Electrical and micro-structural characterization of molybdenum tungsten
electrodes using a combinatorial thin film sputtering technique
Jun, S.-I., P.D. Rack, T.E. McKnight, A.V. Melechko, and M.L. Simpson, .
J. of Appl. Phys, 97(5), Mar. 1, 2005, 054906-01.
A
combinatorial rf magnetron sputter deposition technique
was employed to investigate
the electrical characteristics and
microstructural properties of molybdenum tungsten (MoW)
high temperature electrodes as a function of
the binary composition.
In addition to the composition,
the effect of substrate bias
and temperature was investigated. The
electrical resistivity of MoW samples
deposited at room temperature with zero bias
followed the typical
Nordheim's rule as a function of
composition. The resistivity increases
with tungsten fraction and is a maximum around
0.5 atomic
fraction of tungsten. A metastable
![beta](http://scitation.aip.org/stockgif3/bgr.gif)
-W
phase was identified and
the relative amount of the
![beta](http://scitation.aip.org/stockgif3/bgr.gif)
-W
phase scales with the
resistivity. Samples deposited at
higher temperature (250 °C) also followed Nordheim's
rule as a function of composition, however, it did not
contain the metastable
![beta](http://scitation.aip.org/stockgif3/bgr.gif)
-W
phase and consequently had a lower
resistivity. The resistivity of samples deposited
with substrate bias is
uniformly lower and obeyed the
rule of mixtures as a
function of composition. The molybdenum-rich
compositions had a lower resistivity,
contrary to expectations based on bulk resistivity
values, and is
attributed to high electron-dislocation
scattering cross sections in tungsten versus
molybdenum.
The metastable
![beta](http://scitation.aip.org/stockgif3/bgr.gif)
-W
phase was not observed in the
biased films even when
deposited at room temperature. High resolution
scanning
electron microscopy revealed a more dense structure for the
biased films, which is correlated to the
significantly lower film
resistivity. ©2005
American
Institute of Physics