Patent ID: 6979518

Claim:
An attenuating phase shift mask blank for use in lithography comprising: a substrate comprising a quartz or fluorinated quartz material; an etch stop layer deposited on said substrate comprising a metal selected from groups II, IV, V, transition metals, lanthanides and actinides, said etch stop layer exhibiting improved etch selectivity; a phase shifting layer disposed on said etch stop layer, the phase shifting layer comprising a composite material of formula A w B x N y O z , where A is an element selected from the group consisting of Groups IVA, VA, or VIA; and B is selected from the group consisting of an element from Groups II, IV, V, the transition metals, the lanthanides and the actinides; wherein w is from about 0.1 to about 0.6, x is from about 0 to about 0.2, y is from about 0 to about 0.6, and z is from about 0 to about 0.7; and said phase shift mask blank being capable of producing a photomask with substantially 180° phase shift and an optical transmission of at least 0.001% at a selected wavelength of <500 nm.