Integration of IC technology with MEMS: silicon+ technology for the future

As silicon microelectronics continues its remarkable evolution, the technology is simultaneously scaling to smaller geometries and diversifying into new device types and associated novel application areas. Recent examples of this diversification include smart power (integration of power devices with microelectronics), RF systems (integration of other semiconductor technologies such as SiGe, GaAs and passives with CMOS), microsystems (integration of a wide range of MEMS devices and sensors with CMOS), microdisplays (liquid crystal, light emitting polymers on silicon), bioelectronics (lab on a chip) and silicon photonics (integration of optical components on a silicon platform). All of these diverse Silicon+ technologies have one particular feature in common, namely the use of silicon as a platform for system integration with the added value being the innovation associated with post-processing and/or integration, which in many cases will be on standard foundry technology. The attraction of silicon as a platform technology arises from its dominance as a high performance and cost effective microelectronics technology. It is highly probable that Silicon+ will become the mainstream silicon research direction when scaling has run its course and hits a combination of technological and economic barriers. One vision of Silicon+ is that it effectively treats the platform silicon integrated circuit (IC) technology as a commodity element of the system, and with much of mainstream CMOS being foundry based, the value added part becomes the bespoke processing and the associated IP. One of the attractions of this approach is that state-of-the-art CMOS technology is readily available without the need for any capital investment and so the potential exists for SMEs and startup companies to readily exploit any IC/device technology that is developed. Another appeal is that as foundry-processes are updated the technology is immediately accessible making this element of any technology/product development future proofed without the requirement for any capital investment. This paper will examine the options associated with integrating both foundry and custom IC technology with both new materials and other technologies such as MEMS (sensors and actuators) and present examples of the various options.