利用硅离子注入提高SOI材料的抗辐射性能

研究采用硅离子注入及高温退火的方法对SOI材料进行抗辐射加固．通过对比发现，制作在加固SOI衬底上的NMOS器件和CMOS反相器在总剂量辐射下性能恶化程度大大降低。陷阱电荷和界面电荷的分析解释了加固机理。结合实验结果和理论分析，证明硅离子注入能有效地加固SOI材料的抗辐射性能．

硅基光电子器件的辐射效应研究进展

硅基光电子器件与芯片技术是通信领域的下一代关键技术,在光通信、高性能计算、数据中心等领域有广阔的市场,在生物传感领域也有广泛应用.根据硅光器件高集成度、重量小等特性,可以预见硅基光电子芯片在空间通信、核电站、高能粒子实验等辐射环境中也极具应用前景.本文综述了硅基光电子器件在高能粒子环境下的辐射效应研究工作,阐述了电离和非电离辐射效应;针对无源器件和有源器件分别介绍了辐射效应和响应机理,包括波导、环形谐振器、调制器、探测器、激光器、光纤等.高能辐射对无源器件的影响主要包括结构加速氧化、晶格缺陷、非晶结构致密化等.对于光电探测器和激光器,辐射引起的位移损伤占主导地位,其中点缺陷引入的深能级会影响载流子响应导致器件性能变化,而电光调制器在辐射环境下的主要损伤机制是电离损伤,产生的缺陷电荷会影响载流子浓度从而改变有效折射率.本文最后展望了硅基光电集成器件的辐射加固思路和在空间环境中的应用前景.

对改性晶圆上制备的PDSOI NMOS器件热载流子效应的全面认识

通过与常规器件的对比,本文详细研究了在硅离子注入改性晶圆上制备的PDSOI NMOS的热载流子诱导退化现象。理论分析和TCAD模拟结果表明,硅离子注入在埋氧层中引入的电子陷阱能够捕获注入的电子,并通过改变电场来影响氧化层的热载流子退化。在不同的应力条件下,其效果也有所不同。对改性器件施加热载流子应力时,改性器件的前栅和背栅之间存在着更明显的相互作用。同时,探讨了总剂量辐照对改性器件热载流子退化的影响。在改性器件中存在辐照增强的热载流子退化,高温退火只能部分消除这一影响。

Utilizing a shallow trench isolation parasitic transistor to characterize the total ionizing dose effect of partially-depleted silicon-on-insulator input/output n-MOSFETs

We investigate the effects of 60 Co γ-ray irradiation on the 130 nm partially-depleted silicon-on-isolator(PDSOI)input/output(I/O) n-MOSFETs. A shallow trench isolation(STI) parasitic transistor is responsible for the observed hump in the back-gate transfer characteristic curve. The STI parasitic transistor, in which the trench oxide acts as the gate oxide,is sensitive to the radiation, and it introduces a new way to characterize the total ionizing dose(TID) responses in the STI oxide. A radiation enhanced drain induced barrier lower(DIBL) effect is observed in the STI parasitic transistor. It is manifested as the drain bias dependence of the radiation-induced off-state leakage and the increase of the DIBL parameter in the STI parasitic transistor after irradiation. Increasing the doping concentration in the whole body region or just near the STI sidewall can increase the threshold voltage of the STI parasitic transistor, and further reduce the radiation-induced off-state leakage. Moreover, we find that the radiation-induced trapped charge in the buried oxide leads to an obvious front-gate threshold voltage shift through the coupling effect. The high doping concentration in the body can effectively suppress the radiation-induced coupling effect.

Research on the radiation hardened SOI devices with single-step Si ion implantation

Silicon-on-insulator(SOI) devices are sensitive to the total ionizing dose effect due to the existence of buried oxide.In this paper,an extra single-step Si ion implantation into buried oxide layer prior to the normal complementary metal–oxide–semiconductor transistor(CMOS) process is used to harden the SOI wafer.The top-Si quality of the hardened SOI wafer is confirmed to be good enough for device manufacturing through various characterization methods.The radiation experiments show that the total ionizing dose tolerance of the Si implanted SOI device is improved significantly.The metastable electron traps introduced by Si implantation is also investigated by electrical stress.The results show that these traps are very instable,and electrons will tunnel into or out of the metastable electron traps quickly after hot-electroninjection or hot-hole-injection.

Total ionizing dose induced single transistor latchup in 130-nm PDSOI input/output NMOSFETs

Total ionizing dose induced single transistor latchup effects for 130 nm partially depleted silicon-on-insulator(PDSOI)NMOSFETs with the bodies floating were studied in this work. The latchup phenomenon strongly correlates with the bias configuration during irradiation. It is found that the high body doping concentration can make the devices less sensitive to the single transistor latchup effect, and the onset drain voltage at which latchup occurs can degrade as the total dose level rises. The mechanism of band-to-band tunneling(BBT) has been discussed. Two-dimensional simulations were conducted to evaluate the BBT effect. It is demonstrated that BBT combined with the positive trapped charge in the buried oxide(BOX) contributes a lot to the latchup effect.

