Silicon dioxide vaporization

Silicon, like carbon, is relatively inactive at ordinary temperatures. But, when heated, it reacts vigorously with the halogens (fluorine, chlorine, bromine, cmd iodine) to form halides and with certain metals to form silicides. It is unaffected by all acids except hydrofluoric. At red heat, silicon is attacked by water vapor or by oxygen, forming a surface layer of silicon dioxide. When silicon and carbon are combined at electric furnace temperatures of 2,000 to 2,600 °C (3,600 to 4700 °F), they form silicon carbide (Carborundum = SiC), which is an Importeint abrasive. When reacted with hydrogen, silicon forms a series of hydrides, the silanes. Silicon also forms a series of organic silicon compounds called silicones, when reacted with various organic compounds. 

The other platform is dielectrics, for example, silicon dioxide, silicon nitride, silicon oxynitride, tantalum pentoxide, and titanium dioxide. They can be deposited by various methods, such as plasma-enhanced chemical vapor deposition, thermal evaporation, electron-beam evaporation, and sputtering. There are a number of dielectrics with refractive indices ranging from 1.45 to 2.4, facilitating diverse waveguide designs to satisfy different specification. Dielectrics have two other... 

After addition of solutions of fullerenes C60 or fulleiene C60-containing composites to the cell medium, the concentration of silicon dioxide was 0.02%, and that of fullerenes C60 - 10 5 M. Samples were placed in a glass tube and irradiated for 2 min by mercury-vapor lamp (power 24 W) at the distance of 5 cm. 

Dielectric Deposition Systems. The most common techniques used for dielectric deposition include chemical vapor deposition (CVD), sputtering, and spin-on films. In a CVD system thermal or plasma energy is used to decompose source molecules on the semiconductor surface (189). In plasma-enhanced CVD (PECVD), typical source gases include silane, SiH4, and nitrous oxide, N20, for deposition of silicon nitride. The most common CVD films used are silicon dioxide, silicon nitride, and silicon oxynitrides. 

M.E. Coltrin, P. Ho, H.K. Moffat, and R.J. Buss. Chemical Kinetics in Chemical Vapor Deposition Growth of Silicon Dioxide from Tetraethoxysilane (TEOS). Thin Solid Films, 365 251-263,2000. 

Silicon dioxide layers can be formed using any of several techniques, including thermal oxidation of silicon, wet anodization, CVD, or plasma oxidation. Thermal oxidation is the dominant procedure used in IC fabrication. The oxidation process selected depends on the thickness and properties of the desired oxide layer. Thin oxides are formed in dry oxygen, whereas thick (>0.5 fin1) oxide layers are formed in a water vapor atmosphere (13). 

The wafers were coated with silicon dioxide (400 nm thickness) and silicon nitride by low pressure chemical vapor deposition (LPCVD) alternately. The chips were fabricated by photolithography and etching. The catalyst (for the application Pt) was introduced as a wire (150 pm thickness), which was heated resistively for igniting the reaction. The ignition of the reaction occurred at 100 °C and complete conversion was achieved at a stochiometric ratio of the reacting species generating a thermal power of 72 W (Figure 2.28). 

Silicon Dioxide occurs as an amorphous substance that shows a noncrystalline pattern when examined by X-ray diffraction. It is produced synthetically, either by a vapor-phase hydrolysis process, yielding fumed silica, or by a wet process, yielding precipitated silica, silica gel, colloidal silica, or hydrous silica. Fumed silica is produced in an essentially anhydrous state, whereas the wet-process products are obtained as hydrates or contain surface-adsorbed water. 

The aluminum flakes can be coated with aluminum oxide and/or silicon dioxide in the liquid phase before the CVD process to reduce the reactivity of the metal and to create multilayer color effects. These pigments show strong angle-dependent coloristic effects (color travel) [5.158]. Metal halogenides are difficult to use as gas-phase precursors for metal oxide coating because of the reactivity of the metal flakes and the corrosion of steel in chloride atmospheres. The use of TiCU and water vapor was described about ten years ago. However, no commercial products have, as yet, been introduced. 

SAFETY PROFILE A highly corrosive irritant to the eyes, skin, and mucous membranes. Mildly toxic by inhalation, Explosive reaction with alcohols + hydrogen cyanide, potassium permanganate, sodium (with aqueous HCl), tetraselenium tetranitride. Ignition on contact with aluminum-titanium alloys (with HCl vapor), fluorine, hexa-lithium disilicide, metal acetylides or carbides (e.g., cesium acetylide, rubidium ace-tylide). Violent reaction with 1,1-difluoro-ethylene. Vigorous reaction with aluminum, chlorine + dinitroanilines (evolves gas). Potentially dangerous reaction with sulfuric acid releases HCl gas. Adsorption of the acid onto silicon dioxide is exothermic. See also HYDROGEN CHLORIDE (AEROSOL) and HYDROCHLORIC ACID. 

Violent reactions with ammonium salts, chlorate salts, beryllium fluoride, boron diiodophosphide, carbon tetrachloride + methanol, 1,1,1-trichloroethane, 1,2-dibromoethane, halogens or interhalogens (e.g., fluorine, chlorine, bromine, iodine vapor, chlorine trifluoride, iodine heptafluoride), hydrogen iodide, metal oxides + heat (e.g., beryllium oxide, cadmium oxide, copper oxide, mercury oxide, molybdenum oxide, tin oxide, zinc oxide), nitrogen (when ignited), silicon dioxide powder + heat, polytetrafluoroethylene powder + heat. 

In the production of many microelectronic devices, continuous chemical vapor deposition (CVD) processes are used to deposit thin and exceptionally uniform silicon dioxide films on silicon wafers. One CVD process involves the reaction between silane and oxygen at a very low pressure. 

Ion track formation in dielectric materials is becoming more and more interesting, since there are promising applications in sub micro and nanotechnology [1-3], Some papers have already reported experiments concerning the formation of nanometer-sized pores in silicon dioxide by means of MeV ion beams, and subsequent selective etching of ion tracks by liquid or vapor hydrofluoric acid [4-6],... 

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