Parasitic effects of air-gap through-silicon vias in high-speed three-dimensional integrated circuits

In this paper,ground-signal-ground type through-silicon vias(TSVs) exploiting air gaps as insulation layers are designed,analyzed and simulated for applications in millimeter wave.The compact wideband equivalent-circuit model and passive elements(RLGC) parameters based on the physical parameters are presented with the frequency up to 100 GHz.The parasitic capacitance of TSVs can be approximated as the dielectric capacitance of air gaps when the thickness of air gaps is greater than 0.75 μm.Therefore,the applied voltage of TSVs only needs to achieve the flatband voltage,and there is no need to indicate the threshold voltage.This is due to the small permittivity of air gaps.The proposed model shows good agreement with the simulation results of ADS and Ansoft's HFSS over a wide frequency range.     

Through-silicon-via crosstalk model and optimization design for three-dimensional integrated circuits

Through-silicon-via （TSV） to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits （3D ICs）. Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 rnV and 379 mV reductions in the peak noise voltage, respectively.     

Electronic Transport Properties of （7,0） Semiconducting Carbon Nanotube

Electronic transport properties of a finite （7,0） carbon nanotube （CNT） coupled to Au （111） surfaces are investigated with a fully nonequilibrium Green＇s functions method combined with the density functional theory. The results show that the coupling effect between the CNT and Au electrode plays an important role in the transport properties, which leads to the formation of a high plateau in the transmission spectrum around Fermi energy. In addition, the current-voltage characteristic of the （7,0） CNT coupled to Au electrodes is different from an isolated （7,0） CNT.     

新型NO2化学传感器:碳化硅纳米管

气体吸附对碳化硅纳米管的电子结构的影响是理解碳化硅纳米管气敏传感器工作机理的基础.基于密度泛函理论,利用CASTEP软件包计算NO₂气体吸附前后的碳化硅纳米管的结构及其电子结构.结果表明,NO₂气体与碳化硅纳米管间形成了稳定的吸附,并明显的增强了碳化硅纳米管的导电特性.碳化硅纳米管是制备气体传感器的理想材料之一,为开发应用于NO₂气体检测的碳化硅纳米管提供必要的理论支持.     

Reduction of signal reflection along through silicon via channel in high-speed three-dimensional integration circuit

The through silicon via （TSV） technology has proven to be the critical enabler to realize a three-dimensional （3D） gigscale system with higher performance but shorter interconnect length. However, the received digital signal after trans- mission through a TSV channel, composed of redistribution layers （RDLs）, TSVs, and bumps, is degraded at a high data-rate due to the non-idealities of the channel. We propose the Chebyshev multisection transformers to reduce the signal reflec- tion of TSV channel when operating frequency goes up to 20 GHz, by which signal reflection coefficient （$11） and signal transmission coefficient （$21） are improved remarkably by 150% and 73.3%, respectively. Both the time delay and power dissipation are also reduced by 4% and 13.3%, respectively. The resistance-inductance-conductance-capacitance （RLGC） elements of the TSV channel are iterated from scattering （S）-parameters, and the proposed method of weakening the signal reflection is verified using high frequency simulator structure （HFSS） simulation software by Ansoft.     

Closed-form internal impedance model and characterization of mixed carbon nanotube bundles for three-dimensional integrated circuits

Based on the complex effective conductivity method, a closed-form expression for the internal impedance of mixed carbon nanotube(CNT) bundles, in which the number of CNTs for a given diameter follows a Gaussian distribution, is proposed in this paper. It can appropriately capture the skin effect as well as the temperature effect of mixed CNT bundles.The results of the closed-form expression and the numerical calculation are compared with various mean diameters, standard deviations, and temperatures. It is shown that the proposed model has very high accuracy in the whole frequency range considered, with maximum errors of 1% and 2.3% for the resistance and the internal inductance, respectively. Moreover,by using the proposed model, the high-frequency electrical characteristics of mixed CNT bundles are deeply analyzed to provide helpful design guidelines for their application in future high-performance three-dimensional integrated circuits.     

p型K:ZnO导电机理的第一性原理研究

基于密度泛函理论,利用局域密度近似的第一性原理平面波赝势方法,对掺K以及含有氢填隙(H_i)、氧空位(V_O)、锌填隙(Zn_i)和锌空位(V_Zn)的K:ZnO电子结构分别进行了研究.结果表明,1) 单独掺K可引入浅受主,但系统总能增高;2) K与H共掺可降低系统总能,提升稳定性;3) V_O在K+H:ZnO中的形成比Zn_i困难得多,二者都是 关键词： 氧化锌 p型 第一性原理 电子结构