Heat, moisture and chemical resistance on low dielectric constant (low-k) film using Diethoxymethylsilane (DEMS) prepared by plasma enhanced chemical vapor deposition

Resistance of low dielectric constant (low-k) dielectrics, deposited using Diethoxymethylsilane (DEMS) precursor and helium (He) carrier gas with or without oxygen (O2) reaction gas, against heat, moisture stress and chemical treatment is clarified. The low dielectric constant organosilicate glass (OSG) films deposited using DEMS and O2 is shown to be the most reliable: the dielectric constant are stable even after a heating test at 700 °C and a pressure cooker test (PCT) for 168 h. This stability is high enough to ensure the low-k properties throughout fabricating multilevel interconnects and long-term reliability after the fabrication. This is due to the stability of Si–CH3 bonds and more Si–C–Si– bonds, which has high degree of cross-linking. However, the degradation of the dielectric constant occurs after O2 plasma ashing process. The nitrogen plasma treatment is proposed to prevent the damage from O2 attack in the low-k films deposited using DEMS precursor.