微弧区间脉冲参量对Ti及TiN薄膜微观形貌及硬度的影响

发布时间：2018-05-03 09:53

本文选题：强辉弱弧放电区间 + 高功率脉冲电源　；参考：《西安理工大学》2017年硕士论文

【摘要】：根据气体放电双峰曲线中伏安特性处于“欧姆-反欧姆”过渡区间时,其电子迁移通量将数十倍于磁控溅射离子镀、靶电压数倍于多弧离子镀这一特性。借助脉冲电源模式构建出依靠宽脉冲强电离电场使真空腔内满足强辉弱弧的放电环境,并通过脉冲参量的调控将气体放电维持在强辉弱弧区间的不同阶段。基于此制备纯金属Ti薄膜及化合物TiN薄膜,并利用SEM、AFM、XRD、TEM、纳米压痕仪等检测手段,对薄膜组织形貌、晶体结构及显微硬度进行表征,以探索脉冲环境下镀料粒子能量大小及粒子沉积行为对薄膜生长过程及性能的影响规律。实验发现:对纯金属Ti薄膜而言,随着脉冲持续时间的增加,其表面形貌由球状团簇逐渐转变为疏松的棱角状生长,其截面形貌由纤细的柱状过渡为疏松的枝晶结构。同时,颗粒尺寸急剧增大,薄膜平整度及硬度值均降低。脉冲峰值电流的增大对薄膜形貌并未产生显著影响,但在一定程度上起到细化晶粒的作用。薄膜粗糙度值均维持在4nm以下。与此同时,峰值电流的增大促使沉积速率有效提升。从薄膜的物相分析结果可以看出,脉冲持续时间及峰值电流的增加均使得薄膜的结晶度有所提高且择优取向面也随之发生转变。从纯Ti薄膜的微观结构可以看出,脉冲持续时间为1.6 ms时薄膜中存在晶粒尺寸小于10nm纳米晶。脉冲持续时间越小,薄膜的硬度值越高(约为6.741GPa)。脉冲峰值电流处于15 A-30 A之间时存在硬度的最大值(约为7.203 GPa)。对于化合物TiN薄膜而言,脉冲持续时间与峰值电流的增加并未改变薄膜的形貌,均为典型的(111)面三角锥结构。两种参量的增加均使得薄膜的晶化程度有所提升,且薄膜沿(111)晶面择优生长的趋势逐渐增强。在一定程度上,随着峰值电流的增加,薄膜截面形貌出现近似熔融现象,使得膜层晶粒尺寸及粗糙度值降低,薄膜趋于致密化。同样,脉冲持续时间越小(2 ms),TiN薄膜硬度值越高(约为23.325 GPa)。脉冲峰值电流的改变对TiN薄膜的硬度变化影响不大,其值均在20-24 GPa波动。以上现象表明:气体放电位于强辉弱弧区间时,在较小的脉冲持续时间下,薄膜的成核速率大于生长速率。此时,薄膜颗粒尺寸小而均匀,且致密性好,力学性能较好。同时,存在合适的峰值电流变化范围,既可以提高沉积速率又能进一步优化薄膜形态及性能。
[Abstract]:According to the fact that the volt-ampere characteristic of the gas discharge bimodal curve is in the "ohm-anti-ohmic" transition region, the electron transport flux will be several times higher than that of magnetron sputtering ion plating, and the target voltage will be several times higher than that of multi-arc ion plating. With the help of the pulse power supply mode, the discharge environment of the vacuum cavity with strong ionization electric field is constructed, and the gas discharge is maintained at different stages of the strong glow and weak arc region through the control of pulse parameters. Based on this method, pure metal Ti thin films and compound TiN thin films were prepared. The microstructure, crystal structure and microhardness of the thin films were characterized by means of SEM AFM XRDX TM and nano-indentation instrument. The effects of particle energy and particle deposition behavior on the growth process and properties of the films were investigated. It is found that the surface morphology of pure Ti thin film changes from spherical cluster to loose angular growth with the increase of pulse duration, and the cross-section morphology changes from fine columnar to loose dendritic structure. At the same time, the particle size increases sharply and the film smoothness and hardness decrease. The increase of pulse peak current has no significant effect on the morphology of the film, but to some extent, it plays the role of grain refinement. The roughness values of the films are kept below 4nm. At the same time, the increase of peak current promotes the deposition rate effectively. The results of phase analysis show that the increase of pulse duration and peak current make the crystallinity of the film increase and the preferred orientation surface change with the increase of pulse duration and peak current. It can be seen from the microstructure of pure Ti film that the grain size of the film is smaller than that of 10nm nanocrystalline when the pulse duration is 1.6 Ms. The lower the pulse duration, the higher the hardness of the film (about 6.741 GPA). When the pulse peak current is between 15 and 30 A, there is a maximum hardness (about 7.203 GPA). For compound TiN films, the increase of pulse duration and peak current does not change the morphology of the films, and they all belong to the typical triangular cone structure. With the increase of the two parameters, the crystallization degree of the films is increased, and the preferential growth along the crystal plane of the films increases gradually. To a certain extent, with the increase of peak current, the cross-section morphology of the film appears approximately melting phenomenon, which makes the grain size and roughness value of the film decrease, and the film tends to densify. Similarly, the higher the pulse duration is, the higher the hardness of tin films is (about 23.325 GPA). The change of pulse peak current has little effect on the hardness of TiN film, and its values fluctuate from 20 to 24 GPa. The above results show that the nucleation rate of the film is larger than the growth rate when the gas discharge is in the region of strong glow and weak arc and the pulse duration is small. At this time, the particle size of the film is small and uniform, and the film has good compactness and good mechanical properties. At the same time, there is a suitable range of peak current variation, which can not only increase the deposition rate, but also further optimize the morphology and properties of the films.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB306;TB383.2

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