Hall Sensor STI Depletion Shielding for Reduced Noise
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Solution Overview
Problem
Existing Hall sensors suffer from reduced efficiency due to non-symmetry between well contacts, which is exacerbated by current spinning techniques, leading to increased noise levels and decreased performance.
Innovation Solution
The implementation of shallow trench isolation (STI) structures between well contacts, combined with implants of opposite conductivity type, creates depletion regions that shield electron current from defects and trapped charges, enhancing symmetry and reducing noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If well contacts are formed with higher doping concentration to improve electrical connections, then current carrying capability is improved, but symmetry between well contacts is degraded, reducing offset cancellation efficiency
Solution Approach 1:
Shallow trench isolation (STI) structures are introduced as intermediary elements between adjacent well contacts. These STI structures act as mediators that electrically isolate the well contacts from each other while maintaining their individual doping concentrations and electrical connection qualities, thereby preventing symmetry degradation without compromising electrical connection performance
Solution Approach 2:
The semiconductor substrate is segmented into distinct regions by introducing STI structures that physically separate adjacent well contacts. This segmentation allows each well contact to maintain its optimal doping concentration for electrical connections while the STI structures prevent unwanted electrical interaction, preserving overall device symmetry
2Manufacturing precision
If shallow trench isolation structures are introduced to improve symmetry between well contacts, then offset cancellation efficiency is improved, but noise level increases due to charged trapping in dielectric material
Solution Approach 1:
The harmful effect of charged trapping in STI dielectric material is converted into a beneficial effect by strategically positioning depletion regions. The depletion regions, formed by implanting carriers of opposite conductivity type adjacent to the STI structures, actively counteract the noise caused by trapped charges, transforming the harmful STI presence into a beneficial noise-reduction mechanism
Solution Approach 2:
Depletion regions are pre-formed by implanting carriers of opposite conductivity type adjacent to the STI structures before final device operation. These depletion regions serve as preliminary anti-action against the noise-generating trapped charges in the STI dielectric, neutralizing their harmful effects before they can manifest as noise
3Productivity
If device footprint is reduced to improve integration density, then manufacturing efficiency is improved, but maintaining symmetry between well contacts becomes more difficult
Solution Approach 1:
The problem of maintaining symmetry in compact layouts is solved by utilizing the vertical dimension through shallow trench isolation structures that extend into the substrate. This three-dimensional approach allows well contacts to be closely spaced in the planar view while the STI structures provide the necessary electrical isolation and symmetry maintenance in the vertical profile, enabling high integration density without sacrificing symmetry
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 results in Hall sensors with improved symmetry and reduced noise levels, enabling more accurate and sensitive magnetic field measurements with a smaller device footprint.
Implementation Method 1
Hall sensors are magnetic field sensors which are based on the Hall effect and provide an electrical output signal which is indicative for a predetermined component of a magnetic field
Implementation Method 2
an implant of a second conductivity type, opposite to the first conductivity type, is present on sides of the shallow trench isolation regions such that the Hall sensor comprises a depletion region comprising: a first subregion between the implant on the sides of the shallow trench isolation regions and the electrically conductive well
Data Source
AI summary
A semiconductor chip includes at least one Hall sensor. The at least one Hall sensor includes: an electrically conductive well with a first conductivity type in a semiconductor substrate; a plurality of well contacts arranged at a surface of the electrically conductive well, and having the first conductivity type; a plurality of shallow trench isolation regions which are delimiting the well contacts at the surface of the electrically conductive well. An implant of a second conductivity type, opposite to the first conductivity type, is present on sides of the shallow trench isolation regions such that the Hall sensor comprises a depletion region including: a first subregion between the implant and the electrically conductive well, and a second subregion between the implant and the well contact.