Improved scatterometry time to solution for leading-edge logic applications

Abstract

This paper describes an innovative approach to scatterometry modeling, significantly reducing time to solution compared to the industry's current best practices. One of the drawbacks to traditional scatterometry measurement techniques is the time required to optimize the model, which includes material optical constant extraction, model build time, initial model optimization, and model testing. A novel methodology that includes both stability and self-consistent scatterometry accuracy prediction can achieve an order of magnitude gain in productivity over prior methods. This technique creates opportunities among semiconductor chip manufacturers for wider scatterometry adoption at advanced technology nodes, where scatterometry is often the only reliable non-destructive metrology for device structure dimensions. The reductions in cycle time and improvements in accuracy prediction are keys to the success of scatterometry as an enabler for advanced process control and monitoring. This paper presents results on a conventional poly gate litho and final inspection and on leading-edge high-k metal gate after-etch applications. Spectroscopic ellipsometry is used to collect spectra from the gratings on the wafers. Then scatterometry results are obtained using the new approach and via traditional industryaccepted procedures to compare time to solution. To confirm the validity of the results, reference metrology data are collected on a CDSEM and TEM and the total measurement uncertainty is evaluated.

Scatterometry measurement for SiGe AEI sigma-shaped gate structures of 28nm technology

“…The development of additional optical technologies and modeling capabilities has extended scatterometry's measurement capability to today's more complex device structures on a broad range of process layers [2,3,4,5]. In particular, a newgeneration scatterometry tool, KLA-Tencor's SpectraShape 8810 using AcuShape2 modeling software, includes several enhanced and new optical technologies and advanced modeling capabilities [6,7] that provide the sensitivity required for production process control of complex structures for advanced design node devices. This paper discusses the scatterometry-based metrology measurement of 28nm SiGe after-etch inspection (AEI) Usigma shaped and V-sigma shaped gate structures.…”