Power Semiconductor Devices With Separated Gate Metal Pads

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Solution Overview

Problem

The integration of clamp diodes across the edge termination in semiconductor devices leads to breakdown voltage degradation due to the interaction between electric fields in polysilicon clamp diodes and edge termination, which is not effectively addressed in prior art.

Innovation Solution

The use of separated gate metal pads to integrate MOSFETs with gate-drain clamp diodes and IGBTs with gate-collector clamp diodes, where the gate-drain clamp diodes are located outside the edge termination, eliminating the need for polysilicon clamp diodes over the termination area and thus preventing breakdown voltage degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If clamp diodes are formed using polysilicon layer across the edge termination, then avalanche capability is enhanced, but breakdown voltage of the main device is degraded

Engineering Contradiction:

Improveavalanche capabilityVSAvoidbreakdown voltage degradation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The gate electrode is divided into two separate metal pads (first gate metal pad and second gate metal pad) that are wire-bonded together through the lead frame. This segmentation allows the clamp diode to be formed outside the edge termination area, preventing the polysilicon from blocking the electric field in the termination region while still providing the desired avalanche capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The clamp diode structure is extracted from the edge termination area and relocated to the drift region outside the termination. By using a separate second gate metal pad connected via wire bond, the clamp diode function is removed from the critical termination region, eliminating the harmful interaction between polysilicon electric fields and the termination structure.

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If polysilicon clamp diodes are placed across the edge termination, then gate-drain clamp function is achieved, but electric field interaction with termination blocks breakdown voltage

Engineering Contradiction:

Improvegate-drain clamp functionVSAvoidelectric field blocking in termination

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

A wire bond serves as an intermediary connection between the first gate metal pad (inside termination) and the second gate metal pad (outside termination). This intermediary allows the clamp diode to function properly while keeping the polysilicon structure away from the edge termination, preventing electric field blocking.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8378411B2Power semiconductor devices integrated with clamp diodes having separated gate metal pads to avoid breakdown voltage degradation

Publication Date: 2013.02.19 FORCE MOS TECH CO LTD

AI summary

A structure of power semiconductor device integrated with clamp diodes having separated gate metal pads is disclosed. The separated gate metal pads are wire bonded together on the gate lead frame. This improved structure can prevent the degradation of breakdown voltage due to electric field in termination region blocked by polysilicon or gate metal.