K. Awazu et al., Formation of individual holes in amorphous SiO2 by swift heavy-ion bombardment followed by wet and dry etching, JPN J A P 1, 39(12B), 2000, pp. 7058-7059
Individual holes in amorphous SiO2 were formed from latent tracks which wer
e introduced by bombardment with swift iodine ions. Hole contours strongly
depend on the etching method used. Conic holes with the highest aspect rati
o were obtained by etching with 48% hydrofluoric acid, The aspect ratio of
the holes increased with the acidity of the hydrofluoric acid. Selective et
ching of the latent tracks was not observed with reactive ion etching, yet
48% hydrofluoric acid etching followed by reactive ion etching formed colum
nar holes. The etching mechanism is briefly discussed.