Jw. Klaus et al., Atomic layer deposition of tungsten using sequential surface chemistry with a sacrificial stripping reaction, THIN SOL FI, 360(1-2), 2000, pp. 145-153
Tungsten (W) films were grown with atomic layer control using a novel seque
nce of self-limiting surface reactions. The tungsten film growth was achiev
ed by dividing the binary reaction WF6 + Si2H6 --> W + 2SiHF(3) + 2H(2) int
o two separate half-reactions. Alternating exposures to WF6 and Si2H6 in an
ABAB... sequence produced tungsten deposition at temperatures between 425
and 600 K. The Si2H6, reactant served only a sacrificial role to strip fluo
rine from tungsten without incorporating into the film. FTIR spectroscopic
investigations demonstrated that the WF6 and Si2H6 half-reactions were comp
lete and self-limiting at T > 400 K, In situ spectroscopic ellipsometry mea
surements determined a tungsten growth rate of 2.5 Angstrom/AB cycle with W
F6 and Si2H6 reactant exposures sufficient for complete half-reactions. The
surface topography of the deposited tungsten films was flat indicating smo
oth film growth. The tungsten films were either amorphous or composed of ve
ry small crystalline grains and contained no measurable silicon or fluorine
. These results represent the first. demonstration of atomic layer depositi
on of smooth single-element metal films using sequential surface chemistry.
(C) 2000 Elsevier Science S.A. All rights reserved.