增强型Cascode结构氮化镓功率器件的高能质子辐射效应研究

针对增强型共栅共源(Cascode)级联结构和耗尽型AlGaN/GaN功率器件,利用60 MeV能量质子开展辐射效应研究.获得了经质子辐照后器件电学性能的退化规律,并与常规耗尽型HEMTs器件辐照后的电学性能进行了比较,发现增强型Cascode结构器件对质子辐照更加敏感,分析认为级联硅基MOS管的存在是其对质子辐照敏感的主要原因.质子辐照使硅基MOS管栅氧化层产生大量净的正电荷,诱导发生电离损伤效应,使其出现阈值电压负向漂移及栅泄漏电流增大等现象.利用等效(60 MeV能量质子,累积注量1×10¹² p/cm²)剂量的⁶⁰Co γ射线辐射器件得到电离损伤效应结果,发现器件的电学性能退化规律与60 MeV能量质子辐照后的退化规律一致.通过蒙特卡罗模拟得到质子入射在Cascode型器件内诱导产生的电离能损和非电离能损,模拟结果表明电离能损是导致器件性能退化的主要原因.     

同步动态随机存储器辐射效应测试系统研制

在分析同步动态随机存储器(SDRAM)辐射效应主要失效现象的基础上,研制了具备了读写功能测试、刷新周期测试及功耗电流测试三种功能的SDRAM辐射效应在线测试系统,并开展了SDRAM的总剂量效应实验研究。结果表明,总剂量效应会导致SDRAM器件的数据保持时间不断减小,功耗电流不断增大以及读写功能失效。实验样品MT48LC8M32B2的功能失效主要由外围控制电路造成,而非存储单元翻转。数据保持时间虽然随着辐照剂量的累积不断减小,但不是造成该器件功能失效的直接原因。     

质子辐照作用下浮栅单元的数据翻转及错误退火

本文利用60 MeV质子束流,开展了NAND (not and) flash存储器的质子辐照实验,获取了浮栅单元的单粒子翻转截面,分析了浮栅单元错误的退火规律,研究了质子辐照对浮栅单元的数据保存能力的影响.实验结果表明,浮栅单元单粒子翻转截面随质子能量的升高而增大,随质子注量的升高而减小.浮栅单元错误随着退火时间的推移持续增多,该效应在低能量质子入射时更为明显.经质子辐照后,浮栅单元的数据保存能力有明显的退化.分析认为高能质子通过与靶原子的核反应,间接电离导致浮栅单元发生单粒子翻转,翻转截面与质子注量的相关性是因为浮栅单元单粒子敏感性的差异.质子引起的非电离损伤会在隧穿氧化层形成部分永久性的缺陷损伤,产生可以泄漏浮栅电子的多辅助陷阱导电通道,导致浮栅单元错误增多及数据保存能力退化.     

铁电存储器中高能质子引发的单粒子功能中断效应实验研究

利用中国原子能科学研究院的中高能质子实验平台,针对两款商用铁电存储器开展了中高能质子单粒子效应实验研究,发现其中一款器件在质子辐照下发生了单粒子翻转和单粒子功能中断.本文主要针对单粒子功能中断效应展开了后续实验研究.首先通过改变质子能量对器件进行辐照,发现单粒子功能中断截面随质子能量的提高而增加.为进一步研究器件发生单粒子功能中断的机理,利用激光微束平台开展了辅助实验,对铁电存储器的单粒子功能中断效应的敏感区域进行了定位,最后发现铁电存储器单粒子功能中断是由器件外围电路发生的微锁定导致的.     

SiGe BiCMOS低噪声放大器激光单粒子效应研究

随着CMOS工艺的日益成熟和SiGe外延技术水平的不断提高, SiGe BiCMOS低噪声放大器(LNA)广泛应用于空间射频收发系统的第一级模块. SiGe HBT作为SiGe BiCMOS LNA的核心器件,天然具有优异的低温特性、抗总剂量效应和抗位移损伤效应的能力,然而,其瞬态电荷收集引起的空间单粒子效应是制约其空间应用的瓶颈问题.本文基于SiGe BiCMOS工艺低噪声放大器开展了单粒子效应激光微束实验,并定位了激光单粒子效应敏感区域.实验结果表明, SiGe HBT瞬态电荷收集是引起SiGe BiCMOS LNA单粒子效应的主要原因. TCAD模拟表明,离子在CMOS区域入射时,电离径迹会越过深沟槽隔离结构,进入SiGe HBT区域产生电子空穴对并引起瞬态电荷收集. ADS电路模拟分析表明,单粒子脉冲瞬态电压在越过第1级与第2级之间的电容时,瞬态电压峰值骤降,这表明电容在传递单粒子效应产生的瞬态脉冲过程中起着重要作用.本文实验和模拟工作为SiGe BiCMOS LNA单粒子效应抗辐射设计加固提供了技术支持.     

