Structure and formation method of light sensing device

A light sensing device, comprising:

• a semiconductor substrate;
• a filter element over the semiconductor substrate;
• a light sensing region below the filter element;
• a light shielding element over the semiconductor substrate and surrounding a lower portion of the filter element;
• and
• a dielectric element over the light shielding element and surrounding an upper portion of the filter element, wherein a top width of the light shielding element and a bottom width of the dielectric element are different from each other, and an entirety of the dielectric element is above a top surface of the light shielding element.

A light sensing device, comprising:

• a semiconductor substrate;
• a filter element over the semiconductor substrate, wherein the filter element has a first portion and a second portion;
• a first dielectric element over the semiconductor substrate and surrounding the first portion of the filter element;
• and
• a second dielectric element over the first dielectric element and surrounding the second portion of the filer element, wherein a top width of the first dielectric element is greater than a bottom width of the second dielectric element.