Evaluation as planarizing layers

Evaluation of Several Organic Materials as Planarizing Layers for lithographic and Etchback Processing... 

Poly(dimethyl glutarimide) (PMGI) (structure 3.7) was shown by Hir-aoka (63) to undergo molecular weight reduction upon irradiation with a sensitivity comparable to PMMA. This polymer is sensitive to DUV radiation below 280 nm soluble in aqueous base resistant to common organic solvents and thermally stable to ca. 185 C, which renders the material very attractive as a thick planarizing layer in the exposure-PCM scheme as will be discussed in a later section. This material is being evaluated for commercialization by Shipley Company (64, 65). 

OPLC is an instrumentalized version of planar layer liquid chromatography, and it is suitable for on-line as well as off-line sample application, separation, and detection, and their variations (partial off-line methods). In the on-line mode, the solutes are measured in the drained eluent by connecting a flow-cell detector to the eluent outlet. In the off-line mode, all the principal steps of the chromatographic process, such as sample application, separation, and quantitative evaluation, are performed off-line (2b-28). 

These workers used binary solvent systems over a range of mole fractions to determine, for each solute, the constants a and b of equation (8.2). For methyl and phenacyl esters, TLC was used, while overpressured layer chromatography (OPLC) was used for dansyl amino acids. Nurok and co-workers (11) also evaluated how the quality of a simulated separation varies with changing solvent strength by using the inverse distance function (IDF) or planar response function (PRF), as follows ... 

Let us first outline the theoretical background of the evaluation of both the charge and potential of two interacting diffuse electric layers. It is well known that the charge and potential distribution in the diffuse layer can be represented with a sufficient degree of accuracy using the Poisson-Boltzman (PB) approximation [e.g. 246]. For a planar film from aqueous symmetrical electrical electrolyte of valence z, the respective equation can be written in dimensionless form as... 

Several advantages of the inlaid disk-shaped tips (e.g., well-defined thin-layer geometry and high feedback at short tip/substrate distances) make them most useful for SECM measurements. However, the preparation of submicrometer-sized disk-shaped tips is difficult, and some applications may require nondisk microprobes [e.g., conical tips are useful for penetrating thin polymer films (18)]. Two aspects of the related theory are the calculation of the current-distance curves for a specific tip geometry and the evaluation of the UME shape. Approximate expressions were obtained for the steady-state current in a thin-layer cell formed by two electrodes, for example, one a plane and the second a cone or hemisphere (19). It was shown that the normalized steady-state, diffusion-limited current, as a function of the normalized separation for thin-layer electrochemical cells, is fairly sensitive to the geometry of the electrodes. However, the thin-layer theory does not describe accurately the steady-state current between a small disk tip and a planar substrate because the tip steady-state current iT,co was not included in the approximate model (19). 

Chemical vapor deposition (CVD) was applied to produce homogeneous thin films of pure and doped spinel cobalt oxide with similar morphology on the surface of planar and monolithic supports. The planar substrates were used to investigate the thermal stability and the redox properties of the spinel using temperature-programmed methods monitored by emission-FTIR spectroscopy, while the monolithic substrates were used to test the catalytic performance of the deposited films toward the deep oxidation of methane and to evaluate its durability. The high performance of cobalt oxide to oxidize methane in diluted streams was demonstrated at 500 °C. Furthermore, controlled doping of cobalt oxide layers with suitable cations was demonstrated for nickel as an example, which resulted in substantial increase of electric conductivity. 

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