CMP on SiGe materials — Linking chemical and physical properties to design low defect and selective slurries

Germanium as a high electron mobility material (HEMM) is considered to replace silicon in FET devices. However, since a lot of technical challenges for pure germanium still need to be overcome, Silicon-Germanium alloys (SiGe) devices combine properties of Silicon and Germanium almost linear depending on their composition and are easier to integrate. For p-MOS integration schemes, SiGe has shown to be a promising candidate [1]. Furthermore, Si_1-xGe_x materials are used as strain relaxed buffer for Ge p-MOS devices. This paper shows on the one hand SiGe stochiometry dependent properties which are important during a CMP process e.g. etching rates and on the other hand demonstrates the latest developments of CMP slurries and their performance for such alloys. We show that slurries containing germanium enhancers and Poly-Si suppressors showed improved defect performance and excellent selectivities towards different substrates as eHarp and Poly-Si.