3D Coil Structure for Magnetic Sensor Linearity
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Solution Overview
Problem
Magnetic field sensors face challenges in achieving improved linearity and temperature behavior, as well as efficient magnetic field strength to power consumption ratios, particularly in replacing costly bias magnets and optimizing area consumption.
Innovation Solution
A three-dimensional coil structure surrounding a magnetic sense element is integrated on an active silicon substrate, enabling improved linearity and temperature behavior, and allowing for superior magnetic field strength to power consumption ratios, with on-chip signal modulation and self-test capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a three-dimensional coil structure is integrated on an active silicon substrate, then linearity and temperature behavior are improved, but device complexity increases
Solution Approach 1:
The coil structure is integrated within the silicon substrate by forming coil segments in different metal layers (first metal layer, second metal layer) and connecting them through vias. The magnetic sense element is surrounded by the coil structure in a nested configuration, with the coil winding around the magnetic sense element. This nesting approach achieves three-dimensional integration while maintaining a compact footprint on the substrate.
Solution Approach 2:
The patent transitions from planar two-dimensional coil structures to three-dimensional coil structures by utilizing multiple metal layers and vertical vias. The coil segments are formed in different layers (first metal layer, second metal layer) and connected vertically, creating a three-dimensional winding pattern that surrounds the magnetic sense element. This dimensional transition enables improved magnetic field generation and sensor performance.
2Ease of manufacture
If costly bias magnets are replaced with integrated coil structures, then manufacturing cost is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The coil structure and magnetic sense element are integrated on a single silicon substrate using standard semiconductor fabrication processes. The coil segments are formed in metal layers that are part of the standard CMOS process flow, and the magnetic sense element is fabricated using compatible semiconductor techniques. This merging of components eliminates the need for separate bias magnets and reduces assembly complexity.
Solution Approach 2:
The patent replaces mechanical/physical bias magnets with an electromagnetic coil structure that generates the required magnetic field through current flow. Instead of using permanent magnets or mechanical field sources, the system uses electrical current in the coil segments to generate the magnetic field needed for sensor operation. This substitution enables integration with electronic circuits and eliminates the need for external magnetic components.
3Area of stationary object
If area consumption is optimized through integration, then device footprint is reduced, but coil structure complexity increases
Solution Approach 1:
The coil structure is configured to wind around the magnetic sense element in a compact three-dimensional pattern. The coil segments in different metal layers are positioned to maximize spatial utilization, with inner and outer coil segments arranged to create an efficient winding pattern. This nested configuration achieves high integration density while maintaining a small footprint on the substrate.
Solution Approach 2:
The coil structure is divided into multiple segments formed in different metal layers (first coil segment in first metal layer, second coil segment in second metal layer). Each segment is independently patterned and connected through vias, allowing for optimized routing and reduced interference. This segmentation enables the complex three-dimensional coil structure to be fabricated using standard multi-layer metal processes.
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 three-dimensional coil structure enhances the integration of magnetic field sensors, reducing costs and area consumption while providing robust and efficient performance, enabling the replacement of costly bias magnets and improving sensor functionality.
Implementation Method 1
A magnetic field sensor system includes a coil structure and a magnetic sense element. The coil structure may be surrounded by the magnetic sense element, or the coil structure may surround the magnetic sense element.
Implementation Method 2
Magnetic field sensors may be based on semiconductor materials (e.g., Hall sensors, magnetoresistors, and so forth) and ferromagnetic materials (e.g., ferromagnetic magnetoresistors and flux guides).
Data Source
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AI summary
A method includes forming first coil segments in an electrically conductive layer on an active silicon substrate, forming a magnetic sense element over an electrically insulating layer being over the electrically conductive layer, the magnetic sense element being separated from the first coil segments in the electrically conductive layer by the electrically insulating layer. A protective layer is formed over the magnetic sense element. Conductive vias are formed extending through the protective layer and the electrically insulating layer to electrically couple with the first coil segments, and second coil segments are formed over the protective layer, the second coil segments electrically coupling with the conductive vias to produce a coil structure comprising the first coil segments, the conductive vias, and the second coil segments, with the coil structure surrounding the magnetic sense element.