DOE OSTI2025
There is a rapidly growing need for new materials for extreme ultraviolet (EUV) lithography, which incorporate high EUV absorbing elements. Hybrid resists, which are a combination of inorganic and organic moieties, are promising as they offer both high EUV sensitivity and high etch resistance. However, there is a glaring lack of methods to examine the uniformity of these important materials at the nanoscale. We examine the capabilities of nano-projectile secondary ion mass spectrometry (NP-SIMS) to investigate hybrid resists. NP-SIMS is a mass spectrometry-based technique with high lateral resolution. Using NP-SIMS, a surface is probed stochastically with a suite of individual projectiles, 10 6 to 10 7 in total, separated in time and space. Examining these individual mass spectra allows for nanoscale investigation of the uniformity of the surface. We evaluated the performance of NP-SIMS using samples of poly(methyl methacrylate) (PMMA) infiltrated with varying amounts of InO x via vapor-phase infiltration (VPI), an organic–inorganic hybridization method derived from atomic layer deposition. Here, we found that NP-SIMS measurements contained abundant characteristic ions related to both the PMMA and infiltrated In. The intensity of In atomic ions increased linearly with the number of infiltration cycles; however, the uniformity of In and PMMA varied with the number of infiltration cycles. After one cycle, we found that both the PMMA and In were relatively inhomogeneous. The homogeneity improved with subsequent infiltration cycles. In addition, NP-SIMS measurements contained characteristic ions related to the infiltration reaction and provided insights into the VPI mechanism. Overall, the results show that NP-SIMS is capable of examining both the inorganic and organic moieties in a hybrid resist and will be an important method for understanding the performance of these materials for use in EUV lithography.