FABRICATION OF BIFOCAL MICROLENSES ON INP AND SI BY AR ION-BEAM ETCHING

The fabrication process for the formation of bifocal microlenses on InP and Si substrates by Ar ion beam etching is described. Calculation and experimental results demonstrate that when InP and Si substrates coated with spherical photoresist mask are etched by Ar ion beams with reasonable etching parameters, the shape of the etched lenses will still be spherical and the curvature radius of the etched lens R = R(r)/k (where R(r) is the radius of the spherical photoresist mask, k is the etch ratio of the substrate to mask). Therefore during the etching process when the etching parameters such as ion beam energy or ion incident angle are suitably changed, a bifocal microlens will be realized.