Structures and formation methods of a light sensing device are provided. The light sensing device includes a semiconductor substrate and a filter element over the semiconductor substrate. The light sensing device also includes a light sensing region below the filter element and a light shielding element over the semiconductor substrate and surrounding a lower portion of the filter element. The light sensing device further includes a dielectric element over the light shielding element and surrounding an upper portion of the filter element. A top width of the light shielding element and a bottom width of the dielectric element are different from each other.