Active dummy generation for homogeneity increase in a 130 nm SiGe-BiCMOS process

In this work we investigated the chemical-mechanical polishing (CMP) of the shallow trench isolation of a 130nm SiGe-BiCMOS process. Different active dummy shapes, densities and distances to electrical active devices are considered. The test structures are placed in a dedicated layout to reach a wide range of active densities from 10 to 80%. The main concern of the investigation was the decrease of dishing effects in filler free structures in the surrounding of hetero-junction bipolar transistors. The width of the dummy free area was varied between 2 μm and 70 μm and an optimum was determined depending on the filler shape.