The effect of defocus on the printability of sub-micron 5X reticle defects

Abstract

The effect of defocus on the printability of sub-micron 5X reticle defects is assessed by both practical experiment and computer simulation. A specifically designed test reticle incorporating defects whose size, and proximity to adjacent features, varies within sub-micron line/space arrays was printed onto silicon wafer substrates under production conditions. The results were assessed and are presented by plotting minimum printed defect (MPD) vs. array linewidth (L/W). Computer simulation of the same test reticle was then carried out and similar graphs plotted. In addition, the results were replotted as curves of MPD vs. defocus. Finally, the resist modelling program SOLID has been used to create 3D images of the printed defects and thus demonstrate the effect caused by defocus on the resist profiles. Results on defect printability enable future reticle procurement specifications to be established.