Method of manufacturing image sensor having enhanced backside illumination quantum efficiency

摘要

A system and method for image sensing is disclosed. An embodiment comprises a substrate with a pixel region and a logic region. A first resist protect oxide (RPO) is formed over the pixel region, but not over the logic region. Silicide contacts are formed on the top of active devices formed in the pixel region, but not on the surface of the substrate in the pixel region, and silicide contacts are formed both on the top of active devices and on the surface of the substrate in the logic region. A second RPO is formed over the pixel region and the logic region, and a contact etch stop layer is formed over the second RPO. These layers help to reflect light back to the image sensor when light impinges the sensor from the backside of the substrate, and also helps prevent damage that occurs from overetching.

主权项

1. A method of manufacturing a backside illuminated image sensor, the method comprising:
receiving a substrate with a pixel region and a logic region, the substrate comprising a first side and a second side opposite the first side; forming a first active device in the pixel region, wherein the first active device is at least partially located on the first side of the substrate and wherein the first active device comprises a photosensitive element; forming a second active device in the logic region at least partially located on the first side of the substrate; depositing a first protective layer over the first side of the substrate; removing the first protective layer from the logic region without removing the first protective layer over the pixel region; depositing a second protective layer over the logic region and the first protective layer in the pixel region; forming a dielectric reflector by depositing a contact etch stop layer over the second protective layer, wherein the dielectric reflector is located to reflect light to the photosensitive element; forming a first silicide contact on a top surface of the first active device, wherein a major surface of the substrate located in the pixel region is free from silicide; and forming a second silicide contact on the major surface of the substrate in the logic region.