Abstract
We have investigated the effect of anodic bonding on silicon oxide by
measuring MOS capacitors situated in Pyrex cavities. We used two
different cavity depths, giving 1 µm or 200 µm vertical distance
between the gate electrode and the Pyrex. After bonding, we found that
the flat-band voltage of the capacitors situated in 1 µm deep cavities
had shifted towards more negative values. The shift corresponded to
6.6×1011cm-2 - 9.0×1011cm-2 increase in oxide charges area density. The
capacitors situated in 200 µm deep cavities showed a slight shift in
the opposite direction, which we attribute to thermal annealing of
oxide fixed charge. In addition, we observed that the current between
the gate and the substrate contact had increased after bonding. The
increase was by a factor between 20 and 150, depending both on cavity
depth and gate geometry. Some explanations for our observations are
suggested.
measuring MOS capacitors situated in Pyrex cavities. We used two
different cavity depths, giving 1 µm or 200 µm vertical distance
between the gate electrode and the Pyrex. After bonding, we found that
the flat-band voltage of the capacitors situated in 1 µm deep cavities
had shifted towards more negative values. The shift corresponded to
6.6×1011cm-2 - 9.0×1011cm-2 increase in oxide charges area density. The
capacitors situated in 200 µm deep cavities showed a slight shift in
the opposite direction, which we attribute to thermal annealing of
oxide fixed charge. In addition, we observed that the current between
the gate and the substrate contact had increased after bonding. The
increase was by a factor between 20 and 150, depending both on cavity
depth and gate geometry. Some explanations for our observations are
suggested.
