IGBT-Diode Region Layout for Stable Forward Voltage
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Solution Overview
Problem
The semiconductor device with an IGBT region and a diode region faces a challenge where the forward voltage of the diode changes before and after the application of 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 the total area of diode regions (SD) are optimized to be 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 forward voltage VF of the diode is suppressed, but breakdown tolerance decreases due to current concentration (overcurrent) at the diode region
Solution Approach 1:
The diode region is divided into multiple segments distributed across the active region. Instead of forming a single concentrated diode region, the patent creates multiple diode regions (first diode region, second diode region, etc.) that are spatially separated. This segmentation distributes the current flow paths, preventing current concentration while maintaining multiple carrier inflow paths to suppress forward voltage changes.
Solution Approach 2:
Different regions of the active region are given different functional qualities. The patent creates specific zones with diode characteristics distributed throughout the active region, where each local area has optimized properties for its specific function (carrier injection, current conduction, or diode operation). This allows simultaneous optimization of forward voltage stability and breakdown tolerance in different locations.
2Reliability
If multiple diode regions are formed to improve breakdown tolerance, then current concentration is reduced, but change in forward voltage VF of the diode increases due to increased carrier inflow paths
Solution Approach 1:
The patent optimizes the dynamic balance between the number of diode regions and their individual characteristics. By controlling the total area ratio of diode regions to active region (5-50%) and adjusting the dispersion degree, the system dynamically manages carrier inflow paths. This allows the structure to maintain breakdown tolerance through multiple regions while limiting excessive carrier inflow that would cause forward voltage changes.
Solution Approach 2:
The patent changes key parameters including the total area ratio of diode regions (5-50% of active region area), the dispersion degree (specific numerical ranges), and the spatial distribution pattern of diode regions. These parameter optimizations ensure that multiple diode regions provide sufficient breakdown tolerance while the controlled total area and dispersion prevent excessive carrier inflow paths that would destabilize forward voltage.
3Reliability
If the total area of diode regions is increased to improve breakdown tolerance, then current concentration is reduced, but the forward voltage VF change increases due to greater carrier inflow
Solution Approach 1:
The patent optimizes the total area ratio parameter, setting it within 5-50% of the active region area. This parameter range is critical: it provides sufficient total diode region area to distribute current and improve breakdown tolerance, while simultaneously limiting the total area enough to control the number of carrier inflow paths and prevent excessive forward voltage changes.
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.