Quantitative Analysis of Etching Rate Profiles for 11B+-Implanted Si3N4 Film

Abstract
Etching rate enhancement for 11B+-implanted Si3N4 film was investigated both experimentally and theoretically. The etching solution was concentrated H3PO4 at ∼165°C. Film thicknesses were precisely measured by ellipsometry. Enhancement resulted from Si-N bond breaking. This was confirmed by a decrease of infrared absorption at a 12.0 µm wavelength for Si-N bond vibration. Main and additional peaks were observed in the etching rate profile. The former was due to nuclear damage and was well represented by the calculated etching rate profile deduced from the nuclear deposited energy density distribution. The latter existed in the surface region only when the ion projected range was shorter than the film thickness. This peak was possibly caused by charge accumulation in the insulating Si3N4 film during 11B+ implantation.