Magnetic Sensor Support Geometry for MR Thickness Uniformity
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Solution Overview
Problem
Magnetoresistive elements formed on curved surfaces experience significant thickness variations due to manufacturing process precision issues, leading to inconsistent performance characteristics.
Innovation Solution
A magnetic sensor design with a support member that includes an inclined portion with varying angles and curvatures to minimize thickness changes of the magnetoresistive element, ensuring consistent resistance changes with external magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the magnetoresistive element is formed on a curved surface to detect magnetic fields, then the sensor can detect magnetic fields with components perpendicular to the substrate surface, but the thickness of the magnetoresistive element varies significantly due to manufacturing precision issues
Solution Approach 1:
The support member is designed with a curved surface that has varying inclination angles at different locations. Specifically, the inclination angle is smaller at the position where the magnetoresistive element is formed compared to other positions. This local variation in surface geometry compensates for the thickness reduction effect during non-conformal film formation, ensuring more uniform thickness of the magnetoresistive element while maintaining the curved surface configuration needed for magnetic field detection.
2Shape
If non-conformal film formation is used to create the curved surface, then the magnetoresistive element can be formed on the curved surface, but the thickness decreases as the inclination angle increases
Solution Approach 1:
The invention changes the geometric parameters of the support member's curved surface by controlling the inclination angle to be smaller at the magnetoresistive element formation position. This parameter modification optimizes the thickness distribution of the magnetoresistive element formed through non-conformal film formation, preventing excessive thickness reduction while maintaining the desired curved surface shape for magnetic field detection.
3Ease of manufacture
If the photoresist mask position varies due to photolithography precision limits, then manufacturing is simplified, but the thickness of the magnetoresistive element changes greatly near the edge
Solution Approach 1:
The support member is pre-designed with a curved surface where the inclination angle is specifically made smaller at the magnetoresistive element formation position. This preliminary geometric configuration counteracts the thickness reduction effect that would otherwise occur due to photoresist mask position variations during photolithography, thereby maintaining thickness consistency even when manufacturing precision varies.
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
Reduces thickness variations of the magnetoresistive element, enhancing the sensor's performance stability and reliability.
Implementation Method 1
a magnetoresistive element whose resistance changes with an external magnetic field
Data Source
AI summary
A magnetic sensor includes an MR element and a support member. The support member has an opposed surface including a first inclined portion, and a bottom surface. In a given cross section, the first inclined portion is inclined at a first angle at a first position, and inclined at a second angle smaller than the first angle at a second position. The absolute value of a curvature of the first inclined portion at the first position is less than the absolute value of the curvature of the first inclined portion at the second position. The MR element is provided on the first inclined portion so that the first edge is located above the first position in a given cross section.