Electrostatic Discharge Protection Circuit Layout Area Reduction
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Solution Overview
Problem
Conventional electrostatic discharge protection circuits for semiconductor memory devices have limited driving ability and increased layout area due to the use of diode chains and resistors, which affects their effectiveness in managing static electricity discharge.
Innovation Solution
The proposed electrostatic discharge protection circuit incorporates multiple electrostatic protection units with diodes and MOS transistors to create multiple discharge paths between power and ground voltage lines, enhancing discharge performance while reducing the layout area by optimizing the placement and function of these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diode chains and resistors are used to enhance the driving ability of NMOS transistor, then the electrostatic discharge performance is improved, but the layout area is increased
Solution Approach 1:
The patent merges the functions of multiple electrostatic discharge protection devices into a single integrated circuit block. Instead of separately implementing diode chains, resistors, and multiple protection devices, the invention combines these functions into unified protection units that share common circuit elements, thereby reducing the overall layout area while maintaining enhanced electrostatic discharge performance.
Solution Approach 2:
The patent creates electrostatic discharge protection units that perform multiple functions simultaneously. The protection units can discharge static electricity through multiple paths (to VDD, VSS, and between power lines) while also providing biasing functions and protection against different types of electrostatic discharge events, reducing the need for separate dedicated components for each function.
2Reliability
If multiple electrostatic discharge protection devices are coupled to provide various discharge paths, then the electrostatic discharge performance is enhanced, but the layout area is increased
Solution Approach 1:
The patent segments the electrostatic discharge protection function into multiple protection units (first, second, and third protection units) that can be independently configured and optimized. Each unit handles specific discharge paths or conditions, allowing for more efficient space utilization compared to a single large protection circuit while providing comprehensive multi-path discharge capability.
Solution Approach 2:
The patent implements a nested structure where electrostatic discharge protection units are integrated within the memory device architecture at multiple levels. The protection units are embedded in the circuit paths between pads and internal circuits, with some protection functions nested within others, creating a compact hierarchical structure that reduces overall area while maintaining multiple discharge paths.
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 improves the driving ability and efficiency of static electricity discharge, reducing the layout area and enhancing the overall electrostatic discharge performance of the semiconductor memory device.
Implementation Method 1
When static electricity is generated at a pad 10, the static electricity is discharged from the pad 10 through the NMOS transistor N1 to a ground voltage line VSS
Implementation Method 2
When a voltage level of the drain is increased due to static electricity, an avalanche breakdown is generated between the drain of the NMOS transistor and a substrate to allow electrostatic current to flow to the substrate
Implementation Method 3
the electrostatic current is discharged from the drain to the source of the NMOS transistor according to the bipolar junction transistor (BJT) properties of the NMOS transistor
Data Source
AI summary
The present invention describes an electrostatic discharge protection circuit that protects an internal circuit of a semiconductor device from electrostatic discharge. The electrostatic discharge protection circuit includes a first electrostatic protection unit that transfers static electricity as a driving signal and also discharges the static electricity to a first discharge line when the static electricity is generated in a pad. It also includes a second electrostatic protection unit that discharges the static electricity generated in the pad to a second discharge line in response to the driving signal transferred from the first electrostatic protection unit. Since the first electrostatic protection unit performs an electrostatic discharge operation and at the same time aids the driving of the second electrostatic protection unit, electrostatic discharge performance can be enhanced while a layout area of the electrostatic discharge protection circuit can be reduced.