1. A device used to shield selected areas of a semiconductor wafer during the manufacture of semiconductor components and integrated circuits. During the photolithography process, a set of photographic masks is required to define the openings in the oxide layer through which the various diffusions are made, the windows through which the metal contacts are formed, and the pattern in which the desired metal interconnections are formed. The photographic masks, or photomasks, are either emulsion on glass or an etched thin film of chromium or iron oxide on glass; they are produced by photographic reduction from large-scale layouts.

2. A device made from metal foil and used during the manufacture of thin-film circuits in order to define the pattern of material deposited as a thin film by vacuum evaporation on to the substrate.