Vertical MOSFET with Segmented Source and Body Regions
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Solution Overview
Problem
Existing power MOSFETs lack sufficient robustness to withstand Avalanche breakdown without being damaged, as they are unable to dissipate the energy effectively during this event.
Innovation Solution
The design incorporates a semiconductor body with a drift region, gate electrodes in trenches, and alternating source and body regions, which enhances energy dissipation through the body regions and source electrode, increasing the MOSFET's robustness by allowing better heat dissipation and adjusting the ratio of source and body region areas to balance robustness and on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the drift region is designed to withstand high voltage blocking, then the voltage blocking capability is improved, but the robustness during Avalanche breakdown deteriorates due to insufficient energy dissipation capability
Solution Approach 1:
The source region is divided into multiple source regions arranged in parallel, and the body region is segmented into multiple body regions. This segmentation allows the energy during Avalanche breakdown to be distributed across multiple paths, improving the overall robustness while maintaining the voltage blocking capability of the drift region.
Solution Approach 2:
The patent introduces a lateral dimension by arranging source and body regions in alternating patterns across the semiconductor body. This lateral arrangement provides additional pathways for energy dissipation during Avalanche breakdown, complementing the vertical drift region's voltage blocking function.
2Reliability
If the source and body region areas are increased to improve robustness, then the energy dissipation capability is improved, but the on-resistance increases
Solution Approach 1:
The patent optimizes the ratio between source region area and body region area to achieve a balance between robustness and on-resistance. By carefully controlling these geometric parameters, the device can dissipate sufficient energy during Avalanche breakdown while maintaining acceptable conduction losses during normal operation.
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 enables the MOSFET to dissipate energy during Avalanche breakdown for a longer duration without damage, improving its robustness and voltage blocking capability while managing the on-resistance effectively.
Implementation Method 1
The MOSFET is switched off when a voltage is applied that biases the PN junction in a reverse direction, so that a depletion region is formed in the drift region
Implementation Method 2
When an Avalanche breakthrough sets in a high current flows through the MOSFET in the reverse direction
Implementation Method 3
this current causes the MOSFET to be heated
Data Source
AI summary
A transistor is disclosed that includes a semiconductor body having a first horizontal surface. A drift region is arranged in the semiconductor body. A plurality of gate electrodes is arranged in trenches of the semiconductor body. The trenches have a longitudinal direction and extending parallel relative to each other. The longitudinal direction of the trenches extends in a first lateral direction of the semiconductor body. The body regions and the source regions are arranged between the trenches. The body regions are arranged between the drift region and the source regions in a vertical direction of the semiconductor body. In the first horizontal surface, the source regions and the body regions are arranged alternately in the first lateral direction. A source electrode is electrically connected to the source regions and the body regions in the first horizontal surface.