Semiconductor Diode with Segmented p-Type Diffusion Layers
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Solution Overview
Problem
Existing semiconductor diodes face challenges in achieving both high breakdown voltage and low reverse recovery current, as reducing impurity concentration in the Schottky contact region to minimize reverse recovery current leads to decreased breakdown voltage, and adding a p-type stopper layer to restrict depletion layer spread increases reverse recovery current.
Innovation Solution
A semiconductor device with a p−−-type diffusion layer of low concentration in the anode region and strategically arranged p-type diffusion layers with gaps along the pn-junction interface, allowing electron flow while preventing depletion layer spread to the anode electrode, thereby maintaining high breakdown voltage and reducing reverse recovery current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the impurity concentration of the Schottky contact region is lowered to reduce reverse recovery current, then reverse recovery current decreases, but breakdown voltage cannot be obtained
Solution Approach 1:
The patent applies local quality by creating different impurity concentration zones within the anode region. The Schottky contact region maintains low impurity concentration to minimize hole injection and reduce reverse recovery current, while p-type diffusion layers are introduced at specific locations to prevent depletion layer spread and maintain breakdown voltage. This spatial variation in impurity concentration allows each region to optimize its local function.
Solution Approach 2:
The p-type diffusion layers act as intermediary structures between the Schottky contact region and the pn-junction interface. These intermediate layers serve dual functions: they block the spread of the depletion layer toward the anode electrode (maintaining breakdown voltage) while allowing electrons to pass through to the anode region (maintaining forward current capability).
2Reliability
If a p-type stopper layer is provided to restrict depletion layer spread, then breakdown voltage increases, but reverse recovery current increases
Solution Approach 1:
Rather than providing a continuous p-type stopper layer that would block electrons, the patent uses localized p-type diffusion layers arranged at specific intervals. These discrete layers provide depletion layer blocking functionality while maintaining electron transport pathways through the gaps between layers, thus avoiding the increase in reverse recovery current that would result from a complete stopper layer.
Solution Approach 2:
The patent segments the stopper layer function into multiple discrete p-type diffusion layers distributed along the pn-junction interface rather than using a single continuous layer. This segmentation allows the depletion layer to be blocked at multiple points while maintaining open pathways for electron flow through the intervening regions.
3Loss of time
If carriers in the active layer are discharged quickly to shorten switching time, then switching time decreases, but reverse recovery current increases
Solution Approach 1:
The patent changes the impurity concentration parameter in the anode region to create a low-concentration Schottky contact region. This parameter change reduces hole injection into the active layer during forward conduction, thereby reducing the total carrier storage in the active layer. With fewer carriers stored, less reverse recovery current is required to clear the active layer, enabling faster switching without excessive reverse recovery current.
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 enhances both reverse recovery characteristics and breakdown voltage by minimizing hole injection and ensuring appropriate electron concentration, resulting in improved diode performance with shorter reverse recovery times and higher breakdown voltages.
Implementation Method 1
strategically arranged p-type diffusion layers with gaps along the pn-junction interface, allowing electron flow while preventing depletion layer spread
Implementation Method 2
preventing depletion layer spread to the anode electrode, thereby maintaining high breakdown voltage
Implementation Method 3
minimizing hole injection and ensuring appropriate electron concentration, resulting in improved diode performance with shorter reverse recovery times
Data Source
AI summary
A semiconductor device has a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type, a first conductive layer disposed on a main surface of the first semiconductor region, and a second conductive layer disposed on a main surface of the second semiconductor region. The first conductive layer has a first diffusion layer of the first conductivity type, a plurality of second diffusion layers of the first conductivity type, the second diffusion layers having higher impurity concentration than the first diffusion layer, and a plurality of third diffusion layers of the first conductivity type that are included in the first semiconductor region, or are arranged apart from one another to contact the first and second semiconductor regions, the third diffusion layers being arranged apart from the plurality of second diffusion layers and having higher impurity concentration than the first diffusion layer.