新型槽栅nMOSFET热载流子效应的模拟研究

应用二维器件仿真程序 PISCES- ,对槽栅结构和平面结构器件的特性进行了模拟比较 ,讨论了槽栅结构 MOSFET的沟道电场特征及其对热载流子效应的影响。槽栅结构对抑制短沟道效应和抗热载流子效应是十分有利的 ,而此种结构对热载流子的敏感 ,使器件的亚阈值特性、输出特性变化较大     

异质栅MOSFET热载流子效应的研究

异质栅MOSFET器件的栅极由具有不同功函数的两种材料拼接而成,能够提高载流子输运速度、抑制阈值电压漂移等.文中比较了异质栅MOSFET和常规MOSFET的热载流子退化特性.通过使用器件数值模拟软件MEDICI,对能有效监测热载流子效应的参数,例如电场、衬底电流和栅电流等参数进行仿真.将仿真结果与常规MOSFET对比,从抑制热载流子效应方面验证了新结构器件的高性能.     

不同栅氧厚度NMOS管的热载流子效应

文章主要讨论在相同工艺条件下,针对不同栅氧厚度(例如:Tox分别为150A、200A、 250A)的NMOSFET进行加速应力试验,在试验中当某些参数的漂移量达到失效判据规定的值时(例如:阈值电压改变50mV),可以得到器件的应力寿命,由此估计该器件在正常工作条件下的寿命值, 并对该工艺的热载流子注入效应进行评价。     

超薄栅MOS器件热载流子应力下SILC的产生机制

通过测量界面陷阱的产生,研究了超薄栅nMOS和pMOS器件在热载流子应力下的应力感应漏电流(SILC).在实验结果的基础上,发现对于不同器件类型(n沟和p沟)、不同沟道长度(1、0.5、0.275和0.135μm)、不同栅氧化层厚度(4和2.5nm),热载流子应力后的SILC产生和界面陷阱产生之间均存在线性关系.这些实验证据表明MOS器件减薄后,SILC的产生与界面陷阱关系非常密切.     

超薄栅MOS器件热载流子应力下SILC的产生机制

通过测量界面陷阱的产生,研究了超薄栅n MOS和p MOS器件在热载流子应力下的应力感应漏电流( SIL C) .在实验结果的基础上,发现对于不同器件类型( n沟和p沟)、不同沟道长度( 1、0 .5、0 .2 75和0 .13 5 μm)、不同栅氧化层厚度( 4和2 .5 nm) ,热载流子应力后的SIL C产生和界面陷阱产生之间均存在线性关系.这些实验证据表明MOS器件减薄后,SIL C的产生与界面陷阱关系非常密切     

不同栅压应力下1.8V pMOS热载流子退化机理研究

本文详细研究了不同栅压应力下1.8V pMOS器件的热载流子退化机理.研究结果表明,随着栅压应力增加,电子注入机制逐渐转化为空穴注入机制,使得pMOS漏极饱和电流(I_dsat)、漏极线性电流(I_dlin)及阈值电压(V_th)等性能参数退化量逐渐增加,但在V_gs=90%*V_ds时,因为没有载流子注入栅氧层,使得退化趋势出现转折.此外,研究还发现,界面态位于耗尽区时对空穴迁移率的影响小于其位于非耗尽区时的影响,致使正向I_dsat退化小于反向I_dsat退化,然而,正反向I_dlin退化却相同,这是因为I_dlin状态下器件整个沟道区均处于非耗尽状态.     

一种用于提取LDD结构n-MOSFET热载流子应力下界面陷阱产生的改进方法

提出了一种新的基于电荷泵技术和直流电流法的改进方法,用于提取LDD n-MOSFET沟道区与漏区的界面陷阱产生.这种方法对于初始样品以及热载流子应力退化后的样品都适用.采用这种方法可以准确地确定界面陷阱在沟道区与漏区的产生,从而有利于更深入地研究LDD结构器件的退化机制.     

一种用于提取LDD结构n-MOSFET热载流子应力下界面陷阱产生的改进方法

提出了一种新的基于电荷泵技术和直流电流法的改进方法,用于提取LDDn MOSFET沟道区与漏区的界面陷阱产生.这种方法对于初始样品以及热载流子应力退化后的样品都适用.采用这种方法可以准确地确定界面陷阱在沟道区与漏区的产生,从而有利于更深入地研究LDD结构器件的退化机制.     

