Heat and Moisture Resistance of Siloxane-Based Low-Dielectric-Constant Materials

Resistance of siloxane-based, low-dielectric-constant (low- k ) dielectrics against heat and moisture stress is clarified. The organo-silica-glass (OSG) and the silicon-oxycarbide are shown to be the most reliable: the k -values are stable even after a heating test at 650°C and a pressure cooker treatment for 100 h. This stability is high enough to ensure the low- k property throughout fabricating multilevel interconnects and long-term reliability after the fabrication. This is shown to be due to the stability of bonds and bonds incorporated in the OSG and the silicon-oxycarbide. The stability of the OSG in real low- k interlevel dielectric structure was also demonstrated using four-level interconnect test devices. The low- k property still remains even after the reliability tests, showing that the low- k interlayer dielectric structure is sufficiently resistant to heat and moisture stresses.