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采用反应磁控溅射法制备了一系列具有不同Si3N4层厚度的AlN/Si3N4纳米多层膜,利用X射线衍射仪、高分辨透射电子显微镜和微力学探针表征了多层膜的微结构和力学性能.研究了Si3N4层在AlN/Si3N4纳米多层膜中的晶化现象及其对多层膜生长结构与力学性能的影响.结果表明,在六方纤锌矿结构的晶体AlN调制层的模板作用下,通常溅射条件下以非晶态存在的Si3N4层在其厚度小于约1nm时被强制晶化为结构与AlN相同的赝形晶体,AlN/Si3N4纳米多层膜形成共格外延生长的结构,相应地,多层膜产生硬度升高的超硬效应.Si3N4随层厚的进一步增加又转变为非晶态,多层膜的共格生长结构因而受到破坏,其硬度也随之降低.分析认为,AlN/Si3N4纳米多层膜超硬效应的产生与多层膜共格外延生长所形成的拉压交变应力场导致的两调制层模量差的增大有关.
A series of AlN / Si3N4 multilayer films with different Si3N4 layer thicknesses were prepared by reactive magnetron sputtering. The microstructures of the multilayer films were characterized by X-ray diffraction, high resolution transmission electron microscopy and micromechanical probe. Mechanical properties.The effects of Si3N4 layer crystallization in AlN / Si3N4 multilayer films and its effect on the growth structure and mechanical properties of the multilayer films were studied.The results show that in the AlN / Si3N4 multilayer films with hexagonal wurtzite structure, Under normal sputtering conditions, the Si3N4 layer present in amorphous state is forcibly crystallized into a pseudocrystal having the same structure as AlN at a thickness of less than about 1 nm, and the AlN / Si3N4 nanomembrane forms a coextensive epitaxial growth Structure, and accordingly, the multi-layer film produces a super-hard effect of increasing hardness. Si3N4 is transformed into an amorphous state as the layer thickness is further increased, and the coherent growth structure of the multi-layer film is damaged and the hardness thereof decreases. The analysis shows that the superhard effect of AlN / Si3N4 multilayered films is related to the increase of the difference of the modulus of the two modulation layers caused by the alternating tension and compression stress field induced by the coexistence of multi-layer epitaxial growth.