Backside illuminated image sensor with shallow backside trench for photodiode isolation

A wafer level processing method for forming a plurality of image sensors each having a pixel array configured for backside illumination, the image sensors being formed utilizing an image sensor wafer, the image sensor wafer comprising a substrate and a sensor layer formed over the substrate, the method comprising:

• forming backside trenches in a backside surface of the sensor layer;
• implanting a dopant into the sensor layer through the backside trenches so as to form backside field isolation implant regions corresponding to the backside trenches;
• filling the backside trenches with a material;
• forming at least one antireflective layer over the filled backside trenches;
• attaching a temporary carrier wafer to the backside surface and removing the substrate;
• and
• after removing the substrate, further processing the image sensor wafer to form the plurality of image sensors including the pixel arrays for the plurality of image sensors.