Water-Related Degradation of Aluminum Contacts Made Through Spin-On Silicon-Oxide-Based Dielectrics.

We investigated the effect on the performance of MOS integrated circuits of using silicon-dioxide-based spin-on glasses (SOG) as interlevel dielectrics. Sorbed water causes deterioration of aluminum contacts made in the presence of these SOG materials. Results from measurements on individual contacts indicated that in order to achieve low-resistance aluminum-to-aluminum contacts in submicron windows of spin-on materials, it is necessary to dry the exposed portions of the dielectric in the window. A polysilicate cannot be "dried" by heating at 450C, but the polysiloxane Accuglass 211 can be dried at this temperature by annealing for 3 minutes or longer. (However) via--chain yields were mixed, indicating that this process is not yet ready for manufacturing.) We observed that a polysilicate causes more transconductance degradation (G sub M ) of the MOS transistor than does a polysiloxane (9% versus 4%). The predictive power of the TVS technique suggests its use for screening dielectric materials that have potential water-related problems.