Tungsten nitride films were deposited with atomic layer control using seque
ntial surface reactions. The tungsten nitride film growth was accomplished
by separating the binary reaction 2WF(6) + NH3 --> W2N + 3HF + 9/2F(2) into
two half-reactions. Successive application of the WF6 and NH3 half-reactio
ns in an ABAB... sequence produced tungsten nitride deposition at substrate
temperatures between 600 and 800 K. Transmission Fourier transform infrare
d (FTIR) spectroscopy monitored the coverage of WFx* and NHy* surface speci
es on high surface area particles during the WF6 and NH3 half-reactions. Th
e FTIR spectroscopic results demonstrated that the WF6 and NH3 half-reactio
ns were complete and self-limiting at temperatures greater than or equal to
600 K. In situ spectroscopic ellipsometry monitored the film growth on Si(
100) substrates vs. temperature and reactant exposure. A tungsten nitride d
eposition rate of 2.55 Angstrom/AB cycle was measured at 600-800 K for WF6
and NH3 reactant exposures greater than or equal to 3000 L and 10,000 L, re
spectively. X-ray photoelectron spectroscopy depth-profiling experiments de
termined that the films had a W2N stoichiometry with low C and O impurity c
oncentrations. X-ray diffraction investigations revealed that the tungsten
nitride films were microcrystalline. Atomic force microscopy measurements o
f the deposited films observed remarkably flat surfaces indicating smooth f
ilm growth. These smooth tungsten nitride films deposited with atomic layer
control should be useful as diffusion barriers for Cu on contact and via h
oles. (C) 2000 The Electrochemical Society. S0013-4651(99)05-028-4 All righ
ts reserved.