射环境的基础上,结合NASA、ESA对低等级器件提出的评估筛选标准,思考了低成本卫星和商业卫星用电子器件抗辐射加固保证流程,为后续制定低成本卫星用元器件质量保证体系和大纲提供支撑.

Charge coupled devices with high sensitivity and low dark current were irradiated separately by 10 MeV proton, 14 and 1 MeV neutron up to the fluences of 10(9) cm(-)(2). The generation pattern of hot pixels at different conditions is presented. The experimental results demonstrate that the nuclear inelastic scattering is the dominant generation mechanism of hot pixels induced by proton and neutron irradiations. Meanwhile, a theoretical model is used to predict hot pixel tails at different annealing time points and different operating temperatures.

用能量为3 MeV的质子对一款国产背照式CMOS图像传感器进行了辐照试验,得到了该传感器的固定模式噪声随质子注量和退火温度的变化情况.结果 表明,3 MeV质子辐照后,固定模式噪声有所退化;100℃退火后,固定模式噪声有明显恢复.退化原因主要是浮置扩散结构中位移缺陷引起的暗信号发生了非均匀性变化.此外,受工艺因素限制,读出电路晶体管中的SiO2-Si界面状态在各个像素单元中不一致,导致辐照后电离总剂量效应诱发的界面态陷阱电荷使各个像素单元中读出电路参数的退化情况不同,是固定模式噪声退化的另一个原因.

The complementary metal-oxide-semiconductor (CMOS) active pixel sensors (APSs) can easily be susceptible to heavy-ion radiation in space applications. In this paper, the single event effects (SEEs) of pinned photodiode (PPD) active pixel sensor array exposed to heavy ion (Tantalum, Xenon, Krypton) with linear energy transfer (LET) (37, 50.34 and 81.35 MeV.cm(2)/mg) have been studied. During the heavy ion exposure, all devices were fully functional and integration time was changed, no single event latch-up (SEL) and single event functional interrupt (SEFI) happened. However, dark background with pixel clusters in a frame, which indicates the single event transient (SET) effect were observed. The number of the pixel clusters, total collected charge and cluster size were analyzed in detail. Finally, SRIM simulations were conducted on a PPD in order to predict the number of the electron-hole pairs generated by a heavy ion.

用60 Coγ射线对国产0.18 μm科学级4T互补金属氧化物半导体(CMOS)有源像素图像传感器进行电离总剂量辐照试验,研究了动态偏置下满阱容量的变化规律.试验的吸收剂量率为50 rad(Si)· s-1,测试点的吸收剂量分别为10,30,50,100,150,200,350 krad (Si).结果 表明,随着吸收剂量的增大,满阱容量发生了明显退化.根据提出的钳位光电二极管(PPD)满阱容量计算模型,对实验结果进行了分析.结果 表明,辐照导致PPD沟道所能达到的最小电势和PPD电容的变化是引起满阱容量退化的主要原因.

在室温下开展了1 MeV电子对HgCdTe光伏器件的辐照试验,通过比较电子辐照前、后及室温退火后器件的I-V特性与零偏动态电阻R0,分析了电子辐照对HgCdTe光伏器件暗电流及R0的影响机制.结果 表明,随着电子吸收剂量的增加,HgCdTe光伏器件的暗电流减小,R0增大.室温退火后,HgCdTe光伏器件的暗电流和R0均有明显恢复.分析认为,电子辐照在HgCdTe光伏器件中产生位移损伤,在P区中引入大量的施主型缺陷,使P区空穴浓度迅速下降,少数载流子寿命增加,从而导致暗电流减小,R0增大.

对国产科学级4T-CMOS图像传感器进行电子辐照实验,考察了暗电流、饱和输出灰度值、暗信号非均匀性等参数,分析了器件的电子辐照效应损伤机理.实验结果显示,随着辐照总吸收剂量的增加,器件的饱和输出灰度值下降,并且暗电流显著增加.分析认为,器件的饱和输出灰度值退化机制与电离总剂量效应引起的退化物理机理一致,辐照使转移栅沟道电势势垒下降是饱和输出灰度值下降的主要原因,而暗电流的增长主要由浅槽隔离界面缺陷和体缺陷造成.10 MeV电子辐照后暗电流退化表现出一定的偏置效应,这是由10 MeV电子辐照引起的位移损伤所致.

A pinned photodiode complementary metal-oxide-semiconductor transistor (CMOS) active pixel sensor is exposed to Co-60 to evaluate the performance for space applications. The sample is irradiated with a dose rate of 50 rad (SiO2)/s and a total dose of 100 bad (SiO2), and the photodiode is kept unbiased. The degradation of dark current, full well capacity, and quantum efficiency induced by the total ionizing dose damage effect are investigated. It is found that the dark current increases mainly from the shallow trench isolation (STI) surrounding the pinned photodiode. Further results suggests that the decreasing of full well capacity due to the increase in the density, is induced by the total ionizing dose (TID) effect, of the trap interface, which also leads to the degradation of quantum efficiency at shorter wavelengths.

应用于空间的图像传感器在辐射影响下产生的热像素严重影响空间光电探测性能,本文通过质子辐照试验研究了热像素的产生和变化规律。首先,使用3MeV和10MeV两种能量的质子对图像传感器进行辐照,分析不同能量、不同注量的质子辐照产生热像素的性质;其次,再对辐照后的器件进行退火试验,分析热像素的退火规律。对于相同注量辐照,3MeV质子辐照下热像素产生率大约是10MeV质子辐照下的2.3倍,但是10MeV质子辐照产生热像素的灰度值高于3MeV质子;辐照过程中热像素的数量都是随着注量的增加线性增加。退火过程中,热像素数量都不断减少,而3MeV质子辐照产生的热像素相比于10MeV质子,退火更为显著。结果表明,质子辐照下每个质子与器件之间的作用过程及产生缺陷的机制是相对独立的,不同质子的作用过程之间没有相关性。不同能量的质子辐照产生缺陷的类型不同,导致热像素具有不同特性。

Benefitting from the higher quantum efficiency and sensitivity compared with the front-side illumination (FSI) CMOS image sensors (CISs), backside illumination (BSI) CMOS image sensors tend to replace CCDs and FSI CISs for space applications. However, the radiation damage effects and mechanisms of BSI CISs in the radiation environment are not well understood. We provide radiation effects due to 3 MeV proton irradiations of BSI CISs dedicated to imaging by the analyses of mean dark current increase, dark current nonuniformity and full well capacity in pixel arrays and isolated photodiodes. Additionally, the present annealing certifies the radiation-induced defects, which are responsible for the parameter degradations in BSI CISs.

One of the main reasons for the performance degradation of space imaging system is hot pixels on image sensors (CCD) induced by protons.In order to investigate the mechanisms of hot pixels induced by protons,irradiation testing on interline transfer CCDs were carried out with several energies of protons in terms of 3,10 and 23 MeV.Through the comparison of measurement data under different irradiation test and different operation conditions,effects and mechanisms of hot pixels on devices were analyzed.The results showed that dark signals of CCDs changed slightly,while the numbers of hot pixels increased significantly when the proton fluency was at a low dose rate of 1E9 p/cm2.The generation of hot pixels showed a high correspondence with the irradiated energies of protons.The numbers of hot pixels increased with the increase of the proton energy.The testing data also were analyzed by applying particle transfer calculation and radiation physics theory.The results showed that hot pixels were mainly caused by proton inelastic collision in Si atoms which could produce cluster defects in bulk silicon.