Semiconductor Device Boundary Region Lifetime Control
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Solution Overview
Problem
Conventional semiconductor devices with both transistor and diode portions on the same substrate face challenges in controlling carrier lifetime and suppressing reverse recovery loss due to the increase in hole injection and tunnel current, particularly at the boundary region between the transistor and diode portions, leading to increased reverse recovery peak current and potential device destruction from latch-up.
Innovation Solution
Incorporation of a lifetime control region formed by irradiating helium or protons to promote recombination of holes and electrons, combined with a current suppression structure in the boundary region that alters the dummy ratio of trench portions to reduce tunnel current and maintain transistor functionality, while also forming a lifetime control region on the back surface to enhance carrier disappearance during turn-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a lifetime control region is provided over a part of the region from the diode portion to the adjacent transistor portion to suppress an increase in carriers from the transistor portion, then reverse recovery loss is reduced, but hole injection and tunnel current increase at the boundary region, leading to increased reverse recovery peak current and potential device destruction from latch-up
Solution Approach 1:
The patent applies local quality by providing a lifetime control region selectively in specific areas. The lifetime control region is provided over a part of the region from the diode portion to the adjacent transistor portion, but not uniformly across the entire device. This localized approach allows carrier lifetime to be controlled where needed to reduce reverse recovery loss while avoiding excessive hole injection and tunnel current in other regions, thus preventing latch-up and maintaining device reliability.
2Duration of action of moving object
If the lifetime control region is extended to suppress carrier increase from transistor portion, then reverse recovery characteristics improve, but tunnel current and hole injection increase at boundary region causing latch-up risk
Solution Approach 1:
The patent segments the device into distinct regions with different functionalities. The lifetime control region is segmented to be provided only in specific areas (over a part of the region from the diode portion to the adjacent transistor portion) rather than uniformly across the entire device. This segmentation allows the device to achieve improved reverse recovery characteristics through controlled carrier lifetime reduction while avoiding the harmful effects of excessive tunnel current and hole injection at boundary regions.
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 solution effectively reduces reverse recovery loss by promoting carrier disappearance and suppressing peak current during reverse recovery, while maintaining the transistor's operational integrity by minimizing latch-up and threshold voltage decreases.
Implementation Method 1
a lifetime control region formed by irradiating helium or protons to promote recombination of holes and electrons
Data Source
AI summary
Provided is a semiconductor device including a semiconductor substrate including a transistor portion and a diode portion. The semiconductor substrate includes a drift region of a first conductivity type provided inside. The transistor portion includes: a transistor region separated from the diode portion in a top view of the semiconductor substrate; and a boundary region located between the transistor region and the diode portion in a top view of the semiconductor substrate and including a lifetime control region on a front surface side of the semiconductor substrate in the drift region. The boundary region has a current suppression structure.