S. Sedky et al., Experimental determination of the maximum post-process annealing temperature for standard CMOS wafers, IEEE DEVICE, 48(2), 2001, pp. 377-385
This paper reports on the experimental determination of the maximum post-pr
ocess annealing temperature for standard 0.35 mum CMOS wafers with Aluminum
based interconnections and tungsten plugs, without introducing significant
modifications to their standard characteristics. The impact of increasing
the postprocessing temperature from 475 degreesC to 575 degreesC, for perio
ds varying between 30 and 90 min, on both the front and back end is analyze
d. 0.35 mum CMOS technologies with different Al alloys, Al-1wt%Si-0.5wt%Cu
(AlSiCu) or Al-0.5wt%Cu (AlCu), and different back end structures are consi
dered. It is illustrated that the maximum annealing temperature is a functi
on of the structure and composition of the interconnection layers and their
maximum allowable resistance increase. It is also demonstrated that the tr
ansistor characteristics, the silicide quality and the leakage currents are
as good as unaffected by annealing for 90 min at temperatures up to 525 de
greesC.