Magnetic-Field Angle Sensor Fabrication to Reduce Orthogonality Drift
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Solution Overview
Problem
Angle errors due to orthogonality drift in magnetic-field angle sensors are significant, particularly at reduced magnetic fields, affecting the accuracy of magnetic-field angle sensors.
Innovation Solution
A method involving the rotation of a substrate during multiple depositions of magnetic material layers and application of magnetic fields during annealing to reduce anisotropy effects in antiferromagnetic and ferromagnetic materials, thereby minimizing orthogonality errors between sine and cosine bridges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional angle sensor fabrication is used, then manufacturing simplicity is maintained, but orthogonality errors exceed 0.25° at magnetic fields below 300 Oersted
Solution Approach 1:
The patent applies preliminary action by performing wafer rotation during material deposition and magnetic annealing before the sensor operates. This pre-treatment establishes the desired magnetic anisotropy orientation in the MR elements, ensuring orthogonality is maintained during low-field operation. The rotation and annealing steps prepare the magnetic material properties in advance to prevent orthogonality drift during use.
Solution Approach 2:
The patent changes physical parameters during fabrication by rotating the wafer at specific angles (e.g., 45 degrees) during magnetic material deposition and applying magnetic fields during annealing. These parameter changes in deposition geometry and thermal-magnetic treatment modify the magnetic anisotropy of the MR elements, reducing orthogonality errors to less than 0.25° at low magnetic fields.
2Object-affected harmful factors
If magnetic field strength is reduced to improve safety or compatibility, then application safety is improved, but orthogonality errors increase significantly
Solution Approach 1:
The patent uses preliminary action by pre-configuring the magnetic anisotropy orientation of MR elements through controlled wafer rotation and magnetic annealing during fabrication. This preliminary setup ensures that the sensors maintain accurate orthogonality even when operated at reduced magnetic field strengths, allowing safe low-field operation without sacrificing measurement accuracy.
Solution Approach 2:
The patent changes the magnetic anisotropy parameters of the MR elements during fabrication by applying magnetic fields during annealing and controlling deposition angles. This modifies the magnetic material properties so that the sensors remain accurate at low operating magnetic fields (below 300 Oersted), enabling safe operation without significant orthogonality errors.
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
Significantly reduces orthogonality errors to less than 0.25° for magnetic fields below 300 Oersted, enhancing the accuracy and precision of magnetic-field angle sensors.
Implementation Method 1
A magnetic-field sensing element is used to describe a variety of electronic elements that can sense a magnetic field. The magnetic-field sensing element can be, but is not limited to, a Hall Effect element, a magnetoresistance (MR) element, or a magnetotransistor.
Implementation Method 2
The magnetic-field sensing element can be, but is not limited to, a Hall Effect element, a magnetoresistance (MR) element, or a magnetotransistor.
Implementation Method 3
A method involving the rotation of a substrate during multiple depositions of magnetic material layers
Implementation Method 4
application of magnetic fields during annealing to reduce anisotropy effects in antiferromagnetic and ferromagnetic materials
Data Source
AI summary
In one aspect, a method includes manufacturing a magnetic-field angle sensor on a wafer. The manufacturing includes forming a cosine bridge that includes forming a first magnetoresistance (MR) element. The manufacturing also includes forming a sine bridge that includes forming a second MR element. Forming the first MR element includes using a process to reduce orthogonality errors between the sine bridge and the cosine bridge caused by anisotropy present in magnetic material in the first MR element.