US Patent 10073239 Dual photodiode for phase detection autofocus

A phase detection autofocus image sensor includes a first photodiode in a plurality of photodiodes disposed in a semiconductor material and a second photodiode in the plurality of photodiodes. A first pinning well is disposed between the first photodiode and the second photodiode, and the first pinning well includes a first trench isolation structure that extends from a first surface of the semiconductor material into the semiconductor material a first depth. A second trench isolation structure is disposed in the semiconductor material and surrounds the first photodiode and the second photodiode. The second trench isolation structure extends from the first surface of the semiconductor material into the semiconductor material a second depth, and the second depth is greater than the first depth.