Chemical vapor deposition procedure

Chemical Vapor Deposition Procedure. A horizontal hot-wall quartz-tube reactor was employed. The precursor was heated using an oil bath at 120-140 C using air or nitrogen as a carrier gas. The pressure in the reactor was maintained at ca. 0.5-2.0 torr by continuous pumping. The substrates were Si wafer pieces or SIC fibers which were maintained at ca. 600 C using an external tube furnace. Deposition rates varied from ca. 0.1 - 1 nm/hi depending on the precursor temperature and the flow rate into the reactor. 

Deposition of Thin Films. Laser photochemical deposition has been extensively studied, especially with respect to fabrication of microelectronic stmctures (see Integrated circuits). This procedure could be used in integrated circuit fabrication for the direct generation of patterns. Laser-aided chemical vapor deposition, which can be used to deposit layers of semiconductors, metals, and insulators, could define the circuit features. The deposits can have dimensions in the micrometer regime and they can be produced in specific patterns. Laser chemical vapor deposition can use either of two approaches. 

This procedure, with minor variations, is repeated dozens of times in the manufacture of a semiconductor chip. The chemical treatment can be carried out using reagents in a liquid phase, but gas-phase treatment by a process known as chemical vapor deposition (CVD) has become more important as individual features in the integrated circuit become smaller. 

Chemical vapor deposition (CVD) of carbon from propane is the main reaction in the fabrication of the C/C composites [1,2] and the C-SiC functionally graded material [3,4,5]. The carbon deposition rate from propane is high compared with those from other aliphatic hydrocarbons [4]. Propane is rapidly decomposed in the gas phase and various hydrocarbons are formed independently of the film growth in the CVD reactor. The propane concentration distribution is determined by the gas-phase kinetics. The gas-phase reaction model, in addition to the film growth reaction model, is required for the numerical simulation of the CVD reactor for designing and controlling purposes. Therefore, a compact gas-phase reaction model is preferred. The authors proposed the procedure to reduce an elementary reaction model consisting of hundreds of reactions to a compact model objectively [6]. In this study, the procedure is applied to propane pyrolysis for carbon CVD and a compact gas-phase reaction model is built by the proposed procedure and the kinetic parameters are determined from the experimental results. 

The Re0 7HZ catalyst was prepared by the following procedure. Methyl trioxorhenium (MTO) was sublimed under vacuum at 333 K and the vapor was allowed to enter the chamber, where the zeolites were pretreated in situ at 673 K under vacuum. After the chemical vapor deposition (CVD) into zeolite pores, undeposited MTO was removed by evacuation at RT. The catalyst was treated at 673 K in He before using. 

The steam reformer is a serpentine channel with a channel width of 1000 fim and depth of 230 fim (Figure 15). Four reformers were fabricated per single 100 mm silicon wafer polished on both sides. In the procedure employed to fabricate the reactors, plasma enhanced chemical vapor deposition (PECVD) was used to deposit silicon nitride, an etch stop for a silicon wet etch later in the process, on both sides of the wafer. Next, the desired pattern was transferred to the back of the wafer using photolithography, and the silicon nitride was plasma etched. Potassium hydroxide was then used to etch the exposed silicon to the desired depth. Copper, approximately 33 nm thick, which was used as the reforming catalyst, was then deposited by sputter deposition. The reactor inlet was made by etching a 1 mm hole into the end... 

A range of procedures have been described for the silanization of glass, including approaches employing both elevated and room-temperature organic phase, aqueous phase, vapor phase, and chemical vapor deposition of the silane. However, little has been published with regard to the rehability and... 

Matlhoko L, Pillai SK, Moodley M et al (2009) A comparison of purification procedures for multi-walled carbon nanotubes produced by chemical vapor deposition. J Nanosci Nanotechnol 9 5431-5435... 

