EFFECT OF ANODIC BONDING ON RELIABILITY OF SENSORS AND MOS CIRCUITRY

摘要

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 6.6-10~(11)cm~(-2) -9.0-10~(11)cm~(-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.