Surface shape control of the workpiece in a double-spindle triple-workstation wafer grinder

Double-spindle triple-workstation(DSTW) ultra precision grinders are mainly used in production lines for manufacturing and back thinning large diameter(≥300 mm) silicon wafers for integrated circuits.It is important, but insufficiently studied,to control the wafer shape ground on a DSTW grinder by adjusting the inclination angles of the spindles and work tables.In this paper,the requirements of the inclination angle adjustment of the grinding spindles and work tables in DSTW wafer grinders are analyzed.A reasonable configuration of the grinding spindles and work tables in DSTW wafer grinders are proposed.Based on the proposed configuration,an adjustment method of the inclination angle of grinding spindles and work tables for DSTW wafer grinders is put forward. The mathematical models of wafer shape with the adjustment amount of inclination angles for both fine and rough grinding spindles are derived.The proposed grinder configuration and adjustment method will provide helpful instruction for DSTW wafer grinder design.     

石英晶片化学机械抛光工艺优化

为同时优化化学机械抛光(CMP)后石英晶片平面度和表面粗糙度,进行化学机械抛光协调控制实验。分析了抛光时间、抛光转速和抛光压力对石英晶片平面度和表面粗糙度的影响,确定了最佳工艺参数。研究结果表明：石英晶片平面度和表面粗糙度都随抛光时间延长而优化,在150 min时,平面度和表面粗糙度都能达到稳定。抛光时间为150 min、抛光盘转速为50 r/min、抛光压力为53.5 N时,能使晶片同时得到较好的平面度和表面粗糙度,此时平面度为2.03μm,表面粗糙度为0.68 nm。     

双主轴三工位硅片磨床的工件磨削面型控制的研究

双主轴三工位（DSTW）超精密磨床主要应用于集成电路制造生产线中大直径（≥300mm）硅片的前道制备和背面减薄加工。通过调整DSTW磨床的主轴和工作台的倾角控制磨后的硅片面型的研究很重要,但尚未充分研究。本文分析了DSTW硅片磨床的砂轮主轴和工作台倾斜角度调整的要求。 提出了DSTW硅片磨床对砂轮主轴和工作台的合理配置方案。在此基础上,提出了DSTW硅片磨床的砂轮主轴和工作台倾角调整的方法。推导出粗磨轴和精磨轴的硅片面型与倾角调整量关系的数学模型。提出的磨床倾角配置方案和调整方法将给予DSTW晶圆磨床设计提供参考指导。     

反转法消除硅片重力附加变形适用性研究

建立了计算硅片重力附加变形的有限元模型,模型包含硅片残余应力的影响.通过有限元与实验方法研究了反转法对抛光与磨削加工硅片适用性.结果表明,反转法适用于抛光硅片,有限元与反转法所得重力附加变形差值小于1 μm;对#5000砂轮磨削的300 mm直径394 μm厚度硅片,硅片残余应力使反转前后重力附加变形不再相同,误差超过最大重力附加变形值的5;;对#2000砂轮磨削的200 mm直径194 μm厚度硅片,残余应力超过临界值,硅片变形发生分岔,硅片自由面形与重力附加变形不再符合叠加关系,反转法不再适用.