Deoxidization of Water Desorbed from APCVD TEOS-O3 SiO2 by Titanium Cap Layer

The water absorption and desorption characteristics of APCVD TEOS-0, SiO, have been studied by exposing SiO, films deposited at 380°C in differenl. 0, concentrations to a water-vapor ambient. The total amount of water desorbed from the film decreased with the increasing 0, concentration. In contrast, water desorbed from the film at temperature lower than 300°C increased. In the application of TEOS-0, SiO, as an intermetal didectric, water desorption at lower temperatures causes the bursting of via holes during high-temperature storage tests. It was found that, however, a thin titanium film deoxidizes water desorbed from TEOS-0, SiO, to hydrogen. The bursting of via holes was completely suppressed by using thin i.itanium film between the aluminum and TEOS-0, SiO, lbecause hydrogen passes more easily than water through the aluminum interconnect.