  The majority of microelectromechanical system (MEMS) devices must be combined
with integrated circuits (ICs) for operation in larger electronic systems.
While MEMS transducers sense or control physical, optical or chemical
quantities, ICs typically provide functionalities related to the signals of
these transducers, such as analog-to-digital conversion, amplification,
filtering and information processing as well as communication between the MEMS
transducer and the outside world. Thus, the vast majority of commercial MEMS
products, such as accelerometers, gyroscopes and micro-mirror arrays, are
integrated and packaged together with ICs. There are a variety of possible
methods of integrating and packaging MEMS and IC components, and the technology
of choice strongly depends on the device, the field of application and the
commercial requirements. In this review paper, traditional as well as
innovative and emerging approaches to MEMS and IC integration are reviewed.
These include approaches based on the hybrid integration of multiple chips
(multi-chip solutions) as well as system-on-chip solutions based on wafer-level
monolithic integration and heterogeneous integration techniques. These are
important technological building blocks for the More-Than-Moore paradigm
described in the International Technology Roadmap for Semiconductors. In this
paper, the various approaches are categorized in a coherent manner, their
merits are discussed, and suitable application areas and implementations are
critically investigated. The implications of the different MEMS and IC
integration approaches for packaging, testing and final system costs are
reviewed.
