Shared Component Dual SCR for ESD Protection
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Solution Overview
Problem
Conventional silicon controlled rectifier (SCR) designs for high-speed differential inputs and outputs require significant area, leading to inefficiencies in electrostatic discharge (ESD) protection for integrated circuits, as they typically use two separate diode-triggered SCRs which occupy a large area and increase capacitive loading.
Innovation Solution
A bi-directional ESD structure is developed using a substrate with first and second silicon controlled rectifiers (SCRs) that share at least one component, such as an NPN collector, PNP base, or diode string trigger network, to create a compact dual SCR layout that minimizes device space while maintaining robust ESD protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate diode-triggered SCRs are used for high-speed differential inputs and outputs, then robust ESD protection is achieved, but device area increases significantly
Solution Approach 1:
The patent merges two separate SCR structures into a single integrated dual SCR device where the first and second SCRs share common components including a shared substrate region, shared contact structures, and shared doping regions. This consolidation maintains the protective function of two SCRs while reducing the overall device footprint by eliminating redundant structures.
Solution Approach 2:
The shared substrate region and contact structures serve multiple functions simultaneously - they provide the foundation for both the first SCR and the second SCR, and enable both devices to operate independently for differential ESD protection. This multi-functionality allows two protection circuits to coexist in a single integrated structure.
2Reliability
If two separate diode-triggered SCRs are used for high-speed differential inputs and outputs, then robust ESD protection is achieved, but capacitive loading increases
Solution Approach 1:
By combining the two SCR structures into a single integrated device with shared components, the total capacitance presented to the differential inputs is reduced compared to two separate devices. The shared contact structures and substrate regions eliminate redundant capacitance that would exist in separate implementations.
3Area of stationary object
If a compact SCR design is used, then device area is reduced by 40%, but ESD protection robustness may be compromised
Solution Approach 1:
The compact design achieves area reduction by merging two SCRs into one integrated structure. Despite the reduced footprint, the shared components are designed to maintain full ESD protection capability by preserving the essential functional elements of both SCRs.
Solution Approach 2:
The patent utilizes vertical integration and three-dimensional device architecture to accommodate two SCR structures in a reduced planar footprint. By stacking or overlapping device regions in the vertical dimension, the design achieves compactness without sacrificing the protective function of two SCRs.
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 shared component dual SCR design reduces device area by up to 40% compared to traditional dual SCR configurations, providing low capacitance loading and scalable on-resistance while effectively shunting ESD currents to ground, thus protecting differential driver/receiver circuits from damage.
Implementation Method 1
An ESD event refers to a phenomenon of electrical discharge of a current (positive or negative) for a short duration during which a large amount of current is provided to an integrated circuit (IC)
Implementation Method 2
An SCR can sustain high currents, hold the voltage across the SCR at a low level and may be implemented to bypass high current discharges associated with an ESD event
Data Source
AI summary
A structure includes first and second silicon controlled rectifiers (SCRs) formed in a substrate. The first and the second SCRs each include at least one component commonly shared between the first and the second SCRs.