ESD Protection Structure with Field Plate for Low Trigger Voltage
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Solution Overview
Problem
Conventional electrostatic discharge protection structures have high trigger voltages, which can lead to damage in semiconductor components with thinner oxide layers, making them more susceptible to electrostatic discharge damage.
Innovation Solution
An electrostatic discharge protection structure with an adjustable trigger voltage is designed, featuring a substrate and well region of different electrical conductivities, isolation regions, an oxide layer, and a field plate structure, where the trigger voltage is adjusted by modifying the width and position of the field plate during fabrication, allowing for a lower trigger voltage through the avalanche breakdown voltage of a unidirectional diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional SCR structure is used for electrostatic discharge protection, then the protection mechanism is established through avalanche breakdown, but the trigger voltage is high which causes damage to components with thinner oxide layers
Solution Approach 1:
The patent segments the SCR structure by introducing a communication region that connects the substrate and well region through isolation regions. This segmentation allows the avalanche breakdown to occur at a specific location (at the oxide layer interface) rather than requiring high voltage across the entire structure, thereby reducing the trigger voltage while maintaining ESD protection capability.
Solution Approach 2:
The oxide layer serves as an intermediary element in the patent. By positioning the communication region such that it contacts the oxide layer, the breakdown voltage is determined by the oxide layer's properties rather than the semiconductor junction properties alone. This intermediary role of the oxide layer enables lower trigger voltage for ESD protection.
2Manufacturing precision
If the oxide layer thickness is reduced to improve component performance, then the component becomes more susceptible to ESD damage due to higher susceptibility, but conventional SCR structures have high trigger voltage that causes damage
Solution Approach 1:
The patent changes the critical parameter for trigger voltage from the semiconductor junction characteristics to the oxide layer breakdown characteristics. By making the trigger voltage dependent on oxide layer properties rather than semiconductor doping profiles, the system can accommodate thinner oxide layers without requiring proportionally higher trigger voltages, thus maintaining reliability with improved manufacturing precision.
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 structure effectively reduces the trigger voltage, enhancing the protection against electrostatic discharge by forming a current channel with lower resistance, thus reducing the risk of damage to semiconductor components.
Implementation Method 1
the trigger voltage is lower than that in conventional designs... the avalanche breakdown voltage of a unidirectional diode
Implementation Method 2
the voltage at the anode reaches the breakdown voltage. This results in impact ionization to generate a large amount of electron-hole pairs
Implementation Method 3
The same mechanism also causes carrier drift in the n-type well region to cause holes to flow from the emitter to the base
Data Source
AI summary
An electrostatic discharge protection structure includes: substrate of a first type of conductivity, well region of a second type of conductivity, substrate contact region in the substrate and of the first type of conductivity, well contact region in the well region and of the second type of conductivity, substrate counter-doped region between the substrate contact region and the well contact region and of the second type of conductivity, well counter-doped region between the substrate contact region and the well contact region and of the first type of conductivity, communication region at a lateral junction between the substrate and the well region, first isolation region between the substrate counter-doped region and the communication region, second isolation region between the well counter-doped region and the communication region, oxide layer having one end on the first isolation region and another end on the substrate, and field plate structure on the oxide layer.