La. Okada et Sm. George, Adsorption and desorption kinetics of tetrakis(dimethylamino)titanium and dimethylamine on TiN surfaces, APPL SURF S, 137(1-4), 1999, pp. 113-124
Titanium nitride (TiN) can be deposited using the organometallic precursor
tetrakis(dimethylamino)titanium (Ti[N(CH3)(2)](4)) (TDMAT). Deviations from
conformal TiN film growth have been observed in trench structures using TD
MAT. This nonconformal deposition may be associated with readsorption and s
ite blocking by the dimethylamine (HN(CH,),) (DMA) reaction product. To und
erstand the deviations from conformal TiN deposition in trench structures,
the adsorption and desorption kinetics for TDMAT and DMA were measured on a
sputter-deposited TiN surface using laser induced thermal desorption (LITD
) techniques. The LITD measurements revealed that DMA has a higher sticking
coefficient than TDMAT. The sticking coefficients for both TDMAT and DMA w
ere also dependent on surface coverage. The initial sticking coefficient fo
r TDMAT is S-0 = 0.23 with a coverage-dependence approximated by S(theta) =
0.25 exp(- 4.7 theta) where theta is the normalized surface coverage. The
initial sticking coefficient for DMA is S-0 = 0.70 and the coverage-depende
nce is approximated by S(theta)= 0.86 exp(-3.7 theta). The observed desorpt
ion kinetics of DMA following TDMAT and DMA exposures on TiN were also cove
rage-dependent. The isothermal desorption measurements could be fit using a
simple first-order desorption rate expression, k(d) = v(d)exp[-E-d(theta)/
RT] where E(theta) is the coverage-dependent desorption energy, E-d(theta)=
E-theta-E(1)theta. Assuming a desorption preexponential of v(d)=1x10(13) s(
-1), the observed isothermal desorption measurements for DMA desorption fol
lowing both TDMAT and DMA exposures could be fit using E-0 = 29.1 kcal mol(
-1) and E-1 = 8.2 kcal mol(-1). These measured adsorption and desorption ki
netics are consistent with DMA readsorption as a major contributor to nonco
nformal TiN growth in trench structures using TDMAT. (C) 1999 Published by
Elsevier Science B.V. All rights reserved.