ESD Protection Structure with Resistive Path for SOI Thyristors

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Solution Overview

Problem

Conventional ESD protection structures in SOI technology suffer from current focalization and poor robustness during prolonged ESD gun stress tests, failing to meet automotive standards due to hotspot formation and inadequate voltage distribution across thyristor cells.

Innovation Solution

The introduction of a resistive path between diode-collector nodes of neighboring cells in the thyristor structure, preventing voltage clamping and allowing for easier avalanche breakdown, thereby reducing current focalization and enhancing the structure's ability to handle ESD events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ESD protection structures are implemented with SOI technology, then the structure provides ESD protection functionality, but current focalization causes hotspots and poor robustness during prolonged ESD gun stress tests

Engineering Contradiction:

Improverobustness during ESD gun stress testsVSAvoidcurrent focalization causing hotspots

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a resistive path specifically between diode-collector nodes of neighboring cells to create non-uniform electrical properties in targeted locations. This local modification prevents voltage clamping and promotes distributed avalanche breakdown, thereby eliminating current focalization hotspots while maintaining overall ESD protection functionality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the electrical parameters of the thyristor structure by introducing controlled resistance between diode-collector nodes. This parameter change alters the voltage distribution characteristics, enabling easier avalanche breakdown and more uniform current distribution across the ESD protection structure during stress tests.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional ESD protection structures are used, then the structure is simple in design, but it fails to meet automotive ESD requirements such as 2k/330pF gun model and +/−8kV gun stress target

Engineering Contradiction:

Improvecompliance with automotive ESD standardsVSAvoidthyristor structure configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the thyristor structure into multiple cells with distinct diode-collector nodes, and introduces resistive paths between these segmented nodes. This segmentation approach enables controlled voltage distribution and promotes distributed avalanche breakdown across multiple cells, thereby meeting automotive ESD standards while maintaining manageable structural complexity.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If voltage clamping occurs in conventional structures, then the structure maintains stable voltage, but avalanche breakdown is inhibited and current focalization increases

Engineering Contradiction:

Improvecurrent focalizationVSAvoidvoltage distribution stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent introduces a resistive path as an intermediary element between diode-collector nodes of neighboring cells. This intermediary resistance prevents direct voltage clamping while still providing electrical connection, thereby facilitating avalanche breakdown and reducing current focalization without completely destabilizing the voltage distribution.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces the likelihood of destructive failures during ESD events by distributing current more evenly across the ESD protection structure, improving its robustness and compliance with automotive standards.

Implementation Method 1

allowing for easier avalanche breakdown, thereby reducing the likelihood of an electrostatic discharge current flowing through the electrostatic discharge protection structure becoming focused

Methodology Applied

Scientific EffectAvalanche breakdown: Avalanche Breakdown

Data Source

PatentUS9960251B2ESD protection structure and method of fabrication thereof

Publication Date: 2018.05.01 NXP USA INC

AI summary

An ESD protection structure comprising a first semiconductor region of a first doping type, a second semiconductor region of the first doping type, a semiconductor structure of a second doping type opposite to the first doping type formed to provide lateral isolation between the first and second semiconductor regions of the first doping type, and a first contact region of the second doping type formed within a surface of the second semiconductor region. A thyristor structure is formed within the ESD protection structure comprising the first contact region of the second doping type, the second semiconductor region of the first doping type, the semiconductor structure of the second doping type, and the first semiconductor region of the first doping type. Wherein no contact region is formed within a surface of the semiconductor structure of the second doping type between the first and second semiconductor regions of the first doping type.