Scatterometry performance enhancement by holistic approach

Abstract

Scatterometry performance enhancement is demonstrated through a holistic approach by utilizing comprehensive information from various sources, including data from different process steps, different toolsets, multiple structures, and multiple optical channels using samples from magnetic hard disk drive manufacturing. Parameter and spectrum feed-forward are performed across multiple targets at the photo step and the photo results are fed forward to the post-reactive ion etch (RIE) step. For an isolated structure with critical dimensions (CD) much smaller than the incident light wavelengths, feed-forward methods improve CD correlation with a general improvement of 20 to 60% in precision and fleet measurement precision (FMP). A second technique examined is hybrid metrology, where inputs from source tools, such as CD-SEM and CD-AFM, are used to determine critical parameters. Hybridization of line edge roughness results in CD and sidewall angle (SWA) FMP improvement of ∼60%. We also demonstrate improved CD accuracy using azimuthal scatterometry at 0, 45, and 90 deg azimuth angles measuring resist lines with CD larger than the incident light wavelengths. FMP reductions of ∼60 and 30% are obtained for CD and SWA. SWA hybridization after RIE results in CD and SWA FMP improvements by >50 and 30%, respectively.