Influence of SC-1/SC-2 cleaning on wafer-bonded silicon dioxide structures

Chemical element distributions and electrical properties of metal-oxide-semiconductor devices made of bond-and-etchback silicon-on-insulator materials were investigated. Three groups of devices with different bonded interface locations and prebonding cleaning procedures were compared. For the oxides that were cleaned with SC-1 (NH4OH:H2P2:H2O) and SC-2 (HCl:H2O2:H2O), secondary ion mass spectroscopy revealed higher concentrations of hydrogen at the bonded interface than deionized-water-cleaned oxides. In addition, total reflection x-ray fluorescence gave an indication of slightly higher metal contamination levels in the SC-1/SC-2-cleaned oxides. These devices were also more affected by bias temperature stress and charge injection by internal photoemission. Partial etchback of the bended oxides of SC-1/SC-2-cleaned devices made the top oxide crack at several locations.