Perpendicular SCR Trigger and Discharge Paths
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Solution Overview
Problem
FinFET transistors are susceptible to damage from high ESD currents due to extreme heating, which can permanently damage the gate oxide and N+ region, and they are not ideal for discharge devices despite being suitable for triggering due to their small size and high turn-on resistance.
Innovation Solution
Implementing a Silicon-Controlled Rectifier (SCR) structure with FinFET devices aligned in a horizontal direction for triggering and vertical substrate-based discharge paths, allowing perpendicular current flow to prevent overheating of FinFET fins, and optimizing trigger and discharge currents separately to achieve low turn-on resistance without harming the FinFET transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If FinFET transistors are used for ESD discharge devices, then device size is reduced and power consumption is lowered, but the transistors are damaged by extreme heating from high ESD currents
Solution Approach 1:
The ESD protection circuit is segmented into two distinct functional paths: a trigger path using FinFET transistors and a discharge path using a separate SCR structure. This segmentation allows each component to be optimized for its specific function, preventing the FinFET from being damaged by high discharge currents while still benefiting from its size and power advantages in the trigger function.
Solution Approach 2:
The SCR structure acts as an intermediary between the FinFET trigger and the high-current ESD discharge path. The FinFET triggers the SCR, which then handles the high-current discharge, protecting the FinFET from direct exposure to damaging ESD currents while enabling effective ESD protection.
2Reliability
If high ESD currents are shunted through FinFET transistors, then ESD protection is provided, but extreme heating damages the gate oxide and N+ region
Solution Approach 1:
The current paths are segmented into trigger and discharge paths. The discharge path is routed through the SCR structure which is designed to handle high currents, while the FinFET trigger path handles only the small trigger current, preventing excessive heating in the FinFET.
Solution Approach 2:
The harmful high-current discharge function is extracted from the FinFET transistor and placed into a dedicated SCR discharge structure. This extraction removes the source of extreme heating from the FinFET while preserving the ESD protection function.
3Device complexity
If trigger and discharge functions are combined in a single transistor, then device complexity is reduced, but the transistor cannot simultaneously optimize for both low power and high current handling
Solution Approach 1:
The ESD protection device is segmented into distinct trigger and discharge components with separate current paths. This allows each component to be independently optimized for its specific function while working together as an integrated ESD protection system.
Solution Approach 2:
The SCR structure serves multiple functions: it acts as the discharge device for high-current ESD events and also provides the trigger mechanism through its internal transistor. This multi-functionality reduces the need for separate components while maintaining optimization for both low-power triggering and high-current discharge.
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
This configuration effectively protects FinFET devices from ESD damage by separating trigger and discharge current paths, ensuring low resistance and fast triggering while preventing overheating, thus enhancing the reliability of ESD protection circuits in both FinFET and planar processes.
Implementation Method 1
Implementing a Silicon-Controlled Rectifier (SCR) structure with FinFET devices aligned in a horizontal direction for triggering and vertical substrate-based discharge paths, allowing perpendicular current flow to prevent overheating of FinFET fins
Implementation Method 2
Gate 52 is formed around the channel connecting region. Rather than being flat, gate 52 has an inverted U-shape that surrounds the channel connecting region between N+ regions 42, 44.
Data Source
AI summary
An Electro-Static-Discharge (ESD) protection circuit has a Silicon-Controlled Rectifier (SCR) with a discharge current path in a first direction. A triggering transistor has a trigger current flowing in a second direction that is perpendicular to the first direction. Triggering transistors can be Fin Field-Effect Transistor (FinFET) transistors with current flowing along the long direction of the fins. The trigger current flows into a connecting N+ drain and into an N-Well under a center portion of the connecting N+ drain to inject carriers into the N-base of a PNPN SCR. The injected current flows through the base to generate a voltage gradient that turns on the PN junction in a P+ emitter that is parallel to but spaced apart from the FinFET transistors, causing a discharge current to flow perpendicular to the fins. The perpendicular discharge current flows through the substrate which can handle a larger current than the small fins.