3D MEMS Magnetometer Monolithic Integration
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Solution Overview
Problem
Current MEMS inertial sensors face challenges in achieving high accuracy due to mechanical noise and drift, particularly in applications requiring six-degree-of-freedom capability, where integrating three-axis magnetic field sensors is costly and impractical due to the need for additional material and fabrication steps.
Innovation Solution
A 3D MEMS magnetometer design that includes a MEMS wafer with orthogonal magnetic field transducers and electrode assemblies, allowing for simultaneous measurement of magnetic field components along three axes within a single chip, reducing material and fabrication costs by integrating the sensors at the wafer level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three separate magnetometers are used to measure three vector components of magnetic field, then measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines three separate magnetometer measurements into a single integrated sensor that measures all three vector components (Bx, By, Bz) simultaneously. The magnetic field sensor integrates multiple sensing elements in one device, eliminating the need for three separate magnetometers and reducing system complexity while maintaining full three-axis measurement capability.
Solution Approach 2:
The magnetic field sensor is designed as a multi-functional device that can measure all three components of the magnetic field vector using a single sensor element or integrated sensor array. This universal sensor performs the work of three specialized sensors, reducing overall device complexity while preserving complete measurement functionality.
2Measurement precision
If hybrid integration with separate magnetometer chip is used, then magnetic field sensing is achieved, but manufacturing cost and fabrication complexity increase
Solution Approach 1:
The patent merges the magnetic field sensing function directly into the MEMS inertial sensor fabrication process. Both the inertial measurement units and magnetic field sensors are manufactured using the same MEMS工艺流程, eliminating separate magnetometer chip attachment, adhesive bonding, and wire bonding steps. This monolithic integration dramatically simplifies manufacturing while maintaining sensing performance.
Solution Approach 2:
The MEMS fabrication process is designed to produce both inertial sensors and magnetic field sensors simultaneously using the same manufacturing techniques and equipment. This universal fabrication approach allows a single production line to manufacture multi-functional sensor packages without requiring separate specialized processes for magnetometer integration.
3Volume of moving object
If MEMS inertial sensors are used instead of traditional mechanical gyroscopes, then size is reduced, but mechanical noise and drift increase
Solution Approach 1:
The patent combines MEMS inertial sensors with magnetic field sensors in an integrated package to create a complementary system. The magnetic field sensor provides absolute orientation reference that compensates for the drift and accumulated error inherent in MEMS inertial sensors. This combination maintains the small size advantage of MEMS while improving overall measurement reliability through sensor fusion.
Solution Approach 2:
The magnetic field sensor acts as an intermediary reference system that corrects the drift and noise issues of MEMS inertial sensors. By providing an independent measurement of orientation based on the Earth's magnetic field, it serves as a mediator that stabilizes the overall navigation solution and reduces accumulated errors from inertial integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances accuracy and reduces costs by integrating three-axis magnetic field sensing within a single MEMS chip, addressing the limitations of existing MEMS inertial sensors by providing a compact and cost-effective solution for high-accuracy applications.
Implementation Method 1
first, second and third magnetic field transducers... configured to sense or measure first, second and third vector components of a magnetic field
Data Source
AI summary
A micro-electro-mechanical system (MEMS) magnetometer is provided for measuring magnetic field components along three orthogonal axes. The MEMS magnetometer includes a top cap wafer, a bottom cap wafer and a MEMS wafer having opposed top and bottom sides bonded respectively to the top and bottom cap wafers. The MEMS wafer includes a frame structure and current-carrying first, second and third magnetic field transducers. The top cap, bottom cap and MEMS wafer are electrically conductive and stacked along the third axis. The top cap wafer, bottom cap wafer and frame structure together form one or more cavities enclosing the magnetic field transducers. The MEMS magnetometer further includes first, second and third electrode assemblies, the first and second electrode assemblies being formed in the top and/or bottom cap wafers. Each electrode assembly is configured to sense an output of a respective magnetic field transducer induced by a respective magnetic field component.