具有HfN/HfO2栅结构的p型MOSFET中的负偏置-温度不稳定性研究

研究了HfN/HfO₂高K栅结构p型金属-氧化物-半导体(MOS)晶体管(MOSFET)中，负 偏置-温度应力引起的阈值电压不稳定性(NBTI)特征.HfN/HfO₂高K栅结构的等效 氧化层厚度(EOT)为1.3nm，内含原生缺陷密度较低.研究表明，由于所制备的HfN/HfO₂ 高K栅结构具有低的原生缺陷密度，因此在p-MOSFET器件中观察到的NBTI属HfN/HfO2高K栅结构的本征特征，而非工艺缺陷引起的；进一步研究表明，该HfN/HfO₂高K栅结构中观察到的NBTI与传统的SiO₂基栅介质p-MOSFET器件中观察 到的NBTI具有类似的特征，可以被所谓的反应-扩散(R-D)模型表征： HfN/HfO₂ 栅结构p-MOSFET器件的NBTI效应的起源可以归为衬底注入空穴诱导的界面反应机理，即在负 偏置和温度应力作用下，从Si衬底注入的空穴诱导了Si衬底界面Si-H键断裂这一化学反应的 发生，并由此产生了Si^＋陷阱在Si衬底界面的积累和H原子在介质层内部的扩散 ，这种Si^＋陷阱的界面积累和H原子的扩散导致了器件NBTI效应的发生. 关键词： 高K栅介质 负偏置-温度不稳定性(NBTI) 反应-扩散(R-D)模型     

超深亚微米PMOSFET的自愈合效应

主要研究负栅压偏置不稳定性(negative bias temperature instability，NBTI)效应中的自愈合效应，研究了器件阈值电压随着恢复时间和应力时间的恢复规律.研究表明器件的退化可以恢复是由于NBTI应力后界面态被氢钝化. 关键词： 负偏置温度不稳定性效应 自愈合效应 应力时间 PMOSFET     

p型硅MOS结构Si/SiO2界面及其附近的深能级与界面态

用深能级瞬态谱(DLTS)技术系统研究了Si/SiO₂界面附近的深能级和界面态。结果表明,在热氧化形成的Si/SiO₂界面及其附近经常存在一个浓度很高的深能级,它具有若干有趣的特殊性质,例如它的DLTS峰高度强烈地依赖于温度,以及当栅偏压使费密能级与界面处硅价带顶的距离明显小于深能级与价带顶的距离时,仍然可以观测到一个很强的DLTS峰。另外,用最新方法测量的Si/SiO₂界面连续态的空穴俘获截面与温度有关,而与能量位置无明显关系,DLTS测 关键词：     

Si-W/Si/SiO2/Si(100)的横截面电子显微镜研究

本文用横截面电子显微镜法分析了Si-W/Si/SiO₂/Si(100)在440—1000℃退火后的晶化过程,以及各个界面的变化情况.发现Si-W合金膜中,WSi₂并未优先在表面、界面处形成晶核.当退火温度不高于700℃时,反应在合金膜内发生,表面、界面起伏和缓.退火温度高达800—1000℃时,界面、表面出现原子扩散,造成剧烈的界面起伏;表面则出现小的热沟槽,Si/SiO₂界面也出现高分辨电子显微镜才能观察到的起伏.表面、界面的原子迁移的动力来源于晶界与表面、界面张力.由于SiO₂中Si—O键很稳定,不易发生Si和O在界面处的互扩散,所以Si/SiO₂界面起伏很小. 关键词：     

在p型硅MOS结构Si/SiO2界面区中与金有关的界面态和深能级

用深能级瞬态谱(DLTS)技术详细研究了金在p型<111>晶向硅MOS结构Si/SiO₂界面区中的行为。结果表明,金与Si/SiO₂界面缺陷H_it(0.494)相互作用形成新的缺陷Au-H_it(0.445),和金在硅的禁带中产生一个能量分布很广的连续界面态,利用这些界面态可以合理地解释金使硅MOS结构平带电压向正方向移动的物理机制。结果还表明,在Si/SiO₂界面附近的半导体中,金施主中心的剖面分 关键词：     

