James W. Proscia

Single-Source Precursors to Niobium Nitride and Tantalum Nitride Films

Herein we report our efforts to prepare new precursors to niobium nitride (NbN) and tantalum nitride (TAN, Ta 3 N 5 ) thin films. Treatment of MC1 5 (M = Nb, Ta) with tertbutylamine in benzene solvent affords complexes of the formula [MCI 2 (N t Bu)(NH t Bu)(NH 2 t Bu)] 2 . The niobium complex [NbC1 2 (N t Bu)(NH t Bu)- (NH 2 t Bu)] 2 affords NbN films on glass substrates between 500-600 °C, while the tantalum analog [TaC1 2 (N t Bu)(NH t Bu)(NH 2 t Bu)] 2 gives films of Ta 3 N 5 in this temperature range. Treatment of MCI 5 (M = Nb, Ta) with 1,1-dimethylhydrazine in dichloromethane solvent affords complexes of the formula [MC1 2 (NNMe 2 )(NHNMe 2 )(NH 2 NMe 2 )]n. These hydrazido complexes afford cubic MN films upon glass substrates at ≥400°C. Analyses of the films are presented.

Assessment of Carbon Contamination in Titanium Nitride Films Deposited from the Reaction of Titanium (IV) Ciiloride and Amines

The reaction of titanium (IV) chloride and amines in an atmospheric pressure chemical vapor deposition (APCVD) has been previously shown to produce high quality titanium nitride films. These films were gold in appearance with high infrared reflectivity and resistivities as low as 80 microhm-cm. In the present study, the carbon content of the amines was systematically increased and the carbon levels in the films measured by XPS. For primary amines carbon contamination was not detected. Films deposited from secondary and tertiary amines had measurable carbon contamination. Correlation of carbon contamination with electrical resistivity and infrared reflectivity is discussed. Scanning electron micrographs and x-ray diffraction of the films are presented.

Sem Analysis of the Nucleation of Tin Oxide Films on Glass Surfaces

Fluorine-doped tin oxide films were produced by atmospheric pressure chemical vapor deposition (APCVD) from the reaction of tin tetrachloride, water, and difluoroethanc. Tin oxide films deposited on glass substrates containing high sodium concentrations tended to be of lower quality with higher resistivities than films deposited on low sodium glass. Scanning electron Microscopy (SEM) was used to study the differences in film nucleation on the high and low sodium containing glass substrates. Eiarly in the nuclcation process, individual grains of tin oxide crystals arc observed to be distributed discontinuously over the substrates. As the deposition time was increased the number of nucleation sites increased and the individual grains became larger. The number of nucleation sites was consistently higher on the high sodium glass. However, numerous inclusions of sodium chloride crystals were observed by EDX in the tin oxide films deposited on the high sodium glass. SEM cross sections revealed how the film growth converted from the grains, which initially nucleated on the glass surface, to columns in the direction perpendicular to the substrate surface. Results for tin oxide grown on sodium-containing glass over coated with silica are also be presented.

Chemical Vapor Deposition of Vanadium Oxide Tiiin Films

Vanadium oxide thin films were grown on glass substrates by atmospheric pressure chemical vapor deposition (APCVD) from the reaction of vanadium(IV) chloride with isopropanol and t-butanol. Films were deposited in the temperature range 250 to 450°C. The as-deposited films were a dark greenish color consistent with formation of a lower oxide of vanadium. Annealing a film deposited on Corning 7059 glass in air converted the material to a yellow film. X-ray diffraction of the yellow film revealed the presence of V 2 O 5 . Optical spectra of the films are presented. Glass substrates previously coated with conductive fluorine doped tin oxide were coated with V 2 O 5 and evaluated for electrochromic activity.

Visualization of atmospheric pressure chemical vapor deposition and powder spray pyrolysis by laser light scattering

Atmospheric Pressure Chemical Vapor Deposition (APCVD) and powder spray pyrolysis are both pyrolytic thin film deposition techniques that are used to coat glass with thin films at atmospheric pressure. In the present study, the fluid dynamics of each process was investigated by laser light scattering. For each system, a 193 nm ArF excimer laser pulsed at 7 Hz was used for the analysis. In the case of the APCVD reactor, the difference in Rayleigh scattering between helium injected in the reactor and ambient air was used to characterize the process. For the powder spray process, laser scattering off the sprayed powder was used. The effect of various parameters is discussed.

The Utility of Laser Light Scattering in Assessing the Mixability of Reagents for Chemical Vapor Deposition

The premixability of reagents used in chemical vapor deposition reactors is important to insure that gas feed lines and nozzles do not become clogged with particulates during operation. Even if reactants are to be kept separate until introduced into a reaction chamber, it is desirable to limit the number of particles formed. A reactor which utilizes laser light scattering to monitor particulate formation when gaseous reagents are mixed is described. The reaction of tin (IV) chloride with water is commonly used to produce tin oxide films by chemical vapor deposition. It was found by the light scattering experiment that at temperatures above about 110°C the number of particulates formed is greatly reduced. Therefore, it would be most desirable that these reagents be mixed above this temperature when depositing tin oxide from this reaction. The reaction of titanium tetrachloride with various amine was also investigated by this method. This reaction has been demonstrated to produce titanium nitride above 450°C. For each case, it was observed that there was a temperature above which the number of particulates was significantly reduced. This temperature was always below the optimal temperature for producing titanium nitride films.