Metrology characterization of spacer double patterning by scatterometry

Abstract

Spacer defined double patterning processes consists of multiple deposition, post strips and etch steps and is inherently susceptible to the cumulative effects of defects from each process step leading to higher rate of defect detection. CD distortions and CD non-uniformity leads to DPT overlay errors. This demands improved critical dimension uniformity (CDU) and overlay control. Scatterometry technique enables the characterization and control the CD uniformity and provision to monitor stepper and scanner characteristics such as focus and dose control. While CDSEM is capable of characterizing CD and sidewall angle, is not adequate to resolve shape variations, such as footing and top rounding and spacers with leaning angles, during the intermediate process steps. We will characterize direct low temperature oxide deposition on resist spacer with fewer core films and reduced number of processing and metrology control steps. Metrology characterization of SADP and resist core transferred spacers at various process steps will be performed by scatterometry using spectroscopic ellipsometry and reflectometry. We will present CD distribution (CDU) and profile characterization for core formation, spacer deposition and etch by advanced optical scatterometry and also validate against CDSEM.