Lateral Bipolar Junction Transistor Electrostatic Discharge Protection
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Solution Overview
Problem
Lateral bipolar junction transistors exhibit unsatisfactory electrostatic discharge protection performance compared to vertical transistors, and increasing their size to improve protection is limited due to size constraints of semiconductor devices.
Innovation Solution
The structure of a lateral bipolar junction transistor is modified by forming additional wells and trench element isolation films on a p-type semiconductor substrate to define emitter, base, and collector regions, allowing for reduced base resistance and a deeper current path, thereby improving electrostatic discharge protection without increasing the transistor's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of the lateral bipolar junction transistor is increased to improve electrostatic discharge protection performance, then the protection capability is enhanced, but the device size becomes excessively large
Solution Approach 1:
The patent introduces a third dimension by forming wells at different depths in the semiconductor substrate. The first well is formed at a first depth and the second well is formed at a second depth greater than the first depth, creating a vertical dimension that allows improved electrostatic discharge protection without increasing the lateral footprint of the device.
Solution Approach 2:
The base region is divided into two separate wells (first well and second well) at different depths, with the base region between these wells forming distinct portions. This segmentation allows optimization of different regions for different functions, improving overall protection performance within the same device area.
2Reliability
If additional wells and trench element isolation films are formed to reduce base resistance and increase holding voltage, then electrostatic discharge protection is improved, but device complexity increases
Solution Approach 1:
The base region is segmented into multiple portions formed between the first well and second well, allowing different regions to be optimized for different electrical characteristics. This segmentation enables reduced base resistance and increased holding voltage through strategic impurity implantation in different zones.
Solution Approach 2:
The structure employs nested wells where the first well and second well are formed at different depths within the semiconductor substrate, with the base region nested between them. This nested configuration allows multiple functional regions to be integrated vertically, improving electrical performance without lateral expansion.
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 modification allows for easier adjustment of triggering voltage, increased holding voltage, and enhanced breakdown voltage, effectively improving electrostatic discharge protection performance without enlarging the transistor.
Implementation Method 1
the tunneling effect of the bipolar junction transistor appears faster than that of FIG. 1, such that the triggering time can be advanced
Data Source
AI summary
A bipolar junction transistor includes a first trench element isolation film, a second trench element isolation film, a first base region, a second base region, a collector region, a first well, a second well, an emitter, a collector, and bases. The second well is formed by implanting an n-type impurity into the semiconductor substrate, and the emitter is formed by implanting the n-type impurity into the emitter region between the first trench element isolation film and the second well. The collector is formed by implanting the n-type impurity into the collector region between the first well and the second trench element isolation film, and the bases are formed by implanting the p-type impurity into the first base region and into the second base region between the emitter region and the second well.