KINETIC AND MECHANISTIC STUDIES OF THE CHEMICAL VAPOR DEPOSITION OF Ti-Si-N THIN FILMS WITH Ti(NMe_2)_4 (TDMAT), NH_3, and SiH_4

摘要

Various aspects of the kinetics and mechanism occurring during the thermal chemical vapor deposition of Ti-Si-N thin films using Ti(NMe_2)_4, tetrakis(dimethylamido)titanium (TDMAT), silane, and ammonia have been determined by molecular beam mass spectrometry coupled to a CVD reactor. Silane is activated in the presence of TDMAT and ammonia at 723 K. Additionally, multiple silane molecules are activated by each TDMAT molecule. The kinetics of the TDMAT decomposition (in the absence of silane and ammonia) were measured between 300 and 500 K. The rate constants for TDMAT decay increase with reactor surface-to-volume (S/V) ratio, particularly above 500 K. The Arrhenius plots for the TDMAT decay in these studies indictae a change in mechanism at higher temperatures. For S/V ratio = 0.118 mm~(-1), the Arrhenius parameters between 300 and 500 K are: E_a = 16 +- 2 kjJmol and A = 32 +-4 sec~(-1). For the high temperature regime above 500 K, E_a = 166 +- 16 kJ/mol and A = 1.6 (+- 0.2) x 10~(16) sec~(-1). These parameters are consistent with the following mechanistic interpretation for TDMAT decay: activated adsorption to the walls at low temperatures, followed by gas phase unimolecular decomposition in combination with some surface process at higher temperatures.