TiN/Si_3N_4纳米多层膜的生长结构与超硬效应

Super-Hardness and Microstructures of TiN/Si_3N_4 Nano-Multilayers

采用磁控溅射方法制备了一系列不同Si3N4和TiN层厚的TiN/Si3N4纳米多层膜,采用X射线衍射、高分辨电子显微分析和微力学探针表征了薄膜的微结构和力学性能,研究了Si3N4和TiN层厚对多层膜生长结构和力学性能的影响。结果表明:当Si3N4层厚小于0.7 nm时,原为非晶的Si3N4在TiN的模板作用下晶化并与之形成共格外延生长的柱状晶,使TiN/Si3N4多层膜产生硬度和弹性模量异常升高的超硬效应。最高硬度和弹性模量分别为34.0 GPa和353.5 GPa。当其厚度大于1.3 nm时,Si3N4呈现非晶态,阻断了TiN的外延生长,多层膜的力学性能明显降低。此外,TiN层厚的增加也会对TiN/Si3N4多层膜的生长结构和力学性能造成影响,随着TiN层厚的增加,多层膜的硬度和弹性模量缓慢下降。

Nano TiN and Si3N4 layers with different thickness were alternatively deposited on Si substrates by magnetron sputtering. The TiN/Si3N4 nano-multilayers were characterized with X-ray diffraction （XRD）, high resolution transmission electron microscopy （HRTEM）, and nano-indentation.The results show that the layer thickness of Si3N4 and TiN significantly affects the microstructures and mechanical properties of the multilayer. For example, when Si3N4 layer thickness is less than 0. 7 nm, TiN layer induces an epitaxial growth and re-crystallization of amorphous Si3N4,which results in considerable increases of the hardness and elastic modulus of the multi-layer, whose maximum values can reach 34.0 and 353.5 GPa, respectively. When Si3N4 layer is thicker than 1.3 nm, only amorphous Si3N4 was observed on top of the TiN layer and the mechanical properties of the mulfilayer markedly deteriofiates. As the TiN layer thickness increases, the hardness and elastic modulus of the multilayer slowly decreases.