INVESTIGATIONS OF THE GROWTH OF TIN THIN-FILMS FROM TI(NME2)4 AND AMMONIA

Growth of clean (<5% carbon), stoichiometric (Ti:N = 1.15 +/- 0.1) titanium nitride thin films on Si(100) substrates from the reaction of tetrakisdimethylamido titanium, Ti(NMe2)4, and ammonia is reported. Films were deposited using a novel gas delivery system which allowed the reactants to be mixed at elevated pressures with the substrate held in high vacuum. The films were analyzed using Rutherford backscattering and Auger electron spectroscopy while the gas-phase chemistry was monitored by mass spectrometry. The quality of the films was measured as a function of gas pressure, reactant ratio, and substrate temperature. Growth on patterned wafers gave information on reactant sticking coefficients and surface mobilities. The reaction of Ti(NMe2)4 with (NH3)-N-15 or ND3 clearly showed that both the nitrogen in a clean TiN film and the hydrogen (deuterium) in the gaseous dimethylamine product are derived exclusively from the ammonia. Mass spectrometry studies Indicate that the reactive intermediate may be a high molecular weight oligomer consisting of Ti, N, H, and perhaps C. These finding are discussed both in terms of their impact on understanding the growth mechanism, as well as on the potential of this precursor system to be used in a manufacturing process.