| CPC H01L 22/30 (2013.01) [H01L 22/12 (2013.01); H01L 23/5226 (2013.01)] | 7 Claims |

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1. A multi-level interconnect structure, having a scatterometry test layer, comprising:
a patterned reflective layer, disposed on a substrate and comprising a first reflective pattern and a second reflective pattern separated from each other;
a bulk reflective layer, disposed directly on the patterned reflective layer; and
a patterned test layer, disposed over the bulk reflective layer,
wherein from a top view of the substrate, a ratio of a projected area of the patterned reflective layer to a projected area of the bulk reflective layer is between 0.75 and 0.90, and
wherein the first reflective pattern comprises a plurality of first conductive via patterns, the second reflective pattern comprises a plurality of second conductive via patterns, the first conductive via patterns and the second conductive via patterns are arranged in an array, and the first conductive via patterns with a smaller aperture are located between adjacent second conductive via patterns with a larger aperture.
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