Extending the life of TTL-alignment steppers to 65-nm technology

When older manufacturing tools are used to run newer technologies in high volume, additional expenditures are often made to either improve controls on those tools, to upgrade the tools, or to purchase newer tools to get the job done. This paper explores the use of older ASML steppers with TTL alignment to achieve overlay metrics that allow them to be used for 65-nm technology, using the existing alignment system to align to the previous layer scribe-line marks, which were intended for more modern off-axis alignment systems. By using this previously untapped capability, costly upgrades or tool replacements are avoided.