Abstract
The chemistry of dielectric-breakdown-induced microstructural changes in
Hf
O
2
high-
κ
/polycrystalline silicon gate
n
MOSFETs
under constant voltage stress has been studied. Based on an electron energy loss spectrometry analysis, the hafnium and oxygen chemical bonding in the breakdown induced Hf-based compounds of a "
ball-shaped
" defect is found to be different compared to the stoichiometric
Hf
O
2
and
Si
O
2
. The formation of possibly
Hf
Si
x
O
y
and
Hf
Si
x
compounds in the "
ball-shaped
" defect is attributed to a thermochemical reaction triggered by the gate dielectric breakdown.