Transmission electron microscopy analysis of mechanical polishing-related damage in silicon carbide wafers

Abstract

The subsurface damage generated by mechanical polishing of silicon carbide wafers was investigated and quantified by plan view transmission electron microscopy (TEM) and atomic force microscopy (AFM). Damage generated during polishing using diamond abrasives with 0.5 µm particle size consists of dislocation loops with length up to 400 nm from the scratches. The total dislocation density was estimated at 5 × 1010 dislocations cm−2. TEM analysis of the Burgers vectors indicates that the initial perfect dislocations have a Burgers vector of b = a/3 ⟨11–20⟩-type with many dislocation dissociated into two partials with b = a/3 ⟨1–100⟩. The depth of damage was estimated to be up to 50 nm. 4H–SiC homoepitaxial layers grown on mechanically polished substrates without further surface treatment exhibit threading dislocation density along scratches in the order of 105 cm−1.