Fin-Based Bipolar ESD Structure With Lateral Ballasting Resistance
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Solution Overview
Problem
In FinFET technologies, the lack of horizontal ballasting resistance in ESD devices leads to insufficient protection during electrostatic discharge events, as not all protective devices turn ON due to insufficient resistance, resulting in inadequate current handling.
Innovation Solution
The integration of lateral ballasting resistance in fin-based bipolar ESD devices, achieved by forming epitaxially merged ballast resistance fins with collector fins, providing both vertical and lateral resistance to ensure proper triggering of all multi-finger devices during ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multi-finger ESD devices are used to handle large transient current flow, then current handling capacity is improved, but insufficient ballasting resistance prevents proper triggering of all parallel fingers
Solution Approach 1:
The patent introduces lateral ballasting resistance as a new dimensional approach to the traditional vertical ballasting resistance. By adding resistance in the lateral direction (horizontal ballasting) in addition to the vertical direction, the patent creates a two-dimensional ballasting network that effectively controls current distribution across all parallel fingers, enabling reliable triggering of all ESD devices during ESD events.
Solution Approach 2:
The patent applies different doping types (first dopant type for collector region, second dopant type for ballasting resistance region) to create localized regions with specific electrical properties. This local quality differentiation allows the ballasting resistance region to provide the necessary resistance characteristics without interfering with the collector region's function, enabling precise control over current distribution.
2Reliability
If vertical ballasting resistance is provided in FinFET technologies, then some resistance is achieved, but lack of horizontal ballasting resistance results in insufficient total ballasting resistance
Solution Approach 1:
The patent merges vertical and lateral ballasting resistance paths to create a combined three-dimensional ballasting network. The silicided regions provide vertical resistance while the laterally extended ballasting resistance regions provide horizontal resistance, and these two resistance components work together synergistically to achieve the total ballasting resistance needed for effective ESD protection across all parallel fingers.
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 solution significantly increases the ballast resistance, enabling all ESD devices to turn ON during multi-finger triggering, thereby enhancing ESD performance and current handling capacity, as demonstrated by increased resistance values and simulation results.
Implementation Method 1
the ballast resistance provided by the silicided regions (e.g., silicided block) provides an added resistance which, in turn, adds additional voltage to increase a voltage drop on the pad
Implementation Method 2
electrostatic discharge (ESD), which is a sudden transient flow of charge that can cause electrical shorts or dielectric breakdowns
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to electrostatic discharge (ESD) devices and methods of manufacture. The structure (ESD device) includes: a bipolar transistor comprising a collector region, an emitter region and a base region; and a lateral ballasting resistance comprising semiconductor material adjacent to the collector region.