photomask
noun
pho·to·mask ˈfō-tō-ˌmask 
plural photomasks
: a pattern of opaque material used to shield selected areas of a surface (as of a semiconductor) in deposition or etching (as in producing an integrated circuit) : mask sense 3d
Word History
Etymology
photo- + mask entry 1
First Known Use
1963, in the meaning defined above