Via failures due to water emission from SOG

Abstract

Via failures in multi-level metallization with the sandwich-type structure in which spin-on-glass (SOG) is sandwiched by SiO/sub 2/ films grown by plasma-enhanced chemical vapor deposition (P-SiO/sub 2/) have been studied. A poor via chain yield was obtained when the upper P-SiO/sub 2/ was deposited at a higher temperature than 260/spl deg/C. Water emission characteristics of the sandwich structure were measured. A new phenomenological model to explain the poisoned-via failure is proposed as follows. A thin water permeable P-SiO/sub 2/ layer may be formed on the boundary between SOG and the upper P-SiO/sub 2/. Water contained in SOG passes through this thin layer and is emitted into via holes during the subsequent metallization process. The moisture oxidizes the first metal surface and causes via open failures. Depositing the upper P-SiO/sub 2/ at a relatively low temperature of around 200/spl deg/C can suppress the failure and realize highly reliable vias in submicron scale.<>