多晶硅表面酸腐蚀制备绒面研究

Texturing of Multicrystalline Silicon with Acidic Etching

采用各向同性腐蚀法制备多晶硅绒面,腐蚀液为HF和HNO3的混合溶液,缓和剂为NaH2PO4.2 H2O溶液.利用SEM、AFM和紫外分光光度计对硅片绒面进行检测和分析,初步探讨了酸腐蚀机理.结果表明：采用NaH2PO4.2 H2O溶液作为缓和剂,腐蚀后的硅片表面具有均匀的腐蚀坑,表面陷光效果较好,通过优化各种参量,反应速度可以控制在2μm/min左右,适合工业生产的要求.在富HF时,硅片表面易形成尖锐边缘的腐蚀坑,出现或多或少的小孔,反射率最低可达16.5%-17.5%;在富HNO3时,硅片表面易形成腐蚀坑较浅、尺寸偏大的气泡状绒面或光面,反射率较高.

Texturing of multicrystalline silicon were prepared by isotropic acidic etching.The mixtures contained hydrofluoric acid（HF） and nitric acid（HNO3）,with NaH2PO4.2H2O solution added as diluents.Texturing of multicrystalline silicon were analyzed by SEM,AFM and ultraviolet spectrophotometer,and the mechanism of silicon etching was preliminary discussed.The results show that the surface of multicrystalline silicon being etched has uniform etched-pits and efficient light trapping with NaH2PO4.2H2O solution added as diluents in HNO3/HF mixture.Optimized the conditions,etching rate can control about 2 μm/min,and it meets requirement for industrial production.In HF-rich HF/HNO3 mixtures the surface of multicrystalline silicon easily form etched-pits with sharp edges,more or less small hole,and the lowest reflectance can reach 16.5%～17.5%.In HNO3-rich HF/HNO3 mixtures the surface of multicrystalline silicon form shallower etch pits,larger size bubble-like texture or polished Si wafers and the higher reflectance.