The Role Of Strong Phase Shift Masks In Intel'S Dfm Infrastructure Development

Intel has reported on three separate styles and applications of strong phase shift masks (PSMs) over the last decade including alt-PSM for gate patterning(1), alt-PSM with assist features for contact patterning(2) and Pixelated Phase Masks (PPMs) for metal layer patterning(3). Each had a prominent role in Intel's Design For Manufacturing (DFM) infrastructure development in terms of design rules and DFM tooling. By gradually inserting design rule changes for alt-PSM for gate patterning starting from the 130nm technology node, density and design impact were minimally effected. Alt-PSM for contact layer required development of complex methods of SRAF placement and coloring while also forcing advances in phase shift mask manufacturing infrastructure. Pixelated phase masks for metal patterning when combined with Inverse Lithography Techniques (ILTs) were successful in supporting a high level of flexibility for metal design rules including multiple feature sizes, pitches and two-dimension content.