Phase detection pixels with stacked microlenses

An image sensor that includes a phase detection pixel group, the phase detection pixel group comprising:

• at least two phase detection pixels with respective photosensitive areas;
• at least two per-pixel microlenses that each cover a respective photosensitive area of the photosensitive areas;
• and
• a per-group microlens that covers all of the at least two phase detection pixels in the phase detection pixel group, wherein the per-group microlens overlaps the at least two per-pixel microlenses.

A front-side illuminated image sensor comprising:

• a substrate;
• first and second photosensitive areas in the substrate;
• dielectric layers formed over the substrate that include metal routing structures;
• first and second light pipes that guide light through the dielectric layers and that respectively overlap the first and second photosensitive areas;
• first and second microlenses that respectively overlap the first and second light pipes;
• and
• a third microlens that overlaps both the first and second microlenses.