热载流子应力下超薄栅pMOS器件氧化层陷阱电荷的表征

利用电荷泵技术研究了4nm pMOSFET的热载流子应力下氧化层陷阱电荷的产生行为.首先,对于不同沟道长度下的热载流子退化,通过直接的实验证据,发现空穴陷阱俘获特性与应力时间呈对数关系.然后对不同应力电压、不同沟道长度下氧化层陷阱电荷(包括空穴和电子陷阱俘获)的产生做了进一步的分析.发现对于pMOSFET的热载流子退化,氧化层陷阱电荷产生分两步过程:在较短的应力初期,电子陷阱俘获是主要机制;而随着应力时间增加,空穴陷阱俘获作用逐渐显著,最后主导了氧化层陷阱电荷的产生.     

热载流子应力下超薄栅p MOS器件氧化层陷阱电荷的表征

利用电荷泵技术研究了 4nmpMOSFET的热载流子应力下氧化层陷阱电荷的产生行为 .首先 ,对于不同沟道长度下的热载流子退化 ,通过直接的实验证据 ,发现空穴陷阱俘获特性与应力时间呈对数关系 .然后对不同应力电压、不同沟道长度下氧化层陷阱电荷 (包括空穴和电子陷阱俘获 )的产生做了进一步的分析 .发现对于 pMOSFET的热载流子退化 ,氧化层陷阱电荷产生分两步过程 :在较短的应力初期 ,电子陷阱俘获是主要机制 ;而随着应力时间增加 ,空穴陷阱俘获作用逐渐显著 ,最后主导了氧化层陷阱电荷的产生.     

Hot-carrier-induced on-resistance degradation of step gate oxide NLDMOS

The hot-carrier-induced on-resistance degradations of step gate oxide NLDMOS(SG-NLDMOS) transistors are investigated in detail by a DC voltage stress experiment,a TCAD simulation and a charge pumping test.For different stress conditions,degradation behaviors of SG-NLDMOS transistors are analyzed and degradation mechanisms are presented.Then the effect of various doses of n-type drain drift(NDD) region implant on R_(on) degradation is investigated.Experimental results show that a lower NDD dosage can redu...     

SOI NLIGBT热载流子效应研究

SOI NLIGBT中热载流子效应分别通过直流电压的应力测试、TCAD仿真和电荷泵测试三种方法进行了研究。其中,不同直流电压应力条件下测得的衬底电流Isub和导通电阻Ron用来评估因热载流子效应引起的器件退化程度。为了进行理论分析,对器件内部的电场强度和碰撞离化率也进行了仿真。测试得到的电荷泵电流直接验证了器件表面的损伤程度。最后讨论了SOI LIGBT在不同栅压条件下的退化机制。     

NLDMOS器件性能优化及分析

提出一种改善n型横向双扩散金属氧化物半导体(NLDMOS)器件性能的工艺方法。该方法基于某公司0.18μm标准工艺流程,通过在NLDMOS的共源处增加一道离子注入,引出衬底电荷,以优化NLDMOS器件的击穿电压(Vb)与比导通电阻(Rsp)。选择不同的注入离子浓度与快速热退火时间,研究了器件的Vb与Rsp变化。由于离子激活效率不足,单纯增加20%的注入离子浓度,器件的耐压性能提升极小,采用增加20%注入离子浓度结合延长20s快速热退火时间的方法,NLDMOS器件的Vb提高约2.7%,同时Rsp仅增加0.9%左右。     

不同偏置条件下PMOSFETs的剂量率效应研究

研究了不同剂量率、不同偏置条件下,PMOSFETs的辐照响应特性;并对高剂量率辐照后的器件进行了与低剂量率辐照等时的室温退火。结果表明,随着剂量率的降低,PMOSFETs阈值电压的漂移更加明显;不同偏置条件、不同剂量率范围内表现出TDE和ELDRS两种不同的剂量率效应。利用亚阈分离技术对影响阈值电压漂移的氧化物陷阱电荷和界面态进行了详细的机理分析,认为ELDRS效应的产生是由界面态密度的差异导致的。     

Dose-rate effects of p-channel metal oxide semiconductor field-effect transistors at various biasing conditions

The total-dose response and annealing effect of p-channel metal oxide semiconductor field-effect transistors (PMOSFETs) were investigated at various dose rates and biasing conditions.The results show that the shift of threshold voltage is more obvious when the dose rate is decreased.Under the various dose rates and biasing conditions,some have exhibited a time-dependent effect and others showed enhanced low-dose-rate sensitivity (ELDRS).Finally,using the subthreshold-separating method,the threshold-voltage shift is separated into shifts due to interface states and oxidetrapped charges,and the underlying mechanisms of the observed effects are discussed.It has been indicated that the ELDRS effect results from the different quantities of the interface states generated at high and low dose rates.     

