A chemically advanced template search (CATS) based on topological pharmacophore models has been developed as a technique for virtual screening. This technique has successfully identified novel potent Ca(2+) antagonists (such as 2) that have a similar activity to 1 (a known T-channel blocking agent) in a library of several hundred thousand compounds on the basis of a correlation vector representation.

Articles you may be interested inGas diffusion electrode setup for catalyst testing in concentrated phosphoric acid at elevated temperatures Rev. Sci. Instrum. 86, 024102 (2015); 10.1063/1.4908169Submillisecond post-exposure bake of chemically amplified resists by C O 2 laser spike annealing Effects of photoacid generator incorporation into the polymer main chain on 193 nm chemically amplified resist behavior and lithographic performance In a chemically amplified resist absorbed photons generate stable catalyst molecules instead of directly switching resist solubility via photochemical reaction. This allows for much lower exposure doses to be used in imaging. Some catalyst mobility is necessary to achieve amplification since the catalyst must move from reaction site to reaction site, but a mobile catalyst can blur the deposited aerial image. Catalyst molecules that are free to move in exposed regions are also free to move into adjacent unexposed regions. Understanding acid catalyst diffusion in photoresist resins is complicated by the constantly changing chemical environment the diffusing catalyst experiences as the resist undergoes chemical reactions. The diffusing catalyst promotes chemical reactions which change the properties of its surrounding resin. In addition, it is possible a transient material state is generated by volatile reaction byproducts and their desorption from the film. In most photoresist systems it is impossible to separate reaction and diffusion effects. This work describes studies of acid diffusion in polymers that are close structural analogs to reactive photoresist resins but do not react with the diffusing acidic catalyst. The purpose of this study into nonreactive polymer is to gain insight into the more complex, reactive systems. In addition, experiments with polymeric photoacid generators are reported. These materials provide added insight into acid transport in photoresist materials.

Articles you may be interested inCurrent induced annealing and electrical characterization of single layer graphene grown by chemical vapor deposition for future interconnects in VLSI circuits

A chemically advanced template search (CATS) based on topological pharmacophore models has been developed as a technique for virtual screening. This technique has successfully identified novel potent Ca(2+) antagonists (such as 2) that have a similar activity to 1 (a known T-channel blocking agent) in a library of several hundred thousand compounds on the basis of a correlation vector representation.

Communications to the Editor 2933 the N2C5CI4 molecule is not known. The Ir-N(l) (1.819,1.794 Á) and N(l)-N(2) (1.171,1.159 Á) distances, while similar, are consistent with less it back-bonding from metal to atom N(l) in the N2R species.We believe that the route to a variety of metal-NaR complexes described here is general one and that the comparative reaction and structural chemistry of these complexes and their CO, NO+, and N2Ph+ analogues will prove to be diverse and interesting.

Polymer structure effect on dissolution characteristics and acid diffusion in chemically amplified deep ultraviolet resists J.The microlithographic process is dependent upon the dissolution of acidic polymers in aqueous base. The fundamental mechanism that governs the dissolution of these polymers has been the subject of considerable discussion, and a number of theories have been proposed to explain this behavior. Our research group has presented the critical ionization ͑CI͒ dissolution model to explain the dissolution of phenolic polymers in aqueous base. Specifically, the model proposes that a minimum or critical fraction of ionized sites, f crit , on a given polymer chain must be ionized in order for that chain to dissolve. The main input parameters to this model are the critical fraction of ionized sites, f crit , and the fraction of ionized surface sites, ␣. In this work methods are established for measuring these parameters. A quantitative link between the CI model and experiment has been demonstrated for the dissolution rate and surface roughness dependence on polymer molecular weight. Methods for calculating ␣ are discussed, including a new method that considers the formation of an electrostatic double layer at the resist-developer interface.

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The perpetual advancement of materials and equipment for microlithography has resulted in the ability to print critical dimensions that approach the size of the molecules that make up photoresists. As a result, molecular scale effects such as line edge roughness have become a concern for both resist manufacturers and process engineers. In this work we have investigated the increasing importance of molecular level effects, especially in terms of the contributions of the exposure and postexposure bake (PEB) steps to spatial variations in film composition. A mesoscale simulation of the PEB was used to model the discrete mass transport and reaction events that create the changes in film composition responsible for resist function. Local irregularities in resist composition are generated during the PEB, the magnitude of which can be related to the local concentration of acid. This study is focused on the establishment of an understanding of the effects of process and composition variables on the reaction product distribution. The reaction product distribution was calculated for an APEX®-like resist under a variety of exposure and bake conditions. These process variables have a profound influence on spatial irregularities in the composition gradient. Ultimately, it is the interaction of this reaction product distribution with the development process that will determine line edge roughness.