Proposed single layer composite film used as high transmission phase shifting masks for the 32, 45, and $65nm$ technology nodes

The optical constants of composite films are linearly dependent on their mole fraction. The $(Al2O3)x–(TiO2)1−x$ composite films prepared by using rf unbalanced magnetron sputtering are completely oxidized using an $O2∕Ar$ flow rate ratio of 2.0. By tuning the $Al2O3$ mole fraction of $(Al2O3)x–(TiO2)1−x$ composite films, the optical constants can be made to meet the optical requirements for a high transmittance attenuated phase shifting mask (HT-AttPSM) blank. It can be seen that the $Al2O3$ mole fraction in $(Al2O3)x–(TiO2)1−x$ composite films which would best meet the optical requirements of a HT-AttPSM blank in ArF (immersion) lithography is calculated to be between 78% and 86%. In order to obtain a HT-AttPSM blank with an optimized transmittance of 20%, one $Al2O3–TiO2$ composite film is fabricated. All the films meet the requirements of the adhesion test and surface roughness for HT-AttPSM applications. Therefore, a single layer composite film of $Al2O3–TiO2$ could be applied to HT-AttPSM blanks, which can be utilized to design fine patterns with dimensions as small as 65, 45, and $32nm$⁠.