Sensitivity of heavy-ion-induced single event burnout in SiC MOSFET

The energy deposition and electrothermal behavior of SiC metal-oxide-semiconductor field-effect transistor(MOSFET)under heavy ion radiation are investigated based on Monte Carlo method and TCAD numerical simulation.The Monte Carlo simulation results show that the density of heavy ion-induced energy deposition is the largest in the center of the heavy ion track.The time for energy deposition in SiC is on the order of picoseconds.The TCAD is used to simulate the single event burnout(SEB)sensitivity of SiC MOSFET at four representative incident positions and four incident depths.When heavy ions strike vertically from SiC MOSFET source electrode,the SiC MOSFET has the shortest SEB time and the lowest SEB voltage with respect to direct strike from the epitaxial layer,strike from the channel,and strike from the body diode region.High current and strong electric field simultaneously appear in the local area of SiC MOSFET,resulting in excessive power dissipation,further leading to excessive high lattice temperature.The gate-source junction area and the substrate-epitaxial layer junction area are both the regions where the SiC lattice temperature first reaches the SEB critical temperature.In the SEB simulation of SiC MOSFET at different incident depths,when the incident depth does not exceed the device's epitaxial layer,the heavy-ion-induced charge deposition is not enough to make lattice temperature reach the SEB critical temperature.     

MOS器件辐照过程和辐照后效应模拟

模拟MOS器件脉冲电离辐射响应和长时间恢复效应.假设隧道电子从硅进入氧化层和界面态的建立是辐射效应的恢复机理.在整个退火恢复期,采用卷积模型并考虑了栅偏置压的效应.模拟结果表明:退火过程所加栅偏压的大小以及隧道电子效应与建立的界面态所占比例的不同影响器件的恢复率.     

Dependence of single event upsets sensitivity of low energy proton on test factors in 65 nm SRAM

In order to accurately predict the single event upsets(SEU) rate of on-orbit proton, the influence of the proton energy distribution, incident angle, supply voltage, and test pattern on the height, width, and position of SEU peak of low energy protons(LEP) in 65 nm static random access memory(SRAM) are quantitatively evaluated and analyzed based on LEP testing data and Monte Carlo simulation. The results show that different initial proton energies used to degrade the beam energy will bring about the difference in the energy distribution of average proton energy at the surface and sensitive region of the device under test(DUT), which further leads to significant differences including the height of SEU peak and the threshold energy of SEU. Using the lowest initial proton energy is extremely important for SEU testing with low energy protons. The proton energy corresponding to the SEU peak shifts to higher average proton energies with the increase of the tilt angle, and the SEU peaks also increase significantly. The reduction of supply voltage lowers the critical charge of SEU, leading to the increase of LEP SEU cross section. For standard 6-transitor SRAM with bit-interleaving technology,SEU peak does not show clear dependence on three test patterns of logical checkerboard 55 H, all "1", and all "0". It should be noted that all the SEUs in 65 nm SRAM are single cell upset in LEP testing due to proton's low linear energy transfer(LET) value.     

Discussion of the metric in characterizing the single-event effect induced by heavy ions

The single-event effect(SEE) is the most serious problem in space environment.The modern semiconductor technology is concerned with the feasibility of the linear energy transfer(LET) as metric in characterizing SEE induced by heavy ions.In this paper,we calibrate the detailed static random access memory(SRAM) cell structure model of an advanced field programmable gate array(FPGA) device using the computer-aided design tool,and calculate the heavy ion energy loss in multi-layer metal utilizing Geant4.Based on the heavy ion accelerator experiment and numerical simulation,it is proved that the metric of LET at the device surface,ignoring the top metal material in the advanced semiconductor device,would underestimate the SEE.In the SEE evaluation in space radiation environment the top-layers on the semiconductor device must be taken into consideration.     

不同辐射环境下CMOS器件总剂量测试技术与损伤差异研究

对应用在不同辐射环境下HP4156半导体参数自动化在线测试系统以及脉冲总剂量效应在线测试系统进行了详细的介绍,说明其工作原理和技术指标,并利用这两套测试系统对典型CMOS器件4007在强光一号加速器脉冲硬X射线状态、长脉冲γ射线状态以及⁶⁰Co稳态γ射线状态下开展了不同辐射环境总剂量损伤效应的比较研究, 为今后深入进行此项工作打下了基础.