Methods for Fin Etching profile maintaining and measurement

Characterization of nano-scale device meets increasingly challenging with the decreasing dimension of transistors. The measurement and monitoring of silicon-Fin CD (critical dimension) play an important roles during FinFET process researching and developing. Fin CD measurement is based on TEM images, in which, the sub-angstrom layers have too limited contrast to distinguish the interface between Silicon Fin and isolation SiO2 or Fin profile maintain film. Therefore, the definition of those interface cannot be standardized cause of TEM sample thickness variation, Fin deformation and TEM imaging error just like sphere and chromatic aberration. In this job, firstly, TEM sample preparation was taken with profiling maintain film which has the optimized internal stress and good gap filling for high aspect ratio Fin Etching step. Secondly, Sobel model based interface identification system was setup for auto-measurement which has good data variation performance which is within 2% of the target size to meet the needs of process development.