J. Rappich et al., Is there a limit for the passivation of Si surfaces during anodic oxidation in acidic NH4F solutions?, ELECTR ACT, 45(28), 2000, pp. 4629-4633
The interface state densities of wet anodic oxide layers on Si are normally
very high and, therefore, there is need for special post-treatments. Repet
itive oxidation/hydrogenation cycles in the current oscillating regime lead
to improved passivation of the SiO2/Si interface. The atomic force microsc
opy (AFM) images reveal the formation of macroscopically rough surfaces (ho
les with a diameter of at least 100 nm and a depth of up to 10 nm). This ki
nd of surface structure is more favourable to decrease the strain induced b
y the Si-O-Si bond angle mismatch. This peculiarity of Si surfaces conditio
ning in acidic NH4F solutions leads to a reduction of the defect concentrat
ion at the SiO2/Si interface without further processing. (C) 2000 Elsevier
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