Multi-Schottky Diode Layout for Low Loss and Leakage Control
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Solution Overview
Problem
High-power semiconductor diodes face a tradeoff between forward-operating characteristics and reverse-bias leakage current due to the conflicting requirements of reducing conduction losses and leakage currents, where improving one aspect typically worsens the other.
Innovation Solution
The diode design incorporates multiple Schottky contacts with different barrier heights, strategically locating lower barrier sub-contacts on portions of the drift region with lower electric fields to reduce forward voltage drop and on-state losses without significantly increasing reverse-biased leakage current, thereby improving both forward and reverse operating characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the barrier height of Schottky contact is reduced to lower forward voltage drop, then forward conduction losses are reduced, but reverse-bias leakage current increases
Solution Approach 1:
The Schottky contact is segmented into multiple regions with different barrier heights. A first Schottky contact region with lower barrier height is positioned in a first portion of the drift region to reduce conduction losses, while a second Schottky contact region with higher barrier height is positioned in a second portion of the drift region to suppress leakage current. This spatial segmentation allows independent optimization of forward and reverse characteristics.
Solution Approach 2:
Different portions of the drift region are assigned different local properties through selective placement of Schottky contacts with tailored barrier heights. The lower barrier height region provides favorable forward conduction where needed, while the higher barrier height region provides superior reverse blocking where required, creating local quality variations that resolve the global tradeoff.
2Use of energy by moving object
If forward voltage drop is reduced to improve forward operating characteristics, then on-state conduction losses are reduced, but reverse characteristics deteriorate with increased leakage current
Solution Approach 1:
The Schottky contact structure is divided into segmented regions with different barrier heights positioned at different locations within the drift region. This segmentation enables the first region to handle forward conduction efficiently while the second region maintains reverse blocking integrity, resolving the contradiction between forward energy efficiency and reverse reliability.
Solution Approach 2:
Different barrier height characteristics are assigned to different local regions of the Schottky contact. The lower barrier height region optimizes forward conduction losses, while the higher barrier height region ensures reverse blocking reliability, allowing each region to perform its specialized function optimally.
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
This approach effectively reduces the forward voltage drop and on-state losses while maintaining robust reverse blocking capabilities, achieving an improved tradeoff between on-state and off-state operating characteristics of the diode.
Implementation Method 1
a first Schottky material disposed on at least a portion of the shield region and on a first portion of the upper portion of the drift region, the first Schottky material defining a first Schottky contact with the drift region; and a second Schottky material disposed on a second portion of the drift region, the second Schottky material being adjacent to the first Schottky material, the second Schottky material defining a second Schottky contact with the drift region, the first Schottky contact having a first barrier height, the second Schottky contact having a second barrier height
Data Source
AI summary
In some aspects, a diode can include: a substrate and semiconductor layer of a first conductivity type, the semiconductor layer being disposed on the substrate and including a drift region; a shield region of a second conductivity type disposed in the semiconductor layer adjacent to the drift region; a first Schottky material disposed on at least a portion of the shield region and on a first portion of the drift region, the first Schottky material defining a first Schottky contact with an upper portion of the drift region; and a second Schottky material disposed on a second portion of the drift region, the second Schottky material being adjacent to the first Schottky material, the second Schottky material defining a second Schottky contact with the upper portion of the drift region, the first Schottky contact having a barrier height that is less than a barrier height of the second Schottky contact.