The stability of glazed silicon surfaces to water attack

IBM has developed a glassing technology for the passivation of transistors and diodes. For effective surface protection, the glass should have long-term stability to ambient attack, particularly moisture attack. Since it is difficult to evaluate all glasses under moderate moisture conditions for extended periods, several accelerated tests for determining the stability of glasses to water and humidity were compared. Although the results obtained from exposure of a glassed silicon wafer to boiling water for times ranging from a few minutes to an hour were more severe than those obtained by conventional long-term humidity tests, the results could be correlated. The films were evaluated by infrared spectroscopy and by changes in weight, thickness, and microscopic appearance. It was found that glazed silicon surfaces can best be evaluated for water stability by comparison of the infrared spectra of the films before and after boiling in water. Changes in film thickness or weight was found to be insufficient for a complete evaluation.