Application of polysilazane to etch mask in pattern transfer processes for deep and vacuum ultraviolet lithography

摘要

A polysilazane is investigated for a spin-on glass (SOG) used for a middle layer in a trilevel resist system. Higher film density is required for the middle layer to obtain higher etch resistance during the underlayer etching. The compositions of the polysilazane baked at 200℃ and 300℃ are Si{sub}0.42O{sub}0.34C{sub}0.40N{sub}0.20 and Si{sub}0.29O{sub}0.65C{sub}0.10N{sub}0.05, respectively, which are determined by x-ray photoelectron spectroscopy. The polysilazane is converted to silicon-oxide-like compositions by baking at 300℃. The film density and etch rate of SOG made from polysilazane are compared with that of polysiloxsane on condition that both films are baked at 300℃. The film density of the SOG made from the enter polysilazane is 2.07 g/cm{sup}3, which is higher than 1.87 g/cm{sup}3 of the conventional SOG made from a polysiloxsan. The etch resistance of the SOG made from the polysilazane is improved by 90% compared with that of the SOG made from the polysiloxsane due to the increased film density.