PNP ESD Protection Circuit With Blocking Well Isolation
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Solution Overview
Problem
Semiconductor integrated circuits are vulnerable to electrostatic discharge (ESD) due to increased integration of elements, which can cause malfunctions or damage, and existing ESD protection circuits are inadequate in preventing damage to isolation layers during discharge.
Innovation Solution
The semiconductor integrated circuit device incorporates a PNP transistor structure with a blocking well surrounding the body contact region, which diverts the electrostatic charge away from the isolation layers, preventing damage and ensuring effective discharge through the collector and emitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ESD protection circuit is implemented using a PNP transistor structure, then the integrated circuit is protected from electrostatic charge, but the isolation layers may be damaged during the discharge process
Solution Approach 1:
A blocking well is introduced as an intermediary structure between the body contact region and the isolation layers. This blocking well acts as a mediator that redirects the electrostatic discharge current away from the isolation layers, allowing the ESD protection function to be achieved without damaging the isolation layers. The blocking well serves as a protective intermediary that separates the high-current discharge path from the vulnerable isolation structures.
Solution Approach 2:
The ESD protection structure is segmented into distinct functional regions: the body contact region for charge entry, the blocking well for current redirection, and the isolation layers for structural separation. By segmenting the discharge path and introducing the blocking well as a separate element, the current is divided and redirected through safe paths, preventing concentrated current damage to the isolation layers while maintaining overall protection effectiveness.
2Reliability
If the blocking well is positioned to surround the body contact region, then the electrostatic charge is diverted away from the isolation layers, but the device complexity increases
Solution Approach 1:
The blocking well is merged with the existing PNP transistor structure by positioning it to surround the body contact region, combining the ESD protection function with the transistor's inherent structure. This integration allows the blocking well to serve dual purposes: protecting the isolation layers while maintaining the transistor's electrical functionality, thereby reducing the need for completely separate protection structures.
Solution Approach 2:
The blocking well structure is designed to perform multiple functions: it redirects electrostatic discharge current away from isolation layers, maintains the electrical integrity of the body contact region, and works cooperatively with the PNP transistor's existing structures. This multi-functionality reduces the need for additional separate protection elements, thereby limiting the increase in device complexity.
Data Source
AI summary
A semiconductor integrated circuit device may include a semiconductor substrate, an active well, an emitter, a base, a collector, a body contact region, and a blocking well. The semiconductor substrate may have a first conductive type. The active well may be formed in the semiconductor substrate. The active well may have a second conductive type. The emitter and the base may be formed in the active well. The collector may be formed in the semiconductor substrate outside the active well. The body contact region may be formed in the semiconductor substrate to electrically connect the collector with the semiconductor substrate. The body contact region may have a conductive type substantially the same as that of the collector. The blocking well may be configured to surround an outer wall of the body contact region. The blocking well may have the second conductive type.