CMP process development for high mobility channel materials

Inhalt:
High mobility channel materials are a promising option for devices beyond the 14nm technology node. Due to their high electron and hole mobilities the integration of III/V materials and Ge are pursued for n-MOS and p-MOS. High performance for Ge-based pMOS devices has been demonstrated on a Si platform. Within the Ge-STI approach the Ge integration is done on regular Si wafers. After standard STI processing on 300mm Si wafers the Si is recessed selectively and the resulting trenches are filled epitaxially with Ge. For a proper filling and a good coverage at the interface between Ge and SiO2 a certain overgrowth of the Ge layer is required. Ge-STI CMP is needed to planarize and to smoothen the Ge surface. In this paper we present the results achieved with slurry developed specifically for Ge-STI CMP. Good planarity, low amount of defects and excellent smoothness were achieved. The need for an endpoint control of the CMP process was highlighted. Keywords: planarization, chemical-mechanical polishing, Ge, high mobility channel, slurry