A method to fabricate micro lens array with different diameters

Micro lens arrays are applied to several areas, such as imaging reconstruction and organic light emitting diode light extraction. Researchers have studied on how to increase the efficiency of luminous current and luminous power of an organic light-emitting device (OLED) by using several spheres with different diameters. A method to fabricate a micro lens array with diameters is presented in this paper. By using negative photoresist as a boundary confinement, we can make micro lenses with different diameters on a single thermal reflow process. Unlike traditional method, this method does not suffer tight thermal dose control because the photoresist reflow can be confined effectively by pre-patterned negative photoresist boundaries. The experimental results show that 200 μm and 50 μm micro lens were made successfully on a single wafer by one-time thermal dose.