Vertical Bipolar Junction Transistor BCD Process Integration
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Solution Overview
Problem
The existing Bipolar-CMOS-DMOS (BCD) process for manufacturing bipolar junction transistors increases manufacturing cost while struggling to achieve a satisfactory current gain, necessitating additional process steps that are costly and inefficient.
Innovation Solution
A vertical bipolar junction transistor design that incorporates a high concentration doping region emitter and collector terminals, a self-aligned base layer, and a collector layer with a higher doping concentration, formed using a low-cost BCD process, allowing for simultaneous formation with DMOS devices without the need for additional masks or process steps, thereby reducing manufacturing costs and enhancing current gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional process steps are added to elevate the current gain of the bipolar junction transistor, then the current gain is improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges the formation of the bipolar junction transistor with the formation of DMOS devices in a single integrated process. The emitter terminal, base terminal, and collector terminal are formed simultaneously with DMOS source and drain regions using shared doping and oxidation steps. This consolidation eliminates the need for separate BJT fabrication processes, achieving high current gain (β≥100) without increasing manufacturing cost.
2Reliability
If additional process steps are added to elevate the current gain of the bipolar junction transistor, then the current gain is improved, but the device complexity increases
Solution Approach 1:
The patent creates a universal process that simultaneously fabricates both BJT and DMOS devices using the same sequence of steps. The oxidation step forms both the BJT base-emitter junction and DMOS gate oxide; the doping steps create both BJT terminals and DMOS source/drain regions. This multi-functional approach achieves high current gain while maintaining simple, unified process complexity.
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 proposed design achieves a current gain of 100 or more within a base-emitter voltage range of 0.4 V to 0.7 V, reducing manufacturing costs and eliminating the need for additional process steps to elevate current gain, thus optimizing the BCD process for bipolar junction transistors.
Implementation Method 1
a high concentration doping region emitter terminal disposed on a semiconductor substrate, a high concentration doping region collector terminal disposed on a semiconductor substrate, a high concentration doping region base terminal disposed between the emitter terminal and the collector terminal, a drift region having a first doping concentration surrounding the emitter terminal
Data Source
AI summary
The present disclosure relates to a vertical bipolar junction transistor. A vertical bipolar junction transistor includes a high concentration doping region emitter terminal disposed on a semiconductor substrate; a high concentration doping region collector terminal disposed on a semiconductor substrate; a high concentration doping region base terminal disposed between the emitter terminal and the collector terminal; a drift region having a first doping concentration surrounding the emitter terminal and being deeper than either the base terminal or the collector terminal; a base layer disposed below the drift region; a collector layer in contact with the base layer, the collector layer having a second doping concentration higher than the first doping concentration. The manufacturing cost of the vertical bipolar junction transistor can be lowered and a current gain can be elevated using a low-cost BCD process.