Antireflection microstructures fabricated upon fluorine-doped SiO2 films

Two-dimensional periodic structures were fabricated upon a fluorine-doped S iO2 film in which the fluorine content changed gradually in the direction o f film thickness. The films were deposited by plasma-enhanced chemical-vapo r deposition. The film was periodically patterned into a 1-mum period and a n similar to1-mum-groove depth by inductive coupled plasma reactive-ion etc hing followed by chemical etching in a diluted HF solution. A surface refle ctance of 0.7% was attained at 1.85-mum wavelength, a value that is one fif th as large as the 3.5% Fresnel reflection of a SiO2 substrate with a flat surface. (C) 2001 Optical Society of America.