Smart inertial sensor systems, e.g. gyroscope clusters, are basically formed by a MEMS device with micromachined structures and an ASIC with drive- and sense-circuits. Integration is moving towards a direct interconnect by chip stacking to form a chip-scale system in a package. As an alternative to a Wafer-to-Wafer bonding approach, a Chip-to-Wafer (C2W) assembly can reduce initial product launch costs and thus target for smaller or more innovative market segments. The present work addresses specific aspects related to particle management, singulation of open MEMS and a two-step C2W bonding approach. A short outlook on additional steps to form a MEMS chip-scale package is provided.