MOSFET Source Electrode Layout for Higher Avalanche Capability
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Solution Overview
Problem
Existing power semiconductor devices, such as MOSFETs, face challenges in improving their avalanche capability, particularly due to issues with hole discharge and parasitic NPN transistor activation during turn-off operations, which can lead to reduced avalanche breakdown voltage and on-current.
Innovation Solution
The semiconductor device incorporates a design with a source electrode comprising first and second contact portions, where the second contact portion has a larger width and depth than the first, and includes a field plate electrode, enhancing hole discharge and reducing parasitic transistor activation by minimizing contact with the source region, thereby improving avalanche capability and on-current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source electrode contacts the source region to ensure electrical connection, then electrical conductivity is improved, but parasitic NPN transistor activation occurs and avalanche capability deteriorates
Solution Approach 1:
The source electrode is divided into two distinct portions: a first portion that contacts the source region for electrical connection, and a second portion with larger width and depth that does not contact the source region to prevent parasitic transistor activation. This segmentation allows each portion to fulfill its specific function without causing harmful effects.
Solution Approach 2:
Different portions of the source electrode are designed with different geometries and contact characteristics. The first portion has smaller dimensions suitable for electrical connection, while the second portion has larger width and depth to suppress parasitic effects. This local differentiation optimizes both electrical conductivity and avalanche capability.
2Reliability
If the contact portion width is increased to reduce resistance, then on-current is improved, but parasitic transistor activation increases and avalanche capability decreases
Solution Approach 1:
The source electrode is segmented into portions with different widths. The first portion maintains appropriate width for low resistance, while the second portion has larger width specifically positioned to prevent parasitic activation without excessively increasing overall resistance.
Solution Approach 2:
The width and depth parameters of the source electrode portions are optimized to different values. The second portion has larger width and depth parameters compared to the first portion, creating a gradient structure that balances electrical performance and avalanche capability.
3Reliability
If the source electrode depth is increased to improve contact, then electrical connection is enhanced, but parasitic transistor formation is promoted
Solution Approach 1:
The source electrode is divided into portions with different depths. The first portion has smaller depth suitable for stable electrical connection, while the second portion has larger depth positioned to suppress parasitic effects without过度 penetrating into regions that would activate parasitic transistors.
Solution Approach 2:
Different depths are applied locally to different portions of the source electrode. This creates a three-dimensional structure where connection stability and parasitic suppression are optimized at different locations within the device.
Data Source
AI summary
A semiconductor device according to an embodiment includes: a semiconductor layer; a first and gate electrode extending in a first direction; a second gate electrode extending in the first direction; a first electrode provided on the semiconductor layer; and a second electrode provided on opposites side of the semiconductor layer. The first electrode includes a first portion and a second portion, the first portion and the second portion are provided between the first gate electrode and the second gate electrode, the first portion and the second portion are in contact with the semiconductor layer, the second portion is in the first direction with respect to the first portion, and a second width of the second portion is larger than a first width of the first portion, or a second depth of the second portion is larger than a first depth of the first portion.