Buffer Layer Graded Doping Profile Schottky Diode Avalanche Breakdown
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Solution Overview
Problem
Conventional high-power Schottky diodes have limited reverse performance due to the reduced current capacity of their termination region, which restricts their overall reverse biased safe operating area and avalanche breakdown capabilities.
Innovation Solution
The introduction of a buffer layer with a graded doping profile between the semiconductor layers reduces the localization of avalanche breakdown by smoothing the electric field, thereby enhancing the reverse biased safe operating area without compromising forward operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the termination region is designed to sustain the desired breakdown voltage, then the device is protected against avalanche breakdown, but the current capacity of the termination region is limited
Solution Approach 1:
The device is divided into multiple semiconductor layers with different doping concentrations. The termination region is segmented into at least two regions: a first termination region with higher doping concentration and a second termination region with lower doping concentration. This segmentation allows each region to handle different aspects of the electrical stress, enabling the termination region to sustain breakdown voltage while increasing overall current capacity.
Solution Approach 2:
Different regions of the termination structure are assigned different doping concentrations optimized for their specific functions. The first termination region with higher doping concentration is optimized for handling high current density, while the second termination region with lower doping concentration is optimized for voltage sustainment and electric field distribution. This local optimization resolves the contradiction between current capacity and breakdown protection.
2Reliability
If a buffer layer with graded doping profile is introduced, then the localization of avalanche breakdown is reduced and electric field is smoothed, but the device structure becomes more complex
Solution Approach 1:
A buffer layer with graded doping profile is introduced between the lightly-doped drift region and the heavily-doped termination region. The doping concentration in this buffer layer gradually transitions from the low concentration of the drift region to the high concentration of the termination region. This gradual parameter change smooths the electric field distribution, reduces peak electric field intensity, and prevents avalanche breakdown localization, thereby improving reliability while managing the increased structural complexity through a well-defined doping gradient.
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 solution improves the maximum current and sustainable energy handling capabilities of Schottky diodes, providing improved avalanche breakdown characteristics and preventing device failure from negative resistance and current focalization.
Implementation Method 1
The buffer layer has a graded doping profile that reduces the localization of avalanche breakdown by smoothing the electric field
Implementation Method 2
reduces the localization of avalanche breakdown by smoothing the electric field
Implementation Method 3
The Schottky diode uses a metal semiconductor junction... the first metal layer 125 and the doping concentration of the second semiconductor layer 110 are selected to form a Schottky junction 135 at the interface
Data Source
AI summary
A semiconductor device in one embodiment includes a depletion junction, a peripheral region adjacent the depletion junction, and a buffer layer. The buffer layer is adapted to reduce localization of avalanche breakdown proximate the interface between the depletion junction and the peripheral region.