A schematic reaction mechanism is proposed to explain the Ti/TiN chemi
cal vapor deposition (CVD) process using the TiCl4 molecule as the sou
rce species. The scheme can be considered as two successive steps: (I)
TiCl4 molecules are adsorbed onto surface reactive sites through conc
erted electron delocalizations, (II) ambient reducing agents such as H
-2 or NH3 reactively eliminate Cl atoms from Ti atoms in the form of H
Cl. Preliminary molecular orbital (MO) calculations indicate that step
(I) is an energetically easy process. Conversely, step (II) is expect
ed to be the rate-determining process with a considerable activation e
nergy. As a whole, the characteristics of resultant CVD films (e.g., t
he conformality) are probably controlled not by the TiCl4-adsorption s
tep (I) but by the Cl elimination step (II).