Diode-Integrated Isolated MOSFET for ESD and Latchup Protection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Isolated MOSFETs face a tradeoff between electrostatic discharge (ESD) and latchup performance due to parasitic circuit elements, making it difficult to achieve simultaneous optimal performance in integrated circuits.

Innovation Solution

Incorporating a diode with a first terminal connected to the isolation layer and a second terminal coupled to an isolation voltage source, which operates in reverse-bias mode during ESD events and forward-bias mode during latchup conditions, to steer current towards lower impedance paths and reduce voltage drops.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If isolated MOSFET structure is used to achieve electrical isolation, then different bias potentials can be applied to substrate and backgate, but parasitic circuit elements cause electrostatic discharge and latchup failures

Engineering Contradiction:

Improveelectrical isolation performanceVSAvoidelectrostatic discharge and latchup

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A diode is introduced as an intermediary component between the isolation layer and the substrate. The diode's anode is connected to the isolation layer and its cathode is connected to the substrate, serving as a mediator to control and redirect current flow during ESD and latchup events, thereby protecting the isolated MOSFET structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The diode changes its electrical parameters dynamically based on operating conditions. During normal operation, the diode is reverse-biased and blocks current flow to maintain isolation. During ESD events, the diode becomes forward-biased to provide a low-impedance discharge path, effectively changing its resistance parameter from high to low to protect the device.

Inventive Principle:

Principle #35Parameter changes

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 configuration enhances both ESD and latchup performance by providing strong resistance to current flow during ESD events and requiring higher trigger currents for latchup, thereby improving overall semiconductor device reliability.

Implementation Method 1

operates in reverse-bias mode during ESD events

Methodology Applied

Scientific EffectReverse bias: Diode

Implementation Method 2

forward-bias mode during latchup conditions

Methodology Applied

Scientific EffectForward bias: Diode

Data Source

PatentUS7741680B2Electro-static discharge and latchup resistant semiconductor device

Publication Date: 2010.06.22 ANALOG DEVICES INC

AI summary

The present invention relates to a semiconductor device including a substrate layer, a metal-oxide-semiconductor field-effect transistor (MOSFET), a backgate region, an isolation layer and a diode. The MOSFET includes a gate region, a source region and a drain region. The source and drain regions are embedded in the backgate region, which includes a voltage input terminal. The isolation layer is located between the backgate region and the substrate layer and has a doping type opposite that of the backgate region. The diode includes a first terminal connected to the isolation layer and a second terminal coupled to an isolation voltage source.