Tungsten via poisoning caused by water trapped in embedded organic low-K dielectrics

The control of hygroscopicity in dielectric films is one of the key technologies applied in the fabrication of multilevel interconnections. By experiment we identified a new water trap site formation in a silicon dioxide hard mask deposited on organic low-K film. The trapped water causes via poisoning of the organic low-K application in aluminum interconnections with tungsten electrodes. We showed that by inserting an out-gassing step and using a chemically formed film we can avoid this problem.