Investigations of the adhesion of maleic anhydride/cyclic olefin alternating copolymers to silicon substrates: Improved materials for 193 NM lithography

Various synthetic variations that affect the molecular weight, yield, and composition of maleic anhydride (MAH), norbornene (Nb), and tert-butyl 5-norbornene-2-carboxylate (Nb-TBE) terpolymers have been investigated. The adhesive properties of these polymers were evaluated from work of adhesion (W_adh) values to silicon substrates (treated with hexamethyldisilazane) using the method of fractional surface free energy from contact angle measurements of water and methylene iodide on the polymer films and substrate. These measurements showed that the W_adh increased with higher Nb-TBE content, and values were close to those of conventional 248 nm photoresist polymers. Furthermore, 193 nm resist formulations incorporating polymers with high Nb-TBE content showed increased imaging performance and successfully produced sharp and defined features as small as 110 nm, which were seen via scanning electron microscopy (SEM).