Elastic and plastic energy analysis for multilayered thin films by nanoindentation

本研究采用超高真空多阴极型溅射装置，用反应溅射方法制备了衬底/Al/TiN双层薄膜。靶材为75 mm铝(99.99%)和钛(99.98%)。所用基材为铝硅酸盐玻璃。铝层厚度在0~500 nm之间变化。为了避免直接破坏TiN/Al层的界面(S)，在TiN薄膜表面涂覆了厚度为500 nm的TiN薄膜，得到的衬底/Al/TiN双层膜的硬度随Al层厚度的增加而降低。纳米压痕估算的耗散能随着铝层厚度的增加而增大。对于较大的触笔负载，耗散能量的增加更为显著。弹性能几乎与Al厚度无关。从塑性能和弹性能对Al厚度的依赖关系可以得出结论：塑性变形主要发生在软Al层，…的弹性变形II.基片/(Al/TiN)多层膜研究了基片/(Al/TiN)_n/TiN多层膜，以讨论Al和TiN层在纳米压痕下的塑性和弹性行为中的作用。研究的层数分别为2、20和40层。还沉积了厚度为500 nm的TiN薄膜。所使用的沉积和压痕设备与上述相同。对于Al厚度为100 nm且具有20或40层结构的薄膜，观察到硬度的提高。随着Al厚度的进一步增加，所有层组织的硬度都单调下降。用纳米压痕方法估算了衬底/(Al/TiN)n/TiN多层膜的耗散能随Al厚度的增加而增大。另一方面，弹性能几乎不受Al厚度的影响。随着Al厚度的增加，耗散能与加载能量之比几乎单调增加。然而，与单层TiN单层薄膜相比，具有100 nm Al厚度和40层结构的薄膜的比率较小。这表明该薄膜比单一的TiN薄膜具有更大的弹性，厚度为5 nm的薄Al层不是发生塑性变形的层。在该薄膜中，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。III.衬底/(PTFE/TiN)和(PTFE/TiN)多层薄膜研究了衬底/(PTFE/TiN)_n和(PTFE/TiN)_n多层薄膜，以讨论软性PTFE层在纳米压痕下的塑性和弹性行为中的作用。所研究的膜层数分别为2、10、20、40和60。膜层数越多，膜层硬度越高。弹性能也随着层数的增加而增加。随着膜层厚度的增加，PTFE/TiN膜层体系的弹性能增加比PTFE/TiN膜层体系更为显著。这被认为与两层材料表面自由能的不同有关。纳米压痕能谱分析表明，薄的聚四氟乙烯层起到了反常层的作用，提高了薄膜的弹性。较少

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