BJT Field Plate Reduces Area While Maintaining ESD Breakdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrostatic discharge (ESD) clamps in semiconductor fabrication and testing processes are inefficient in protecting internal circuits due to varying breakdown voltages and trigger voltages, leading to potential damage from ESD events.
Innovation Solution
Incorporating a field plate over shallow trench isolation (STI) between collector and emitter doping regions in bipolar junction transistors (BJTs), which reduces the distance between these regions, thereby achieving a consistent breakdown voltage and lower trigger voltage, enhancing ESD protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between collector and emitter doping regions is reduced, then the trigger voltage is lowered and ESD protection is improved, but the breakdown voltage becomes inconsistent and varies
Solution Approach 1:
A field plate structure is introduced as an intermediary element positioned between the collector and emitter doping regions. The field plate includes a first field plate portion extending from the collector region toward the emitter region, and a second field plate portion extending from the emitter region toward the collector region, with a gap between them. This intermediary structure modifies the electric field distribution to achieve consistent breakdown voltage while maintaining low trigger voltage for effective ESD protection.
2Reliability
If a field plate is added to reduce trigger voltage, then ESD protection is enhanced, but the device area increases
Solution Approach 1:
The field plate structure extends vertically above the substrate surface rather than only laterally in the plane of the doping regions. By utilizing the vertical dimension, the field plate can influence the electric field between collector and emitter regions without proportionally increasing the lateral device footprint, thus reducing the area penalty compared to planar field plate configurations.
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 solution provides improved ESD protection by maintaining a consistent breakdown voltage and reducing the trigger voltage, thus preventing damage to internal circuits during ESD events and expanding the electrical-safe operating area.
Implementation Method 1
Incorporating a field plate over shallow trench isolation (STI) between collector and emitter doping regions in bipolar junction transistors (BJTs), which reduces the distance between these regions, thereby achieving a consistent breakdown voltage and lower trigger voltage
Data Source
AI summary
In some embodiments, a BJT structure includes a base region, an emitter region formed in the base region and including an emitter doping region, a collector region including a collector doping region, an insulating structure and a field plate. The base region forms a junction with the collector region between the emitter and collector doping regions. The field plate is formed over an insulating structure over the junction. A first distance between the corresponding emitter and collector doping regions to the junction is shorter than a second distance in another BJT structure without the field plate corresponding to the first distance. The first distance causes a breakdown of the junction corresponding to a first breakdown voltage value between the emitter and collector doping regions being substantially the same or greater than a second breakdown voltage value of the other BJT structure corresponding to the first breakdown voltage value.