Km. Chang et al., Barrier characteristics of chemical vapor deposited amorphous-like tungsten silicide with in situ nitrogen plasma treatment, J ELCHEM SO, 146(7), 1999, pp. 2533-2539
Our team investigated the characteristics of inserting an 80 nm amorphous-l
ike WSi1.6N0.5N/WSi1.6 barrier layer between aluminum film and a shallow di
ode to retard aluminum and silicon interdiffusion. In one chamber without b
reaking vacuum, we used a nitrogen plasma treatment to stuff nitrogen atoms
into the grain boundaries of amorphous-like tungsten silicide film. The ni
trogen atoms eliminated the fast diffusion paths of film, thus giving the a
morphous-like tungsten silicide film a smaller diffusion coefficient. We th
en examined the failure of diodes with amorphous-like WSi1.6N0.5/WSi1.6 bar
riers which were annealed at 575 degrees C for 30 min and which had leakage
currents of 10(7) and 10(8) nA/cm(2). These diodes failed due to the diffu
sion of aluminum along the sidewalls of the barriers and the field oxide in
terface. In the search for a solution to this problem we investigated the u
se of tetraethylorthosilicate, which is known for its thermal stability as
a stress buffer. In this experiment we used tetraelhylorthosilicate to form
a "contact array structure" which in turn prevented diode failure at 575 d
egrees C annealing for 30 min, and furthermore, the diodes in the contact a
rray structure only began to show evidence of degradation at 600 degrees C.
(C) 1999 The Electrochemical Society. S0013-4651(98)09-086-7. All rights r
eserved.