Steady-state tensile stresses during the growth of polycrystalline films
Steady-state tensile stresses during the growth of polycrystalline films
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DOI：
10.1016/j.actamat.2007.05.008
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发表时间：
2007-09
期刊：
影响因子：
9.4
通讯作者：
B. Sheldon;A. Bhandari;A. Bower;S. Raghavan;X. Weng;J. Redwing
中科院分区：
文献类型：
--
作者：
B. Sheldon;A. Bhandari;A. Bower;S. Raghavan;X. Weng;J. Redwing
拉伸应力，在多晶薄膜的生长过程中出现的描述使用内聚区的方法，沿着与有限元模型，占不同的二面角在晶界与生长表面的交叉点。这种组合的方法预测的最大拉伸应力作为晶粒尺寸和晶界/表面能的函数。这些关系不同于以前提出的。该模型还表明，晶粒边界尖点可以有显着的影响的拉伸生长应力的大小，与尖锐的晶粒边界尖点导致较低的稳态拉伸应力在膜中。从几种材料与大的拉伸增长应力的数据是在合理的协议与模型。特别是，通过金属有机化学气相沉积生长的AlN膜表现出的拉伸应力是在或接近最大预测的拉伸值。从这些氮化物薄膜的实验结果也与其他两个模型的预测在拉伸极限的增长是一致的：应力是（i）独立的生长速率和（ii）在（或接近）的断裂极限。
Tensile stresses that arise during the growth of polycrystalline films are described using a cohesive zone approach, along with a finite element model that accounts for different dihedral angles at grain boundary intersections with the growth surface. This combined approach predicts the maximum tensile stress as a function of the grain size and the grain boundary/surface energies. These relationships differ from those proposed previously. The model also indicates that grain boundary cusps can have a significant effect on the magnitude of tensile growth stresses, with sharper grain boundary cusps leading to lower steady-state tensile stresses in the film. Data from several materials with large tensile growth stresses are in reasonable agreement with the model. In particular, AlN films grown by metal organic chemical vapor deposition exhibit tensile stresses that are at or near the maximum predicted tensile values. The experimental results from these nitride films are also consistent with two other model predictions for growth at the tensile limit: the stresses are (i) independent of the growth rate and (ii) at (or close to) the fracture limit.