Polyimide as the pedestal of batch fabricated micro-ball lens and micro-mushroom array

The paper presents an innovative process to fabricate micro-ball lenses and micro-mushroom arrays. The new batch fabrication idea is a simple process with one mask and easily integrated in the planar substrate. The integrated micro-ball lens is no longer a dream. With proper heat treatment of high aspect ratio photoresist on a polyimide pedestal, micro-ball lenses and micro-mushroom arrays are easily fabricated. The fabrication result shows that the reflowed shape depends on the diameter and height of the photoresist pattern. The theory, fabrication and result are discussed.