Application of AlSi-based materials on approach of chemical stability of embedded layer for bi-layer attenuated phase-shifting mask in 193 nm lithography

AlSi-based films could be formed by a combination of transparent chemical compositions and absorbing elements. When the oxide structure increased with the increasing of atomic percentage of oxygen, the n of AlSixOy appeared to increase while k appeared to decrease in 193 nm. The saturation of formation of AlN and Si3N4 in AlSixNy was observed about 4.8 sccm N-2 flow rate. The correlation between optical properties and chemical compositions of AlSi-based films has been described, therefore, the chemical stability of embedded material could be approached. Top layer film with saturation of AlN, Si3N4 or Al2O3, SiO2 could provide better chemical stability. Bottom layer with suitable mount of Al and Si chemical structure could provide enough light absorption. With proper combination of top and bottom layer AlSixOy and AlSixNy embedded material, the optical properties of bi-layer attenuated phase-shifting mask could kept in the range of high transmittance (T%=15-45%). The 0.18-mum-fine/space NEB-22 resist pattern exposed by e-beam writer on AlSixOy embedded layer has good resolution. Due to good resist profile, the 0.3-mum-line/space etched pattern of bilayer AlSixOy was also successfully carried out.