Coplanar Magnetoresistive Sensor with Integrated Set/Reset Strap
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Solution Overview
Problem
Existing magnetic-field sensors with anisotropic magnetoresistive elements require multiple straps for set/reset and offset compensation, complicating manufacturing and increasing costs, especially for multi-axis sensors, and do not allow for optimal scaling down due to geometrical anisotropy limitations.
Innovation Solution
A magnetoresistive sensor design where all magnetoresistive elements are coplanar and formed during a single deposition step, with their easy axis oriented orthogonally to the axes of sensitivity, allowing a single planar strap to perform both set/reset and offset compensation operations, and optimizing the sensor's geometry for improved sensitivity and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple straps are used for set/reset and offset compensation, then the sensor functionality is complete, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the set/reset strap and offset strap into a single integrated strap structure. This single strap performs both set/reset operations and offset compensation operations, thereby reducing manufacturing complexity while maintaining complete sensor functionality. The unified strap design eliminates the need for separate straps that would otherwise be required to perform these distinct functions.
Solution Approach 2:
The single strap is designed with multi-functionality, serving as both the set/reset strap and the offset strap. By making the strap universal, it can perform multiple operations (set, reset, and offset compensation) that would traditionally require separate dedicated components, thus reducing overall device complexity while preserving all necessary sensor functions.
2Reliability
If multiple straps are used for set/reset and offset compensation, then the sensor functionality is complete, but the production cost increases
Solution Approach 1:
The patent merges the set/reset strap and offset strap into a single integrated strap structure. This single strap performs both set/reset operations and offset compensation operations, thereby reducing manufacturing complexity while maintaining complete sensor functionality. The unified strap design eliminates the need for separate straps that would otherwise be required to perform these distinct functions.
3Device complexity
If traditional geometrical anisotropy is used, then the sensor structure is simple, but the scaling down to smaller dimensions is limited
Solution Approach 1:
The patent changes the geometric parameters of the magnetoresistive elements by orienting their easy axis perpendicular to the sensitivity axis, rather than parallel to it. This parameter change in the orientation of magnetic anisotropy enables the sensor to achieve high sensitivity while being scalable to smaller dimensions, overcoming the limitations of traditional geometrical anisotropy configurations.
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 simplifies the manufacturing process, reduces production costs, and enables the creation of compact, high-sensitivity sensors with dimensions smaller than 0.7×0.7 mm2, while maintaining efficient set/reset and calibration operations.
Implementation Method 1
the phenomenon of anisotropic magnetoresistivity occurs within particular ferromagnetic materials, which, when subjected to an external magnetic field, undergo a variation of resistivity according to the characteristics of the applied magnetic field
Implementation Method 2
designed to generate, when traversed by a current of appropriate value, a magnetic field that couples in a direction perpendicular to the direction of detection of the sensors
Implementation Method 3
the variation of the sense of magnetization is obtained by applying to the magnetoresistive element, via the set/reset strap, a magnetic field of appropriate value for a short period of time, such as to force arbitrarily the sense of the magnetic dipoles of the magnetoresistive element
Implementation Method 4
The magnetic field generated by the offset strap is such as to force partially the orientation of the magnetic dipoles of each magnetoresistive element in a second predefined direction
Implementation Method 5
the magnetic field generated by the offset strap is such as to force partially the orientation of the magnetic dipoles of each magnetoresistive element
Data Source
AI summary
A method of manufacturing a magnetic-field sensor includes forming an insulating layer on a first surface of a substrate. First and second magnetoresistors are formed at different above the first surface of the substrate and are spaced apart from the first surface by different distances. The first and second magnetoresistors have respective main axes of magnetization transverse to one another, and respective secondary axes of magnetization transverse to one another. The method further includes forming a first magnetic-field generator configured to generate a first magnetic field having field lines along the main axis of magnetization of the first magnetoresistor, and forming a second magnetic-field generator configured to generate a second magnetic field having field lines along the main axis of magnetization of the second magnetoresistor.