US Patent 8202681 Hybrid multi-layer mask

A hybrid mask set for exposing a plurality of layers on a semiconductor substrate to create an integrated circuit device is disclosed. The hybrid mask set includes a first group of one or more multi-layer masks (MLMs) for a first subset of the plurality of layers. Each MLM includes a plurality of different images for different layers, the images being separated by a relatively wide image spacer. The hybrid mask set also includes a first group of one or more production-ready masks for a second subset of the plurality of layers. Each production-ready mask includes a plurality of similar images for a common layer, each image being separated by a relatively narrow scribe street.