Patent ID: 8564135

Claim:
An image sensor, comprising: a first substrate including a light-receiving element configured to receive light from a first side of the first substrate; a second substrate bonded to a second side of the first substrate, wherein the second substrate comprises peripheral circuitry configured to process signals associated with the light-receiving element; an interlayer insulation layer positioned between the first substrate and the second substrate; a via hole formed through the interlayer insulation layer and the first substrate; a spacer formed on an inner sidewall of the via hole; an alignment key configured to fill the via hole; a barrier layer positioned between the spacer and the alignment key along an inner surface of the via hole; interconnection layers formed between the interlayer insulation layer and the second substrate with at least one layer of the interconnection layer coupled to the alignment key; and a pad formed on the first side of the first substrate and coupled to the alignment key.