Free Wheel Diode Mesa Width Control for Stable Characteristics
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Solution Overview
Problem
The miniaturization of reverse conducting IGBT structures leads to difficulties in controlling and suppressing the diode characteristics of free wheel diodes, as the reduced mesa width causes sharp changes in diode performance, making it challenging to maintain consistent characteristics.
Innovation Solution
Setting the mesa width of the free wheel diode to be equal to or greater than 0.3 μm, while allowing the IGBT mesa width to be reduced, allows for easier characteristic control and variation suppression, achieving a substantially constant diode characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the mesa width of FWD is reduced to match the miniaturized IGBT mesa width, then the device size is reduced, but the diode characteristic control and variation suppression become difficult
Solution Approach 1:
The patent applies local quality by differentiating the mesa width between two regions: the IGBT region maintains a narrow mesa width (0.05-0.2 μm) for miniaturization, while the FWD region maintains a wider mesa width (0.3-1.0 μm) for stable diode characteristics. This spatial differentiation allows each component to have optimized dimensions for its specific function without compromising the other.
2Productivity
If the mesa width is reduced for miniaturization, then the device density increases, but the diode characteristic becomes unstable and varies sharply
Solution Approach 1:
The patent segments the semiconductor device into distinct functional regions with different mesa width characteristics. The IGBT portion is segmented with narrow mesas for high density, while the FWD portion is segmented with wider mesas for stability. This segmentation allows independent optimization of each region's geometric parameters to achieve both high device density and stable diode characteristics.
Data Source
AI summary
A semiconductor device includes a diode provided with: a drift layer being a first conductivity type; a cathode region being provided in a back face side of the drift layer and being the first conductivity type; a second conductivity type region provided in a surface layer part of the drift layer; multiple trenches dividing the second conductivity type region into pieces by being provided deeper than the second conductivity type region, and configuring an anode region; a gate insulation film provided in a surface of the trench; a gate electrode provided in a surface of the gate insulation film; an upper electrode electrically connected with the anode region; and a lower electrode electrically connected with the cathode region. A width between the trenches is narrowest in the drift layer is defined as a mesa width. The mesa width is set to be equal to or greater than 0.3 .mu.m.