Bootstrap Diode Structure for High Breakdown and Low Leakage
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Solution Overview
Problem
Conventional bootstrap diodes fail to meet the requirements of high-voltage integrated circuit chips in terms of breakdown voltage and substrate leakage current.
Innovation Solution
An improved diode structure is designed with a substrate, multiple well regions, doped regions, and a specific configuration that includes a ring-shaped well region and buried layers to achieve high breakdown voltage and low substrate leakage current, suitable for high-voltage integrated circuit chips and integrated with BCD process fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bootstrap diode is used, then the device can be fabricated with simple structure, but the breakdown voltage is insufficient and substrate leakage current is high
Solution Approach 1:
The diode structure is segmented into multiple functional regions including a first well region with first doped region, a ring-shaped well region surrounding the first doped region, and a second well region with second doped region. This segmentation allows each region to contribute to different aspects of performance, achieving high breakdown voltage while maintaining low substrate leakage current.
Solution Approach 2:
The patent employs a nested structure where the ring-shaped well region surrounds the first doped region within the first well region, and the second doped region is positioned within the second well region. This nested arrangement optimizes space utilization and electrical field distribution, enabling high breakdown voltage without excessive device complexity.
2Reliability
If a conventional bootstrap diode is used, then the fabrication process is simple, but the substrate leakage current is high
Solution Approach 1:
Different regions of the diode structure are doped with different conductivity types and doping concentrations to optimize local electrical characteristics. The first well region contains a first doped region with one conductivity type, while the ring-shaped well region and second well region contain regions with opposite conductivity types. This local quality variation effectively suppresses substrate leakage current in critical areas.
Solution Approach 2:
The patent combines multiple well regions and doped regions into a single integrated diode structure that can be fabricated using the existing BCD process. By merging the high-voltage diode structure with transistor fabrication processes, the solution achieves low substrate leakage current without requiring a completely new fabrication methodology.
3Adaptability or versatility
If the diode structure is integrated with BCD process, then multi-functionality is achieved, but the device complexity increases
Solution Approach 1:
The diode structure is designed to be universal and compatible with the BCD fabrication process, allowing it to be integrated alongside bipolar junction transistors, CMOS transistors, and DMOS transistors. The same process steps used to create transistor structures can also form the diode's well regions and doped regions, enabling multi-functionality in a single fabrication run.
Data Source
AI summary
A diode structure includes a substrate having a first conductivity type, a first well region having a second conductivity type opposite to the first conductivity type and disposed in the substrate, a first doped region having the first conductivity type and disposed in the first well region, a ring-shaped well region having the second conductivity type, disposed in the first well region and surrounding the first doped region, an anode disposed on the first doped region, a second well region having the second conductivity type, separated from the first well region and disposed in the substrate, a second doped region having the second conductivity type and disposed in the second well region, and a cathode disposed on the second doped region.