Possible Mechanisms for Applications of Polarizable and OH-Containing Glasses to MOS Devices

The selection of materials for semiconductor device passivation was investigated as regards the application of ZnO- and PbO-based glasses in MOS (metal, oxide, and silicon) devices. It was found that mechanisms affecting the application of these glasses to MOS devices were related to the molar polarizabilities and the OH radical contents in glasses. With regard to the recovery of C-V (capacitance-voltage) hysteresis loops in MOS capacitors, ZnO-based glasses were found to be superior to PbO-based glasses, since the molar polarizability of ZnO-based glasses was smaller than that of PbO-based glasses. The concentration of OH radicals depends on the composition of the glasses and had a negative effect on the recovery of C-V curve shifts in MOS capacitors passivated by these glasses. The glasses had low-temperature reflow below 800℃; PbO-based glasses had lower flow points than ZnO-based glasses. The possible mechanisms for the recovery of △V(↑-)G shifts in C-V hysteresis loops were elucidated by the use of Poisson’s equation and OH absorption coefficients.

Keiji Kobayashi
Toshiba ULSI Research Center, 1-Komukai Toshibacho, Kawasaki, Japan