CVD-diagrams

The substitution of TiCU for WCI4 yields the CVD diagram as shown in Fig. 10.90 (Vahlas et al. 1996) and it can clearly be seen that the CVD diagram is totally different, demonstrating both the system specific nature of such diagrams and the importance of the underlying thermodynamics in determining how the process will occur in practice. 

If diffusion and chemical reaction rate coefficients are high with respect to the flow of the bulk reactant gas supply (similar to the situation of a well-stirred reactor in which the contents are in thermodynamic equilibrium), so-called CVD diagrams or stability diagrams can be used to predict the process conditions necessary for... 

What is a CVD diagram and what sort of information in it is useful for choosing process conditions What are the limitations of CVD diagrams ... 

The chemical potential diagram for this ternaty system (Figure 3.3) shows that the reaction with the elements would reduce the iodine pressure to a very low value, which is not suitable for CVD, whereas tire compound Ta5Si3, in which the chemical potentials of the two elements are about 40kJgram-atom would be suitable for CVD at about 1300 K. 

Fig. 7. Bachmann diagram for CVD diamond film growth (adapted from [80].)...

Figure 16.6. Diagram of CVD apparatus for the deposition of solar-control coatings on glass.

Figure 16.12. Diagram of plasma-CVD apparatus for optical fiber production.

The following diagram, given as 6.17.3 on the next page, shows the cyclic natiu e of the steps used to form the intermediate layers of an electronic device. In this case, we have shown at least 8 individual steps needed to fabricate this structure. Note that the use of photoresist is not indicated in the CVD steps, although it plays a significant role in the overall process. Note that these same 8 steps can be repeated so as to build up a series of electrical and isolated layers which comprise the overall IC design... 

Features common to all CVD reactors include source evaporators with an associated gas handling system to control input gases and gas-phase precursor concentrations, a reactor cell with a susceptor heated by either radio frequency or infrared radiation, and an exhaust system to remove waste products (which may include a vacuum pump for low-pressure operations). Substrate temperatures can vary from less than 200 °C to temperatures in excess of 1000 °C, depending on the nature of the material layer and precursor used. Schematic diagrams of some simple CVD reactors are shown in Figure 4. 

CVD processes, 24 746 CVS system flow, 10 33, 35 CW laser beam, 14 673, 674 Cyagard RF1204, 11 496 Cyan, CIE chromaticity diagram, 7 313, 315. See also Cyan dyes... 

Figure 8 Schematic diagram of experimental setup for photo-CVD polysilane synthesis.

Figure 10J8 Calculated CVD phase diagram for die WG2-SiH4-H2-Ar system at r-1000 K, 1 atm and P =0.9 atm (flom Vahlas et al. 1996).

Figure 10.89 Calculated CVD phase diagram for the WCU-SiCl2H2-Hr Ar system at T= 1000 K, Aoui I and AV 0.9 atm (irom Vahlas et al. 1996).

The chemical vapour deposition (CVD) technique can be regarded as an extension of the sublimation method used for the preparation of single crystals discussed before, but adapted to thin him growth implying deposihon on substrates. A schematic diagram of a horizontal hot-wall CVD apparatus is shown in Fig. 3.15. 

Figure 15 On-chip microplasma reactor using nanostructured electrodes, (a) silicon chip before and after a CVD process for nanostructure growth, (b) microplasma reactor, and (c) general diagram of the device (Agiral et al., 2008b reproduced with permission).

Figure 4 Equilibrium CVD phase diagram for the Nb-Ge-H-CI system. The diagram was constructed from thermodynamic calculation results and depicts the condensed phases which form as a function of experimental variables. The Nb/(Nb+Ge) values are reactant gas concentrations. After Wan.9...

Figure 13.1 Schematic diagram showing various components of a CVD system (1 reactor 2 heating element 3 reaction tube 4 water-cooled end flanges 5 power controller 6 pressure indicator 7 temperature sensor 8,10,11. -precursor gas tanks, 9 metal halide (liquid) vaporizer 12 particulate trap 13 gas scrubber 14 flow meter 15 flow meter valves 16 gas tank regulators 17 substrate support 18 substrates).

The CVD process was carried out hrst at Atmospheric Pressure (AP-CVD), as illustrated by the typical schematic diagram shown in Fig. 6.1. Later on, the pressure was reduced to 0.1-10Torr, in order to improve further the control of the chemical reactions involved in the deposition process, and thus, also improve the thickness homogeneity of the resulting layers [2,4,9,16-18]. A further advantage of the low-pressure CVD (LP-CVD) process is that the... 

Fig. 6.46. Schematic diagram of the expanding thermal plasma aixtron reactor system used at Eindhoven University of Technology to deposit PE-CVD ZnO films [51]. DEZ and oxygen are used as precursors for ZnO formation. Trimethyl-aluminium (TMA) is used as doping source. The total pressure is 2.5mbar and the substrate temperature is varied from 200 to 350°C. Reprinted with permission from [85]...

Because of the low volatility of Group 2 compounds, even more extreme methods to ensure that the precursor can reach the substrate have been used. In many cases described in Section IV, a container with the Group 2 element precursor was placed directly inside the CVD reactor adjacent to the substrate. A schematic diagram of a typical reactor setup is shown in Fig. 3.31 This has often led to successful transport of the Group 2 precursor to the heated substrate surface, but it is unlikely that these conditions can be scaled up for practical applications. 

In summary, this brief review of the synthesis of Group 2 /3-diketonate compounds shows how sensitive the outcome of the reaction is to the nature of the reaction conditions. As a result, it is often difficult to determine exactly which species have been used in CVD experiments when, for example, the species Ba(dpm)2 has been used and obtained from a commercial source. Indeed, the CVD literature is often misleading, with figures showing schematic diagrams of the molecular structure of monomeric Ba(dpm)2 as the source used for CVD experiments.215... 

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