Method for making long focal length micro-lens for color filters

摘要

A method for making long focal length micro-lens for color filters in CMOS image sensor applications and device made by the method are described. In the method, a layer of micro-lens material is first spin coated on top of a color filter, patterned by a photolithographic method into at least four discrete regions, and preferably at least nine discrete regions for each micro-lens with a pre-set spacing therein between. The discrete regions allow a smaller volume of micro-lens material to be used for forming the micro-lens in a subsequent reflow process. The micro-lens formed by the present invention novel method has a focal length of at least 7 mum, and preferably at least 10 mum such that a 0.35 mum technology CMOS image sensor utilizing two or three layers of metal conductors can be formed by the present invention method.