3DS (3D System) MEMS Inertial Sensor Platform: Navigation Grade, Multi-Axis 3DoF MEMs Accelerometer
ABSTRACT
MEI Micro has developed a proprietary MEMS design and fabrication platform that supports the large volume manufacture of a wide range of commercial MEMS devices, including chip-scale, multi-axis accelerometers, gyros and combo inertial sensors capable of tactical to navigation grade performance. The architecture supports quick photomask changes to enable a wide range of scale factors and frequencies to support applications from sensitive medical measurements through position, navigation and timing (PNT) related applications, to high g and vibration measurement. The platform also supports the in-chip integration of additional non-inertial sensor designs such as pressure, magnetometer, and time of flight (ToF) sensors to enable a single chip inertial navigation system (INS). Additionally, the MEMS is hermetically sealed at the wafer level, enabling further 3D integration with CMOS or other sensor technologies. In the field of PNT, this includes the integration of GNSS and LEO receivers and MEMs timing chips leading to the development of an integrated “core” of any assured PNT system. It’s the size and cost of the core of any A-PNT solution which has limited the widespread use of A-PNT solutions especially when CSWaP (Cost, Size, Weight and Power) is a big factor in deciding on what solution to use.
The key proprietary features of the 3DS MEMs process platform architecture include the inclusion of full-wafer-thickness inertial masses and large planar electrodes for low thermomechanical noise and high sensitivity. Additionally, MEI Micro’s proprietary 3D TCVs (Through-Chip-Vias) were developed to route drive and sense signals throughout the chip to bond pads on either cap while maintaining hermeticity. This solved the problem of the inability of TSVs (Through-Silicon-Vias) to enable the type of hermicity required for the enabling advanced packaging approach leading to new performance levels yet to be achieved by MEMs inertial sensors produced at a large volume capable MEMs foundry. It also enabled, for the first time, this type of performance from a device that was capable of multiple axis operation.
The initial sensor design implemented in the platform is a single chip 6 DoF (Degrees of Freedom) IMU (multi-axis gyro and accelerometer combo sensor). In this talk we will describe the 3DS platform and initial 6 DoF IMU design. We will also describe the first product from the platform, a single proof mass navigation-grade 3 Axis Accelerometer, an industry first. The IMU consists of a 7.7 x 7.7 mm chip which includes both a 3-axis accelerometer and 3-axis gyroscope monolithically fabricated, photolithographically aligned, and vacuum sealed at the wafer level. The MEMS IMU is integrated with analog electronics and a customized FPGA into a small (42 mm x 42 mm x 20 mm) package with a 29-bit SPI interface that enables the IMU to be repurposed for multiple applications, including an EDGE device which can serve as the core of any assured position, navigation and timing (A-PNT) or guidance, navigation and control (GNC) system or subsystem. The accelerometer has a range of +/-10 g and scale factor around 300 mV/g with a bias instability as low as 5 ug. Scale factor linearity measured using a 1 g tumble testing is about 0.5% across 1 g. The scale factor temperature coefficient is very linear, on the order of 0.02 g/deg C, and can be compensated with digital electronics. The 3DS architecture not only provides low noise and high sensitivity but also provides a built-in shock resistance. The bare MEMS has been shock-tested to 14,000 g without industry standard protective packaging and has withstood radiation doses up to 2 Mrad leading to a unique and unmatched vibration, shock and radiation profile.
BIOGRAPHY
Louis Ross has over 25 years industry experience in strategy, operations, business development and IP management and valuation. As a startup company founder, he has managed several commercial MEMS/Microsystems foundry R&D and commercialisation projects in the US, Japan, Europe, Canada and Asia focused on MEMS inertial sensor systems. Prior to his career in technology development and commercialization, Louis was a senior executive, emerging technology analyst, and strategist/portfolio manager in the investment banking, private equity and management consulting industries. He continues to act as expert in identifying disruptive emerging technologies for direct equity investment and commercialisation. Louis is a co-inventor on 8 US and foreign patents and applications pertaining to MEMS inertial sensor systems and applications.
Louis received his BA, Economics from Rollins College, a master's in finance/MBA from Johns Hopkins University, studied intensive Japanese at Keio University (Tokyo) and was a post-graduate research fellow at The University of Tokyo's Faculty of Law (Commercial/Finance & Intellectual Property Law).