Field Stop Proton Profile for Gentle Semiconductor Reverse Recovery
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Solution Overview
Problem
Conventional semiconductor devices face challenges in achieving low reverse recovery loss and gentle reverse recovery characteristics, particularly in terms of peak current, tail current, and the rate of temporal change of reverse recovery voltage.
Innovation Solution
The semiconductor device incorporates an n-type semiconductor substrate with a p-type semiconductor region on the front surface and an n-type field stop region on the rear surface, featuring a concentration distribution of protons as donors with multiple peaks in the depth direction, which controls the carrier lifetime distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional vertical semiconductor device structure is used, then the device can be manufactured with standard processes, but the reverse recovery loss is high and reverse recovery characteristics are poor
Solution Approach 1:
The patent applies parameter changes by creating a multi-peaked concentration distribution of donors in the field stop region, with specific peak positions and concentrations optimized to control carrier lifetime. This complex concentration profile (with 3-5 peaks at different depths and concentrations) enables simultaneous reduction of peak current and tail current during reverse recovery, thereby reducing reverse recovery loss while maintaining manufacturability through controlled doping processes
Solution Approach 2:
The patent implements local quality by creating non-uniform donor concentration distributions at different depth regions within the field stop region. Each peak in the concentration distribution (first peak near front surface, second peak in middle, third peak near rear surface) provides localized carrier lifetime control, allowing different regions to contribute differently to reverse recovery characteristics, thus reducing overall reverse recovery loss
2Loss of energy
If the peak current of reverse recovery current is reduced, then reverse recovery loss decreases, but the tail current may increase or reverse recovery may become less gentle
Solution Approach 1:
The patent uses parameter changes by establishing specific relationships between multiple concentration peaks: the first peak (closest to front surface) has concentration 1×10^16 to 1×10^18 atoms/cm³, the second peak (middle depth) has 5×10^15 to 5×10^17 atoms/cm³, and the third peak (near rear surface) has 1×10^16 to 1×10^18 atoms/cm³. This multi-parameter optimization of peak positions, concentrations, and depth distributions enables simultaneous control of both peak current and tail current characteristics
Solution Approach 2:
The patent applies segmentation by dividing the field stop region into multiple zones corresponding to different concentration peaks. The first peak zone controls early reverse recovery behavior (peak current), the second peak zone controls intermediate behavior, and the third peak zone controls late behavior (tail current). This segmented approach allows independent optimization of different phases of reverse recovery, achieving stable overall performance
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 configuration effectively reduces reverse recovery loss by minimizing peak and tail currents and achieves gentle reverse recovery by controlling the rate of temporal change of reverse recovery voltage.
Implementation Method 1
An n-type field stop region is formed in a rear surface side of the semiconductor substrate, the n-type field stop region including protons as a donor
Data Source
AI summary
A p-type semiconductor region formed in a front surface side of the semiconductor substrate. An n-type field stop (FS) region including protons as a donor is formed in a rear surface side of the semiconductor substrate. A concentration distribution of the donor in the FS region includes a first, second, third and fourth peaks in order from a front surface to the rear surface. A maximum point of peak concentration of the second peak is lower than a maximum point of peak concentration of the first peak.