Absorption enhancement structure for image sensor

A semiconductor device, comprising:

• a substrate comprising interior sidewalls defining a plurality of protrusions disposed along a back-side of the substrate;
• an image sensing element arranged within the substrate;
• one or more dielectric materials arranged along the back-side of the substrate over and between the plurality of protrusions;
• and
• wherein the interior sidewalls of the substrate respectively comprise a first segment that is oriented at a first angle of between approximately 45° and approximately 55° measured through the substrate with respect to a horizontal plane that is parallel to a front-side of the substrate.

A semiconductor device, comprising:

• a substrate comprising a first plurality of sidewalls defining a plurality of protrusions along a back-side of the substrate and further comprising a second plurality of sidewalls defining a ridge along the back-side of the substrate, the ridge continuously extending in a loop surrounding the plurality of protrusions;
• an image sensing element disposed within the substrate;
• and
• an isolation structure comprising a dielectric material vertically extending from an upper surface of the substrate defining a top of the ridge to a position that is below bottoms of the plurality of protrusions.