氧化硅层厚度对Si/SiO2界面电子态结构与光学性质的影响

在氧化硅上生长纳米硅晶,保持氧化硅的直接带隙结构,降低其能带带隙,以用于发光和光伏。采用基于密度泛函理论的第一性原理研究了块体α-方石英、薄膜α-方石英、Si/SiO₂界面的电子态结构和Si/SiO₂界面的光学性质。结果显示,其均为直接带隙半导体,当薄膜α-方石英厚度和Si/SiO₂界面氧化硅层厚度逐渐减小时,能带带隙均逐渐变大,表现出明显的量子限制效应。光学性质计算结果表明：Si/SiO₂界面虚部介电峰和吸收峰的峰值随氧化硅层厚度降低而显著升高,且峰位向高能量方向蓝移。使用脉冲激光沉积制备了氧化硅上硅晶薄膜,测量了Si/SiO₂界面样品的PL光谱,在670 nm处存在一个强的发光峰,在波长超过830 nm后,Si/SiO₂界面样品的发光强度不断升高。因此,可以通过控制Si/SiO₂界面氧化硅层厚度有效地调控Si/SiO₂界面的电子态结构和光学性质,引进边缘电子态,调控其带隙进入1～2 eV区间,获取硅基发光材料...     

Au/(SiO2/Si/SiO2)纳米双势垒/n+-Si结构的电致发光研究

利用射频磁控溅射方法,在n⁺-Si衬底上淀积SiO₂/Si/SiO_{2纳米双势垒单势阱结构,其中Si层厚度为2至4nm,间隔为0.2nm,邻近n⁺-S i衬底的SiO2层厚度固定为1.5nm,另一SiO2层厚度固定为3nm.为了 对比研究,还制备了Si层厚度为零的结构,即SiO2(4.5nm)/n⁺-Si 结构.在经过600℃氮气下退火30min,正面蒸上半透明Au膜,背面也蒸Au作欧姆接触后,所 有样品都在反向偏置(n^＋-Si的电压高于Au电极的电压)下发光,而在正向偏压 下不发光.在一定的反向偏置下,电流和电致发光强度都随Si层厚度的增加而同步振荡,位 相相同.所有样品的电致发光谱都可分解为相对高度不等的中心位于2.26eV(550nm)和1.85eV (670nm)两个高斯型发光峰.分析指出该结构电致发光的机制是：反向偏压下的强电场使Au/( SiO2/Si/SiO2)纳米双势垒/n⁺-Si结构发生了雪崩击穿 ,产生大量的电子-空穴对,它们在纳米SiO2层中的发光中心(缺陷或杂质)上复 合而发光. 关键词： 电致发光 纳米双势垒 高斯型发光峰 雪崩击穿}     

Co/Co3O4/PZT多铁复合薄膜的交换偏置效应及其磁电耦合特性

本文采用溶胶-凝胶工艺并结合脉冲激光沉积技术, 在Pt/Ti/SiO₂/Si衬底上制备了Co/Co₃O₄/PZT多铁复合薄膜. 对复合薄膜的微结构和组分进行了表征, 并系统研究了复合薄膜中的交换偏置效应及其对磁电耦合作用的影响. 研究结果表明, 复合薄膜在77 K具有明显的交换偏置效应, 交换偏置场达到80 Oe, 且交换偏置场及矫顽场均随温度降低而增大. 当温度降低到10 K时, 交换偏置场增至160 Oe. X射线光电子能谱(XPS)测试结果证实在Co和Co₃O₄界面处存在约5 nm厚的CoO层, 表明77 K下的交换偏置效应源自反铁磁的CoO层对Co的钉扎作用. 观察到复合薄膜的电容-温度曲线随着外加磁场大小和方向的改变而呈现出规律性的变化, 表明复合薄膜存在磁电耦合效应. 进一步研究发现, 在低温下复合薄膜呈现出各向异性的磁电容效应, 与磁场大小和方向密切相关. 复合薄膜的这种磁电耦合特性主要与复合体系的交换偏置效应及基于界面应力传递的磁电耦合作用有关, 本文对其中的物理机理进行了详细讨论与分析.     

Si基Si3N4/SiO2双层膜驻极体的电荷储存与输运

利用等温表面电位衰减及热刺激放电(thermally stimulated discharge,TSD)方法探讨了恒栅压电晕充电经常压化学气相沉积(APCVD)的Si基Si3N4和热生长SiO₂双层薄膜驻极体电荷的存储特性.结果表明:在常温环境中,300℃高温下,以及95%相对湿度时的60℃条件下,所有试样表现出极好的电荷储存稳定性.对于负电晕充电试样,其电荷输运受慢再捕获效应(slow retrapping effect)控制;用热离子发射模型来描述了正电晕充电Si₃N₄/SiO₂驻极体的正电荷输运特性. 关键词： 驻极体 薄膜 电荷储存 热离子发射     

