Deep Trench Isolation With Segmented Punch-Through Structures
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Solution Overview
Problem
Conventional deep trench isolation structures face challenges in maintaining adequate breakdown voltage as component density increases, leading to reduced isolation voltage capability and manufacturing yield, especially under high-temperature operating conditions.
Innovation Solution
The implementation of a deep trench isolation structure with multiple punch-through structures and isolation trench rings around the isolated region, which helps to distribute the electrical potential more evenly and reduce the burden on weak points, thereby enhancing the breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If component density is increased to improve device integration, then productivity is improved, but isolation breakdown voltage deteriorates
Solution Approach 1:
The isolation structure is segmented into multiple punch-through structures (first, second, and third punch-through structures) distributed around the isolated region. This segmentation allows the isolation function to be distributed across multiple points, maintaining adequate breakdown voltage even as component density increases and trench spacing decreases.
Solution Approach 2:
Different regions around the isolated region receive different isolation structures. Punch-through structures are strategically placed at specific locations (e.g., corners and midpoints of sides) where electrical stress is highest. This local quality approach ensures that critical areas have enhanced isolation capability while maintaining overall high component density.
2Ease of manufacture
If conventional deep trench isolation is used to maintain isolation, then manufacturing complexity is reduced, but isolation breakdown voltage deteriorates under high-temperature conditions
Solution Approach 1:
The isolation structure is divided into multiple discrete punch-through structures rather than relying on a single continuous trench. Each punch-through structure can be formed using standard semiconductor fabrication processes, making the segmented approach compatible with existing manufacturing capabilities while improving isolation performance.
Solution Approach 2:
The punch-through structures are nested within or around the deep trench isolation structure. The first, second, and third punch-through structures are positioned at different locations and depths, creating a nested configuration that enhances isolation without requiring completely new manufacturing processes.
3Productivity
If component density is increased, then productivity is improved, but distribution of breakdown voltages widens leading to lower manufacturing yields
Solution Approach 1:
By segmenting the isolation into multiple punch-through structures, the electrical stress is distributed across multiple isolation points rather than concentrating at single trench locations. This segmentation reduces the variation in breakdown voltage across different locations on the wafer, narrowing the distribution and improving manufacturing yield.
Solution Approach 2:
The multiple punch-through structures are designed to create more uniform electrical potential distribution around the isolated region. By placing structures at strategic locations (corners and midpoints), the equipotentiality is improved, reducing hot spots and minimizing breakdown voltage variation across the device.
Data Source
AI summary
An integrated semiconductor device includes a substrate of a first conductivity type, a buried layer located over the substrate, an isolated region located over a first portion of the buried layer, and an isolation trench located around the isolated region. A punch-through structure is located around at least a portion of the isolation trench. The punch-through structure includes a second portion of the buried layer, a first region located over the second portion of the buried layer, the first region having a second conductivity type, and a second region located over the first region, the second region having the first conductivity type.