A chemically amplified positive tone resist system, based on new maleimide polymers and a photoacid generator, has been developed, called MISTRAL (Maleimide-Styrene based Resist for Advanced Lithography). These polymers, which are insoluble in aqueous base, consist of two different types of monomers: blocked p- hydroxystyrenes and N-substituted maleimides. In the irradiated zones of the resist film, the phenols are regenerated by the presence of a photoacid, thereby making the resist soluble in an appropriate developer. The maleimides, on the other hand, are needed to introduce high thermal stability and good film properties. The maleimides can further be used to tailor the dissolution properties of the resist. A variety of different MISTRAL polymers have been prepared, starting from the corresponding monomers. Changes in the molecular weight, the types of monomers used and their ratio in the feed have been analyzed: a correlation study between the physical properties of the MISTRAL polymers and their lithographic behavior was systematically performed, revealing quarter micron resolution capabilities.