Vertical MTJ Sensor for In-Plane Magnetic Field Detection
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Solution Overview
Problem
Conventional magnetic-field sensors, being planar devices, exhibit low sensitivity when detecting magnetic fields parallel to their surface, limiting their effectiveness in sensing magnetic field directions.
Innovation Solution
A magnetic-tunnel-junction device structure is developed, comprising a first electrode, a pinned layer, a tunnel barrier layer, and a free layer, where the pinned layer's magnetization is fixed, and the free layer's magnetization can rotate in response to external magnetic fields, enhancing sensitivity by utilizing a Wheatstone bridge array configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional planar magnetic-field sensor structures are used, then manufacturing is simple, but sensitivity to in-plane magnetic fields is low
Solution Approach 1:
The patent transitions from conventional planar (2D) magnetic-field sensor structures to a three-dimensional vertical structure. The magnetic tunnel junction device is configured with pinned layer, tunnel barrier layer, and free layer stacked vertically, enabling the sensor to detect in-plane magnetic fields with high sensitivity by utilizing the vertical dimension for field detection rather than relying solely on planar geometry.
Solution Approach 2:
The patent employs composite material structures in the magnetic tunnel junction device, combining multiple functional layers including pinned layer, tunnel barrier layer, and free layer with distinct magnetic and electrical properties. This composite structure enables enhanced sensitivity to in-plane magnetic fields while maintaining manufacturability through established thin-film deposition techniques.
2Reliability
If planar magnetic-field sensor structures are used, then device fabrication is straightforward, but sensing margin is insufficient
Solution Approach 1:
By configuring the magnetic tunnel junction device with vertically stacked layers (pinned layer, tunnel barrier layer, free layer), the patent achieves enhanced sensing margin through three-dimensional geometry. This vertical configuration increases the interaction volume with in-plane magnetic fields, providing a larger sensing margin compared to conventional planar structures.
Solution Approach 2:
The patent utilizes changes in resistance state of the magnetic tunnel junction device in response to magnetic field variations. The tunnel barrier layer's resistance changes significantly when the free layer's magnetization rotates due to external magnetic fields, providing a large electrical signal output that enhances the sensing margin and reliability of the sensor.
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
The magnetic-tunnel-junction device structure significantly improves sensitivity to in-plane magnetic fields, allowing for accurate detection of magnetic field directions with increased sensing margin through resistance state changes.
Implementation Method 1
a tunnel barrier layer between the free layer and the pinned layer
Data Source
AI summary
Structures including a magnetic-tunnel-junction device and methods of forming such structures. The structure comprises a magnetic-tunnel-junction device that includes a first electrode having a first sidewall, a second electrode having a second sidewall facing the first sidewall of the first electrode, a pinned layer adjacent to the first sidewall of the first electrode, a free layer adjacent to the second sidewall of the second electrode, and a tunnel barrier layer between the free layer and the pinned layer.