Angular Dependence of Si 3 N 4 Etching in C 4 F 6 /CH 2 F 2 /O 2 /Ar Plasmas

The dependence of Si 3 N 4 etching on ion‐incident angles is investigated at various CH 2 F 2 flow rates in C 4 F 6 /CH 2 F 2 /O 2 /Ar plasmas. The normalized etch yield (NEY) curves for Si 3 N 4 imply that physical sputtering is a major contributor to Si 3 N 4 etching. An increase in the amount of CH 2 F 2 in the plasma produces thicker and more etch‐resistant fluorocarbon films. Systematic analyses on deposition and etching of the passively deposited fluorocarbon films on Si 3 N 4 in a C 4 F 6 /CH 2 F 2 /O 2 /Ar plasma show that the normalized deposition rate of the fluorocarbon film is nearly the same and unaffected by the CH 2 F 2 flow rate while etching of fluorocarbon films is similar to etching of Si 3 N 4 , thus, etching of the fluorocarbon film, rather than its deposition, limits Si 3 N 4 etching in C 4 F 6 /CH 2 F 2 /O 2 /Ar plasmas.