Suppression of stacking-fault expansion in 4H-SiC PiN diodes using proton implantation to solve bipolar degradation

Abstract

Abstract4H-SiC has been commercialized as a material for power semiconductor devices. However, the long-term reliability of 4H-SiC devices is a barrier to their widespread application, and the most important reliability issue in 4H-SiC devices is bipolar degradation. This degradation is caused by the expansion of single Shockley stacking-faults (1SSFs) from basal plane dislocations in the 4H-SiC crystal. Here, we present a method for suppressing the 1SSF expansion by proton implantation on a 4H-SiC epitaxial wafer. PiN diodes fabricated on a proton-implanted wafer show current–voltage characteristics similar to those of PiN diodes without proton implantation. In contrast, the expansion of 1SSFs is effectively suppressed in PiN diodes with proton implantation. Therefore, proton implantation into 4H-SiC epitaxial wafers is an effective method for suppressing bipolar degradation in 4H-SiC power-semiconductor devices while maintaining device performance. This result contributes to the development of highly reliable 4H-SiC devices.

Effects of proton implantation for expansion of basal plane dislocations in SiC toward suppression of bipolar degradation: review and perspective

“…To apply the proton implantation method in SiC devices, we fabricated PiN diodes with proton implantation. 46) Although we have also performed proton implantation during or after the PiN diode fabrication processes, the fabricated diodes have exhibited significantly high on-resistance, as reported in previous studies. [63][64][65] This increase of on-resistance would be caused by trapping of electrons and reduction of the electron mobility due to defects induced by damages of the proton implantation.…”

“…62) Based on these insights, our study focused on proton implantation, a technique already used extensively in semiconductor processes. 43,[45][46][47] 4. Proton implantation…”

“…We have discussed ion implantation techniques to reduce the carrier lifetime in drift layers, 43,44) and recently presented proton implantation as a novel approach. [45][46][47] This paper reviews the mechanisms behind dislocation mobility reduction and effects of ion/ proton implantation on suppressing the BPD expansion. We also provide perspectives on the developed technique based on a comparative discussion with other methods and discuss whether proton implantation can be a last resort approach for solving bipolar degradation.…”

Suppression of partial dislocation glide motion during contraction of stacking faults in SiC epitaxial layers by hydrogen ion implantation

“…One of the critical issues that hinder the widespread use of SiC power devices is the bipolar degradation phenomenon. [17][18][19][20][21] SiC bipolar devices such as pin diodes and insulated gate bipolar transistors face problems with defect-related degradation, in which the forward voltage is degraded due to the spontaneous expansion of single Shockley-type stacking faults (SFs) in the epitaxial layer during forward bias application. The SFs expand from basal plane dislocations (BPDs) to accommodate the glides of partial dislocations.…”

“…35,36) Recently, we have reported that proton irradiation, which is commonly used in semiconductor processing, can suppress SF expansion in the SiC epitaxial layer driven by ultraviolet (UV) illumination and forward bias application. 21,37) Although we carefully separated the effect of change in carrier lifetimes on the driving force of SF expansion and the effect of the pinning of dislocations by proton implantation, the relationship between dislocation mobility and proton implantation has remained unclear. In the present study, we investigated the contraction behavior of SFs subjected to proton implantation and revealed the relationship between dislocation mobility and proton implantation.…”