LED蓝宝石衬底的表面质量会极大影响到后续外延质量, 进而影响到LED器件性能。蓝宝石研磨片经Al2O3磨粒粗抛液、SiO2磨粒精抛液下进行化学机械抛光(CMP), 最终表面经原子力显微镜(AFM)所测表面粗糙度达到0.101 nm, 获得亚纳米级粗糙度超光滑表面, 并呈现出原子台阶形貌。同时, 通过使用Zygo表面形貌仪、AFM观察蓝宝石从研磨片经Al2O3粗抛液、SiO2精抛液抛光后的表面变化, 阐述蓝宝石表面原子台阶形貌的形成原因, 提出蓝宝石原子级超光滑表面形成的CMP去除机理。通过控制蓝宝石抛光中的工艺条件, 获得a-a型、a-b型两种不同周期规律性的台阶形貌表面, 并探讨不同周期规律性台阶形貌的形成机理。

Surface quality of LED sapphire substrate influences epitaxy quality greatly, and further influences the performance of LED devices. After the chemical mechanical polishing (CMP) of slurry including Al2O3 abrasive and SiO2 abrasive of sapphire grinding wafer, finally ultra smooth surface of sub-nanometric roughness was achieved with surface roughness reaching 0.101 nm measured by atomic force microscope (AFM) and atomic step morphology was presented. Using Zygo profiler and AFM to observe the variations of surface of sapphire grinding wafer from being polished by Al2O3 abrasive slurry to SiO2 abrasive slurry, the generation reason of atomic step morphology of sapphire surface was elaborated, and the CMP removal mechanism of the sapphire atomically ultra-smooth surface was proposed. Through controlling the process conditions of sapphire polishing, a-a type and a-b type atomic step periodic morphologies were obtained respectively. The experimental result shows the chemical reaction speed of double-atom layer 6H1, 6H2 of different adsorptive energy between layers is slightly different. When the revolving speed is relatively slower and mechanical effect Rm is slightly weaker than chemical effect, the difference of chemical reaction speed Rc of different double-atom layer is also presented, and mechanical removal only acts on softening double-atom layer with sapphire polishing surface presenting step morphology of different width of a-b type; while when the revolving speed is relatively faster and mechanical effect Rm is slightly stronger than chemical effect, the mechanical removal speed of each double-atom layer is the same with sapphire polishing surface presenting step morphology of the same width of a-a type.