Fluorine-Implanted Power Diode Anode for Lower Reverse Recovery Peaks
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Solution Overview
Problem
In power diodes, high charge carrier concentration near the anode terminal can lead to high current peaks during reverse recovery, which is undesirable in certain applications.
Innovation Solution
A power diode with a semiconductor body having an anode region and a drift region, where an anode contact zone and an anode damage zone are formed in the anode region through a single ion implantation processing step, and fluorine is included in these zones at a concentration of at least 10^16 atoms/cm^3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high charge carrier concentration is maintained in the anode region, then good forward conduction is achieved, but high current peaks occur during reverse recovery
Solution Approach 1:
The anode region is segmented into multiple zones with different doping concentrations: a first anode zone with higher doping concentration (10^18 to 10^20 atoms/cm³) for good contact, a second anode zone with intermediate concentration (10^17 to 10^19 atoms/cm³), and a third anode zone with lower concentration (10^16 to 10^18 atoms/cm³) adjacent to the drift region. This gradient structure allows progressive reduction of charge carrier concentration toward the drift region boundary, reducing reverse recovery current peaks while maintaining forward conduction capability.
Solution Approach 2:
Different regions of the anode are assigned different doping concentrations tailored to their specific functions: the first anode zone near the contact has high concentration for low contact resistance, the third anode zone near the drift region has lower concentration to reduce stored charge and reverse recovery peaks, and intermediate zones provide transition. This local optimization resolves the contradiction between overall forward conduction and localized reverse recovery behavior.
2Object-generated harmful factors
If charge carrier concentration is reduced in the anode region, then reverse recovery current peaks are reduced, but forward conduction capability deteriorates
Solution Approach 1:
The anode is divided into multiple zones with a doping concentration gradient rather than uniform doping. The first zone maintains high concentration (10^18 to 10^20 atoms/cm³) for good forward conduction and low contact resistance, while the third zone has reduced concentration (10^16 to 10^18 atoms/cm³) to limit reverse recovery current peaks. This segmentation allows simultaneous optimization of both forward conduction and reverse recovery characteristics.
Solution Approach 2:
The doping concentration parameter is varied spatially across the anode region, creating a gradient from high concentration at the contact interface to lower concentration near the drift region boundary. This parameter change enables the anode to exhibit different electrical characteristics in different locations, achieving both low forward resistance and reduced reverse recovery peaks.
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 solution effectively reduces the reverse recovery current peaks by controlling the charge carrier concentration and defect distribution in the anode region, improving the power diode's performance and reliability.
Implementation Method 1
forming, by a single ion implantation processing step, each of an anode contact zone and an anode damage zone in the anode region
Implementation Method 2
fluorine is included within each of the anode contact zone and the anode damage zone at a fluorine concentration of at least 10^16 atoms*cm−3
Data Source
AI summary
A power diode includes a semiconductor body having an anode region and a drift region, the semiconductor body being coupled to an anode metallization of the power diode and to a cathode metallization of the power diode, and an anode contact zone and an anode damage zone, both implemented in the anode region, the anode contact zone being arranged in contact with the anode metallization, and the anode damage zone being arranged in contact with and below the anode contact zone, wherein fluorine is included within each of the anode contact zone and the anode damage zone at a fluorine concentration of at least 1016 atoms*cm-3.