Elasticity study of very thin Cu films
Elasticity study of very thin Cu films
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DOI：
10.1016/j.msea.2006.01.138
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发表时间：
2006-12-20
期刊：
影响因子：
6.4
通讯作者：
Mizubayashi, H.
中科院分区：
文献类型：
--
作者：
Fujiwara, K.;Tanimoto, H.;Mizubayashi, H.
研究了Cu膜厚度t（Cu）在7 ~ 1000nm范围内溅射沉积Cu/Ta膜和Ta/Cu/Ta膜的弹性性能和表面形貌。在200K以上，通常观察到组成Cu膜的内摩擦Q(f)（-1）单调增加。对于Cu/Ta薄膜，Cu薄膜的杨氏模量E-f与t(Cu) >近似于80 nm的理论值吻合较好，在t(Cu) >近似于80 nm以下随t（Cu）减小而减小。400 K退火后Q(f)（-1）减小，δ Q(f,400k)（-1）和表面粗糙度分别在80 nm附近出现局部最小值和局部最大值，表明后续Cu层的沉积（自封盖效应）改变了Cu膜的性能。对于Ta/Cu/Ta薄膜，Ta封顶导致平行于薄膜表面的晶粒尺寸增大，内应力减小，Ef减小，而垂直于薄膜表面的晶粒尺寸、Q(f)（-1）、δ Q(f,400k)（-1）和表面粗糙度对t（Cu）的依赖性没有变化。这些结果在纳米级Cu薄膜的晶界和界面的弹性响应方面进行了讨论，这可能对电子器件的小型化具有重要意义。(c) 2006 Elsevier B.V.版权所有
The elastic properties and the surface morphology of Cu/Ta films and Ta/Cu/Ta films sputter-deposited on Si reed substrates were studied for the Cu film thickness, t(Cu), between 7 and 1000nm. A monotonic increase in the internal friction, Q(f)(-1), in the constituent Cu film above 200K was commonly observed. For Cu/Ta films, Young's modulus of a Cu film, E-f, showed good agreement with the theoretical value for t(Cu) >similar to 80 nm and a decrease with decreasing t(Cu) below similar to 80 nm. A decrease in Q(f)(-1) after 400 K annealing, Delta Q(f,400k)(-1) and the surface roughness showed a local minimum and a local maximum near 80 nm, respectively, indicating that the properties of the Cu film were modified by subsequent deposition of a Cu layer (the self capping effect). For Ta/Cu/Ta films, Ta capping brought about an increase in the grain size parallel to the film surface, a decrease in the internal stress and a decrease in Ef but no changes in the grain size normal to the film surface, Q(f)(-1), Delta Q(f,400k)(-1) and the t(Cu)-dependence of the surface roughness. These results are discussed in the light of the anclastic responses of grain boundaries and interface in nano-scale Cu films which may be important for down-sizing of electric devices. (c) 2006 Elsevier B.V. All rights reserved.