Vertical SCR ESD Layout With Split Buried Layer Tradeoff Control
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Solution Overview
Problem
Conventional high-voltage electrostatic discharge (ESD) devices face a tradeoff between high current performance and high holding voltage, typically providing either one but not both, which can lead to damage of integrated circuits during ESD stress.
Innovation Solution
A high-voltage ESD device structure comprising a vertical silicon-controlled rectifier (SCR) and vertical NPN device, connected through a buried n+ layer split by a p+ isolation region, which enhances both current performance and holding voltage by increasing resistance and optimizing device configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-voltage ESD device structures are used, then either high current performance or high holding voltage can be achieved, but not both simultaneously
Solution Approach 1:
The device is segmented into distinct functional regions: a first SCR structure (anode, n-well, p-substrate) and a second SCR structure (cathode, n-well, p-substrate), connected through shared buried layers. This segmentation allows independent optimization of each SCR for its specific function while achieving both high current performance and high holding voltage at the device level.
Solution Approach 2:
Two SCR structures are merged into a single integrated device, sharing common n+ buried layers and p-substrate regions. The first SCR handles high-voltage blocking while the second SCR manages current discharge, and their combination through shared buried layers enables simultaneous achievement of high holding voltage and high current performance that neither structure could achieve alone.
2Reliability
If high voltage PNP structure is used, then high holding voltage control is provided, but high current performance is not achieved
Solution Approach 1:
The n+ buried layers serve multiple functions: they act as the cathode for the first SCR (enabling high-voltage blocking), the anode for the second SCR (enabling current discharge), and provide electrical connection between the two SCR structures. This multi-functionality allows a single structural element to support both high holding voltage control and high current performance.
3Productivity
If low voltage/high voltage SCR structure is used, then high current performance is provided, but high holding voltage control is not achieved
Solution Approach 1:
Different regions of the device have specialized doping characteristics optimized for their specific functions: the first n-well has doping concentrated near the anode for high-voltage blocking, while the second n-well has doping concentrated near the cathode for current discharge. This local quality differentiation enables each region to excel at its specific task while contributing to overall device performance.
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 proposed structure achieves high current performance and high holding voltage, while also saving chip area, effectively protecting integrated circuits from ESD stress and improving device reliability.
Implementation Method 1
enhances both current performance and holding voltage by increasing resistance
Implementation Method 2
Electrostatic discharge (ESD) devices protect integrated circuits from the sudden flow of electricity
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to high-voltage electrostatic discharge (ESD) devices and methods of manufacture. The structure includes a vertical silicon-controlled rectifier (SCR) connecting to an anode, and includes a buried layer of a first dopant type in electrical contact with an underlying buried layer a second dopant type split with an isolation region of the first dopant type within a substrate.