High-Voltage Tub Layout With Floating Poly Trenches for Breakdown Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices face challenges in maintaining effective isolation breakdown voltage as component density increases, leading to variations in breakdown voltages and reduced manufacturing yields, while also being costly and inefficient with current trench-based isolation techniques.
Innovation Solution
The implementation of high voltage tub structures with electrically-shorted concentric deep trench isolation rings, which separate and define an outer conductive well ring shorted to an inner conductive well region, optimizing breakdown voltages and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trench-based isolation techniques are used to electrically isolate adjacent regions, then isolation effectiveness is improved, but manufacturing cost increases and breakdown voltage varies across the die
Solution Approach 1:
The patent divides the isolation structure into multiple concentric trenches (first trench, second trench, third trench) with different filling materials and electrical connections. This segmentation allows each trench to serve a specific function: the first trench provides primary isolation, the second trench enhances isolation with different material properties, and the third trench provides additional isolation layer. This segmented approach achieves superior isolation effectiveness while enabling more controlled and cost-effective manufacturing compared to uniform deep trench isolation.
2Productivity
If component density is increased to improve productivity, then components per unit area increase, but breakdown voltage distribution varies and manufacturing yield decreases
Solution Approach 1:
The patent applies different filling materials and electrical connection strategies to different trenches based on their specific isolation requirements. The first trench may be filled with conductive material and connected to a specific potential, the second trench filled with different material properties, and the third trench providing additional isolation. This local differentiation of isolation structures allows the patent to maintain consistent breakdown voltage characteristics even as component density increases, because each local isolation region is optimized for its specific function.
3Reliability
If deeper trenches are used to improve isolation, then isolation breakdown voltage is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent implements a nested trench structure where the first trench, second trench, and third trench are arranged concentrically with one another. The first trench is positioned at a first depth, the second trench at a second depth, and the third trench at a third depth, creating a nested configuration. This nesting approach provides enhanced isolation breakdown voltage because multiple trenches work together to block electrical breakdown paths, while the concentric arrangement maintains manufacturing simplicity by using standard circular patterning techniques rather than requiring complex three-dimensional trench geometries.
Data Source
AI summary
A method and apparatus are disclosed for an integrated circuit having a high voltage tub including a buried layer of a first conductivity type formed in a substrate of a second conductivity type, a central region of the first conductivity type formed in the substrate in contact with the buried layer, a first floating isolation trench formed in the substrate to surround the central region and to extend down to and surround the buried layer, a second floating isolation trench formed in the substrate around the first isolation trench, a shallow ring region of the first conductivity type formed in the substrate between the first floating isolation trench and the second floating isolation trench, a first conductive interconnect structure for electrically shorting the central region to the shallow ring region, and a second conductive interconnect structure for electrically shorting the first floating isolation trench to the second floating isolation trench.