Multiple-Finger ESD Device Layout for Uniform Current Distribution

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Solution Overview

Problem

Existing bipolar- and MOSFET-based ESD protection devices are unable to protect semiconductor devices with turn-on voltages lower than the trigger voltage of the ESD clamp, leading to potential failure during electrostatic discharge events due to high snap-back behavior and uneven current distribution among multiple-finger devices.

Innovation Solution

A multiple-finger ESD protection device layout featuring parallel-connected MOSFET or bipolar transistor devices with base or body contacts oriented perpendicularly to the fingers, ensuring uniform triggering and resistance across all fingers, maximizing current-carrying capability and ESD protection performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing bipolar- or MOSFET-based ESD clamps are used, then ESD protection is provided, but semiconductor devices with turn-on voltage lower than the trigger voltage cannot be protected

Engineering Contradiction:

ImproveESD protection capabilityVSAvoidcompatibility with low turn-on voltage devices

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the trigger mechanism from voltage-based (conventional ESD clamps) to current-based (parasitic bipolar transistor activation). By utilizing the parasitic bipolar transistor's turn-on characteristics, the ESD protection triggers at lower voltage levels, enabling protection of low turn-on voltage semiconductor devices while maintaining ESD protection functionality.

Inventive Principle:

Principle #35Parameter changes

2Power

If multiple-finger ESD protection devices are used, then current-carrying capability is increased, but uneven current distribution occurs among fingers

Engineering Contradiction:

Improvecurrent-carrying capabilityVSAvoidcurrent distribution uniformity

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The patent introduces asymmetric resistance elements (dummy resistors) in specific positions within the multiple-finger structure. These asymmetric elements compensate for the inherent resistance differences between fingers, forcing uniform current distribution across all fingers while maintaining the high current-carrying capability of the multi-finger configuration.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If multiple-finger ESD devices are used, then ESD protection performance is enhanced, but high snap-back behavior occurs

Engineering Contradiction:

ImproveESD protection performanceVSAvoidsnap-back behavior

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful snap-back behavior into a beneficial feature by utilizing the parasitic bipolar transistor's snap-back characteristic as the triggering mechanism. The snap-back effect, which normally causes uneven current distribution, is harnessed to activate the ESD protection at the appropriate moment, transforming a harmful phenomenon into the basis of the protection mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enhanced layout ensures uniform triggering of all fingers during an ESD event, effectively distributing current and enhancing the overall ESD protection performance by maximizing current-carrying capability and preventing device failure.

Implementation Method 1

the ESD protection device utilizes the body effect exhibited by the MOSFET device to activate a parasitic bipolar transistor at a lower voltage level

Methodology Applied

Scientific EffectParasitic bipolar transistor activation:

Implementation Method 2

the ESD protection device utilizes the body effect exhibited by the MOSFET device to activate a parasitic bipolar transistor at a lower voltage level

Methodology Applied

Scientific EffectBody effect:

Data Source

PatentUS10535649B2Enhanced layout of multiple-finger electrostatic discharge (ESD) protection device

Publication Date: 2020.01.14 INTERSIL AMERICAS INC

AI summary

An enhanced layout for a multiple-finger ESD protection device has several embodiments. In these embodiments, the base contacts of the NPN (or PNP) transistors utilized as voltage clamps in the multiple-finger NPN-based (or PNP-based) multiple-finger ESD protection device are disposed at opposite edges of the multiple-finger ESD protection device and oriented perpendicularly to the orientation of the fingers in the multiple-finger ESD protection device. Similarly, the body contacts of the NMOS (or PMOS) transistors utilized as voltage clamps in the multiple-finger NMOS-based (or PMOS-based) multiple-finger ESD protection device are disposed at opposite edges of the multiple-finger ESD protection device and oriented perpendicularly to the orientation of the fingers in the multiple-finger ESD protection device.