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In this paper we describe the lithographic behavior and related material properties of a new class of chemically amplified, positive tone, silicon-containing methacrylate photoresists incorporating the polyhedral oligomeric silsesquioxane (POSS) group as the etch-resistant component. POSS-bearing monomers were copolymerized with methacrylic acid (MA), tertbutyl methacrylate (TBMA), tert-butyl trifluoro methacrylate (TBTFMA), itaconic anhydride (IA), and 2-(trifluoromethyl) acrylic acid (TFMA), in various compositions. A perfluorooctylsulfonate-based photoacid generator (PAG) was used to deprotect TBMA (or TBTFMA) to base soluble carboxylic acid by heating after exposure. XPS and angular XPS analysis were used to examine possible surface segregation phenomena. It was proven that POSS surface enrichment occurs for the POSS-TBMA copolymers while surface segregation may be reduced if suitable additional resist components are selected. The POSS-based resists were studied for 157-nm lithographic applications and found to have high sensitivity (<10 mJ/cm 2 under open field exposure), no silicon outgassing, and sub-100-nm resolution capabilities. Ninety nanometer patterns in 100-nm thick films were resolved. At present, their absorbance is high (∼4 µm -1 ) for single-layer lithographic applications at 157 nm; however, high etch resistance in oxygen plasma makes them suitable for bilayer schemes.

The transesterification of two different frying oils (soybean oil and a mixture of soybean and cotton seed oil) with methanol, in the presence of an alkali catalyst (NaOH), by means of low-frequency ultrasonication (24 kHz, 200 W) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. The two different frying oils gave similar yields of isolated methyl esters both under mechanical stirring and ultrasonication. Also the physical and chemical properties of the two biodiesel fuels produced were investigated. The fuels produced were characterized by determining their density, viscosity, flash point, boiling point, cetane number, sulfur content, cloud point, pour point, cold filter plugging point, acid value, iodine value, and saponification value. From the physical and chemical properties of the two biodiesel fuels, it is concluded that these fuels have very similar properties to those of conventional diesel, except for the cetane number, which is higher, and the sulfur content of the biodiesel, which is negligible. Thus, experimental biodiesel fuels are environmentally friendly and attractive alternatives to conventional diesel.

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Siloxane and silsesquioxane copolymers have been synthesized and first evaluated as potential components of 157 nm resist materials. In block copolymers of dimethylsiloxane and tert-butyl methacrylate negative imaging chemistry dominates at 157 nm, due to the presence of the siloxane component, although positive imaging in aqueous base developers via chemical amplification was obtained at longer wavelengths ͑248 nm͒. The same behavior is observed in graft copolymers of dimethylsiloxane and tert-butyl methacrylate. On the other hand, random copolymers of polymerizable polyhedral oligomeric silsesquioxane monomers with various acrylates, including partially fluorinated, can be used as components of resist formulations that provide positive imaging at 157 nm, aqueous base development, and physicochemical properties which resemble those of conventional poly͑meth͒acrylates. Pattern transfer properties depend on the selection of the silsesquioxane component. Polymers containing 30% or higher w/w ethyl-substituted silsesquioxane cages provide the necessary etch resistance as well as low surface roughness to oxygen plasma at 100 nm film thickness, allowing bilayer 157 nm lithography, even without further absorbance optimization.

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Novel polymers containing polyhedral oligomeric silsesquioxane (POSS) pendant groups have been synthesized and evaluated as components of I 57 nm resist formulations. Random copolymers of polymerizable, ethyl-POSS containing monomers with various acrylates, including tert-butyl methacrylates, were first used in positive, aqueous basedevelopable resist formulations and evaluated at thicknesses in the range of 100 nm. Copolymers with optimized monomer composition do not present strong self-organization phenomena and provide materials with good film forming properties, and high sensitivity at 157 nm (1-10 mJ/cm2 under open field exposure). Process studies reveal strong influence of thermal processing conditions and development concentrations on swelling of unexposed and underexposed resist areas. Similar results are obtained from Dissolution Rate Monitoring (DRM) studies. A typical process selected for swelling reduction includes pre-exposure and post-exposure bake steps at 160°C (2minutes) and selection of low strength developers. High resolution patterning under these conditions has shown potential for sub 130 11111 lithography upon further material optimization. On the other hand, pattern transfer studies have shown that 100 nm thick films ofPOSS containing materials, having the same silicon content as the ones evaluated for high resolution 157 nm lithography, provide the necessary oxygen plasma resistance for use as bilayer resists. X-ray photoelectron spectroscopy (XPS) was used for surface characterization before plasma etching. Both XPS and angular XPS characterization have revealed that the POSS moieties tend to segregate preferentially on the free surface ofthe films.