Image Sensor Comprising Reflective Guide Layer and Method of Forming the Same

A method comprising:

• forming an insulating layer over a backside of a substrate, the substrate comprising a photo diode, an interconnect structure being on a front side of the substrate;
• forming a recess in the insulating layer, the recess extending only partially through the insulating layer, the recess being aligned above the photo diode;
• forming a reflective guide layer along sidewalls of the recess, a bottom of the recess being free of the reflective guide layer;
• forming a color filter in the recess, a portion of the insulating layer being between the color filter and an adjacent color filter;
• and
• forming a lens over the color filter such that the color filter is interposed directly between the lens and the substrate.

A structure comprising:

• a substrate comprising a plurality of photo diodes;
• an interconnect structure on a first side of the substrate;
• an insulating layer on a second side of the substrate, the insulating layer comprising a plurality of recesses, each of the plurality of recesses being aligned above a respective one of the plurality of photo diodes;
• a reflective guide material on sidewalls of each of the recesses, a bottom of each of the recesses being free of the reflective guide material;
• color filters each being in a respective one of the recesses, an upper surface of the reflective guide material, an upper surface of the color filters, and an upper surface of the insulating layer being level;
• and
• lenses each being on a respective one of the color filters.