A semiconductor device having a substrate with at least one photo-detecting region and at least one bond pad is provided. A first passivation layer is deposited over the substrate and over step portions at the edges of the bond pad and a trench having sidewalls and a bottom surface is formed in the substrate. A light shielding layer is deposited over the first passivation layer and covering the trench sidewalls. The light shielding layer has end portions at the photo-detecting region, at step portions at the edges of the bond pad and at the bottom surface of the trench. A second passivation layer is deposited over the light shielding layer. A third passivation layer is deposited over the end portions of the light shielding layer at the photo-detecting region and at the step portions at edges of the bond pad.