An image sensor device is provided. A substrate has a photosensor region formed therein and/or thereon. An interconnection structure is formed over the substrate, and includes metal lines formed in inter-metal dielectric (IMD) layers. At least one IMD-level micro-lens is/are formed in at least one of the IMD layers over the photosensor region. Preferably, barrier layers are located between the IMD layers. Preferably, each of the barrier layers at each level has a net thickness limited to 100 angstroms or less at locations over the photosensor region, except at locations where the IMD-level micro-lenses are located. The IMD-level micro-lenses and the etch stop layers preferably have a refractive index greater than that of the IMD layers. A cap layer is preferably formed on the metal lines, especially when the metal lines include copper. An upper-level micro-lens may be located on a level that is above the interconnection structure.