Multiple layer techniques in optical lithography: Applications to fine line mos production

The theory and practical concerns of multi-layer techniques using an anti-reflective polymer coating will be discussed. Anti Reflective Coating (ARC, Brewer Science, Inc.) was incorporated into the metal lithography process for a 1.2 micron gate CMOS prototype production line. Previously, reflections from substrate topography had caused a loss in linewidth control. These reflections were minimized by the ARC, which also restored process latitude. For the process described, ARC coating uniformity was nm, adhesion was good, and step coverage was seen to be adequate to 0.8 micron high verticle wall steps.