Resolution–linewidth roughness–sensitivity performance tradeoffs for an extreme ultraviolet polymer bound photo-acid generator resist

摘要

The goal of this work is to use a combination of experiment andncalibrated resist models to understand the impact of photo-acid generatorn(PAG) and sensitizer loading on the performance of a polymer bound PAGnresist based processes for extreme ultraviolet (EUV) lithography. This pa-nper describes construction of a chemically amplified resist model acrossn248 nm, 193 nm, and EUV imaging wavelengths. Using resist absorbanceninput as obtained from experiment and modeling, only the acid formationnkinetics are allowed to vary across imaging wavelengths. This constrainingnsystem affords very good fitting results, which provides high confidencenthat the extracted parameters from the model have actual physical sig-nnificance. The quantum efficiency for acid formation in EUV is found tonbe ∼8× higher than at 248 or 193 nm, due to the excitation mechanismnby secondary electrons. Most notably for the polymer bound PAG systemnunder study the model provides an extremely low acid diffusion lengthn(∼8 nm), suggesting an excellent inherent resolution for this material.nNext, resist models are created for a series of sensitizer containing poly-nmer bound PAG formulations, where the sensitizer loading is systemati-ncally varied. Compared to the reference polymer bound PAG resist withoutnsensitizer the efficiency of acid formation is significantly increased, withoutna negative impact on either resolution or linewidth roughness. For thesenmaterials the quantum efficiency of acid formation in EUV is found to ben∼12× higher than at 248 nm. In these formulations the impact of sensi-ntizer loading on the sizing dose is found to be rather moderate. This maynsuggest that even at the lowest sensitizer loading studied the energy of thensecondary electrons is already efficiently transferred to the PAGs