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.
Optical immersion lithography utilizes liquids with refractive indices >1 (the index of air) below the last lens element to enhance numerical aperture and resolution, enabling sub-40-nm feature patterning. This shift from conventional dry optical lithography introduces numerous challenges requiring innovations in materials at all imaging stack levels. In this article, we highlight the recent materials advances in photomasks, immersion fluids, topcoats, and photoresists. Some of the challenges encountered include the fluids' and photomask materials' UV durability, the high-index liquids' compatibility with topcoats and photoresists, and overall immersion imaging and defectivity performance. In addition, we include a section on novel materials and methods for double-patterning lithography-a technique that may further extend immersion technology by effectively doubling a less dense pattern's line density. 93 Annu. Rev. Mater. Res. 2009.39:93-126. Downloaded from www.annualreviews.org by Otterbein University on 09/17/13. For personal use only.
This article presents experimental results that suggest that classical Fickian diffusion cannot account for any significant fraction of the critical dimension bias observed in chemically amplified photoresists. A transport mechanism based on reaction front propagation is proposed as a possible explanation for the experimental observations.
A carbon-doped silicon oxide (CDO) finds use as a material with a low dielectric constant (k) for copper interconnects in multilayered integrated circuits (ICs).
Three metal-catalyzed vinyl addition copolymers derived from partially fluorinated norbornenes and tricyclononenes have been synthesized and evaluated for use in formulating photoresists
for 157 nm lithography imaging. The transparency of these polymers at 157 nm, as measured by variable
angle spectroscopic ellipsometry (VASE), is greatly improved over their nonfluorinated counterparts. The
results of preliminary lithographic evaluations of resists formulated from these polymers alone and with
the addition of several new fluorinated dissolution inhibitors are presented. Images as small as 70 nm
have been printed in some formulations.
Many semiconductor device manufacturers plan to make products with 157 nm lithography beginning in 2004. There is, at this time, no functional photoresist suitable for 157 nm exposure. Developing resist materials for 157 nm lithography is particularly challenging since water, oxygen, and even polyethylene are strongly absorbing at this wavelength. A modular approach to the design of a single layer resist for 157 nm has been undertaken. In this approach, the resist has been conceptually segmented into four functional modules: an acidic group, an acid labile protecting group, an etch resistant moiety, and a polymer backbone. Each of these modules has an assigned function and each must be transparent at 157 nm. Progress has been made toward finding candidate structures for each of these modules. We have demonstrated that acidic bistrifluoromethylcarbinols are very transparent at 157 nm and function efficiently in chemically amplified resists with both high and low activation energy protecting groups. Judicious incorporation of fluorine in acrylates and alicyclics has provided etch resistant polymers with greatly improved transparency at 157 nm. In particular, esters of poly͑␣-trifluromethylacrylic acid͒ are far more transparent than their protio analogs. The Diels-Alder adducts derived from reaction of these and other fluorinated alkenes with cyclopentadiene offer a route to a wide range of alicyclic monomers that show great promise as transparent, etch resistant platforms for the design of 157 nm resists. Polymers of this sort with absorbance below 2 per micrometer are reported.
The structure and phase composition of HAp coatings deposited onto Ti6Al4V coupons (50x20x2mm) by atmospheric plasma spraying (APS) were studied by laser-Raman spectroscopy, 31 Pand 1 H-MAS-NMR and 2D-31 P/ 1 H HETCOR-CP-NMR spectroscopy, and XRD with Rietveld refinement. The samples investigated comprised APS HAp coatings with and without a TiO 2 bond coat as well as coatings incubated for different lengths of time (up to 12 weeks) in simulated body fluid (SBF) under physiological conditions. In APS coatings the presence of a bond coat increased the proportion of well-ordered crystalline HAp at the expense of distorted apatite-like structures such as oxyHAp and oxyapatite, and thermal decomposition products such as tricalcium phosphate (TCP) and tetracalcium phosphate (TTCP), and also decreased the amount of amorphous calcium phosphate (ACP). Incubation in SBF further advanced the proportion of crystalline HAp since the disordered structures, the thermal decomposition products, and ACP exhibit substantially higher solubility.
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