纳米磨料硬度对超光滑表面抛光粗糙度的影响

Effect of hardness of nano-sized abrasives on roughness of polished super-smooth surface

通过均相沉淀法制备了纳米CeO2和Al2O3粉体,研究了在相同抛光条件下纳米CeO2、Al2O3和SiO2磨料对硅片的抛光效果,用原子力显微镜观察了抛光表面的微观形貌并测量其表面粗糙度。结果表明:纳米CeO2磨料抛光后表面具有更低的表面粗糙度,在5μm×5μm范围内表面粗糙度Ra值为0.240nm,而且表面的微观起伏更趋向于平缓;考虑了纳米磨料在抛光条件下所发生的自身变形,其变形量相当于一部分抵消了纳米磨料嵌入基体材料的切削深度,而这个切削深度最终决定了抛光表面的粗糙度;分析指出这个变形量与纳米磨料的硬度成反比,硬度低的纳米磨料由于自身变形量大,导致切削深度小,抛光后表面的粗糙度值低。解释了在相同的抛光条件下不同硬度的纳米磨料具有不同的抛光表面粗糙度的原因。

Nano-powder of CeO2 and Al2O3 were prepared via homogenous precipitation,and the different polishing behavior of nano-CeO2, nano-Al2O3 and nano-SiO2 abrasives under the same polishing condition were studied by atomic force microscopy （AFM）. The surface roughness of the wafer polished by nano-CeO2 is lower than that polished by the nano-Al2O3 and nano-SiO2, and its surface undulation is smaller. The influence of the deformation of the abrasive particle on polishing mechanism is considered for the first time. The deformation of the abrasive counteracts part of the cutting depth which determines the roughness of the polished surface. The deformation amount is in proportion to the hardness of the abrasives. The reason why the abrasives with different hardness has different polishing behavior is analyzed.