Single-Chip Two-Axis Magnetic Sensor Using Permanent Magnet Biasing
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Solution Overview
Problem
Current magnetic sensors face challenges such as excessive size, inadequate sensitivity, and manufacturing difficulties, particularly in producing high-sensitivity two-axis magnetic field sensors compatible with semiconductor devices and integrated circuits, with issues related to yield and magnetoresistive response matching.
Innovation Solution
A single-chip two-axis magnetic field sensor design utilizing tunneling magnetoresistance (TMR) or giant magnetoresistance (GMR) elements on a semiconductor substrate, with permanent magnets creating bias fields to stabilize sensitivity and magnetization direction, allowing for orthogonal sensing axes without requiring special processing like local magnetic annealing or multiple magnetic layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple discrete magnetic field sensors are used to measure different spatial components, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple magnetic field sensor elements (first and second bridge-type magnetic field sensors) into a single integrated sensor unit that can measure multiple spatial components (x and y directions) simultaneously. This merging approach maintains the measurement precision of multiple sensors while reducing device complexity by integrating them into one compact structure with shared components.
Solution Approach 2:
The integrated magnetic field sensor achieves multi-functionality by enabling measurement of magnetic field components in multiple spatial directions (x and y axes) using a single sensor device. The sensor structure allows it to perform multiple measurement functions that would traditionally require separate discrete sensors, thereby reducing overall system complexity while maintaining comprehensive measurement capability.
2Measurement precision
If discrete magnetic field sensors are used, then measurement capability is improved, but manufacturing cost increases
Solution Approach 1:
By merging multiple sensor functions into a single integrated device, the patent reduces the total number of components that need to be manufactured and assembled. This integration lowers manufacturing costs through reduced material usage, simplified production processes, and decreased assembly requirements, while still delivering the measurement capability of multiple discrete sensors.
3Power
If bridge-type magnetic field sensors are used, then output signal is improved, but device complexity increases
Solution Approach 1:
The patent integrates multiple bridge-type magnetic field sensor elements into a single device, maintaining the high output signal characteristics of bridge-type sensors while reducing overall device complexity through shared structural components and integrated design. The merged structure allows multiple sensing elements to work together without requiring separate complex assemblies for each.
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
Enables mass production of sensitive, cost-effective, and reliable two-axis magnetic field sensors with improved sensitivity and stability, integrated into a single semiconductor chip, addressing yield and manufacturing challenges while maintaining low power consumption.
Implementation Method 1
the magnetic field sensor (100) is configured to measure spatial components of a magnetic field vector
Data Source
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AI summary
The present invention discloses a design for a single-chip dual-axis magnetic field sensor, based on magnetic tunnel junction (MTJ) elements and permanent magnets integrated on a semiconductor substrate to produce two types of sensor bridges that detect orthogonal magnetic field components. The orthogonal magnetic field component detection capability results from the different types of sensor bridges that can be produced by varying the shape of the MTJ elements and the bias fields that can be created by permanent magnets. Because the permanent magnets can create orthogonal bias fields on the different sensor bridges, it is possible to use a single pinned layer to set direction for both sensor bridges. This is advantageous because it permits the two-axis sensor to be fabricated on a single semiconductor chip without the need for specialized processing technology such as local heating, or deposition of multiple magnetoresistive films with different pinned layers setting directions