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Organic salts are known to affect the contact charge developed between two polymers. When ionomers are present, the charge often increases monotonically with the salt concentration and the charge has been ascribed to the transfer of ions. A model is presented which relates the charge with salt concentration in the polymer blend. In this model, only dissociated ions but not ion pair ions are proposed to transfer. The model incorporates ion pair dissociation (K1) and ion pair aggregation (K) and shows that when ion pair aggregation is minimal, the concentration of dissociated ions scales near linearly with the square root of the concentration of salt in the blend. The linear relationship between the charge and [salt]1/2 is demonstrated. It is further shown that the equilibrated charge which is established is limited by the concentration of dissociated ions on the surface of the polymer and not by the surface provided by the second material.

A production-worthy deep UV resist system built on the ESCAP platform is described. The resist consists of a thermally and hydrolytically stable resin and acid generator and thus can be heated at high temperatures for free volume reduction, which provides stabilization toward airborne base contamination. The film densification in conjunction with the use of a bulky acid reduces acid diffusion during postexposure bake, contributing to high lithographic performance. Robust 0.25 µm process latitudes have been demonstrated. Furthermore, the resist has produced excellent 175 nm line/space images with a depth-of-focus of 0.3 p m on a KrF excimer laser stepper with a numerical aperture of 0.60, indicating that the resist allows the use of the current exposure tool in the early 1 Gbit generation.

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The thin film dissolution behavior of phenolic resins such as poly(4-hydroxystyrene) and poly(4-bydroxystyreneco-t-butyl acrylate), the dissolution inhibition effect of acid generators, and the development kinetics ofthe ESCAP resist are reported. All the dissolution rate measurements were carried out using a quartz crystal inicrobalauce (QCM), which can provide valuable information on the time-dependent dissolution behavior even for an extremely fast rate of 30,000 A/sec. Poly(4-hydroxystyrene)s with a wide range of molecular weights (M=2,3OO26,OOO) and molecular weight distributions (1.2.5.5) have been found to dissolve linearly with time in a 0.21 N tetramethylammonium hydroxide (TMAH) aqueous solution. The dissolution rate of the copolymers decreases exponentially with an increase in the acrylate concentration, accompanied by an increase in an induction period. The dissolution inhibition effect of acid generators varies widely.Oniuiu salts are excellent dissolution inhibitors, even stronger than so-called dissolution inhibitors such as t-butoxycarbonyl-protected bisphenol A. A higher loading of triphenylsulfonium triflate in the copolymer film results in a longer induction period and an exponentially slower dissolution rate. The ESCAP resist based on the copolymer begins to dissolve in a 0.26 N TMAH solution at only ca. 5 % conversion of the t-butyl ester to carboxylic acid and reaches its maximum dissolution rate of 30,000 A/sec at the dose to clear with ca. 60 % conversion, which corresponds to the developer selectivity of >15. Although the dissolution rate does not change much above the dose to clear, the induction period becomes shorter at a higher dose, which can be observed by QCM even when the full development time is <1 sec.