IGBT Diode Boundary Recovery via Extended Damage Region
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Solution Overview
Problem
The recovery characteristic of semiconductor devices with IGBT and diode regions is compromised at the boundary regions, leading to increased recovery current, loss, and decreased recovery resistance, especially at the ends of the diode region in the longitudinal direction.
Innovation Solution
A semiconductor device design where a damage region is extended in the outer peripheral region adjacent to the boundary between the diode and outer peripheral regions, with a length equal to or more than twice the thickness of the semiconductor substrate, to restrict hole flow and improve recovery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a damage region is arranged only in the diode region, then the reverse current during diode recovery is reduced, but the recovery characteristic deteriorates at the boundary region between the diode region and outer peripheral region
Solution Approach 1:
The damage region is selectively extended into the outer peripheral region adjacent to the diode region boundary, creating a localized structural modification. This extension specifically addresses the boundary region's poor recovery characteristic by forming a damage region that spans both the diode region and the adjacent outer peripheral region, thereby improving hole recombination at the boundary without affecting other areas
Solution Approach 2:
The damage region extension is defined by a specific dimensional criterion: the length in the longitudinal direction of the diode region is set to equal to or more than twice the thickness of the semiconductor substrate. This dimensional relationship ensures sufficient extension into the outer peripheral region to effectively block hole flow from the IGBT region while maintaining manufacturability
2Reliability
If the damage region is extended into the outer peripheral region, then the recovery characteristic at the boundary region is improved, but the device structure becomes more complex
Solution Approach 1:
The damage region's geometric parameters are precisely controlled: the length in the longitudinal direction of the diode region is specified as equal to or more than twice the substrate thickness. This parameter-based definition simplifies manufacturing by providing clear dimensional criteria for the extension process, avoiding the need for complex multi-step fabrication while ensuring effective boundary region modification
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
The extended damage region effectively reduces the recovery current and loss, enhancing the recovery resistance and overall recovery characteristic of the diode region adjacent to the boundary.
Implementation Method 1
a hole of the drift layer (i.e., an excess carrier) is recombined with an electron and eliminated in the damage region during the recovery time of the diode element
Implementation Method 2
a hole that flows from the IGBT region (i.e., IGBT element) to the diode region (i.e., diode element) during the recovery time is not blocked
Data Source
AI summary
A semiconductor device includes a semiconductor substrate having a drift layer, a base layer, a collector layer and a cathode layer. The semiconductor substrate includes a cell region and an outer peripheral region surrounding the cell region. The cell region includes an IGBT region and a diode region. The semiconductor substrate further includes a damage region arranged in the diode region and a part of the outer peripheral region adjacent to a boundary between the outer peripheral region and the diode region. A length, in a longitudinal direction of the diode region, of the part of the outer peripheral region, in which the damage region is arranged, is equal to or more than twice of a thickness of the semiconductor substrate. As a result, recovery characteristic is improved in a portion of the diode region adjacent to the boundary between the outer peripheral region and the diode region.