Bi-Directional SCR Structure for SOI ESD Protection
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Solution Overview
Problem
Silicon controlled rectifiers (SCRs) in existing technologies face limitations in achieving high failure current and efficient electrostatic discharge (ESD) protection, particularly in semiconductor on insulator (SOI) technologies, where they often require improved area efficiency and reliability.
Innovation Solution
The proposed solution involves a bi-directional SCR structure with a symmetrical design comprising deep and shallow depth portions, separated by an intermediate depth portion with varying doping concentrations, and a buried insulator material, fabricated using integrated circuit technology techniques such as photolithographic processes and rapid thermal anneal, to enhance failure current and ESD protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SCR structures are used in SOI technology, then the device can perform basic current control function, but the failure current is limited and ESD protection capability is insufficient
Solution Approach 1:
The SCR structure is segmented into multiple distinct regions including a first well, second well, third well, and first diffusion region with different polarities. This segmentation creates multiple p-n-p-n layers that work together to enhance failure current and ESD protection while maintaining manageable structural complexity through systematic division of functional zones
Solution Approach 2:
Different regions of the SCR are assigned specific doping concentrations and polarities optimized for their local functions. The first diffusion region has same polarity as the third well and extends into first and second wells with varying doping concentrations, creating locally optimized electrical characteristics that collectively improve overall reliability and ESD protection
2Reliability
If the SCR structure is optimized for high failure current and ESD protection, then reliability improves, but the area efficiency may be compromised
Solution Approach 1:
Multiple functional elements including wells of different polarities and diffusion regions are merged into a single integrated SCR structure. This consolidation achieves high ESD protection capability within a compact footprint by combining isolation, current control, and protection functions in one unified device architecture
Solution Approach 2:
The SCR structure utilizes vertical dimensionality with wells extending at different depths and a diffusion region extending into multiple wells. This three-dimensional arrangement allows complex electrical characteristics and high ESD protection capability to be achieved without proportionally increasing the lateral device area
Data Source
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AI summary
The present disclosure relates to semiconductor structures and, more particularly, to silicon control rectifiers and methods of manufacture. The structure includes: a first well in a semiconductor substrate; a second well in the semiconductor substrate; a third well in the semiconductor substrate which isolates the first well from the second well; and a first diffusion region at a surface of the semiconductor substrate and which extends into the first well and the second well, the first diffusion region includes a same polarity as the third well.