New high fill-factor dual-curvature microlens array fabrication using UV proximity printing

A new method to fabricate a high fill-factor dual-curvature microlens array using the proximity printing in lithography process is reported. The technology utilized the UV proximity printing by controlling a printing gap between the mask and substrate. The designed high density microlens array pattern can produce high fill-factor dual-curvature microlens array in photoresist. It is due to the UV light diffraction to deflect away from the aperture edges and produce a certain exposure in photoresist material outside the aperture edges. This method can precisely control the geometric profile of high fill factor dual-curvature microlens array. The experimental results showed that the dual-curvature micro-lens array in photoresist could be formed automatically when the printing gap ranged from 360 to 600 μm. The gapless dual-curvature microlens array will be used to enhance of luminance and uniformity for light-emitting diodes.