In this report, we'll also show that as MEMS moves from competing on process technology to competing on functions and systems, a move towards more standard solutions will be necessary to drive down package size and cost. Currently, MEMS foundries still compete at the process level and have to propose a wide range of processes in order to cope with new MEMS designs and structures. This approach differs from fabless companies, which usually focus on one type of MEMS design. Their main objective is to find the most experienced and reliable foundry partner in order to convince customers of their expertise. IDMs, meanwhile, generally rely on robust and established MEMS processes to manufacture their products (i.e. THELMA for ST). Foundries, which must always remain at the forefront of changes in the MEMS manufacturing landscape, have the biggest challenge.
TSV & UNIQUE WAFER STACKING SOLUTIONS ARE KEY ENABLERS FOR REDUCING DIE SIZE AND COST
MEMS Front-End Manufacturing Trends report highlights the major front-end manufacturing changes. For example, TSV for CSP is gradually seeping into the MEMS industry. To this end, we've analyzed STMicroelectronics' unique approach to making TSVs in its MEMS die in-house, in order to attach the die to the motherboard. This approach eliminates the area needed for the bond pads by replacing them with polysilicon vias isolated by etched-out air gaps, made with its basic MEMS process but on about a 10x larger scale. STM reports that the 20%-30% reduction in die size more than offsets the modest cost of the TSV process, resulting in a lower total cost.
However, since miniaturization will be limited, new detection principles are currently being developed at various R&D Institutes (i.e. Tronic's M&NEMS concept) in order to lower MEMS size at the silicon level. This technology is based on piezoresistive nanowires rather than pure capacitive detection, and is poised to be a leap forward in terms of device performance and chip size. This will set the stage for a new generation of combo sensors for Motion Sensing applications, achieving both significant surface reduction and performance improvement for multi-DOF sensors.Amongst the large array of MEMS technologies, we've identified several that will have the widest diffusion in the years to come.