The Origin and Formation Mechanism of an Inclined Line‐like Defect in 4H‐SiC Epilayers

Abstract

The origin and the formation mechanism of a surface morphological defect in 4H‐SiC epilayers are reported. The defect appears on the surface of an epilayer as an inclined line‐like feature at an angle of ±80° to the step‐flow direction . The defect is confirmed to originate from a threading screw dislocation intersecting the surface and its orientation is controlled by the sign of the Burgers vector of the dislocation. The defect forms through the interaction of local spiral growth associated with threading screw dislocations and step‐flow growth related to the substrate offcut. The defect mainly appears in the epilayers grown through chloride‐based chemistry, where in situ surface preparation of the substrate is performed in H2 + HCl at a relatively high temperature.

Influence of Different Hydrocarbons on Chemical Vapor Deposition Growth and Surface Morphological Defects in 4H‐SiC Epitaxial Layers

“…[ 29 ] Increasing the C/Si ratio eliminates SSBs but leads to the formation of ILL surface morphological defects (Figure 5b–e). [ 25 ] Notably, two different orientations of the ILL defects can be observed, with angles of +80 and −80 degrees to the step‐flow direction. Most importantly, no such defects are observed when growth is performed using as a C source even with a high C/Si ratio.…”

“…The origin and formation mechanism of ILL surface morphological defects on 4 H‐SiC epitaxial layers are discussed in detail in ref. [25]. There we have demonstrated that TSDs present in the substrate are responsible for the formation of such defects.…”

“…We have observed that the use of different hydrocarbon sources in chloride‐based chemistry has a significant influence on the surface quality and formation of surface morphological defects such as short step bunching (SSB) and inclined line‐like (ILL) defects, [ 25 ] as well as the structure of extended defects like triangular defects.…”

Influence of Growth Process on Suppression of Surface Morphological Defects in 4H-SiC Homoepitaxial Layers

“…The main destructive defects are instant surface dislocation (BPD) defects and stacking faults (SF), which are likely to continuously increase the on-resistance of bipolar devices [25][26][27][28][29][30][31][32][33][34][35]. Surface defects, such as dump, scratch, particle, downfall (DF), triangle (TD), comet and carrot defects, are typically detrimental and easily observable, and often lead to device failure [36][37][38][39][40][41][42]. Therefore, one of the main challenges in 4H-SiC epitaxial growth is to decrease the defect density of the epitaxial layer.…”

“…The main destructive defects are instant surface dislocation (BPD) defects and stacking faults (SF), which are likely to continuously increase the on-resistance of bipolar devices [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Surface defects, such as dump, scratch, particle, downfall (DF), triangle (TD), comet and carrot defects, are typically detrimental and easily observable, and often lead to device failure [ 36 , 37 , 38 , 39 , 40 , 41 , 42 ].…”