In-Situ Ellipsometric Study of Aqueous NH(4)OH Treatment of Silicon

摘要

In-situ ellipsometry at a wavelength of 632.8nm is used to analyze silicon surfaces in an aqueous NH4OH ambient. The ellipsometric data indicate that a surface which is optically quite similar to bare Si is obtained when the native SiO2 film is etched from a Si substrate by aqueous NH4OH. In contrast, the surface obtained by etching the native oxide in aqueous buffered HF4 leads to formation of a residual film on the Si substrate. Roughening of sample surfaces treated with either aqueous NH4OH or BHF is observed by microscopy. The high degree of roughness obtained following NH4OH treatment appears to influence ellipsometric measurements on samples, but this influence is not observed following BHF exposure where less roughness is noted.