脉冲激光沉积TiN/AlN多层膜的微结构与力学性能

Microstructure and mechanical properties of TiN/AlN multilayer films deposited by pulsed laser ablation

采用脉冲激光沉积(LPA)法,在单晶Si表面制备了调制周期为50nm的不同调制比的TiN/AlN多层膜,并研究了调制比对多层膜微结构和力学性能的影响。扫描电镜(SEM)和原子力显微镜(AFM)显示,薄膜的调制比在1～4之间。并且小调制比下薄膜表面的岛密度小,岛面积过大,分布不均匀,相邻岛之间的起伏较大。X射线衍射(XRD)结果表明,小调制比下,AlN相为明显的(002)择优取向,TiN相主要以(200)、(220)形式存在;调制比增大后,AlN相的择优取向减弱,同时伴随着薄膜晶粒的细化及硬度增强,这一研究结果说明,调制比对多层膜的性质有一定的影响,大调制比会导致Al元素在界面处聚集,并与TiN进行合金化后的形成TiAlN结构,进而对薄膜的硬度产生影响。

In this study,polycrystalline TiN/AlN multilayer film with various modulation ratios was deposited onto silicon substrate using pulsed laser ablation.The microstructure and the nanoindentation hardness of TiN/AlN multilayer films were also investigated.SEM and AFM confirmed a standard modulation ratio ranging from 1 to 4,the least density and large tracts of island had been found in small modulaton ratio.XRD revealed that an obvious preferred orientation（002） is appeared in AlN phase,and orientation（200）（220） is also presented in TiN phase.Preferred orientation tends to weaken when arising from the structure refinement by the increasing of modulation ratio.At the same time,thinner of grain size was also found.This point was consistent with the results obtained by SEM and EDS.Nanoindentation showed that the smaller grain size there is in the film,the better film hardness will be,and is accompanied by an enhancement of Al content in the interface.The results of this study meant that the TiN/AlN multilayer film present micro structural features influenced by modulation ratio,and Al element would be accumulated easily near the interface under the circumstances of small modulation ration.These led to the formation of TiAlN structure,and therefore an enhancement of hardness.