Jc. Chiou et Mc. Chen, THERMAL-STABILITY OF CU COSI2 CONTACTED P+N SHALLOW JUNCTION WITH ANDWITHOUT TIW DIFFUSION BARRIER/, Journal of the Electrochemical Society, 141(10), 1994, pp. 2804-2810
The thermal stability of Cu/CoSi2 contacted p+n shallow junction diode
s with and without TiW diffusion barrier was investigated with respect
to metallurgical reaction and electrical characteristics. Without the
diffusion barrier, the Cu (2000 angstrom)/CoSi2 (700 angstrom)/p+n di
odes (with a junction depth of 0.2 mum measured from the silicide surf
ace) were able to sustain a 30 s rapid thermal annealing (RTA) in N2 a
mbient up to 450-degrees-C without losing the integrity of the devices
characteristics. The Cu3Si phase was observed at the CoSi2/Si interfa
ce after 500-degrees-C annealing; the phase penetrated through the CoS
i2 layer causing a catastrophic change in layer structure after 700-de
grees-C annealing. With the addition of a 1200 angstrom thickness of T
iW diffusion barrier between Cu and CoSi2, the junction diodes were ab
le to sustain the RTA treatment up to 775-degrees-C without degrading
the basic electrical characteristics, and no metallurgical reaction co
uld be observed even after an 800-degrees-C annealing.