Simple test structures have been used to evaluate the yield capabilities of a photoengraving process. The structures consist of meander tracks placed between two interdigitating sets of fingers so that electrical tests reveal both the breaks in the track and any shorts between the track and the fingers. This paper illustrates some aspects of the yield obtained with a standard positive resist photoengraving process applied to single-layer metallisation and to polysilicon over a range of feature sizes. Simple mathematical models are employed to convert yield data into fault density data and to conveniently express the dependence on feature size. The models are applicable to both test structures and circuits.
"Yield Detraction In Simple Photoengraving", Proc. SPIE 0394, Optical Microlithography II: Technology for the 1980s, (7 November 1983); doi: 10.1117/12.935138; https://doi.org/10.1117/12.935138