The Enhanced Role of Shallow-Trench Isolation in Ionizing Radiation Damage of Narrow Width Devices in 0.2 µm Partially-Depleted Silicon-on-Insulator Technology

An anomalous total dose effect is observed in narrow-width devices fabricated in a 0.2μm partially-depleted silicon-on-insulator(SOI)technology.The previous radiation-induced narrow channel effect manifests itself with obvious threshold voltage shift after the transistors are subjected to total dose radiation in bulk technology.Nevertheless,a sharply increasing off-state leakage current dominates the total dose effects in narrow devices of this partially-depleted SOI technology instead of threshold voltage shifts.A radiation-induced positive charge trapping model is introduced to understand this phenomenon.The enhanced role of shallow-trench oxide induced by compressive mechanical stress in narrow devices is discussed in detail in terms of modification of the edge impurity density and charge trapping characteristics,which affect the total dose sensitivity.

Influence of Tilted Angle on Effective Linear Energy Transfer in Single Event Effect Tests for Integrated Circuits at 130 nm Technology Node

A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130 nm CMOS bulk Si and silicon-on-insulator(SOI) technologies. The effectiveness of linear energy transfer(LET) with a tilted ion beam at the 130 nm technology node is obtained. Tests of tilted angles θ=0°,30°and 60°with respect to the normal direction are performed under heav.y-ion Kr with certain power whose LET is about 40 MeVcm^2/mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cosθ, furthermore the effective LET for SOI is more closely in inverse proportion to cos θ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cos 0 very well, which is also specifically explained.

Bias dependence of a deep submicron NMOSFET response to total dose irradiation

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/SiO 2 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.

Total ionizing dose effect in an input/output device for flash memory

Input/output devices for flash memory are exposed to gamma ray irradiation.Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes.In this paper,we observed a larger increase of off-state leakage in the short channel device than in long one.However,a larger threshold voltage shift is observed for the narrow width device than for the wide one,which is well known as the radiation induced narrow channel effect.The radiation induced charge in the shallow trench isolation oxide influences the electric field of the narrow channel device.Also,the drain bias dependence of the off-state leakage after irradiation is observed,which is called the radiation enhanced drain induced barrier lowing effect.Finally,we found that substrate bias voltage can suppress the off-state leakage,while leading to more obvious hump effect.

Impact of substrate bias on radiation-induced edge effects in MOSFETs

This paper investigates the effects of gamma-ray irradiation on the Shallow-Trench Isolation (STI) leakage currents in 180-nm complementary metal oxide semiconductor technology.No hump effect in the subthreshold region is observed after irradiation,which is considered to be due to the thin STI corner oxide thickness.A negative substrate bias could effectively suppress the STI leakage,but it also impairs the device characteristics.The three-dimensional simulation is introduced to understand the impact of substrate bias.Moreover,we propose a simple method for extracting the best substrate bias value,which not only eliminates the STI leakage but also has the least impact on the device characteristics.

Metastable Electron Traps in Modified Silicon-on-Insulator Wafer

We perform the total ionizing radiation and electrical stress experiments to investigate the electrical characteristics of the modified silicon-on-insulator(SOI) wafers under different Si ion implantation conditions. It is confirmed that Si implantation into the buried oxide can create deep electron traps with large capture cross section to effectively improve the antiradiation capability of the SOI device. It is first proposed that the metastable electron traps accompanied with Si implantation can be avoided by adjusting the peak location of the Si implantation reasonably.

Enhanced radiation-induced narrow channel effects in 0.13-μm PDSOI nMOSFETs with shallow trench isolation

Total ionizing dose responses of different transistor geometries after being irradiated by ^(60)Co γ-rays, in 0.13-μm partially-depleted silicon-on-insulator(PD SOI) technology are investigated. The negative threshold voltage shift in an n-type metal-oxide semiconductor field effect transistor(nMOSFET) is inversely proportional to the channel width due to radiation-induced charges trapped in trench oxide, which is called the radiation-induced narrow channel effect(RINCE).The analysis based on a charge sharing model and three-dimensional technology computer aided design(TCAD) simulations demonstrate that phenomenon. The radiation-induced leakage currents under different drain biases are also discussed in detail.

