Various aspects of the kinetics and mechanism occurring during the gas-phase thermal decomposition of Ti(N(CH 3 ) 2 ) 4 , tetrakis(dimethylamido)titanium, have been determined by in situ molecular beam mass spectrometry coupled to a chemical vapor deposition reactor. The rate of Ti(N(CH 3 ) 2 ) 4 decomposition was measured between 333 and 583 K. The rate constants increase with reactor surface area to volume ratio (S/V), particularly above 530 K (S/V ) 0.118 mm -1 ), which indicates a change in mechanism at higher temperatures. For S/V ) 0.118 mm -1 , the Arrhenius parameters between 300 and 530 K are E a ) 16 ( 2 kJ mol -1 and A ) 32 ( 4 s -1 . For the high-temperature regime above 530 K, E a ) 166 ( 16 kJ mol -1 and A ) (1.6 ( 0.2) × 10 16 s -1 . These parameters are consistent with the following mechanistic interpretation for Ti(N(CH 3 ) 2 ) 4 decomposition: activated adsorption to the walls at low temperatures, followed by gas-phase unimolecular decomposition in combination with some surface process at higher temperatures. Mass spectral evidence supports β-hydride elimination and metallacycle formation as the TDMAT decomposition pathways.

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Molecular beam mass spectrometry has been used to observe the activation of silane, predominantly in the gas phase, during the chemical vapor deposition of Ti-Si-N thin films using Ti(NMe 2 ) 4 , tetrakis(dimethylamido)titanium, silane, and ammonia at 450 °C. The extent of silane reactivity was dependent upon the relative amounts of Ti(NMe 2 ) 4 and NH 3 . Ti-Si-N thin films were deposited using similar process conditions as the molecular beam experiments. RBS and XPS were used to determine the atomic composition of these films. The variations of the Ti:Si ratio as a function of Ti(NMe 2 ) 4 and NH 3 flows were consistent with the changes in silane reactivity under similar conditions.

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