Deoxidization of Water Desorbed from APCVD TEOS ­ O 3 SiO2 Film with Thin Titanium Cap Film

The water absorption characteristics and desorption characteristics of atmospheric-pressure chemical vapor deposited (APCVD) tetraethylorthosilicate and ozone (TEOS-O 3 ) film have been studied in detail to apply TEOS-O 3 film to LSI intermetal dielectric film. TEOS-O 3 film absorbs a large amount of water from the air, and desorbs the water at 200°C or less. It has also been found that titanium thin film deposited on TEOS-O 3 film suppresses water desorption from TEOS-O 3 film completely. Titanium thin film deoxidizes water desorbed from TEOS-O 3 film to hydrogen even at 200°C or less. The reliability of aluminum wiring with TEOS-O 3 intermetal dielectric film has not been sufficient because of aluminum film bursting in the via-hole formed on TEOS-O 3 film during high-temperature storage testing at 150°C or more. However, if titanium thin film is used as the lowest layer of the accumulating aluminum wiring structure on TEOS-O 3 film, aluminum bursting in the via-hole is suppressed completely. We consider the aluminum bursting to be caused by water pressure during the high-temperature storage testing, and the suppression by the titanium thin film to be caused by titanium deoxidization of water to hydrogen.