Vertical Hall Element Buried Layer Magnetic Sensitivity
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Solution Overview
Problem
Vertical Hall elements formed in implanted wells have inherently low sensitivity to in-plane magnetic fields, and increasing sensitivity through well narrowing leads to higher electrical resistance, a trade-off that is undesirable.
Innovation Solution
A buried layer with a higher dopant concentration than the well region is introduced beneath the vertical Hall element, drawing biasing current deeper into the region of lower dopant concentration, thereby enhancing magnetic sensitivity without increasing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the well and well contact region are narrowed to increase sensitivity, then magnetic sensitivity is improved, but electrical resistance increases undesirably
Solution Approach 1:
The patent introduces a buried layer beneath the well region, extending the current path vertically into a third dimension. This allows the current to flow through regions of varying dopant concentration (from high at the surface to low deeper in the well), achieving higher sensitivity without narrowing the lateral dimensions of the well, thus avoiding the resistance penalty
Solution Approach 2:
The patent creates non-uniform dopant concentration distribution within the well region by introducing a buried layer with different doping characteristics. This allows different vertical regions of the well to have optimized properties: higher dopant concentration near the surface for lower resistance, and lower dopant concentration deeper in the well for higher Hall effect sensitivity
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 buried layer design achieves higher Hall effect sensitivity while maintaining lower electrical resistance, improving the detection of in-plane magnetic fields without the adverse resistance increase associated with previous sensitivity enhancements.
Implementation Method 1
this buried layer draws biasing current deeper into the region of the well where there is lower dopant concentration than near the surface. This region of lower concentration provides higher Hall effect sensitivity.
Data Source
AI summary
A vertical Hall element and method of fabricating are disclosed. The method includes forming a buried region having a first conductivity type in a substrate having a second conductivity type and implanting a dopant of the first conductivity type into a well region between the top surface of the substrate and the buried region. The buried region has a doping concentration increasing with an increasing depth from a top surface of the substrate and the well region has a doping concentration decreasing from the top surface of the substrate to the buried region. The method includes forming first through fifth contacts on the well region. First and second contacts define a conductive path and second and third contacts define another conductive path through the well region. The fourth contact is formed between first and second contacts and the fifth contact is formed between second and third contacts.