Cavityless chip-scale image-sensor package

A cavityless chip-scale image-sensor package comprising:

• a substrate that includes a plurality of pixels forming a pixel array;
• a microlens array that includes a plurality of microlenses each (i) having a lens refractive index, (ii) being aligned to a respective one of the plurality of pixels, and (iii) having a non-planar microlens surface facing away from the respective one of the plurality of pixels;
• a low-index layer having a first refractive index less than the lens refractive index, and a bottom surface, at least part of which is conformal to each non-planar microlens surface, the microlens array being between the pixel array and the low-index layer;
• and
• a bonding layer adjoining the low-index layer such that the low-index layer is between the microlens array and the bonding layer;
• and
• a cover glass disposed on the bonding layer opposite the low-index layer,
• the bonding layer and the cover glass having a second refractive index and a third refractive index respectively, each exceeding the first refractive index.