Dishing and erosion amount prediction according pattern density calculation algorithm in 3D design layout — Kuang-Wei Chen

Chemical Mechanical Planarization (CMP) become a mainstream process in semiconductor industry, it is a key technology to generate flat and smooth surface at several critical steps in the manufacturing processes. The planarization performance is influenced by topography characteristics, line/space width, pattern density, slurry chemistry, rotation speed, PAD type, force/pressure, etc. However, as device continuous shrink, CMP process becomes more challengeable to achieve planarization. There exist two common issues that often occur at different pattern densities and line widths are dishing and erosion, as shown in Fig. 1. In STI CMP, dishing is defined as the oxide loss relative to the level of the neighboring nitride space, and erosion refers to the nitride loss relative to the nitride level of the neighboring area. Wide trenches or open structures usually enhance the dishing issue, while dense trenches lead to more erosion. Nitride erosion exposes the underlying active devices will lead to device failure; on the other hand, oxide dishing results in poor isolation.