ICN was photolyzed at 254 nm in the gas phase in the presence of 15-20 torr of certain alkenes or aromatics. The products were analyzed by GC-MS. Ethene gave acrylonitrile; propene gave acrylonitrile, allyl cyanide and cis-and trans-1 -cyanopropene; 2-methylpropene gave 2-cyanopropene; benzene gave benzonitrile; toluene gave benzonitrile and 2-, 3-, and 4-cyanotoluene. These products are explained by a mechanism involving attack of CN on the organic to give vibrationally excited radicals. These radicals rapidly fragment, producing the major products, or react more slowly in bimolecular processes. The relevance of these results to R F discharge chemistry is discussed.Recent studies have demonstrated a useful method for the direct cyanation of unsaturated compounds in the gas It has been proposed that these reactions involve the radical CN. This radical is hypothesized, for example, to attack benzene, giving high yields of benzonitrile, and to attack substituted aromatic compounds to give a mixture of ipso (l), ortho-(2), meta-(3) FN FN FN CN
The effects of Ta barrier thickness on electromigration reliability of dual-damascene Cu/porous methylsilsesquioxane interconnects were investigated. With decreasing Ta barrier thicknesses, the threshold product of current density and line length (jL)c was found to be reduced due to less structural confinement from thinner barriers. The effect can be accounted for by the effective modulus of the structure except for the 75-Å Ta barrier where the (jL)c product is reduced more than expected, probably due to the presence of defects in the barrier. Results from the early failure test structures revealed a bimodal failure distribution for samples with the 75-Å and l00-Å barriers. Focused ion beam microprobe and transmission electron microscopy observations revealed that the weak-mode early failure was caused by Cu outdiffusion through structural defects in the thin Ta barrier.
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