SiC外延层表面化学态的研究

用高分辨X射线光电子能谱仪(XPS)和傅里叶变换红外(FTIR)光谱仪研究了SiC外延层表面的组分结构. XPS宽扫描谱,红外掠反射吸收谱及红外镜面反射谱的解析结果说明SiC外延层表面是由Si—O—Si和Si—CH₂—Si聚合体构成的非晶SiC_xO_y:H. SiC外延层表面的化学态结构为Si(CH₂)₄,SiO(CH₂)₃,SiO₂(CH₃)₂,SiO₃(CH₃),Si—Si,游离H₂O,缔合OH,Si—OH,O和O₂. 根据化学态结构和元素电负性确定了化学态的各原子芯电子束缚能顺序,并与XPS窄扫描谱拟合结果相对比,建立了化学态与其束缚能的对应关系,进而用Si(CH₂)₄的实际C 1s束缚能值进行校正,确定了各化学态的束缚能. 结果发现,除了SiC_xO_y(x=1,2,3,4,x+y=4)的Si 2p束缚能彼此不同外,其C 1s和O 1s彼此也不相同,其中SiO₂(CH₃)₂和SiO₃(CH₃)的C 1s束缚能与CH_m和C—O中C 1s的相近,对此从化学态结构,元素电负性和邻位效应进行了解释. 关键词： SiC 化学态 XPS FTIR     

New insight into the parasitic bipolar amplification effect in single event transient production

In this paper, a new method is proposed to study the mechanism of charge collection in single event transient (SET) production in 90 nm bulk complementary metal oxide semiconductor (CMOS) technology. We find that different from the case in the pMOSFET, the parasitic bipolar amplification effect (bipolar effect) in the balanced inverter does not exist in the nMOSFET after the ion striking. The influence of the substrate process on the bipolar effect is also studied in the pMOSFET. We find that the bipolar effect can be effectively mitigated by a buried deep P⁺-well layer and can be removed by a buried SO₂ layer.     

Mechanism of single-event transient pulse quenching between dummy gate isolated logic nodes

As integrated circuits scale down in size,a single high-energy ion strike often affects multiple adjacent logic nodes.The so-called single-event transient(SET)pulse quenching induced by single-event charge sharing collection has been widely studied.In this paper,SET pulse quenching enhancement is found in dummy gate isolated adjacent logic nodes compared with that isolated by the common shallow trench isolation(STI).The physical mechanism is studied in depth and this isolation technique is explored for SET mitigation in combinational standard cells.Three-dimensional(3D)technology computer-aided design simulation(TCAD)results show that this technique can achieve efficient SET mitigation.     

The dual role of multiple-transistor charge sharing collection in single-event transients

As technologies scale down in size, multiple-transistors being affected by a single ion has become a universal phenomenon, and some new effects are present in single event transients (SETs) due to the charge sharing collection of the adjacent multiple-transistors. In this paper, not only the off-state p-channel metal-oxide semiconductor field-effect transistor (PMOS FET), but also the on-state PMOS is struck by a heavy-ion in the two-transistor inverter chain, due to the charge sharing collection and the electrical interaction. The SET induced by striking the off-state PMOS is efficiently mitigated by the pulse quenching effect, but the SET induced by striking the on-state PMOS becomes dominant. It is indicated in this study that in the advanced technologies, the SET will no longer just be induced by an ion striking the off-state transistor, and the SET sensitive region will no longer just surround the off-state transistor either, as it is in the older technologies. We also discuss this issue in a three-transistor inverter in depth, and the study illustrates that the three-transistor inverter is still a better replacement for spaceborne integrated circuit design in advanced technologies.     

不同偏置影响锗硅异质结双极晶体管单粒子效应的三维数值仿真研究

针对国产锗硅异质结双极晶体管(SiGe HBT),采用半导体器件三维计算机模拟工具,建立单粒子效应三维损伤模型,研究不同偏置状态对SiGe HBT单粒子效应的影响.分析比较不同偏置下重离子入射器件后,各端口电流瞬变峰值和电荷收集量随时间的变化关系,获得SiGe HBT单粒子效应与偏置的响应关系.结果表明:不同端口对单粒子效应响应的最劣偏置不同,同一端口电荷收集量和瞬变电流峰值的最劣偏置也有所差异.载流子输运方式变化和外加电场影响是造成这种现象的主要原因.     

