REVOLUTIONARY AND EVOLUTIONARY RESIST DESIGN CONCEPTS FOR 193-NM LITHOGRAPHY

The intense absorption of aromatic molecules at 193 nm severely limits the use of conventional matrix aromatic resins such as novolac, poly vinyl phenol for 193 nm lithography. This paradigm shift in resist des ign provides opportunities for new chemistries and process schemes to provide the required aqueous base solubility, etch resistance, resolut ion, photospeed and process latitude. In addition, regulatory constrai nts on the volatile organic emissions (VOC) also provide opportunities to design revolutionary resist schemes that not only address the lith ographic performance requirements but also alleviate the environmental safety and health (ES&H) aspects of resist technology. In this paper, we will analyze the several resist options available for 193 nm litho graphy and provide results for evolutionary single layer, bilayer and revolutionary ''all-dry'' plasma polymerized methyl silane (PPMS) resi st schemes. For single layer schemes, we have synthesized several co- and terpolymers with cycloolefins, maleic anhydride and acrylates (acr ylic, methacrylic acids and esters) and have used the protected polyme rs as matrix resins in three component systems with a photoacid genera tor (PAG) and dissolution inhibitor(s) (DI). Alternately, we have used the unprotected terpolymer with DI's and FAG in three component syste ms. The lithographic results for single layer and bilayer resist mater ials were obtained at 193 nm using a 0.55 NA Nikon or 0.56 NA ISI (Int egrated Solutions Inc.) small field exposure systems. Single layer res ist materials showed at least 0.16 mu m l/s pair resolution and modula tion down to 0.14 mu m l/s pairs using a formulation and process optim ized at 248 nm. We have also evaluated the performance of P(SI-CMS) (p oly(trimethyl silyl methyl methacrylate-co-chloromethyl styrene), a ne gative e-beam resist, at 193 nm and have obtained 0.25 mu m l/s pair r esolution without much optimization. Structure-activity relationships between the polymer properties and lithographic performance for this s ystem have been identified. The results obtained for PPMS, a plasma de posited all-dry resist technology, on the 193 nm Micrascan (0.50 NA) w ere also very encouraging. Again using a non-optimized process, we hav e obtained at least 0.15 mu m l/s pair resolution in a bilayer scheme.