Hall Sensor STI Depletion Structure for Low-Noise Measurement
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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
Implementing shallow trench isolation (STI) structures around well contacts and incorporating implants of opposite conductivity type to create depletion regions, shielding electron current from defects and trapped charges, thereby enhancing symmetry and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If well contacts are formed by creating regions with higher doping concentration, then electrical connections are established, but non-symmetry is introduced between well contacts, decreasing efficiency of current spinning and offset cancellation
Solution Approach 1:
The patent segments the well contact formation process into two distinct parts: (1) forming the well contact region with higher doping concentration to establish electrical connection, and (2) forming shallow trench isolation regions with opposite conductivity type adjacent to the well contact. This segmentation allows each part to fulfill its specific function independently, resolving the contradiction between electrical connection and symmetry.
Solution Approach 2:
The patent applies local quality by creating different conductivity types in different locations: the well contact region has one conductivity type for electrical connection, while the adjacent shallow trench isolation regions have opposite conductivity type to provide symmetry and shield from noise. This localized differentiation resolves the contradiction by assigning different properties to different spatial regions.
2Manufacturing precision
If shallow trench isolation regions are used to delimit well contacts, then symmetry between well contacts is increased, but noise level increases due to charged trapping in dielectric material
Solution Approach 1:
The patent introduces an intermediary structure - the shallow trench isolation regions with opposite conductivity type - that acts as a mediator between the well contact and the surrounding environment. These isolation regions provide the necessary symmetry while simultaneously shielding the electron current from defects and trapped charges in the dielectric material, thus reducing noise. The intermediary structure resolves the contradiction by providing both symmetry and noise reduction.
Solution Approach 2:
The patent converts the potentially harmful effect of charged trapping in dielectric material into a beneficial outcome. By placing shallow trench isolation regions with opposite conductivity type adjacent to the well contact, the structure utilizes the dielectric material in a controlled manner to create symmetry and depletion regions that shield against noise, transforming the potential harm into a benefit for both symmetry and noise reduction.
3Measurement precision
If current spinning technique is used for offset cancellation, then offset is reduced, but efficiency decreases due to non-symmetry between well contacts
Solution Approach 1:
The patent segments the well contact structure into symmetric components by adding shallow trench isolation regions with opposite conductivity type adjacent to each well contact. This segmentation creates a symmetric overall structure that restores efficiency to the current spinning technique while maintaining offset cancellation capability, resolving the contradiction between measurement precision and productivity.
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 solution results in Hall sensors with improved symmetry and reduced noise levels, enabling more accurate magnetic field measurements and offset cancellation.
Implementation Method 1
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, and a second subregion between the implant on the sides of the shallow trench isolation regions and the well contact
Implementation Method 2
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
Data Source
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AI summary
A semiconductor chip (100) comprising at least one Hall sensor (110). The at least one Hall sensor (110) comprises: an electrically conductive well (111) with a first conductivity type in a semiconductor substrate; a plurality of well contacts (114) arranged at a surface of the electrically conductive well (111), and having the first conductivity type; a plurality of shallow trench isolation regions (113) which are delimiting the well contacts (114) at the surface of the electrically conductive well (111). An implant (112) of a second conductivity type, opposite to the first conductivity type, is present on sides of the shallow trench isolation regions (113) such that the Hall sensor (110) comprises a depletion region comprising: a first subregion (115a) between the implant (112) and the electrically conductive well (111), and a second subregion (115b) between the implant (112) and the well contact (114).