【作者】 苏晋荣；

【导师】 张文梅；

【作者基本信息】 山西大学 ， 无线电物理， 2017， 博士

【摘要】 在近半个世纪间,半导体技术一直遵循摩尔定律向更小尺寸,更低能耗,更高性能发展。然而,当工艺尺寸进一步缩小至深亚微米级时,互连线带来的能耗、散热、延迟等问题越来越凸显,成为制约摩尔定律进一步延续的瓶颈。为此,人们提出多种技术方案,而三维集成电路(Three-Dimensional Integrated Circuit,3D IC)便是其中最有潜力的方案之一,其核心技术在于堆叠芯片间的垂直互连,即硅通孔(Through-Silicon-Via,TSV)技术。本文针对几种TSV结构的电模型以及传输特性展开研究,主要内容和创新点如下:第二章提出圆台形TSV的氧化层电容及一对TSV间衬底电容的解析表达式,并研究了圆台形TSV的传输特性。首先,通过求解麦克斯韦方程,提取出圆台形TSV的寄生电容表达式,利用电磁仿真软件CST EMS验证了表达式的精确性。结果表明,两电容表达式最大误差分别为1.86%和3.75%。然后,利用所提的电容公式,建立了一对圆台形TSV的等效电路模型,计算了其S参数、串扰和延迟,发现圆台形TSV比圆柱形TSV串扰更小,但延迟稍长。最后,分析了两种圆台形TSV阵列的串扰。第三章提出一种新的抑制TSV引起的衬底噪声的结构——部分同轴TSV。该结构在金属过孔外包围一层苯并环丁烯(Benzocyclobutene,BCB)材料,并在其一端BCB层之外增加接地金属环,整体可看做同轴TSV的外屏蔽层缩减为一个接地金属环,比同轴TSV更易加工。该结构中BCB层可以有效减少通孔中信号向衬底的泄露,接地金属环能为衬底噪声提供一条低阻抗路径。频域分析结果表明,与传统TSV、有p+层的TSV以及带有p+保护环的TSV结构相比,该结构具有更大的正向传输系数和更小的近端串扰。此外,时域分析发现,该结构的衬底噪声峰值电压与上述有p+层的TSV以及带有p+保护环的TSV相比有明显减小。第四章以多壁碳纳米管束(Multi-walled Carbon Nanotubes Bundle,MWCNTB)为导体材料形成屏蔽型硅通孔结构,建立了其等效电路模型。利用该模型计算了其正向传输系数S21、衰减常数及时间延迟,结果表明,该TSV比以铜为导体的同轴TSV具有更大的传输系数和更小的衰减及延迟。此外,对MWCNTB等效电导率表达式进行简化,并利用该表达式定义了电导率敏感系数,分析得知,MWCNTB的电导率对其表层直径最敏感;探讨了MWCNTB电导率与其填充密度之间的关系,给出了在保证MWCNTB电导率优于铜的前提下,MWCNT的几何尺寸选择准则。最后,系统的分析了量子电容对屏蔽型TSV的传输性能影响。结果表明,中间介质层为BCB时,量子电容的引入能明显提升MWCNTB填充的屏蔽型TSV的高频段传输性能;当介质层为硅时,量子电容的温度效应可以与硅的温度效应相抵消一部分,有利于提高系统的热稳定性。第五章建立了填充MWCNTB的TSV(MWCNTB-TSV)的电模型。该模型综合考虑了MWCNT的导电通道数、TSV电容及衬底电导的温度效应。利用该模型,计算了一对MWCNTB-TSV的正向传输系数、串扰和传播常数。通过分析相移常数,给出了晶圆级、芯片级和转接板级应用中,不同温度下能实现零色散传输的MWCNTB-TSV衬底及节距的选择准则。此外,利用MWCNTB等效电导率紧凑表达式,导出了满足MWCNTB-TSV的衰减小于Cu-TSV的衰减的MWCNT表层直径最小值表达式。更多还原

