Multi-Portioned Guard Ring Schottky Diode Leakage Reduction
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Solution Overview
Problem
Schottky diodes exhibit higher leakage currents and lower breakdown voltages due to sharp contact edges, leading to electric field crowding and minority carrier injection issues, which slow switching speeds and cause latch-up problems in integrated circuits.
Innovation Solution
A Schottky diode structure with a multi-portioned guard ring that includes a first portion for forming an ohmic contact and a second portion for forming a Schottky contact, where the conductive contact overlaps only the second portion, reducing leakage and suppressing minority carrier injection while maintaining high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a doped pn junction guard ring is used to reduce electric field crowding, then leakage current is reduced and breakdown voltage is increased, but minority carrier injection increases which slows switching speeds and causes latch-up problems
Solution Approach 1:
The guard ring is divided into two distinct portions: a first portion with higher dopant concentration that forms an ohmic contact to reduce electric field crowding, and a second portion with lower dopant concentration that forms a Schottky contact to suppress minority carrier injection. This segmentation allows each portion to perform its specific function independently, resolving the contradiction between improving breakdown voltage and maintaining switching speed.
Solution Approach 2:
Different regions of the guard ring are assigned different dopant concentrations to create localized functional zones. The first portion (higher doping) is optimized for electric field management, while the second portion (lower doping) is optimized for minimizing carrier injection. This local differentiation enables the guard ring to simultaneously achieve high breakdown voltage and fast switching performance.
2Object-affected harmful factors
If a traditional guard ring structure is used, then electric field crowding is reduced, but the parallel connected pn junction diode causes significant minority carrier injection
Solution Approach 1:
The guard ring is segmented into two portions with different electrical characteristics. The first portion handles electric field crowding through higher doping, while the second portion minimizes minority carrier injection through lower doping and Schottky contact formation. This segmentation allows independent optimization of each harmful factor without compromise.
Solution Approach 2:
The multi-portioned guard ring structure acts as an intermediary between the Schottky contact and the substrate, mediating the electric field distribution and carrier flow. By introducing this intermediate structure with graded doping, the patent simultaneously mitigates electric field crowding at the contact edge and reduces minority carrier injection into the substrate.
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 multi-portioned guard ring structure reduces off-state leakage, suppresses minority carrier injection, and enhances reverse breakdown voltage characteristics, improving switching speed and preventing latch-up issues in integrated circuits.
Implementation Method 1
a first portion having a dopant concentration in proximity to the major surface that is configured to form an ohmic contact
Implementation Method 2
a second portion or portions having a dopant concentration in proximity to another portion of the major surface that is configured to form a Schottky contact
Implementation Method 3
The conductive contact overlaps the second portion of the guard ring and forms a second Schottky barrier with the second portion of the guard ring that has an opposite polarity to the first Schottky barrier
Data Source
AI summary
In one embodiment, a semiconductor structure comprises a multi-portioned guard ring that includes a first portion and a second portion formed in a region of semiconductor material. A conductive contact layer forms a first Schottky barrier with the region of semiconductor material. The conductive contact layer overlaps the second portion and forms a second Schottky barrier that has an opposite polarity to the first Schottky barrier. The conductive contact layer does not overlap the first portion, which forms a pn junction with the region of semiconductor material.