Abstract
A new configuration of conductive atomic force microscope (CAFM) is presented, which is based in a conventional AFM with a logarithmic current-to-voltage (log
I
-
V
) amplifier. While a standard CAFM allows to measure a current dynamic range of typically three orders of magnitude
(
0.1
-
100
pA
)
, with the new setup it is possible to measure up to nine orders of magnitude. The extended current range allows to evaluate the reliability of gate dielectrics in a single electrical test, overcoming the limitations of standard CAFM configurations. The setup has been tested by analyzing breakdown (BD) spots induced in
Si
O
2
and high-
k
layers. For current measurements, the results show that
I
-
V
characteristics and current images (measured at a constant voltage) can be easily obtained in a wide dynamic range, which can reveal new details of the BD mechanisms. In particular, the setup was used to investigate the area electrically affected by the breakdown event in
Si
O
2
and
Hf
O
2
∕
Si
O
2
stacks.