Schottky Diode Floating Guard Rings Breakdown Voltage
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Solution Overview
Problem
Conventional Schottky diodes have low breakdown voltage, limiting their application in integrated circuits, particularly in BCD technology, where higher breakdown voltage is desirable without compromising switching performance.
Innovation Solution
The implementation of a Schottky diode with multiple floating guard rings and additional element isolation layers, such as shallow trench isolation, to enhance breakdown voltage while maintaining low turn-on voltage and negligible degradation of turn-on current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Schottky diode structure is used, then switching performance is maintained, but breakdown voltage is low
Solution Approach 1:
The guard ring structure is divided into multiple segments (first guard ring, second guard ring, third guard ring) with different conductivity types and doping concentrations. Each segment serves a specific function in controlling the electric field distribution, allowing the breakdown voltage to be increased through progressive field management rather than a single uniform structure.
Solution Approach 2:
Different regions of the guard ring structure are assigned different local properties: the first guard ring has high doping concentration for strong field control near the junction, the second guard ring has moderate doping for intermediate field management, and the third guard ring has low doping for extended field control. This local differentiation allows optimal breakdown voltage enhancement without compromising overall device performance.
2Reliability
If guard ring structure is added to improve breakdown voltage, then switching performance degrades
Solution Approach 1:
The guard ring structure is designed to be dynamically active during switching operations. The multiple guard rings with different conductivity types create time-varying electric field distributions that adapt to the switching state, enabling fast turn-on and turn-off while maintaining high breakdown voltage. The structure responds dynamically to voltage changes rather than being a static barrier.
Solution Approach 2:
The doping concentrations of the guard rings are specifically optimized to change the electrical parameters at different operating conditions. The first guard ring (high doping) controls parameters during high-voltage blocking, while the third guard ring (low doping) influences parameters during low-voltage switching, allowing both high breakdown voltage and fast switching to be achieved through parameter optimization.
3Reliability
If multiple floating guard rings are implemented, then breakdown voltage increases to 38-50V, but device complexity increases
Solution Approach 1:
The multi-guard ring structure serves multiple functions simultaneously: the first guard ring provides primary field control and junction protection, the second guard ring extends field management to intermediate regions, and the third guard ring provides secondary protection and leakage control. This multi-functionality allows a single integrated structure to achieve high breakdown voltage without requiring separate components for each function.
Solution Approach 2:
The guard rings are nested concentrically around the p-n junction, with the first guard ring closest to the junction, the second guard ring surrounding it, and the third guard ring outermost. This nested arrangement allows the structure to manage electric fields at multiple radial distances simultaneously, achieving high breakdown voltage through compact geometric nesting rather than dispersed component placement.
Data Source
AI summary
The present examples relate to a Schottky diode having floating guard rings and an additional element isolation layer configured to further improve a breakdown voltage of the Schottky diode, while maintaining the turn-on voltage and current in the forward characteristic, compared to a related Schottky diode. The floating guard rings in the examples are located in a position between the anode and the cathode regions or under the anode.