Kinetic and Mechanistic Studies of the Thermal Decomposition of Ti(N(CH₃)₂)₄ during Chemical Vapor Deposition by in Situ Molecular Beam Mass Spectrometry

Abstract

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.

Structure and photoluminescence of the TiO2 films grown by atomic layer deposition using tetrakis-dimethylamino titanium and ozone

“…On the contrary, in the O 3 -based process, the desorption of intermediate products is suppressed without the surface adsorption of the -OH groups from H 2 O vapor; therefore, a wider ALD saturated growth temperature window from 100°C to 250°C was observed, and the growth rate shows a strong increase of from 0.58 to 4.08 Å/cycle with increasing the growth temperature from 250°C to 400°C. The strong increase of the growth rate is due to the chemical vapor deposition (CVD) process which is related to the strong thermal decomposition of the TDMAT precursor [ 41 , 42 ] at temperature above 250°C.…”

Structure and photoluminescence of the TiO2 films grown by atomic layer deposition using tetrakis-dimethylamino titanium and ozone

“…The strong increase of the growth rate is due to the chemical vapor deposition (CVD) process which is related to the strong thermal decomposition of the TDMAT precursor [41,42] at temperature above 250°C. Figure 2 shows the XRD patterns of the TiO2 films deposited at different growth temperatures from 175°C to 400°C.…”

Synthesis of Nanocrystalline Zr3N4 and Hf3N4 Powders from Metal Dialkylamides

“…The first one is intramolecular β-hydrogen activation leading to formation of metallocycle MϪNϪC rings with strong MϪC bonds [22]. An evidence for this process was found in experiments on deposition of TiN films using pure titanium dialkylamides [23,24] or in the presence of ammonia [6,22]. At elevated temperatures the rate of β-hydrogen activation increases and causes a higher carbon contamination.…”