AlN/Si3N4纳米多层膜的外延生长与力学性能

采用射频磁控溅射方法制备单层AlN, Si₃N₄薄膜和不同调制周期的AlN/Si₃N₄纳米多层膜.采用X射线衍射仪、高分辨透射电子显微镜和纳米压痕仪对薄膜进行表征.结果发现，多层膜中Si₃N₄层的晶体结构和多层膜的硬度依赖于Si₃N₄层的厚度.当AlN层厚度为4.0nm、 Si₃N₄层厚度 关键词： 3N₄纳米多层膜')" href="#">AlN/Si₃N₄纳米多层膜 外延生长 应力场 超硬效应

Epitaxial growth and mechanical properties of AlN/Si3N4 nanostructured multilayers

Monolithic AlN，Si₃N₄ films and AlN/Si₃N₄ multilayers with different modulation periods were prepared by reactively magnetic sputtering. The films were characterized by X-ray diffraction, high-resolution transmission electron microscopy and nanoindentation. The results showed that the crystal structure of Si₃N₄ layers in the multilayers and the hardness of AlN/Si₃N₄ multilayers depend on the thickness of Si₃N₄ layer. When the thickness of AlN is 4.0nm and that of Si₃N₄ layer is 0.4nm, Si₃N₄ layers grew epitaxially with AlN and form strong columnar crystals which extend over several modulation periods. A large degree of hardness enhancement of the multilayer was produced. The microstructure of Si₃N₄ changes from crystalline to amorphous as Si₃N₄ thickness increases, leading to blocking of the epitaxial growth and the superhardness effect disappears. The critical thickness of Si₃N₄ layers, which marks the change from crystalline to amorphous, has been calculated through thermodynamic and elastic considerations. The hardening mechanisms of AlN/Si₃N₄ multilayers are discussed.