PIN Diode Trench Layout for Reverse Recovery Loss Reduction
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Solution Overview
Problem
Reverse recovery operations in pin diodes lead to recovery losses and potential damage due to electric field concentration and avalanche breakdown, limiting the reverse recovery safe operating area.
Innovation Solution
The semiconductor device incorporates a pin diode structure with a channel region and strategically positioned anode regions to reduce carrier injection into the drift region, dispersing avalanche breakdown and enhancing hole discharge paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pin diode is used for reverse recovery operation, then the freewheeling diode function is achieved, but recovery loss increases due to carrier injection into the drift region
Solution Approach 1:
The drift region is divided into multiple segments by introducing first and second trenches, creating first and second drift regions separated by a trench insulating film. This segmentation reduces carrier injection into each drift region segment, thereby reducing recovery loss while maintaining the freewheeling diode function.
Solution Approach 2:
Different regions are created with distinct properties: the first and second drift regions have different carrier concentrations, the channel region provides selective carrier transport, and the trench insulating film creates electrical isolation. This local differentiation optimizes both recovery loss reduction and freewheeling diode performance.
2Ease of operation
If reverse recovery operation is performed in pin diode, then current switching is achieved, but electric field concentration causes avalanche breakdown and potential damage
Solution Approach 1:
The drift region is segmented into first and second drift regions by trenches, which disperses the electric field distribution during reverse recovery operation. This prevents electric field concentration at single points, reducing avalanche breakdown risk while maintaining current switching capability.
Solution Approach 2:
The channel region acts as an intermediary between the anode and drift regions, providing controlled carrier transport and field distribution. The trench insulating film serves as an intermediary structure that electrically isolates regions and prevents harmful field concentration, enabling safe current switching.
3Loss of energy
If carrier injection into drift region is reduced, then recovery loss decreases, but the reverse recovery safe operating area may be limited
Solution Approach 1:
The first and second drift regions are designed with different carrier concentrations and geometries, allowing optimized carrier injection reduction in each region while maintaining overall device performance. This local optimization enables both reduced recovery loss and expanded safe operating area.
Solution Approach 2:
The trench structure introduces a vertical dimension for field distribution and carrier management, allowing three-dimensional optimization of carrier concentration profiles. This enables simultaneous reduction of recovery loss and expansion of safe operating area through spatially differentiated design.
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 losses and expands the reverse recovery safe operating area by minimizing carrier injection and dispersing avalanche current, thereby suppressing damage and improving operational reliability.
Implementation Method 1
a recovery current flows in the reverse direction to discharge the carriers injected into the drift region
Implementation Method 2
electric field concentration may occur at a specific location of the pn junction to cause avalanche breakdown
Data Source
AI summary
A semiconductor device of embodiments includes: a semiconductor layer including a first trench, a second trench, a first semiconductor region of a first conductive type, a second semiconductor region of a second conductive type provided between a first face and the first semiconductor region, between the first trench and the second trench, and in contact with the second trench, a third semiconductor region of a first conductive type provided between the first trench and the second semiconductor region, a fourth semiconductor region of a second conductive type provided between the third semiconductor region and the first face, and a fifth semiconductor region of a second conductive type provided between the second semiconductor region and the first face, spaced from the fourth semiconductor region, in contact with the second trench; a first electrode on a first face side; and a second electrode on a second face side.