化学气相沉积碳化硅超光滑抛光机理与表面粗糙度影响因素

Mechanism and Influencing Factors on Surface Roughness of Ultra-smooth Polishing of Chemical Vapor Deposition Silicon Carbide

为实现化学气相沉积碳化硅(CVD SiC)的超光滑抛光,采用纳米划痕试验研究了化学气相沉积碳化硅脆塑转变的临界载荷,根据单颗磨粒受力对其抛光机理进行了分析,并从材料特性、工艺参数以及抛光液pH值三个方面对其表面粗糙度影响因素进行了系统的试验研究。研究结果表明:化学气相沉积碳化硅的稳定抛光过程是磨粒对碳化硅表面的塑性域划痕过程;CVD SiC的晶粒不均匀与表面高点会降低最终所能达到的表面质量;表面粗糙度在一定范围内随磨粒粒度增加呈近似线性增长,随抛光模硬度的增加而增长;抛光压强对表面粗糙度的影响规律与抛光模的变形行为相关,当抛光模处于弹性或弹塑性变形阶段时,表面粗糙度随抛光压强的增加呈小幅增长,而当抛光模包含塑性变形之后,表面粗糙度基本与抛光压强无关;此外,抛光速度和抛光液pH值对表面粗糙度的影响不大。研究结论为CVD SiC超光滑抛光的工艺参数优化选择提供了定量的试验依据。

To realize the super-smooth polishing of chemical vapor deposition silicon carbide （CVD SIC）, nano-scratch test is applied to study the critical load for brittle-ductile transition, and its polishing mechanism is analyzed according to the force on an abrasive grain. Furthermore, the influencing factors on the surface roughness are systemically investigated by experiments from the aspects of material characteristics, processing parameters and pH values of the polishing fluids. The research results show that the polishing mechanism for CVD SiC in a steady polishing process is a ductile scratch process of abrasive particles on the surface of CVD SiC. The inhomogeneity of CVD SiC grains and surface high spots degrade the surface finish. The surface roughness increases nearlinearly with the abrasive particle size in a certain extent, and increases with the hardness of polishing pad. However, the effect of polishing pressure on surface roughness is related to the deformation behavior of polishing pad, i.e., when polishing pad has an elastic or elastic-plastic deformation, surface roughness increases with polishing pressure in a narrow range; when polishing pad has a plastic deformation, polishing pressure has no obvious effect on surface roughness. In addition, polishing velocity and the pH value of polishing fluid have little effect on surface roughness. The research results provide a quantitative experimental basis for the optimization of selecting processing parameters during the super-smooth polishing of CVD SiC.