Required metrology and inspection for nanoimprint lithography

Abstract

We summarize the metrology and inspection required for the development of nanoimprint lithography (NIL), which is recognized as a candidate for next-generation lithography. Template inspection and residual layer thickness (RLT) metrology are discussed. An optical-based inspection tool for replica template inspection showed sensitivity for defects below 10 nm with sufficient throughput. For the RLT control, in-die RLT metrology is needed. Because the metrology requires dense sampling, optical scatterometry is the best solution owing to its ability to measure profile features nondestructively with high throughput. For in-die metrology, we have developed a new hybrid metrology that can combine key information from these complex geometries with scatterometry measurements to reduce the impact on the RLT measurement due to the layers beneath the resist. The technologies discussed here will be important when NIL is applied for IC manufacturing, as well as in the development phases of those lithography technologies.