Characterization of latent image of resist materials via critical-dimension resonant soft x-ray scattering

A comprehensive understanding of the chemical profile of the latent image is pivotal for mitigating stochastic effects and optimizing pattern quality in the process of EUV lithography. However, the subtle differences in chemistry between the exposed and unexposed regions of the resists make it extremely challenging to characterize the latent images with sub-nanometer precision. Here we develop the new metrology with critical-dimension resonant soft X-ray scattering (CD-RSoXS) to probe the chemical profiles of latent images stored in resist after exposure. The results are compared to the simulations with a finite element method (FEM) based Maxwell solver to extract a detailed profile of the latent and developed images. We demonstrate that CD-RSoXS technique can provide valuable insights into the high spatial resolution and local chemical sensitivity simultaneously, which is crucial to understand the resolution limits and stochastics effects in EUV lithography processes.