InvenSense is leading the creation of the next-generation of MEMS motion processing technologies for the consumer electronics (CE) market. Today, many CE products have started to adopt the use of motion sensing products primarily based on 3-axis MEMS accelerometers. These motion sensors have limited functionality and are used to detect very basic motions such as portrait versus landscape in the Apple iPhone™, or to detect a movement to trigger a function in a game, such as the Nintendo Wii™. InvenSense technology is bringing to market the next generation in motion sensing called, “motion processing”.
Motion processing provides a true 1:1 motion sensing capability that surpasses the current solutions in performance and functionality by allowing the development of the next generation of more immersive gaming solutions, such as the Wii MotionPlus™, development of gesture based handsets, 3D remote controls, and many other innovative consumer applications.
Motion processing technology is fundamentally based on the adoption of a new generation of vibrating mass MEMS rate sensors, commonly called gyroscopes. Yet until the advent of InvenSense integrated gyroscopes, it was not mechanically feasible or economically possible for mainstream CE products to incorporate traditional gyroscope designs, which were costly, bulky, and fragile.
InvenSense has pioneered the development of multi-axis rate sensor gyroscopes that were specifically designed from the outset to meet the market requirements of handheld CE products. The Company introduced the world’s first dual-axis high performance gyroscope in 2006, and in 2007, set a new industry benchmark for the smallest dual-axis gyroscope targeting CE applications, as shown in the photo.
InvenSense consistently provides “world’s first” MEMS solutions through its unique and patented Nasiri-Fabrication platform. This key technology enables direct integration of MEMS to integrated circuit electronics through wafer level bonding, achieving both a MEMS hermetically sealed vacuum package and direct electrical interconnections between the MEMS and CMOS wafers.
A single wafer bonding process utilizes existing aluminum from standard CMOS to achieve a hermetic seal on thousands of devices while simultaneously providing hundreds of thousands of electrical interconnects between the MEMS sensing electrodes and CMOS electronics (see photo). This creates cost and performance advantages for InvenSense versus its competition. Alternative approaches are more costly and inefficient, including the addition of a silicon cap with a glass-frit seal, residual gas getters for vacuum reliability, hermetically sealed ceramic packages, and multi-chip assembly of the MEMS and CMOS at the package level. Furthermore, additional cost advantages are derived from the simple 6-mask bulk silicon Nasiri-Fabrication process, which enables high-speed calibration and electrically integrated MEMS system-level testing.
Another key enabling technological advantage for InvenSense is its patented, out-of-plane resonating structures, which are the cornerstone of a vibrating, dual-mass, tuning fork design that surpasses the competition by its ability to serve the low-cost consumer electronics market.
Vibratory mass gyros are based on the transfer of energy between the two resonating modes of a structure due to Coriolis acceleration, which arises in a rotating reference frame, and is proportional to the rate of rotation. Vibratory mass gyros generally contain a pair of vibrating masses that are driven to oscillation with equal magnitude and in opposite directions. When the gyro device is rotated, the Coriolis force creates an orthogonal vibration force proportional to the rate of rotation, which is measured using capacitive sensing techniques.
Nasiri-Fabrication is protected by numerous patents and leverages innovative MEMS fabrication technology, proven bulk silicon processes, and low-cost, wafer-level packaging and integration techniques to achieve very low-cost, single-chip motion processing solutions.
Nasiri-Fabrication supports a wide range of MEMS devices including gyroscopes, accelerometers, rotation sensors, actuators, and potentially many other MEMS devices. This process is particularly suitable for MEMS capacitive sensing types or devices requiring actuators. Unlike many MEMS inertial sensor manufacturers that must go through interconnects and wire bonds to a companion chip, the Nasiri-Fabrication process directly bonds the MEMS to the CMOS allowing for direct electrical interconnection between the MEMS and its appropriate CMOS circuits. Though the process uses off-the-shelf wafer bonding equipment, the bonding technology itself is patented and proprietary, allowing for eutectic bonding of the MEMS wafers to the aluminum layer on the CMOS wafer without the addition of any other layers on the aluminum. Nasiri-Fabrication reduces wafer-scale integration and packaging to a single step in the process, setting the industry’s benchmark for its combined small size, high performance, robustness and low cost. The process streamlines wafer-scale packaging and provides a full hermetic sealing of the sensitive MEMS structures, resulting in high temperature and humidity resistance.
The Nasiri-Fabrication process has been ported to several high volume MEMS foundries, and has been ramped for large volume production without the typical constraints of competing gyroscope technologies.
