BONDING PAD ON A BACK SIDE ILLUMINATED IMAGE SENSOR

摘要

A bonding pad structure for an image sensor device and a method of fabrication thereof. The image sensor device has a radiation-sensor region including a substrate and a radiation detection device, and a bonding pad region including the bonding pad structure. The bonding pad structure includes: an interconnect layer; an interlayer dielectric layer (IDL), both layers extending from under the substrate into the bonding pad region; an isolation layer formed on IDL; a conductive pad having a planar portion and one or more bridging portions extending perpendicularly from the planar portion, through the IDL and isolation layers, and to the interconnect layer; and a plurality of non-conducting stress-releasing structures disposed between the isolation layer and the conductive pad in such a way to adjoin its planar and the bridging portions together for releasing potential pulling stress applied thereon and preventing a conductive pad peeling.

主权项

1. An image sensor device, comprising:
a substrate having a front surface, a back surface, and a sidewall perpendicular to the front and back surfaces; a radiation-detection device formed in the substrate, the radiation-detection device being operable to detect radiation waves that enter the substrate through the back surface; an interconnect structure formed on the front surface of the substrate, the interconnect structure having an extended portion that extends beyond the sidewall of the substrate; and a bonding pad structure comprising:
an interlayer dielectric layer formed on the extended portion of the interconnect structure;an isolation layer formed on the interlayer dielectric layer;a conductive pad having a planar portion formed on the isolation layer, and one or more bridging portions extending generally perpendicularly from the planar portion, through the interlayer dielectric and the isolation layers, and to the interconnect structure for establishing electric contact therewith; and a plurality of non-conducting stress-releasing structures disposed between the isolation layer and the planar portion of the conductive pad in such a way to adjoin the planar and the bridging portions of the conductive pad together.