单晶硅片的电化学-固结-游离磨料复合加工表面完整性

Surface Integrity of Electrochemical-Fixed-Free-Abrasive Composite Processing of Monocrystalline Silicon Wafers

为解决金刚线固结磨料切割硅片中表面线痕较深等问题,提出了电化学-固结-游离磨料复合加工技术。通过实验对比固结磨料线锯切割和复合切割后硅片的表面形貌、表面平均粗糙度(Ra)和表面平整度(即总厚度变化(TTV)),评估复合加工对单晶硅片切割质量的影响。实验结果表明,复合加工技术的固结磨料刻滑-游离磨料剥落-电化学氧化材料去除复合机制使硅片表面的线痕明显减少。Ra和TTV也得到了明显改善,表面粗糙度曲线峰谷差从12.09μm降至4.21μm,Ra从1.20μm降至0.65μm,TTV从8.24μm降至6.46μm。基于本实验系统进一步开展电参数对比实验得出复合加工的最优电压为20 V。该复合加工方法能够有效改善切割硅片的表面质量,降低后续制绒工序的减薄量,进而降低生产成本。

In order to solve the problem of deep surface marks in diamond wire fixed-abrasive cutting silicon wafers,an electrochemical-fixed-free-abrasive composite processing technology was proposed.The surface morphology,surface average roughness(R_a)and surface flatness(i.e.total thickness variation(TTV))of silicon wafers after fixed-abrasive wire saw cutting and composite cutting were compared through experiments to evaluate the impact of composite processing on the cutting quality of monocrystalline silicon wafers.The experimental results show that the composite processing technology significantly reduces the line marks on the silicon wafer surface due to the composite mechanism of fixed-abrasive cutting,free-abrasive peeling and electrochemical oxidation material removal.R_a and TTV are also significantly improved,with the peak-to-valley difference in surface roughness curves decreasing from 12.09μm to 4.21μm,R_a decreasing from 1.20μm to 0.65μm,and TTV decreasing from 8.24μm to 6.46μm.Based on the experimental system,further electrical parameter comparison experiments were conducted,and it is obtained that the optimal voltage for composite processing is 20 V.The composite processing method can effectively improve the surface quality of cutting silicon wafers,reduce the thinning amount of wafers in subsequent grinding processes,and thereby lower production costs.