ESD Device Trigger Voltage Reduction via Segmented Doping
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Solution Overview
Problem
Existing ESD devices fail to protect internal circuits from electrostatic discharge due to trigger voltage being higher than the operation voltage of output drivers, leading to potential damage during high-voltage operations.
Innovation Solution
The ESD device design is modified by incorporating a deep doped well and an inserted doping well of a second conductive type, creating additional resistance paths that reduce the trigger voltage and provide an additional discharging path, allowing the ESD device to be triggered before the output driver is damaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ESD device is designed with conventional structure, then it can provide basic ESD protection, but the trigger voltage is higher than the maximum operation voltage level of the internal circuit device, causing the ESD device to fail to trigger before the output driver is damaged
Solution Approach 1:
The drain structure is segmented into multiple regions: a drain doped well, an inserted doping well of opposite conductive type, and a drain region. This segmentation creates multiple resistance paths that work together to reduce the trigger voltage while maintaining protection capability.
Solution Approach 2:
The inserted doping well is strategically placed within the drain doped well to create localized regions of opposite conductive type. This local modification of electrical properties creates additional resistance paths that reduce the overall trigger voltage without compromising the global protection function.
2Reliability
If the ESD device trigger voltage is reduced to protect low voltage internal circuits, then the protection capability is improved, but the device complexity increases due to additional doped wells and regions
Solution Approach 1:
The ESD device structure is merged with the existing output driver structure, sharing common regions such as the substrate, doped wells, and gate structure. This integration allows the ESD protection function to be added without completely redesigning the output driver, thereby reducing overall device complexity.
Solution Approach 2:
The output driver structure serves dual functions: normal circuit operation and ESD protection. The same doped wells and regions are used for both the output driver's switching function and the ESD device's protection function, eliminating the need for separate dedicated ESD protection structures.
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 modified ESD device effectively reduces the trigger voltage, ensuring that the ESD current is directed to ground instead of the internal circuit, thereby enhancing protection capabilities for circuits with low operation voltage levels.
Implementation Method 1
incorporating a deep doped well and an inserted doping well of a second conductive type, creating additional resistance paths that reduce the trigger voltage
Implementation Method 2
When an ESD current enters the input/output terminal, the ESD device is triggered in conducting state to lead the ESD current to the system power source, such as the ground voltage (VSS)
Data Source
AI summary
An electrostatic discharge device includes a substrate. A deep doped well of a first conductive type is disposed in the substrate. A drain doped well of the first conductive type is disposed in the substrate above the deep doped well. An inserted doping well of a second conductive type is disposed in the drain doped well, in contact with the deep doped well. A drain region of the first conductive type is in the drain doped well and above the inserted doping well. An inserted drain of the second conductive type is on the inserted doping well and surrounded by the drain region. A source doped well of the second conductive type is disposed in the substrate, abut the drain doped well. A source region is disposed in the source doped well. A gate structure is disposed on the substrate between the drain region and the source region.