IMAGE SENSORS WITH DIFFRACTIVE LENSES IN A SEMICONDUCTOR SUBSTRATE

An image sensor may include an array of imaging pixels. Each imaging pixel may have a photosensitive area formed in a semiconductor substrate that is covered by a respective microlens that focuses light onto the photosensitive area. Each imaging pixel may also include a diffractive lens formed in the semiconductor substrate. The diffractive lens may spread light to increase the average path length of incident light within the photosensitive area and increase efficiency of the pixel. An additional diffractive lens may be formed over the semiconductor substrate to focus light onto the diffractive lens and further improve efficiency. Multiple diffractive lenses may be formed in the semiconductor substrate of a single imaging pixel. The diffractive lenses may be multipart diffractive lenses.