Effect of dissolved oxygen on etching process of Si(111) in 2.5% NH3 solution

Etching processes of Si(111) in 2.5% NH3 solution (pH 12) were examined wit h attention to the effect of oxygen dissolved in the solution. Atomic force microscopy observation showed that many etch pits were formed on the surfa ce in the solution containing dissolved oxygen at high concentrations. In c ontrast, the surface was atomically flattened by removing dissolved oxygen from the solution. Infrared absorption spectroscopy revealed that the surfa ce was hydrogen-terminated after treatment with the solutions with and with out dissolved oxygen, and that dissolved oxygen degraded the homogeneity of the surface. It was also found that dissolved oxygen lowered the etching r ate of Si(111) in the solution. (C) 2000 Elsevier Science B.V. All rights r eserved.