EUV RLS performance tradeoffs for a polymer bound PAG resist

Abstract

This paper describes construction of a chemically amplified resist model across 248nm, 193nm and EUV imaging wavelengths. Using resist absorbance input as obtained from experiment and modeling, only the acid formation kinetics are allowed to vary across imaging wavelengths. This very constraining system affords very good fitting results, which provides high confidence that the extracted parameters from the model have actual physical significance. The quantum efficiency for acid formation in EUV is found to be ~8X higher than at 248 or 193nm, due to the excitation mechanism by secondary electrons. Most notably for the polymer bound PAG system under study the model provides an extremely low acid diffusion length (~7nm), suggesting an excellent inherent resolution for this material. Next, resist models are created for a series of sensitizer containing polymer bound PAG formulations, where the sensitizer loading is systematically varied. Compared to the reference polymer bound PAG resist without sensitizer the efficiency of acid formation is significantly increased, without a negative impact on either resolution or line width roughness. For the materials the quantum efficiency of acid formation in EUV is found to be ~12X higher than at 248nm. In these formulations the impact of sensitizer loading on the sizing dose is found to be rather moderate. This may suggest that even at the lowest sensitizer loading studied the energy of the secondary electrons is already efficiently transferred to the PAGs.