IGBT-Diode Region Layout for Stable VF and Breakdown Tolerance
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Solution Overview
Problem
The semiconductor device with IGBT and diode regions faces a challenge where the forward voltage of the diode changes before and after applying a bias voltage to the IGBT, due to carrier inflow changes, leading to decreased breakdown tolerance and current concentration issues.
Innovation Solution
The semiconductor device is designed with a specific dispersion degree of diode regions relative to the active region, defined by the formula Loge(L2/SD), where the total extension of boundary lines between IGBT and diode regions (L) and their total area (SD) are optimized to ensure the diode regions are dispersed such that the dispersion degree is between 2 and 15, improving breakdown tolerance while minimizing forward voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the diode region is formed at just one location to restrict inflow paths for carriers, then change in the forward voltage VF of the diode can be suppressed, but breakdown tolerance decreases due to current concentration (overcurrent) at the diode region
Solution Approach 1:
The diode region is divided into multiple discrete diode regions (first diode region and second diode region) that are spatially separated and each adjacent to different IGBT regions. This segmentation distributes the carrier inflow paths across multiple locations, preventing current concentration at a single point while maintaining forward voltage stability through controlled carrier distribution.
Solution Approach 2:
Different diode regions are positioned at specific locations adjacent to different IGBT regions, creating local variations in carrier inflow characteristics. The first diode region is adjacent to the first IGBT region and the second diode region is adjacent to the second IGBT region, allowing each diode region to handle carriers locally generated in its adjacent IGBT region, thus balancing current distribution.
2Reliability
If multiple diode regions are formed to distribute current and improve breakdown tolerance, then breakdown tolerance increases, but the forward voltage VF of the diode changes more due to increased carrier inflow paths
Solution Approach 1:
The diode regions are asymmetrically positioned relative to the IGBT regions, with each diode region specifically adjacent to its corresponding IGBT region. The first diode region is adjacent to the first IGBT region while the second diode region is adjacent to the second IGBT region, creating an asymmetric but controlled carrier inflow pattern that balances breakdown tolerance improvement with forward voltage stability.
Solution Approach 2:
The patent introduces a spatial dimension consideration by positioning diode regions at different locations around the IGBT regions. The dispersion degree parameter (Loge(L2/SD)) quantifies this spatial distribution, where L represents the total extension of boundary lines and SD represents the total area of diode regions. By controlling the dispersion degree within 2-15, the patent optimizes the spatial arrangement to achieve both improved breakdown tolerance and maintained forward voltage stability.
Data Source
AI summary
A semiconductor device includes a semiconductor layer that has a first main surface at one side and a second main surface at another side and includes an active region, a plurality of IGBT regions that are formed in the active region, and a plurality of diode regions that are formed in the active region such as to be adjacent to the plurality of IGBT regions, and where when a total extension of boundary lines between the plurality of IGBT regions and the plurality of diode regions is represented by L, a total area of the plurality of diode regions is represented by SD, and a dispersion degree of the plurality of diode regions with respect to the active region is defined by a formula Loge (L2/SD), the dispersion degree is not less than 2 and not more than 15.