Spatial frequency breakdown of CD variation

Abstract

Controlling the Local CD Uniformity is important for the implementation of EUV lithography in high-volume production. Spatial frequency breakdown of stochastic effects and identification of stochastic noise contributors may help us to understand the current performance and suggest possibilities and pathways for future improvement. In this work, we look for potentially hidden sources of systematic local variability by collecting and analyzing CD metrology data over lengths greater than a single SEM field of view (FOV). Fourier analysis of the CD data is used to identify any systematic variability. This work will enable a more accurate breakdown of local variability. Additionally, using the length scale of any observed systematic signal we can attempt to trace back the origin and reduce or eliminate its source.