Semiconductor Isolation Trench for Parasitic PNPN Suppression
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Solution Overview
Problem
In semiconductor structures, particularly in switching regulators, the parasitic PNPN thyristor can turn on due to uncontrolled internal currents during the freewheeling process of the reverse body diode, leading to potential failure, which is challenging to prevent without a large isolation area.
Innovation Solution
Incorporating an isolation component in the semiconductor substrate with a trench structure doped with N-type or P-type polysilicon, which recombines and extracts carriers, thereby preventing the flow of carriers between regions and reducing the overall area required for isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large isolation area is used to prevent parasitic PNPN thyristor turn-on, then reliability is improved, but device area increases
Solution Approach 1:
The patent changes the electrical parameters of the isolation component by introducing doped regions with specific doping types and concentrations. The first doped region has a first doping type and concentration, while the second doped region has a second doping type and concentration, creating electrical isolation that prevents parasitic thyristor turn-on without requiring large physical area.
Solution Approach 2:
The isolation component uses composite doped regions within the semiconductor substrate. By combining regions with different doping types (n-type and p-type) and concentrations, the structure creates effective electrical isolation barriers that block carrier flow and prevent parasitic thyristor activation while maintaining compact dimensions.
2Ease of manufacture
If conventional isolation structures are used, then manufacturing is simple, but carrier flow between regions cannot be effectively controlled
Solution Approach 1:
The patent applies local quality by creating doped regions with specific doping types and concentrations at precise locations within the isolation component. The first doped region and second doped region have different doping characteristics tailored to their specific positions, enabling effective carrier flow control in different areas of the isolation structure.
Solution Approach 2:
The isolation component is segmented into multiple doped regions (first doped region and second doped region) with different doping types and concentrations. This segmentation allows independent optimization of carrier blocking characteristics in different areas, effectively preventing parasitic thyristor turn-on while maintaining manufacturing feasibility.
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 isolation component effectively prevents the parasitic PNPN thyristor from turning on by recombining and extracting carriers, thereby enhancing the reliability and reducing the area needed for isolation in semiconductor structures.
Implementation Method 1
The isolation component recombines carriers flowing from the first region toward the second region and extracts carriers flowing from the second region toward the first region
Implementation Method 2
The isolation component may be electrically connected to an isolation electrode receiving a predetermined electric potential such that when carriers flow through the isolation component, most carriers are extracted to the isolated electrode and discharged
Data Source
AI summary
A semiconductor structure can include: a semiconductor substrate having a first region, a second region, and an isolation region disposed between the first region and the second region; an isolation component located in the isolation region; and where the isolation component is configured to recombine first carriers flowing from the first region toward the second region, and to extract second carriers flowing from the second region toward the first region.