论文标题

FCC Ruthenium用于高级互连的第一原理评估

First principles evaluation of fcc ruthenium for use in advanced interconnects

论文作者

Philip, Timothy M., Lanzillo, Nicholas A., Gunst, Tue, Markussen, Troels, Cobb, Jonathan, Aboud, Shela, Robison, Robert R.

论文摘要

随着半导体行业转向替代导体来代替CU来替代将来的互连节点,因此非常关注的重点是评估RU的电性能。已经对典型的六边形封闭式(HCP)相进行了广泛的研究,但是对以面部为中心的立方(FCC)相的关注相对较少,这已显示出在密封结构中的成核,并且可能存在于紧密的互连中。使用\ emph {ab initio}技术,我们基于FCC RU的性能进行基准测试。我们发现,FCC RU的声子限制的散装电阻率不到HCP RU的一半,这一特征我们追溯到了更强的电子 - 光子偶联元素,这些耦合元素是从Fermi Fermi表面形状的几何遗传的FCC晶体。尽管FCC相的好处,但与基于CU的平均晶粒尺寸相似的基于CU的互连相比,高晶界散射会增加电阻率。但是,我们发现,由于导体体积因粘附和润湿衬里而丢失,FCC RU的线电阻低于21 nm线宽度的CU。除了研究散装运输特性外,我们还评估了FCC RU的粘附衬里的性能。我们发现,FCC RU直接与二氧化硅结合的能量在能量上比通过常规粘附衬里(如Tan和Tin)更有利。在RU沉积技术需要薄的衬里的情况下,我们发现FCC RU的衬里的垂直电阻损失可能比用于CU互连的常规衬里计算的近八倍。因此,我们的计算表明,RU的FCC相的形成可能对先进的低电阻互连是有益的。

As the semiconductor industry turns to alternate conductors to replace Cu for future interconnect nodes, much attention as been focused on evaluating the electrical performance of Ru. The typical hexagonal close-packed (hcp) phase has been extensively studied, but relatively little attention has been paid to the face-centered cubic (fcc) phase, which has been shown to nucleate in confined structures and may be present in tight-pitch interconnects. Using \emph{ab initio} techniques, we benchmark the performance of fcc Ru. We find that the phonon-limited bulk resistivity of the fcc Ru is less than half of that of hcp Ru, a feature we trace back to the stronger electron-phonon coupling elements that are geometrically inherited from the modified Fermi surface shape of the fcc crystal. Despite this benefit of the fcc phase, high grain boundary scattering results in increased resistivity compared to Cu-based interconnects with similar average grain size. We find, however, that the line resistance of fcc Ru is lower than that of Cu below 21 nm line width due to the conductor volume lost to adhesion and wetting liners. In addition to studying bulk transport properties, we evaluate the performance of adhesion liners for fcc Ru. We find that it is energetically more favorable for fcc Ru to bind directly to silicon dioxide than through conventional adhesion liners such as TaN and TiN. In the case that a thin liner is necessary for the Ru deposition technique, we find that the vertical resistance penalty of a liner for fcc Ru can be up to eight times lower than that calculated for conventional liners used for Cu interconnects. Our calculations, therefore, suggest that the formation of the fcc phase of Ru may be a beneficial for advanced, low-resistance interconnects.

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