Lateral BJT Breakdown Voltage via Lightly Doped Region
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Solution Overview
Problem
Current lateral bipolar junction transistors (BJTs) have insufficient breakdown voltage, making them inadequate for modern electronic devices that require higher voltage ranges, particularly in applications such as electrostatic discharge protection circuits.
Innovation Solution
The introduction of a lightly doped region below the doped regions connected to a cathode and anode in the lateral BJTs, which can be of the same or different conductivity type, increases the breakdown voltage by confining current in a small region and dispersing the electric field, without requiring additional photomasks or altering the existing fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional BJT structure is used, then fabrication process is simple, but breakdown voltage is insufficient
Solution Approach 1:
The patent introduces a lightly doped region with specific doping concentration parameters between the n-type and p-type doped regions. This parameter change in doping concentration creates a gradient that increases the breakdown voltage from 7.7V to above 9V, while the doping process is integrated into existing fabrication steps without adding complex process steps.
2Reliability
If BJT breakdown voltage is increased, then electrostatic discharge protection capability is improved, but device area increases
Solution Approach 1:
The patent applies local quality by creating a lightly doped region specifically in the area between the cathode and anode doped regions. This localized modification of doping concentration enhances the breakdown voltage and electrostatic discharge protection capability in the critical region without requiring overall device area expansion.
3Reliability
If additional photomasks are added to increase breakdown voltage, then breakdown voltage is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the formation of the lightly doped region with existing fabrication processes. The lightly doped region is created using doping steps that are already part of the standard BJT fabrication sequence, eliminating the need for additional photomasks and reducing manufacturing costs while achieving the desired breakdown voltage improvement.
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 approach enhances the breakdown voltage of lateral BJTs from 8.5 volts to 9.2 volts, enabling their use in high-speed devices and complementary metal-oxide semiconductor radio frequency applications while maintaining compatibility with existing fabrication processes and improving heat dissipation.
Implementation Method 1
the doping concentration of the at least one lightly doped region is lower than the doping concentration of each of the first doped region and the second doped region, and is lower than the doping concentration of the well region
Implementation Method 2
can disperse an electric field, and increase the effect of heat dissipation
Data Source
AI summary
Provided is a lateral BJT including a substrate, a well region, an area, at least one lightly doped region, a first doped region, and a second doped region. The substrate is of a first conductivity type. The well region is of a second conductivity type and is in the substrate. The area is in the well region. The at least one lightly doped region is in the well region below the area. The first doped region and the second doped region are of the first conductivity type and are in the well region on both sides of the area. The first doped region is connected to a cathode. The second doped region is connected to an anode, wherein the doping concentration of the at least one lightly doped region is lower than that of each of the first doped region, the second doped region, and the well region.