Elastic and plastic energy analysis for multilayered thin films by nanoindentation

1 .衬底/Al/TiN双层薄膜本研究采用超高真空多阴极型溅射装置反应溅射沉积了衬底/Al/TiN双层薄膜。靶材为75mm Al（99.99%）和Ti（99.98%）。基材为硅酸铝玻璃。铝层厚度从0 ~ 500nm不等。为了避免直接破坏TiN/Al层的界面，采用镀覆厚度为500nm的TiN顶层层。随着Al层厚度的增加，衬底/Al/TiN双层膜的硬度降低。纳米压痕计算的耗散能随着铝层厚度的增加而增加。对于较大的手写笔负载，耗散能量的增加更为显著。弹性能几乎与铝的厚度无关。从塑性能和弹性能对Al厚度的依赖性来看，塑性变形主要发生在软Al层，而弹性变形主要发生在TiN层。研究了衬底/(Al/TiN)_n/TiN多层薄膜，探讨了Al和TiN层在纳米压痕下的塑性和弹性行为。研究的层数分别为2层、20层和40层。制备了厚度为500nm的TiN薄膜。所使用的沉积和压痕装置与上述相同。对于铝膜厚度为100 nm、层状结构为20或40层的薄膜，硬度有所提高。随着Al厚度的进一步增加，各层组织的硬度单调降低。衬底/(Al/TiN)_n/TiN多层膜的纳米压痕耗散能随Al厚度的增加而增加。另一方面，弹性能几乎与铝的厚度无关。随着铝厚度的增加，耗散能量与负载能量的比值几乎单调增加。然而，与TiN单层膜相比，Al厚度为100nm， 40层结构的薄膜的比值较小。这意味着该薄膜比单片TiN更有弹性。厚度为5nm的薄铝层不作为发生塑性变形的层。在该薄层中，薄膜界面处的应力和应变被认为是导致多层薄膜异常行为的原因。研究了衬底/(PTFE/TiN)和（PTFE/Ti）多层薄膜，探讨了软层PTFE在纳米压痕下的塑性和弹性行为。研究的层数分别为2层、10层、20层、40层和60层。膜的硬度随层数的增加而增加。随着层数的增加，弹性能也随之增加。PTFE/TiN层体系的弹性能随膜层数的增加而增加的幅度要大于PTFE/Ti层体系。这被认为与两层材料之间表面自由能的差异有关。纳米压痕的能量分析表明，薄的聚四氟乙烯层作为一个异常层，增加了薄膜的弹性。少

I.Substrate/Al/TiN bilayered thin flimsSubstrate/Al/TiN bilayered films examined in this study have been deposited by reactive sputtering using the ultra high vacuum multi cathode-type sputtering apparatus. Targets were 75mm Al (99.99%) and Ti (99.98%). Substrate used was aluminosilicate glass. The thickness of Al layer was varied from 0 to 500nm. The toplayer of TiN with a thickness of 500 nm was coated to avoid a direct destruction of interface (s) of TiN/Al layers.The hardness obtained for Substrate/Al/TiN bilayered films decreases with increasing Al layer thickness. The dissipated energy evaluated by nanoindentation increases with increasing Al layer thickness. The increase in the dissipated energy is more significant for a large stylus load. The elastic energy is nearly independent of Al thickness. From the dependencies of plastic and elastic energies on Al thickness, it is concluded that the plastic deformation occurs mainly in the soft Al layer and that the elastic deformation o … More ccurs mainly in the TiN layer.II.Substrate/(Al/TiN) multilayered thin filmsSubstrate/(Al/TiN)_n/TiN multilayered films have been examined in order to discuss role of Al and TiN layer in plastic and elastic behavior under the nanoindentation. The number of layers studied was 2, 20 and 40. The toplayer of TiN with a thickness of 500 nm was also deposited. The deposition and indentation apparatus used are the same as descried above.For films with an Al thickness of 100 nm and with 20 or 40-layered structure, the hardness enhancement is observed. For a further increase in Al thickness, the hardness decreases monotonically for all layer structure. The dissipated energy evaluated by nanoindentation for substrate/(Al/TiN)_n/TiN multilayered films increases with Al thickness. on the other hand, the elastic energy is nearly independent of Al thickness. The ratio or dissipated to loaded energy increases nearly monotonically with increasing Al thickness. However the ratio of the film with 100nm Al thickness and 40 layered structure indicates a smaller value compared to that of the monolithic TiN single layer film. This implies that this film is more elastic than the monolithic TiN.The thin Al layer of 5 nm thickness does not act as the layer in which plastic deformation occurs. In this thin layer, the stress and strain at the interface in a thin film are thought to cause abnormal behaviors of the multilayered thin films.III.Substrate/ (PTFE/TiN) and (PTFE/Ti) multilayered thin filmsSubstrate/(PTFE/TiN)_n and (PTFE/TiN)_n multilayered films have been examined in order to discuss role of soft PTFE layer in plastic and elastic behavior under the nanoindentation. The number of layers studied was 2, 10, 20, 40, and 60.The hardness of the film increses with increasing the number of layeres. The elestic energy is alos increasing with increasing the number of layer. The increase in the elestic energy with increasing the film layer is more remarkable for PTFE/TiN layer system than for PTFE/Ti layer system. This is thought to relate to the difference in the surface free energy between the two layer materilas. The energy analysis by nanoinddentation clarify that the thin PTFE layer act as an abnormal layer that increases the elesticity of the film. Less