Wafer-Level Magnetic Sensor Testing Using Segmented Coils
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Solution Overview
Problem
Testing multi-axis magnetic field sensors requires large coils to generate uniform magnetic fields, leading to increased electricity consumption and longer testing times, especially when testing sensors on wafers or in packages, where separate devices and sequential testing are necessary.
Innovation Solution
A method and apparatus using a ring-shaped coil with a smaller cross-sectional area than the wafer, positioning the magnetic field sensor away from the coil's center, and applying magnetic field lines at an angle less than 90 degrees to achieve similar X, Y, and Z axis components with a single coil, reducing the number of coils and electricity needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large coils are used to generate uniform magnetic fields for testing multi-axis magnetic field sensors, then the magnetic field uniformity is improved, but the electricity consumption increases and the device complexity increases
Solution Approach 1:
The patent divides the wafer into multiple regions, with each region having a dedicated smaller coil. This segmentation allows each coil to generate a uniform magnetic field locally without requiring a single large coil to cover the entire wafer, thereby reducing overall electricity consumption while maintaining magnetic field uniformity in each testing region.
Solution Approach 2:
The patent applies local quality by using smaller coils positioned at specific locations on the wafer to generate magnetic fields tailored to local sensing regions. Each coil is optimized for its specific location, creating uniform magnetic fields only where needed, which reduces the total energy required compared to using one large coil for the entire wafer surface.
2Measurement precision
If separate devices and sequential testing are used for testing magnetic field sensors in packages, then the testing accuracy is improved, but the testing time increases and the productivity decreases
Solution Approach 1:
The patent merges multiple testing functions into a single integrated wafer-level testing system. Multiple magnetic field sensors on the wafer are tested simultaneously using multiple smaller coils that can be activated concurrently, eliminating the need for sequential testing with separate devices. This combining approach maintains testing accuracy while dramatically improving productivity by testing all sensors in parallel.
Solution Approach 2:
The patent creates a universal testing apparatus that can test multiple types of magnetic field sensors (including multi-axis sensors) on a single wafer platform. The system uses a standardized array of coils that can generate magnetic fields in multiple directions, allowing one testing device to perform multiple testing functions that previously required separate specialized devices.
3Area of stationary object
If coils larger than the wafer are used to test Z-axis direction, then the magnetic field coverage is improved, but the device complexity and cost increase
Solution Approach 1:
The patent solves the Z-axis testing problem by changing the dimensional approach. Instead of using a single large coil above the wafer, the patent embeds multiple smaller coils within the wafer plane at different angular orientations. These in-plane coils generate magnetic field components that, when combined, provide full three-dimensional including Z-axis coverage. This dimensional reconfiguration reduces coil size and complexity while maintaining comprehensive magnetic field coverage.
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 approach allows for efficient testing of multi-axis magnetic field sensors with reduced electricity consumption and shorter testing times, while minimizing the number of coils and costs, by generating effective magnetic fields across all axes using a single coil.
Implementation Method 1
arranging a coil configured to generate a magnetic field on the wafer; applying the magnetic field to the magnetic field sensor using the coil
Data Source
AI summary
An apparatus and a method for testing a magnetic field sensor are provided, in which the method includes arranging a coil for generating a magnetic field, applying the magnetic field to the magnetic field sensor using the coil, and detecting the magnetic field applied to the magnetic field sensor.