Figure 3

SEM micrographs of the Si surface of sample 1 after RIE through PAA film and alumina dissolution. Three different gas mixtures were used for etching, which are indicated on top of the images. The etching duration was 20 s. Micrographs 1 of (a), (b), and (c) are cross-sectional images of the PAA layer/Si stack, while micrographs 2 and 3 are plane view SEM images (slightly tilted in images 2 of (a), (b), and (c); at vertical e-beam incidence in images 3).