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

Abstract

Resistance of low dielectric constant (low-k) dielectrics, deposited using Diethoxymethylsilane (DEMS) precursor and helium (He) carrier gas with or without oxygen (O-2) reaction gas, against heat, moisture stress and chemical treatment is clarified. The low dielectric constant organosilicate glass (OSG) films deposited using DEMS and O-2 is shown to be the most reliable: the dielectric constant are stable even after a heating test at 700 degrees 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 O-2 plasma ashing process. The nitrogen plasma treatment is proposed to prevent the damage from O-2 attack in the low-k films deposited using DEMS precursor. (c) 2005 Elsevier B.V. All rights reserved.