DSOI-a novel structure enabling adjust circuit dynamically

A double silicon on insulator (DSOI) structure was introduced based on fully depleted SOI (FDSOI) technology. The circuit performance could be adjusted dynamically through the separate back gate electrodes applied to N-channel and P-channel devices. Based on DSOI ring oscillator (OSC), this paper focused on the theoretical analysis and electrical test of how the OSC''s frequency being influenced by the back gate electrodes (soi2n, soi2p). The testing results showed that the frequency and power consumption of OSC could change nearly linearly along with the back gate bias. According to the different requirements of the circuit designers, the circuit performance could be improved by positive soi2n and negative soi2p, and the power consumption could be reduced by negative soi2n and positive soi2p. The best compromise between performance and power consumption of the circuit could be achieved by appropriate back gate biasing.     

Analytical modelling of threshold voltage for underlap Fully Depleted Silicon-On-Insulator MOSFET

In this article, surface-potential-based analytical threshold voltage model for underlap Fully Depleted Silicon-On-Insulator MOSFET (underlap-SOI) is developed by solving two-dimensional Poisson equation. The gate underlap at source/drain (S/D) has different boundary conditions as compared to channel region under the gate dielectric that divide the whole channel into three regions. It leads us to derive the new surface potential model for three different channel regions, i.e. the region under the gate dielectric and two gate underlap regions at S/D. The effects of underlap length, channel length, body thickness, channel doping concentration, metal gate work function and gate dielectric constant on threshold voltage have been included in our model. The threshold voltage dependence on different device parameters has been studied using analytical model and simulations. The closeness between the simulation results and model results show that the analytical model accurately calculate the threshold voltage values for large range of device parameters.     

SOI和体硅MOSFET大信号非准静态效应比较研究

研究了全耗尽SOI、部分耗尽SOI和体硅NMOS器件中源、漏、栅和衬底电流的非准静态现象。研究表明,在相同的结构参数下,体硅器件的非准静态效应最强,PDSOI次之,FDSOI最弱。指出了沟道源、漏端反型时间和反型程度的不同是造成非准静态效应的内在原因。最后提出临界升压时间的概念,以此对非准静态效应进行定量表征,深入研究器件结构参数对非准静态效应的影响规律。结果显示,通过缩短沟道长度、降低沟道掺杂浓度、减小硅膜厚度和栅氧厚度、提高埋氧层厚度等手段,可以弱化SOI射频MOS器件中的非准静态效应。     

W/TiN Gate Thin-Film Fully-Depleted SOI CMOS Devices

TiN gate thin-film fully-depleted SOI CMOS devices are fabricated and discussed.Key process technologies are demonstrated.Compared with the dual polysilicon gate devices,the channel doping concentration of nMOS and pMOS can be reduced without changing threshold voltage (VT)，which enhances the mobility.Symmetrical VT is achieved by nearly the same VT implant dose because of the near mid-gap workfunction of TiN gate.The SCE effect is improved when the thin-film thickness is reduced.     

Elevated Source/Drain Engineering by Novel Technology for Fully Depleted SOI CMOS Devices and Circuits

0.35μm thin-film fully-depleted SOI CMOS devices with elevated source/drain structure are fabricated by a novel technology.Key process technologies are demonstrated.The devices have quasi-ideal subthreshold properties;the subthreshold slope of nMOSFETs is 65mV/decade,while that of pMOSFETs is 69mV/decade.The saturation current of 1.2μm nMOSFETs is increased by 32% with elevated source/drain structure,and that of 1.2μm pMOSFETs is increased by 24%.The per stage propagation delay of 101-stage fully-depleted SOI CMOS ring oscillator is 75ps with 3V supply voltage.     

