Concentric BJT Layout for High-Voltage Substrate Leakage Analysis
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Solution Overview
Problem
High-voltage bipolar junction transistors (BJTs) experience substrate leakage and breakdown voltage limitations, affecting nearby devices in integrated circuits.
Innovation Solution
A semiconductor device with a concentric pattern of doped regions and ring-shaped isolations is designed, featuring point symmetry around the emitter, allowing easy characterization of current leakage into the substrate by capturing currents at different locations and modeling the relationship between current and distance from the emitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-voltage bipolar junction transistor is used, then breakdown voltage is improved, but substrate leakage increases
Solution Approach 1:
An n-type buried layer is introduced as an intermediary between the p-type substrate and the collector region. This buried layer acts as a mediator that blocks substrate leakage current while maintaining the high breakdown voltage capability of the BJT structure.
Solution Approach 2:
The patent applies different doping types and concentrations to different regions: the buried layer has high n-type doping concentration to block leakage, while the collector and emitter regions maintain their specific doping profiles for high voltage operation. This local differentiation of material properties resolves the contradiction between breakdown voltage and substrate leakage.
2Object-affected harmful factors
If the distance between BJT and other devices is increased, then substrate leakage impact is reduced, but device area increases
Solution Approach 1:
The n-type buried layer serves as a localized intermediary that confines substrate leakage current directly at the BJT location, eliminating the need for increased spacing to other devices. This allows compact integration while preventing leakage propagation.
Solution Approach 2:
By changing the doping parameters of the buried layer (high n-type concentration), the patent modifies the electrical properties of the substrate region to actively block leakage current, replacing the passive solution of increased physical distance with an active material property modification.
Data Source
AI summary
A semiconductor device includes an emitter, a first base encircling the emitter, a first collector encircling the emitter and the first base, a second base encircling the emitter, the first base and the first collector, and a second collector encircling the second base. The first collector is separated from the emitter by the first base, and the second collector is separated from the emitter, the first base and the first collector by the second base. The emitter, the first base, the first collector, the second base and the second collector form a concentric pattern.