This CVD procedure is somewhat different from that used to deposit semiconductor layers. In the latter process, the primary reaction occurs on the substrate surface, following gas-phase decomposition (if necessary), transport, and adsorption. In the fiber optic process, the reaction takes place in the gas phase. As a result, the process is termed modified chemical vapor deposition (MCVD). The need for gas-phase particle synthesis is necessitated by the slow deposition rates of surface reactions. Early attempts to increase deposition rates of surface-controlled reactions resulted in gas-phase silica particles that acted as scattering centers in the deposited layers, leading to attenuation loss. With the MCVD process, the precursor gas flow rates are increased to nearly 10 times those used in traditional CVD processes, in order to produce Ge02-Si02 particles that collect on the tube wall and are vitrified (densified) by the torch flame. 

Many [M(dik)4] complexes are volatile, especially those that contain fluorinated diketonate ligands. Mass spectra and gas chromatographic behavior of several of these complexes have been studied (see Table 10). Isenhour and coworkers240 241 have employed fluorinated diketonates in mass spectrometric procedures for determination of Zr and Zr/Hf ratios in geological samples. The most intense peak in mass spectra of [M(dik)4] complexes is [M(dik)3]+. Sievers et al.242 have used gas chromatography of metal trifluoroacetylacetonates to separate Zr from Al, Cr and Rh. However, attempts to separate [Zr(tfacac)4] and [Hf(tfacac)4] by gas chromatography were unsuccessful. Zirconium and hafnium can be separated by solvent extraction procedures that employ fluorinated diketones.105 [M(dik)4] (M = Zr or Hf dik = acac, dpm, tfacac or hfacac) have been used as volatile source materials for chemical vapor deposition of thin films of the metal oxides.243,244... 

Different procedures have been established chemical vapor deposition [5, 16], powder sintering combined with pressing [1, 2, 6, 7, 12, 17-25], sputtering [9, 26], flux and melt grown [10, 27, 28], chemical deposition [11, 14, 29, 30], sol-gel techni-ques [31], mechano-chemical pro-cessing [32], forced hydrolysis [33,34], spray pyrolysis [35-41], and thermal and hydro- thermal oxidation [3, 4, 8, 10, 17,42-58]. 

Ceramic and semiconductor thin films have been prepared by a number of methods including chemical vapor deposition (CVD), spray-coating, and sol-gel techniques. In the present work, the sol-gel method was chosen to prepare uniform, thin films of titanium oxides on palladium Titanium oxide was chosen because of its versatility as a support material and also because the sol-gel synthesis of titania films has been clearly described by Takahashi and co-workers (22). The procedure utilized herein follows the work of Takahashi, but is modified to take advantage of the hydrogen permeability of the palladium substrate. Our objective was to develop a reliable procedure for the fabrication of thin titania films on palladium, and then to evaluate the performance of the resulting metalloceramic membranes for hydrogen transport and ethylene hydrogenation for comparison to the pure palladium membrane results. 

This reference provides in-depth coverage of the technologies and various approaches in luminous chemical vapor deposition (LCVD) and showcases the development and utilization of LCVD procedures in industrial scale applications—offering a wide range of examples, case studies, and recommendations for clear understanding of this innovative science. 

Unfortunately, current S3mthesis techniques, such as chemical vapor deposition, arc discharge, laser ablation, or detonation, typically lead to a mixture of various nanostructures, amorphous carbon, and catalyst particles rather than a particular nanostructure with defined properties, thus limiting the number of potential applications [1]. Even if pure materials were available, the size-dependence of most nanomaterial properties requires a high structural selectivity. In order to fully exploit the great potential of carbon nanostmctures, one needs to provide purification procedures that allow for a selective separation of carbon nanostructures, and methods which enable size control and surface functionalization. 

PS-I23 Microelectronic devices are formed by first forming Si02 on a silicon wafer by chemical vapor deposition (Figure P5-12 cf. Problem P3-25). This procedure is followed by coating the SiOj with a polymer called a photoresist. The pattern of the electronic circuit is then placed on the polymer and the sample is irradiated with ultraviolet light. If the polymer is a positive photoresist, the sections that were irradiated will dissolve in the appropriate solvent and those sections not irradiated will protect the S1O2 from further treatment The wafer is then exposed to strong acids, such as HP, which etch (i.e, dissolve) the... 

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