A. Jain et al., CHEMICAL-VAPOR-DEPOSITION OF COPPER FROM (HFAC)CUL (L=VTMS AND 2-BUTYNE) IN THE PRESENCE OF WATER, METHANOL, AND DIMETHYL ETHER, Chemistry of materials, 8(5), 1996, pp. 1119-1127
The CVD of Cu using (hfac)Cu(VTMS) (hfac = hexafluoroacetylacetonate,
VTMS = vinyltrimethylsilane) and (hfac)Cu(2-butyne) in the presence of
water and other reagents has been studied. The overall CVD reaction i
nvolving disproportionation of these copper(I) compounds in the presen
ce of water is similar to the overall reaction in the absence of water
. The Cu films deposited at low water vapor flow rate (0.2 seem) exhib
ited near bulk resistivities (similar to 2.0 mu Omega cm) and dense su
rface morphologies while the Cu films deposited at higher water vapor
flow rate (2.4 seem) showed significantly higher resistivities (simila
r to 12 mu Omega cm) and porous morphologies. At higher water flow rat
es the deposition rate and conductivity of the films were reduced as a
result of Cu2O incorporation. The presence of water during CVD is bel
ieved to introduce a reaction parallel to the main CVD disproportionat
ion reaction via reaction of water with surface-bound [Cu(hfac)] and r
esults in the incorporation of copper(I) oxide (Cu2O) in the Cu films.
Labeling experiments using H2O18 showed that the oxygen incorporated
into the films (SIMS) at high water-flow rates was derived from reacti
on with H2O18. The deposition rate enhancements with methanol and dime
thyl ether showed similar trends as a function of flow rate but lower
overall rate enhancements compared to water. The presence of water is
believed to aid the dissociation of the L from the (hfac)CuL by hydrog
en bonding with the hfac ligand and/or oxygen donation to the copper(I
) center. The incorporation of Cu2O was completely suppressed by intro
duction of hfacH vapor along with the precursor and water vapor during
CVD of Cu.