GaN Vertical FET With Merged PiN Schottky Diode

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Solution Overview

Problem

Conventional nitride semiconductor devices with SBD protectors fail to fully utilize the high breakdown voltage characteristics of vertical FETs due to limited breakdown voltage, and replacing SBD with PN diodes increases conduction loss.

Innovation Solution

A nitride semiconductor device with a vertical GaN transistor and a merged PiN Schottky (MPS) diode connected in parallel, featuring discrete openings to enhance breakdown voltage and reduce conduction loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If an SBD protector is used in parallel with the vertical FET, then the device structure is simple with high current capability, but the breakdown voltage characteristics are limited and cannot fully utilize the inherent high breakdown voltage of the vertical FET

Engineering Contradiction:

Improvestructure simplicityVSAvoidbreakdown voltage characteristics

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent merges the PiN diode and Schottky barrier diode into a single integrated MPS diode structure. The PiN region provides high breakdown voltage capability while the Schottky contact region provides low forward voltage drop, allowing the device to simultaneously achieve high breakdown voltage characteristics and low conduction loss without requiring separate parallel components

Inventive Principle:

Principle #5Merging (Combining)

2Loss of energy

If an SBD protector is used, then the device has low conduction loss, but the breakdown voltage is limited and cannot achieve high breakdown voltage characteristics

Engineering Contradiction:

Improveconduction lossVSAvoidbreakdown voltage

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The MPS diode combines the PiN structure (providing high breakdown voltage) and Schottky contact structure (providing low forward voltage) into a single device. This merging allows simultaneous achievement of high breakdown voltage and low conduction loss, resolving the trade-off between these two parameters

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If a PN diode is used instead of SBD, then the breakdown voltage increases, but the conduction loss increases as well

Engineering Contradiction:

Improvebreakdown voltageVSAvoidconduction loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The MPS diode merges the PiN diode structure (high breakdown voltage) with Schottky contact structure (low forward voltage) to create a single device that achieves both high breakdown voltage and low conduction loss, eliminating the need to choose between these conflicting characteristics

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10193001B2Nitride semiconductor device

Publication Date: 2019.01.29 PANASONIC HOLDINGS CORP

AI summary

A nitride semiconductor device is provided that includes: a substrate; an n-type drift layer above the front surface of the substrate; a p-type base layer above the n-type drift layer; a gate opening in the base layer that reaches the drift layer; an n-type channel forming layer that covers the gate opening and has a channel region; a gate electrode above a section of the channel forming layer in the gate opening; an opening that is separated from the gate electrode and reaches the base layer; an opening formed in a bottom surface of said opening and reaching the drift layer; a source electrode covering the openings; and a drain electrode on the rear surface of the substrate.