TiN栅及抬高源漏的薄膜全耗尽SOI CMOS器件的模拟研究

对0．25μm TiN栅及抬高源漏的薄膜全耗尽SOI CMOS器件进行了模拟研究。由于TiN栅具有中间禁带功函数，在低的工作电压下，NMOS和PMOS的阈值电压都得到了优化。随硅膜厚度的减小，釆用源漏抬高结构，减小了源漏串联电阻。采用抬高源漏结构的NMOS和PMOS，其饱和电流分别提高了36％和41％。由于采用源漏抬高能进一步降低硅膜厚度，短沟道效应也得到了抑制．     

关于超薄埋氧层及超薄SOI的MOSFET器件衬底掺杂的设计研究

The importance of substrate doping engineering for extremely thin SOI MOSFETs with ultra-thin buried oxide(ES-UB-MOSFETs) is demonstrated by simulation.A new substrate/backgate doping engineering,lateral non-uniform dopant distributions(LNDD) is investigated in ES-UB-MOSFETs.The effects of LNDD on device performance,V t-roll-off,channel mobility and random dopant fluctuation(RDF) are studied and optimized.Fixing the long channel threshold voltage(V t) at 0.3 V,ES-UB-MOSFETs with lateral uniform doping in the substrate and forward back bias can scale only to 35 nm,meanwhile LNDD enables ES-UB-MOSFETs to scale to a 20 nm gate length,which is 43% smaller.The LNDD degradation is 10% of the carrier mobility both for n MOS and p MOS,but it is canceled out by a good short channel effect controlled by the LNDD.Fixing V t at 0.3 V,in long channel devices,due to more channel doping concentration for the LNDD technique,the RDF in LNDD controlled ES-UB-MOSFETs is worse than in back-bias controlled ES-UB-MOSFETs,but in the short channel,the RDF for LNDD controlled ES-UB-MOSFET is better due to its self-adaption of substrate doping engineering by using a fixed thickness inner-spacer.A novel process flow to form LNDD is proposed and simulated.     

采用新的抬高源漏工艺技术制作的全耗尽SOI CMOS器件和电路

采用新的工艺技术,成功研制了具有抬高源漏结构的薄膜全耗尽SOI CMOS器件.详细阐述了其中的关键工艺技术.器件具有接近理想的亚阈值特性,nMOSFETs和pMOSFETs的亚阈值斜率分别为65和69mV/dec.采用抬高源漏结构的1.2μm nMOSFETs的饱和电流提高了32%,pMOSFETs的饱和电流提高了24%.在3V工作电压下101级环形振荡器电路的单级门延迟为75ps.     

Simulation of a Double-Gate Dynamic Threshold Voltage Fully Depleted Silicon-on-Insulator nMOSFET

提出了新型全耗尽SOI平面双栅动态阈值nMOS场效应晶体管,模拟并讨论了器件结构、相应的工艺技术和工作机理.对于nMOS器件,背栅n阱是通过剂量为3×1013cm-2,能量为250keV的磷离子注入实现的,并与n 前栅多晶硅直接相连.这项技术与体硅工艺完全兼容.通过Tsuprem4和Medici模拟,发现全耗尽SOI平面双栅动态阈值nMOSFET保持了传统全耗尽SOI nMOSFET的优势,消除了反常亚阈值斜率和kink效应,同时较传统全耗尽SOI nMOSFET有更加优秀的电流驱动能力和跨导特性.     

Thermal aware design and comparative analysis of a high performance 64-bit adder in FD-SOI and bulk CMOS technologies

Thermal behaviours of high-performance digital circuits in bulk CMOS and FDSOI technologies are compared on a 64-bit Kogge-Stone adder designed in 40 nm node. Temperature profiles of the adder in bulk and FDSOI are extracted with thermal simulations and hotspot locations are studied. The influence of local power density on peak temperature is examined. It is shown that high power density devices have significant influence on peak temperature in FDSOI. It is found that some group of devices that perform the same function are the most prominent heat generators. A modification on the design of these devices is proposed which decreases the hotspot temperatures significantly.