Comparative study of AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors with Al2O3 and HfO2 gate oxide

AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOSHFETs) with Al₂O₃ gate oxide which was deposited by atomic layer deposition (ALD) were fabricated and their performance was then compared with that of AlGaN/GaN MOSHFETs with HfO₂ gate oxide. The capacitance (C)-voltage (V) curve of the Al₂O₃/GaN MOS diodes showed a lower hysteresis and lower interface state density than the C-V curve of the HfO₂/GaN diodes, indicating better quality of the Al₂O₃/GaN interface. The saturation of drain current in the I_D-V_GS relation of the Al₂O₃ AlGaN/GaN MOSHFETs was not as pronounced as that of the HfO₂ AlGaN/GaN MOSHFETs. The gate leakage current of the Al₂O₃ MOSHFET was five to eight orders of magnitude smaller than that of the HfO₂ MOSHFETs.     

Microstructure of reactively sputtered oxide diffusion barriers

Molybdenum oxide (Mo_1-x O _x ) and ruthenium oxide (RuO₂) films were prepared by rf reactive sputtering of Mo or Ru targets in an O₂/Ar plasma. Both films exhibit metallic conductivities. The influence of the deposition parameters on the phase that forms and on the microstructure of Mo_1-x O _x and RuO₂ films is reported. A phase transformation is observed in Mo_1-x O _x films subjected to heat treatment. The diffusion barrier performance of Mo_1-x O _x and RuO₂ layers interposed between Al and Si is compared.     

Structural and interfacial properties of high-k HfOxNy gate dielectric films

The thermal stability and interfacial characteristics for hafnium oxynitride (HfO_xN_y) gate dielectrics formed on Si (1 0 0) by plasma oxidation of sputtered HfN films have been investigated. X-ray diffraction results show that the crystallization temperature of nitrogen-incorporated HfO₂ films increases compared to HfO₂ films. Analyses by X-ray photoelectron spectroscopy confirm the nitrogen incorporation in the as-deposited sample and nitrogen substitution by oxygen in the annealed species. Results of FTIR characterization indicate that the growth of the interfacial SiO₂ layer is suppressed in HfO_xN_y films compared to HfO₂ films annealed in N₂ ambient. The growth mechanism of the interfacial layer is discussed in detail.     

一种用于分析接触电阻对OTFT的性能影响的新方法研究

一种通用的,可用于分析OTFT接触电阻对OTFT性能影响的模型具有重要意义,但这至今尚未见报道。为此本文通过引进一个关键参数Rc/Rch0 （接触电阻/通态电阻）,并以模拟方法分析它与各性能参数变化率关系,从而使上述模型得到部分实现。研究中首先拓展了OTFT的Brown模型公式,接着分析了接触电阻导致的各性能参数（迁移率μ,饱和电压 VDsat等）误差变化情况。接着根据所得到结果,对关键参数Rc/Rch0重点进行了分析和论证,获得一个非常有意义的结果,在此基础上,一种估算OTFT内在接触电阻,进而修正因接触电阻导致的各性能参数误差值的方法被首次提出。实验证明该方法具有合理性。     

Thermal annealing effect on electrical properties of metal nitride gate electrodes with hafnium oxide gate dielectrics in nano-metric MOS devices

Electrical properties of hafnium oxide (HfO₂) gate dielectric with various metal nitride gate electrodes, i.e., tantalum nitride (TaN), molybdenum nitride (MoN), and tungsten nitride (WN), were studied over a range of HfO₂ thicknesses, e.g., 2.5-10 nm, and post-metal annealing (PMA) temperatures, e.g., 600 °C to 800 °C. The work function of the nitride gate electrode was dependent on the material and the post-metal annealing (PMA) temperature. The scanning transmission electron microscopy technique is used to observe the effect of PMA on the interfacial gate dielectric thickness. After high-temperature annealing, the metal nitride gates were suitable for NMOS. At the same PMA temperature, the oxide-trapped charges increased and the interface state densities decreased with the increase of the HfO₂ thickness for TaN and WN gate electrodes. However, for MoN gate electrode the interface state density is almost independent of film thickness. Therefore, dielectric properties of the HfO₂ high-k film depend not only on the metal nitride gate electrode material but also the post-metal annealing condition as well as the film thickness. During constant voltage stress of the MOS capacitors, an increase in the time-dependent gate leakage current is also observed.