Starting from general arguments on the relation of polymer structure, transpareiicy at 248 nm, resin hydrophilicity and resist dissolution characteristics, binder systems for novel DUV resists are presented, and the results of their lithographic evaluation are discussed. Phenolic polymers studied include homo-and copolymers of 2-, 3,-and 4-hvdroxystyrenes and of their alkyl substituted derivatives for three-component systems, as well as 2-and 4-hydroxyphenylmethacrylates for use in two-component t-BOC'-type resists. As an alternative non-phenolic resin, the peiformance of a maleimide/styrene copolymer in a two-component system is discussed.

It is generally accepted that the production of shrink versions of the 16 MB DRAM and the 64 MB DRAM generations will be patterned using deep UV radiation. This provides a new challenge to the photoresist suppliers, as the standard photoresist formulations are not suitable for this technology, mainly because the presently used novolak resins are highly opaque in the 200 -300 nm region. This is especially true for the 248 nm wavelength of KrF eximer lasers. Poly 4hydroxystyrene [PHS] has several advantages in transmission and thermal stability; however, its dissolution rate in commercial grade developers is unacceptably high. We report some recent results on modified, alkyl-substituted PHS derivatives. These polymers combine reduced alkaline solubiity with adequate optical and thermal properties, making them acceptable for future deep UV based production processes. Selected data of these new (co)polymers are discussed.

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