The figure above shows a Chip-to-Wafer concept that unites micromachined silicon sensors (top chip, shown as a transparent block) with a microelectronic chip (bottom). Within the ultra-small hermetic cavity between the chips, a getter film (black layer) covers the ASIC surface and provides a lifetime vacuum inside the package. This allows the sensor's proof mass to operate in a resonant mode with controlled damping. The chip stack is protected against fracturing by a wafer molding process. Through-silicon vias redistribute all contacts to solder balls on the backside, thus forming a chip-scale system in a package.