【Abstract】 In the past fifty years,semiconductor technology has been continusly developed in the way of smaller size,lower consumption and higher performance driven by Moore’s law.However,as feature size shrinks to deep submicron,the problems induced by interconnect,such as,power consumption,heat dissipation and delay are becoming increasingly prominent.Then,interconnect technology has become a bottleneck restricting the further continuation of Moore’s law.Therefore,many methods are proposed to solve this problem.Among them three-dimensional integrated circuit(3D IC)is widely regarded as the most potential one.Through-silicon-via is the core technology of 3D IC that provides vertical interconnection between the stacked chips.In this dissertation,the electrical model and transmission performance of several novel TSV structures are studied in detail,and the main academic contribution is summarized as follows.In chapter 2,Closed-form expressions of the parasitic insulator capacitance and the substrate capacitance for tapered through-silicon vias(T-TSVs)are proposed.First,the expressions are deduced by solving Maxwell equations.The maximum percentage errors between the calculated and simulated results for the insulator capacitance and the substrate capacitance are 1.86% and 3.75%,respectively.Then,based on the expressions,the equivalent circuit model of a T-TSV signal-ground(S-G)pair is established.Furthermore,the electrical characteristics of the T-TSV are evaluated using the model.The results indicate that the T-TSV has longer latency and less crosstalk than the cylindrical TSVs.Finally,the crosstalk of two types of T-TSV arrays is analyzed and the applicability of the two expressions is discussed.Then,based on the expressions,the equivalent circuit model of a T-TSV signal–ground(S-G)pair is establishedIn chapter 3,a novel TSV,named partial coaxial TSV,is proposed to suppress the substrate noise induced by TSV.In this structure,the via is surrounded by a BCB layer,and a grounded metal ring is placed at one end outside the BCB layer.It can be seemed as partial shielded coaxial TSV and it is easier to process than coaxial TSV.The BCB layer can effectively reduce the leakage of the signal to the substrate,and the metal ring provides a low impedance path for the substrate noise.Frequency domain analysis results indicate that this structure has larger |S21| and less near-end crosstalk compared with the traditional TSV,TSV with p+ layer and TSV with p+ guard ring.Additionally,time domain analysis results show that the substrate peak noise voltage of this structure is obviously reduced compared with the two methods above.In chapter 4,the multi-walled carbon nanotube bundle(MWCNTB)filled shielded through-silicon via(S-TSV)is proposed and its equivalent circuit model is established.Then,the electrical characteristics including the S parameters,attenuation constant and time delay are investigated using the model.The results indicate that the MS-TSV(MWCNTB filled S-TSV)has a larger |S21|,smaller attenuation and shorter time delay compared with the copper filled S-TSV(CuS-TSV).In addition,the expression for the equivalent conductivity of MWCNTB(σMWCNTB)is simplified,and the sensitivity coefficient of σMWCNTB is defined.The analysis shows that the outermost shell of MWCNT has the most significant impact on σMWCNTB.Also,the minimum packing density of MWCNTB satisfying σMWCNTB ≥ σCu has been deduced,and guidelines for the geometrical parameters of MS-TSV that satisfy σMWCNTB ≥ σCu are obtained.Finally,the impact of quantum capacitance(Cq)of CNT on the transmission performance of S-TSVs is analyzed.The results show that the transmission performance of S-TSV filled with BCB insulation layer and MWCNT bundle above 20 GHz can be significantly improved by Cq.In addition,the performance of S-TSVs with silicon insulation layer can also be dramatically improved by Cq.Besides,the temperature effect of silicon can be balanced by Cq such that the heat stability of S-TSV with silicon insulation layer is improved.In chapter 5,the electrical model of MWCNT-based through-silicon vias(MWCNT-TSVs)is established considering the temperature effects of the mean free path,metal-oxide-semiconductor(MOS)capacitance,substrate conductance and number of conducting channels of multi-walled carbon nanotube(MWCNT).Then,Based on this model,the propagation constant,forward transmission coefficient S21 and crosstalk at different temperatures are calculated.By analyzing the phase constant,the zero dispersion transmission(ZDT)condition is obtained.According to this condition,the guidelines on how to select the substrate in different level integrations are proposed.Furthermore,a concise formula for the equivalent conductivity of MWCNT is proposed.Also,the expression of the minimum diameter of MWCNT-TSV whose attenuation is less than that of copper-filled TSV has been deduced.更多还原