单粒子效应课件.ppt

单粒子效应（Single Event Effect）,Contents,Radiation Environment,Semiconductor Devices,Cosmic rays,Nuclear explosions,Nuclear power plant,Atmospheric radiation,Radiation effects on semiconductor,Classification,非破坏性单粒子效应 (Soft Error) - 单粒子翻转（SEU: Single Event Upsets ） - 单粒子瞬变效应（SET: Single Event Transient） 灾难性单粒子效应 (Hard Failure) - 单粒子锁定（SEL: Single Event Latchup） - 单粒子烧毁（SEB: Single Event Burnout） - 单粒子门断裂（SEGR: Single Event Gate Rupture）,Sources of Single Event Effects,Space applications: High-energy heavy ions Long range in Si, large LET, direct interaction High-energy protons (trapped, solar, cosmic) Direct / Indirect interaction through nuclear reactions Terrestrial and avionic applications: High energy neutrons (cosmic ray byproducts) Indirect interaction through nuclear reactions Low energy neutrons (thermal) Indirect interaction via 10B nuclear reaction Alpha particles from radioactive decay of contaminants (from U, Th decay chains) in the chip/package/solder Short range in Si, small LET, direct interaction,Why do we study SEE?,1975 年美国发现通信卫星的数字电路JK 触发器由于单个重核粒子的作用被触发。 陆续发现陶瓷管壳所含的微量放射性同位素铀和钍放出的粒子以及宇宙射线中的高能中子、质子、电子等, 都能使集成电路产生单粒子效应。 进一步的模拟试验和在轨卫星的测试证实: 几乎所有的集成电路都能产生这种效应。,（19711986）,Why do we study SEE?,Moores law is (self-)validated by reducing the device dimension over the years, by scaling down the minimum feature size of the CMOS technology node,What is SEE?,Single Event Effect (SEE): perturbation of the behavior of electronic (optoelectronic) devices, circuits and/or systems produced by a single ionizing particle.,Charge generation Direct ionizing (Heavy ion) Indirect ionizing (Proton) Charge collection Prompt component Drift/funneling (high field regions) Delayed component Diffusion (low field regions),Charge generation,An ionizing particle generates a (dense) track of electron-hole pairs in semiconductors (Silicon) and dielectrics (SiO2); The number of generated carriers is proportional to the particle Linear Energy Transfer (LET) coefficient (MeVcm2/mg), i.e., the ionizing energy loss/unit path length (Energy / e-h pair: 3.6 eV in Si, 17 eV in SiO2),Charge generation and collection,Under an external electric field the two columns of carriers recombine and drift: many electrons and holes survive in Si, fewer in SiO2; Eventually, a net negative/positive charge can be collected at sensitive nodes: if this charge exceeds a threshold value (critical charge) an event may be observed affecting the circuit.,Charge collection in a reverse biased p-n junction,Charge funneling model,Time evolution of charge collection,Single Event Upset (SEU) in SRAM,How to study SEE?,SEE tests are performed to evaluate the expected error/failure rate of the device/system in the specific operating environment (Space, HEP, Avionic, Sea level,) by using: Ion beams from accelerators Neutron beams Alpha sources Lasers A large number of devices operating under low intensity radiation (unaccelerated tests: the Rosetta experiment) The SEE sensitivity of each SEE type (SEU, SEL, SEB, ) in any particular device is evaluated by measuring the corresponding cross section vs LET: Cross section : (LET) = # Events / particle fluence (cm2) The error rates in operating condition is derived from cross sections and the features (nature of particles, corresponding fluxes, mission duration) of the actual environment Error rate = # errors / device day,accelerated tests,SEE cross section and threshold LET,LETth is the minimum (threshold) LET to cause the specific SEE. The saturation cross section sat is approached at high LET values. The (LET) curve is obtained by measuring the cross section at a few LET values and fitting data with a Weibull curve.,Basic principle of SEE test,“School book” Example,Standards,Accelerators,Nuclear reactor,反应堆,Hardening,Single Event Effects in devices/circuits can be mitigated by using different strategies at different levels. For instance: Circuit level, by using specific technologies or processes for fabrication (such as epi-CMOS, SOI, additional capacitors in SRAM, or rad-hardened electronic components) Design level, by using ad hoc logic structures aiming to SEE immunity (such as SEE immune latches) System level, by modifying