IGBT Diode Absorption Region Design
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Solution Overview
Problem
Semiconductor devices with integrated IGBT and diode elements face challenges in reducing recovery loss due to excessive minority carrier accumulation, particularly around the guard ring and IGBT regions, which affects voltage breakdown resistance and switching efficiency.
Innovation Solution
The semiconductor device incorporates a semiconductor substrate with an IGBT region and a diode region, featuring a heavily doped absorption region on the back surface side with a varying ratio to the cathode region, optimized to effectively absorb minority carriers and improve voltage breakdown resistance by strategically placing the absorption region closer to the IGBT and guard ring areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a guard ring is formed around the element to improve voltage breakdown resistance, then voltage breakdown resistance is improved, but holes are excessively accumulated around the element causing reduction in recovery capability
Solution Approach 1:
The cathode region is divided into multiple regions with different P-type region configurations. The first cathode region has a higher concentration of P-type regions to absorb holes from the guard ring, while the second cathode region has fewer P-type regions to maintain good recovery characteristics. This segmentation allows different parts of the cathode region to serve different functions.
Solution Approach 2:
Different regions of the cathode are given different local qualities regarding P-type region concentration. The first cathode region (closer to guard ring) has higher P-type region concentration for hole absorption, while the second cathode region has lower P-type region concentration for maintaining recovery capability. This local differentiation resolves the contradiction between hole absorption and recovery performance.
2Loss of energy
If the P-type region is distributed in the cathode region to absorb holes, then hole absorption is improved, but it is difficult to completely absorb holes when a lot of holes are injected from the guard ring or IGBT
Solution Approach 1:
The cathode region is segmented into a first cathode region with high P-type region concentration for effective hole absorption and a second cathode region with lower P-type region concentration. This segmentation enables the device to handle large hole injection from guard ring and IGBT while maintaining good recovery characteristics in the second region.
Solution Approach 2:
The first cathode region uses excessive P-type region concentration to ensure complete hole absorption in areas where holes are heavily injected (near guard ring and IGBT), while the second cathode region uses partial P-type region concentration to maintain optimal recovery performance. This partial/excessive action strategy ensures holes are completely absorbed where needed without compromising overall recovery capability.
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 reduces recovery loss and enhances voltage breakdown resistance by efficiently absorbing minority carriers, thereby improving the overall performance and efficiency of the semiconductor device.
Implementation Method 1
holes that are injected from the heavily doped region around the element are likely to be excessively accumulated around the element
Implementation Method 2
A heavily doped region of first conductivity type is located on the first surface side around the element region. An absorption region of first conductivity type is located on the second surface side around the element region.
Data Source
AI summary
A semiconductor device includes a semiconductor substrate with a first surface and a second surface. The semiconductor substrate has an element region including an IGBT region and a diode region located adjacent to the IGBT region. An IGBT element is formed in the IGBT region. A diode element is formed in the diode region. A heavily doped region of first conductivity type is located on the first surface side around the element region. An absorption region of first conductivity type is located on the second surface side around the element region. A third semiconductor region of second conductivity type is located on the second surface side around the element region.