Bonding Pad ESD Protection Circuit With Dynamic Power Clamping
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Solution Overview
Problem
The reduction in size of semiconductor components has compromised the reliability of integrated circuits by affecting their electrostatic discharge (ESD) protection, as existing buffer circuits struggle to effectively manage high voltage ESD events, potentially damaging components.
Innovation Solution
An electrostatic discharge protection circuit comprising a buffer circuit, a drive circuit, and a power-clamping circuit, where the buffer circuit includes N-type and P-type MOS transistors in a cascade configuration, and the drive circuit determines the state of these transistors based on a control voltage generated by the power-clamping circuit, which responds to the voltage on the bonding pad to manage ESD events by turning off the transistors and directing discharge currents to ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the size of semiconductor components is reduced to improve performance and operation speed, then performance and operation speed are improved, but electrostatic discharge protection capability deteriorates
Solution Approach 1:
The buffer circuit is divided into multiple transistor stages (first buffer transistor, second buffer transistor, third buffer transistor) with different functions. The first transistor provides voltage buffering, the second transistor provides ESD protection path, and the third transistor provides control. This segmentation allows each component to be optimized for its specific function while working together to solve the overall ESD protection problem in scaled technologies.
Solution Approach 2:
The patent introduces a control signal terminal and control circuit as intermediaries between the bonding pad and the buffer circuit. The control signal dynamically adjusts the ESD protection level by controlling the third buffer transistor, which acts as a mediator to activate or deactivate the ESD protection path based on operating conditions, thus protecting the scaled components without compromising normal operation.
2Reliability
If transistors are connected in series to conduct ESD current to ground, then electrostatic discharge protection is provided, but device complexity increases
Solution Approach 1:
The buffer circuit transistors serve multiple functions: the first buffer transistor provides both voltage buffering and ESD protection, the second buffer transistor provides both signal transmission and ESD current path, and the third buffer transistor provides both control functionality and ESD protection. This multi-functionality reduces the need for separate dedicated ESD protection components, thereby limiting the increase in device complexity while maintaining robust ESD protection.
Solution Approach 2:
The ESD protection circuit employs dynamic control through the control signal terminal that can activate or deactivate the ESD protection path based on operating conditions. The third buffer transistor dynamically adjusts its conduction state to enable ESD protection only when needed, rather than being permanently activated. This dynamic approach reduces the effective complexity by making the protection circuit adaptive rather than static.
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 circuit effectively protects semiconductor components from ESD by ensuring that ESD currents are safely conducted to ground, enhancing the electrostatic discharge capability and preventing component damage, even at high voltage levels.
Implementation Method 1
The power-clamping circuit is coupled to the bonding pad through the first node and coupled to a gate of the third transistor at a second node. The first control voltage is generated at the second node. The power-clamping circuit determines a level of the first control voltage according to a voltage on the bonding pad.
Implementation Method 2
In response to an electrostatic discharge event occurring on the bonding pad, the drive circuit turns off the first transistor according to the first control voltage.
Data Source
AI summary
An ESD protection circuit includes a buffer circuit, a driving circuit, and a power-clamping circuit. The buffer circuit includes first and second transistors having a first conductivity type coupled in a cascade configuration between a first node and a first power supply node. A bonding pad is coupled to the first node. The drive circuit determines a state of at least one of the first and second transistors according to a control voltage. The drive circuit includes a third transistor having a second conductivity type, which is coupled between a second power supply node and a gate of the first transistor and is controlled by the control signal. The power-clamping circuit is coupled to the bonding pad and a gate of the third transistor at a second node. The control voltage is generated at the second node and determined by a voltage at the bonding pad.