Characterization and modeling of the nitrogen passivation of interface traps in SiO2/4H–SiC

Abstract

The relationship between nitrogen content and interface trap density (Dit) in SiO2/4H–SiC near the conduction band has been quantitatively determined. Nitridation using NO significantly reduces Dit near the conduction band, but the effect saturates after ≈2.5×1014 cm−2 of nitrogen. These results are consistent with a model of the interface in which defects such as carbon clusters or silicon suboxide states produce traps with energies corresponding to the sizes of the defects. Nitrogen passivation results in the dissolution of the defects, which then lowers the energies of the traps in the band gap.

Fixed nitrogen atoms in the SiO2/SiC interface region and their direct relationship to interface trap density

“…Previously, it was believed that incorporated nitrogen atoms of $10 14 cm À2 were distributed in the oxide side of a nitrided SiO 2 /SiC interface. 12 However, our findings suggest a new model that nitrogen atoms are not only embedded in the oxide layer but also fixed in the SiO 2 / SiC interface region.…”

“…Although the reason for such a threshold remains unclear at present, a similar trend has been reported in a previous study. 12 Finally, the reason why nitrogen atoms incorporated into the SiO 2 /SiC interface region are not removed by HF etching is discussed. There are two possible mechanisms that fix nitrogen atoms in the interface region.…”

Nanoscale transport properties at silicon carbide interfaces

“…Furthermore, for nitrided oxides, XPS showed that the complex suboxide and oxide-carbon bonds were removed, thus being accompanied by the formation of strong Si N bonds and the significant reduction of the spectral intensity of C-C bonds [127]. Mc Donald et al [128] studied the reduction of the interface states density by NO-nitridation, observing a saturation effect upon a nitrogen incorporation level of 2.5×10 14 cm 2 . The presence of such saturation is consistent with a model of the interface in which large clusters composed of an excess of interfacial carbon or silicon are subsequently passivated (and dissolved) by the indiffusing nitrogen, with the formation of strong C N and Si N bonds.…”

SiC/SiO2 Interface Characteristics in N-based 4H-SiC MOS Capacitor Fabricated with PECVD and NO Annealing Processes

“…하지만 SiC/SiO2 구조는 Si/SiO2 대비 계면 포획 밀도가 약 100배 수준으로 높기 때문에 MOSFET 제작에 응용 할 경우 반전 채널에서의 전자 이동도가 5cm 2 /Vs 수 준으로 낮아 전류 구동 능력이 물성의 기대치에 현저 히 못 미치는 문제점을 가지고 있다 [3] . 질소-패시베이 션을 이용하여 계면 포획 농도를 감소시키는 방법이 잘 알려져 있지만, SiC의 표면에서 SiO2를 성장시킬 때 형성되는 구조적 결함들을 모두 해결할 수 없다는 한계 또한 존재하고 있다 [4] . 이에 다른 산화막 물질 [5] , 산화막을 형성하는 다른 방법 [6] 및 질소-패시베이션 의 대체 공정 개발 [7], [8] 등 다양한 방향으로 SiC/SiO2…”