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We report on a study of the chemical and lithographic behavior in a 193 nm single layer resist of two types of base additives, aminosulfonates opium and tetrabutylammonium carboxylate salts. These additives were examined because of their low potential for undesirable reaction with maleic anhydride or acrylic acid repeat units in norbonene/maleic anhydride/acrylate based 193 nm resins. For ammonium carboxylate additives it will be shown that using these gives comparable lithographic performance to a standard formulation containing an amine additive. For aminosulfonate onium salts a study was done of the relationship between chemical structure of these additives and their thermal stability and the lithographic performance imparted by these to a 193 nm single layer resist system. It will be shown that the decomposition temperature is a function of the basicity (nucleophilicity) of the counter anion decreasing with increasing basicity but can be improved by going from an iodonium to a sulfonium chromophore. Cyclamate and cysteate opium salts will be shown to provide good lithographic performance with good post-exposure bake delay latitude.

Through a series of statistical design experiments we optimized the lithographic performance of a 193 rim single layer resist based on a norbomene-maleic anhydride matrix resin. Several interesting findings were found including that having the PEB temperature higher than the SB temperature improved the performance of the resist. The polymer composition was found to strongly influence the lithographic performance of the resist. Variables that we examined included acrylate loading and blocking level. By optimizing the composition of the polymer, we have obtained resists with high etch resistance, square profiles and 0. 130 micron dense line ultimate resolution in 0.5 micron thick films. The resist formulations are compatible with industry standard 0.262 N TMAH. During exposure the resist does not suffer from the outgassing of volatile species (less than 2 molecules/cm2 x sec).

Post exposure bake (PEB) models in the STORM program have been extended to study pattern formation in 193nm chemically amplified resists. Applications to resists formulated with cycloolefin-maleic anhydride copolymers, cholate based dissolution inhibitor, nonafiate photoacid generator and base quencher are presented. The PEB modeling is based on the chemical and physical mechanisms including the thermally induced deprotection reaction, acid loss due to base neutralization and protected-sites-enhanced acid diffusion. Simplifying assumptions are made to derive analytical expressions for PEB. The model parameters are extracted from the following experiments. UVvisible spectroscopy is used to extract the resist absorbance parameters. The generation of acid is monitored using the method of "base additions". The extent of deprotection that occurs during the bake is determined by monitoring the characteristic FTIR absorbance band around 1 170 cm1 over a range of exposure doses and bake temperatures. Diffusion parameters are extracted from line end shortening (LES) measurements. These parameters are optimized using the Method of Feasible Directions algorithm. Application results show good agreement with experimental data for different LES features.