A study by In Situ FTIR Spectroscopy of the Decomposition of Precursors for the MOCVD of High Temperature Superconductors

Abstract

In this paper we report on a study by FTIR spectroscopy of the gas phase thermal decomposition of p(TMHD) 31, [Cu(TMHD)2] and [Ba(TDFND)2.tetraglyme] under a total pressure of I0 Torr, for a temperature range 200 -650°C, and in the absence and presence of oxygen. nie variation of the decomposition characteristics for each of the complexes as a function of temperature, and as shown by changes in the absorption coefficients, are related to the molecular structures.

Remote AP‐PECVD of Silicon Dioxide Films from Hexamethyldisiloxane (HMDSO)

“…[33] The fall off in refractive index at temperatures above~500 C could result from the removal of any carbonaceous material by oxidation. [34] The low refractive index results for the lower deposition temperatures are consistent with the corresponding FTIR spectra for the films. Figure 6 shows that, compared with the spectrum for a film deposited at 500 C (773 K) (Fig.…”

Gas Phase Vibrations as a Tool for the Characterization of CVD Precursors and Processes

“…This position offers some advantages in that IR windows do not need protection from condensation or deposition, [30] and measurements can be carried out at a constant temperature since, after a 40 cm path, all the output gases can be cooled to about 100 C. This last point is particularly important because the conversion to absolute concentrations needs molar absorption coefficients that depend nonlinearly on gas temperature, total pressure, and concentration of gas species, [38] and CVD reactors are used in wide ranges of these parameters. Some systems try to overcome these difficulties with strategies such as calibration at different temperatures, or recalculation of the IR spectra from tabulated spectroscopic constants.…”

“…[24] FTIR spectroscopy was also employed to control the evaporation rate of hexafluoroacetylacetonate platinum, [25] and the thermal behavior of diisopropoxide dipivaloylmethanato titanium. [26] In-situ FTIR analysis has been widely performed for kinetic purposes concerning propane for pyrocarbon deposition, [27] heterogeneous and homogeneous reactions during the decomposition of yttrium acetylacetonates, [28] copper acetylacetonates, [29] barium fluorinated acetylacetonates, [30] titanium tetraisopropoxide, [31] and tert-butylarsine and phosphine for epitaxial In 1±x Ga x As y P 1±y films. [32] The way in which in-situ FTIR measurements assist in the understanding of mechanism pathways is shown in a recent paper dealing with La(hfac) 3 diglyme.…”

Computational Algorithm for Dynamic Optimization of Chemical Vapor Deposition Processes in Stagnation Flow Reactors

“…Since the total deposition time enters as one of the optimization variables, the DAE integration problem requires a slight modification. In addition to the optimization parameters obtained from the continuous control parameterization, a new optimization variable p t is introduced so that the physical problem time is defined as t ϭ p t , t ʦ [0, t f ] [25] where The integrand of the multiobjective cost function is [27] where A inl and A sub are the reactor inlet and substrate areas, inl is the density of the gas at the inlet, and W ෆ is the mean molar mass of the gas at the inlet. The first term represents the cost associated with the precursor entering the reactor (i.e., a measure of precursor bypass) and the second term represents cost associated with processing time.…”