SCR ESD Protection Layout for High Trigger Voltage
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Solution Overview
Problem
Conventional silicon controlled rectifier (SCR)-based electrostatic discharge protection devices have high trigger voltages but low holding voltages due to internal parasitic bipolar junction transistors, making it challenging to design devices that operate stably at high trigger voltages while maintaining current gain.
Innovation Solution
The design includes a substrate with specific conductivity type wells and diffusion regions arranged to form PNP and NPN transistors, allowing for efficient electrostatic discharge current discharge by adjusting the breakdown voltage through the arrangement of diffusion regions and wells, thereby maintaining high current gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the distance between the P-well and the N-well is increased to increase the trigger voltage, then the trigger voltage is improved, but the current gain decreases causing the device to not operate properly
Solution Approach 1:
The patent introduces intermediate diffusion regions (first, second, third diffusion regions) between the P-well and N-well, segmenting the breakdown path into multiple stages. This allows the trigger voltage to be distributed across several reverse breakdown junctions, achieving high trigger voltage without requiring a large single distance that would reduce current gain.
Solution Approach 2:
The intermediate diffusion regions act as mediators between the P-well and N-well. These regions enable reverse breakdown at controlled voltages, facilitating high trigger voltage operation while maintaining proper current gain through the distributed structure.
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 solution enables the electrostatic discharge protection device to operate effectively at high trigger voltages with improved current gain, efficiently discharging high-value ESD currents, addressing the limitations of conventional devices.
Implementation Method 1
An electrostatic discharge protection device that is a silicon controlled rectifier (SCR) (or thyristor) is triggered by the reverse breakdown between an N-well and a P-well
Data Source
AI summary
Disclosed is an electrostatic discharge protection device which includes a substrate including a first well having a first conductivity type and a second well surrounding the first well, first to fifth diffusion regions formed on the first well, and sixth and seventh diffusion regions formed on the second well. The second diffusion region surrounds the first diffusion region, the fourth diffusion region surrounds the fifth diffusion region, and the fifth diffusion region surrounds the second diffusion region and the fourth diffusion region. The sixth diffusion region surrounds the fifth diffusion region, and the seventh diffusion region surrounds the sixth diffusion region. The sixth and seventh diffusion regions are connected to an anode electrode, and the first to fifth diffusion regions are connected a cathode electrode.