The fact suggests that hydrogen originated from the broken SiH bonds enhanced the polymerization, which causes the decrease of etch rate. ![]() ![]() We found that the fluorocarbon thickness was thicker in the SiH rich samples than NH rich samples. The NH rich films exhibited a lower etch rate at −20 ☌ than that observed at room temperature or higher, whereas the SiH rich films showed a higher etch rate at −20 ☌. The FTIR shows that the ratio of NH and SiH groups were found to be significantly different in the SiN films. The XRR and XPS results indicate that the chemical composition and film density were almost identical for the films. The dependence of substrate temperatures (50 to −20 ☌) on etch rate in two kinds of PECVD SiN films were investigated by a CF4/H2 mixture plasma. Quasi-chemisorbed F atoms could be also responsible for F atoms recombination on SiOx surfaces. In addition, quasi-chemisorbed F atoms induce the weakening of the adjacent Si–O bonds in OxSiFy surface complexes promoting breaks of these Si–O bonds under further F atoms attacks. F atoms quasi-chemisorption on surface SiOx groups accompanied by fourth-coordinated Si atoms transition to pentavalent Si states is related with the experimentally observed fast fluorination stage and vibrational frequency shifts. In the frame of 1-D model, evolutions of the SiCH3 and appeared SiCHxFy surface groups distributions inside the porous films are calculated as a function of F atoms dose. DFT method is applied to calculate vibrational mode frequencies and their shifts under F atoms flux. One-dimensional 1-D Monte Carlo & gas-surface kinetics (MC&GSK) model and density functional theory (DFT) simulations used for the development of the multi-step mechanism of OSG films damage and etching are further verified on FTIR spectroscopy data. Nitrogen, with its very stable triple bonds, requires electric discharge and high temperatures to combine directly with fluorine.Fluorine atoms interactions with organosilicate glass (OSG)-based low-κ dielectric films are experimentally and theoretically studied. The lighter noble gases xenon and krypton can be made to react with fluorine under special conditions and argon will combine with hydrogen fluoride. ![]() The halogens react readily with fluorine gas as does the heavy noble gas radon. The noble metals ruthenium, rhodium, palladium, platinum, and gold react least readily, requiring pure fluorine gas at 300–450 ☌ (575–850 ☏).įluorine reacts explosively with hydrogen in a manner similar to that of alkali metals. The alkali metals react with fluorine with a bang (small explosion), while the alkaline earth metals react at room temperature as well but not as aggressively. Often, the metal must be powdered because many metals passivate (form protective layers of the metal fluoride that resist further fluoridation). Several heavy radioactive elements have not been fluoridated because of their extreme rarity, but such reactions are theoretically possible.Īll metals react with fluorine, but conditions vary with the metal. Fluorine is also known to form compounds with rutherfordium, element 104, and seaborgium, element 106. All of the elements up to einsteinium, element 99, have been checked except for astatine and francium. Extra footage.įluorine forms compounds, fluorides, with all elements except neon and helium. External videosįluorine video from the University of Nottingham: Cold gas impinging on several substances causes bright flames. Wood and even water burn with flames when subjected to a jet of fluorine, without the need for a spark. Many generally non-reactive substances such as powdered steel, glass fragments and asbestos fibers are readily consumed by cold fluorine gas. Reactions with fluorine are often sudden or explosive. The covalent radius of fluorine in difluorine molecules, about 71 picometers, is significantly larger than that in other compounds because of the weak bonding between fluorine atoms. ![]() That bond energy is significantly weaker than those of dichlorine or dibromine molecules and similar to the easily cleaved oxygen–oxygen bonds of peroxides or nitrogen–nitrogen bonds of hydrazines. Halogen bond energies (kJ/mol) Xįluorine gas is highly reactive with other substances both because of the strong bonds it forms with other atoms and because of the relative weakness of the fluorine–fluorine bond. The removal of an electron from a fluorine atom requires so much energy that no known oxidant can oxidize fluorine to any positive oxidation state. It is the most electronegative element and a strong oxidant. Fluorine's chemistry is dominated by its tendency to gain an electron.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |