Deep Collector Bipolar Transistor Base Tuning Diffusion
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Solution Overview
Problem
Optimizing bipolar transistor characteristics such as gain (hfe) in CMOS integrated circuits is challenging without incurring additional processing costs, especially when manufacturing vertical bipolar transistors.
Innovation Solution
A deep collector vertical bipolar transistor with a first base tuning diffusion is implemented, where the first and second base tuning diffusions are formed using the same implant, allowing for independent adjustment of doping in the base tuning diffusion to optimize tradeoffs between breakdown voltage and gain without requiring extra lithography steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base tuning diffusion is optimized to enhance bipolar transistor gain, then gain (hfe) is improved, but breakdown voltage may deteriorate
Solution Approach 1:
The patent applies local quality by creating a base tuning diffusion with specific doping characteristics in the bipolar transistor region while maintaining different doping characteristics in the MOS transistor region. This localized optimization allows enhancement of bipolar transistor gain through controlled doping in the base region without adversely affecting the overall device breakdown voltage, as the doping is precisely targeted to where it is needed.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the doping concentration and profile in the base tuning diffusion to optimize the trade-off between gain and breakdown voltage. By modifying doping parameters (concentration, depth, distribution) in the base region, the bipolar transistor gain is enhanced while the breakdown voltage characteristics are maintained through controlled parameter selection.
2Manufacturing precision
If additional processing steps are added to optimize bipolar transistor characteristics, then manufacturing precision is improved, but device complexity and processing cost increase
Solution Approach 1:
The patent merges the base tuning diffusion process for bipolar transistors with the existing MOS transistor fabrication process. By combining these operations into a single integrated process step using the same implantation and diffusion conditions, the patent achieves precise control of bipolar transistor characteristics without adding separate processing steps, thereby avoiding increased device complexity and processing cost.
Solution Approach 2:
The patent applies universality by designing a base tuning diffusion process that serves dual purposes: optimizing bipolar transistor gain while simultaneously maintaining compatibility with MOS transistor fabrication. This multi-functional approach allows a single processing step to achieve multiple objectives, eliminating the need for additional dedicated processing steps for bipolar optimization.
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 gain of the deep collector vertical bipolar transistor while maintaining diode capacitance and breakdown voltage within specifications, allowing for improved performance without additional processing costs.
Implementation Method 1
A deep collector vertical bipolar transistor with a first base tuning diffusion
Data Source
AI summary
An integrated circuit and method having a deep collector vertical bipolar transistor with a first base tuning diffusion. A MOS transistor has a second base tuning diffusion. The first base tuning diffusion and the second base tuning diffusion are formed using the same implant.