A first-principles analysis of ballistic conductance, grain boundary scattering and vertical resistance in aluminum interconnects
A first-principles analysis of ballistic conductance, grain boundary scattering and vertical resistance in aluminum interconnects
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DOI：
10.1063/1.5027084
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发表时间：
2018-05
期刊：
影响因子：
1.6
通讯作者：
Tianji Zhou;N. Lanzillo;Bhosale Prasad;D. Gall;R. Quon
中科院分区：
文献类型：
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作者：
Tianji Zhou;N. Lanzillo;Bhosale Prasad;D. Gall;R. Quon
我们从后端 (BEOL) 的角度对铝互连中的电子散射机制进行了从头开始的评估。我们将弹道电导视为纳米线尺寸的函数，以及表面氧化对电子传输的影响。我们还考虑了几种代表性的孪晶界，并计算了每种情况的电阻率和反射系数。最后，我们计算了 Al/Ta(N)/Al 和 Cu/Ta(N)/Cu 界面上的垂直电阻，它们是具有扩散势垒的典型垂直互连结构的代表。尽管具有高弹道电导，但计算得出的 Al 晶界电阻率比 Cu 高 70-100%，并且 Al 跨 Ta(N) 扩散势垒的垂直电阻比 Cu 高 60-100%。这些结果表明，除了铝互连中众所周知的电迁移限制之外，电子散射也是在精细尺寸下实现低互连线电阻的一个主要问题。我们从后端（BEOL）的角度对铝互连中的电子散射机制进行了从头算评估。我们将弹道电导视为纳米线尺寸的函数，以及表面氧化对电子传输的影响。我们还考虑了几种代表性的孪晶界，并计算了每种情况的电阻率和反射系数。最后，我们计算了 Al/Ta(N)/Al 和 Cu/Ta(N)/Cu 界面上的垂直电阻，它们是具有扩散势垒的典型垂直互连结构的代表。尽管具有高弹道电导，但计算得出的 Al 晶界电阻率比 Cu 高 70-100%，并且 Al 跨 Ta(N) 扩散势垒的垂直电阻比 Cu 高 60-100%。这些结果表明，除了铝互连中众所周知的电迁移限制之外，电子散射也是实现低互连 l 的一个主要问题。
We present an ab initio evaluation of electron scattering mechanisms in Al interconnects from a back-end-of-line (BEOL) perspective. We consider the ballistic conductance as a function of nanowire size, as well as the impact of surface oxidation on electron transport. We also consider several representative twin grain boundaries and calculate the specific resistivity and reflection coefficients for each case. Lastly, we calculate the vertical resistance across the Al/Ta(N)/Al and Cu/Ta(N)/Cu interfaces, which are representative of typical vertical interconnect structures with diffusion barriers. Despite a high ballistic conductance, the calculated specific resistivities at grain boundaries are 70-100% higher in Al than in Cu, and the vertical resistance across Ta(N) diffusion barriers are 60-100% larger for Al than for Cu. These results suggest that in addition to the well-known electromigration limitations in Al interconnects, electron scattering represents a major problem in achieving low interconnect line resistance at fine dimensions.We present an ab initio evaluation of electron scattering mechanisms in Al interconnects from a back-end-of-line (BEOL) perspective. We consider the ballistic conductance as a function of nanowire size, as well as the impact of surface oxidation on electron transport. We also consider several representative twin grain boundaries and calculate the specific resistivity and reflection coefficients for each case. Lastly, we calculate the vertical resistance across the Al/Ta(N)/Al and Cu/Ta(N)/Cu interfaces, which are representative of typical vertical interconnect structures with diffusion barriers. Despite a high ballistic conductance, the calculated specific resistivities at grain boundaries are 70-100% higher in Al than in Cu, and the vertical resistance across Ta(N) diffusion barriers are 60-100% larger for Al than for Cu. These results suggest that in addition to the well-known electromigration limitations in Al interconnects, electron scattering represents a major problem in achieving low interconnect l...