Integrated Hall Sensor Multi-Winding Coils for Uniform Calibration
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Solution Overview
Problem
Existing Hall sensors face challenges in achieving a uniform and homogeneous magnetic field for testing and calibration, particularly for vertical Hall sensors, due to limitations in coil efficiency and self-heating issues, which are critical for accurate calibration and testing.
Innovation Solution
The integration of CMOS-compatible processes forms a multi-winding coil configuration around the Hall sensor elements, ensuring a homogeneous magnetic field is induced within the Hall plate, using through silicon vias and multiple metal layers to connect coils in series, thereby enhancing coil efficiency and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single integrated coil is used for Hall sensor testing, then the device complexity is reduced, but the magnetic field uniformity and coil efficiency deteriorate
Solution Approach 1:
The integrated coil is divided into multiple windings (first winding, second winding, third winding, fourth winding) arranged in a specific pattern around the Hall sensor. This segmentation allows each winding to contribute to creating a uniform magnetic field in the measurement region, resolving the contradiction between simple structure and field uniformity.
Solution Approach 2:
The coil windings are positioned asymmetrically at different distances from the Hall sensor surface, with specific windings placed closer and others farther away. This asymmetric arrangement optimizes the magnetic field distribution and uniformity in the measurement region while maintaining a relatively simple integrated structure.
2Force
If higher coil current is applied to increase magnetic field strength, then the magnetic field strength is improved, but self-heating increases
Solution Approach 1:
The coil is segmented into multiple windings that can be connected in series, allowing the total resistance to be higher for the same current. This enables achieving the required magnetic field strength with lower current, thereby reducing self-heating effects during sensor calibration.
Solution Approach 2:
Instead of increasing current magnitude in one dimension, the solution distributes the magnetic field generation across multiple spatial dimensions by using multiple windings at different positions and orientations, achieving the required field strength through geometric arrangement rather than current increase.
3Productivity
If maximum coil current is used during calibration, then the calibration speed is improved, but electromigration performance deteriorates
Solution Approach 1:
The coil is divided into multiple series-connected windings, which increases the total resistance and allows calibration to be performed at lower currents. This maintains acceptable calibration speed while significantly improving electromigration performance and long-term reliability of the CMOS metal layers.
4Loss of energy
If through silicon vias and multiple metal layers are used to connect coils in series, then the coil efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The coil windings are integrated into the existing CMOS metallization structure, merging the coil function with the standard manufacturing process. Through silicon vias and metal layers are utilized as part of the normal CMOS fabrication sequence, so the additional complexity is minimal and leverages existing process capabilities.
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 configuration allows for effective testing and calibration of Hall sensors by ensuring a uniform magnetic field, reducing self-heating, and improving the accuracy and efficiency of the calibration process.
Implementation Method 1
The integration of CMOS-compatible processes forms a multi-winding coil configuration around the Hall sensor elements, ensuring a homogeneous magnetic field is induced within the Hall plate
Implementation Method 2
Magnetic sensor ICs (Integrated Circuits) typically use silicon-based Hall sensor elements which are monolithically integrated with the electrical circuits required for signal conditioning and amplification
Data Source
AI summary
An integrated Hall sensor is provided with: a main wafer (10) of semiconductor material having a substrate (101) with a first surface (101a) and a second surface (101b), opposite to the first surface (101a) along a vertical axis (y); Hall sensor terminals (1, 2, 3, 4; 1′, 2′, 3′, 4′) arranged at least one of the first and second surfaces (101a, 101b) of the substrate (101); an isolation structure (109) in the substrate (101) defining a Hall sensor plate (103) of the integrated Hall sensor, the Hall sensor terminals being arranged in the isolation structure (109). The integrated Hall sensor moreover has a test or calibration coil integrated in the wafer (10), having a plurality of windings formed, at least in part, by metal portions (130b, 170b; 130a, 170a) arranged above the first and second surfaces (101a, 101b) of the substrate (101) and defining an inner volume (1001) entirely enclosing the Hall sensor plate (103).