Nanoscale insights on the origin of the Power MOSFETs breakdown after extremely long high temperature reverse bias stress

TL;DR

This study investigates the nanoscale mechanisms behind the dielectric breakdown in 4H-SiC power MOSFETs after prolonged high temperature reverse bias stress, highlighting the role of threading dislocations in device failure.

Contribution

It provides new nanoscale insights linking threading dislocations to breakdown locations, clarifying failure mechanisms in 4H-SiC MOSFETs after long-term stress.

Findings

Breakdown correlates with threading dislocations.

Dislocations exhibit conductive behavior and alter carrier concentration.

Dislocations are key to understanding device failure after HTRB stress.

Abstract

In this work, the origin of the dielectric breakdown of 4H-SiC power MOSFETs was studied at the nanoscale, analyzing devices that failed after extremely long (three months) of high temperature reverse bias (HTRB) stress. A one-to-one correspondence between the location of the breakdown event and a threading dislocation propagating through the epitaxial layer was found. Scanning probe microscopy (SPM) revealed the conductive nature of the threading dislocation and a local modification of the minority carriers concentration. Basing on these results, the role of the threading dislocation on the failure of 4H-SiC MOSFETs could be clarified.