Dummy fill effect on CMP planarity

With the use of a chemical-mechanical polishing(CMP)simulator verified by testing data from a foundry,the effect of dummy fill characteristics,such as fill size,fill density and fill shape,on CMP planarity is analyzed.The results indicate that dummy density has a significant impact on oxide erosion,and copper dishing is in proportion to dummy size.We also demonstrate that cross shape dummy fill can have the best dishing performance at the same density.     

冗余金属填充对化学机械抛光的平坦性影响研究

在深亚微米大规模集成电路制造过程中,化学机械抛光已经被广泛用来实现大范围的平坦性。化学机械抛光后的形貌非常依赖版图的样式,并且在芯片上会有很大的波动。然而,由于器件结构分布的不均匀,化学机械抛光会导致金属层的凹陷和电解质的侵蚀。解决这种现象的方法之一便是插入冗余金属来实现给定层的均匀性。本文使用中科院EDA中心开发的化学机械抛光模拟器,分析了冗余填充的尺寸,密度和形状之类的参数对化学机械抛光后表面平坦性的影响。