Multi-Voltage IC Isolation Structure for Leakage Blocking
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Solution Overview
Problem
Multi-voltage integrated circuits (ICs) face significant leakage current issues due to the use of isolating transistors, leading to undesirable shorting between active device regions.
Innovation Solution
The implementation of a multi-voltage IC structure with a trench isolation region and isolating transistors connected in series, biased to maintain an off state, effectively prevents leakage current and shorting between voltage domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If isolating transistors are used to electrically isolate active device regions, then IC size can be scaled down, but significant leakage current occurs between voltage domains
Solution Approach 1:
The isolation structure is segmented into multiple components: a trench isolation region extending through the semiconductor body, multiple isolating transistors distributed along the trench, and an insulator layer. This segmentation allows each component to contribute to isolation functionality while minimizing leakage current through distributed isolation rather than relying on a single transistor.
Solution Approach 2:
The trench isolation region filled with insulator material serves as an intermediary structure between active device regions at different voltage domains. The isolating transistors are positioned adjacent to the trench, using the trench as a physical barrier and reference structure, thereby reducing direct leakage paths between voltage domains while maintaining compact IC size.
2Ease of manufacture
If a single trench isolation structure is used, then manufacturing is simple, but isolation effectiveness between multiple voltage domains is insufficient
Solution Approach 1:
The isolation structure is segmented into multiple components: a trench isolation region extending through the semiconductor body, multiple isolating transistors distributed along the trench, and an insulator layer. This segmentation allows each component to contribute to isolation functionality while minimizing leakage current through distributed isolation rather than relying on a single transistor.
Solution Approach 2:
The trench isolation region serves multiple functions simultaneously: it provides physical separation between voltage domains, acts as a structural reference for positioning isolating transistors, and works in conjunction with the insulator layer to establish electrical isolation. This multi-functionality maintains manufacturing simplicity while enhancing isolation effectiveness across multiple voltage domains.
3Object-generated harmful factors
If isolating transistors are biased to maintain off state, then current blocking is achieved, but saturation threshold voltage increases and saturation drain current decreases
Solution Approach 1:
Instead of relying on a single isolating transistor that must be fully enhanced for isolation, the structure uses multiple isolating transistors distributed along the trench isolation region. Each transistor can operate with partial isolation responsibility, allowing them to maintain lower threshold voltages and higher drain currents while collectively providing sufficient isolation effectiveness through their distributed arrangement.
Data Source
AI summary
Disclosed are embodiments of an integrated circuit (IC) including a first IC section operating in a first voltage domain, a second IC section operating in a second voltage domain, and an isolation structure between the two sections. The isolation structure can include a trench isolation region within a semiconductor layer, isolating first PFETs and, optionally, isolating second PFETs. The isolating first PFETs can be series-connected and can include a first portion of the semiconductor layer between a functional PFET of the first IC section and a first edge of the trench isolation region. Additionally, the isolating first PFETs can operate in the first voltage domain and can be biased so as to remain always off. The isolating second PFETs can be similarly configured between a functional PFET of the second IC section and a second edge of the trench isolation region opposite the first edge.