The etching of a secondary SiO2 target, target (2), by ions reflected from a primary SiO2 target, target (1), in a CHF3 plasma using various angles for the ions incident on target (1), 0(i), was examined. The etch rate of target (2) was enhanced by collision with reflected ions and the extent of etch-rate enhancement was significantly affected by the surface roughness of target (1). The extent and range of secondary etching increased when 0(i) was increased from 60degrees to 80degrees. Under the conditions used in this study, the maximum scattering angle for initiating secondary etching was nearly constant, at about 60degrees, irrespective of 0(i), when the latter was between 60degrees and 80degrees. When 0(i) was increased to 85degrees, the surface of target (1) was covered with a fluorocarbon polymer layer, which drastically decreased the extent of secondary etching. At 0(i) = 85degrees, the maximum scattering angle was lowered to about 40degrees and, as a result, the range of secondary etching was reduced.