Dielectric-Trench Hall Element Layout for Vertical Current Sensing
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Solution Overview
Problem
Existing Hall Effect elements often suffer from low sensitivity due to significant lateral current flow, which degrades the signal-to-noise ratio and reduces the effectiveness of magnetic field sensing.
Innovation Solution
The fabrication of Hall effect devices with increased trench depth in the epitaxial layer, filled with dielectric material, reduces lateral current flow and enhances vertical current flow, thereby increasing sensitivity to magnetic field changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional vertical Hall Effect element structure is used, then the device is simpler to manufacture, but lateral current flow reduces sensitivity and signal-to-noise ratio
Solution Approach 1:
The device is segmented into distinct regions: an epitaxial layer containing Hall effect elements, and a separate implantation layer for current injection. This segmentation allows independent optimization of each layer's function, enabling vertical current flow while maintaining manufacturing feasibility through standardized layering processes.
Solution Approach 2:
The invention transitions from planar current flow to vertical current flow by stacking the implantation layer beneath the epitaxial layer. This dimensional change forces current to flow perpendicular to the Hall effect elements, eliminating lateral current paths that cause sensitivity loss and improving the signal-to-noise ratio.
2Measurement precision
If trench depth is increased to reduce lateral current, then sensitivity improves, but manufacturing complexity and difficulty increase
Solution Approach 1:
The trench structure is formed preliminarily during the epitaxial growth process rather than as a separate post-processing step. The trench depth is predetermined by the epitaxial layer thickness, which is controlled through established semiconductor fabrication processes, thereby achieving deep trenches (greater than 1 micron) without requiring complex deep etching or precise depth control techniques.
Solution Approach 2:
The invention changes the controlling parameter for trench depth from etch depth control to epitaxial growth thickness control. By growing the epitaxial layer to a specific thickness that defines the trench depth, the manufacturing process leverages well-controlled deposition techniques rather than challenging etching processes, improving both precision and ease of manufacture.
3Measurement precision
If lateral current flow is allowed, then current distribution is more uniform, but sensitivity to magnetic field changes decreases
Solution Approach 1:
The harmful lateral current paths are extracted or removed from the current flow path by introducing dielectric material into trenches that extend vertically through the structure. This forces the current to flow exclusively in the vertical direction through the implantation layer, eliminating the competing lateral flow paths while maintaining efficient current delivery to the Hall effect elements.
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 increased trench depth improves the sensitivity and signal-to-noise ratio of Hall effect devices by enhancing vertical current flow and reducing lateral current flow, resulting in improved magnetic field sensing performance.
Implementation Method 1
Hall Effect elements that can sense a magnetic field are known
Implementation Method 2
a trench filled with a dielectric material and extending from a top surface of the epitaxial layer into the implantation layer
Data Source
AI summary
In one aspect, a Hall effect device includes an implantation layer; an epitaxial layer located above the implantation layer; a trench filled with a dielectric material and extending from a top surface of the epitaxial layer into the implantation layer and defining an enclosed region; a buried layer the epitaxial layer from the implantation layer within the enclosed region; and a contact pad located on the epitaxial layer. The trench reduces a current from the contact pad from traveling in a lateral direction orthogonal to a vertical direction and enables the current to travel in the vertical direction.