Lateral Bipolar Transistor With Bias-Modulated Collector Doping
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Solution Overview
Problem
Existing lateral bipolar transistors face challenges in achieving a balance between switching speed and breakdown voltage, with current designs often compromising on one aspect at the expense of the other.
Innovation Solution
A lateral bipolar transistor design featuring a doped emitter and collector region with a base region positioned between, where the collector region is wider and less doped than the emitter, and a bias circuit modulates the electrostatic doping of the collector region by applying a bias voltage to a substrate region, enhancing switching speed and breakdown voltage through geometric and doping asymmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the collector region width is increased to improve breakdown voltage, then the breakdown voltage increases, but the switching speed decreases due to larger capacitance
Solution Approach 1:
The patent applies different doping concentrations to different regions: the collector region has a first doping concentration optimized for breakdown voltage, while the emitter region has a second doping concentration optimized for injection efficiency. This local differentiation allows each region to be optimized for its specific function without compromising the other.
Solution Approach 2:
The patent introduces a substrate bias circuit that can dynamically adjust the electrostatic doping of the collector region. By applying different bias voltages to the substrate, the effective doping concentration of the collector can be modulated, allowing the transistor to adapt its characteristics for different operating conditions (high voltage vs. high speed).
2Productivity
If the emitter doping concentration is increased to improve injection efficiency, then the injection efficiency improves, but the breakdown voltage decreases
Solution Approach 1:
The patent implements asymmetric doping where the emitter region receives a higher doping concentration than the collector region. This local quality differentiation enables the emitter to achieve high injection efficiency while the collector maintains lower doping for higher breakdown voltage capability.
Solution Approach 2:
The patent deliberately creates an asymmetric structure with different doping concentrations in the emitter and collector regions. This asymmetry is fundamental to achieving both high injection efficiency in the emitter and high breakdown voltage in the collector, as symmetric doping would force a compromise between these two parameters.
3Adaptability or versatility
If substrate biasing is applied to modulate electrostatic doping for improved performance, then switching speed and breakdown voltage can be optimized, but device complexity increases
Solution Approach 1:
The substrate bias circuit serves multiple functions: it modulates the electrostatic doping of the collector region, enables dynamic adjustment of breakdown voltage, and allows optimization of switching speed. This multi-functionality justifies the added complexity by providing comprehensive performance control from a single mechanism.
Solution Approach 2:
The patent utilizes parameter changes in the substrate bias voltage to dynamically adjust the electrostatic doping concentration of the collector region. By varying this parameter, the transistor can be tuned for different operating modes (high voltage operation vs. high speed operation) without physical restructuring.
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 design allows for improved switching speed and breakdown voltage performance by modulating the electrostatic doping of the collector region, offering a more efficient compromise between these critical transistor characteristics.
Implementation Method 1
a bias circuit coupled to the substrate region, and configured to deliver to said substrate region a bias voltage so as to modulate the electrostatic doping of the collector region
Data Source
AI summary
A lateral bipolar transistor includes an emitter region doped with a first conductivity type, having a first width and a first average doping concentration; a collector region doped with the first conductivity type, having a second width greater than the first width of the emitter region and a second average doping concentration lower than the first average doping concentration ; and a base region positioned between the emitter and collector regions. The emitter, collector and base regions are arranged in a silicon layer on an insulator layer on a substrate. A substrate region that is deprived of the silicon and insulator layers is positioned on a side of the collector region. A bias circuit is coupled, and configured to deliver, to the substrate region a bias voltage. This bias voltage is controlled to modulate an electrostatic doping of the collector region.