IGBT-Diode Boundary Structure for Lower Reverse Recovery Loss
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Solution Overview
Problem
Conventional semiconductor devices with insulated gate bipolar transistors (IGBTs) and diodes experience high reverse recovery losses due to hole flow across the boundary between the IGBT and diode regions, leading to inefficient energy discharge and increased power losses.
Innovation Solution
Incorporating a p-type current limiting region above the boundary between the collector and cathode regions, which floats in an n-type region formed by the buffer and drift regions, restricts hole flow and reduces reverse recovery losses by acting as a barrier during diode operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional semiconductor device structure with IGBT and diode regions is used, then the device can perform both switching and rectification functions, but reverse recovery losses increase due to hole flow across the boundary region
Solution Approach 1:
The semiconductor device is divided into distinct functional regions: an IGBT region with collector region, body region, and emitter region, and a diode region with cathode region and anode region. A buffer region is introduced between these regions to segment the hole flow paths, preventing holes from the IGBT region from flowing into the diode region during reverse recovery, thereby reducing reverse recovery losses while maintaining both switching and rectification functions
Solution Approach 2:
A buffer region of n-type semiconductor is introduced as an intermediary layer between the IGBT region and diode region. This buffer region acts as a mediator that blocks hole flow from the IGBT region into the diode region during reverse recovery, reducing reverse recovery losses without affecting the normal operation of either the IGBT or diode
2Productivity
If the boundary region between IGBT and diode is made larger to improve carrier flow, then device performance improves, but reverse recovery losses increase due to increased hole backflow
Solution Approach 1:
The boundary region is segmented by introducing a buffer region that divides the space between IGBT and diode regions. This segmentation allows the boundary to be sufficiently large for good electrical contact while preventing harmful hole backflow through the buffer region, thus improving device performance without increasing reverse recovery losses
Solution Approach 2:
The buffer region serves as an intermediary layer at the boundary between IGBT and diode regions, enabling sufficient physical separation for device performance while acting as a barrier to hole backflow, thereby decoupling the relationship between boundary size and reverse recovery losses
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 current limiting region effectively restricts reverse recovery losses by minimizing hole backflow at the boundary between the IGBT and diode regions, resulting in reduced power losses and improved efficiency.
Implementation Method 1
a current limiting region of p-type disposed above a boundary between the collector region and the cathode region and being in contact with an upper surface of the buffer region
Data Source
AI summary
A semiconductor device includes a semiconductor substrate and a lower electrode. The semiconductor substrate includes a collector region of p-type and a cathode region of n-type being in contact with the lower electrode. The semiconductor substrate has an insulated gate bipolar transistor range overlapping with the collector region when viewed along a thickness direction of the semiconductor substrate, and a diode range overlapping with the cathode region when viewed along the thickness direction of the semiconductor substrate. The semiconductor substrate further includes a buffer region of n-type being in contact with upper surfaces of the collector region and the cathode region, a drift region of n-type being in contact with an upper surface of the buffer region, and a current limiting region of p-type disposed above a boundary between the collector region and the cathode region and being in contact with an upper surface of the buffer region.