新型高速单粒子翻转自恢复锁存器设计

航天器中芯片工作时钟频率的不断提高使得单粒子翻转(single-event-upset,SEU)效应对时序逻辑的影响更加显著。目前已经提出的辐射加固锁存器存在面积和延时较大、功耗较高且抗单粒子翻转能力有限的问题。针对这些问题,提出了一款基于130 nm部分耗尽绝缘体上硅(partially-depleted silicon on insulator,PD-SOI)工艺的高速单粒子辐射自恢复锁存器。在对电路设计进行介绍的基础上,与其他已经报道的电路进行了对比,并利用节点翻转分析和仿真波形验证了该锁存器具有抗单粒子翻转自恢复的功能。对比结果表明,与其他的抗单粒子翻转自恢复锁存器相比,在牺牲部分功耗的代价下,大幅减小了锁存器的面积和延时。本方案所提出的辐射加固锁存器的综合开销指标APDP较其他辐射加固锁存器平均节省了71.14%,适用于辐射环境下的对速度和可靠性有较高要求的电路,为国产宇航高可靠自研芯片提供了选择。

Enhanced Radiation Sensitivity in Short-Channel Partially Depleted Silicon-on-Insulator n-Type Metal-Oxide-Semiconductor Field Effect Transistors

The total ionizing dose effects of partially depleted silicon-on-insulator(SOI)transistors in a 0.13𝜈m technology are studied by^(60)Co𝛿-ray irradiation.Radiation enhanced drain-induced barrier lowering(DIBL)under different bias conditions is related to the parasitic bipolar in the SOI transistor and oxide trapped charge in the buried oxide,and it is experimentally observed for short channel transistors.The enhanced DIBL effect manifests as the DIBL parameter increases with total dose.Body doping concentration is a key factor affecting the total ionizing dose effect of the transistor.The low body doping transistor exhibits not only significant front gate threshold voltage shift as a result of the coupling effect,but also great off-state leakage at high drain voltage due to the enhanced DIBL effect.

Enhanced Total Ionizing Dose Susceptibility in Narrow Channel Devices

Total ionizing dose effects of different transistor sizes in a 0.18µm technology are studied by 60Coγ-ray irradiation.Significant threshold voltage shift is observed for the narrow channel devices,which is called the radiation induced narrow channel effect(RINCE).A charge sharing model is introduced to understand the phenomenon.The devices'characteristic degradations after irradiation,such as threshold voltage shift,increase in on-state current under different drain biases and substrate biases,are discussed in detail.Radiation induced oxide trapped charge at the edges of shallow trench isolation plays an important role in the RINCE.Narrow channel devices are susceptible to the total ionizing dose effect.

Pseudo-MOS晶体管和nMOS晶体管评估SOI材料抗总剂量辐射能力的比较

本文用辐射加固和未加固的SIMOX(注氧隔离)SOI(绝缘体上硅)材料制作了Pseudo-MOS晶体管和nMOS晶体管,并进行了X射线总剂量辐射实验。结果表明加固工艺能有效提高SIMOXSOI材料的抗总剂量辐射能力,同时也表明Pseudo-MOS晶体管能有效的替代nMOS晶体管对SOI材料的抗总剂量辐射能力进行评估。

0.18μm MOSFET器件的总剂量辐照效应

对0.18μm metal-oxide-semiconductor field-effect-transistor(MOSFET)器件进行γ射线辐照实验,讨论分析器件辐照前后关态漏电流、阈值电压、跨导、栅电流、亚阈值斜率等特性参数的变化,研究深亚微米器件的总剂量效应.通过在隔离氧化物中引入等效陷阱电荷,三维模拟结果与实验结果符合很好.深亚微米器件栅氧化层对总剂量辐照不敏感,浅沟槽隔离氧化物是导致器件性能退化的主要因素.

硅离子注入引入纳米晶对SIMOX材料进行总剂量辐射加固

本研究工作采用硅离子注入和高温退火工艺对SIMOX材料的BOX层进行总剂量辐射加固。辐射实验结果证明了该加固方法的有效性。PL谱和HRTEM图像显示了硅离子注入及退火工艺在材料的BOX层中引入了Si纳米晶,形成电子陷阱能级,有效俘获电子,从而提高了材料BOX层的抗总剂量辐射能力。

总剂量辐照效应对窄沟道SOI NMOSFET器件的影响

本文深入研究了130nm Silicon-on-Insulator(SOI)技术下的窄沟道n型metal-oxide-semiconductor-field-effect-transistor(MOSFET)器件的总剂量辐照效应.在总剂量辐照下,相比于宽沟道器件,窄沟道器件的阈值电压漂移更为明显.论文利用电荷守恒定律很好地解释了辐照增强的窄沟道效应.另外,本文首次发现,对于工作在线性区的窄沟道器件,辐照产生的浅沟槽隔离氧化物(STI)陷阱正电荷会增加沟道区载流子之间的碰撞概率和沟道表面粗糙度散射,从而导致主沟道晶体管的载流子迁移率退化以及跨导降低.最后,对辐照增强的窄沟效应以及迁移率退化进行了三维器件仿真模拟,仿真结果与实验结果符合得很好.