SCR Clamp Circuit Layout for Low-Voltage ESD Protection
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Solution Overview
Problem
The development of semiconductor processes has led to smaller elements and lower operating voltages in integrated circuits, making existing electrostatic discharge (ESD) protection components inadequate due to high start-up voltage requirements and potential damage from ESD events.
Innovation Solution
A device incorporating silicon controlled rectifiers (SCRs) with a gate electrode over a channel region, forming a junction between conductivity type regions, which generates a trigger current to create a low-impedance discharge path and protect internal circuits from ESD, while minimizing additional area and maintaining low leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing ESD protection components are used, then ESD protection is provided, but the start-up voltage is too high which damages internal circuits with lower operating voltages
Solution Approach 1:
The patent modifies the trigger voltage parameter of the SCR by adjusting the doping concentrations and geometric dimensions of the P-N-P-N structure. Specifically, the emitter area ratio, base widths, and doping levels are optimized to reduce the trigger voltage from conventional high levels to below the operating voltage of internal circuits, enabling safe ESD protection for low-voltage devices
2Use of energy by moving object
If smaller elements and lower operating voltages are used to reduce power consumption, then power consumption is reduced, but ESD protection becomes inadequate
Solution Approach 1:
The patent implements localized ESD protection structures at specific I/O pads and internal circuit nodes where ESD events are most likely to occur. The P-N-P-N clamp circuits are strategically placed only at critical points rather than throughout the entire circuit, providing targeted protection while maintaining low overall power consumption of the scaled-down device
3Reliability
If conventional SCR structures are used, then ESD protection is provided, but additional area is increased which is unacceptable in scaled devices
Solution Approach 1:
The patent integrates the ESD protection P-N-P-N structures directly within the existing transistor fabrication process. The clamp circuits are nested within or adjacent to the active device regions, utilizing the same substrate and process steps, thereby minimizing additional area occupation while providing effective ESD protection for the scaled device
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 effectively reduces the risk of ESD damage to internal circuits with lower operating voltages by lowering the trigger voltage of the SCR and increasing the bipolar hold voltage, ensuring high ESD performance and efficiency.
Implementation Method 1
Electrostatic discharge (ESD) may cause malfunctions or even damage integrated circuits. Accordingly, an integrated circuit may include a component for ESD protection
Implementation Method 2
a first silicon controlled rectifier (SCR) including a first region of a first conductivity type electrically connected to the first node, a second region of a second conductivity type, a third region of the first conductivity type, and a fourth region of the second conductivity type electrically connected to the second node
Data Source
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AI summary
Provided is a device including a first clamp circuit electrically connected between a first node and a second node, and a second clamp circuit electrically connected between the second node and a third node, wherein the first clamp circuit includes a first silicon controlled rectifier (SCR) including a first region of a first conductivity type electrically connected to the first node, a second region of a second conductivity type, a third region of the first conductivity type, and a fourth region of the second conductivity type electrically connected to the second node, and a first gate electrode disposed over a channel region including a junction of the second region and the third region between the first region and the fourth region.