Design, Fabrication and Testing of Nanoscale Gap Microlens Array Applied in Image Sensor

In this paper, a kind of nanoscale gap microlens array is designed and fabricated on 2.8um pixels based on 0.18um CMOS imager process to increase the photodetector sensitivity and to decrease the optical crosstalk. Both imaging techniques of SEM and atomic force microscopy (AFM) have been adopted to study surface structure. Especially, AFM´s probe can touch the sample surface and AFM is suitable all material surface. It is first to adopt the AFM to investigate the surface topography of microlens array that provide detailed topographical information about microlens features. As a result of this study, nanoscale gap microlens array has been successfully designed and fabricated whose gap is about 117nm. This nanoscale gap microlens array can be widely integrated onto photo-detector products to improve the light collection efficiency, increase the pixel fill factor and reduce the optical crosstalk.