Etching Observation of Stacking Faults in Thermally Oxidized Silicon

Abstract

Stacking faults in thermally oxidized silicon were examined by etching. The shape of stacking faults and their density distribution by depth became visible with additional 1HF-4HNO₃-1 acetic acid mixture etching after Sirtl etching.
Various shaped Frank sessile dislocations surrounding extrinsic stacking faults were observed. Generally, Frank loops were semicircular, though irregular, circular and hexagonal shaped loops and double layer stacking faults were also detected. It was proved that stacking faults were generated not only at the surface but into the bulk silicon several micrometers deep from the surface.
Stacking faults had relatively uniform size in “singly” oxidized silicon, however, their size varied in “multiply” oxidized silicon. The ratio of depth to length were about 0.3 and 0.15-1 for singly and triply oxidized (100) wafers, respectively.