Three-dimensional simulation of fabrication process-dependent effects on single event effects of SiGe heterojunction bipolar transistor

The fabrication process dependent effects on single event effects(SEEs) are investigated in a commercial silicon–germanium heterojunction bipolar transistor(SiGe HBT) using three-dimensional(3D) TCAD simulations. The influences of device structure and doping concentration on SEEs are discussed via analysis of current transient and charge collection induced by ions strike. The results show that the SEEs representation of current transient is different from representation of the charge collection for the same process parameters. To be specific, the area of C/S junction is the key parameter that affects charge collection of SEE. Both current transient and charge collection are dependent on the doping of collector and substrate. The base doping slightly influences transient currents of base, emitter, and collector terminals. However, the SEEs of SiGe HBT are hardly affected by the doping of epitaxial base and the content of Ge.     

Synergistic effect of total ionizing dose on single event effect induced by pulsed laser microbeam on SiGe heterojunction bipolar transistor

The synergistic effect of total ionizing dose(TID) on single event effect(SEE) in SiGe heterojunction bipolar transistor(HBT) is investigated in a series of experiments. The SiGe HBTs after being exposed to 60 Co g irradiation are struck by pulsed laser to simulate SEE. The SEE transient currents and collected charges of the un-irradiated device are compared with those of the devices which are irradiated at high and low dose rate with various biases. The results show that the SEE damage to un-irradiated device is more serious than that to irradiated SiGe HBT at a low applied voltage of laser test. In addition, the g irradiations at forward and all-grounded bias have an obvious influence on SEE in the SiGe HBT, but the synergistic effect after cutting off the g irradiation is not significant. The influence of positive oxide-trap charges induced by TID on the distortion of electric field in SEE is the major factor of the synergistic effect. Moreover, the recombination of interface traps also plays a role in charge collection.     

The modulation effect of substrate doping on multi-node charge collection and single-event transient propagation in 90-nm bulk complementary metal-oxide semiconductor technology

Variation of substrate background doping will affect the charge collection of active and passive MOSFETs in complementary metal-oxide semiconductor (CMOS) technologies, which are significant for charge sharing, thus affecting the propagated single event transient pulsewidths in circuits. The trends of charge collected by the drain of a positive channel metal-oxide semiconductor (PMOS) and an N metal-oxide semiconductor (NMOS) are opposite as the substrate doping increases. The PMOS source will inject carriers after strike and the amount of charge injected will increase as the substrate doping increases, whereas the source of the NMOS will mainly collect carriers and the source of the NMOS can also inject electrons when the substrate doping is light enough. Additionally, it indicates that substrate doping mainly affects the bipolar amplification component of a single-event transient current, and has little effect on the drift and diffusion. The change in substrate doping has a much greater effect on PMOS than on NMOS.     

Parasitic bipolar amplification in single event transient and its temperature dependence

Using three-dimensional technology computer-aided design (TCAD) simulation, parasitic bipolar amplification in single event transient (SET) current of single transistor and its temperature dependence are studied. We quantify the contributions of different current components in SET current pulse, and it is found that the proportion of parasitic bipolar amplification in total collected charge is about 30% in both 130-nm and 90-nm technologies. The temperature dependence of parasitic bipolar amplification and the mechanism of SET pulse are also investigated and quantified. The results show that the proportion of charge induced by parasitic bipolar increases with rising temperature, which illustrates that the parasitic bipolar amplification plays an important role in the charge collection of single transistor.     

Parasitic bipolar amplification in a single event transient and its temperature dependence

Using three-dimensional technology computer-aided design (TCAD) simulation, parasitic bipolar amplification in a single event transient (SET) current of a single transistor and its temperature dependence are studied. We quantify the contributions of different current components in a SET current pulse, and it is found that the proportion of parasitic bipolar amplification in total collected charge is about 30% in both 130-nm and 90-nm technologies. The temperature dependence of parasitic bipolar amplification and the mechanism of the SET pulse are also investigated and quantified. The results show that the proportion of charge induced by parasitic bipolar increases with rising temperature, which illustrates that the parasitic bipolar amplification plays an important role in the charge collection of a single transistor.     

Recovery of single event upset in advanced complementary metalben oxide semiconductor static random access memory cells

Using computer-aided design three-dimensional (3D) simulation technology, the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied. It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings. It cannot exhibit the recovery effect. It is also indicated that the upset linear energy transfer (LET) threshold is kept constant while the recovery LET threshold increases as the spacing increases. Additionally, the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect, thus strengthening the recovery ability.