Trenched Implanted Bipolar Transistor Base Layer Optimization
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Solution Overview
Problem
High voltage BJTs face limitations in achieving high common emitter current gain without compromising blocking capability due to low common emitter current gain and complications in gate driver design, as well as the need for thicker base layers to prevent punch-through breakdown.
Innovation Solution
A trenched-and-implanted bipolar junction transistor (TI-BJT) design with a thin base layer and U-shaped trenches, along with ion implantation and epitaxial structures, to enhance current gain and blocking voltage while reducing base layer thickness and doping requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base layer thickness is increased to prevent punch-through breakdown, then blocking capability is improved, but common emitter current gain deteriorates
Solution Approach 1:
The patent introduces U-shaped trenches that extend vertically through the base layer, creating a three-dimensional structure. This vertical dimension allows the depletion region to be contained within the trench structure during blocking mode, preventing lateral punch-through while maintaining a thin base layer for high current gain during conduction mode.
Solution Approach 2:
The base layer is segmented by the U-shaped trenches into multiple regions. The trenches divide the base layer into isolated sections, allowing each segment to be independently optimized. This segmentation enables the base layer to be thin enough for high current gain while the trench structure provides the necessary blocking capability.
2Productivity
If the base layer thickness is reduced to improve current gain, then common emitter current gain is improved, but blocking capability deteriorates due to punch-through breakdown
Solution Approach 1:
By introducing vertical U-shaped trenches, the patent adds a third dimension to the base layer structure. This allows the base layer to be thin in the horizontal plane for high current gain, while the vertical trench walls provide the necessary depletion region containment for blocking capability.
Solution Approach 2:
The U-shaped trenches act as intermediary structures between the emitter and collector regions. These trenches provide a physical barrier that prevents direct punch-through of the depletion region through the thin base layer, enabling both thin base operation and high blocking capability.
3Manufacturing precision
If ion implantation is used to form the base layer, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent uses ion implantation to create localized doping regions with precise control over dopant concentration and depth. The U-shaped trenches are selectively formed in specific regions, allowing different parts of the device to have different doping characteristics optimized for their specific functions.
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 TI-BJT achieves higher common emitter current gain and improved blocking voltage without increasing base layer thickness, enabling efficient power conversion applications with reduced base current requirements.
Implementation Method 1
the side walls of the trenches may be implanted with a conductivity type to form an electrostatic shield
Implementation Method 2
at least one implanted U-shaped conductivity region of the first conductivity type
Data Source
AI summary
The present invention concerns a monolithically merged trenched-and-implanted Bipolar Junction Transistor (TI-BJT) with antiparallel diode and a method of manufacturing the same. Trenches are made in a collector, base, emitter stack downto the collector. The base electrode is formed on an implanted base contact region at the bottom surface of the trench. The present invention also provides for products produced by the methods of the present invention and for apparatuses used to perform the methods of the present invention.