溅射方法和基体材料对氧化钛薄膜微观结构的影响

Effects of Sputtering Techniques and Substrate Materials on Microstructure of Titanium Oxide Films

目的研究不同溅射方法和基体材料对沉积氧化钛薄膜的晶体结构、化学价态、表面形貌的影响。方法采用高功率脉冲磁控溅射(HPPMS)和直流磁控溅射(DCMS)在316L不锈钢和硅片表面制备了氧化钛薄膜。采用等离子光发射谱检测了沉积薄膜时的等离子体特征。采用X射线衍射仪(XRD)、X射线光电子能谱(XPS)、原子力显微镜(AFM)和扫描电子显微镜(SEM),分别评价氧化钛薄膜的晶体结构、化学价态、晶粒尺寸和表面粗糙度。结果等离子体特征显示,沉积氧化钛薄膜时,HPPMS比DCMS具有更高的离化率和等离子体密度。XRD结果显示,在相同的平均溅射功率下,采用HPPMS和DCMS方法,均在不锈钢表面制备出纯金红石结构的氧化钛薄膜,而在硅片表面得到的氧化钛薄膜为金红石、锐钛矿混合结构,且采用HPPMS比DCMS技术制备的氧化钛薄膜含有更高的金红石含量。XPS结果显示,两种方法在所有基体表面均制备出了含有氧缺位的氧化钛薄膜。采用HPPMS和DCMS制备氧化钛薄膜时,不锈钢基体沉积的薄膜中,Ti3+/Ti4+比值均高于Si基体上的薄膜。SEM和硬度测试结果显示,HPPMS制备的氧化钛薄膜为等轴晶,晶粒较小,硬度较高。DCMS制备的氧化钛薄膜具有柱状晶的结构,晶粒较大。AFM的结果显示,采用不同溅射方法制备的氧化钛薄膜表面粗糙度没有明显差别。结论不同溅射方法和基体材料导致了薄膜沉积时样品表面离子轰击能量的差异,因此影响了氧化钛薄膜的晶体结构、化学价态和晶粒尺寸。

The work aims to study effects of sputtering techniques and substrate materials on crystal structure, chemical va- lence and morphology of titanium oxide films. Titanium oxide films were deposited on 316L stainless steel and silicon （t 00） wafers） in the method of high power pulsed magnetron sputtering （HPPMS） and DC magnetron sputtering （DCMS）. Plasma characteristics were tested by using optical emission spectroscopy. Crystal structure, chemical valence, grain size and surface roughness of the films were evaluated by using X-ray diffractometer （XRD）, X-ray photoelectron spectroscopy （XPS）, atomic force microscope （AFM） and scanning electron microscopy （SEM）, respectively. The plasma characteristics showed that HPPMS exhibited higher ionization rate and plasma density than DCMS in depositing titanium oxide films. XRD results showed that titanium oxide film of pure rutile structure was successfully prepared on 316L stainless steel in the methods of HPPMS and DCMS, while both rutile and anatase structures were obtained for the films on silicone substrate. Rutile content was higher on titanium oxide film prepared in the method of HPPMS than that on titanium oxide film prepared in the method of DCMS. XPS results exhibited that higher ratio of Ti3＋/Ti4＋ was obtained for films deposited in the method of either HPPMS or DCMS on stainless steel compared to that on silicon substrate. SEM and hardness test results showed that titanium oxide films deposited in the method of HPPMS exhibited equiaxed grains in smaller size and of higher hardness while the films deposited in the method of DCMS exhibited a columnar crystal structure in larger size. The AFM results showed no significant difference in surface roughness of the films deposited in the method of HPPMS and DCMS. Difference in ion bombardment energy of titanium oxide samples is caused by different sputtering techniques and substrate materials, and therefore crystal structure, chemical valence and grain size of titanium oxide films are affected as well.