Segmented MOSFET Drift Regions for Parasitic Diode Breakdown Control
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Solution Overview
Problem
Semiconductor devices, such as MOSFETs, face breakdown issues due to the operation of parasitic diodes, which are not effectively suppressed by existing technologies, leading to reduced breakdown voltage and potential device failure.
Innovation Solution
The semiconductor device incorporates specific semiconductor regions with controlled impurity concentrations and geometries, including p-type RESURF and relaxation regions, to manage electric field intensity and suppress breakdown by separating and positioning these regions to lag behind the primary parasitic diode operation, thereby reducing the risk of breakdown and maintaining high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If parasitic diodes are allowed to operate in semiconductor devices, then current flow capability is improved, but breakdown voltage decreases leading to device failure
Solution Approach 1:
The semiconductor device divides the drift region into multiple segments: a first drift region, a second drift region with higher impurity concentration, and a third drift region. This segmentation allows different regions to handle different aspects of current flow and voltage blocking, enabling parasitic diode operation while maintaining high breakdown voltage through the structured impurity concentration distribution.
Solution Approach 2:
The patent applies local quality by creating regions with different impurity concentrations at specific locations. The second drift region has a higher impurity concentration than the first and third drift regions, and the guard ring structure has tailored impurity profiles. This local variation in material properties enables the device to tolerate parasitic diode operation while preserving overall breakdown voltage.
2Reliability
If guard ring structures are added to suppress breakdown, then breakdown voltage is improved, but device complexity increases
Solution Approach 1:
The patent merges the guard ring structure with the drift region by forming the guard ring within the same semiconductor layer continuum. The guard ring shares the same basic structural framework as the drift region, eliminating the need for completely separate structures and reducing overall device complexity while maintaining breakdown voltage suppression functionality.
Solution Approach 2:
The drift region structure serves multiple functions: it provides the primary current conduction path, establishes the breakdown voltage characteristics, and incorporates the guard ring functionality for parasitic diode suppression. This multi-functionality reduces the need for additional dedicated structures, thereby limiting the increase in device complexity.
3Reliability
If impurity concentration is increased in drift regions, then breakdown voltage is improved, but current flow capability during parasitic diode operation deteriorates
Solution Approach 1:
The patent applies local quality by creating regions with different impurity concentrations at specific locations. The second drift region has a higher impurity concentration than the first and third drift regions, and the guard ring structure has tailored impurity profiles. This local variation in material properties enables the device to tolerate parasitic diode operation while preserving overall breakdown voltage.
Solution Approach 2:
The patent changes the impurity concentration parameter spatially across different drift regions. The second drift region has a higher impurity concentration to enhance local breakdown characteristics, while the first and third drift regions maintain lower concentrations to facilitate current flow during parasitic diode operation. This parameter variation resolves the contradiction between breakdown voltage and current capability.
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 suppresses breakdown when parasitic diodes operate, while maintaining a high breakdown voltage, even under conditions of large current flow, particularly beneficial for SiC devices where high currents can lead to breakdown.
Implementation Method 1
manage electric field intensity and suppress breakdown by separating and positioning these regions to lag behind the primary parasitic diode operation
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first electrode, a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type, a third semiconductor region of the first conductivity type, a gate electrode, a fourth semiconductor region of the second conductivity type, a fifth semiconductor region of the second conductivity type, a sixth semiconductor region of the second conductivity type, a seventh semiconductor region of the second conductivity type, an eighth semiconductor region of the second conductivity type, a second electrode, and a third electrode. The fourth semiconductor region is located around the second semiconductor region and the gate electrode. The fourth, fifth and sixth semiconductor regions are separated from each other. The fourth, seventh and eighth semiconductor regions are separated from each other. The third electrode is located on the eighth semiconductor region with an insulating layer interposed.