超薄纳米铜薄膜在接触变形下变形机制的研究

发布时间：2018-09-10 11:48

【摘要】：纳米晶金属薄膜材料目前已经被广泛应用于微电子，半导体等高新领域中。这种新型材料不仅可以作为MEMS部件上的硬质涂层，也可以作为电子器件上的导热导电涂层而使用。由于纳米薄膜在工作过程中往往会受到循环应力的作用，因此，其力学性能成为其研究的重点，，而揭示薄膜在受力过程中的变形机制对于纳米薄膜力学性能的研究起到重要的作用。本文通过采用一种薄膜转移技术方法，研究超薄纳米晶铜薄膜在接触变形下的微观结构和变形机制。即首先利用光刻蚀技术制作带有特殊花纹的“光刻胶/SiO2/Si”复合结构，然后通过直流磁控溅射在复合基底上制备50nm厚的超薄纳米晶铜薄膜。利用扫描和透射电子显微技术，研究薄膜纳米压痕微观组织形貌及纳米尺度下组织结构的变化，并探讨了纳米压痕的微观变形机制。其研究结果如下： (1)扫描与透射电子显微镜下，压痕为正三角形，其形状与压头相吻合，并在压痕区域周围出现明显的“pile-up”现象。与非压痕部位相比，纳米压痕区域的晶粒数量减少，晶粒取向发生变化。 (2)高分辨透射电子显微镜下，压痕区域的晶粒为等轴晶，晶粒尺寸比未压痕区域晶粒的尺寸大。另外晶粒中还出现大量的形变孪晶，且孪晶出现明显取向性。 (3)纳米压入过程中，晶粒长大可以通过晶界的迁移、晶粒的旋转以及孪晶调节的方式，与周围晶粒减小晶界角；或者以吞噬小尺寸晶粒的方式进行晶粒长大。 (4)形变孪晶是薄膜在接触变形下的另一个主要途径。形变孪晶通过晶界发出不全位错在滑移面上形成，同时改变晶粒的形状。晶粒内部的不全位错在局部应力作用下通过多次自增殖的方式在孪晶面滑移形成形变孪晶。另外，不全位错也可以利用回弹机制在晶粒中形成“V”字形和平行四边形的孪晶区域。
[Abstract]:Nanocrystalline metal thin films have been widely used in high-tech fields such as microelectronics and semiconductors. This new material can be used not only as a hard coating on MEMS parts, but also as a thermal conductive coating on electronic devices. The mechanical properties of nanocrystalline films have become the focus of study because they are often subjected to cyclic stress in the working process. Revealing the deformation mechanism of the film plays an important role in the study of the mechanical properties of nanocrystalline films. In this paper, the microstructure and deformation mechanism of ultrathin nanocrystalline copper films under contact deformation were studied by a thin film transfer technique. Firstly, the "photoresist / Sio _ 2 / Si" composite structure with special pattern was fabricated by photoetching technique, and then the ultrathin nanocrystalline copper thin films with 50nm thickness were deposited on the composite substrate by DC magnetron sputtering. Scanning and transmission electron microscopy (TEM) techniques were used to study the microstructure and microstructure of nano-indentation films. The mechanism of nano-indentation deformation was also discussed. The results are as follows: (1) under the scanning and transmission electron microscopy, the indentation is equilateral triangle, its shape is consistent with the indentation head, and there is an obvious "pile-up" phenomenon around the indentation area. Compared with the non-indentation site, the number of grains in the indentation area decreased and the grain orientation changed. (2) under the high resolution transmission electron microscope, the grains in the indentation region were equiaxed. The grain size is larger than that in the unindented region. In addition, there are a large number of deformation twins in the grains, and the twins have obvious orientation. (3) in the process of nanocrystalline indentation, the grain growth can pass through the grain boundary migration, the rotation of the grains and the adjustment of the twins. (4) deformation twinning is another main way of film deformation under contact deformation. Deformation twins emit incomplete dislocations through grain boundaries on the slip plane and change the shape of the grains at the same time. Deformation twins are formed by multiple self-proliferation of incomplete dislocations in grains under local stress. In addition, incomplete dislocations can also be used to form "V" zigzag and parallelogram twin regions in the grains by means of springback mechanism.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.121

【参考文献】