金刚石线锯切割多晶硅片表面特性与酸刻蚀制绒问题

The Surface Characteristics of Diamond Wire Sawn Multicrystalline Silicon Wafers and Their Acidic Texturization

为解决金刚石切割多晶硅片与常规HF-HNO3-H2O混合酸湿法制绒技术不兼容的问题，对金刚石切割多晶硅片的表面特性和大幅度提高混合酸溶液中HF的比例进行了刻蚀制绒实验．结果表明，金刚石线切割多晶硅片表面存在约33％的光滑条带区域，其余为与砂浆切割硅片表面相近的粗糙崩坑区域；这些光滑区域使得金刚石切割多晶硅片表面光反射率比砂浆切割多晶硅片高3％～4％；而且光滑区域在富HN0。和富HF的HF—HNO3-H2O混合酸溶液中均较难于腐蚀，使其刻蚀制绒后反射率比砂浆切割多晶硅片低1％～2％，制绒后的金刚石切割多晶硅片反射率比制绒后的砂浆切割多晶硅片高4％～6％，不能满足太阳电池生产要求．富HNO3和富HF两种酸刻蚀体系，均不能解决金刚石切割多晶硅片的制绒问题．

In order to solve the incompatibility problems between the diamond cut multicrystalline silicon wafer and the currently used HNO3-rich HF-HNO3-H2O acidic wet etching technology, the surface feature of diamond cut multicrystalline silicon wafers was investigated, and the acidic etching was revealed aimed to improve the acidic texture of diamond cut multicrystalline silicon wafers by greatly increase the proportion of HF in the mixed acid solution. The results show that, diamond cut silicon surfaces have about 33 % smooth band areas, with the rest of surface being pits of cracking and spalling, similar to the surfaces of slurry cut silicon wafers. These smooth areas leads to 3% --4% higher light reflectivity as compared to the slurry cut multicrystalline silicon wafers. The smooth area is relatively difficult to etch in both HNO3-rich and HF-rich HF- HNO3- H2O mixed acid solution, making the light reflectivity reduction 1%--2% lower than the slurry cut wafers, after the acidic etching. The final light reflectivity of the acidic wet textured diamond cut multicrystalline silicon wafers is thus 4%- 6 % higher than the similarly textured slurry cut multicrystalline silicon wafers, which is not low enough for solar cell application. Both HNO3-rich and HF-rich etching systerm, can not solve the problem of etching diamond wire saw multicrystalline silicon wafers.