The effects of surface terminal bonds and microstructure of SiO2 aerogel ®lms on dry etching

The effects of microstructure and surface terminal bonds of SiO2 aerogel ®lms on dry etching were investigated using Ar, SF6, and C2F6 plasma gases. With Ar plasma etching, physical effect of ion bombardment on porous ®lm was found. In residue-free SF6 plasma etching, reactive etchant transport and high-mass ion bombardment were observed. With C2F6 plasma etching, ¯uorocarbon residue layer was revealed to maintain surface morphology as acting a barrier to radical transport and ion bombardment. An etching of 4508C-annealed SiO2 aerogel showed that a dense surface induced the decrease in reaction area, inhibition of etchant transport, and then uniform etching. # 2001 Elsevier Science B.V. All rights reserved