Diode String Circuit Leakage Reduction via Segmented Doped Regions
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Solution Overview
Problem
Current electrostatic discharge (ESD) devices with diode string circuits face increased leakage current due to parasitic bipolar junction transistors and require complex manufacturing processes, such as deep N-well, leading to larger layout areas and higher costs.
Innovation Solution
A diode structure is designed with a substrate, insulating layers, a well, and deep doped regions of different conductivity types, allowing for electrical isolation and reducing leakage current, while enabling diode strings to be fabricated in the same well without additional masks or complex processes, thus minimizing layout area and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode string circuit is implemented using conventional structures, then ESD protection function is provided, but leakage current increases due to parasitic bipolar junction transistors
Solution Approach 1:
The patent divides the doped regions into multiple segments: a first doped region, a second doped region, and a deep doped region. This segmentation breaks the continuous doped path that would form parasitic BJT structures, thereby reducing leakage current while maintaining ESD protection functionality through the diode string circuit.
Solution Approach 2:
The deep doped region acts as an intermediary element between the first and second doped regions. It provides electrical isolation that prevents the formation of parasitic BJT structures, thereby reducing leakage current while still allowing the diode string to function for ESD protection.
2Reliability
If deep N-well process is used to implement diode string circuit, then electrical isolation is improved, but layout area and manufacturing cost increase
Solution Approach 1:
The patent merges multiple diode structures into a single well region. By sharing the well infrastructure among multiple diodes in the string circuit, the layout area is reduced compared to implementing each diode with separate deep N-well structures, while still achieving the necessary electrical isolation through the deep doped region configuration.
Solution Approach 2:
The well structure serves multiple functions: it provides mechanical support, electrical isolation, and a common substrate for multiple doped regions. This multi-functionality eliminates the need for additional deep N-well processes for each diode, reducing both layout area and manufacturing complexity.
3Reliability
If deep N-well process is used to implement diode string circuit, then electrical isolation is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines the electrical isolation function with the existing well structure, eliminating the need for separate deep N-well processes. The deep doped region within the well provides the necessary isolation, simplifying the manufacturing process while maintaining reliability.
Solution Approach 2:
The well structure itself provides the electrical isolation function through its inherent properties and the configuration of doped regions within it. This self-service approach eliminates the need for additional complex manufacturing processes specifically dedicated to electrical isolation.
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 significantly reduces leakage current and manufacturing costs by allowing diode strings to be integrated in a single well, optimizing device parameters like threshold voltage and breakdown voltage, and preventing unnecessary power consumption.
Implementation Method 1
The second doped region is disposed on the deep doped region, and is electrically isolated from the well through the deep doped region and the first doped region
Data Source
AI summary
A diode includes a substrate, a first insulating layer, a second insulating layer, a well, a deep doped region, a first doped region, and a second doped region. The first insulating layer is disposed on the substrate. The second insulating layer is disposed on the substrate, and defines a cell region with the first insulating layer. The well is disposed on the substrate and beneath the cell region. The deep doped region is disposed in the well and beneath the cell region. The first doped region is disposed in the cell region and on the deep doped region. The second doped region is disposed adjacent to the first doped region. The second doped region is disposed on the deep doped region, and is electrically isolated from the well through the deep doped region and the first doped region.