Parallel PNP Transistor and Diode ESD Protection
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Solution Overview
Problem
Existing ESD protection circuits are inadequate in handling high-voltage electrostatic discharge (ESD) events, particularly in human body mode, as they often result in permanent damage to semiconductor elements and computer systems due to insufficient breakdown voltage and discharging speed.
Innovation Solution
An ESD protection device comprising at least one PNP transistor and one diode electrically coupled in parallel, with a Salicide block to prevent salicide formation within the diode region, providing an enhanced ESD discharging path between the input and ground terminals to protect inner circuits from high-voltage ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single diode or PNP transistor is used for ESD protection, then the device complexity is low, but the ESD protection capability in high-voltage scenarios is insufficient
Solution Approach 1:
The patent combines a PNP transistor and a diode into a parallel configuration to form a hybrid ESD protection device. The PNP transistor provides fast discharge capability through its collector-emitter path, while the diode provides clamping action through its breakdown characteristic. This merging of two different protection mechanisms in parallel achieves enhanced ESD protection capability (higher breakdown voltage and faster discharge speed) while maintaining relatively simple device structure and implementation
2Reliability
If the breakdown voltage of ESD protection elements is increased to handle high-voltage ESD events, then the protection capability against high-voltage ESD is improved, but the discharging speed decreases
Solution Approach 1:
The patent merges the characteristics of PNP transistor and diode by connecting them in parallel. The PNP transistor contributes fast discharge speed through its minority carrier injection and collector-emitter conduction path, while the diode contributes high breakdown voltage capability. This combination allows the ESD protection device to simultaneously achieve both high breakdown voltage (for high-voltage ESD protection) and fast discharge speed (through PNP transistor action), resolving the trade-off between these two parameters
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 enhances the ESD protection capability, particularly in high-voltage scenarios, by providing a robust discharging path that prevents damage to inner circuits, as demonstrated by experimental data showing improved performance compared to diode-only and PNP transistor-only configurations.
Implementation Method 1
the elements used in the ESD protection circuit must have low breakdown voltage therein or- faster discharging speed
Data Source
AI summary
Electrostatic discharge (ESD) protection device in high voltage and the relevant manufacturing method is disclosed. The mentioned ESD protection device is disposed to bridge a ground and an input connected with an inner circuit to be protected. In which, the ESD protection device for high voltage comprises at least one PNP transistor and at least one diode connected in parallel, and an ESD discharging path is formed thereby. The PNP transistor is formed with an adjacent heavily doped P-type semiconductor zone (P+), lightly doped N-type semiconductor zone (N−), and a P-type semiconductor substrate. The diode is formed with an adjacent lightly doped N-type semiconductor zone and a light doped P-type semiconductor zone.