A detailed comparison is made of several local-composition lattice models. The models considered include several popular activity coefficient models:  the Wilson equation, Guggenheim's quasi-chemical theory (GQC), the nonrandom two-liquid theory (NRTL), and the universal quasi-chemical (UNIQUAC) theory. Also considered are three recently developed lattice models:  the Born−Green−Yvon (BGY) model, the nonrandom surface fraction (NRSF) model, and the Aranovich−Donohue (AD) model. Similarities and differences in the assumptions regarding the local compositions are examined. Detailed comparisons are made for both symmetric and asymmetric monomer mixtures as well as for polymer/solvent mixtures with Monte Carlo simulations.

The density and molecular size dependence of the equation of state for molecules that consist of freely jointed, tangent hard spheres is investigated. It is shown that the properties of hard-chain molecules can be accurately described using the properties of spherical molecules and a function c which varies approximately linearly with the reduced density. Monte Carlo and molecular dynamics simulation data for hard chains were used to develop the expression for c. The new equation of state is simple in form and more accurate for the calculation of compressibility factors for hard-chain molecules than either Wertheim’s first-order thermodynamic perturbation theory or the generalized Flory dimer theory (GFD). Further, this new equation reduces to the correct second virial coefficient limit as the density approaches zero.

The phase behavior of polymer solutions, melts, and blends depends on competition between the energy and entropy of mixing. Accurate representation of both the temperature and composition dependence is particularly difficult near mixture critical points. Although a number of theories have been proposed, assessing their accuracy and limitations was difficult until molecular simulations of polymer solutions were made. In this work, a new expression for free energy of mixing is proposed. The repulsive part is Guggenheim's random-mixing theory; the attractive part is a Boltzmann-weighted, surface-fraction-averaged energy. We compare this equation with expressions from Flory, Guggenheim, Bom-Green-Yvon, and Freed as well as with Monte Carlo simulations. Comparisons also are made with experimental data for real systems.

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The design of 193 nm photoresists with improved reactive ion etch (RIE) resistance has been a longstanding aim of both industrial and academic research and development programs. A variety of correlations between photoresist polymer structure and etch resistance have been developed,'3 however, the universality of these approaches, and in particular, the practicality of making comparisons across specific polymer families and specific RIE processes has recently been called in to question.4 In order to examine structure:RIE correlations in more detail, we have developed a new model based on the incremental structural parameter (ISP.)This model makes use of a molecular fragment-based definition of polymer structure which incorporates and extends aspects of previous parameters such as the Ohnishi and Ring parameters. An initial study revealed that this model allowed quantitative correlations between polymer families and across etch processes to be made.Continuing studies which examine the use of the ISP model in integrating 193 nm photoresists in prototype production processes will be described. Various polymer families used in deep-UV and 193 nm photoresists including methacrylates, alternating copolymers, styrenes, and cyclic olefins will be compared. We will present a more detailed description of the ISP model and of the follow-on 'new' ISP method which has been developed based on insights gained from the original ISP model, and make extended comparisons between the two ISP models.