Epitaxial metals for interconnects beyond Cu
Epitaxial metals for interconnects beyond Cu
复制标题
用于Cu以外互连的外延金属
DOI：
10.1116/6.0000018
复制
发表时间：
2020-05-01
影响因子：
2.9
通讯作者：
Coffey, Kevin R.
中科院分区：
文献类型：
--
作者：
Barmak, Katayun;Ezzat, Sameer;Coffey, Kevin R.
使用福克 - 桑德海默半经典模型对在c面蓝宝石衬底上生长的Co(0001)和Ru(0001)单晶薄膜的实验测量电阻率随厚度的变化进行建模。模型拟合表明，在大约20nm的厚度时，Ru的电阻率将低于Co的电阻率。对于厚度大于20nm的Ru薄膜，透射电子显微镜显示出穿晶位错和失配位错、层错以及变形孪晶。Co薄膜暴露在环境空气中以及在Ru上沉积SiO₂、MgO、Al₂O₃和Cr₂O₃氧化物层会降低金属层的表面镜面反射率。然而，对于Ru薄膜，在还原气氛中退火可恢复表面镜面反射率。以在外延沉积的Ru层上外延电化学沉积Co为例，证明了为后端制程结构生成外延互连的可行性。描述了一种基于紧束缚方法的电子传输模型，并以Ru互连为例。该模型能够计算由大量原子（10⁵ - 10⁶）组成的结构的电导率，与系统尺寸呈线性比例关系，并且还可以包含缺陷。
Experimentally measured resistivity of Co(0001) and Ru(0001) single crystal thin films, grown on c-plane sapphire substrates, as a function of thickness is modeled using the semiclassical model of Fuchs-Sondheimer. The model fits show that the resistivity of Ru would cross below that for Co at a thickness of approximately 20nm. For Ru films with thicknesses above 20nm, transmission electron microscopy evidences threading and misfit dislocations, stacking faults, and deformation twins. Exposure of Co films to ambient air and the deposition of oxide layers of SiO2, MgO, Al2O3, and Cr2O3 on Ru degrade the surface specularity of the metallic layer. However, for the Ru films, annealing in a reducing ambient restores the surface specularity. Epitaxial electrochemical deposition of Co on epitaxially deposited Ru layers is used as an example to demonstrate the feasibility of generating epitaxial interconnects for back-end-of-line structures. An electron transport model based on a tight-binding approach is described, with Ru interconnects used as an example. The model allows conductivity to be computed for structures comprising large ensembles of atoms (10(5)-10(6)), scales linearly with system size, and can also incorporate defects.