Copper decoration and etching of crystal defects in SOI materials

Abstract

Crystal defects in Silicon-On-Insulator (SOI)-wafers can be delineated with etching solutions. To visualize even small defects (of some nanometer in size) a combination of copper decoration of the defects and subsequent defect etching may be applied. A shortcoming of copper decoration is the possible formation of artefacts on the SOI-film which appears like defects and gives rise to much higher defect densities. Results of defect etching studies without and with copper decoration of defects in SOI are presented. A new defect-type called “red spot” has been discovered in copper decorated SOI-wafers. These defects are located at the interfaces of SOI-film/Buried oxide (BOX) and BOX/Si substrate and very likely nucleate at grown-in crystal defects of the CZ silicon or defects induced by the SOI fabrication process.