Development of In-Situ Surface Observation System with an Atomic Resolution under Tensile Stress by Atomic Force Microscope

为了解释微纳力学体系中薄膜表面的变形和裂纹扩展机制，发展了一种新的具有原子级分辨率的拉伸应力下的表面原位观测系统。力学性能如杨氏模量可同时测定。该观察系统由片上拉伸测试系统和商品化的原子力显微镜（AFM）组成。片上测试系统的特点是由一个静态加载机构与一个片弹簧和一个测试芯片的单晶硅15×15×0.5毫米。特别注意的是，抑制振动的影响，表面的图像与原子分辨率。在不同的拉伸应变下，可以观察到云母表面的原子图像，直到断裂发生。对沉积在Si（100）上的TiN薄膜的裂纹生长和杨氏模量也有清晰的描述。 ...更多信息 简易爆炸装置(1)该系统由片上拉伸测试装置和商品化的AFM系统组成。为了完善片上拉伸测试装置的部分和整个单元，应特别注意以下几点：（a）具有足够刚度的不锈钢材料的选择和各部分尺寸的设计，（B）围绕系统的气密室，以及（c）在系统和气密室的适当点下插入橡胶板。(2)即使在2.37%的拉伸应变下，偏转信号中的周期性噪声也消失了，直到可以观察到具有原子分辨率的云母表面的相同图像。因此，一个新的原位表面观测系统在拉应力下的原子分辨率已首次开发。(3)当应变连续增加到4.08%时，云母的表面图像突然改变。可以看出，基面的晶格参数已经变为标准常数0.52nm的两倍长，因为保持了六次旋转对称。张应力释放后，图像恢复到原始图像。这种突然的图像变化也显示出可重复性。我们无法解释这一有趣现象的原因。(4)当应变为1.56%时，TiN薄膜在垂直于拉伸应力的方向上出现第一道裂纹。结果表明，随着应变的增加，裂纹长度增加，裂纹数目增多。有趣的是，还可以澄清的是，在TiN的情况下，裂纹几乎以彼此相等的距离发生。可以认为，裂纹形态的周期性是由受应力固体的波动稳定性引起的。裂纹的横截面形状为矩形，裂纹的深度与薄膜的厚度相对应。可以认为TiN薄膜与硅基体界面处的分层影响了TiN薄膜中裂纹的生长。(5)TiN薄膜中裂纹的形成与衬底材料和厚度有关。少

A new in-situ surface observation system under tensile stress with an atomic resolution has been developed for the purpose of the explanation of the deformation of the surface and the crack growth mechanism for thin films in the micro- and nano-mechanical systems. The mechanical properties such as Young's modulus can be determined at the same time. This observation system consists of the on-chip tensile testing system and a commercialized atomic force microscope (AFM). The on-chip testing system is characterized by a static loading mechanism with a flat spring and a test chip of single-crystal silicon of 15×15×0.5 mm. Particular attention has been paid to the suppression of the vibration which effects on images of the surface with an atomic resolution. Atomic images of the surface of mica can be observed under various tensile strains till the occurrence of the fracture. The growth of the cracks and Young's modulus for TiN thin film deposited on silicon (100) specimen can be also clarif … More ied.(1) The system was consisted of a on-chip tensile testing device and a commercialized AFM system. In order to improve the part of the on-chip tensile testing device and the whole unit, special attentions for the fetal vibration should be paid to the points as follows : (a) the selection of the stainless steel material with enough stiffness and the design of the dimension for each part, (b) an air tight chamber around the system and (c) insertion of rubber plates under the appropriate points of the system and air tight chamber.(2) The periodic noise in the deflection signal disappears even under tensile strain of 2.37% until the same image with an atomic resolution of mica surface could be observed. Therefore, a new in-situ surface observation system under tensile stress with an atomic resolution has been first developed.(3) When the strain was continuously added up to 4.08%, the surface image of the mica suddenly changed. It can be seen that the lattice parameter of the basal plane has become twice times as long as the standard constant of 0.52 nm as the six hold rotational symmetry was maintained. After the tensile stress was released, the image returned to its original one. This abrupt image change also showed reproducibility. We couldn't clarify the reason of this interesting phenomenon.(4) The first crack of TiN film was observed in the vertical direction to the tensile stress at the strain of 1.56%. It could be seen that the crack length grows and the number of the crack increase with increasing the strain. Interestingly, it could be also clarified that the cracks occurs almost at equal distances each other in the case of TiN. It could be considered that the periodicity of the cracking pattern is attributed to the wave stability of stressed solid. The cross section profile showed the rectangular shape and the depth of the crack corresponds to the thickness of the film. It could be considered that the delamination of the film at the interface between the film and the silicon substrate affected the growth of the cracks in TiN film.(5) The formation of the cracks in TiN thin films depended on the substrate material and the thickness. Less