Si nodules that appear in the Al-Si electrode of integrated circuits o
ften reduce their reliability. We have been studying methods for reduc
ing the Si nodules precipitated on an insulated film such as a BPSG fi
lm. In our previous study, we proposed a growth mechanism for Si nodul
es on the insulated film, based on the detailed analysis of the interf
ace between the Si nodule and the insulated film [6]. In this paper, t
he relationship between the Si contents (X) of Al-X wt.% Si film and t
he generation of the Si nodules is discussed in relation to the develo
ped growth mechanism of Si nodules on the insulated film. Al-X wt.% Si
films (X = 0.5, 0.7, 1.0, 3.3) deposited on the insulated film by spu
ttering method are annealed at 723 K for 30 min according to the usual
IC procedure. The Si nodules are observed by TEM, SEI (scanning elect
ron image) and SEM. In the case of X = 0.7 or more, Si nodules are pre
cipitated on the insulated film, while in the cast of X = 0.5, no Si n
odule is precipitated. According to the EDX analysis of the Si nodule/
BPSG interface, it is observed that al the central part of the interfa
ce, an Si-O layer is formed, and at the periphery, an Al-Si-P-O layer
is formed. It is thought that in the case of X=0.5, all of the Si nodu
les are dissolved in the Al film during annealing because the Si solub
ility in Al is 0.5 wt.% at 723 K according to the Al-Si phase diagram.
While in the case of X > 0.5 wt.%, Si nodules exist during annealing,
Si nodules are precipitated on the BPSG film after annealing. In the
case of X = 0.7, Si nodules are grown on the BPSG film, while in the c
ase of X = 3.3, the Si nodules are grown both on the BPSG film and wit
hin the Al film. The difference is thought to come from the Si content
s.