Distributed ESD Protection Cells for CDM-Resistant Semiconductor I/O
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Solution Overview
Problem
In semiconductor devices, the input-logic circuit or internal circuit is prone to destruction due to potential differences during Electro-Static-Discharge (ESD) tests, particularly in Charged Device Model (CDM) tests, where the existing ESD protection circuits may not provide sufficient resistance, leading to potential breakdown.
Innovation Solution
The semiconductor device incorporates a small-area ESD protector with a bidirectional diode configuration between power supply and ground lines, ensuring high ESD resistance by distributing power supply cells and ESD protective circuits across the chip, forming efficient discharging paths to mitigate potential differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ESD protection circuit is used, then the circuit can provide basic ESD protection, but the protection area is large and the ESD resistance is insufficient
Solution Approach 1:
The ESD protection function is segmented into multiple power supply cells (first power supply cell, second power supply cell, third power supply cell, fourth power supply cell), each containing protection circuits distributed across different locations. This segmentation allows the protection function to be distributed rather than concentrated, reducing the area required for each individual protection circuit while maintaining overall ESD resistance through the combined effect of multiple segments.
Solution Approach 2:
The patent introduces bidirectional diodes connected between different ground lines (first ground line and second ground line) in addition to the conventional power supply to ground protection paths. This adds a new dimensional aspect to the ESD protection architecture, creating multiple discharge paths that operate in different electrical dimensions, thereby improving ESD resistance without requiring proportional increases in planar area.
2Area of stationary object
If the ESD protection circuit is made smaller, then the chip area is reduced, but the ESD resistance and protection capability deteriorate
Solution Approach 1:
Each power supply cell contains both power supply functionality and ESD protection functionality integrated together. The protection circuits and bidirectional diodes serve dual purposes: protecting against ESD events while also participating in the normal power supply distribution network. This multi-functionality allows the same structural elements to contribute to both area efficiency and ESD protection capability simultaneously.
Solution Approach 2:
The bidirectional diodes are pre-configured between ground lines to establish potential equalization paths before ESD events occur. During normal operation, these diodes are in standby, but they are already in place to immediately activate when ESD events create potential differences, providing preliminary protection readiness without requiring additional area during the protection event itself.
3Reliability
If protection circuits are added to multiple power supply cells, then ESD resistance is improved, but the device complexity increases
Solution Approach 1:
Each power supply cell is designed with identical local structure containing protection circuits and bidirectional diodes. This local quality uniformity means that the same design pattern is replicated across multiple cells, which actually reduces overall complexity through standardization rather than increasing it. Each local unit is simple and identical, making the complex multi-cell system manageable through modular repetition.
Solution Approach 2:
The protection circuits and bidirectional diodes are merged into the existing power supply cell structures rather than being added as separate external protection modules. By combining the ESD protection function with the power supply distribution function in the same structural units, the patent avoids the complexity that would arise from having separate protection modules, thereby improving ESD resistance while minimizing increases in device complexity.
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 the semiconductor device from ESD damage by reducing parasitic resistances and ensuring high ESD resistance, preventing breakdowns in both input/output and internal circuits during CDM tests.
Implementation Method 1
a bidirectional diode connected between the first ground line and the second ground line
Data Source
AI summary
A semiconductor device is provided. The semiconductor device includes an input/output cell, a core logic circuit, a first power supply cell, a second power supply cell, a third power supply cell and a fourth power supply cell. Each of the power supply cells includes a protection circuit and a bidirectional diode.