Bipolar Transistor Non-Uniform Doped Region for High Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon-based bipolar transistors face limitations in high-voltage operations due to lower breakdown voltage and increased collector resistance, which affects their performance in RF power amplifiers.
Innovation Solution
A bipolar transistor design featuring a laterally extending drift region with a doped region having a non-uniform lateral doping profile, where the doping level is highest near the collector-base junction, to enhance breakdown voltage and reduce collector resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a lateral drift region is introduced to increase breakdown voltage, then breakdown voltage is improved, but collector resistance increases
Solution Approach 1:
The patent applies local quality by creating a doped region with non-uniform doping concentration specifically beneath the collector-base junction. The doping concentration is highest near the junction and decreases laterally, providing localized field control exactly where needed to manage the trade-off between breakdown voltage and collector resistance.
Solution Approach 2:
The patent changes the doping concentration parameter of the doped region beneath the collector. By having a non-uniform doping profile with concentration varying from highest near the collector-base junction to lower laterally, the electric field distribution is modified to achieve both high breakdown voltage and low collector resistance.
2Strength
If doping concentration is increased near collector-base junction, then breakdown voltage is improved, but parasitic PNP turn-on risk increases
Solution Approach 1:
The patent applies local quality by creating a doped region with non-uniform doping concentration specifically beneath the collector-base junction. The doping concentration is highest near the junction and decreases laterally, providing localized field control exactly where needed to manage the trade-off between breakdown voltage and collector resistance.
Solution Approach 2:
The patent uses a doped region that replicates the field-control function of traditional lateral drift regions but achieves it through vertical doping beneath the junction rather than lateral extension, thereby avoiding the harmful effects while copying the beneficial field-shaping function.
3Speed
If collector resistance is reduced for high-frequency performance, then cut-off frequency is improved, but breakdown voltage decreases
Solution Approach 1:
The patent changes the doping concentration parameter of the doped region beneath the collector. By having a non-uniform doping profile with concentration varying from highest near the collector-base junction to lower laterally, the electric field distribution is modified to achieve both high breakdown voltage and low collector resistance.
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 design improves breakdown voltage and cut-off frequency while maintaining low collector resistance, making it suitable for high-voltage RF power amplifier applications.
Implementation Method 1
a doped region having a conductivity type that is different to that of the collector. The doped region extends laterally beneath the collector to form a junction at a region of contact between the doped region and the collector. The doped region has a non-uniform lateral doping profile.
Implementation Method 2
The placement of the doped region extending laterally beneath the collector may allow for electrical-field shaping within the collector to improve the breakdown voltage within the device.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A bipolar transistor includes a collector including a laterally extending drift region. The bipolar transistor also includes a base located above the collector. The bipolar transistor further includes an emitter located above the base. The bipolar transistor also includes a doped region having a conductivity type that is different to that of the collector. The doped region extends laterally beneath the collector to form a junction at a region of contact between the doped region and the collector. The doped region has a non-uniform lateral doping profile. A doping level of the doped region is highest in a part of the doped region closest to a collector-base junction of the bipolar transistor.