Bilayer resists for 193 nm lithography: SSQ and POSS

Positive 193 nm bilayer resists based on polysilsesquioxanes (SSQ) and polyhedral oligomeric silsesquioxanes (POSS) are described. Fluoroalcohol is employed as an acid group. Our POSS materials are prepared by condensation of functional trialkoxysilane rather than by the commonly employed hydrosilylation on POSS and consist of T-3 while the hydrosilylation method produces Q(4) POSS. The condensation method is more suitable for scale-up, producing POSS materials with higher glass transition temperatures. The materials were analyzed by F-19, C-13, and Si-29 NMR to determine composition and to quantify Q/T. The SSQ and POSS materials with the same compositions were compared in terms of the degree of hydrogen bonding by IR and the dissolution behavior by quartz crystal microbalance (QCM). Densities of the SSQ polymers were determined by X-ray reflectivity measurements and Rutherford back-scattering. Positive resists formulated with ternary SSQ and POSS were evaluated for contact hole and line/space applications, respectively. Characterization and lithographic performance of SSQ and POSS resists are described in detail.