硅晶圆磨削减薄工艺的磨削力模型

A GRINDING FORCE MODEL IN THE SILICON WAFER THINNING PROCESS

硅晶圆磨削减薄是一种有别于传统磨削的材料加工方式。磨削减薄过程中,硅晶圆和砂轮同时绕旋转轴旋转,砂轮沿垂直方向连续进给去除材料,其中磨削力是磨削质量的决定性因素。目前,尚缺少一个用于硅晶圆磨削减薄工艺的磨削力预测模型。为了得到磨削力模型,分析了磨削减薄过程中的硅晶圆材料去除机理,将磨削力分为摩擦力和切屑力,考虑了磨粒运动轨迹,分别计算了单颗磨粒在法向和切向上的摩擦力和切屑力,最后基于有效磨粒总数建立了总磨削力模型。模型综合考虑了磨削参数、砂轮和硅晶圆的几何参数和材料性质对磨削力的影响。讨论了砂轮进给速度、晶圆转速和砂轮转速三个主要磨削参数对磨削力的影响,讨论了硅晶圆上晶向对磨削力的影响,给出了磨削力在硅晶圆面上沿径向的分布情况。

Silicon wafer grinding thinning is a material removal method different from conventional grinding. During grinding, the silicon wafer and the grinding wheel rotate simultaneously, and the grinding wheel feeds into the silicon wafer to remove excess material. The grinding force is a determinative factor on the grinding quality. There is no theoretical model of grinding force in silicon wafer self-rotating grinding yet. To develop the grinding force model, the grinding mechanism of silicon wafer self-rotating grinding was studied, and the grinding force was divided into a sliding force and a chip formation force. By considering the grain trajectory during grinding, the sliding force and the chip formation force of single abrasive grain on normal and tangential directions were established. Subsequently, based on the number of effective cutting grains, the total grinding force model was established. In this model, the influence of processing parameters, geometry parameters and material properties of silicon wafer and grinding wheel were comprehensively considered. Nine sets of grinding parameters were adopted into the model to study the effects of feed rate, wafer speed and wheel speed on the grinding force.Meanwhile, the effects of crystalline orientation were discussed, and the distribution of grinding force along radius on silicon wafer surface was also analyzed.